1 /*
2 * Copyright (c) 1997, 2016, 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 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/codeCacheExtensions.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/gcId.hpp"
37 #include "gc/shared/gcLocker.inline.hpp"
38 #include "gc/shared/referencePendingListLocker.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jvmtifiles/jvmtiEnv.hpp"
44 #include "logging/log.hpp"
45 #include "logging/logConfiguration.hpp"
46 #include "memory/metaspaceShared.hpp"
47 #include "memory/oopFactory.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "memory/universe.inline.hpp"
50 #include "oops/instanceKlass.hpp"
51 #include "oops/objArrayOop.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/symbol.hpp"
54 #include "oops/verifyOopClosure.hpp"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.inline.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagWriteableList.hpp"
64 #include "runtime/commandLineFlagRangeList.hpp"
65 #include "runtime/deoptimization.hpp"
66 #include "runtime/fprofiler.hpp"
67 #include "runtime/frame.inline.hpp"
68 #include "runtime/globals.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/interfaceSupport.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/jniPeriodicChecker.hpp"
74 #include "runtime/timerTrace.hpp"
75 #include "runtime/memprofiler.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/objectMonitor.hpp"
78 #include "runtime/orderAccess.inline.hpp"
79 #include "runtime/osThread.hpp"
80 #include "runtime/safepoint.hpp"
81 #include "runtime/sharedRuntime.hpp"
82 #include "runtime/statSampler.hpp"
83 #include "runtime/stubRoutines.hpp"
84 #include "runtime/sweeper.hpp"
85 #include "runtime/task.hpp"
86 #include "runtime/thread.inline.hpp"
87 #include "runtime/threadCritical.hpp"
88 #include "runtime/vframe.hpp"
89 #include "runtime/vframeArray.hpp"
90 #include "runtime/vframe_hp.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "runtime/vm_operations.hpp"
93 #include "runtime/vm_version.hpp"
94 #include "services/attachListener.hpp"
95 #include "services/management.hpp"
96 #include "services/memTracker.hpp"
97 #include "services/threadService.hpp"
98 #include "trace/traceMacros.hpp"
99 #include "trace/tracing.hpp"
100 #include "utilities/defaultStream.hpp"
101 #include "utilities/dtrace.hpp"
102 #include "utilities/events.hpp"
103 #include "utilities/macros.hpp"
104 #include "utilities/preserveException.hpp"
105 #if INCLUDE_JVMCI
106 #include "jvmci/jvmciCompiler.hpp"
107 #include "jvmci/jvmciRuntime.hpp"
108 #endif
109 #ifdef COMPILER1
110 #include "c1/c1_Compiler.hpp"
111 #endif
112 #ifdef COMPILER2
113 #include "opto/c2compiler.hpp"
114 #include "opto/idealGraphPrinter.hpp"
115 #endif
116 #if INCLUDE_RTM_OPT
117 #include "runtime/rtmLocking.hpp"
118 #endif
119
120 // Initialization after module runtime initialization
121 void universe_post_module_init(); // must happen after call_initPhase2
122
123 #ifdef DTRACE_ENABLED
124
125 // Only bother with this argument setup if dtrace is available
126
127 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
128 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
129
130 #define DTRACE_THREAD_PROBE(probe, javathread) \
131 { \
132 ResourceMark rm(this); \
133 int len = 0; \
134 const char* name = (javathread)->get_thread_name(); \
135 len = strlen(name); \
136 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
137 (char *) name, len, \
138 java_lang_Thread::thread_id((javathread)->threadObj()), \
139 (uintptr_t) (javathread)->osthread()->thread_id(), \
140 java_lang_Thread::is_daemon((javathread)->threadObj())); \
141 }
142
143 #else // ndef DTRACE_ENABLED
144
145 #define DTRACE_THREAD_PROBE(probe, javathread)
146
147 #endif // ndef DTRACE_ENABLED
148
149 #ifndef USE_LIBRARY_BASED_TLS_ONLY
150 // Current thread is maintained as a thread-local variable
151 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
152 #endif
153 // Class hierarchy
154 // - Thread
155 // - VMThread
156 // - WatcherThread
157 // - ConcurrentMarkSweepThread
158 // - JavaThread
159 // - CompilerThread
160
161 // ======= Thread ========
162 // Support for forcing alignment of thread objects for biased locking
163 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
164 if (UseBiasedLocking) {
165 const int alignment = markOopDesc::biased_lock_alignment;
166 size_t aligned_size = size + (alignment - sizeof(intptr_t));
167 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
168 : AllocateHeap(aligned_size, flags, CURRENT_PC,
169 AllocFailStrategy::RETURN_NULL);
170 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
171 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
172 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
173 "JavaThread alignment code overflowed allocated storage");
174 if (aligned_addr != real_malloc_addr) {
175 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
176 p2i(real_malloc_addr),
177 p2i(aligned_addr));
178 }
179 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
180 return aligned_addr;
181 } else {
182 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
183 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
184 }
185 }
186
187 void Thread::operator delete(void* p) {
188 if (UseBiasedLocking) {
189 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
190 FreeHeap(real_malloc_addr);
191 } else {
192 FreeHeap(p);
193 }
194 }
195
196
197 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
198 // JavaThread
199
200
201 Thread::Thread() {
202 // stack and get_thread
203 set_stack_base(NULL);
204 set_stack_size(0);
205 set_self_raw_id(0);
206 set_lgrp_id(-1);
207 DEBUG_ONLY(clear_suspendible_thread();)
208
209 // allocated data structures
210 set_osthread(NULL);
211 set_resource_area(new (mtThread)ResourceArea());
212 DEBUG_ONLY(_current_resource_mark = NULL;)
213 set_handle_area(new (mtThread) HandleArea(NULL));
214 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
215 set_active_handles(NULL);
216 set_free_handle_block(NULL);
217 set_last_handle_mark(NULL);
218
219 // This initial value ==> never claimed.
220 _oops_do_parity = 0;
221
222 // the handle mark links itself to last_handle_mark
223 new HandleMark(this);
224
225 // plain initialization
226 debug_only(_owned_locks = NULL;)
227 debug_only(_allow_allocation_count = 0;)
228 NOT_PRODUCT(_allow_safepoint_count = 0;)
229 NOT_PRODUCT(_skip_gcalot = false;)
230 _jvmti_env_iteration_count = 0;
231 set_allocated_bytes(0);
232 _vm_operation_started_count = 0;
233 _vm_operation_completed_count = 0;
234 _current_pending_monitor = NULL;
235 _current_pending_monitor_is_from_java = true;
236 _current_waiting_monitor = NULL;
237 _num_nested_signal = 0;
238 omFreeList = NULL;
239 omFreeCount = 0;
240 omFreeProvision = 32;
241 omInUseList = NULL;
242 omInUseCount = 0;
243
244 #ifdef ASSERT
245 _visited_for_critical_count = false;
246 #endif
247
248 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
249 Monitor::_safepoint_check_sometimes);
250 _suspend_flags = 0;
251
252 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
253 _hashStateX = os::random();
254 _hashStateY = 842502087;
255 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
256 _hashStateW = 273326509;
257
258 _OnTrap = 0;
259 _schedctl = NULL;
260 _Stalled = 0;
261 _TypeTag = 0x2BAD;
262
263 // Many of the following fields are effectively final - immutable
264 // Note that nascent threads can't use the Native Monitor-Mutex
265 // construct until the _MutexEvent is initialized ...
266 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
267 // we might instead use a stack of ParkEvents that we could provision on-demand.
268 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
269 // and ::Release()
270 _ParkEvent = ParkEvent::Allocate(this);
271 _SleepEvent = ParkEvent::Allocate(this);
272 _MutexEvent = ParkEvent::Allocate(this);
273 _MuxEvent = ParkEvent::Allocate(this);
274
275 #ifdef CHECK_UNHANDLED_OOPS
276 if (CheckUnhandledOops) {
277 _unhandled_oops = new UnhandledOops(this);
278 }
279 #endif // CHECK_UNHANDLED_OOPS
280 #ifdef ASSERT
281 if (UseBiasedLocking) {
282 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
283 assert(this == _real_malloc_address ||
284 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
285 "bug in forced alignment of thread objects");
286 }
287 #endif // ASSERT
288 }
289
290 void Thread::initialize_thread_current() {
291 #ifndef USE_LIBRARY_BASED_TLS_ONLY
292 assert(_thr_current == NULL, "Thread::current already initialized");
293 _thr_current = this;
294 #endif
295 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
296 ThreadLocalStorage::set_thread(this);
297 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
298 }
299
300 void Thread::clear_thread_current() {
301 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
302 #ifndef USE_LIBRARY_BASED_TLS_ONLY
303 _thr_current = NULL;
304 #endif
305 ThreadLocalStorage::set_thread(NULL);
306 }
307
308 void Thread::record_stack_base_and_size() {
309 set_stack_base(os::current_stack_base());
310 set_stack_size(os::current_stack_size());
311 // CR 7190089: on Solaris, primordial thread's stack is adjusted
312 // in initialize_thread(). Without the adjustment, stack size is
313 // incorrect if stack is set to unlimited (ulimit -s unlimited).
314 // So far, only Solaris has real implementation of initialize_thread().
315 //
316 // set up any platform-specific state.
317 os::initialize_thread(this);
318
319 // Set stack limits after thread is initialized.
320 if (is_Java_thread()) {
321 ((JavaThread*) this)->set_stack_overflow_limit();
322 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
323 }
324 #if INCLUDE_NMT
325 // record thread's native stack, stack grows downward
326 MemTracker::record_thread_stack(stack_end(), stack_size());
327 #endif // INCLUDE_NMT
328 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
329 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
330 os::current_thread_id(), p2i(stack_base() - stack_size()),
331 p2i(stack_base()), stack_size()/1024);
332 }
333
334
335 Thread::~Thread() {
336 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
337 ObjectSynchronizer::omFlush(this);
338
339 EVENT_THREAD_DESTRUCT(this);
340
341 // stack_base can be NULL if the thread is never started or exited before
342 // record_stack_base_and_size called. Although, we would like to ensure
343 // that all started threads do call record_stack_base_and_size(), there is
344 // not proper way to enforce that.
345 #if INCLUDE_NMT
346 if (_stack_base != NULL) {
347 MemTracker::release_thread_stack(stack_end(), stack_size());
348 #ifdef ASSERT
349 set_stack_base(NULL);
350 #endif
351 }
352 #endif // INCLUDE_NMT
353
354 // deallocate data structures
355 delete resource_area();
356 // since the handle marks are using the handle area, we have to deallocated the root
357 // handle mark before deallocating the thread's handle area,
358 assert(last_handle_mark() != NULL, "check we have an element");
359 delete last_handle_mark();
360 assert(last_handle_mark() == NULL, "check we have reached the end");
361
362 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
363 // We NULL out the fields for good hygiene.
364 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
365 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
366 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
367 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
368
369 delete handle_area();
370 delete metadata_handles();
371
372 // osthread() can be NULL, if creation of thread failed.
373 if (osthread() != NULL) os::free_thread(osthread());
374
375 delete _SR_lock;
376
377 // clear Thread::current if thread is deleting itself.
378 // Needed to ensure JNI correctly detects non-attached threads.
379 if (this == Thread::current()) {
380 clear_thread_current();
381 }
382
383 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
384 }
385
386 // NOTE: dummy function for assertion purpose.
387 void Thread::run() {
388 ShouldNotReachHere();
389 }
390
391 #ifdef ASSERT
392 // Private method to check for dangling thread pointer
393 void check_for_dangling_thread_pointer(Thread *thread) {
394 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
395 "possibility of dangling Thread pointer");
396 }
397 #endif
398
399 ThreadPriority Thread::get_priority(const Thread* const thread) {
400 ThreadPriority priority;
401 // Can return an error!
402 (void)os::get_priority(thread, priority);
403 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
404 return priority;
405 }
406
407 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
408 debug_only(check_for_dangling_thread_pointer(thread);)
409 // Can return an error!
410 (void)os::set_priority(thread, priority);
411 }
412
413
414 void Thread::start(Thread* thread) {
415 // Start is different from resume in that its safety is guaranteed by context or
416 // being called from a Java method synchronized on the Thread object.
417 if (!DisableStartThread) {
418 if (thread->is_Java_thread()) {
419 // Initialize the thread state to RUNNABLE before starting this thread.
420 // Can not set it after the thread started because we do not know the
421 // exact thread state at that time. It could be in MONITOR_WAIT or
422 // in SLEEPING or some other state.
423 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
424 java_lang_Thread::RUNNABLE);
425 }
426 os::start_thread(thread);
427 }
428 }
429
430 // Enqueue a VM_Operation to do the job for us - sometime later
431 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
432 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
433 VMThread::execute(vm_stop);
434 }
435
436
437 // Check if an external suspend request has completed (or has been
438 // cancelled). Returns true if the thread is externally suspended and
439 // false otherwise.
440 //
441 // The bits parameter returns information about the code path through
442 // the routine. Useful for debugging:
443 //
444 // set in is_ext_suspend_completed():
445 // 0x00000001 - routine was entered
446 // 0x00000010 - routine return false at end
447 // 0x00000100 - thread exited (return false)
448 // 0x00000200 - suspend request cancelled (return false)
449 // 0x00000400 - thread suspended (return true)
450 // 0x00001000 - thread is in a suspend equivalent state (return true)
451 // 0x00002000 - thread is native and walkable (return true)
452 // 0x00004000 - thread is native_trans and walkable (needed retry)
453 //
454 // set in wait_for_ext_suspend_completion():
455 // 0x00010000 - routine was entered
456 // 0x00020000 - suspend request cancelled before loop (return false)
457 // 0x00040000 - thread suspended before loop (return true)
458 // 0x00080000 - suspend request cancelled in loop (return false)
459 // 0x00100000 - thread suspended in loop (return true)
460 // 0x00200000 - suspend not completed during retry loop (return false)
461
462 // Helper class for tracing suspend wait debug bits.
463 //
464 // 0x00000100 indicates that the target thread exited before it could
465 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
466 // 0x00080000 each indicate a cancelled suspend request so they don't
467 // count as wait failures either.
468 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
469
470 class TraceSuspendDebugBits : public StackObj {
471 private:
472 JavaThread * jt;
473 bool is_wait;
474 bool called_by_wait; // meaningful when !is_wait
475 uint32_t * bits;
476
477 public:
478 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
479 uint32_t *_bits) {
480 jt = _jt;
481 is_wait = _is_wait;
482 called_by_wait = _called_by_wait;
483 bits = _bits;
484 }
485
486 ~TraceSuspendDebugBits() {
487 if (!is_wait) {
488 #if 1
489 // By default, don't trace bits for is_ext_suspend_completed() calls.
490 // That trace is very chatty.
491 return;
492 #else
493 if (!called_by_wait) {
494 // If tracing for is_ext_suspend_completed() is enabled, then only
495 // trace calls to it from wait_for_ext_suspend_completion()
496 return;
497 }
498 #endif
499 }
500
501 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
502 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
503 MutexLocker ml(Threads_lock); // needed for get_thread_name()
504 ResourceMark rm;
505
506 tty->print_cr(
507 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
508 jt->get_thread_name(), *bits);
509
510 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
511 }
512 }
513 }
514 };
515 #undef DEBUG_FALSE_BITS
516
517
518 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
519 uint32_t *bits) {
520 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
521
522 bool did_trans_retry = false; // only do thread_in_native_trans retry once
523 bool do_trans_retry; // flag to force the retry
524
525 *bits |= 0x00000001;
526
527 do {
528 do_trans_retry = false;
529
530 if (is_exiting()) {
531 // Thread is in the process of exiting. This is always checked
532 // first to reduce the risk of dereferencing a freed JavaThread.
533 *bits |= 0x00000100;
534 return false;
535 }
536
537 if (!is_external_suspend()) {
538 // Suspend request is cancelled. This is always checked before
539 // is_ext_suspended() to reduce the risk of a rogue resume
540 // confusing the thread that made the suspend request.
541 *bits |= 0x00000200;
542 return false;
543 }
544
545 if (is_ext_suspended()) {
546 // thread is suspended
547 *bits |= 0x00000400;
548 return true;
549 }
550
551 // Now that we no longer do hard suspends of threads running
552 // native code, the target thread can be changing thread state
553 // while we are in this routine:
554 //
555 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
556 //
557 // We save a copy of the thread state as observed at this moment
558 // and make our decision about suspend completeness based on the
559 // copy. This closes the race where the thread state is seen as
560 // _thread_in_native_trans in the if-thread_blocked check, but is
561 // seen as _thread_blocked in if-thread_in_native_trans check.
562 JavaThreadState save_state = thread_state();
563
564 if (save_state == _thread_blocked && is_suspend_equivalent()) {
565 // If the thread's state is _thread_blocked and this blocking
566 // condition is known to be equivalent to a suspend, then we can
567 // consider the thread to be externally suspended. This means that
568 // the code that sets _thread_blocked has been modified to do
569 // self-suspension if the blocking condition releases. We also
570 // used to check for CONDVAR_WAIT here, but that is now covered by
571 // the _thread_blocked with self-suspension check.
572 //
573 // Return true since we wouldn't be here unless there was still an
574 // external suspend request.
575 *bits |= 0x00001000;
576 return true;
577 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
578 // Threads running native code will self-suspend on native==>VM/Java
579 // transitions. If its stack is walkable (should always be the case
580 // unless this function is called before the actual java_suspend()
581 // call), then the wait is done.
582 *bits |= 0x00002000;
583 return true;
584 } else if (!called_by_wait && !did_trans_retry &&
585 save_state == _thread_in_native_trans &&
586 frame_anchor()->walkable()) {
587 // The thread is transitioning from thread_in_native to another
588 // thread state. check_safepoint_and_suspend_for_native_trans()
589 // will force the thread to self-suspend. If it hasn't gotten
590 // there yet we may have caught the thread in-between the native
591 // code check above and the self-suspend. Lucky us. If we were
592 // called by wait_for_ext_suspend_completion(), then it
593 // will be doing the retries so we don't have to.
594 //
595 // Since we use the saved thread state in the if-statement above,
596 // there is a chance that the thread has already transitioned to
597 // _thread_blocked by the time we get here. In that case, we will
598 // make a single unnecessary pass through the logic below. This
599 // doesn't hurt anything since we still do the trans retry.
600
601 *bits |= 0x00004000;
602
603 // Once the thread leaves thread_in_native_trans for another
604 // thread state, we break out of this retry loop. We shouldn't
605 // need this flag to prevent us from getting back here, but
606 // sometimes paranoia is good.
607 did_trans_retry = true;
608
609 // We wait for the thread to transition to a more usable state.
610 for (int i = 1; i <= SuspendRetryCount; i++) {
611 // We used to do an "os::yield_all(i)" call here with the intention
612 // that yielding would increase on each retry. However, the parameter
613 // is ignored on Linux which means the yield didn't scale up. Waiting
614 // on the SR_lock below provides a much more predictable scale up for
615 // the delay. It also provides a simple/direct point to check for any
616 // safepoint requests from the VMThread
617
618 // temporarily drops SR_lock while doing wait with safepoint check
619 // (if we're a JavaThread - the WatcherThread can also call this)
620 // and increase delay with each retry
621 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
622
623 // check the actual thread state instead of what we saved above
624 if (thread_state() != _thread_in_native_trans) {
625 // the thread has transitioned to another thread state so
626 // try all the checks (except this one) one more time.
627 do_trans_retry = true;
628 break;
629 }
630 } // end retry loop
631
632
633 }
634 } while (do_trans_retry);
635
636 *bits |= 0x00000010;
637 return false;
638 }
639
640 // Wait for an external suspend request to complete (or be cancelled).
641 // Returns true if the thread is externally suspended and false otherwise.
642 //
643 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
644 uint32_t *bits) {
645 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
646 false /* !called_by_wait */, bits);
647
648 // local flag copies to minimize SR_lock hold time
649 bool is_suspended;
650 bool pending;
651 uint32_t reset_bits;
652
653 // set a marker so is_ext_suspend_completed() knows we are the caller
654 *bits |= 0x00010000;
655
656 // We use reset_bits to reinitialize the bits value at the top of
657 // each retry loop. This allows the caller to make use of any
658 // unused bits for their own marking purposes.
659 reset_bits = *bits;
660
661 {
662 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
663 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
664 delay, bits);
665 pending = is_external_suspend();
666 }
667 // must release SR_lock to allow suspension to complete
668
669 if (!pending) {
670 // A cancelled suspend request is the only false return from
671 // is_ext_suspend_completed() that keeps us from entering the
672 // retry loop.
673 *bits |= 0x00020000;
674 return false;
675 }
676
677 if (is_suspended) {
678 *bits |= 0x00040000;
679 return true;
680 }
681
682 for (int i = 1; i <= retries; i++) {
683 *bits = reset_bits; // reinit to only track last retry
684
685 // We used to do an "os::yield_all(i)" call here with the intention
686 // that yielding would increase on each retry. However, the parameter
687 // is ignored on Linux which means the yield didn't scale up. Waiting
688 // on the SR_lock below provides a much more predictable scale up for
689 // the delay. It also provides a simple/direct point to check for any
690 // safepoint requests from the VMThread
691
692 {
693 MutexLocker ml(SR_lock());
694 // wait with safepoint check (if we're a JavaThread - the WatcherThread
695 // can also call this) and increase delay with each retry
696 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
697
698 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
699 delay, bits);
700
701 // It is possible for the external suspend request to be cancelled
702 // (by a resume) before the actual suspend operation is completed.
703 // Refresh our local copy to see if we still need to wait.
704 pending = is_external_suspend();
705 }
706
707 if (!pending) {
708 // A cancelled suspend request is the only false return from
709 // is_ext_suspend_completed() that keeps us from staying in the
710 // retry loop.
711 *bits |= 0x00080000;
712 return false;
713 }
714
715 if (is_suspended) {
716 *bits |= 0x00100000;
717 return true;
718 }
719 } // end retry loop
720
721 // thread did not suspend after all our retries
722 *bits |= 0x00200000;
723 return false;
724 }
725
726 #ifndef PRODUCT
727 void JavaThread::record_jump(address target, address instr, const char* file,
728 int line) {
729
730 // This should not need to be atomic as the only way for simultaneous
731 // updates is via interrupts. Even then this should be rare or non-existent
732 // and we don't care that much anyway.
733
734 int index = _jmp_ring_index;
735 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
736 _jmp_ring[index]._target = (intptr_t) target;
737 _jmp_ring[index]._instruction = (intptr_t) instr;
738 _jmp_ring[index]._file = file;
739 _jmp_ring[index]._line = line;
740 }
741 #endif // PRODUCT
742
743 // Called by flat profiler
744 // Callers have already called wait_for_ext_suspend_completion
745 // The assertion for that is currently too complex to put here:
746 bool JavaThread::profile_last_Java_frame(frame* _fr) {
747 bool gotframe = false;
748 // self suspension saves needed state.
749 if (has_last_Java_frame() && _anchor.walkable()) {
750 *_fr = pd_last_frame();
751 gotframe = true;
752 }
753 return gotframe;
754 }
755
756 void Thread::interrupt(Thread* thread) {
757 debug_only(check_for_dangling_thread_pointer(thread);)
758 os::interrupt(thread);
759 }
760
761 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
762 debug_only(check_for_dangling_thread_pointer(thread);)
763 // Note: If clear_interrupted==false, this simply fetches and
764 // returns the value of the field osthread()->interrupted().
765 return os::is_interrupted(thread, clear_interrupted);
766 }
767
768
769 // GC Support
770 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
771 jint thread_parity = _oops_do_parity;
772 if (thread_parity != strong_roots_parity) {
773 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
774 if (res == thread_parity) {
775 return true;
776 } else {
777 guarantee(res == strong_roots_parity, "Or else what?");
778 return false;
779 }
780 }
781 return false;
782 }
783
784 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
785 active_handles()->oops_do(f);
786 // Do oop for ThreadShadow
787 f->do_oop((oop*)&_pending_exception);
788 handle_area()->oops_do(f);
789 }
790
791 void Thread::metadata_handles_do(void f(Metadata*)) {
792 // Only walk the Handles in Thread.
793 if (metadata_handles() != NULL) {
794 for (int i = 0; i< metadata_handles()->length(); i++) {
795 f(metadata_handles()->at(i));
796 }
797 }
798 }
799
800 void Thread::print_on(outputStream* st) const {
801 // get_priority assumes osthread initialized
802 if (osthread() != NULL) {
803 int os_prio;
804 if (os::get_native_priority(this, &os_prio) == OS_OK) {
805 st->print("os_prio=%d ", os_prio);
806 }
807 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
808 ext().print_on(st);
809 osthread()->print_on(st);
810 }
811 debug_only(if (WizardMode) print_owned_locks_on(st);)
812 }
813
814 // Thread::print_on_error() is called by fatal error handler. Don't use
815 // any lock or allocate memory.
816 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
817 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
818
819 if (is_VM_thread()) { st->print("VMThread"); }
820 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
821 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
822 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
823 else { st->print("Thread"); }
824
825 if (is_Named_thread()) {
826 st->print(" \"%s\"", name());
827 }
828
829 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
830 p2i(stack_end()), p2i(stack_base()));
831
832 if (osthread()) {
833 st->print(" [id=%d]", osthread()->thread_id());
834 }
835 }
836
837 #ifdef ASSERT
838 void Thread::print_owned_locks_on(outputStream* st) const {
839 Monitor *cur = _owned_locks;
840 if (cur == NULL) {
841 st->print(" (no locks) ");
842 } else {
843 st->print_cr(" Locks owned:");
844 while (cur) {
845 cur->print_on(st);
846 cur = cur->next();
847 }
848 }
849 }
850
851 static int ref_use_count = 0;
852
853 bool Thread::owns_locks_but_compiled_lock() const {
854 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
855 if (cur != Compile_lock) return true;
856 }
857 return false;
858 }
859
860
861 #endif
862
863 #ifndef PRODUCT
864
865 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
866 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
867 // no threads which allow_vm_block's are held
868 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
869 // Check if current thread is allowed to block at a safepoint
870 if (!(_allow_safepoint_count == 0)) {
871 fatal("Possible safepoint reached by thread that does not allow it");
872 }
873 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
874 fatal("LEAF method calling lock?");
875 }
876
877 #ifdef ASSERT
878 if (potential_vm_operation && is_Java_thread()
879 && !Universe::is_bootstrapping()) {
880 // Make sure we do not hold any locks that the VM thread also uses.
881 // This could potentially lead to deadlocks
882 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
883 // Threads_lock is special, since the safepoint synchronization will not start before this is
884 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
885 // since it is used to transfer control between JavaThreads and the VMThread
886 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
887 if ((cur->allow_vm_block() &&
888 cur != Threads_lock &&
889 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
890 cur != VMOperationRequest_lock &&
891 cur != VMOperationQueue_lock) ||
892 cur->rank() == Mutex::special) {
893 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
894 }
895 }
896 }
897
898 if (GCALotAtAllSafepoints) {
899 // We could enter a safepoint here and thus have a gc
900 InterfaceSupport::check_gc_alot();
901 }
902 #endif
903 }
904 #endif
905
906 bool Thread::is_in_stack(address adr) const {
907 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
908 address end = os::current_stack_pointer();
909 // Allow non Java threads to call this without stack_base
910 if (_stack_base == NULL) return true;
911 if (stack_base() >= adr && adr >= end) return true;
912
913 return false;
914 }
915
916 bool Thread::is_in_usable_stack(address adr) const {
917 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
918 size_t usable_stack_size = _stack_size - stack_guard_size;
919
920 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
921 }
922
923
924 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
925 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
926 // used for compilation in the future. If that change is made, the need for these methods
927 // should be revisited, and they should be removed if possible.
928
929 bool Thread::is_lock_owned(address adr) const {
930 return on_local_stack(adr);
931 }
932
933 bool Thread::set_as_starting_thread() {
934 // NOTE: this must be called inside the main thread.
935 return os::create_main_thread((JavaThread*)this);
936 }
937
938 static void initialize_class(Symbol* class_name, TRAPS) {
939 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
940 InstanceKlass::cast(klass)->initialize(CHECK);
941 }
942
943
944 // Creates the initial ThreadGroup
945 static Handle create_initial_thread_group(TRAPS) {
946 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
947 instanceKlassHandle klass (THREAD, k);
948
949 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
950 {
951 JavaValue result(T_VOID);
952 JavaCalls::call_special(&result,
953 system_instance,
954 klass,
955 vmSymbols::object_initializer_name(),
956 vmSymbols::void_method_signature(),
957 CHECK_NH);
958 }
959 Universe::set_system_thread_group(system_instance());
960
961 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
962 {
963 JavaValue result(T_VOID);
964 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
965 JavaCalls::call_special(&result,
966 main_instance,
967 klass,
968 vmSymbols::object_initializer_name(),
969 vmSymbols::threadgroup_string_void_signature(),
970 system_instance,
971 string,
972 CHECK_NH);
973 }
974 return main_instance;
975 }
976
977 // Creates the initial Thread
978 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
979 TRAPS) {
980 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
981 instanceKlassHandle klass (THREAD, k);
982 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
983
984 java_lang_Thread::set_thread(thread_oop(), thread);
985 java_lang_Thread::set_priority(thread_oop(), NormPriority);
986 thread->set_threadObj(thread_oop());
987
988 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
989
990 JavaValue result(T_VOID);
991 JavaCalls::call_special(&result, thread_oop,
992 klass,
993 vmSymbols::object_initializer_name(),
994 vmSymbols::threadgroup_string_void_signature(),
995 thread_group,
996 string,
997 CHECK_NULL);
998 return thread_oop();
999 }
1000
1001 char java_runtime_name[128] = "";
1002 char java_runtime_version[128] = "";
1003
1004 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1005 static const char* get_java_runtime_name(TRAPS) {
1006 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1007 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1008 fieldDescriptor fd;
1009 bool found = k != NULL &&
1010 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1011 vmSymbols::string_signature(), &fd);
1012 if (found) {
1013 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1014 if (name_oop == NULL) {
1015 return NULL;
1016 }
1017 const char* name = java_lang_String::as_utf8_string(name_oop,
1018 java_runtime_name,
1019 sizeof(java_runtime_name));
1020 return name;
1021 } else {
1022 return NULL;
1023 }
1024 }
1025
1026 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1027 static const char* get_java_runtime_version(TRAPS) {
1028 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1029 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1030 fieldDescriptor fd;
1031 bool found = k != NULL &&
1032 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1033 vmSymbols::string_signature(), &fd);
1034 if (found) {
1035 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1036 if (name_oop == NULL) {
1037 return NULL;
1038 }
1039 const char* name = java_lang_String::as_utf8_string(name_oop,
1040 java_runtime_version,
1041 sizeof(java_runtime_version));
1042 return name;
1043 } else {
1044 return NULL;
1045 }
1046 }
1047
1048 // General purpose hook into Java code, run once when the VM is initialized.
1049 // The Java library method itself may be changed independently from the VM.
1050 static void call_postVMInitHook(TRAPS) {
1051 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1052 instanceKlassHandle klass (THREAD, k);
1053 if (klass.not_null()) {
1054 JavaValue result(T_VOID);
1055 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1056 vmSymbols::void_method_signature(),
1057 CHECK);
1058 }
1059 }
1060
1061 static void reset_vm_info_property(TRAPS) {
1062 // the vm info string
1063 ResourceMark rm(THREAD);
1064 const char *vm_info = VM_Version::vm_info_string();
1065
1066 // java.lang.System class
1067 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1068 instanceKlassHandle klass (THREAD, k);
1069
1070 // setProperty arguments
1071 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1072 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1073
1074 // return value
1075 JavaValue r(T_OBJECT);
1076
1077 // public static String setProperty(String key, String value);
1078 JavaCalls::call_static(&r,
1079 klass,
1080 vmSymbols::setProperty_name(),
1081 vmSymbols::string_string_string_signature(),
1082 key_str,
1083 value_str,
1084 CHECK);
1085 }
1086
1087
1088 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1089 bool daemon, TRAPS) {
1090 assert(thread_group.not_null(), "thread group should be specified");
1091 assert(threadObj() == NULL, "should only create Java thread object once");
1092
1093 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1094 instanceKlassHandle klass (THREAD, k);
1095 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1096
1097 java_lang_Thread::set_thread(thread_oop(), this);
1098 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1099 set_threadObj(thread_oop());
1100
1101 JavaValue result(T_VOID);
1102 if (thread_name != NULL) {
1103 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1104 // Thread gets assigned specified name and null target
1105 JavaCalls::call_special(&result,
1106 thread_oop,
1107 klass,
1108 vmSymbols::object_initializer_name(),
1109 vmSymbols::threadgroup_string_void_signature(),
1110 thread_group, // Argument 1
1111 name, // Argument 2
1112 THREAD);
1113 } else {
1114 // Thread gets assigned name "Thread-nnn" and null target
1115 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1116 JavaCalls::call_special(&result,
1117 thread_oop,
1118 klass,
1119 vmSymbols::object_initializer_name(),
1120 vmSymbols::threadgroup_runnable_void_signature(),
1121 thread_group, // Argument 1
1122 Handle(), // Argument 2
1123 THREAD);
1124 }
1125
1126
1127 if (daemon) {
1128 java_lang_Thread::set_daemon(thread_oop());
1129 }
1130
1131 if (HAS_PENDING_EXCEPTION) {
1132 return;
1133 }
1134
1135 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1136 Handle threadObj(THREAD, this->threadObj());
1137
1138 JavaCalls::call_special(&result,
1139 thread_group,
1140 group,
1141 vmSymbols::add_method_name(),
1142 vmSymbols::thread_void_signature(),
1143 threadObj, // Arg 1
1144 THREAD);
1145 }
1146
1147 // NamedThread -- non-JavaThread subclasses with multiple
1148 // uniquely named instances should derive from this.
1149 NamedThread::NamedThread() : Thread() {
1150 _name = NULL;
1151 _processed_thread = NULL;
1152 _gc_id = GCId::undefined();
1153 }
1154
1155 NamedThread::~NamedThread() {
1156 if (_name != NULL) {
1157 FREE_C_HEAP_ARRAY(char, _name);
1158 _name = NULL;
1159 }
1160 }
1161
1162 void NamedThread::set_name(const char* format, ...) {
1163 guarantee(_name == NULL, "Only get to set name once.");
1164 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1165 guarantee(_name != NULL, "alloc failure");
1166 va_list ap;
1167 va_start(ap, format);
1168 jio_vsnprintf(_name, max_name_len, format, ap);
1169 va_end(ap);
1170 }
1171
1172 void NamedThread::initialize_named_thread() {
1173 set_native_thread_name(name());
1174 }
1175
1176 void NamedThread::print_on(outputStream* st) const {
1177 st->print("\"%s\" ", name());
1178 Thread::print_on(st);
1179 st->cr();
1180 }
1181
1182
1183 // ======= WatcherThread ========
1184
1185 // The watcher thread exists to simulate timer interrupts. It should
1186 // be replaced by an abstraction over whatever native support for
1187 // timer interrupts exists on the platform.
1188
1189 WatcherThread* WatcherThread::_watcher_thread = NULL;
1190 bool WatcherThread::_startable = false;
1191 volatile bool WatcherThread::_should_terminate = false;
1192
1193 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1194 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1195 if (os::create_thread(this, os::watcher_thread)) {
1196 _watcher_thread = this;
1197
1198 // Set the watcher thread to the highest OS priority which should not be
1199 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1200 // is created. The only normal thread using this priority is the reference
1201 // handler thread, which runs for very short intervals only.
1202 // If the VMThread's priority is not lower than the WatcherThread profiling
1203 // will be inaccurate.
1204 os::set_priority(this, MaxPriority);
1205 if (!DisableStartThread) {
1206 os::start_thread(this);
1207 }
1208 }
1209 }
1210
1211 int WatcherThread::sleep() const {
1212 // The WatcherThread does not participate in the safepoint protocol
1213 // for the PeriodicTask_lock because it is not a JavaThread.
1214 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1215
1216 if (_should_terminate) {
1217 // check for termination before we do any housekeeping or wait
1218 return 0; // we did not sleep.
1219 }
1220
1221 // remaining will be zero if there are no tasks,
1222 // causing the WatcherThread to sleep until a task is
1223 // enrolled
1224 int remaining = PeriodicTask::time_to_wait();
1225 int time_slept = 0;
1226
1227 // we expect this to timeout - we only ever get unparked when
1228 // we should terminate or when a new task has been enrolled
1229 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1230
1231 jlong time_before_loop = os::javaTimeNanos();
1232
1233 while (true) {
1234 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1235 remaining);
1236 jlong now = os::javaTimeNanos();
1237
1238 if (remaining == 0) {
1239 // if we didn't have any tasks we could have waited for a long time
1240 // consider the time_slept zero and reset time_before_loop
1241 time_slept = 0;
1242 time_before_loop = now;
1243 } else {
1244 // need to recalculate since we might have new tasks in _tasks
1245 time_slept = (int) ((now - time_before_loop) / 1000000);
1246 }
1247
1248 // Change to task list or spurious wakeup of some kind
1249 if (timedout || _should_terminate) {
1250 break;
1251 }
1252
1253 remaining = PeriodicTask::time_to_wait();
1254 if (remaining == 0) {
1255 // Last task was just disenrolled so loop around and wait until
1256 // another task gets enrolled
1257 continue;
1258 }
1259
1260 remaining -= time_slept;
1261 if (remaining <= 0) {
1262 break;
1263 }
1264 }
1265
1266 return time_slept;
1267 }
1268
1269 void WatcherThread::run() {
1270 assert(this == watcher_thread(), "just checking");
1271
1272 this->record_stack_base_and_size();
1273 this->set_native_thread_name(this->name());
1274 this->set_active_handles(JNIHandleBlock::allocate_block());
1275 while (true) {
1276 assert(watcher_thread() == Thread::current(), "thread consistency check");
1277 assert(watcher_thread() == this, "thread consistency check");
1278
1279 // Calculate how long it'll be until the next PeriodicTask work
1280 // should be done, and sleep that amount of time.
1281 int time_waited = sleep();
1282
1283 if (is_error_reported()) {
1284 // A fatal error has happened, the error handler(VMError::report_and_die)
1285 // should abort JVM after creating an error log file. However in some
1286 // rare cases, the error handler itself might deadlock. Here we try to
1287 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1288 //
1289 // This code is in WatcherThread because WatcherThread wakes up
1290 // periodically so the fatal error handler doesn't need to do anything;
1291 // also because the WatcherThread is less likely to crash than other
1292 // threads.
1293
1294 for (;;) {
1295 if (!ShowMessageBoxOnError
1296 && (OnError == NULL || OnError[0] == '\0')
1297 && Arguments::abort_hook() == NULL) {
1298 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1299 fdStream err(defaultStream::output_fd());
1300 err.print_raw_cr("# [ timer expired, abort... ]");
1301 // skip atexit/vm_exit/vm_abort hooks
1302 os::die();
1303 }
1304
1305 // Wake up 5 seconds later, the fatal handler may reset OnError or
1306 // ShowMessageBoxOnError when it is ready to abort.
1307 os::sleep(this, 5 * 1000, false);
1308 }
1309 }
1310
1311 if (_should_terminate) {
1312 // check for termination before posting the next tick
1313 break;
1314 }
1315
1316 PeriodicTask::real_time_tick(time_waited);
1317 }
1318
1319 // Signal that it is terminated
1320 {
1321 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1322 _watcher_thread = NULL;
1323 Terminator_lock->notify();
1324 }
1325 }
1326
1327 void WatcherThread::start() {
1328 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1329
1330 if (watcher_thread() == NULL && _startable) {
1331 _should_terminate = false;
1332 // Create the single instance of WatcherThread
1333 new WatcherThread();
1334 }
1335 }
1336
1337 void WatcherThread::make_startable() {
1338 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1339 _startable = true;
1340 }
1341
1342 void WatcherThread::stop() {
1343 {
1344 // Follow normal safepoint aware lock enter protocol since the
1345 // WatcherThread is stopped by another JavaThread.
1346 MutexLocker ml(PeriodicTask_lock);
1347 _should_terminate = true;
1348
1349 WatcherThread* watcher = watcher_thread();
1350 if (watcher != NULL) {
1351 // unpark the WatcherThread so it can see that it should terminate
1352 watcher->unpark();
1353 }
1354 }
1355
1356 MutexLocker mu(Terminator_lock);
1357
1358 while (watcher_thread() != NULL) {
1359 // This wait should make safepoint checks, wait without a timeout,
1360 // and wait as a suspend-equivalent condition.
1361 //
1362 // Note: If the FlatProfiler is running, then this thread is waiting
1363 // for the WatcherThread to terminate and the WatcherThread, via the
1364 // FlatProfiler task, is waiting for the external suspend request on
1365 // this thread to complete. wait_for_ext_suspend_completion() will
1366 // eventually timeout, but that takes time. Making this wait a
1367 // suspend-equivalent condition solves that timeout problem.
1368 //
1369 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1370 Mutex::_as_suspend_equivalent_flag);
1371 }
1372 }
1373
1374 void WatcherThread::unpark() {
1375 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1376 PeriodicTask_lock->notify();
1377 }
1378
1379 void WatcherThread::print_on(outputStream* st) const {
1380 st->print("\"%s\" ", name());
1381 Thread::print_on(st);
1382 st->cr();
1383 }
1384
1385 // ======= JavaThread ========
1386
1387 #if INCLUDE_JVMCI
1388
1389 jlong* JavaThread::_jvmci_old_thread_counters;
1390
1391 bool jvmci_counters_include(JavaThread* thread) {
1392 oop threadObj = thread->threadObj();
1393 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1394 }
1395
1396 void JavaThread::collect_counters(typeArrayOop array) {
1397 if (JVMCICounterSize > 0) {
1398 MutexLocker tl(Threads_lock);
1399 for (int i = 0; i < array->length(); i++) {
1400 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1401 }
1402 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1403 if (jvmci_counters_include(tp)) {
1404 for (int i = 0; i < array->length(); i++) {
1405 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1406 }
1407 }
1408 }
1409 }
1410 }
1411
1412 #endif // INCLUDE_JVMCI
1413
1414 // A JavaThread is a normal Java thread
1415
1416 void JavaThread::initialize() {
1417 // Initialize fields
1418
1419 set_saved_exception_pc(NULL);
1420 set_threadObj(NULL);
1421 _anchor.clear();
1422 set_entry_point(NULL);
1423 set_jni_functions(jni_functions());
1424 set_callee_target(NULL);
1425 set_vm_result(NULL);
1426 set_vm_result_2(NULL);
1427 set_vframe_array_head(NULL);
1428 set_vframe_array_last(NULL);
1429 set_deferred_locals(NULL);
1430 set_deopt_mark(NULL);
1431 set_deopt_compiled_method(NULL);
1432 clear_must_deopt_id();
1433 set_monitor_chunks(NULL);
1434 set_next(NULL);
1435 set_thread_state(_thread_new);
1436 _terminated = _not_terminated;
1437 _privileged_stack_top = NULL;
1438 _array_for_gc = NULL;
1439 _suspend_equivalent = false;
1440 _in_deopt_handler = 0;
1441 _doing_unsafe_access = false;
1442 _stack_guard_state = stack_guard_unused;
1443 #if INCLUDE_JVMCI
1444 _pending_monitorenter = false;
1445 _pending_deoptimization = -1;
1446 _pending_failed_speculation = NULL;
1447 _pending_transfer_to_interpreter = false;
1448 _adjusting_comp_level = false;
1449 _jvmci._alternate_call_target = NULL;
1450 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1451 if (JVMCICounterSize > 0) {
1452 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1453 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1454 } else {
1455 _jvmci_counters = NULL;
1456 }
1457 #endif // INCLUDE_JVMCI
1458 _reserved_stack_activation = NULL; // stack base not known yet
1459 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1460 _exception_pc = 0;
1461 _exception_handler_pc = 0;
1462 _is_method_handle_return = 0;
1463 _jvmti_thread_state= NULL;
1464 _should_post_on_exceptions_flag = JNI_FALSE;
1465 _jvmti_get_loaded_classes_closure = NULL;
1466 _interp_only_mode = 0;
1467 _special_runtime_exit_condition = _no_async_condition;
1468 _pending_async_exception = NULL;
1469 _thread_stat = NULL;
1470 _thread_stat = new ThreadStatistics();
1471 _blocked_on_compilation = false;
1472 _jni_active_critical = 0;
1473 _pending_jni_exception_check_fn = NULL;
1474 _do_not_unlock_if_synchronized = false;
1475 _cached_monitor_info = NULL;
1476 _parker = Parker::Allocate(this);
1477
1478 #ifndef PRODUCT
1479 _jmp_ring_index = 0;
1480 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1481 record_jump(NULL, NULL, NULL, 0);
1482 }
1483 #endif // PRODUCT
1484
1485 set_thread_profiler(NULL);
1486 if (FlatProfiler::is_active()) {
1487 // This is where we would decide to either give each thread it's own profiler
1488 // or use one global one from FlatProfiler,
1489 // or up to some count of the number of profiled threads, etc.
1490 ThreadProfiler* pp = new ThreadProfiler();
1491 pp->engage();
1492 set_thread_profiler(pp);
1493 }
1494
1495 // Setup safepoint state info for this thread
1496 ThreadSafepointState::create(this);
1497
1498 debug_only(_java_call_counter = 0);
1499
1500 // JVMTI PopFrame support
1501 _popframe_condition = popframe_inactive;
1502 _popframe_preserved_args = NULL;
1503 _popframe_preserved_args_size = 0;
1504 _frames_to_pop_failed_realloc = 0;
1505
1506 pd_initialize();
1507 }
1508
1509 #if INCLUDE_ALL_GCS
1510 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1511 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1512 #endif // INCLUDE_ALL_GCS
1513
1514 JavaThread::JavaThread(bool is_attaching_via_jni) :
1515 Thread()
1516 #if INCLUDE_ALL_GCS
1517 , _satb_mark_queue(&_satb_mark_queue_set),
1518 _dirty_card_queue(&_dirty_card_queue_set)
1519 #endif // INCLUDE_ALL_GCS
1520 {
1521 initialize();
1522 if (is_attaching_via_jni) {
1523 _jni_attach_state = _attaching_via_jni;
1524 } else {
1525 _jni_attach_state = _not_attaching_via_jni;
1526 }
1527 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1528 }
1529
1530 bool JavaThread::reguard_stack(address cur_sp) {
1531 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1532 && _stack_guard_state != stack_guard_reserved_disabled) {
1533 return true; // Stack already guarded or guard pages not needed.
1534 }
1535
1536 if (register_stack_overflow()) {
1537 // For those architectures which have separate register and
1538 // memory stacks, we must check the register stack to see if
1539 // it has overflowed.
1540 return false;
1541 }
1542
1543 // Java code never executes within the yellow zone: the latter is only
1544 // there to provoke an exception during stack banging. If java code
1545 // is executing there, either StackShadowPages should be larger, or
1546 // some exception code in c1, c2 or the interpreter isn't unwinding
1547 // when it should.
1548 guarantee(cur_sp > stack_reserved_zone_base(),
1549 "not enough space to reguard - increase StackShadowPages");
1550 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1551 enable_stack_yellow_reserved_zone();
1552 if (reserved_stack_activation() != stack_base()) {
1553 set_reserved_stack_activation(stack_base());
1554 }
1555 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1556 set_reserved_stack_activation(stack_base());
1557 enable_stack_reserved_zone();
1558 }
1559 return true;
1560 }
1561
1562 bool JavaThread::reguard_stack(void) {
1563 return reguard_stack(os::current_stack_pointer());
1564 }
1565
1566
1567 void JavaThread::block_if_vm_exited() {
1568 if (_terminated == _vm_exited) {
1569 // _vm_exited is set at safepoint, and Threads_lock is never released
1570 // we will block here forever
1571 Threads_lock->lock_without_safepoint_check();
1572 ShouldNotReachHere();
1573 }
1574 }
1575
1576
1577 // Remove this ifdef when C1 is ported to the compiler interface.
1578 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1579 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1580
1581 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1582 Thread()
1583 #if INCLUDE_ALL_GCS
1584 , _satb_mark_queue(&_satb_mark_queue_set),
1585 _dirty_card_queue(&_dirty_card_queue_set)
1586 #endif // INCLUDE_ALL_GCS
1587 {
1588 initialize();
1589 _jni_attach_state = _not_attaching_via_jni;
1590 set_entry_point(entry_point);
1591 // Create the native thread itself.
1592 // %note runtime_23
1593 os::ThreadType thr_type = os::java_thread;
1594 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1595 os::java_thread;
1596 os::create_thread(this, thr_type, stack_sz);
1597 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1598 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1599 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1600 // the exception consists of creating the exception object & initializing it, initialization
1601 // will leave the VM via a JavaCall and then all locks must be unlocked).
1602 //
1603 // The thread is still suspended when we reach here. Thread must be explicit started
1604 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1605 // by calling Threads:add. The reason why this is not done here, is because the thread
1606 // object must be fully initialized (take a look at JVM_Start)
1607 }
1608
1609 JavaThread::~JavaThread() {
1610
1611 // JSR166 -- return the parker to the free list
1612 Parker::Release(_parker);
1613 _parker = NULL;
1614
1615 // Free any remaining previous UnrollBlock
1616 vframeArray* old_array = vframe_array_last();
1617
1618 if (old_array != NULL) {
1619 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1620 old_array->set_unroll_block(NULL);
1621 delete old_info;
1622 delete old_array;
1623 }
1624
1625 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1626 if (deferred != NULL) {
1627 // This can only happen if thread is destroyed before deoptimization occurs.
1628 assert(deferred->length() != 0, "empty array!");
1629 do {
1630 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1631 deferred->remove_at(0);
1632 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1633 delete dlv;
1634 } while (deferred->length() != 0);
1635 delete deferred;
1636 }
1637
1638 // All Java related clean up happens in exit
1639 ThreadSafepointState::destroy(this);
1640 if (_thread_profiler != NULL) delete _thread_profiler;
1641 if (_thread_stat != NULL) delete _thread_stat;
1642
1643 #if INCLUDE_JVMCI
1644 if (JVMCICounterSize > 0) {
1645 if (jvmci_counters_include(this)) {
1646 for (int i = 0; i < JVMCICounterSize; i++) {
1647 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1648 }
1649 }
1650 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1651 }
1652 #endif // INCLUDE_JVMCI
1653 }
1654
1655
1656 // The first routine called by a new Java thread
1657 void JavaThread::run() {
1658 // initialize thread-local alloc buffer related fields
1659 this->initialize_tlab();
1660
1661 // used to test validity of stack trace backs
1662 this->record_base_of_stack_pointer();
1663
1664 // Record real stack base and size.
1665 this->record_stack_base_and_size();
1666
1667 this->create_stack_guard_pages();
1668
1669 this->cache_global_variables();
1670
1671 // Thread is now sufficient initialized to be handled by the safepoint code as being
1672 // in the VM. Change thread state from _thread_new to _thread_in_vm
1673 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1674
1675 assert(JavaThread::current() == this, "sanity check");
1676 assert(!Thread::current()->owns_locks(), "sanity check");
1677
1678 DTRACE_THREAD_PROBE(start, this);
1679
1680 // This operation might block. We call that after all safepoint checks for a new thread has
1681 // been completed.
1682 this->set_active_handles(JNIHandleBlock::allocate_block());
1683
1684 if (JvmtiExport::should_post_thread_life()) {
1685 JvmtiExport::post_thread_start(this);
1686 }
1687
1688 EventThreadStart event;
1689 if (event.should_commit()) {
1690 event.set_thread(THREAD_TRACE_ID(this));
1691 event.commit();
1692 }
1693
1694 // We call another function to do the rest so we are sure that the stack addresses used
1695 // from there will be lower than the stack base just computed
1696 thread_main_inner();
1697
1698 // Note, thread is no longer valid at this point!
1699 }
1700
1701
1702 void JavaThread::thread_main_inner() {
1703 assert(JavaThread::current() == this, "sanity check");
1704 assert(this->threadObj() != NULL, "just checking");
1705
1706 // Execute thread entry point unless this thread has a pending exception
1707 // or has been stopped before starting.
1708 // Note: Due to JVM_StopThread we can have pending exceptions already!
1709 if (!this->has_pending_exception() &&
1710 !java_lang_Thread::is_stillborn(this->threadObj())) {
1711 {
1712 ResourceMark rm(this);
1713 this->set_native_thread_name(this->get_thread_name());
1714 }
1715 HandleMark hm(this);
1716 this->entry_point()(this, this);
1717 }
1718
1719 DTRACE_THREAD_PROBE(stop, this);
1720
1721 this->exit(false);
1722 delete this;
1723 }
1724
1725
1726 static void ensure_join(JavaThread* thread) {
1727 // We do not need to grap the Threads_lock, since we are operating on ourself.
1728 Handle threadObj(thread, thread->threadObj());
1729 assert(threadObj.not_null(), "java thread object must exist");
1730 ObjectLocker lock(threadObj, thread);
1731 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1732 thread->clear_pending_exception();
1733 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1734 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1735 // Clear the native thread instance - this makes isAlive return false and allows the join()
1736 // to complete once we've done the notify_all below
1737 java_lang_Thread::set_thread(threadObj(), NULL);
1738 lock.notify_all(thread);
1739 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1740 thread->clear_pending_exception();
1741 }
1742
1743
1744 // For any new cleanup additions, please check to see if they need to be applied to
1745 // cleanup_failed_attach_current_thread as well.
1746 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1747 assert(this == JavaThread::current(), "thread consistency check");
1748
1749 HandleMark hm(this);
1750 Handle uncaught_exception(this, this->pending_exception());
1751 this->clear_pending_exception();
1752 Handle threadObj(this, this->threadObj());
1753 assert(threadObj.not_null(), "Java thread object should be created");
1754
1755 if (get_thread_profiler() != NULL) {
1756 get_thread_profiler()->disengage();
1757 ResourceMark rm;
1758 get_thread_profiler()->print(get_thread_name());
1759 }
1760
1761
1762 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1763 {
1764 EXCEPTION_MARK;
1765
1766 CLEAR_PENDING_EXCEPTION;
1767 }
1768 if (!destroy_vm) {
1769 if (uncaught_exception.not_null()) {
1770 EXCEPTION_MARK;
1771 // Call method Thread.dispatchUncaughtException().
1772 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1773 JavaValue result(T_VOID);
1774 JavaCalls::call_virtual(&result,
1775 threadObj, thread_klass,
1776 vmSymbols::dispatchUncaughtException_name(),
1777 vmSymbols::throwable_void_signature(),
1778 uncaught_exception,
1779 THREAD);
1780 if (HAS_PENDING_EXCEPTION) {
1781 ResourceMark rm(this);
1782 jio_fprintf(defaultStream::error_stream(),
1783 "\nException: %s thrown from the UncaughtExceptionHandler"
1784 " in thread \"%s\"\n",
1785 pending_exception()->klass()->external_name(),
1786 get_thread_name());
1787 CLEAR_PENDING_EXCEPTION;
1788 }
1789 }
1790
1791 // Called before the java thread exit since we want to read info
1792 // from java_lang_Thread object
1793 EventThreadEnd event;
1794 if (event.should_commit()) {
1795 event.set_thread(THREAD_TRACE_ID(this));
1796 event.commit();
1797 }
1798
1799 // Call after last event on thread
1800 EVENT_THREAD_EXIT(this);
1801
1802 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1803 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1804 // is deprecated anyhow.
1805 if (!is_Compiler_thread()) {
1806 int count = 3;
1807 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1808 EXCEPTION_MARK;
1809 JavaValue result(T_VOID);
1810 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1811 JavaCalls::call_virtual(&result,
1812 threadObj, thread_klass,
1813 vmSymbols::exit_method_name(),
1814 vmSymbols::void_method_signature(),
1815 THREAD);
1816 CLEAR_PENDING_EXCEPTION;
1817 }
1818 }
1819 // notify JVMTI
1820 if (JvmtiExport::should_post_thread_life()) {
1821 JvmtiExport::post_thread_end(this);
1822 }
1823
1824 // We have notified the agents that we are exiting, before we go on,
1825 // we must check for a pending external suspend request and honor it
1826 // in order to not surprise the thread that made the suspend request.
1827 while (true) {
1828 {
1829 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1830 if (!is_external_suspend()) {
1831 set_terminated(_thread_exiting);
1832 ThreadService::current_thread_exiting(this);
1833 break;
1834 }
1835 // Implied else:
1836 // Things get a little tricky here. We have a pending external
1837 // suspend request, but we are holding the SR_lock so we
1838 // can't just self-suspend. So we temporarily drop the lock
1839 // and then self-suspend.
1840 }
1841
1842 ThreadBlockInVM tbivm(this);
1843 java_suspend_self();
1844
1845 // We're done with this suspend request, but we have to loop around
1846 // and check again. Eventually we will get SR_lock without a pending
1847 // external suspend request and will be able to mark ourselves as
1848 // exiting.
1849 }
1850 // no more external suspends are allowed at this point
1851 } else {
1852 // before_exit() has already posted JVMTI THREAD_END events
1853 }
1854
1855 // Notify waiters on thread object. This has to be done after exit() is called
1856 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1857 // group should have the destroyed bit set before waiters are notified).
1858 ensure_join(this);
1859 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1860
1861 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1862 // held by this thread must be released. The spec does not distinguish
1863 // between JNI-acquired and regular Java monitors. We can only see
1864 // regular Java monitors here if monitor enter-exit matching is broken.
1865 //
1866 // Optionally release any monitors for regular JavaThread exits. This
1867 // is provided as a work around for any bugs in monitor enter-exit
1868 // matching. This can be expensive so it is not enabled by default.
1869 //
1870 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1871 // ObjectSynchronizer::release_monitors_owned_by_thread().
1872 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1873 // Sanity check even though JNI DetachCurrentThread() would have
1874 // returned JNI_ERR if there was a Java frame. JavaThread exit
1875 // should be done executing Java code by the time we get here.
1876 assert(!this->has_last_Java_frame(),
1877 "should not have a Java frame when detaching or exiting");
1878 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1879 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1880 }
1881
1882 // These things needs to be done while we are still a Java Thread. Make sure that thread
1883 // is in a consistent state, in case GC happens
1884 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1885
1886 if (active_handles() != NULL) {
1887 JNIHandleBlock* block = active_handles();
1888 set_active_handles(NULL);
1889 JNIHandleBlock::release_block(block);
1890 }
1891
1892 if (free_handle_block() != NULL) {
1893 JNIHandleBlock* block = free_handle_block();
1894 set_free_handle_block(NULL);
1895 JNIHandleBlock::release_block(block);
1896 }
1897
1898 // These have to be removed while this is still a valid thread.
1899 remove_stack_guard_pages();
1900
1901 if (UseTLAB) {
1902 tlab().make_parsable(true); // retire TLAB
1903 }
1904
1905 if (JvmtiEnv::environments_might_exist()) {
1906 JvmtiExport::cleanup_thread(this);
1907 }
1908
1909 // We must flush any deferred card marks before removing a thread from
1910 // the list of active threads.
1911 GC::gc()->heap()->flush_deferred_store_barrier(this);
1912 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1913
1914 #if INCLUDE_ALL_GCS
1915 // We must flush the G1-related buffers before removing a thread
1916 // from the list of active threads. We must do this after any deferred
1917 // card marks have been flushed (above) so that any entries that are
1918 // added to the thread's dirty card queue as a result are not lost.
1919 if (UseG1GC) {
1920 flush_barrier_queues();
1921 }
1922 #endif // INCLUDE_ALL_GCS
1923
1924 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1925 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1926 os::current_thread_id());
1927
1928 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1929 Threads::remove(this);
1930 }
1931
1932 #if INCLUDE_ALL_GCS
1933 // Flush G1-related queues.
1934 void JavaThread::flush_barrier_queues() {
1935 satb_mark_queue().flush();
1936 dirty_card_queue().flush();
1937 }
1938
1939 void JavaThread::initialize_queues() {
1940 assert(!SafepointSynchronize::is_at_safepoint(),
1941 "we should not be at a safepoint");
1942
1943 SATBMarkQueue& satb_queue = satb_mark_queue();
1944 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1945 // The SATB queue should have been constructed with its active
1946 // field set to false.
1947 assert(!satb_queue.is_active(), "SATB queue should not be active");
1948 assert(satb_queue.is_empty(), "SATB queue should be empty");
1949 // If we are creating the thread during a marking cycle, we should
1950 // set the active field of the SATB queue to true.
1951 if (satb_queue_set.is_active()) {
1952 satb_queue.set_active(true);
1953 }
1954
1955 DirtyCardQueue& dirty_queue = dirty_card_queue();
1956 // The dirty card queue should have been constructed with its
1957 // active field set to true.
1958 assert(dirty_queue.is_active(), "dirty card queue should be active");
1959 }
1960 #endif // INCLUDE_ALL_GCS
1961
1962 void JavaThread::cleanup_failed_attach_current_thread() {
1963 if (get_thread_profiler() != NULL) {
1964 get_thread_profiler()->disengage();
1965 ResourceMark rm;
1966 get_thread_profiler()->print(get_thread_name());
1967 }
1968
1969 if (active_handles() != NULL) {
1970 JNIHandleBlock* block = active_handles();
1971 set_active_handles(NULL);
1972 JNIHandleBlock::release_block(block);
1973 }
1974
1975 if (free_handle_block() != NULL) {
1976 JNIHandleBlock* block = free_handle_block();
1977 set_free_handle_block(NULL);
1978 JNIHandleBlock::release_block(block);
1979 }
1980
1981 // These have to be removed while this is still a valid thread.
1982 remove_stack_guard_pages();
1983
1984 if (UseTLAB) {
1985 tlab().make_parsable(true); // retire TLAB, if any
1986 }
1987
1988 #if INCLUDE_ALL_GCS
1989 if (UseG1GC) {
1990 flush_barrier_queues();
1991 }
1992 #endif // INCLUDE_ALL_GCS
1993
1994 Threads::remove(this);
1995 delete this;
1996 }
1997
1998
1999
2000
2001 JavaThread* JavaThread::active() {
2002 Thread* thread = Thread::current();
2003 if (thread->is_Java_thread()) {
2004 return (JavaThread*) thread;
2005 } else {
2006 assert(thread->is_VM_thread(), "this must be a vm thread");
2007 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2008 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2009 assert(ret->is_Java_thread(), "must be a Java thread");
2010 return ret;
2011 }
2012 }
2013
2014 bool JavaThread::is_lock_owned(address adr) const {
2015 if (Thread::is_lock_owned(adr)) return true;
2016
2017 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2018 if (chunk->contains(adr)) return true;
2019 }
2020
2021 return false;
2022 }
2023
2024
2025 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2026 chunk->set_next(monitor_chunks());
2027 set_monitor_chunks(chunk);
2028 }
2029
2030 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2031 guarantee(monitor_chunks() != NULL, "must be non empty");
2032 if (monitor_chunks() == chunk) {
2033 set_monitor_chunks(chunk->next());
2034 } else {
2035 MonitorChunk* prev = monitor_chunks();
2036 while (prev->next() != chunk) prev = prev->next();
2037 prev->set_next(chunk->next());
2038 }
2039 }
2040
2041 // JVM support.
2042
2043 // Note: this function shouldn't block if it's called in
2044 // _thread_in_native_trans state (such as from
2045 // check_special_condition_for_native_trans()).
2046 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2047
2048 if (has_last_Java_frame() && has_async_condition()) {
2049 // If we are at a polling page safepoint (not a poll return)
2050 // then we must defer async exception because live registers
2051 // will be clobbered by the exception path. Poll return is
2052 // ok because the call we a returning from already collides
2053 // with exception handling registers and so there is no issue.
2054 // (The exception handling path kills call result registers but
2055 // this is ok since the exception kills the result anyway).
2056
2057 if (is_at_poll_safepoint()) {
2058 // if the code we are returning to has deoptimized we must defer
2059 // the exception otherwise live registers get clobbered on the
2060 // exception path before deoptimization is able to retrieve them.
2061 //
2062 RegisterMap map(this, false);
2063 frame caller_fr = last_frame().sender(&map);
2064 assert(caller_fr.is_compiled_frame(), "what?");
2065 if (caller_fr.is_deoptimized_frame()) {
2066 log_info(exceptions)("deferred async exception at compiled safepoint");
2067 return;
2068 }
2069 }
2070 }
2071
2072 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2073 if (condition == _no_async_condition) {
2074 // Conditions have changed since has_special_runtime_exit_condition()
2075 // was called:
2076 // - if we were here only because of an external suspend request,
2077 // then that was taken care of above (or cancelled) so we are done
2078 // - if we were here because of another async request, then it has
2079 // been cleared between the has_special_runtime_exit_condition()
2080 // and now so again we are done
2081 return;
2082 }
2083
2084 // Check for pending async. exception
2085 if (_pending_async_exception != NULL) {
2086 // Only overwrite an already pending exception, if it is not a threadDeath.
2087 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2088
2089 // We cannot call Exceptions::_throw(...) here because we cannot block
2090 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2091
2092 if (log_is_enabled(Info, exceptions)) {
2093 ResourceMark rm;
2094 outputStream* logstream = Log(exceptions)::info_stream();
2095 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2096 if (has_last_Java_frame()) {
2097 frame f = last_frame();
2098 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2099 }
2100 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2101 }
2102 _pending_async_exception = NULL;
2103 clear_has_async_exception();
2104 }
2105 }
2106
2107 if (check_unsafe_error &&
2108 condition == _async_unsafe_access_error && !has_pending_exception()) {
2109 condition = _no_async_condition; // done
2110 switch (thread_state()) {
2111 case _thread_in_vm: {
2112 JavaThread* THREAD = this;
2113 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2114 }
2115 case _thread_in_native: {
2116 ThreadInVMfromNative tiv(this);
2117 JavaThread* THREAD = this;
2118 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2119 }
2120 case _thread_in_Java: {
2121 ThreadInVMfromJava tiv(this);
2122 JavaThread* THREAD = this;
2123 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2124 }
2125 default:
2126 ShouldNotReachHere();
2127 }
2128 }
2129
2130 assert(condition == _no_async_condition || has_pending_exception() ||
2131 (!check_unsafe_error && condition == _async_unsafe_access_error),
2132 "must have handled the async condition, if no exception");
2133 }
2134
2135 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2136 //
2137 // Check for pending external suspend. Internal suspend requests do
2138 // not use handle_special_runtime_exit_condition().
2139 // If JNIEnv proxies are allowed, don't self-suspend if the target
2140 // thread is not the current thread. In older versions of jdbx, jdbx
2141 // threads could call into the VM with another thread's JNIEnv so we
2142 // can be here operating on behalf of a suspended thread (4432884).
2143 bool do_self_suspend = is_external_suspend_with_lock();
2144 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2145 //
2146 // Because thread is external suspended the safepoint code will count
2147 // thread as at a safepoint. This can be odd because we can be here
2148 // as _thread_in_Java which would normally transition to _thread_blocked
2149 // at a safepoint. We would like to mark the thread as _thread_blocked
2150 // before calling java_suspend_self like all other callers of it but
2151 // we must then observe proper safepoint protocol. (We can't leave
2152 // _thread_blocked with a safepoint in progress). However we can be
2153 // here as _thread_in_native_trans so we can't use a normal transition
2154 // constructor/destructor pair because they assert on that type of
2155 // transition. We could do something like:
2156 //
2157 // JavaThreadState state = thread_state();
2158 // set_thread_state(_thread_in_vm);
2159 // {
2160 // ThreadBlockInVM tbivm(this);
2161 // java_suspend_self()
2162 // }
2163 // set_thread_state(_thread_in_vm_trans);
2164 // if (safepoint) block;
2165 // set_thread_state(state);
2166 //
2167 // but that is pretty messy. Instead we just go with the way the
2168 // code has worked before and note that this is the only path to
2169 // java_suspend_self that doesn't put the thread in _thread_blocked
2170 // mode.
2171
2172 frame_anchor()->make_walkable(this);
2173 java_suspend_self();
2174
2175 // We might be here for reasons in addition to the self-suspend request
2176 // so check for other async requests.
2177 }
2178
2179 if (check_asyncs) {
2180 check_and_handle_async_exceptions();
2181 }
2182 }
2183
2184 void JavaThread::send_thread_stop(oop java_throwable) {
2185 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2186 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2187 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2188
2189 // Do not throw asynchronous exceptions against the compiler thread
2190 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2191 if (!can_call_java()) return;
2192
2193 {
2194 // Actually throw the Throwable against the target Thread - however
2195 // only if there is no thread death exception installed already.
2196 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2197 // If the topmost frame is a runtime stub, then we are calling into
2198 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2199 // must deoptimize the caller before continuing, as the compiled exception handler table
2200 // may not be valid
2201 if (has_last_Java_frame()) {
2202 frame f = last_frame();
2203 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2204 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2205 RegisterMap reg_map(this, UseBiasedLocking);
2206 frame compiled_frame = f.sender(®_map);
2207 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2208 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2209 }
2210 }
2211 }
2212
2213 // Set async. pending exception in thread.
2214 set_pending_async_exception(java_throwable);
2215
2216 if (log_is_enabled(Info, exceptions)) {
2217 ResourceMark rm;
2218 log_info(exceptions)("Pending Async. exception installed of type: %s",
2219 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2220 }
2221 // for AbortVMOnException flag
2222 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2223 }
2224 }
2225
2226
2227 // Interrupt thread so it will wake up from a potential wait()
2228 Thread::interrupt(this);
2229 }
2230
2231 // External suspension mechanism.
2232 //
2233 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2234 // to any VM_locks and it is at a transition
2235 // Self-suspension will happen on the transition out of the vm.
2236 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2237 //
2238 // Guarantees on return:
2239 // + Target thread will not execute any new bytecode (that's why we need to
2240 // force a safepoint)
2241 // + Target thread will not enter any new monitors
2242 //
2243 void JavaThread::java_suspend() {
2244 { MutexLocker mu(Threads_lock);
2245 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2246 return;
2247 }
2248 }
2249
2250 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2251 if (!is_external_suspend()) {
2252 // a racing resume has cancelled us; bail out now
2253 return;
2254 }
2255
2256 // suspend is done
2257 uint32_t debug_bits = 0;
2258 // Warning: is_ext_suspend_completed() may temporarily drop the
2259 // SR_lock to allow the thread to reach a stable thread state if
2260 // it is currently in a transient thread state.
2261 if (is_ext_suspend_completed(false /* !called_by_wait */,
2262 SuspendRetryDelay, &debug_bits)) {
2263 return;
2264 }
2265 }
2266
2267 VM_ForceSafepoint vm_suspend;
2268 VMThread::execute(&vm_suspend);
2269 }
2270
2271 // Part II of external suspension.
2272 // A JavaThread self suspends when it detects a pending external suspend
2273 // request. This is usually on transitions. It is also done in places
2274 // where continuing to the next transition would surprise the caller,
2275 // e.g., monitor entry.
2276 //
2277 // Returns the number of times that the thread self-suspended.
2278 //
2279 // Note: DO NOT call java_suspend_self() when you just want to block current
2280 // thread. java_suspend_self() is the second stage of cooperative
2281 // suspension for external suspend requests and should only be used
2282 // to complete an external suspend request.
2283 //
2284 int JavaThread::java_suspend_self() {
2285 int ret = 0;
2286
2287 // we are in the process of exiting so don't suspend
2288 if (is_exiting()) {
2289 clear_external_suspend();
2290 return ret;
2291 }
2292
2293 assert(_anchor.walkable() ||
2294 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2295 "must have walkable stack");
2296
2297 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2298
2299 assert(!this->is_ext_suspended(),
2300 "a thread trying to self-suspend should not already be suspended");
2301
2302 if (this->is_suspend_equivalent()) {
2303 // If we are self-suspending as a result of the lifting of a
2304 // suspend equivalent condition, then the suspend_equivalent
2305 // flag is not cleared until we set the ext_suspended flag so
2306 // that wait_for_ext_suspend_completion() returns consistent
2307 // results.
2308 this->clear_suspend_equivalent();
2309 }
2310
2311 // A racing resume may have cancelled us before we grabbed SR_lock
2312 // above. Or another external suspend request could be waiting for us
2313 // by the time we return from SR_lock()->wait(). The thread
2314 // that requested the suspension may already be trying to walk our
2315 // stack and if we return now, we can change the stack out from under
2316 // it. This would be a "bad thing (TM)" and cause the stack walker
2317 // to crash. We stay self-suspended until there are no more pending
2318 // external suspend requests.
2319 while (is_external_suspend()) {
2320 ret++;
2321 this->set_ext_suspended();
2322
2323 // _ext_suspended flag is cleared by java_resume()
2324 while (is_ext_suspended()) {
2325 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2326 }
2327 }
2328
2329 return ret;
2330 }
2331
2332 #ifdef ASSERT
2333 // verify the JavaThread has not yet been published in the Threads::list, and
2334 // hence doesn't need protection from concurrent access at this stage
2335 void JavaThread::verify_not_published() {
2336 if (!Threads_lock->owned_by_self()) {
2337 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2338 assert(!Threads::includes(this),
2339 "java thread shouldn't have been published yet!");
2340 } else {
2341 assert(!Threads::includes(this),
2342 "java thread shouldn't have been published yet!");
2343 }
2344 }
2345 #endif
2346
2347 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2348 // progress or when _suspend_flags is non-zero.
2349 // Current thread needs to self-suspend if there is a suspend request and/or
2350 // block if a safepoint is in progress.
2351 // Async exception ISN'T checked.
2352 // Note only the ThreadInVMfromNative transition can call this function
2353 // directly and when thread state is _thread_in_native_trans
2354 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2355 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2356
2357 JavaThread *curJT = JavaThread::current();
2358 bool do_self_suspend = thread->is_external_suspend();
2359
2360 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2361
2362 // If JNIEnv proxies are allowed, don't self-suspend if the target
2363 // thread is not the current thread. In older versions of jdbx, jdbx
2364 // threads could call into the VM with another thread's JNIEnv so we
2365 // can be here operating on behalf of a suspended thread (4432884).
2366 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2367 JavaThreadState state = thread->thread_state();
2368
2369 // We mark this thread_blocked state as a suspend-equivalent so
2370 // that a caller to is_ext_suspend_completed() won't be confused.
2371 // The suspend-equivalent state is cleared by java_suspend_self().
2372 thread->set_suspend_equivalent();
2373
2374 // If the safepoint code sees the _thread_in_native_trans state, it will
2375 // wait until the thread changes to other thread state. There is no
2376 // guarantee on how soon we can obtain the SR_lock and complete the
2377 // self-suspend request. It would be a bad idea to let safepoint wait for
2378 // too long. Temporarily change the state to _thread_blocked to
2379 // let the VM thread know that this thread is ready for GC. The problem
2380 // of changing thread state is that safepoint could happen just after
2381 // java_suspend_self() returns after being resumed, and VM thread will
2382 // see the _thread_blocked state. We must check for safepoint
2383 // after restoring the state and make sure we won't leave while a safepoint
2384 // is in progress.
2385 thread->set_thread_state(_thread_blocked);
2386 thread->java_suspend_self();
2387 thread->set_thread_state(state);
2388 // Make sure new state is seen by VM thread
2389 if (os::is_MP()) {
2390 if (UseMembar) {
2391 // Force a fence between the write above and read below
2392 OrderAccess::fence();
2393 } else {
2394 // Must use this rather than serialization page in particular on Windows
2395 InterfaceSupport::serialize_memory(thread);
2396 }
2397 }
2398 }
2399
2400 if (SafepointSynchronize::do_call_back()) {
2401 // If we are safepointing, then block the caller which may not be
2402 // the same as the target thread (see above).
2403 SafepointSynchronize::block(curJT);
2404 }
2405
2406 if (thread->is_deopt_suspend()) {
2407 thread->clear_deopt_suspend();
2408 RegisterMap map(thread, false);
2409 frame f = thread->last_frame();
2410 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2411 f = f.sender(&map);
2412 }
2413 if (f.id() == thread->must_deopt_id()) {
2414 thread->clear_must_deopt_id();
2415 f.deoptimize(thread);
2416 } else {
2417 fatal("missed deoptimization!");
2418 }
2419 }
2420 }
2421
2422 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2423 // progress or when _suspend_flags is non-zero.
2424 // Current thread needs to self-suspend if there is a suspend request and/or
2425 // block if a safepoint is in progress.
2426 // Also check for pending async exception (not including unsafe access error).
2427 // Note only the native==>VM/Java barriers can call this function and when
2428 // thread state is _thread_in_native_trans.
2429 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2430 check_safepoint_and_suspend_for_native_trans(thread);
2431
2432 if (thread->has_async_exception()) {
2433 // We are in _thread_in_native_trans state, don't handle unsafe
2434 // access error since that may block.
2435 thread->check_and_handle_async_exceptions(false);
2436 }
2437 }
2438
2439 // This is a variant of the normal
2440 // check_special_condition_for_native_trans with slightly different
2441 // semantics for use by critical native wrappers. It does all the
2442 // normal checks but also performs the transition back into
2443 // thread_in_Java state. This is required so that critical natives
2444 // can potentially block and perform a GC if they are the last thread
2445 // exiting the GCLocker.
2446 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2447 check_special_condition_for_native_trans(thread);
2448
2449 // Finish the transition
2450 thread->set_thread_state(_thread_in_Java);
2451
2452 if (thread->do_critical_native_unlock()) {
2453 ThreadInVMfromJavaNoAsyncException tiv(thread);
2454 GCLocker::unlock_critical(thread);
2455 thread->clear_critical_native_unlock();
2456 }
2457 }
2458
2459 // We need to guarantee the Threads_lock here, since resumes are not
2460 // allowed during safepoint synchronization
2461 // Can only resume from an external suspension
2462 void JavaThread::java_resume() {
2463 assert_locked_or_safepoint(Threads_lock);
2464
2465 // Sanity check: thread is gone, has started exiting or the thread
2466 // was not externally suspended.
2467 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2468 return;
2469 }
2470
2471 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2472
2473 clear_external_suspend();
2474
2475 if (is_ext_suspended()) {
2476 clear_ext_suspended();
2477 SR_lock()->notify_all();
2478 }
2479 }
2480
2481 size_t JavaThread::_stack_red_zone_size = 0;
2482 size_t JavaThread::_stack_yellow_zone_size = 0;
2483 size_t JavaThread::_stack_reserved_zone_size = 0;
2484 size_t JavaThread::_stack_shadow_zone_size = 0;
2485
2486 void JavaThread::create_stack_guard_pages() {
2487 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2488 address low_addr = stack_end();
2489 size_t len = stack_guard_zone_size();
2490
2491 int must_commit = os::must_commit_stack_guard_pages();
2492 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2493
2494 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2495 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2496 return;
2497 }
2498
2499 if (os::guard_memory((char *) low_addr, len)) {
2500 _stack_guard_state = stack_guard_enabled;
2501 } else {
2502 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2503 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2504 if (os::uncommit_memory((char *) low_addr, len)) {
2505 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2506 }
2507 return;
2508 }
2509
2510 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2511 PTR_FORMAT "-" PTR_FORMAT ".",
2512 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2513 }
2514
2515 void JavaThread::remove_stack_guard_pages() {
2516 assert(Thread::current() == this, "from different thread");
2517 if (_stack_guard_state == stack_guard_unused) return;
2518 address low_addr = stack_end();
2519 size_t len = stack_guard_zone_size();
2520
2521 if (os::must_commit_stack_guard_pages()) {
2522 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2523 _stack_guard_state = stack_guard_unused;
2524 } else {
2525 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2526 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2527 return;
2528 }
2529 } else {
2530 if (_stack_guard_state == stack_guard_unused) return;
2531 if (os::unguard_memory((char *) low_addr, len)) {
2532 _stack_guard_state = stack_guard_unused;
2533 } else {
2534 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2535 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2536 return;
2537 }
2538 }
2539
2540 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2541 PTR_FORMAT "-" PTR_FORMAT ".",
2542 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2543 }
2544
2545 void JavaThread::enable_stack_reserved_zone() {
2546 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2547 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2548
2549 // The base notation is from the stack's point of view, growing downward.
2550 // We need to adjust it to work correctly with guard_memory()
2551 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2552
2553 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2554 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2555
2556 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2557 _stack_guard_state = stack_guard_enabled;
2558 } else {
2559 warning("Attempt to guard stack reserved zone failed.");
2560 }
2561 enable_register_stack_guard();
2562 }
2563
2564 void JavaThread::disable_stack_reserved_zone() {
2565 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2566 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2567
2568 // Simply return if called for a thread that does not use guard pages.
2569 if (_stack_guard_state == stack_guard_unused) return;
2570
2571 // The base notation is from the stack's point of view, growing downward.
2572 // We need to adjust it to work correctly with guard_memory()
2573 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2574
2575 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2576 _stack_guard_state = stack_guard_reserved_disabled;
2577 } else {
2578 warning("Attempt to unguard stack reserved zone failed.");
2579 }
2580 disable_register_stack_guard();
2581 }
2582
2583 void JavaThread::enable_stack_yellow_reserved_zone() {
2584 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2585 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2586
2587 // The base notation is from the stacks point of view, growing downward.
2588 // We need to adjust it to work correctly with guard_memory()
2589 address base = stack_red_zone_base();
2590
2591 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2592 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2593
2594 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2595 _stack_guard_state = stack_guard_enabled;
2596 } else {
2597 warning("Attempt to guard stack yellow zone failed.");
2598 }
2599 enable_register_stack_guard();
2600 }
2601
2602 void JavaThread::disable_stack_yellow_reserved_zone() {
2603 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2604 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2605
2606 // Simply return if called for a thread that does not use guard pages.
2607 if (_stack_guard_state == stack_guard_unused) return;
2608
2609 // The base notation is from the stacks point of view, growing downward.
2610 // We need to adjust it to work correctly with guard_memory()
2611 address base = stack_red_zone_base();
2612
2613 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2614 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2615 } else {
2616 warning("Attempt to unguard stack yellow zone failed.");
2617 }
2618 disable_register_stack_guard();
2619 }
2620
2621 void JavaThread::enable_stack_red_zone() {
2622 // The base notation is from the stacks point of view, growing downward.
2623 // We need to adjust it to work correctly with guard_memory()
2624 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2625 address base = stack_red_zone_base() - stack_red_zone_size();
2626
2627 guarantee(base < stack_base(), "Error calculating stack red zone");
2628 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2629
2630 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2631 warning("Attempt to guard stack red zone failed.");
2632 }
2633 }
2634
2635 void JavaThread::disable_stack_red_zone() {
2636 // The base notation is from the stacks point of view, growing downward.
2637 // We need to adjust it to work correctly with guard_memory()
2638 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2639 address base = stack_red_zone_base() - stack_red_zone_size();
2640 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2641 warning("Attempt to unguard stack red zone failed.");
2642 }
2643 }
2644
2645 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2646 // ignore is there is no stack
2647 if (!has_last_Java_frame()) return;
2648 // traverse the stack frames. Starts from top frame.
2649 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2650 frame* fr = fst.current();
2651 f(fr, fst.register_map());
2652 }
2653 }
2654
2655
2656 #ifndef PRODUCT
2657 // Deoptimization
2658 // Function for testing deoptimization
2659 void JavaThread::deoptimize() {
2660 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2661 StackFrameStream fst(this, UseBiasedLocking);
2662 bool deopt = false; // Dump stack only if a deopt actually happens.
2663 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2664 // Iterate over all frames in the thread and deoptimize
2665 for (; !fst.is_done(); fst.next()) {
2666 if (fst.current()->can_be_deoptimized()) {
2667
2668 if (only_at) {
2669 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2670 // consists of comma or carriage return separated numbers so
2671 // search for the current bci in that string.
2672 address pc = fst.current()->pc();
2673 nmethod* nm = (nmethod*) fst.current()->cb();
2674 ScopeDesc* sd = nm->scope_desc_at(pc);
2675 char buffer[8];
2676 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2677 size_t len = strlen(buffer);
2678 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2679 while (found != NULL) {
2680 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2681 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2682 // Check that the bci found is bracketed by terminators.
2683 break;
2684 }
2685 found = strstr(found + 1, buffer);
2686 }
2687 if (!found) {
2688 continue;
2689 }
2690 }
2691
2692 if (DebugDeoptimization && !deopt) {
2693 deopt = true; // One-time only print before deopt
2694 tty->print_cr("[BEFORE Deoptimization]");
2695 trace_frames();
2696 trace_stack();
2697 }
2698 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2699 }
2700 }
2701
2702 if (DebugDeoptimization && deopt) {
2703 tty->print_cr("[AFTER Deoptimization]");
2704 trace_frames();
2705 }
2706 }
2707
2708
2709 // Make zombies
2710 void JavaThread::make_zombies() {
2711 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2712 if (fst.current()->can_be_deoptimized()) {
2713 // it is a Java nmethod
2714 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2715 nm->make_not_entrant();
2716 }
2717 }
2718 }
2719 #endif // PRODUCT
2720
2721
2722 void JavaThread::deoptimized_wrt_marked_nmethods() {
2723 if (!has_last_Java_frame()) return;
2724 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2725 StackFrameStream fst(this, UseBiasedLocking);
2726 for (; !fst.is_done(); fst.next()) {
2727 if (fst.current()->should_be_deoptimized()) {
2728 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2729 }
2730 }
2731 }
2732
2733
2734 // If the caller is a NamedThread, then remember, in the current scope,
2735 // the given JavaThread in its _processed_thread field.
2736 class RememberProcessedThread: public StackObj {
2737 NamedThread* _cur_thr;
2738 public:
2739 RememberProcessedThread(JavaThread* jthr) {
2740 Thread* thread = Thread::current();
2741 if (thread->is_Named_thread()) {
2742 _cur_thr = (NamedThread *)thread;
2743 _cur_thr->set_processed_thread(jthr);
2744 } else {
2745 _cur_thr = NULL;
2746 }
2747 }
2748
2749 ~RememberProcessedThread() {
2750 if (_cur_thr) {
2751 _cur_thr->set_processed_thread(NULL);
2752 }
2753 }
2754 };
2755
2756 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2757 // Verify that the deferred card marks have been flushed.
2758 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2759
2760 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2761 // since there may be more than one thread using each ThreadProfiler.
2762
2763 // Traverse the GCHandles
2764 Thread::oops_do(f, cf);
2765
2766 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2767
2768 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2769 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2770
2771 if (has_last_Java_frame()) {
2772 // Record JavaThread to GC thread
2773 RememberProcessedThread rpt(this);
2774
2775 // Traverse the privileged stack
2776 if (_privileged_stack_top != NULL) {
2777 _privileged_stack_top->oops_do(f);
2778 }
2779
2780 // traverse the registered growable array
2781 if (_array_for_gc != NULL) {
2782 for (int index = 0; index < _array_for_gc->length(); index++) {
2783 f->do_oop(_array_for_gc->adr_at(index));
2784 }
2785 }
2786
2787 // Traverse the monitor chunks
2788 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2789 chunk->oops_do(f);
2790 }
2791
2792 // Traverse the execution stack
2793 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2794 fst.current()->oops_do(f, cf, fst.register_map());
2795 }
2796 }
2797
2798 // callee_target is never live across a gc point so NULL it here should
2799 // it still contain a methdOop.
2800
2801 set_callee_target(NULL);
2802
2803 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2804 // If we have deferred set_locals there might be oops waiting to be
2805 // written
2806 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2807 if (list != NULL) {
2808 for (int i = 0; i < list->length(); i++) {
2809 list->at(i)->oops_do(f);
2810 }
2811 }
2812
2813 // Traverse instance variables at the end since the GC may be moving things
2814 // around using this function
2815 f->do_oop((oop*) &_threadObj);
2816 f->do_oop((oop*) &_vm_result);
2817 f->do_oop((oop*) &_exception_oop);
2818 f->do_oop((oop*) &_pending_async_exception);
2819
2820 if (jvmti_thread_state() != NULL) {
2821 jvmti_thread_state()->oops_do(f);
2822 }
2823 }
2824
2825 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2826 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2827 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2828
2829 if (has_last_Java_frame()) {
2830 // Traverse the execution stack
2831 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2832 fst.current()->nmethods_do(cf);
2833 }
2834 }
2835 }
2836
2837 void JavaThread::metadata_do(void f(Metadata*)) {
2838 if (has_last_Java_frame()) {
2839 // Traverse the execution stack to call f() on the methods in the stack
2840 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2841 fst.current()->metadata_do(f);
2842 }
2843 } else if (is_Compiler_thread()) {
2844 // need to walk ciMetadata in current compile tasks to keep alive.
2845 CompilerThread* ct = (CompilerThread*)this;
2846 if (ct->env() != NULL) {
2847 ct->env()->metadata_do(f);
2848 }
2849 if (ct->task() != NULL) {
2850 ct->task()->metadata_do(f);
2851 }
2852 }
2853 }
2854
2855 // Printing
2856 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2857 switch (_thread_state) {
2858 case _thread_uninitialized: return "_thread_uninitialized";
2859 case _thread_new: return "_thread_new";
2860 case _thread_new_trans: return "_thread_new_trans";
2861 case _thread_in_native: return "_thread_in_native";
2862 case _thread_in_native_trans: return "_thread_in_native_trans";
2863 case _thread_in_vm: return "_thread_in_vm";
2864 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2865 case _thread_in_Java: return "_thread_in_Java";
2866 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2867 case _thread_blocked: return "_thread_blocked";
2868 case _thread_blocked_trans: return "_thread_blocked_trans";
2869 default: return "unknown thread state";
2870 }
2871 }
2872
2873 #ifndef PRODUCT
2874 void JavaThread::print_thread_state_on(outputStream *st) const {
2875 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2876 };
2877 void JavaThread::print_thread_state() const {
2878 print_thread_state_on(tty);
2879 }
2880 #endif // PRODUCT
2881
2882 // Called by Threads::print() for VM_PrintThreads operation
2883 void JavaThread::print_on(outputStream *st) const {
2884 st->print_raw("\"");
2885 st->print_raw(get_thread_name());
2886 st->print_raw("\" ");
2887 oop thread_oop = threadObj();
2888 if (thread_oop != NULL) {
2889 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2890 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2891 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2892 }
2893 Thread::print_on(st);
2894 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2895 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2896 if (thread_oop != NULL) {
2897 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2898 }
2899 #ifndef PRODUCT
2900 print_thread_state_on(st);
2901 _safepoint_state->print_on(st);
2902 #endif // PRODUCT
2903 if (is_Compiler_thread()) {
2904 CompilerThread* ct = (CompilerThread*)this;
2905 if (ct->task() != NULL) {
2906 st->print(" Compiling: ");
2907 ct->task()->print(st, NULL, true, false);
2908 } else {
2909 st->print(" No compile task");
2910 }
2911 st->cr();
2912 }
2913 }
2914
2915 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2916 st->print("%s", get_thread_name_string(buf, buflen));
2917 }
2918
2919 // Called by fatal error handler. The difference between this and
2920 // JavaThread::print() is that we can't grab lock or allocate memory.
2921 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2922 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2923 oop thread_obj = threadObj();
2924 if (thread_obj != NULL) {
2925 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2926 }
2927 st->print(" [");
2928 st->print("%s", _get_thread_state_name(_thread_state));
2929 if (osthread()) {
2930 st->print(", id=%d", osthread()->thread_id());
2931 }
2932 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2933 p2i(stack_end()), p2i(stack_base()));
2934 st->print("]");
2935 return;
2936 }
2937
2938 // Verification
2939
2940 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2941
2942 void JavaThread::verify() {
2943 // Verify oops in the thread.
2944 oops_do(&VerifyOopClosure::verify_oop, NULL);
2945
2946 // Verify the stack frames.
2947 frames_do(frame_verify);
2948 }
2949
2950 // CR 6300358 (sub-CR 2137150)
2951 // Most callers of this method assume that it can't return NULL but a
2952 // thread may not have a name whilst it is in the process of attaching to
2953 // the VM - see CR 6412693, and there are places where a JavaThread can be
2954 // seen prior to having it's threadObj set (eg JNI attaching threads and
2955 // if vm exit occurs during initialization). These cases can all be accounted
2956 // for such that this method never returns NULL.
2957 const char* JavaThread::get_thread_name() const {
2958 #ifdef ASSERT
2959 // early safepoints can hit while current thread does not yet have TLS
2960 if (!SafepointSynchronize::is_at_safepoint()) {
2961 Thread *cur = Thread::current();
2962 if (!(cur->is_Java_thread() && cur == this)) {
2963 // Current JavaThreads are allowed to get their own name without
2964 // the Threads_lock.
2965 assert_locked_or_safepoint(Threads_lock);
2966 }
2967 }
2968 #endif // ASSERT
2969 return get_thread_name_string();
2970 }
2971
2972 // Returns a non-NULL representation of this thread's name, or a suitable
2973 // descriptive string if there is no set name
2974 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2975 const char* name_str;
2976 oop thread_obj = threadObj();
2977 if (thread_obj != NULL) {
2978 oop name = java_lang_Thread::name(thread_obj);
2979 if (name != NULL) {
2980 if (buf == NULL) {
2981 name_str = java_lang_String::as_utf8_string(name);
2982 } else {
2983 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2984 }
2985 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2986 name_str = "<no-name - thread is attaching>";
2987 } else {
2988 name_str = Thread::name();
2989 }
2990 } else {
2991 name_str = Thread::name();
2992 }
2993 assert(name_str != NULL, "unexpected NULL thread name");
2994 return name_str;
2995 }
2996
2997
2998 const char* JavaThread::get_threadgroup_name() const {
2999 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3000 oop thread_obj = threadObj();
3001 if (thread_obj != NULL) {
3002 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3003 if (thread_group != NULL) {
3004 // ThreadGroup.name can be null
3005 return java_lang_ThreadGroup::name(thread_group);
3006 }
3007 }
3008 return NULL;
3009 }
3010
3011 const char* JavaThread::get_parent_name() const {
3012 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3013 oop thread_obj = threadObj();
3014 if (thread_obj != NULL) {
3015 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3016 if (thread_group != NULL) {
3017 oop parent = java_lang_ThreadGroup::parent(thread_group);
3018 if (parent != NULL) {
3019 // ThreadGroup.name can be null
3020 return java_lang_ThreadGroup::name(parent);
3021 }
3022 }
3023 }
3024 return NULL;
3025 }
3026
3027 ThreadPriority JavaThread::java_priority() const {
3028 oop thr_oop = threadObj();
3029 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3030 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3031 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3032 return priority;
3033 }
3034
3035 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3036
3037 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3038 // Link Java Thread object <-> C++ Thread
3039
3040 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3041 // and put it into a new Handle. The Handle "thread_oop" can then
3042 // be used to pass the C++ thread object to other methods.
3043
3044 // Set the Java level thread object (jthread) field of the
3045 // new thread (a JavaThread *) to C++ thread object using the
3046 // "thread_oop" handle.
3047
3048 // Set the thread field (a JavaThread *) of the
3049 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3050
3051 Handle thread_oop(Thread::current(),
3052 JNIHandles::resolve_non_null(jni_thread));
3053 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3054 "must be initialized");
3055 set_threadObj(thread_oop());
3056 java_lang_Thread::set_thread(thread_oop(), this);
3057
3058 if (prio == NoPriority) {
3059 prio = java_lang_Thread::priority(thread_oop());
3060 assert(prio != NoPriority, "A valid priority should be present");
3061 }
3062
3063 // Push the Java priority down to the native thread; needs Threads_lock
3064 Thread::set_priority(this, prio);
3065
3066 prepare_ext();
3067
3068 // Add the new thread to the Threads list and set it in motion.
3069 // We must have threads lock in order to call Threads::add.
3070 // It is crucial that we do not block before the thread is
3071 // added to the Threads list for if a GC happens, then the java_thread oop
3072 // will not be visited by GC.
3073 Threads::add(this);
3074 }
3075
3076 oop JavaThread::current_park_blocker() {
3077 // Support for JSR-166 locks
3078 oop thread_oop = threadObj();
3079 if (thread_oop != NULL &&
3080 JDK_Version::current().supports_thread_park_blocker()) {
3081 return java_lang_Thread::park_blocker(thread_oop);
3082 }
3083 return NULL;
3084 }
3085
3086
3087 void JavaThread::print_stack_on(outputStream* st) {
3088 if (!has_last_Java_frame()) return;
3089 ResourceMark rm;
3090 HandleMark hm;
3091
3092 RegisterMap reg_map(this);
3093 vframe* start_vf = last_java_vframe(®_map);
3094 int count = 0;
3095 for (vframe* f = start_vf; f; f = f->sender()) {
3096 if (f->is_java_frame()) {
3097 javaVFrame* jvf = javaVFrame::cast(f);
3098 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3099
3100 // Print out lock information
3101 if (JavaMonitorsInStackTrace) {
3102 jvf->print_lock_info_on(st, count);
3103 }
3104 } else {
3105 // Ignore non-Java frames
3106 }
3107
3108 // Bail-out case for too deep stacks
3109 count++;
3110 if (MaxJavaStackTraceDepth == count) return;
3111 }
3112 }
3113
3114
3115 // JVMTI PopFrame support
3116 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3117 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3118 if (in_bytes(size_in_bytes) != 0) {
3119 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3120 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3121 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3122 }
3123 }
3124
3125 void* JavaThread::popframe_preserved_args() {
3126 return _popframe_preserved_args;
3127 }
3128
3129 ByteSize JavaThread::popframe_preserved_args_size() {
3130 return in_ByteSize(_popframe_preserved_args_size);
3131 }
3132
3133 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3134 int sz = in_bytes(popframe_preserved_args_size());
3135 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3136 return in_WordSize(sz / wordSize);
3137 }
3138
3139 void JavaThread::popframe_free_preserved_args() {
3140 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3141 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3142 _popframe_preserved_args = NULL;
3143 _popframe_preserved_args_size = 0;
3144 }
3145
3146 #ifndef PRODUCT
3147
3148 void JavaThread::trace_frames() {
3149 tty->print_cr("[Describe stack]");
3150 int frame_no = 1;
3151 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3152 tty->print(" %d. ", frame_no++);
3153 fst.current()->print_value_on(tty, this);
3154 tty->cr();
3155 }
3156 }
3157
3158 class PrintAndVerifyOopClosure: public OopClosure {
3159 protected:
3160 template <class T> inline void do_oop_work(T* p) {
3161 oop obj = oopDesc::load_decode_heap_oop(p);
3162 if (obj == NULL) return;
3163 tty->print(INTPTR_FORMAT ": ", p2i(p));
3164 if (obj->is_oop_or_null()) {
3165 if (obj->is_objArray()) {
3166 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3167 } else {
3168 obj->print();
3169 }
3170 } else {
3171 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3172 }
3173 tty->cr();
3174 }
3175 public:
3176 virtual void do_oop(oop* p) { do_oop_work(p); }
3177 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3178 };
3179
3180
3181 static void oops_print(frame* f, const RegisterMap *map) {
3182 PrintAndVerifyOopClosure print;
3183 f->print_value();
3184 f->oops_do(&print, NULL, (RegisterMap*)map);
3185 }
3186
3187 // Print our all the locations that contain oops and whether they are
3188 // valid or not. This useful when trying to find the oldest frame
3189 // where an oop has gone bad since the frame walk is from youngest to
3190 // oldest.
3191 void JavaThread::trace_oops() {
3192 tty->print_cr("[Trace oops]");
3193 frames_do(oops_print);
3194 }
3195
3196
3197 #ifdef ASSERT
3198 // Print or validate the layout of stack frames
3199 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3200 ResourceMark rm;
3201 PRESERVE_EXCEPTION_MARK;
3202 FrameValues values;
3203 int frame_no = 0;
3204 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3205 fst.current()->describe(values, ++frame_no);
3206 if (depth == frame_no) break;
3207 }
3208 if (validate_only) {
3209 values.validate();
3210 } else {
3211 tty->print_cr("[Describe stack layout]");
3212 values.print(this);
3213 }
3214 }
3215 #endif
3216
3217 void JavaThread::trace_stack_from(vframe* start_vf) {
3218 ResourceMark rm;
3219 int vframe_no = 1;
3220 for (vframe* f = start_vf; f; f = f->sender()) {
3221 if (f->is_java_frame()) {
3222 javaVFrame::cast(f)->print_activation(vframe_no++);
3223 } else {
3224 f->print();
3225 }
3226 if (vframe_no > StackPrintLimit) {
3227 tty->print_cr("...<more frames>...");
3228 return;
3229 }
3230 }
3231 }
3232
3233
3234 void JavaThread::trace_stack() {
3235 if (!has_last_Java_frame()) return;
3236 ResourceMark rm;
3237 HandleMark hm;
3238 RegisterMap reg_map(this);
3239 trace_stack_from(last_java_vframe(®_map));
3240 }
3241
3242
3243 #endif // PRODUCT
3244
3245
3246 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3247 assert(reg_map != NULL, "a map must be given");
3248 frame f = last_frame();
3249 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3250 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3251 }
3252 return NULL;
3253 }
3254
3255
3256 Klass* JavaThread::security_get_caller_class(int depth) {
3257 vframeStream vfst(this);
3258 vfst.security_get_caller_frame(depth);
3259 if (!vfst.at_end()) {
3260 return vfst.method()->method_holder();
3261 }
3262 return NULL;
3263 }
3264
3265 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3266 assert(thread->is_Compiler_thread(), "must be compiler thread");
3267 CompileBroker::compiler_thread_loop();
3268 }
3269
3270 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3271 NMethodSweeper::sweeper_loop();
3272 }
3273
3274 // Create a CompilerThread
3275 CompilerThread::CompilerThread(CompileQueue* queue,
3276 CompilerCounters* counters)
3277 : JavaThread(&compiler_thread_entry) {
3278 _env = NULL;
3279 _log = NULL;
3280 _task = NULL;
3281 _queue = queue;
3282 _counters = counters;
3283 _buffer_blob = NULL;
3284 _compiler = NULL;
3285
3286 #ifndef PRODUCT
3287 _ideal_graph_printer = NULL;
3288 #endif
3289 }
3290
3291 bool CompilerThread::can_call_java() const {
3292 return _compiler != NULL && _compiler->is_jvmci();
3293 }
3294
3295 // Create sweeper thread
3296 CodeCacheSweeperThread::CodeCacheSweeperThread()
3297 : JavaThread(&sweeper_thread_entry) {
3298 _scanned_compiled_method = NULL;
3299 }
3300
3301 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3302 JavaThread::oops_do(f, cf);
3303 if (_scanned_compiled_method != NULL && cf != NULL) {
3304 // Safepoints can occur when the sweeper is scanning an nmethod so
3305 // process it here to make sure it isn't unloaded in the middle of
3306 // a scan.
3307 cf->do_code_blob(_scanned_compiled_method);
3308 }
3309 }
3310
3311 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3312 JavaThread::nmethods_do(cf);
3313 if (_scanned_compiled_method != NULL && cf != NULL) {
3314 // Safepoints can occur when the sweeper is scanning an nmethod so
3315 // process it here to make sure it isn't unloaded in the middle of
3316 // a scan.
3317 cf->do_code_blob(_scanned_compiled_method);
3318 }
3319 }
3320
3321
3322 // ======= Threads ========
3323
3324 // The Threads class links together all active threads, and provides
3325 // operations over all threads. It is protected by its own Mutex
3326 // lock, which is also used in other contexts to protect thread
3327 // operations from having the thread being operated on from exiting
3328 // and going away unexpectedly (e.g., safepoint synchronization)
3329
3330 JavaThread* Threads::_thread_list = NULL;
3331 int Threads::_number_of_threads = 0;
3332 int Threads::_number_of_non_daemon_threads = 0;
3333 int Threads::_return_code = 0;
3334 int Threads::_thread_claim_parity = 0;
3335 size_t JavaThread::_stack_size_at_create = 0;
3336 #ifdef ASSERT
3337 bool Threads::_vm_complete = false;
3338 #endif
3339
3340 // All JavaThreads
3341 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3342
3343 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3344 void Threads::threads_do(ThreadClosure* tc) {
3345 assert_locked_or_safepoint(Threads_lock);
3346 // ALL_JAVA_THREADS iterates through all JavaThreads
3347 ALL_JAVA_THREADS(p) {
3348 tc->do_thread(p);
3349 }
3350 // Someday we could have a table or list of all non-JavaThreads.
3351 // For now, just manually iterate through them.
3352 tc->do_thread(VMThread::vm_thread());
3353 GC::gc()->heap()->gc_threads_do(tc);
3354 WatcherThread *wt = WatcherThread::watcher_thread();
3355 // Strictly speaking, the following NULL check isn't sufficient to make sure
3356 // the data for WatcherThread is still valid upon being examined. However,
3357 // considering that WatchThread terminates when the VM is on the way to
3358 // exit at safepoint, the chance of the above is extremely small. The right
3359 // way to prevent termination of WatcherThread would be to acquire
3360 // Terminator_lock, but we can't do that without violating the lock rank
3361 // checking in some cases.
3362 if (wt != NULL) {
3363 tc->do_thread(wt);
3364 }
3365
3366 // If CompilerThreads ever become non-JavaThreads, add them here
3367 }
3368
3369 // The system initialization in the library has three phases.
3370 //
3371 // Phase 1: java.lang.System class initialization
3372 // java.lang.System is a primordial class loaded and initialized
3373 // by the VM early during startup. java.lang.System.<clinit>
3374 // only does registerNatives and keeps the rest of the class
3375 // initialization work later until thread initialization completes.
3376 //
3377 // System.initPhase1 initializes the system properties, the static
3378 // fields in, out, and err. Set up java signal handlers, OS-specific
3379 // system settings, and thread group of the main thread.
3380 static void call_initPhase1(TRAPS) {
3381 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3382 instanceKlassHandle klass (THREAD, k);
3383
3384 JavaValue result(T_VOID);
3385 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3386 vmSymbols::void_method_signature(), CHECK);
3387 }
3388
3389 // Phase 2. Module system initialization
3390 // This will initialize the module system. Only java.base classes
3391 // can be loaded until phase 2 completes.
3392 //
3393 // Call System.initPhase2 after the compiler initialization and jsr292
3394 // classes get initialized because module initialization runs a lot of java
3395 // code, that for performance reasons, should be compiled. Also, this will
3396 // enable the startup code to use lambda and other language features in this
3397 // phase and onward.
3398 //
3399 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3400 static void call_initPhase2(TRAPS) {
3401 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime));
3402
3403 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3404 instanceKlassHandle klass (THREAD, k);
3405
3406 JavaValue result(T_VOID);
3407 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3408 vmSymbols::void_method_signature(), CHECK);
3409 universe_post_module_init();
3410 }
3411
3412 // Phase 3. final setup - set security manager, system class loader and TCCL
3413 //
3414 // This will instantiate and set the security manager, set the system class
3415 // loader as well as the thread context class loader. The security manager
3416 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3417 // other modules or the application's classpath.
3418 static void call_initPhase3(TRAPS) {
3419 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3420 instanceKlassHandle klass (THREAD, k);
3421
3422 JavaValue result(T_VOID);
3423 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3424 vmSymbols::void_method_signature(), CHECK);
3425 }
3426
3427 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3428 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3429
3430 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3431 create_vm_init_libraries();
3432 }
3433
3434 initialize_class(vmSymbols::java_lang_String(), CHECK);
3435
3436 // Inject CompactStrings value after the static initializers for String ran.
3437 java_lang_String::set_compact_strings(CompactStrings);
3438
3439 // Initialize java_lang.System (needed before creating the thread)
3440 initialize_class(vmSymbols::java_lang_System(), CHECK);
3441 // The VM creates & returns objects of this class. Make sure it's initialized.
3442 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3443 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3444 Handle thread_group = create_initial_thread_group(CHECK);
3445 Universe::set_main_thread_group(thread_group());
3446 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3447 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3448 main_thread->set_threadObj(thread_object);
3449 // Set thread status to running since main thread has
3450 // been started and running.
3451 java_lang_Thread::set_thread_status(thread_object,
3452 java_lang_Thread::RUNNABLE);
3453
3454 // The VM creates objects of this class.
3455 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3456
3457 // The VM preresolves methods to these classes. Make sure that they get initialized
3458 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3459 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3460
3461 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3462 call_initPhase1(CHECK);
3463
3464 // get the Java runtime name after java.lang.System is initialized
3465 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3466 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3467
3468 // an instance of OutOfMemory exception has been allocated earlier
3469 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3470 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3471 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3472 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3473 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3474 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3475 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3476 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3477 }
3478
3479 void Threads::initialize_jsr292_core_classes(TRAPS) {
3480 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3481
3482 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3483 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3484 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3485 }
3486
3487 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3488 extern void JDK_Version_init();
3489
3490 // Preinitialize version info.
3491 VM_Version::early_initialize();
3492
3493 // Check version
3494 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3495
3496 // Initialize library-based TLS
3497 ThreadLocalStorage::init();
3498
3499 // Initialize the output stream module
3500 ostream_init();
3501
3502 // Process java launcher properties.
3503 Arguments::process_sun_java_launcher_properties(args);
3504
3505 // Initialize the os module
3506 os::init();
3507
3508 // Record VM creation timing statistics
3509 TraceVmCreationTime create_vm_timer;
3510 create_vm_timer.start();
3511
3512 // Initialize system properties.
3513 Arguments::init_system_properties();
3514
3515 // So that JDK version can be used as a discriminator when parsing arguments
3516 JDK_Version_init();
3517
3518 // Update/Initialize System properties after JDK version number is known
3519 Arguments::init_version_specific_system_properties();
3520
3521 // Make sure to initialize log configuration *before* parsing arguments
3522 LogConfiguration::initialize(create_vm_timer.begin_time());
3523
3524 // Parse arguments
3525 jint parse_result = Arguments::parse(args);
3526 if (parse_result != JNI_OK) return parse_result;
3527
3528 os::init_before_ergo();
3529
3530 Arguments::select_gc();
3531 jint gc_result = GC::initialize();
3532 if (gc_result != JNI_OK) {
3533 return gc_result;
3534 }
3535
3536 jint ergo_result = Arguments::apply_ergo();
3537 if (ergo_result != JNI_OK) return ergo_result;
3538
3539 // Final check of all ranges after ergonomics which may change values.
3540 if (!CommandLineFlagRangeList::check_ranges()) {
3541 return JNI_EINVAL;
3542 }
3543
3544 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3545 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3546 if (!constraint_result) {
3547 return JNI_EINVAL;
3548 }
3549
3550 CommandLineFlagWriteableList::mark_startup();
3551
3552 if (PauseAtStartup) {
3553 os::pause();
3554 }
3555
3556 HOTSPOT_VM_INIT_BEGIN();
3557
3558 // Timing (must come after argument parsing)
3559 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3560
3561 // Initialize the os module after parsing the args
3562 jint os_init_2_result = os::init_2();
3563 if (os_init_2_result != JNI_OK) return os_init_2_result;
3564
3565 jint adjust_after_os_result = Arguments::adjust_after_os();
3566 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3567
3568 // Initialize output stream logging
3569 ostream_init_log();
3570
3571 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3572 // Must be before create_vm_init_agents()
3573 if (Arguments::init_libraries_at_startup()) {
3574 convert_vm_init_libraries_to_agents();
3575 }
3576
3577 // Launch -agentlib/-agentpath and converted -Xrun agents
3578 if (Arguments::init_agents_at_startup()) {
3579 create_vm_init_agents();
3580 }
3581
3582 // Initialize Threads state
3583 _thread_list = NULL;
3584 _number_of_threads = 0;
3585 _number_of_non_daemon_threads = 0;
3586
3587 // Initialize global data structures and create system classes in heap
3588 vm_init_globals();
3589
3590 #if INCLUDE_JVMCI
3591 if (JVMCICounterSize > 0) {
3592 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3593 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3594 } else {
3595 JavaThread::_jvmci_old_thread_counters = NULL;
3596 }
3597 #endif // INCLUDE_JVMCI
3598
3599 // Attach the main thread to this os thread
3600 JavaThread* main_thread = new JavaThread();
3601 main_thread->set_thread_state(_thread_in_vm);
3602 main_thread->initialize_thread_current();
3603 // must do this before set_active_handles
3604 main_thread->record_stack_base_and_size();
3605 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3606
3607 if (!main_thread->set_as_starting_thread()) {
3608 vm_shutdown_during_initialization(
3609 "Failed necessary internal allocation. Out of swap space");
3610 delete main_thread;
3611 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3612 return JNI_ENOMEM;
3613 }
3614
3615 // Enable guard page *after* os::create_main_thread(), otherwise it would
3616 // crash Linux VM, see notes in os_linux.cpp.
3617 main_thread->create_stack_guard_pages();
3618
3619 // Initialize Java-Level synchronization subsystem
3620 ObjectMonitor::Initialize();
3621
3622 // Initialize global modules
3623 jint status = init_globals();
3624 if (status != JNI_OK) {
3625 delete main_thread;
3626 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3627 return status;
3628 }
3629
3630 if (TRACE_INITIALIZE() != JNI_OK) {
3631 vm_exit_during_initialization("Failed to initialize tracing backend");
3632 }
3633
3634 // Should be done after the heap is fully created
3635 main_thread->cache_global_variables();
3636
3637 HandleMark hm;
3638
3639 { MutexLocker mu(Threads_lock);
3640 Threads::add(main_thread);
3641 }
3642
3643 // Any JVMTI raw monitors entered in onload will transition into
3644 // real raw monitor. VM is setup enough here for raw monitor enter.
3645 JvmtiExport::transition_pending_onload_raw_monitors();
3646
3647 // Create the VMThread
3648 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3649
3650 VMThread::create();
3651 Thread* vmthread = VMThread::vm_thread();
3652
3653 if (!os::create_thread(vmthread, os::vm_thread)) {
3654 vm_exit_during_initialization("Cannot create VM thread. "
3655 "Out of system resources.");
3656 }
3657
3658 // Wait for the VM thread to become ready, and VMThread::run to initialize
3659 // Monitors can have spurious returns, must always check another state flag
3660 {
3661 MutexLocker ml(Notify_lock);
3662 os::start_thread(vmthread);
3663 while (vmthread->active_handles() == NULL) {
3664 Notify_lock->wait();
3665 }
3666 }
3667 }
3668
3669 assert(Universe::is_fully_initialized(), "not initialized");
3670 if (VerifyDuringStartup) {
3671 // Make sure we're starting with a clean slate.
3672 VM_Verify verify_op;
3673 VMThread::execute(&verify_op);
3674 }
3675
3676 Thread* THREAD = Thread::current();
3677
3678 // At this point, the Universe is initialized, but we have not executed
3679 // any byte code. Now is a good time (the only time) to dump out the
3680 // internal state of the JVM for sharing.
3681 if (DumpSharedSpaces) {
3682 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3683 ShouldNotReachHere();
3684 }
3685
3686 // Always call even when there are not JVMTI environments yet, since environments
3687 // may be attached late and JVMTI must track phases of VM execution
3688 JvmtiExport::enter_early_start_phase();
3689
3690 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3691 JvmtiExport::post_early_vm_start();
3692
3693 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3694
3695 // We need this for ClassDataSharing - the initial vm.info property is set
3696 // with the default value of CDS "sharing" which may be reset through
3697 // command line options.
3698 reset_vm_info_property(CHECK_JNI_ERR);
3699
3700 quicken_jni_functions();
3701
3702 // No more stub generation allowed after that point.
3703 StubCodeDesc::freeze();
3704
3705 // Set flag that basic initialization has completed. Used by exceptions and various
3706 // debug stuff, that does not work until all basic classes have been initialized.
3707 set_init_completed();
3708
3709 LogConfiguration::post_initialize();
3710 Metaspace::post_initialize();
3711
3712 HOTSPOT_VM_INIT_END();
3713
3714 // record VM initialization completion time
3715 #if INCLUDE_MANAGEMENT
3716 Management::record_vm_init_completed();
3717 #endif // INCLUDE_MANAGEMENT
3718
3719 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3720 // set_init_completed has just been called, causing exceptions not to be shortcut
3721 // anymore. We call vm_exit_during_initialization directly instead.
3722
3723 // Initialize reference pending list locker
3724 bool needs_locker_thread = GC::gc()->heap()->needs_reference_pending_list_locker_thread();
3725 ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR);
3726
3727 // Signal Dispatcher needs to be started before VMInit event is posted
3728 os::signal_init();
3729
3730 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3731 if (!DisableAttachMechanism) {
3732 AttachListener::vm_start();
3733 if (StartAttachListener || AttachListener::init_at_startup()) {
3734 AttachListener::init();
3735 }
3736 }
3737
3738 // Launch -Xrun agents
3739 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3740 // back-end can launch with -Xdebug -Xrunjdwp.
3741 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3742 create_vm_init_libraries();
3743 }
3744
3745 if (CleanChunkPoolAsync) {
3746 Chunk::start_chunk_pool_cleaner_task();
3747 }
3748
3749 // initialize compiler(s)
3750 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3751 CompileBroker::compilation_init(CHECK_JNI_ERR);
3752 #endif
3753
3754 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3755 // It is done after compilers are initialized, because otherwise compilations of
3756 // signature polymorphic MH intrinsics can be missed
3757 // (see SystemDictionary::find_method_handle_intrinsic).
3758 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3759
3760 // This will initialize the module system. Only java.base classes can be
3761 // loaded until phase 2 completes
3762 call_initPhase2(CHECK_JNI_ERR);
3763
3764 // Always call even when there are not JVMTI environments yet, since environments
3765 // may be attached late and JVMTI must track phases of VM execution
3766 JvmtiExport::enter_start_phase();
3767
3768 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3769 JvmtiExport::post_vm_start();
3770
3771 // Final system initialization including security manager and system class loader
3772 call_initPhase3(CHECK_JNI_ERR);
3773
3774 // cache the system class loader
3775 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3776
3777 #if INCLUDE_JVMCI
3778 if (EnableJVMCI && UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation)) {
3779 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3780 // compilations via JVMCI will not actually block until JVMCI is initialized.
3781 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3782 }
3783 #endif
3784
3785 // Always call even when there are not JVMTI environments yet, since environments
3786 // may be attached late and JVMTI must track phases of VM execution
3787 JvmtiExport::enter_live_phase();
3788
3789 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3790 JvmtiExport::post_vm_initialized();
3791
3792 if (TRACE_START() != JNI_OK) {
3793 vm_exit_during_initialization("Failed to start tracing backend.");
3794 }
3795
3796 #if INCLUDE_MANAGEMENT
3797 Management::initialize(THREAD);
3798
3799 if (HAS_PENDING_EXCEPTION) {
3800 // management agent fails to start possibly due to
3801 // configuration problem and is responsible for printing
3802 // stack trace if appropriate. Simply exit VM.
3803 vm_exit(1);
3804 }
3805 #endif // INCLUDE_MANAGEMENT
3806
3807 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3808 if (MemProfiling) MemProfiler::engage();
3809 StatSampler::engage();
3810 if (CheckJNICalls) JniPeriodicChecker::engage();
3811
3812 BiasedLocking::init();
3813
3814 #if INCLUDE_RTM_OPT
3815 RTMLockingCounters::init();
3816 #endif
3817
3818 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3819 call_postVMInitHook(THREAD);
3820 // The Java side of PostVMInitHook.run must deal with all
3821 // exceptions and provide means of diagnosis.
3822 if (HAS_PENDING_EXCEPTION) {
3823 CLEAR_PENDING_EXCEPTION;
3824 }
3825 }
3826
3827 {
3828 MutexLocker ml(PeriodicTask_lock);
3829 // Make sure the WatcherThread can be started by WatcherThread::start()
3830 // or by dynamic enrollment.
3831 WatcherThread::make_startable();
3832 // Start up the WatcherThread if there are any periodic tasks
3833 // NOTE: All PeriodicTasks should be registered by now. If they
3834 // aren't, late joiners might appear to start slowly (we might
3835 // take a while to process their first tick).
3836 if (PeriodicTask::num_tasks() > 0) {
3837 WatcherThread::start();
3838 }
3839 }
3840
3841 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3842
3843 create_vm_timer.end();
3844 #ifdef ASSERT
3845 _vm_complete = true;
3846 #endif
3847 return JNI_OK;
3848 }
3849
3850 // type for the Agent_OnLoad and JVM_OnLoad entry points
3851 extern "C" {
3852 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3853 }
3854 // Find a command line agent library and return its entry point for
3855 // -agentlib: -agentpath: -Xrun
3856 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3857 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3858 const char *on_load_symbols[],
3859 size_t num_symbol_entries) {
3860 OnLoadEntry_t on_load_entry = NULL;
3861 void *library = NULL;
3862
3863 if (!agent->valid()) {
3864 char buffer[JVM_MAXPATHLEN];
3865 char ebuf[1024] = "";
3866 const char *name = agent->name();
3867 const char *msg = "Could not find agent library ";
3868
3869 // First check to see if agent is statically linked into executable
3870 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3871 library = agent->os_lib();
3872 } else if (agent->is_absolute_path()) {
3873 library = os::dll_load(name, ebuf, sizeof ebuf);
3874 if (library == NULL) {
3875 const char *sub_msg = " in absolute path, with error: ";
3876 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3877 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3878 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3879 // If we can't find the agent, exit.
3880 vm_exit_during_initialization(buf, NULL);
3881 FREE_C_HEAP_ARRAY(char, buf);
3882 }
3883 } else {
3884 // Try to load the agent from the standard dll directory
3885 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3886 name)) {
3887 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3888 }
3889 if (library == NULL) { // Try the local directory
3890 char ns[1] = {0};
3891 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3892 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3893 }
3894 if (library == NULL) {
3895 const char *sub_msg = " on the library path, with error: ";
3896 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3897 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3898 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3899 // If we can't find the agent, exit.
3900 vm_exit_during_initialization(buf, NULL);
3901 FREE_C_HEAP_ARRAY(char, buf);
3902 }
3903 }
3904 }
3905 agent->set_os_lib(library);
3906 agent->set_valid();
3907 }
3908
3909 // Find the OnLoad function.
3910 on_load_entry =
3911 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3912 false,
3913 on_load_symbols,
3914 num_symbol_entries));
3915 return on_load_entry;
3916 }
3917
3918 // Find the JVM_OnLoad entry point
3919 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3920 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3921 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3922 }
3923
3924 // Find the Agent_OnLoad entry point
3925 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3926 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3927 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3928 }
3929
3930 // For backwards compatibility with -Xrun
3931 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3932 // treated like -agentpath:
3933 // Must be called before agent libraries are created
3934 void Threads::convert_vm_init_libraries_to_agents() {
3935 AgentLibrary* agent;
3936 AgentLibrary* next;
3937
3938 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3939 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3940 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3941
3942 // If there is an JVM_OnLoad function it will get called later,
3943 // otherwise see if there is an Agent_OnLoad
3944 if (on_load_entry == NULL) {
3945 on_load_entry = lookup_agent_on_load(agent);
3946 if (on_load_entry != NULL) {
3947 // switch it to the agent list -- so that Agent_OnLoad will be called,
3948 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3949 Arguments::convert_library_to_agent(agent);
3950 } else {
3951 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3952 }
3953 }
3954 }
3955 }
3956
3957 // Create agents for -agentlib: -agentpath: and converted -Xrun
3958 // Invokes Agent_OnLoad
3959 // Called very early -- before JavaThreads exist
3960 void Threads::create_vm_init_agents() {
3961 extern struct JavaVM_ main_vm;
3962 AgentLibrary* agent;
3963
3964 JvmtiExport::enter_onload_phase();
3965
3966 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3967 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3968
3969 if (on_load_entry != NULL) {
3970 // Invoke the Agent_OnLoad function
3971 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3972 if (err != JNI_OK) {
3973 vm_exit_during_initialization("agent library failed to init", agent->name());
3974 }
3975 } else {
3976 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3977 }
3978 }
3979 JvmtiExport::enter_primordial_phase();
3980 }
3981
3982 extern "C" {
3983 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3984 }
3985
3986 void Threads::shutdown_vm_agents() {
3987 // Send any Agent_OnUnload notifications
3988 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3989 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3990 extern struct JavaVM_ main_vm;
3991 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3992
3993 // Find the Agent_OnUnload function.
3994 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3995 os::find_agent_function(agent,
3996 false,
3997 on_unload_symbols,
3998 num_symbol_entries));
3999
4000 // Invoke the Agent_OnUnload function
4001 if (unload_entry != NULL) {
4002 JavaThread* thread = JavaThread::current();
4003 ThreadToNativeFromVM ttn(thread);
4004 HandleMark hm(thread);
4005 (*unload_entry)(&main_vm);
4006 }
4007 }
4008 }
4009
4010 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4011 // Invokes JVM_OnLoad
4012 void Threads::create_vm_init_libraries() {
4013 extern struct JavaVM_ main_vm;
4014 AgentLibrary* agent;
4015
4016 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4017 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4018
4019 if (on_load_entry != NULL) {
4020 // Invoke the JVM_OnLoad function
4021 JavaThread* thread = JavaThread::current();
4022 ThreadToNativeFromVM ttn(thread);
4023 HandleMark hm(thread);
4024 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4025 if (err != JNI_OK) {
4026 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4027 }
4028 } else {
4029 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4030 }
4031 }
4032 }
4033
4034 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4035 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4036
4037 JavaThread* java_thread = NULL;
4038 // Sequential search for now. Need to do better optimization later.
4039 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4040 oop tobj = thread->threadObj();
4041 if (!thread->is_exiting() &&
4042 tobj != NULL &&
4043 java_tid == java_lang_Thread::thread_id(tobj)) {
4044 java_thread = thread;
4045 break;
4046 }
4047 }
4048 return java_thread;
4049 }
4050
4051
4052 // Last thread running calls java.lang.Shutdown.shutdown()
4053 void JavaThread::invoke_shutdown_hooks() {
4054 HandleMark hm(this);
4055
4056 // We could get here with a pending exception, if so clear it now.
4057 if (this->has_pending_exception()) {
4058 this->clear_pending_exception();
4059 }
4060
4061 EXCEPTION_MARK;
4062 Klass* k =
4063 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4064 THREAD);
4065 if (k != NULL) {
4066 // SystemDictionary::resolve_or_null will return null if there was
4067 // an exception. If we cannot load the Shutdown class, just don't
4068 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4069 // and finalizers (if runFinalizersOnExit is set) won't be run.
4070 // Note that if a shutdown hook was registered or runFinalizersOnExit
4071 // was called, the Shutdown class would have already been loaded
4072 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4073 instanceKlassHandle shutdown_klass (THREAD, k);
4074 JavaValue result(T_VOID);
4075 JavaCalls::call_static(&result,
4076 shutdown_klass,
4077 vmSymbols::shutdown_method_name(),
4078 vmSymbols::void_method_signature(),
4079 THREAD);
4080 }
4081 CLEAR_PENDING_EXCEPTION;
4082 }
4083
4084 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4085 // the program falls off the end of main(). Another VM exit path is through
4086 // vm_exit() when the program calls System.exit() to return a value or when
4087 // there is a serious error in VM. The two shutdown paths are not exactly
4088 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4089 // and VM_Exit op at VM level.
4090 //
4091 // Shutdown sequence:
4092 // + Shutdown native memory tracking if it is on
4093 // + Wait until we are the last non-daemon thread to execute
4094 // <-- every thing is still working at this moment -->
4095 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4096 // shutdown hooks, run finalizers if finalization-on-exit
4097 // + Call before_exit(), prepare for VM exit
4098 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4099 // currently the only user of this mechanism is File.deleteOnExit())
4100 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4101 // post thread end and vm death events to JVMTI,
4102 // stop signal thread
4103 // + Call JavaThread::exit(), it will:
4104 // > release JNI handle blocks, remove stack guard pages
4105 // > remove this thread from Threads list
4106 // <-- no more Java code from this thread after this point -->
4107 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4108 // the compiler threads at safepoint
4109 // <-- do not use anything that could get blocked by Safepoint -->
4110 // + Disable tracing at JNI/JVM barriers
4111 // + Set _vm_exited flag for threads that are still running native code
4112 // + Delete this thread
4113 // + Call exit_globals()
4114 // > deletes tty
4115 // > deletes PerfMemory resources
4116 // + Return to caller
4117
4118 bool Threads::destroy_vm() {
4119 JavaThread* thread = JavaThread::current();
4120
4121 #ifdef ASSERT
4122 _vm_complete = false;
4123 #endif
4124 // Wait until we are the last non-daemon thread to execute
4125 { MutexLocker nu(Threads_lock);
4126 while (Threads::number_of_non_daemon_threads() > 1)
4127 // This wait should make safepoint checks, wait without a timeout,
4128 // and wait as a suspend-equivalent condition.
4129 //
4130 // Note: If the FlatProfiler is running and this thread is waiting
4131 // for another non-daemon thread to finish, then the FlatProfiler
4132 // is waiting for the external suspend request on this thread to
4133 // complete. wait_for_ext_suspend_completion() will eventually
4134 // timeout, but that takes time. Making this wait a suspend-
4135 // equivalent condition solves that timeout problem.
4136 //
4137 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4138 Mutex::_as_suspend_equivalent_flag);
4139 }
4140
4141 // Hang forever on exit if we are reporting an error.
4142 if (ShowMessageBoxOnError && is_error_reported()) {
4143 os::infinite_sleep();
4144 }
4145 os::wait_for_keypress_at_exit();
4146
4147 // run Java level shutdown hooks
4148 thread->invoke_shutdown_hooks();
4149
4150 before_exit(thread);
4151
4152 thread->exit(true);
4153
4154 // Stop VM thread.
4155 {
4156 // 4945125 The vm thread comes to a safepoint during exit.
4157 // GC vm_operations can get caught at the safepoint, and the
4158 // heap is unparseable if they are caught. Grab the Heap_lock
4159 // to prevent this. The GC vm_operations will not be able to
4160 // queue until after the vm thread is dead. After this point,
4161 // we'll never emerge out of the safepoint before the VM exits.
4162
4163 MutexLocker ml(Heap_lock);
4164
4165 VMThread::wait_for_vm_thread_exit();
4166 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4167 VMThread::destroy();
4168 }
4169
4170 // clean up ideal graph printers
4171 #if defined(COMPILER2) && !defined(PRODUCT)
4172 IdealGraphPrinter::clean_up();
4173 #endif
4174
4175 // Now, all Java threads are gone except daemon threads. Daemon threads
4176 // running Java code or in VM are stopped by the Safepoint. However,
4177 // daemon threads executing native code are still running. But they
4178 // will be stopped at native=>Java/VM barriers. Note that we can't
4179 // simply kill or suspend them, as it is inherently deadlock-prone.
4180
4181 VM_Exit::set_vm_exited();
4182
4183 notify_vm_shutdown();
4184
4185 delete thread;
4186
4187 #if INCLUDE_JVMCI
4188 if (JVMCICounterSize > 0) {
4189 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4190 }
4191 #endif
4192
4193 // exit_globals() will delete tty
4194 exit_globals();
4195
4196 LogConfiguration::finalize();
4197
4198 return true;
4199 }
4200
4201
4202 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4203 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4204 return is_supported_jni_version(version);
4205 }
4206
4207
4208 jboolean Threads::is_supported_jni_version(jint version) {
4209 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4210 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4211 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4212 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4213 if (version == JNI_VERSION_9) return JNI_TRUE;
4214 return JNI_FALSE;
4215 }
4216
4217
4218 void Threads::add(JavaThread* p, bool force_daemon) {
4219 // The threads lock must be owned at this point
4220 assert_locked_or_safepoint(Threads_lock);
4221
4222 // See the comment for this method in thread.hpp for its purpose and
4223 // why it is called here.
4224 p->initialize_queues();
4225 p->set_next(_thread_list);
4226 _thread_list = p;
4227 _number_of_threads++;
4228 oop threadObj = p->threadObj();
4229 bool daemon = true;
4230 // Bootstrapping problem: threadObj can be null for initial
4231 // JavaThread (or for threads attached via JNI)
4232 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4233 _number_of_non_daemon_threads++;
4234 daemon = false;
4235 }
4236
4237 ThreadService::add_thread(p, daemon);
4238
4239 // Possible GC point.
4240 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4241 }
4242
4243 void Threads::remove(JavaThread* p) {
4244 // Extra scope needed for Thread_lock, so we can check
4245 // that we do not remove thread without safepoint code notice
4246 { MutexLocker ml(Threads_lock);
4247
4248 assert(includes(p), "p must be present");
4249
4250 JavaThread* current = _thread_list;
4251 JavaThread* prev = NULL;
4252
4253 while (current != p) {
4254 prev = current;
4255 current = current->next();
4256 }
4257
4258 if (prev) {
4259 prev->set_next(current->next());
4260 } else {
4261 _thread_list = p->next();
4262 }
4263 _number_of_threads--;
4264 oop threadObj = p->threadObj();
4265 bool daemon = true;
4266 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4267 _number_of_non_daemon_threads--;
4268 daemon = false;
4269
4270 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4271 // on destroy_vm will wake up.
4272 if (number_of_non_daemon_threads() == 1) {
4273 Threads_lock->notify_all();
4274 }
4275 }
4276 ThreadService::remove_thread(p, daemon);
4277
4278 // Make sure that safepoint code disregard this thread. This is needed since
4279 // the thread might mess around with locks after this point. This can cause it
4280 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4281 // of this thread since it is removed from the queue.
4282 p->set_terminated_value();
4283 } // unlock Threads_lock
4284
4285 // Since Events::log uses a lock, we grab it outside the Threads_lock
4286 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4287 }
4288
4289 // Threads_lock must be held when this is called (or must be called during a safepoint)
4290 bool Threads::includes(JavaThread* p) {
4291 assert(Threads_lock->is_locked(), "sanity check");
4292 ALL_JAVA_THREADS(q) {
4293 if (q == p) {
4294 return true;
4295 }
4296 }
4297 return false;
4298 }
4299
4300 // Operations on the Threads list for GC. These are not explicitly locked,
4301 // but the garbage collector must provide a safe context for them to run.
4302 // In particular, these things should never be called when the Threads_lock
4303 // is held by some other thread. (Note: the Safepoint abstraction also
4304 // uses the Threads_lock to guarantee this property. It also makes sure that
4305 // all threads gets blocked when exiting or starting).
4306
4307 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4308 ALL_JAVA_THREADS(p) {
4309 p->oops_do(f, cf);
4310 }
4311 VMThread::vm_thread()->oops_do(f, cf);
4312 }
4313
4314 void Threads::change_thread_claim_parity() {
4315 // Set the new claim parity.
4316 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4317 "Not in range.");
4318 _thread_claim_parity++;
4319 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4320 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4321 "Not in range.");
4322 }
4323
4324 #ifdef ASSERT
4325 void Threads::assert_all_threads_claimed() {
4326 ALL_JAVA_THREADS(p) {
4327 const int thread_parity = p->oops_do_parity();
4328 assert((thread_parity == _thread_claim_parity),
4329 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4330 }
4331 }
4332 #endif // ASSERT
4333
4334 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4335 int cp = Threads::thread_claim_parity();
4336 ALL_JAVA_THREADS(p) {
4337 if (p->claim_oops_do(is_par, cp)) {
4338 p->oops_do(f, cf);
4339 }
4340 }
4341 VMThread* vmt = VMThread::vm_thread();
4342 if (vmt->claim_oops_do(is_par, cp)) {
4343 vmt->oops_do(f, cf);
4344 }
4345 }
4346
4347 void Threads::nmethods_do(CodeBlobClosure* cf) {
4348 ALL_JAVA_THREADS(p) {
4349 // This is used by the code cache sweeper to mark nmethods that are active
4350 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4351 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4352 if(!p->is_Code_cache_sweeper_thread()) {
4353 p->nmethods_do(cf);
4354 }
4355 }
4356 }
4357
4358 void Threads::metadata_do(void f(Metadata*)) {
4359 ALL_JAVA_THREADS(p) {
4360 p->metadata_do(f);
4361 }
4362 }
4363
4364 class ThreadHandlesClosure : public ThreadClosure {
4365 void (*_f)(Metadata*);
4366 public:
4367 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4368 virtual void do_thread(Thread* thread) {
4369 thread->metadata_handles_do(_f);
4370 }
4371 };
4372
4373 void Threads::metadata_handles_do(void f(Metadata*)) {
4374 // Only walk the Handles in Thread.
4375 ThreadHandlesClosure handles_closure(f);
4376 threads_do(&handles_closure);
4377 }
4378
4379 void Threads::deoptimized_wrt_marked_nmethods() {
4380 ALL_JAVA_THREADS(p) {
4381 p->deoptimized_wrt_marked_nmethods();
4382 }
4383 }
4384
4385
4386 // Get count Java threads that are waiting to enter the specified monitor.
4387 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4388 address monitor,
4389 bool doLock) {
4390 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4391 "must grab Threads_lock or be at safepoint");
4392 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4393
4394 int i = 0;
4395 {
4396 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4397 ALL_JAVA_THREADS(p) {
4398 if (!p->can_call_java()) continue;
4399
4400 address pending = (address)p->current_pending_monitor();
4401 if (pending == monitor) { // found a match
4402 if (i < count) result->append(p); // save the first count matches
4403 i++;
4404 }
4405 }
4406 }
4407 return result;
4408 }
4409
4410
4411 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4412 bool doLock) {
4413 assert(doLock ||
4414 Threads_lock->owned_by_self() ||
4415 SafepointSynchronize::is_at_safepoint(),
4416 "must grab Threads_lock or be at safepoint");
4417
4418 // NULL owner means not locked so we can skip the search
4419 if (owner == NULL) return NULL;
4420
4421 {
4422 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4423 ALL_JAVA_THREADS(p) {
4424 // first, see if owner is the address of a Java thread
4425 if (owner == (address)p) return p;
4426 }
4427 }
4428 // Cannot assert on lack of success here since this function may be
4429 // used by code that is trying to report useful problem information
4430 // like deadlock detection.
4431 if (UseHeavyMonitors) return NULL;
4432
4433 // If we didn't find a matching Java thread and we didn't force use of
4434 // heavyweight monitors, then the owner is the stack address of the
4435 // Lock Word in the owning Java thread's stack.
4436 //
4437 JavaThread* the_owner = NULL;
4438 {
4439 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4440 ALL_JAVA_THREADS(q) {
4441 if (q->is_lock_owned(owner)) {
4442 the_owner = q;
4443 break;
4444 }
4445 }
4446 }
4447 // cannot assert on lack of success here; see above comment
4448 return the_owner;
4449 }
4450
4451 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4452 void Threads::print_on(outputStream* st, bool print_stacks,
4453 bool internal_format, bool print_concurrent_locks) {
4454 char buf[32];
4455 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4456
4457 st->print_cr("Full thread dump %s (%s %s):",
4458 Abstract_VM_Version::vm_name(),
4459 Abstract_VM_Version::vm_release(),
4460 Abstract_VM_Version::vm_info_string());
4461 st->cr();
4462
4463 #if INCLUDE_SERVICES
4464 // Dump concurrent locks
4465 ConcurrentLocksDump concurrent_locks;
4466 if (print_concurrent_locks) {
4467 concurrent_locks.dump_at_safepoint();
4468 }
4469 #endif // INCLUDE_SERVICES
4470
4471 ALL_JAVA_THREADS(p) {
4472 ResourceMark rm;
4473 p->print_on(st);
4474 if (print_stacks) {
4475 if (internal_format) {
4476 p->trace_stack();
4477 } else {
4478 p->print_stack_on(st);
4479 }
4480 }
4481 st->cr();
4482 #if INCLUDE_SERVICES
4483 if (print_concurrent_locks) {
4484 concurrent_locks.print_locks_on(p, st);
4485 }
4486 #endif // INCLUDE_SERVICES
4487 }
4488
4489 VMThread::vm_thread()->print_on(st);
4490 st->cr();
4491 GC::gc()->heap()->print_gc_threads_on(st);
4492 WatcherThread* wt = WatcherThread::watcher_thread();
4493 if (wt != NULL) {
4494 wt->print_on(st);
4495 st->cr();
4496 }
4497 st->flush();
4498 }
4499
4500 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4501 int buflen, bool* found_current) {
4502 if (this_thread != NULL) {
4503 bool is_current = (current == this_thread);
4504 *found_current = *found_current || is_current;
4505 st->print("%s", is_current ? "=>" : " ");
4506
4507 st->print(PTR_FORMAT, p2i(this_thread));
4508 st->print(" ");
4509 this_thread->print_on_error(st, buf, buflen);
4510 st->cr();
4511 }
4512 }
4513
4514 class PrintOnErrorClosure : public ThreadClosure {
4515 outputStream* _st;
4516 Thread* _current;
4517 char* _buf;
4518 int _buflen;
4519 bool* _found_current;
4520 public:
4521 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4522 int buflen, bool* found_current) :
4523 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4524
4525 virtual void do_thread(Thread* thread) {
4526 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4527 }
4528 };
4529
4530 // Threads::print_on_error() is called by fatal error handler. It's possible
4531 // that VM is not at safepoint and/or current thread is inside signal handler.
4532 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4533 // memory (even in resource area), it might deadlock the error handler.
4534 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4535 int buflen) {
4536 bool found_current = false;
4537 st->print_cr("Java Threads: ( => current thread )");
4538 ALL_JAVA_THREADS(thread) {
4539 print_on_error(thread, st, current, buf, buflen, &found_current);
4540 }
4541 st->cr();
4542
4543 st->print_cr("Other Threads:");
4544 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4545 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4546
4547 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4548 GC::gc()->heap()->gc_threads_do(&print_closure);
4549
4550 if (!found_current) {
4551 st->cr();
4552 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4553 current->print_on_error(st, buf, buflen);
4554 st->cr();
4555 }
4556 st->cr();
4557 st->print_cr("Threads with active compile tasks:");
4558 print_threads_compiling(st, buf, buflen);
4559 }
4560
4561 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4562 ALL_JAVA_THREADS(thread) {
4563 if (thread->is_Compiler_thread()) {
4564 CompilerThread* ct = (CompilerThread*) thread;
4565 if (ct->task() != NULL) {
4566 thread->print_name_on_error(st, buf, buflen);
4567 ct->task()->print(st, NULL, true, true);
4568 }
4569 }
4570 }
4571 }
4572
4573
4574 // Internal SpinLock and Mutex
4575 // Based on ParkEvent
4576
4577 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4578 //
4579 // We employ SpinLocks _only for low-contention, fixed-length
4580 // short-duration critical sections where we're concerned
4581 // about native mutex_t or HotSpot Mutex:: latency.
4582 // The mux construct provides a spin-then-block mutual exclusion
4583 // mechanism.
4584 //
4585 // Testing has shown that contention on the ListLock guarding gFreeList
4586 // is common. If we implement ListLock as a simple SpinLock it's common
4587 // for the JVM to devolve to yielding with little progress. This is true
4588 // despite the fact that the critical sections protected by ListLock are
4589 // extremely short.
4590 //
4591 // TODO-FIXME: ListLock should be of type SpinLock.
4592 // We should make this a 1st-class type, integrated into the lock
4593 // hierarchy as leaf-locks. Critically, the SpinLock structure
4594 // should have sufficient padding to avoid false-sharing and excessive
4595 // cache-coherency traffic.
4596
4597
4598 typedef volatile int SpinLockT;
4599
4600 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4601 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4602 return; // normal fast-path return
4603 }
4604
4605 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4606 TEVENT(SpinAcquire - ctx);
4607 int ctr = 0;
4608 int Yields = 0;
4609 for (;;) {
4610 while (*adr != 0) {
4611 ++ctr;
4612 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4613 if (Yields > 5) {
4614 os::naked_short_sleep(1);
4615 } else {
4616 os::naked_yield();
4617 ++Yields;
4618 }
4619 } else {
4620 SpinPause();
4621 }
4622 }
4623 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4624 }
4625 }
4626
4627 void Thread::SpinRelease(volatile int * adr) {
4628 assert(*adr != 0, "invariant");
4629 OrderAccess::fence(); // guarantee at least release consistency.
4630 // Roach-motel semantics.
4631 // It's safe if subsequent LDs and STs float "up" into the critical section,
4632 // but prior LDs and STs within the critical section can't be allowed
4633 // to reorder or float past the ST that releases the lock.
4634 // Loads and stores in the critical section - which appear in program
4635 // order before the store that releases the lock - must also appear
4636 // before the store that releases the lock in memory visibility order.
4637 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4638 // the ST of 0 into the lock-word which releases the lock, so fence
4639 // more than covers this on all platforms.
4640 *adr = 0;
4641 }
4642
4643 // muxAcquire and muxRelease:
4644 //
4645 // * muxAcquire and muxRelease support a single-word lock-word construct.
4646 // The LSB of the word is set IFF the lock is held.
4647 // The remainder of the word points to the head of a singly-linked list
4648 // of threads blocked on the lock.
4649 //
4650 // * The current implementation of muxAcquire-muxRelease uses its own
4651 // dedicated Thread._MuxEvent instance. If we're interested in
4652 // minimizing the peak number of extant ParkEvent instances then
4653 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4654 // as certain invariants were satisfied. Specifically, care would need
4655 // to be taken with regards to consuming unpark() "permits".
4656 // A safe rule of thumb is that a thread would never call muxAcquire()
4657 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4658 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4659 // consume an unpark() permit intended for monitorenter, for instance.
4660 // One way around this would be to widen the restricted-range semaphore
4661 // implemented in park(). Another alternative would be to provide
4662 // multiple instances of the PlatformEvent() for each thread. One
4663 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4664 //
4665 // * Usage:
4666 // -- Only as leaf locks
4667 // -- for short-term locking only as muxAcquire does not perform
4668 // thread state transitions.
4669 //
4670 // Alternatives:
4671 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4672 // but with parking or spin-then-park instead of pure spinning.
4673 // * Use Taura-Oyama-Yonenzawa locks.
4674 // * It's possible to construct a 1-0 lock if we encode the lockword as
4675 // (List,LockByte). Acquire will CAS the full lockword while Release
4676 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4677 // acquiring threads use timers (ParkTimed) to detect and recover from
4678 // the stranding window. Thread/Node structures must be aligned on 256-byte
4679 // boundaries by using placement-new.
4680 // * Augment MCS with advisory back-link fields maintained with CAS().
4681 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4682 // The validity of the backlinks must be ratified before we trust the value.
4683 // If the backlinks are invalid the exiting thread must back-track through the
4684 // the forward links, which are always trustworthy.
4685 // * Add a successor indication. The LockWord is currently encoded as
4686 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4687 // to provide the usual futile-wakeup optimization.
4688 // See RTStt for details.
4689 // * Consider schedctl.sc_nopreempt to cover the critical section.
4690 //
4691
4692
4693 typedef volatile intptr_t MutexT; // Mux Lock-word
4694 enum MuxBits { LOCKBIT = 1 };
4695
4696 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4697 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4698 if (w == 0) return;
4699 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4700 return;
4701 }
4702
4703 TEVENT(muxAcquire - Contention);
4704 ParkEvent * const Self = Thread::current()->_MuxEvent;
4705 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4706 for (;;) {
4707 int its = (os::is_MP() ? 100 : 0) + 1;
4708
4709 // Optional spin phase: spin-then-park strategy
4710 while (--its >= 0) {
4711 w = *Lock;
4712 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4713 return;
4714 }
4715 }
4716
4717 Self->reset();
4718 Self->OnList = intptr_t(Lock);
4719 // The following fence() isn't _strictly necessary as the subsequent
4720 // CAS() both serializes execution and ratifies the fetched *Lock value.
4721 OrderAccess::fence();
4722 for (;;) {
4723 w = *Lock;
4724 if ((w & LOCKBIT) == 0) {
4725 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4726 Self->OnList = 0; // hygiene - allows stronger asserts
4727 return;
4728 }
4729 continue; // Interference -- *Lock changed -- Just retry
4730 }
4731 assert(w & LOCKBIT, "invariant");
4732 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4733 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4734 }
4735
4736 while (Self->OnList != 0) {
4737 Self->park();
4738 }
4739 }
4740 }
4741
4742 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4743 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4744 if (w == 0) return;
4745 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4746 return;
4747 }
4748
4749 TEVENT(muxAcquire - Contention);
4750 ParkEvent * ReleaseAfter = NULL;
4751 if (ev == NULL) {
4752 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4753 }
4754 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4755 for (;;) {
4756 guarantee(ev->OnList == 0, "invariant");
4757 int its = (os::is_MP() ? 100 : 0) + 1;
4758
4759 // Optional spin phase: spin-then-park strategy
4760 while (--its >= 0) {
4761 w = *Lock;
4762 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4763 if (ReleaseAfter != NULL) {
4764 ParkEvent::Release(ReleaseAfter);
4765 }
4766 return;
4767 }
4768 }
4769
4770 ev->reset();
4771 ev->OnList = intptr_t(Lock);
4772 // The following fence() isn't _strictly necessary as the subsequent
4773 // CAS() both serializes execution and ratifies the fetched *Lock value.
4774 OrderAccess::fence();
4775 for (;;) {
4776 w = *Lock;
4777 if ((w & LOCKBIT) == 0) {
4778 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4779 ev->OnList = 0;
4780 // We call ::Release while holding the outer lock, thus
4781 // artificially lengthening the critical section.
4782 // Consider deferring the ::Release() until the subsequent unlock(),
4783 // after we've dropped the outer lock.
4784 if (ReleaseAfter != NULL) {
4785 ParkEvent::Release(ReleaseAfter);
4786 }
4787 return;
4788 }
4789 continue; // Interference -- *Lock changed -- Just retry
4790 }
4791 assert(w & LOCKBIT, "invariant");
4792 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4793 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4794 }
4795
4796 while (ev->OnList != 0) {
4797 ev->park();
4798 }
4799 }
4800 }
4801
4802 // Release() must extract a successor from the list and then wake that thread.
4803 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4804 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4805 // Release() would :
4806 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4807 // (B) Extract a successor from the private list "in-hand"
4808 // (C) attempt to CAS() the residual back into *Lock over null.
4809 // If there were any newly arrived threads and the CAS() would fail.
4810 // In that case Release() would detach the RATs, re-merge the list in-hand
4811 // with the RATs and repeat as needed. Alternately, Release() might
4812 // detach and extract a successor, but then pass the residual list to the wakee.
4813 // The wakee would be responsible for reattaching and remerging before it
4814 // competed for the lock.
4815 //
4816 // Both "pop" and DMR are immune from ABA corruption -- there can be
4817 // multiple concurrent pushers, but only one popper or detacher.
4818 // This implementation pops from the head of the list. This is unfair,
4819 // but tends to provide excellent throughput as hot threads remain hot.
4820 // (We wake recently run threads first).
4821 //
4822 // All paths through muxRelease() will execute a CAS.
4823 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4824 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4825 // executed within the critical section are complete and globally visible before the
4826 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4827 void Thread::muxRelease(volatile intptr_t * Lock) {
4828 for (;;) {
4829 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4830 assert(w & LOCKBIT, "invariant");
4831 if (w == LOCKBIT) return;
4832 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4833 assert(List != NULL, "invariant");
4834 assert(List->OnList == intptr_t(Lock), "invariant");
4835 ParkEvent * const nxt = List->ListNext;
4836 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4837
4838 // The following CAS() releases the lock and pops the head element.
4839 // The CAS() also ratifies the previously fetched lock-word value.
4840 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4841 continue;
4842 }
4843 List->OnList = 0;
4844 OrderAccess::fence();
4845 List->unpark();
4846 return;
4847 }
4848 }
4849
4850
4851 void Threads::verify() {
4852 ALL_JAVA_THREADS(p) {
4853 p->verify();
4854 }
4855 VMThread* thread = VMThread::vm_thread();
4856 if (thread != NULL) thread->verify();
4857 }