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.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_ALL_GCS
106 #include "gc/shenandoah/shenandoahConcurrentThread.hpp"
107 #include "gc/cms/concurrentMarkSweepThread.hpp"
108 #include "gc/g1/concurrentMarkThread.inline.hpp"
109 #include "gc/parallel/pcTasks.hpp"
110 #endif // INCLUDE_ALL_GCS
111 #if INCLUDE_JVMCI
112 #include "jvmci/jvmciCompiler.hpp"
113 #include "jvmci/jvmciRuntime.hpp"
114 #endif
115 #ifdef COMPILER1
116 #include "c1/c1_Compiler.hpp"
117 #endif
118 #ifdef COMPILER2
119 #include "opto/c2compiler.hpp"
120 #include "opto/idealGraphPrinter.hpp"
121 #endif
122 #if INCLUDE_RTM_OPT
123 #include "runtime/rtmLocking.hpp"
124 #endif
125
126 // Initialization after module runtime initialization
127 void universe_post_module_init(); // must happen after call_initPhase2
128
129 #ifdef DTRACE_ENABLED
130
131 // Only bother with this argument setup if dtrace is available
132
133 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
134 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
135
136 #define DTRACE_THREAD_PROBE(probe, javathread) \
137 { \
138 ResourceMark rm(this); \
139 int len = 0; \
140 const char* name = (javathread)->get_thread_name(); \
141 len = strlen(name); \
142 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
143 (char *) name, len, \
144 java_lang_Thread::thread_id((javathread)->threadObj()), \
145 (uintptr_t) (javathread)->osthread()->thread_id(), \
146 java_lang_Thread::is_daemon((javathread)->threadObj())); \
147 }
148
149 #else // ndef DTRACE_ENABLED
150
151 #define DTRACE_THREAD_PROBE(probe, javathread)
152
153 #endif // ndef DTRACE_ENABLED
154
155 #ifndef USE_LIBRARY_BASED_TLS_ONLY
156 // Current thread is maintained as a thread-local variable
157 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
158 #endif
159 // Class hierarchy
160 // - Thread
161 // - VMThread
162 // - WatcherThread
163 // - ConcurrentMarkSweepThread
164 // - JavaThread
165 // - CompilerThread
166
167 // ======= Thread ========
168 // Support for forcing alignment of thread objects for biased locking
169 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
170 if (UseBiasedLocking) {
171 const int alignment = markOopDesc::biased_lock_alignment;
172 size_t aligned_size = size + (alignment - sizeof(intptr_t));
173 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
174 : AllocateHeap(aligned_size, flags, CURRENT_PC,
175 AllocFailStrategy::RETURN_NULL);
176 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
177 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
178 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
179 "JavaThread alignment code overflowed allocated storage");
180 if (aligned_addr != real_malloc_addr) {
181 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
182 p2i(real_malloc_addr),
183 p2i(aligned_addr));
184 }
185 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
186 return aligned_addr;
187 } else {
188 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
189 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
190 }
191 }
192
193 void Thread::operator delete(void* p) {
194 if (UseBiasedLocking) {
195 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
196 FreeHeap(real_malloc_addr);
197 } else {
198 FreeHeap(p);
199 }
200 }
201
202
203 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
204 // JavaThread
205
206
207 Thread::Thread() {
208 // stack and get_thread
209 set_stack_base(NULL);
210 set_stack_size(0);
211 set_self_raw_id(0);
212 set_lgrp_id(-1);
213 DEBUG_ONLY(clear_suspendible_thread();)
214
215 // allocated data structures
216 set_osthread(NULL);
217 set_resource_area(new (mtThread)ResourceArea());
218 DEBUG_ONLY(_current_resource_mark = NULL;)
219 set_handle_area(new (mtThread) HandleArea(NULL));
220 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
221 set_active_handles(NULL);
222 set_free_handle_block(NULL);
223 set_last_handle_mark(NULL);
224
225 // This initial value ==> never claimed.
226 _oops_do_parity = 0;
227
228 // the handle mark links itself to last_handle_mark
229 new HandleMark(this);
230
231 // plain initialization
232 debug_only(_owned_locks = NULL;)
233 debug_only(_allow_allocation_count = 0;)
234 NOT_PRODUCT(_allow_safepoint_count = 0;)
235 NOT_PRODUCT(_skip_gcalot = false;)
236 _jvmti_env_iteration_count = 0;
237 set_allocated_bytes(0);
238 _vm_operation_started_count = 0;
239 _vm_operation_completed_count = 0;
240 _current_pending_monitor = NULL;
241 _current_pending_monitor_is_from_java = true;
242 _current_waiting_monitor = NULL;
243 _num_nested_signal = 0;
244 omFreeList = NULL;
245 omFreeCount = 0;
246 omFreeProvision = 32;
247 omInUseList = NULL;
248 omInUseCount = 0;
249
250 #ifdef ASSERT
251 _visited_for_critical_count = false;
252 #endif
253
254 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
255 Monitor::_safepoint_check_sometimes);
256 _suspend_flags = 0;
257
258 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
259 _hashStateX = os::random();
260 _hashStateY = 842502087;
261 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
262 _hashStateW = 273326509;
263
264 _OnTrap = 0;
265 _schedctl = NULL;
266 _Stalled = 0;
267 _TypeTag = 0x2BAD;
268
269 // Many of the following fields are effectively final - immutable
270 // Note that nascent threads can't use the Native Monitor-Mutex
271 // construct until the _MutexEvent is initialized ...
272 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
273 // we might instead use a stack of ParkEvents that we could provision on-demand.
274 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
275 // and ::Release()
276 _ParkEvent = ParkEvent::Allocate(this);
277 _SleepEvent = ParkEvent::Allocate(this);
278 _MutexEvent = ParkEvent::Allocate(this);
279 _MuxEvent = ParkEvent::Allocate(this);
280
281 #ifdef CHECK_UNHANDLED_OOPS
282 if (CheckUnhandledOops) {
283 _unhandled_oops = new UnhandledOops(this);
284 }
285 #endif // CHECK_UNHANDLED_OOPS
286 #ifdef ASSERT
287 if (UseBiasedLocking) {
288 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
289 assert(this == _real_malloc_address ||
290 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
291 "bug in forced alignment of thread objects");
292 }
293 #endif // ASSERT
294 }
295
296 void Thread::initialize_thread_current() {
297 #ifndef USE_LIBRARY_BASED_TLS_ONLY
298 assert(_thr_current == NULL, "Thread::current already initialized");
299 _thr_current = this;
300 #endif
301 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
302 ThreadLocalStorage::set_thread(this);
303 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
304 }
305
306 void Thread::clear_thread_current() {
307 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
308 #ifndef USE_LIBRARY_BASED_TLS_ONLY
309 _thr_current = NULL;
310 #endif
311 ThreadLocalStorage::set_thread(NULL);
312 }
313
314 void Thread::record_stack_base_and_size() {
315 set_stack_base(os::current_stack_base());
316 set_stack_size(os::current_stack_size());
317 // CR 7190089: on Solaris, primordial thread's stack is adjusted
318 // in initialize_thread(). Without the adjustment, stack size is
319 // incorrect if stack is set to unlimited (ulimit -s unlimited).
320 // So far, only Solaris has real implementation of initialize_thread().
321 //
322 // set up any platform-specific state.
323 os::initialize_thread(this);
324
325 // Set stack limits after thread is initialized.
326 if (is_Java_thread()) {
327 ((JavaThread*) this)->set_stack_overflow_limit();
328 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
329 }
330 #if INCLUDE_NMT
331 // record thread's native stack, stack grows downward
332 MemTracker::record_thread_stack(stack_end(), stack_size());
333 #endif // INCLUDE_NMT
334 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
335 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
336 os::current_thread_id(), p2i(stack_base() - stack_size()),
337 p2i(stack_base()), stack_size()/1024);
338 }
339
340
341 Thread::~Thread() {
342 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
343 ObjectSynchronizer::omFlush(this);
344
345 EVENT_THREAD_DESTRUCT(this);
346
347 // stack_base can be NULL if the thread is never started or exited before
348 // record_stack_base_and_size called. Although, we would like to ensure
349 // that all started threads do call record_stack_base_and_size(), there is
350 // not proper way to enforce that.
351 #if INCLUDE_NMT
352 if (_stack_base != NULL) {
353 MemTracker::release_thread_stack(stack_end(), stack_size());
354 #ifdef ASSERT
355 set_stack_base(NULL);
356 #endif
357 }
358 #endif // INCLUDE_NMT
359
360 // deallocate data structures
361 delete resource_area();
362 // since the handle marks are using the handle area, we have to deallocated the root
363 // handle mark before deallocating the thread's handle area,
364 assert(last_handle_mark() != NULL, "check we have an element");
365 delete last_handle_mark();
366 assert(last_handle_mark() == NULL, "check we have reached the end");
367
368 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
369 // We NULL out the fields for good hygiene.
370 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
371 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
372 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
373 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
374
375 delete handle_area();
376 delete metadata_handles();
377
378 // SR_handler uses this as a termination indicator -
379 // needs to happen before os::free_thread()
380 delete _SR_lock;
381 _SR_lock = NULL;
382
383 // osthread() can be NULL, if creation of thread failed.
384 if (osthread() != NULL) os::free_thread(osthread());
385
386 // clear Thread::current if thread is deleting itself.
387 // Needed to ensure JNI correctly detects non-attached threads.
388 if (this == Thread::current()) {
389 clear_thread_current();
390 }
391
392 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
393 }
394
395 // NOTE: dummy function for assertion purpose.
396 void Thread::run() {
397 ShouldNotReachHere();
398 }
399
400 #ifdef ASSERT
401 // Private method to check for dangling thread pointer
402 void check_for_dangling_thread_pointer(Thread *thread) {
403 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
404 "possibility of dangling Thread pointer");
405 }
406 #endif
407
408 ThreadPriority Thread::get_priority(const Thread* const thread) {
409 ThreadPriority priority;
410 // Can return an error!
411 (void)os::get_priority(thread, priority);
412 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
413 return priority;
414 }
415
416 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
417 debug_only(check_for_dangling_thread_pointer(thread);)
418 // Can return an error!
419 (void)os::set_priority(thread, priority);
420 }
421
422
423 void Thread::start(Thread* thread) {
424 // Start is different from resume in that its safety is guaranteed by context or
425 // being called from a Java method synchronized on the Thread object.
426 if (!DisableStartThread) {
427 if (thread->is_Java_thread()) {
428 // Initialize the thread state to RUNNABLE before starting this thread.
429 // Can not set it after the thread started because we do not know the
430 // exact thread state at that time. It could be in MONITOR_WAIT or
431 // in SLEEPING or some other state.
432 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
433 java_lang_Thread::RUNNABLE);
434 }
435 os::start_thread(thread);
436 }
437 }
438
439 // Enqueue a VM_Operation to do the job for us - sometime later
440 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
441 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
442 VMThread::execute(vm_stop);
443 }
444
445
446 // Check if an external suspend request has completed (or has been
447 // cancelled). Returns true if the thread is externally suspended and
448 // false otherwise.
449 //
450 // The bits parameter returns information about the code path through
451 // the routine. Useful for debugging:
452 //
453 // set in is_ext_suspend_completed():
454 // 0x00000001 - routine was entered
455 // 0x00000010 - routine return false at end
456 // 0x00000100 - thread exited (return false)
457 // 0x00000200 - suspend request cancelled (return false)
458 // 0x00000400 - thread suspended (return true)
459 // 0x00001000 - thread is in a suspend equivalent state (return true)
460 // 0x00002000 - thread is native and walkable (return true)
461 // 0x00004000 - thread is native_trans and walkable (needed retry)
462 //
463 // set in wait_for_ext_suspend_completion():
464 // 0x00010000 - routine was entered
465 // 0x00020000 - suspend request cancelled before loop (return false)
466 // 0x00040000 - thread suspended before loop (return true)
467 // 0x00080000 - suspend request cancelled in loop (return false)
468 // 0x00100000 - thread suspended in loop (return true)
469 // 0x00200000 - suspend not completed during retry loop (return false)
470
471 // Helper class for tracing suspend wait debug bits.
472 //
473 // 0x00000100 indicates that the target thread exited before it could
474 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
475 // 0x00080000 each indicate a cancelled suspend request so they don't
476 // count as wait failures either.
477 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
478
479 class TraceSuspendDebugBits : public StackObj {
480 private:
481 JavaThread * jt;
482 bool is_wait;
483 bool called_by_wait; // meaningful when !is_wait
484 uint32_t * bits;
485
486 public:
487 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
488 uint32_t *_bits) {
489 jt = _jt;
490 is_wait = _is_wait;
491 called_by_wait = _called_by_wait;
492 bits = _bits;
493 }
494
495 ~TraceSuspendDebugBits() {
496 if (!is_wait) {
497 #if 1
498 // By default, don't trace bits for is_ext_suspend_completed() calls.
499 // That trace is very chatty.
500 return;
501 #else
502 if (!called_by_wait) {
503 // If tracing for is_ext_suspend_completed() is enabled, then only
504 // trace calls to it from wait_for_ext_suspend_completion()
505 return;
506 }
507 #endif
508 }
509
510 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
511 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
512 MutexLocker ml(Threads_lock); // needed for get_thread_name()
513 ResourceMark rm;
514
515 tty->print_cr(
516 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
517 jt->get_thread_name(), *bits);
518
519 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
520 }
521 }
522 }
523 };
524 #undef DEBUG_FALSE_BITS
525
526
527 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
528 uint32_t *bits) {
529 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
530
531 bool did_trans_retry = false; // only do thread_in_native_trans retry once
532 bool do_trans_retry; // flag to force the retry
533
534 *bits |= 0x00000001;
535
536 do {
537 do_trans_retry = false;
538
539 if (is_exiting()) {
540 // Thread is in the process of exiting. This is always checked
541 // first to reduce the risk of dereferencing a freed JavaThread.
542 *bits |= 0x00000100;
543 return false;
544 }
545
546 if (!is_external_suspend()) {
547 // Suspend request is cancelled. This is always checked before
548 // is_ext_suspended() to reduce the risk of a rogue resume
549 // confusing the thread that made the suspend request.
550 *bits |= 0x00000200;
551 return false;
552 }
553
554 if (is_ext_suspended()) {
555 // thread is suspended
556 *bits |= 0x00000400;
557 return true;
558 }
559
560 // Now that we no longer do hard suspends of threads running
561 // native code, the target thread can be changing thread state
562 // while we are in this routine:
563 //
564 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
565 //
566 // We save a copy of the thread state as observed at this moment
567 // and make our decision about suspend completeness based on the
568 // copy. This closes the race where the thread state is seen as
569 // _thread_in_native_trans in the if-thread_blocked check, but is
570 // seen as _thread_blocked in if-thread_in_native_trans check.
571 JavaThreadState save_state = thread_state();
572
573 if (save_state == _thread_blocked && is_suspend_equivalent()) {
574 // If the thread's state is _thread_blocked and this blocking
575 // condition is known to be equivalent to a suspend, then we can
576 // consider the thread to be externally suspended. This means that
577 // the code that sets _thread_blocked has been modified to do
578 // self-suspension if the blocking condition releases. We also
579 // used to check for CONDVAR_WAIT here, but that is now covered by
580 // the _thread_blocked with self-suspension check.
581 //
582 // Return true since we wouldn't be here unless there was still an
583 // external suspend request.
584 *bits |= 0x00001000;
585 return true;
586 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
587 // Threads running native code will self-suspend on native==>VM/Java
588 // transitions. If its stack is walkable (should always be the case
589 // unless this function is called before the actual java_suspend()
590 // call), then the wait is done.
591 *bits |= 0x00002000;
592 return true;
593 } else if (!called_by_wait && !did_trans_retry &&
594 save_state == _thread_in_native_trans &&
595 frame_anchor()->walkable()) {
596 // The thread is transitioning from thread_in_native to another
597 // thread state. check_safepoint_and_suspend_for_native_trans()
598 // will force the thread to self-suspend. If it hasn't gotten
599 // there yet we may have caught the thread in-between the native
600 // code check above and the self-suspend. Lucky us. If we were
601 // called by wait_for_ext_suspend_completion(), then it
602 // will be doing the retries so we don't have to.
603 //
604 // Since we use the saved thread state in the if-statement above,
605 // there is a chance that the thread has already transitioned to
606 // _thread_blocked by the time we get here. In that case, we will
607 // make a single unnecessary pass through the logic below. This
608 // doesn't hurt anything since we still do the trans retry.
609
610 *bits |= 0x00004000;
611
612 // Once the thread leaves thread_in_native_trans for another
613 // thread state, we break out of this retry loop. We shouldn't
614 // need this flag to prevent us from getting back here, but
615 // sometimes paranoia is good.
616 did_trans_retry = true;
617
618 // We wait for the thread to transition to a more usable state.
619 for (int i = 1; i <= SuspendRetryCount; i++) {
620 // We used to do an "os::yield_all(i)" call here with the intention
621 // that yielding would increase on each retry. However, the parameter
622 // is ignored on Linux which means the yield didn't scale up. Waiting
623 // on the SR_lock below provides a much more predictable scale up for
624 // the delay. It also provides a simple/direct point to check for any
625 // safepoint requests from the VMThread
626
627 // temporarily drops SR_lock while doing wait with safepoint check
628 // (if we're a JavaThread - the WatcherThread can also call this)
629 // and increase delay with each retry
630 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
631
632 // check the actual thread state instead of what we saved above
633 if (thread_state() != _thread_in_native_trans) {
634 // the thread has transitioned to another thread state so
635 // try all the checks (except this one) one more time.
636 do_trans_retry = true;
637 break;
638 }
639 } // end retry loop
640
641
642 }
643 } while (do_trans_retry);
644
645 *bits |= 0x00000010;
646 return false;
647 }
648
649 // Wait for an external suspend request to complete (or be cancelled).
650 // Returns true if the thread is externally suspended and false otherwise.
651 //
652 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
653 uint32_t *bits) {
654 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
655 false /* !called_by_wait */, bits);
656
657 // local flag copies to minimize SR_lock hold time
658 bool is_suspended;
659 bool pending;
660 uint32_t reset_bits;
661
662 // set a marker so is_ext_suspend_completed() knows we are the caller
663 *bits |= 0x00010000;
664
665 // We use reset_bits to reinitialize the bits value at the top of
666 // each retry loop. This allows the caller to make use of any
667 // unused bits for their own marking purposes.
668 reset_bits = *bits;
669
670 {
671 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
672 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
673 delay, bits);
674 pending = is_external_suspend();
675 }
676 // must release SR_lock to allow suspension to complete
677
678 if (!pending) {
679 // A cancelled suspend request is the only false return from
680 // is_ext_suspend_completed() that keeps us from entering the
681 // retry loop.
682 *bits |= 0x00020000;
683 return false;
684 }
685
686 if (is_suspended) {
687 *bits |= 0x00040000;
688 return true;
689 }
690
691 for (int i = 1; i <= retries; i++) {
692 *bits = reset_bits; // reinit to only track last retry
693
694 // We used to do an "os::yield_all(i)" call here with the intention
695 // that yielding would increase on each retry. However, the parameter
696 // is ignored on Linux which means the yield didn't scale up. Waiting
697 // on the SR_lock below provides a much more predictable scale up for
698 // the delay. It also provides a simple/direct point to check for any
699 // safepoint requests from the VMThread
700
701 {
702 MutexLocker ml(SR_lock());
703 // wait with safepoint check (if we're a JavaThread - the WatcherThread
704 // can also call this) and increase delay with each retry
705 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
706
707 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
708 delay, bits);
709
710 // It is possible for the external suspend request to be cancelled
711 // (by a resume) before the actual suspend operation is completed.
712 // Refresh our local copy to see if we still need to wait.
713 pending = is_external_suspend();
714 }
715
716 if (!pending) {
717 // A cancelled suspend request is the only false return from
718 // is_ext_suspend_completed() that keeps us from staying in the
719 // retry loop.
720 *bits |= 0x00080000;
721 return false;
722 }
723
724 if (is_suspended) {
725 *bits |= 0x00100000;
726 return true;
727 }
728 } // end retry loop
729
730 // thread did not suspend after all our retries
731 *bits |= 0x00200000;
732 return false;
733 }
734
735 #ifndef PRODUCT
736 void JavaThread::record_jump(address target, address instr, const char* file,
737 int line) {
738
739 // This should not need to be atomic as the only way for simultaneous
740 // updates is via interrupts. Even then this should be rare or non-existent
741 // and we don't care that much anyway.
742
743 int index = _jmp_ring_index;
744 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
745 _jmp_ring[index]._target = (intptr_t) target;
746 _jmp_ring[index]._instruction = (intptr_t) instr;
747 _jmp_ring[index]._file = file;
748 _jmp_ring[index]._line = line;
749 }
750 #endif // PRODUCT
751
752 // Called by flat profiler
753 // Callers have already called wait_for_ext_suspend_completion
754 // The assertion for that is currently too complex to put here:
755 bool JavaThread::profile_last_Java_frame(frame* _fr) {
756 bool gotframe = false;
757 // self suspension saves needed state.
758 if (has_last_Java_frame() && _anchor.walkable()) {
759 *_fr = pd_last_frame();
760 gotframe = true;
761 }
762 return gotframe;
763 }
764
765 void Thread::interrupt(Thread* thread) {
766 debug_only(check_for_dangling_thread_pointer(thread);)
767 os::interrupt(thread);
768 }
769
770 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
771 debug_only(check_for_dangling_thread_pointer(thread);)
772 // Note: If clear_interrupted==false, this simply fetches and
773 // returns the value of the field osthread()->interrupted().
774 return os::is_interrupted(thread, clear_interrupted);
775 }
776
777
778 // GC Support
779 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
780 jint thread_parity = _oops_do_parity;
781 if (thread_parity != strong_roots_parity) {
782 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
783 if (res == thread_parity) {
784 return true;
785 } else {
786 guarantee(res == strong_roots_parity, "Or else what?");
787 return false;
788 }
789 }
790 return false;
791 }
792
793 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
794 active_handles()->oops_do(f);
795 // Do oop for ThreadShadow
796 f->do_oop((oop*)&_pending_exception);
797 handle_area()->oops_do(f);
798 }
799
800 void Thread::metadata_handles_do(void f(Metadata*)) {
801 // Only walk the Handles in Thread.
802 if (metadata_handles() != NULL) {
803 for (int i = 0; i< metadata_handles()->length(); i++) {
804 f(metadata_handles()->at(i));
805 }
806 }
807 }
808
809 void Thread::print_on(outputStream* st) const {
810 // get_priority assumes osthread initialized
811 if (osthread() != NULL) {
812 int os_prio;
813 if (os::get_native_priority(this, &os_prio) == OS_OK) {
814 st->print("os_prio=%d ", os_prio);
815 }
816 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
817 ext().print_on(st);
818 osthread()->print_on(st);
819 }
820 debug_only(if (WizardMode) print_owned_locks_on(st);)
821 }
822
823 // Thread::print_on_error() is called by fatal error handler. Don't use
824 // any lock or allocate memory.
825 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
826 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
827
828 if (is_VM_thread()) { st->print("VMThread"); }
829 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
830 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
831 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
832 else { st->print("Thread"); }
833
834 if (is_Named_thread()) {
835 st->print(" \"%s\"", name());
836 }
837
838 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
839 p2i(stack_end()), p2i(stack_base()));
840
841 if (osthread()) {
842 st->print(" [id=%d]", osthread()->thread_id());
843 }
844 }
845
846 #ifdef ASSERT
847 void Thread::print_owned_locks_on(outputStream* st) const {
848 Monitor *cur = _owned_locks;
849 if (cur == NULL) {
850 st->print(" (no locks) ");
851 } else {
852 st->print_cr(" Locks owned:");
853 while (cur) {
854 cur->print_on(st);
855 cur = cur->next();
856 }
857 }
858 }
859
860 static int ref_use_count = 0;
861
862 bool Thread::owns_locks_but_compiled_lock() const {
863 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
864 if (cur != Compile_lock) return true;
865 }
866 return false;
867 }
868
869
870 #endif
871
872 #ifndef PRODUCT
873
874 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
875 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
876 // no threads which allow_vm_block's are held
877 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
878 // Check if current thread is allowed to block at a safepoint
879 if (!(_allow_safepoint_count == 0)) {
880 fatal("Possible safepoint reached by thread that does not allow it");
881 }
882 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
883 fatal("LEAF method calling lock?");
884 }
885
886 #ifdef ASSERT
887 if (potential_vm_operation && is_Java_thread()
888 && !Universe::is_bootstrapping()) {
889 // Make sure we do not hold any locks that the VM thread also uses.
890 // This could potentially lead to deadlocks
891 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
892 // Threads_lock is special, since the safepoint synchronization will not start before this is
893 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
894 // since it is used to transfer control between JavaThreads and the VMThread
895 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
896 if ((cur->allow_vm_block() &&
897 cur != Threads_lock &&
898 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
899 cur != VMOperationRequest_lock &&
900 cur != VMOperationQueue_lock) ||
901 cur->rank() == Mutex::special) {
902 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
903 }
904 }
905 }
906
907 if (GCALotAtAllSafepoints) {
908 // We could enter a safepoint here and thus have a gc
909 InterfaceSupport::check_gc_alot();
910 }
911 #endif
912 }
913 #endif
914
915 bool Thread::is_in_stack(address adr) const {
916 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
917 address end = os::current_stack_pointer();
918 // Allow non Java threads to call this without stack_base
919 if (_stack_base == NULL) return true;
920 if (stack_base() >= adr && adr >= end) return true;
921
922 return false;
923 }
924
925 bool Thread::is_in_usable_stack(address adr) const {
926 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
927 size_t usable_stack_size = _stack_size - stack_guard_size;
928
929 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
930 }
931
932
933 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
934 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
935 // used for compilation in the future. If that change is made, the need for these methods
936 // should be revisited, and they should be removed if possible.
937
938 bool Thread::is_lock_owned(address adr) const {
939 return on_local_stack(adr);
940 }
941
942 bool Thread::set_as_starting_thread() {
943 // NOTE: this must be called inside the main thread.
944 return os::create_main_thread((JavaThread*)this);
945 }
946
947 static void initialize_class(Symbol* class_name, TRAPS) {
948 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
949 InstanceKlass::cast(klass)->initialize(CHECK);
950 }
951
952
953 // Creates the initial ThreadGroup
954 static Handle create_initial_thread_group(TRAPS) {
955 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
956 instanceKlassHandle klass (THREAD, k);
957
958 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
959 {
960 JavaValue result(T_VOID);
961 JavaCalls::call_special(&result,
962 system_instance,
963 klass,
964 vmSymbols::object_initializer_name(),
965 vmSymbols::void_method_signature(),
966 CHECK_NH);
967 }
968 Universe::set_system_thread_group(system_instance());
969
970 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
971 {
972 JavaValue result(T_VOID);
973 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
974 JavaCalls::call_special(&result,
975 main_instance,
976 klass,
977 vmSymbols::object_initializer_name(),
978 vmSymbols::threadgroup_string_void_signature(),
979 system_instance,
980 string,
981 CHECK_NH);
982 }
983 return main_instance;
984 }
985
986 // Creates the initial Thread
987 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
988 TRAPS) {
989 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
990 instanceKlassHandle klass (THREAD, k);
991 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
992
993 java_lang_Thread::set_thread(thread_oop(), thread);
994 java_lang_Thread::set_priority(thread_oop(), NormPriority);
995 thread->set_threadObj(thread_oop());
996
997 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
998
999 JavaValue result(T_VOID);
1000 JavaCalls::call_special(&result, thread_oop,
1001 klass,
1002 vmSymbols::object_initializer_name(),
1003 vmSymbols::threadgroup_string_void_signature(),
1004 thread_group,
1005 string,
1006 CHECK_NULL);
1007 return thread_oop();
1008 }
1009
1010 char java_runtime_name[128] = "";
1011 char java_runtime_version[128] = "";
1012
1013 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1014 static const char* get_java_runtime_name(TRAPS) {
1015 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1016 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1017 fieldDescriptor fd;
1018 bool found = k != NULL &&
1019 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1020 vmSymbols::string_signature(), &fd);
1021 if (found) {
1022 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1023 if (name_oop == NULL) {
1024 return NULL;
1025 }
1026 const char* name = java_lang_String::as_utf8_string(name_oop,
1027 java_runtime_name,
1028 sizeof(java_runtime_name));
1029 return name;
1030 } else {
1031 return NULL;
1032 }
1033 }
1034
1035 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1036 static const char* get_java_runtime_version(TRAPS) {
1037 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1038 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1039 fieldDescriptor fd;
1040 bool found = k != NULL &&
1041 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1042 vmSymbols::string_signature(), &fd);
1043 if (found) {
1044 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1045 if (name_oop == NULL) {
1046 return NULL;
1047 }
1048 const char* name = java_lang_String::as_utf8_string(name_oop,
1049 java_runtime_version,
1050 sizeof(java_runtime_version));
1051 return name;
1052 } else {
1053 return NULL;
1054 }
1055 }
1056
1057 // General purpose hook into Java code, run once when the VM is initialized.
1058 // The Java library method itself may be changed independently from the VM.
1059 static void call_postVMInitHook(TRAPS) {
1060 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1061 instanceKlassHandle klass (THREAD, k);
1062 if (klass.not_null()) {
1063 JavaValue result(T_VOID);
1064 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1065 vmSymbols::void_method_signature(),
1066 CHECK);
1067 }
1068 }
1069
1070 static void reset_vm_info_property(TRAPS) {
1071 // the vm info string
1072 ResourceMark rm(THREAD);
1073 const char *vm_info = VM_Version::vm_info_string();
1074
1075 // java.lang.System class
1076 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1077 instanceKlassHandle klass (THREAD, k);
1078
1079 // setProperty arguments
1080 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1081 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1082
1083 // return value
1084 JavaValue r(T_OBJECT);
1085
1086 // public static String setProperty(String key, String value);
1087 JavaCalls::call_static(&r,
1088 klass,
1089 vmSymbols::setProperty_name(),
1090 vmSymbols::string_string_string_signature(),
1091 key_str,
1092 value_str,
1093 CHECK);
1094 }
1095
1096
1097 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1098 bool daemon, TRAPS) {
1099 assert(thread_group.not_null(), "thread group should be specified");
1100 assert(threadObj() == NULL, "should only create Java thread object once");
1101
1102 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1103 instanceKlassHandle klass (THREAD, k);
1104 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1105
1106 java_lang_Thread::set_thread(thread_oop(), this);
1107 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1108 set_threadObj(thread_oop());
1109
1110 JavaValue result(T_VOID);
1111 if (thread_name != NULL) {
1112 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1113 // Thread gets assigned specified name and null target
1114 JavaCalls::call_special(&result,
1115 thread_oop,
1116 klass,
1117 vmSymbols::object_initializer_name(),
1118 vmSymbols::threadgroup_string_void_signature(),
1119 thread_group, // Argument 1
1120 name, // Argument 2
1121 THREAD);
1122 } else {
1123 // Thread gets assigned name "Thread-nnn" and null target
1124 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1125 JavaCalls::call_special(&result,
1126 thread_oop,
1127 klass,
1128 vmSymbols::object_initializer_name(),
1129 vmSymbols::threadgroup_runnable_void_signature(),
1130 thread_group, // Argument 1
1131 Handle(), // Argument 2
1132 THREAD);
1133 }
1134
1135
1136 if (daemon) {
1137 java_lang_Thread::set_daemon(thread_oop());
1138 }
1139
1140 if (HAS_PENDING_EXCEPTION) {
1141 return;
1142 }
1143
1144 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1145 Handle threadObj(THREAD, this->threadObj());
1146
1147 JavaCalls::call_special(&result,
1148 thread_group,
1149 group,
1150 vmSymbols::add_method_name(),
1151 vmSymbols::thread_void_signature(),
1152 threadObj, // Arg 1
1153 THREAD);
1154 }
1155
1156 // NamedThread -- non-JavaThread subclasses with multiple
1157 // uniquely named instances should derive from this.
1158 NamedThread::NamedThread() : Thread() {
1159 _name = NULL;
1160 _processed_thread = NULL;
1161 _gc_id = GCId::undefined();
1162 }
1163
1164 NamedThread::~NamedThread() {
1165 if (_name != NULL) {
1166 FREE_C_HEAP_ARRAY(char, _name);
1167 _name = NULL;
1168 }
1169 }
1170
1171 void NamedThread::set_name(const char* format, ...) {
1172 guarantee(_name == NULL, "Only get to set name once.");
1173 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1174 guarantee(_name != NULL, "alloc failure");
1175 va_list ap;
1176 va_start(ap, format);
1177 jio_vsnprintf(_name, max_name_len, format, ap);
1178 va_end(ap);
1179 }
1180
1181 void NamedThread::initialize_named_thread() {
1182 set_native_thread_name(name());
1183 }
1184
1185 void NamedThread::print_on(outputStream* st) const {
1186 st->print("\"%s\" ", name());
1187 Thread::print_on(st);
1188 st->cr();
1189 }
1190
1191
1192 // ======= WatcherThread ========
1193
1194 // The watcher thread exists to simulate timer interrupts. It should
1195 // be replaced by an abstraction over whatever native support for
1196 // timer interrupts exists on the platform.
1197
1198 WatcherThread* WatcherThread::_watcher_thread = NULL;
1199 bool WatcherThread::_startable = false;
1200 volatile bool WatcherThread::_should_terminate = false;
1201
1202 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1203 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1204 if (os::create_thread(this, os::watcher_thread)) {
1205 _watcher_thread = this;
1206
1207 // Set the watcher thread to the highest OS priority which should not be
1208 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1209 // is created. The only normal thread using this priority is the reference
1210 // handler thread, which runs for very short intervals only.
1211 // If the VMThread's priority is not lower than the WatcherThread profiling
1212 // will be inaccurate.
1213 os::set_priority(this, MaxPriority);
1214 if (!DisableStartThread) {
1215 os::start_thread(this);
1216 }
1217 }
1218 }
1219
1220 int WatcherThread::sleep() const {
1221 // The WatcherThread does not participate in the safepoint protocol
1222 // for the PeriodicTask_lock because it is not a JavaThread.
1223 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1224
1225 if (_should_terminate) {
1226 // check for termination before we do any housekeeping or wait
1227 return 0; // we did not sleep.
1228 }
1229
1230 // remaining will be zero if there are no tasks,
1231 // causing the WatcherThread to sleep until a task is
1232 // enrolled
1233 int remaining = PeriodicTask::time_to_wait();
1234 int time_slept = 0;
1235
1236 // we expect this to timeout - we only ever get unparked when
1237 // we should terminate or when a new task has been enrolled
1238 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1239
1240 jlong time_before_loop = os::javaTimeNanos();
1241
1242 while (true) {
1243 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1244 remaining);
1245 jlong now = os::javaTimeNanos();
1246
1247 if (remaining == 0) {
1248 // if we didn't have any tasks we could have waited for a long time
1249 // consider the time_slept zero and reset time_before_loop
1250 time_slept = 0;
1251 time_before_loop = now;
1252 } else {
1253 // need to recalculate since we might have new tasks in _tasks
1254 time_slept = (int) ((now - time_before_loop) / 1000000);
1255 }
1256
1257 // Change to task list or spurious wakeup of some kind
1258 if (timedout || _should_terminate) {
1259 break;
1260 }
1261
1262 remaining = PeriodicTask::time_to_wait();
1263 if (remaining == 0) {
1264 // Last task was just disenrolled so loop around and wait until
1265 // another task gets enrolled
1266 continue;
1267 }
1268
1269 remaining -= time_slept;
1270 if (remaining <= 0) {
1271 break;
1272 }
1273 }
1274
1275 return time_slept;
1276 }
1277
1278 void WatcherThread::run() {
1279 assert(this == watcher_thread(), "just checking");
1280
1281 this->record_stack_base_and_size();
1282 this->set_native_thread_name(this->name());
1283 this->set_active_handles(JNIHandleBlock::allocate_block());
1284 while (true) {
1285 assert(watcher_thread() == Thread::current(), "thread consistency check");
1286 assert(watcher_thread() == this, "thread consistency check");
1287
1288 // Calculate how long it'll be until the next PeriodicTask work
1289 // should be done, and sleep that amount of time.
1290 int time_waited = sleep();
1291
1292 if (is_error_reported()) {
1293 // A fatal error has happened, the error handler(VMError::report_and_die)
1294 // should abort JVM after creating an error log file. However in some
1295 // rare cases, the error handler itself might deadlock. Here we try to
1296 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1297 //
1298 // This code is in WatcherThread because WatcherThread wakes up
1299 // periodically so the fatal error handler doesn't need to do anything;
1300 // also because the WatcherThread is less likely to crash than other
1301 // threads.
1302
1303 for (;;) {
1304 if (!ShowMessageBoxOnError
1305 && (OnError == NULL || OnError[0] == '\0')
1306 && Arguments::abort_hook() == NULL) {
1307 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1308 fdStream err(defaultStream::output_fd());
1309 err.print_raw_cr("# [ timer expired, abort... ]");
1310 // skip atexit/vm_exit/vm_abort hooks
1311 os::die();
1312 }
1313
1314 // Wake up 5 seconds later, the fatal handler may reset OnError or
1315 // ShowMessageBoxOnError when it is ready to abort.
1316 os::sleep(this, 5 * 1000, false);
1317 }
1318 }
1319
1320 if (_should_terminate) {
1321 // check for termination before posting the next tick
1322 break;
1323 }
1324
1325 PeriodicTask::real_time_tick(time_waited);
1326 }
1327
1328 // Signal that it is terminated
1329 {
1330 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1331 _watcher_thread = NULL;
1332 Terminator_lock->notify();
1333 }
1334 }
1335
1336 void WatcherThread::start() {
1337 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1338
1339 if (watcher_thread() == NULL && _startable) {
1340 _should_terminate = false;
1341 // Create the single instance of WatcherThread
1342 new WatcherThread();
1343 }
1344 }
1345
1346 void WatcherThread::make_startable() {
1347 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1348 _startable = true;
1349 }
1350
1351 void WatcherThread::stop() {
1352 {
1353 // Follow normal safepoint aware lock enter protocol since the
1354 // WatcherThread is stopped by another JavaThread.
1355 MutexLocker ml(PeriodicTask_lock);
1356 _should_terminate = true;
1357
1358 WatcherThread* watcher = watcher_thread();
1359 if (watcher != NULL) {
1360 // unpark the WatcherThread so it can see that it should terminate
1361 watcher->unpark();
1362 }
1363 }
1364
1365 MutexLocker mu(Terminator_lock);
1366
1367 while (watcher_thread() != NULL) {
1368 // This wait should make safepoint checks, wait without a timeout,
1369 // and wait as a suspend-equivalent condition.
1370 //
1371 // Note: If the FlatProfiler is running, then this thread is waiting
1372 // for the WatcherThread to terminate and the WatcherThread, via the
1373 // FlatProfiler task, is waiting for the external suspend request on
1374 // this thread to complete. wait_for_ext_suspend_completion() will
1375 // eventually timeout, but that takes time. Making this wait a
1376 // suspend-equivalent condition solves that timeout problem.
1377 //
1378 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1379 Mutex::_as_suspend_equivalent_flag);
1380 }
1381 }
1382
1383 void WatcherThread::unpark() {
1384 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1385 PeriodicTask_lock->notify();
1386 }
1387
1388 void WatcherThread::print_on(outputStream* st) const {
1389 st->print("\"%s\" ", name());
1390 Thread::print_on(st);
1391 st->cr();
1392 }
1393
1394 // ======= JavaThread ========
1395
1396 #if INCLUDE_JVMCI
1397
1398 jlong* JavaThread::_jvmci_old_thread_counters;
1399
1400 bool jvmci_counters_include(JavaThread* thread) {
1401 oop threadObj = thread->threadObj();
1402 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1403 }
1404
1405 void JavaThread::collect_counters(typeArrayOop array) {
1406 if (JVMCICounterSize > 0) {
1407 MutexLocker tl(Threads_lock);
1408 for (int i = 0; i < array->length(); i++) {
1409 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1410 }
1411 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1412 if (jvmci_counters_include(tp)) {
1413 for (int i = 0; i < array->length(); i++) {
1414 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1415 }
1416 }
1417 }
1418 }
1419 }
1420
1421 #endif // INCLUDE_JVMCI
1422
1423 // A JavaThread is a normal Java thread
1424
1425 void JavaThread::initialize() {
1426 // Initialize fields
1427
1428 set_saved_exception_pc(NULL);
1429 set_threadObj(NULL);
1430 _anchor.clear();
1431 set_entry_point(NULL);
1432 set_jni_functions(jni_functions());
1433 set_callee_target(NULL);
1434 set_vm_result(NULL);
1435 set_vm_result_2(NULL);
1436 set_vframe_array_head(NULL);
1437 set_vframe_array_last(NULL);
1438 set_deferred_locals(NULL);
1439 set_deopt_mark(NULL);
1440 set_deopt_compiled_method(NULL);
1441 clear_must_deopt_id();
1442 set_monitor_chunks(NULL);
1443 set_next(NULL);
1444 set_thread_state(_thread_new);
1445 _terminated = _not_terminated;
1446 _privileged_stack_top = NULL;
1447 _array_for_gc = NULL;
1448 _suspend_equivalent = false;
1449 _in_deopt_handler = 0;
1450 _doing_unsafe_access = false;
1451 _stack_guard_state = stack_guard_unused;
1452 #if INCLUDE_JVMCI
1453 _pending_monitorenter = false;
1454 _pending_deoptimization = -1;
1455 _pending_failed_speculation = NULL;
1456 _pending_transfer_to_interpreter = false;
1457 _adjusting_comp_level = false;
1458 _jvmci._alternate_call_target = NULL;
1459 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1460 if (JVMCICounterSize > 0) {
1461 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1462 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1463 } else {
1464 _jvmci_counters = NULL;
1465 }
1466 #endif // INCLUDE_JVMCI
1467 _reserved_stack_activation = NULL; // stack base not known yet
1468 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1469 _exception_pc = 0;
1470 _exception_handler_pc = 0;
1471 _is_method_handle_return = 0;
1472 _jvmti_thread_state= NULL;
1473 _should_post_on_exceptions_flag = JNI_FALSE;
1474 _jvmti_get_loaded_classes_closure = NULL;
1475 _interp_only_mode = 0;
1476 _special_runtime_exit_condition = _no_async_condition;
1477 _pending_async_exception = NULL;
1478 _thread_stat = NULL;
1479 _thread_stat = new ThreadStatistics();
1480 _blocked_on_compilation = false;
1481 _jni_active_critical = 0;
1482 _pending_jni_exception_check_fn = NULL;
1483 _do_not_unlock_if_synchronized = false;
1484 _cached_monitor_info = NULL;
1485 _parker = Parker::Allocate(this);
1486
1487 #ifndef PRODUCT
1488 _jmp_ring_index = 0;
1489 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1490 record_jump(NULL, NULL, NULL, 0);
1491 }
1492 #endif // PRODUCT
1493
1494 set_thread_profiler(NULL);
1495 if (FlatProfiler::is_active()) {
1496 // This is where we would decide to either give each thread it's own profiler
1497 // or use one global one from FlatProfiler,
1498 // or up to some count of the number of profiled threads, etc.
1499 ThreadProfiler* pp = new ThreadProfiler();
1500 pp->engage();
1501 set_thread_profiler(pp);
1502 }
1503
1504 // Setup safepoint state info for this thread
1505 ThreadSafepointState::create(this);
1506
1507 debug_only(_java_call_counter = 0);
1508
1509 // JVMTI PopFrame support
1510 _popframe_condition = popframe_inactive;
1511 _popframe_preserved_args = NULL;
1512 _popframe_preserved_args_size = 0;
1513 _frames_to_pop_failed_realloc = 0;
1514
1515 pd_initialize();
1516 }
1517
1518 #if INCLUDE_ALL_GCS
1519 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1520 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1521 bool JavaThread::_evacuation_in_progress_global = false;
1522 #endif // INCLUDE_ALL_GCS
1523
1524 JavaThread::JavaThread(bool is_attaching_via_jni) :
1525 Thread()
1526 #if INCLUDE_ALL_GCS
1527 , _satb_mark_queue(&_satb_mark_queue_set),
1528 _dirty_card_queue(&_dirty_card_queue_set),
1529 _evacuation_in_progress(_evacuation_in_progress_global)
1530 #endif // INCLUDE_ALL_GCS
1531 {
1532 initialize();
1533 if (is_attaching_via_jni) {
1534 _jni_attach_state = _attaching_via_jni;
1535 } else {
1536 _jni_attach_state = _not_attaching_via_jni;
1537 }
1538 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1539 }
1540
1541 bool JavaThread::reguard_stack(address cur_sp) {
1542 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1543 && _stack_guard_state != stack_guard_reserved_disabled) {
1544 return true; // Stack already guarded or guard pages not needed.
1545 }
1546
1547 if (register_stack_overflow()) {
1548 // For those architectures which have separate register and
1549 // memory stacks, we must check the register stack to see if
1550 // it has overflowed.
1551 return false;
1552 }
1553
1554 // Java code never executes within the yellow zone: the latter is only
1555 // there to provoke an exception during stack banging. If java code
1556 // is executing there, either StackShadowPages should be larger, or
1557 // some exception code in c1, c2 or the interpreter isn't unwinding
1558 // when it should.
1559 guarantee(cur_sp > stack_reserved_zone_base(),
1560 "not enough space to reguard - increase StackShadowPages");
1561 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1562 enable_stack_yellow_reserved_zone();
1563 if (reserved_stack_activation() != stack_base()) {
1564 set_reserved_stack_activation(stack_base());
1565 }
1566 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1567 set_reserved_stack_activation(stack_base());
1568 enable_stack_reserved_zone();
1569 }
1570 return true;
1571 }
1572
1573 bool JavaThread::reguard_stack(void) {
1574 return reguard_stack(os::current_stack_pointer());
1575 }
1576
1577
1578 void JavaThread::block_if_vm_exited() {
1579 if (_terminated == _vm_exited) {
1580 // _vm_exited is set at safepoint, and Threads_lock is never released
1581 // we will block here forever
1582 Threads_lock->lock_without_safepoint_check();
1583 ShouldNotReachHere();
1584 }
1585 }
1586
1587
1588 // Remove this ifdef when C1 is ported to the compiler interface.
1589 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1590 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1591
1592 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1593 Thread()
1594 #if INCLUDE_ALL_GCS
1595 , _satb_mark_queue(&_satb_mark_queue_set),
1596 _dirty_card_queue(&_dirty_card_queue_set),
1597 _evacuation_in_progress(_evacuation_in_progress_global)
1598 #endif // INCLUDE_ALL_GCS
1599 {
1600 initialize();
1601 _jni_attach_state = _not_attaching_via_jni;
1602 set_entry_point(entry_point);
1603 // Create the native thread itself.
1604 // %note runtime_23
1605 os::ThreadType thr_type = os::java_thread;
1606 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1607 os::java_thread;
1608 os::create_thread(this, thr_type, stack_sz);
1609 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1610 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1611 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1612 // the exception consists of creating the exception object & initializing it, initialization
1613 // will leave the VM via a JavaCall and then all locks must be unlocked).
1614 //
1615 // The thread is still suspended when we reach here. Thread must be explicit started
1616 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1617 // by calling Threads:add. The reason why this is not done here, is because the thread
1618 // object must be fully initialized (take a look at JVM_Start)
1619 }
1620
1621 JavaThread::~JavaThread() {
1622
1623 // JSR166 -- return the parker to the free list
1624 Parker::Release(_parker);
1625 _parker = NULL;
1626
1627 // Free any remaining previous UnrollBlock
1628 vframeArray* old_array = vframe_array_last();
1629
1630 if (old_array != NULL) {
1631 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1632 old_array->set_unroll_block(NULL);
1633 delete old_info;
1634 delete old_array;
1635 }
1636
1637 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1638 if (deferred != NULL) {
1639 // This can only happen if thread is destroyed before deoptimization occurs.
1640 assert(deferred->length() != 0, "empty array!");
1641 do {
1642 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1643 deferred->remove_at(0);
1644 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1645 delete dlv;
1646 } while (deferred->length() != 0);
1647 delete deferred;
1648 }
1649
1650 // All Java related clean up happens in exit
1651 ThreadSafepointState::destroy(this);
1652 if (_thread_profiler != NULL) delete _thread_profiler;
1653 if (_thread_stat != NULL) delete _thread_stat;
1654
1655 #if INCLUDE_JVMCI
1656 if (JVMCICounterSize > 0) {
1657 if (jvmci_counters_include(this)) {
1658 for (int i = 0; i < JVMCICounterSize; i++) {
1659 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1660 }
1661 }
1662 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1663 }
1664 #endif // INCLUDE_JVMCI
1665 }
1666
1667
1668 // The first routine called by a new Java thread
1669 void JavaThread::run() {
1670 // initialize thread-local alloc buffer related fields
1671 this->initialize_tlab();
1672
1673 // used to test validity of stack trace backs
1674 this->record_base_of_stack_pointer();
1675
1676 // Record real stack base and size.
1677 this->record_stack_base_and_size();
1678
1679 this->create_stack_guard_pages();
1680
1681 this->cache_global_variables();
1682
1683 // Thread is now sufficient initialized to be handled by the safepoint code as being
1684 // in the VM. Change thread state from _thread_new to _thread_in_vm
1685 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1686
1687 assert(JavaThread::current() == this, "sanity check");
1688 assert(!Thread::current()->owns_locks(), "sanity check");
1689
1690 DTRACE_THREAD_PROBE(start, this);
1691
1692 // This operation might block. We call that after all safepoint checks for a new thread has
1693 // been completed.
1694 this->set_active_handles(JNIHandleBlock::allocate_block());
1695
1696 if (JvmtiExport::should_post_thread_life()) {
1697 JvmtiExport::post_thread_start(this);
1698 }
1699
1700 EventThreadStart event;
1701 if (event.should_commit()) {
1702 event.set_thread(THREAD_TRACE_ID(this));
1703 event.commit();
1704 }
1705
1706 // We call another function to do the rest so we are sure that the stack addresses used
1707 // from there will be lower than the stack base just computed
1708 thread_main_inner();
1709
1710 // Note, thread is no longer valid at this point!
1711 }
1712
1713
1714 void JavaThread::thread_main_inner() {
1715 assert(JavaThread::current() == this, "sanity check");
1716 assert(this->threadObj() != NULL, "just checking");
1717
1718 // Execute thread entry point unless this thread has a pending exception
1719 // or has been stopped before starting.
1720 // Note: Due to JVM_StopThread we can have pending exceptions already!
1721 if (!this->has_pending_exception() &&
1722 !java_lang_Thread::is_stillborn(this->threadObj())) {
1723 {
1724 ResourceMark rm(this);
1725 this->set_native_thread_name(this->get_thread_name());
1726 }
1727 HandleMark hm(this);
1728 this->entry_point()(this, this);
1729 }
1730
1731 DTRACE_THREAD_PROBE(stop, this);
1732
1733 this->exit(false);
1734 delete this;
1735 }
1736
1737
1738 static void ensure_join(JavaThread* thread) {
1739 // We do not need to grap the Threads_lock, since we are operating on ourself.
1740 Handle threadObj(thread, thread->threadObj());
1741 assert(threadObj.not_null(), "java thread object must exist");
1742 ObjectLocker lock(threadObj, thread);
1743 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1744 thread->clear_pending_exception();
1745 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1746 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1747 // Clear the native thread instance - this makes isAlive return false and allows the join()
1748 // to complete once we've done the notify_all below
1749 java_lang_Thread::set_thread(threadObj(), NULL);
1750 lock.notify_all(thread);
1751 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1752 thread->clear_pending_exception();
1753 }
1754
1755
1756 // For any new cleanup additions, please check to see if they need to be applied to
1757 // cleanup_failed_attach_current_thread as well.
1758 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1759 assert(this == JavaThread::current(), "thread consistency check");
1760
1761 HandleMark hm(this);
1762 Handle uncaught_exception(this, this->pending_exception());
1763 this->clear_pending_exception();
1764 Handle threadObj(this, this->threadObj());
1765 assert(threadObj.not_null(), "Java thread object should be created");
1766
1767 if (get_thread_profiler() != NULL) {
1768 get_thread_profiler()->disengage();
1769 ResourceMark rm;
1770 get_thread_profiler()->print(get_thread_name());
1771 }
1772
1773
1774 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1775 {
1776 EXCEPTION_MARK;
1777
1778 CLEAR_PENDING_EXCEPTION;
1779 }
1780 if (!destroy_vm) {
1781 if (uncaught_exception.not_null()) {
1782 EXCEPTION_MARK;
1783 // Call method Thread.dispatchUncaughtException().
1784 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1785 JavaValue result(T_VOID);
1786 JavaCalls::call_virtual(&result,
1787 threadObj, thread_klass,
1788 vmSymbols::dispatchUncaughtException_name(),
1789 vmSymbols::throwable_void_signature(),
1790 uncaught_exception,
1791 THREAD);
1792 if (HAS_PENDING_EXCEPTION) {
1793 ResourceMark rm(this);
1794 jio_fprintf(defaultStream::error_stream(),
1795 "\nException: %s thrown from the UncaughtExceptionHandler"
1796 " in thread \"%s\"\n",
1797 pending_exception()->klass()->external_name(),
1798 get_thread_name());
1799 CLEAR_PENDING_EXCEPTION;
1800 }
1801 }
1802
1803 // Called before the java thread exit since we want to read info
1804 // from java_lang_Thread object
1805 EventThreadEnd event;
1806 if (event.should_commit()) {
1807 event.set_thread(THREAD_TRACE_ID(this));
1808 event.commit();
1809 }
1810
1811 // Call after last event on thread
1812 EVENT_THREAD_EXIT(this);
1813
1814 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1815 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1816 // is deprecated anyhow.
1817 if (!is_Compiler_thread()) {
1818 int count = 3;
1819 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1820 EXCEPTION_MARK;
1821 JavaValue result(T_VOID);
1822 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1823 JavaCalls::call_virtual(&result,
1824 threadObj, thread_klass,
1825 vmSymbols::exit_method_name(),
1826 vmSymbols::void_method_signature(),
1827 THREAD);
1828 CLEAR_PENDING_EXCEPTION;
1829 }
1830 }
1831 // notify JVMTI
1832 if (JvmtiExport::should_post_thread_life()) {
1833 JvmtiExport::post_thread_end(this);
1834 }
1835
1836 // We have notified the agents that we are exiting, before we go on,
1837 // we must check for a pending external suspend request and honor it
1838 // in order to not surprise the thread that made the suspend request.
1839 while (true) {
1840 {
1841 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1842 if (!is_external_suspend()) {
1843 set_terminated(_thread_exiting);
1844 ThreadService::current_thread_exiting(this);
1845 break;
1846 }
1847 // Implied else:
1848 // Things get a little tricky here. We have a pending external
1849 // suspend request, but we are holding the SR_lock so we
1850 // can't just self-suspend. So we temporarily drop the lock
1851 // and then self-suspend.
1852 }
1853
1854 ThreadBlockInVM tbivm(this);
1855 java_suspend_self();
1856
1857 // We're done with this suspend request, but we have to loop around
1858 // and check again. Eventually we will get SR_lock without a pending
1859 // external suspend request and will be able to mark ourselves as
1860 // exiting.
1861 }
1862 // no more external suspends are allowed at this point
1863 } else {
1864 // before_exit() has already posted JVMTI THREAD_END events
1865 }
1866
1867 // Notify waiters on thread object. This has to be done after exit() is called
1868 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1869 // group should have the destroyed bit set before waiters are notified).
1870 ensure_join(this);
1871 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1872
1873 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1874 // held by this thread must be released. The spec does not distinguish
1875 // between JNI-acquired and regular Java monitors. We can only see
1876 // regular Java monitors here if monitor enter-exit matching is broken.
1877 //
1878 // Optionally release any monitors for regular JavaThread exits. This
1879 // is provided as a work around for any bugs in monitor enter-exit
1880 // matching. This can be expensive so it is not enabled by default.
1881 //
1882 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1883 // ObjectSynchronizer::release_monitors_owned_by_thread().
1884 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1885 // Sanity check even though JNI DetachCurrentThread() would have
1886 // returned JNI_ERR if there was a Java frame. JavaThread exit
1887 // should be done executing Java code by the time we get here.
1888 assert(!this->has_last_Java_frame(),
1889 "should not have a Java frame when detaching or exiting");
1890 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1891 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1892 }
1893
1894 // These things needs to be done while we are still a Java Thread. Make sure that thread
1895 // is in a consistent state, in case GC happens
1896 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1897
1898 if (active_handles() != NULL) {
1899 JNIHandleBlock* block = active_handles();
1900 set_active_handles(NULL);
1901 JNIHandleBlock::release_block(block);
1902 }
1903
1904 if (free_handle_block() != NULL) {
1905 JNIHandleBlock* block = free_handle_block();
1906 set_free_handle_block(NULL);
1907 JNIHandleBlock::release_block(block);
1908 }
1909
1910 // These have to be removed while this is still a valid thread.
1911 remove_stack_guard_pages();
1912
1913 if (UseTLAB) {
1914 tlab().make_parsable(true); // retire TLAB
1915 }
1916
1917 if (JvmtiEnv::environments_might_exist()) {
1918 JvmtiExport::cleanup_thread(this);
1919 }
1920
1921 // We must flush any deferred card marks before removing a thread from
1922 // the list of active threads.
1923 Universe::heap()->flush_deferred_store_barrier(this);
1924 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1925
1926 #if INCLUDE_ALL_GCS
1927 // We must flush the G1-related buffers before removing a thread
1928 // from the list of active threads. We must do this after any deferred
1929 // card marks have been flushed (above) so that any entries that are
1930 // added to the thread's dirty card queue as a result are not lost.
1931 if (UseG1GC || UseShenandoahGC) {
1932 flush_barrier_queues();
1933 }
1934 if (UseShenandoahGC && UseTLAB) {
1935 gclab().make_parsable(true);
1936 }
1937 #endif // INCLUDE_ALL_GCS
1938
1939 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1940 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1941 os::current_thread_id());
1942
1943 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1944 Threads::remove(this);
1945 }
1946
1947 #if INCLUDE_ALL_GCS
1948 // Flush G1-related queues.
1949 void JavaThread::flush_barrier_queues() {
1950 satb_mark_queue().flush();
1951 dirty_card_queue().flush();
1952 }
1953
1954 void JavaThread::initialize_queues() {
1955 assert(!SafepointSynchronize::is_at_safepoint(),
1956 "we should not be at a safepoint");
1957
1958 SATBMarkQueue& satb_queue = satb_mark_queue();
1959 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1960 // The SATB queue should have been constructed with its active
1961 // field set to false.
1962 assert(!satb_queue.is_active(), "SATB queue should not be active");
1963 assert(satb_queue.is_empty(), "SATB queue should be empty");
1964 // If we are creating the thread during a marking cycle, we should
1965 // set the active field of the SATB queue to true.
1966 if (satb_queue_set.is_active()) {
1967 satb_queue.set_active(true);
1968 }
1969
1970 DirtyCardQueue& dirty_queue = dirty_card_queue();
1971 // The dirty card queue should have been constructed with its
1972 // active field set to true.
1973 assert(dirty_queue.is_active(), "dirty card queue should be active");
1974 }
1975
1976 bool JavaThread::evacuation_in_progress() const {
1977 return _evacuation_in_progress;
1978 }
1979
1980 void JavaThread::set_evacuation_in_progress(bool in_prog) {
1981 _evacuation_in_progress = in_prog;
1982 }
1983
1984 void JavaThread::set_evacuation_in_progress_all_threads(bool in_prog) {
1985 _evacuation_in_progress_global = in_prog;
1986 for (JavaThread* t = Threads::first(); t; t = t->next()) {
1987 t->set_evacuation_in_progress(in_prog);
1988 }
1989 }
1990 #endif // INCLUDE_ALL_GCS
1991
1992 void JavaThread::cleanup_failed_attach_current_thread() {
1993 if (get_thread_profiler() != NULL) {
1994 get_thread_profiler()->disengage();
1995 ResourceMark rm;
1996 get_thread_profiler()->print(get_thread_name());
1997 }
1998
1999 if (active_handles() != NULL) {
2000 JNIHandleBlock* block = active_handles();
2001 set_active_handles(NULL);
2002 JNIHandleBlock::release_block(block);
2003 }
2004
2005 if (free_handle_block() != NULL) {
2006 JNIHandleBlock* block = free_handle_block();
2007 set_free_handle_block(NULL);
2008 JNIHandleBlock::release_block(block);
2009 }
2010
2011 // These have to be removed while this is still a valid thread.
2012 remove_stack_guard_pages();
2013
2014 if (UseTLAB) {
2015 tlab().make_parsable(true); // retire TLAB, if any
2016 }
2017
2018 #if INCLUDE_ALL_GCS
2019 if (UseG1GC || UseShenandoahGC) {
2020 flush_barrier_queues();
2021 }
2022 if (UseShenandoahGC && UseTLAB) {
2023 gclab().make_parsable(true);
2024 }
2025 #endif // INCLUDE_ALL_GCS
2026
2027 Threads::remove(this);
2028 delete this;
2029 }
2030
2031
2032
2033
2034 JavaThread* JavaThread::active() {
2035 Thread* thread = Thread::current();
2036 if (thread->is_Java_thread()) {
2037 return (JavaThread*) thread;
2038 } else {
2039 assert(thread->is_VM_thread(), "this must be a vm thread");
2040 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2041 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2042 assert(ret->is_Java_thread(), "must be a Java thread");
2043 return ret;
2044 }
2045 }
2046
2047 bool JavaThread::is_lock_owned(address adr) const {
2048 if (Thread::is_lock_owned(adr)) return true;
2049
2050 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2051 if (chunk->contains(adr)) return true;
2052 }
2053
2054 return false;
2055 }
2056
2057
2058 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2059 chunk->set_next(monitor_chunks());
2060 set_monitor_chunks(chunk);
2061 }
2062
2063 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2064 guarantee(monitor_chunks() != NULL, "must be non empty");
2065 if (monitor_chunks() == chunk) {
2066 set_monitor_chunks(chunk->next());
2067 } else {
2068 MonitorChunk* prev = monitor_chunks();
2069 while (prev->next() != chunk) prev = prev->next();
2070 prev->set_next(chunk->next());
2071 }
2072 }
2073
2074 // JVM support.
2075
2076 // Note: this function shouldn't block if it's called in
2077 // _thread_in_native_trans state (such as from
2078 // check_special_condition_for_native_trans()).
2079 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2080
2081 if (has_last_Java_frame() && has_async_condition()) {
2082 // If we are at a polling page safepoint (not a poll return)
2083 // then we must defer async exception because live registers
2084 // will be clobbered by the exception path. Poll return is
2085 // ok because the call we a returning from already collides
2086 // with exception handling registers and so there is no issue.
2087 // (The exception handling path kills call result registers but
2088 // this is ok since the exception kills the result anyway).
2089
2090 if (is_at_poll_safepoint()) {
2091 // if the code we are returning to has deoptimized we must defer
2092 // the exception otherwise live registers get clobbered on the
2093 // exception path before deoptimization is able to retrieve them.
2094 //
2095 RegisterMap map(this, false);
2096 frame caller_fr = last_frame().sender(&map);
2097 assert(caller_fr.is_compiled_frame(), "what?");
2098 if (caller_fr.is_deoptimized_frame()) {
2099 log_info(exceptions)("deferred async exception at compiled safepoint");
2100 return;
2101 }
2102 }
2103 }
2104
2105 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2106 if (condition == _no_async_condition) {
2107 // Conditions have changed since has_special_runtime_exit_condition()
2108 // was called:
2109 // - if we were here only because of an external suspend request,
2110 // then that was taken care of above (or cancelled) so we are done
2111 // - if we were here because of another async request, then it has
2112 // been cleared between the has_special_runtime_exit_condition()
2113 // and now so again we are done
2114 return;
2115 }
2116
2117 // Check for pending async. exception
2118 if (_pending_async_exception != NULL) {
2119 // Only overwrite an already pending exception, if it is not a threadDeath.
2120 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2121
2122 // We cannot call Exceptions::_throw(...) here because we cannot block
2123 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2124
2125 if (log_is_enabled(Info, exceptions)) {
2126 ResourceMark rm;
2127 outputStream* logstream = Log(exceptions)::info_stream();
2128 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2129 if (has_last_Java_frame()) {
2130 frame f = last_frame();
2131 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2132 }
2133 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2134 }
2135 _pending_async_exception = NULL;
2136 clear_has_async_exception();
2137 }
2138 }
2139
2140 if (check_unsafe_error &&
2141 condition == _async_unsafe_access_error && !has_pending_exception()) {
2142 condition = _no_async_condition; // done
2143 switch (thread_state()) {
2144 case _thread_in_vm: {
2145 JavaThread* THREAD = this;
2146 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2147 }
2148 case _thread_in_native: {
2149 ThreadInVMfromNative tiv(this);
2150 JavaThread* THREAD = this;
2151 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2152 }
2153 case _thread_in_Java: {
2154 ThreadInVMfromJava tiv(this);
2155 JavaThread* THREAD = this;
2156 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2157 }
2158 default:
2159 ShouldNotReachHere();
2160 }
2161 }
2162
2163 assert(condition == _no_async_condition || has_pending_exception() ||
2164 (!check_unsafe_error && condition == _async_unsafe_access_error),
2165 "must have handled the async condition, if no exception");
2166 }
2167
2168 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2169 //
2170 // Check for pending external suspend. Internal suspend requests do
2171 // not use handle_special_runtime_exit_condition().
2172 // If JNIEnv proxies are allowed, don't self-suspend if the target
2173 // thread is not the current thread. In older versions of jdbx, jdbx
2174 // threads could call into the VM with another thread's JNIEnv so we
2175 // can be here operating on behalf of a suspended thread (4432884).
2176 bool do_self_suspend = is_external_suspend_with_lock();
2177 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2178 //
2179 // Because thread is external suspended the safepoint code will count
2180 // thread as at a safepoint. This can be odd because we can be here
2181 // as _thread_in_Java which would normally transition to _thread_blocked
2182 // at a safepoint. We would like to mark the thread as _thread_blocked
2183 // before calling java_suspend_self like all other callers of it but
2184 // we must then observe proper safepoint protocol. (We can't leave
2185 // _thread_blocked with a safepoint in progress). However we can be
2186 // here as _thread_in_native_trans so we can't use a normal transition
2187 // constructor/destructor pair because they assert on that type of
2188 // transition. We could do something like:
2189 //
2190 // JavaThreadState state = thread_state();
2191 // set_thread_state(_thread_in_vm);
2192 // {
2193 // ThreadBlockInVM tbivm(this);
2194 // java_suspend_self()
2195 // }
2196 // set_thread_state(_thread_in_vm_trans);
2197 // if (safepoint) block;
2198 // set_thread_state(state);
2199 //
2200 // but that is pretty messy. Instead we just go with the way the
2201 // code has worked before and note that this is the only path to
2202 // java_suspend_self that doesn't put the thread in _thread_blocked
2203 // mode.
2204
2205 frame_anchor()->make_walkable(this);
2206 java_suspend_self();
2207
2208 // We might be here for reasons in addition to the self-suspend request
2209 // so check for other async requests.
2210 }
2211
2212 if (check_asyncs) {
2213 check_and_handle_async_exceptions();
2214 }
2215 }
2216
2217 void JavaThread::send_thread_stop(oop java_throwable) {
2218 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2219 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2220 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2221
2222 // Do not throw asynchronous exceptions against the compiler thread
2223 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2224 if (!can_call_java()) return;
2225
2226 {
2227 // Actually throw the Throwable against the target Thread - however
2228 // only if there is no thread death exception installed already.
2229 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2230 // If the topmost frame is a runtime stub, then we are calling into
2231 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2232 // must deoptimize the caller before continuing, as the compiled exception handler table
2233 // may not be valid
2234 if (has_last_Java_frame()) {
2235 frame f = last_frame();
2236 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2237 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2238 RegisterMap reg_map(this, UseBiasedLocking);
2239 frame compiled_frame = f.sender(®_map);
2240 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2241 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2242 }
2243 }
2244 }
2245
2246 // Set async. pending exception in thread.
2247 set_pending_async_exception(java_throwable);
2248
2249 if (log_is_enabled(Info, exceptions)) {
2250 ResourceMark rm;
2251 log_info(exceptions)("Pending Async. exception installed of type: %s",
2252 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2253 }
2254 // for AbortVMOnException flag
2255 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2256 }
2257 }
2258
2259
2260 // Interrupt thread so it will wake up from a potential wait()
2261 Thread::interrupt(this);
2262 }
2263
2264 // External suspension mechanism.
2265 //
2266 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2267 // to any VM_locks and it is at a transition
2268 // Self-suspension will happen on the transition out of the vm.
2269 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2270 //
2271 // Guarantees on return:
2272 // + Target thread will not execute any new bytecode (that's why we need to
2273 // force a safepoint)
2274 // + Target thread will not enter any new monitors
2275 //
2276 void JavaThread::java_suspend() {
2277 { MutexLocker mu(Threads_lock);
2278 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2279 return;
2280 }
2281 }
2282
2283 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2284 if (!is_external_suspend()) {
2285 // a racing resume has cancelled us; bail out now
2286 return;
2287 }
2288
2289 // suspend is done
2290 uint32_t debug_bits = 0;
2291 // Warning: is_ext_suspend_completed() may temporarily drop the
2292 // SR_lock to allow the thread to reach a stable thread state if
2293 // it is currently in a transient thread state.
2294 if (is_ext_suspend_completed(false /* !called_by_wait */,
2295 SuspendRetryDelay, &debug_bits)) {
2296 return;
2297 }
2298 }
2299
2300 VM_ForceSafepoint vm_suspend;
2301 VMThread::execute(&vm_suspend);
2302 }
2303
2304 // Part II of external suspension.
2305 // A JavaThread self suspends when it detects a pending external suspend
2306 // request. This is usually on transitions. It is also done in places
2307 // where continuing to the next transition would surprise the caller,
2308 // e.g., monitor entry.
2309 //
2310 // Returns the number of times that the thread self-suspended.
2311 //
2312 // Note: DO NOT call java_suspend_self() when you just want to block current
2313 // thread. java_suspend_self() is the second stage of cooperative
2314 // suspension for external suspend requests and should only be used
2315 // to complete an external suspend request.
2316 //
2317 int JavaThread::java_suspend_self() {
2318 int ret = 0;
2319
2320 // we are in the process of exiting so don't suspend
2321 if (is_exiting()) {
2322 clear_external_suspend();
2323 return ret;
2324 }
2325
2326 assert(_anchor.walkable() ||
2327 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2328 "must have walkable stack");
2329
2330 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2331
2332 assert(!this->is_ext_suspended(),
2333 "a thread trying to self-suspend should not already be suspended");
2334
2335 if (this->is_suspend_equivalent()) {
2336 // If we are self-suspending as a result of the lifting of a
2337 // suspend equivalent condition, then the suspend_equivalent
2338 // flag is not cleared until we set the ext_suspended flag so
2339 // that wait_for_ext_suspend_completion() returns consistent
2340 // results.
2341 this->clear_suspend_equivalent();
2342 }
2343
2344 // A racing resume may have cancelled us before we grabbed SR_lock
2345 // above. Or another external suspend request could be waiting for us
2346 // by the time we return from SR_lock()->wait(). The thread
2347 // that requested the suspension may already be trying to walk our
2348 // stack and if we return now, we can change the stack out from under
2349 // it. This would be a "bad thing (TM)" and cause the stack walker
2350 // to crash. We stay self-suspended until there are no more pending
2351 // external suspend requests.
2352 while (is_external_suspend()) {
2353 ret++;
2354 this->set_ext_suspended();
2355
2356 // _ext_suspended flag is cleared by java_resume()
2357 while (is_ext_suspended()) {
2358 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2359 }
2360 }
2361
2362 return ret;
2363 }
2364
2365 #ifdef ASSERT
2366 // verify the JavaThread has not yet been published in the Threads::list, and
2367 // hence doesn't need protection from concurrent access at this stage
2368 void JavaThread::verify_not_published() {
2369 if (!Threads_lock->owned_by_self()) {
2370 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2371 assert(!Threads::includes(this),
2372 "java thread shouldn't have been published yet!");
2373 } else {
2374 assert(!Threads::includes(this),
2375 "java thread shouldn't have been published yet!");
2376 }
2377 }
2378 #endif
2379
2380 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2381 // progress or when _suspend_flags is non-zero.
2382 // Current thread needs to self-suspend if there is a suspend request and/or
2383 // block if a safepoint is in progress.
2384 // Async exception ISN'T checked.
2385 // Note only the ThreadInVMfromNative transition can call this function
2386 // directly and when thread state is _thread_in_native_trans
2387 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2388 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2389
2390 JavaThread *curJT = JavaThread::current();
2391 bool do_self_suspend = thread->is_external_suspend();
2392
2393 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2394
2395 // If JNIEnv proxies are allowed, don't self-suspend if the target
2396 // thread is not the current thread. In older versions of jdbx, jdbx
2397 // threads could call into the VM with another thread's JNIEnv so we
2398 // can be here operating on behalf of a suspended thread (4432884).
2399 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2400 JavaThreadState state = thread->thread_state();
2401
2402 // We mark this thread_blocked state as a suspend-equivalent so
2403 // that a caller to is_ext_suspend_completed() won't be confused.
2404 // The suspend-equivalent state is cleared by java_suspend_self().
2405 thread->set_suspend_equivalent();
2406
2407 // If the safepoint code sees the _thread_in_native_trans state, it will
2408 // wait until the thread changes to other thread state. There is no
2409 // guarantee on how soon we can obtain the SR_lock and complete the
2410 // self-suspend request. It would be a bad idea to let safepoint wait for
2411 // too long. Temporarily change the state to _thread_blocked to
2412 // let the VM thread know that this thread is ready for GC. The problem
2413 // of changing thread state is that safepoint could happen just after
2414 // java_suspend_self() returns after being resumed, and VM thread will
2415 // see the _thread_blocked state. We must check for safepoint
2416 // after restoring the state and make sure we won't leave while a safepoint
2417 // is in progress.
2418 thread->set_thread_state(_thread_blocked);
2419 thread->java_suspend_self();
2420 thread->set_thread_state(state);
2421 // Make sure new state is seen by VM thread
2422 if (os::is_MP()) {
2423 if (UseMembar) {
2424 // Force a fence between the write above and read below
2425 OrderAccess::fence();
2426 } else {
2427 // Must use this rather than serialization page in particular on Windows
2428 InterfaceSupport::serialize_memory(thread);
2429 }
2430 }
2431 }
2432
2433 if (SafepointSynchronize::do_call_back()) {
2434 // If we are safepointing, then block the caller which may not be
2435 // the same as the target thread (see above).
2436 SafepointSynchronize::block(curJT);
2437 }
2438
2439 if (thread->is_deopt_suspend()) {
2440 thread->clear_deopt_suspend();
2441 RegisterMap map(thread, false);
2442 frame f = thread->last_frame();
2443 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2444 f = f.sender(&map);
2445 }
2446 if (f.id() == thread->must_deopt_id()) {
2447 thread->clear_must_deopt_id();
2448 f.deoptimize(thread);
2449 } else {
2450 fatal("missed deoptimization!");
2451 }
2452 }
2453 }
2454
2455 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2456 // progress or when _suspend_flags is non-zero.
2457 // Current thread needs to self-suspend if there is a suspend request and/or
2458 // block if a safepoint is in progress.
2459 // Also check for pending async exception (not including unsafe access error).
2460 // Note only the native==>VM/Java barriers can call this function and when
2461 // thread state is _thread_in_native_trans.
2462 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2463 check_safepoint_and_suspend_for_native_trans(thread);
2464
2465 if (thread->has_async_exception()) {
2466 // We are in _thread_in_native_trans state, don't handle unsafe
2467 // access error since that may block.
2468 thread->check_and_handle_async_exceptions(false);
2469 }
2470 }
2471
2472 // This is a variant of the normal
2473 // check_special_condition_for_native_trans with slightly different
2474 // semantics for use by critical native wrappers. It does all the
2475 // normal checks but also performs the transition back into
2476 // thread_in_Java state. This is required so that critical natives
2477 // can potentially block and perform a GC if they are the last thread
2478 // exiting the GCLocker.
2479 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2480 check_special_condition_for_native_trans(thread);
2481
2482 // Finish the transition
2483 thread->set_thread_state(_thread_in_Java);
2484
2485 if (thread->do_critical_native_unlock()) {
2486 ThreadInVMfromJavaNoAsyncException tiv(thread);
2487 GCLocker::unlock_critical(thread);
2488 thread->clear_critical_native_unlock();
2489 }
2490 }
2491
2492 // We need to guarantee the Threads_lock here, since resumes are not
2493 // allowed during safepoint synchronization
2494 // Can only resume from an external suspension
2495 void JavaThread::java_resume() {
2496 assert_locked_or_safepoint(Threads_lock);
2497
2498 // Sanity check: thread is gone, has started exiting or the thread
2499 // was not externally suspended.
2500 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2501 return;
2502 }
2503
2504 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2505
2506 clear_external_suspend();
2507
2508 if (is_ext_suspended()) {
2509 clear_ext_suspended();
2510 SR_lock()->notify_all();
2511 }
2512 }
2513
2514 size_t JavaThread::_stack_red_zone_size = 0;
2515 size_t JavaThread::_stack_yellow_zone_size = 0;
2516 size_t JavaThread::_stack_reserved_zone_size = 0;
2517 size_t JavaThread::_stack_shadow_zone_size = 0;
2518
2519 void JavaThread::create_stack_guard_pages() {
2520 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2521 address low_addr = stack_end();
2522 size_t len = stack_guard_zone_size();
2523
2524 int must_commit = os::must_commit_stack_guard_pages();
2525 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2526
2527 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2528 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2529 return;
2530 }
2531
2532 if (os::guard_memory((char *) low_addr, len)) {
2533 _stack_guard_state = stack_guard_enabled;
2534 } else {
2535 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2536 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2537 if (os::uncommit_memory((char *) low_addr, len)) {
2538 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2539 }
2540 return;
2541 }
2542
2543 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2544 PTR_FORMAT "-" PTR_FORMAT ".",
2545 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2546 }
2547
2548 void JavaThread::remove_stack_guard_pages() {
2549 assert(Thread::current() == this, "from different thread");
2550 if (_stack_guard_state == stack_guard_unused) return;
2551 address low_addr = stack_end();
2552 size_t len = stack_guard_zone_size();
2553
2554 if (os::must_commit_stack_guard_pages()) {
2555 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2556 _stack_guard_state = stack_guard_unused;
2557 } else {
2558 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2559 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2560 return;
2561 }
2562 } else {
2563 if (_stack_guard_state == stack_guard_unused) return;
2564 if (os::unguard_memory((char *) low_addr, len)) {
2565 _stack_guard_state = stack_guard_unused;
2566 } else {
2567 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2568 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2569 return;
2570 }
2571 }
2572
2573 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2574 PTR_FORMAT "-" PTR_FORMAT ".",
2575 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2576 }
2577
2578 void JavaThread::enable_stack_reserved_zone() {
2579 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2580 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2581
2582 // The base notation is from the stack's point of view, growing downward.
2583 // We need to adjust it to work correctly with guard_memory()
2584 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2585
2586 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2587 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2588
2589 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2590 _stack_guard_state = stack_guard_enabled;
2591 } else {
2592 warning("Attempt to guard stack reserved zone failed.");
2593 }
2594 enable_register_stack_guard();
2595 }
2596
2597 void JavaThread::disable_stack_reserved_zone() {
2598 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2599 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2600
2601 // Simply return if called for a thread that does not use guard pages.
2602 if (_stack_guard_state == stack_guard_unused) return;
2603
2604 // The base notation is from the stack's point of view, growing downward.
2605 // We need to adjust it to work correctly with guard_memory()
2606 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2607
2608 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2609 _stack_guard_state = stack_guard_reserved_disabled;
2610 } else {
2611 warning("Attempt to unguard stack reserved zone failed.");
2612 }
2613 disable_register_stack_guard();
2614 }
2615
2616 void JavaThread::enable_stack_yellow_reserved_zone() {
2617 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2618 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2619
2620 // The base notation is from the stacks point of view, growing downward.
2621 // We need to adjust it to work correctly with guard_memory()
2622 address base = stack_red_zone_base();
2623
2624 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2625 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2626
2627 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2628 _stack_guard_state = stack_guard_enabled;
2629 } else {
2630 warning("Attempt to guard stack yellow zone failed.");
2631 }
2632 enable_register_stack_guard();
2633 }
2634
2635 void JavaThread::disable_stack_yellow_reserved_zone() {
2636 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2637 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2638
2639 // Simply return if called for a thread that does not use guard pages.
2640 if (_stack_guard_state == stack_guard_unused) return;
2641
2642 // The base notation is from the stacks point of view, growing downward.
2643 // We need to adjust it to work correctly with guard_memory()
2644 address base = stack_red_zone_base();
2645
2646 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2647 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2648 } else {
2649 warning("Attempt to unguard stack yellow zone failed.");
2650 }
2651 disable_register_stack_guard();
2652 }
2653
2654 void JavaThread::enable_stack_red_zone() {
2655 // The base notation is from the stacks point of view, growing downward.
2656 // We need to adjust it to work correctly with guard_memory()
2657 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2658 address base = stack_red_zone_base() - stack_red_zone_size();
2659
2660 guarantee(base < stack_base(), "Error calculating stack red zone");
2661 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2662
2663 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2664 warning("Attempt to guard stack red zone failed.");
2665 }
2666 }
2667
2668 void JavaThread::disable_stack_red_zone() {
2669 // The base notation is from the stacks point of view, growing downward.
2670 // We need to adjust it to work correctly with guard_memory()
2671 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2672 address base = stack_red_zone_base() - stack_red_zone_size();
2673 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2674 warning("Attempt to unguard stack red zone failed.");
2675 }
2676 }
2677
2678 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2679 // ignore is there is no stack
2680 if (!has_last_Java_frame()) return;
2681 // traverse the stack frames. Starts from top frame.
2682 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2683 frame* fr = fst.current();
2684 f(fr, fst.register_map());
2685 }
2686 }
2687
2688
2689 #ifndef PRODUCT
2690 // Deoptimization
2691 // Function for testing deoptimization
2692 void JavaThread::deoptimize() {
2693 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2694 StackFrameStream fst(this, UseBiasedLocking);
2695 bool deopt = false; // Dump stack only if a deopt actually happens.
2696 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2697 // Iterate over all frames in the thread and deoptimize
2698 for (; !fst.is_done(); fst.next()) {
2699 if (fst.current()->can_be_deoptimized()) {
2700
2701 if (only_at) {
2702 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2703 // consists of comma or carriage return separated numbers so
2704 // search for the current bci in that string.
2705 address pc = fst.current()->pc();
2706 nmethod* nm = (nmethod*) fst.current()->cb();
2707 ScopeDesc* sd = nm->scope_desc_at(pc);
2708 char buffer[8];
2709 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2710 size_t len = strlen(buffer);
2711 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2712 while (found != NULL) {
2713 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2714 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2715 // Check that the bci found is bracketed by terminators.
2716 break;
2717 }
2718 found = strstr(found + 1, buffer);
2719 }
2720 if (!found) {
2721 continue;
2722 }
2723 }
2724
2725 if (DebugDeoptimization && !deopt) {
2726 deopt = true; // One-time only print before deopt
2727 tty->print_cr("[BEFORE Deoptimization]");
2728 trace_frames();
2729 trace_stack();
2730 }
2731 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2732 }
2733 }
2734
2735 if (DebugDeoptimization && deopt) {
2736 tty->print_cr("[AFTER Deoptimization]");
2737 trace_frames();
2738 }
2739 }
2740
2741
2742 // Make zombies
2743 void JavaThread::make_zombies() {
2744 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2745 if (fst.current()->can_be_deoptimized()) {
2746 // it is a Java nmethod
2747 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2748 nm->make_not_entrant();
2749 }
2750 }
2751 }
2752 #endif // PRODUCT
2753
2754
2755 void JavaThread::deoptimized_wrt_marked_nmethods() {
2756 if (!has_last_Java_frame()) return;
2757 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2758 StackFrameStream fst(this, UseBiasedLocking);
2759 for (; !fst.is_done(); fst.next()) {
2760 if (fst.current()->should_be_deoptimized()) {
2761 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2762 }
2763 }
2764 }
2765
2766
2767 // If the caller is a NamedThread, then remember, in the current scope,
2768 // the given JavaThread in its _processed_thread field.
2769 class RememberProcessedThread: public StackObj {
2770 NamedThread* _cur_thr;
2771 public:
2772 RememberProcessedThread(JavaThread* jthr) {
2773 Thread* thread = Thread::current();
2774 if (thread->is_Named_thread()) {
2775 _cur_thr = (NamedThread *)thread;
2776 _cur_thr->set_processed_thread(jthr);
2777 } else {
2778 _cur_thr = NULL;
2779 }
2780 }
2781
2782 ~RememberProcessedThread() {
2783 if (_cur_thr) {
2784 _cur_thr->set_processed_thread(NULL);
2785 }
2786 }
2787 };
2788
2789 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2790 // Verify that the deferred card marks have been flushed.
2791 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2792
2793 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2794 // since there may be more than one thread using each ThreadProfiler.
2795
2796 // Traverse the GCHandles
2797 Thread::oops_do(f, cf);
2798
2799 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2800
2801 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2802 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2803
2804 if (has_last_Java_frame()) {
2805 // Record JavaThread to GC thread
2806 RememberProcessedThread rpt(this);
2807
2808 // Traverse the privileged stack
2809 if (_privileged_stack_top != NULL) {
2810 _privileged_stack_top->oops_do(f);
2811 }
2812
2813 // traverse the registered growable array
2814 if (_array_for_gc != NULL) {
2815 for (int index = 0; index < _array_for_gc->length(); index++) {
2816 f->do_oop(_array_for_gc->adr_at(index));
2817 }
2818 }
2819
2820 // Traverse the monitor chunks
2821 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2822 chunk->oops_do(f);
2823 }
2824
2825 // Traverse the execution stack
2826 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2827 fst.current()->oops_do(f, cf, fst.register_map());
2828 }
2829 }
2830
2831 // callee_target is never live across a gc point so NULL it here should
2832 // it still contain a methdOop.
2833
2834 set_callee_target(NULL);
2835
2836 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2837 // If we have deferred set_locals there might be oops waiting to be
2838 // written
2839 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2840 if (list != NULL) {
2841 for (int i = 0; i < list->length(); i++) {
2842 list->at(i)->oops_do(f);
2843 }
2844 }
2845
2846 // Traverse instance variables at the end since the GC may be moving things
2847 // around using this function
2848 f->do_oop((oop*) &_threadObj);
2849 f->do_oop((oop*) &_vm_result);
2850 f->do_oop((oop*) &_exception_oop);
2851 f->do_oop((oop*) &_pending_async_exception);
2852
2853 if (jvmti_thread_state() != NULL) {
2854 jvmti_thread_state()->oops_do(f);
2855 }
2856 }
2857
2858 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2859 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2860 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2861
2862 if (has_last_Java_frame()) {
2863 // Traverse the execution stack
2864 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2865 fst.current()->nmethods_do(cf);
2866 }
2867 }
2868 }
2869
2870 void JavaThread::metadata_do(void f(Metadata*)) {
2871 if (has_last_Java_frame()) {
2872 // Traverse the execution stack to call f() on the methods in the stack
2873 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2874 fst.current()->metadata_do(f);
2875 }
2876 } else if (is_Compiler_thread()) {
2877 // need to walk ciMetadata in current compile tasks to keep alive.
2878 CompilerThread* ct = (CompilerThread*)this;
2879 if (ct->env() != NULL) {
2880 ct->env()->metadata_do(f);
2881 }
2882 if (ct->task() != NULL) {
2883 ct->task()->metadata_do(f);
2884 }
2885 }
2886 }
2887
2888 // Printing
2889 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2890 switch (_thread_state) {
2891 case _thread_uninitialized: return "_thread_uninitialized";
2892 case _thread_new: return "_thread_new";
2893 case _thread_new_trans: return "_thread_new_trans";
2894 case _thread_in_native: return "_thread_in_native";
2895 case _thread_in_native_trans: return "_thread_in_native_trans";
2896 case _thread_in_vm: return "_thread_in_vm";
2897 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2898 case _thread_in_Java: return "_thread_in_Java";
2899 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2900 case _thread_blocked: return "_thread_blocked";
2901 case _thread_blocked_trans: return "_thread_blocked_trans";
2902 default: return "unknown thread state";
2903 }
2904 }
2905
2906 #ifndef PRODUCT
2907 void JavaThread::print_thread_state_on(outputStream *st) const {
2908 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2909 };
2910 void JavaThread::print_thread_state() const {
2911 print_thread_state_on(tty);
2912 }
2913 #endif // PRODUCT
2914
2915 // Called by Threads::print() for VM_PrintThreads operation
2916 void JavaThread::print_on(outputStream *st) const {
2917 st->print_raw("\"");
2918 st->print_raw(get_thread_name());
2919 st->print_raw("\" ");
2920 oop thread_oop = threadObj();
2921 if (thread_oop != NULL) {
2922 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2923 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2924 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2925 }
2926 Thread::print_on(st);
2927 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2928 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2929 if (thread_oop != NULL) {
2930 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2931 }
2932 #ifndef PRODUCT
2933 print_thread_state_on(st);
2934 _safepoint_state->print_on(st);
2935 #endif // PRODUCT
2936 if (is_Compiler_thread()) {
2937 CompilerThread* ct = (CompilerThread*)this;
2938 if (ct->task() != NULL) {
2939 st->print(" Compiling: ");
2940 ct->task()->print(st, NULL, true, false);
2941 } else {
2942 st->print(" No compile task");
2943 }
2944 st->cr();
2945 }
2946 }
2947
2948 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2949 st->print("%s", get_thread_name_string(buf, buflen));
2950 }
2951
2952 // Called by fatal error handler. The difference between this and
2953 // JavaThread::print() is that we can't grab lock or allocate memory.
2954 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2955 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2956 oop thread_obj = threadObj();
2957 if (thread_obj != NULL) {
2958 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2959 }
2960 st->print(" [");
2961 st->print("%s", _get_thread_state_name(_thread_state));
2962 if (osthread()) {
2963 st->print(", id=%d", osthread()->thread_id());
2964 }
2965 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2966 p2i(stack_end()), p2i(stack_base()));
2967 st->print("]");
2968 return;
2969 }
2970
2971 // Verification
2972
2973 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2974
2975 void JavaThread::verify() {
2976 // Verify oops in the thread.
2977 oops_do(&VerifyOopClosure::verify_oop, NULL);
2978
2979 // Verify the stack frames.
2980 frames_do(frame_verify);
2981 }
2982
2983 // CR 6300358 (sub-CR 2137150)
2984 // Most callers of this method assume that it can't return NULL but a
2985 // thread may not have a name whilst it is in the process of attaching to
2986 // the VM - see CR 6412693, and there are places where a JavaThread can be
2987 // seen prior to having it's threadObj set (eg JNI attaching threads and
2988 // if vm exit occurs during initialization). These cases can all be accounted
2989 // for such that this method never returns NULL.
2990 const char* JavaThread::get_thread_name() const {
2991 #ifdef ASSERT
2992 // early safepoints can hit while current thread does not yet have TLS
2993 if (!SafepointSynchronize::is_at_safepoint()) {
2994 Thread *cur = Thread::current();
2995 if (!(cur->is_Java_thread() && cur == this)) {
2996 // Current JavaThreads are allowed to get their own name without
2997 // the Threads_lock.
2998 assert_locked_or_safepoint(Threads_lock);
2999 }
3000 }
3001 #endif // ASSERT
3002 return get_thread_name_string();
3003 }
3004
3005 // Returns a non-NULL representation of this thread's name, or a suitable
3006 // descriptive string if there is no set name
3007 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3008 const char* name_str;
3009 oop thread_obj = threadObj();
3010 if (thread_obj != NULL) {
3011 oop name = java_lang_Thread::name(thread_obj);
3012 if (name != NULL) {
3013 if (buf == NULL) {
3014 name_str = java_lang_String::as_utf8_string(name);
3015 } else {
3016 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3017 }
3018 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3019 name_str = "<no-name - thread is attaching>";
3020 } else {
3021 name_str = Thread::name();
3022 }
3023 } else {
3024 name_str = Thread::name();
3025 }
3026 assert(name_str != NULL, "unexpected NULL thread name");
3027 return name_str;
3028 }
3029
3030
3031 const char* JavaThread::get_threadgroup_name() const {
3032 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3033 oop thread_obj = threadObj();
3034 if (thread_obj != NULL) {
3035 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3036 if (thread_group != NULL) {
3037 // ThreadGroup.name can be null
3038 return java_lang_ThreadGroup::name(thread_group);
3039 }
3040 }
3041 return NULL;
3042 }
3043
3044 const char* JavaThread::get_parent_name() const {
3045 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3046 oop thread_obj = threadObj();
3047 if (thread_obj != NULL) {
3048 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3049 if (thread_group != NULL) {
3050 oop parent = java_lang_ThreadGroup::parent(thread_group);
3051 if (parent != NULL) {
3052 // ThreadGroup.name can be null
3053 return java_lang_ThreadGroup::name(parent);
3054 }
3055 }
3056 }
3057 return NULL;
3058 }
3059
3060 ThreadPriority JavaThread::java_priority() const {
3061 oop thr_oop = threadObj();
3062 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3063 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3064 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3065 return priority;
3066 }
3067
3068 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3069
3070 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3071 // Link Java Thread object <-> C++ Thread
3072
3073 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3074 // and put it into a new Handle. The Handle "thread_oop" can then
3075 // be used to pass the C++ thread object to other methods.
3076
3077 // Set the Java level thread object (jthread) field of the
3078 // new thread (a JavaThread *) to C++ thread object using the
3079 // "thread_oop" handle.
3080
3081 // Set the thread field (a JavaThread *) of the
3082 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3083
3084 Handle thread_oop(Thread::current(),
3085 JNIHandles::resolve_non_null(jni_thread));
3086 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3087 "must be initialized");
3088 set_threadObj(thread_oop());
3089 java_lang_Thread::set_thread(thread_oop(), this);
3090
3091 if (prio == NoPriority) {
3092 prio = java_lang_Thread::priority(thread_oop());
3093 assert(prio != NoPriority, "A valid priority should be present");
3094 }
3095
3096 // Push the Java priority down to the native thread; needs Threads_lock
3097 Thread::set_priority(this, prio);
3098
3099 prepare_ext();
3100
3101 // Add the new thread to the Threads list and set it in motion.
3102 // We must have threads lock in order to call Threads::add.
3103 // It is crucial that we do not block before the thread is
3104 // added to the Threads list for if a GC happens, then the java_thread oop
3105 // will not be visited by GC.
3106 Threads::add(this);
3107 }
3108
3109 oop JavaThread::current_park_blocker() {
3110 // Support for JSR-166 locks
3111 oop thread_oop = threadObj();
3112 if (thread_oop != NULL &&
3113 JDK_Version::current().supports_thread_park_blocker()) {
3114 return java_lang_Thread::park_blocker(thread_oop);
3115 }
3116 return NULL;
3117 }
3118
3119
3120 void JavaThread::print_stack_on(outputStream* st) {
3121 if (!has_last_Java_frame()) return;
3122 ResourceMark rm;
3123 HandleMark hm;
3124
3125 RegisterMap reg_map(this);
3126 vframe* start_vf = last_java_vframe(®_map);
3127 int count = 0;
3128 for (vframe* f = start_vf; f; f = f->sender()) {
3129 if (f->is_java_frame()) {
3130 javaVFrame* jvf = javaVFrame::cast(f);
3131 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3132
3133 // Print out lock information
3134 if (JavaMonitorsInStackTrace) {
3135 jvf->print_lock_info_on(st, count);
3136 }
3137 } else {
3138 // Ignore non-Java frames
3139 }
3140
3141 // Bail-out case for too deep stacks
3142 count++;
3143 if (MaxJavaStackTraceDepth == count) return;
3144 }
3145 }
3146
3147
3148 // JVMTI PopFrame support
3149 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3150 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3151 if (in_bytes(size_in_bytes) != 0) {
3152 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3153 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3154 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3155 }
3156 }
3157
3158 void* JavaThread::popframe_preserved_args() {
3159 return _popframe_preserved_args;
3160 }
3161
3162 ByteSize JavaThread::popframe_preserved_args_size() {
3163 return in_ByteSize(_popframe_preserved_args_size);
3164 }
3165
3166 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3167 int sz = in_bytes(popframe_preserved_args_size());
3168 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3169 return in_WordSize(sz / wordSize);
3170 }
3171
3172 void JavaThread::popframe_free_preserved_args() {
3173 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3174 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3175 _popframe_preserved_args = NULL;
3176 _popframe_preserved_args_size = 0;
3177 }
3178
3179 #ifndef PRODUCT
3180
3181 void JavaThread::trace_frames() {
3182 tty->print_cr("[Describe stack]");
3183 int frame_no = 1;
3184 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3185 tty->print(" %d. ", frame_no++);
3186 fst.current()->print_value_on(tty, this);
3187 tty->cr();
3188 }
3189 }
3190
3191 class PrintAndVerifyOopClosure: public OopClosure {
3192 protected:
3193 template <class T> inline void do_oop_work(T* p) {
3194 oop obj = oopDesc::load_decode_heap_oop(p);
3195 if (obj == NULL) return;
3196 tty->print(INTPTR_FORMAT ": ", p2i(p));
3197 if (obj->is_oop_or_null()) {
3198 if (obj->is_objArray()) {
3199 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3200 } else {
3201 obj->print();
3202 }
3203 } else {
3204 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3205 }
3206 tty->cr();
3207 }
3208 public:
3209 virtual void do_oop(oop* p) { do_oop_work(p); }
3210 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3211 };
3212
3213
3214 static void oops_print(frame* f, const RegisterMap *map) {
3215 PrintAndVerifyOopClosure print;
3216 f->print_value();
3217 f->oops_do(&print, NULL, (RegisterMap*)map);
3218 }
3219
3220 // Print our all the locations that contain oops and whether they are
3221 // valid or not. This useful when trying to find the oldest frame
3222 // where an oop has gone bad since the frame walk is from youngest to
3223 // oldest.
3224 void JavaThread::trace_oops() {
3225 tty->print_cr("[Trace oops]");
3226 frames_do(oops_print);
3227 }
3228
3229
3230 #ifdef ASSERT
3231 // Print or validate the layout of stack frames
3232 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3233 ResourceMark rm;
3234 PRESERVE_EXCEPTION_MARK;
3235 FrameValues values;
3236 int frame_no = 0;
3237 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3238 fst.current()->describe(values, ++frame_no);
3239 if (depth == frame_no) break;
3240 }
3241 if (validate_only) {
3242 values.validate();
3243 } else {
3244 tty->print_cr("[Describe stack layout]");
3245 values.print(this);
3246 }
3247 }
3248 #endif
3249
3250 void JavaThread::trace_stack_from(vframe* start_vf) {
3251 ResourceMark rm;
3252 int vframe_no = 1;
3253 for (vframe* f = start_vf; f; f = f->sender()) {
3254 if (f->is_java_frame()) {
3255 javaVFrame::cast(f)->print_activation(vframe_no++);
3256 } else {
3257 f->print();
3258 }
3259 if (vframe_no > StackPrintLimit) {
3260 tty->print_cr("...<more frames>...");
3261 return;
3262 }
3263 }
3264 }
3265
3266
3267 void JavaThread::trace_stack() {
3268 if (!has_last_Java_frame()) return;
3269 ResourceMark rm;
3270 HandleMark hm;
3271 RegisterMap reg_map(this);
3272 trace_stack_from(last_java_vframe(®_map));
3273 }
3274
3275
3276 #endif // PRODUCT
3277
3278
3279 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3280 assert(reg_map != NULL, "a map must be given");
3281 frame f = last_frame();
3282 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3283 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3284 }
3285 return NULL;
3286 }
3287
3288
3289 Klass* JavaThread::security_get_caller_class(int depth) {
3290 vframeStream vfst(this);
3291 vfst.security_get_caller_frame(depth);
3292 if (!vfst.at_end()) {
3293 return vfst.method()->method_holder();
3294 }
3295 return NULL;
3296 }
3297
3298 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3299 assert(thread->is_Compiler_thread(), "must be compiler thread");
3300 CompileBroker::compiler_thread_loop();
3301 }
3302
3303 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3304 NMethodSweeper::sweeper_loop();
3305 }
3306
3307 // Create a CompilerThread
3308 CompilerThread::CompilerThread(CompileQueue* queue,
3309 CompilerCounters* counters)
3310 : JavaThread(&compiler_thread_entry) {
3311 _env = NULL;
3312 _log = NULL;
3313 _task = NULL;
3314 _queue = queue;
3315 _counters = counters;
3316 _buffer_blob = NULL;
3317 _compiler = NULL;
3318
3319 #ifndef PRODUCT
3320 _ideal_graph_printer = NULL;
3321 #endif
3322 }
3323
3324 bool CompilerThread::can_call_java() const {
3325 return _compiler != NULL && _compiler->is_jvmci();
3326 }
3327
3328 // Create sweeper thread
3329 CodeCacheSweeperThread::CodeCacheSweeperThread()
3330 : JavaThread(&sweeper_thread_entry) {
3331 _scanned_compiled_method = NULL;
3332 }
3333
3334 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3335 JavaThread::oops_do(f, cf);
3336 if (_scanned_compiled_method != NULL && cf != NULL) {
3337 // Safepoints can occur when the sweeper is scanning an nmethod so
3338 // process it here to make sure it isn't unloaded in the middle of
3339 // a scan.
3340 cf->do_code_blob(_scanned_compiled_method);
3341 }
3342 }
3343
3344 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3345 JavaThread::nmethods_do(cf);
3346 if (_scanned_compiled_method != NULL && cf != NULL) {
3347 // Safepoints can occur when the sweeper is scanning an nmethod so
3348 // process it here to make sure it isn't unloaded in the middle of
3349 // a scan.
3350 cf->do_code_blob(_scanned_compiled_method);
3351 }
3352 }
3353
3354
3355 // ======= Threads ========
3356
3357 // The Threads class links together all active threads, and provides
3358 // operations over all threads. It is protected by its own Mutex
3359 // lock, which is also used in other contexts to protect thread
3360 // operations from having the thread being operated on from exiting
3361 // and going away unexpectedly (e.g., safepoint synchronization)
3362
3363 JavaThread* Threads::_thread_list = NULL;
3364 int Threads::_number_of_threads = 0;
3365 int Threads::_number_of_non_daemon_threads = 0;
3366 int Threads::_return_code = 0;
3367 int Threads::_thread_claim_parity = 0;
3368 size_t JavaThread::_stack_size_at_create = 0;
3369 #ifdef ASSERT
3370 bool Threads::_vm_complete = false;
3371 #endif
3372
3373 // All JavaThreads
3374 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3375
3376 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3377 void Threads::threads_do(ThreadClosure* tc) {
3378 assert_locked_or_safepoint(Threads_lock);
3379 // ALL_JAVA_THREADS iterates through all JavaThreads
3380 ALL_JAVA_THREADS(p) {
3381 tc->do_thread(p);
3382 }
3383 // Someday we could have a table or list of all non-JavaThreads.
3384 // For now, just manually iterate through them.
3385 tc->do_thread(VMThread::vm_thread());
3386 Universe::heap()->gc_threads_do(tc);
3387 WatcherThread *wt = WatcherThread::watcher_thread();
3388 // Strictly speaking, the following NULL check isn't sufficient to make sure
3389 // the data for WatcherThread is still valid upon being examined. However,
3390 // considering that WatchThread terminates when the VM is on the way to
3391 // exit at safepoint, the chance of the above is extremely small. The right
3392 // way to prevent termination of WatcherThread would be to acquire
3393 // Terminator_lock, but we can't do that without violating the lock rank
3394 // checking in some cases.
3395 if (wt != NULL) {
3396 tc->do_thread(wt);
3397 }
3398
3399 // If CompilerThreads ever become non-JavaThreads, add them here
3400 }
3401
3402 // The system initialization in the library has three phases.
3403 //
3404 // Phase 1: java.lang.System class initialization
3405 // java.lang.System is a primordial class loaded and initialized
3406 // by the VM early during startup. java.lang.System.<clinit>
3407 // only does registerNatives and keeps the rest of the class
3408 // initialization work later until thread initialization completes.
3409 //
3410 // System.initPhase1 initializes the system properties, the static
3411 // fields in, out, and err. Set up java signal handlers, OS-specific
3412 // system settings, and thread group of the main thread.
3413 static void call_initPhase1(TRAPS) {
3414 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3415 instanceKlassHandle klass (THREAD, k);
3416
3417 JavaValue result(T_VOID);
3418 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3419 vmSymbols::void_method_signature(), CHECK);
3420 }
3421
3422 // Phase 2. Module system initialization
3423 // This will initialize the module system. Only java.base classes
3424 // can be loaded until phase 2 completes.
3425 //
3426 // Call System.initPhase2 after the compiler initialization and jsr292
3427 // classes get initialized because module initialization runs a lot of java
3428 // code, that for performance reasons, should be compiled. Also, this will
3429 // enable the startup code to use lambda and other language features in this
3430 // phase and onward.
3431 //
3432 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3433 static void call_initPhase2(TRAPS) {
3434 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime));
3435
3436 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3437 instanceKlassHandle klass (THREAD, k);
3438
3439 JavaValue result(T_VOID);
3440 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3441 vmSymbols::void_method_signature(), CHECK);
3442 universe_post_module_init();
3443 }
3444
3445 // Phase 3. final setup - set security manager, system class loader and TCCL
3446 //
3447 // This will instantiate and set the security manager, set the system class
3448 // loader as well as the thread context class loader. The security manager
3449 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3450 // other modules or the application's classpath.
3451 static void call_initPhase3(TRAPS) {
3452 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3453 instanceKlassHandle klass (THREAD, k);
3454
3455 JavaValue result(T_VOID);
3456 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3457 vmSymbols::void_method_signature(), CHECK);
3458 }
3459
3460 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3461 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3462
3463 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3464 create_vm_init_libraries();
3465 }
3466
3467 initialize_class(vmSymbols::java_lang_String(), CHECK);
3468
3469 // Inject CompactStrings value after the static initializers for String ran.
3470 java_lang_String::set_compact_strings(CompactStrings);
3471
3472 // Initialize java_lang.System (needed before creating the thread)
3473 initialize_class(vmSymbols::java_lang_System(), CHECK);
3474 // The VM creates & returns objects of this class. Make sure it's initialized.
3475 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3476 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3477 Handle thread_group = create_initial_thread_group(CHECK);
3478 Universe::set_main_thread_group(thread_group());
3479 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3480 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3481 main_thread->set_threadObj(thread_object);
3482 // Set thread status to running since main thread has
3483 // been started and running.
3484 java_lang_Thread::set_thread_status(thread_object,
3485 java_lang_Thread::RUNNABLE);
3486
3487 // The VM creates objects of this class.
3488 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3489
3490 // The VM preresolves methods to these classes. Make sure that they get initialized
3491 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3492 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3493
3494 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3495 call_initPhase1(CHECK);
3496
3497 // get the Java runtime name after java.lang.System is initialized
3498 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3499 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3500
3501 // an instance of OutOfMemory exception has been allocated earlier
3502 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3503 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3504 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3505 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3506 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3507 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3508 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3509 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3510 }
3511
3512 void Threads::initialize_jsr292_core_classes(TRAPS) {
3513 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3514
3515 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3516 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3517 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3518 }
3519
3520 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3521 extern void JDK_Version_init();
3522
3523 // Preinitialize version info.
3524 VM_Version::early_initialize();
3525
3526 // Check version
3527 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3528
3529 // Initialize library-based TLS
3530 ThreadLocalStorage::init();
3531
3532 // Initialize the output stream module
3533 ostream_init();
3534
3535 // Process java launcher properties.
3536 Arguments::process_sun_java_launcher_properties(args);
3537
3538 // Initialize the os module
3539 os::init();
3540
3541 // Record VM creation timing statistics
3542 TraceVmCreationTime create_vm_timer;
3543 create_vm_timer.start();
3544
3545 // Initialize system properties.
3546 Arguments::init_system_properties();
3547
3548 // So that JDK version can be used as a discriminator when parsing arguments
3549 JDK_Version_init();
3550
3551 // Update/Initialize System properties after JDK version number is known
3552 Arguments::init_version_specific_system_properties();
3553
3554 // Make sure to initialize log configuration *before* parsing arguments
3555 LogConfiguration::initialize(create_vm_timer.begin_time());
3556
3557 // Parse arguments
3558 jint parse_result = Arguments::parse(args);
3559 if (parse_result != JNI_OK) return parse_result;
3560
3561 os::init_before_ergo();
3562
3563 jint ergo_result = Arguments::apply_ergo();
3564 if (ergo_result != JNI_OK) return ergo_result;
3565
3566 // Final check of all ranges after ergonomics which may change values.
3567 if (!CommandLineFlagRangeList::check_ranges()) {
3568 return JNI_EINVAL;
3569 }
3570
3571 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3572 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3573 if (!constraint_result) {
3574 return JNI_EINVAL;
3575 }
3576
3577 CommandLineFlagWriteableList::mark_startup();
3578
3579 if (PauseAtStartup) {
3580 os::pause();
3581 }
3582
3583 HOTSPOT_VM_INIT_BEGIN();
3584
3585 // Timing (must come after argument parsing)
3586 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3587
3588 // Initialize the os module after parsing the args
3589 jint os_init_2_result = os::init_2();
3590 if (os_init_2_result != JNI_OK) return os_init_2_result;
3591
3592 jint adjust_after_os_result = Arguments::adjust_after_os();
3593 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3594
3595 // Initialize output stream logging
3596 ostream_init_log();
3597
3598 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3599 // Must be before create_vm_init_agents()
3600 if (Arguments::init_libraries_at_startup()) {
3601 convert_vm_init_libraries_to_agents();
3602 }
3603
3604 // Launch -agentlib/-agentpath and converted -Xrun agents
3605 if (Arguments::init_agents_at_startup()) {
3606 create_vm_init_agents();
3607 }
3608
3609 // Initialize Threads state
3610 _thread_list = NULL;
3611 _number_of_threads = 0;
3612 _number_of_non_daemon_threads = 0;
3613
3614 // Initialize global data structures and create system classes in heap
3615 vm_init_globals();
3616
3617 #if INCLUDE_JVMCI
3618 if (JVMCICounterSize > 0) {
3619 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3620 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3621 } else {
3622 JavaThread::_jvmci_old_thread_counters = NULL;
3623 }
3624 #endif // INCLUDE_JVMCI
3625
3626 // Attach the main thread to this os thread
3627 JavaThread* main_thread = new JavaThread();
3628 main_thread->set_thread_state(_thread_in_vm);
3629 main_thread->initialize_thread_current();
3630 // must do this before set_active_handles
3631 main_thread->record_stack_base_and_size();
3632 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3633
3634 if (!main_thread->set_as_starting_thread()) {
3635 vm_shutdown_during_initialization(
3636 "Failed necessary internal allocation. Out of swap space");
3637 delete main_thread;
3638 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3639 return JNI_ENOMEM;
3640 }
3641
3642 // Enable guard page *after* os::create_main_thread(), otherwise it would
3643 // crash Linux VM, see notes in os_linux.cpp.
3644 main_thread->create_stack_guard_pages();
3645
3646 // Initialize Java-Level synchronization subsystem
3647 ObjectMonitor::Initialize();
3648
3649 // Initialize global modules
3650 jint status = init_globals();
3651 if (status != JNI_OK) {
3652 delete main_thread;
3653 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3654 return status;
3655 }
3656
3657 if (TRACE_INITIALIZE() != JNI_OK) {
3658 vm_exit_during_initialization("Failed to initialize tracing backend");
3659 }
3660
3661 // Should be done after the heap is fully created
3662 main_thread->cache_global_variables();
3663
3664 HandleMark hm;
3665
3666 { MutexLocker mu(Threads_lock);
3667 Threads::add(main_thread);
3668 }
3669
3670 // Any JVMTI raw monitors entered in onload will transition into
3671 // real raw monitor. VM is setup enough here for raw monitor enter.
3672 JvmtiExport::transition_pending_onload_raw_monitors();
3673
3674 // Create the VMThread
3675 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3676
3677 VMThread::create();
3678 Thread* vmthread = VMThread::vm_thread();
3679
3680 if (!os::create_thread(vmthread, os::vm_thread)) {
3681 vm_exit_during_initialization("Cannot create VM thread. "
3682 "Out of system resources.");
3683 }
3684
3685 // Wait for the VM thread to become ready, and VMThread::run to initialize
3686 // Monitors can have spurious returns, must always check another state flag
3687 {
3688 MutexLocker ml(Notify_lock);
3689 os::start_thread(vmthread);
3690 while (vmthread->active_handles() == NULL) {
3691 Notify_lock->wait();
3692 }
3693 }
3694 }
3695
3696 assert(Universe::is_fully_initialized(), "not initialized");
3697 if (VerifyDuringStartup) {
3698 // Make sure we're starting with a clean slate.
3699 VM_Verify verify_op;
3700 VMThread::execute(&verify_op);
3701 }
3702
3703 Thread* THREAD = Thread::current();
3704
3705 // At this point, the Universe is initialized, but we have not executed
3706 // any byte code. Now is a good time (the only time) to dump out the
3707 // internal state of the JVM for sharing.
3708 if (DumpSharedSpaces) {
3709 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3710 ShouldNotReachHere();
3711 }
3712
3713 // Always call even when there are not JVMTI environments yet, since environments
3714 // may be attached late and JVMTI must track phases of VM execution
3715 JvmtiExport::enter_early_start_phase();
3716
3717 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3718 JvmtiExport::post_early_vm_start();
3719
3720 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3721
3722 // We need this for ClassDataSharing - the initial vm.info property is set
3723 // with the default value of CDS "sharing" which may be reset through
3724 // command line options.
3725 reset_vm_info_property(CHECK_JNI_ERR);
3726
3727 quicken_jni_functions();
3728
3729 // No more stub generation allowed after that point.
3730 StubCodeDesc::freeze();
3731
3732 // Set flag that basic initialization has completed. Used by exceptions and various
3733 // debug stuff, that does not work until all basic classes have been initialized.
3734 set_init_completed();
3735
3736 LogConfiguration::post_initialize();
3737 Metaspace::post_initialize();
3738
3739 HOTSPOT_VM_INIT_END();
3740
3741 // record VM initialization completion time
3742 #if INCLUDE_MANAGEMENT
3743 Management::record_vm_init_completed();
3744 #endif // INCLUDE_MANAGEMENT
3745
3746 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3747 // set_init_completed has just been called, causing exceptions not to be shortcut
3748 // anymore. We call vm_exit_during_initialization directly instead.
3749
3750 // Initialize reference pending list locker
3751 bool needs_locker_thread = Universe::heap()->needs_reference_pending_list_locker_thread();
3752 ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR);
3753
3754 // Signal Dispatcher needs to be started before VMInit event is posted
3755 os::signal_init();
3756
3757 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3758 if (!DisableAttachMechanism) {
3759 AttachListener::vm_start();
3760 if (StartAttachListener || AttachListener::init_at_startup()) {
3761 AttachListener::init();
3762 }
3763 }
3764
3765 // Launch -Xrun agents
3766 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3767 // back-end can launch with -Xdebug -Xrunjdwp.
3768 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3769 create_vm_init_libraries();
3770 }
3771
3772 if (CleanChunkPoolAsync) {
3773 Chunk::start_chunk_pool_cleaner_task();
3774 }
3775
3776 // initialize compiler(s)
3777 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3778 CompileBroker::compilation_init(CHECK_JNI_ERR);
3779 #endif
3780
3781 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3782 // It is done after compilers are initialized, because otherwise compilations of
3783 // signature polymorphic MH intrinsics can be missed
3784 // (see SystemDictionary::find_method_handle_intrinsic).
3785 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3786
3787 // This will initialize the module system. Only java.base classes can be
3788 // loaded until phase 2 completes
3789 call_initPhase2(CHECK_JNI_ERR);
3790
3791 // Always call even when there are not JVMTI environments yet, since environments
3792 // may be attached late and JVMTI must track phases of VM execution
3793 JvmtiExport::enter_start_phase();
3794
3795 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3796 JvmtiExport::post_vm_start();
3797
3798 // Final system initialization including security manager and system class loader
3799 call_initPhase3(CHECK_JNI_ERR);
3800
3801 // cache the system class loader
3802 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3803
3804 #if INCLUDE_JVMCI
3805 if (EnableJVMCI && UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation)) {
3806 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3807 // compilations via JVMCI will not actually block until JVMCI is initialized.
3808 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3809 }
3810 #endif
3811
3812 // Always call even when there are not JVMTI environments yet, since environments
3813 // may be attached late and JVMTI must track phases of VM execution
3814 JvmtiExport::enter_live_phase();
3815
3816 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3817 JvmtiExport::post_vm_initialized();
3818
3819 if (TRACE_START() != JNI_OK) {
3820 vm_exit_during_initialization("Failed to start tracing backend.");
3821 }
3822
3823 #if INCLUDE_MANAGEMENT
3824 Management::initialize(THREAD);
3825
3826 if (HAS_PENDING_EXCEPTION) {
3827 // management agent fails to start possibly due to
3828 // configuration problem and is responsible for printing
3829 // stack trace if appropriate. Simply exit VM.
3830 vm_exit(1);
3831 }
3832 #endif // INCLUDE_MANAGEMENT
3833
3834 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3835 if (MemProfiling) MemProfiler::engage();
3836 StatSampler::engage();
3837 if (CheckJNICalls) JniPeriodicChecker::engage();
3838
3839 BiasedLocking::init();
3840
3841 #if INCLUDE_RTM_OPT
3842 RTMLockingCounters::init();
3843 #endif
3844
3845 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3846 call_postVMInitHook(THREAD);
3847 // The Java side of PostVMInitHook.run must deal with all
3848 // exceptions and provide means of diagnosis.
3849 if (HAS_PENDING_EXCEPTION) {
3850 CLEAR_PENDING_EXCEPTION;
3851 }
3852 }
3853
3854 {
3855 MutexLocker ml(PeriodicTask_lock);
3856 // Make sure the WatcherThread can be started by WatcherThread::start()
3857 // or by dynamic enrollment.
3858 WatcherThread::make_startable();
3859 // Start up the WatcherThread if there are any periodic tasks
3860 // NOTE: All PeriodicTasks should be registered by now. If they
3861 // aren't, late joiners might appear to start slowly (we might
3862 // take a while to process their first tick).
3863 if (PeriodicTask::num_tasks() > 0) {
3864 WatcherThread::start();
3865 }
3866 }
3867
3868 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3869
3870 create_vm_timer.end();
3871 #ifdef ASSERT
3872 _vm_complete = true;
3873 #endif
3874 return JNI_OK;
3875 }
3876
3877 // type for the Agent_OnLoad and JVM_OnLoad entry points
3878 extern "C" {
3879 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3880 }
3881 // Find a command line agent library and return its entry point for
3882 // -agentlib: -agentpath: -Xrun
3883 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3884 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3885 const char *on_load_symbols[],
3886 size_t num_symbol_entries) {
3887 OnLoadEntry_t on_load_entry = NULL;
3888 void *library = NULL;
3889
3890 if (!agent->valid()) {
3891 char buffer[JVM_MAXPATHLEN];
3892 char ebuf[1024] = "";
3893 const char *name = agent->name();
3894 const char *msg = "Could not find agent library ";
3895
3896 // First check to see if agent is statically linked into executable
3897 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3898 library = agent->os_lib();
3899 } else if (agent->is_absolute_path()) {
3900 library = os::dll_load(name, ebuf, sizeof ebuf);
3901 if (library == NULL) {
3902 const char *sub_msg = " in absolute path, with error: ";
3903 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3904 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3905 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3906 // If we can't find the agent, exit.
3907 vm_exit_during_initialization(buf, NULL);
3908 FREE_C_HEAP_ARRAY(char, buf);
3909 }
3910 } else {
3911 // Try to load the agent from the standard dll directory
3912 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3913 name)) {
3914 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3915 }
3916 if (library == NULL) { // Try the local directory
3917 char ns[1] = {0};
3918 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3919 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3920 }
3921 if (library == NULL) {
3922 const char *sub_msg = " on the library path, with error: ";
3923 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3924 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3925 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3926 // If we can't find the agent, exit.
3927 vm_exit_during_initialization(buf, NULL);
3928 FREE_C_HEAP_ARRAY(char, buf);
3929 }
3930 }
3931 }
3932 agent->set_os_lib(library);
3933 agent->set_valid();
3934 }
3935
3936 // Find the OnLoad function.
3937 on_load_entry =
3938 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3939 false,
3940 on_load_symbols,
3941 num_symbol_entries));
3942 return on_load_entry;
3943 }
3944
3945 // Find the JVM_OnLoad entry point
3946 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3947 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3948 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3949 }
3950
3951 // Find the Agent_OnLoad entry point
3952 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3953 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3954 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3955 }
3956
3957 // For backwards compatibility with -Xrun
3958 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3959 // treated like -agentpath:
3960 // Must be called before agent libraries are created
3961 void Threads::convert_vm_init_libraries_to_agents() {
3962 AgentLibrary* agent;
3963 AgentLibrary* next;
3964
3965 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3966 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3967 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3968
3969 // If there is an JVM_OnLoad function it will get called later,
3970 // otherwise see if there is an Agent_OnLoad
3971 if (on_load_entry == NULL) {
3972 on_load_entry = lookup_agent_on_load(agent);
3973 if (on_load_entry != NULL) {
3974 // switch it to the agent list -- so that Agent_OnLoad will be called,
3975 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3976 Arguments::convert_library_to_agent(agent);
3977 } else {
3978 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3979 }
3980 }
3981 }
3982 }
3983
3984 // Create agents for -agentlib: -agentpath: and converted -Xrun
3985 // Invokes Agent_OnLoad
3986 // Called very early -- before JavaThreads exist
3987 void Threads::create_vm_init_agents() {
3988 extern struct JavaVM_ main_vm;
3989 AgentLibrary* agent;
3990
3991 JvmtiExport::enter_onload_phase();
3992
3993 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3994 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3995
3996 if (on_load_entry != NULL) {
3997 // Invoke the Agent_OnLoad function
3998 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3999 if (err != JNI_OK) {
4000 vm_exit_during_initialization("agent library failed to init", agent->name());
4001 }
4002 } else {
4003 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4004 }
4005 }
4006 JvmtiExport::enter_primordial_phase();
4007 }
4008
4009 extern "C" {
4010 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4011 }
4012
4013 void Threads::shutdown_vm_agents() {
4014 // Send any Agent_OnUnload notifications
4015 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4016 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4017 extern struct JavaVM_ main_vm;
4018 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4019
4020 // Find the Agent_OnUnload function.
4021 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4022 os::find_agent_function(agent,
4023 false,
4024 on_unload_symbols,
4025 num_symbol_entries));
4026
4027 // Invoke the Agent_OnUnload function
4028 if (unload_entry != NULL) {
4029 JavaThread* thread = JavaThread::current();
4030 ThreadToNativeFromVM ttn(thread);
4031 HandleMark hm(thread);
4032 (*unload_entry)(&main_vm);
4033 }
4034 }
4035 }
4036
4037 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4038 // Invokes JVM_OnLoad
4039 void Threads::create_vm_init_libraries() {
4040 extern struct JavaVM_ main_vm;
4041 AgentLibrary* agent;
4042
4043 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4044 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4045
4046 if (on_load_entry != NULL) {
4047 // Invoke the JVM_OnLoad function
4048 JavaThread* thread = JavaThread::current();
4049 ThreadToNativeFromVM ttn(thread);
4050 HandleMark hm(thread);
4051 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4052 if (err != JNI_OK) {
4053 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4054 }
4055 } else {
4056 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4057 }
4058 }
4059 }
4060
4061 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4062 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4063
4064 JavaThread* java_thread = NULL;
4065 // Sequential search for now. Need to do better optimization later.
4066 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4067 oop tobj = thread->threadObj();
4068 if (!thread->is_exiting() &&
4069 tobj != NULL &&
4070 java_tid == java_lang_Thread::thread_id(tobj)) {
4071 java_thread = thread;
4072 break;
4073 }
4074 }
4075 return java_thread;
4076 }
4077
4078
4079 // Last thread running calls java.lang.Shutdown.shutdown()
4080 void JavaThread::invoke_shutdown_hooks() {
4081 HandleMark hm(this);
4082
4083 // We could get here with a pending exception, if so clear it now.
4084 if (this->has_pending_exception()) {
4085 this->clear_pending_exception();
4086 }
4087
4088 EXCEPTION_MARK;
4089 Klass* k =
4090 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4091 THREAD);
4092 if (k != NULL) {
4093 // SystemDictionary::resolve_or_null will return null if there was
4094 // an exception. If we cannot load the Shutdown class, just don't
4095 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4096 // and finalizers (if runFinalizersOnExit is set) won't be run.
4097 // Note that if a shutdown hook was registered or runFinalizersOnExit
4098 // was called, the Shutdown class would have already been loaded
4099 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4100 instanceKlassHandle shutdown_klass (THREAD, k);
4101 JavaValue result(T_VOID);
4102 JavaCalls::call_static(&result,
4103 shutdown_klass,
4104 vmSymbols::shutdown_method_name(),
4105 vmSymbols::void_method_signature(),
4106 THREAD);
4107 }
4108 CLEAR_PENDING_EXCEPTION;
4109 }
4110
4111 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4112 // the program falls off the end of main(). Another VM exit path is through
4113 // vm_exit() when the program calls System.exit() to return a value or when
4114 // there is a serious error in VM. The two shutdown paths are not exactly
4115 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4116 // and VM_Exit op at VM level.
4117 //
4118 // Shutdown sequence:
4119 // + Shutdown native memory tracking if it is on
4120 // + Wait until we are the last non-daemon thread to execute
4121 // <-- every thing is still working at this moment -->
4122 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4123 // shutdown hooks, run finalizers if finalization-on-exit
4124 // + Call before_exit(), prepare for VM exit
4125 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4126 // currently the only user of this mechanism is File.deleteOnExit())
4127 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4128 // post thread end and vm death events to JVMTI,
4129 // stop signal thread
4130 // + Call JavaThread::exit(), it will:
4131 // > release JNI handle blocks, remove stack guard pages
4132 // > remove this thread from Threads list
4133 // <-- no more Java code from this thread after this point -->
4134 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4135 // the compiler threads at safepoint
4136 // <-- do not use anything that could get blocked by Safepoint -->
4137 // + Disable tracing at JNI/JVM barriers
4138 // + Set _vm_exited flag for threads that are still running native code
4139 // + Delete this thread
4140 // + Call exit_globals()
4141 // > deletes tty
4142 // > deletes PerfMemory resources
4143 // + Return to caller
4144
4145 bool Threads::destroy_vm() {
4146 JavaThread* thread = JavaThread::current();
4147
4148 #ifdef ASSERT
4149 _vm_complete = false;
4150 #endif
4151 // Wait until we are the last non-daemon thread to execute
4152 { MutexLocker nu(Threads_lock);
4153 while (Threads::number_of_non_daemon_threads() > 1)
4154 // This wait should make safepoint checks, wait without a timeout,
4155 // and wait as a suspend-equivalent condition.
4156 //
4157 // Note: If the FlatProfiler is running and this thread is waiting
4158 // for another non-daemon thread to finish, then the FlatProfiler
4159 // is waiting for the external suspend request on this thread to
4160 // complete. wait_for_ext_suspend_completion() will eventually
4161 // timeout, but that takes time. Making this wait a suspend-
4162 // equivalent condition solves that timeout problem.
4163 //
4164 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4165 Mutex::_as_suspend_equivalent_flag);
4166 }
4167
4168 // Hang forever on exit if we are reporting an error.
4169 if (ShowMessageBoxOnError && is_error_reported()) {
4170 os::infinite_sleep();
4171 }
4172 os::wait_for_keypress_at_exit();
4173
4174 // run Java level shutdown hooks
4175 thread->invoke_shutdown_hooks();
4176
4177 before_exit(thread);
4178
4179 thread->exit(true);
4180
4181 // Stop VM thread.
4182 {
4183 // 4945125 The vm thread comes to a safepoint during exit.
4184 // GC vm_operations can get caught at the safepoint, and the
4185 // heap is unparseable if they are caught. Grab the Heap_lock
4186 // to prevent this. The GC vm_operations will not be able to
4187 // queue until after the vm thread is dead. After this point,
4188 // we'll never emerge out of the safepoint before the VM exits.
4189
4190 MutexLocker ml(Heap_lock);
4191
4192 VMThread::wait_for_vm_thread_exit();
4193 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4194 VMThread::destroy();
4195 }
4196
4197 // clean up ideal graph printers
4198 #if defined(COMPILER2) && !defined(PRODUCT)
4199 IdealGraphPrinter::clean_up();
4200 #endif
4201
4202 // Now, all Java threads are gone except daemon threads. Daemon threads
4203 // running Java code or in VM are stopped by the Safepoint. However,
4204 // daemon threads executing native code are still running. But they
4205 // will be stopped at native=>Java/VM barriers. Note that we can't
4206 // simply kill or suspend them, as it is inherently deadlock-prone.
4207
4208 VM_Exit::set_vm_exited();
4209
4210 notify_vm_shutdown();
4211
4212 delete thread;
4213
4214 #if INCLUDE_JVMCI
4215 if (JVMCICounterSize > 0) {
4216 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4217 }
4218 #endif
4219
4220 // exit_globals() will delete tty
4221 exit_globals();
4222
4223 LogConfiguration::finalize();
4224
4225 return true;
4226 }
4227
4228
4229 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4230 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4231 return is_supported_jni_version(version);
4232 }
4233
4234
4235 jboolean Threads::is_supported_jni_version(jint version) {
4236 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4237 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4238 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4239 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4240 if (version == JNI_VERSION_9) return JNI_TRUE;
4241 return JNI_FALSE;
4242 }
4243
4244
4245 void Threads::add(JavaThread* p, bool force_daemon) {
4246 // The threads lock must be owned at this point
4247 assert_locked_or_safepoint(Threads_lock);
4248
4249 // See the comment for this method in thread.hpp for its purpose and
4250 // why it is called here.
4251 p->initialize_queues();
4252 p->set_next(_thread_list);
4253 _thread_list = p;
4254 _number_of_threads++;
4255 oop threadObj = p->threadObj();
4256 bool daemon = true;
4257 // Bootstrapping problem: threadObj can be null for initial
4258 // JavaThread (or for threads attached via JNI)
4259 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4260 _number_of_non_daemon_threads++;
4261 daemon = false;
4262 }
4263
4264 ThreadService::add_thread(p, daemon);
4265
4266 // Possible GC point.
4267 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4268 }
4269
4270 void Threads::remove(JavaThread* p) {
4271 // Extra scope needed for Thread_lock, so we can check
4272 // that we do not remove thread without safepoint code notice
4273 { MutexLocker ml(Threads_lock);
4274
4275 assert(includes(p), "p must be present");
4276
4277 JavaThread* current = _thread_list;
4278 JavaThread* prev = NULL;
4279
4280 while (current != p) {
4281 prev = current;
4282 current = current->next();
4283 }
4284
4285 if (prev) {
4286 prev->set_next(current->next());
4287 } else {
4288 _thread_list = p->next();
4289 }
4290 _number_of_threads--;
4291 oop threadObj = p->threadObj();
4292 bool daemon = true;
4293 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4294 _number_of_non_daemon_threads--;
4295 daemon = false;
4296
4297 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4298 // on destroy_vm will wake up.
4299 if (number_of_non_daemon_threads() == 1) {
4300 Threads_lock->notify_all();
4301 }
4302 }
4303 ThreadService::remove_thread(p, daemon);
4304
4305 // Make sure that safepoint code disregard this thread. This is needed since
4306 // the thread might mess around with locks after this point. This can cause it
4307 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4308 // of this thread since it is removed from the queue.
4309 p->set_terminated_value();
4310 } // unlock Threads_lock
4311
4312 // Since Events::log uses a lock, we grab it outside the Threads_lock
4313 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4314 }
4315
4316 // Threads_lock must be held when this is called (or must be called during a safepoint)
4317 bool Threads::includes(JavaThread* p) {
4318 assert(Threads_lock->is_locked(), "sanity check");
4319 ALL_JAVA_THREADS(q) {
4320 if (q == p) {
4321 return true;
4322 }
4323 }
4324 return false;
4325 }
4326
4327 // Operations on the Threads list for GC. These are not explicitly locked,
4328 // but the garbage collector must provide a safe context for them to run.
4329 // In particular, these things should never be called when the Threads_lock
4330 // is held by some other thread. (Note: the Safepoint abstraction also
4331 // uses the Threads_lock to guarantee this property. It also makes sure that
4332 // all threads gets blocked when exiting or starting).
4333
4334 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4335 ALL_JAVA_THREADS(p) {
4336 p->oops_do(f, cf);
4337 }
4338 VMThread::vm_thread()->oops_do(f, cf);
4339 }
4340
4341 void Threads::change_thread_claim_parity() {
4342 // Set the new claim parity.
4343 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4344 "Not in range.");
4345 _thread_claim_parity++;
4346 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4347 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4348 "Not in range.");
4349 }
4350
4351 #ifdef ASSERT
4352 void Threads::assert_all_threads_claimed() {
4353 ALL_JAVA_THREADS(p) {
4354 const int thread_parity = p->oops_do_parity();
4355 assert((thread_parity == _thread_claim_parity),
4356 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4357 }
4358 }
4359 #endif // ASSERT
4360
4361 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4362 int cp = Threads::thread_claim_parity();
4363 ALL_JAVA_THREADS(p) {
4364 if (p->claim_oops_do(is_par, cp)) {
4365 p->oops_do(f, cf);
4366 }
4367 }
4368 VMThread* vmt = VMThread::vm_thread();
4369 if (vmt->claim_oops_do(is_par, cp)) {
4370 vmt->oops_do(f, cf);
4371 }
4372 }
4373
4374 #if INCLUDE_ALL_GCS
4375 // Used by ParallelScavenge
4376 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4377 ALL_JAVA_THREADS(p) {
4378 q->enqueue(new ThreadRootsTask(p));
4379 }
4380 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4381 }
4382
4383 // Used by Parallel Old
4384 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4385 ALL_JAVA_THREADS(p) {
4386 q->enqueue(new ThreadRootsMarkingTask(p));
4387 }
4388 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4389 }
4390 #endif // INCLUDE_ALL_GCS
4391
4392 void Threads::nmethods_do(CodeBlobClosure* cf) {
4393 ALL_JAVA_THREADS(p) {
4394 // This is used by the code cache sweeper to mark nmethods that are active
4395 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4396 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4397 if(!p->is_Code_cache_sweeper_thread()) {
4398 p->nmethods_do(cf);
4399 }
4400 }
4401 }
4402
4403 void Threads::metadata_do(void f(Metadata*)) {
4404 ALL_JAVA_THREADS(p) {
4405 p->metadata_do(f);
4406 }
4407 }
4408
4409 class ThreadHandlesClosure : public ThreadClosure {
4410 void (*_f)(Metadata*);
4411 public:
4412 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4413 virtual void do_thread(Thread* thread) {
4414 thread->metadata_handles_do(_f);
4415 }
4416 };
4417
4418 void Threads::metadata_handles_do(void f(Metadata*)) {
4419 // Only walk the Handles in Thread.
4420 ThreadHandlesClosure handles_closure(f);
4421 threads_do(&handles_closure);
4422 }
4423
4424 void Threads::deoptimized_wrt_marked_nmethods() {
4425 ALL_JAVA_THREADS(p) {
4426 p->deoptimized_wrt_marked_nmethods();
4427 }
4428 }
4429
4430
4431 // Get count Java threads that are waiting to enter the specified monitor.
4432 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4433 address monitor,
4434 bool doLock) {
4435 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4436 "must grab Threads_lock or be at safepoint");
4437 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4438
4439 int i = 0;
4440 {
4441 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4442 ALL_JAVA_THREADS(p) {
4443 if (!p->can_call_java()) continue;
4444
4445 address pending = (address)p->current_pending_monitor();
4446 if (pending == monitor) { // found a match
4447 if (i < count) result->append(p); // save the first count matches
4448 i++;
4449 }
4450 }
4451 }
4452 return result;
4453 }
4454
4455
4456 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4457 bool doLock) {
4458 assert(doLock ||
4459 Threads_lock->owned_by_self() ||
4460 SafepointSynchronize::is_at_safepoint(),
4461 "must grab Threads_lock or be at safepoint");
4462
4463 // NULL owner means not locked so we can skip the search
4464 if (owner == NULL) return NULL;
4465
4466 {
4467 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4468 ALL_JAVA_THREADS(p) {
4469 // first, see if owner is the address of a Java thread
4470 if (owner == (address)p) return p;
4471 }
4472 }
4473 // Cannot assert on lack of success here since this function may be
4474 // used by code that is trying to report useful problem information
4475 // like deadlock detection.
4476 if (UseHeavyMonitors) return NULL;
4477
4478 // If we didn't find a matching Java thread and we didn't force use of
4479 // heavyweight monitors, then the owner is the stack address of the
4480 // Lock Word in the owning Java thread's stack.
4481 //
4482 JavaThread* the_owner = NULL;
4483 {
4484 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4485 ALL_JAVA_THREADS(q) {
4486 if (q->is_lock_owned(owner)) {
4487 the_owner = q;
4488 break;
4489 }
4490 }
4491 }
4492 // cannot assert on lack of success here; see above comment
4493 return the_owner;
4494 }
4495
4496 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4497 void Threads::print_on(outputStream* st, bool print_stacks,
4498 bool internal_format, bool print_concurrent_locks) {
4499 char buf[32];
4500 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4501
4502 st->print_cr("Full thread dump %s (%s %s):",
4503 Abstract_VM_Version::vm_name(),
4504 Abstract_VM_Version::vm_release(),
4505 Abstract_VM_Version::vm_info_string());
4506 st->cr();
4507
4508 #if INCLUDE_SERVICES
4509 // Dump concurrent locks
4510 ConcurrentLocksDump concurrent_locks;
4511 if (print_concurrent_locks) {
4512 concurrent_locks.dump_at_safepoint();
4513 }
4514 #endif // INCLUDE_SERVICES
4515
4516 ALL_JAVA_THREADS(p) {
4517 ResourceMark rm;
4518 p->print_on(st);
4519 if (print_stacks) {
4520 if (internal_format) {
4521 p->trace_stack();
4522 } else {
4523 p->print_stack_on(st);
4524 }
4525 }
4526 st->cr();
4527 #if INCLUDE_SERVICES
4528 if (print_concurrent_locks) {
4529 concurrent_locks.print_locks_on(p, st);
4530 }
4531 #endif // INCLUDE_SERVICES
4532 }
4533
4534 VMThread::vm_thread()->print_on(st);
4535 st->cr();
4536 Universe::heap()->print_gc_threads_on(st);
4537 WatcherThread* wt = WatcherThread::watcher_thread();
4538 if (wt != NULL) {
4539 wt->print_on(st);
4540 st->cr();
4541 }
4542 st->flush();
4543 }
4544
4545 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4546 int buflen, bool* found_current) {
4547 if (this_thread != NULL) {
4548 bool is_current = (current == this_thread);
4549 *found_current = *found_current || is_current;
4550 st->print("%s", is_current ? "=>" : " ");
4551
4552 st->print(PTR_FORMAT, p2i(this_thread));
4553 st->print(" ");
4554 this_thread->print_on_error(st, buf, buflen);
4555 st->cr();
4556 }
4557 }
4558
4559 class PrintOnErrorClosure : public ThreadClosure {
4560 outputStream* _st;
4561 Thread* _current;
4562 char* _buf;
4563 int _buflen;
4564 bool* _found_current;
4565 public:
4566 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4567 int buflen, bool* found_current) :
4568 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4569
4570 virtual void do_thread(Thread* thread) {
4571 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4572 }
4573 };
4574
4575 // Threads::print_on_error() is called by fatal error handler. It's possible
4576 // that VM is not at safepoint and/or current thread is inside signal handler.
4577 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4578 // memory (even in resource area), it might deadlock the error handler.
4579 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4580 int buflen) {
4581 bool found_current = false;
4582 st->print_cr("Java Threads: ( => current thread )");
4583 ALL_JAVA_THREADS(thread) {
4584 print_on_error(thread, st, current, buf, buflen, &found_current);
4585 }
4586 st->cr();
4587
4588 st->print_cr("Other Threads:");
4589 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4590 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4591
4592 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4593 Universe::heap()->gc_threads_do(&print_closure);
4594
4595 if (!found_current) {
4596 st->cr();
4597 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4598 current->print_on_error(st, buf, buflen);
4599 st->cr();
4600 }
4601 st->cr();
4602 st->print_cr("Threads with active compile tasks:");
4603 print_threads_compiling(st, buf, buflen);
4604 }
4605
4606 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4607 ALL_JAVA_THREADS(thread) {
4608 if (thread->is_Compiler_thread()) {
4609 CompilerThread* ct = (CompilerThread*) thread;
4610 if (ct->task() != NULL) {
4611 thread->print_name_on_error(st, buf, buflen);
4612 ct->task()->print(st, NULL, true, true);
4613 }
4614 }
4615 }
4616 }
4617
4618
4619 // Internal SpinLock and Mutex
4620 // Based on ParkEvent
4621
4622 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4623 //
4624 // We employ SpinLocks _only for low-contention, fixed-length
4625 // short-duration critical sections where we're concerned
4626 // about native mutex_t or HotSpot Mutex:: latency.
4627 // The mux construct provides a spin-then-block mutual exclusion
4628 // mechanism.
4629 //
4630 // Testing has shown that contention on the ListLock guarding gFreeList
4631 // is common. If we implement ListLock as a simple SpinLock it's common
4632 // for the JVM to devolve to yielding with little progress. This is true
4633 // despite the fact that the critical sections protected by ListLock are
4634 // extremely short.
4635 //
4636 // TODO-FIXME: ListLock should be of type SpinLock.
4637 // We should make this a 1st-class type, integrated into the lock
4638 // hierarchy as leaf-locks. Critically, the SpinLock structure
4639 // should have sufficient padding to avoid false-sharing and excessive
4640 // cache-coherency traffic.
4641
4642
4643 typedef volatile int SpinLockT;
4644
4645 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4646 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4647 return; // normal fast-path return
4648 }
4649
4650 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4651 TEVENT(SpinAcquire - ctx);
4652 int ctr = 0;
4653 int Yields = 0;
4654 for (;;) {
4655 while (*adr != 0) {
4656 ++ctr;
4657 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4658 if (Yields > 5) {
4659 os::naked_short_sleep(1);
4660 } else {
4661 os::naked_yield();
4662 ++Yields;
4663 }
4664 } else {
4665 SpinPause();
4666 }
4667 }
4668 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4669 }
4670 }
4671
4672 void Thread::SpinRelease(volatile int * adr) {
4673 assert(*adr != 0, "invariant");
4674 OrderAccess::fence(); // guarantee at least release consistency.
4675 // Roach-motel semantics.
4676 // It's safe if subsequent LDs and STs float "up" into the critical section,
4677 // but prior LDs and STs within the critical section can't be allowed
4678 // to reorder or float past the ST that releases the lock.
4679 // Loads and stores in the critical section - which appear in program
4680 // order before the store that releases the lock - must also appear
4681 // before the store that releases the lock in memory visibility order.
4682 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4683 // the ST of 0 into the lock-word which releases the lock, so fence
4684 // more than covers this on all platforms.
4685 *adr = 0;
4686 }
4687
4688 // muxAcquire and muxRelease:
4689 //
4690 // * muxAcquire and muxRelease support a single-word lock-word construct.
4691 // The LSB of the word is set IFF the lock is held.
4692 // The remainder of the word points to the head of a singly-linked list
4693 // of threads blocked on the lock.
4694 //
4695 // * The current implementation of muxAcquire-muxRelease uses its own
4696 // dedicated Thread._MuxEvent instance. If we're interested in
4697 // minimizing the peak number of extant ParkEvent instances then
4698 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4699 // as certain invariants were satisfied. Specifically, care would need
4700 // to be taken with regards to consuming unpark() "permits".
4701 // A safe rule of thumb is that a thread would never call muxAcquire()
4702 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4703 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4704 // consume an unpark() permit intended for monitorenter, for instance.
4705 // One way around this would be to widen the restricted-range semaphore
4706 // implemented in park(). Another alternative would be to provide
4707 // multiple instances of the PlatformEvent() for each thread. One
4708 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4709 //
4710 // * Usage:
4711 // -- Only as leaf locks
4712 // -- for short-term locking only as muxAcquire does not perform
4713 // thread state transitions.
4714 //
4715 // Alternatives:
4716 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4717 // but with parking or spin-then-park instead of pure spinning.
4718 // * Use Taura-Oyama-Yonenzawa locks.
4719 // * It's possible to construct a 1-0 lock if we encode the lockword as
4720 // (List,LockByte). Acquire will CAS the full lockword while Release
4721 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4722 // acquiring threads use timers (ParkTimed) to detect and recover from
4723 // the stranding window. Thread/Node structures must be aligned on 256-byte
4724 // boundaries by using placement-new.
4725 // * Augment MCS with advisory back-link fields maintained with CAS().
4726 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4727 // The validity of the backlinks must be ratified before we trust the value.
4728 // If the backlinks are invalid the exiting thread must back-track through the
4729 // the forward links, which are always trustworthy.
4730 // * Add a successor indication. The LockWord is currently encoded as
4731 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4732 // to provide the usual futile-wakeup optimization.
4733 // See RTStt for details.
4734 // * Consider schedctl.sc_nopreempt to cover the critical section.
4735 //
4736
4737
4738 typedef volatile intptr_t MutexT; // Mux Lock-word
4739 enum MuxBits { LOCKBIT = 1 };
4740
4741 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4742 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4743 if (w == 0) return;
4744 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4745 return;
4746 }
4747
4748 TEVENT(muxAcquire - Contention);
4749 ParkEvent * const Self = Thread::current()->_MuxEvent;
4750 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4751 for (;;) {
4752 int its = (os::is_MP() ? 100 : 0) + 1;
4753
4754 // Optional spin phase: spin-then-park strategy
4755 while (--its >= 0) {
4756 w = *Lock;
4757 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4758 return;
4759 }
4760 }
4761
4762 Self->reset();
4763 Self->OnList = intptr_t(Lock);
4764 // The following fence() isn't _strictly necessary as the subsequent
4765 // CAS() both serializes execution and ratifies the fetched *Lock value.
4766 OrderAccess::fence();
4767 for (;;) {
4768 w = *Lock;
4769 if ((w & LOCKBIT) == 0) {
4770 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4771 Self->OnList = 0; // hygiene - allows stronger asserts
4772 return;
4773 }
4774 continue; // Interference -- *Lock changed -- Just retry
4775 }
4776 assert(w & LOCKBIT, "invariant");
4777 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4778 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4779 }
4780
4781 while (Self->OnList != 0) {
4782 Self->park();
4783 }
4784 }
4785 }
4786
4787 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4788 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4789 if (w == 0) return;
4790 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4791 return;
4792 }
4793
4794 TEVENT(muxAcquire - Contention);
4795 ParkEvent * ReleaseAfter = NULL;
4796 if (ev == NULL) {
4797 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4798 }
4799 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4800 for (;;) {
4801 guarantee(ev->OnList == 0, "invariant");
4802 int its = (os::is_MP() ? 100 : 0) + 1;
4803
4804 // Optional spin phase: spin-then-park strategy
4805 while (--its >= 0) {
4806 w = *Lock;
4807 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4808 if (ReleaseAfter != NULL) {
4809 ParkEvent::Release(ReleaseAfter);
4810 }
4811 return;
4812 }
4813 }
4814
4815 ev->reset();
4816 ev->OnList = intptr_t(Lock);
4817 // The following fence() isn't _strictly necessary as the subsequent
4818 // CAS() both serializes execution and ratifies the fetched *Lock value.
4819 OrderAccess::fence();
4820 for (;;) {
4821 w = *Lock;
4822 if ((w & LOCKBIT) == 0) {
4823 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4824 ev->OnList = 0;
4825 // We call ::Release while holding the outer lock, thus
4826 // artificially lengthening the critical section.
4827 // Consider deferring the ::Release() until the subsequent unlock(),
4828 // after we've dropped the outer lock.
4829 if (ReleaseAfter != NULL) {
4830 ParkEvent::Release(ReleaseAfter);
4831 }
4832 return;
4833 }
4834 continue; // Interference -- *Lock changed -- Just retry
4835 }
4836 assert(w & LOCKBIT, "invariant");
4837 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4838 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4839 }
4840
4841 while (ev->OnList != 0) {
4842 ev->park();
4843 }
4844 }
4845 }
4846
4847 // Release() must extract a successor from the list and then wake that thread.
4848 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4849 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4850 // Release() would :
4851 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4852 // (B) Extract a successor from the private list "in-hand"
4853 // (C) attempt to CAS() the residual back into *Lock over null.
4854 // If there were any newly arrived threads and the CAS() would fail.
4855 // In that case Release() would detach the RATs, re-merge the list in-hand
4856 // with the RATs and repeat as needed. Alternately, Release() might
4857 // detach and extract a successor, but then pass the residual list to the wakee.
4858 // The wakee would be responsible for reattaching and remerging before it
4859 // competed for the lock.
4860 //
4861 // Both "pop" and DMR are immune from ABA corruption -- there can be
4862 // multiple concurrent pushers, but only one popper or detacher.
4863 // This implementation pops from the head of the list. This is unfair,
4864 // but tends to provide excellent throughput as hot threads remain hot.
4865 // (We wake recently run threads first).
4866 //
4867 // All paths through muxRelease() will execute a CAS.
4868 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4869 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4870 // executed within the critical section are complete and globally visible before the
4871 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4872 void Thread::muxRelease(volatile intptr_t * Lock) {
4873 for (;;) {
4874 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4875 assert(w & LOCKBIT, "invariant");
4876 if (w == LOCKBIT) return;
4877 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4878 assert(List != NULL, "invariant");
4879 assert(List->OnList == intptr_t(Lock), "invariant");
4880 ParkEvent * const nxt = List->ListNext;
4881 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4882
4883 // The following CAS() releases the lock and pops the head element.
4884 // The CAS() also ratifies the previously fetched lock-word value.
4885 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4886 continue;
4887 }
4888 List->OnList = 0;
4889 OrderAccess::fence();
4890 List->unpark();
4891 return;
4892 }
4893 }
4894
4895
4896 void Threads::verify() {
4897 ALL_JAVA_THREADS(p) {
4898 p->verify();
4899 }
4900 VMThread* thread = VMThread::vm_thread();
4901 if (thread != NULL) thread->verify();
4902 }