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