Mon, 17 Sep 2012 10:20:04 -0400
7190089: NMT ON: NMT failed assertion on thread's stack base address
Summary: Solaris only, record stack info to NMT after stack size adjustment was made for primordial threads
Reviewed-by: kvn, acorn, coleenp
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/metaspaceShared.hpp"
38 #include "memory/oopFactory.hpp"
39 #include "memory/universe.inline.hpp"
40 #include "oops/instanceKlass.hpp"
41 #include "oops/objArrayOop.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "oops/symbol.hpp"
44 #include "prims/jvm_misc.hpp"
45 #include "prims/jvmtiExport.hpp"
46 #include "prims/jvmtiThreadState.hpp"
47 #include "prims/privilegedStack.hpp"
48 #include "runtime/aprofiler.hpp"
49 #include "runtime/arguments.hpp"
50 #include "runtime/biasedLocking.hpp"
51 #include "runtime/deoptimization.hpp"
52 #include "runtime/fprofiler.hpp"
53 #include "runtime/frame.inline.hpp"
54 #include "runtime/init.hpp"
55 #include "runtime/interfaceSupport.hpp"
56 #include "runtime/java.hpp"
57 #include "runtime/javaCalls.hpp"
58 #include "runtime/jniPeriodicChecker.hpp"
59 #include "runtime/memprofiler.hpp"
60 #include "runtime/mutexLocker.hpp"
61 #include "runtime/objectMonitor.hpp"
62 #include "runtime/osThread.hpp"
63 #include "runtime/safepoint.hpp"
64 #include "runtime/sharedRuntime.hpp"
65 #include "runtime/statSampler.hpp"
66 #include "runtime/stubRoutines.hpp"
67 #include "runtime/task.hpp"
68 #include "runtime/threadCritical.hpp"
69 #include "runtime/threadLocalStorage.hpp"
70 #include "runtime/vframe.hpp"
71 #include "runtime/vframeArray.hpp"
72 #include "runtime/vframe_hp.hpp"
73 #include "runtime/vmThread.hpp"
74 #include "runtime/vm_operations.hpp"
75 #include "services/attachListener.hpp"
76 #include "services/management.hpp"
77 #include "services/memTracker.hpp"
78 #include "services/threadService.hpp"
79 #include "trace/traceEventTypes.hpp"
80 #include "utilities/defaultStream.hpp"
81 #include "utilities/dtrace.hpp"
82 #include "utilities/events.hpp"
83 #include "utilities/preserveException.hpp"
84 #ifdef TARGET_OS_FAMILY_linux
85 # include "os_linux.inline.hpp"
86 # include "thread_linux.inline.hpp"
87 #endif
88 #ifdef TARGET_OS_FAMILY_solaris
89 # include "os_solaris.inline.hpp"
90 # include "thread_solaris.inline.hpp"
91 #endif
92 #ifdef TARGET_OS_FAMILY_windows
93 # include "os_windows.inline.hpp"
94 # include "thread_windows.inline.hpp"
95 #endif
96 #ifdef TARGET_OS_FAMILY_bsd
97 # include "os_bsd.inline.hpp"
98 # include "thread_bsd.inline.hpp"
99 #endif
100 #ifndef SERIALGC
101 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
102 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
103 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
104 #endif
105 #ifdef COMPILER1
106 #include "c1/c1_Compiler.hpp"
107 #endif
108 #ifdef COMPILER2
109 #include "opto/c2compiler.hpp"
110 #include "opto/idealGraphPrinter.hpp"
111 #endif
113 #ifdef DTRACE_ENABLED
115 // Only bother with this argument setup if dtrace is available
117 #ifndef USDT2
118 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
119 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
120 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
121 intptr_t, intptr_t, bool);
122 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
123 intptr_t, intptr_t, bool);
125 #define DTRACE_THREAD_PROBE(probe, javathread) \
126 { \
127 ResourceMark rm(this); \
128 int len = 0; \
129 const char* name = (javathread)->get_thread_name(); \
130 len = strlen(name); \
131 HS_DTRACE_PROBE5(hotspot, thread__##probe, \
132 name, len, \
133 java_lang_Thread::thread_id((javathread)->threadObj()), \
134 (javathread)->osthread()->thread_id(), \
135 java_lang_Thread::is_daemon((javathread)->threadObj())); \
136 }
138 #else /* USDT2 */
140 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_PROBE_START
141 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_PROBE_STOP
143 #define DTRACE_THREAD_PROBE(probe, javathread) \
144 { \
145 ResourceMark rm(this); \
146 int len = 0; \
147 const char* name = (javathread)->get_thread_name(); \
148 len = strlen(name); \
149 HOTSPOT_THREAD_PROBE_##probe( /* probe = start, stop */ \
150 (char *) name, len, \
151 java_lang_Thread::thread_id((javathread)->threadObj()), \
152 (uintptr_t) (javathread)->osthread()->thread_id(), \
153 java_lang_Thread::is_daemon((javathread)->threadObj())); \
154 }
156 #endif /* USDT2 */
158 #else // ndef DTRACE_ENABLED
160 #define DTRACE_THREAD_PROBE(probe, javathread)
162 #endif // ndef DTRACE_ENABLED
165 // Class hierarchy
166 // - Thread
167 // - VMThread
168 // - WatcherThread
169 // - ConcurrentMarkSweepThread
170 // - JavaThread
171 // - CompilerThread
173 // ======= Thread ========
174 // Support for forcing alignment of thread objects for biased locking
175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
176 if (UseBiasedLocking) {
177 const int alignment = markOopDesc::biased_lock_alignment;
178 size_t aligned_size = size + (alignment - sizeof(intptr_t));
179 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
180 : os::malloc(aligned_size, flags, CURRENT_PC);
181 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
184 "JavaThread alignment code overflowed allocated storage");
185 if (TraceBiasedLocking) {
186 if (aligned_addr != real_malloc_addr)
187 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
188 real_malloc_addr, aligned_addr);
189 }
190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
191 return aligned_addr;
192 } else {
193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
194 : os::malloc(size, flags, CURRENT_PC);
195 }
196 }
198 void Thread::operator delete(void* p) {
199 if (UseBiasedLocking) {
200 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
201 FreeHeap(real_malloc_addr, mtThread);
202 } else {
203 FreeHeap(p, mtThread);
204 }
205 }
208 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
209 // JavaThread
212 Thread::Thread() {
213 // stack and get_thread
214 set_stack_base(NULL);
215 set_stack_size(0);
216 set_self_raw_id(0);
217 set_lgrp_id(-1);
219 // allocated data structures
220 set_osthread(NULL);
221 set_resource_area(new (mtThread)ResourceArea());
222 set_handle_area(new (mtThread) HandleArea(NULL));
223 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(300, true));
224 set_active_handles(NULL);
225 set_free_handle_block(NULL);
226 set_last_handle_mark(NULL);
228 // This initial value ==> never claimed.
229 _oops_do_parity = 0;
231 // the handle mark links itself to last_handle_mark
232 new HandleMark(this);
234 // plain initialization
235 debug_only(_owned_locks = NULL;)
236 debug_only(_allow_allocation_count = 0;)
237 NOT_PRODUCT(_allow_safepoint_count = 0;)
238 NOT_PRODUCT(_skip_gcalot = false;)
239 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
240 _jvmti_env_iteration_count = 0;
241 set_allocated_bytes(0);
242 set_trace_buffer(NULL);
243 _vm_operation_started_count = 0;
244 _vm_operation_completed_count = 0;
245 _current_pending_monitor = NULL;
246 _current_pending_monitor_is_from_java = true;
247 _current_waiting_monitor = NULL;
248 _num_nested_signal = 0;
249 omFreeList = NULL ;
250 omFreeCount = 0 ;
251 omFreeProvision = 32 ;
252 omInUseList = NULL ;
253 omInUseCount = 0 ;
255 #ifdef ASSERT
256 _visited_for_critical_count = false;
257 #endif
259 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
260 _suspend_flags = 0;
262 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
263 _hashStateX = os::random() ;
264 _hashStateY = 842502087 ;
265 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
266 _hashStateW = 273326509 ;
268 _OnTrap = 0 ;
269 _schedctl = NULL ;
270 _Stalled = 0 ;
271 _TypeTag = 0x2BAD ;
273 // Many of the following fields are effectively final - immutable
274 // Note that nascent threads can't use the Native Monitor-Mutex
275 // construct until the _MutexEvent is initialized ...
276 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
277 // we might instead use a stack of ParkEvents that we could provision on-demand.
278 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
279 // and ::Release()
280 _ParkEvent = ParkEvent::Allocate (this) ;
281 _SleepEvent = ParkEvent::Allocate (this) ;
282 _MutexEvent = ParkEvent::Allocate (this) ;
283 _MuxEvent = ParkEvent::Allocate (this) ;
285 #ifdef CHECK_UNHANDLED_OOPS
286 if (CheckUnhandledOops) {
287 _unhandled_oops = new UnhandledOops(this);
288 }
289 #endif // CHECK_UNHANDLED_OOPS
290 #ifdef ASSERT
291 if (UseBiasedLocking) {
292 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
293 assert(this == _real_malloc_address ||
294 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
295 "bug in forced alignment of thread objects");
296 }
297 #endif /* ASSERT */
298 }
300 void Thread::initialize_thread_local_storage() {
301 // Note: Make sure this method only calls
302 // non-blocking operations. Otherwise, it might not work
303 // with the thread-startup/safepoint interaction.
305 // During Java thread startup, safepoint code should allow this
306 // method to complete because it may need to allocate memory to
307 // store information for the new thread.
309 // initialize structure dependent on thread local storage
310 ThreadLocalStorage::set_thread(this);
311 }
313 void Thread::record_stack_base_and_size() {
314 set_stack_base(os::current_stack_base());
315 set_stack_size(os::current_stack_size());
316 // CR 7190089: on Solaris, primordial thread's stack is adjusted
317 // in initialize_thread(). Without the adjustment, stack size is
318 // incorrect if stack is set to unlimited (ulimit -s unlimited).
319 // So far, only Solaris has real implementation of initialize_thread().
320 //
321 // set up any platform-specific state.
322 os::initialize_thread(this);
324 // record thread's native stack, stack grows downward
325 if (MemTracker::is_on()) {
326 address stack_low_addr = stack_base() - stack_size();
327 MemTracker::record_thread_stack(stack_low_addr, stack_size(), this,
328 CURRENT_PC);
329 }
330 }
333 Thread::~Thread() {
334 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
335 ObjectSynchronizer::omFlush (this) ;
337 // stack_base can be NULL if the thread is never started or exited before
338 // record_stack_base_and_size called. Although, we would like to ensure
339 // that all started threads do call record_stack_base_and_size(), there is
340 // not proper way to enforce that.
341 if (_stack_base != NULL) {
342 address low_stack_addr = stack_base() - stack_size();
343 MemTracker::release_thread_stack(low_stack_addr, stack_size(), this);
344 }
346 // deallocate data structures
347 delete resource_area();
348 // since the handle marks are using the handle area, we have to deallocated the root
349 // handle mark before deallocating the thread's handle area,
350 assert(last_handle_mark() != NULL, "check we have an element");
351 delete last_handle_mark();
352 assert(last_handle_mark() == NULL, "check we have reached the end");
354 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
355 // We NULL out the fields for good hygiene.
356 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
357 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
358 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
359 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
361 delete handle_area();
362 delete metadata_handles();
364 // osthread() can be NULL, if creation of thread failed.
365 if (osthread() != NULL) os::free_thread(osthread());
367 delete _SR_lock;
369 // clear thread local storage if the Thread is deleting itself
370 if (this == Thread::current()) {
371 ThreadLocalStorage::set_thread(NULL);
372 } else {
373 // In the case where we're not the current thread, invalidate all the
374 // caches in case some code tries to get the current thread or the
375 // thread that was destroyed, and gets stale information.
376 ThreadLocalStorage::invalidate_all();
377 }
378 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
379 }
381 // NOTE: dummy function for assertion purpose.
382 void Thread::run() {
383 ShouldNotReachHere();
384 }
386 #ifdef ASSERT
387 // Private method to check for dangling thread pointer
388 void check_for_dangling_thread_pointer(Thread *thread) {
389 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
390 "possibility of dangling Thread pointer");
391 }
392 #endif
395 #ifndef PRODUCT
396 // Tracing method for basic thread operations
397 void Thread::trace(const char* msg, const Thread* const thread) {
398 if (!TraceThreadEvents) return;
399 ResourceMark rm;
400 ThreadCritical tc;
401 const char *name = "non-Java thread";
402 int prio = -1;
403 if (thread->is_Java_thread()
404 && !thread->is_Compiler_thread()) {
405 // The Threads_lock must be held to get information about
406 // this thread but may not be in some situations when
407 // tracing thread events.
408 bool release_Threads_lock = false;
409 if (!Threads_lock->owned_by_self()) {
410 Threads_lock->lock();
411 release_Threads_lock = true;
412 }
413 JavaThread* jt = (JavaThread *)thread;
414 name = (char *)jt->get_thread_name();
415 oop thread_oop = jt->threadObj();
416 if (thread_oop != NULL) {
417 prio = java_lang_Thread::priority(thread_oop);
418 }
419 if (release_Threads_lock) {
420 Threads_lock->unlock();
421 }
422 }
423 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
424 }
425 #endif
428 ThreadPriority Thread::get_priority(const Thread* const thread) {
429 trace("get priority", thread);
430 ThreadPriority priority;
431 // Can return an error!
432 (void)os::get_priority(thread, priority);
433 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
434 return priority;
435 }
437 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
438 trace("set priority", thread);
439 debug_only(check_for_dangling_thread_pointer(thread);)
440 // Can return an error!
441 (void)os::set_priority(thread, priority);
442 }
445 void Thread::start(Thread* thread) {
446 trace("start", thread);
447 // Start is different from resume in that its safety is guaranteed by context or
448 // being called from a Java method synchronized on the Thread object.
449 if (!DisableStartThread) {
450 if (thread->is_Java_thread()) {
451 // Initialize the thread state to RUNNABLE before starting this thread.
452 // Can not set it after the thread started because we do not know the
453 // exact thread state at that time. It could be in MONITOR_WAIT or
454 // in SLEEPING or some other state.
455 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
456 java_lang_Thread::RUNNABLE);
457 }
458 os::start_thread(thread);
459 }
460 }
462 // Enqueue a VM_Operation to do the job for us - sometime later
463 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
464 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
465 VMThread::execute(vm_stop);
466 }
469 //
470 // Check if an external suspend request has completed (or has been
471 // cancelled). Returns true if the thread is externally suspended and
472 // false otherwise.
473 //
474 // The bits parameter returns information about the code path through
475 // the routine. Useful for debugging:
476 //
477 // set in is_ext_suspend_completed():
478 // 0x00000001 - routine was entered
479 // 0x00000010 - routine return false at end
480 // 0x00000100 - thread exited (return false)
481 // 0x00000200 - suspend request cancelled (return false)
482 // 0x00000400 - thread suspended (return true)
483 // 0x00001000 - thread is in a suspend equivalent state (return true)
484 // 0x00002000 - thread is native and walkable (return true)
485 // 0x00004000 - thread is native_trans and walkable (needed retry)
486 //
487 // set in wait_for_ext_suspend_completion():
488 // 0x00010000 - routine was entered
489 // 0x00020000 - suspend request cancelled before loop (return false)
490 // 0x00040000 - thread suspended before loop (return true)
491 // 0x00080000 - suspend request cancelled in loop (return false)
492 // 0x00100000 - thread suspended in loop (return true)
493 // 0x00200000 - suspend not completed during retry loop (return false)
494 //
496 // Helper class for tracing suspend wait debug bits.
497 //
498 // 0x00000100 indicates that the target thread exited before it could
499 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
500 // 0x00080000 each indicate a cancelled suspend request so they don't
501 // count as wait failures either.
502 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
504 class TraceSuspendDebugBits : public StackObj {
505 private:
506 JavaThread * jt;
507 bool is_wait;
508 bool called_by_wait; // meaningful when !is_wait
509 uint32_t * bits;
511 public:
512 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
513 uint32_t *_bits) {
514 jt = _jt;
515 is_wait = _is_wait;
516 called_by_wait = _called_by_wait;
517 bits = _bits;
518 }
520 ~TraceSuspendDebugBits() {
521 if (!is_wait) {
522 #if 1
523 // By default, don't trace bits for is_ext_suspend_completed() calls.
524 // That trace is very chatty.
525 return;
526 #else
527 if (!called_by_wait) {
528 // If tracing for is_ext_suspend_completed() is enabled, then only
529 // trace calls to it from wait_for_ext_suspend_completion()
530 return;
531 }
532 #endif
533 }
535 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
536 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
537 MutexLocker ml(Threads_lock); // needed for get_thread_name()
538 ResourceMark rm;
540 tty->print_cr(
541 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
542 jt->get_thread_name(), *bits);
544 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
545 }
546 }
547 }
548 };
549 #undef DEBUG_FALSE_BITS
552 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
553 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
555 bool did_trans_retry = false; // only do thread_in_native_trans retry once
556 bool do_trans_retry; // flag to force the retry
558 *bits |= 0x00000001;
560 do {
561 do_trans_retry = false;
563 if (is_exiting()) {
564 // Thread is in the process of exiting. This is always checked
565 // first to reduce the risk of dereferencing a freed JavaThread.
566 *bits |= 0x00000100;
567 return false;
568 }
570 if (!is_external_suspend()) {
571 // Suspend request is cancelled. This is always checked before
572 // is_ext_suspended() to reduce the risk of a rogue resume
573 // confusing the thread that made the suspend request.
574 *bits |= 0x00000200;
575 return false;
576 }
578 if (is_ext_suspended()) {
579 // thread is suspended
580 *bits |= 0x00000400;
581 return true;
582 }
584 // Now that we no longer do hard suspends of threads running
585 // native code, the target thread can be changing thread state
586 // while we are in this routine:
587 //
588 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
589 //
590 // We save a copy of the thread state as observed at this moment
591 // and make our decision about suspend completeness based on the
592 // copy. This closes the race where the thread state is seen as
593 // _thread_in_native_trans in the if-thread_blocked check, but is
594 // seen as _thread_blocked in if-thread_in_native_trans check.
595 JavaThreadState save_state = thread_state();
597 if (save_state == _thread_blocked && is_suspend_equivalent()) {
598 // If the thread's state is _thread_blocked and this blocking
599 // condition is known to be equivalent to a suspend, then we can
600 // consider the thread to be externally suspended. This means that
601 // the code that sets _thread_blocked has been modified to do
602 // self-suspension if the blocking condition releases. We also
603 // used to check for CONDVAR_WAIT here, but that is now covered by
604 // the _thread_blocked with self-suspension check.
605 //
606 // Return true since we wouldn't be here unless there was still an
607 // external suspend request.
608 *bits |= 0x00001000;
609 return true;
610 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
611 // Threads running native code will self-suspend on native==>VM/Java
612 // transitions. If its stack is walkable (should always be the case
613 // unless this function is called before the actual java_suspend()
614 // call), then the wait is done.
615 *bits |= 0x00002000;
616 return true;
617 } else if (!called_by_wait && !did_trans_retry &&
618 save_state == _thread_in_native_trans &&
619 frame_anchor()->walkable()) {
620 // The thread is transitioning from thread_in_native to another
621 // thread state. check_safepoint_and_suspend_for_native_trans()
622 // will force the thread to self-suspend. If it hasn't gotten
623 // there yet we may have caught the thread in-between the native
624 // code check above and the self-suspend. Lucky us. If we were
625 // called by wait_for_ext_suspend_completion(), then it
626 // will be doing the retries so we don't have to.
627 //
628 // Since we use the saved thread state in the if-statement above,
629 // there is a chance that the thread has already transitioned to
630 // _thread_blocked by the time we get here. In that case, we will
631 // make a single unnecessary pass through the logic below. This
632 // doesn't hurt anything since we still do the trans retry.
634 *bits |= 0x00004000;
636 // Once the thread leaves thread_in_native_trans for another
637 // thread state, we break out of this retry loop. We shouldn't
638 // need this flag to prevent us from getting back here, but
639 // sometimes paranoia is good.
640 did_trans_retry = true;
642 // We wait for the thread to transition to a more usable state.
643 for (int i = 1; i <= SuspendRetryCount; i++) {
644 // We used to do an "os::yield_all(i)" call here with the intention
645 // that yielding would increase on each retry. However, the parameter
646 // is ignored on Linux which means the yield didn't scale up. Waiting
647 // on the SR_lock below provides a much more predictable scale up for
648 // the delay. It also provides a simple/direct point to check for any
649 // safepoint requests from the VMThread
651 // temporarily drops SR_lock while doing wait with safepoint check
652 // (if we're a JavaThread - the WatcherThread can also call this)
653 // and increase delay with each retry
654 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
656 // check the actual thread state instead of what we saved above
657 if (thread_state() != _thread_in_native_trans) {
658 // the thread has transitioned to another thread state so
659 // try all the checks (except this one) one more time.
660 do_trans_retry = true;
661 break;
662 }
663 } // end retry loop
666 }
667 } while (do_trans_retry);
669 *bits |= 0x00000010;
670 return false;
671 }
673 //
674 // Wait for an external suspend request to complete (or be cancelled).
675 // Returns true if the thread is externally suspended and false otherwise.
676 //
677 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
678 uint32_t *bits) {
679 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
680 false /* !called_by_wait */, bits);
682 // local flag copies to minimize SR_lock hold time
683 bool is_suspended;
684 bool pending;
685 uint32_t reset_bits;
687 // set a marker so is_ext_suspend_completed() knows we are the caller
688 *bits |= 0x00010000;
690 // We use reset_bits to reinitialize the bits value at the top of
691 // each retry loop. This allows the caller to make use of any
692 // unused bits for their own marking purposes.
693 reset_bits = *bits;
695 {
696 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
697 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
698 delay, bits);
699 pending = is_external_suspend();
700 }
701 // must release SR_lock to allow suspension to complete
703 if (!pending) {
704 // A cancelled suspend request is the only false return from
705 // is_ext_suspend_completed() that keeps us from entering the
706 // retry loop.
707 *bits |= 0x00020000;
708 return false;
709 }
711 if (is_suspended) {
712 *bits |= 0x00040000;
713 return true;
714 }
716 for (int i = 1; i <= retries; i++) {
717 *bits = reset_bits; // reinit to only track last retry
719 // We used to do an "os::yield_all(i)" call here with the intention
720 // that yielding would increase on each retry. However, the parameter
721 // is ignored on Linux which means the yield didn't scale up. Waiting
722 // on the SR_lock below provides a much more predictable scale up for
723 // the delay. It also provides a simple/direct point to check for any
724 // safepoint requests from the VMThread
726 {
727 MutexLocker ml(SR_lock());
728 // wait with safepoint check (if we're a JavaThread - the WatcherThread
729 // can also call this) and increase delay with each retry
730 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
732 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
733 delay, bits);
735 // It is possible for the external suspend request to be cancelled
736 // (by a resume) before the actual suspend operation is completed.
737 // Refresh our local copy to see if we still need to wait.
738 pending = is_external_suspend();
739 }
741 if (!pending) {
742 // A cancelled suspend request is the only false return from
743 // is_ext_suspend_completed() that keeps us from staying in the
744 // retry loop.
745 *bits |= 0x00080000;
746 return false;
747 }
749 if (is_suspended) {
750 *bits |= 0x00100000;
751 return true;
752 }
753 } // end retry loop
755 // thread did not suspend after all our retries
756 *bits |= 0x00200000;
757 return false;
758 }
760 #ifndef PRODUCT
761 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
763 // This should not need to be atomic as the only way for simultaneous
764 // updates is via interrupts. Even then this should be rare or non-existant
765 // and we don't care that much anyway.
767 int index = _jmp_ring_index;
768 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
769 _jmp_ring[index]._target = (intptr_t) target;
770 _jmp_ring[index]._instruction = (intptr_t) instr;
771 _jmp_ring[index]._file = file;
772 _jmp_ring[index]._line = line;
773 }
774 #endif /* PRODUCT */
776 // Called by flat profiler
777 // Callers have already called wait_for_ext_suspend_completion
778 // The assertion for that is currently too complex to put here:
779 bool JavaThread::profile_last_Java_frame(frame* _fr) {
780 bool gotframe = false;
781 // self suspension saves needed state.
782 if (has_last_Java_frame() && _anchor.walkable()) {
783 *_fr = pd_last_frame();
784 gotframe = true;
785 }
786 return gotframe;
787 }
789 void Thread::interrupt(Thread* thread) {
790 trace("interrupt", thread);
791 debug_only(check_for_dangling_thread_pointer(thread);)
792 os::interrupt(thread);
793 }
795 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
796 trace("is_interrupted", thread);
797 debug_only(check_for_dangling_thread_pointer(thread);)
798 // Note: If clear_interrupted==false, this simply fetches and
799 // returns the value of the field osthread()->interrupted().
800 return os::is_interrupted(thread, clear_interrupted);
801 }
804 // GC Support
805 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
806 jint thread_parity = _oops_do_parity;
807 if (thread_parity != strong_roots_parity) {
808 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
809 if (res == thread_parity) {
810 return true;
811 } else {
812 guarantee(res == strong_roots_parity, "Or else what?");
813 assert(SharedHeap::heap()->workers()->active_workers() > 0,
814 "Should only fail when parallel.");
815 return false;
816 }
817 }
818 assert(SharedHeap::heap()->workers()->active_workers() > 0,
819 "Should only fail when parallel.");
820 return false;
821 }
823 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
824 active_handles()->oops_do(f);
825 // Do oop for ThreadShadow
826 f->do_oop((oop*)&_pending_exception);
827 handle_area()->oops_do(f);
828 }
830 void Thread::nmethods_do(CodeBlobClosure* cf) {
831 // no nmethods in a generic thread...
832 }
834 void Thread::metadata_do(void f(Metadata*)) {
835 if (metadata_handles() != NULL) {
836 for (int i = 0; i< metadata_handles()->length(); i++) {
837 f(metadata_handles()->at(i));
838 }
839 }
840 }
842 void Thread::print_on(outputStream* st) const {
843 // get_priority assumes osthread initialized
844 if (osthread() != NULL) {
845 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
846 osthread()->print_on(st);
847 }
848 debug_only(if (WizardMode) print_owned_locks_on(st);)
849 }
851 // Thread::print_on_error() is called by fatal error handler. Don't use
852 // any lock or allocate memory.
853 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
854 if (is_VM_thread()) st->print("VMThread");
855 else if (is_Compiler_thread()) st->print("CompilerThread");
856 else if (is_Java_thread()) st->print("JavaThread");
857 else if (is_GC_task_thread()) st->print("GCTaskThread");
858 else if (is_Watcher_thread()) st->print("WatcherThread");
859 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
860 else st->print("Thread");
862 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
863 _stack_base - _stack_size, _stack_base);
865 if (osthread()) {
866 st->print(" [id=%d]", osthread()->thread_id());
867 }
868 }
870 #ifdef ASSERT
871 void Thread::print_owned_locks_on(outputStream* st) const {
872 Monitor *cur = _owned_locks;
873 if (cur == NULL) {
874 st->print(" (no locks) ");
875 } else {
876 st->print_cr(" Locks owned:");
877 while(cur) {
878 cur->print_on(st);
879 cur = cur->next();
880 }
881 }
882 }
884 static int ref_use_count = 0;
886 bool Thread::owns_locks_but_compiled_lock() const {
887 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
888 if (cur != Compile_lock) return true;
889 }
890 return false;
891 }
894 #endif
896 #ifndef PRODUCT
898 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
899 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
900 // no threads which allow_vm_block's are held
901 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
902 // Check if current thread is allowed to block at a safepoint
903 if (!(_allow_safepoint_count == 0))
904 fatal("Possible safepoint reached by thread that does not allow it");
905 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
906 fatal("LEAF method calling lock?");
907 }
909 #ifdef ASSERT
910 if (potential_vm_operation && is_Java_thread()
911 && !Universe::is_bootstrapping()) {
912 // Make sure we do not hold any locks that the VM thread also uses.
913 // This could potentially lead to deadlocks
914 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
915 // Threads_lock is special, since the safepoint synchronization will not start before this is
916 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
917 // since it is used to transfer control between JavaThreads and the VMThread
918 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
919 if ( (cur->allow_vm_block() &&
920 cur != Threads_lock &&
921 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
922 cur != VMOperationRequest_lock &&
923 cur != VMOperationQueue_lock) ||
924 cur->rank() == Mutex::special) {
925 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
926 }
927 }
928 }
930 if (GCALotAtAllSafepoints) {
931 // We could enter a safepoint here and thus have a gc
932 InterfaceSupport::check_gc_alot();
933 }
934 #endif
935 }
936 #endif
938 bool Thread::is_in_stack(address adr) const {
939 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
940 address end = os::current_stack_pointer();
941 // Allow non Java threads to call this without stack_base
942 if (_stack_base == NULL) return true;
943 if (stack_base() >= adr && adr >= end) return true;
945 return false;
946 }
949 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
950 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
951 // used for compilation in the future. If that change is made, the need for these methods
952 // should be revisited, and they should be removed if possible.
954 bool Thread::is_lock_owned(address adr) const {
955 return on_local_stack(adr);
956 }
958 bool Thread::set_as_starting_thread() {
959 // NOTE: this must be called inside the main thread.
960 return os::create_main_thread((JavaThread*)this);
961 }
963 static void initialize_class(Symbol* class_name, TRAPS) {
964 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
965 InstanceKlass::cast(klass)->initialize(CHECK);
966 }
969 // Creates the initial ThreadGroup
970 static Handle create_initial_thread_group(TRAPS) {
971 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
972 instanceKlassHandle klass (THREAD, k);
974 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
975 {
976 JavaValue result(T_VOID);
977 JavaCalls::call_special(&result,
978 system_instance,
979 klass,
980 vmSymbols::object_initializer_name(),
981 vmSymbols::void_method_signature(),
982 CHECK_NH);
983 }
984 Universe::set_system_thread_group(system_instance());
986 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
987 {
988 JavaValue result(T_VOID);
989 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
990 JavaCalls::call_special(&result,
991 main_instance,
992 klass,
993 vmSymbols::object_initializer_name(),
994 vmSymbols::threadgroup_string_void_signature(),
995 system_instance,
996 string,
997 CHECK_NH);
998 }
999 return main_instance;
1000 }
1002 // Creates the initial Thread
1003 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
1004 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1005 instanceKlassHandle klass (THREAD, k);
1006 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
1008 java_lang_Thread::set_thread(thread_oop(), thread);
1009 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1010 thread->set_threadObj(thread_oop());
1012 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1014 JavaValue result(T_VOID);
1015 JavaCalls::call_special(&result, thread_oop,
1016 klass,
1017 vmSymbols::object_initializer_name(),
1018 vmSymbols::threadgroup_string_void_signature(),
1019 thread_group,
1020 string,
1021 CHECK_NULL);
1022 return thread_oop();
1023 }
1025 static void call_initializeSystemClass(TRAPS) {
1026 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1027 instanceKlassHandle klass (THREAD, k);
1029 JavaValue result(T_VOID);
1030 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
1031 vmSymbols::void_method_signature(), CHECK);
1032 }
1034 char java_runtime_name[128] = "";
1036 // extract the JRE name from sun.misc.Version.java_runtime_name
1037 static const char* get_java_runtime_name(TRAPS) {
1038 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1039 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1040 fieldDescriptor fd;
1041 bool found = k != NULL &&
1042 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1043 vmSymbols::string_signature(), &fd);
1044 if (found) {
1045 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1046 if (name_oop == NULL)
1047 return NULL;
1048 const char* name = java_lang_String::as_utf8_string(name_oop,
1049 java_runtime_name,
1050 sizeof(java_runtime_name));
1051 return name;
1052 } else {
1053 return NULL;
1054 }
1055 }
1057 // General purpose hook into Java code, run once when the VM is initialized.
1058 // The Java library method itself may be changed independently from the VM.
1059 static void call_postVMInitHook(TRAPS) {
1060 Klass* k = SystemDictionary::PostVMInitHook_klass();
1061 instanceKlassHandle klass (THREAD, k);
1062 if (klass.not_null()) {
1063 JavaValue result(T_VOID);
1064 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1065 vmSymbols::void_method_signature(),
1066 CHECK);
1067 }
1068 }
1070 static void reset_vm_info_property(TRAPS) {
1071 // the vm info string
1072 ResourceMark rm(THREAD);
1073 const char *vm_info = VM_Version::vm_info_string();
1075 // java.lang.System class
1076 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1077 instanceKlassHandle klass (THREAD, k);
1079 // setProperty arguments
1080 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1081 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1083 // return value
1084 JavaValue r(T_OBJECT);
1086 // public static String setProperty(String key, String value);
1087 JavaCalls::call_static(&r,
1088 klass,
1089 vmSymbols::setProperty_name(),
1090 vmSymbols::string_string_string_signature(),
1091 key_str,
1092 value_str,
1093 CHECK);
1094 }
1097 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1098 assert(thread_group.not_null(), "thread group should be specified");
1099 assert(threadObj() == NULL, "should only create Java thread object once");
1101 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1102 instanceKlassHandle klass (THREAD, k);
1103 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1105 java_lang_Thread::set_thread(thread_oop(), this);
1106 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1107 set_threadObj(thread_oop());
1109 JavaValue result(T_VOID);
1110 if (thread_name != NULL) {
1111 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1112 // Thread gets assigned specified name and null target
1113 JavaCalls::call_special(&result,
1114 thread_oop,
1115 klass,
1116 vmSymbols::object_initializer_name(),
1117 vmSymbols::threadgroup_string_void_signature(),
1118 thread_group, // Argument 1
1119 name, // Argument 2
1120 THREAD);
1121 } else {
1122 // Thread gets assigned name "Thread-nnn" and null target
1123 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1124 JavaCalls::call_special(&result,
1125 thread_oop,
1126 klass,
1127 vmSymbols::object_initializer_name(),
1128 vmSymbols::threadgroup_runnable_void_signature(),
1129 thread_group, // Argument 1
1130 Handle(), // Argument 2
1131 THREAD);
1132 }
1135 if (daemon) {
1136 java_lang_Thread::set_daemon(thread_oop());
1137 }
1139 if (HAS_PENDING_EXCEPTION) {
1140 return;
1141 }
1143 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1144 Handle threadObj(this, this->threadObj());
1146 JavaCalls::call_special(&result,
1147 thread_group,
1148 group,
1149 vmSymbols::add_method_name(),
1150 vmSymbols::thread_void_signature(),
1151 threadObj, // Arg 1
1152 THREAD);
1155 }
1157 // NamedThread -- non-JavaThread subclasses with multiple
1158 // uniquely named instances should derive from this.
1159 NamedThread::NamedThread() : Thread() {
1160 _name = NULL;
1161 _processed_thread = NULL;
1162 }
1164 NamedThread::~NamedThread() {
1165 if (_name != NULL) {
1166 FREE_C_HEAP_ARRAY(char, _name, mtThread);
1167 _name = NULL;
1168 }
1169 }
1171 void NamedThread::set_name(const char* format, ...) {
1172 guarantee(_name == NULL, "Only get to set name once.");
1173 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1174 guarantee(_name != NULL, "alloc failure");
1175 va_list ap;
1176 va_start(ap, format);
1177 jio_vsnprintf(_name, max_name_len, format, ap);
1178 va_end(ap);
1179 }
1181 // ======= WatcherThread ========
1183 // The watcher thread exists to simulate timer interrupts. It should
1184 // be replaced by an abstraction over whatever native support for
1185 // timer interrupts exists on the platform.
1187 WatcherThread* WatcherThread::_watcher_thread = NULL;
1188 volatile bool WatcherThread::_should_terminate = false;
1190 WatcherThread::WatcherThread() : Thread() {
1191 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1192 if (os::create_thread(this, os::watcher_thread)) {
1193 _watcher_thread = this;
1195 // Set the watcher thread to the highest OS priority which should not be
1196 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1197 // is created. The only normal thread using this priority is the reference
1198 // handler thread, which runs for very short intervals only.
1199 // If the VMThread's priority is not lower than the WatcherThread profiling
1200 // will be inaccurate.
1201 os::set_priority(this, MaxPriority);
1202 if (!DisableStartThread) {
1203 os::start_thread(this);
1204 }
1205 }
1206 }
1208 void WatcherThread::run() {
1209 assert(this == watcher_thread(), "just checking");
1211 this->record_stack_base_and_size();
1212 this->initialize_thread_local_storage();
1213 this->set_active_handles(JNIHandleBlock::allocate_block());
1214 while(!_should_terminate) {
1215 assert(watcher_thread() == Thread::current(), "thread consistency check");
1216 assert(watcher_thread() == this, "thread consistency check");
1218 // Calculate how long it'll be until the next PeriodicTask work
1219 // should be done, and sleep that amount of time.
1220 size_t time_to_wait = PeriodicTask::time_to_wait();
1222 // we expect this to timeout - we only ever get unparked when
1223 // we should terminate
1224 {
1225 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1227 jlong prev_time = os::javaTimeNanos();
1228 for (;;) {
1229 int res= _SleepEvent->park(time_to_wait);
1230 if (res == OS_TIMEOUT || _should_terminate)
1231 break;
1232 // spurious wakeup of some kind
1233 jlong now = os::javaTimeNanos();
1234 time_to_wait -= (now - prev_time) / 1000000;
1235 if (time_to_wait <= 0)
1236 break;
1237 prev_time = now;
1238 }
1239 }
1241 if (is_error_reported()) {
1242 // A fatal error has happened, the error handler(VMError::report_and_die)
1243 // should abort JVM after creating an error log file. However in some
1244 // rare cases, the error handler itself might deadlock. Here we try to
1245 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1246 //
1247 // This code is in WatcherThread because WatcherThread wakes up
1248 // periodically so the fatal error handler doesn't need to do anything;
1249 // also because the WatcherThread is less likely to crash than other
1250 // threads.
1252 for (;;) {
1253 if (!ShowMessageBoxOnError
1254 && (OnError == NULL || OnError[0] == '\0')
1255 && Arguments::abort_hook() == NULL) {
1256 os::sleep(this, 2 * 60 * 1000, false);
1257 fdStream err(defaultStream::output_fd());
1258 err.print_raw_cr("# [ timer expired, abort... ]");
1259 // skip atexit/vm_exit/vm_abort hooks
1260 os::die();
1261 }
1263 // Wake up 5 seconds later, the fatal handler may reset OnError or
1264 // ShowMessageBoxOnError when it is ready to abort.
1265 os::sleep(this, 5 * 1000, false);
1266 }
1267 }
1269 PeriodicTask::real_time_tick(time_to_wait);
1271 // If we have no more tasks left due to dynamic disenrollment,
1272 // shut down the thread since we don't currently support dynamic enrollment
1273 if (PeriodicTask::num_tasks() == 0) {
1274 _should_terminate = true;
1275 }
1276 }
1278 // Signal that it is terminated
1279 {
1280 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1281 _watcher_thread = NULL;
1282 Terminator_lock->notify();
1283 }
1285 // Thread destructor usually does this..
1286 ThreadLocalStorage::set_thread(NULL);
1287 }
1289 void WatcherThread::start() {
1290 if (watcher_thread() == NULL) {
1291 _should_terminate = false;
1292 // Create the single instance of WatcherThread
1293 new WatcherThread();
1294 }
1295 }
1297 void WatcherThread::stop() {
1298 // it is ok to take late safepoints here, if needed
1299 MutexLocker mu(Terminator_lock);
1300 _should_terminate = true;
1301 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1303 Thread* watcher = watcher_thread();
1304 if (watcher != NULL)
1305 watcher->_SleepEvent->unpark();
1307 while(watcher_thread() != NULL) {
1308 // This wait should make safepoint checks, wait without a timeout,
1309 // and wait as a suspend-equivalent condition.
1310 //
1311 // Note: If the FlatProfiler is running, then this thread is waiting
1312 // for the WatcherThread to terminate and the WatcherThread, via the
1313 // FlatProfiler task, is waiting for the external suspend request on
1314 // this thread to complete. wait_for_ext_suspend_completion() will
1315 // eventually timeout, but that takes time. Making this wait a
1316 // suspend-equivalent condition solves that timeout problem.
1317 //
1318 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1319 Mutex::_as_suspend_equivalent_flag);
1320 }
1321 }
1323 void WatcherThread::print_on(outputStream* st) const {
1324 st->print("\"%s\" ", name());
1325 Thread::print_on(st);
1326 st->cr();
1327 }
1329 // ======= JavaThread ========
1331 // A JavaThread is a normal Java thread
1333 void JavaThread::initialize() {
1334 // Initialize fields
1336 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1337 set_claimed_par_id(-1);
1339 set_saved_exception_pc(NULL);
1340 set_threadObj(NULL);
1341 _anchor.clear();
1342 set_entry_point(NULL);
1343 set_jni_functions(jni_functions());
1344 set_callee_target(NULL);
1345 set_vm_result(NULL);
1346 set_vm_result_2(NULL);
1347 set_vframe_array_head(NULL);
1348 set_vframe_array_last(NULL);
1349 set_deferred_locals(NULL);
1350 set_deopt_mark(NULL);
1351 set_deopt_nmethod(NULL);
1352 clear_must_deopt_id();
1353 set_monitor_chunks(NULL);
1354 set_next(NULL);
1355 set_thread_state(_thread_new);
1356 set_recorder(NULL);
1357 _terminated = _not_terminated;
1358 _privileged_stack_top = NULL;
1359 _array_for_gc = NULL;
1360 _suspend_equivalent = false;
1361 _in_deopt_handler = 0;
1362 _doing_unsafe_access = false;
1363 _stack_guard_state = stack_guard_unused;
1364 _exception_oop = NULL;
1365 _exception_pc = 0;
1366 _exception_handler_pc = 0;
1367 _is_method_handle_return = 0;
1368 _jvmti_thread_state= NULL;
1369 _should_post_on_exceptions_flag = JNI_FALSE;
1370 _jvmti_get_loaded_classes_closure = NULL;
1371 _interp_only_mode = 0;
1372 _special_runtime_exit_condition = _no_async_condition;
1373 _pending_async_exception = NULL;
1374 _is_compiling = false;
1375 _thread_stat = NULL;
1376 _thread_stat = new ThreadStatistics();
1377 _blocked_on_compilation = false;
1378 _jni_active_critical = 0;
1379 _do_not_unlock_if_synchronized = false;
1380 _cached_monitor_info = NULL;
1381 _parker = Parker::Allocate(this) ;
1383 #ifndef PRODUCT
1384 _jmp_ring_index = 0;
1385 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1386 record_jump(NULL, NULL, NULL, 0);
1387 }
1388 #endif /* PRODUCT */
1390 set_thread_profiler(NULL);
1391 if (FlatProfiler::is_active()) {
1392 // This is where we would decide to either give each thread it's own profiler
1393 // or use one global one from FlatProfiler,
1394 // or up to some count of the number of profiled threads, etc.
1395 ThreadProfiler* pp = new ThreadProfiler();
1396 pp->engage();
1397 set_thread_profiler(pp);
1398 }
1400 // Setup safepoint state info for this thread
1401 ThreadSafepointState::create(this);
1403 debug_only(_java_call_counter = 0);
1405 // JVMTI PopFrame support
1406 _popframe_condition = popframe_inactive;
1407 _popframe_preserved_args = NULL;
1408 _popframe_preserved_args_size = 0;
1410 pd_initialize();
1411 }
1413 #ifndef SERIALGC
1414 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1415 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1416 #endif // !SERIALGC
1418 JavaThread::JavaThread(bool is_attaching_via_jni) :
1419 Thread()
1420 #ifndef SERIALGC
1421 , _satb_mark_queue(&_satb_mark_queue_set),
1422 _dirty_card_queue(&_dirty_card_queue_set)
1423 #endif // !SERIALGC
1424 {
1425 initialize();
1426 if (is_attaching_via_jni) {
1427 _jni_attach_state = _attaching_via_jni;
1428 } else {
1429 _jni_attach_state = _not_attaching_via_jni;
1430 }
1431 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1432 _safepoint_visible = false;
1433 }
1435 bool JavaThread::reguard_stack(address cur_sp) {
1436 if (_stack_guard_state != stack_guard_yellow_disabled) {
1437 return true; // Stack already guarded or guard pages not needed.
1438 }
1440 if (register_stack_overflow()) {
1441 // For those architectures which have separate register and
1442 // memory stacks, we must check the register stack to see if
1443 // it has overflowed.
1444 return false;
1445 }
1447 // Java code never executes within the yellow zone: the latter is only
1448 // there to provoke an exception during stack banging. If java code
1449 // is executing there, either StackShadowPages should be larger, or
1450 // some exception code in c1, c2 or the interpreter isn't unwinding
1451 // when it should.
1452 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1454 enable_stack_yellow_zone();
1455 return true;
1456 }
1458 bool JavaThread::reguard_stack(void) {
1459 return reguard_stack(os::current_stack_pointer());
1460 }
1463 void JavaThread::block_if_vm_exited() {
1464 if (_terminated == _vm_exited) {
1465 // _vm_exited is set at safepoint, and Threads_lock is never released
1466 // we will block here forever
1467 Threads_lock->lock_without_safepoint_check();
1468 ShouldNotReachHere();
1469 }
1470 }
1473 // Remove this ifdef when C1 is ported to the compiler interface.
1474 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1476 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1477 Thread()
1478 #ifndef SERIALGC
1479 , _satb_mark_queue(&_satb_mark_queue_set),
1480 _dirty_card_queue(&_dirty_card_queue_set)
1481 #endif // !SERIALGC
1482 {
1483 if (TraceThreadEvents) {
1484 tty->print_cr("creating thread %p", this);
1485 }
1486 initialize();
1487 _jni_attach_state = _not_attaching_via_jni;
1488 set_entry_point(entry_point);
1489 // Create the native thread itself.
1490 // %note runtime_23
1491 os::ThreadType thr_type = os::java_thread;
1492 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1493 os::java_thread;
1494 os::create_thread(this, thr_type, stack_sz);
1495 _safepoint_visible = false;
1496 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1497 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1498 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1499 // the exception consists of creating the exception object & initializing it, initialization
1500 // will leave the VM via a JavaCall and then all locks must be unlocked).
1501 //
1502 // The thread is still suspended when we reach here. Thread must be explicit started
1503 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1504 // by calling Threads:add. The reason why this is not done here, is because the thread
1505 // object must be fully initialized (take a look at JVM_Start)
1506 }
1508 JavaThread::~JavaThread() {
1509 if (TraceThreadEvents) {
1510 tty->print_cr("terminate thread %p", this);
1511 }
1513 // Info NMT that this JavaThread is exiting, its memory
1514 // recorder should be collected
1515 assert(!is_safepoint_visible(), "wrong state");
1516 MemTracker::thread_exiting(this);
1518 // JSR166 -- return the parker to the free list
1519 Parker::Release(_parker);
1520 _parker = NULL ;
1522 // Free any remaining previous UnrollBlock
1523 vframeArray* old_array = vframe_array_last();
1525 if (old_array != NULL) {
1526 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1527 old_array->set_unroll_block(NULL);
1528 delete old_info;
1529 delete old_array;
1530 }
1532 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1533 if (deferred != NULL) {
1534 // This can only happen if thread is destroyed before deoptimization occurs.
1535 assert(deferred->length() != 0, "empty array!");
1536 do {
1537 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1538 deferred->remove_at(0);
1539 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1540 delete dlv;
1541 } while (deferred->length() != 0);
1542 delete deferred;
1543 }
1545 // All Java related clean up happens in exit
1546 ThreadSafepointState::destroy(this);
1547 if (_thread_profiler != NULL) delete _thread_profiler;
1548 if (_thread_stat != NULL) delete _thread_stat;
1549 }
1552 // The first routine called by a new Java thread
1553 void JavaThread::run() {
1554 // initialize thread-local alloc buffer related fields
1555 this->initialize_tlab();
1557 // used to test validitity of stack trace backs
1558 this->record_base_of_stack_pointer();
1560 // Record real stack base and size.
1561 this->record_stack_base_and_size();
1563 // Initialize thread local storage; set before calling MutexLocker
1564 this->initialize_thread_local_storage();
1566 this->create_stack_guard_pages();
1568 this->cache_global_variables();
1570 // Thread is now sufficient initialized to be handled by the safepoint code as being
1571 // in the VM. Change thread state from _thread_new to _thread_in_vm
1572 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1574 assert(JavaThread::current() == this, "sanity check");
1575 assert(!Thread::current()->owns_locks(), "sanity check");
1577 DTRACE_THREAD_PROBE(start, this);
1579 // This operation might block. We call that after all safepoint checks for a new thread has
1580 // been completed.
1581 this->set_active_handles(JNIHandleBlock::allocate_block());
1583 if (JvmtiExport::should_post_thread_life()) {
1584 JvmtiExport::post_thread_start(this);
1585 }
1587 EVENT_BEGIN(TraceEventThreadStart, event);
1588 EVENT_COMMIT(event,
1589 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1591 // We call another function to do the rest so we are sure that the stack addresses used
1592 // from there will be lower than the stack base just computed
1593 thread_main_inner();
1595 // Note, thread is no longer valid at this point!
1596 }
1599 void JavaThread::thread_main_inner() {
1600 assert(JavaThread::current() == this, "sanity check");
1601 assert(this->threadObj() != NULL, "just checking");
1603 // Execute thread entry point unless this thread has a pending exception
1604 // or has been stopped before starting.
1605 // Note: Due to JVM_StopThread we can have pending exceptions already!
1606 if (!this->has_pending_exception() &&
1607 !java_lang_Thread::is_stillborn(this->threadObj())) {
1608 {
1609 ResourceMark rm(this);
1610 this->set_native_thread_name(this->get_thread_name());
1611 }
1612 HandleMark hm(this);
1613 this->entry_point()(this, this);
1614 }
1616 DTRACE_THREAD_PROBE(stop, this);
1618 this->exit(false);
1619 delete this;
1620 }
1623 static void ensure_join(JavaThread* thread) {
1624 // We do not need to grap the Threads_lock, since we are operating on ourself.
1625 Handle threadObj(thread, thread->threadObj());
1626 assert(threadObj.not_null(), "java thread object must exist");
1627 ObjectLocker lock(threadObj, thread);
1628 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1629 thread->clear_pending_exception();
1630 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1631 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1632 // Clear the native thread instance - this makes isAlive return false and allows the join()
1633 // to complete once we've done the notify_all below
1634 java_lang_Thread::set_thread(threadObj(), NULL);
1635 lock.notify_all(thread);
1636 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1637 thread->clear_pending_exception();
1638 }
1641 // For any new cleanup additions, please check to see if they need to be applied to
1642 // cleanup_failed_attach_current_thread as well.
1643 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1644 assert(this == JavaThread::current(), "thread consistency check");
1645 if (!InitializeJavaLangSystem) return;
1647 HandleMark hm(this);
1648 Handle uncaught_exception(this, this->pending_exception());
1649 this->clear_pending_exception();
1650 Handle threadObj(this, this->threadObj());
1651 assert(threadObj.not_null(), "Java thread object should be created");
1653 if (get_thread_profiler() != NULL) {
1654 get_thread_profiler()->disengage();
1655 ResourceMark rm;
1656 get_thread_profiler()->print(get_thread_name());
1657 }
1660 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1661 {
1662 EXCEPTION_MARK;
1664 CLEAR_PENDING_EXCEPTION;
1665 }
1666 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1667 // has to be fixed by a runtime query method
1668 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1669 // JSR-166: change call from from ThreadGroup.uncaughtException to
1670 // java.lang.Thread.dispatchUncaughtException
1671 if (uncaught_exception.not_null()) {
1672 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1673 {
1674 EXCEPTION_MARK;
1675 // Check if the method Thread.dispatchUncaughtException() exists. If so
1676 // call it. Otherwise we have an older library without the JSR-166 changes,
1677 // so call ThreadGroup.uncaughtException()
1678 KlassHandle recvrKlass(THREAD, threadObj->klass());
1679 CallInfo callinfo;
1680 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1681 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1682 vmSymbols::dispatchUncaughtException_name(),
1683 vmSymbols::throwable_void_signature(),
1684 KlassHandle(), false, false, THREAD);
1685 CLEAR_PENDING_EXCEPTION;
1686 methodHandle method = callinfo.selected_method();
1687 if (method.not_null()) {
1688 JavaValue result(T_VOID);
1689 JavaCalls::call_virtual(&result,
1690 threadObj, thread_klass,
1691 vmSymbols::dispatchUncaughtException_name(),
1692 vmSymbols::throwable_void_signature(),
1693 uncaught_exception,
1694 THREAD);
1695 } else {
1696 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1697 JavaValue result(T_VOID);
1698 JavaCalls::call_virtual(&result,
1699 group, thread_group,
1700 vmSymbols::uncaughtException_name(),
1701 vmSymbols::thread_throwable_void_signature(),
1702 threadObj, // Arg 1
1703 uncaught_exception, // Arg 2
1704 THREAD);
1705 }
1706 if (HAS_PENDING_EXCEPTION) {
1707 ResourceMark rm(this);
1708 jio_fprintf(defaultStream::error_stream(),
1709 "\nException: %s thrown from the UncaughtExceptionHandler"
1710 " in thread \"%s\"\n",
1711 Klass::cast(pending_exception()->klass())->external_name(),
1712 get_thread_name());
1713 CLEAR_PENDING_EXCEPTION;
1714 }
1715 }
1716 }
1718 // Called before the java thread exit since we want to read info
1719 // from java_lang_Thread object
1720 EVENT_BEGIN(TraceEventThreadEnd, event);
1721 EVENT_COMMIT(event,
1722 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1724 // Call after last event on thread
1725 EVENT_THREAD_EXIT(this);
1727 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1728 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1729 // is deprecated anyhow.
1730 { int count = 3;
1731 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1732 EXCEPTION_MARK;
1733 JavaValue result(T_VOID);
1734 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1735 JavaCalls::call_virtual(&result,
1736 threadObj, thread_klass,
1737 vmSymbols::exit_method_name(),
1738 vmSymbols::void_method_signature(),
1739 THREAD);
1740 CLEAR_PENDING_EXCEPTION;
1741 }
1742 }
1744 // notify JVMTI
1745 if (JvmtiExport::should_post_thread_life()) {
1746 JvmtiExport::post_thread_end(this);
1747 }
1749 // We have notified the agents that we are exiting, before we go on,
1750 // we must check for a pending external suspend request and honor it
1751 // in order to not surprise the thread that made the suspend request.
1752 while (true) {
1753 {
1754 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1755 if (!is_external_suspend()) {
1756 set_terminated(_thread_exiting);
1757 ThreadService::current_thread_exiting(this);
1758 break;
1759 }
1760 // Implied else:
1761 // Things get a little tricky here. We have a pending external
1762 // suspend request, but we are holding the SR_lock so we
1763 // can't just self-suspend. So we temporarily drop the lock
1764 // and then self-suspend.
1765 }
1767 ThreadBlockInVM tbivm(this);
1768 java_suspend_self();
1770 // We're done with this suspend request, but we have to loop around
1771 // and check again. Eventually we will get SR_lock without a pending
1772 // external suspend request and will be able to mark ourselves as
1773 // exiting.
1774 }
1775 // no more external suspends are allowed at this point
1776 } else {
1777 // before_exit() has already posted JVMTI THREAD_END events
1778 }
1780 // Notify waiters on thread object. This has to be done after exit() is called
1781 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1782 // group should have the destroyed bit set before waiters are notified).
1783 ensure_join(this);
1784 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1786 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1787 // held by this thread must be released. A detach operation must only
1788 // get here if there are no Java frames on the stack. Therefore, any
1789 // owned monitors at this point MUST be JNI-acquired monitors which are
1790 // pre-inflated and in the monitor cache.
1791 //
1792 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1793 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1794 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1795 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1796 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1797 }
1799 // These things needs to be done while we are still a Java Thread. Make sure that thread
1800 // is in a consistent state, in case GC happens
1801 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1803 if (active_handles() != NULL) {
1804 JNIHandleBlock* block = active_handles();
1805 set_active_handles(NULL);
1806 JNIHandleBlock::release_block(block);
1807 }
1809 if (free_handle_block() != NULL) {
1810 JNIHandleBlock* block = free_handle_block();
1811 set_free_handle_block(NULL);
1812 JNIHandleBlock::release_block(block);
1813 }
1815 // These have to be removed while this is still a valid thread.
1816 remove_stack_guard_pages();
1818 if (UseTLAB) {
1819 tlab().make_parsable(true); // retire TLAB
1820 }
1822 if (JvmtiEnv::environments_might_exist()) {
1823 JvmtiExport::cleanup_thread(this);
1824 }
1826 #ifndef SERIALGC
1827 // We must flush G1-related buffers before removing a thread from
1828 // the list of active threads.
1829 if (UseG1GC) {
1830 flush_barrier_queues();
1831 }
1832 #endif
1834 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1835 Threads::remove(this);
1836 }
1838 #ifndef SERIALGC
1839 // Flush G1-related queues.
1840 void JavaThread::flush_barrier_queues() {
1841 satb_mark_queue().flush();
1842 dirty_card_queue().flush();
1843 }
1845 void JavaThread::initialize_queues() {
1846 assert(!SafepointSynchronize::is_at_safepoint(),
1847 "we should not be at a safepoint");
1849 ObjPtrQueue& satb_queue = satb_mark_queue();
1850 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1851 // The SATB queue should have been constructed with its active
1852 // field set to false.
1853 assert(!satb_queue.is_active(), "SATB queue should not be active");
1854 assert(satb_queue.is_empty(), "SATB queue should be empty");
1855 // If we are creating the thread during a marking cycle, we should
1856 // set the active field of the SATB queue to true.
1857 if (satb_queue_set.is_active()) {
1858 satb_queue.set_active(true);
1859 }
1861 DirtyCardQueue& dirty_queue = dirty_card_queue();
1862 // The dirty card queue should have been constructed with its
1863 // active field set to true.
1864 assert(dirty_queue.is_active(), "dirty card queue should be active");
1865 }
1866 #endif // !SERIALGC
1868 void JavaThread::cleanup_failed_attach_current_thread() {
1869 if (get_thread_profiler() != NULL) {
1870 get_thread_profiler()->disengage();
1871 ResourceMark rm;
1872 get_thread_profiler()->print(get_thread_name());
1873 }
1875 if (active_handles() != NULL) {
1876 JNIHandleBlock* block = active_handles();
1877 set_active_handles(NULL);
1878 JNIHandleBlock::release_block(block);
1879 }
1881 if (free_handle_block() != NULL) {
1882 JNIHandleBlock* block = free_handle_block();
1883 set_free_handle_block(NULL);
1884 JNIHandleBlock::release_block(block);
1885 }
1887 // These have to be removed while this is still a valid thread.
1888 remove_stack_guard_pages();
1890 if (UseTLAB) {
1891 tlab().make_parsable(true); // retire TLAB, if any
1892 }
1894 #ifndef SERIALGC
1895 if (UseG1GC) {
1896 flush_barrier_queues();
1897 }
1898 #endif
1900 Threads::remove(this);
1901 delete this;
1902 }
1907 JavaThread* JavaThread::active() {
1908 Thread* thread = ThreadLocalStorage::thread();
1909 assert(thread != NULL, "just checking");
1910 if (thread->is_Java_thread()) {
1911 return (JavaThread*) thread;
1912 } else {
1913 assert(thread->is_VM_thread(), "this must be a vm thread");
1914 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1915 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1916 assert(ret->is_Java_thread(), "must be a Java thread");
1917 return ret;
1918 }
1919 }
1921 bool JavaThread::is_lock_owned(address adr) const {
1922 if (Thread::is_lock_owned(adr)) return true;
1924 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1925 if (chunk->contains(adr)) return true;
1926 }
1928 return false;
1929 }
1932 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1933 chunk->set_next(monitor_chunks());
1934 set_monitor_chunks(chunk);
1935 }
1937 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1938 guarantee(monitor_chunks() != NULL, "must be non empty");
1939 if (monitor_chunks() == chunk) {
1940 set_monitor_chunks(chunk->next());
1941 } else {
1942 MonitorChunk* prev = monitor_chunks();
1943 while (prev->next() != chunk) prev = prev->next();
1944 prev->set_next(chunk->next());
1945 }
1946 }
1948 // JVM support.
1950 // Note: this function shouldn't block if it's called in
1951 // _thread_in_native_trans state (such as from
1952 // check_special_condition_for_native_trans()).
1953 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1955 if (has_last_Java_frame() && has_async_condition()) {
1956 // If we are at a polling page safepoint (not a poll return)
1957 // then we must defer async exception because live registers
1958 // will be clobbered by the exception path. Poll return is
1959 // ok because the call we a returning from already collides
1960 // with exception handling registers and so there is no issue.
1961 // (The exception handling path kills call result registers but
1962 // this is ok since the exception kills the result anyway).
1964 if (is_at_poll_safepoint()) {
1965 // if the code we are returning to has deoptimized we must defer
1966 // the exception otherwise live registers get clobbered on the
1967 // exception path before deoptimization is able to retrieve them.
1968 //
1969 RegisterMap map(this, false);
1970 frame caller_fr = last_frame().sender(&map);
1971 assert(caller_fr.is_compiled_frame(), "what?");
1972 if (caller_fr.is_deoptimized_frame()) {
1973 if (TraceExceptions) {
1974 ResourceMark rm;
1975 tty->print_cr("deferred async exception at compiled safepoint");
1976 }
1977 return;
1978 }
1979 }
1980 }
1982 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1983 if (condition == _no_async_condition) {
1984 // Conditions have changed since has_special_runtime_exit_condition()
1985 // was called:
1986 // - if we were here only because of an external suspend request,
1987 // then that was taken care of above (or cancelled) so we are done
1988 // - if we were here because of another async request, then it has
1989 // been cleared between the has_special_runtime_exit_condition()
1990 // and now so again we are done
1991 return;
1992 }
1994 // Check for pending async. exception
1995 if (_pending_async_exception != NULL) {
1996 // Only overwrite an already pending exception, if it is not a threadDeath.
1997 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1999 // We cannot call Exceptions::_throw(...) here because we cannot block
2000 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2002 if (TraceExceptions) {
2003 ResourceMark rm;
2004 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2005 if (has_last_Java_frame() ) {
2006 frame f = last_frame();
2007 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2008 }
2009 tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2010 }
2011 _pending_async_exception = NULL;
2012 clear_has_async_exception();
2013 }
2014 }
2016 if (check_unsafe_error &&
2017 condition == _async_unsafe_access_error && !has_pending_exception()) {
2018 condition = _no_async_condition; // done
2019 switch (thread_state()) {
2020 case _thread_in_vm:
2021 {
2022 JavaThread* THREAD = this;
2023 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2024 }
2025 case _thread_in_native:
2026 {
2027 ThreadInVMfromNative tiv(this);
2028 JavaThread* THREAD = this;
2029 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2030 }
2031 case _thread_in_Java:
2032 {
2033 ThreadInVMfromJava tiv(this);
2034 JavaThread* THREAD = this;
2035 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2036 }
2037 default:
2038 ShouldNotReachHere();
2039 }
2040 }
2042 assert(condition == _no_async_condition || has_pending_exception() ||
2043 (!check_unsafe_error && condition == _async_unsafe_access_error),
2044 "must have handled the async condition, if no exception");
2045 }
2047 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2048 //
2049 // Check for pending external suspend. Internal suspend requests do
2050 // not use handle_special_runtime_exit_condition().
2051 // If JNIEnv proxies are allowed, don't self-suspend if the target
2052 // thread is not the current thread. In older versions of jdbx, jdbx
2053 // threads could call into the VM with another thread's JNIEnv so we
2054 // can be here operating on behalf of a suspended thread (4432884).
2055 bool do_self_suspend = is_external_suspend_with_lock();
2056 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2057 //
2058 // Because thread is external suspended the safepoint code will count
2059 // thread as at a safepoint. This can be odd because we can be here
2060 // as _thread_in_Java which would normally transition to _thread_blocked
2061 // at a safepoint. We would like to mark the thread as _thread_blocked
2062 // before calling java_suspend_self like all other callers of it but
2063 // we must then observe proper safepoint protocol. (We can't leave
2064 // _thread_blocked with a safepoint in progress). However we can be
2065 // here as _thread_in_native_trans so we can't use a normal transition
2066 // constructor/destructor pair because they assert on that type of
2067 // transition. We could do something like:
2068 //
2069 // JavaThreadState state = thread_state();
2070 // set_thread_state(_thread_in_vm);
2071 // {
2072 // ThreadBlockInVM tbivm(this);
2073 // java_suspend_self()
2074 // }
2075 // set_thread_state(_thread_in_vm_trans);
2076 // if (safepoint) block;
2077 // set_thread_state(state);
2078 //
2079 // but that is pretty messy. Instead we just go with the way the
2080 // code has worked before and note that this is the only path to
2081 // java_suspend_self that doesn't put the thread in _thread_blocked
2082 // mode.
2084 frame_anchor()->make_walkable(this);
2085 java_suspend_self();
2087 // We might be here for reasons in addition to the self-suspend request
2088 // so check for other async requests.
2089 }
2091 if (check_asyncs) {
2092 check_and_handle_async_exceptions();
2093 }
2094 }
2096 void JavaThread::send_thread_stop(oop java_throwable) {
2097 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2098 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2099 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2101 // Do not throw asynchronous exceptions against the compiler thread
2102 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2103 if (is_Compiler_thread()) return;
2105 {
2106 // Actually throw the Throwable against the target Thread - however
2107 // only if there is no thread death exception installed already.
2108 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2109 // If the topmost frame is a runtime stub, then we are calling into
2110 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2111 // must deoptimize the caller before continuing, as the compiled exception handler table
2112 // may not be valid
2113 if (has_last_Java_frame()) {
2114 frame f = last_frame();
2115 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2116 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2117 RegisterMap reg_map(this, UseBiasedLocking);
2118 frame compiled_frame = f.sender(®_map);
2119 if (compiled_frame.can_be_deoptimized()) {
2120 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2121 }
2122 }
2123 }
2125 // Set async. pending exception in thread.
2126 set_pending_async_exception(java_throwable);
2128 if (TraceExceptions) {
2129 ResourceMark rm;
2130 tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2131 }
2132 // for AbortVMOnException flag
2133 NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2134 }
2135 }
2138 // Interrupt thread so it will wake up from a potential wait()
2139 Thread::interrupt(this);
2140 }
2142 // External suspension mechanism.
2143 //
2144 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2145 // to any VM_locks and it is at a transition
2146 // Self-suspension will happen on the transition out of the vm.
2147 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2148 //
2149 // Guarantees on return:
2150 // + Target thread will not execute any new bytecode (that's why we need to
2151 // force a safepoint)
2152 // + Target thread will not enter any new monitors
2153 //
2154 void JavaThread::java_suspend() {
2155 { MutexLocker mu(Threads_lock);
2156 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2157 return;
2158 }
2159 }
2161 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2162 if (!is_external_suspend()) {
2163 // a racing resume has cancelled us; bail out now
2164 return;
2165 }
2167 // suspend is done
2168 uint32_t debug_bits = 0;
2169 // Warning: is_ext_suspend_completed() may temporarily drop the
2170 // SR_lock to allow the thread to reach a stable thread state if
2171 // it is currently in a transient thread state.
2172 if (is_ext_suspend_completed(false /* !called_by_wait */,
2173 SuspendRetryDelay, &debug_bits) ) {
2174 return;
2175 }
2176 }
2178 VM_ForceSafepoint vm_suspend;
2179 VMThread::execute(&vm_suspend);
2180 }
2182 // Part II of external suspension.
2183 // A JavaThread self suspends when it detects a pending external suspend
2184 // request. This is usually on transitions. It is also done in places
2185 // where continuing to the next transition would surprise the caller,
2186 // e.g., monitor entry.
2187 //
2188 // Returns the number of times that the thread self-suspended.
2189 //
2190 // Note: DO NOT call java_suspend_self() when you just want to block current
2191 // thread. java_suspend_self() is the second stage of cooperative
2192 // suspension for external suspend requests and should only be used
2193 // to complete an external suspend request.
2194 //
2195 int JavaThread::java_suspend_self() {
2196 int ret = 0;
2198 // we are in the process of exiting so don't suspend
2199 if (is_exiting()) {
2200 clear_external_suspend();
2201 return ret;
2202 }
2204 assert(_anchor.walkable() ||
2205 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2206 "must have walkable stack");
2208 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2210 assert(!this->is_ext_suspended(),
2211 "a thread trying to self-suspend should not already be suspended");
2213 if (this->is_suspend_equivalent()) {
2214 // If we are self-suspending as a result of the lifting of a
2215 // suspend equivalent condition, then the suspend_equivalent
2216 // flag is not cleared until we set the ext_suspended flag so
2217 // that wait_for_ext_suspend_completion() returns consistent
2218 // results.
2219 this->clear_suspend_equivalent();
2220 }
2222 // A racing resume may have cancelled us before we grabbed SR_lock
2223 // above. Or another external suspend request could be waiting for us
2224 // by the time we return from SR_lock()->wait(). The thread
2225 // that requested the suspension may already be trying to walk our
2226 // stack and if we return now, we can change the stack out from under
2227 // it. This would be a "bad thing (TM)" and cause the stack walker
2228 // to crash. We stay self-suspended until there are no more pending
2229 // external suspend requests.
2230 while (is_external_suspend()) {
2231 ret++;
2232 this->set_ext_suspended();
2234 // _ext_suspended flag is cleared by java_resume()
2235 while (is_ext_suspended()) {
2236 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2237 }
2238 }
2240 return ret;
2241 }
2243 #ifdef ASSERT
2244 // verify the JavaThread has not yet been published in the Threads::list, and
2245 // hence doesn't need protection from concurrent access at this stage
2246 void JavaThread::verify_not_published() {
2247 if (!Threads_lock->owned_by_self()) {
2248 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2249 assert( !Threads::includes(this),
2250 "java thread shouldn't have been published yet!");
2251 }
2252 else {
2253 assert( !Threads::includes(this),
2254 "java thread shouldn't have been published yet!");
2255 }
2256 }
2257 #endif
2259 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2260 // progress or when _suspend_flags is non-zero.
2261 // Current thread needs to self-suspend if there is a suspend request and/or
2262 // block if a safepoint is in progress.
2263 // Async exception ISN'T checked.
2264 // Note only the ThreadInVMfromNative transition can call this function
2265 // directly and when thread state is _thread_in_native_trans
2266 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2267 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2269 JavaThread *curJT = JavaThread::current();
2270 bool do_self_suspend = thread->is_external_suspend();
2272 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2274 // If JNIEnv proxies are allowed, don't self-suspend if the target
2275 // thread is not the current thread. In older versions of jdbx, jdbx
2276 // threads could call into the VM with another thread's JNIEnv so we
2277 // can be here operating on behalf of a suspended thread (4432884).
2278 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2279 JavaThreadState state = thread->thread_state();
2281 // We mark this thread_blocked state as a suspend-equivalent so
2282 // that a caller to is_ext_suspend_completed() won't be confused.
2283 // The suspend-equivalent state is cleared by java_suspend_self().
2284 thread->set_suspend_equivalent();
2286 // If the safepoint code sees the _thread_in_native_trans state, it will
2287 // wait until the thread changes to other thread state. There is no
2288 // guarantee on how soon we can obtain the SR_lock and complete the
2289 // self-suspend request. It would be a bad idea to let safepoint wait for
2290 // too long. Temporarily change the state to _thread_blocked to
2291 // let the VM thread know that this thread is ready for GC. The problem
2292 // of changing thread state is that safepoint could happen just after
2293 // java_suspend_self() returns after being resumed, and VM thread will
2294 // see the _thread_blocked state. We must check for safepoint
2295 // after restoring the state and make sure we won't leave while a safepoint
2296 // is in progress.
2297 thread->set_thread_state(_thread_blocked);
2298 thread->java_suspend_self();
2299 thread->set_thread_state(state);
2300 // Make sure new state is seen by VM thread
2301 if (os::is_MP()) {
2302 if (UseMembar) {
2303 // Force a fence between the write above and read below
2304 OrderAccess::fence();
2305 } else {
2306 // Must use this rather than serialization page in particular on Windows
2307 InterfaceSupport::serialize_memory(thread);
2308 }
2309 }
2310 }
2312 if (SafepointSynchronize::do_call_back()) {
2313 // If we are safepointing, then block the caller which may not be
2314 // the same as the target thread (see above).
2315 SafepointSynchronize::block(curJT);
2316 }
2318 if (thread->is_deopt_suspend()) {
2319 thread->clear_deopt_suspend();
2320 RegisterMap map(thread, false);
2321 frame f = thread->last_frame();
2322 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2323 f = f.sender(&map);
2324 }
2325 if (f.id() == thread->must_deopt_id()) {
2326 thread->clear_must_deopt_id();
2327 f.deoptimize(thread);
2328 } else {
2329 fatal("missed deoptimization!");
2330 }
2331 }
2332 }
2334 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2335 // progress or when _suspend_flags is non-zero.
2336 // Current thread needs to self-suspend if there is a suspend request and/or
2337 // block if a safepoint is in progress.
2338 // Also check for pending async exception (not including unsafe access error).
2339 // Note only the native==>VM/Java barriers can call this function and when
2340 // thread state is _thread_in_native_trans.
2341 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2342 check_safepoint_and_suspend_for_native_trans(thread);
2344 if (thread->has_async_exception()) {
2345 // We are in _thread_in_native_trans state, don't handle unsafe
2346 // access error since that may block.
2347 thread->check_and_handle_async_exceptions(false);
2348 }
2349 }
2351 // This is a variant of the normal
2352 // check_special_condition_for_native_trans with slightly different
2353 // semantics for use by critical native wrappers. It does all the
2354 // normal checks but also performs the transition back into
2355 // thread_in_Java state. This is required so that critical natives
2356 // can potentially block and perform a GC if they are the last thread
2357 // exiting the GC_locker.
2358 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2359 check_special_condition_for_native_trans(thread);
2361 // Finish the transition
2362 thread->set_thread_state(_thread_in_Java);
2364 if (thread->do_critical_native_unlock()) {
2365 ThreadInVMfromJavaNoAsyncException tiv(thread);
2366 GC_locker::unlock_critical(thread);
2367 thread->clear_critical_native_unlock();
2368 }
2369 }
2371 // We need to guarantee the Threads_lock here, since resumes are not
2372 // allowed during safepoint synchronization
2373 // Can only resume from an external suspension
2374 void JavaThread::java_resume() {
2375 assert_locked_or_safepoint(Threads_lock);
2377 // Sanity check: thread is gone, has started exiting or the thread
2378 // was not externally suspended.
2379 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2380 return;
2381 }
2383 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2385 clear_external_suspend();
2387 if (is_ext_suspended()) {
2388 clear_ext_suspended();
2389 SR_lock()->notify_all();
2390 }
2391 }
2393 void JavaThread::create_stack_guard_pages() {
2394 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2395 address low_addr = stack_base() - stack_size();
2396 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2398 int allocate = os::allocate_stack_guard_pages();
2399 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2401 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2402 warning("Attempt to allocate stack guard pages failed.");
2403 return;
2404 }
2406 if (os::guard_memory((char *) low_addr, len)) {
2407 _stack_guard_state = stack_guard_enabled;
2408 } else {
2409 warning("Attempt to protect stack guard pages failed.");
2410 if (os::uncommit_memory((char *) low_addr, len)) {
2411 warning("Attempt to deallocate stack guard pages failed.");
2412 }
2413 }
2414 }
2416 void JavaThread::remove_stack_guard_pages() {
2417 if (_stack_guard_state == stack_guard_unused) return;
2418 address low_addr = stack_base() - stack_size();
2419 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2421 if (os::allocate_stack_guard_pages()) {
2422 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2423 _stack_guard_state = stack_guard_unused;
2424 } else {
2425 warning("Attempt to deallocate stack guard pages failed.");
2426 }
2427 } else {
2428 if (_stack_guard_state == stack_guard_unused) return;
2429 if (os::unguard_memory((char *) low_addr, len)) {
2430 _stack_guard_state = stack_guard_unused;
2431 } else {
2432 warning("Attempt to unprotect stack guard pages failed.");
2433 }
2434 }
2435 }
2437 void JavaThread::enable_stack_yellow_zone() {
2438 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2439 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2441 // The base notation is from the stacks point of view, growing downward.
2442 // We need to adjust it to work correctly with guard_memory()
2443 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2445 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2446 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2448 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2449 _stack_guard_state = stack_guard_enabled;
2450 } else {
2451 warning("Attempt to guard stack yellow zone failed.");
2452 }
2453 enable_register_stack_guard();
2454 }
2456 void JavaThread::disable_stack_yellow_zone() {
2457 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2458 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2460 // Simply return if called for a thread that does not use guard pages.
2461 if (_stack_guard_state == stack_guard_unused) return;
2463 // The base notation is from the stacks point of view, growing downward.
2464 // We need to adjust it to work correctly with guard_memory()
2465 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2467 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2468 _stack_guard_state = stack_guard_yellow_disabled;
2469 } else {
2470 warning("Attempt to unguard stack yellow zone failed.");
2471 }
2472 disable_register_stack_guard();
2473 }
2475 void JavaThread::enable_stack_red_zone() {
2476 // The base notation is from the stacks point of view, growing downward.
2477 // We need to adjust it to work correctly with guard_memory()
2478 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2479 address base = stack_red_zone_base() - stack_red_zone_size();
2481 guarantee(base < stack_base(),"Error calculating stack red zone");
2482 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2484 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2485 warning("Attempt to guard stack red zone failed.");
2486 }
2487 }
2489 void JavaThread::disable_stack_red_zone() {
2490 // The base notation is from the stacks point of view, growing downward.
2491 // We need to adjust it to work correctly with guard_memory()
2492 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2493 address base = stack_red_zone_base() - stack_red_zone_size();
2494 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2495 warning("Attempt to unguard stack red zone failed.");
2496 }
2497 }
2499 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2500 // ignore is there is no stack
2501 if (!has_last_Java_frame()) return;
2502 // traverse the stack frames. Starts from top frame.
2503 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2504 frame* fr = fst.current();
2505 f(fr, fst.register_map());
2506 }
2507 }
2510 #ifndef PRODUCT
2511 // Deoptimization
2512 // Function for testing deoptimization
2513 void JavaThread::deoptimize() {
2514 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2515 StackFrameStream fst(this, UseBiasedLocking);
2516 bool deopt = false; // Dump stack only if a deopt actually happens.
2517 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2518 // Iterate over all frames in the thread and deoptimize
2519 for(; !fst.is_done(); fst.next()) {
2520 if(fst.current()->can_be_deoptimized()) {
2522 if (only_at) {
2523 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2524 // consists of comma or carriage return separated numbers so
2525 // search for the current bci in that string.
2526 address pc = fst.current()->pc();
2527 nmethod* nm = (nmethod*) fst.current()->cb();
2528 ScopeDesc* sd = nm->scope_desc_at( pc);
2529 char buffer[8];
2530 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2531 size_t len = strlen(buffer);
2532 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2533 while (found != NULL) {
2534 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2535 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2536 // Check that the bci found is bracketed by terminators.
2537 break;
2538 }
2539 found = strstr(found + 1, buffer);
2540 }
2541 if (!found) {
2542 continue;
2543 }
2544 }
2546 if (DebugDeoptimization && !deopt) {
2547 deopt = true; // One-time only print before deopt
2548 tty->print_cr("[BEFORE Deoptimization]");
2549 trace_frames();
2550 trace_stack();
2551 }
2552 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2553 }
2554 }
2556 if (DebugDeoptimization && deopt) {
2557 tty->print_cr("[AFTER Deoptimization]");
2558 trace_frames();
2559 }
2560 }
2563 // Make zombies
2564 void JavaThread::make_zombies() {
2565 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2566 if (fst.current()->can_be_deoptimized()) {
2567 // it is a Java nmethod
2568 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2569 nm->make_not_entrant();
2570 }
2571 }
2572 }
2573 #endif // PRODUCT
2576 void JavaThread::deoptimized_wrt_marked_nmethods() {
2577 if (!has_last_Java_frame()) return;
2578 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2579 StackFrameStream fst(this, UseBiasedLocking);
2580 for(; !fst.is_done(); fst.next()) {
2581 if (fst.current()->should_be_deoptimized()) {
2582 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2583 }
2584 }
2585 }
2588 // GC support
2589 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2591 void JavaThread::gc_epilogue() {
2592 frames_do(frame_gc_epilogue);
2593 }
2596 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2598 void JavaThread::gc_prologue() {
2599 frames_do(frame_gc_prologue);
2600 }
2602 // If the caller is a NamedThread, then remember, in the current scope,
2603 // the given JavaThread in its _processed_thread field.
2604 class RememberProcessedThread: public StackObj {
2605 NamedThread* _cur_thr;
2606 public:
2607 RememberProcessedThread(JavaThread* jthr) {
2608 Thread* thread = Thread::current();
2609 if (thread->is_Named_thread()) {
2610 _cur_thr = (NamedThread *)thread;
2611 _cur_thr->set_processed_thread(jthr);
2612 } else {
2613 _cur_thr = NULL;
2614 }
2615 }
2617 ~RememberProcessedThread() {
2618 if (_cur_thr) {
2619 _cur_thr->set_processed_thread(NULL);
2620 }
2621 }
2622 };
2624 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2625 // Verify that the deferred card marks have been flushed.
2626 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2628 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2629 // since there may be more than one thread using each ThreadProfiler.
2631 // Traverse the GCHandles
2632 Thread::oops_do(f, cf);
2634 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2635 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2637 if (has_last_Java_frame()) {
2638 // Record JavaThread to GC thread
2639 RememberProcessedThread rpt(this);
2641 // Traverse the privileged stack
2642 if (_privileged_stack_top != NULL) {
2643 _privileged_stack_top->oops_do(f);
2644 }
2646 // traverse the registered growable array
2647 if (_array_for_gc != NULL) {
2648 for (int index = 0; index < _array_for_gc->length(); index++) {
2649 f->do_oop(_array_for_gc->adr_at(index));
2650 }
2651 }
2653 // Traverse the monitor chunks
2654 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2655 chunk->oops_do(f);
2656 }
2658 // Traverse the execution stack
2659 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2660 fst.current()->oops_do(f, cf, fst.register_map());
2661 }
2662 }
2664 // callee_target is never live across a gc point so NULL it here should
2665 // it still contain a methdOop.
2667 set_callee_target(NULL);
2669 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2670 // If we have deferred set_locals there might be oops waiting to be
2671 // written
2672 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2673 if (list != NULL) {
2674 for (int i = 0; i < list->length(); i++) {
2675 list->at(i)->oops_do(f);
2676 }
2677 }
2679 // Traverse instance variables at the end since the GC may be moving things
2680 // around using this function
2681 f->do_oop((oop*) &_threadObj);
2682 f->do_oop((oop*) &_vm_result);
2683 f->do_oop((oop*) &_exception_oop);
2684 f->do_oop((oop*) &_pending_async_exception);
2686 if (jvmti_thread_state() != NULL) {
2687 jvmti_thread_state()->oops_do(f);
2688 }
2689 }
2691 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2692 Thread::nmethods_do(cf); // (super method is a no-op)
2694 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2695 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2697 if (has_last_Java_frame()) {
2698 // Traverse the execution stack
2699 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2700 fst.current()->nmethods_do(cf);
2701 }
2702 }
2703 }
2705 void JavaThread::metadata_do(void f(Metadata*)) {
2706 Thread::metadata_do(f);
2707 if (has_last_Java_frame()) {
2708 // Traverse the execution stack to call f() on the methods in the stack
2709 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2710 fst.current()->metadata_do(f);
2711 }
2712 } else if (is_Compiler_thread()) {
2713 // need to walk ciMetadata in current compile tasks to keep alive.
2714 CompilerThread* ct = (CompilerThread*)this;
2715 if (ct->env() != NULL) {
2716 ct->env()->metadata_do(f);
2717 }
2718 }
2719 }
2721 // Printing
2722 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2723 switch (_thread_state) {
2724 case _thread_uninitialized: return "_thread_uninitialized";
2725 case _thread_new: return "_thread_new";
2726 case _thread_new_trans: return "_thread_new_trans";
2727 case _thread_in_native: return "_thread_in_native";
2728 case _thread_in_native_trans: return "_thread_in_native_trans";
2729 case _thread_in_vm: return "_thread_in_vm";
2730 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2731 case _thread_in_Java: return "_thread_in_Java";
2732 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2733 case _thread_blocked: return "_thread_blocked";
2734 case _thread_blocked_trans: return "_thread_blocked_trans";
2735 default: return "unknown thread state";
2736 }
2737 }
2739 #ifndef PRODUCT
2740 void JavaThread::print_thread_state_on(outputStream *st) const {
2741 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2742 };
2743 void JavaThread::print_thread_state() const {
2744 print_thread_state_on(tty);
2745 };
2746 #endif // PRODUCT
2748 // Called by Threads::print() for VM_PrintThreads operation
2749 void JavaThread::print_on(outputStream *st) const {
2750 st->print("\"%s\" ", get_thread_name());
2751 oop thread_oop = threadObj();
2752 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2753 Thread::print_on(st);
2754 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2755 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2756 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2757 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2758 }
2759 #ifndef PRODUCT
2760 print_thread_state_on(st);
2761 _safepoint_state->print_on(st);
2762 #endif // PRODUCT
2763 }
2765 // Called by fatal error handler. The difference between this and
2766 // JavaThread::print() is that we can't grab lock or allocate memory.
2767 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2768 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2769 oop thread_obj = threadObj();
2770 if (thread_obj != NULL) {
2771 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2772 }
2773 st->print(" [");
2774 st->print("%s", _get_thread_state_name(_thread_state));
2775 if (osthread()) {
2776 st->print(", id=%d", osthread()->thread_id());
2777 }
2778 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2779 _stack_base - _stack_size, _stack_base);
2780 st->print("]");
2781 return;
2782 }
2784 // Verification
2786 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2788 void JavaThread::verify() {
2789 // Verify oops in the thread.
2790 oops_do(&VerifyOopClosure::verify_oop, NULL);
2792 // Verify the stack frames.
2793 frames_do(frame_verify);
2794 }
2796 // CR 6300358 (sub-CR 2137150)
2797 // Most callers of this method assume that it can't return NULL but a
2798 // thread may not have a name whilst it is in the process of attaching to
2799 // the VM - see CR 6412693, and there are places where a JavaThread can be
2800 // seen prior to having it's threadObj set (eg JNI attaching threads and
2801 // if vm exit occurs during initialization). These cases can all be accounted
2802 // for such that this method never returns NULL.
2803 const char* JavaThread::get_thread_name() const {
2804 #ifdef ASSERT
2805 // early safepoints can hit while current thread does not yet have TLS
2806 if (!SafepointSynchronize::is_at_safepoint()) {
2807 Thread *cur = Thread::current();
2808 if (!(cur->is_Java_thread() && cur == this)) {
2809 // Current JavaThreads are allowed to get their own name without
2810 // the Threads_lock.
2811 assert_locked_or_safepoint(Threads_lock);
2812 }
2813 }
2814 #endif // ASSERT
2815 return get_thread_name_string();
2816 }
2818 // Returns a non-NULL representation of this thread's name, or a suitable
2819 // descriptive string if there is no set name
2820 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2821 const char* name_str;
2822 oop thread_obj = threadObj();
2823 if (thread_obj != NULL) {
2824 typeArrayOop name = java_lang_Thread::name(thread_obj);
2825 if (name != NULL) {
2826 if (buf == NULL) {
2827 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2828 }
2829 else {
2830 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2831 }
2832 }
2833 else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2834 name_str = "<no-name - thread is attaching>";
2835 }
2836 else {
2837 name_str = Thread::name();
2838 }
2839 }
2840 else {
2841 name_str = Thread::name();
2842 }
2843 assert(name_str != NULL, "unexpected NULL thread name");
2844 return name_str;
2845 }
2848 const char* JavaThread::get_threadgroup_name() const {
2849 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2850 oop thread_obj = threadObj();
2851 if (thread_obj != NULL) {
2852 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2853 if (thread_group != NULL) {
2854 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2855 // ThreadGroup.name can be null
2856 if (name != NULL) {
2857 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2858 return str;
2859 }
2860 }
2861 }
2862 return NULL;
2863 }
2865 const char* JavaThread::get_parent_name() const {
2866 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2867 oop thread_obj = threadObj();
2868 if (thread_obj != NULL) {
2869 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2870 if (thread_group != NULL) {
2871 oop parent = java_lang_ThreadGroup::parent(thread_group);
2872 if (parent != NULL) {
2873 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2874 // ThreadGroup.name can be null
2875 if (name != NULL) {
2876 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2877 return str;
2878 }
2879 }
2880 }
2881 }
2882 return NULL;
2883 }
2885 ThreadPriority JavaThread::java_priority() const {
2886 oop thr_oop = threadObj();
2887 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2888 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2889 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2890 return priority;
2891 }
2893 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2895 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2896 // Link Java Thread object <-> C++ Thread
2898 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2899 // and put it into a new Handle. The Handle "thread_oop" can then
2900 // be used to pass the C++ thread object to other methods.
2902 // Set the Java level thread object (jthread) field of the
2903 // new thread (a JavaThread *) to C++ thread object using the
2904 // "thread_oop" handle.
2906 // Set the thread field (a JavaThread *) of the
2907 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2909 Handle thread_oop(Thread::current(),
2910 JNIHandles::resolve_non_null(jni_thread));
2911 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2912 "must be initialized");
2913 set_threadObj(thread_oop());
2914 java_lang_Thread::set_thread(thread_oop(), this);
2916 if (prio == NoPriority) {
2917 prio = java_lang_Thread::priority(thread_oop());
2918 assert(prio != NoPriority, "A valid priority should be present");
2919 }
2921 // Push the Java priority down to the native thread; needs Threads_lock
2922 Thread::set_priority(this, prio);
2924 // Add the new thread to the Threads list and set it in motion.
2925 // We must have threads lock in order to call Threads::add.
2926 // It is crucial that we do not block before the thread is
2927 // added to the Threads list for if a GC happens, then the java_thread oop
2928 // will not be visited by GC.
2929 Threads::add(this);
2930 }
2932 oop JavaThread::current_park_blocker() {
2933 // Support for JSR-166 locks
2934 oop thread_oop = threadObj();
2935 if (thread_oop != NULL &&
2936 JDK_Version::current().supports_thread_park_blocker()) {
2937 return java_lang_Thread::park_blocker(thread_oop);
2938 }
2939 return NULL;
2940 }
2943 void JavaThread::print_stack_on(outputStream* st) {
2944 if (!has_last_Java_frame()) return;
2945 ResourceMark rm;
2946 HandleMark hm;
2948 RegisterMap reg_map(this);
2949 vframe* start_vf = last_java_vframe(®_map);
2950 int count = 0;
2951 for (vframe* f = start_vf; f; f = f->sender() ) {
2952 if (f->is_java_frame()) {
2953 javaVFrame* jvf = javaVFrame::cast(f);
2954 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2956 // Print out lock information
2957 if (JavaMonitorsInStackTrace) {
2958 jvf->print_lock_info_on(st, count);
2959 }
2960 } else {
2961 // Ignore non-Java frames
2962 }
2964 // Bail-out case for too deep stacks
2965 count++;
2966 if (MaxJavaStackTraceDepth == count) return;
2967 }
2968 }
2971 // JVMTI PopFrame support
2972 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2973 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2974 if (in_bytes(size_in_bytes) != 0) {
2975 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2976 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2977 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2978 }
2979 }
2981 void* JavaThread::popframe_preserved_args() {
2982 return _popframe_preserved_args;
2983 }
2985 ByteSize JavaThread::popframe_preserved_args_size() {
2986 return in_ByteSize(_popframe_preserved_args_size);
2987 }
2989 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2990 int sz = in_bytes(popframe_preserved_args_size());
2991 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2992 return in_WordSize(sz / wordSize);
2993 }
2995 void JavaThread::popframe_free_preserved_args() {
2996 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2997 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread);
2998 _popframe_preserved_args = NULL;
2999 _popframe_preserved_args_size = 0;
3000 }
3002 #ifndef PRODUCT
3004 void JavaThread::trace_frames() {
3005 tty->print_cr("[Describe stack]");
3006 int frame_no = 1;
3007 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3008 tty->print(" %d. ", frame_no++);
3009 fst.current()->print_value_on(tty,this);
3010 tty->cr();
3011 }
3012 }
3014 class PrintAndVerifyOopClosure: public OopClosure {
3015 protected:
3016 template <class T> inline void do_oop_work(T* p) {
3017 oop obj = oopDesc::load_decode_heap_oop(p);
3018 if (obj == NULL) return;
3019 tty->print(INTPTR_FORMAT ": ", p);
3020 if (obj->is_oop_or_null()) {
3021 if (obj->is_objArray()) {
3022 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3023 } else {
3024 obj->print();
3025 }
3026 } else {
3027 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3028 }
3029 tty->cr();
3030 }
3031 public:
3032 virtual void do_oop(oop* p) { do_oop_work(p); }
3033 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3034 };
3037 static void oops_print(frame* f, const RegisterMap *map) {
3038 PrintAndVerifyOopClosure print;
3039 f->print_value();
3040 f->oops_do(&print, NULL, (RegisterMap*)map);
3041 }
3043 // Print our all the locations that contain oops and whether they are
3044 // valid or not. This useful when trying to find the oldest frame
3045 // where an oop has gone bad since the frame walk is from youngest to
3046 // oldest.
3047 void JavaThread::trace_oops() {
3048 tty->print_cr("[Trace oops]");
3049 frames_do(oops_print);
3050 }
3053 #ifdef ASSERT
3054 // Print or validate the layout of stack frames
3055 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3056 ResourceMark rm;
3057 PRESERVE_EXCEPTION_MARK;
3058 FrameValues values;
3059 int frame_no = 0;
3060 for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3061 fst.current()->describe(values, ++frame_no);
3062 if (depth == frame_no) break;
3063 }
3064 if (validate_only) {
3065 values.validate();
3066 } else {
3067 tty->print_cr("[Describe stack layout]");
3068 values.print(this);
3069 }
3070 }
3071 #endif
3073 void JavaThread::trace_stack_from(vframe* start_vf) {
3074 ResourceMark rm;
3075 int vframe_no = 1;
3076 for (vframe* f = start_vf; f; f = f->sender() ) {
3077 if (f->is_java_frame()) {
3078 javaVFrame::cast(f)->print_activation(vframe_no++);
3079 } else {
3080 f->print();
3081 }
3082 if (vframe_no > StackPrintLimit) {
3083 tty->print_cr("...<more frames>...");
3084 return;
3085 }
3086 }
3087 }
3090 void JavaThread::trace_stack() {
3091 if (!has_last_Java_frame()) return;
3092 ResourceMark rm;
3093 HandleMark hm;
3094 RegisterMap reg_map(this);
3095 trace_stack_from(last_java_vframe(®_map));
3096 }
3099 #endif // PRODUCT
3102 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3103 assert(reg_map != NULL, "a map must be given");
3104 frame f = last_frame();
3105 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
3106 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3107 }
3108 return NULL;
3109 }
3112 Klass* JavaThread::security_get_caller_class(int depth) {
3113 vframeStream vfst(this);
3114 vfst.security_get_caller_frame(depth);
3115 if (!vfst.at_end()) {
3116 return vfst.method()->method_holder();
3117 }
3118 return NULL;
3119 }
3121 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3122 assert(thread->is_Compiler_thread(), "must be compiler thread");
3123 CompileBroker::compiler_thread_loop();
3124 }
3126 // Create a CompilerThread
3127 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
3128 : JavaThread(&compiler_thread_entry) {
3129 _env = NULL;
3130 _log = NULL;
3131 _task = NULL;
3132 _queue = queue;
3133 _counters = counters;
3134 _buffer_blob = NULL;
3135 _scanned_nmethod = NULL;
3137 #ifndef PRODUCT
3138 _ideal_graph_printer = NULL;
3139 #endif
3140 }
3142 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3143 JavaThread::oops_do(f, cf);
3144 if (_scanned_nmethod != NULL && cf != NULL) {
3145 // Safepoints can occur when the sweeper is scanning an nmethod so
3146 // process it here to make sure it isn't unloaded in the middle of
3147 // a scan.
3148 cf->do_code_blob(_scanned_nmethod);
3149 }
3150 }
3152 // ======= Threads ========
3154 // The Threads class links together all active threads, and provides
3155 // operations over all threads. It is protected by its own Mutex
3156 // lock, which is also used in other contexts to protect thread
3157 // operations from having the thread being operated on from exiting
3158 // and going away unexpectedly (e.g., safepoint synchronization)
3160 JavaThread* Threads::_thread_list = NULL;
3161 int Threads::_number_of_threads = 0;
3162 int Threads::_number_of_non_daemon_threads = 0;
3163 int Threads::_return_code = 0;
3164 size_t JavaThread::_stack_size_at_create = 0;
3165 #ifdef ASSERT
3166 bool Threads::_vm_complete = false;
3167 #endif
3169 // All JavaThreads
3170 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3172 void os_stream();
3174 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3175 void Threads::threads_do(ThreadClosure* tc) {
3176 assert_locked_or_safepoint(Threads_lock);
3177 // ALL_JAVA_THREADS iterates through all JavaThreads
3178 ALL_JAVA_THREADS(p) {
3179 tc->do_thread(p);
3180 }
3181 // Someday we could have a table or list of all non-JavaThreads.
3182 // For now, just manually iterate through them.
3183 tc->do_thread(VMThread::vm_thread());
3184 Universe::heap()->gc_threads_do(tc);
3185 WatcherThread *wt = WatcherThread::watcher_thread();
3186 // Strictly speaking, the following NULL check isn't sufficient to make sure
3187 // the data for WatcherThread is still valid upon being examined. However,
3188 // considering that WatchThread terminates when the VM is on the way to
3189 // exit at safepoint, the chance of the above is extremely small. The right
3190 // way to prevent termination of WatcherThread would be to acquire
3191 // Terminator_lock, but we can't do that without violating the lock rank
3192 // checking in some cases.
3193 if (wt != NULL)
3194 tc->do_thread(wt);
3196 // If CompilerThreads ever become non-JavaThreads, add them here
3197 }
3199 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3201 extern void JDK_Version_init();
3203 // Check version
3204 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3206 // Initialize the output stream module
3207 ostream_init();
3209 // Process java launcher properties.
3210 Arguments::process_sun_java_launcher_properties(args);
3212 // Initialize the os module before using TLS
3213 os::init();
3215 // Initialize system properties.
3216 Arguments::init_system_properties();
3218 // So that JDK version can be used as a discrimintor when parsing arguments
3219 JDK_Version_init();
3221 // Update/Initialize System properties after JDK version number is known
3222 Arguments::init_version_specific_system_properties();
3224 // Parse arguments
3225 jint parse_result = Arguments::parse(args);
3226 if (parse_result != JNI_OK) return parse_result;
3228 if (PauseAtStartup) {
3229 os::pause();
3230 }
3232 #ifndef USDT2
3233 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3234 #else /* USDT2 */
3235 HOTSPOT_VM_INIT_BEGIN();
3236 #endif /* USDT2 */
3238 // Record VM creation timing statistics
3239 TraceVmCreationTime create_vm_timer;
3240 create_vm_timer.start();
3242 // Timing (must come after argument parsing)
3243 TraceTime timer("Create VM", TraceStartupTime);
3245 // Initialize the os module after parsing the args
3246 jint os_init_2_result = os::init_2();
3247 if (os_init_2_result != JNI_OK) return os_init_2_result;
3249 // intialize TLS
3250 ThreadLocalStorage::init();
3252 // Bootstrap native memory tracking, so it can start recording memory
3253 // activities before worker thread is started. This is the first phase
3254 // of bootstrapping, VM is currently running in single-thread mode.
3255 MemTracker::bootstrap_single_thread();
3257 // Initialize output stream logging
3258 ostream_init_log();
3260 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3261 // Must be before create_vm_init_agents()
3262 if (Arguments::init_libraries_at_startup()) {
3263 convert_vm_init_libraries_to_agents();
3264 }
3266 // Launch -agentlib/-agentpath and converted -Xrun agents
3267 if (Arguments::init_agents_at_startup()) {
3268 create_vm_init_agents();
3269 }
3271 // Initialize Threads state
3272 _thread_list = NULL;
3273 _number_of_threads = 0;
3274 _number_of_non_daemon_threads = 0;
3276 // Initialize global data structures and create system classes in heap
3277 vm_init_globals();
3279 // Attach the main thread to this os thread
3280 JavaThread* main_thread = new JavaThread();
3281 main_thread->set_thread_state(_thread_in_vm);
3282 // must do this before set_active_handles and initialize_thread_local_storage
3283 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3284 // change the stack size recorded here to one based on the java thread
3285 // stacksize. This adjusted size is what is used to figure the placement
3286 // of the guard pages.
3287 main_thread->record_stack_base_and_size();
3288 main_thread->initialize_thread_local_storage();
3290 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3292 if (!main_thread->set_as_starting_thread()) {
3293 vm_shutdown_during_initialization(
3294 "Failed necessary internal allocation. Out of swap space");
3295 delete main_thread;
3296 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3297 return JNI_ENOMEM;
3298 }
3300 // Enable guard page *after* os::create_main_thread(), otherwise it would
3301 // crash Linux VM, see notes in os_linux.cpp.
3302 main_thread->create_stack_guard_pages();
3304 // Initialize Java-Level synchronization subsystem
3305 ObjectMonitor::Initialize() ;
3307 // Second phase of bootstrapping, VM is about entering multi-thread mode
3308 MemTracker::bootstrap_multi_thread();
3310 // Initialize global modules
3311 jint status = init_globals();
3312 if (status != JNI_OK) {
3313 delete main_thread;
3314 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3315 return status;
3316 }
3318 // Should be done after the heap is fully created
3319 main_thread->cache_global_variables();
3321 HandleMark hm;
3323 { MutexLocker mu(Threads_lock);
3324 Threads::add(main_thread);
3325 }
3327 // Any JVMTI raw monitors entered in onload will transition into
3328 // real raw monitor. VM is setup enough here for raw monitor enter.
3329 JvmtiExport::transition_pending_onload_raw_monitors();
3331 if (VerifyBeforeGC &&
3332 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3333 Universe::heap()->prepare_for_verify();
3334 Universe::verify(); // make sure we're starting with a clean slate
3335 }
3337 // Fully start NMT
3338 MemTracker::start();
3340 // Create the VMThread
3341 { TraceTime timer("Start VMThread", TraceStartupTime);
3342 VMThread::create();
3343 Thread* vmthread = VMThread::vm_thread();
3345 if (!os::create_thread(vmthread, os::vm_thread))
3346 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3348 // Wait for the VM thread to become ready, and VMThread::run to initialize
3349 // Monitors can have spurious returns, must always check another state flag
3350 {
3351 MutexLocker ml(Notify_lock);
3352 os::start_thread(vmthread);
3353 while (vmthread->active_handles() == NULL) {
3354 Notify_lock->wait();
3355 }
3356 }
3357 }
3359 assert (Universe::is_fully_initialized(), "not initialized");
3360 EXCEPTION_MARK;
3362 // At this point, the Universe is initialized, but we have not executed
3363 // any byte code. Now is a good time (the only time) to dump out the
3364 // internal state of the JVM for sharing.
3365 if (DumpSharedSpaces) {
3366 MetaspaceShared::preload_and_dump(CHECK_0);
3367 ShouldNotReachHere();
3368 }
3370 // Always call even when there are not JVMTI environments yet, since environments
3371 // may be attached late and JVMTI must track phases of VM execution
3372 JvmtiExport::enter_start_phase();
3374 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3375 JvmtiExport::post_vm_start();
3377 {
3378 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3380 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3381 create_vm_init_libraries();
3382 }
3384 if (InitializeJavaLangString) {
3385 initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3386 } else {
3387 warning("java.lang.String not initialized");
3388 }
3390 if (AggressiveOpts) {
3391 {
3392 // Forcibly initialize java/util/HashMap and mutate the private
3393 // static final "frontCacheEnabled" field before we start creating instances
3394 #ifdef ASSERT
3395 Klass* tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3396 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3397 #endif
3398 Klass* k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3399 KlassHandle k = KlassHandle(THREAD, k_o);
3400 guarantee(k.not_null(), "Must find java/util/HashMap");
3401 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3402 ik->initialize(CHECK_0);
3403 fieldDescriptor fd;
3404 // Possible we might not find this field; if so, don't break
3405 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3406 k()->java_mirror()->bool_field_put(fd.offset(), true);
3407 }
3408 }
3410 if (UseStringCache) {
3411 // Forcibly initialize java/lang/StringValue and mutate the private
3412 // static final "stringCacheEnabled" field before we start creating instances
3413 Klass* k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3414 // Possible that StringValue isn't present: if so, silently don't break
3415 if (k_o != NULL) {
3416 KlassHandle k = KlassHandle(THREAD, k_o);
3417 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3418 ik->initialize(CHECK_0);
3419 fieldDescriptor fd;
3420 // Possible we might not find this field: if so, silently don't break
3421 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3422 k()->java_mirror()->bool_field_put(fd.offset(), true);
3423 }
3424 }
3425 }
3426 }
3428 // Initialize java_lang.System (needed before creating the thread)
3429 if (InitializeJavaLangSystem) {
3430 initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3431 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3432 Handle thread_group = create_initial_thread_group(CHECK_0);
3433 Universe::set_main_thread_group(thread_group());
3434 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3435 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3436 main_thread->set_threadObj(thread_object);
3437 // Set thread status to running since main thread has
3438 // been started and running.
3439 java_lang_Thread::set_thread_status(thread_object,
3440 java_lang_Thread::RUNNABLE);
3442 // The VM preresolve methods to these classes. Make sure that get initialized
3443 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3444 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0);
3445 // The VM creates & returns objects of this class. Make sure it's initialized.
3446 initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3447 call_initializeSystemClass(CHECK_0);
3449 // get the Java runtime name after java.lang.System is initialized
3450 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3451 } else {
3452 warning("java.lang.System not initialized");
3453 }
3455 // an instance of OutOfMemory exception has been allocated earlier
3456 if (InitializeJavaLangExceptionsErrors) {
3457 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3458 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3459 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3460 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3461 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3462 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3463 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3464 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK_0);
3465 } else {
3466 warning("java.lang.OutOfMemoryError has not been initialized");
3467 warning("java.lang.NullPointerException has not been initialized");
3468 warning("java.lang.ClassCastException has not been initialized");
3469 warning("java.lang.ArrayStoreException has not been initialized");
3470 warning("java.lang.ArithmeticException has not been initialized");
3471 warning("java.lang.StackOverflowError has not been initialized");
3472 warning("java.lang.IllegalArgumentException has not been initialized");
3473 }
3474 }
3476 // See : bugid 4211085.
3477 // Background : the static initializer of java.lang.Compiler tries to read
3478 // property"java.compiler" and read & write property "java.vm.info".
3479 // When a security manager is installed through the command line
3480 // option "-Djava.security.manager", the above properties are not
3481 // readable and the static initializer for java.lang.Compiler fails
3482 // resulting in a NoClassDefFoundError. This can happen in any
3483 // user code which calls methods in java.lang.Compiler.
3484 // Hack : the hack is to pre-load and initialize this class, so that only
3485 // system domains are on the stack when the properties are read.
3486 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3487 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3488 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3489 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3490 // Once that is done, we should remove this hack.
3491 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3493 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3494 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3495 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3496 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3497 // This should also be taken out as soon as 4211383 gets fixed.
3498 reset_vm_info_property(CHECK_0);
3500 quicken_jni_functions();
3502 // Must be run after init_ft which initializes ft_enabled
3503 if (TRACE_INITIALIZE() != JNI_OK) {
3504 vm_exit_during_initialization("Failed to initialize tracing backend");
3505 }
3507 // Set flag that basic initialization has completed. Used by exceptions and various
3508 // debug stuff, that does not work until all basic classes have been initialized.
3509 set_init_completed();
3511 #ifndef USDT2
3512 HS_DTRACE_PROBE(hotspot, vm__init__end);
3513 #else /* USDT2 */
3514 HOTSPOT_VM_INIT_END();
3515 #endif /* USDT2 */
3517 // record VM initialization completion time
3518 Management::record_vm_init_completed();
3520 // Compute system loader. Note that this has to occur after set_init_completed, since
3521 // valid exceptions may be thrown in the process.
3522 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3523 // set_init_completed has just been called, causing exceptions not to be shortcut
3524 // anymore. We call vm_exit_during_initialization directly instead.
3525 SystemDictionary::compute_java_system_loader(THREAD);
3526 if (HAS_PENDING_EXCEPTION) {
3527 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3528 }
3530 #ifndef SERIALGC
3531 // Support for ConcurrentMarkSweep. This should be cleaned up
3532 // and better encapsulated. The ugly nested if test would go away
3533 // once things are properly refactored. XXX YSR
3534 if (UseConcMarkSweepGC || UseG1GC) {
3535 if (UseConcMarkSweepGC) {
3536 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3537 } else {
3538 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3539 }
3540 if (HAS_PENDING_EXCEPTION) {
3541 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3542 }
3543 }
3544 #endif // SERIALGC
3546 // Always call even when there are not JVMTI environments yet, since environments
3547 // may be attached late and JVMTI must track phases of VM execution
3548 JvmtiExport::enter_live_phase();
3550 // Signal Dispatcher needs to be started before VMInit event is posted
3551 os::signal_init();
3553 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3554 if (!DisableAttachMechanism) {
3555 if (StartAttachListener || AttachListener::init_at_startup()) {
3556 AttachListener::init();
3557 }
3558 }
3560 // Launch -Xrun agents
3561 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3562 // back-end can launch with -Xdebug -Xrunjdwp.
3563 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3564 create_vm_init_libraries();
3565 }
3567 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3568 JvmtiExport::post_vm_initialized();
3570 if (!TRACE_START()) {
3571 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3572 }
3574 if (CleanChunkPoolAsync) {
3575 Chunk::start_chunk_pool_cleaner_task();
3576 }
3578 // initialize compiler(s)
3579 CompileBroker::compilation_init();
3581 Management::initialize(THREAD);
3582 if (HAS_PENDING_EXCEPTION) {
3583 // management agent fails to start possibly due to
3584 // configuration problem and is responsible for printing
3585 // stack trace if appropriate. Simply exit VM.
3586 vm_exit(1);
3587 }
3589 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3590 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3591 if (MemProfiling) MemProfiler::engage();
3592 StatSampler::engage();
3593 if (CheckJNICalls) JniPeriodicChecker::engage();
3595 BiasedLocking::init();
3597 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3598 call_postVMInitHook(THREAD);
3599 // The Java side of PostVMInitHook.run must deal with all
3600 // exceptions and provide means of diagnosis.
3601 if (HAS_PENDING_EXCEPTION) {
3602 CLEAR_PENDING_EXCEPTION;
3603 }
3604 }
3606 // Start up the WatcherThread if there are any periodic tasks
3607 // NOTE: All PeriodicTasks should be registered by now. If they
3608 // aren't, late joiners might appear to start slowly (we might
3609 // take a while to process their first tick).
3610 if (PeriodicTask::num_tasks() > 0) {
3611 WatcherThread::start();
3612 }
3614 // Give os specific code one last chance to start
3615 os::init_3();
3617 create_vm_timer.end();
3618 #ifdef ASSERT
3619 _vm_complete = true;
3620 #endif
3621 return JNI_OK;
3622 }
3624 // type for the Agent_OnLoad and JVM_OnLoad entry points
3625 extern "C" {
3626 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3627 }
3628 // Find a command line agent library and return its entry point for
3629 // -agentlib: -agentpath: -Xrun
3630 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3631 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3632 OnLoadEntry_t on_load_entry = NULL;
3633 void *library = agent->os_lib(); // check if we have looked it up before
3635 if (library == NULL) {
3636 char buffer[JVM_MAXPATHLEN];
3637 char ebuf[1024];
3638 const char *name = agent->name();
3639 const char *msg = "Could not find agent library ";
3641 if (agent->is_absolute_path()) {
3642 library = os::dll_load(name, ebuf, sizeof ebuf);
3643 if (library == NULL) {
3644 const char *sub_msg = " in absolute path, with error: ";
3645 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3646 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3647 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3648 // If we can't find the agent, exit.
3649 vm_exit_during_initialization(buf, NULL);
3650 FREE_C_HEAP_ARRAY(char, buf, mtThread);
3651 }
3652 } else {
3653 // Try to load the agent from the standard dll directory
3654 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3655 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3656 #ifdef KERNEL
3657 // Download instrument dll
3658 if (library == NULL && strcmp(name, "instrument") == 0) {
3659 char *props = Arguments::get_kernel_properties();
3660 char *home = Arguments::get_java_home();
3661 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3662 " sun.jkernel.DownloadManager -download client_jvm";
3663 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3664 char *cmd = NEW_C_HEAP_ARRAY(char, length, mtThread);
3665 jio_snprintf(cmd, length, fmt, home, props);
3666 int status = os::fork_and_exec(cmd);
3667 FreeHeap(props);
3668 if (status == -1) {
3669 warning(cmd);
3670 vm_exit_during_initialization("fork_and_exec failed: %s",
3671 strerror(errno));
3672 }
3673 FREE_C_HEAP_ARRAY(char, cmd, mtThread);
3674 // when this comes back the instrument.dll should be where it belongs.
3675 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3676 }
3677 #endif // KERNEL
3678 if (library == NULL) { // Try the local directory
3679 char ns[1] = {0};
3680 os::dll_build_name(buffer, sizeof(buffer), ns, name);
3681 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3682 if (library == NULL) {
3683 const char *sub_msg = " on the library path, with error: ";
3684 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3685 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3686 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3687 // If we can't find the agent, exit.
3688 vm_exit_during_initialization(buf, NULL);
3689 FREE_C_HEAP_ARRAY(char, buf, mtThread);
3690 }
3691 }
3692 }
3693 agent->set_os_lib(library);
3694 }
3696 // Find the OnLoad function.
3697 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3698 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3699 if (on_load_entry != NULL) break;
3700 }
3701 return on_load_entry;
3702 }
3704 // Find the JVM_OnLoad entry point
3705 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3706 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3707 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3708 }
3710 // Find the Agent_OnLoad entry point
3711 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3712 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3713 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3714 }
3716 // For backwards compatibility with -Xrun
3717 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3718 // treated like -agentpath:
3719 // Must be called before agent libraries are created
3720 void Threads::convert_vm_init_libraries_to_agents() {
3721 AgentLibrary* agent;
3722 AgentLibrary* next;
3724 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3725 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3726 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3728 // If there is an JVM_OnLoad function it will get called later,
3729 // otherwise see if there is an Agent_OnLoad
3730 if (on_load_entry == NULL) {
3731 on_load_entry = lookup_agent_on_load(agent);
3732 if (on_load_entry != NULL) {
3733 // switch it to the agent list -- so that Agent_OnLoad will be called,
3734 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3735 Arguments::convert_library_to_agent(agent);
3736 } else {
3737 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3738 }
3739 }
3740 }
3741 }
3743 // Create agents for -agentlib: -agentpath: and converted -Xrun
3744 // Invokes Agent_OnLoad
3745 // Called very early -- before JavaThreads exist
3746 void Threads::create_vm_init_agents() {
3747 extern struct JavaVM_ main_vm;
3748 AgentLibrary* agent;
3750 JvmtiExport::enter_onload_phase();
3751 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3752 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3754 if (on_load_entry != NULL) {
3755 // Invoke the Agent_OnLoad function
3756 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3757 if (err != JNI_OK) {
3758 vm_exit_during_initialization("agent library failed to init", agent->name());
3759 }
3760 } else {
3761 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3762 }
3763 }
3764 JvmtiExport::enter_primordial_phase();
3765 }
3767 extern "C" {
3768 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3769 }
3771 void Threads::shutdown_vm_agents() {
3772 // Send any Agent_OnUnload notifications
3773 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3774 extern struct JavaVM_ main_vm;
3775 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3777 // Find the Agent_OnUnload function.
3778 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3779 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3780 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3782 // Invoke the Agent_OnUnload function
3783 if (unload_entry != NULL) {
3784 JavaThread* thread = JavaThread::current();
3785 ThreadToNativeFromVM ttn(thread);
3786 HandleMark hm(thread);
3787 (*unload_entry)(&main_vm);
3788 break;
3789 }
3790 }
3791 }
3792 }
3794 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3795 // Invokes JVM_OnLoad
3796 void Threads::create_vm_init_libraries() {
3797 extern struct JavaVM_ main_vm;
3798 AgentLibrary* agent;
3800 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3801 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3803 if (on_load_entry != NULL) {
3804 // Invoke the JVM_OnLoad function
3805 JavaThread* thread = JavaThread::current();
3806 ThreadToNativeFromVM ttn(thread);
3807 HandleMark hm(thread);
3808 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3809 if (err != JNI_OK) {
3810 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3811 }
3812 } else {
3813 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3814 }
3815 }
3816 }
3818 // Last thread running calls java.lang.Shutdown.shutdown()
3819 void JavaThread::invoke_shutdown_hooks() {
3820 HandleMark hm(this);
3822 // We could get here with a pending exception, if so clear it now.
3823 if (this->has_pending_exception()) {
3824 this->clear_pending_exception();
3825 }
3827 EXCEPTION_MARK;
3828 Klass* k =
3829 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3830 THREAD);
3831 if (k != NULL) {
3832 // SystemDictionary::resolve_or_null will return null if there was
3833 // an exception. If we cannot load the Shutdown class, just don't
3834 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3835 // and finalizers (if runFinalizersOnExit is set) won't be run.
3836 // Note that if a shutdown hook was registered or runFinalizersOnExit
3837 // was called, the Shutdown class would have already been loaded
3838 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3839 instanceKlassHandle shutdown_klass (THREAD, k);
3840 JavaValue result(T_VOID);
3841 JavaCalls::call_static(&result,
3842 shutdown_klass,
3843 vmSymbols::shutdown_method_name(),
3844 vmSymbols::void_method_signature(),
3845 THREAD);
3846 }
3847 CLEAR_PENDING_EXCEPTION;
3848 }
3850 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3851 // the program falls off the end of main(). Another VM exit path is through
3852 // vm_exit() when the program calls System.exit() to return a value or when
3853 // there is a serious error in VM. The two shutdown paths are not exactly
3854 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3855 // and VM_Exit op at VM level.
3856 //
3857 // Shutdown sequence:
3858 // + Shutdown native memory tracking if it is on
3859 // + Wait until we are the last non-daemon thread to execute
3860 // <-- every thing is still working at this moment -->
3861 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3862 // shutdown hooks, run finalizers if finalization-on-exit
3863 // + Call before_exit(), prepare for VM exit
3864 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3865 // currently the only user of this mechanism is File.deleteOnExit())
3866 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3867 // post thread end and vm death events to JVMTI,
3868 // stop signal thread
3869 // + Call JavaThread::exit(), it will:
3870 // > release JNI handle blocks, remove stack guard pages
3871 // > remove this thread from Threads list
3872 // <-- no more Java code from this thread after this point -->
3873 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3874 // the compiler threads at safepoint
3875 // <-- do not use anything that could get blocked by Safepoint -->
3876 // + Disable tracing at JNI/JVM barriers
3877 // + Set _vm_exited flag for threads that are still running native code
3878 // + Delete this thread
3879 // + Call exit_globals()
3880 // > deletes tty
3881 // > deletes PerfMemory resources
3882 // + Return to caller
3884 bool Threads::destroy_vm() {
3885 JavaThread* thread = JavaThread::current();
3887 #ifdef ASSERT
3888 _vm_complete = false;
3889 #endif
3890 // Wait until we are the last non-daemon thread to execute
3891 { MutexLocker nu(Threads_lock);
3892 while (Threads::number_of_non_daemon_threads() > 1 )
3893 // This wait should make safepoint checks, wait without a timeout,
3894 // and wait as a suspend-equivalent condition.
3895 //
3896 // Note: If the FlatProfiler is running and this thread is waiting
3897 // for another non-daemon thread to finish, then the FlatProfiler
3898 // is waiting for the external suspend request on this thread to
3899 // complete. wait_for_ext_suspend_completion() will eventually
3900 // timeout, but that takes time. Making this wait a suspend-
3901 // equivalent condition solves that timeout problem.
3902 //
3903 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3904 Mutex::_as_suspend_equivalent_flag);
3905 }
3907 // Shutdown NMT before exit. Otherwise,
3908 // it will run into trouble when system destroys static variables.
3909 MemTracker::shutdown(MemTracker::NMT_normal);
3911 // Hang forever on exit if we are reporting an error.
3912 if (ShowMessageBoxOnError && is_error_reported()) {
3913 os::infinite_sleep();
3914 }
3915 os::wait_for_keypress_at_exit();
3917 if (JDK_Version::is_jdk12x_version()) {
3918 // We are the last thread running, so check if finalizers should be run.
3919 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3920 HandleMark rm(thread);
3921 Universe::run_finalizers_on_exit();
3922 } else {
3923 // run Java level shutdown hooks
3924 thread->invoke_shutdown_hooks();
3925 }
3927 before_exit(thread);
3929 thread->exit(true);
3931 // Stop VM thread.
3932 {
3933 // 4945125 The vm thread comes to a safepoint during exit.
3934 // GC vm_operations can get caught at the safepoint, and the
3935 // heap is unparseable if they are caught. Grab the Heap_lock
3936 // to prevent this. The GC vm_operations will not be able to
3937 // queue until after the vm thread is dead.
3938 // After this point, we'll never emerge out of the safepoint before
3939 // the VM exits, so concurrent GC threads do not need to be explicitly
3940 // stopped; they remain inactive until the process exits.
3941 // Note: some concurrent G1 threads may be running during a safepoint,
3942 // but these will not be accessing the heap, just some G1-specific side
3943 // data structures that are not accessed by any other threads but them
3944 // after this point in a terminal safepoint.
3946 MutexLocker ml(Heap_lock);
3948 VMThread::wait_for_vm_thread_exit();
3949 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3950 VMThread::destroy();
3951 }
3953 // clean up ideal graph printers
3954 #if defined(COMPILER2) && !defined(PRODUCT)
3955 IdealGraphPrinter::clean_up();
3956 #endif
3958 // Now, all Java threads are gone except daemon threads. Daemon threads
3959 // running Java code or in VM are stopped by the Safepoint. However,
3960 // daemon threads executing native code are still running. But they
3961 // will be stopped at native=>Java/VM barriers. Note that we can't
3962 // simply kill or suspend them, as it is inherently deadlock-prone.
3964 #ifndef PRODUCT
3965 // disable function tracing at JNI/JVM barriers
3966 TraceJNICalls = false;
3967 TraceJVMCalls = false;
3968 TraceRuntimeCalls = false;
3969 #endif
3971 VM_Exit::set_vm_exited();
3973 notify_vm_shutdown();
3975 delete thread;
3977 // exit_globals() will delete tty
3978 exit_globals();
3980 return true;
3981 }
3984 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3985 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3986 return is_supported_jni_version(version);
3987 }
3990 jboolean Threads::is_supported_jni_version(jint version) {
3991 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3992 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3993 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3994 return JNI_FALSE;
3995 }
3998 void Threads::add(JavaThread* p, bool force_daemon) {
3999 // The threads lock must be owned at this point
4000 assert_locked_or_safepoint(Threads_lock);
4002 // See the comment for this method in thread.hpp for its purpose and
4003 // why it is called here.
4004 p->initialize_queues();
4005 p->set_next(_thread_list);
4006 _thread_list = p;
4007 _number_of_threads++;
4008 oop threadObj = p->threadObj();
4009 bool daemon = true;
4010 // Bootstrapping problem: threadObj can be null for initial
4011 // JavaThread (or for threads attached via JNI)
4012 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4013 _number_of_non_daemon_threads++;
4014 daemon = false;
4015 }
4017 p->set_safepoint_visible(true);
4019 ThreadService::add_thread(p, daemon);
4021 // Possible GC point.
4022 Events::log(p, "Thread added: " INTPTR_FORMAT, p);
4023 }
4025 void Threads::remove(JavaThread* p) {
4026 // Extra scope needed for Thread_lock, so we can check
4027 // that we do not remove thread without safepoint code notice
4028 { MutexLocker ml(Threads_lock);
4030 assert(includes(p), "p must be present");
4032 JavaThread* current = _thread_list;
4033 JavaThread* prev = NULL;
4035 while (current != p) {
4036 prev = current;
4037 current = current->next();
4038 }
4040 if (prev) {
4041 prev->set_next(current->next());
4042 } else {
4043 _thread_list = p->next();
4044 }
4045 _number_of_threads--;
4046 oop threadObj = p->threadObj();
4047 bool daemon = true;
4048 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4049 _number_of_non_daemon_threads--;
4050 daemon = false;
4052 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4053 // on destroy_vm will wake up.
4054 if (number_of_non_daemon_threads() == 1)
4055 Threads_lock->notify_all();
4056 }
4057 ThreadService::remove_thread(p, daemon);
4059 // Make sure that safepoint code disregard this thread. This is needed since
4060 // the thread might mess around with locks after this point. This can cause it
4061 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4062 // of this thread since it is removed from the queue.
4063 p->set_terminated_value();
4065 // Now, this thread is not visible to safepoint
4066 p->set_safepoint_visible(false);
4068 } // unlock Threads_lock
4070 // Since Events::log uses a lock, we grab it outside the Threads_lock
4071 Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4072 }
4074 // Threads_lock must be held when this is called (or must be called during a safepoint)
4075 bool Threads::includes(JavaThread* p) {
4076 assert(Threads_lock->is_locked(), "sanity check");
4077 ALL_JAVA_THREADS(q) {
4078 if (q == p ) {
4079 return true;
4080 }
4081 }
4082 return false;
4083 }
4085 // Operations on the Threads list for GC. These are not explicitly locked,
4086 // but the garbage collector must provide a safe context for them to run.
4087 // In particular, these things should never be called when the Threads_lock
4088 // is held by some other thread. (Note: the Safepoint abstraction also
4089 // uses the Threads_lock to gurantee this property. It also makes sure that
4090 // all threads gets blocked when exiting or starting).
4092 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4093 ALL_JAVA_THREADS(p) {
4094 p->oops_do(f, cf);
4095 }
4096 VMThread::vm_thread()->oops_do(f, cf);
4097 }
4099 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
4100 // Introduce a mechanism allowing parallel threads to claim threads as
4101 // root groups. Overhead should be small enough to use all the time,
4102 // even in sequential code.
4103 SharedHeap* sh = SharedHeap::heap();
4104 // Cannot yet substitute active_workers for n_par_threads
4105 // because of G1CollectedHeap::verify() use of
4106 // SharedHeap::process_strong_roots(). n_par_threads == 0 will
4107 // turn off parallelism in process_strong_roots while active_workers
4108 // is being used for parallelism elsewhere.
4109 bool is_par = sh->n_par_threads() > 0;
4110 assert(!is_par ||
4111 (SharedHeap::heap()->n_par_threads() ==
4112 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4113 int cp = SharedHeap::heap()->strong_roots_parity();
4114 ALL_JAVA_THREADS(p) {
4115 if (p->claim_oops_do(is_par, cp)) {
4116 p->oops_do(f, cf);
4117 }
4118 }
4119 VMThread* vmt = VMThread::vm_thread();
4120 if (vmt->claim_oops_do(is_par, cp)) {
4121 vmt->oops_do(f, cf);
4122 }
4123 }
4125 #ifndef SERIALGC
4126 // Used by ParallelScavenge
4127 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4128 ALL_JAVA_THREADS(p) {
4129 q->enqueue(new ThreadRootsTask(p));
4130 }
4131 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4132 }
4134 // Used by Parallel Old
4135 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4136 ALL_JAVA_THREADS(p) {
4137 q->enqueue(new ThreadRootsMarkingTask(p));
4138 }
4139 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4140 }
4141 #endif // SERIALGC
4143 void Threads::nmethods_do(CodeBlobClosure* cf) {
4144 ALL_JAVA_THREADS(p) {
4145 p->nmethods_do(cf);
4146 }
4147 VMThread::vm_thread()->nmethods_do(cf);
4148 }
4150 void Threads::metadata_do(void f(Metadata*)) {
4151 ALL_JAVA_THREADS(p) {
4152 p->metadata_do(f);
4153 }
4154 }
4156 void Threads::gc_epilogue() {
4157 ALL_JAVA_THREADS(p) {
4158 p->gc_epilogue();
4159 }
4160 }
4162 void Threads::gc_prologue() {
4163 ALL_JAVA_THREADS(p) {
4164 p->gc_prologue();
4165 }
4166 }
4168 void Threads::deoptimized_wrt_marked_nmethods() {
4169 ALL_JAVA_THREADS(p) {
4170 p->deoptimized_wrt_marked_nmethods();
4171 }
4172 }
4175 // Get count Java threads that are waiting to enter the specified monitor.
4176 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4177 address monitor, bool doLock) {
4178 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4179 "must grab Threads_lock or be at safepoint");
4180 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4182 int i = 0;
4183 {
4184 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4185 ALL_JAVA_THREADS(p) {
4186 if (p->is_Compiler_thread()) continue;
4188 address pending = (address)p->current_pending_monitor();
4189 if (pending == monitor) { // found a match
4190 if (i < count) result->append(p); // save the first count matches
4191 i++;
4192 }
4193 }
4194 }
4195 return result;
4196 }
4199 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
4200 assert(doLock ||
4201 Threads_lock->owned_by_self() ||
4202 SafepointSynchronize::is_at_safepoint(),
4203 "must grab Threads_lock or be at safepoint");
4205 // NULL owner means not locked so we can skip the search
4206 if (owner == NULL) return NULL;
4208 {
4209 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4210 ALL_JAVA_THREADS(p) {
4211 // first, see if owner is the address of a Java thread
4212 if (owner == (address)p) return p;
4213 }
4214 }
4215 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
4216 if (UseHeavyMonitors) return NULL;
4218 //
4219 // If we didn't find a matching Java thread and we didn't force use of
4220 // heavyweight monitors, then the owner is the stack address of the
4221 // Lock Word in the owning Java thread's stack.
4222 //
4223 JavaThread* the_owner = NULL;
4224 {
4225 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4226 ALL_JAVA_THREADS(q) {
4227 if (q->is_lock_owned(owner)) {
4228 the_owner = q;
4229 break;
4230 }
4231 }
4232 }
4233 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
4234 return the_owner;
4235 }
4237 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4238 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
4239 char buf[32];
4240 st->print_cr(os::local_time_string(buf, sizeof(buf)));
4242 st->print_cr("Full thread dump %s (%s %s):",
4243 Abstract_VM_Version::vm_name(),
4244 Abstract_VM_Version::vm_release(),
4245 Abstract_VM_Version::vm_info_string()
4246 );
4247 st->cr();
4249 #ifndef SERIALGC
4250 // Dump concurrent locks
4251 ConcurrentLocksDump concurrent_locks;
4252 if (print_concurrent_locks) {
4253 concurrent_locks.dump_at_safepoint();
4254 }
4255 #endif // SERIALGC
4257 ALL_JAVA_THREADS(p) {
4258 ResourceMark rm;
4259 p->print_on(st);
4260 if (print_stacks) {
4261 if (internal_format) {
4262 p->trace_stack();
4263 } else {
4264 p->print_stack_on(st);
4265 }
4266 }
4267 st->cr();
4268 #ifndef SERIALGC
4269 if (print_concurrent_locks) {
4270 concurrent_locks.print_locks_on(p, st);
4271 }
4272 #endif // SERIALGC
4273 }
4275 VMThread::vm_thread()->print_on(st);
4276 st->cr();
4277 Universe::heap()->print_gc_threads_on(st);
4278 WatcherThread* wt = WatcherThread::watcher_thread();
4279 if (wt != NULL) wt->print_on(st);
4280 st->cr();
4281 CompileBroker::print_compiler_threads_on(st);
4282 st->flush();
4283 }
4285 // Threads::print_on_error() is called by fatal error handler. It's possible
4286 // that VM is not at safepoint and/or current thread is inside signal handler.
4287 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4288 // memory (even in resource area), it might deadlock the error handler.
4289 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4290 bool found_current = false;
4291 st->print_cr("Java Threads: ( => current thread )");
4292 ALL_JAVA_THREADS(thread) {
4293 bool is_current = (current == thread);
4294 found_current = found_current || is_current;
4296 st->print("%s", is_current ? "=>" : " ");
4298 st->print(PTR_FORMAT, thread);
4299 st->print(" ");
4300 thread->print_on_error(st, buf, buflen);
4301 st->cr();
4302 }
4303 st->cr();
4305 st->print_cr("Other Threads:");
4306 if (VMThread::vm_thread()) {
4307 bool is_current = (current == VMThread::vm_thread());
4308 found_current = found_current || is_current;
4309 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4311 st->print(PTR_FORMAT, VMThread::vm_thread());
4312 st->print(" ");
4313 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4314 st->cr();
4315 }
4316 WatcherThread* wt = WatcherThread::watcher_thread();
4317 if (wt != NULL) {
4318 bool is_current = (current == wt);
4319 found_current = found_current || is_current;
4320 st->print("%s", is_current ? "=>" : " ");
4322 st->print(PTR_FORMAT, wt);
4323 st->print(" ");
4324 wt->print_on_error(st, buf, buflen);
4325 st->cr();
4326 }
4327 if (!found_current) {
4328 st->cr();
4329 st->print("=>" PTR_FORMAT " (exited) ", current);
4330 current->print_on_error(st, buf, buflen);
4331 st->cr();
4332 }
4333 }
4335 // Internal SpinLock and Mutex
4336 // Based on ParkEvent
4338 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4339 //
4340 // We employ SpinLocks _only for low-contention, fixed-length
4341 // short-duration critical sections where we're concerned
4342 // about native mutex_t or HotSpot Mutex:: latency.
4343 // The mux construct provides a spin-then-block mutual exclusion
4344 // mechanism.
4345 //
4346 // Testing has shown that contention on the ListLock guarding gFreeList
4347 // is common. If we implement ListLock as a simple SpinLock it's common
4348 // for the JVM to devolve to yielding with little progress. This is true
4349 // despite the fact that the critical sections protected by ListLock are
4350 // extremely short.
4351 //
4352 // TODO-FIXME: ListLock should be of type SpinLock.
4353 // We should make this a 1st-class type, integrated into the lock
4354 // hierarchy as leaf-locks. Critically, the SpinLock structure
4355 // should have sufficient padding to avoid false-sharing and excessive
4356 // cache-coherency traffic.
4359 typedef volatile int SpinLockT ;
4361 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4362 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4363 return ; // normal fast-path return
4364 }
4366 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4367 TEVENT (SpinAcquire - ctx) ;
4368 int ctr = 0 ;
4369 int Yields = 0 ;
4370 for (;;) {
4371 while (*adr != 0) {
4372 ++ctr ;
4373 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4374 if (Yields > 5) {
4375 // Consider using a simple NakedSleep() instead.
4376 // Then SpinAcquire could be called by non-JVM threads
4377 Thread::current()->_ParkEvent->park(1) ;
4378 } else {
4379 os::NakedYield() ;
4380 ++Yields ;
4381 }
4382 } else {
4383 SpinPause() ;
4384 }
4385 }
4386 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4387 }
4388 }
4390 void Thread::SpinRelease (volatile int * adr) {
4391 assert (*adr != 0, "invariant") ;
4392 OrderAccess::fence() ; // guarantee at least release consistency.
4393 // Roach-motel semantics.
4394 // It's safe if subsequent LDs and STs float "up" into the critical section,
4395 // but prior LDs and STs within the critical section can't be allowed
4396 // to reorder or float past the ST that releases the lock.
4397 *adr = 0 ;
4398 }
4400 // muxAcquire and muxRelease:
4401 //
4402 // * muxAcquire and muxRelease support a single-word lock-word construct.
4403 // The LSB of the word is set IFF the lock is held.
4404 // The remainder of the word points to the head of a singly-linked list
4405 // of threads blocked on the lock.
4406 //
4407 // * The current implementation of muxAcquire-muxRelease uses its own
4408 // dedicated Thread._MuxEvent instance. If we're interested in
4409 // minimizing the peak number of extant ParkEvent instances then
4410 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4411 // as certain invariants were satisfied. Specifically, care would need
4412 // to be taken with regards to consuming unpark() "permits".
4413 // A safe rule of thumb is that a thread would never call muxAcquire()
4414 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4415 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4416 // consume an unpark() permit intended for monitorenter, for instance.
4417 // One way around this would be to widen the restricted-range semaphore
4418 // implemented in park(). Another alternative would be to provide
4419 // multiple instances of the PlatformEvent() for each thread. One
4420 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4421 //
4422 // * Usage:
4423 // -- Only as leaf locks
4424 // -- for short-term locking only as muxAcquire does not perform
4425 // thread state transitions.
4426 //
4427 // Alternatives:
4428 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4429 // but with parking or spin-then-park instead of pure spinning.
4430 // * Use Taura-Oyama-Yonenzawa locks.
4431 // * It's possible to construct a 1-0 lock if we encode the lockword as
4432 // (List,LockByte). Acquire will CAS the full lockword while Release
4433 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4434 // acquiring threads use timers (ParkTimed) to detect and recover from
4435 // the stranding window. Thread/Node structures must be aligned on 256-byte
4436 // boundaries by using placement-new.
4437 // * Augment MCS with advisory back-link fields maintained with CAS().
4438 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4439 // The validity of the backlinks must be ratified before we trust the value.
4440 // If the backlinks are invalid the exiting thread must back-track through the
4441 // the forward links, which are always trustworthy.
4442 // * Add a successor indication. The LockWord is currently encoded as
4443 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4444 // to provide the usual futile-wakeup optimization.
4445 // See RTStt for details.
4446 // * Consider schedctl.sc_nopreempt to cover the critical section.
4447 //
4450 typedef volatile intptr_t MutexT ; // Mux Lock-word
4451 enum MuxBits { LOCKBIT = 1 } ;
4453 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4454 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4455 if (w == 0) return ;
4456 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4457 return ;
4458 }
4460 TEVENT (muxAcquire - Contention) ;
4461 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4462 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4463 for (;;) {
4464 int its = (os::is_MP() ? 100 : 0) + 1 ;
4466 // Optional spin phase: spin-then-park strategy
4467 while (--its >= 0) {
4468 w = *Lock ;
4469 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4470 return ;
4471 }
4472 }
4474 Self->reset() ;
4475 Self->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 Self->OnList = 0 ; // hygiene - allows stronger asserts
4484 return ;
4485 }
4486 continue ; // Interference -- *Lock changed -- Just retry
4487 }
4488 assert (w & LOCKBIT, "invariant") ;
4489 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4490 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4491 }
4493 while (Self->OnList != 0) {
4494 Self->park() ;
4495 }
4496 }
4497 }
4499 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4500 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4501 if (w == 0) return ;
4502 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4503 return ;
4504 }
4506 TEVENT (muxAcquire - Contention) ;
4507 ParkEvent * ReleaseAfter = NULL ;
4508 if (ev == NULL) {
4509 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4510 }
4511 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4512 for (;;) {
4513 guarantee (ev->OnList == 0, "invariant") ;
4514 int its = (os::is_MP() ? 100 : 0) + 1 ;
4516 // Optional spin phase: spin-then-park strategy
4517 while (--its >= 0) {
4518 w = *Lock ;
4519 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4520 if (ReleaseAfter != NULL) {
4521 ParkEvent::Release (ReleaseAfter) ;
4522 }
4523 return ;
4524 }
4525 }
4527 ev->reset() ;
4528 ev->OnList = intptr_t(Lock) ;
4529 // The following fence() isn't _strictly necessary as the subsequent
4530 // CAS() both serializes execution and ratifies the fetched *Lock value.
4531 OrderAccess::fence();
4532 for (;;) {
4533 w = *Lock ;
4534 if ((w & LOCKBIT) == 0) {
4535 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4536 ev->OnList = 0 ;
4537 // We call ::Release while holding the outer lock, thus
4538 // artificially lengthening the critical section.
4539 // Consider deferring the ::Release() until the subsequent unlock(),
4540 // after we've dropped the outer lock.
4541 if (ReleaseAfter != NULL) {
4542 ParkEvent::Release (ReleaseAfter) ;
4543 }
4544 return ;
4545 }
4546 continue ; // Interference -- *Lock changed -- Just retry
4547 }
4548 assert (w & LOCKBIT, "invariant") ;
4549 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4550 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4551 }
4553 while (ev->OnList != 0) {
4554 ev->park() ;
4555 }
4556 }
4557 }
4559 // Release() must extract a successor from the list and then wake that thread.
4560 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4561 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4562 // Release() would :
4563 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4564 // (B) Extract a successor from the private list "in-hand"
4565 // (C) attempt to CAS() the residual back into *Lock over null.
4566 // If there were any newly arrived threads and the CAS() would fail.
4567 // In that case Release() would detach the RATs, re-merge the list in-hand
4568 // with the RATs and repeat as needed. Alternately, Release() might
4569 // detach and extract a successor, but then pass the residual list to the wakee.
4570 // The wakee would be responsible for reattaching and remerging before it
4571 // competed for the lock.
4572 //
4573 // Both "pop" and DMR are immune from ABA corruption -- there can be
4574 // multiple concurrent pushers, but only one popper or detacher.
4575 // This implementation pops from the head of the list. This is unfair,
4576 // but tends to provide excellent throughput as hot threads remain hot.
4577 // (We wake recently run threads first).
4579 void Thread::muxRelease (volatile intptr_t * Lock) {
4580 for (;;) {
4581 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4582 assert (w & LOCKBIT, "invariant") ;
4583 if (w == LOCKBIT) return ;
4584 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4585 assert (List != NULL, "invariant") ;
4586 assert (List->OnList == intptr_t(Lock), "invariant") ;
4587 ParkEvent * nxt = List->ListNext ;
4589 // The following CAS() releases the lock and pops the head element.
4590 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4591 continue ;
4592 }
4593 List->OnList = 0 ;
4594 OrderAccess::fence() ;
4595 List->unpark () ;
4596 return ;
4597 }
4598 }
4601 void Threads::verify() {
4602 ALL_JAVA_THREADS(p) {
4603 p->verify();
4604 }
4605 VMThread* thread = VMThread::vm_thread();
4606 if (thread != NULL) thread->verify();
4607 }