Tue, 24 Jul 2012 10:51:00 -0700
7023639: JSR 292 method handle invocation needs a fast path for compiled code
6984705: JSR 292 method handle creation should not go through JNI
Summary: remove assembly code for JDK 7 chained method handles
Reviewed-by: jrose, twisti, kvn, mhaupt
Contributed-by: John Rose <john.r.rose@oracle.com>, Christian Thalinger <christian.thalinger@oracle.com>, Michael Haupt <michael.haupt@oracle.com>
1 /*
2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/scopeDesc.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "interpreter/interpreter.hpp"
33 #include "interpreter/linkResolver.hpp"
34 #include "interpreter/oopMapCache.hpp"
35 #include "jvmtifiles/jvmtiEnv.hpp"
36 #include "memory/gcLocker.inline.hpp"
37 #include "memory/oopFactory.hpp"
38 #include "memory/universe.inline.hpp"
39 #include "oops/instanceKlass.hpp"
40 #include "oops/objArrayOop.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "oops/symbol.hpp"
43 #include "prims/jvm_misc.hpp"
44 #include "prims/jvmtiExport.hpp"
45 #include "prims/jvmtiThreadState.hpp"
46 #include "prims/privilegedStack.hpp"
47 #include "runtime/aprofiler.hpp"
48 #include "runtime/arguments.hpp"
49 #include "runtime/biasedLocking.hpp"
50 #include "runtime/deoptimization.hpp"
51 #include "runtime/fprofiler.hpp"
52 #include "runtime/frame.inline.hpp"
53 #include "runtime/init.hpp"
54 #include "runtime/interfaceSupport.hpp"
55 #include "runtime/java.hpp"
56 #include "runtime/javaCalls.hpp"
57 #include "runtime/jniPeriodicChecker.hpp"
58 #include "runtime/memprofiler.hpp"
59 #include "runtime/mutexLocker.hpp"
60 #include "runtime/objectMonitor.hpp"
61 #include "runtime/osThread.hpp"
62 #include "runtime/safepoint.hpp"
63 #include "runtime/sharedRuntime.hpp"
64 #include "runtime/statSampler.hpp"
65 #include "runtime/stubRoutines.hpp"
66 #include "runtime/task.hpp"
67 #include "runtime/threadCritical.hpp"
68 #include "runtime/threadLocalStorage.hpp"
69 #include "runtime/vframe.hpp"
70 #include "runtime/vframeArray.hpp"
71 #include "runtime/vframe_hp.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "runtime/vm_operations.hpp"
74 #include "services/attachListener.hpp"
75 #include "services/management.hpp"
76 #include "services/memTracker.hpp"
77 #include "services/threadService.hpp"
78 #include "trace/traceEventTypes.hpp"
79 #include "utilities/defaultStream.hpp"
80 #include "utilities/dtrace.hpp"
81 #include "utilities/events.hpp"
82 #include "utilities/preserveException.hpp"
83 #ifdef TARGET_OS_FAMILY_linux
84 # include "os_linux.inline.hpp"
85 # include "thread_linux.inline.hpp"
86 #endif
87 #ifdef TARGET_OS_FAMILY_solaris
88 # include "os_solaris.inline.hpp"
89 # include "thread_solaris.inline.hpp"
90 #endif
91 #ifdef TARGET_OS_FAMILY_windows
92 # include "os_windows.inline.hpp"
93 # include "thread_windows.inline.hpp"
94 #endif
95 #ifdef TARGET_OS_FAMILY_bsd
96 # include "os_bsd.inline.hpp"
97 # include "thread_bsd.inline.hpp"
98 #endif
99 #ifndef SERIALGC
100 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
101 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
102 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
103 #endif
104 #ifdef COMPILER1
105 #include "c1/c1_Compiler.hpp"
106 #endif
107 #ifdef COMPILER2
108 #include "opto/c2compiler.hpp"
109 #include "opto/idealGraphPrinter.hpp"
110 #endif
112 #ifdef DTRACE_ENABLED
114 // Only bother with this argument setup if dtrace is available
116 #ifndef USDT2
117 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
118 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
119 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
120 intptr_t, intptr_t, bool);
121 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
122 intptr_t, intptr_t, bool);
124 #define DTRACE_THREAD_PROBE(probe, javathread) \
125 { \
126 ResourceMark rm(this); \
127 int len = 0; \
128 const char* name = (javathread)->get_thread_name(); \
129 len = strlen(name); \
130 HS_DTRACE_PROBE5(hotspot, thread__##probe, \
131 name, len, \
132 java_lang_Thread::thread_id((javathread)->threadObj()), \
133 (javathread)->osthread()->thread_id(), \
134 java_lang_Thread::is_daemon((javathread)->threadObj())); \
135 }
137 #else /* USDT2 */
139 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_PROBE_START
140 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_PROBE_STOP
142 #define DTRACE_THREAD_PROBE(probe, javathread) \
143 { \
144 ResourceMark rm(this); \
145 int len = 0; \
146 const char* name = (javathread)->get_thread_name(); \
147 len = strlen(name); \
148 HOTSPOT_THREAD_PROBE_##probe( /* probe = start, stop */ \
149 (char *) name, len, \
150 java_lang_Thread::thread_id((javathread)->threadObj()), \
151 (uintptr_t) (javathread)->osthread()->thread_id(), \
152 java_lang_Thread::is_daemon((javathread)->threadObj())); \
153 }
155 #endif /* USDT2 */
157 #else // ndef DTRACE_ENABLED
159 #define DTRACE_THREAD_PROBE(probe, javathread)
161 #endif // ndef DTRACE_ENABLED
164 // Class hierarchy
165 // - Thread
166 // - VMThread
167 // - WatcherThread
168 // - ConcurrentMarkSweepThread
169 // - JavaThread
170 // - CompilerThread
172 // ======= Thread ========
173 // Support for forcing alignment of thread objects for biased locking
174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
175 if (UseBiasedLocking) {
176 const int alignment = markOopDesc::biased_lock_alignment;
177 size_t aligned_size = size + (alignment - sizeof(intptr_t));
178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
179 : os::malloc(aligned_size, flags, CURRENT_PC);
180 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
181 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
182 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
183 "JavaThread alignment code overflowed allocated storage");
184 if (TraceBiasedLocking) {
185 if (aligned_addr != real_malloc_addr)
186 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
187 real_malloc_addr, aligned_addr);
188 }
189 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
190 return aligned_addr;
191 } else {
192 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
193 : os::malloc(size, flags, CURRENT_PC);
194 }
195 }
197 void Thread::operator delete(void* p) {
198 if (UseBiasedLocking) {
199 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
200 FreeHeap(real_malloc_addr, mtThread);
201 } else {
202 FreeHeap(p, mtThread);
203 }
204 }
207 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
208 // JavaThread
211 Thread::Thread() {
212 // stack and get_thread
213 set_stack_base(NULL);
214 set_stack_size(0);
215 set_self_raw_id(0);
216 set_lgrp_id(-1);
218 // allocated data structures
219 set_osthread(NULL);
220 set_resource_area(new (mtThread)ResourceArea());
221 set_handle_area(new (mtThread) HandleArea(NULL));
222 set_active_handles(NULL);
223 set_free_handle_block(NULL);
224 set_last_handle_mark(NULL);
226 // This initial value ==> never claimed.
227 _oops_do_parity = 0;
229 // the handle mark links itself to last_handle_mark
230 new HandleMark(this);
232 // plain initialization
233 debug_only(_owned_locks = NULL;)
234 debug_only(_allow_allocation_count = 0;)
235 NOT_PRODUCT(_allow_safepoint_count = 0;)
236 NOT_PRODUCT(_skip_gcalot = false;)
237 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
238 _jvmti_env_iteration_count = 0;
239 set_allocated_bytes(0);
240 set_trace_buffer(NULL);
241 _vm_operation_started_count = 0;
242 _vm_operation_completed_count = 0;
243 _current_pending_monitor = NULL;
244 _current_pending_monitor_is_from_java = true;
245 _current_waiting_monitor = NULL;
246 _num_nested_signal = 0;
247 omFreeList = NULL ;
248 omFreeCount = 0 ;
249 omFreeProvision = 32 ;
250 omInUseList = NULL ;
251 omInUseCount = 0 ;
253 #ifdef ASSERT
254 _visited_for_critical_count = false;
255 #endif
257 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
258 _suspend_flags = 0;
260 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
261 _hashStateX = os::random() ;
262 _hashStateY = 842502087 ;
263 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
264 _hashStateW = 273326509 ;
266 _OnTrap = 0 ;
267 _schedctl = NULL ;
268 _Stalled = 0 ;
269 _TypeTag = 0x2BAD ;
271 // Many of the following fields are effectively final - immutable
272 // Note that nascent threads can't use the Native Monitor-Mutex
273 // construct until the _MutexEvent is initialized ...
274 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
275 // we might instead use a stack of ParkEvents that we could provision on-demand.
276 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
277 // and ::Release()
278 _ParkEvent = ParkEvent::Allocate (this) ;
279 _SleepEvent = ParkEvent::Allocate (this) ;
280 _MutexEvent = ParkEvent::Allocate (this) ;
281 _MuxEvent = ParkEvent::Allocate (this) ;
283 #ifdef CHECK_UNHANDLED_OOPS
284 if (CheckUnhandledOops) {
285 _unhandled_oops = new UnhandledOops(this);
286 }
287 #endif // CHECK_UNHANDLED_OOPS
288 #ifdef ASSERT
289 if (UseBiasedLocking) {
290 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
291 assert(this == _real_malloc_address ||
292 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
293 "bug in forced alignment of thread objects");
294 }
295 #endif /* ASSERT */
296 }
298 void Thread::initialize_thread_local_storage() {
299 // Note: Make sure this method only calls
300 // non-blocking operations. Otherwise, it might not work
301 // with the thread-startup/safepoint interaction.
303 // During Java thread startup, safepoint code should allow this
304 // method to complete because it may need to allocate memory to
305 // store information for the new thread.
307 // initialize structure dependent on thread local storage
308 ThreadLocalStorage::set_thread(this);
310 // set up any platform-specific state.
311 os::initialize_thread();
312 }
314 void Thread::record_stack_base_and_size() {
315 set_stack_base(os::current_stack_base());
316 set_stack_size(os::current_stack_size());
318 // record thread's native stack, stack grows downward
319 address vm_base = _stack_base - _stack_size;
320 MemTracker::record_virtual_memory_reserve(vm_base, _stack_size,
321 CURRENT_PC, this);
322 MemTracker::record_virtual_memory_type(vm_base, mtThreadStack);
323 }
326 Thread::~Thread() {
327 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
328 ObjectSynchronizer::omFlush (this) ;
330 MemTracker::record_virtual_memory_release((_stack_base - _stack_size),
331 _stack_size, this);
333 // deallocate data structures
334 delete resource_area();
335 // since the handle marks are using the handle area, we have to deallocated the root
336 // handle mark before deallocating the thread's handle area,
337 assert(last_handle_mark() != NULL, "check we have an element");
338 delete last_handle_mark();
339 assert(last_handle_mark() == NULL, "check we have reached the end");
341 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
342 // We NULL out the fields for good hygiene.
343 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
344 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
345 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
346 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
348 delete handle_area();
350 // osthread() can be NULL, if creation of thread failed.
351 if (osthread() != NULL) os::free_thread(osthread());
353 delete _SR_lock;
355 // clear thread local storage if the Thread is deleting itself
356 if (this == Thread::current()) {
357 ThreadLocalStorage::set_thread(NULL);
358 } else {
359 // In the case where we're not the current thread, invalidate all the
360 // caches in case some code tries to get the current thread or the
361 // thread that was destroyed, and gets stale information.
362 ThreadLocalStorage::invalidate_all();
363 }
364 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
365 }
367 // NOTE: dummy function for assertion purpose.
368 void Thread::run() {
369 ShouldNotReachHere();
370 }
372 #ifdef ASSERT
373 // Private method to check for dangling thread pointer
374 void check_for_dangling_thread_pointer(Thread *thread) {
375 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
376 "possibility of dangling Thread pointer");
377 }
378 #endif
381 #ifndef PRODUCT
382 // Tracing method for basic thread operations
383 void Thread::trace(const char* msg, const Thread* const thread) {
384 if (!TraceThreadEvents) return;
385 ResourceMark rm;
386 ThreadCritical tc;
387 const char *name = "non-Java thread";
388 int prio = -1;
389 if (thread->is_Java_thread()
390 && !thread->is_Compiler_thread()) {
391 // The Threads_lock must be held to get information about
392 // this thread but may not be in some situations when
393 // tracing thread events.
394 bool release_Threads_lock = false;
395 if (!Threads_lock->owned_by_self()) {
396 Threads_lock->lock();
397 release_Threads_lock = true;
398 }
399 JavaThread* jt = (JavaThread *)thread;
400 name = (char *)jt->get_thread_name();
401 oop thread_oop = jt->threadObj();
402 if (thread_oop != NULL) {
403 prio = java_lang_Thread::priority(thread_oop);
404 }
405 if (release_Threads_lock) {
406 Threads_lock->unlock();
407 }
408 }
409 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
410 }
411 #endif
414 ThreadPriority Thread::get_priority(const Thread* const thread) {
415 trace("get priority", thread);
416 ThreadPriority priority;
417 // Can return an error!
418 (void)os::get_priority(thread, priority);
419 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
420 return priority;
421 }
423 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
424 trace("set priority", thread);
425 debug_only(check_for_dangling_thread_pointer(thread);)
426 // Can return an error!
427 (void)os::set_priority(thread, priority);
428 }
431 void Thread::start(Thread* thread) {
432 trace("start", thread);
433 // Start is different from resume in that its safety is guaranteed by context or
434 // being called from a Java method synchronized on the Thread object.
435 if (!DisableStartThread) {
436 if (thread->is_Java_thread()) {
437 // Initialize the thread state to RUNNABLE before starting this thread.
438 // Can not set it after the thread started because we do not know the
439 // exact thread state at that time. It could be in MONITOR_WAIT or
440 // in SLEEPING or some other state.
441 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
442 java_lang_Thread::RUNNABLE);
443 }
444 os::start_thread(thread);
445 }
446 }
448 // Enqueue a VM_Operation to do the job for us - sometime later
449 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
450 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
451 VMThread::execute(vm_stop);
452 }
455 //
456 // Check if an external suspend request has completed (or has been
457 // cancelled). Returns true if the thread is externally suspended and
458 // false otherwise.
459 //
460 // The bits parameter returns information about the code path through
461 // the routine. Useful for debugging:
462 //
463 // set in is_ext_suspend_completed():
464 // 0x00000001 - routine was entered
465 // 0x00000010 - routine return false at end
466 // 0x00000100 - thread exited (return false)
467 // 0x00000200 - suspend request cancelled (return false)
468 // 0x00000400 - thread suspended (return true)
469 // 0x00001000 - thread is in a suspend equivalent state (return true)
470 // 0x00002000 - thread is native and walkable (return true)
471 // 0x00004000 - thread is native_trans and walkable (needed retry)
472 //
473 // set in wait_for_ext_suspend_completion():
474 // 0x00010000 - routine was entered
475 // 0x00020000 - suspend request cancelled before loop (return false)
476 // 0x00040000 - thread suspended before loop (return true)
477 // 0x00080000 - suspend request cancelled in loop (return false)
478 // 0x00100000 - thread suspended in loop (return true)
479 // 0x00200000 - suspend not completed during retry loop (return false)
480 //
482 // Helper class for tracing suspend wait debug bits.
483 //
484 // 0x00000100 indicates that the target thread exited before it could
485 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
486 // 0x00080000 each indicate a cancelled suspend request so they don't
487 // count as wait failures either.
488 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
490 class TraceSuspendDebugBits : public StackObj {
491 private:
492 JavaThread * jt;
493 bool is_wait;
494 bool called_by_wait; // meaningful when !is_wait
495 uint32_t * bits;
497 public:
498 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
499 uint32_t *_bits) {
500 jt = _jt;
501 is_wait = _is_wait;
502 called_by_wait = _called_by_wait;
503 bits = _bits;
504 }
506 ~TraceSuspendDebugBits() {
507 if (!is_wait) {
508 #if 1
509 // By default, don't trace bits for is_ext_suspend_completed() calls.
510 // That trace is very chatty.
511 return;
512 #else
513 if (!called_by_wait) {
514 // If tracing for is_ext_suspend_completed() is enabled, then only
515 // trace calls to it from wait_for_ext_suspend_completion()
516 return;
517 }
518 #endif
519 }
521 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
522 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
523 MutexLocker ml(Threads_lock); // needed for get_thread_name()
524 ResourceMark rm;
526 tty->print_cr(
527 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
528 jt->get_thread_name(), *bits);
530 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
531 }
532 }
533 }
534 };
535 #undef DEBUG_FALSE_BITS
538 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
539 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
541 bool did_trans_retry = false; // only do thread_in_native_trans retry once
542 bool do_trans_retry; // flag to force the retry
544 *bits |= 0x00000001;
546 do {
547 do_trans_retry = false;
549 if (is_exiting()) {
550 // Thread is in the process of exiting. This is always checked
551 // first to reduce the risk of dereferencing a freed JavaThread.
552 *bits |= 0x00000100;
553 return false;
554 }
556 if (!is_external_suspend()) {
557 // Suspend request is cancelled. This is always checked before
558 // is_ext_suspended() to reduce the risk of a rogue resume
559 // confusing the thread that made the suspend request.
560 *bits |= 0x00000200;
561 return false;
562 }
564 if (is_ext_suspended()) {
565 // thread is suspended
566 *bits |= 0x00000400;
567 return true;
568 }
570 // Now that we no longer do hard suspends of threads running
571 // native code, the target thread can be changing thread state
572 // while we are in this routine:
573 //
574 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
575 //
576 // We save a copy of the thread state as observed at this moment
577 // and make our decision about suspend completeness based on the
578 // copy. This closes the race where the thread state is seen as
579 // _thread_in_native_trans in the if-thread_blocked check, but is
580 // seen as _thread_blocked in if-thread_in_native_trans check.
581 JavaThreadState save_state = thread_state();
583 if (save_state == _thread_blocked && is_suspend_equivalent()) {
584 // If the thread's state is _thread_blocked and this blocking
585 // condition is known to be equivalent to a suspend, then we can
586 // consider the thread to be externally suspended. This means that
587 // the code that sets _thread_blocked has been modified to do
588 // self-suspension if the blocking condition releases. We also
589 // used to check for CONDVAR_WAIT here, but that is now covered by
590 // the _thread_blocked with self-suspension check.
591 //
592 // Return true since we wouldn't be here unless there was still an
593 // external suspend request.
594 *bits |= 0x00001000;
595 return true;
596 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
597 // Threads running native code will self-suspend on native==>VM/Java
598 // transitions. If its stack is walkable (should always be the case
599 // unless this function is called before the actual java_suspend()
600 // call), then the wait is done.
601 *bits |= 0x00002000;
602 return true;
603 } else if (!called_by_wait && !did_trans_retry &&
604 save_state == _thread_in_native_trans &&
605 frame_anchor()->walkable()) {
606 // The thread is transitioning from thread_in_native to another
607 // thread state. check_safepoint_and_suspend_for_native_trans()
608 // will force the thread to self-suspend. If it hasn't gotten
609 // there yet we may have caught the thread in-between the native
610 // code check above and the self-suspend. Lucky us. If we were
611 // called by wait_for_ext_suspend_completion(), then it
612 // will be doing the retries so we don't have to.
613 //
614 // Since we use the saved thread state in the if-statement above,
615 // there is a chance that the thread has already transitioned to
616 // _thread_blocked by the time we get here. In that case, we will
617 // make a single unnecessary pass through the logic below. This
618 // doesn't hurt anything since we still do the trans retry.
620 *bits |= 0x00004000;
622 // Once the thread leaves thread_in_native_trans for another
623 // thread state, we break out of this retry loop. We shouldn't
624 // need this flag to prevent us from getting back here, but
625 // sometimes paranoia is good.
626 did_trans_retry = true;
628 // We wait for the thread to transition to a more usable state.
629 for (int i = 1; i <= SuspendRetryCount; i++) {
630 // We used to do an "os::yield_all(i)" call here with the intention
631 // that yielding would increase on each retry. However, the parameter
632 // is ignored on Linux which means the yield didn't scale up. Waiting
633 // on the SR_lock below provides a much more predictable scale up for
634 // the delay. It also provides a simple/direct point to check for any
635 // safepoint requests from the VMThread
637 // temporarily drops SR_lock while doing wait with safepoint check
638 // (if we're a JavaThread - the WatcherThread can also call this)
639 // and increase delay with each retry
640 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
642 // check the actual thread state instead of what we saved above
643 if (thread_state() != _thread_in_native_trans) {
644 // the thread has transitioned to another thread state so
645 // try all the checks (except this one) one more time.
646 do_trans_retry = true;
647 break;
648 }
649 } // end retry loop
652 }
653 } while (do_trans_retry);
655 *bits |= 0x00000010;
656 return false;
657 }
659 //
660 // Wait for an external suspend request to complete (or be cancelled).
661 // Returns true if the thread is externally suspended and false otherwise.
662 //
663 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
664 uint32_t *bits) {
665 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
666 false /* !called_by_wait */, bits);
668 // local flag copies to minimize SR_lock hold time
669 bool is_suspended;
670 bool pending;
671 uint32_t reset_bits;
673 // set a marker so is_ext_suspend_completed() knows we are the caller
674 *bits |= 0x00010000;
676 // We use reset_bits to reinitialize the bits value at the top of
677 // each retry loop. This allows the caller to make use of any
678 // unused bits for their own marking purposes.
679 reset_bits = *bits;
681 {
682 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
683 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
684 delay, bits);
685 pending = is_external_suspend();
686 }
687 // must release SR_lock to allow suspension to complete
689 if (!pending) {
690 // A cancelled suspend request is the only false return from
691 // is_ext_suspend_completed() that keeps us from entering the
692 // retry loop.
693 *bits |= 0x00020000;
694 return false;
695 }
697 if (is_suspended) {
698 *bits |= 0x00040000;
699 return true;
700 }
702 for (int i = 1; i <= retries; i++) {
703 *bits = reset_bits; // reinit to only track last retry
705 // We used to do an "os::yield_all(i)" call here with the intention
706 // that yielding would increase on each retry. However, the parameter
707 // is ignored on Linux which means the yield didn't scale up. Waiting
708 // on the SR_lock below provides a much more predictable scale up for
709 // the delay. It also provides a simple/direct point to check for any
710 // safepoint requests from the VMThread
712 {
713 MutexLocker ml(SR_lock());
714 // wait with safepoint check (if we're a JavaThread - the WatcherThread
715 // can also call this) and increase delay with each retry
716 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
718 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
719 delay, bits);
721 // It is possible for the external suspend request to be cancelled
722 // (by a resume) before the actual suspend operation is completed.
723 // Refresh our local copy to see if we still need to wait.
724 pending = is_external_suspend();
725 }
727 if (!pending) {
728 // A cancelled suspend request is the only false return from
729 // is_ext_suspend_completed() that keeps us from staying in the
730 // retry loop.
731 *bits |= 0x00080000;
732 return false;
733 }
735 if (is_suspended) {
736 *bits |= 0x00100000;
737 return true;
738 }
739 } // end retry loop
741 // thread did not suspend after all our retries
742 *bits |= 0x00200000;
743 return false;
744 }
746 #ifndef PRODUCT
747 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
749 // This should not need to be atomic as the only way for simultaneous
750 // updates is via interrupts. Even then this should be rare or non-existant
751 // and we don't care that much anyway.
753 int index = _jmp_ring_index;
754 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
755 _jmp_ring[index]._target = (intptr_t) target;
756 _jmp_ring[index]._instruction = (intptr_t) instr;
757 _jmp_ring[index]._file = file;
758 _jmp_ring[index]._line = line;
759 }
760 #endif /* PRODUCT */
762 // Called by flat profiler
763 // Callers have already called wait_for_ext_suspend_completion
764 // The assertion for that is currently too complex to put here:
765 bool JavaThread::profile_last_Java_frame(frame* _fr) {
766 bool gotframe = false;
767 // self suspension saves needed state.
768 if (has_last_Java_frame() && _anchor.walkable()) {
769 *_fr = pd_last_frame();
770 gotframe = true;
771 }
772 return gotframe;
773 }
775 void Thread::interrupt(Thread* thread) {
776 trace("interrupt", thread);
777 debug_only(check_for_dangling_thread_pointer(thread);)
778 os::interrupt(thread);
779 }
781 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
782 trace("is_interrupted", thread);
783 debug_only(check_for_dangling_thread_pointer(thread);)
784 // Note: If clear_interrupted==false, this simply fetches and
785 // returns the value of the field osthread()->interrupted().
786 return os::is_interrupted(thread, clear_interrupted);
787 }
790 // GC Support
791 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
792 jint thread_parity = _oops_do_parity;
793 if (thread_parity != strong_roots_parity) {
794 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
795 if (res == thread_parity) {
796 return true;
797 } else {
798 guarantee(res == strong_roots_parity, "Or else what?");
799 assert(SharedHeap::heap()->workers()->active_workers() > 0,
800 "Should only fail when parallel.");
801 return false;
802 }
803 }
804 assert(SharedHeap::heap()->workers()->active_workers() > 0,
805 "Should only fail when parallel.");
806 return false;
807 }
809 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
810 active_handles()->oops_do(f);
811 // Do oop for ThreadShadow
812 f->do_oop((oop*)&_pending_exception);
813 handle_area()->oops_do(f);
814 }
816 void Thread::nmethods_do(CodeBlobClosure* cf) {
817 // no nmethods in a generic thread...
818 }
820 void Thread::print_on(outputStream* st) const {
821 // get_priority assumes osthread initialized
822 if (osthread() != NULL) {
823 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
824 osthread()->print_on(st);
825 }
826 debug_only(if (WizardMode) print_owned_locks_on(st);)
827 }
829 // Thread::print_on_error() is called by fatal error handler. Don't use
830 // any lock or allocate memory.
831 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
832 if (is_VM_thread()) st->print("VMThread");
833 else if (is_Compiler_thread()) st->print("CompilerThread");
834 else if (is_Java_thread()) st->print("JavaThread");
835 else if (is_GC_task_thread()) st->print("GCTaskThread");
836 else if (is_Watcher_thread()) st->print("WatcherThread");
837 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
838 else st->print("Thread");
840 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
841 _stack_base - _stack_size, _stack_base);
843 if (osthread()) {
844 st->print(" [id=%d]", osthread()->thread_id());
845 }
846 }
848 #ifdef ASSERT
849 void Thread::print_owned_locks_on(outputStream* st) const {
850 Monitor *cur = _owned_locks;
851 if (cur == NULL) {
852 st->print(" (no locks) ");
853 } else {
854 st->print_cr(" Locks owned:");
855 while(cur) {
856 cur->print_on(st);
857 cur = cur->next();
858 }
859 }
860 }
862 static int ref_use_count = 0;
864 bool Thread::owns_locks_but_compiled_lock() const {
865 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
866 if (cur != Compile_lock) return true;
867 }
868 return false;
869 }
872 #endif
874 #ifndef PRODUCT
876 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
877 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
878 // no threads which allow_vm_block's are held
879 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
880 // Check if current thread is allowed to block at a safepoint
881 if (!(_allow_safepoint_count == 0))
882 fatal("Possible safepoint reached by thread that does not allow it");
883 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
884 fatal("LEAF method calling lock?");
885 }
887 #ifdef ASSERT
888 if (potential_vm_operation && is_Java_thread()
889 && !Universe::is_bootstrapping()) {
890 // Make sure we do not hold any locks that the VM thread also uses.
891 // This could potentially lead to deadlocks
892 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
893 // Threads_lock is special, since the safepoint synchronization will not start before this is
894 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
895 // since it is used to transfer control between JavaThreads and the VMThread
896 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
897 if ( (cur->allow_vm_block() &&
898 cur != Threads_lock &&
899 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
900 cur != VMOperationRequest_lock &&
901 cur != VMOperationQueue_lock) ||
902 cur->rank() == Mutex::special) {
903 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
904 }
905 }
906 }
908 if (GCALotAtAllSafepoints) {
909 // We could enter a safepoint here and thus have a gc
910 InterfaceSupport::check_gc_alot();
911 }
912 #endif
913 }
914 #endif
916 bool Thread::is_in_stack(address adr) const {
917 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
918 address end = os::current_stack_pointer();
919 if (stack_base() >= adr && adr >= end) return true;
921 return false;
922 }
925 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
926 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
927 // used for compilation in the future. If that change is made, the need for these methods
928 // should be revisited, and they should be removed if possible.
930 bool Thread::is_lock_owned(address adr) const {
931 return on_local_stack(adr);
932 }
934 bool Thread::set_as_starting_thread() {
935 // NOTE: this must be called inside the main thread.
936 return os::create_main_thread((JavaThread*)this);
937 }
939 static void initialize_class(Symbol* class_name, TRAPS) {
940 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
941 instanceKlass::cast(klass)->initialize(CHECK);
942 }
945 // Creates the initial ThreadGroup
946 static Handle create_initial_thread_group(TRAPS) {
947 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
948 instanceKlassHandle klass (THREAD, k);
950 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
951 {
952 JavaValue result(T_VOID);
953 JavaCalls::call_special(&result,
954 system_instance,
955 klass,
956 vmSymbols::object_initializer_name(),
957 vmSymbols::void_method_signature(),
958 CHECK_NH);
959 }
960 Universe::set_system_thread_group(system_instance());
962 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
963 {
964 JavaValue result(T_VOID);
965 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
966 JavaCalls::call_special(&result,
967 main_instance,
968 klass,
969 vmSymbols::object_initializer_name(),
970 vmSymbols::threadgroup_string_void_signature(),
971 system_instance,
972 string,
973 CHECK_NH);
974 }
975 return main_instance;
976 }
978 // Creates the initial Thread
979 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
980 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
981 instanceKlassHandle klass (THREAD, k);
982 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
984 java_lang_Thread::set_thread(thread_oop(), thread);
985 java_lang_Thread::set_priority(thread_oop(), NormPriority);
986 thread->set_threadObj(thread_oop());
988 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
990 JavaValue result(T_VOID);
991 JavaCalls::call_special(&result, thread_oop,
992 klass,
993 vmSymbols::object_initializer_name(),
994 vmSymbols::threadgroup_string_void_signature(),
995 thread_group,
996 string,
997 CHECK_NULL);
998 return thread_oop();
999 }
1001 static void call_initializeSystemClass(TRAPS) {
1002 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1003 instanceKlassHandle klass (THREAD, k);
1005 JavaValue result(T_VOID);
1006 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
1007 vmSymbols::void_method_signature(), CHECK);
1008 }
1010 char java_runtime_name[128] = "";
1012 // extract the JRE name from sun.misc.Version.java_runtime_name
1013 static const char* get_java_runtime_name(TRAPS) {
1014 klassOop k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1015 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1016 fieldDescriptor fd;
1017 bool found = k != NULL &&
1018 instanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1019 vmSymbols::string_signature(), &fd);
1020 if (found) {
1021 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1022 if (name_oop == NULL)
1023 return NULL;
1024 const char* name = java_lang_String::as_utf8_string(name_oop,
1025 java_runtime_name,
1026 sizeof(java_runtime_name));
1027 return name;
1028 } else {
1029 return NULL;
1030 }
1031 }
1033 // General purpose hook into Java code, run once when the VM is initialized.
1034 // The Java library method itself may be changed independently from the VM.
1035 static void call_postVMInitHook(TRAPS) {
1036 klassOop k = SystemDictionary::PostVMInitHook_klass();
1037 instanceKlassHandle klass (THREAD, k);
1038 if (klass.not_null()) {
1039 JavaValue result(T_VOID);
1040 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1041 vmSymbols::void_method_signature(),
1042 CHECK);
1043 }
1044 }
1046 static void reset_vm_info_property(TRAPS) {
1047 // the vm info string
1048 ResourceMark rm(THREAD);
1049 const char *vm_info = VM_Version::vm_info_string();
1051 // java.lang.System class
1052 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1053 instanceKlassHandle klass (THREAD, k);
1055 // setProperty arguments
1056 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1057 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1059 // return value
1060 JavaValue r(T_OBJECT);
1062 // public static String setProperty(String key, String value);
1063 JavaCalls::call_static(&r,
1064 klass,
1065 vmSymbols::setProperty_name(),
1066 vmSymbols::string_string_string_signature(),
1067 key_str,
1068 value_str,
1069 CHECK);
1070 }
1073 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1074 assert(thread_group.not_null(), "thread group should be specified");
1075 assert(threadObj() == NULL, "should only create Java thread object once");
1077 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1078 instanceKlassHandle klass (THREAD, k);
1079 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1081 java_lang_Thread::set_thread(thread_oop(), this);
1082 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1083 set_threadObj(thread_oop());
1085 JavaValue result(T_VOID);
1086 if (thread_name != NULL) {
1087 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1088 // Thread gets assigned specified name and null target
1089 JavaCalls::call_special(&result,
1090 thread_oop,
1091 klass,
1092 vmSymbols::object_initializer_name(),
1093 vmSymbols::threadgroup_string_void_signature(),
1094 thread_group, // Argument 1
1095 name, // Argument 2
1096 THREAD);
1097 } else {
1098 // Thread gets assigned name "Thread-nnn" and null target
1099 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1100 JavaCalls::call_special(&result,
1101 thread_oop,
1102 klass,
1103 vmSymbols::object_initializer_name(),
1104 vmSymbols::threadgroup_runnable_void_signature(),
1105 thread_group, // Argument 1
1106 Handle(), // Argument 2
1107 THREAD);
1108 }
1111 if (daemon) {
1112 java_lang_Thread::set_daemon(thread_oop());
1113 }
1115 if (HAS_PENDING_EXCEPTION) {
1116 return;
1117 }
1119 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1120 Handle threadObj(this, this->threadObj());
1122 JavaCalls::call_special(&result,
1123 thread_group,
1124 group,
1125 vmSymbols::add_method_name(),
1126 vmSymbols::thread_void_signature(),
1127 threadObj, // Arg 1
1128 THREAD);
1131 }
1133 // NamedThread -- non-JavaThread subclasses with multiple
1134 // uniquely named instances should derive from this.
1135 NamedThread::NamedThread() : Thread() {
1136 _name = NULL;
1137 _processed_thread = NULL;
1138 }
1140 NamedThread::~NamedThread() {
1141 if (_name != NULL) {
1142 FREE_C_HEAP_ARRAY(char, _name, mtThread);
1143 _name = NULL;
1144 }
1145 }
1147 void NamedThread::set_name(const char* format, ...) {
1148 guarantee(_name == NULL, "Only get to set name once.");
1149 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1150 guarantee(_name != NULL, "alloc failure");
1151 va_list ap;
1152 va_start(ap, format);
1153 jio_vsnprintf(_name, max_name_len, format, ap);
1154 va_end(ap);
1155 }
1157 // ======= WatcherThread ========
1159 // The watcher thread exists to simulate timer interrupts. It should
1160 // be replaced by an abstraction over whatever native support for
1161 // timer interrupts exists on the platform.
1163 WatcherThread* WatcherThread::_watcher_thread = NULL;
1164 volatile bool WatcherThread::_should_terminate = false;
1166 WatcherThread::WatcherThread() : Thread() {
1167 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1168 if (os::create_thread(this, os::watcher_thread)) {
1169 _watcher_thread = this;
1171 // Set the watcher thread to the highest OS priority which should not be
1172 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1173 // is created. The only normal thread using this priority is the reference
1174 // handler thread, which runs for very short intervals only.
1175 // If the VMThread's priority is not lower than the WatcherThread profiling
1176 // will be inaccurate.
1177 os::set_priority(this, MaxPriority);
1178 if (!DisableStartThread) {
1179 os::start_thread(this);
1180 }
1181 }
1182 }
1184 void WatcherThread::run() {
1185 assert(this == watcher_thread(), "just checking");
1187 this->record_stack_base_and_size();
1188 this->initialize_thread_local_storage();
1189 this->set_active_handles(JNIHandleBlock::allocate_block());
1190 while(!_should_terminate) {
1191 assert(watcher_thread() == Thread::current(), "thread consistency check");
1192 assert(watcher_thread() == this, "thread consistency check");
1194 // Calculate how long it'll be until the next PeriodicTask work
1195 // should be done, and sleep that amount of time.
1196 size_t time_to_wait = PeriodicTask::time_to_wait();
1198 // we expect this to timeout - we only ever get unparked when
1199 // we should terminate
1200 {
1201 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1203 jlong prev_time = os::javaTimeNanos();
1204 for (;;) {
1205 int res= _SleepEvent->park(time_to_wait);
1206 if (res == OS_TIMEOUT || _should_terminate)
1207 break;
1208 // spurious wakeup of some kind
1209 jlong now = os::javaTimeNanos();
1210 time_to_wait -= (now - prev_time) / 1000000;
1211 if (time_to_wait <= 0)
1212 break;
1213 prev_time = now;
1214 }
1215 }
1217 if (is_error_reported()) {
1218 // A fatal error has happened, the error handler(VMError::report_and_die)
1219 // should abort JVM after creating an error log file. However in some
1220 // rare cases, the error handler itself might deadlock. Here we try to
1221 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1222 //
1223 // This code is in WatcherThread because WatcherThread wakes up
1224 // periodically so the fatal error handler doesn't need to do anything;
1225 // also because the WatcherThread is less likely to crash than other
1226 // threads.
1228 for (;;) {
1229 if (!ShowMessageBoxOnError
1230 && (OnError == NULL || OnError[0] == '\0')
1231 && Arguments::abort_hook() == NULL) {
1232 os::sleep(this, 2 * 60 * 1000, false);
1233 fdStream err(defaultStream::output_fd());
1234 err.print_raw_cr("# [ timer expired, abort... ]");
1235 // skip atexit/vm_exit/vm_abort hooks
1236 os::die();
1237 }
1239 // Wake up 5 seconds later, the fatal handler may reset OnError or
1240 // ShowMessageBoxOnError when it is ready to abort.
1241 os::sleep(this, 5 * 1000, false);
1242 }
1243 }
1245 PeriodicTask::real_time_tick(time_to_wait);
1247 // If we have no more tasks left due to dynamic disenrollment,
1248 // shut down the thread since we don't currently support dynamic enrollment
1249 if (PeriodicTask::num_tasks() == 0) {
1250 _should_terminate = true;
1251 }
1252 }
1254 // Signal that it is terminated
1255 {
1256 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1257 _watcher_thread = NULL;
1258 Terminator_lock->notify();
1259 }
1261 // Thread destructor usually does this..
1262 ThreadLocalStorage::set_thread(NULL);
1263 }
1265 void WatcherThread::start() {
1266 if (watcher_thread() == NULL) {
1267 _should_terminate = false;
1268 // Create the single instance of WatcherThread
1269 new WatcherThread();
1270 }
1271 }
1273 void WatcherThread::stop() {
1274 // it is ok to take late safepoints here, if needed
1275 MutexLocker mu(Terminator_lock);
1276 _should_terminate = true;
1277 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1279 Thread* watcher = watcher_thread();
1280 if (watcher != NULL)
1281 watcher->_SleepEvent->unpark();
1283 while(watcher_thread() != NULL) {
1284 // This wait should make safepoint checks, wait without a timeout,
1285 // and wait as a suspend-equivalent condition.
1286 //
1287 // Note: If the FlatProfiler is running, then this thread is waiting
1288 // for the WatcherThread to terminate and the WatcherThread, via the
1289 // FlatProfiler task, is waiting for the external suspend request on
1290 // this thread to complete. wait_for_ext_suspend_completion() will
1291 // eventually timeout, but that takes time. Making this wait a
1292 // suspend-equivalent condition solves that timeout problem.
1293 //
1294 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1295 Mutex::_as_suspend_equivalent_flag);
1296 }
1297 }
1299 void WatcherThread::print_on(outputStream* st) const {
1300 st->print("\"%s\" ", name());
1301 Thread::print_on(st);
1302 st->cr();
1303 }
1305 // ======= JavaThread ========
1307 // A JavaThread is a normal Java thread
1309 void JavaThread::initialize() {
1310 // Initialize fields
1312 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1313 set_claimed_par_id(-1);
1315 set_saved_exception_pc(NULL);
1316 set_threadObj(NULL);
1317 _anchor.clear();
1318 set_entry_point(NULL);
1319 set_jni_functions(jni_functions());
1320 set_callee_target(NULL);
1321 set_vm_result(NULL);
1322 set_vm_result_2(NULL);
1323 set_vframe_array_head(NULL);
1324 set_vframe_array_last(NULL);
1325 set_deferred_locals(NULL);
1326 set_deopt_mark(NULL);
1327 set_deopt_nmethod(NULL);
1328 clear_must_deopt_id();
1329 set_monitor_chunks(NULL);
1330 set_next(NULL);
1331 set_thread_state(_thread_new);
1332 set_recorder(NULL);
1333 _terminated = _not_terminated;
1334 _privileged_stack_top = NULL;
1335 _array_for_gc = NULL;
1336 _suspend_equivalent = false;
1337 _in_deopt_handler = 0;
1338 _doing_unsafe_access = false;
1339 _stack_guard_state = stack_guard_unused;
1340 _exception_oop = NULL;
1341 _exception_pc = 0;
1342 _exception_handler_pc = 0;
1343 _is_method_handle_return = 0;
1344 _jvmti_thread_state= NULL;
1345 _should_post_on_exceptions_flag = JNI_FALSE;
1346 _jvmti_get_loaded_classes_closure = NULL;
1347 _interp_only_mode = 0;
1348 _special_runtime_exit_condition = _no_async_condition;
1349 _pending_async_exception = NULL;
1350 _is_compiling = false;
1351 _thread_stat = NULL;
1352 _thread_stat = new ThreadStatistics();
1353 _blocked_on_compilation = false;
1354 _jni_active_critical = 0;
1355 _do_not_unlock_if_synchronized = false;
1356 _cached_monitor_info = NULL;
1357 _parker = Parker::Allocate(this) ;
1359 #ifndef PRODUCT
1360 _jmp_ring_index = 0;
1361 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1362 record_jump(NULL, NULL, NULL, 0);
1363 }
1364 #endif /* PRODUCT */
1366 set_thread_profiler(NULL);
1367 if (FlatProfiler::is_active()) {
1368 // This is where we would decide to either give each thread it's own profiler
1369 // or use one global one from FlatProfiler,
1370 // or up to some count of the number of profiled threads, etc.
1371 ThreadProfiler* pp = new ThreadProfiler();
1372 pp->engage();
1373 set_thread_profiler(pp);
1374 }
1376 // Setup safepoint state info for this thread
1377 ThreadSafepointState::create(this);
1379 debug_only(_java_call_counter = 0);
1381 // JVMTI PopFrame support
1382 _popframe_condition = popframe_inactive;
1383 _popframe_preserved_args = NULL;
1384 _popframe_preserved_args_size = 0;
1386 pd_initialize();
1387 }
1389 #ifndef SERIALGC
1390 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1391 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1392 #endif // !SERIALGC
1394 JavaThread::JavaThread(bool is_attaching_via_jni) :
1395 Thread()
1396 #ifndef SERIALGC
1397 , _satb_mark_queue(&_satb_mark_queue_set),
1398 _dirty_card_queue(&_dirty_card_queue_set)
1399 #endif // !SERIALGC
1400 {
1401 initialize();
1402 if (is_attaching_via_jni) {
1403 _jni_attach_state = _attaching_via_jni;
1404 } else {
1405 _jni_attach_state = _not_attaching_via_jni;
1406 }
1407 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1408 _safepoint_visible = false;
1409 }
1411 bool JavaThread::reguard_stack(address cur_sp) {
1412 if (_stack_guard_state != stack_guard_yellow_disabled) {
1413 return true; // Stack already guarded or guard pages not needed.
1414 }
1416 if (register_stack_overflow()) {
1417 // For those architectures which have separate register and
1418 // memory stacks, we must check the register stack to see if
1419 // it has overflowed.
1420 return false;
1421 }
1423 // Java code never executes within the yellow zone: the latter is only
1424 // there to provoke an exception during stack banging. If java code
1425 // is executing there, either StackShadowPages should be larger, or
1426 // some exception code in c1, c2 or the interpreter isn't unwinding
1427 // when it should.
1428 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1430 enable_stack_yellow_zone();
1431 return true;
1432 }
1434 bool JavaThread::reguard_stack(void) {
1435 return reguard_stack(os::current_stack_pointer());
1436 }
1439 void JavaThread::block_if_vm_exited() {
1440 if (_terminated == _vm_exited) {
1441 // _vm_exited is set at safepoint, and Threads_lock is never released
1442 // we will block here forever
1443 Threads_lock->lock_without_safepoint_check();
1444 ShouldNotReachHere();
1445 }
1446 }
1449 // Remove this ifdef when C1 is ported to the compiler interface.
1450 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1452 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1453 Thread()
1454 #ifndef SERIALGC
1455 , _satb_mark_queue(&_satb_mark_queue_set),
1456 _dirty_card_queue(&_dirty_card_queue_set)
1457 #endif // !SERIALGC
1458 {
1459 if (TraceThreadEvents) {
1460 tty->print_cr("creating thread %p", this);
1461 }
1462 initialize();
1463 _jni_attach_state = _not_attaching_via_jni;
1464 set_entry_point(entry_point);
1465 // Create the native thread itself.
1466 // %note runtime_23
1467 os::ThreadType thr_type = os::java_thread;
1468 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1469 os::java_thread;
1470 os::create_thread(this, thr_type, stack_sz);
1471 _safepoint_visible = false;
1472 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1473 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1474 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1475 // the exception consists of creating the exception object & initializing it, initialization
1476 // will leave the VM via a JavaCall and then all locks must be unlocked).
1477 //
1478 // The thread is still suspended when we reach here. Thread must be explicit started
1479 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1480 // by calling Threads:add. The reason why this is not done here, is because the thread
1481 // object must be fully initialized (take a look at JVM_Start)
1482 }
1484 JavaThread::~JavaThread() {
1485 if (TraceThreadEvents) {
1486 tty->print_cr("terminate thread %p", this);
1487 }
1489 // Info NMT that this JavaThread is exiting, its memory
1490 // recorder should be collected
1491 assert(!is_safepoint_visible(), "wrong state");
1492 MemTracker::thread_exiting(this);
1494 // JSR166 -- return the parker to the free list
1495 Parker::Release(_parker);
1496 _parker = NULL ;
1498 // Free any remaining previous UnrollBlock
1499 vframeArray* old_array = vframe_array_last();
1501 if (old_array != NULL) {
1502 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1503 old_array->set_unroll_block(NULL);
1504 delete old_info;
1505 delete old_array;
1506 }
1508 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1509 if (deferred != NULL) {
1510 // This can only happen if thread is destroyed before deoptimization occurs.
1511 assert(deferred->length() != 0, "empty array!");
1512 do {
1513 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1514 deferred->remove_at(0);
1515 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1516 delete dlv;
1517 } while (deferred->length() != 0);
1518 delete deferred;
1519 }
1521 // All Java related clean up happens in exit
1522 ThreadSafepointState::destroy(this);
1523 if (_thread_profiler != NULL) delete _thread_profiler;
1524 if (_thread_stat != NULL) delete _thread_stat;
1525 }
1528 // The first routine called by a new Java thread
1529 void JavaThread::run() {
1530 // initialize thread-local alloc buffer related fields
1531 this->initialize_tlab();
1533 // used to test validitity of stack trace backs
1534 this->record_base_of_stack_pointer();
1536 // Record real stack base and size.
1537 this->record_stack_base_and_size();
1539 // Initialize thread local storage; set before calling MutexLocker
1540 this->initialize_thread_local_storage();
1542 this->create_stack_guard_pages();
1544 this->cache_global_variables();
1546 // Thread is now sufficient initialized to be handled by the safepoint code as being
1547 // in the VM. Change thread state from _thread_new to _thread_in_vm
1548 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1550 assert(JavaThread::current() == this, "sanity check");
1551 assert(!Thread::current()->owns_locks(), "sanity check");
1553 DTRACE_THREAD_PROBE(start, this);
1555 // This operation might block. We call that after all safepoint checks for a new thread has
1556 // been completed.
1557 this->set_active_handles(JNIHandleBlock::allocate_block());
1559 if (JvmtiExport::should_post_thread_life()) {
1560 JvmtiExport::post_thread_start(this);
1561 }
1563 EVENT_BEGIN(TraceEventThreadStart, event);
1564 EVENT_COMMIT(event,
1565 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1567 // We call another function to do the rest so we are sure that the stack addresses used
1568 // from there will be lower than the stack base just computed
1569 thread_main_inner();
1571 // Note, thread is no longer valid at this point!
1572 }
1575 void JavaThread::thread_main_inner() {
1576 assert(JavaThread::current() == this, "sanity check");
1577 assert(this->threadObj() != NULL, "just checking");
1579 // Execute thread entry point unless this thread has a pending exception
1580 // or has been stopped before starting.
1581 // Note: Due to JVM_StopThread we can have pending exceptions already!
1582 if (!this->has_pending_exception() &&
1583 !java_lang_Thread::is_stillborn(this->threadObj())) {
1584 {
1585 ResourceMark rm(this);
1586 this->set_native_thread_name(this->get_thread_name());
1587 }
1588 HandleMark hm(this);
1589 this->entry_point()(this, this);
1590 }
1592 DTRACE_THREAD_PROBE(stop, this);
1594 this->exit(false);
1595 delete this;
1596 }
1599 static void ensure_join(JavaThread* thread) {
1600 // We do not need to grap the Threads_lock, since we are operating on ourself.
1601 Handle threadObj(thread, thread->threadObj());
1602 assert(threadObj.not_null(), "java thread object must exist");
1603 ObjectLocker lock(threadObj, thread);
1604 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1605 thread->clear_pending_exception();
1606 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1607 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1608 // Clear the native thread instance - this makes isAlive return false and allows the join()
1609 // to complete once we've done the notify_all below
1610 java_lang_Thread::set_thread(threadObj(), NULL);
1611 lock.notify_all(thread);
1612 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1613 thread->clear_pending_exception();
1614 }
1617 // For any new cleanup additions, please check to see if they need to be applied to
1618 // cleanup_failed_attach_current_thread as well.
1619 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1620 assert(this == JavaThread::current(), "thread consistency check");
1621 if (!InitializeJavaLangSystem) return;
1623 HandleMark hm(this);
1624 Handle uncaught_exception(this, this->pending_exception());
1625 this->clear_pending_exception();
1626 Handle threadObj(this, this->threadObj());
1627 assert(threadObj.not_null(), "Java thread object should be created");
1629 if (get_thread_profiler() != NULL) {
1630 get_thread_profiler()->disengage();
1631 ResourceMark rm;
1632 get_thread_profiler()->print(get_thread_name());
1633 }
1636 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1637 {
1638 EXCEPTION_MARK;
1640 CLEAR_PENDING_EXCEPTION;
1641 }
1642 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1643 // has to be fixed by a runtime query method
1644 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1645 // JSR-166: change call from from ThreadGroup.uncaughtException to
1646 // java.lang.Thread.dispatchUncaughtException
1647 if (uncaught_exception.not_null()) {
1648 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1649 {
1650 EXCEPTION_MARK;
1651 // Check if the method Thread.dispatchUncaughtException() exists. If so
1652 // call it. Otherwise we have an older library without the JSR-166 changes,
1653 // so call ThreadGroup.uncaughtException()
1654 KlassHandle recvrKlass(THREAD, threadObj->klass());
1655 CallInfo callinfo;
1656 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1657 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1658 vmSymbols::dispatchUncaughtException_name(),
1659 vmSymbols::throwable_void_signature(),
1660 KlassHandle(), false, false, THREAD);
1661 CLEAR_PENDING_EXCEPTION;
1662 methodHandle method = callinfo.selected_method();
1663 if (method.not_null()) {
1664 JavaValue result(T_VOID);
1665 JavaCalls::call_virtual(&result,
1666 threadObj, thread_klass,
1667 vmSymbols::dispatchUncaughtException_name(),
1668 vmSymbols::throwable_void_signature(),
1669 uncaught_exception,
1670 THREAD);
1671 } else {
1672 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1673 JavaValue result(T_VOID);
1674 JavaCalls::call_virtual(&result,
1675 group, thread_group,
1676 vmSymbols::uncaughtException_name(),
1677 vmSymbols::thread_throwable_void_signature(),
1678 threadObj, // Arg 1
1679 uncaught_exception, // Arg 2
1680 THREAD);
1681 }
1682 if (HAS_PENDING_EXCEPTION) {
1683 ResourceMark rm(this);
1684 jio_fprintf(defaultStream::error_stream(),
1685 "\nException: %s thrown from the UncaughtExceptionHandler"
1686 " in thread \"%s\"\n",
1687 Klass::cast(pending_exception()->klass())->external_name(),
1688 get_thread_name());
1689 CLEAR_PENDING_EXCEPTION;
1690 }
1691 }
1692 }
1694 // Called before the java thread exit since we want to read info
1695 // from java_lang_Thread object
1696 EVENT_BEGIN(TraceEventThreadEnd, event);
1697 EVENT_COMMIT(event,
1698 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj())));
1700 // Call after last event on thread
1701 EVENT_THREAD_EXIT(this);
1703 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1704 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1705 // is deprecated anyhow.
1706 { int count = 3;
1707 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1708 EXCEPTION_MARK;
1709 JavaValue result(T_VOID);
1710 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1711 JavaCalls::call_virtual(&result,
1712 threadObj, thread_klass,
1713 vmSymbols::exit_method_name(),
1714 vmSymbols::void_method_signature(),
1715 THREAD);
1716 CLEAR_PENDING_EXCEPTION;
1717 }
1718 }
1720 // notify JVMTI
1721 if (JvmtiExport::should_post_thread_life()) {
1722 JvmtiExport::post_thread_end(this);
1723 }
1725 // We have notified the agents that we are exiting, before we go on,
1726 // we must check for a pending external suspend request and honor it
1727 // in order to not surprise the thread that made the suspend request.
1728 while (true) {
1729 {
1730 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1731 if (!is_external_suspend()) {
1732 set_terminated(_thread_exiting);
1733 ThreadService::current_thread_exiting(this);
1734 break;
1735 }
1736 // Implied else:
1737 // Things get a little tricky here. We have a pending external
1738 // suspend request, but we are holding the SR_lock so we
1739 // can't just self-suspend. So we temporarily drop the lock
1740 // and then self-suspend.
1741 }
1743 ThreadBlockInVM tbivm(this);
1744 java_suspend_self();
1746 // We're done with this suspend request, but we have to loop around
1747 // and check again. Eventually we will get SR_lock without a pending
1748 // external suspend request and will be able to mark ourselves as
1749 // exiting.
1750 }
1751 // no more external suspends are allowed at this point
1752 } else {
1753 // before_exit() has already posted JVMTI THREAD_END events
1754 }
1756 // Notify waiters on thread object. This has to be done after exit() is called
1757 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1758 // group should have the destroyed bit set before waiters are notified).
1759 ensure_join(this);
1760 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1762 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1763 // held by this thread must be released. A detach operation must only
1764 // get here if there are no Java frames on the stack. Therefore, any
1765 // owned monitors at this point MUST be JNI-acquired monitors which are
1766 // pre-inflated and in the monitor cache.
1767 //
1768 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1769 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1770 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1771 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1772 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1773 }
1775 // These things needs to be done while we are still a Java Thread. Make sure that thread
1776 // is in a consistent state, in case GC happens
1777 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1779 if (active_handles() != NULL) {
1780 JNIHandleBlock* block = active_handles();
1781 set_active_handles(NULL);
1782 JNIHandleBlock::release_block(block);
1783 }
1785 if (free_handle_block() != NULL) {
1786 JNIHandleBlock* block = free_handle_block();
1787 set_free_handle_block(NULL);
1788 JNIHandleBlock::release_block(block);
1789 }
1791 // These have to be removed while this is still a valid thread.
1792 remove_stack_guard_pages();
1794 if (UseTLAB) {
1795 tlab().make_parsable(true); // retire TLAB
1796 }
1798 if (JvmtiEnv::environments_might_exist()) {
1799 JvmtiExport::cleanup_thread(this);
1800 }
1802 #ifndef SERIALGC
1803 // We must flush G1-related buffers before removing a thread from
1804 // the list of active threads.
1805 if (UseG1GC) {
1806 flush_barrier_queues();
1807 }
1808 #endif
1810 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1811 Threads::remove(this);
1812 }
1814 #ifndef SERIALGC
1815 // Flush G1-related queues.
1816 void JavaThread::flush_barrier_queues() {
1817 satb_mark_queue().flush();
1818 dirty_card_queue().flush();
1819 }
1821 void JavaThread::initialize_queues() {
1822 assert(!SafepointSynchronize::is_at_safepoint(),
1823 "we should not be at a safepoint");
1825 ObjPtrQueue& satb_queue = satb_mark_queue();
1826 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1827 // The SATB queue should have been constructed with its active
1828 // field set to false.
1829 assert(!satb_queue.is_active(), "SATB queue should not be active");
1830 assert(satb_queue.is_empty(), "SATB queue should be empty");
1831 // If we are creating the thread during a marking cycle, we should
1832 // set the active field of the SATB queue to true.
1833 if (satb_queue_set.is_active()) {
1834 satb_queue.set_active(true);
1835 }
1837 DirtyCardQueue& dirty_queue = dirty_card_queue();
1838 // The dirty card queue should have been constructed with its
1839 // active field set to true.
1840 assert(dirty_queue.is_active(), "dirty card queue should be active");
1841 }
1842 #endif // !SERIALGC
1844 void JavaThread::cleanup_failed_attach_current_thread() {
1845 if (get_thread_profiler() != NULL) {
1846 get_thread_profiler()->disengage();
1847 ResourceMark rm;
1848 get_thread_profiler()->print(get_thread_name());
1849 }
1851 if (active_handles() != NULL) {
1852 JNIHandleBlock* block = active_handles();
1853 set_active_handles(NULL);
1854 JNIHandleBlock::release_block(block);
1855 }
1857 if (free_handle_block() != NULL) {
1858 JNIHandleBlock* block = free_handle_block();
1859 set_free_handle_block(NULL);
1860 JNIHandleBlock::release_block(block);
1861 }
1863 // These have to be removed while this is still a valid thread.
1864 remove_stack_guard_pages();
1866 if (UseTLAB) {
1867 tlab().make_parsable(true); // retire TLAB, if any
1868 }
1870 #ifndef SERIALGC
1871 if (UseG1GC) {
1872 flush_barrier_queues();
1873 }
1874 #endif
1876 Threads::remove(this);
1877 delete this;
1878 }
1883 JavaThread* JavaThread::active() {
1884 Thread* thread = ThreadLocalStorage::thread();
1885 assert(thread != NULL, "just checking");
1886 if (thread->is_Java_thread()) {
1887 return (JavaThread*) thread;
1888 } else {
1889 assert(thread->is_VM_thread(), "this must be a vm thread");
1890 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1891 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1892 assert(ret->is_Java_thread(), "must be a Java thread");
1893 return ret;
1894 }
1895 }
1897 bool JavaThread::is_lock_owned(address adr) const {
1898 if (Thread::is_lock_owned(adr)) return true;
1900 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1901 if (chunk->contains(adr)) return true;
1902 }
1904 return false;
1905 }
1908 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1909 chunk->set_next(monitor_chunks());
1910 set_monitor_chunks(chunk);
1911 }
1913 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1914 guarantee(monitor_chunks() != NULL, "must be non empty");
1915 if (monitor_chunks() == chunk) {
1916 set_monitor_chunks(chunk->next());
1917 } else {
1918 MonitorChunk* prev = monitor_chunks();
1919 while (prev->next() != chunk) prev = prev->next();
1920 prev->set_next(chunk->next());
1921 }
1922 }
1924 // JVM support.
1926 // Note: this function shouldn't block if it's called in
1927 // _thread_in_native_trans state (such as from
1928 // check_special_condition_for_native_trans()).
1929 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1931 if (has_last_Java_frame() && has_async_condition()) {
1932 // If we are at a polling page safepoint (not a poll return)
1933 // then we must defer async exception because live registers
1934 // will be clobbered by the exception path. Poll return is
1935 // ok because the call we a returning from already collides
1936 // with exception handling registers and so there is no issue.
1937 // (The exception handling path kills call result registers but
1938 // this is ok since the exception kills the result anyway).
1940 if (is_at_poll_safepoint()) {
1941 // if the code we are returning to has deoptimized we must defer
1942 // the exception otherwise live registers get clobbered on the
1943 // exception path before deoptimization is able to retrieve them.
1944 //
1945 RegisterMap map(this, false);
1946 frame caller_fr = last_frame().sender(&map);
1947 assert(caller_fr.is_compiled_frame(), "what?");
1948 if (caller_fr.is_deoptimized_frame()) {
1949 if (TraceExceptions) {
1950 ResourceMark rm;
1951 tty->print_cr("deferred async exception at compiled safepoint");
1952 }
1953 return;
1954 }
1955 }
1956 }
1958 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1959 if (condition == _no_async_condition) {
1960 // Conditions have changed since has_special_runtime_exit_condition()
1961 // was called:
1962 // - if we were here only because of an external suspend request,
1963 // then that was taken care of above (or cancelled) so we are done
1964 // - if we were here because of another async request, then it has
1965 // been cleared between the has_special_runtime_exit_condition()
1966 // and now so again we are done
1967 return;
1968 }
1970 // Check for pending async. exception
1971 if (_pending_async_exception != NULL) {
1972 // Only overwrite an already pending exception, if it is not a threadDeath.
1973 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1975 // We cannot call Exceptions::_throw(...) here because we cannot block
1976 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1978 if (TraceExceptions) {
1979 ResourceMark rm;
1980 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1981 if (has_last_Java_frame() ) {
1982 frame f = last_frame();
1983 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1984 }
1985 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1986 }
1987 _pending_async_exception = NULL;
1988 clear_has_async_exception();
1989 }
1990 }
1992 if (check_unsafe_error &&
1993 condition == _async_unsafe_access_error && !has_pending_exception()) {
1994 condition = _no_async_condition; // done
1995 switch (thread_state()) {
1996 case _thread_in_vm:
1997 {
1998 JavaThread* THREAD = this;
1999 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2000 }
2001 case _thread_in_native:
2002 {
2003 ThreadInVMfromNative tiv(this);
2004 JavaThread* THREAD = this;
2005 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2006 }
2007 case _thread_in_Java:
2008 {
2009 ThreadInVMfromJava tiv(this);
2010 JavaThread* THREAD = this;
2011 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2012 }
2013 default:
2014 ShouldNotReachHere();
2015 }
2016 }
2018 assert(condition == _no_async_condition || has_pending_exception() ||
2019 (!check_unsafe_error && condition == _async_unsafe_access_error),
2020 "must have handled the async condition, if no exception");
2021 }
2023 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2024 //
2025 // Check for pending external suspend. Internal suspend requests do
2026 // not use handle_special_runtime_exit_condition().
2027 // If JNIEnv proxies are allowed, don't self-suspend if the target
2028 // thread is not the current thread. In older versions of jdbx, jdbx
2029 // threads could call into the VM with another thread's JNIEnv so we
2030 // can be here operating on behalf of a suspended thread (4432884).
2031 bool do_self_suspend = is_external_suspend_with_lock();
2032 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2033 //
2034 // Because thread is external suspended the safepoint code will count
2035 // thread as at a safepoint. This can be odd because we can be here
2036 // as _thread_in_Java which would normally transition to _thread_blocked
2037 // at a safepoint. We would like to mark the thread as _thread_blocked
2038 // before calling java_suspend_self like all other callers of it but
2039 // we must then observe proper safepoint protocol. (We can't leave
2040 // _thread_blocked with a safepoint in progress). However we can be
2041 // here as _thread_in_native_trans so we can't use a normal transition
2042 // constructor/destructor pair because they assert on that type of
2043 // transition. We could do something like:
2044 //
2045 // JavaThreadState state = thread_state();
2046 // set_thread_state(_thread_in_vm);
2047 // {
2048 // ThreadBlockInVM tbivm(this);
2049 // java_suspend_self()
2050 // }
2051 // set_thread_state(_thread_in_vm_trans);
2052 // if (safepoint) block;
2053 // set_thread_state(state);
2054 //
2055 // but that is pretty messy. Instead we just go with the way the
2056 // code has worked before and note that this is the only path to
2057 // java_suspend_self that doesn't put the thread in _thread_blocked
2058 // mode.
2060 frame_anchor()->make_walkable(this);
2061 java_suspend_self();
2063 // We might be here for reasons in addition to the self-suspend request
2064 // so check for other async requests.
2065 }
2067 if (check_asyncs) {
2068 check_and_handle_async_exceptions();
2069 }
2070 }
2072 void JavaThread::send_thread_stop(oop java_throwable) {
2073 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2074 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2075 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2077 // Do not throw asynchronous exceptions against the compiler thread
2078 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2079 if (is_Compiler_thread()) return;
2081 {
2082 // Actually throw the Throwable against the target Thread - however
2083 // only if there is no thread death exception installed already.
2084 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2085 // If the topmost frame is a runtime stub, then we are calling into
2086 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2087 // must deoptimize the caller before continuing, as the compiled exception handler table
2088 // may not be valid
2089 if (has_last_Java_frame()) {
2090 frame f = last_frame();
2091 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2092 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2093 RegisterMap reg_map(this, UseBiasedLocking);
2094 frame compiled_frame = f.sender(®_map);
2095 if (compiled_frame.can_be_deoptimized()) {
2096 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2097 }
2098 }
2099 }
2101 // Set async. pending exception in thread.
2102 set_pending_async_exception(java_throwable);
2104 if (TraceExceptions) {
2105 ResourceMark rm;
2106 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2107 }
2108 // for AbortVMOnException flag
2109 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2110 }
2111 }
2114 // Interrupt thread so it will wake up from a potential wait()
2115 Thread::interrupt(this);
2116 }
2118 // External suspension mechanism.
2119 //
2120 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2121 // to any VM_locks and it is at a transition
2122 // Self-suspension will happen on the transition out of the vm.
2123 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2124 //
2125 // Guarantees on return:
2126 // + Target thread will not execute any new bytecode (that's why we need to
2127 // force a safepoint)
2128 // + Target thread will not enter any new monitors
2129 //
2130 void JavaThread::java_suspend() {
2131 { MutexLocker mu(Threads_lock);
2132 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2133 return;
2134 }
2135 }
2137 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2138 if (!is_external_suspend()) {
2139 // a racing resume has cancelled us; bail out now
2140 return;
2141 }
2143 // suspend is done
2144 uint32_t debug_bits = 0;
2145 // Warning: is_ext_suspend_completed() may temporarily drop the
2146 // SR_lock to allow the thread to reach a stable thread state if
2147 // it is currently in a transient thread state.
2148 if (is_ext_suspend_completed(false /* !called_by_wait */,
2149 SuspendRetryDelay, &debug_bits) ) {
2150 return;
2151 }
2152 }
2154 VM_ForceSafepoint vm_suspend;
2155 VMThread::execute(&vm_suspend);
2156 }
2158 // Part II of external suspension.
2159 // A JavaThread self suspends when it detects a pending external suspend
2160 // request. This is usually on transitions. It is also done in places
2161 // where continuing to the next transition would surprise the caller,
2162 // e.g., monitor entry.
2163 //
2164 // Returns the number of times that the thread self-suspended.
2165 //
2166 // Note: DO NOT call java_suspend_self() when you just want to block current
2167 // thread. java_suspend_self() is the second stage of cooperative
2168 // suspension for external suspend requests and should only be used
2169 // to complete an external suspend request.
2170 //
2171 int JavaThread::java_suspend_self() {
2172 int ret = 0;
2174 // we are in the process of exiting so don't suspend
2175 if (is_exiting()) {
2176 clear_external_suspend();
2177 return ret;
2178 }
2180 assert(_anchor.walkable() ||
2181 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2182 "must have walkable stack");
2184 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2186 assert(!this->is_ext_suspended(),
2187 "a thread trying to self-suspend should not already be suspended");
2189 if (this->is_suspend_equivalent()) {
2190 // If we are self-suspending as a result of the lifting of a
2191 // suspend equivalent condition, then the suspend_equivalent
2192 // flag is not cleared until we set the ext_suspended flag so
2193 // that wait_for_ext_suspend_completion() returns consistent
2194 // results.
2195 this->clear_suspend_equivalent();
2196 }
2198 // A racing resume may have cancelled us before we grabbed SR_lock
2199 // above. Or another external suspend request could be waiting for us
2200 // by the time we return from SR_lock()->wait(). The thread
2201 // that requested the suspension may already be trying to walk our
2202 // stack and if we return now, we can change the stack out from under
2203 // it. This would be a "bad thing (TM)" and cause the stack walker
2204 // to crash. We stay self-suspended until there are no more pending
2205 // external suspend requests.
2206 while (is_external_suspend()) {
2207 ret++;
2208 this->set_ext_suspended();
2210 // _ext_suspended flag is cleared by java_resume()
2211 while (is_ext_suspended()) {
2212 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2213 }
2214 }
2216 return ret;
2217 }
2219 #ifdef ASSERT
2220 // verify the JavaThread has not yet been published in the Threads::list, and
2221 // hence doesn't need protection from concurrent access at this stage
2222 void JavaThread::verify_not_published() {
2223 if (!Threads_lock->owned_by_self()) {
2224 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2225 assert( !Threads::includes(this),
2226 "java thread shouldn't have been published yet!");
2227 }
2228 else {
2229 assert( !Threads::includes(this),
2230 "java thread shouldn't have been published yet!");
2231 }
2232 }
2233 #endif
2235 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2236 // progress or when _suspend_flags is non-zero.
2237 // Current thread needs to self-suspend if there is a suspend request and/or
2238 // block if a safepoint is in progress.
2239 // Async exception ISN'T checked.
2240 // Note only the ThreadInVMfromNative transition can call this function
2241 // directly and when thread state is _thread_in_native_trans
2242 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2243 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2245 JavaThread *curJT = JavaThread::current();
2246 bool do_self_suspend = thread->is_external_suspend();
2248 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2250 // If JNIEnv proxies are allowed, don't self-suspend if the target
2251 // thread is not the current thread. In older versions of jdbx, jdbx
2252 // threads could call into the VM with another thread's JNIEnv so we
2253 // can be here operating on behalf of a suspended thread (4432884).
2254 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2255 JavaThreadState state = thread->thread_state();
2257 // We mark this thread_blocked state as a suspend-equivalent so
2258 // that a caller to is_ext_suspend_completed() won't be confused.
2259 // The suspend-equivalent state is cleared by java_suspend_self().
2260 thread->set_suspend_equivalent();
2262 // If the safepoint code sees the _thread_in_native_trans state, it will
2263 // wait until the thread changes to other thread state. There is no
2264 // guarantee on how soon we can obtain the SR_lock and complete the
2265 // self-suspend request. It would be a bad idea to let safepoint wait for
2266 // too long. Temporarily change the state to _thread_blocked to
2267 // let the VM thread know that this thread is ready for GC. The problem
2268 // of changing thread state is that safepoint could happen just after
2269 // java_suspend_self() returns after being resumed, and VM thread will
2270 // see the _thread_blocked state. We must check for safepoint
2271 // after restoring the state and make sure we won't leave while a safepoint
2272 // is in progress.
2273 thread->set_thread_state(_thread_blocked);
2274 thread->java_suspend_self();
2275 thread->set_thread_state(state);
2276 // Make sure new state is seen by VM thread
2277 if (os::is_MP()) {
2278 if (UseMembar) {
2279 // Force a fence between the write above and read below
2280 OrderAccess::fence();
2281 } else {
2282 // Must use this rather than serialization page in particular on Windows
2283 InterfaceSupport::serialize_memory(thread);
2284 }
2285 }
2286 }
2288 if (SafepointSynchronize::do_call_back()) {
2289 // If we are safepointing, then block the caller which may not be
2290 // the same as the target thread (see above).
2291 SafepointSynchronize::block(curJT);
2292 }
2294 if (thread->is_deopt_suspend()) {
2295 thread->clear_deopt_suspend();
2296 RegisterMap map(thread, false);
2297 frame f = thread->last_frame();
2298 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2299 f = f.sender(&map);
2300 }
2301 if (f.id() == thread->must_deopt_id()) {
2302 thread->clear_must_deopt_id();
2303 f.deoptimize(thread);
2304 } else {
2305 fatal("missed deoptimization!");
2306 }
2307 }
2308 }
2310 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2311 // progress or when _suspend_flags is non-zero.
2312 // Current thread needs to self-suspend if there is a suspend request and/or
2313 // block if a safepoint is in progress.
2314 // Also check for pending async exception (not including unsafe access error).
2315 // Note only the native==>VM/Java barriers can call this function and when
2316 // thread state is _thread_in_native_trans.
2317 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2318 check_safepoint_and_suspend_for_native_trans(thread);
2320 if (thread->has_async_exception()) {
2321 // We are in _thread_in_native_trans state, don't handle unsafe
2322 // access error since that may block.
2323 thread->check_and_handle_async_exceptions(false);
2324 }
2325 }
2327 // This is a variant of the normal
2328 // check_special_condition_for_native_trans with slightly different
2329 // semantics for use by critical native wrappers. It does all the
2330 // normal checks but also performs the transition back into
2331 // thread_in_Java state. This is required so that critical natives
2332 // can potentially block and perform a GC if they are the last thread
2333 // exiting the GC_locker.
2334 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2335 check_special_condition_for_native_trans(thread);
2337 // Finish the transition
2338 thread->set_thread_state(_thread_in_Java);
2340 if (thread->do_critical_native_unlock()) {
2341 ThreadInVMfromJavaNoAsyncException tiv(thread);
2342 GC_locker::unlock_critical(thread);
2343 thread->clear_critical_native_unlock();
2344 }
2345 }
2347 // We need to guarantee the Threads_lock here, since resumes are not
2348 // allowed during safepoint synchronization
2349 // Can only resume from an external suspension
2350 void JavaThread::java_resume() {
2351 assert_locked_or_safepoint(Threads_lock);
2353 // Sanity check: thread is gone, has started exiting or the thread
2354 // was not externally suspended.
2355 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2356 return;
2357 }
2359 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2361 clear_external_suspend();
2363 if (is_ext_suspended()) {
2364 clear_ext_suspended();
2365 SR_lock()->notify_all();
2366 }
2367 }
2369 void JavaThread::create_stack_guard_pages() {
2370 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2371 address low_addr = stack_base() - stack_size();
2372 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2374 int allocate = os::allocate_stack_guard_pages();
2375 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2377 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2378 warning("Attempt to allocate stack guard pages failed.");
2379 return;
2380 }
2382 if (os::guard_memory((char *) low_addr, len)) {
2383 _stack_guard_state = stack_guard_enabled;
2384 } else {
2385 warning("Attempt to protect stack guard pages failed.");
2386 if (os::uncommit_memory((char *) low_addr, len)) {
2387 warning("Attempt to deallocate stack guard pages failed.");
2388 }
2389 }
2390 }
2392 void JavaThread::remove_stack_guard_pages() {
2393 if (_stack_guard_state == stack_guard_unused) return;
2394 address low_addr = stack_base() - stack_size();
2395 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2397 if (os::allocate_stack_guard_pages()) {
2398 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2399 _stack_guard_state = stack_guard_unused;
2400 } else {
2401 warning("Attempt to deallocate stack guard pages failed.");
2402 }
2403 } else {
2404 if (_stack_guard_state == stack_guard_unused) return;
2405 if (os::unguard_memory((char *) low_addr, len)) {
2406 _stack_guard_state = stack_guard_unused;
2407 } else {
2408 warning("Attempt to unprotect stack guard pages failed.");
2409 }
2410 }
2411 }
2413 void JavaThread::enable_stack_yellow_zone() {
2414 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2415 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2417 // The base notation is from the stacks point of view, growing downward.
2418 // We need to adjust it to work correctly with guard_memory()
2419 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2421 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2422 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2424 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2425 _stack_guard_state = stack_guard_enabled;
2426 } else {
2427 warning("Attempt to guard stack yellow zone failed.");
2428 }
2429 enable_register_stack_guard();
2430 }
2432 void JavaThread::disable_stack_yellow_zone() {
2433 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2434 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2436 // Simply return if called for a thread that does not use guard pages.
2437 if (_stack_guard_state == stack_guard_unused) return;
2439 // The base notation is from the stacks point of view, growing downward.
2440 // We need to adjust it to work correctly with guard_memory()
2441 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2443 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2444 _stack_guard_state = stack_guard_yellow_disabled;
2445 } else {
2446 warning("Attempt to unguard stack yellow zone failed.");
2447 }
2448 disable_register_stack_guard();
2449 }
2451 void JavaThread::enable_stack_red_zone() {
2452 // The base notation is from the stacks point of view, growing downward.
2453 // We need to adjust it to work correctly with guard_memory()
2454 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2455 address base = stack_red_zone_base() - stack_red_zone_size();
2457 guarantee(base < stack_base(),"Error calculating stack red zone");
2458 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2460 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2461 warning("Attempt to guard stack red zone failed.");
2462 }
2463 }
2465 void JavaThread::disable_stack_red_zone() {
2466 // The base notation is from the stacks point of view, growing downward.
2467 // We need to adjust it to work correctly with guard_memory()
2468 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2469 address base = stack_red_zone_base() - stack_red_zone_size();
2470 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2471 warning("Attempt to unguard stack red zone failed.");
2472 }
2473 }
2475 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2476 // ignore is there is no stack
2477 if (!has_last_Java_frame()) return;
2478 // traverse the stack frames. Starts from top frame.
2479 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2480 frame* fr = fst.current();
2481 f(fr, fst.register_map());
2482 }
2483 }
2486 #ifndef PRODUCT
2487 // Deoptimization
2488 // Function for testing deoptimization
2489 void JavaThread::deoptimize() {
2490 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2491 StackFrameStream fst(this, UseBiasedLocking);
2492 bool deopt = false; // Dump stack only if a deopt actually happens.
2493 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2494 // Iterate over all frames in the thread and deoptimize
2495 for(; !fst.is_done(); fst.next()) {
2496 if(fst.current()->can_be_deoptimized()) {
2498 if (only_at) {
2499 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2500 // consists of comma or carriage return separated numbers so
2501 // search for the current bci in that string.
2502 address pc = fst.current()->pc();
2503 nmethod* nm = (nmethod*) fst.current()->cb();
2504 ScopeDesc* sd = nm->scope_desc_at( pc);
2505 char buffer[8];
2506 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2507 size_t len = strlen(buffer);
2508 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2509 while (found != NULL) {
2510 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2511 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2512 // Check that the bci found is bracketed by terminators.
2513 break;
2514 }
2515 found = strstr(found + 1, buffer);
2516 }
2517 if (!found) {
2518 continue;
2519 }
2520 }
2522 if (DebugDeoptimization && !deopt) {
2523 deopt = true; // One-time only print before deopt
2524 tty->print_cr("[BEFORE Deoptimization]");
2525 trace_frames();
2526 trace_stack();
2527 }
2528 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2529 }
2530 }
2532 if (DebugDeoptimization && deopt) {
2533 tty->print_cr("[AFTER Deoptimization]");
2534 trace_frames();
2535 }
2536 }
2539 // Make zombies
2540 void JavaThread::make_zombies() {
2541 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2542 if (fst.current()->can_be_deoptimized()) {
2543 // it is a Java nmethod
2544 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2545 nm->make_not_entrant();
2546 }
2547 }
2548 }
2549 #endif // PRODUCT
2552 void JavaThread::deoptimized_wrt_marked_nmethods() {
2553 if (!has_last_Java_frame()) return;
2554 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2555 StackFrameStream fst(this, UseBiasedLocking);
2556 for(; !fst.is_done(); fst.next()) {
2557 if (fst.current()->should_be_deoptimized()) {
2558 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2559 }
2560 }
2561 }
2564 // GC support
2565 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2567 void JavaThread::gc_epilogue() {
2568 frames_do(frame_gc_epilogue);
2569 }
2572 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2574 void JavaThread::gc_prologue() {
2575 frames_do(frame_gc_prologue);
2576 }
2578 // If the caller is a NamedThread, then remember, in the current scope,
2579 // the given JavaThread in its _processed_thread field.
2580 class RememberProcessedThread: public StackObj {
2581 NamedThread* _cur_thr;
2582 public:
2583 RememberProcessedThread(JavaThread* jthr) {
2584 Thread* thread = Thread::current();
2585 if (thread->is_Named_thread()) {
2586 _cur_thr = (NamedThread *)thread;
2587 _cur_thr->set_processed_thread(jthr);
2588 } else {
2589 _cur_thr = NULL;
2590 }
2591 }
2593 ~RememberProcessedThread() {
2594 if (_cur_thr) {
2595 _cur_thr->set_processed_thread(NULL);
2596 }
2597 }
2598 };
2600 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2601 // Verify that the deferred card marks have been flushed.
2602 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2604 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2605 // since there may be more than one thread using each ThreadProfiler.
2607 // Traverse the GCHandles
2608 Thread::oops_do(f, cf);
2610 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2611 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2613 if (has_last_Java_frame()) {
2614 // Record JavaThread to GC thread
2615 RememberProcessedThread rpt(this);
2617 // Traverse the privileged stack
2618 if (_privileged_stack_top != NULL) {
2619 _privileged_stack_top->oops_do(f);
2620 }
2622 // traverse the registered growable array
2623 if (_array_for_gc != NULL) {
2624 for (int index = 0; index < _array_for_gc->length(); index++) {
2625 f->do_oop(_array_for_gc->adr_at(index));
2626 }
2627 }
2629 // Traverse the monitor chunks
2630 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2631 chunk->oops_do(f);
2632 }
2634 // Traverse the execution stack
2635 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2636 fst.current()->oops_do(f, cf, fst.register_map());
2637 }
2638 }
2640 // callee_target is never live across a gc point so NULL it here should
2641 // it still contain a methdOop.
2643 set_callee_target(NULL);
2645 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2646 // If we have deferred set_locals there might be oops waiting to be
2647 // written
2648 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2649 if (list != NULL) {
2650 for (int i = 0; i < list->length(); i++) {
2651 list->at(i)->oops_do(f);
2652 }
2653 }
2655 // Traverse instance variables at the end since the GC may be moving things
2656 // around using this function
2657 f->do_oop((oop*) &_threadObj);
2658 f->do_oop((oop*) &_vm_result);
2659 f->do_oop((oop*) &_vm_result_2);
2660 f->do_oop((oop*) &_exception_oop);
2661 f->do_oop((oop*) &_pending_async_exception);
2663 if (jvmti_thread_state() != NULL) {
2664 jvmti_thread_state()->oops_do(f);
2665 }
2666 }
2668 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2669 Thread::nmethods_do(cf); // (super method is a no-op)
2671 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2672 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2674 if (has_last_Java_frame()) {
2675 // Traverse the execution stack
2676 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2677 fst.current()->nmethods_do(cf);
2678 }
2679 }
2680 }
2682 // Printing
2683 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2684 switch (_thread_state) {
2685 case _thread_uninitialized: return "_thread_uninitialized";
2686 case _thread_new: return "_thread_new";
2687 case _thread_new_trans: return "_thread_new_trans";
2688 case _thread_in_native: return "_thread_in_native";
2689 case _thread_in_native_trans: return "_thread_in_native_trans";
2690 case _thread_in_vm: return "_thread_in_vm";
2691 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2692 case _thread_in_Java: return "_thread_in_Java";
2693 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2694 case _thread_blocked: return "_thread_blocked";
2695 case _thread_blocked_trans: return "_thread_blocked_trans";
2696 default: return "unknown thread state";
2697 }
2698 }
2700 #ifndef PRODUCT
2701 void JavaThread::print_thread_state_on(outputStream *st) const {
2702 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2703 };
2704 void JavaThread::print_thread_state() const {
2705 print_thread_state_on(tty);
2706 };
2707 #endif // PRODUCT
2709 // Called by Threads::print() for VM_PrintThreads operation
2710 void JavaThread::print_on(outputStream *st) const {
2711 st->print("\"%s\" ", get_thread_name());
2712 oop thread_oop = threadObj();
2713 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2714 Thread::print_on(st);
2715 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2716 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2717 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2718 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2719 }
2720 #ifndef PRODUCT
2721 print_thread_state_on(st);
2722 _safepoint_state->print_on(st);
2723 #endif // PRODUCT
2724 }
2726 // Called by fatal error handler. The difference between this and
2727 // JavaThread::print() is that we can't grab lock or allocate memory.
2728 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2729 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2730 oop thread_obj = threadObj();
2731 if (thread_obj != NULL) {
2732 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2733 }
2734 st->print(" [");
2735 st->print("%s", _get_thread_state_name(_thread_state));
2736 if (osthread()) {
2737 st->print(", id=%d", osthread()->thread_id());
2738 }
2739 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2740 _stack_base - _stack_size, _stack_base);
2741 st->print("]");
2742 return;
2743 }
2745 // Verification
2747 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2749 void JavaThread::verify() {
2750 // Verify oops in the thread.
2751 oops_do(&VerifyOopClosure::verify_oop, NULL);
2753 // Verify the stack frames.
2754 frames_do(frame_verify);
2755 }
2757 // CR 6300358 (sub-CR 2137150)
2758 // Most callers of this method assume that it can't return NULL but a
2759 // thread may not have a name whilst it is in the process of attaching to
2760 // the VM - see CR 6412693, and there are places where a JavaThread can be
2761 // seen prior to having it's threadObj set (eg JNI attaching threads and
2762 // if vm exit occurs during initialization). These cases can all be accounted
2763 // for such that this method never returns NULL.
2764 const char* JavaThread::get_thread_name() const {
2765 #ifdef ASSERT
2766 // early safepoints can hit while current thread does not yet have TLS
2767 if (!SafepointSynchronize::is_at_safepoint()) {
2768 Thread *cur = Thread::current();
2769 if (!(cur->is_Java_thread() && cur == this)) {
2770 // Current JavaThreads are allowed to get their own name without
2771 // the Threads_lock.
2772 assert_locked_or_safepoint(Threads_lock);
2773 }
2774 }
2775 #endif // ASSERT
2776 return get_thread_name_string();
2777 }
2779 // Returns a non-NULL representation of this thread's name, or a suitable
2780 // descriptive string if there is no set name
2781 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2782 const char* name_str;
2783 oop thread_obj = threadObj();
2784 if (thread_obj != NULL) {
2785 typeArrayOop name = java_lang_Thread::name(thread_obj);
2786 if (name != NULL) {
2787 if (buf == NULL) {
2788 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2789 }
2790 else {
2791 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2792 }
2793 }
2794 else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2795 name_str = "<no-name - thread is attaching>";
2796 }
2797 else {
2798 name_str = Thread::name();
2799 }
2800 }
2801 else {
2802 name_str = Thread::name();
2803 }
2804 assert(name_str != NULL, "unexpected NULL thread name");
2805 return name_str;
2806 }
2809 const char* JavaThread::get_threadgroup_name() const {
2810 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2811 oop thread_obj = threadObj();
2812 if (thread_obj != NULL) {
2813 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2814 if (thread_group != NULL) {
2815 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2816 // ThreadGroup.name can be null
2817 if (name != NULL) {
2818 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2819 return str;
2820 }
2821 }
2822 }
2823 return NULL;
2824 }
2826 const char* JavaThread::get_parent_name() const {
2827 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2828 oop thread_obj = threadObj();
2829 if (thread_obj != NULL) {
2830 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2831 if (thread_group != NULL) {
2832 oop parent = java_lang_ThreadGroup::parent(thread_group);
2833 if (parent != NULL) {
2834 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2835 // ThreadGroup.name can be null
2836 if (name != NULL) {
2837 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2838 return str;
2839 }
2840 }
2841 }
2842 }
2843 return NULL;
2844 }
2846 ThreadPriority JavaThread::java_priority() const {
2847 oop thr_oop = threadObj();
2848 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2849 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2850 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2851 return priority;
2852 }
2854 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2856 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2857 // Link Java Thread object <-> C++ Thread
2859 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2860 // and put it into a new Handle. The Handle "thread_oop" can then
2861 // be used to pass the C++ thread object to other methods.
2863 // Set the Java level thread object (jthread) field of the
2864 // new thread (a JavaThread *) to C++ thread object using the
2865 // "thread_oop" handle.
2867 // Set the thread field (a JavaThread *) of the
2868 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2870 Handle thread_oop(Thread::current(),
2871 JNIHandles::resolve_non_null(jni_thread));
2872 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2873 "must be initialized");
2874 set_threadObj(thread_oop());
2875 java_lang_Thread::set_thread(thread_oop(), this);
2877 if (prio == NoPriority) {
2878 prio = java_lang_Thread::priority(thread_oop());
2879 assert(prio != NoPriority, "A valid priority should be present");
2880 }
2882 // Push the Java priority down to the native thread; needs Threads_lock
2883 Thread::set_priority(this, prio);
2885 // Add the new thread to the Threads list and set it in motion.
2886 // We must have threads lock in order to call Threads::add.
2887 // It is crucial that we do not block before the thread is
2888 // added to the Threads list for if a GC happens, then the java_thread oop
2889 // will not be visited by GC.
2890 Threads::add(this);
2891 }
2893 oop JavaThread::current_park_blocker() {
2894 // Support for JSR-166 locks
2895 oop thread_oop = threadObj();
2896 if (thread_oop != NULL &&
2897 JDK_Version::current().supports_thread_park_blocker()) {
2898 return java_lang_Thread::park_blocker(thread_oop);
2899 }
2900 return NULL;
2901 }
2904 void JavaThread::print_stack_on(outputStream* st) {
2905 if (!has_last_Java_frame()) return;
2906 ResourceMark rm;
2907 HandleMark hm;
2909 RegisterMap reg_map(this);
2910 vframe* start_vf = last_java_vframe(®_map);
2911 int count = 0;
2912 for (vframe* f = start_vf; f; f = f->sender() ) {
2913 if (f->is_java_frame()) {
2914 javaVFrame* jvf = javaVFrame::cast(f);
2915 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2917 // Print out lock information
2918 if (JavaMonitorsInStackTrace) {
2919 jvf->print_lock_info_on(st, count);
2920 }
2921 } else {
2922 // Ignore non-Java frames
2923 }
2925 // Bail-out case for too deep stacks
2926 count++;
2927 if (MaxJavaStackTraceDepth == count) return;
2928 }
2929 }
2932 // JVMTI PopFrame support
2933 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2934 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2935 if (in_bytes(size_in_bytes) != 0) {
2936 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2937 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2938 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2939 }
2940 }
2942 void* JavaThread::popframe_preserved_args() {
2943 return _popframe_preserved_args;
2944 }
2946 ByteSize JavaThread::popframe_preserved_args_size() {
2947 return in_ByteSize(_popframe_preserved_args_size);
2948 }
2950 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2951 int sz = in_bytes(popframe_preserved_args_size());
2952 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2953 return in_WordSize(sz / wordSize);
2954 }
2956 void JavaThread::popframe_free_preserved_args() {
2957 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2958 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread);
2959 _popframe_preserved_args = NULL;
2960 _popframe_preserved_args_size = 0;
2961 }
2963 #ifndef PRODUCT
2965 void JavaThread::trace_frames() {
2966 tty->print_cr("[Describe stack]");
2967 int frame_no = 1;
2968 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2969 tty->print(" %d. ", frame_no++);
2970 fst.current()->print_value_on(tty,this);
2971 tty->cr();
2972 }
2973 }
2975 class PrintAndVerifyOopClosure: public OopClosure {
2976 protected:
2977 template <class T> inline void do_oop_work(T* p) {
2978 oop obj = oopDesc::load_decode_heap_oop(p);
2979 if (obj == NULL) return;
2980 tty->print(INTPTR_FORMAT ": ", p);
2981 if (obj->is_oop_or_null()) {
2982 if (obj->is_objArray()) {
2983 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
2984 } else {
2985 obj->print();
2986 }
2987 } else {
2988 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
2989 }
2990 tty->cr();
2991 }
2992 public:
2993 virtual void do_oop(oop* p) { do_oop_work(p); }
2994 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2995 };
2998 static void oops_print(frame* f, const RegisterMap *map) {
2999 PrintAndVerifyOopClosure print;
3000 f->print_value();
3001 f->oops_do(&print, NULL, (RegisterMap*)map);
3002 }
3004 // Print our all the locations that contain oops and whether they are
3005 // valid or not. This useful when trying to find the oldest frame
3006 // where an oop has gone bad since the frame walk is from youngest to
3007 // oldest.
3008 void JavaThread::trace_oops() {
3009 tty->print_cr("[Trace oops]");
3010 frames_do(oops_print);
3011 }
3014 #ifdef ASSERT
3015 // Print or validate the layout of stack frames
3016 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3017 ResourceMark rm;
3018 PRESERVE_EXCEPTION_MARK;
3019 FrameValues values;
3020 int frame_no = 0;
3021 for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3022 fst.current()->describe(values, ++frame_no);
3023 if (depth == frame_no) break;
3024 }
3025 if (validate_only) {
3026 values.validate();
3027 } else {
3028 tty->print_cr("[Describe stack layout]");
3029 values.print(this);
3030 }
3031 }
3032 #endif
3034 void JavaThread::trace_stack_from(vframe* start_vf) {
3035 ResourceMark rm;
3036 int vframe_no = 1;
3037 for (vframe* f = start_vf; f; f = f->sender() ) {
3038 if (f->is_java_frame()) {
3039 javaVFrame::cast(f)->print_activation(vframe_no++);
3040 } else {
3041 f->print();
3042 }
3043 if (vframe_no > StackPrintLimit) {
3044 tty->print_cr("...<more frames>...");
3045 return;
3046 }
3047 }
3048 }
3051 void JavaThread::trace_stack() {
3052 if (!has_last_Java_frame()) return;
3053 ResourceMark rm;
3054 HandleMark hm;
3055 RegisterMap reg_map(this);
3056 trace_stack_from(last_java_vframe(®_map));
3057 }
3060 #endif // PRODUCT
3063 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3064 assert(reg_map != NULL, "a map must be given");
3065 frame f = last_frame();
3066 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
3067 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3068 }
3069 return NULL;
3070 }
3073 klassOop JavaThread::security_get_caller_class(int depth) {
3074 vframeStream vfst(this);
3075 vfst.security_get_caller_frame(depth);
3076 if (!vfst.at_end()) {
3077 return vfst.method()->method_holder();
3078 }
3079 return NULL;
3080 }
3082 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3083 assert(thread->is_Compiler_thread(), "must be compiler thread");
3084 CompileBroker::compiler_thread_loop();
3085 }
3087 // Create a CompilerThread
3088 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
3089 : JavaThread(&compiler_thread_entry) {
3090 _env = NULL;
3091 _log = NULL;
3092 _task = NULL;
3093 _queue = queue;
3094 _counters = counters;
3095 _buffer_blob = NULL;
3096 _scanned_nmethod = NULL;
3098 #ifndef PRODUCT
3099 _ideal_graph_printer = NULL;
3100 #endif
3101 }
3103 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3104 JavaThread::oops_do(f, cf);
3105 if (_scanned_nmethod != NULL && cf != NULL) {
3106 // Safepoints can occur when the sweeper is scanning an nmethod so
3107 // process it here to make sure it isn't unloaded in the middle of
3108 // a scan.
3109 cf->do_code_blob(_scanned_nmethod);
3110 }
3111 }
3113 // ======= Threads ========
3115 // The Threads class links together all active threads, and provides
3116 // operations over all threads. It is protected by its own Mutex
3117 // lock, which is also used in other contexts to protect thread
3118 // operations from having the thread being operated on from exiting
3119 // and going away unexpectedly (e.g., safepoint synchronization)
3121 JavaThread* Threads::_thread_list = NULL;
3122 int Threads::_number_of_threads = 0;
3123 int Threads::_number_of_non_daemon_threads = 0;
3124 int Threads::_return_code = 0;
3125 size_t JavaThread::_stack_size_at_create = 0;
3127 // All JavaThreads
3128 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3130 void os_stream();
3132 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3133 void Threads::threads_do(ThreadClosure* tc) {
3134 assert_locked_or_safepoint(Threads_lock);
3135 // ALL_JAVA_THREADS iterates through all JavaThreads
3136 ALL_JAVA_THREADS(p) {
3137 tc->do_thread(p);
3138 }
3139 // Someday we could have a table or list of all non-JavaThreads.
3140 // For now, just manually iterate through them.
3141 tc->do_thread(VMThread::vm_thread());
3142 Universe::heap()->gc_threads_do(tc);
3143 WatcherThread *wt = WatcherThread::watcher_thread();
3144 // Strictly speaking, the following NULL check isn't sufficient to make sure
3145 // the data for WatcherThread is still valid upon being examined. However,
3146 // considering that WatchThread terminates when the VM is on the way to
3147 // exit at safepoint, the chance of the above is extremely small. The right
3148 // way to prevent termination of WatcherThread would be to acquire
3149 // Terminator_lock, but we can't do that without violating the lock rank
3150 // checking in some cases.
3151 if (wt != NULL)
3152 tc->do_thread(wt);
3154 // If CompilerThreads ever become non-JavaThreads, add them here
3155 }
3157 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3159 extern void JDK_Version_init();
3161 // Check version
3162 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3164 // Initialize the output stream module
3165 ostream_init();
3167 // Process java launcher properties.
3168 Arguments::process_sun_java_launcher_properties(args);
3170 // Initialize the os module before using TLS
3171 os::init();
3173 // Initialize system properties.
3174 Arguments::init_system_properties();
3176 // So that JDK version can be used as a discrimintor when parsing arguments
3177 JDK_Version_init();
3179 // Update/Initialize System properties after JDK version number is known
3180 Arguments::init_version_specific_system_properties();
3182 // Parse arguments
3183 jint parse_result = Arguments::parse(args);
3184 if (parse_result != JNI_OK) return parse_result;
3186 if (PauseAtStartup) {
3187 os::pause();
3188 }
3190 #ifndef USDT2
3191 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3192 #else /* USDT2 */
3193 HOTSPOT_VM_INIT_BEGIN();
3194 #endif /* USDT2 */
3196 // Record VM creation timing statistics
3197 TraceVmCreationTime create_vm_timer;
3198 create_vm_timer.start();
3200 // Timing (must come after argument parsing)
3201 TraceTime timer("Create VM", TraceStartupTime);
3203 // Initialize the os module after parsing the args
3204 jint os_init_2_result = os::init_2();
3205 if (os_init_2_result != JNI_OK) return os_init_2_result;
3207 // intialize TLS
3208 ThreadLocalStorage::init();
3210 // Bootstrap native memory tracking, so it can start recording memory
3211 // activities before worker thread is started. This is the first phase
3212 // of bootstrapping, VM is currently running in single-thread mode.
3213 MemTracker::bootstrap_single_thread();
3215 // Initialize output stream logging
3216 ostream_init_log();
3218 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3219 // Must be before create_vm_init_agents()
3220 if (Arguments::init_libraries_at_startup()) {
3221 convert_vm_init_libraries_to_agents();
3222 }
3224 // Launch -agentlib/-agentpath and converted -Xrun agents
3225 if (Arguments::init_agents_at_startup()) {
3226 create_vm_init_agents();
3227 }
3229 // Initialize Threads state
3230 _thread_list = NULL;
3231 _number_of_threads = 0;
3232 _number_of_non_daemon_threads = 0;
3234 // Initialize global data structures and create system classes in heap
3235 vm_init_globals();
3237 // Attach the main thread to this os thread
3238 JavaThread* main_thread = new JavaThread();
3239 main_thread->set_thread_state(_thread_in_vm);
3240 // must do this before set_active_handles and initialize_thread_local_storage
3241 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3242 // change the stack size recorded here to one based on the java thread
3243 // stacksize. This adjusted size is what is used to figure the placement
3244 // of the guard pages.
3245 main_thread->record_stack_base_and_size();
3246 main_thread->initialize_thread_local_storage();
3248 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3250 if (!main_thread->set_as_starting_thread()) {
3251 vm_shutdown_during_initialization(
3252 "Failed necessary internal allocation. Out of swap space");
3253 delete main_thread;
3254 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3255 return JNI_ENOMEM;
3256 }
3258 // Enable guard page *after* os::create_main_thread(), otherwise it would
3259 // crash Linux VM, see notes in os_linux.cpp.
3260 main_thread->create_stack_guard_pages();
3262 // Initialize Java-Level synchronization subsystem
3263 ObjectMonitor::Initialize() ;
3265 // Second phase of bootstrapping, VM is about entering multi-thread mode
3266 MemTracker::bootstrap_multi_thread();
3268 // Initialize global modules
3269 jint status = init_globals();
3270 if (status != JNI_OK) {
3271 delete main_thread;
3272 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3273 return status;
3274 }
3276 // Should be done after the heap is fully created
3277 main_thread->cache_global_variables();
3279 HandleMark hm;
3281 { MutexLocker mu(Threads_lock);
3282 Threads::add(main_thread);
3283 }
3285 // Any JVMTI raw monitors entered in onload will transition into
3286 // real raw monitor. VM is setup enough here for raw monitor enter.
3287 JvmtiExport::transition_pending_onload_raw_monitors();
3289 if (VerifyBeforeGC &&
3290 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3291 Universe::heap()->prepare_for_verify();
3292 Universe::verify(); // make sure we're starting with a clean slate
3293 }
3295 // Fully start NMT
3296 MemTracker::start();
3298 // Create the VMThread
3299 { TraceTime timer("Start VMThread", TraceStartupTime);
3300 VMThread::create();
3301 Thread* vmthread = VMThread::vm_thread();
3303 if (!os::create_thread(vmthread, os::vm_thread))
3304 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3306 // Wait for the VM thread to become ready, and VMThread::run to initialize
3307 // Monitors can have spurious returns, must always check another state flag
3308 {
3309 MutexLocker ml(Notify_lock);
3310 os::start_thread(vmthread);
3311 while (vmthread->active_handles() == NULL) {
3312 Notify_lock->wait();
3313 }
3314 }
3315 }
3317 assert (Universe::is_fully_initialized(), "not initialized");
3318 EXCEPTION_MARK;
3320 // At this point, the Universe is initialized, but we have not executed
3321 // any byte code. Now is a good time (the only time) to dump out the
3322 // internal state of the JVM for sharing.
3324 if (DumpSharedSpaces) {
3325 Universe::heap()->preload_and_dump(CHECK_0);
3326 ShouldNotReachHere();
3327 }
3329 // Always call even when there are not JVMTI environments yet, since environments
3330 // may be attached late and JVMTI must track phases of VM execution
3331 JvmtiExport::enter_start_phase();
3333 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3334 JvmtiExport::post_vm_start();
3336 {
3337 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3339 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3340 create_vm_init_libraries();
3341 }
3343 if (InitializeJavaLangString) {
3344 initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3345 } else {
3346 warning("java.lang.String not initialized");
3347 }
3349 if (AggressiveOpts) {
3350 {
3351 // Forcibly initialize java/util/HashMap and mutate the private
3352 // static final "frontCacheEnabled" field before we start creating instances
3353 #ifdef ASSERT
3354 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3355 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3356 #endif
3357 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3358 KlassHandle k = KlassHandle(THREAD, k_o);
3359 guarantee(k.not_null(), "Must find java/util/HashMap");
3360 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3361 ik->initialize(CHECK_0);
3362 fieldDescriptor fd;
3363 // Possible we might not find this field; if so, don't break
3364 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3365 k()->java_mirror()->bool_field_put(fd.offset(), true);
3366 }
3367 }
3369 if (UseStringCache) {
3370 // Forcibly initialize java/lang/StringValue and mutate the private
3371 // static final "stringCacheEnabled" field before we start creating instances
3372 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3373 // Possible that StringValue isn't present: if so, silently don't break
3374 if (k_o != NULL) {
3375 KlassHandle k = KlassHandle(THREAD, k_o);
3376 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3377 ik->initialize(CHECK_0);
3378 fieldDescriptor fd;
3379 // Possible we might not find this field: if so, silently don't break
3380 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3381 k()->java_mirror()->bool_field_put(fd.offset(), true);
3382 }
3383 }
3384 }
3385 }
3387 // Initialize java_lang.System (needed before creating the thread)
3388 if (InitializeJavaLangSystem) {
3389 initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3390 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3391 Handle thread_group = create_initial_thread_group(CHECK_0);
3392 Universe::set_main_thread_group(thread_group());
3393 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3394 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3395 main_thread->set_threadObj(thread_object);
3396 // Set thread status to running since main thread has
3397 // been started and running.
3398 java_lang_Thread::set_thread_status(thread_object,
3399 java_lang_Thread::RUNNABLE);
3401 // The VM preresolve methods to these classes. Make sure that get initialized
3402 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3403 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0);
3404 // The VM creates & returns objects of this class. Make sure it's initialized.
3405 initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3406 call_initializeSystemClass(CHECK_0);
3408 // get the Java runtime name after java.lang.System is initialized
3409 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3410 } else {
3411 warning("java.lang.System not initialized");
3412 }
3414 // an instance of OutOfMemory exception has been allocated earlier
3415 if (InitializeJavaLangExceptionsErrors) {
3416 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3417 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3418 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3419 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3420 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3421 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3422 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3423 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK_0);
3424 } else {
3425 warning("java.lang.OutOfMemoryError has not been initialized");
3426 warning("java.lang.NullPointerException has not been initialized");
3427 warning("java.lang.ClassCastException has not been initialized");
3428 warning("java.lang.ArrayStoreException has not been initialized");
3429 warning("java.lang.ArithmeticException has not been initialized");
3430 warning("java.lang.StackOverflowError has not been initialized");
3431 warning("java.lang.IllegalArgumentException has not been initialized");
3432 }
3433 }
3435 // See : bugid 4211085.
3436 // Background : the static initializer of java.lang.Compiler tries to read
3437 // property"java.compiler" and read & write property "java.vm.info".
3438 // When a security manager is installed through the command line
3439 // option "-Djava.security.manager", the above properties are not
3440 // readable and the static initializer for java.lang.Compiler fails
3441 // resulting in a NoClassDefFoundError. This can happen in any
3442 // user code which calls methods in java.lang.Compiler.
3443 // Hack : the hack is to pre-load and initialize this class, so that only
3444 // system domains are on the stack when the properties are read.
3445 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3446 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3447 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3448 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3449 // Once that is done, we should remove this hack.
3450 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3452 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3453 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3454 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3455 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3456 // This should also be taken out as soon as 4211383 gets fixed.
3457 reset_vm_info_property(CHECK_0);
3459 quicken_jni_functions();
3461 // Must be run after init_ft which initializes ft_enabled
3462 if (TRACE_INITIALIZE() != JNI_OK) {
3463 vm_exit_during_initialization("Failed to initialize tracing backend");
3464 }
3466 // Set flag that basic initialization has completed. Used by exceptions and various
3467 // debug stuff, that does not work until all basic classes have been initialized.
3468 set_init_completed();
3470 #ifndef USDT2
3471 HS_DTRACE_PROBE(hotspot, vm__init__end);
3472 #else /* USDT2 */
3473 HOTSPOT_VM_INIT_END();
3474 #endif /* USDT2 */
3476 // record VM initialization completion time
3477 Management::record_vm_init_completed();
3479 // Compute system loader. Note that this has to occur after set_init_completed, since
3480 // valid exceptions may be thrown in the process.
3481 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3482 // set_init_completed has just been called, causing exceptions not to be shortcut
3483 // anymore. We call vm_exit_during_initialization directly instead.
3484 SystemDictionary::compute_java_system_loader(THREAD);
3485 if (HAS_PENDING_EXCEPTION) {
3486 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3487 }
3489 #ifndef SERIALGC
3490 // Support for ConcurrentMarkSweep. This should be cleaned up
3491 // and better encapsulated. The ugly nested if test would go away
3492 // once things are properly refactored. XXX YSR
3493 if (UseConcMarkSweepGC || UseG1GC) {
3494 if (UseConcMarkSweepGC) {
3495 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3496 } else {
3497 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3498 }
3499 if (HAS_PENDING_EXCEPTION) {
3500 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3501 }
3502 }
3503 #endif // SERIALGC
3505 // Always call even when there are not JVMTI environments yet, since environments
3506 // may be attached late and JVMTI must track phases of VM execution
3507 JvmtiExport::enter_live_phase();
3509 // Signal Dispatcher needs to be started before VMInit event is posted
3510 os::signal_init();
3512 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3513 if (!DisableAttachMechanism) {
3514 if (StartAttachListener || AttachListener::init_at_startup()) {
3515 AttachListener::init();
3516 }
3517 }
3519 // Launch -Xrun agents
3520 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3521 // back-end can launch with -Xdebug -Xrunjdwp.
3522 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3523 create_vm_init_libraries();
3524 }
3526 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3527 JvmtiExport::post_vm_initialized();
3529 if (!TRACE_START()) {
3530 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3531 }
3533 if (CleanChunkPoolAsync) {
3534 Chunk::start_chunk_pool_cleaner_task();
3535 }
3537 // initialize compiler(s)
3538 CompileBroker::compilation_init();
3540 Management::initialize(THREAD);
3541 if (HAS_PENDING_EXCEPTION) {
3542 // management agent fails to start possibly due to
3543 // configuration problem and is responsible for printing
3544 // stack trace if appropriate. Simply exit VM.
3545 vm_exit(1);
3546 }
3548 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3549 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3550 if (MemProfiling) MemProfiler::engage();
3551 StatSampler::engage();
3552 if (CheckJNICalls) JniPeriodicChecker::engage();
3554 BiasedLocking::init();
3556 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3557 call_postVMInitHook(THREAD);
3558 // The Java side of PostVMInitHook.run must deal with all
3559 // exceptions and provide means of diagnosis.
3560 if (HAS_PENDING_EXCEPTION) {
3561 CLEAR_PENDING_EXCEPTION;
3562 }
3563 }
3565 // Start up the WatcherThread if there are any periodic tasks
3566 // NOTE: All PeriodicTasks should be registered by now. If they
3567 // aren't, late joiners might appear to start slowly (we might
3568 // take a while to process their first tick).
3569 if (PeriodicTask::num_tasks() > 0) {
3570 WatcherThread::start();
3571 }
3573 // Give os specific code one last chance to start
3574 os::init_3();
3576 create_vm_timer.end();
3577 return JNI_OK;
3578 }
3580 // type for the Agent_OnLoad and JVM_OnLoad entry points
3581 extern "C" {
3582 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3583 }
3584 // Find a command line agent library and return its entry point for
3585 // -agentlib: -agentpath: -Xrun
3586 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3587 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3588 OnLoadEntry_t on_load_entry = NULL;
3589 void *library = agent->os_lib(); // check if we have looked it up before
3591 if (library == NULL) {
3592 char buffer[JVM_MAXPATHLEN];
3593 char ebuf[1024];
3594 const char *name = agent->name();
3595 const char *msg = "Could not find agent library ";
3597 if (agent->is_absolute_path()) {
3598 library = os::dll_load(name, ebuf, sizeof ebuf);
3599 if (library == NULL) {
3600 const char *sub_msg = " in absolute path, with error: ";
3601 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3602 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3603 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3604 // If we can't find the agent, exit.
3605 vm_exit_during_initialization(buf, NULL);
3606 FREE_C_HEAP_ARRAY(char, buf, mtThread);
3607 }
3608 } else {
3609 // Try to load the agent from the standard dll directory
3610 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3611 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3612 #ifdef KERNEL
3613 // Download instrument dll
3614 if (library == NULL && strcmp(name, "instrument") == 0) {
3615 char *props = Arguments::get_kernel_properties();
3616 char *home = Arguments::get_java_home();
3617 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3618 " sun.jkernel.DownloadManager -download client_jvm";
3619 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3620 char *cmd = NEW_C_HEAP_ARRAY(char, length, mtThread);
3621 jio_snprintf(cmd, length, fmt, home, props);
3622 int status = os::fork_and_exec(cmd);
3623 FreeHeap(props);
3624 if (status == -1) {
3625 warning(cmd);
3626 vm_exit_during_initialization("fork_and_exec failed: %s",
3627 strerror(errno));
3628 }
3629 FREE_C_HEAP_ARRAY(char, cmd, mtThread);
3630 // when this comes back the instrument.dll should be where it belongs.
3631 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3632 }
3633 #endif // KERNEL
3634 if (library == NULL) { // Try the local directory
3635 char ns[1] = {0};
3636 os::dll_build_name(buffer, sizeof(buffer), ns, name);
3637 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3638 if (library == NULL) {
3639 const char *sub_msg = " on the library path, with error: ";
3640 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3641 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3642 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3643 // If we can't find the agent, exit.
3644 vm_exit_during_initialization(buf, NULL);
3645 FREE_C_HEAP_ARRAY(char, buf, mtThread);
3646 }
3647 }
3648 }
3649 agent->set_os_lib(library);
3650 }
3652 // Find the OnLoad function.
3653 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3654 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3655 if (on_load_entry != NULL) break;
3656 }
3657 return on_load_entry;
3658 }
3660 // Find the JVM_OnLoad entry point
3661 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3662 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3663 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3664 }
3666 // Find the Agent_OnLoad entry point
3667 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3668 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3669 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3670 }
3672 // For backwards compatibility with -Xrun
3673 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3674 // treated like -agentpath:
3675 // Must be called before agent libraries are created
3676 void Threads::convert_vm_init_libraries_to_agents() {
3677 AgentLibrary* agent;
3678 AgentLibrary* next;
3680 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3681 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3682 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3684 // If there is an JVM_OnLoad function it will get called later,
3685 // otherwise see if there is an Agent_OnLoad
3686 if (on_load_entry == NULL) {
3687 on_load_entry = lookup_agent_on_load(agent);
3688 if (on_load_entry != NULL) {
3689 // switch it to the agent list -- so that Agent_OnLoad will be called,
3690 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3691 Arguments::convert_library_to_agent(agent);
3692 } else {
3693 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3694 }
3695 }
3696 }
3697 }
3699 // Create agents for -agentlib: -agentpath: and converted -Xrun
3700 // Invokes Agent_OnLoad
3701 // Called very early -- before JavaThreads exist
3702 void Threads::create_vm_init_agents() {
3703 extern struct JavaVM_ main_vm;
3704 AgentLibrary* agent;
3706 JvmtiExport::enter_onload_phase();
3707 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3708 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3710 if (on_load_entry != NULL) {
3711 // Invoke the Agent_OnLoad function
3712 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3713 if (err != JNI_OK) {
3714 vm_exit_during_initialization("agent library failed to init", agent->name());
3715 }
3716 } else {
3717 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3718 }
3719 }
3720 JvmtiExport::enter_primordial_phase();
3721 }
3723 extern "C" {
3724 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3725 }
3727 void Threads::shutdown_vm_agents() {
3728 // Send any Agent_OnUnload notifications
3729 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3730 extern struct JavaVM_ main_vm;
3731 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3733 // Find the Agent_OnUnload function.
3734 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3735 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3736 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3738 // Invoke the Agent_OnUnload function
3739 if (unload_entry != NULL) {
3740 JavaThread* thread = JavaThread::current();
3741 ThreadToNativeFromVM ttn(thread);
3742 HandleMark hm(thread);
3743 (*unload_entry)(&main_vm);
3744 break;
3745 }
3746 }
3747 }
3748 }
3750 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3751 // Invokes JVM_OnLoad
3752 void Threads::create_vm_init_libraries() {
3753 extern struct JavaVM_ main_vm;
3754 AgentLibrary* agent;
3756 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3757 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3759 if (on_load_entry != NULL) {
3760 // Invoke the JVM_OnLoad function
3761 JavaThread* thread = JavaThread::current();
3762 ThreadToNativeFromVM ttn(thread);
3763 HandleMark hm(thread);
3764 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3765 if (err != JNI_OK) {
3766 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3767 }
3768 } else {
3769 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3770 }
3771 }
3772 }
3774 // Last thread running calls java.lang.Shutdown.shutdown()
3775 void JavaThread::invoke_shutdown_hooks() {
3776 HandleMark hm(this);
3778 // We could get here with a pending exception, if so clear it now.
3779 if (this->has_pending_exception()) {
3780 this->clear_pending_exception();
3781 }
3783 EXCEPTION_MARK;
3784 klassOop k =
3785 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3786 THREAD);
3787 if (k != NULL) {
3788 // SystemDictionary::resolve_or_null will return null if there was
3789 // an exception. If we cannot load the Shutdown class, just don't
3790 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3791 // and finalizers (if runFinalizersOnExit is set) won't be run.
3792 // Note that if a shutdown hook was registered or runFinalizersOnExit
3793 // was called, the Shutdown class would have already been loaded
3794 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3795 instanceKlassHandle shutdown_klass (THREAD, k);
3796 JavaValue result(T_VOID);
3797 JavaCalls::call_static(&result,
3798 shutdown_klass,
3799 vmSymbols::shutdown_method_name(),
3800 vmSymbols::void_method_signature(),
3801 THREAD);
3802 }
3803 CLEAR_PENDING_EXCEPTION;
3804 }
3806 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3807 // the program falls off the end of main(). Another VM exit path is through
3808 // vm_exit() when the program calls System.exit() to return a value or when
3809 // there is a serious error in VM. The two shutdown paths are not exactly
3810 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3811 // and VM_Exit op at VM level.
3812 //
3813 // Shutdown sequence:
3814 // + Shutdown native memory tracking if it is on
3815 // + Wait until we are the last non-daemon thread to execute
3816 // <-- every thing is still working at this moment -->
3817 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3818 // shutdown hooks, run finalizers if finalization-on-exit
3819 // + Call before_exit(), prepare for VM exit
3820 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3821 // currently the only user of this mechanism is File.deleteOnExit())
3822 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3823 // post thread end and vm death events to JVMTI,
3824 // stop signal thread
3825 // + Call JavaThread::exit(), it will:
3826 // > release JNI handle blocks, remove stack guard pages
3827 // > remove this thread from Threads list
3828 // <-- no more Java code from this thread after this point -->
3829 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3830 // the compiler threads at safepoint
3831 // <-- do not use anything that could get blocked by Safepoint -->
3832 // + Disable tracing at JNI/JVM barriers
3833 // + Set _vm_exited flag for threads that are still running native code
3834 // + Delete this thread
3835 // + Call exit_globals()
3836 // > deletes tty
3837 // > deletes PerfMemory resources
3838 // + Return to caller
3840 bool Threads::destroy_vm() {
3841 JavaThread* thread = JavaThread::current();
3843 // Wait until we are the last non-daemon thread to execute
3844 { MutexLocker nu(Threads_lock);
3845 while (Threads::number_of_non_daemon_threads() > 1 )
3846 // This wait should make safepoint checks, wait without a timeout,
3847 // and wait as a suspend-equivalent condition.
3848 //
3849 // Note: If the FlatProfiler is running and this thread is waiting
3850 // for another non-daemon thread to finish, then the FlatProfiler
3851 // is waiting for the external suspend request on this thread to
3852 // complete. wait_for_ext_suspend_completion() will eventually
3853 // timeout, but that takes time. Making this wait a suspend-
3854 // equivalent condition solves that timeout problem.
3855 //
3856 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3857 Mutex::_as_suspend_equivalent_flag);
3858 }
3860 // Shutdown NMT before exit. Otherwise,
3861 // it will run into trouble when system destroys static variables.
3862 MemTracker::shutdown(MemTracker::NMT_normal);
3864 // Hang forever on exit if we are reporting an error.
3865 if (ShowMessageBoxOnError && is_error_reported()) {
3866 os::infinite_sleep();
3867 }
3868 os::wait_for_keypress_at_exit();
3870 if (JDK_Version::is_jdk12x_version()) {
3871 // We are the last thread running, so check if finalizers should be run.
3872 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3873 HandleMark rm(thread);
3874 Universe::run_finalizers_on_exit();
3875 } else {
3876 // run Java level shutdown hooks
3877 thread->invoke_shutdown_hooks();
3878 }
3880 before_exit(thread);
3882 thread->exit(true);
3884 // Stop VM thread.
3885 {
3886 // 4945125 The vm thread comes to a safepoint during exit.
3887 // GC vm_operations can get caught at the safepoint, and the
3888 // heap is unparseable if they are caught. Grab the Heap_lock
3889 // to prevent this. The GC vm_operations will not be able to
3890 // queue until after the vm thread is dead.
3891 // After this point, we'll never emerge out of the safepoint before
3892 // the VM exits, so concurrent GC threads do not need to be explicitly
3893 // stopped; they remain inactive until the process exits.
3894 // Note: some concurrent G1 threads may be running during a safepoint,
3895 // but these will not be accessing the heap, just some G1-specific side
3896 // data structures that are not accessed by any other threads but them
3897 // after this point in a terminal safepoint.
3899 MutexLocker ml(Heap_lock);
3901 VMThread::wait_for_vm_thread_exit();
3902 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3903 VMThread::destroy();
3904 }
3906 // clean up ideal graph printers
3907 #if defined(COMPILER2) && !defined(PRODUCT)
3908 IdealGraphPrinter::clean_up();
3909 #endif
3911 // Now, all Java threads are gone except daemon threads. Daemon threads
3912 // running Java code or in VM are stopped by the Safepoint. However,
3913 // daemon threads executing native code are still running. But they
3914 // will be stopped at native=>Java/VM barriers. Note that we can't
3915 // simply kill or suspend them, as it is inherently deadlock-prone.
3917 #ifndef PRODUCT
3918 // disable function tracing at JNI/JVM barriers
3919 TraceJNICalls = false;
3920 TraceJVMCalls = false;
3921 TraceRuntimeCalls = false;
3922 #endif
3924 VM_Exit::set_vm_exited();
3926 notify_vm_shutdown();
3928 delete thread;
3930 // exit_globals() will delete tty
3931 exit_globals();
3933 return true;
3934 }
3937 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3938 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3939 return is_supported_jni_version(version);
3940 }
3943 jboolean Threads::is_supported_jni_version(jint version) {
3944 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3945 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3946 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3947 return JNI_FALSE;
3948 }
3951 void Threads::add(JavaThread* p, bool force_daemon) {
3952 // The threads lock must be owned at this point
3953 assert_locked_or_safepoint(Threads_lock);
3955 // See the comment for this method in thread.hpp for its purpose and
3956 // why it is called here.
3957 p->initialize_queues();
3958 p->set_next(_thread_list);
3959 _thread_list = p;
3960 _number_of_threads++;
3961 oop threadObj = p->threadObj();
3962 bool daemon = true;
3963 // Bootstrapping problem: threadObj can be null for initial
3964 // JavaThread (or for threads attached via JNI)
3965 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3966 _number_of_non_daemon_threads++;
3967 daemon = false;
3968 }
3970 p->set_safepoint_visible(true);
3972 ThreadService::add_thread(p, daemon);
3974 // Possible GC point.
3975 Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3976 }
3978 void Threads::remove(JavaThread* p) {
3979 // Extra scope needed for Thread_lock, so we can check
3980 // that we do not remove thread without safepoint code notice
3981 { MutexLocker ml(Threads_lock);
3983 assert(includes(p), "p must be present");
3985 JavaThread* current = _thread_list;
3986 JavaThread* prev = NULL;
3988 while (current != p) {
3989 prev = current;
3990 current = current->next();
3991 }
3993 if (prev) {
3994 prev->set_next(current->next());
3995 } else {
3996 _thread_list = p->next();
3997 }
3998 _number_of_threads--;
3999 oop threadObj = p->threadObj();
4000 bool daemon = true;
4001 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4002 _number_of_non_daemon_threads--;
4003 daemon = false;
4005 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4006 // on destroy_vm will wake up.
4007 if (number_of_non_daemon_threads() == 1)
4008 Threads_lock->notify_all();
4009 }
4010 ThreadService::remove_thread(p, daemon);
4012 // Make sure that safepoint code disregard this thread. This is needed since
4013 // the thread might mess around with locks after this point. This can cause it
4014 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4015 // of this thread since it is removed from the queue.
4016 p->set_terminated_value();
4018 // Now, this thread is not visible to safepoint
4019 p->set_safepoint_visible(false);
4021 } // unlock Threads_lock
4023 // Since Events::log uses a lock, we grab it outside the Threads_lock
4024 Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4025 }
4027 // Threads_lock must be held when this is called (or must be called during a safepoint)
4028 bool Threads::includes(JavaThread* p) {
4029 assert(Threads_lock->is_locked(), "sanity check");
4030 ALL_JAVA_THREADS(q) {
4031 if (q == p ) {
4032 return true;
4033 }
4034 }
4035 return false;
4036 }
4038 // Operations on the Threads list for GC. These are not explicitly locked,
4039 // but the garbage collector must provide a safe context for them to run.
4040 // In particular, these things should never be called when the Threads_lock
4041 // is held by some other thread. (Note: the Safepoint abstraction also
4042 // uses the Threads_lock to gurantee this property. It also makes sure that
4043 // all threads gets blocked when exiting or starting).
4045 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4046 ALL_JAVA_THREADS(p) {
4047 p->oops_do(f, cf);
4048 }
4049 VMThread::vm_thread()->oops_do(f, cf);
4050 }
4052 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
4053 // Introduce a mechanism allowing parallel threads to claim threads as
4054 // root groups. Overhead should be small enough to use all the time,
4055 // even in sequential code.
4056 SharedHeap* sh = SharedHeap::heap();
4057 // Cannot yet substitute active_workers for n_par_threads
4058 // because of G1CollectedHeap::verify() use of
4059 // SharedHeap::process_strong_roots(). n_par_threads == 0 will
4060 // turn off parallelism in process_strong_roots while active_workers
4061 // is being used for parallelism elsewhere.
4062 bool is_par = sh->n_par_threads() > 0;
4063 assert(!is_par ||
4064 (SharedHeap::heap()->n_par_threads() ==
4065 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
4066 int cp = SharedHeap::heap()->strong_roots_parity();
4067 ALL_JAVA_THREADS(p) {
4068 if (p->claim_oops_do(is_par, cp)) {
4069 p->oops_do(f, cf);
4070 }
4071 }
4072 VMThread* vmt = VMThread::vm_thread();
4073 if (vmt->claim_oops_do(is_par, cp)) {
4074 vmt->oops_do(f, cf);
4075 }
4076 }
4078 #ifndef SERIALGC
4079 // Used by ParallelScavenge
4080 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4081 ALL_JAVA_THREADS(p) {
4082 q->enqueue(new ThreadRootsTask(p));
4083 }
4084 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4085 }
4087 // Used by Parallel Old
4088 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4089 ALL_JAVA_THREADS(p) {
4090 q->enqueue(new ThreadRootsMarkingTask(p));
4091 }
4092 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4093 }
4094 #endif // SERIALGC
4096 void Threads::nmethods_do(CodeBlobClosure* cf) {
4097 ALL_JAVA_THREADS(p) {
4098 p->nmethods_do(cf);
4099 }
4100 VMThread::vm_thread()->nmethods_do(cf);
4101 }
4103 void Threads::gc_epilogue() {
4104 ALL_JAVA_THREADS(p) {
4105 p->gc_epilogue();
4106 }
4107 }
4109 void Threads::gc_prologue() {
4110 ALL_JAVA_THREADS(p) {
4111 p->gc_prologue();
4112 }
4113 }
4115 void Threads::deoptimized_wrt_marked_nmethods() {
4116 ALL_JAVA_THREADS(p) {
4117 p->deoptimized_wrt_marked_nmethods();
4118 }
4119 }
4122 // Get count Java threads that are waiting to enter the specified monitor.
4123 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4124 address monitor, bool doLock) {
4125 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4126 "must grab Threads_lock or be at safepoint");
4127 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4129 int i = 0;
4130 {
4131 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4132 ALL_JAVA_THREADS(p) {
4133 if (p->is_Compiler_thread()) continue;
4135 address pending = (address)p->current_pending_monitor();
4136 if (pending == monitor) { // found a match
4137 if (i < count) result->append(p); // save the first count matches
4138 i++;
4139 }
4140 }
4141 }
4142 return result;
4143 }
4146 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
4147 assert(doLock ||
4148 Threads_lock->owned_by_self() ||
4149 SafepointSynchronize::is_at_safepoint(),
4150 "must grab Threads_lock or be at safepoint");
4152 // NULL owner means not locked so we can skip the search
4153 if (owner == NULL) return NULL;
4155 {
4156 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4157 ALL_JAVA_THREADS(p) {
4158 // first, see if owner is the address of a Java thread
4159 if (owner == (address)p) return p;
4160 }
4161 }
4162 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
4163 if (UseHeavyMonitors) return NULL;
4165 //
4166 // If we didn't find a matching Java thread and we didn't force use of
4167 // heavyweight monitors, then the owner is the stack address of the
4168 // Lock Word in the owning Java thread's stack.
4169 //
4170 JavaThread* the_owner = NULL;
4171 {
4172 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4173 ALL_JAVA_THREADS(q) {
4174 if (q->is_lock_owned(owner)) {
4175 the_owner = q;
4176 break;
4177 }
4178 }
4179 }
4180 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
4181 return the_owner;
4182 }
4184 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4185 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
4186 char buf[32];
4187 st->print_cr(os::local_time_string(buf, sizeof(buf)));
4189 st->print_cr("Full thread dump %s (%s %s):",
4190 Abstract_VM_Version::vm_name(),
4191 Abstract_VM_Version::vm_release(),
4192 Abstract_VM_Version::vm_info_string()
4193 );
4194 st->cr();
4196 #ifndef SERIALGC
4197 // Dump concurrent locks
4198 ConcurrentLocksDump concurrent_locks;
4199 if (print_concurrent_locks) {
4200 concurrent_locks.dump_at_safepoint();
4201 }
4202 #endif // SERIALGC
4204 ALL_JAVA_THREADS(p) {
4205 ResourceMark rm;
4206 p->print_on(st);
4207 if (print_stacks) {
4208 if (internal_format) {
4209 p->trace_stack();
4210 } else {
4211 p->print_stack_on(st);
4212 }
4213 }
4214 st->cr();
4215 #ifndef SERIALGC
4216 if (print_concurrent_locks) {
4217 concurrent_locks.print_locks_on(p, st);
4218 }
4219 #endif // SERIALGC
4220 }
4222 VMThread::vm_thread()->print_on(st);
4223 st->cr();
4224 Universe::heap()->print_gc_threads_on(st);
4225 WatcherThread* wt = WatcherThread::watcher_thread();
4226 if (wt != NULL) wt->print_on(st);
4227 st->cr();
4228 CompileBroker::print_compiler_threads_on(st);
4229 st->flush();
4230 }
4232 // Threads::print_on_error() is called by fatal error handler. It's possible
4233 // that VM is not at safepoint and/or current thread is inside signal handler.
4234 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4235 // memory (even in resource area), it might deadlock the error handler.
4236 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4237 bool found_current = false;
4238 st->print_cr("Java Threads: ( => current thread )");
4239 ALL_JAVA_THREADS(thread) {
4240 bool is_current = (current == thread);
4241 found_current = found_current || is_current;
4243 st->print("%s", is_current ? "=>" : " ");
4245 st->print(PTR_FORMAT, thread);
4246 st->print(" ");
4247 thread->print_on_error(st, buf, buflen);
4248 st->cr();
4249 }
4250 st->cr();
4252 st->print_cr("Other Threads:");
4253 if (VMThread::vm_thread()) {
4254 bool is_current = (current == VMThread::vm_thread());
4255 found_current = found_current || is_current;
4256 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4258 st->print(PTR_FORMAT, VMThread::vm_thread());
4259 st->print(" ");
4260 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4261 st->cr();
4262 }
4263 WatcherThread* wt = WatcherThread::watcher_thread();
4264 if (wt != NULL) {
4265 bool is_current = (current == wt);
4266 found_current = found_current || is_current;
4267 st->print("%s", is_current ? "=>" : " ");
4269 st->print(PTR_FORMAT, wt);
4270 st->print(" ");
4271 wt->print_on_error(st, buf, buflen);
4272 st->cr();
4273 }
4274 if (!found_current) {
4275 st->cr();
4276 st->print("=>" PTR_FORMAT " (exited) ", current);
4277 current->print_on_error(st, buf, buflen);
4278 st->cr();
4279 }
4280 }
4282 // Internal SpinLock and Mutex
4283 // Based on ParkEvent
4285 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4286 //
4287 // We employ SpinLocks _only for low-contention, fixed-length
4288 // short-duration critical sections where we're concerned
4289 // about native mutex_t or HotSpot Mutex:: latency.
4290 // The mux construct provides a spin-then-block mutual exclusion
4291 // mechanism.
4292 //
4293 // Testing has shown that contention on the ListLock guarding gFreeList
4294 // is common. If we implement ListLock as a simple SpinLock it's common
4295 // for the JVM to devolve to yielding with little progress. This is true
4296 // despite the fact that the critical sections protected by ListLock are
4297 // extremely short.
4298 //
4299 // TODO-FIXME: ListLock should be of type SpinLock.
4300 // We should make this a 1st-class type, integrated into the lock
4301 // hierarchy as leaf-locks. Critically, the SpinLock structure
4302 // should have sufficient padding to avoid false-sharing and excessive
4303 // cache-coherency traffic.
4306 typedef volatile int SpinLockT ;
4308 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4309 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4310 return ; // normal fast-path return
4311 }
4313 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4314 TEVENT (SpinAcquire - ctx) ;
4315 int ctr = 0 ;
4316 int Yields = 0 ;
4317 for (;;) {
4318 while (*adr != 0) {
4319 ++ctr ;
4320 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4321 if (Yields > 5) {
4322 // Consider using a simple NakedSleep() instead.
4323 // Then SpinAcquire could be called by non-JVM threads
4324 Thread::current()->_ParkEvent->park(1) ;
4325 } else {
4326 os::NakedYield() ;
4327 ++Yields ;
4328 }
4329 } else {
4330 SpinPause() ;
4331 }
4332 }
4333 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4334 }
4335 }
4337 void Thread::SpinRelease (volatile int * adr) {
4338 assert (*adr != 0, "invariant") ;
4339 OrderAccess::fence() ; // guarantee at least release consistency.
4340 // Roach-motel semantics.
4341 // It's safe if subsequent LDs and STs float "up" into the critical section,
4342 // but prior LDs and STs within the critical section can't be allowed
4343 // to reorder or float past the ST that releases the lock.
4344 *adr = 0 ;
4345 }
4347 // muxAcquire and muxRelease:
4348 //
4349 // * muxAcquire and muxRelease support a single-word lock-word construct.
4350 // The LSB of the word is set IFF the lock is held.
4351 // The remainder of the word points to the head of a singly-linked list
4352 // of threads blocked on the lock.
4353 //
4354 // * The current implementation of muxAcquire-muxRelease uses its own
4355 // dedicated Thread._MuxEvent instance. If we're interested in
4356 // minimizing the peak number of extant ParkEvent instances then
4357 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4358 // as certain invariants were satisfied. Specifically, care would need
4359 // to be taken with regards to consuming unpark() "permits".
4360 // A safe rule of thumb is that a thread would never call muxAcquire()
4361 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4362 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4363 // consume an unpark() permit intended for monitorenter, for instance.
4364 // One way around this would be to widen the restricted-range semaphore
4365 // implemented in park(). Another alternative would be to provide
4366 // multiple instances of the PlatformEvent() for each thread. One
4367 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4368 //
4369 // * Usage:
4370 // -- Only as leaf locks
4371 // -- for short-term locking only as muxAcquire does not perform
4372 // thread state transitions.
4373 //
4374 // Alternatives:
4375 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4376 // but with parking or spin-then-park instead of pure spinning.
4377 // * Use Taura-Oyama-Yonenzawa locks.
4378 // * It's possible to construct a 1-0 lock if we encode the lockword as
4379 // (List,LockByte). Acquire will CAS the full lockword while Release
4380 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4381 // acquiring threads use timers (ParkTimed) to detect and recover from
4382 // the stranding window. Thread/Node structures must be aligned on 256-byte
4383 // boundaries by using placement-new.
4384 // * Augment MCS with advisory back-link fields maintained with CAS().
4385 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4386 // The validity of the backlinks must be ratified before we trust the value.
4387 // If the backlinks are invalid the exiting thread must back-track through the
4388 // the forward links, which are always trustworthy.
4389 // * Add a successor indication. The LockWord is currently encoded as
4390 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4391 // to provide the usual futile-wakeup optimization.
4392 // See RTStt for details.
4393 // * Consider schedctl.sc_nopreempt to cover the critical section.
4394 //
4397 typedef volatile intptr_t MutexT ; // Mux Lock-word
4398 enum MuxBits { LOCKBIT = 1 } ;
4400 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4401 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4402 if (w == 0) return ;
4403 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4404 return ;
4405 }
4407 TEVENT (muxAcquire - Contention) ;
4408 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4409 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4410 for (;;) {
4411 int its = (os::is_MP() ? 100 : 0) + 1 ;
4413 // Optional spin phase: spin-then-park strategy
4414 while (--its >= 0) {
4415 w = *Lock ;
4416 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4417 return ;
4418 }
4419 }
4421 Self->reset() ;
4422 Self->OnList = intptr_t(Lock) ;
4423 // The following fence() isn't _strictly necessary as the subsequent
4424 // CAS() both serializes execution and ratifies the fetched *Lock value.
4425 OrderAccess::fence();
4426 for (;;) {
4427 w = *Lock ;
4428 if ((w & LOCKBIT) == 0) {
4429 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4430 Self->OnList = 0 ; // hygiene - allows stronger asserts
4431 return ;
4432 }
4433 continue ; // Interference -- *Lock changed -- Just retry
4434 }
4435 assert (w & LOCKBIT, "invariant") ;
4436 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4437 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4438 }
4440 while (Self->OnList != 0) {
4441 Self->park() ;
4442 }
4443 }
4444 }
4446 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4447 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4448 if (w == 0) return ;
4449 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4450 return ;
4451 }
4453 TEVENT (muxAcquire - Contention) ;
4454 ParkEvent * ReleaseAfter = NULL ;
4455 if (ev == NULL) {
4456 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4457 }
4458 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4459 for (;;) {
4460 guarantee (ev->OnList == 0, "invariant") ;
4461 int its = (os::is_MP() ? 100 : 0) + 1 ;
4463 // Optional spin phase: spin-then-park strategy
4464 while (--its >= 0) {
4465 w = *Lock ;
4466 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4467 if (ReleaseAfter != NULL) {
4468 ParkEvent::Release (ReleaseAfter) ;
4469 }
4470 return ;
4471 }
4472 }
4474 ev->reset() ;
4475 ev->OnList = intptr_t(Lock) ;
4476 // The following fence() isn't _strictly necessary as the subsequent
4477 // CAS() both serializes execution and ratifies the fetched *Lock value.
4478 OrderAccess::fence();
4479 for (;;) {
4480 w = *Lock ;
4481 if ((w & LOCKBIT) == 0) {
4482 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4483 ev->OnList = 0 ;
4484 // We call ::Release while holding the outer lock, thus
4485 // artificially lengthening the critical section.
4486 // Consider deferring the ::Release() until the subsequent unlock(),
4487 // after we've dropped the outer lock.
4488 if (ReleaseAfter != NULL) {
4489 ParkEvent::Release (ReleaseAfter) ;
4490 }
4491 return ;
4492 }
4493 continue ; // Interference -- *Lock changed -- Just retry
4494 }
4495 assert (w & LOCKBIT, "invariant") ;
4496 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4497 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4498 }
4500 while (ev->OnList != 0) {
4501 ev->park() ;
4502 }
4503 }
4504 }
4506 // Release() must extract a successor from the list and then wake that thread.
4507 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4508 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4509 // Release() would :
4510 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4511 // (B) Extract a successor from the private list "in-hand"
4512 // (C) attempt to CAS() the residual back into *Lock over null.
4513 // If there were any newly arrived threads and the CAS() would fail.
4514 // In that case Release() would detach the RATs, re-merge the list in-hand
4515 // with the RATs and repeat as needed. Alternately, Release() might
4516 // detach and extract a successor, but then pass the residual list to the wakee.
4517 // The wakee would be responsible for reattaching and remerging before it
4518 // competed for the lock.
4519 //
4520 // Both "pop" and DMR are immune from ABA corruption -- there can be
4521 // multiple concurrent pushers, but only one popper or detacher.
4522 // This implementation pops from the head of the list. This is unfair,
4523 // but tends to provide excellent throughput as hot threads remain hot.
4524 // (We wake recently run threads first).
4526 void Thread::muxRelease (volatile intptr_t * Lock) {
4527 for (;;) {
4528 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4529 assert (w & LOCKBIT, "invariant") ;
4530 if (w == LOCKBIT) return ;
4531 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4532 assert (List != NULL, "invariant") ;
4533 assert (List->OnList == intptr_t(Lock), "invariant") ;
4534 ParkEvent * nxt = List->ListNext ;
4536 // The following CAS() releases the lock and pops the head element.
4537 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4538 continue ;
4539 }
4540 List->OnList = 0 ;
4541 OrderAccess::fence() ;
4542 List->unpark () ;
4543 return ;
4544 }
4545 }
4548 void Threads::verify() {
4549 ALL_JAVA_THREADS(p) {
4550 p->verify();
4551 }
4552 VMThread* thread = VMThread::vm_thread();
4553 if (thread != NULL) thread->verify();
4554 }