src/share/vm/runtime/thread.cpp

Tue, 24 Jul 2012 10:51:00 -0700

author
twisti
date
Tue, 24 Jul 2012 10:51:00 -0700
changeset 3969
1d7922586cf6
parent 3901
24b9c7f4cae6
child 4037
da91efe96a93
permissions
-rw-r--r--

7023639: JSR 292 method handle invocation needs a fast path for compiled code
6984705: JSR 292 method handle creation should not go through JNI
Summary: remove assembly code for JDK 7 chained method handles
Reviewed-by: jrose, twisti, kvn, mhaupt
Contributed-by: John Rose <john.r.rose@oracle.com>, Christian Thalinger <christian.thalinger@oracle.com>, Michael Haupt <michael.haupt@oracle.com>

     1 /*
     2  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     4  *
     5  * This code is free software; you can redistribute it and/or modify it
     6  * under the terms of the GNU General Public License version 2 only, as
     7  * published by the Free Software Foundation.
     8  *
     9  * This code is distributed in the hope that it will be useful, but WITHOUT
    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    12  * version 2 for more details (a copy is included in the LICENSE file that
    13  * accompanied this code).
    14  *
    15  * You should have received a copy of the GNU General Public License version
    16  * 2 along with this work; if not, write to the Free Software Foundation,
    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    18  *
    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
    20  * or visit www.oracle.com if you need additional information or have any
    21  * questions.
    22  *
    23  */
    25 #include "precompiled.hpp"
    26 #include "classfile/classLoader.hpp"
    27 #include "classfile/javaClasses.hpp"
    28 #include "classfile/systemDictionary.hpp"
    29 #include "classfile/vmSymbols.hpp"
    30 #include "code/scopeDesc.hpp"
    31 #include "compiler/compileBroker.hpp"
    32 #include "interpreter/interpreter.hpp"
    33 #include "interpreter/linkResolver.hpp"
    34 #include "interpreter/oopMapCache.hpp"
    35 #include "jvmtifiles/jvmtiEnv.hpp"
    36 #include "memory/gcLocker.inline.hpp"
    37 #include "memory/oopFactory.hpp"
    38 #include "memory/universe.inline.hpp"
    39 #include "oops/instanceKlass.hpp"
    40 #include "oops/objArrayOop.hpp"
    41 #include "oops/oop.inline.hpp"
    42 #include "oops/symbol.hpp"
    43 #include "prims/jvm_misc.hpp"
    44 #include "prims/jvmtiExport.hpp"
    45 #include "prims/jvmtiThreadState.hpp"
    46 #include "prims/privilegedStack.hpp"
    47 #include "runtime/aprofiler.hpp"
    48 #include "runtime/arguments.hpp"
    49 #include "runtime/biasedLocking.hpp"
    50 #include "runtime/deoptimization.hpp"
    51 #include "runtime/fprofiler.hpp"
    52 #include "runtime/frame.inline.hpp"
    53 #include "runtime/init.hpp"
    54 #include "runtime/interfaceSupport.hpp"
    55 #include "runtime/java.hpp"
    56 #include "runtime/javaCalls.hpp"
    57 #include "runtime/jniPeriodicChecker.hpp"
    58 #include "runtime/memprofiler.hpp"
    59 #include "runtime/mutexLocker.hpp"
    60 #include "runtime/objectMonitor.hpp"
    61 #include "runtime/osThread.hpp"
    62 #include "runtime/safepoint.hpp"
    63 #include "runtime/sharedRuntime.hpp"
    64 #include "runtime/statSampler.hpp"
    65 #include "runtime/stubRoutines.hpp"
    66 #include "runtime/task.hpp"
    67 #include "runtime/threadCritical.hpp"
    68 #include "runtime/threadLocalStorage.hpp"
    69 #include "runtime/vframe.hpp"
    70 #include "runtime/vframeArray.hpp"
    71 #include "runtime/vframe_hp.hpp"
    72 #include "runtime/vmThread.hpp"
    73 #include "runtime/vm_operations.hpp"
    74 #include "services/attachListener.hpp"
    75 #include "services/management.hpp"
    76 #include "services/memTracker.hpp"
    77 #include "services/threadService.hpp"
    78 #include "trace/traceEventTypes.hpp"
    79 #include "utilities/defaultStream.hpp"
    80 #include "utilities/dtrace.hpp"
    81 #include "utilities/events.hpp"
    82 #include "utilities/preserveException.hpp"
    83 #ifdef TARGET_OS_FAMILY_linux
    84 # include "os_linux.inline.hpp"
    85 # include "thread_linux.inline.hpp"
    86 #endif
    87 #ifdef TARGET_OS_FAMILY_solaris
    88 # include "os_solaris.inline.hpp"
    89 # include "thread_solaris.inline.hpp"
    90 #endif
    91 #ifdef TARGET_OS_FAMILY_windows
    92 # include "os_windows.inline.hpp"
    93 # include "thread_windows.inline.hpp"
    94 #endif
    95 #ifdef TARGET_OS_FAMILY_bsd
    96 # include "os_bsd.inline.hpp"
    97 # include "thread_bsd.inline.hpp"
    98 #endif
    99 #ifndef SERIALGC
   100 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
   101 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
   102 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
   103 #endif
   104 #ifdef COMPILER1
   105 #include "c1/c1_Compiler.hpp"
   106 #endif
   107 #ifdef COMPILER2
   108 #include "opto/c2compiler.hpp"
   109 #include "opto/idealGraphPrinter.hpp"
   110 #endif
   112 #ifdef DTRACE_ENABLED
   114 // Only bother with this argument setup if dtrace is available
   116 #ifndef USDT2
   117 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
   118 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
   119 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
   120   intptr_t, intptr_t, bool);
   121 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
   122   intptr_t, intptr_t, bool);
   124 #define DTRACE_THREAD_PROBE(probe, javathread)                             \
   125   {                                                                        \
   126     ResourceMark rm(this);                                                 \
   127     int len = 0;                                                           \
   128     const char* name = (javathread)->get_thread_name();                    \
   129     len = strlen(name);                                                    \
   130     HS_DTRACE_PROBE5(hotspot, thread__##probe,                             \
   131       name, len,                                                           \
   132       java_lang_Thread::thread_id((javathread)->threadObj()),              \
   133       (javathread)->osthread()->thread_id(),                               \
   134       java_lang_Thread::is_daemon((javathread)->threadObj()));             \
   135   }
   137 #else /* USDT2 */
   139 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_PROBE_START
   140 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_PROBE_STOP
   142 #define DTRACE_THREAD_PROBE(probe, javathread)                             \
   143   {                                                                        \
   144     ResourceMark rm(this);                                                 \
   145     int len = 0;                                                           \
   146     const char* name = (javathread)->get_thread_name();                    \
   147     len = strlen(name);                                                    \
   148     HOTSPOT_THREAD_PROBE_##probe(  /* probe = start, stop */               \
   149       (char *) name, len,                                                           \
   150       java_lang_Thread::thread_id((javathread)->threadObj()),              \
   151       (uintptr_t) (javathread)->osthread()->thread_id(),                               \
   152       java_lang_Thread::is_daemon((javathread)->threadObj()));             \
   153   }
   155 #endif /* USDT2 */
   157 #else //  ndef DTRACE_ENABLED
   159 #define DTRACE_THREAD_PROBE(probe, javathread)
   161 #endif // ndef DTRACE_ENABLED
   164 // Class hierarchy
   165 // - Thread
   166 //   - VMThread
   167 //   - WatcherThread
   168 //   - ConcurrentMarkSweepThread
   169 //   - JavaThread
   170 //     - CompilerThread
   172 // ======= Thread ========
   173 // Support for forcing alignment of thread objects for biased locking
   174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
   175   if (UseBiasedLocking) {
   176     const int alignment = markOopDesc::biased_lock_alignment;
   177     size_t aligned_size = size + (alignment - sizeof(intptr_t));
   178     void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
   179                                           : os::malloc(aligned_size, flags, CURRENT_PC);
   180     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
   181     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
   182            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
   183            "JavaThread alignment code overflowed allocated storage");
   184     if (TraceBiasedLocking) {
   185       if (aligned_addr != real_malloc_addr)
   186         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
   187                       real_malloc_addr, aligned_addr);
   188     }
   189     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
   190     return aligned_addr;
   191   } else {
   192     return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
   193                        : os::malloc(size, flags, CURRENT_PC);
   194   }
   195 }
   197 void Thread::operator delete(void* p) {
   198   if (UseBiasedLocking) {
   199     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
   200     FreeHeap(real_malloc_addr, mtThread);
   201   } else {
   202     FreeHeap(p, mtThread);
   203   }
   204 }
   207 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
   208 // JavaThread
   211 Thread::Thread() {
   212   // stack and get_thread
   213   set_stack_base(NULL);
   214   set_stack_size(0);
   215   set_self_raw_id(0);
   216   set_lgrp_id(-1);
   218   // allocated data structures
   219   set_osthread(NULL);
   220   set_resource_area(new (mtThread)ResourceArea());
   221   set_handle_area(new (mtThread) HandleArea(NULL));
   222   set_active_handles(NULL);
   223   set_free_handle_block(NULL);
   224   set_last_handle_mark(NULL);
   226   // This initial value ==> never claimed.
   227   _oops_do_parity = 0;
   229   // the handle mark links itself to last_handle_mark
   230   new HandleMark(this);
   232   // plain initialization
   233   debug_only(_owned_locks = NULL;)
   234   debug_only(_allow_allocation_count = 0;)
   235   NOT_PRODUCT(_allow_safepoint_count = 0;)
   236   NOT_PRODUCT(_skip_gcalot = false;)
   237   CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
   238   _jvmti_env_iteration_count = 0;
   239   set_allocated_bytes(0);
   240   set_trace_buffer(NULL);
   241   _vm_operation_started_count = 0;
   242   _vm_operation_completed_count = 0;
   243   _current_pending_monitor = NULL;
   244   _current_pending_monitor_is_from_java = true;
   245   _current_waiting_monitor = NULL;
   246   _num_nested_signal = 0;
   247   omFreeList = NULL ;
   248   omFreeCount = 0 ;
   249   omFreeProvision = 32 ;
   250   omInUseList = NULL ;
   251   omInUseCount = 0 ;
   253 #ifdef ASSERT
   254   _visited_for_critical_count = false;
   255 #endif
   257   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
   258   _suspend_flags = 0;
   260   // thread-specific hashCode stream generator state - Marsaglia shift-xor form
   261   _hashStateX = os::random() ;
   262   _hashStateY = 842502087 ;
   263   _hashStateZ = 0x8767 ;    // (int)(3579807591LL & 0xffff) ;
   264   _hashStateW = 273326509 ;
   266   _OnTrap   = 0 ;
   267   _schedctl = NULL ;
   268   _Stalled  = 0 ;
   269   _TypeTag  = 0x2BAD ;
   271   // Many of the following fields are effectively final - immutable
   272   // Note that nascent threads can't use the Native Monitor-Mutex
   273   // construct until the _MutexEvent is initialized ...
   274   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
   275   // we might instead use a stack of ParkEvents that we could provision on-demand.
   276   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
   277   // and ::Release()
   278   _ParkEvent   = ParkEvent::Allocate (this) ;
   279   _SleepEvent  = ParkEvent::Allocate (this) ;
   280   _MutexEvent  = ParkEvent::Allocate (this) ;
   281   _MuxEvent    = ParkEvent::Allocate (this) ;
   283 #ifdef CHECK_UNHANDLED_OOPS
   284   if (CheckUnhandledOops) {
   285     _unhandled_oops = new UnhandledOops(this);
   286   }
   287 #endif // CHECK_UNHANDLED_OOPS
   288 #ifdef ASSERT
   289   if (UseBiasedLocking) {
   290     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
   291     assert(this == _real_malloc_address ||
   292            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
   293            "bug in forced alignment of thread objects");
   294   }
   295 #endif /* ASSERT */
   296 }
   298 void Thread::initialize_thread_local_storage() {
   299   // Note: Make sure this method only calls
   300   // non-blocking operations. Otherwise, it might not work
   301   // with the thread-startup/safepoint interaction.
   303   // During Java thread startup, safepoint code should allow this
   304   // method to complete because it may need to allocate memory to
   305   // store information for the new thread.
   307   // initialize structure dependent on thread local storage
   308   ThreadLocalStorage::set_thread(this);
   310   // set up any platform-specific state.
   311   os::initialize_thread();
   312 }
   314 void Thread::record_stack_base_and_size() {
   315   set_stack_base(os::current_stack_base());
   316   set_stack_size(os::current_stack_size());
   318   // record thread's native stack, stack grows downward
   319   address vm_base = _stack_base - _stack_size;
   320   MemTracker::record_virtual_memory_reserve(vm_base, _stack_size,
   321     CURRENT_PC, this);
   322   MemTracker::record_virtual_memory_type(vm_base, mtThreadStack);
   323 }
   326 Thread::~Thread() {
   327   // Reclaim the objectmonitors from the omFreeList of the moribund thread.
   328   ObjectSynchronizer::omFlush (this) ;
   330   MemTracker::record_virtual_memory_release((_stack_base - _stack_size),
   331     _stack_size, this);
   333   // deallocate data structures
   334   delete resource_area();
   335   // since the handle marks are using the handle area, we have to deallocated the root
   336   // handle mark before deallocating the thread's handle area,
   337   assert(last_handle_mark() != NULL, "check we have an element");
   338   delete last_handle_mark();
   339   assert(last_handle_mark() == NULL, "check we have reached the end");
   341   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
   342   // We NULL out the fields for good hygiene.
   343   ParkEvent::Release (_ParkEvent)   ; _ParkEvent   = NULL ;
   344   ParkEvent::Release (_SleepEvent)  ; _SleepEvent  = NULL ;
   345   ParkEvent::Release (_MutexEvent)  ; _MutexEvent  = NULL ;
   346   ParkEvent::Release (_MuxEvent)    ; _MuxEvent    = NULL ;
   348   delete handle_area();
   350   // osthread() can be NULL, if creation of thread failed.
   351   if (osthread() != NULL) os::free_thread(osthread());
   353   delete _SR_lock;
   355   // clear thread local storage if the Thread is deleting itself
   356   if (this == Thread::current()) {
   357     ThreadLocalStorage::set_thread(NULL);
   358   } else {
   359     // In the case where we're not the current thread, invalidate all the
   360     // caches in case some code tries to get the current thread or the
   361     // thread that was destroyed, and gets stale information.
   362     ThreadLocalStorage::invalidate_all();
   363   }
   364   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
   365 }
   367 // NOTE: dummy function for assertion purpose.
   368 void Thread::run() {
   369   ShouldNotReachHere();
   370 }
   372 #ifdef ASSERT
   373 // Private method to check for dangling thread pointer
   374 void check_for_dangling_thread_pointer(Thread *thread) {
   375  assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
   376          "possibility of dangling Thread pointer");
   377 }
   378 #endif
   381 #ifndef PRODUCT
   382 // Tracing method for basic thread operations
   383 void Thread::trace(const char* msg, const Thread* const thread) {
   384   if (!TraceThreadEvents) return;
   385   ResourceMark rm;
   386   ThreadCritical tc;
   387   const char *name = "non-Java thread";
   388   int prio = -1;
   389   if (thread->is_Java_thread()
   390       && !thread->is_Compiler_thread()) {
   391     // The Threads_lock must be held to get information about
   392     // this thread but may not be in some situations when
   393     // tracing  thread events.
   394     bool release_Threads_lock = false;
   395     if (!Threads_lock->owned_by_self()) {
   396       Threads_lock->lock();
   397       release_Threads_lock = true;
   398     }
   399     JavaThread* jt = (JavaThread *)thread;
   400     name = (char *)jt->get_thread_name();
   401     oop thread_oop = jt->threadObj();
   402     if (thread_oop != NULL) {
   403       prio = java_lang_Thread::priority(thread_oop);
   404     }
   405     if (release_Threads_lock) {
   406       Threads_lock->unlock();
   407     }
   408   }
   409   tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
   410 }
   411 #endif
   414 ThreadPriority Thread::get_priority(const Thread* const thread) {
   415   trace("get priority", thread);
   416   ThreadPriority priority;
   417   // Can return an error!
   418   (void)os::get_priority(thread, priority);
   419   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
   420   return priority;
   421 }
   423 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
   424   trace("set priority", thread);
   425   debug_only(check_for_dangling_thread_pointer(thread);)
   426   // Can return an error!
   427   (void)os::set_priority(thread, priority);
   428 }
   431 void Thread::start(Thread* thread) {
   432   trace("start", thread);
   433   // Start is different from resume in that its safety is guaranteed by context or
   434   // being called from a Java method synchronized on the Thread object.
   435   if (!DisableStartThread) {
   436     if (thread->is_Java_thread()) {
   437       // Initialize the thread state to RUNNABLE before starting this thread.
   438       // Can not set it after the thread started because we do not know the
   439       // exact thread state at that time. It could be in MONITOR_WAIT or
   440       // in SLEEPING or some other state.
   441       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
   442                                           java_lang_Thread::RUNNABLE);
   443     }
   444     os::start_thread(thread);
   445   }
   446 }
   448 // Enqueue a VM_Operation to do the job for us - sometime later
   449 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
   450   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
   451   VMThread::execute(vm_stop);
   452 }
   455 //
   456 // Check if an external suspend request has completed (or has been
   457 // cancelled). Returns true if the thread is externally suspended and
   458 // false otherwise.
   459 //
   460 // The bits parameter returns information about the code path through
   461 // the routine. Useful for debugging:
   462 //
   463 // set in is_ext_suspend_completed():
   464 // 0x00000001 - routine was entered
   465 // 0x00000010 - routine return false at end
   466 // 0x00000100 - thread exited (return false)
   467 // 0x00000200 - suspend request cancelled (return false)
   468 // 0x00000400 - thread suspended (return true)
   469 // 0x00001000 - thread is in a suspend equivalent state (return true)
   470 // 0x00002000 - thread is native and walkable (return true)
   471 // 0x00004000 - thread is native_trans and walkable (needed retry)
   472 //
   473 // set in wait_for_ext_suspend_completion():
   474 // 0x00010000 - routine was entered
   475 // 0x00020000 - suspend request cancelled before loop (return false)
   476 // 0x00040000 - thread suspended before loop (return true)
   477 // 0x00080000 - suspend request cancelled in loop (return false)
   478 // 0x00100000 - thread suspended in loop (return true)
   479 // 0x00200000 - suspend not completed during retry loop (return false)
   480 //
   482 // Helper class for tracing suspend wait debug bits.
   483 //
   484 // 0x00000100 indicates that the target thread exited before it could
   485 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
   486 // 0x00080000 each indicate a cancelled suspend request so they don't
   487 // count as wait failures either.
   488 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
   490 class TraceSuspendDebugBits : public StackObj {
   491  private:
   492   JavaThread * jt;
   493   bool         is_wait;
   494   bool         called_by_wait;  // meaningful when !is_wait
   495   uint32_t *   bits;
   497  public:
   498   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
   499                         uint32_t *_bits) {
   500     jt             = _jt;
   501     is_wait        = _is_wait;
   502     called_by_wait = _called_by_wait;
   503     bits           = _bits;
   504   }
   506   ~TraceSuspendDebugBits() {
   507     if (!is_wait) {
   508 #if 1
   509       // By default, don't trace bits for is_ext_suspend_completed() calls.
   510       // That trace is very chatty.
   511       return;
   512 #else
   513       if (!called_by_wait) {
   514         // If tracing for is_ext_suspend_completed() is enabled, then only
   515         // trace calls to it from wait_for_ext_suspend_completion()
   516         return;
   517       }
   518 #endif
   519     }
   521     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
   522       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
   523         MutexLocker ml(Threads_lock);  // needed for get_thread_name()
   524         ResourceMark rm;
   526         tty->print_cr(
   527             "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
   528             jt->get_thread_name(), *bits);
   530         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
   531       }
   532     }
   533   }
   534 };
   535 #undef DEBUG_FALSE_BITS
   538 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
   539   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
   541   bool did_trans_retry = false;  // only do thread_in_native_trans retry once
   542   bool do_trans_retry;           // flag to force the retry
   544   *bits |= 0x00000001;
   546   do {
   547     do_trans_retry = false;
   549     if (is_exiting()) {
   550       // Thread is in the process of exiting. This is always checked
   551       // first to reduce the risk of dereferencing a freed JavaThread.
   552       *bits |= 0x00000100;
   553       return false;
   554     }
   556     if (!is_external_suspend()) {
   557       // Suspend request is cancelled. This is always checked before
   558       // is_ext_suspended() to reduce the risk of a rogue resume
   559       // confusing the thread that made the suspend request.
   560       *bits |= 0x00000200;
   561       return false;
   562     }
   564     if (is_ext_suspended()) {
   565       // thread is suspended
   566       *bits |= 0x00000400;
   567       return true;
   568     }
   570     // Now that we no longer do hard suspends of threads running
   571     // native code, the target thread can be changing thread state
   572     // while we are in this routine:
   573     //
   574     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked
   575     //
   576     // We save a copy of the thread state as observed at this moment
   577     // and make our decision about suspend completeness based on the
   578     // copy. This closes the race where the thread state is seen as
   579     // _thread_in_native_trans in the if-thread_blocked check, but is
   580     // seen as _thread_blocked in if-thread_in_native_trans check.
   581     JavaThreadState save_state = thread_state();
   583     if (save_state == _thread_blocked && is_suspend_equivalent()) {
   584       // If the thread's state is _thread_blocked and this blocking
   585       // condition is known to be equivalent to a suspend, then we can
   586       // consider the thread to be externally suspended. This means that
   587       // the code that sets _thread_blocked has been modified to do
   588       // self-suspension if the blocking condition releases. We also
   589       // used to check for CONDVAR_WAIT here, but that is now covered by
   590       // the _thread_blocked with self-suspension check.
   591       //
   592       // Return true since we wouldn't be here unless there was still an
   593       // external suspend request.
   594       *bits |= 0x00001000;
   595       return true;
   596     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
   597       // Threads running native code will self-suspend on native==>VM/Java
   598       // transitions. If its stack is walkable (should always be the case
   599       // unless this function is called before the actual java_suspend()
   600       // call), then the wait is done.
   601       *bits |= 0x00002000;
   602       return true;
   603     } else if (!called_by_wait && !did_trans_retry &&
   604                save_state == _thread_in_native_trans &&
   605                frame_anchor()->walkable()) {
   606       // The thread is transitioning from thread_in_native to another
   607       // thread state. check_safepoint_and_suspend_for_native_trans()
   608       // will force the thread to self-suspend. If it hasn't gotten
   609       // there yet we may have caught the thread in-between the native
   610       // code check above and the self-suspend. Lucky us. If we were
   611       // called by wait_for_ext_suspend_completion(), then it
   612       // will be doing the retries so we don't have to.
   613       //
   614       // Since we use the saved thread state in the if-statement above,
   615       // there is a chance that the thread has already transitioned to
   616       // _thread_blocked by the time we get here. In that case, we will
   617       // make a single unnecessary pass through the logic below. This
   618       // doesn't hurt anything since we still do the trans retry.
   620       *bits |= 0x00004000;
   622       // Once the thread leaves thread_in_native_trans for another
   623       // thread state, we break out of this retry loop. We shouldn't
   624       // need this flag to prevent us from getting back here, but
   625       // sometimes paranoia is good.
   626       did_trans_retry = true;
   628       // We wait for the thread to transition to a more usable state.
   629       for (int i = 1; i <= SuspendRetryCount; i++) {
   630         // We used to do an "os::yield_all(i)" call here with the intention
   631         // that yielding would increase on each retry. However, the parameter
   632         // is ignored on Linux which means the yield didn't scale up. Waiting
   633         // on the SR_lock below provides a much more predictable scale up for
   634         // the delay. It also provides a simple/direct point to check for any
   635         // safepoint requests from the VMThread
   637         // temporarily drops SR_lock while doing wait with safepoint check
   638         // (if we're a JavaThread - the WatcherThread can also call this)
   639         // and increase delay with each retry
   640         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
   642         // check the actual thread state instead of what we saved above
   643         if (thread_state() != _thread_in_native_trans) {
   644           // the thread has transitioned to another thread state so
   645           // try all the checks (except this one) one more time.
   646           do_trans_retry = true;
   647           break;
   648         }
   649       } // end retry loop
   652     }
   653   } while (do_trans_retry);
   655   *bits |= 0x00000010;
   656   return false;
   657 }
   659 //
   660 // Wait for an external suspend request to complete (or be cancelled).
   661 // Returns true if the thread is externally suspended and false otherwise.
   662 //
   663 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
   664        uint32_t *bits) {
   665   TraceSuspendDebugBits tsdb(this, true /* is_wait */,
   666                              false /* !called_by_wait */, bits);
   668   // local flag copies to minimize SR_lock hold time
   669   bool is_suspended;
   670   bool pending;
   671   uint32_t reset_bits;
   673   // set a marker so is_ext_suspend_completed() knows we are the caller
   674   *bits |= 0x00010000;
   676   // We use reset_bits to reinitialize the bits value at the top of
   677   // each retry loop. This allows the caller to make use of any
   678   // unused bits for their own marking purposes.
   679   reset_bits = *bits;
   681   {
   682     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
   683     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
   684                                             delay, bits);
   685     pending = is_external_suspend();
   686   }
   687   // must release SR_lock to allow suspension to complete
   689   if (!pending) {
   690     // A cancelled suspend request is the only false return from
   691     // is_ext_suspend_completed() that keeps us from entering the
   692     // retry loop.
   693     *bits |= 0x00020000;
   694     return false;
   695   }
   697   if (is_suspended) {
   698     *bits |= 0x00040000;
   699     return true;
   700   }
   702   for (int i = 1; i <= retries; i++) {
   703     *bits = reset_bits;  // reinit to only track last retry
   705     // We used to do an "os::yield_all(i)" call here with the intention
   706     // that yielding would increase on each retry. However, the parameter
   707     // is ignored on Linux which means the yield didn't scale up. Waiting
   708     // on the SR_lock below provides a much more predictable scale up for
   709     // the delay. It also provides a simple/direct point to check for any
   710     // safepoint requests from the VMThread
   712     {
   713       MutexLocker ml(SR_lock());
   714       // wait with safepoint check (if we're a JavaThread - the WatcherThread
   715       // can also call this)  and increase delay with each retry
   716       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
   718       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
   719                                               delay, bits);
   721       // It is possible for the external suspend request to be cancelled
   722       // (by a resume) before the actual suspend operation is completed.
   723       // Refresh our local copy to see if we still need to wait.
   724       pending = is_external_suspend();
   725     }
   727     if (!pending) {
   728       // A cancelled suspend request is the only false return from
   729       // is_ext_suspend_completed() that keeps us from staying in the
   730       // retry loop.
   731       *bits |= 0x00080000;
   732       return false;
   733     }
   735     if (is_suspended) {
   736       *bits |= 0x00100000;
   737       return true;
   738     }
   739   } // end retry loop
   741   // thread did not suspend after all our retries
   742   *bits |= 0x00200000;
   743   return false;
   744 }
   746 #ifndef PRODUCT
   747 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
   749   // This should not need to be atomic as the only way for simultaneous
   750   // updates is via interrupts. Even then this should be rare or non-existant
   751   // and we don't care that much anyway.
   753   int index = _jmp_ring_index;
   754   _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
   755   _jmp_ring[index]._target = (intptr_t) target;
   756   _jmp_ring[index]._instruction = (intptr_t) instr;
   757   _jmp_ring[index]._file = file;
   758   _jmp_ring[index]._line = line;
   759 }
   760 #endif /* PRODUCT */
   762 // Called by flat profiler
   763 // Callers have already called wait_for_ext_suspend_completion
   764 // The assertion for that is currently too complex to put here:
   765 bool JavaThread::profile_last_Java_frame(frame* _fr) {
   766   bool gotframe = false;
   767   // self suspension saves needed state.
   768   if (has_last_Java_frame() && _anchor.walkable()) {
   769      *_fr = pd_last_frame();
   770      gotframe = true;
   771   }
   772   return gotframe;
   773 }
   775 void Thread::interrupt(Thread* thread) {
   776   trace("interrupt", thread);
   777   debug_only(check_for_dangling_thread_pointer(thread);)
   778   os::interrupt(thread);
   779 }
   781 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
   782   trace("is_interrupted", thread);
   783   debug_only(check_for_dangling_thread_pointer(thread);)
   784   // Note:  If clear_interrupted==false, this simply fetches and
   785   // returns the value of the field osthread()->interrupted().
   786   return os::is_interrupted(thread, clear_interrupted);
   787 }
   790 // GC Support
   791 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
   792   jint thread_parity = _oops_do_parity;
   793   if (thread_parity != strong_roots_parity) {
   794     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
   795     if (res == thread_parity) {
   796       return true;
   797     } else {
   798       guarantee(res == strong_roots_parity, "Or else what?");
   799       assert(SharedHeap::heap()->workers()->active_workers() > 0,
   800          "Should only fail when parallel.");
   801       return false;
   802     }
   803   }
   804   assert(SharedHeap::heap()->workers()->active_workers() > 0,
   805          "Should only fail when parallel.");
   806   return false;
   807 }
   809 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
   810   active_handles()->oops_do(f);
   811   // Do oop for ThreadShadow
   812   f->do_oop((oop*)&_pending_exception);
   813   handle_area()->oops_do(f);
   814 }
   816 void Thread::nmethods_do(CodeBlobClosure* cf) {
   817   // no nmethods in a generic thread...
   818 }
   820 void Thread::print_on(outputStream* st) const {
   821   // get_priority assumes osthread initialized
   822   if (osthread() != NULL) {
   823     st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
   824     osthread()->print_on(st);
   825   }
   826   debug_only(if (WizardMode) print_owned_locks_on(st);)
   827 }
   829 // Thread::print_on_error() is called by fatal error handler. Don't use
   830 // any lock or allocate memory.
   831 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
   832   if      (is_VM_thread())                  st->print("VMThread");
   833   else if (is_Compiler_thread())            st->print("CompilerThread");
   834   else if (is_Java_thread())                st->print("JavaThread");
   835   else if (is_GC_task_thread())             st->print("GCTaskThread");
   836   else if (is_Watcher_thread())             st->print("WatcherThread");
   837   else if (is_ConcurrentGC_thread())        st->print("ConcurrentGCThread");
   838   else st->print("Thread");
   840   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
   841             _stack_base - _stack_size, _stack_base);
   843   if (osthread()) {
   844     st->print(" [id=%d]", osthread()->thread_id());
   845   }
   846 }
   848 #ifdef ASSERT
   849 void Thread::print_owned_locks_on(outputStream* st) const {
   850   Monitor *cur = _owned_locks;
   851   if (cur == NULL) {
   852     st->print(" (no locks) ");
   853   } else {
   854     st->print_cr(" Locks owned:");
   855     while(cur) {
   856       cur->print_on(st);
   857       cur = cur->next();
   858     }
   859   }
   860 }
   862 static int ref_use_count  = 0;
   864 bool Thread::owns_locks_but_compiled_lock() const {
   865   for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
   866     if (cur != Compile_lock) return true;
   867   }
   868   return false;
   869 }
   872 #endif
   874 #ifndef PRODUCT
   876 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
   877 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
   878 // no threads which allow_vm_block's are held
   879 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
   880     // Check if current thread is allowed to block at a safepoint
   881     if (!(_allow_safepoint_count == 0))
   882       fatal("Possible safepoint reached by thread that does not allow it");
   883     if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
   884       fatal("LEAF method calling lock?");
   885     }
   887 #ifdef ASSERT
   888     if (potential_vm_operation && is_Java_thread()
   889         && !Universe::is_bootstrapping()) {
   890       // Make sure we do not hold any locks that the VM thread also uses.
   891       // This could potentially lead to deadlocks
   892       for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
   893         // Threads_lock is special, since the safepoint synchronization will not start before this is
   894         // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
   895         // since it is used to transfer control between JavaThreads and the VMThread
   896         // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
   897         if ( (cur->allow_vm_block() &&
   898               cur != Threads_lock &&
   899               cur != Compile_lock &&               // Temporary: should not be necessary when we get spearate compilation
   900               cur != VMOperationRequest_lock &&
   901               cur != VMOperationQueue_lock) ||
   902               cur->rank() == Mutex::special) {
   903           warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
   904         }
   905       }
   906     }
   908     if (GCALotAtAllSafepoints) {
   909       // We could enter a safepoint here and thus have a gc
   910       InterfaceSupport::check_gc_alot();
   911     }
   912 #endif
   913 }
   914 #endif
   916 bool Thread::is_in_stack(address adr) const {
   917   assert(Thread::current() == this, "is_in_stack can only be called from current thread");
   918   address end = os::current_stack_pointer();
   919   if (stack_base() >= adr && adr >= end) return true;
   921   return false;
   922 }
   925 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
   926 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
   927 // used for compilation in the future. If that change is made, the need for these methods
   928 // should be revisited, and they should be removed if possible.
   930 bool Thread::is_lock_owned(address adr) const {
   931   return on_local_stack(adr);
   932 }
   934 bool Thread::set_as_starting_thread() {
   935  // NOTE: this must be called inside the main thread.
   936   return os::create_main_thread((JavaThread*)this);
   937 }
   939 static void initialize_class(Symbol* class_name, TRAPS) {
   940   klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
   941   instanceKlass::cast(klass)->initialize(CHECK);
   942 }
   945 // Creates the initial ThreadGroup
   946 static Handle create_initial_thread_group(TRAPS) {
   947   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
   948   instanceKlassHandle klass (THREAD, k);
   950   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
   951   {
   952     JavaValue result(T_VOID);
   953     JavaCalls::call_special(&result,
   954                             system_instance,
   955                             klass,
   956                             vmSymbols::object_initializer_name(),
   957                             vmSymbols::void_method_signature(),
   958                             CHECK_NH);
   959   }
   960   Universe::set_system_thread_group(system_instance());
   962   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
   963   {
   964     JavaValue result(T_VOID);
   965     Handle string = java_lang_String::create_from_str("main", CHECK_NH);
   966     JavaCalls::call_special(&result,
   967                             main_instance,
   968                             klass,
   969                             vmSymbols::object_initializer_name(),
   970                             vmSymbols::threadgroup_string_void_signature(),
   971                             system_instance,
   972                             string,
   973                             CHECK_NH);
   974   }
   975   return main_instance;
   976 }
   978 // Creates the initial Thread
   979 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
   980   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
   981   instanceKlassHandle klass (THREAD, k);
   982   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
   984   java_lang_Thread::set_thread(thread_oop(), thread);
   985   java_lang_Thread::set_priority(thread_oop(), NormPriority);
   986   thread->set_threadObj(thread_oop());
   988   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
   990   JavaValue result(T_VOID);
   991   JavaCalls::call_special(&result, thread_oop,
   992                                    klass,
   993                                    vmSymbols::object_initializer_name(),
   994                                    vmSymbols::threadgroup_string_void_signature(),
   995                                    thread_group,
   996                                    string,
   997                                    CHECK_NULL);
   998   return thread_oop();
   999 }
  1001 static void call_initializeSystemClass(TRAPS) {
  1002   klassOop k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
  1003   instanceKlassHandle klass (THREAD, k);
  1005   JavaValue result(T_VOID);
  1006   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
  1007                                          vmSymbols::void_method_signature(), CHECK);
  1010 char java_runtime_name[128] = "";
  1012 // extract the JRE name from sun.misc.Version.java_runtime_name
  1013 static const char* get_java_runtime_name(TRAPS) {
  1014   klassOop k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
  1015                                       Handle(), Handle(), CHECK_AND_CLEAR_NULL);
  1016   fieldDescriptor fd;
  1017   bool found = k != NULL &&
  1018                instanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
  1019                                                         vmSymbols::string_signature(), &fd);
  1020   if (found) {
  1021     oop name_oop = k->java_mirror()->obj_field(fd.offset());
  1022     if (name_oop == NULL)
  1023       return NULL;
  1024     const char* name = java_lang_String::as_utf8_string(name_oop,
  1025                                                         java_runtime_name,
  1026                                                         sizeof(java_runtime_name));
  1027     return name;
  1028   } else {
  1029     return NULL;
  1033 // General purpose hook into Java code, run once when the VM is initialized.
  1034 // The Java library method itself may be changed independently from the VM.
  1035 static void call_postVMInitHook(TRAPS) {
  1036   klassOop k = SystemDictionary::PostVMInitHook_klass();
  1037   instanceKlassHandle klass (THREAD, k);
  1038   if (klass.not_null()) {
  1039     JavaValue result(T_VOID);
  1040     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
  1041                                            vmSymbols::void_method_signature(),
  1042                                            CHECK);
  1046 static void reset_vm_info_property(TRAPS) {
  1047   // the vm info string
  1048   ResourceMark rm(THREAD);
  1049   const char *vm_info = VM_Version::vm_info_string();
  1051   // java.lang.System class
  1052   klassOop k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
  1053   instanceKlassHandle klass (THREAD, k);
  1055   // setProperty arguments
  1056   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);
  1057   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);
  1059   // return value
  1060   JavaValue r(T_OBJECT);
  1062   // public static String setProperty(String key, String value);
  1063   JavaCalls::call_static(&r,
  1064                          klass,
  1065                          vmSymbols::setProperty_name(),
  1066                          vmSymbols::string_string_string_signature(),
  1067                          key_str,
  1068                          value_str,
  1069                          CHECK);
  1073 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
  1074   assert(thread_group.not_null(), "thread group should be specified");
  1075   assert(threadObj() == NULL, "should only create Java thread object once");
  1077   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
  1078   instanceKlassHandle klass (THREAD, k);
  1079   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
  1081   java_lang_Thread::set_thread(thread_oop(), this);
  1082   java_lang_Thread::set_priority(thread_oop(), NormPriority);
  1083   set_threadObj(thread_oop());
  1085   JavaValue result(T_VOID);
  1086   if (thread_name != NULL) {
  1087     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
  1088     // Thread gets assigned specified name and null target
  1089     JavaCalls::call_special(&result,
  1090                             thread_oop,
  1091                             klass,
  1092                             vmSymbols::object_initializer_name(),
  1093                             vmSymbols::threadgroup_string_void_signature(),
  1094                             thread_group, // Argument 1
  1095                             name,         // Argument 2
  1096                             THREAD);
  1097   } else {
  1098     // Thread gets assigned name "Thread-nnn" and null target
  1099     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
  1100     JavaCalls::call_special(&result,
  1101                             thread_oop,
  1102                             klass,
  1103                             vmSymbols::object_initializer_name(),
  1104                             vmSymbols::threadgroup_runnable_void_signature(),
  1105                             thread_group, // Argument 1
  1106                             Handle(),     // Argument 2
  1107                             THREAD);
  1111   if (daemon) {
  1112       java_lang_Thread::set_daemon(thread_oop());
  1115   if (HAS_PENDING_EXCEPTION) {
  1116     return;
  1119   KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
  1120   Handle threadObj(this, this->threadObj());
  1122   JavaCalls::call_special(&result,
  1123                          thread_group,
  1124                          group,
  1125                          vmSymbols::add_method_name(),
  1126                          vmSymbols::thread_void_signature(),
  1127                          threadObj,          // Arg 1
  1128                          THREAD);
  1133 // NamedThread --  non-JavaThread subclasses with multiple
  1134 // uniquely named instances should derive from this.
  1135 NamedThread::NamedThread() : Thread() {
  1136   _name = NULL;
  1137   _processed_thread = NULL;
  1140 NamedThread::~NamedThread() {
  1141   if (_name != NULL) {
  1142     FREE_C_HEAP_ARRAY(char, _name, mtThread);
  1143     _name = NULL;
  1147 void NamedThread::set_name(const char* format, ...) {
  1148   guarantee(_name == NULL, "Only get to set name once.");
  1149   _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
  1150   guarantee(_name != NULL, "alloc failure");
  1151   va_list ap;
  1152   va_start(ap, format);
  1153   jio_vsnprintf(_name, max_name_len, format, ap);
  1154   va_end(ap);
  1157 // ======= WatcherThread ========
  1159 // The watcher thread exists to simulate timer interrupts.  It should
  1160 // be replaced by an abstraction over whatever native support for
  1161 // timer interrupts exists on the platform.
  1163 WatcherThread* WatcherThread::_watcher_thread   = NULL;
  1164 volatile bool  WatcherThread::_should_terminate = false;
  1166 WatcherThread::WatcherThread() : Thread() {
  1167   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
  1168   if (os::create_thread(this, os::watcher_thread)) {
  1169     _watcher_thread = this;
  1171     // Set the watcher thread to the highest OS priority which should not be
  1172     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
  1173     // is created. The only normal thread using this priority is the reference
  1174     // handler thread, which runs for very short intervals only.
  1175     // If the VMThread's priority is not lower than the WatcherThread profiling
  1176     // will be inaccurate.
  1177     os::set_priority(this, MaxPriority);
  1178     if (!DisableStartThread) {
  1179       os::start_thread(this);
  1184 void WatcherThread::run() {
  1185   assert(this == watcher_thread(), "just checking");
  1187   this->record_stack_base_and_size();
  1188   this->initialize_thread_local_storage();
  1189   this->set_active_handles(JNIHandleBlock::allocate_block());
  1190   while(!_should_terminate) {
  1191     assert(watcher_thread() == Thread::current(),  "thread consistency check");
  1192     assert(watcher_thread() == this,  "thread consistency check");
  1194     // Calculate how long it'll be until the next PeriodicTask work
  1195     // should be done, and sleep that amount of time.
  1196     size_t time_to_wait = PeriodicTask::time_to_wait();
  1198     // we expect this to timeout - we only ever get unparked when
  1199     // we should terminate
  1201       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
  1203       jlong prev_time = os::javaTimeNanos();
  1204       for (;;) {
  1205         int res= _SleepEvent->park(time_to_wait);
  1206         if (res == OS_TIMEOUT || _should_terminate)
  1207           break;
  1208         // spurious wakeup of some kind
  1209         jlong now = os::javaTimeNanos();
  1210         time_to_wait -= (now - prev_time) / 1000000;
  1211         if (time_to_wait <= 0)
  1212           break;
  1213         prev_time = now;
  1217     if (is_error_reported()) {
  1218       // A fatal error has happened, the error handler(VMError::report_and_die)
  1219       // should abort JVM after creating an error log file. However in some
  1220       // rare cases, the error handler itself might deadlock. Here we try to
  1221       // kill JVM if the fatal error handler fails to abort in 2 minutes.
  1222       //
  1223       // This code is in WatcherThread because WatcherThread wakes up
  1224       // periodically so the fatal error handler doesn't need to do anything;
  1225       // also because the WatcherThread is less likely to crash than other
  1226       // threads.
  1228       for (;;) {
  1229         if (!ShowMessageBoxOnError
  1230          && (OnError == NULL || OnError[0] == '\0')
  1231          && Arguments::abort_hook() == NULL) {
  1232              os::sleep(this, 2 * 60 * 1000, false);
  1233              fdStream err(defaultStream::output_fd());
  1234              err.print_raw_cr("# [ timer expired, abort... ]");
  1235              // skip atexit/vm_exit/vm_abort hooks
  1236              os::die();
  1239         // Wake up 5 seconds later, the fatal handler may reset OnError or
  1240         // ShowMessageBoxOnError when it is ready to abort.
  1241         os::sleep(this, 5 * 1000, false);
  1245     PeriodicTask::real_time_tick(time_to_wait);
  1247     // If we have no more tasks left due to dynamic disenrollment,
  1248     // shut down the thread since we don't currently support dynamic enrollment
  1249     if (PeriodicTask::num_tasks() == 0) {
  1250       _should_terminate = true;
  1254   // Signal that it is terminated
  1256     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
  1257     _watcher_thread = NULL;
  1258     Terminator_lock->notify();
  1261   // Thread destructor usually does this..
  1262   ThreadLocalStorage::set_thread(NULL);
  1265 void WatcherThread::start() {
  1266   if (watcher_thread() == NULL) {
  1267     _should_terminate = false;
  1268     // Create the single instance of WatcherThread
  1269     new WatcherThread();
  1273 void WatcherThread::stop() {
  1274   // it is ok to take late safepoints here, if needed
  1275   MutexLocker mu(Terminator_lock);
  1276   _should_terminate = true;
  1277   OrderAccess::fence();  // ensure WatcherThread sees update in main loop
  1279   Thread* watcher = watcher_thread();
  1280   if (watcher != NULL)
  1281     watcher->_SleepEvent->unpark();
  1283   while(watcher_thread() != NULL) {
  1284     // This wait should make safepoint checks, wait without a timeout,
  1285     // and wait as a suspend-equivalent condition.
  1286     //
  1287     // Note: If the FlatProfiler is running, then this thread is waiting
  1288     // for the WatcherThread to terminate and the WatcherThread, via the
  1289     // FlatProfiler task, is waiting for the external suspend request on
  1290     // this thread to complete. wait_for_ext_suspend_completion() will
  1291     // eventually timeout, but that takes time. Making this wait a
  1292     // suspend-equivalent condition solves that timeout problem.
  1293     //
  1294     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
  1295                           Mutex::_as_suspend_equivalent_flag);
  1299 void WatcherThread::print_on(outputStream* st) const {
  1300   st->print("\"%s\" ", name());
  1301   Thread::print_on(st);
  1302   st->cr();
  1305 // ======= JavaThread ========
  1307 // A JavaThread is a normal Java thread
  1309 void JavaThread::initialize() {
  1310   // Initialize fields
  1312   // Set the claimed par_id to -1 (ie not claiming any par_ids)
  1313   set_claimed_par_id(-1);
  1315   set_saved_exception_pc(NULL);
  1316   set_threadObj(NULL);
  1317   _anchor.clear();
  1318   set_entry_point(NULL);
  1319   set_jni_functions(jni_functions());
  1320   set_callee_target(NULL);
  1321   set_vm_result(NULL);
  1322   set_vm_result_2(NULL);
  1323   set_vframe_array_head(NULL);
  1324   set_vframe_array_last(NULL);
  1325   set_deferred_locals(NULL);
  1326   set_deopt_mark(NULL);
  1327   set_deopt_nmethod(NULL);
  1328   clear_must_deopt_id();
  1329   set_monitor_chunks(NULL);
  1330   set_next(NULL);
  1331   set_thread_state(_thread_new);
  1332   set_recorder(NULL);
  1333   _terminated = _not_terminated;
  1334   _privileged_stack_top = NULL;
  1335   _array_for_gc = NULL;
  1336   _suspend_equivalent = false;
  1337   _in_deopt_handler = 0;
  1338   _doing_unsafe_access = false;
  1339   _stack_guard_state = stack_guard_unused;
  1340   _exception_oop = NULL;
  1341   _exception_pc  = 0;
  1342   _exception_handler_pc = 0;
  1343   _is_method_handle_return = 0;
  1344   _jvmti_thread_state= NULL;
  1345   _should_post_on_exceptions_flag = JNI_FALSE;
  1346   _jvmti_get_loaded_classes_closure = NULL;
  1347   _interp_only_mode    = 0;
  1348   _special_runtime_exit_condition = _no_async_condition;
  1349   _pending_async_exception = NULL;
  1350   _is_compiling = false;
  1351   _thread_stat = NULL;
  1352   _thread_stat = new ThreadStatistics();
  1353   _blocked_on_compilation = false;
  1354   _jni_active_critical = 0;
  1355   _do_not_unlock_if_synchronized = false;
  1356   _cached_monitor_info = NULL;
  1357   _parker = Parker::Allocate(this) ;
  1359 #ifndef PRODUCT
  1360   _jmp_ring_index = 0;
  1361   for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
  1362     record_jump(NULL, NULL, NULL, 0);
  1364 #endif /* PRODUCT */
  1366   set_thread_profiler(NULL);
  1367   if (FlatProfiler::is_active()) {
  1368     // This is where we would decide to either give each thread it's own profiler
  1369     // or use one global one from FlatProfiler,
  1370     // or up to some count of the number of profiled threads, etc.
  1371     ThreadProfiler* pp = new ThreadProfiler();
  1372     pp->engage();
  1373     set_thread_profiler(pp);
  1376   // Setup safepoint state info for this thread
  1377   ThreadSafepointState::create(this);
  1379   debug_only(_java_call_counter = 0);
  1381   // JVMTI PopFrame support
  1382   _popframe_condition = popframe_inactive;
  1383   _popframe_preserved_args = NULL;
  1384   _popframe_preserved_args_size = 0;
  1386   pd_initialize();
  1389 #ifndef SERIALGC
  1390 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
  1391 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
  1392 #endif // !SERIALGC
  1394 JavaThread::JavaThread(bool is_attaching_via_jni) :
  1395   Thread()
  1396 #ifndef SERIALGC
  1397   , _satb_mark_queue(&_satb_mark_queue_set),
  1398   _dirty_card_queue(&_dirty_card_queue_set)
  1399 #endif // !SERIALGC
  1401   initialize();
  1402   if (is_attaching_via_jni) {
  1403     _jni_attach_state = _attaching_via_jni;
  1404   } else {
  1405     _jni_attach_state = _not_attaching_via_jni;
  1407   assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
  1408   _safepoint_visible = false;
  1411 bool JavaThread::reguard_stack(address cur_sp) {
  1412   if (_stack_guard_state != stack_guard_yellow_disabled) {
  1413     return true; // Stack already guarded or guard pages not needed.
  1416   if (register_stack_overflow()) {
  1417     // For those architectures which have separate register and
  1418     // memory stacks, we must check the register stack to see if
  1419     // it has overflowed.
  1420     return false;
  1423   // Java code never executes within the yellow zone: the latter is only
  1424   // there to provoke an exception during stack banging.  If java code
  1425   // is executing there, either StackShadowPages should be larger, or
  1426   // some exception code in c1, c2 or the interpreter isn't unwinding
  1427   // when it should.
  1428   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
  1430   enable_stack_yellow_zone();
  1431   return true;
  1434 bool JavaThread::reguard_stack(void) {
  1435   return reguard_stack(os::current_stack_pointer());
  1439 void JavaThread::block_if_vm_exited() {
  1440   if (_terminated == _vm_exited) {
  1441     // _vm_exited is set at safepoint, and Threads_lock is never released
  1442     // we will block here forever
  1443     Threads_lock->lock_without_safepoint_check();
  1444     ShouldNotReachHere();
  1449 // Remove this ifdef when C1 is ported to the compiler interface.
  1450 static void compiler_thread_entry(JavaThread* thread, TRAPS);
  1452 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
  1453   Thread()
  1454 #ifndef SERIALGC
  1455   , _satb_mark_queue(&_satb_mark_queue_set),
  1456   _dirty_card_queue(&_dirty_card_queue_set)
  1457 #endif // !SERIALGC
  1459   if (TraceThreadEvents) {
  1460     tty->print_cr("creating thread %p", this);
  1462   initialize();
  1463   _jni_attach_state = _not_attaching_via_jni;
  1464   set_entry_point(entry_point);
  1465   // Create the native thread itself.
  1466   // %note runtime_23
  1467   os::ThreadType thr_type = os::java_thread;
  1468   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
  1469                                                      os::java_thread;
  1470   os::create_thread(this, thr_type, stack_sz);
  1471   _safepoint_visible = false;
  1472   // The _osthread may be NULL here because we ran out of memory (too many threads active).
  1473   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
  1474   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
  1475   // the exception consists of creating the exception object & initializing it, initialization
  1476   // will leave the VM via a JavaCall and then all locks must be unlocked).
  1477   //
  1478   // The thread is still suspended when we reach here. Thread must be explicit started
  1479   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
  1480   // by calling Threads:add. The reason why this is not done here, is because the thread
  1481   // object must be fully initialized (take a look at JVM_Start)
  1484 JavaThread::~JavaThread() {
  1485   if (TraceThreadEvents) {
  1486       tty->print_cr("terminate thread %p", this);
  1489   // Info NMT that this JavaThread is exiting, its memory
  1490   // recorder should be collected
  1491   assert(!is_safepoint_visible(), "wrong state");
  1492   MemTracker::thread_exiting(this);
  1494   // JSR166 -- return the parker to the free list
  1495   Parker::Release(_parker);
  1496   _parker = NULL ;
  1498   // Free any remaining  previous UnrollBlock
  1499   vframeArray* old_array = vframe_array_last();
  1501   if (old_array != NULL) {
  1502     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
  1503     old_array->set_unroll_block(NULL);
  1504     delete old_info;
  1505     delete old_array;
  1508   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
  1509   if (deferred != NULL) {
  1510     // This can only happen if thread is destroyed before deoptimization occurs.
  1511     assert(deferred->length() != 0, "empty array!");
  1512     do {
  1513       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
  1514       deferred->remove_at(0);
  1515       // individual jvmtiDeferredLocalVariableSet are CHeapObj's
  1516       delete dlv;
  1517     } while (deferred->length() != 0);
  1518     delete deferred;
  1521   // All Java related clean up happens in exit
  1522   ThreadSafepointState::destroy(this);
  1523   if (_thread_profiler != NULL) delete _thread_profiler;
  1524   if (_thread_stat != NULL) delete _thread_stat;
  1528 // The first routine called by a new Java thread
  1529 void JavaThread::run() {
  1530   // initialize thread-local alloc buffer related fields
  1531   this->initialize_tlab();
  1533   // used to test validitity of stack trace backs
  1534   this->record_base_of_stack_pointer();
  1536   // Record real stack base and size.
  1537   this->record_stack_base_and_size();
  1539   // Initialize thread local storage; set before calling MutexLocker
  1540   this->initialize_thread_local_storage();
  1542   this->create_stack_guard_pages();
  1544   this->cache_global_variables();
  1546   // Thread is now sufficient initialized to be handled by the safepoint code as being
  1547   // in the VM. Change thread state from _thread_new to _thread_in_vm
  1548   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
  1550   assert(JavaThread::current() == this, "sanity check");
  1551   assert(!Thread::current()->owns_locks(), "sanity check");
  1553   DTRACE_THREAD_PROBE(start, this);
  1555   // This operation might block. We call that after all safepoint checks for a new thread has
  1556   // been completed.
  1557   this->set_active_handles(JNIHandleBlock::allocate_block());
  1559   if (JvmtiExport::should_post_thread_life()) {
  1560     JvmtiExport::post_thread_start(this);
  1563   EVENT_BEGIN(TraceEventThreadStart, event);
  1564   EVENT_COMMIT(event,
  1565      EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
  1567   // We call another function to do the rest so we are sure that the stack addresses used
  1568   // from there will be lower than the stack base just computed
  1569   thread_main_inner();
  1571   // Note, thread is no longer valid at this point!
  1575 void JavaThread::thread_main_inner() {
  1576   assert(JavaThread::current() == this, "sanity check");
  1577   assert(this->threadObj() != NULL, "just checking");
  1579   // Execute thread entry point unless this thread has a pending exception
  1580   // or has been stopped before starting.
  1581   // Note: Due to JVM_StopThread we can have pending exceptions already!
  1582   if (!this->has_pending_exception() &&
  1583       !java_lang_Thread::is_stillborn(this->threadObj())) {
  1585       ResourceMark rm(this);
  1586       this->set_native_thread_name(this->get_thread_name());
  1588     HandleMark hm(this);
  1589     this->entry_point()(this, this);
  1592   DTRACE_THREAD_PROBE(stop, this);
  1594   this->exit(false);
  1595   delete this;
  1599 static void ensure_join(JavaThread* thread) {
  1600   // We do not need to grap the Threads_lock, since we are operating on ourself.
  1601   Handle threadObj(thread, thread->threadObj());
  1602   assert(threadObj.not_null(), "java thread object must exist");
  1603   ObjectLocker lock(threadObj, thread);
  1604   // Ignore pending exception (ThreadDeath), since we are exiting anyway
  1605   thread->clear_pending_exception();
  1606   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
  1607   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
  1608   // Clear the native thread instance - this makes isAlive return false and allows the join()
  1609   // to complete once we've done the notify_all below
  1610   java_lang_Thread::set_thread(threadObj(), NULL);
  1611   lock.notify_all(thread);
  1612   // Ignore pending exception (ThreadDeath), since we are exiting anyway
  1613   thread->clear_pending_exception();
  1617 // For any new cleanup additions, please check to see if they need to be applied to
  1618 // cleanup_failed_attach_current_thread as well.
  1619 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
  1620   assert(this == JavaThread::current(),  "thread consistency check");
  1621   if (!InitializeJavaLangSystem) return;
  1623   HandleMark hm(this);
  1624   Handle uncaught_exception(this, this->pending_exception());
  1625   this->clear_pending_exception();
  1626   Handle threadObj(this, this->threadObj());
  1627   assert(threadObj.not_null(), "Java thread object should be created");
  1629   if (get_thread_profiler() != NULL) {
  1630     get_thread_profiler()->disengage();
  1631     ResourceMark rm;
  1632     get_thread_profiler()->print(get_thread_name());
  1636   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
  1638     EXCEPTION_MARK;
  1640     CLEAR_PENDING_EXCEPTION;
  1642   // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
  1643   // has to be fixed by a runtime query method
  1644   if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
  1645     // JSR-166: change call from from ThreadGroup.uncaughtException to
  1646     // java.lang.Thread.dispatchUncaughtException
  1647     if (uncaught_exception.not_null()) {
  1648       Handle group(this, java_lang_Thread::threadGroup(threadObj()));
  1650         EXCEPTION_MARK;
  1651         // Check if the method Thread.dispatchUncaughtException() exists. If so
  1652         // call it.  Otherwise we have an older library without the JSR-166 changes,
  1653         // so call ThreadGroup.uncaughtException()
  1654         KlassHandle recvrKlass(THREAD, threadObj->klass());
  1655         CallInfo callinfo;
  1656         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
  1657         LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
  1658                                            vmSymbols::dispatchUncaughtException_name(),
  1659                                            vmSymbols::throwable_void_signature(),
  1660                                            KlassHandle(), false, false, THREAD);
  1661         CLEAR_PENDING_EXCEPTION;
  1662         methodHandle method = callinfo.selected_method();
  1663         if (method.not_null()) {
  1664           JavaValue result(T_VOID);
  1665           JavaCalls::call_virtual(&result,
  1666                                   threadObj, thread_klass,
  1667                                   vmSymbols::dispatchUncaughtException_name(),
  1668                                   vmSymbols::throwable_void_signature(),
  1669                                   uncaught_exception,
  1670                                   THREAD);
  1671         } else {
  1672           KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
  1673           JavaValue result(T_VOID);
  1674           JavaCalls::call_virtual(&result,
  1675                                   group, thread_group,
  1676                                   vmSymbols::uncaughtException_name(),
  1677                                   vmSymbols::thread_throwable_void_signature(),
  1678                                   threadObj,           // Arg 1
  1679                                   uncaught_exception,  // Arg 2
  1680                                   THREAD);
  1682         if (HAS_PENDING_EXCEPTION) {
  1683           ResourceMark rm(this);
  1684           jio_fprintf(defaultStream::error_stream(),
  1685                 "\nException: %s thrown from the UncaughtExceptionHandler"
  1686                 " in thread \"%s\"\n",
  1687                 Klass::cast(pending_exception()->klass())->external_name(),
  1688                 get_thread_name());
  1689           CLEAR_PENDING_EXCEPTION;
  1694     // Called before the java thread exit since we want to read info
  1695     // from java_lang_Thread object
  1696     EVENT_BEGIN(TraceEventThreadEnd, event);
  1697     EVENT_COMMIT(event,
  1698         EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
  1700     // Call after last event on thread
  1701     EVENT_THREAD_EXIT(this);
  1703     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
  1704     // the execution of the method. If that is not enough, then we don't really care. Thread.stop
  1705     // is deprecated anyhow.
  1706     { int count = 3;
  1707       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
  1708         EXCEPTION_MARK;
  1709         JavaValue result(T_VOID);
  1710         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
  1711         JavaCalls::call_virtual(&result,
  1712                               threadObj, thread_klass,
  1713                               vmSymbols::exit_method_name(),
  1714                               vmSymbols::void_method_signature(),
  1715                               THREAD);
  1716         CLEAR_PENDING_EXCEPTION;
  1720     // notify JVMTI
  1721     if (JvmtiExport::should_post_thread_life()) {
  1722       JvmtiExport::post_thread_end(this);
  1725     // We have notified the agents that we are exiting, before we go on,
  1726     // we must check for a pending external suspend request and honor it
  1727     // in order to not surprise the thread that made the suspend request.
  1728     while (true) {
  1730         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
  1731         if (!is_external_suspend()) {
  1732           set_terminated(_thread_exiting);
  1733           ThreadService::current_thread_exiting(this);
  1734           break;
  1736         // Implied else:
  1737         // Things get a little tricky here. We have a pending external
  1738         // suspend request, but we are holding the SR_lock so we
  1739         // can't just self-suspend. So we temporarily drop the lock
  1740         // and then self-suspend.
  1743       ThreadBlockInVM tbivm(this);
  1744       java_suspend_self();
  1746       // We're done with this suspend request, but we have to loop around
  1747       // and check again. Eventually we will get SR_lock without a pending
  1748       // external suspend request and will be able to mark ourselves as
  1749       // exiting.
  1751     // no more external suspends are allowed at this point
  1752   } else {
  1753     // before_exit() has already posted JVMTI THREAD_END events
  1756   // Notify waiters on thread object. This has to be done after exit() is called
  1757   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
  1758   // group should have the destroyed bit set before waiters are notified).
  1759   ensure_join(this);
  1760   assert(!this->has_pending_exception(), "ensure_join should have cleared");
  1762   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
  1763   // held by this thread must be released.  A detach operation must only
  1764   // get here if there are no Java frames on the stack.  Therefore, any
  1765   // owned monitors at this point MUST be JNI-acquired monitors which are
  1766   // pre-inflated and in the monitor cache.
  1767   //
  1768   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
  1769   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
  1770     assert(!this->has_last_Java_frame(), "detaching with Java frames?");
  1771     ObjectSynchronizer::release_monitors_owned_by_thread(this);
  1772     assert(!this->has_pending_exception(), "release_monitors should have cleared");
  1775   // These things needs to be done while we are still a Java Thread. Make sure that thread
  1776   // is in a consistent state, in case GC happens
  1777   assert(_privileged_stack_top == NULL, "must be NULL when we get here");
  1779   if (active_handles() != NULL) {
  1780     JNIHandleBlock* block = active_handles();
  1781     set_active_handles(NULL);
  1782     JNIHandleBlock::release_block(block);
  1785   if (free_handle_block() != NULL) {
  1786     JNIHandleBlock* block = free_handle_block();
  1787     set_free_handle_block(NULL);
  1788     JNIHandleBlock::release_block(block);
  1791   // These have to be removed while this is still a valid thread.
  1792   remove_stack_guard_pages();
  1794   if (UseTLAB) {
  1795     tlab().make_parsable(true);  // retire TLAB
  1798   if (JvmtiEnv::environments_might_exist()) {
  1799     JvmtiExport::cleanup_thread(this);
  1802 #ifndef SERIALGC
  1803   // We must flush G1-related buffers before removing a thread from
  1804   // the list of active threads.
  1805   if (UseG1GC) {
  1806     flush_barrier_queues();
  1808 #endif
  1810   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
  1811   Threads::remove(this);
  1814 #ifndef SERIALGC
  1815 // Flush G1-related queues.
  1816 void JavaThread::flush_barrier_queues() {
  1817   satb_mark_queue().flush();
  1818   dirty_card_queue().flush();
  1821 void JavaThread::initialize_queues() {
  1822   assert(!SafepointSynchronize::is_at_safepoint(),
  1823          "we should not be at a safepoint");
  1825   ObjPtrQueue& satb_queue = satb_mark_queue();
  1826   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
  1827   // The SATB queue should have been constructed with its active
  1828   // field set to false.
  1829   assert(!satb_queue.is_active(), "SATB queue should not be active");
  1830   assert(satb_queue.is_empty(), "SATB queue should be empty");
  1831   // If we are creating the thread during a marking cycle, we should
  1832   // set the active field of the SATB queue to true.
  1833   if (satb_queue_set.is_active()) {
  1834     satb_queue.set_active(true);
  1837   DirtyCardQueue& dirty_queue = dirty_card_queue();
  1838   // The dirty card queue should have been constructed with its
  1839   // active field set to true.
  1840   assert(dirty_queue.is_active(), "dirty card queue should be active");
  1842 #endif // !SERIALGC
  1844 void JavaThread::cleanup_failed_attach_current_thread() {
  1845   if (get_thread_profiler() != NULL) {
  1846     get_thread_profiler()->disengage();
  1847     ResourceMark rm;
  1848     get_thread_profiler()->print(get_thread_name());
  1851   if (active_handles() != NULL) {
  1852     JNIHandleBlock* block = active_handles();
  1853     set_active_handles(NULL);
  1854     JNIHandleBlock::release_block(block);
  1857   if (free_handle_block() != NULL) {
  1858     JNIHandleBlock* block = free_handle_block();
  1859     set_free_handle_block(NULL);
  1860     JNIHandleBlock::release_block(block);
  1863   // These have to be removed while this is still a valid thread.
  1864   remove_stack_guard_pages();
  1866   if (UseTLAB) {
  1867     tlab().make_parsable(true);  // retire TLAB, if any
  1870 #ifndef SERIALGC
  1871   if (UseG1GC) {
  1872     flush_barrier_queues();
  1874 #endif
  1876   Threads::remove(this);
  1877   delete this;
  1883 JavaThread* JavaThread::active() {
  1884   Thread* thread = ThreadLocalStorage::thread();
  1885   assert(thread != NULL, "just checking");
  1886   if (thread->is_Java_thread()) {
  1887     return (JavaThread*) thread;
  1888   } else {
  1889     assert(thread->is_VM_thread(), "this must be a vm thread");
  1890     VM_Operation* op = ((VMThread*) thread)->vm_operation();
  1891     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
  1892     assert(ret->is_Java_thread(), "must be a Java thread");
  1893     return ret;
  1897 bool JavaThread::is_lock_owned(address adr) const {
  1898   if (Thread::is_lock_owned(adr)) return true;
  1900   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
  1901     if (chunk->contains(adr)) return true;
  1904   return false;
  1908 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
  1909   chunk->set_next(monitor_chunks());
  1910   set_monitor_chunks(chunk);
  1913 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
  1914   guarantee(monitor_chunks() != NULL, "must be non empty");
  1915   if (monitor_chunks() == chunk) {
  1916     set_monitor_chunks(chunk->next());
  1917   } else {
  1918     MonitorChunk* prev = monitor_chunks();
  1919     while (prev->next() != chunk) prev = prev->next();
  1920     prev->set_next(chunk->next());
  1924 // JVM support.
  1926 // Note: this function shouldn't block if it's called in
  1927 // _thread_in_native_trans state (such as from
  1928 // check_special_condition_for_native_trans()).
  1929 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
  1931   if (has_last_Java_frame() && has_async_condition()) {
  1932     // If we are at a polling page safepoint (not a poll return)
  1933     // then we must defer async exception because live registers
  1934     // will be clobbered by the exception path. Poll return is
  1935     // ok because the call we a returning from already collides
  1936     // with exception handling registers and so there is no issue.
  1937     // (The exception handling path kills call result registers but
  1938     //  this is ok since the exception kills the result anyway).
  1940     if (is_at_poll_safepoint()) {
  1941       // if the code we are returning to has deoptimized we must defer
  1942       // the exception otherwise live registers get clobbered on the
  1943       // exception path before deoptimization is able to retrieve them.
  1944       //
  1945       RegisterMap map(this, false);
  1946       frame caller_fr = last_frame().sender(&map);
  1947       assert(caller_fr.is_compiled_frame(), "what?");
  1948       if (caller_fr.is_deoptimized_frame()) {
  1949         if (TraceExceptions) {
  1950           ResourceMark rm;
  1951           tty->print_cr("deferred async exception at compiled safepoint");
  1953         return;
  1958   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
  1959   if (condition == _no_async_condition) {
  1960     // Conditions have changed since has_special_runtime_exit_condition()
  1961     // was called:
  1962     // - if we were here only because of an external suspend request,
  1963     //   then that was taken care of above (or cancelled) so we are done
  1964     // - if we were here because of another async request, then it has
  1965     //   been cleared between the has_special_runtime_exit_condition()
  1966     //   and now so again we are done
  1967     return;
  1970   // Check for pending async. exception
  1971   if (_pending_async_exception != NULL) {
  1972     // Only overwrite an already pending exception, if it is not a threadDeath.
  1973     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
  1975       // We cannot call Exceptions::_throw(...) here because we cannot block
  1976       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
  1978       if (TraceExceptions) {
  1979         ResourceMark rm;
  1980         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
  1981         if (has_last_Java_frame() ) {
  1982           frame f = last_frame();
  1983           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
  1985         tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
  1987       _pending_async_exception = NULL;
  1988       clear_has_async_exception();
  1992   if (check_unsafe_error &&
  1993       condition == _async_unsafe_access_error && !has_pending_exception()) {
  1994     condition = _no_async_condition;  // done
  1995     switch (thread_state()) {
  1996     case _thread_in_vm:
  1998         JavaThread* THREAD = this;
  1999         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
  2001     case _thread_in_native:
  2003         ThreadInVMfromNative tiv(this);
  2004         JavaThread* THREAD = this;
  2005         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
  2007     case _thread_in_Java:
  2009         ThreadInVMfromJava tiv(this);
  2010         JavaThread* THREAD = this;
  2011         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
  2013     default:
  2014       ShouldNotReachHere();
  2018   assert(condition == _no_async_condition || has_pending_exception() ||
  2019          (!check_unsafe_error && condition == _async_unsafe_access_error),
  2020          "must have handled the async condition, if no exception");
  2023 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
  2024   //
  2025   // Check for pending external suspend. Internal suspend requests do
  2026   // not use handle_special_runtime_exit_condition().
  2027   // If JNIEnv proxies are allowed, don't self-suspend if the target
  2028   // thread is not the current thread. In older versions of jdbx, jdbx
  2029   // threads could call into the VM with another thread's JNIEnv so we
  2030   // can be here operating on behalf of a suspended thread (4432884).
  2031   bool do_self_suspend = is_external_suspend_with_lock();
  2032   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
  2033     //
  2034     // Because thread is external suspended the safepoint code will count
  2035     // thread as at a safepoint. This can be odd because we can be here
  2036     // as _thread_in_Java which would normally transition to _thread_blocked
  2037     // at a safepoint. We would like to mark the thread as _thread_blocked
  2038     // before calling java_suspend_self like all other callers of it but
  2039     // we must then observe proper safepoint protocol. (We can't leave
  2040     // _thread_blocked with a safepoint in progress). However we can be
  2041     // here as _thread_in_native_trans so we can't use a normal transition
  2042     // constructor/destructor pair because they assert on that type of
  2043     // transition. We could do something like:
  2044     //
  2045     // JavaThreadState state = thread_state();
  2046     // set_thread_state(_thread_in_vm);
  2047     // {
  2048     //   ThreadBlockInVM tbivm(this);
  2049     //   java_suspend_self()
  2050     // }
  2051     // set_thread_state(_thread_in_vm_trans);
  2052     // if (safepoint) block;
  2053     // set_thread_state(state);
  2054     //
  2055     // but that is pretty messy. Instead we just go with the way the
  2056     // code has worked before and note that this is the only path to
  2057     // java_suspend_self that doesn't put the thread in _thread_blocked
  2058     // mode.
  2060     frame_anchor()->make_walkable(this);
  2061     java_suspend_self();
  2063     // We might be here for reasons in addition to the self-suspend request
  2064     // so check for other async requests.
  2067   if (check_asyncs) {
  2068     check_and_handle_async_exceptions();
  2072 void JavaThread::send_thread_stop(oop java_throwable)  {
  2073   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
  2074   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
  2075   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
  2077   // Do not throw asynchronous exceptions against the compiler thread
  2078   // (the compiler thread should not be a Java thread -- fix in 1.4.2)
  2079   if (is_Compiler_thread()) return;
  2082     // Actually throw the Throwable against the target Thread - however
  2083     // only if there is no thread death exception installed already.
  2084     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
  2085       // If the topmost frame is a runtime stub, then we are calling into
  2086       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
  2087       // must deoptimize the caller before continuing, as the compiled  exception handler table
  2088       // may not be valid
  2089       if (has_last_Java_frame()) {
  2090         frame f = last_frame();
  2091         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
  2092           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
  2093           RegisterMap reg_map(this, UseBiasedLocking);
  2094           frame compiled_frame = f.sender(&reg_map);
  2095           if (compiled_frame.can_be_deoptimized()) {
  2096             Deoptimization::deoptimize(this, compiled_frame, &reg_map);
  2101       // Set async. pending exception in thread.
  2102       set_pending_async_exception(java_throwable);
  2104       if (TraceExceptions) {
  2105        ResourceMark rm;
  2106        tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
  2108       // for AbortVMOnException flag
  2109       NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
  2114   // Interrupt thread so it will wake up from a potential wait()
  2115   Thread::interrupt(this);
  2118 // External suspension mechanism.
  2119 //
  2120 // Tell the VM to suspend a thread when ever it knows that it does not hold on
  2121 // to any VM_locks and it is at a transition
  2122 // Self-suspension will happen on the transition out of the vm.
  2123 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
  2124 //
  2125 // Guarantees on return:
  2126 //   + Target thread will not execute any new bytecode (that's why we need to
  2127 //     force a safepoint)
  2128 //   + Target thread will not enter any new monitors
  2129 //
  2130 void JavaThread::java_suspend() {
  2131   { MutexLocker mu(Threads_lock);
  2132     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
  2133        return;
  2137   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
  2138     if (!is_external_suspend()) {
  2139       // a racing resume has cancelled us; bail out now
  2140       return;
  2143     // suspend is done
  2144     uint32_t debug_bits = 0;
  2145     // Warning: is_ext_suspend_completed() may temporarily drop the
  2146     // SR_lock to allow the thread to reach a stable thread state if
  2147     // it is currently in a transient thread state.
  2148     if (is_ext_suspend_completed(false /* !called_by_wait */,
  2149                                  SuspendRetryDelay, &debug_bits) ) {
  2150       return;
  2154   VM_ForceSafepoint vm_suspend;
  2155   VMThread::execute(&vm_suspend);
  2158 // Part II of external suspension.
  2159 // A JavaThread self suspends when it detects a pending external suspend
  2160 // request. This is usually on transitions. It is also done in places
  2161 // where continuing to the next transition would surprise the caller,
  2162 // e.g., monitor entry.
  2163 //
  2164 // Returns the number of times that the thread self-suspended.
  2165 //
  2166 // Note: DO NOT call java_suspend_self() when you just want to block current
  2167 //       thread. java_suspend_self() is the second stage of cooperative
  2168 //       suspension for external suspend requests and should only be used
  2169 //       to complete an external suspend request.
  2170 //
  2171 int JavaThread::java_suspend_self() {
  2172   int ret = 0;
  2174   // we are in the process of exiting so don't suspend
  2175   if (is_exiting()) {
  2176      clear_external_suspend();
  2177      return ret;
  2180   assert(_anchor.walkable() ||
  2181     (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
  2182     "must have walkable stack");
  2184   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
  2186   assert(!this->is_ext_suspended(),
  2187     "a thread trying to self-suspend should not already be suspended");
  2189   if (this->is_suspend_equivalent()) {
  2190     // If we are self-suspending as a result of the lifting of a
  2191     // suspend equivalent condition, then the suspend_equivalent
  2192     // flag is not cleared until we set the ext_suspended flag so
  2193     // that wait_for_ext_suspend_completion() returns consistent
  2194     // results.
  2195     this->clear_suspend_equivalent();
  2198   // A racing resume may have cancelled us before we grabbed SR_lock
  2199   // above. Or another external suspend request could be waiting for us
  2200   // by the time we return from SR_lock()->wait(). The thread
  2201   // that requested the suspension may already be trying to walk our
  2202   // stack and if we return now, we can change the stack out from under
  2203   // it. This would be a "bad thing (TM)" and cause the stack walker
  2204   // to crash. We stay self-suspended until there are no more pending
  2205   // external suspend requests.
  2206   while (is_external_suspend()) {
  2207     ret++;
  2208     this->set_ext_suspended();
  2210     // _ext_suspended flag is cleared by java_resume()
  2211     while (is_ext_suspended()) {
  2212       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
  2216   return ret;
  2219 #ifdef ASSERT
  2220 // verify the JavaThread has not yet been published in the Threads::list, and
  2221 // hence doesn't need protection from concurrent access at this stage
  2222 void JavaThread::verify_not_published() {
  2223   if (!Threads_lock->owned_by_self()) {
  2224    MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);
  2225    assert( !Threads::includes(this),
  2226            "java thread shouldn't have been published yet!");
  2228   else {
  2229    assert( !Threads::includes(this),
  2230            "java thread shouldn't have been published yet!");
  2233 #endif
  2235 // Slow path when the native==>VM/Java barriers detect a safepoint is in
  2236 // progress or when _suspend_flags is non-zero.
  2237 // Current thread needs to self-suspend if there is a suspend request and/or
  2238 // block if a safepoint is in progress.
  2239 // Async exception ISN'T checked.
  2240 // Note only the ThreadInVMfromNative transition can call this function
  2241 // directly and when thread state is _thread_in_native_trans
  2242 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
  2243   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
  2245   JavaThread *curJT = JavaThread::current();
  2246   bool do_self_suspend = thread->is_external_suspend();
  2248   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
  2250   // If JNIEnv proxies are allowed, don't self-suspend if the target
  2251   // thread is not the current thread. In older versions of jdbx, jdbx
  2252   // threads could call into the VM with another thread's JNIEnv so we
  2253   // can be here operating on behalf of a suspended thread (4432884).
  2254   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
  2255     JavaThreadState state = thread->thread_state();
  2257     // We mark this thread_blocked state as a suspend-equivalent so
  2258     // that a caller to is_ext_suspend_completed() won't be confused.
  2259     // The suspend-equivalent state is cleared by java_suspend_self().
  2260     thread->set_suspend_equivalent();
  2262     // If the safepoint code sees the _thread_in_native_trans state, it will
  2263     // wait until the thread changes to other thread state. There is no
  2264     // guarantee on how soon we can obtain the SR_lock and complete the
  2265     // self-suspend request. It would be a bad idea to let safepoint wait for
  2266     // too long. Temporarily change the state to _thread_blocked to
  2267     // let the VM thread know that this thread is ready for GC. The problem
  2268     // of changing thread state is that safepoint could happen just after
  2269     // java_suspend_self() returns after being resumed, and VM thread will
  2270     // see the _thread_blocked state. We must check for safepoint
  2271     // after restoring the state and make sure we won't leave while a safepoint
  2272     // is in progress.
  2273     thread->set_thread_state(_thread_blocked);
  2274     thread->java_suspend_self();
  2275     thread->set_thread_state(state);
  2276     // Make sure new state is seen by VM thread
  2277     if (os::is_MP()) {
  2278       if (UseMembar) {
  2279         // Force a fence between the write above and read below
  2280         OrderAccess::fence();
  2281       } else {
  2282         // Must use this rather than serialization page in particular on Windows
  2283         InterfaceSupport::serialize_memory(thread);
  2288   if (SafepointSynchronize::do_call_back()) {
  2289     // If we are safepointing, then block the caller which may not be
  2290     // the same as the target thread (see above).
  2291     SafepointSynchronize::block(curJT);
  2294   if (thread->is_deopt_suspend()) {
  2295     thread->clear_deopt_suspend();
  2296     RegisterMap map(thread, false);
  2297     frame f = thread->last_frame();
  2298     while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
  2299       f = f.sender(&map);
  2301     if (f.id() == thread->must_deopt_id()) {
  2302       thread->clear_must_deopt_id();
  2303       f.deoptimize(thread);
  2304     } else {
  2305       fatal("missed deoptimization!");
  2310 // Slow path when the native==>VM/Java barriers detect a safepoint is in
  2311 // progress or when _suspend_flags is non-zero.
  2312 // Current thread needs to self-suspend if there is a suspend request and/or
  2313 // block if a safepoint is in progress.
  2314 // Also check for pending async exception (not including unsafe access error).
  2315 // Note only the native==>VM/Java barriers can call this function and when
  2316 // thread state is _thread_in_native_trans.
  2317 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
  2318   check_safepoint_and_suspend_for_native_trans(thread);
  2320   if (thread->has_async_exception()) {
  2321     // We are in _thread_in_native_trans state, don't handle unsafe
  2322     // access error since that may block.
  2323     thread->check_and_handle_async_exceptions(false);
  2327 // This is a variant of the normal
  2328 // check_special_condition_for_native_trans with slightly different
  2329 // semantics for use by critical native wrappers.  It does all the
  2330 // normal checks but also performs the transition back into
  2331 // thread_in_Java state.  This is required so that critical natives
  2332 // can potentially block and perform a GC if they are the last thread
  2333 // exiting the GC_locker.
  2334 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
  2335   check_special_condition_for_native_trans(thread);
  2337   // Finish the transition
  2338   thread->set_thread_state(_thread_in_Java);
  2340   if (thread->do_critical_native_unlock()) {
  2341     ThreadInVMfromJavaNoAsyncException tiv(thread);
  2342     GC_locker::unlock_critical(thread);
  2343     thread->clear_critical_native_unlock();
  2347 // We need to guarantee the Threads_lock here, since resumes are not
  2348 // allowed during safepoint synchronization
  2349 // Can only resume from an external suspension
  2350 void JavaThread::java_resume() {
  2351   assert_locked_or_safepoint(Threads_lock);
  2353   // Sanity check: thread is gone, has started exiting or the thread
  2354   // was not externally suspended.
  2355   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
  2356     return;
  2359   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
  2361   clear_external_suspend();
  2363   if (is_ext_suspended()) {
  2364     clear_ext_suspended();
  2365     SR_lock()->notify_all();
  2369 void JavaThread::create_stack_guard_pages() {
  2370   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
  2371   address low_addr = stack_base() - stack_size();
  2372   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
  2374   int allocate = os::allocate_stack_guard_pages();
  2375   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
  2377   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
  2378     warning("Attempt to allocate stack guard pages failed.");
  2379     return;
  2382   if (os::guard_memory((char *) low_addr, len)) {
  2383     _stack_guard_state = stack_guard_enabled;
  2384   } else {
  2385     warning("Attempt to protect stack guard pages failed.");
  2386     if (os::uncommit_memory((char *) low_addr, len)) {
  2387       warning("Attempt to deallocate stack guard pages failed.");
  2392 void JavaThread::remove_stack_guard_pages() {
  2393   if (_stack_guard_state == stack_guard_unused) return;
  2394   address low_addr = stack_base() - stack_size();
  2395   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
  2397   if (os::allocate_stack_guard_pages()) {
  2398     if (os::remove_stack_guard_pages((char *) low_addr, len)) {
  2399       _stack_guard_state = stack_guard_unused;
  2400     } else {
  2401       warning("Attempt to deallocate stack guard pages failed.");
  2403   } else {
  2404     if (_stack_guard_state == stack_guard_unused) return;
  2405     if (os::unguard_memory((char *) low_addr, len)) {
  2406       _stack_guard_state = stack_guard_unused;
  2407     } else {
  2408         warning("Attempt to unprotect stack guard pages failed.");
  2413 void JavaThread::enable_stack_yellow_zone() {
  2414   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
  2415   assert(_stack_guard_state != stack_guard_enabled, "already enabled");
  2417   // The base notation is from the stacks point of view, growing downward.
  2418   // We need to adjust it to work correctly with guard_memory()
  2419   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
  2421   guarantee(base < stack_base(),"Error calculating stack yellow zone");
  2422   guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
  2424   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
  2425     _stack_guard_state = stack_guard_enabled;
  2426   } else {
  2427     warning("Attempt to guard stack yellow zone failed.");
  2429   enable_register_stack_guard();
  2432 void JavaThread::disable_stack_yellow_zone() {
  2433   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
  2434   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
  2436   // Simply return if called for a thread that does not use guard pages.
  2437   if (_stack_guard_state == stack_guard_unused) return;
  2439   // The base notation is from the stacks point of view, growing downward.
  2440   // We need to adjust it to work correctly with guard_memory()
  2441   address base = stack_yellow_zone_base() - stack_yellow_zone_size();
  2443   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
  2444     _stack_guard_state = stack_guard_yellow_disabled;
  2445   } else {
  2446     warning("Attempt to unguard stack yellow zone failed.");
  2448   disable_register_stack_guard();
  2451 void JavaThread::enable_stack_red_zone() {
  2452   // The base notation is from the stacks point of view, growing downward.
  2453   // We need to adjust it to work correctly with guard_memory()
  2454   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
  2455   address base = stack_red_zone_base() - stack_red_zone_size();
  2457   guarantee(base < stack_base(),"Error calculating stack red zone");
  2458   guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
  2460   if(!os::guard_memory((char *) base, stack_red_zone_size())) {
  2461     warning("Attempt to guard stack red zone failed.");
  2465 void JavaThread::disable_stack_red_zone() {
  2466   // The base notation is from the stacks point of view, growing downward.
  2467   // We need to adjust it to work correctly with guard_memory()
  2468   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
  2469   address base = stack_red_zone_base() - stack_red_zone_size();
  2470   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
  2471     warning("Attempt to unguard stack red zone failed.");
  2475 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
  2476   // ignore is there is no stack
  2477   if (!has_last_Java_frame()) return;
  2478   // traverse the stack frames. Starts from top frame.
  2479   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
  2480     frame* fr = fst.current();
  2481     f(fr, fst.register_map());
  2486 #ifndef PRODUCT
  2487 // Deoptimization
  2488 // Function for testing deoptimization
  2489 void JavaThread::deoptimize() {
  2490   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
  2491   StackFrameStream fst(this, UseBiasedLocking);
  2492   bool deopt = false;           // Dump stack only if a deopt actually happens.
  2493   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
  2494   // Iterate over all frames in the thread and deoptimize
  2495   for(; !fst.is_done(); fst.next()) {
  2496     if(fst.current()->can_be_deoptimized()) {
  2498       if (only_at) {
  2499         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
  2500         // consists of comma or carriage return separated numbers so
  2501         // search for the current bci in that string.
  2502         address pc = fst.current()->pc();
  2503         nmethod* nm =  (nmethod*) fst.current()->cb();
  2504         ScopeDesc* sd = nm->scope_desc_at( pc);
  2505         char buffer[8];
  2506         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
  2507         size_t len = strlen(buffer);
  2508         const char * found = strstr(DeoptimizeOnlyAt, buffer);
  2509         while (found != NULL) {
  2510           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
  2511               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
  2512             // Check that the bci found is bracketed by terminators.
  2513             break;
  2515           found = strstr(found + 1, buffer);
  2517         if (!found) {
  2518           continue;
  2522       if (DebugDeoptimization && !deopt) {
  2523         deopt = true; // One-time only print before deopt
  2524         tty->print_cr("[BEFORE Deoptimization]");
  2525         trace_frames();
  2526         trace_stack();
  2528       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
  2532   if (DebugDeoptimization && deopt) {
  2533     tty->print_cr("[AFTER Deoptimization]");
  2534     trace_frames();
  2539 // Make zombies
  2540 void JavaThread::make_zombies() {
  2541   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
  2542     if (fst.current()->can_be_deoptimized()) {
  2543       // it is a Java nmethod
  2544       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
  2545       nm->make_not_entrant();
  2549 #endif // PRODUCT
  2552 void JavaThread::deoptimized_wrt_marked_nmethods() {
  2553   if (!has_last_Java_frame()) return;
  2554   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
  2555   StackFrameStream fst(this, UseBiasedLocking);
  2556   for(; !fst.is_done(); fst.next()) {
  2557     if (fst.current()->should_be_deoptimized()) {
  2558       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
  2564 // GC support
  2565 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
  2567 void JavaThread::gc_epilogue() {
  2568   frames_do(frame_gc_epilogue);
  2572 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
  2574 void JavaThread::gc_prologue() {
  2575   frames_do(frame_gc_prologue);
  2578 // If the caller is a NamedThread, then remember, in the current scope,
  2579 // the given JavaThread in its _processed_thread field.
  2580 class RememberProcessedThread: public StackObj {
  2581   NamedThread* _cur_thr;
  2582 public:
  2583   RememberProcessedThread(JavaThread* jthr) {
  2584     Thread* thread = Thread::current();
  2585     if (thread->is_Named_thread()) {
  2586       _cur_thr = (NamedThread *)thread;
  2587       _cur_thr->set_processed_thread(jthr);
  2588     } else {
  2589       _cur_thr = NULL;
  2593   ~RememberProcessedThread() {
  2594     if (_cur_thr) {
  2595       _cur_thr->set_processed_thread(NULL);
  2598 };
  2600 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
  2601   // Verify that the deferred card marks have been flushed.
  2602   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
  2604   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
  2605   // since there may be more than one thread using each ThreadProfiler.
  2607   // Traverse the GCHandles
  2608   Thread::oops_do(f, cf);
  2610   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
  2611           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
  2613   if (has_last_Java_frame()) {
  2614     // Record JavaThread to GC thread
  2615     RememberProcessedThread rpt(this);
  2617     // Traverse the privileged stack
  2618     if (_privileged_stack_top != NULL) {
  2619       _privileged_stack_top->oops_do(f);
  2622     // traverse the registered growable array
  2623     if (_array_for_gc != NULL) {
  2624       for (int index = 0; index < _array_for_gc->length(); index++) {
  2625         f->do_oop(_array_for_gc->adr_at(index));
  2629     // Traverse the monitor chunks
  2630     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
  2631       chunk->oops_do(f);
  2634     // Traverse the execution stack
  2635     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
  2636       fst.current()->oops_do(f, cf, fst.register_map());
  2640   // callee_target is never live across a gc point so NULL it here should
  2641   // it still contain a methdOop.
  2643   set_callee_target(NULL);
  2645   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
  2646   // If we have deferred set_locals there might be oops waiting to be
  2647   // written
  2648   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
  2649   if (list != NULL) {
  2650     for (int i = 0; i < list->length(); i++) {
  2651       list->at(i)->oops_do(f);
  2655   // Traverse instance variables at the end since the GC may be moving things
  2656   // around using this function
  2657   f->do_oop((oop*) &_threadObj);
  2658   f->do_oop((oop*) &_vm_result);
  2659   f->do_oop((oop*) &_vm_result_2);
  2660   f->do_oop((oop*) &_exception_oop);
  2661   f->do_oop((oop*) &_pending_async_exception);
  2663   if (jvmti_thread_state() != NULL) {
  2664     jvmti_thread_state()->oops_do(f);
  2668 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
  2669   Thread::nmethods_do(cf);  // (super method is a no-op)
  2671   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
  2672           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
  2674   if (has_last_Java_frame()) {
  2675     // Traverse the execution stack
  2676     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
  2677       fst.current()->nmethods_do(cf);
  2682 // Printing
  2683 const char* _get_thread_state_name(JavaThreadState _thread_state) {
  2684   switch (_thread_state) {
  2685   case _thread_uninitialized:     return "_thread_uninitialized";
  2686   case _thread_new:               return "_thread_new";
  2687   case _thread_new_trans:         return "_thread_new_trans";
  2688   case _thread_in_native:         return "_thread_in_native";
  2689   case _thread_in_native_trans:   return "_thread_in_native_trans";
  2690   case _thread_in_vm:             return "_thread_in_vm";
  2691   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
  2692   case _thread_in_Java:           return "_thread_in_Java";
  2693   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
  2694   case _thread_blocked:           return "_thread_blocked";
  2695   case _thread_blocked_trans:     return "_thread_blocked_trans";
  2696   default:                        return "unknown thread state";
  2700 #ifndef PRODUCT
  2701 void JavaThread::print_thread_state_on(outputStream *st) const {
  2702   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
  2703 };
  2704 void JavaThread::print_thread_state() const {
  2705   print_thread_state_on(tty);
  2706 };
  2707 #endif // PRODUCT
  2709 // Called by Threads::print() for VM_PrintThreads operation
  2710 void JavaThread::print_on(outputStream *st) const {
  2711   st->print("\"%s\" ", get_thread_name());
  2712   oop thread_oop = threadObj();
  2713   if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
  2714   Thread::print_on(st);
  2715   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
  2716   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
  2717   if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
  2718     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
  2720 #ifndef PRODUCT
  2721   print_thread_state_on(st);
  2722   _safepoint_state->print_on(st);
  2723 #endif // PRODUCT
  2726 // Called by fatal error handler. The difference between this and
  2727 // JavaThread::print() is that we can't grab lock or allocate memory.
  2728 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
  2729   st->print("JavaThread \"%s\"",  get_thread_name_string(buf, buflen));
  2730   oop thread_obj = threadObj();
  2731   if (thread_obj != NULL) {
  2732      if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
  2734   st->print(" [");
  2735   st->print("%s", _get_thread_state_name(_thread_state));
  2736   if (osthread()) {
  2737     st->print(", id=%d", osthread()->thread_id());
  2739   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
  2740             _stack_base - _stack_size, _stack_base);
  2741   st->print("]");
  2742   return;
  2745 // Verification
  2747 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
  2749 void JavaThread::verify() {
  2750   // Verify oops in the thread.
  2751   oops_do(&VerifyOopClosure::verify_oop, NULL);
  2753   // Verify the stack frames.
  2754   frames_do(frame_verify);
  2757 // CR 6300358 (sub-CR 2137150)
  2758 // Most callers of this method assume that it can't return NULL but a
  2759 // thread may not have a name whilst it is in the process of attaching to
  2760 // the VM - see CR 6412693, and there are places where a JavaThread can be
  2761 // seen prior to having it's threadObj set (eg JNI attaching threads and
  2762 // if vm exit occurs during initialization). These cases can all be accounted
  2763 // for such that this method never returns NULL.
  2764 const char* JavaThread::get_thread_name() const {
  2765 #ifdef ASSERT
  2766   // early safepoints can hit while current thread does not yet have TLS
  2767   if (!SafepointSynchronize::is_at_safepoint()) {
  2768     Thread *cur = Thread::current();
  2769     if (!(cur->is_Java_thread() && cur == this)) {
  2770       // Current JavaThreads are allowed to get their own name without
  2771       // the Threads_lock.
  2772       assert_locked_or_safepoint(Threads_lock);
  2775 #endif // ASSERT
  2776     return get_thread_name_string();
  2779 // Returns a non-NULL representation of this thread's name, or a suitable
  2780 // descriptive string if there is no set name
  2781 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
  2782   const char* name_str;
  2783   oop thread_obj = threadObj();
  2784   if (thread_obj != NULL) {
  2785     typeArrayOop name = java_lang_Thread::name(thread_obj);
  2786     if (name != NULL) {
  2787       if (buf == NULL) {
  2788         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
  2790       else {
  2791         name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
  2794     else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
  2795       name_str = "<no-name - thread is attaching>";
  2797     else {
  2798       name_str = Thread::name();
  2801   else {
  2802     name_str = Thread::name();
  2804   assert(name_str != NULL, "unexpected NULL thread name");
  2805   return name_str;
  2809 const char* JavaThread::get_threadgroup_name() const {
  2810   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
  2811   oop thread_obj = threadObj();
  2812   if (thread_obj != NULL) {
  2813     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
  2814     if (thread_group != NULL) {
  2815       typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
  2816       // ThreadGroup.name can be null
  2817       if (name != NULL) {
  2818         const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
  2819         return str;
  2823   return NULL;
  2826 const char* JavaThread::get_parent_name() const {
  2827   debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
  2828   oop thread_obj = threadObj();
  2829   if (thread_obj != NULL) {
  2830     oop thread_group = java_lang_Thread::threadGroup(thread_obj);
  2831     if (thread_group != NULL) {
  2832       oop parent = java_lang_ThreadGroup::parent(thread_group);
  2833       if (parent != NULL) {
  2834         typeArrayOop name = java_lang_ThreadGroup::name(parent);
  2835         // ThreadGroup.name can be null
  2836         if (name != NULL) {
  2837           const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
  2838           return str;
  2843   return NULL;
  2846 ThreadPriority JavaThread::java_priority() const {
  2847   oop thr_oop = threadObj();
  2848   if (thr_oop == NULL) return NormPriority; // Bootstrapping
  2849   ThreadPriority priority = java_lang_Thread::priority(thr_oop);
  2850   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
  2851   return priority;
  2854 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
  2856   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
  2857   // Link Java Thread object <-> C++ Thread
  2859   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
  2860   // and put it into a new Handle.  The Handle "thread_oop" can then
  2861   // be used to pass the C++ thread object to other methods.
  2863   // Set the Java level thread object (jthread) field of the
  2864   // new thread (a JavaThread *) to C++ thread object using the
  2865   // "thread_oop" handle.
  2867   // Set the thread field (a JavaThread *) of the
  2868   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
  2870   Handle thread_oop(Thread::current(),
  2871                     JNIHandles::resolve_non_null(jni_thread));
  2872   assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
  2873     "must be initialized");
  2874   set_threadObj(thread_oop());
  2875   java_lang_Thread::set_thread(thread_oop(), this);
  2877   if (prio == NoPriority) {
  2878     prio = java_lang_Thread::priority(thread_oop());
  2879     assert(prio != NoPriority, "A valid priority should be present");
  2882   // Push the Java priority down to the native thread; needs Threads_lock
  2883   Thread::set_priority(this, prio);
  2885   // Add the new thread to the Threads list and set it in motion.
  2886   // We must have threads lock in order to call Threads::add.
  2887   // It is crucial that we do not block before the thread is
  2888   // added to the Threads list for if a GC happens, then the java_thread oop
  2889   // will not be visited by GC.
  2890   Threads::add(this);
  2893 oop JavaThread::current_park_blocker() {
  2894   // Support for JSR-166 locks
  2895   oop thread_oop = threadObj();
  2896   if (thread_oop != NULL &&
  2897       JDK_Version::current().supports_thread_park_blocker()) {
  2898     return java_lang_Thread::park_blocker(thread_oop);
  2900   return NULL;
  2904 void JavaThread::print_stack_on(outputStream* st) {
  2905   if (!has_last_Java_frame()) return;
  2906   ResourceMark rm;
  2907   HandleMark   hm;
  2909   RegisterMap reg_map(this);
  2910   vframe* start_vf = last_java_vframe(&reg_map);
  2911   int count = 0;
  2912   for (vframe* f = start_vf; f; f = f->sender() ) {
  2913     if (f->is_java_frame()) {
  2914       javaVFrame* jvf = javaVFrame::cast(f);
  2915       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
  2917       // Print out lock information
  2918       if (JavaMonitorsInStackTrace) {
  2919         jvf->print_lock_info_on(st, count);
  2921     } else {
  2922       // Ignore non-Java frames
  2925     // Bail-out case for too deep stacks
  2926     count++;
  2927     if (MaxJavaStackTraceDepth == count) return;
  2932 // JVMTI PopFrame support
  2933 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
  2934   assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
  2935   if (in_bytes(size_in_bytes) != 0) {
  2936     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
  2937     _popframe_preserved_args_size = in_bytes(size_in_bytes);
  2938     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
  2942 void* JavaThread::popframe_preserved_args() {
  2943   return _popframe_preserved_args;
  2946 ByteSize JavaThread::popframe_preserved_args_size() {
  2947   return in_ByteSize(_popframe_preserved_args_size);
  2950 WordSize JavaThread::popframe_preserved_args_size_in_words() {
  2951   int sz = in_bytes(popframe_preserved_args_size());
  2952   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
  2953   return in_WordSize(sz / wordSize);
  2956 void JavaThread::popframe_free_preserved_args() {
  2957   assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
  2958   FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread);
  2959   _popframe_preserved_args = NULL;
  2960   _popframe_preserved_args_size = 0;
  2963 #ifndef PRODUCT
  2965 void JavaThread::trace_frames() {
  2966   tty->print_cr("[Describe stack]");
  2967   int frame_no = 1;
  2968   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
  2969     tty->print("  %d. ", frame_no++);
  2970     fst.current()->print_value_on(tty,this);
  2971     tty->cr();
  2975 class PrintAndVerifyOopClosure: public OopClosure {
  2976  protected:
  2977   template <class T> inline void do_oop_work(T* p) {
  2978     oop obj = oopDesc::load_decode_heap_oop(p);
  2979     if (obj == NULL) return;
  2980     tty->print(INTPTR_FORMAT ": ", p);
  2981     if (obj->is_oop_or_null()) {
  2982       if (obj->is_objArray()) {
  2983         tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
  2984       } else {
  2985         obj->print();
  2987     } else {
  2988       tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
  2990     tty->cr();
  2992  public:
  2993   virtual void do_oop(oop* p) { do_oop_work(p); }
  2994   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
  2995 };
  2998 static void oops_print(frame* f, const RegisterMap *map) {
  2999   PrintAndVerifyOopClosure print;
  3000   f->print_value();
  3001   f->oops_do(&print, NULL, (RegisterMap*)map);
  3004 // Print our all the locations that contain oops and whether they are
  3005 // valid or not.  This useful when trying to find the oldest frame
  3006 // where an oop has gone bad since the frame walk is from youngest to
  3007 // oldest.
  3008 void JavaThread::trace_oops() {
  3009   tty->print_cr("[Trace oops]");
  3010   frames_do(oops_print);
  3014 #ifdef ASSERT
  3015 // Print or validate the layout of stack frames
  3016 void JavaThread::print_frame_layout(int depth, bool validate_only) {
  3017   ResourceMark rm;
  3018   PRESERVE_EXCEPTION_MARK;
  3019   FrameValues values;
  3020   int frame_no = 0;
  3021   for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
  3022     fst.current()->describe(values, ++frame_no);
  3023     if (depth == frame_no) break;
  3025   if (validate_only) {
  3026     values.validate();
  3027   } else {
  3028     tty->print_cr("[Describe stack layout]");
  3029     values.print(this);
  3032 #endif
  3034 void JavaThread::trace_stack_from(vframe* start_vf) {
  3035   ResourceMark rm;
  3036   int vframe_no = 1;
  3037   for (vframe* f = start_vf; f; f = f->sender() ) {
  3038     if (f->is_java_frame()) {
  3039       javaVFrame::cast(f)->print_activation(vframe_no++);
  3040     } else {
  3041       f->print();
  3043     if (vframe_no > StackPrintLimit) {
  3044       tty->print_cr("...<more frames>...");
  3045       return;
  3051 void JavaThread::trace_stack() {
  3052   if (!has_last_Java_frame()) return;
  3053   ResourceMark rm;
  3054   HandleMark   hm;
  3055   RegisterMap reg_map(this);
  3056   trace_stack_from(last_java_vframe(&reg_map));
  3060 #endif // PRODUCT
  3063 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
  3064   assert(reg_map != NULL, "a map must be given");
  3065   frame f = last_frame();
  3066   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
  3067     if (vf->is_java_frame()) return javaVFrame::cast(vf);
  3069   return NULL;
  3073 klassOop JavaThread::security_get_caller_class(int depth) {
  3074   vframeStream vfst(this);
  3075   vfst.security_get_caller_frame(depth);
  3076   if (!vfst.at_end()) {
  3077     return vfst.method()->method_holder();
  3079   return NULL;
  3082 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
  3083   assert(thread->is_Compiler_thread(), "must be compiler thread");
  3084   CompileBroker::compiler_thread_loop();
  3087 // Create a CompilerThread
  3088 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
  3089 : JavaThread(&compiler_thread_entry) {
  3090   _env   = NULL;
  3091   _log   = NULL;
  3092   _task  = NULL;
  3093   _queue = queue;
  3094   _counters = counters;
  3095   _buffer_blob = NULL;
  3096   _scanned_nmethod = NULL;
  3098 #ifndef PRODUCT
  3099   _ideal_graph_printer = NULL;
  3100 #endif
  3103 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
  3104   JavaThread::oops_do(f, cf);
  3105   if (_scanned_nmethod != NULL && cf != NULL) {
  3106     // Safepoints can occur when the sweeper is scanning an nmethod so
  3107     // process it here to make sure it isn't unloaded in the middle of
  3108     // a scan.
  3109     cf->do_code_blob(_scanned_nmethod);
  3113 // ======= Threads ========
  3115 // The Threads class links together all active threads, and provides
  3116 // operations over all threads.  It is protected by its own Mutex
  3117 // lock, which is also used in other contexts to protect thread
  3118 // operations from having the thread being operated on from exiting
  3119 // and going away unexpectedly (e.g., safepoint synchronization)
  3121 JavaThread* Threads::_thread_list = NULL;
  3122 int         Threads::_number_of_threads = 0;
  3123 int         Threads::_number_of_non_daemon_threads = 0;
  3124 int         Threads::_return_code = 0;
  3125 size_t      JavaThread::_stack_size_at_create = 0;
  3127 // All JavaThreads
  3128 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
  3130 void os_stream();
  3132 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
  3133 void Threads::threads_do(ThreadClosure* tc) {
  3134   assert_locked_or_safepoint(Threads_lock);
  3135   // ALL_JAVA_THREADS iterates through all JavaThreads
  3136   ALL_JAVA_THREADS(p) {
  3137     tc->do_thread(p);
  3139   // Someday we could have a table or list of all non-JavaThreads.
  3140   // For now, just manually iterate through them.
  3141   tc->do_thread(VMThread::vm_thread());
  3142   Universe::heap()->gc_threads_do(tc);
  3143   WatcherThread *wt = WatcherThread::watcher_thread();
  3144   // Strictly speaking, the following NULL check isn't sufficient to make sure
  3145   // the data for WatcherThread is still valid upon being examined. However,
  3146   // considering that WatchThread terminates when the VM is on the way to
  3147   // exit at safepoint, the chance of the above is extremely small. The right
  3148   // way to prevent termination of WatcherThread would be to acquire
  3149   // Terminator_lock, but we can't do that without violating the lock rank
  3150   // checking in some cases.
  3151   if (wt != NULL)
  3152     tc->do_thread(wt);
  3154   // If CompilerThreads ever become non-JavaThreads, add them here
  3157 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
  3159   extern void JDK_Version_init();
  3161   // Check version
  3162   if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
  3164   // Initialize the output stream module
  3165   ostream_init();
  3167   // Process java launcher properties.
  3168   Arguments::process_sun_java_launcher_properties(args);
  3170   // Initialize the os module before using TLS
  3171   os::init();
  3173   // Initialize system properties.
  3174   Arguments::init_system_properties();
  3176   // So that JDK version can be used as a discrimintor when parsing arguments
  3177   JDK_Version_init();
  3179   // Update/Initialize System properties after JDK version number is known
  3180   Arguments::init_version_specific_system_properties();
  3182   // Parse arguments
  3183   jint parse_result = Arguments::parse(args);
  3184   if (parse_result != JNI_OK) return parse_result;
  3186   if (PauseAtStartup) {
  3187     os::pause();
  3190 #ifndef USDT2
  3191   HS_DTRACE_PROBE(hotspot, vm__init__begin);
  3192 #else /* USDT2 */
  3193   HOTSPOT_VM_INIT_BEGIN();
  3194 #endif /* USDT2 */
  3196   // Record VM creation timing statistics
  3197   TraceVmCreationTime create_vm_timer;
  3198   create_vm_timer.start();
  3200   // Timing (must come after argument parsing)
  3201   TraceTime timer("Create VM", TraceStartupTime);
  3203   // Initialize the os module after parsing the args
  3204   jint os_init_2_result = os::init_2();
  3205   if (os_init_2_result != JNI_OK) return os_init_2_result;
  3207   // intialize TLS
  3208   ThreadLocalStorage::init();
  3210   // Bootstrap native memory tracking, so it can start recording memory
  3211   // activities before worker thread is started. This is the first phase
  3212   // of bootstrapping, VM is currently running in single-thread mode.
  3213   MemTracker::bootstrap_single_thread();
  3215   // Initialize output stream logging
  3216   ostream_init_log();
  3218   // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
  3219   // Must be before create_vm_init_agents()
  3220   if (Arguments::init_libraries_at_startup()) {
  3221     convert_vm_init_libraries_to_agents();
  3224   // Launch -agentlib/-agentpath and converted -Xrun agents
  3225   if (Arguments::init_agents_at_startup()) {
  3226     create_vm_init_agents();
  3229   // Initialize Threads state
  3230   _thread_list = NULL;
  3231   _number_of_threads = 0;
  3232   _number_of_non_daemon_threads = 0;
  3234   // Initialize global data structures and create system classes in heap
  3235   vm_init_globals();
  3237   // Attach the main thread to this os thread
  3238   JavaThread* main_thread = new JavaThread();
  3239   main_thread->set_thread_state(_thread_in_vm);
  3240   // must do this before set_active_handles and initialize_thread_local_storage
  3241   // Note: on solaris initialize_thread_local_storage() will (indirectly)
  3242   // change the stack size recorded here to one based on the java thread
  3243   // stacksize. This adjusted size is what is used to figure the placement
  3244   // of the guard pages.
  3245   main_thread->record_stack_base_and_size();
  3246   main_thread->initialize_thread_local_storage();
  3248   main_thread->set_active_handles(JNIHandleBlock::allocate_block());
  3250   if (!main_thread->set_as_starting_thread()) {
  3251     vm_shutdown_during_initialization(
  3252       "Failed necessary internal allocation. Out of swap space");
  3253     delete main_thread;
  3254     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
  3255     return JNI_ENOMEM;
  3258   // Enable guard page *after* os::create_main_thread(), otherwise it would
  3259   // crash Linux VM, see notes in os_linux.cpp.
  3260   main_thread->create_stack_guard_pages();
  3262   // Initialize Java-Level synchronization subsystem
  3263   ObjectMonitor::Initialize() ;
  3265   // Second phase of bootstrapping, VM is about entering multi-thread mode
  3266   MemTracker::bootstrap_multi_thread();
  3268   // Initialize global modules
  3269   jint status = init_globals();
  3270   if (status != JNI_OK) {
  3271     delete main_thread;
  3272     *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
  3273     return status;
  3276   // Should be done after the heap is fully created
  3277   main_thread->cache_global_variables();
  3279   HandleMark hm;
  3281   { MutexLocker mu(Threads_lock);
  3282     Threads::add(main_thread);
  3285   // Any JVMTI raw monitors entered in onload will transition into
  3286   // real raw monitor. VM is setup enough here for raw monitor enter.
  3287   JvmtiExport::transition_pending_onload_raw_monitors();
  3289   if (VerifyBeforeGC &&
  3290       Universe::heap()->total_collections() >= VerifyGCStartAt) {
  3291     Universe::heap()->prepare_for_verify();
  3292     Universe::verify();   // make sure we're starting with a clean slate
  3295   // Fully start NMT
  3296   MemTracker::start();
  3298   // Create the VMThread
  3299   { TraceTime timer("Start VMThread", TraceStartupTime);
  3300     VMThread::create();
  3301     Thread* vmthread = VMThread::vm_thread();
  3303     if (!os::create_thread(vmthread, os::vm_thread))
  3304       vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
  3306     // Wait for the VM thread to become ready, and VMThread::run to initialize
  3307     // Monitors can have spurious returns, must always check another state flag
  3309       MutexLocker ml(Notify_lock);
  3310       os::start_thread(vmthread);
  3311       while (vmthread->active_handles() == NULL) {
  3312         Notify_lock->wait();
  3317   assert (Universe::is_fully_initialized(), "not initialized");
  3318   EXCEPTION_MARK;
  3320   // At this point, the Universe is initialized, but we have not executed
  3321   // any byte code.  Now is a good time (the only time) to dump out the
  3322   // internal state of the JVM for sharing.
  3324   if (DumpSharedSpaces) {
  3325     Universe::heap()->preload_and_dump(CHECK_0);
  3326     ShouldNotReachHere();
  3329   // Always call even when there are not JVMTI environments yet, since environments
  3330   // may be attached late and JVMTI must track phases of VM execution
  3331   JvmtiExport::enter_start_phase();
  3333   // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
  3334   JvmtiExport::post_vm_start();
  3337     TraceTime timer("Initialize java.lang classes", TraceStartupTime);
  3339     if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
  3340       create_vm_init_libraries();
  3343     if (InitializeJavaLangString) {
  3344       initialize_class(vmSymbols::java_lang_String(), CHECK_0);
  3345     } else {
  3346       warning("java.lang.String not initialized");
  3349     if (AggressiveOpts) {
  3351         // Forcibly initialize java/util/HashMap and mutate the private
  3352         // static final "frontCacheEnabled" field before we start creating instances
  3353 #ifdef ASSERT
  3354         klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
  3355         assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
  3356 #endif
  3357         klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
  3358         KlassHandle k = KlassHandle(THREAD, k_o);
  3359         guarantee(k.not_null(), "Must find java/util/HashMap");
  3360         instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
  3361         ik->initialize(CHECK_0);
  3362         fieldDescriptor fd;
  3363         // Possible we might not find this field; if so, don't break
  3364         if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
  3365           k()->java_mirror()->bool_field_put(fd.offset(), true);
  3369       if (UseStringCache) {
  3370         // Forcibly initialize java/lang/StringValue and mutate the private
  3371         // static final "stringCacheEnabled" field before we start creating instances
  3372         klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
  3373         // Possible that StringValue isn't present: if so, silently don't break
  3374         if (k_o != NULL) {
  3375           KlassHandle k = KlassHandle(THREAD, k_o);
  3376           instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
  3377           ik->initialize(CHECK_0);
  3378           fieldDescriptor fd;
  3379           // Possible we might not find this field: if so, silently don't break
  3380           if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
  3381             k()->java_mirror()->bool_field_put(fd.offset(), true);
  3387     // Initialize java_lang.System (needed before creating the thread)
  3388     if (InitializeJavaLangSystem) {
  3389       initialize_class(vmSymbols::java_lang_System(), CHECK_0);
  3390       initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
  3391       Handle thread_group = create_initial_thread_group(CHECK_0);
  3392       Universe::set_main_thread_group(thread_group());
  3393       initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
  3394       oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
  3395       main_thread->set_threadObj(thread_object);
  3396       // Set thread status to running since main thread has
  3397       // been started and running.
  3398       java_lang_Thread::set_thread_status(thread_object,
  3399                                           java_lang_Thread::RUNNABLE);
  3401       // The VM preresolve methods to these classes. Make sure that get initialized
  3402       initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
  3403       initialize_class(vmSymbols::java_lang_ref_Finalizer(),  CHECK_0);
  3404       // The VM creates & returns objects of this class. Make sure it's initialized.
  3405       initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
  3406       call_initializeSystemClass(CHECK_0);
  3408       // get the Java runtime name after java.lang.System is initialized
  3409       JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
  3410     } else {
  3411       warning("java.lang.System not initialized");
  3414     // an instance of OutOfMemory exception has been allocated earlier
  3415     if (InitializeJavaLangExceptionsErrors) {
  3416       initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
  3417       initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
  3418       initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
  3419       initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
  3420       initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
  3421       initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
  3422       initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
  3423       initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK_0);
  3424     } else {
  3425       warning("java.lang.OutOfMemoryError has not been initialized");
  3426       warning("java.lang.NullPointerException has not been initialized");
  3427       warning("java.lang.ClassCastException has not been initialized");
  3428       warning("java.lang.ArrayStoreException has not been initialized");
  3429       warning("java.lang.ArithmeticException has not been initialized");
  3430       warning("java.lang.StackOverflowError has not been initialized");
  3431       warning("java.lang.IllegalArgumentException has not been initialized");
  3435   // See        : bugid 4211085.
  3436   // Background : the static initializer of java.lang.Compiler tries to read
  3437   //              property"java.compiler" and read & write property "java.vm.info".
  3438   //              When a security manager is installed through the command line
  3439   //              option "-Djava.security.manager", the above properties are not
  3440   //              readable and the static initializer for java.lang.Compiler fails
  3441   //              resulting in a NoClassDefFoundError.  This can happen in any
  3442   //              user code which calls methods in java.lang.Compiler.
  3443   // Hack :       the hack is to pre-load and initialize this class, so that only
  3444   //              system domains are on the stack when the properties are read.
  3445   //              Currently even the AWT code has calls to methods in java.lang.Compiler.
  3446   //              On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
  3447   // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
  3448   //              read and write"java.vm.info" in the default policy file. See bugid 4211383
  3449   //              Once that is done, we should remove this hack.
  3450   initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
  3452   // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
  3453   // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
  3454   // compiler does not get loaded through java.lang.Compiler).  "java -version" with the
  3455   // hotspot vm says "nojit" all the time which is confusing.  So, we reset it here.
  3456   // This should also be taken out as soon as 4211383 gets fixed.
  3457   reset_vm_info_property(CHECK_0);
  3459   quicken_jni_functions();
  3461   // Must be run after init_ft which initializes ft_enabled
  3462   if (TRACE_INITIALIZE() != JNI_OK) {
  3463     vm_exit_during_initialization("Failed to initialize tracing backend");
  3466   // Set flag that basic initialization has completed. Used by exceptions and various
  3467   // debug stuff, that does not work until all basic classes have been initialized.
  3468   set_init_completed();
  3470 #ifndef USDT2
  3471   HS_DTRACE_PROBE(hotspot, vm__init__end);
  3472 #else /* USDT2 */
  3473   HOTSPOT_VM_INIT_END();
  3474 #endif /* USDT2 */
  3476   // record VM initialization completion time
  3477   Management::record_vm_init_completed();
  3479   // Compute system loader. Note that this has to occur after set_init_completed, since
  3480   // valid exceptions may be thrown in the process.
  3481   // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
  3482   // set_init_completed has just been called, causing exceptions not to be shortcut
  3483   // anymore. We call vm_exit_during_initialization directly instead.
  3484   SystemDictionary::compute_java_system_loader(THREAD);
  3485   if (HAS_PENDING_EXCEPTION) {
  3486     vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
  3489 #ifndef SERIALGC
  3490   // Support for ConcurrentMarkSweep. This should be cleaned up
  3491   // and better encapsulated. The ugly nested if test would go away
  3492   // once things are properly refactored. XXX YSR
  3493   if (UseConcMarkSweepGC || UseG1GC) {
  3494     if (UseConcMarkSweepGC) {
  3495       ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
  3496     } else {
  3497       ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
  3499     if (HAS_PENDING_EXCEPTION) {
  3500       vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
  3503 #endif // SERIALGC
  3505   // Always call even when there are not JVMTI environments yet, since environments
  3506   // may be attached late and JVMTI must track phases of VM execution
  3507   JvmtiExport::enter_live_phase();
  3509   // Signal Dispatcher needs to be started before VMInit event is posted
  3510   os::signal_init();
  3512   // Start Attach Listener if +StartAttachListener or it can't be started lazily
  3513   if (!DisableAttachMechanism) {
  3514     if (StartAttachListener || AttachListener::init_at_startup()) {
  3515       AttachListener::init();
  3519   // Launch -Xrun agents
  3520   // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
  3521   // back-end can launch with -Xdebug -Xrunjdwp.
  3522   if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
  3523     create_vm_init_libraries();
  3526   // Notify JVMTI agents that VM initialization is complete - nop if no agents.
  3527   JvmtiExport::post_vm_initialized();
  3529   if (!TRACE_START()) {
  3530     vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
  3533   if (CleanChunkPoolAsync) {
  3534     Chunk::start_chunk_pool_cleaner_task();
  3537   // initialize compiler(s)
  3538   CompileBroker::compilation_init();
  3540   Management::initialize(THREAD);
  3541   if (HAS_PENDING_EXCEPTION) {
  3542     // management agent fails to start possibly due to
  3543     // configuration problem and is responsible for printing
  3544     // stack trace if appropriate. Simply exit VM.
  3545     vm_exit(1);
  3548   if (Arguments::has_profile())       FlatProfiler::engage(main_thread, true);
  3549   if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
  3550   if (MemProfiling)                   MemProfiler::engage();
  3551   StatSampler::engage();
  3552   if (CheckJNICalls)                  JniPeriodicChecker::engage();
  3554   BiasedLocking::init();
  3556   if (JDK_Version::current().post_vm_init_hook_enabled()) {
  3557     call_postVMInitHook(THREAD);
  3558     // The Java side of PostVMInitHook.run must deal with all
  3559     // exceptions and provide means of diagnosis.
  3560     if (HAS_PENDING_EXCEPTION) {
  3561       CLEAR_PENDING_EXCEPTION;
  3565   // Start up the WatcherThread if there are any periodic tasks
  3566   // NOTE:  All PeriodicTasks should be registered by now. If they
  3567   //   aren't, late joiners might appear to start slowly (we might
  3568   //   take a while to process their first tick).
  3569   if (PeriodicTask::num_tasks() > 0) {
  3570     WatcherThread::start();
  3573   // Give os specific code one last chance to start
  3574   os::init_3();
  3576   create_vm_timer.end();
  3577   return JNI_OK;
  3580 // type for the Agent_OnLoad and JVM_OnLoad entry points
  3581 extern "C" {
  3582   typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
  3584 // Find a command line agent library and return its entry point for
  3585 //         -agentlib:  -agentpath:   -Xrun
  3586 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
  3587 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
  3588   OnLoadEntry_t on_load_entry = NULL;
  3589   void *library = agent->os_lib();  // check if we have looked it up before
  3591   if (library == NULL) {
  3592     char buffer[JVM_MAXPATHLEN];
  3593     char ebuf[1024];
  3594     const char *name = agent->name();
  3595     const char *msg = "Could not find agent library ";
  3597     if (agent->is_absolute_path()) {
  3598       library = os::dll_load(name, ebuf, sizeof ebuf);
  3599       if (library == NULL) {
  3600         const char *sub_msg = " in absolute path, with error: ";
  3601         size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
  3602         char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
  3603         jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
  3604         // If we can't find the agent, exit.
  3605         vm_exit_during_initialization(buf, NULL);
  3606         FREE_C_HEAP_ARRAY(char, buf, mtThread);
  3608     } else {
  3609       // Try to load the agent from the standard dll directory
  3610       os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
  3611       library = os::dll_load(buffer, ebuf, sizeof ebuf);
  3612 #ifdef KERNEL
  3613       // Download instrument dll
  3614       if (library == NULL && strcmp(name, "instrument") == 0) {
  3615         char *props = Arguments::get_kernel_properties();
  3616         char *home  = Arguments::get_java_home();
  3617         const char *fmt   = "%s/bin/java %s -Dkernel.background.download=false"
  3618                       " sun.jkernel.DownloadManager -download client_jvm";
  3619         size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
  3620         char *cmd = NEW_C_HEAP_ARRAY(char, length, mtThread);
  3621         jio_snprintf(cmd, length, fmt, home, props);
  3622         int status = os::fork_and_exec(cmd);
  3623         FreeHeap(props);
  3624         if (status == -1) {
  3625           warning(cmd);
  3626           vm_exit_during_initialization("fork_and_exec failed: %s",
  3627                                          strerror(errno));
  3629         FREE_C_HEAP_ARRAY(char, cmd, mtThread);
  3630         // when this comes back the instrument.dll should be where it belongs.
  3631         library = os::dll_load(buffer, ebuf, sizeof ebuf);
  3633 #endif // KERNEL
  3634       if (library == NULL) { // Try the local directory
  3635         char ns[1] = {0};
  3636         os::dll_build_name(buffer, sizeof(buffer), ns, name);
  3637         library = os::dll_load(buffer, ebuf, sizeof ebuf);
  3638         if (library == NULL) {
  3639           const char *sub_msg = " on the library path, with error: ";
  3640           size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
  3641           char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
  3642           jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
  3643           // If we can't find the agent, exit.
  3644           vm_exit_during_initialization(buf, NULL);
  3645           FREE_C_HEAP_ARRAY(char, buf, mtThread);
  3649     agent->set_os_lib(library);
  3652   // Find the OnLoad function.
  3653   for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
  3654     on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
  3655     if (on_load_entry != NULL) break;
  3657   return on_load_entry;
  3660 // Find the JVM_OnLoad entry point
  3661 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
  3662   const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
  3663   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
  3666 // Find the Agent_OnLoad entry point
  3667 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
  3668   const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
  3669   return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
  3672 // For backwards compatibility with -Xrun
  3673 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
  3674 // treated like -agentpath:
  3675 // Must be called before agent libraries are created
  3676 void Threads::convert_vm_init_libraries_to_agents() {
  3677   AgentLibrary* agent;
  3678   AgentLibrary* next;
  3680   for (agent = Arguments::libraries(); agent != NULL; agent = next) {
  3681     next = agent->next();  // cache the next agent now as this agent may get moved off this list
  3682     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
  3684     // If there is an JVM_OnLoad function it will get called later,
  3685     // otherwise see if there is an Agent_OnLoad
  3686     if (on_load_entry == NULL) {
  3687       on_load_entry = lookup_agent_on_load(agent);
  3688       if (on_load_entry != NULL) {
  3689         // switch it to the agent list -- so that Agent_OnLoad will be called,
  3690         // JVM_OnLoad won't be attempted and Agent_OnUnload will
  3691         Arguments::convert_library_to_agent(agent);
  3692       } else {
  3693         vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
  3699 // Create agents for -agentlib:  -agentpath:  and converted -Xrun
  3700 // Invokes Agent_OnLoad
  3701 // Called very early -- before JavaThreads exist
  3702 void Threads::create_vm_init_agents() {
  3703   extern struct JavaVM_ main_vm;
  3704   AgentLibrary* agent;
  3706   JvmtiExport::enter_onload_phase();
  3707   for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
  3708     OnLoadEntry_t  on_load_entry = lookup_agent_on_load(agent);
  3710     if (on_load_entry != NULL) {
  3711       // Invoke the Agent_OnLoad function
  3712       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
  3713       if (err != JNI_OK) {
  3714         vm_exit_during_initialization("agent library failed to init", agent->name());
  3716     } else {
  3717       vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
  3720   JvmtiExport::enter_primordial_phase();
  3723 extern "C" {
  3724   typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
  3727 void Threads::shutdown_vm_agents() {
  3728   // Send any Agent_OnUnload notifications
  3729   const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
  3730   extern struct JavaVM_ main_vm;
  3731   for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
  3733     // Find the Agent_OnUnload function.
  3734     for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
  3735       Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
  3736                os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
  3738       // Invoke the Agent_OnUnload function
  3739       if (unload_entry != NULL) {
  3740         JavaThread* thread = JavaThread::current();
  3741         ThreadToNativeFromVM ttn(thread);
  3742         HandleMark hm(thread);
  3743         (*unload_entry)(&main_vm);
  3744         break;
  3750 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
  3751 // Invokes JVM_OnLoad
  3752 void Threads::create_vm_init_libraries() {
  3753   extern struct JavaVM_ main_vm;
  3754   AgentLibrary* agent;
  3756   for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
  3757     OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
  3759     if (on_load_entry != NULL) {
  3760       // Invoke the JVM_OnLoad function
  3761       JavaThread* thread = JavaThread::current();
  3762       ThreadToNativeFromVM ttn(thread);
  3763       HandleMark hm(thread);
  3764       jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
  3765       if (err != JNI_OK) {
  3766         vm_exit_during_initialization("-Xrun library failed to init", agent->name());
  3768     } else {
  3769       vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
  3774 // Last thread running calls java.lang.Shutdown.shutdown()
  3775 void JavaThread::invoke_shutdown_hooks() {
  3776   HandleMark hm(this);
  3778   // We could get here with a pending exception, if so clear it now.
  3779   if (this->has_pending_exception()) {
  3780     this->clear_pending_exception();
  3783   EXCEPTION_MARK;
  3784   klassOop k =
  3785     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
  3786                                       THREAD);
  3787   if (k != NULL) {
  3788     // SystemDictionary::resolve_or_null will return null if there was
  3789     // an exception.  If we cannot load the Shutdown class, just don't
  3790     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
  3791     // and finalizers (if runFinalizersOnExit is set) won't be run.
  3792     // Note that if a shutdown hook was registered or runFinalizersOnExit
  3793     // was called, the Shutdown class would have already been loaded
  3794     // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
  3795     instanceKlassHandle shutdown_klass (THREAD, k);
  3796     JavaValue result(T_VOID);
  3797     JavaCalls::call_static(&result,
  3798                            shutdown_klass,
  3799                            vmSymbols::shutdown_method_name(),
  3800                            vmSymbols::void_method_signature(),
  3801                            THREAD);
  3803   CLEAR_PENDING_EXCEPTION;
  3806 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
  3807 // the program falls off the end of main(). Another VM exit path is through
  3808 // vm_exit() when the program calls System.exit() to return a value or when
  3809 // there is a serious error in VM. The two shutdown paths are not exactly
  3810 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
  3811 // and VM_Exit op at VM level.
  3812 //
  3813 // Shutdown sequence:
  3814 //   + Shutdown native memory tracking if it is on
  3815 //   + Wait until we are the last non-daemon thread to execute
  3816 //     <-- every thing is still working at this moment -->
  3817 //   + Call java.lang.Shutdown.shutdown(), which will invoke Java level
  3818 //        shutdown hooks, run finalizers if finalization-on-exit
  3819 //   + Call before_exit(), prepare for VM exit
  3820 //      > run VM level shutdown hooks (they are registered through JVM_OnExit(),
  3821 //        currently the only user of this mechanism is File.deleteOnExit())
  3822 //      > stop flat profiler, StatSampler, watcher thread, CMS threads,
  3823 //        post thread end and vm death events to JVMTI,
  3824 //        stop signal thread
  3825 //   + Call JavaThread::exit(), it will:
  3826 //      > release JNI handle blocks, remove stack guard pages
  3827 //      > remove this thread from Threads list
  3828 //     <-- no more Java code from this thread after this point -->
  3829 //   + Stop VM thread, it will bring the remaining VM to a safepoint and stop
  3830 //     the compiler threads at safepoint
  3831 //     <-- do not use anything that could get blocked by Safepoint -->
  3832 //   + Disable tracing at JNI/JVM barriers
  3833 //   + Set _vm_exited flag for threads that are still running native code
  3834 //   + Delete this thread
  3835 //   + Call exit_globals()
  3836 //      > deletes tty
  3837 //      > deletes PerfMemory resources
  3838 //   + Return to caller
  3840 bool Threads::destroy_vm() {
  3841   JavaThread* thread = JavaThread::current();
  3843   // Wait until we are the last non-daemon thread to execute
  3844   { MutexLocker nu(Threads_lock);
  3845     while (Threads::number_of_non_daemon_threads() > 1 )
  3846       // This wait should make safepoint checks, wait without a timeout,
  3847       // and wait as a suspend-equivalent condition.
  3848       //
  3849       // Note: If the FlatProfiler is running and this thread is waiting
  3850       // for another non-daemon thread to finish, then the FlatProfiler
  3851       // is waiting for the external suspend request on this thread to
  3852       // complete. wait_for_ext_suspend_completion() will eventually
  3853       // timeout, but that takes time. Making this wait a suspend-
  3854       // equivalent condition solves that timeout problem.
  3855       //
  3856       Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
  3857                          Mutex::_as_suspend_equivalent_flag);
  3860   // Shutdown NMT before exit. Otherwise,
  3861   // it will run into trouble when system destroys static variables.
  3862   MemTracker::shutdown(MemTracker::NMT_normal);
  3864   // Hang forever on exit if we are reporting an error.
  3865   if (ShowMessageBoxOnError && is_error_reported()) {
  3866     os::infinite_sleep();
  3868   os::wait_for_keypress_at_exit();
  3870   if (JDK_Version::is_jdk12x_version()) {
  3871     // We are the last thread running, so check if finalizers should be run.
  3872     // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
  3873     HandleMark rm(thread);
  3874     Universe::run_finalizers_on_exit();
  3875   } else {
  3876     // run Java level shutdown hooks
  3877     thread->invoke_shutdown_hooks();
  3880   before_exit(thread);
  3882   thread->exit(true);
  3884   // Stop VM thread.
  3886     // 4945125 The vm thread comes to a safepoint during exit.
  3887     // GC vm_operations can get caught at the safepoint, and the
  3888     // heap is unparseable if they are caught. Grab the Heap_lock
  3889     // to prevent this. The GC vm_operations will not be able to
  3890     // queue until after the vm thread is dead.
  3891     // After this point, we'll never emerge out of the safepoint before
  3892     // the VM exits, so concurrent GC threads do not need to be explicitly
  3893     // stopped; they remain inactive until the process exits.
  3894     // Note: some concurrent G1 threads may be running during a safepoint,
  3895     // but these will not be accessing the heap, just some G1-specific side
  3896     // data structures that are not accessed by any other threads but them
  3897     // after this point in a terminal safepoint.
  3899     MutexLocker ml(Heap_lock);
  3901     VMThread::wait_for_vm_thread_exit();
  3902     assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
  3903     VMThread::destroy();
  3906   // clean up ideal graph printers
  3907 #if defined(COMPILER2) && !defined(PRODUCT)
  3908   IdealGraphPrinter::clean_up();
  3909 #endif
  3911   // Now, all Java threads are gone except daemon threads. Daemon threads
  3912   // running Java code or in VM are stopped by the Safepoint. However,
  3913   // daemon threads executing native code are still running.  But they
  3914   // will be stopped at native=>Java/VM barriers. Note that we can't
  3915   // simply kill or suspend them, as it is inherently deadlock-prone.
  3917 #ifndef PRODUCT
  3918   // disable function tracing at JNI/JVM barriers
  3919   TraceJNICalls = false;
  3920   TraceJVMCalls = false;
  3921   TraceRuntimeCalls = false;
  3922 #endif
  3924   VM_Exit::set_vm_exited();
  3926   notify_vm_shutdown();
  3928   delete thread;
  3930   // exit_globals() will delete tty
  3931   exit_globals();
  3933   return true;
  3937 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
  3938   if (version == JNI_VERSION_1_1) return JNI_TRUE;
  3939   return is_supported_jni_version(version);
  3943 jboolean Threads::is_supported_jni_version(jint version) {
  3944   if (version == JNI_VERSION_1_2) return JNI_TRUE;
  3945   if (version == JNI_VERSION_1_4) return JNI_TRUE;
  3946   if (version == JNI_VERSION_1_6) return JNI_TRUE;
  3947   return JNI_FALSE;
  3951 void Threads::add(JavaThread* p, bool force_daemon) {
  3952   // The threads lock must be owned at this point
  3953   assert_locked_or_safepoint(Threads_lock);
  3955   // See the comment for this method in thread.hpp for its purpose and
  3956   // why it is called here.
  3957   p->initialize_queues();
  3958   p->set_next(_thread_list);
  3959   _thread_list = p;
  3960   _number_of_threads++;
  3961   oop threadObj = p->threadObj();
  3962   bool daemon = true;
  3963   // Bootstrapping problem: threadObj can be null for initial
  3964   // JavaThread (or for threads attached via JNI)
  3965   if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
  3966     _number_of_non_daemon_threads++;
  3967     daemon = false;
  3970   p->set_safepoint_visible(true);
  3972   ThreadService::add_thread(p, daemon);
  3974   // Possible GC point.
  3975   Events::log(p, "Thread added: " INTPTR_FORMAT, p);
  3978 void Threads::remove(JavaThread* p) {
  3979   // Extra scope needed for Thread_lock, so we can check
  3980   // that we do not remove thread without safepoint code notice
  3981   { MutexLocker ml(Threads_lock);
  3983     assert(includes(p), "p must be present");
  3985     JavaThread* current = _thread_list;
  3986     JavaThread* prev    = NULL;
  3988     while (current != p) {
  3989       prev    = current;
  3990       current = current->next();
  3993     if (prev) {
  3994       prev->set_next(current->next());
  3995     } else {
  3996       _thread_list = p->next();
  3998     _number_of_threads--;
  3999     oop threadObj = p->threadObj();
  4000     bool daemon = true;
  4001     if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
  4002       _number_of_non_daemon_threads--;
  4003       daemon = false;
  4005       // Only one thread left, do a notify on the Threads_lock so a thread waiting
  4006       // on destroy_vm will wake up.
  4007       if (number_of_non_daemon_threads() == 1)
  4008         Threads_lock->notify_all();
  4010     ThreadService::remove_thread(p, daemon);
  4012     // Make sure that safepoint code disregard this thread. This is needed since
  4013     // the thread might mess around with locks after this point. This can cause it
  4014     // to do callbacks into the safepoint code. However, the safepoint code is not aware
  4015     // of this thread since it is removed from the queue.
  4016     p->set_terminated_value();
  4018     // Now, this thread is not visible to safepoint
  4019     p->set_safepoint_visible(false);
  4021   } // unlock Threads_lock
  4023   // Since Events::log uses a lock, we grab it outside the Threads_lock
  4024   Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
  4027 // Threads_lock must be held when this is called (or must be called during a safepoint)
  4028 bool Threads::includes(JavaThread* p) {
  4029   assert(Threads_lock->is_locked(), "sanity check");
  4030   ALL_JAVA_THREADS(q) {
  4031     if (q == p ) {
  4032       return true;
  4035   return false;
  4038 // Operations on the Threads list for GC.  These are not explicitly locked,
  4039 // but the garbage collector must provide a safe context for them to run.
  4040 // In particular, these things should never be called when the Threads_lock
  4041 // is held by some other thread. (Note: the Safepoint abstraction also
  4042 // uses the Threads_lock to gurantee this property. It also makes sure that
  4043 // all threads gets blocked when exiting or starting).
  4045 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
  4046   ALL_JAVA_THREADS(p) {
  4047     p->oops_do(f, cf);
  4049   VMThread::vm_thread()->oops_do(f, cf);
  4052 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
  4053   // Introduce a mechanism allowing parallel threads to claim threads as
  4054   // root groups.  Overhead should be small enough to use all the time,
  4055   // even in sequential code.
  4056   SharedHeap* sh = SharedHeap::heap();
  4057   // Cannot yet substitute active_workers for n_par_threads
  4058   // because of G1CollectedHeap::verify() use of
  4059   // SharedHeap::process_strong_roots().  n_par_threads == 0 will
  4060   // turn off parallelism in process_strong_roots while active_workers
  4061   // is being used for parallelism elsewhere.
  4062   bool is_par = sh->n_par_threads() > 0;
  4063   assert(!is_par ||
  4064          (SharedHeap::heap()->n_par_threads() ==
  4065           SharedHeap::heap()->workers()->active_workers()), "Mismatch");
  4066   int cp = SharedHeap::heap()->strong_roots_parity();
  4067   ALL_JAVA_THREADS(p) {
  4068     if (p->claim_oops_do(is_par, cp)) {
  4069       p->oops_do(f, cf);
  4072   VMThread* vmt = VMThread::vm_thread();
  4073   if (vmt->claim_oops_do(is_par, cp)) {
  4074     vmt->oops_do(f, cf);
  4078 #ifndef SERIALGC
  4079 // Used by ParallelScavenge
  4080 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
  4081   ALL_JAVA_THREADS(p) {
  4082     q->enqueue(new ThreadRootsTask(p));
  4084   q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
  4087 // Used by Parallel Old
  4088 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
  4089   ALL_JAVA_THREADS(p) {
  4090     q->enqueue(new ThreadRootsMarkingTask(p));
  4092   q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
  4094 #endif // SERIALGC
  4096 void Threads::nmethods_do(CodeBlobClosure* cf) {
  4097   ALL_JAVA_THREADS(p) {
  4098     p->nmethods_do(cf);
  4100   VMThread::vm_thread()->nmethods_do(cf);
  4103 void Threads::gc_epilogue() {
  4104   ALL_JAVA_THREADS(p) {
  4105     p->gc_epilogue();
  4109 void Threads::gc_prologue() {
  4110   ALL_JAVA_THREADS(p) {
  4111     p->gc_prologue();
  4115 void Threads::deoptimized_wrt_marked_nmethods() {
  4116   ALL_JAVA_THREADS(p) {
  4117     p->deoptimized_wrt_marked_nmethods();
  4122 // Get count Java threads that are waiting to enter the specified monitor.
  4123 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
  4124   address monitor, bool doLock) {
  4125   assert(doLock || SafepointSynchronize::is_at_safepoint(),
  4126     "must grab Threads_lock or be at safepoint");
  4127   GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
  4129   int i = 0;
  4131     MutexLockerEx ml(doLock ? Threads_lock : NULL);
  4132     ALL_JAVA_THREADS(p) {
  4133       if (p->is_Compiler_thread()) continue;
  4135       address pending = (address)p->current_pending_monitor();
  4136       if (pending == monitor) {             // found a match
  4137         if (i < count) result->append(p);   // save the first count matches
  4138         i++;
  4142   return result;
  4146 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
  4147   assert(doLock ||
  4148          Threads_lock->owned_by_self() ||
  4149          SafepointSynchronize::is_at_safepoint(),
  4150          "must grab Threads_lock or be at safepoint");
  4152   // NULL owner means not locked so we can skip the search
  4153   if (owner == NULL) return NULL;
  4156     MutexLockerEx ml(doLock ? Threads_lock : NULL);
  4157     ALL_JAVA_THREADS(p) {
  4158       // first, see if owner is the address of a Java thread
  4159       if (owner == (address)p) return p;
  4162   assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
  4163   if (UseHeavyMonitors) return NULL;
  4165   //
  4166   // If we didn't find a matching Java thread and we didn't force use of
  4167   // heavyweight monitors, then the owner is the stack address of the
  4168   // Lock Word in the owning Java thread's stack.
  4169   //
  4170   JavaThread* the_owner = NULL;
  4172     MutexLockerEx ml(doLock ? Threads_lock : NULL);
  4173     ALL_JAVA_THREADS(q) {
  4174       if (q->is_lock_owned(owner)) {
  4175         the_owner = q;
  4176         break;
  4180   assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
  4181   return the_owner;
  4184 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
  4185 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
  4186   char buf[32];
  4187   st->print_cr(os::local_time_string(buf, sizeof(buf)));
  4189   st->print_cr("Full thread dump %s (%s %s):",
  4190                 Abstract_VM_Version::vm_name(),
  4191                 Abstract_VM_Version::vm_release(),
  4192                 Abstract_VM_Version::vm_info_string()
  4193                );
  4194   st->cr();
  4196 #ifndef SERIALGC
  4197   // Dump concurrent locks
  4198   ConcurrentLocksDump concurrent_locks;
  4199   if (print_concurrent_locks) {
  4200     concurrent_locks.dump_at_safepoint();
  4202 #endif // SERIALGC
  4204   ALL_JAVA_THREADS(p) {
  4205     ResourceMark rm;
  4206     p->print_on(st);
  4207     if (print_stacks) {
  4208       if (internal_format) {
  4209         p->trace_stack();
  4210       } else {
  4211         p->print_stack_on(st);
  4214     st->cr();
  4215 #ifndef SERIALGC
  4216     if (print_concurrent_locks) {
  4217       concurrent_locks.print_locks_on(p, st);
  4219 #endif // SERIALGC
  4222   VMThread::vm_thread()->print_on(st);
  4223   st->cr();
  4224   Universe::heap()->print_gc_threads_on(st);
  4225   WatcherThread* wt = WatcherThread::watcher_thread();
  4226   if (wt != NULL) wt->print_on(st);
  4227   st->cr();
  4228   CompileBroker::print_compiler_threads_on(st);
  4229   st->flush();
  4232 // Threads::print_on_error() is called by fatal error handler. It's possible
  4233 // that VM is not at safepoint and/or current thread is inside signal handler.
  4234 // Don't print stack trace, as the stack may not be walkable. Don't allocate
  4235 // memory (even in resource area), it might deadlock the error handler.
  4236 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
  4237   bool found_current = false;
  4238   st->print_cr("Java Threads: ( => current thread )");
  4239   ALL_JAVA_THREADS(thread) {
  4240     bool is_current = (current == thread);
  4241     found_current = found_current || is_current;
  4243     st->print("%s", is_current ? "=>" : "  ");
  4245     st->print(PTR_FORMAT, thread);
  4246     st->print(" ");
  4247     thread->print_on_error(st, buf, buflen);
  4248     st->cr();
  4250   st->cr();
  4252   st->print_cr("Other Threads:");
  4253   if (VMThread::vm_thread()) {
  4254     bool is_current = (current == VMThread::vm_thread());
  4255     found_current = found_current || is_current;
  4256     st->print("%s", current == VMThread::vm_thread() ? "=>" : "  ");
  4258     st->print(PTR_FORMAT, VMThread::vm_thread());
  4259     st->print(" ");
  4260     VMThread::vm_thread()->print_on_error(st, buf, buflen);
  4261     st->cr();
  4263   WatcherThread* wt = WatcherThread::watcher_thread();
  4264   if (wt != NULL) {
  4265     bool is_current = (current == wt);
  4266     found_current = found_current || is_current;
  4267     st->print("%s", is_current ? "=>" : "  ");
  4269     st->print(PTR_FORMAT, wt);
  4270     st->print(" ");
  4271     wt->print_on_error(st, buf, buflen);
  4272     st->cr();
  4274   if (!found_current) {
  4275     st->cr();
  4276     st->print("=>" PTR_FORMAT " (exited) ", current);
  4277     current->print_on_error(st, buf, buflen);
  4278     st->cr();
  4282 // Internal SpinLock and Mutex
  4283 // Based on ParkEvent
  4285 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
  4286 //
  4287 // We employ SpinLocks _only for low-contention, fixed-length
  4288 // short-duration critical sections where we're concerned
  4289 // about native mutex_t or HotSpot Mutex:: latency.
  4290 // The mux construct provides a spin-then-block mutual exclusion
  4291 // mechanism.
  4292 //
  4293 // Testing has shown that contention on the ListLock guarding gFreeList
  4294 // is common.  If we implement ListLock as a simple SpinLock it's common
  4295 // for the JVM to devolve to yielding with little progress.  This is true
  4296 // despite the fact that the critical sections protected by ListLock are
  4297 // extremely short.
  4298 //
  4299 // TODO-FIXME: ListLock should be of type SpinLock.
  4300 // We should make this a 1st-class type, integrated into the lock
  4301 // hierarchy as leaf-locks.  Critically, the SpinLock structure
  4302 // should have sufficient padding to avoid false-sharing and excessive
  4303 // cache-coherency traffic.
  4306 typedef volatile int SpinLockT ;
  4308 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
  4309   if (Atomic::cmpxchg (1, adr, 0) == 0) {
  4310      return ;   // normal fast-path return
  4313   // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
  4314   TEVENT (SpinAcquire - ctx) ;
  4315   int ctr = 0 ;
  4316   int Yields = 0 ;
  4317   for (;;) {
  4318      while (*adr != 0) {
  4319         ++ctr ;
  4320         if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
  4321            if (Yields > 5) {
  4322              // Consider using a simple NakedSleep() instead.
  4323              // Then SpinAcquire could be called by non-JVM threads
  4324              Thread::current()->_ParkEvent->park(1) ;
  4325            } else {
  4326              os::NakedYield() ;
  4327              ++Yields ;
  4329         } else {
  4330            SpinPause() ;
  4333      if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
  4337 void Thread::SpinRelease (volatile int * adr) {
  4338   assert (*adr != 0, "invariant") ;
  4339   OrderAccess::fence() ;      // guarantee at least release consistency.
  4340   // Roach-motel semantics.
  4341   // It's safe if subsequent LDs and STs float "up" into the critical section,
  4342   // but prior LDs and STs within the critical section can't be allowed
  4343   // to reorder or float past the ST that releases the lock.
  4344   *adr = 0 ;
  4347 // muxAcquire and muxRelease:
  4348 //
  4349 // *  muxAcquire and muxRelease support a single-word lock-word construct.
  4350 //    The LSB of the word is set IFF the lock is held.
  4351 //    The remainder of the word points to the head of a singly-linked list
  4352 //    of threads blocked on the lock.
  4353 //
  4354 // *  The current implementation of muxAcquire-muxRelease uses its own
  4355 //    dedicated Thread._MuxEvent instance.  If we're interested in
  4356 //    minimizing the peak number of extant ParkEvent instances then
  4357 //    we could eliminate _MuxEvent and "borrow" _ParkEvent as long
  4358 //    as certain invariants were satisfied.  Specifically, care would need
  4359 //    to be taken with regards to consuming unpark() "permits".
  4360 //    A safe rule of thumb is that a thread would never call muxAcquire()
  4361 //    if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
  4362 //    park().  Otherwise the _ParkEvent park() operation in muxAcquire() could
  4363 //    consume an unpark() permit intended for monitorenter, for instance.
  4364 //    One way around this would be to widen the restricted-range semaphore
  4365 //    implemented in park().  Another alternative would be to provide
  4366 //    multiple instances of the PlatformEvent() for each thread.  One
  4367 //    instance would be dedicated to muxAcquire-muxRelease, for instance.
  4368 //
  4369 // *  Usage:
  4370 //    -- Only as leaf locks
  4371 //    -- for short-term locking only as muxAcquire does not perform
  4372 //       thread state transitions.
  4373 //
  4374 // Alternatives:
  4375 // *  We could implement muxAcquire and muxRelease with MCS or CLH locks
  4376 //    but with parking or spin-then-park instead of pure spinning.
  4377 // *  Use Taura-Oyama-Yonenzawa locks.
  4378 // *  It's possible to construct a 1-0 lock if we encode the lockword as
  4379 //    (List,LockByte).  Acquire will CAS the full lockword while Release
  4380 //    will STB 0 into the LockByte.  The 1-0 scheme admits stranding, so
  4381 //    acquiring threads use timers (ParkTimed) to detect and recover from
  4382 //    the stranding window.  Thread/Node structures must be aligned on 256-byte
  4383 //    boundaries by using placement-new.
  4384 // *  Augment MCS with advisory back-link fields maintained with CAS().
  4385 //    Pictorially:  LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
  4386 //    The validity of the backlinks must be ratified before we trust the value.
  4387 //    If the backlinks are invalid the exiting thread must back-track through the
  4388 //    the forward links, which are always trustworthy.
  4389 // *  Add a successor indication.  The LockWord is currently encoded as
  4390 //    (List, LOCKBIT:1).  We could also add a SUCCBIT or an explicit _succ variable
  4391 //    to provide the usual futile-wakeup optimization.
  4392 //    See RTStt for details.
  4393 // *  Consider schedctl.sc_nopreempt to cover the critical section.
  4394 //
  4397 typedef volatile intptr_t MutexT ;      // Mux Lock-word
  4398 enum MuxBits { LOCKBIT = 1 } ;
  4400 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
  4401   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
  4402   if (w == 0) return ;
  4403   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
  4404      return ;
  4407   TEVENT (muxAcquire - Contention) ;
  4408   ParkEvent * const Self = Thread::current()->_MuxEvent ;
  4409   assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
  4410   for (;;) {
  4411      int its = (os::is_MP() ? 100 : 0) + 1 ;
  4413      // Optional spin phase: spin-then-park strategy
  4414      while (--its >= 0) {
  4415        w = *Lock ;
  4416        if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
  4417           return ;
  4421      Self->reset() ;
  4422      Self->OnList = intptr_t(Lock) ;
  4423      // The following fence() isn't _strictly necessary as the subsequent
  4424      // CAS() both serializes execution and ratifies the fetched *Lock value.
  4425      OrderAccess::fence();
  4426      for (;;) {
  4427         w = *Lock ;
  4428         if ((w & LOCKBIT) == 0) {
  4429             if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
  4430                 Self->OnList = 0 ;   // hygiene - allows stronger asserts
  4431                 return ;
  4433             continue ;      // Interference -- *Lock changed -- Just retry
  4435         assert (w & LOCKBIT, "invariant") ;
  4436         Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
  4437         if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
  4440      while (Self->OnList != 0) {
  4441         Self->park() ;
  4446 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
  4447   intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
  4448   if (w == 0) return ;
  4449   if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
  4450     return ;
  4453   TEVENT (muxAcquire - Contention) ;
  4454   ParkEvent * ReleaseAfter = NULL ;
  4455   if (ev == NULL) {
  4456     ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
  4458   assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
  4459   for (;;) {
  4460     guarantee (ev->OnList == 0, "invariant") ;
  4461     int its = (os::is_MP() ? 100 : 0) + 1 ;
  4463     // Optional spin phase: spin-then-park strategy
  4464     while (--its >= 0) {
  4465       w = *Lock ;
  4466       if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
  4467         if (ReleaseAfter != NULL) {
  4468           ParkEvent::Release (ReleaseAfter) ;
  4470         return ;
  4474     ev->reset() ;
  4475     ev->OnList = intptr_t(Lock) ;
  4476     // The following fence() isn't _strictly necessary as the subsequent
  4477     // CAS() both serializes execution and ratifies the fetched *Lock value.
  4478     OrderAccess::fence();
  4479     for (;;) {
  4480       w = *Lock ;
  4481       if ((w & LOCKBIT) == 0) {
  4482         if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
  4483           ev->OnList = 0 ;
  4484           // We call ::Release while holding the outer lock, thus
  4485           // artificially lengthening the critical section.
  4486           // Consider deferring the ::Release() until the subsequent unlock(),
  4487           // after we've dropped the outer lock.
  4488           if (ReleaseAfter != NULL) {
  4489             ParkEvent::Release (ReleaseAfter) ;
  4491           return ;
  4493         continue ;      // Interference -- *Lock changed -- Just retry
  4495       assert (w & LOCKBIT, "invariant") ;
  4496       ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
  4497       if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
  4500     while (ev->OnList != 0) {
  4501       ev->park() ;
  4506 // Release() must extract a successor from the list and then wake that thread.
  4507 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
  4508 // similar to that used by ParkEvent::Allocate() and ::Release().  DMR-based
  4509 // Release() would :
  4510 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
  4511 // (B) Extract a successor from the private list "in-hand"
  4512 // (C) attempt to CAS() the residual back into *Lock over null.
  4513 //     If there were any newly arrived threads and the CAS() would fail.
  4514 //     In that case Release() would detach the RATs, re-merge the list in-hand
  4515 //     with the RATs and repeat as needed.  Alternately, Release() might
  4516 //     detach and extract a successor, but then pass the residual list to the wakee.
  4517 //     The wakee would be responsible for reattaching and remerging before it
  4518 //     competed for the lock.
  4519 //
  4520 // Both "pop" and DMR are immune from ABA corruption -- there can be
  4521 // multiple concurrent pushers, but only one popper or detacher.
  4522 // This implementation pops from the head of the list.  This is unfair,
  4523 // but tends to provide excellent throughput as hot threads remain hot.
  4524 // (We wake recently run threads first).
  4526 void Thread::muxRelease (volatile intptr_t * Lock)  {
  4527   for (;;) {
  4528     const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
  4529     assert (w & LOCKBIT, "invariant") ;
  4530     if (w == LOCKBIT) return ;
  4531     ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
  4532     assert (List != NULL, "invariant") ;
  4533     assert (List->OnList == intptr_t(Lock), "invariant") ;
  4534     ParkEvent * nxt = List->ListNext ;
  4536     // The following CAS() releases the lock and pops the head element.
  4537     if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
  4538       continue ;
  4540     List->OnList = 0 ;
  4541     OrderAccess::fence() ;
  4542     List->unpark () ;
  4543     return ;
  4548 void Threads::verify() {
  4549   ALL_JAVA_THREADS(p) {
  4550     p->verify();
  4552   VMThread* thread = VMThread::vm_thread();
  4553   if (thread != NULL) thread->verify();

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