Wed, 12 Jan 2011 15:44:16 +0000
6994753: Implement optional hook to a Java method at VM startup.
Reviewed-by: mchung, acorn
1 /*
2 * Copyright (c) 1997, 2011, 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 "jvmtifiles/jvmtiEnv.hpp"
35 #include "memory/oopFactory.hpp"
36 #include "memory/universe.inline.hpp"
37 #include "oops/instanceKlass.hpp"
38 #include "oops/objArrayOop.hpp"
39 #include "oops/oop.inline.hpp"
40 #include "oops/symbolOop.hpp"
41 #include "prims/jvm_misc.hpp"
42 #include "prims/jvmtiExport.hpp"
43 #include "prims/jvmtiThreadState.hpp"
44 #include "prims/privilegedStack.hpp"
45 #include "runtime/aprofiler.hpp"
46 #include "runtime/arguments.hpp"
47 #include "runtime/biasedLocking.hpp"
48 #include "runtime/deoptimization.hpp"
49 #include "runtime/fprofiler.hpp"
50 #include "runtime/frame.inline.hpp"
51 #include "runtime/init.hpp"
52 #include "runtime/interfaceSupport.hpp"
53 #include "runtime/java.hpp"
54 #include "runtime/javaCalls.hpp"
55 #include "runtime/jniPeriodicChecker.hpp"
56 #include "runtime/memprofiler.hpp"
57 #include "runtime/mutexLocker.hpp"
58 #include "runtime/objectMonitor.hpp"
59 #include "runtime/osThread.hpp"
60 #include "runtime/safepoint.hpp"
61 #include "runtime/sharedRuntime.hpp"
62 #include "runtime/statSampler.hpp"
63 #include "runtime/stubRoutines.hpp"
64 #include "runtime/task.hpp"
65 #include "runtime/threadCritical.hpp"
66 #include "runtime/threadLocalStorage.hpp"
67 #include "runtime/vframe.hpp"
68 #include "runtime/vframeArray.hpp"
69 #include "runtime/vframe_hp.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "runtime/vm_operations.hpp"
72 #include "services/attachListener.hpp"
73 #include "services/management.hpp"
74 #include "services/threadService.hpp"
75 #include "utilities/defaultStream.hpp"
76 #include "utilities/dtrace.hpp"
77 #include "utilities/events.hpp"
78 #include "utilities/preserveException.hpp"
79 #ifdef TARGET_OS_FAMILY_linux
80 # include "os_linux.inline.hpp"
81 # include "thread_linux.inline.hpp"
82 #endif
83 #ifdef TARGET_OS_FAMILY_solaris
84 # include "os_solaris.inline.hpp"
85 # include "thread_solaris.inline.hpp"
86 #endif
87 #ifdef TARGET_OS_FAMILY_windows
88 # include "os_windows.inline.hpp"
89 # include "thread_windows.inline.hpp"
90 #endif
91 #ifndef SERIALGC
92 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
93 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
94 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
95 #endif
96 #ifdef COMPILER1
97 #include "c1/c1_Compiler.hpp"
98 #endif
99 #ifdef COMPILER2
100 #include "opto/c2compiler.hpp"
101 #include "opto/idealGraphPrinter.hpp"
102 #endif
104 #ifdef DTRACE_ENABLED
106 // Only bother with this argument setup if dtrace is available
108 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
109 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
110 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
111 intptr_t, intptr_t, bool);
112 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
113 intptr_t, intptr_t, bool);
115 #define DTRACE_THREAD_PROBE(probe, javathread) \
116 { \
117 ResourceMark rm(this); \
118 int len = 0; \
119 const char* name = (javathread)->get_thread_name(); \
120 len = strlen(name); \
121 HS_DTRACE_PROBE5(hotspot, thread__##probe, \
122 name, len, \
123 java_lang_Thread::thread_id((javathread)->threadObj()), \
124 (javathread)->osthread()->thread_id(), \
125 java_lang_Thread::is_daemon((javathread)->threadObj())); \
126 }
128 #else // ndef DTRACE_ENABLED
130 #define DTRACE_THREAD_PROBE(probe, javathread)
132 #endif // ndef DTRACE_ENABLED
134 // Class hierarchy
135 // - Thread
136 // - VMThread
137 // - WatcherThread
138 // - ConcurrentMarkSweepThread
139 // - JavaThread
140 // - CompilerThread
142 // ======= Thread ========
144 // Support for forcing alignment of thread objects for biased locking
145 void* Thread::operator new(size_t size) {
146 if (UseBiasedLocking) {
147 const int alignment = markOopDesc::biased_lock_alignment;
148 size_t aligned_size = size + (alignment - sizeof(intptr_t));
149 void* real_malloc_addr = CHeapObj::operator new(aligned_size);
150 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
151 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
152 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
153 "JavaThread alignment code overflowed allocated storage");
154 if (TraceBiasedLocking) {
155 if (aligned_addr != real_malloc_addr)
156 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
157 real_malloc_addr, aligned_addr);
158 }
159 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
160 return aligned_addr;
161 } else {
162 return CHeapObj::operator new(size);
163 }
164 }
166 void Thread::operator delete(void* p) {
167 if (UseBiasedLocking) {
168 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
169 CHeapObj::operator delete(real_malloc_addr);
170 } else {
171 CHeapObj::operator delete(p);
172 }
173 }
176 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
177 // JavaThread
180 Thread::Thread() {
181 // stack and get_thread
182 set_stack_base(NULL);
183 set_stack_size(0);
184 set_self_raw_id(0);
185 set_lgrp_id(-1);
187 // allocated data structures
188 set_osthread(NULL);
189 set_resource_area(new ResourceArea());
190 set_handle_area(new HandleArea(NULL));
191 set_active_handles(NULL);
192 set_free_handle_block(NULL);
193 set_last_handle_mark(NULL);
195 // This initial value ==> never claimed.
196 _oops_do_parity = 0;
198 // the handle mark links itself to last_handle_mark
199 new HandleMark(this);
201 // plain initialization
202 debug_only(_owned_locks = NULL;)
203 debug_only(_allow_allocation_count = 0;)
204 NOT_PRODUCT(_allow_safepoint_count = 0;)
205 NOT_PRODUCT(_skip_gcalot = false;)
206 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
207 _jvmti_env_iteration_count = 0;
208 set_allocated_bytes(0);
209 _vm_operation_started_count = 0;
210 _vm_operation_completed_count = 0;
211 _current_pending_monitor = NULL;
212 _current_pending_monitor_is_from_java = true;
213 _current_waiting_monitor = NULL;
214 _num_nested_signal = 0;
215 omFreeList = NULL ;
216 omFreeCount = 0 ;
217 omFreeProvision = 32 ;
218 omInUseList = NULL ;
219 omInUseCount = 0 ;
221 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
222 _suspend_flags = 0;
224 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
225 _hashStateX = os::random() ;
226 _hashStateY = 842502087 ;
227 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
228 _hashStateW = 273326509 ;
230 _OnTrap = 0 ;
231 _schedctl = NULL ;
232 _Stalled = 0 ;
233 _TypeTag = 0x2BAD ;
235 // Many of the following fields are effectively final - immutable
236 // Note that nascent threads can't use the Native Monitor-Mutex
237 // construct until the _MutexEvent is initialized ...
238 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
239 // we might instead use a stack of ParkEvents that we could provision on-demand.
240 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
241 // and ::Release()
242 _ParkEvent = ParkEvent::Allocate (this) ;
243 _SleepEvent = ParkEvent::Allocate (this) ;
244 _MutexEvent = ParkEvent::Allocate (this) ;
245 _MuxEvent = ParkEvent::Allocate (this) ;
247 #ifdef CHECK_UNHANDLED_OOPS
248 if (CheckUnhandledOops) {
249 _unhandled_oops = new UnhandledOops(this);
250 }
251 #endif // CHECK_UNHANDLED_OOPS
252 #ifdef ASSERT
253 if (UseBiasedLocking) {
254 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
255 assert(this == _real_malloc_address ||
256 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
257 "bug in forced alignment of thread objects");
258 }
259 #endif /* ASSERT */
260 }
262 void Thread::initialize_thread_local_storage() {
263 // Note: Make sure this method only calls
264 // non-blocking operations. Otherwise, it might not work
265 // with the thread-startup/safepoint interaction.
267 // During Java thread startup, safepoint code should allow this
268 // method to complete because it may need to allocate memory to
269 // store information for the new thread.
271 // initialize structure dependent on thread local storage
272 ThreadLocalStorage::set_thread(this);
274 // set up any platform-specific state.
275 os::initialize_thread();
277 }
279 void Thread::record_stack_base_and_size() {
280 set_stack_base(os::current_stack_base());
281 set_stack_size(os::current_stack_size());
282 }
285 Thread::~Thread() {
286 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
287 ObjectSynchronizer::omFlush (this) ;
289 // deallocate data structures
290 delete resource_area();
291 // since the handle marks are using the handle area, we have to deallocated the root
292 // handle mark before deallocating the thread's handle area,
293 assert(last_handle_mark() != NULL, "check we have an element");
294 delete last_handle_mark();
295 assert(last_handle_mark() == NULL, "check we have reached the end");
297 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
298 // We NULL out the fields for good hygiene.
299 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
300 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
301 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
302 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
304 delete handle_area();
306 // osthread() can be NULL, if creation of thread failed.
307 if (osthread() != NULL) os::free_thread(osthread());
309 delete _SR_lock;
311 // clear thread local storage if the Thread is deleting itself
312 if (this == Thread::current()) {
313 ThreadLocalStorage::set_thread(NULL);
314 } else {
315 // In the case where we're not the current thread, invalidate all the
316 // caches in case some code tries to get the current thread or the
317 // thread that was destroyed, and gets stale information.
318 ThreadLocalStorage::invalidate_all();
319 }
320 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
321 }
323 // NOTE: dummy function for assertion purpose.
324 void Thread::run() {
325 ShouldNotReachHere();
326 }
328 #ifdef ASSERT
329 // Private method to check for dangling thread pointer
330 void check_for_dangling_thread_pointer(Thread *thread) {
331 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
332 "possibility of dangling Thread pointer");
333 }
334 #endif
337 #ifndef PRODUCT
338 // Tracing method for basic thread operations
339 void Thread::trace(const char* msg, const Thread* const thread) {
340 if (!TraceThreadEvents) return;
341 ResourceMark rm;
342 ThreadCritical tc;
343 const char *name = "non-Java thread";
344 int prio = -1;
345 if (thread->is_Java_thread()
346 && !thread->is_Compiler_thread()) {
347 // The Threads_lock must be held to get information about
348 // this thread but may not be in some situations when
349 // tracing thread events.
350 bool release_Threads_lock = false;
351 if (!Threads_lock->owned_by_self()) {
352 Threads_lock->lock();
353 release_Threads_lock = true;
354 }
355 JavaThread* jt = (JavaThread *)thread;
356 name = (char *)jt->get_thread_name();
357 oop thread_oop = jt->threadObj();
358 if (thread_oop != NULL) {
359 prio = java_lang_Thread::priority(thread_oop);
360 }
361 if (release_Threads_lock) {
362 Threads_lock->unlock();
363 }
364 }
365 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
366 }
367 #endif
370 ThreadPriority Thread::get_priority(const Thread* const thread) {
371 trace("get priority", thread);
372 ThreadPriority priority;
373 // Can return an error!
374 (void)os::get_priority(thread, priority);
375 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
376 return priority;
377 }
379 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
380 trace("set priority", thread);
381 debug_only(check_for_dangling_thread_pointer(thread);)
382 // Can return an error!
383 (void)os::set_priority(thread, priority);
384 }
387 void Thread::start(Thread* thread) {
388 trace("start", thread);
389 // Start is different from resume in that its safety is guaranteed by context or
390 // being called from a Java method synchronized on the Thread object.
391 if (!DisableStartThread) {
392 if (thread->is_Java_thread()) {
393 // Initialize the thread state to RUNNABLE before starting this thread.
394 // Can not set it after the thread started because we do not know the
395 // exact thread state at that time. It could be in MONITOR_WAIT or
396 // in SLEEPING or some other state.
397 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
398 java_lang_Thread::RUNNABLE);
399 }
400 os::start_thread(thread);
401 }
402 }
404 // Enqueue a VM_Operation to do the job for us - sometime later
405 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
406 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
407 VMThread::execute(vm_stop);
408 }
411 //
412 // Check if an external suspend request has completed (or has been
413 // cancelled). Returns true if the thread is externally suspended and
414 // false otherwise.
415 //
416 // The bits parameter returns information about the code path through
417 // the routine. Useful for debugging:
418 //
419 // set in is_ext_suspend_completed():
420 // 0x00000001 - routine was entered
421 // 0x00000010 - routine return false at end
422 // 0x00000100 - thread exited (return false)
423 // 0x00000200 - suspend request cancelled (return false)
424 // 0x00000400 - thread suspended (return true)
425 // 0x00001000 - thread is in a suspend equivalent state (return true)
426 // 0x00002000 - thread is native and walkable (return true)
427 // 0x00004000 - thread is native_trans and walkable (needed retry)
428 //
429 // set in wait_for_ext_suspend_completion():
430 // 0x00010000 - routine was entered
431 // 0x00020000 - suspend request cancelled before loop (return false)
432 // 0x00040000 - thread suspended before loop (return true)
433 // 0x00080000 - suspend request cancelled in loop (return false)
434 // 0x00100000 - thread suspended in loop (return true)
435 // 0x00200000 - suspend not completed during retry loop (return false)
436 //
438 // Helper class for tracing suspend wait debug bits.
439 //
440 // 0x00000100 indicates that the target thread exited before it could
441 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
442 // 0x00080000 each indicate a cancelled suspend request so they don't
443 // count as wait failures either.
444 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
446 class TraceSuspendDebugBits : public StackObj {
447 private:
448 JavaThread * jt;
449 bool is_wait;
450 bool called_by_wait; // meaningful when !is_wait
451 uint32_t * bits;
453 public:
454 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
455 uint32_t *_bits) {
456 jt = _jt;
457 is_wait = _is_wait;
458 called_by_wait = _called_by_wait;
459 bits = _bits;
460 }
462 ~TraceSuspendDebugBits() {
463 if (!is_wait) {
464 #if 1
465 // By default, don't trace bits for is_ext_suspend_completed() calls.
466 // That trace is very chatty.
467 return;
468 #else
469 if (!called_by_wait) {
470 // If tracing for is_ext_suspend_completed() is enabled, then only
471 // trace calls to it from wait_for_ext_suspend_completion()
472 return;
473 }
474 #endif
475 }
477 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
478 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
479 MutexLocker ml(Threads_lock); // needed for get_thread_name()
480 ResourceMark rm;
482 tty->print_cr(
483 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
484 jt->get_thread_name(), *bits);
486 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
487 }
488 }
489 }
490 };
491 #undef DEBUG_FALSE_BITS
494 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
495 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
497 bool did_trans_retry = false; // only do thread_in_native_trans retry once
498 bool do_trans_retry; // flag to force the retry
500 *bits |= 0x00000001;
502 do {
503 do_trans_retry = false;
505 if (is_exiting()) {
506 // Thread is in the process of exiting. This is always checked
507 // first to reduce the risk of dereferencing a freed JavaThread.
508 *bits |= 0x00000100;
509 return false;
510 }
512 if (!is_external_suspend()) {
513 // Suspend request is cancelled. This is always checked before
514 // is_ext_suspended() to reduce the risk of a rogue resume
515 // confusing the thread that made the suspend request.
516 *bits |= 0x00000200;
517 return false;
518 }
520 if (is_ext_suspended()) {
521 // thread is suspended
522 *bits |= 0x00000400;
523 return true;
524 }
526 // Now that we no longer do hard suspends of threads running
527 // native code, the target thread can be changing thread state
528 // while we are in this routine:
529 //
530 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
531 //
532 // We save a copy of the thread state as observed at this moment
533 // and make our decision about suspend completeness based on the
534 // copy. This closes the race where the thread state is seen as
535 // _thread_in_native_trans in the if-thread_blocked check, but is
536 // seen as _thread_blocked in if-thread_in_native_trans check.
537 JavaThreadState save_state = thread_state();
539 if (save_state == _thread_blocked && is_suspend_equivalent()) {
540 // If the thread's state is _thread_blocked and this blocking
541 // condition is known to be equivalent to a suspend, then we can
542 // consider the thread to be externally suspended. This means that
543 // the code that sets _thread_blocked has been modified to do
544 // self-suspension if the blocking condition releases. We also
545 // used to check for CONDVAR_WAIT here, but that is now covered by
546 // the _thread_blocked with self-suspension check.
547 //
548 // Return true since we wouldn't be here unless there was still an
549 // external suspend request.
550 *bits |= 0x00001000;
551 return true;
552 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
553 // Threads running native code will self-suspend on native==>VM/Java
554 // transitions. If its stack is walkable (should always be the case
555 // unless this function is called before the actual java_suspend()
556 // call), then the wait is done.
557 *bits |= 0x00002000;
558 return true;
559 } else if (!called_by_wait && !did_trans_retry &&
560 save_state == _thread_in_native_trans &&
561 frame_anchor()->walkable()) {
562 // The thread is transitioning from thread_in_native to another
563 // thread state. check_safepoint_and_suspend_for_native_trans()
564 // will force the thread to self-suspend. If it hasn't gotten
565 // there yet we may have caught the thread in-between the native
566 // code check above and the self-suspend. Lucky us. If we were
567 // called by wait_for_ext_suspend_completion(), then it
568 // will be doing the retries so we don't have to.
569 //
570 // Since we use the saved thread state in the if-statement above,
571 // there is a chance that the thread has already transitioned to
572 // _thread_blocked by the time we get here. In that case, we will
573 // make a single unnecessary pass through the logic below. This
574 // doesn't hurt anything since we still do the trans retry.
576 *bits |= 0x00004000;
578 // Once the thread leaves thread_in_native_trans for another
579 // thread state, we break out of this retry loop. We shouldn't
580 // need this flag to prevent us from getting back here, but
581 // sometimes paranoia is good.
582 did_trans_retry = true;
584 // We wait for the thread to transition to a more usable state.
585 for (int i = 1; i <= SuspendRetryCount; i++) {
586 // We used to do an "os::yield_all(i)" call here with the intention
587 // that yielding would increase on each retry. However, the parameter
588 // is ignored on Linux which means the yield didn't scale up. Waiting
589 // on the SR_lock below provides a much more predictable scale up for
590 // the delay. It also provides a simple/direct point to check for any
591 // safepoint requests from the VMThread
593 // temporarily drops SR_lock while doing wait with safepoint check
594 // (if we're a JavaThread - the WatcherThread can also call this)
595 // and increase delay with each retry
596 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
598 // check the actual thread state instead of what we saved above
599 if (thread_state() != _thread_in_native_trans) {
600 // the thread has transitioned to another thread state so
601 // try all the checks (except this one) one more time.
602 do_trans_retry = true;
603 break;
604 }
605 } // end retry loop
608 }
609 } while (do_trans_retry);
611 *bits |= 0x00000010;
612 return false;
613 }
615 //
616 // Wait for an external suspend request to complete (or be cancelled).
617 // Returns true if the thread is externally suspended and false otherwise.
618 //
619 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
620 uint32_t *bits) {
621 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
622 false /* !called_by_wait */, bits);
624 // local flag copies to minimize SR_lock hold time
625 bool is_suspended;
626 bool pending;
627 uint32_t reset_bits;
629 // set a marker so is_ext_suspend_completed() knows we are the caller
630 *bits |= 0x00010000;
632 // We use reset_bits to reinitialize the bits value at the top of
633 // each retry loop. This allows the caller to make use of any
634 // unused bits for their own marking purposes.
635 reset_bits = *bits;
637 {
638 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
639 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
640 delay, bits);
641 pending = is_external_suspend();
642 }
643 // must release SR_lock to allow suspension to complete
645 if (!pending) {
646 // A cancelled suspend request is the only false return from
647 // is_ext_suspend_completed() that keeps us from entering the
648 // retry loop.
649 *bits |= 0x00020000;
650 return false;
651 }
653 if (is_suspended) {
654 *bits |= 0x00040000;
655 return true;
656 }
658 for (int i = 1; i <= retries; i++) {
659 *bits = reset_bits; // reinit to only track last retry
661 // We used to do an "os::yield_all(i)" call here with the intention
662 // that yielding would increase on each retry. However, the parameter
663 // is ignored on Linux which means the yield didn't scale up. Waiting
664 // on the SR_lock below provides a much more predictable scale up for
665 // the delay. It also provides a simple/direct point to check for any
666 // safepoint requests from the VMThread
668 {
669 MutexLocker ml(SR_lock());
670 // wait with safepoint check (if we're a JavaThread - the WatcherThread
671 // can also call this) and increase delay with each retry
672 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
674 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
675 delay, bits);
677 // It is possible for the external suspend request to be cancelled
678 // (by a resume) before the actual suspend operation is completed.
679 // Refresh our local copy to see if we still need to wait.
680 pending = is_external_suspend();
681 }
683 if (!pending) {
684 // A cancelled suspend request is the only false return from
685 // is_ext_suspend_completed() that keeps us from staying in the
686 // retry loop.
687 *bits |= 0x00080000;
688 return false;
689 }
691 if (is_suspended) {
692 *bits |= 0x00100000;
693 return true;
694 }
695 } // end retry loop
697 // thread did not suspend after all our retries
698 *bits |= 0x00200000;
699 return false;
700 }
702 #ifndef PRODUCT
703 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
705 // This should not need to be atomic as the only way for simultaneous
706 // updates is via interrupts. Even then this should be rare or non-existant
707 // and we don't care that much anyway.
709 int index = _jmp_ring_index;
710 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
711 _jmp_ring[index]._target = (intptr_t) target;
712 _jmp_ring[index]._instruction = (intptr_t) instr;
713 _jmp_ring[index]._file = file;
714 _jmp_ring[index]._line = line;
715 }
716 #endif /* PRODUCT */
718 // Called by flat profiler
719 // Callers have already called wait_for_ext_suspend_completion
720 // The assertion for that is currently too complex to put here:
721 bool JavaThread::profile_last_Java_frame(frame* _fr) {
722 bool gotframe = false;
723 // self suspension saves needed state.
724 if (has_last_Java_frame() && _anchor.walkable()) {
725 *_fr = pd_last_frame();
726 gotframe = true;
727 }
728 return gotframe;
729 }
731 void Thread::interrupt(Thread* thread) {
732 trace("interrupt", thread);
733 debug_only(check_for_dangling_thread_pointer(thread);)
734 os::interrupt(thread);
735 }
737 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
738 trace("is_interrupted", thread);
739 debug_only(check_for_dangling_thread_pointer(thread);)
740 // Note: If clear_interrupted==false, this simply fetches and
741 // returns the value of the field osthread()->interrupted().
742 return os::is_interrupted(thread, clear_interrupted);
743 }
746 // GC Support
747 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
748 jint thread_parity = _oops_do_parity;
749 if (thread_parity != strong_roots_parity) {
750 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
751 if (res == thread_parity) return true;
752 else {
753 guarantee(res == strong_roots_parity, "Or else what?");
754 assert(SharedHeap::heap()->n_par_threads() > 0,
755 "Should only fail when parallel.");
756 return false;
757 }
758 }
759 assert(SharedHeap::heap()->n_par_threads() > 0,
760 "Should only fail when parallel.");
761 return false;
762 }
764 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
765 active_handles()->oops_do(f);
766 // Do oop for ThreadShadow
767 f->do_oop((oop*)&_pending_exception);
768 handle_area()->oops_do(f);
769 }
771 void Thread::nmethods_do(CodeBlobClosure* cf) {
772 // no nmethods in a generic thread...
773 }
775 void Thread::print_on(outputStream* st) const {
776 // get_priority assumes osthread initialized
777 if (osthread() != NULL) {
778 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
779 osthread()->print_on(st);
780 }
781 debug_only(if (WizardMode) print_owned_locks_on(st);)
782 }
784 // Thread::print_on_error() is called by fatal error handler. Don't use
785 // any lock or allocate memory.
786 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
787 if (is_VM_thread()) st->print("VMThread");
788 else if (is_Compiler_thread()) st->print("CompilerThread");
789 else if (is_Java_thread()) st->print("JavaThread");
790 else if (is_GC_task_thread()) st->print("GCTaskThread");
791 else if (is_Watcher_thread()) st->print("WatcherThread");
792 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
793 else st->print("Thread");
795 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
796 _stack_base - _stack_size, _stack_base);
798 if (osthread()) {
799 st->print(" [id=%d]", osthread()->thread_id());
800 }
801 }
803 #ifdef ASSERT
804 void Thread::print_owned_locks_on(outputStream* st) const {
805 Monitor *cur = _owned_locks;
806 if (cur == NULL) {
807 st->print(" (no locks) ");
808 } else {
809 st->print_cr(" Locks owned:");
810 while(cur) {
811 cur->print_on(st);
812 cur = cur->next();
813 }
814 }
815 }
817 static int ref_use_count = 0;
819 bool Thread::owns_locks_but_compiled_lock() const {
820 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
821 if (cur != Compile_lock) return true;
822 }
823 return false;
824 }
827 #endif
829 #ifndef PRODUCT
831 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
832 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
833 // no threads which allow_vm_block's are held
834 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
835 // Check if current thread is allowed to block at a safepoint
836 if (!(_allow_safepoint_count == 0))
837 fatal("Possible safepoint reached by thread that does not allow it");
838 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
839 fatal("LEAF method calling lock?");
840 }
842 #ifdef ASSERT
843 if (potential_vm_operation && is_Java_thread()
844 && !Universe::is_bootstrapping()) {
845 // Make sure we do not hold any locks that the VM thread also uses.
846 // This could potentially lead to deadlocks
847 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
848 // Threads_lock is special, since the safepoint synchronization will not start before this is
849 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
850 // since it is used to transfer control between JavaThreads and the VMThread
851 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
852 if ( (cur->allow_vm_block() &&
853 cur != Threads_lock &&
854 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
855 cur != VMOperationRequest_lock &&
856 cur != VMOperationQueue_lock) ||
857 cur->rank() == Mutex::special) {
858 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
859 }
860 }
861 }
863 if (GCALotAtAllSafepoints) {
864 // We could enter a safepoint here and thus have a gc
865 InterfaceSupport::check_gc_alot();
866 }
867 #endif
868 }
869 #endif
871 bool Thread::is_in_stack(address adr) const {
872 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
873 address end = os::current_stack_pointer();
874 if (stack_base() >= adr && adr >= end) return true;
876 return false;
877 }
880 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
881 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
882 // used for compilation in the future. If that change is made, the need for these methods
883 // should be revisited, and they should be removed if possible.
885 bool Thread::is_lock_owned(address adr) const {
886 return on_local_stack(adr);
887 }
889 bool Thread::set_as_starting_thread() {
890 // NOTE: this must be called inside the main thread.
891 return os::create_main_thread((JavaThread*)this);
892 }
894 static void initialize_class(symbolHandle class_name, TRAPS) {
895 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
896 instanceKlass::cast(klass)->initialize(CHECK);
897 }
900 // Creates the initial ThreadGroup
901 static Handle create_initial_thread_group(TRAPS) {
902 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_ThreadGroup(), true, CHECK_NH);
903 instanceKlassHandle klass (THREAD, k);
905 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
906 {
907 JavaValue result(T_VOID);
908 JavaCalls::call_special(&result,
909 system_instance,
910 klass,
911 vmSymbolHandles::object_initializer_name(),
912 vmSymbolHandles::void_method_signature(),
913 CHECK_NH);
914 }
915 Universe::set_system_thread_group(system_instance());
917 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
918 {
919 JavaValue result(T_VOID);
920 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
921 JavaCalls::call_special(&result,
922 main_instance,
923 klass,
924 vmSymbolHandles::object_initializer_name(),
925 vmSymbolHandles::threadgroup_string_void_signature(),
926 system_instance,
927 string,
928 CHECK_NH);
929 }
930 return main_instance;
931 }
933 // Creates the initial Thread
934 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
935 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK_NULL);
936 instanceKlassHandle klass (THREAD, k);
937 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
939 java_lang_Thread::set_thread(thread_oop(), thread);
940 java_lang_Thread::set_priority(thread_oop(), NormPriority);
941 thread->set_threadObj(thread_oop());
943 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
945 JavaValue result(T_VOID);
946 JavaCalls::call_special(&result, thread_oop,
947 klass,
948 vmSymbolHandles::object_initializer_name(),
949 vmSymbolHandles::threadgroup_string_void_signature(),
950 thread_group,
951 string,
952 CHECK_NULL);
953 return thread_oop();
954 }
956 static void call_initializeSystemClass(TRAPS) {
957 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_System(), true, CHECK);
958 instanceKlassHandle klass (THREAD, k);
960 JavaValue result(T_VOID);
961 JavaCalls::call_static(&result, klass, vmSymbolHandles::initializeSystemClass_name(),
962 vmSymbolHandles::void_method_signature(), CHECK);
963 }
965 #ifdef KERNEL
966 static void set_jkernel_boot_classloader_hook(TRAPS) {
967 klassOop k = SystemDictionary::sun_jkernel_DownloadManager_klass();
968 instanceKlassHandle klass (THREAD, k);
970 if (k == NULL) {
971 // sun.jkernel.DownloadManager may not present in the JDK; just return
972 return;
973 }
975 JavaValue result(T_VOID);
976 JavaCalls::call_static(&result, klass, vmSymbolHandles::setBootClassLoaderHook_name(),
977 vmSymbolHandles::void_method_signature(), CHECK);
978 }
979 #endif // KERNEL
981 // General purpose hook into Java code, run once when the VM is initialized.
982 // The Java library method itself may be changed independently from the VM.
983 static void call_postVMInitHook(TRAPS) {
984 klassOop k = SystemDictionary::sun_misc_PostVMInitHook_klass();
985 instanceKlassHandle klass (THREAD, k);
986 if (klass.not_null()) {
987 JavaValue result(T_VOID);
988 JavaCalls::call_static(&result, klass, vmSymbolHandles::run_method_name(),
989 vmSymbolHandles::void_method_signature(),
990 CHECK);
991 }
992 }
994 static void reset_vm_info_property(TRAPS) {
995 // the vm info string
996 ResourceMark rm(THREAD);
997 const char *vm_info = VM_Version::vm_info_string();
999 // java.lang.System class
1000 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_System(), true, CHECK);
1001 instanceKlassHandle klass (THREAD, k);
1003 // setProperty arguments
1004 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1005 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1007 // return value
1008 JavaValue r(T_OBJECT);
1010 // public static String setProperty(String key, String value);
1011 JavaCalls::call_static(&r,
1012 klass,
1013 vmSymbolHandles::setProperty_name(),
1014 vmSymbolHandles::string_string_string_signature(),
1015 key_str,
1016 value_str,
1017 CHECK);
1018 }
1021 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1022 assert(thread_group.not_null(), "thread group should be specified");
1023 assert(threadObj() == NULL, "should only create Java thread object once");
1025 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK);
1026 instanceKlassHandle klass (THREAD, k);
1027 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1029 java_lang_Thread::set_thread(thread_oop(), this);
1030 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1031 set_threadObj(thread_oop());
1033 JavaValue result(T_VOID);
1034 if (thread_name != NULL) {
1035 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1036 // Thread gets assigned specified name and null target
1037 JavaCalls::call_special(&result,
1038 thread_oop,
1039 klass,
1040 vmSymbolHandles::object_initializer_name(),
1041 vmSymbolHandles::threadgroup_string_void_signature(),
1042 thread_group, // Argument 1
1043 name, // Argument 2
1044 THREAD);
1045 } else {
1046 // Thread gets assigned name "Thread-nnn" and null target
1047 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1048 JavaCalls::call_special(&result,
1049 thread_oop,
1050 klass,
1051 vmSymbolHandles::object_initializer_name(),
1052 vmSymbolHandles::threadgroup_runnable_void_signature(),
1053 thread_group, // Argument 1
1054 Handle(), // Argument 2
1055 THREAD);
1056 }
1059 if (daemon) {
1060 java_lang_Thread::set_daemon(thread_oop());
1061 }
1063 if (HAS_PENDING_EXCEPTION) {
1064 return;
1065 }
1067 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1068 Handle threadObj(this, this->threadObj());
1070 JavaCalls::call_special(&result,
1071 thread_group,
1072 group,
1073 vmSymbolHandles::add_method_name(),
1074 vmSymbolHandles::thread_void_signature(),
1075 threadObj, // Arg 1
1076 THREAD);
1079 }
1081 // NamedThread -- non-JavaThread subclasses with multiple
1082 // uniquely named instances should derive from this.
1083 NamedThread::NamedThread() : Thread() {
1084 _name = NULL;
1085 _processed_thread = NULL;
1086 }
1088 NamedThread::~NamedThread() {
1089 if (_name != NULL) {
1090 FREE_C_HEAP_ARRAY(char, _name);
1091 _name = NULL;
1092 }
1093 }
1095 void NamedThread::set_name(const char* format, ...) {
1096 guarantee(_name == NULL, "Only get to set name once.");
1097 _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1098 guarantee(_name != NULL, "alloc failure");
1099 va_list ap;
1100 va_start(ap, format);
1101 jio_vsnprintf(_name, max_name_len, format, ap);
1102 va_end(ap);
1103 }
1105 // ======= WatcherThread ========
1107 // The watcher thread exists to simulate timer interrupts. It should
1108 // be replaced by an abstraction over whatever native support for
1109 // timer interrupts exists on the platform.
1111 WatcherThread* WatcherThread::_watcher_thread = NULL;
1112 volatile bool WatcherThread::_should_terminate = false;
1114 WatcherThread::WatcherThread() : Thread() {
1115 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1116 if (os::create_thread(this, os::watcher_thread)) {
1117 _watcher_thread = this;
1119 // Set the watcher thread to the highest OS priority which should not be
1120 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1121 // is created. The only normal thread using this priority is the reference
1122 // handler thread, which runs for very short intervals only.
1123 // If the VMThread's priority is not lower than the WatcherThread profiling
1124 // will be inaccurate.
1125 os::set_priority(this, MaxPriority);
1126 if (!DisableStartThread) {
1127 os::start_thread(this);
1128 }
1129 }
1130 }
1132 void WatcherThread::run() {
1133 assert(this == watcher_thread(), "just checking");
1135 this->record_stack_base_and_size();
1136 this->initialize_thread_local_storage();
1137 this->set_active_handles(JNIHandleBlock::allocate_block());
1138 while(!_should_terminate) {
1139 assert(watcher_thread() == Thread::current(), "thread consistency check");
1140 assert(watcher_thread() == this, "thread consistency check");
1142 // Calculate how long it'll be until the next PeriodicTask work
1143 // should be done, and sleep that amount of time.
1144 size_t time_to_wait = PeriodicTask::time_to_wait();
1146 // we expect this to timeout - we only ever get unparked when
1147 // we should terminate
1148 {
1149 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1151 jlong prev_time = os::javaTimeNanos();
1152 for (;;) {
1153 int res= _SleepEvent->park(time_to_wait);
1154 if (res == OS_TIMEOUT || _should_terminate)
1155 break;
1156 // spurious wakeup of some kind
1157 jlong now = os::javaTimeNanos();
1158 time_to_wait -= (now - prev_time) / 1000000;
1159 if (time_to_wait <= 0)
1160 break;
1161 prev_time = now;
1162 }
1163 }
1165 if (is_error_reported()) {
1166 // A fatal error has happened, the error handler(VMError::report_and_die)
1167 // should abort JVM after creating an error log file. However in some
1168 // rare cases, the error handler itself might deadlock. Here we try to
1169 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1170 //
1171 // This code is in WatcherThread because WatcherThread wakes up
1172 // periodically so the fatal error handler doesn't need to do anything;
1173 // also because the WatcherThread is less likely to crash than other
1174 // threads.
1176 for (;;) {
1177 if (!ShowMessageBoxOnError
1178 && (OnError == NULL || OnError[0] == '\0')
1179 && Arguments::abort_hook() == NULL) {
1180 os::sleep(this, 2 * 60 * 1000, false);
1181 fdStream err(defaultStream::output_fd());
1182 err.print_raw_cr("# [ timer expired, abort... ]");
1183 // skip atexit/vm_exit/vm_abort hooks
1184 os::die();
1185 }
1187 // Wake up 5 seconds later, the fatal handler may reset OnError or
1188 // ShowMessageBoxOnError when it is ready to abort.
1189 os::sleep(this, 5 * 1000, false);
1190 }
1191 }
1193 PeriodicTask::real_time_tick(time_to_wait);
1195 // If we have no more tasks left due to dynamic disenrollment,
1196 // shut down the thread since we don't currently support dynamic enrollment
1197 if (PeriodicTask::num_tasks() == 0) {
1198 _should_terminate = true;
1199 }
1200 }
1202 // Signal that it is terminated
1203 {
1204 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1205 _watcher_thread = NULL;
1206 Terminator_lock->notify();
1207 }
1209 // Thread destructor usually does this..
1210 ThreadLocalStorage::set_thread(NULL);
1211 }
1213 void WatcherThread::start() {
1214 if (watcher_thread() == NULL) {
1215 _should_terminate = false;
1216 // Create the single instance of WatcherThread
1217 new WatcherThread();
1218 }
1219 }
1221 void WatcherThread::stop() {
1222 // it is ok to take late safepoints here, if needed
1223 MutexLocker mu(Terminator_lock);
1224 _should_terminate = true;
1225 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1227 Thread* watcher = watcher_thread();
1228 if (watcher != NULL)
1229 watcher->_SleepEvent->unpark();
1231 while(watcher_thread() != NULL) {
1232 // This wait should make safepoint checks, wait without a timeout,
1233 // and wait as a suspend-equivalent condition.
1234 //
1235 // Note: If the FlatProfiler is running, then this thread is waiting
1236 // for the WatcherThread to terminate and the WatcherThread, via the
1237 // FlatProfiler task, is waiting for the external suspend request on
1238 // this thread to complete. wait_for_ext_suspend_completion() will
1239 // eventually timeout, but that takes time. Making this wait a
1240 // suspend-equivalent condition solves that timeout problem.
1241 //
1242 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1243 Mutex::_as_suspend_equivalent_flag);
1244 }
1245 }
1247 void WatcherThread::print_on(outputStream* st) const {
1248 st->print("\"%s\" ", name());
1249 Thread::print_on(st);
1250 st->cr();
1251 }
1253 // ======= JavaThread ========
1255 // A JavaThread is a normal Java thread
1257 void JavaThread::initialize() {
1258 // Initialize fields
1260 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1261 set_claimed_par_id(-1);
1263 set_saved_exception_pc(NULL);
1264 set_threadObj(NULL);
1265 _anchor.clear();
1266 set_entry_point(NULL);
1267 set_jni_functions(jni_functions());
1268 set_callee_target(NULL);
1269 set_vm_result(NULL);
1270 set_vm_result_2(NULL);
1271 set_vframe_array_head(NULL);
1272 set_vframe_array_last(NULL);
1273 set_deferred_locals(NULL);
1274 set_deopt_mark(NULL);
1275 set_deopt_nmethod(NULL);
1276 clear_must_deopt_id();
1277 set_monitor_chunks(NULL);
1278 set_next(NULL);
1279 set_thread_state(_thread_new);
1280 _terminated = _not_terminated;
1281 _privileged_stack_top = NULL;
1282 _array_for_gc = NULL;
1283 _suspend_equivalent = false;
1284 _in_deopt_handler = 0;
1285 _doing_unsafe_access = false;
1286 _stack_guard_state = stack_guard_unused;
1287 _exception_oop = NULL;
1288 _exception_pc = 0;
1289 _exception_handler_pc = 0;
1290 _exception_stack_size = 0;
1291 _is_method_handle_return = 0;
1292 _jvmti_thread_state= NULL;
1293 _should_post_on_exceptions_flag = JNI_FALSE;
1294 _jvmti_get_loaded_classes_closure = NULL;
1295 _interp_only_mode = 0;
1296 _special_runtime_exit_condition = _no_async_condition;
1297 _pending_async_exception = NULL;
1298 _is_compiling = false;
1299 _thread_stat = NULL;
1300 _thread_stat = new ThreadStatistics();
1301 _blocked_on_compilation = false;
1302 _jni_active_critical = 0;
1303 _do_not_unlock_if_synchronized = false;
1304 _cached_monitor_info = NULL;
1305 _parker = Parker::Allocate(this) ;
1307 #ifndef PRODUCT
1308 _jmp_ring_index = 0;
1309 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1310 record_jump(NULL, NULL, NULL, 0);
1311 }
1312 #endif /* PRODUCT */
1314 set_thread_profiler(NULL);
1315 if (FlatProfiler::is_active()) {
1316 // This is where we would decide to either give each thread it's own profiler
1317 // or use one global one from FlatProfiler,
1318 // or up to some count of the number of profiled threads, etc.
1319 ThreadProfiler* pp = new ThreadProfiler();
1320 pp->engage();
1321 set_thread_profiler(pp);
1322 }
1324 // Setup safepoint state info for this thread
1325 ThreadSafepointState::create(this);
1327 debug_only(_java_call_counter = 0);
1329 // JVMTI PopFrame support
1330 _popframe_condition = popframe_inactive;
1331 _popframe_preserved_args = NULL;
1332 _popframe_preserved_args_size = 0;
1334 pd_initialize();
1335 }
1337 #ifndef SERIALGC
1338 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1339 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1340 #endif // !SERIALGC
1342 JavaThread::JavaThread(bool is_attaching) :
1343 Thread()
1344 #ifndef SERIALGC
1345 , _satb_mark_queue(&_satb_mark_queue_set),
1346 _dirty_card_queue(&_dirty_card_queue_set)
1347 #endif // !SERIALGC
1348 {
1349 initialize();
1350 _is_attaching = is_attaching;
1351 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1352 }
1354 bool JavaThread::reguard_stack(address cur_sp) {
1355 if (_stack_guard_state != stack_guard_yellow_disabled) {
1356 return true; // Stack already guarded or guard pages not needed.
1357 }
1359 if (register_stack_overflow()) {
1360 // For those architectures which have separate register and
1361 // memory stacks, we must check the register stack to see if
1362 // it has overflowed.
1363 return false;
1364 }
1366 // Java code never executes within the yellow zone: the latter is only
1367 // there to provoke an exception during stack banging. If java code
1368 // is executing there, either StackShadowPages should be larger, or
1369 // some exception code in c1, c2 or the interpreter isn't unwinding
1370 // when it should.
1371 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1373 enable_stack_yellow_zone();
1374 return true;
1375 }
1377 bool JavaThread::reguard_stack(void) {
1378 return reguard_stack(os::current_stack_pointer());
1379 }
1382 void JavaThread::block_if_vm_exited() {
1383 if (_terminated == _vm_exited) {
1384 // _vm_exited is set at safepoint, and Threads_lock is never released
1385 // we will block here forever
1386 Threads_lock->lock_without_safepoint_check();
1387 ShouldNotReachHere();
1388 }
1389 }
1392 // Remove this ifdef when C1 is ported to the compiler interface.
1393 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1395 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1396 Thread()
1397 #ifndef SERIALGC
1398 , _satb_mark_queue(&_satb_mark_queue_set),
1399 _dirty_card_queue(&_dirty_card_queue_set)
1400 #endif // !SERIALGC
1401 {
1402 if (TraceThreadEvents) {
1403 tty->print_cr("creating thread %p", this);
1404 }
1405 initialize();
1406 _is_attaching = false;
1407 set_entry_point(entry_point);
1408 // Create the native thread itself.
1409 // %note runtime_23
1410 os::ThreadType thr_type = os::java_thread;
1411 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1412 os::java_thread;
1413 os::create_thread(this, thr_type, stack_sz);
1415 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1416 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1417 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1418 // the exception consists of creating the exception object & initializing it, initialization
1419 // will leave the VM via a JavaCall and then all locks must be unlocked).
1420 //
1421 // The thread is still suspended when we reach here. Thread must be explicit started
1422 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1423 // by calling Threads:add. The reason why this is not done here, is because the thread
1424 // object must be fully initialized (take a look at JVM_Start)
1425 }
1427 JavaThread::~JavaThread() {
1428 if (TraceThreadEvents) {
1429 tty->print_cr("terminate thread %p", this);
1430 }
1432 // JSR166 -- return the parker to the free list
1433 Parker::Release(_parker);
1434 _parker = NULL ;
1436 // Free any remaining previous UnrollBlock
1437 vframeArray* old_array = vframe_array_last();
1439 if (old_array != NULL) {
1440 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1441 old_array->set_unroll_block(NULL);
1442 delete old_info;
1443 delete old_array;
1444 }
1446 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1447 if (deferred != NULL) {
1448 // This can only happen if thread is destroyed before deoptimization occurs.
1449 assert(deferred->length() != 0, "empty array!");
1450 do {
1451 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1452 deferred->remove_at(0);
1453 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1454 delete dlv;
1455 } while (deferred->length() != 0);
1456 delete deferred;
1457 }
1459 // All Java related clean up happens in exit
1460 ThreadSafepointState::destroy(this);
1461 if (_thread_profiler != NULL) delete _thread_profiler;
1462 if (_thread_stat != NULL) delete _thread_stat;
1463 }
1466 // The first routine called by a new Java thread
1467 void JavaThread::run() {
1468 // initialize thread-local alloc buffer related fields
1469 this->initialize_tlab();
1471 // used to test validitity of stack trace backs
1472 this->record_base_of_stack_pointer();
1474 // Record real stack base and size.
1475 this->record_stack_base_and_size();
1477 // Initialize thread local storage; set before calling MutexLocker
1478 this->initialize_thread_local_storage();
1480 this->create_stack_guard_pages();
1482 this->cache_global_variables();
1484 // Thread is now sufficient initialized to be handled by the safepoint code as being
1485 // in the VM. Change thread state from _thread_new to _thread_in_vm
1486 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1488 assert(JavaThread::current() == this, "sanity check");
1489 assert(!Thread::current()->owns_locks(), "sanity check");
1491 DTRACE_THREAD_PROBE(start, this);
1493 // This operation might block. We call that after all safepoint checks for a new thread has
1494 // been completed.
1495 this->set_active_handles(JNIHandleBlock::allocate_block());
1497 if (JvmtiExport::should_post_thread_life()) {
1498 JvmtiExport::post_thread_start(this);
1499 }
1501 // We call another function to do the rest so we are sure that the stack addresses used
1502 // from there will be lower than the stack base just computed
1503 thread_main_inner();
1505 // Note, thread is no longer valid at this point!
1506 }
1509 void JavaThread::thread_main_inner() {
1510 assert(JavaThread::current() == this, "sanity check");
1511 assert(this->threadObj() != NULL, "just checking");
1513 // Execute thread entry point. If this thread is being asked to restart,
1514 // or has been stopped before starting, do not reexecute entry point.
1515 // Note: Due to JVM_StopThread we can have pending exceptions already!
1516 if (!this->has_pending_exception() && !java_lang_Thread::is_stillborn(this->threadObj())) {
1517 // enter the thread's entry point only if we have no pending exceptions
1518 HandleMark hm(this);
1519 this->entry_point()(this, this);
1520 }
1522 DTRACE_THREAD_PROBE(stop, this);
1524 this->exit(false);
1525 delete this;
1526 }
1529 static void ensure_join(JavaThread* thread) {
1530 // We do not need to grap the Threads_lock, since we are operating on ourself.
1531 Handle threadObj(thread, thread->threadObj());
1532 assert(threadObj.not_null(), "java thread object must exist");
1533 ObjectLocker lock(threadObj, thread);
1534 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1535 thread->clear_pending_exception();
1536 // It is of profound importance that we set the stillborn bit and reset the thread object,
1537 // before we do the notify. Since, changing these two variable will make JVM_IsAlive return
1538 // false. So in case another thread is doing a join on this thread , it will detect that the thread
1539 // is dead when it gets notified.
1540 java_lang_Thread::set_stillborn(threadObj());
1541 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1542 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1543 java_lang_Thread::set_thread(threadObj(), NULL);
1544 lock.notify_all(thread);
1545 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1546 thread->clear_pending_exception();
1547 }
1550 // For any new cleanup additions, please check to see if they need to be applied to
1551 // cleanup_failed_attach_current_thread as well.
1552 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1553 assert(this == JavaThread::current(), "thread consistency check");
1554 if (!InitializeJavaLangSystem) return;
1556 HandleMark hm(this);
1557 Handle uncaught_exception(this, this->pending_exception());
1558 this->clear_pending_exception();
1559 Handle threadObj(this, this->threadObj());
1560 assert(threadObj.not_null(), "Java thread object should be created");
1562 if (get_thread_profiler() != NULL) {
1563 get_thread_profiler()->disengage();
1564 ResourceMark rm;
1565 get_thread_profiler()->print(get_thread_name());
1566 }
1569 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1570 {
1571 EXCEPTION_MARK;
1573 CLEAR_PENDING_EXCEPTION;
1574 }
1575 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1576 // has to be fixed by a runtime query method
1577 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1578 // JSR-166: change call from from ThreadGroup.uncaughtException to
1579 // java.lang.Thread.dispatchUncaughtException
1580 if (uncaught_exception.not_null()) {
1581 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1582 Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",
1583 (address)uncaught_exception(), (address)threadObj(), (address)group());
1584 {
1585 EXCEPTION_MARK;
1586 // Check if the method Thread.dispatchUncaughtException() exists. If so
1587 // call it. Otherwise we have an older library without the JSR-166 changes,
1588 // so call ThreadGroup.uncaughtException()
1589 KlassHandle recvrKlass(THREAD, threadObj->klass());
1590 CallInfo callinfo;
1591 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1592 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1593 vmSymbolHandles::dispatchUncaughtException_name(),
1594 vmSymbolHandles::throwable_void_signature(),
1595 KlassHandle(), false, false, THREAD);
1596 CLEAR_PENDING_EXCEPTION;
1597 methodHandle method = callinfo.selected_method();
1598 if (method.not_null()) {
1599 JavaValue result(T_VOID);
1600 JavaCalls::call_virtual(&result,
1601 threadObj, thread_klass,
1602 vmSymbolHandles::dispatchUncaughtException_name(),
1603 vmSymbolHandles::throwable_void_signature(),
1604 uncaught_exception,
1605 THREAD);
1606 } else {
1607 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1608 JavaValue result(T_VOID);
1609 JavaCalls::call_virtual(&result,
1610 group, thread_group,
1611 vmSymbolHandles::uncaughtException_name(),
1612 vmSymbolHandles::thread_throwable_void_signature(),
1613 threadObj, // Arg 1
1614 uncaught_exception, // Arg 2
1615 THREAD);
1616 }
1617 CLEAR_PENDING_EXCEPTION;
1618 }
1619 }
1621 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1622 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1623 // is deprecated anyhow.
1624 { int count = 3;
1625 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1626 EXCEPTION_MARK;
1627 JavaValue result(T_VOID);
1628 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1629 JavaCalls::call_virtual(&result,
1630 threadObj, thread_klass,
1631 vmSymbolHandles::exit_method_name(),
1632 vmSymbolHandles::void_method_signature(),
1633 THREAD);
1634 CLEAR_PENDING_EXCEPTION;
1635 }
1636 }
1638 // notify JVMTI
1639 if (JvmtiExport::should_post_thread_life()) {
1640 JvmtiExport::post_thread_end(this);
1641 }
1643 // We have notified the agents that we are exiting, before we go on,
1644 // we must check for a pending external suspend request and honor it
1645 // in order to not surprise the thread that made the suspend request.
1646 while (true) {
1647 {
1648 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1649 if (!is_external_suspend()) {
1650 set_terminated(_thread_exiting);
1651 ThreadService::current_thread_exiting(this);
1652 break;
1653 }
1654 // Implied else:
1655 // Things get a little tricky here. We have a pending external
1656 // suspend request, but we are holding the SR_lock so we
1657 // can't just self-suspend. So we temporarily drop the lock
1658 // and then self-suspend.
1659 }
1661 ThreadBlockInVM tbivm(this);
1662 java_suspend_self();
1664 // We're done with this suspend request, but we have to loop around
1665 // and check again. Eventually we will get SR_lock without a pending
1666 // external suspend request and will be able to mark ourselves as
1667 // exiting.
1668 }
1669 // no more external suspends are allowed at this point
1670 } else {
1671 // before_exit() has already posted JVMTI THREAD_END events
1672 }
1674 // Notify waiters on thread object. This has to be done after exit() is called
1675 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1676 // group should have the destroyed bit set before waiters are notified).
1677 ensure_join(this);
1678 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1680 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1681 // held by this thread must be released. A detach operation must only
1682 // get here if there are no Java frames on the stack. Therefore, any
1683 // owned monitors at this point MUST be JNI-acquired monitors which are
1684 // pre-inflated and in the monitor cache.
1685 //
1686 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1687 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1688 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1689 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1690 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1691 }
1693 // These things needs to be done while we are still a Java Thread. Make sure that thread
1694 // is in a consistent state, in case GC happens
1695 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1697 if (active_handles() != NULL) {
1698 JNIHandleBlock* block = active_handles();
1699 set_active_handles(NULL);
1700 JNIHandleBlock::release_block(block);
1701 }
1703 if (free_handle_block() != NULL) {
1704 JNIHandleBlock* block = free_handle_block();
1705 set_free_handle_block(NULL);
1706 JNIHandleBlock::release_block(block);
1707 }
1709 // These have to be removed while this is still a valid thread.
1710 remove_stack_guard_pages();
1712 if (UseTLAB) {
1713 tlab().make_parsable(true); // retire TLAB
1714 }
1716 if (JvmtiEnv::environments_might_exist()) {
1717 JvmtiExport::cleanup_thread(this);
1718 }
1720 #ifndef SERIALGC
1721 // We must flush G1-related buffers before removing a thread from
1722 // the list of active threads.
1723 if (UseG1GC) {
1724 flush_barrier_queues();
1725 }
1726 #endif
1728 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1729 Threads::remove(this);
1730 }
1732 #ifndef SERIALGC
1733 // Flush G1-related queues.
1734 void JavaThread::flush_barrier_queues() {
1735 satb_mark_queue().flush();
1736 dirty_card_queue().flush();
1737 }
1739 void JavaThread::initialize_queues() {
1740 assert(!SafepointSynchronize::is_at_safepoint(),
1741 "we should not be at a safepoint");
1743 ObjPtrQueue& satb_queue = satb_mark_queue();
1744 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1745 // The SATB queue should have been constructed with its active
1746 // field set to false.
1747 assert(!satb_queue.is_active(), "SATB queue should not be active");
1748 assert(satb_queue.is_empty(), "SATB queue should be empty");
1749 // If we are creating the thread during a marking cycle, we should
1750 // set the active field of the SATB queue to true.
1751 if (satb_queue_set.is_active()) {
1752 satb_queue.set_active(true);
1753 }
1755 DirtyCardQueue& dirty_queue = dirty_card_queue();
1756 // The dirty card queue should have been constructed with its
1757 // active field set to true.
1758 assert(dirty_queue.is_active(), "dirty card queue should be active");
1759 }
1760 #endif // !SERIALGC
1762 void JavaThread::cleanup_failed_attach_current_thread() {
1763 if (get_thread_profiler() != NULL) {
1764 get_thread_profiler()->disengage();
1765 ResourceMark rm;
1766 get_thread_profiler()->print(get_thread_name());
1767 }
1769 if (active_handles() != NULL) {
1770 JNIHandleBlock* block = active_handles();
1771 set_active_handles(NULL);
1772 JNIHandleBlock::release_block(block);
1773 }
1775 if (free_handle_block() != NULL) {
1776 JNIHandleBlock* block = free_handle_block();
1777 set_free_handle_block(NULL);
1778 JNIHandleBlock::release_block(block);
1779 }
1781 // These have to be removed while this is still a valid thread.
1782 remove_stack_guard_pages();
1784 if (UseTLAB) {
1785 tlab().make_parsable(true); // retire TLAB, if any
1786 }
1788 #ifndef SERIALGC
1789 if (UseG1GC) {
1790 flush_barrier_queues();
1791 }
1792 #endif
1794 Threads::remove(this);
1795 delete this;
1796 }
1801 JavaThread* JavaThread::active() {
1802 Thread* thread = ThreadLocalStorage::thread();
1803 assert(thread != NULL, "just checking");
1804 if (thread->is_Java_thread()) {
1805 return (JavaThread*) thread;
1806 } else {
1807 assert(thread->is_VM_thread(), "this must be a vm thread");
1808 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1809 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1810 assert(ret->is_Java_thread(), "must be a Java thread");
1811 return ret;
1812 }
1813 }
1815 bool JavaThread::is_lock_owned(address adr) const {
1816 if (Thread::is_lock_owned(adr)) return true;
1818 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1819 if (chunk->contains(adr)) return true;
1820 }
1822 return false;
1823 }
1826 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1827 chunk->set_next(monitor_chunks());
1828 set_monitor_chunks(chunk);
1829 }
1831 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1832 guarantee(monitor_chunks() != NULL, "must be non empty");
1833 if (monitor_chunks() == chunk) {
1834 set_monitor_chunks(chunk->next());
1835 } else {
1836 MonitorChunk* prev = monitor_chunks();
1837 while (prev->next() != chunk) prev = prev->next();
1838 prev->set_next(chunk->next());
1839 }
1840 }
1842 // JVM support.
1844 // Note: this function shouldn't block if it's called in
1845 // _thread_in_native_trans state (such as from
1846 // check_special_condition_for_native_trans()).
1847 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1849 if (has_last_Java_frame() && has_async_condition()) {
1850 // If we are at a polling page safepoint (not a poll return)
1851 // then we must defer async exception because live registers
1852 // will be clobbered by the exception path. Poll return is
1853 // ok because the call we a returning from already collides
1854 // with exception handling registers and so there is no issue.
1855 // (The exception handling path kills call result registers but
1856 // this is ok since the exception kills the result anyway).
1858 if (is_at_poll_safepoint()) {
1859 // if the code we are returning to has deoptimized we must defer
1860 // the exception otherwise live registers get clobbered on the
1861 // exception path before deoptimization is able to retrieve them.
1862 //
1863 RegisterMap map(this, false);
1864 frame caller_fr = last_frame().sender(&map);
1865 assert(caller_fr.is_compiled_frame(), "what?");
1866 if (caller_fr.is_deoptimized_frame()) {
1867 if (TraceExceptions) {
1868 ResourceMark rm;
1869 tty->print_cr("deferred async exception at compiled safepoint");
1870 }
1871 return;
1872 }
1873 }
1874 }
1876 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1877 if (condition == _no_async_condition) {
1878 // Conditions have changed since has_special_runtime_exit_condition()
1879 // was called:
1880 // - if we were here only because of an external suspend request,
1881 // then that was taken care of above (or cancelled) so we are done
1882 // - if we were here because of another async request, then it has
1883 // been cleared between the has_special_runtime_exit_condition()
1884 // and now so again we are done
1885 return;
1886 }
1888 // Check for pending async. exception
1889 if (_pending_async_exception != NULL) {
1890 // Only overwrite an already pending exception, if it is not a threadDeath.
1891 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1893 // We cannot call Exceptions::_throw(...) here because we cannot block
1894 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1896 if (TraceExceptions) {
1897 ResourceMark rm;
1898 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1899 if (has_last_Java_frame() ) {
1900 frame f = last_frame();
1901 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1902 }
1903 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1904 }
1905 _pending_async_exception = NULL;
1906 clear_has_async_exception();
1907 }
1908 }
1910 if (check_unsafe_error &&
1911 condition == _async_unsafe_access_error && !has_pending_exception()) {
1912 condition = _no_async_condition; // done
1913 switch (thread_state()) {
1914 case _thread_in_vm:
1915 {
1916 JavaThread* THREAD = this;
1917 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1918 }
1919 case _thread_in_native:
1920 {
1921 ThreadInVMfromNative tiv(this);
1922 JavaThread* THREAD = this;
1923 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1924 }
1925 case _thread_in_Java:
1926 {
1927 ThreadInVMfromJava tiv(this);
1928 JavaThread* THREAD = this;
1929 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1930 }
1931 default:
1932 ShouldNotReachHere();
1933 }
1934 }
1936 assert(condition == _no_async_condition || has_pending_exception() ||
1937 (!check_unsafe_error && condition == _async_unsafe_access_error),
1938 "must have handled the async condition, if no exception");
1939 }
1941 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1942 //
1943 // Check for pending external suspend. Internal suspend requests do
1944 // not use handle_special_runtime_exit_condition().
1945 // If JNIEnv proxies are allowed, don't self-suspend if the target
1946 // thread is not the current thread. In older versions of jdbx, jdbx
1947 // threads could call into the VM with another thread's JNIEnv so we
1948 // can be here operating on behalf of a suspended thread (4432884).
1949 bool do_self_suspend = is_external_suspend_with_lock();
1950 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1951 //
1952 // Because thread is external suspended the safepoint code will count
1953 // thread as at a safepoint. This can be odd because we can be here
1954 // as _thread_in_Java which would normally transition to _thread_blocked
1955 // at a safepoint. We would like to mark the thread as _thread_blocked
1956 // before calling java_suspend_self like all other callers of it but
1957 // we must then observe proper safepoint protocol. (We can't leave
1958 // _thread_blocked with a safepoint in progress). However we can be
1959 // here as _thread_in_native_trans so we can't use a normal transition
1960 // constructor/destructor pair because they assert on that type of
1961 // transition. We could do something like:
1962 //
1963 // JavaThreadState state = thread_state();
1964 // set_thread_state(_thread_in_vm);
1965 // {
1966 // ThreadBlockInVM tbivm(this);
1967 // java_suspend_self()
1968 // }
1969 // set_thread_state(_thread_in_vm_trans);
1970 // if (safepoint) block;
1971 // set_thread_state(state);
1972 //
1973 // but that is pretty messy. Instead we just go with the way the
1974 // code has worked before and note that this is the only path to
1975 // java_suspend_self that doesn't put the thread in _thread_blocked
1976 // mode.
1978 frame_anchor()->make_walkable(this);
1979 java_suspend_self();
1981 // We might be here for reasons in addition to the self-suspend request
1982 // so check for other async requests.
1983 }
1985 if (check_asyncs) {
1986 check_and_handle_async_exceptions();
1987 }
1988 }
1990 void JavaThread::send_thread_stop(oop java_throwable) {
1991 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
1992 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
1993 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
1995 // Do not throw asynchronous exceptions against the compiler thread
1996 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1997 if (is_Compiler_thread()) return;
1999 // This is a change from JDK 1.1, but JDK 1.2 will also do it:
2000 if (java_throwable->is_a(SystemDictionary::ThreadDeath_klass())) {
2001 java_lang_Thread::set_stillborn(threadObj());
2002 }
2004 {
2005 // Actually throw the Throwable against the target Thread - however
2006 // only if there is no thread death exception installed already.
2007 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2008 // If the topmost frame is a runtime stub, then we are calling into
2009 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2010 // must deoptimize the caller before continuing, as the compiled exception handler table
2011 // may not be valid
2012 if (has_last_Java_frame()) {
2013 frame f = last_frame();
2014 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2015 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2016 RegisterMap reg_map(this, UseBiasedLocking);
2017 frame compiled_frame = f.sender(®_map);
2018 if (compiled_frame.can_be_deoptimized()) {
2019 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2020 }
2021 }
2022 }
2024 // Set async. pending exception in thread.
2025 set_pending_async_exception(java_throwable);
2027 if (TraceExceptions) {
2028 ResourceMark rm;
2029 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2030 }
2031 // for AbortVMOnException flag
2032 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2033 }
2034 }
2037 // Interrupt thread so it will wake up from a potential wait()
2038 Thread::interrupt(this);
2039 }
2041 // External suspension mechanism.
2042 //
2043 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2044 // to any VM_locks and it is at a transition
2045 // Self-suspension will happen on the transition out of the vm.
2046 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2047 //
2048 // Guarantees on return:
2049 // + Target thread will not execute any new bytecode (that's why we need to
2050 // force a safepoint)
2051 // + Target thread will not enter any new monitors
2052 //
2053 void JavaThread::java_suspend() {
2054 { MutexLocker mu(Threads_lock);
2055 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2056 return;
2057 }
2058 }
2060 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2061 if (!is_external_suspend()) {
2062 // a racing resume has cancelled us; bail out now
2063 return;
2064 }
2066 // suspend is done
2067 uint32_t debug_bits = 0;
2068 // Warning: is_ext_suspend_completed() may temporarily drop the
2069 // SR_lock to allow the thread to reach a stable thread state if
2070 // it is currently in a transient thread state.
2071 if (is_ext_suspend_completed(false /* !called_by_wait */,
2072 SuspendRetryDelay, &debug_bits) ) {
2073 return;
2074 }
2075 }
2077 VM_ForceSafepoint vm_suspend;
2078 VMThread::execute(&vm_suspend);
2079 }
2081 // Part II of external suspension.
2082 // A JavaThread self suspends when it detects a pending external suspend
2083 // request. This is usually on transitions. It is also done in places
2084 // where continuing to the next transition would surprise the caller,
2085 // e.g., monitor entry.
2086 //
2087 // Returns the number of times that the thread self-suspended.
2088 //
2089 // Note: DO NOT call java_suspend_self() when you just want to block current
2090 // thread. java_suspend_self() is the second stage of cooperative
2091 // suspension for external suspend requests and should only be used
2092 // to complete an external suspend request.
2093 //
2094 int JavaThread::java_suspend_self() {
2095 int ret = 0;
2097 // we are in the process of exiting so don't suspend
2098 if (is_exiting()) {
2099 clear_external_suspend();
2100 return ret;
2101 }
2103 assert(_anchor.walkable() ||
2104 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2105 "must have walkable stack");
2107 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2109 assert(!this->is_ext_suspended(),
2110 "a thread trying to self-suspend should not already be suspended");
2112 if (this->is_suspend_equivalent()) {
2113 // If we are self-suspending as a result of the lifting of a
2114 // suspend equivalent condition, then the suspend_equivalent
2115 // flag is not cleared until we set the ext_suspended flag so
2116 // that wait_for_ext_suspend_completion() returns consistent
2117 // results.
2118 this->clear_suspend_equivalent();
2119 }
2121 // A racing resume may have cancelled us before we grabbed SR_lock
2122 // above. Or another external suspend request could be waiting for us
2123 // by the time we return from SR_lock()->wait(). The thread
2124 // that requested the suspension may already be trying to walk our
2125 // stack and if we return now, we can change the stack out from under
2126 // it. This would be a "bad thing (TM)" and cause the stack walker
2127 // to crash. We stay self-suspended until there are no more pending
2128 // external suspend requests.
2129 while (is_external_suspend()) {
2130 ret++;
2131 this->set_ext_suspended();
2133 // _ext_suspended flag is cleared by java_resume()
2134 while (is_ext_suspended()) {
2135 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2136 }
2137 }
2139 return ret;
2140 }
2142 #ifdef ASSERT
2143 // verify the JavaThread has not yet been published in the Threads::list, and
2144 // hence doesn't need protection from concurrent access at this stage
2145 void JavaThread::verify_not_published() {
2146 if (!Threads_lock->owned_by_self()) {
2147 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2148 assert( !Threads::includes(this),
2149 "java thread shouldn't have been published yet!");
2150 }
2151 else {
2152 assert( !Threads::includes(this),
2153 "java thread shouldn't have been published yet!");
2154 }
2155 }
2156 #endif
2158 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2159 // progress or when _suspend_flags is non-zero.
2160 // Current thread needs to self-suspend if there is a suspend request and/or
2161 // block if a safepoint is in progress.
2162 // Async exception ISN'T checked.
2163 // Note only the ThreadInVMfromNative transition can call this function
2164 // directly and when thread state is _thread_in_native_trans
2165 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2166 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2168 JavaThread *curJT = JavaThread::current();
2169 bool do_self_suspend = thread->is_external_suspend();
2171 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2173 // If JNIEnv proxies are allowed, don't self-suspend if the target
2174 // thread is not the current thread. In older versions of jdbx, jdbx
2175 // threads could call into the VM with another thread's JNIEnv so we
2176 // can be here operating on behalf of a suspended thread (4432884).
2177 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2178 JavaThreadState state = thread->thread_state();
2180 // We mark this thread_blocked state as a suspend-equivalent so
2181 // that a caller to is_ext_suspend_completed() won't be confused.
2182 // The suspend-equivalent state is cleared by java_suspend_self().
2183 thread->set_suspend_equivalent();
2185 // If the safepoint code sees the _thread_in_native_trans state, it will
2186 // wait until the thread changes to other thread state. There is no
2187 // guarantee on how soon we can obtain the SR_lock and complete the
2188 // self-suspend request. It would be a bad idea to let safepoint wait for
2189 // too long. Temporarily change the state to _thread_blocked to
2190 // let the VM thread know that this thread is ready for GC. The problem
2191 // of changing thread state is that safepoint could happen just after
2192 // java_suspend_self() returns after being resumed, and VM thread will
2193 // see the _thread_blocked state. We must check for safepoint
2194 // after restoring the state and make sure we won't leave while a safepoint
2195 // is in progress.
2196 thread->set_thread_state(_thread_blocked);
2197 thread->java_suspend_self();
2198 thread->set_thread_state(state);
2199 // Make sure new state is seen by VM thread
2200 if (os::is_MP()) {
2201 if (UseMembar) {
2202 // Force a fence between the write above and read below
2203 OrderAccess::fence();
2204 } else {
2205 // Must use this rather than serialization page in particular on Windows
2206 InterfaceSupport::serialize_memory(thread);
2207 }
2208 }
2209 }
2211 if (SafepointSynchronize::do_call_back()) {
2212 // If we are safepointing, then block the caller which may not be
2213 // the same as the target thread (see above).
2214 SafepointSynchronize::block(curJT);
2215 }
2217 if (thread->is_deopt_suspend()) {
2218 thread->clear_deopt_suspend();
2219 RegisterMap map(thread, false);
2220 frame f = thread->last_frame();
2221 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2222 f = f.sender(&map);
2223 }
2224 if (f.id() == thread->must_deopt_id()) {
2225 thread->clear_must_deopt_id();
2226 f.deoptimize(thread);
2227 } else {
2228 fatal("missed deoptimization!");
2229 }
2230 }
2231 }
2233 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2234 // progress or when _suspend_flags is non-zero.
2235 // Current thread needs to self-suspend if there is a suspend request and/or
2236 // block if a safepoint is in progress.
2237 // Also check for pending async exception (not including unsafe access error).
2238 // Note only the native==>VM/Java barriers can call this function and when
2239 // thread state is _thread_in_native_trans.
2240 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2241 check_safepoint_and_suspend_for_native_trans(thread);
2243 if (thread->has_async_exception()) {
2244 // We are in _thread_in_native_trans state, don't handle unsafe
2245 // access error since that may block.
2246 thread->check_and_handle_async_exceptions(false);
2247 }
2248 }
2250 // We need to guarantee the Threads_lock here, since resumes are not
2251 // allowed during safepoint synchronization
2252 // Can only resume from an external suspension
2253 void JavaThread::java_resume() {
2254 assert_locked_or_safepoint(Threads_lock);
2256 // Sanity check: thread is gone, has started exiting or the thread
2257 // was not externally suspended.
2258 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2259 return;
2260 }
2262 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2264 clear_external_suspend();
2266 if (is_ext_suspended()) {
2267 clear_ext_suspended();
2268 SR_lock()->notify_all();
2269 }
2270 }
2272 void JavaThread::create_stack_guard_pages() {
2273 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2274 address low_addr = stack_base() - stack_size();
2275 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2277 int allocate = os::allocate_stack_guard_pages();
2278 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2280 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2281 warning("Attempt to allocate stack guard pages failed.");
2282 return;
2283 }
2285 if (os::guard_memory((char *) low_addr, len)) {
2286 _stack_guard_state = stack_guard_enabled;
2287 } else {
2288 warning("Attempt to protect stack guard pages failed.");
2289 if (os::uncommit_memory((char *) low_addr, len)) {
2290 warning("Attempt to deallocate stack guard pages failed.");
2291 }
2292 }
2293 }
2295 void JavaThread::remove_stack_guard_pages() {
2296 if (_stack_guard_state == stack_guard_unused) return;
2297 address low_addr = stack_base() - stack_size();
2298 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2300 if (os::allocate_stack_guard_pages()) {
2301 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2302 _stack_guard_state = stack_guard_unused;
2303 } else {
2304 warning("Attempt to deallocate stack guard pages failed.");
2305 }
2306 } else {
2307 if (_stack_guard_state == stack_guard_unused) return;
2308 if (os::unguard_memory((char *) low_addr, len)) {
2309 _stack_guard_state = stack_guard_unused;
2310 } else {
2311 warning("Attempt to unprotect stack guard pages failed.");
2312 }
2313 }
2314 }
2316 void JavaThread::enable_stack_yellow_zone() {
2317 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2318 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2320 // The base notation is from the stacks point of view, growing downward.
2321 // We need to adjust it to work correctly with guard_memory()
2322 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2324 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2325 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2327 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2328 _stack_guard_state = stack_guard_enabled;
2329 } else {
2330 warning("Attempt to guard stack yellow zone failed.");
2331 }
2332 enable_register_stack_guard();
2333 }
2335 void JavaThread::disable_stack_yellow_zone() {
2336 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2337 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2339 // Simply return if called for a thread that does not use guard pages.
2340 if (_stack_guard_state == stack_guard_unused) return;
2342 // The base notation is from the stacks point of view, growing downward.
2343 // We need to adjust it to work correctly with guard_memory()
2344 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2346 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2347 _stack_guard_state = stack_guard_yellow_disabled;
2348 } else {
2349 warning("Attempt to unguard stack yellow zone failed.");
2350 }
2351 disable_register_stack_guard();
2352 }
2354 void JavaThread::enable_stack_red_zone() {
2355 // The base notation is from the stacks point of view, growing downward.
2356 // We need to adjust it to work correctly with guard_memory()
2357 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2358 address base = stack_red_zone_base() - stack_red_zone_size();
2360 guarantee(base < stack_base(),"Error calculating stack red zone");
2361 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2363 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2364 warning("Attempt to guard stack red zone failed.");
2365 }
2366 }
2368 void JavaThread::disable_stack_red_zone() {
2369 // The base notation is from the stacks point of view, growing downward.
2370 // We need to adjust it to work correctly with guard_memory()
2371 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2372 address base = stack_red_zone_base() - stack_red_zone_size();
2373 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2374 warning("Attempt to unguard stack red zone failed.");
2375 }
2376 }
2378 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2379 // ignore is there is no stack
2380 if (!has_last_Java_frame()) return;
2381 // traverse the stack frames. Starts from top frame.
2382 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2383 frame* fr = fst.current();
2384 f(fr, fst.register_map());
2385 }
2386 }
2389 #ifndef PRODUCT
2390 // Deoptimization
2391 // Function for testing deoptimization
2392 void JavaThread::deoptimize() {
2393 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2394 StackFrameStream fst(this, UseBiasedLocking);
2395 bool deopt = false; // Dump stack only if a deopt actually happens.
2396 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2397 // Iterate over all frames in the thread and deoptimize
2398 for(; !fst.is_done(); fst.next()) {
2399 if(fst.current()->can_be_deoptimized()) {
2401 if (only_at) {
2402 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2403 // consists of comma or carriage return separated numbers so
2404 // search for the current bci in that string.
2405 address pc = fst.current()->pc();
2406 nmethod* nm = (nmethod*) fst.current()->cb();
2407 ScopeDesc* sd = nm->scope_desc_at( pc);
2408 char buffer[8];
2409 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2410 size_t len = strlen(buffer);
2411 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2412 while (found != NULL) {
2413 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2414 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2415 // Check that the bci found is bracketed by terminators.
2416 break;
2417 }
2418 found = strstr(found + 1, buffer);
2419 }
2420 if (!found) {
2421 continue;
2422 }
2423 }
2425 if (DebugDeoptimization && !deopt) {
2426 deopt = true; // One-time only print before deopt
2427 tty->print_cr("[BEFORE Deoptimization]");
2428 trace_frames();
2429 trace_stack();
2430 }
2431 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2432 }
2433 }
2435 if (DebugDeoptimization && deopt) {
2436 tty->print_cr("[AFTER Deoptimization]");
2437 trace_frames();
2438 }
2439 }
2442 // Make zombies
2443 void JavaThread::make_zombies() {
2444 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2445 if (fst.current()->can_be_deoptimized()) {
2446 // it is a Java nmethod
2447 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2448 nm->make_not_entrant();
2449 }
2450 }
2451 }
2452 #endif // PRODUCT
2455 void JavaThread::deoptimized_wrt_marked_nmethods() {
2456 if (!has_last_Java_frame()) return;
2457 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2458 StackFrameStream fst(this, UseBiasedLocking);
2459 for(; !fst.is_done(); fst.next()) {
2460 if (fst.current()->should_be_deoptimized()) {
2461 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2462 }
2463 }
2464 }
2467 // GC support
2468 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2470 void JavaThread::gc_epilogue() {
2471 frames_do(frame_gc_epilogue);
2472 }
2475 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2477 void JavaThread::gc_prologue() {
2478 frames_do(frame_gc_prologue);
2479 }
2481 // If the caller is a NamedThread, then remember, in the current scope,
2482 // the given JavaThread in its _processed_thread field.
2483 class RememberProcessedThread: public StackObj {
2484 NamedThread* _cur_thr;
2485 public:
2486 RememberProcessedThread(JavaThread* jthr) {
2487 Thread* thread = Thread::current();
2488 if (thread->is_Named_thread()) {
2489 _cur_thr = (NamedThread *)thread;
2490 _cur_thr->set_processed_thread(jthr);
2491 } else {
2492 _cur_thr = NULL;
2493 }
2494 }
2496 ~RememberProcessedThread() {
2497 if (_cur_thr) {
2498 _cur_thr->set_processed_thread(NULL);
2499 }
2500 }
2501 };
2503 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2504 // Verify that the deferred card marks have been flushed.
2505 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2507 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2508 // since there may be more than one thread using each ThreadProfiler.
2510 // Traverse the GCHandles
2511 Thread::oops_do(f, cf);
2513 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2514 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2516 if (has_last_Java_frame()) {
2517 // Record JavaThread to GC thread
2518 RememberProcessedThread rpt(this);
2520 // Traverse the privileged stack
2521 if (_privileged_stack_top != NULL) {
2522 _privileged_stack_top->oops_do(f);
2523 }
2525 // traverse the registered growable array
2526 if (_array_for_gc != NULL) {
2527 for (int index = 0; index < _array_for_gc->length(); index++) {
2528 f->do_oop(_array_for_gc->adr_at(index));
2529 }
2530 }
2532 // Traverse the monitor chunks
2533 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2534 chunk->oops_do(f);
2535 }
2537 // Traverse the execution stack
2538 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2539 fst.current()->oops_do(f, cf, fst.register_map());
2540 }
2541 }
2543 // callee_target is never live across a gc point so NULL it here should
2544 // it still contain a methdOop.
2546 set_callee_target(NULL);
2548 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2549 // If we have deferred set_locals there might be oops waiting to be
2550 // written
2551 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2552 if (list != NULL) {
2553 for (int i = 0; i < list->length(); i++) {
2554 list->at(i)->oops_do(f);
2555 }
2556 }
2558 // Traverse instance variables at the end since the GC may be moving things
2559 // around using this function
2560 f->do_oop((oop*) &_threadObj);
2561 f->do_oop((oop*) &_vm_result);
2562 f->do_oop((oop*) &_vm_result_2);
2563 f->do_oop((oop*) &_exception_oop);
2564 f->do_oop((oop*) &_pending_async_exception);
2566 if (jvmti_thread_state() != NULL) {
2567 jvmti_thread_state()->oops_do(f);
2568 }
2569 }
2571 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2572 Thread::nmethods_do(cf); // (super method is a no-op)
2574 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2575 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2577 if (has_last_Java_frame()) {
2578 // Traverse the execution stack
2579 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2580 fst.current()->nmethods_do(cf);
2581 }
2582 }
2583 }
2585 // Printing
2586 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2587 switch (_thread_state) {
2588 case _thread_uninitialized: return "_thread_uninitialized";
2589 case _thread_new: return "_thread_new";
2590 case _thread_new_trans: return "_thread_new_trans";
2591 case _thread_in_native: return "_thread_in_native";
2592 case _thread_in_native_trans: return "_thread_in_native_trans";
2593 case _thread_in_vm: return "_thread_in_vm";
2594 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2595 case _thread_in_Java: return "_thread_in_Java";
2596 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2597 case _thread_blocked: return "_thread_blocked";
2598 case _thread_blocked_trans: return "_thread_blocked_trans";
2599 default: return "unknown thread state";
2600 }
2601 }
2603 #ifndef PRODUCT
2604 void JavaThread::print_thread_state_on(outputStream *st) const {
2605 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2606 };
2607 void JavaThread::print_thread_state() const {
2608 print_thread_state_on(tty);
2609 };
2610 #endif // PRODUCT
2612 // Called by Threads::print() for VM_PrintThreads operation
2613 void JavaThread::print_on(outputStream *st) const {
2614 st->print("\"%s\" ", get_thread_name());
2615 oop thread_oop = threadObj();
2616 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2617 Thread::print_on(st);
2618 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2619 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2620 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2621 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2622 }
2623 #ifndef PRODUCT
2624 print_thread_state_on(st);
2625 _safepoint_state->print_on(st);
2626 #endif // PRODUCT
2627 }
2629 // Called by fatal error handler. The difference between this and
2630 // JavaThread::print() is that we can't grab lock or allocate memory.
2631 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2632 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2633 oop thread_obj = threadObj();
2634 if (thread_obj != NULL) {
2635 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2636 }
2637 st->print(" [");
2638 st->print("%s", _get_thread_state_name(_thread_state));
2639 if (osthread()) {
2640 st->print(", id=%d", osthread()->thread_id());
2641 }
2642 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2643 _stack_base - _stack_size, _stack_base);
2644 st->print("]");
2645 return;
2646 }
2648 // Verification
2650 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2652 void JavaThread::verify() {
2653 // Verify oops in the thread.
2654 oops_do(&VerifyOopClosure::verify_oop, NULL);
2656 // Verify the stack frames.
2657 frames_do(frame_verify);
2658 }
2660 // CR 6300358 (sub-CR 2137150)
2661 // Most callers of this method assume that it can't return NULL but a
2662 // thread may not have a name whilst it is in the process of attaching to
2663 // the VM - see CR 6412693, and there are places where a JavaThread can be
2664 // seen prior to having it's threadObj set (eg JNI attaching threads and
2665 // if vm exit occurs during initialization). These cases can all be accounted
2666 // for such that this method never returns NULL.
2667 const char* JavaThread::get_thread_name() const {
2668 #ifdef ASSERT
2669 // early safepoints can hit while current thread does not yet have TLS
2670 if (!SafepointSynchronize::is_at_safepoint()) {
2671 Thread *cur = Thread::current();
2672 if (!(cur->is_Java_thread() && cur == this)) {
2673 // Current JavaThreads are allowed to get their own name without
2674 // the Threads_lock.
2675 assert_locked_or_safepoint(Threads_lock);
2676 }
2677 }
2678 #endif // ASSERT
2679 return get_thread_name_string();
2680 }
2682 // Returns a non-NULL representation of this thread's name, or a suitable
2683 // descriptive string if there is no set name
2684 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2685 const char* name_str;
2686 oop thread_obj = threadObj();
2687 if (thread_obj != NULL) {
2688 typeArrayOop name = java_lang_Thread::name(thread_obj);
2689 if (name != NULL) {
2690 if (buf == NULL) {
2691 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2692 }
2693 else {
2694 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2695 }
2696 }
2697 else if (is_attaching()) { // workaround for 6412693 - see 6404306
2698 name_str = "<no-name - thread is attaching>";
2699 }
2700 else {
2701 name_str = Thread::name();
2702 }
2703 }
2704 else {
2705 name_str = Thread::name();
2706 }
2707 assert(name_str != NULL, "unexpected NULL thread name");
2708 return name_str;
2709 }
2712 const char* JavaThread::get_threadgroup_name() const {
2713 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2714 oop thread_obj = threadObj();
2715 if (thread_obj != NULL) {
2716 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2717 if (thread_group != NULL) {
2718 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2719 // ThreadGroup.name can be null
2720 if (name != NULL) {
2721 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2722 return str;
2723 }
2724 }
2725 }
2726 return NULL;
2727 }
2729 const char* JavaThread::get_parent_name() const {
2730 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2731 oop thread_obj = threadObj();
2732 if (thread_obj != NULL) {
2733 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2734 if (thread_group != NULL) {
2735 oop parent = java_lang_ThreadGroup::parent(thread_group);
2736 if (parent != NULL) {
2737 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2738 // ThreadGroup.name can be null
2739 if (name != NULL) {
2740 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2741 return str;
2742 }
2743 }
2744 }
2745 }
2746 return NULL;
2747 }
2749 ThreadPriority JavaThread::java_priority() const {
2750 oop thr_oop = threadObj();
2751 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2752 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2753 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2754 return priority;
2755 }
2757 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2759 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2760 // Link Java Thread object <-> C++ Thread
2762 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2763 // and put it into a new Handle. The Handle "thread_oop" can then
2764 // be used to pass the C++ thread object to other methods.
2766 // Set the Java level thread object (jthread) field of the
2767 // new thread (a JavaThread *) to C++ thread object using the
2768 // "thread_oop" handle.
2770 // Set the thread field (a JavaThread *) of the
2771 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2773 Handle thread_oop(Thread::current(),
2774 JNIHandles::resolve_non_null(jni_thread));
2775 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2776 "must be initialized");
2777 set_threadObj(thread_oop());
2778 java_lang_Thread::set_thread(thread_oop(), this);
2780 if (prio == NoPriority) {
2781 prio = java_lang_Thread::priority(thread_oop());
2782 assert(prio != NoPriority, "A valid priority should be present");
2783 }
2785 // Push the Java priority down to the native thread; needs Threads_lock
2786 Thread::set_priority(this, prio);
2788 // Add the new thread to the Threads list and set it in motion.
2789 // We must have threads lock in order to call Threads::add.
2790 // It is crucial that we do not block before the thread is
2791 // added to the Threads list for if a GC happens, then the java_thread oop
2792 // will not be visited by GC.
2793 Threads::add(this);
2794 }
2796 oop JavaThread::current_park_blocker() {
2797 // Support for JSR-166 locks
2798 oop thread_oop = threadObj();
2799 if (thread_oop != NULL &&
2800 JDK_Version::current().supports_thread_park_blocker()) {
2801 return java_lang_Thread::park_blocker(thread_oop);
2802 }
2803 return NULL;
2804 }
2807 void JavaThread::print_stack_on(outputStream* st) {
2808 if (!has_last_Java_frame()) return;
2809 ResourceMark rm;
2810 HandleMark hm;
2812 RegisterMap reg_map(this);
2813 vframe* start_vf = last_java_vframe(®_map);
2814 int count = 0;
2815 for (vframe* f = start_vf; f; f = f->sender() ) {
2816 if (f->is_java_frame()) {
2817 javaVFrame* jvf = javaVFrame::cast(f);
2818 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2820 // Print out lock information
2821 if (JavaMonitorsInStackTrace) {
2822 jvf->print_lock_info_on(st, count);
2823 }
2824 } else {
2825 // Ignore non-Java frames
2826 }
2828 // Bail-out case for too deep stacks
2829 count++;
2830 if (MaxJavaStackTraceDepth == count) return;
2831 }
2832 }
2835 // JVMTI PopFrame support
2836 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2837 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2838 if (in_bytes(size_in_bytes) != 0) {
2839 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2840 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2841 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2842 }
2843 }
2845 void* JavaThread::popframe_preserved_args() {
2846 return _popframe_preserved_args;
2847 }
2849 ByteSize JavaThread::popframe_preserved_args_size() {
2850 return in_ByteSize(_popframe_preserved_args_size);
2851 }
2853 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2854 int sz = in_bytes(popframe_preserved_args_size());
2855 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2856 return in_WordSize(sz / wordSize);
2857 }
2859 void JavaThread::popframe_free_preserved_args() {
2860 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2861 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2862 _popframe_preserved_args = NULL;
2863 _popframe_preserved_args_size = 0;
2864 }
2866 #ifndef PRODUCT
2868 void JavaThread::trace_frames() {
2869 tty->print_cr("[Describe stack]");
2870 int frame_no = 1;
2871 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2872 tty->print(" %d. ", frame_no++);
2873 fst.current()->print_value_on(tty,this);
2874 tty->cr();
2875 }
2876 }
2879 void JavaThread::trace_stack_from(vframe* start_vf) {
2880 ResourceMark rm;
2881 int vframe_no = 1;
2882 for (vframe* f = start_vf; f; f = f->sender() ) {
2883 if (f->is_java_frame()) {
2884 javaVFrame::cast(f)->print_activation(vframe_no++);
2885 } else {
2886 f->print();
2887 }
2888 if (vframe_no > StackPrintLimit) {
2889 tty->print_cr("...<more frames>...");
2890 return;
2891 }
2892 }
2893 }
2896 void JavaThread::trace_stack() {
2897 if (!has_last_Java_frame()) return;
2898 ResourceMark rm;
2899 HandleMark hm;
2900 RegisterMap reg_map(this);
2901 trace_stack_from(last_java_vframe(®_map));
2902 }
2905 #endif // PRODUCT
2908 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2909 assert(reg_map != NULL, "a map must be given");
2910 frame f = last_frame();
2911 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
2912 if (vf->is_java_frame()) return javaVFrame::cast(vf);
2913 }
2914 return NULL;
2915 }
2918 klassOop JavaThread::security_get_caller_class(int depth) {
2919 vframeStream vfst(this);
2920 vfst.security_get_caller_frame(depth);
2921 if (!vfst.at_end()) {
2922 return vfst.method()->method_holder();
2923 }
2924 return NULL;
2925 }
2927 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
2928 assert(thread->is_Compiler_thread(), "must be compiler thread");
2929 CompileBroker::compiler_thread_loop();
2930 }
2932 // Create a CompilerThread
2933 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
2934 : JavaThread(&compiler_thread_entry) {
2935 _env = NULL;
2936 _log = NULL;
2937 _task = NULL;
2938 _queue = queue;
2939 _counters = counters;
2940 _buffer_blob = NULL;
2942 #ifndef PRODUCT
2943 _ideal_graph_printer = NULL;
2944 #endif
2945 }
2948 // ======= Threads ========
2950 // The Threads class links together all active threads, and provides
2951 // operations over all threads. It is protected by its own Mutex
2952 // lock, which is also used in other contexts to protect thread
2953 // operations from having the thread being operated on from exiting
2954 // and going away unexpectedly (e.g., safepoint synchronization)
2956 JavaThread* Threads::_thread_list = NULL;
2957 int Threads::_number_of_threads = 0;
2958 int Threads::_number_of_non_daemon_threads = 0;
2959 int Threads::_return_code = 0;
2960 size_t JavaThread::_stack_size_at_create = 0;
2962 // All JavaThreads
2963 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
2965 void os_stream();
2967 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
2968 void Threads::threads_do(ThreadClosure* tc) {
2969 assert_locked_or_safepoint(Threads_lock);
2970 // ALL_JAVA_THREADS iterates through all JavaThreads
2971 ALL_JAVA_THREADS(p) {
2972 tc->do_thread(p);
2973 }
2974 // Someday we could have a table or list of all non-JavaThreads.
2975 // For now, just manually iterate through them.
2976 tc->do_thread(VMThread::vm_thread());
2977 Universe::heap()->gc_threads_do(tc);
2978 WatcherThread *wt = WatcherThread::watcher_thread();
2979 // Strictly speaking, the following NULL check isn't sufficient to make sure
2980 // the data for WatcherThread is still valid upon being examined. However,
2981 // considering that WatchThread terminates when the VM is on the way to
2982 // exit at safepoint, the chance of the above is extremely small. The right
2983 // way to prevent termination of WatcherThread would be to acquire
2984 // Terminator_lock, but we can't do that without violating the lock rank
2985 // checking in some cases.
2986 if (wt != NULL)
2987 tc->do_thread(wt);
2989 // If CompilerThreads ever become non-JavaThreads, add them here
2990 }
2992 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
2994 extern void JDK_Version_init();
2996 // Check version
2997 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
2999 // Initialize the output stream module
3000 ostream_init();
3002 // Process java launcher properties.
3003 Arguments::process_sun_java_launcher_properties(args);
3005 // Initialize the os module before using TLS
3006 os::init();
3008 // Initialize system properties.
3009 Arguments::init_system_properties();
3011 // So that JDK version can be used as a discrimintor when parsing arguments
3012 JDK_Version_init();
3014 // Update/Initialize System properties after JDK version number is known
3015 Arguments::init_version_specific_system_properties();
3017 // Parse arguments
3018 jint parse_result = Arguments::parse(args);
3019 if (parse_result != JNI_OK) return parse_result;
3021 if (PauseAtStartup) {
3022 os::pause();
3023 }
3025 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3027 // Record VM creation timing statistics
3028 TraceVmCreationTime create_vm_timer;
3029 create_vm_timer.start();
3031 // Timing (must come after argument parsing)
3032 TraceTime timer("Create VM", TraceStartupTime);
3034 // Initialize the os module after parsing the args
3035 jint os_init_2_result = os::init_2();
3036 if (os_init_2_result != JNI_OK) return os_init_2_result;
3038 // Initialize output stream logging
3039 ostream_init_log();
3041 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3042 // Must be before create_vm_init_agents()
3043 if (Arguments::init_libraries_at_startup()) {
3044 convert_vm_init_libraries_to_agents();
3045 }
3047 // Launch -agentlib/-agentpath and converted -Xrun agents
3048 if (Arguments::init_agents_at_startup()) {
3049 create_vm_init_agents();
3050 }
3052 // Initialize Threads state
3053 _thread_list = NULL;
3054 _number_of_threads = 0;
3055 _number_of_non_daemon_threads = 0;
3057 // Initialize TLS
3058 ThreadLocalStorage::init();
3060 // Initialize global data structures and create system classes in heap
3061 vm_init_globals();
3063 // Attach the main thread to this os thread
3064 JavaThread* main_thread = new JavaThread();
3065 main_thread->set_thread_state(_thread_in_vm);
3066 // must do this before set_active_handles and initialize_thread_local_storage
3067 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3068 // change the stack size recorded here to one based on the java thread
3069 // stacksize. This adjusted size is what is used to figure the placement
3070 // of the guard pages.
3071 main_thread->record_stack_base_and_size();
3072 main_thread->initialize_thread_local_storage();
3074 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3076 if (!main_thread->set_as_starting_thread()) {
3077 vm_shutdown_during_initialization(
3078 "Failed necessary internal allocation. Out of swap space");
3079 delete main_thread;
3080 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3081 return JNI_ENOMEM;
3082 }
3084 // Enable guard page *after* os::create_main_thread(), otherwise it would
3085 // crash Linux VM, see notes in os_linux.cpp.
3086 main_thread->create_stack_guard_pages();
3088 // Initialize Java-Level synchronization subsystem
3089 ObjectMonitor::Initialize() ;
3091 // Initialize global modules
3092 jint status = init_globals();
3093 if (status != JNI_OK) {
3094 delete main_thread;
3095 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3096 return status;
3097 }
3099 // Should be done after the heap is fully created
3100 main_thread->cache_global_variables();
3102 HandleMark hm;
3104 { MutexLocker mu(Threads_lock);
3105 Threads::add(main_thread);
3106 }
3108 // Any JVMTI raw monitors entered in onload will transition into
3109 // real raw monitor. VM is setup enough here for raw monitor enter.
3110 JvmtiExport::transition_pending_onload_raw_monitors();
3112 if (VerifyBeforeGC &&
3113 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3114 Universe::heap()->prepare_for_verify();
3115 Universe::verify(); // make sure we're starting with a clean slate
3116 }
3118 // Create the VMThread
3119 { TraceTime timer("Start VMThread", TraceStartupTime);
3120 VMThread::create();
3121 Thread* vmthread = VMThread::vm_thread();
3123 if (!os::create_thread(vmthread, os::vm_thread))
3124 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3126 // Wait for the VM thread to become ready, and VMThread::run to initialize
3127 // Monitors can have spurious returns, must always check another state flag
3128 {
3129 MutexLocker ml(Notify_lock);
3130 os::start_thread(vmthread);
3131 while (vmthread->active_handles() == NULL) {
3132 Notify_lock->wait();
3133 }
3134 }
3135 }
3137 assert (Universe::is_fully_initialized(), "not initialized");
3138 EXCEPTION_MARK;
3140 // At this point, the Universe is initialized, but we have not executed
3141 // any byte code. Now is a good time (the only time) to dump out the
3142 // internal state of the JVM for sharing.
3144 if (DumpSharedSpaces) {
3145 Universe::heap()->preload_and_dump(CHECK_0);
3146 ShouldNotReachHere();
3147 }
3149 // Always call even when there are not JVMTI environments yet, since environments
3150 // may be attached late and JVMTI must track phases of VM execution
3151 JvmtiExport::enter_start_phase();
3153 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3154 JvmtiExport::post_vm_start();
3156 {
3157 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3159 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3160 create_vm_init_libraries();
3161 }
3163 if (InitializeJavaLangString) {
3164 initialize_class(vmSymbolHandles::java_lang_String(), CHECK_0);
3165 } else {
3166 warning("java.lang.String not initialized");
3167 }
3169 if (AggressiveOpts) {
3170 {
3171 // Forcibly initialize java/util/HashMap and mutate the private
3172 // static final "frontCacheEnabled" field before we start creating instances
3173 #ifdef ASSERT
3174 klassOop tmp_k = SystemDictionary::find(vmSymbolHandles::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3175 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3176 #endif
3177 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbolHandles::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3178 KlassHandle k = KlassHandle(THREAD, k_o);
3179 guarantee(k.not_null(), "Must find java/util/HashMap");
3180 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3181 ik->initialize(CHECK_0);
3182 fieldDescriptor fd;
3183 // Possible we might not find this field; if so, don't break
3184 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3185 k()->bool_field_put(fd.offset(), true);
3186 }
3187 }
3189 if (UseStringCache) {
3190 // Forcibly initialize java/lang/StringValue and mutate the private
3191 // static final "stringCacheEnabled" field before we start creating instances
3192 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbolHandles::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3193 // Possible that StringValue isn't present: if so, silently don't break
3194 if (k_o != NULL) {
3195 KlassHandle k = KlassHandle(THREAD, k_o);
3196 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3197 ik->initialize(CHECK_0);
3198 fieldDescriptor fd;
3199 // Possible we might not find this field: if so, silently don't break
3200 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3201 k()->bool_field_put(fd.offset(), true);
3202 }
3203 }
3204 }
3205 }
3207 // Initialize java_lang.System (needed before creating the thread)
3208 if (InitializeJavaLangSystem) {
3209 initialize_class(vmSymbolHandles::java_lang_System(), CHECK_0);
3210 initialize_class(vmSymbolHandles::java_lang_ThreadGroup(), CHECK_0);
3211 Handle thread_group = create_initial_thread_group(CHECK_0);
3212 Universe::set_main_thread_group(thread_group());
3213 initialize_class(vmSymbolHandles::java_lang_Thread(), CHECK_0);
3214 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3215 main_thread->set_threadObj(thread_object);
3216 // Set thread status to running since main thread has
3217 // been started and running.
3218 java_lang_Thread::set_thread_status(thread_object,
3219 java_lang_Thread::RUNNABLE);
3221 // The VM preresolve methods to these classes. Make sure that get initialized
3222 initialize_class(vmSymbolHandles::java_lang_reflect_Method(), CHECK_0);
3223 initialize_class(vmSymbolHandles::java_lang_ref_Finalizer(), CHECK_0);
3224 // The VM creates & returns objects of this class. Make sure it's initialized.
3225 initialize_class(vmSymbolHandles::java_lang_Class(), CHECK_0);
3226 call_initializeSystemClass(CHECK_0);
3227 } else {
3228 warning("java.lang.System not initialized");
3229 }
3231 // an instance of OutOfMemory exception has been allocated earlier
3232 if (InitializeJavaLangExceptionsErrors) {
3233 initialize_class(vmSymbolHandles::java_lang_OutOfMemoryError(), CHECK_0);
3234 initialize_class(vmSymbolHandles::java_lang_NullPointerException(), CHECK_0);
3235 initialize_class(vmSymbolHandles::java_lang_ClassCastException(), CHECK_0);
3236 initialize_class(vmSymbolHandles::java_lang_ArrayStoreException(), CHECK_0);
3237 initialize_class(vmSymbolHandles::java_lang_ArithmeticException(), CHECK_0);
3238 initialize_class(vmSymbolHandles::java_lang_StackOverflowError(), CHECK_0);
3239 initialize_class(vmSymbolHandles::java_lang_IllegalMonitorStateException(), CHECK_0);
3240 } else {
3241 warning("java.lang.OutOfMemoryError has not been initialized");
3242 warning("java.lang.NullPointerException has not been initialized");
3243 warning("java.lang.ClassCastException has not been initialized");
3244 warning("java.lang.ArrayStoreException has not been initialized");
3245 warning("java.lang.ArithmeticException has not been initialized");
3246 warning("java.lang.StackOverflowError has not been initialized");
3247 }
3248 }
3250 // See : bugid 4211085.
3251 // Background : the static initializer of java.lang.Compiler tries to read
3252 // property"java.compiler" and read & write property "java.vm.info".
3253 // When a security manager is installed through the command line
3254 // option "-Djava.security.manager", the above properties are not
3255 // readable and the static initializer for java.lang.Compiler fails
3256 // resulting in a NoClassDefFoundError. This can happen in any
3257 // user code which calls methods in java.lang.Compiler.
3258 // Hack : the hack is to pre-load and initialize this class, so that only
3259 // system domains are on the stack when the properties are read.
3260 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3261 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3262 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3263 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3264 // Once that is done, we should remove this hack.
3265 initialize_class(vmSymbolHandles::java_lang_Compiler(), CHECK_0);
3267 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3268 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3269 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3270 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3271 // This should also be taken out as soon as 4211383 gets fixed.
3272 reset_vm_info_property(CHECK_0);
3274 quicken_jni_functions();
3276 // Set flag that basic initialization has completed. Used by exceptions and various
3277 // debug stuff, that does not work until all basic classes have been initialized.
3278 set_init_completed();
3280 HS_DTRACE_PROBE(hotspot, vm__init__end);
3282 // record VM initialization completion time
3283 Management::record_vm_init_completed();
3285 // Compute system loader. Note that this has to occur after set_init_completed, since
3286 // valid exceptions may be thrown in the process.
3287 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3288 // set_init_completed has just been called, causing exceptions not to be shortcut
3289 // anymore. We call vm_exit_during_initialization directly instead.
3290 SystemDictionary::compute_java_system_loader(THREAD);
3291 if (HAS_PENDING_EXCEPTION) {
3292 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3293 }
3295 #ifdef KERNEL
3296 if (JDK_Version::is_gte_jdk17x_version()) {
3297 set_jkernel_boot_classloader_hook(THREAD);
3298 }
3299 #endif // KERNEL
3301 #ifndef SERIALGC
3302 // Support for ConcurrentMarkSweep. This should be cleaned up
3303 // and better encapsulated. The ugly nested if test would go away
3304 // once things are properly refactored. XXX YSR
3305 if (UseConcMarkSweepGC || UseG1GC) {
3306 if (UseConcMarkSweepGC) {
3307 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3308 } else {
3309 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3310 }
3311 if (HAS_PENDING_EXCEPTION) {
3312 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3313 }
3314 }
3315 #endif // SERIALGC
3317 // Always call even when there are not JVMTI environments yet, since environments
3318 // may be attached late and JVMTI must track phases of VM execution
3319 JvmtiExport::enter_live_phase();
3321 // Signal Dispatcher needs to be started before VMInit event is posted
3322 os::signal_init();
3324 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3325 if (!DisableAttachMechanism) {
3326 if (StartAttachListener || AttachListener::init_at_startup()) {
3327 AttachListener::init();
3328 }
3329 }
3331 // Launch -Xrun agents
3332 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3333 // back-end can launch with -Xdebug -Xrunjdwp.
3334 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3335 create_vm_init_libraries();
3336 }
3338 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3339 JvmtiExport::post_vm_initialized();
3341 Chunk::start_chunk_pool_cleaner_task();
3343 // initialize compiler(s)
3344 CompileBroker::compilation_init();
3346 Management::initialize(THREAD);
3347 if (HAS_PENDING_EXCEPTION) {
3348 // management agent fails to start possibly due to
3349 // configuration problem and is responsible for printing
3350 // stack trace if appropriate. Simply exit VM.
3351 vm_exit(1);
3352 }
3354 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3355 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3356 if (MemProfiling) MemProfiler::engage();
3357 StatSampler::engage();
3358 if (CheckJNICalls) JniPeriodicChecker::engage();
3360 BiasedLocking::init();
3362 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3363 call_postVMInitHook(THREAD);
3364 // The Java side of PostVMInitHook.run must deal with all
3365 // exceptions and provide means of diagnosis.
3366 if (HAS_PENDING_EXCEPTION) {
3367 CLEAR_PENDING_EXCEPTION;
3368 }
3369 }
3371 // Start up the WatcherThread if there are any periodic tasks
3372 // NOTE: All PeriodicTasks should be registered by now. If they
3373 // aren't, late joiners might appear to start slowly (we might
3374 // take a while to process their first tick).
3375 if (PeriodicTask::num_tasks() > 0) {
3376 WatcherThread::start();
3377 }
3379 // Give os specific code one last chance to start
3380 os::init_3();
3382 create_vm_timer.end();
3383 return JNI_OK;
3384 }
3386 // type for the Agent_OnLoad and JVM_OnLoad entry points
3387 extern "C" {
3388 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3389 }
3390 // Find a command line agent library and return its entry point for
3391 // -agentlib: -agentpath: -Xrun
3392 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3393 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3394 OnLoadEntry_t on_load_entry = NULL;
3395 void *library = agent->os_lib(); // check if we have looked it up before
3397 if (library == NULL) {
3398 char buffer[JVM_MAXPATHLEN];
3399 char ebuf[1024];
3400 const char *name = agent->name();
3401 const char *msg = "Could not find agent library ";
3403 if (agent->is_absolute_path()) {
3404 library = os::dll_load(name, ebuf, sizeof ebuf);
3405 if (library == NULL) {
3406 const char *sub_msg = " in absolute path, with error: ";
3407 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3408 char *buf = NEW_C_HEAP_ARRAY(char, len);
3409 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3410 // If we can't find the agent, exit.
3411 vm_exit_during_initialization(buf, NULL);
3412 FREE_C_HEAP_ARRAY(char, buf);
3413 }
3414 } else {
3415 // Try to load the agent from the standard dll directory
3416 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3417 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3418 #ifdef KERNEL
3419 // Download instrument dll
3420 if (library == NULL && strcmp(name, "instrument") == 0) {
3421 char *props = Arguments::get_kernel_properties();
3422 char *home = Arguments::get_java_home();
3423 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3424 " sun.jkernel.DownloadManager -download client_jvm";
3425 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3426 char *cmd = NEW_C_HEAP_ARRAY(char, length);
3427 jio_snprintf(cmd, length, fmt, home, props);
3428 int status = os::fork_and_exec(cmd);
3429 FreeHeap(props);
3430 if (status == -1) {
3431 warning(cmd);
3432 vm_exit_during_initialization("fork_and_exec failed: %s",
3433 strerror(errno));
3434 }
3435 FREE_C_HEAP_ARRAY(char, cmd);
3436 // when this comes back the instrument.dll should be where it belongs.
3437 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3438 }
3439 #endif // KERNEL
3440 if (library == NULL) { // Try the local directory
3441 char ns[1] = {0};
3442 os::dll_build_name(buffer, sizeof(buffer), ns, name);
3443 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3444 if (library == NULL) {
3445 const char *sub_msg = " on the library path, with error: ";
3446 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3447 char *buf = NEW_C_HEAP_ARRAY(char, len);
3448 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3449 // If we can't find the agent, exit.
3450 vm_exit_during_initialization(buf, NULL);
3451 FREE_C_HEAP_ARRAY(char, buf);
3452 }
3453 }
3454 }
3455 agent->set_os_lib(library);
3456 }
3458 // Find the OnLoad function.
3459 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3460 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3461 if (on_load_entry != NULL) break;
3462 }
3463 return on_load_entry;
3464 }
3466 // Find the JVM_OnLoad entry point
3467 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3468 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3469 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3470 }
3472 // Find the Agent_OnLoad entry point
3473 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3474 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3475 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3476 }
3478 // For backwards compatibility with -Xrun
3479 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3480 // treated like -agentpath:
3481 // Must be called before agent libraries are created
3482 void Threads::convert_vm_init_libraries_to_agents() {
3483 AgentLibrary* agent;
3484 AgentLibrary* next;
3486 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3487 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3488 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3490 // If there is an JVM_OnLoad function it will get called later,
3491 // otherwise see if there is an Agent_OnLoad
3492 if (on_load_entry == NULL) {
3493 on_load_entry = lookup_agent_on_load(agent);
3494 if (on_load_entry != NULL) {
3495 // switch it to the agent list -- so that Agent_OnLoad will be called,
3496 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3497 Arguments::convert_library_to_agent(agent);
3498 } else {
3499 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3500 }
3501 }
3502 }
3503 }
3505 // Create agents for -agentlib: -agentpath: and converted -Xrun
3506 // Invokes Agent_OnLoad
3507 // Called very early -- before JavaThreads exist
3508 void Threads::create_vm_init_agents() {
3509 extern struct JavaVM_ main_vm;
3510 AgentLibrary* agent;
3512 JvmtiExport::enter_onload_phase();
3513 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3514 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3516 if (on_load_entry != NULL) {
3517 // Invoke the Agent_OnLoad function
3518 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3519 if (err != JNI_OK) {
3520 vm_exit_during_initialization("agent library failed to init", agent->name());
3521 }
3522 } else {
3523 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3524 }
3525 }
3526 JvmtiExport::enter_primordial_phase();
3527 }
3529 extern "C" {
3530 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3531 }
3533 void Threads::shutdown_vm_agents() {
3534 // Send any Agent_OnUnload notifications
3535 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3536 extern struct JavaVM_ main_vm;
3537 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3539 // Find the Agent_OnUnload function.
3540 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3541 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3542 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3544 // Invoke the Agent_OnUnload function
3545 if (unload_entry != NULL) {
3546 JavaThread* thread = JavaThread::current();
3547 ThreadToNativeFromVM ttn(thread);
3548 HandleMark hm(thread);
3549 (*unload_entry)(&main_vm);
3550 break;
3551 }
3552 }
3553 }
3554 }
3556 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3557 // Invokes JVM_OnLoad
3558 void Threads::create_vm_init_libraries() {
3559 extern struct JavaVM_ main_vm;
3560 AgentLibrary* agent;
3562 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3563 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3565 if (on_load_entry != NULL) {
3566 // Invoke the JVM_OnLoad function
3567 JavaThread* thread = JavaThread::current();
3568 ThreadToNativeFromVM ttn(thread);
3569 HandleMark hm(thread);
3570 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3571 if (err != JNI_OK) {
3572 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3573 }
3574 } else {
3575 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3576 }
3577 }
3578 }
3580 // Last thread running calls java.lang.Shutdown.shutdown()
3581 void JavaThread::invoke_shutdown_hooks() {
3582 HandleMark hm(this);
3584 // We could get here with a pending exception, if so clear it now.
3585 if (this->has_pending_exception()) {
3586 this->clear_pending_exception();
3587 }
3589 EXCEPTION_MARK;
3590 klassOop k =
3591 SystemDictionary::resolve_or_null(vmSymbolHandles::java_lang_Shutdown(),
3592 THREAD);
3593 if (k != NULL) {
3594 // SystemDictionary::resolve_or_null will return null if there was
3595 // an exception. If we cannot load the Shutdown class, just don't
3596 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3597 // and finalizers (if runFinalizersOnExit is set) won't be run.
3598 // Note that if a shutdown hook was registered or runFinalizersOnExit
3599 // was called, the Shutdown class would have already been loaded
3600 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3601 instanceKlassHandle shutdown_klass (THREAD, k);
3602 JavaValue result(T_VOID);
3603 JavaCalls::call_static(&result,
3604 shutdown_klass,
3605 vmSymbolHandles::shutdown_method_name(),
3606 vmSymbolHandles::void_method_signature(),
3607 THREAD);
3608 }
3609 CLEAR_PENDING_EXCEPTION;
3610 }
3612 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3613 // the program falls off the end of main(). Another VM exit path is through
3614 // vm_exit() when the program calls System.exit() to return a value or when
3615 // there is a serious error in VM. The two shutdown paths are not exactly
3616 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3617 // and VM_Exit op at VM level.
3618 //
3619 // Shutdown sequence:
3620 // + Wait until we are the last non-daemon thread to execute
3621 // <-- every thing is still working at this moment -->
3622 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3623 // shutdown hooks, run finalizers if finalization-on-exit
3624 // + Call before_exit(), prepare for VM exit
3625 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3626 // currently the only user of this mechanism is File.deleteOnExit())
3627 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3628 // post thread end and vm death events to JVMTI,
3629 // stop signal thread
3630 // + Call JavaThread::exit(), it will:
3631 // > release JNI handle blocks, remove stack guard pages
3632 // > remove this thread from Threads list
3633 // <-- no more Java code from this thread after this point -->
3634 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3635 // the compiler threads at safepoint
3636 // <-- do not use anything that could get blocked by Safepoint -->
3637 // + Disable tracing at JNI/JVM barriers
3638 // + Set _vm_exited flag for threads that are still running native code
3639 // + Delete this thread
3640 // + Call exit_globals()
3641 // > deletes tty
3642 // > deletes PerfMemory resources
3643 // + Return to caller
3645 bool Threads::destroy_vm() {
3646 JavaThread* thread = JavaThread::current();
3648 // Wait until we are the last non-daemon thread to execute
3649 { MutexLocker nu(Threads_lock);
3650 while (Threads::number_of_non_daemon_threads() > 1 )
3651 // This wait should make safepoint checks, wait without a timeout,
3652 // and wait as a suspend-equivalent condition.
3653 //
3654 // Note: If the FlatProfiler is running and this thread is waiting
3655 // for another non-daemon thread to finish, then the FlatProfiler
3656 // is waiting for the external suspend request on this thread to
3657 // complete. wait_for_ext_suspend_completion() will eventually
3658 // timeout, but that takes time. Making this wait a suspend-
3659 // equivalent condition solves that timeout problem.
3660 //
3661 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3662 Mutex::_as_suspend_equivalent_flag);
3663 }
3665 // Hang forever on exit if we are reporting an error.
3666 if (ShowMessageBoxOnError && is_error_reported()) {
3667 os::infinite_sleep();
3668 }
3670 if (JDK_Version::is_jdk12x_version()) {
3671 // We are the last thread running, so check if finalizers should be run.
3672 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3673 HandleMark rm(thread);
3674 Universe::run_finalizers_on_exit();
3675 } else {
3676 // run Java level shutdown hooks
3677 thread->invoke_shutdown_hooks();
3678 }
3680 before_exit(thread);
3682 thread->exit(true);
3684 // Stop VM thread.
3685 {
3686 // 4945125 The vm thread comes to a safepoint during exit.
3687 // GC vm_operations can get caught at the safepoint, and the
3688 // heap is unparseable if they are caught. Grab the Heap_lock
3689 // to prevent this. The GC vm_operations will not be able to
3690 // queue until after the vm thread is dead.
3691 MutexLocker ml(Heap_lock);
3693 VMThread::wait_for_vm_thread_exit();
3694 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3695 VMThread::destroy();
3696 }
3698 // clean up ideal graph printers
3699 #if defined(COMPILER2) && !defined(PRODUCT)
3700 IdealGraphPrinter::clean_up();
3701 #endif
3703 // Now, all Java threads are gone except daemon threads. Daemon threads
3704 // running Java code or in VM are stopped by the Safepoint. However,
3705 // daemon threads executing native code are still running. But they
3706 // will be stopped at native=>Java/VM barriers. Note that we can't
3707 // simply kill or suspend them, as it is inherently deadlock-prone.
3709 #ifndef PRODUCT
3710 // disable function tracing at JNI/JVM barriers
3711 TraceJNICalls = false;
3712 TraceJVMCalls = false;
3713 TraceRuntimeCalls = false;
3714 #endif
3716 VM_Exit::set_vm_exited();
3718 notify_vm_shutdown();
3720 delete thread;
3722 // exit_globals() will delete tty
3723 exit_globals();
3725 return true;
3726 }
3729 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3730 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3731 return is_supported_jni_version(version);
3732 }
3735 jboolean Threads::is_supported_jni_version(jint version) {
3736 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3737 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3738 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3739 return JNI_FALSE;
3740 }
3743 void Threads::add(JavaThread* p, bool force_daemon) {
3744 // The threads lock must be owned at this point
3745 assert_locked_or_safepoint(Threads_lock);
3747 // See the comment for this method in thread.hpp for its purpose and
3748 // why it is called here.
3749 p->initialize_queues();
3750 p->set_next(_thread_list);
3751 _thread_list = p;
3752 _number_of_threads++;
3753 oop threadObj = p->threadObj();
3754 bool daemon = true;
3755 // Bootstrapping problem: threadObj can be null for initial
3756 // JavaThread (or for threads attached via JNI)
3757 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3758 _number_of_non_daemon_threads++;
3759 daemon = false;
3760 }
3762 ThreadService::add_thread(p, daemon);
3764 // Possible GC point.
3765 Events::log("Thread added: " INTPTR_FORMAT, p);
3766 }
3768 void Threads::remove(JavaThread* p) {
3769 // Extra scope needed for Thread_lock, so we can check
3770 // that we do not remove thread without safepoint code notice
3771 { MutexLocker ml(Threads_lock);
3773 assert(includes(p), "p must be present");
3775 JavaThread* current = _thread_list;
3776 JavaThread* prev = NULL;
3778 while (current != p) {
3779 prev = current;
3780 current = current->next();
3781 }
3783 if (prev) {
3784 prev->set_next(current->next());
3785 } else {
3786 _thread_list = p->next();
3787 }
3788 _number_of_threads--;
3789 oop threadObj = p->threadObj();
3790 bool daemon = true;
3791 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3792 _number_of_non_daemon_threads--;
3793 daemon = false;
3795 // Only one thread left, do a notify on the Threads_lock so a thread waiting
3796 // on destroy_vm will wake up.
3797 if (number_of_non_daemon_threads() == 1)
3798 Threads_lock->notify_all();
3799 }
3800 ThreadService::remove_thread(p, daemon);
3802 // Make sure that safepoint code disregard this thread. This is needed since
3803 // the thread might mess around with locks after this point. This can cause it
3804 // to do callbacks into the safepoint code. However, the safepoint code is not aware
3805 // of this thread since it is removed from the queue.
3806 p->set_terminated_value();
3807 } // unlock Threads_lock
3809 // Since Events::log uses a lock, we grab it outside the Threads_lock
3810 Events::log("Thread exited: " INTPTR_FORMAT, p);
3811 }
3813 // Threads_lock must be held when this is called (or must be called during a safepoint)
3814 bool Threads::includes(JavaThread* p) {
3815 assert(Threads_lock->is_locked(), "sanity check");
3816 ALL_JAVA_THREADS(q) {
3817 if (q == p ) {
3818 return true;
3819 }
3820 }
3821 return false;
3822 }
3824 // Operations on the Threads list for GC. These are not explicitly locked,
3825 // but the garbage collector must provide a safe context for them to run.
3826 // In particular, these things should never be called when the Threads_lock
3827 // is held by some other thread. (Note: the Safepoint abstraction also
3828 // uses the Threads_lock to gurantee this property. It also makes sure that
3829 // all threads gets blocked when exiting or starting).
3831 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3832 ALL_JAVA_THREADS(p) {
3833 p->oops_do(f, cf);
3834 }
3835 VMThread::vm_thread()->oops_do(f, cf);
3836 }
3838 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3839 // Introduce a mechanism allowing parallel threads to claim threads as
3840 // root groups. Overhead should be small enough to use all the time,
3841 // even in sequential code.
3842 SharedHeap* sh = SharedHeap::heap();
3843 bool is_par = (sh->n_par_threads() > 0);
3844 int cp = SharedHeap::heap()->strong_roots_parity();
3845 ALL_JAVA_THREADS(p) {
3846 if (p->claim_oops_do(is_par, cp)) {
3847 p->oops_do(f, cf);
3848 }
3849 }
3850 VMThread* vmt = VMThread::vm_thread();
3851 if (vmt->claim_oops_do(is_par, cp))
3852 vmt->oops_do(f, cf);
3853 }
3855 #ifndef SERIALGC
3856 // Used by ParallelScavenge
3857 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
3858 ALL_JAVA_THREADS(p) {
3859 q->enqueue(new ThreadRootsTask(p));
3860 }
3861 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
3862 }
3864 // Used by Parallel Old
3865 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
3866 ALL_JAVA_THREADS(p) {
3867 q->enqueue(new ThreadRootsMarkingTask(p));
3868 }
3869 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
3870 }
3871 #endif // SERIALGC
3873 void Threads::nmethods_do(CodeBlobClosure* cf) {
3874 ALL_JAVA_THREADS(p) {
3875 p->nmethods_do(cf);
3876 }
3877 VMThread::vm_thread()->nmethods_do(cf);
3878 }
3880 void Threads::gc_epilogue() {
3881 ALL_JAVA_THREADS(p) {
3882 p->gc_epilogue();
3883 }
3884 }
3886 void Threads::gc_prologue() {
3887 ALL_JAVA_THREADS(p) {
3888 p->gc_prologue();
3889 }
3890 }
3892 void Threads::deoptimized_wrt_marked_nmethods() {
3893 ALL_JAVA_THREADS(p) {
3894 p->deoptimized_wrt_marked_nmethods();
3895 }
3896 }
3899 // Get count Java threads that are waiting to enter the specified monitor.
3900 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
3901 address monitor, bool doLock) {
3902 assert(doLock || SafepointSynchronize::is_at_safepoint(),
3903 "must grab Threads_lock or be at safepoint");
3904 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3906 int i = 0;
3907 {
3908 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3909 ALL_JAVA_THREADS(p) {
3910 if (p->is_Compiler_thread()) continue;
3912 address pending = (address)p->current_pending_monitor();
3913 if (pending == monitor) { // found a match
3914 if (i < count) result->append(p); // save the first count matches
3915 i++;
3916 }
3917 }
3918 }
3919 return result;
3920 }
3923 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
3924 assert(doLock ||
3925 Threads_lock->owned_by_self() ||
3926 SafepointSynchronize::is_at_safepoint(),
3927 "must grab Threads_lock or be at safepoint");
3929 // NULL owner means not locked so we can skip the search
3930 if (owner == NULL) return NULL;
3932 {
3933 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3934 ALL_JAVA_THREADS(p) {
3935 // first, see if owner is the address of a Java thread
3936 if (owner == (address)p) return p;
3937 }
3938 }
3939 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
3940 if (UseHeavyMonitors) return NULL;
3942 //
3943 // If we didn't find a matching Java thread and we didn't force use of
3944 // heavyweight monitors, then the owner is the stack address of the
3945 // Lock Word in the owning Java thread's stack.
3946 //
3947 JavaThread* the_owner = NULL;
3948 {
3949 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3950 ALL_JAVA_THREADS(q) {
3951 if (q->is_lock_owned(owner)) {
3952 the_owner = q;
3953 break;
3954 }
3955 }
3956 }
3957 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
3958 return the_owner;
3959 }
3961 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3962 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
3963 char buf[32];
3964 st->print_cr(os::local_time_string(buf, sizeof(buf)));
3966 st->print_cr("Full thread dump %s (%s %s):",
3967 Abstract_VM_Version::vm_name(),
3968 Abstract_VM_Version::vm_release(),
3969 Abstract_VM_Version::vm_info_string()
3970 );
3971 st->cr();
3973 #ifndef SERIALGC
3974 // Dump concurrent locks
3975 ConcurrentLocksDump concurrent_locks;
3976 if (print_concurrent_locks) {
3977 concurrent_locks.dump_at_safepoint();
3978 }
3979 #endif // SERIALGC
3981 ALL_JAVA_THREADS(p) {
3982 ResourceMark rm;
3983 p->print_on(st);
3984 if (print_stacks) {
3985 if (internal_format) {
3986 p->trace_stack();
3987 } else {
3988 p->print_stack_on(st);
3989 }
3990 }
3991 st->cr();
3992 #ifndef SERIALGC
3993 if (print_concurrent_locks) {
3994 concurrent_locks.print_locks_on(p, st);
3995 }
3996 #endif // SERIALGC
3997 }
3999 VMThread::vm_thread()->print_on(st);
4000 st->cr();
4001 Universe::heap()->print_gc_threads_on(st);
4002 WatcherThread* wt = WatcherThread::watcher_thread();
4003 if (wt != NULL) wt->print_on(st);
4004 st->cr();
4005 CompileBroker::print_compiler_threads_on(st);
4006 st->flush();
4007 }
4009 // Threads::print_on_error() is called by fatal error handler. It's possible
4010 // that VM is not at safepoint and/or current thread is inside signal handler.
4011 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4012 // memory (even in resource area), it might deadlock the error handler.
4013 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4014 bool found_current = false;
4015 st->print_cr("Java Threads: ( => current thread )");
4016 ALL_JAVA_THREADS(thread) {
4017 bool is_current = (current == thread);
4018 found_current = found_current || is_current;
4020 st->print("%s", is_current ? "=>" : " ");
4022 st->print(PTR_FORMAT, thread);
4023 st->print(" ");
4024 thread->print_on_error(st, buf, buflen);
4025 st->cr();
4026 }
4027 st->cr();
4029 st->print_cr("Other Threads:");
4030 if (VMThread::vm_thread()) {
4031 bool is_current = (current == VMThread::vm_thread());
4032 found_current = found_current || is_current;
4033 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4035 st->print(PTR_FORMAT, VMThread::vm_thread());
4036 st->print(" ");
4037 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4038 st->cr();
4039 }
4040 WatcherThread* wt = WatcherThread::watcher_thread();
4041 if (wt != NULL) {
4042 bool is_current = (current == wt);
4043 found_current = found_current || is_current;
4044 st->print("%s", is_current ? "=>" : " ");
4046 st->print(PTR_FORMAT, wt);
4047 st->print(" ");
4048 wt->print_on_error(st, buf, buflen);
4049 st->cr();
4050 }
4051 if (!found_current) {
4052 st->cr();
4053 st->print("=>" PTR_FORMAT " (exited) ", current);
4054 current->print_on_error(st, buf, buflen);
4055 st->cr();
4056 }
4057 }
4059 // Internal SpinLock and Mutex
4060 // Based on ParkEvent
4062 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4063 //
4064 // We employ SpinLocks _only for low-contention, fixed-length
4065 // short-duration critical sections where we're concerned
4066 // about native mutex_t or HotSpot Mutex:: latency.
4067 // The mux construct provides a spin-then-block mutual exclusion
4068 // mechanism.
4069 //
4070 // Testing has shown that contention on the ListLock guarding gFreeList
4071 // is common. If we implement ListLock as a simple SpinLock it's common
4072 // for the JVM to devolve to yielding with little progress. This is true
4073 // despite the fact that the critical sections protected by ListLock are
4074 // extremely short.
4075 //
4076 // TODO-FIXME: ListLock should be of type SpinLock.
4077 // We should make this a 1st-class type, integrated into the lock
4078 // hierarchy as leaf-locks. Critically, the SpinLock structure
4079 // should have sufficient padding to avoid false-sharing and excessive
4080 // cache-coherency traffic.
4083 typedef volatile int SpinLockT ;
4085 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4086 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4087 return ; // normal fast-path return
4088 }
4090 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4091 TEVENT (SpinAcquire - ctx) ;
4092 int ctr = 0 ;
4093 int Yields = 0 ;
4094 for (;;) {
4095 while (*adr != 0) {
4096 ++ctr ;
4097 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4098 if (Yields > 5) {
4099 // Consider using a simple NakedSleep() instead.
4100 // Then SpinAcquire could be called by non-JVM threads
4101 Thread::current()->_ParkEvent->park(1) ;
4102 } else {
4103 os::NakedYield() ;
4104 ++Yields ;
4105 }
4106 } else {
4107 SpinPause() ;
4108 }
4109 }
4110 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4111 }
4112 }
4114 void Thread::SpinRelease (volatile int * adr) {
4115 assert (*adr != 0, "invariant") ;
4116 OrderAccess::fence() ; // guarantee at least release consistency.
4117 // Roach-motel semantics.
4118 // It's safe if subsequent LDs and STs float "up" into the critical section,
4119 // but prior LDs and STs within the critical section can't be allowed
4120 // to reorder or float past the ST that releases the lock.
4121 *adr = 0 ;
4122 }
4124 // muxAcquire and muxRelease:
4125 //
4126 // * muxAcquire and muxRelease support a single-word lock-word construct.
4127 // The LSB of the word is set IFF the lock is held.
4128 // The remainder of the word points to the head of a singly-linked list
4129 // of threads blocked on the lock.
4130 //
4131 // * The current implementation of muxAcquire-muxRelease uses its own
4132 // dedicated Thread._MuxEvent instance. If we're interested in
4133 // minimizing the peak number of extant ParkEvent instances then
4134 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4135 // as certain invariants were satisfied. Specifically, care would need
4136 // to be taken with regards to consuming unpark() "permits".
4137 // A safe rule of thumb is that a thread would never call muxAcquire()
4138 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4139 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4140 // consume an unpark() permit intended for monitorenter, for instance.
4141 // One way around this would be to widen the restricted-range semaphore
4142 // implemented in park(). Another alternative would be to provide
4143 // multiple instances of the PlatformEvent() for each thread. One
4144 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4145 //
4146 // * Usage:
4147 // -- Only as leaf locks
4148 // -- for short-term locking only as muxAcquire does not perform
4149 // thread state transitions.
4150 //
4151 // Alternatives:
4152 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4153 // but with parking or spin-then-park instead of pure spinning.
4154 // * Use Taura-Oyama-Yonenzawa locks.
4155 // * It's possible to construct a 1-0 lock if we encode the lockword as
4156 // (List,LockByte). Acquire will CAS the full lockword while Release
4157 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4158 // acquiring threads use timers (ParkTimed) to detect and recover from
4159 // the stranding window. Thread/Node structures must be aligned on 256-byte
4160 // boundaries by using placement-new.
4161 // * Augment MCS with advisory back-link fields maintained with CAS().
4162 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4163 // The validity of the backlinks must be ratified before we trust the value.
4164 // If the backlinks are invalid the exiting thread must back-track through the
4165 // the forward links, which are always trustworthy.
4166 // * Add a successor indication. The LockWord is currently encoded as
4167 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4168 // to provide the usual futile-wakeup optimization.
4169 // See RTStt for details.
4170 // * Consider schedctl.sc_nopreempt to cover the critical section.
4171 //
4174 typedef volatile intptr_t MutexT ; // Mux Lock-word
4175 enum MuxBits { LOCKBIT = 1 } ;
4177 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4178 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4179 if (w == 0) return ;
4180 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4181 return ;
4182 }
4184 TEVENT (muxAcquire - Contention) ;
4185 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4186 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4187 for (;;) {
4188 int its = (os::is_MP() ? 100 : 0) + 1 ;
4190 // Optional spin phase: spin-then-park strategy
4191 while (--its >= 0) {
4192 w = *Lock ;
4193 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4194 return ;
4195 }
4196 }
4198 Self->reset() ;
4199 Self->OnList = intptr_t(Lock) ;
4200 // The following fence() isn't _strictly necessary as the subsequent
4201 // CAS() both serializes execution and ratifies the fetched *Lock value.
4202 OrderAccess::fence();
4203 for (;;) {
4204 w = *Lock ;
4205 if ((w & LOCKBIT) == 0) {
4206 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4207 Self->OnList = 0 ; // hygiene - allows stronger asserts
4208 return ;
4209 }
4210 continue ; // Interference -- *Lock changed -- Just retry
4211 }
4212 assert (w & LOCKBIT, "invariant") ;
4213 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4214 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4215 }
4217 while (Self->OnList != 0) {
4218 Self->park() ;
4219 }
4220 }
4221 }
4223 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4224 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4225 if (w == 0) return ;
4226 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4227 return ;
4228 }
4230 TEVENT (muxAcquire - Contention) ;
4231 ParkEvent * ReleaseAfter = NULL ;
4232 if (ev == NULL) {
4233 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4234 }
4235 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4236 for (;;) {
4237 guarantee (ev->OnList == 0, "invariant") ;
4238 int its = (os::is_MP() ? 100 : 0) + 1 ;
4240 // Optional spin phase: spin-then-park strategy
4241 while (--its >= 0) {
4242 w = *Lock ;
4243 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4244 if (ReleaseAfter != NULL) {
4245 ParkEvent::Release (ReleaseAfter) ;
4246 }
4247 return ;
4248 }
4249 }
4251 ev->reset() ;
4252 ev->OnList = intptr_t(Lock) ;
4253 // The following fence() isn't _strictly necessary as the subsequent
4254 // CAS() both serializes execution and ratifies the fetched *Lock value.
4255 OrderAccess::fence();
4256 for (;;) {
4257 w = *Lock ;
4258 if ((w & LOCKBIT) == 0) {
4259 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4260 ev->OnList = 0 ;
4261 // We call ::Release while holding the outer lock, thus
4262 // artificially lengthening the critical section.
4263 // Consider deferring the ::Release() until the subsequent unlock(),
4264 // after we've dropped the outer lock.
4265 if (ReleaseAfter != NULL) {
4266 ParkEvent::Release (ReleaseAfter) ;
4267 }
4268 return ;
4269 }
4270 continue ; // Interference -- *Lock changed -- Just retry
4271 }
4272 assert (w & LOCKBIT, "invariant") ;
4273 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4274 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4275 }
4277 while (ev->OnList != 0) {
4278 ev->park() ;
4279 }
4280 }
4281 }
4283 // Release() must extract a successor from the list and then wake that thread.
4284 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4285 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4286 // Release() would :
4287 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4288 // (B) Extract a successor from the private list "in-hand"
4289 // (C) attempt to CAS() the residual back into *Lock over null.
4290 // If there were any newly arrived threads and the CAS() would fail.
4291 // In that case Release() would detach the RATs, re-merge the list in-hand
4292 // with the RATs and repeat as needed. Alternately, Release() might
4293 // detach and extract a successor, but then pass the residual list to the wakee.
4294 // The wakee would be responsible for reattaching and remerging before it
4295 // competed for the lock.
4296 //
4297 // Both "pop" and DMR are immune from ABA corruption -- there can be
4298 // multiple concurrent pushers, but only one popper or detacher.
4299 // This implementation pops from the head of the list. This is unfair,
4300 // but tends to provide excellent throughput as hot threads remain hot.
4301 // (We wake recently run threads first).
4303 void Thread::muxRelease (volatile intptr_t * Lock) {
4304 for (;;) {
4305 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4306 assert (w & LOCKBIT, "invariant") ;
4307 if (w == LOCKBIT) return ;
4308 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4309 assert (List != NULL, "invariant") ;
4310 assert (List->OnList == intptr_t(Lock), "invariant") ;
4311 ParkEvent * nxt = List->ListNext ;
4313 // The following CAS() releases the lock and pops the head element.
4314 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4315 continue ;
4316 }
4317 List->OnList = 0 ;
4318 OrderAccess::fence() ;
4319 List->unpark () ;
4320 return ;
4321 }
4322 }
4325 void Threads::verify() {
4326 ALL_JAVA_THREADS(p) {
4327 p->verify();
4328 }
4329 VMThread* thread = VMThread::vm_thread();
4330 if (thread != NULL) thread->verify();
4331 }