1 /*
2 * Copyright (c) 1997, 2017, 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/shenandoah/shenandoahConcurrentThread.hpp"
105 #include "gc/cms/concurrentMarkSweepThread.hpp"
106 #include "gc/g1/concurrentMarkThread.inline.hpp"
107 #include "gc/parallel/pcTasks.hpp"
108 #endif // INCLUDE_ALL_GCS
109 #if INCLUDE_JVMCI
110 #include "jvmci/jvmciCompiler.hpp"
111 #include "jvmci/jvmciRuntime.hpp"
112 #endif
113 #ifdef COMPILER1
114 #include "c1/c1_Compiler.hpp"
115 #endif
116 #ifdef COMPILER2
117 #include "opto/c2compiler.hpp"
118 #include "opto/idealGraphPrinter.hpp"
119 #endif
120 #if INCLUDE_RTM_OPT
121 #include "runtime/rtmLocking.hpp"
122 #endif
123
124 // Initialization after module runtime initialization
125 void universe_post_module_init(); // must happen after call_initPhase2
126
127 #ifdef DTRACE_ENABLED
128
129 // Only bother with this argument setup if dtrace is available
130
131 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
132 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
133
134 #define DTRACE_THREAD_PROBE(probe, javathread) \
135 { \
136 ResourceMark rm(this); \
137 int len = 0; \
138 const char* name = (javathread)->get_thread_name(); \
139 len = strlen(name); \
140 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
141 (char *) name, len, \
142 java_lang_Thread::thread_id((javathread)->threadObj()), \
143 (uintptr_t) (javathread)->osthread()->thread_id(), \
144 java_lang_Thread::is_daemon((javathread)->threadObj())); \
145 }
146
147 #else // ndef DTRACE_ENABLED
148
149 #define DTRACE_THREAD_PROBE(probe, javathread)
150
151 #endif // ndef DTRACE_ENABLED
152
153 #ifndef USE_LIBRARY_BASED_TLS_ONLY
154 // Current thread is maintained as a thread-local variable
155 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
156 #endif
157 // Class hierarchy
158 // - Thread
159 // - VMThread
160 // - WatcherThread
161 // - ConcurrentMarkSweepThread
162 // - JavaThread
163 // - CompilerThread
164
165 // ======= Thread ========
166 // Support for forcing alignment of thread objects for biased locking
167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
168 if (UseBiasedLocking) {
169 const int alignment = markOopDesc::biased_lock_alignment;
170 size_t aligned_size = size + (alignment - sizeof(intptr_t));
171 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
172 : AllocateHeap(aligned_size, flags, CURRENT_PC,
173 AllocFailStrategy::RETURN_NULL);
174 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
175 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
176 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
177 "JavaThread alignment code overflowed allocated storage");
178 if (aligned_addr != real_malloc_addr) {
179 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
180 p2i(real_malloc_addr),
181 p2i(aligned_addr));
182 }
183 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
184 return aligned_addr;
185 } else {
186 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
187 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
188 }
189 }
190
191 void Thread::operator delete(void* p) {
192 if (UseBiasedLocking) {
193 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
194 FreeHeap(real_malloc_addr);
195 } else {
196 FreeHeap(p);
197 }
198 }
199
200
201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
202 // JavaThread
203
204
205 Thread::Thread() {
206 // stack and get_thread
207 set_stack_base(NULL);
208 set_stack_size(0);
209 set_self_raw_id(0);
210 set_lgrp_id(-1);
211 DEBUG_ONLY(clear_suspendible_thread();)
212
213 // allocated data structures
214 set_osthread(NULL);
215 set_resource_area(new (mtThread)ResourceArea());
216 DEBUG_ONLY(_current_resource_mark = NULL;)
217 set_handle_area(new (mtThread) HandleArea(NULL));
218 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
219 set_active_handles(NULL);
220 set_free_handle_block(NULL);
221 set_last_handle_mark(NULL);
222
223 // This initial value ==> never claimed.
224 _oops_do_parity = 0;
225
226 // the handle mark links itself to last_handle_mark
227 new HandleMark(this);
228
229 // plain initialization
230 debug_only(_owned_locks = NULL;)
231 debug_only(_allow_allocation_count = 0;)
232 NOT_PRODUCT(_allow_safepoint_count = 0;)
233 NOT_PRODUCT(_skip_gcalot = false;)
234 _jvmti_env_iteration_count = 0;
235 set_allocated_bytes(0);
236 _vm_operation_started_count = 0;
237 _vm_operation_completed_count = 0;
238 _current_pending_monitor = NULL;
239 _current_pending_monitor_is_from_java = true;
240 _current_waiting_monitor = NULL;
241 _num_nested_signal = 0;
242 omFreeList = NULL;
243 omFreeCount = 0;
244 omFreeProvision = 32;
245 omInUseList = NULL;
246 omInUseCount = 0;
247
248 #ifdef ASSERT
249 _visited_for_critical_count = false;
250 #endif
251
252 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
253 Monitor::_safepoint_check_sometimes);
254 _suspend_flags = 0;
255
256 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
257 _hashStateX = os::random();
258 _hashStateY = 842502087;
259 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
260 _hashStateW = 273326509;
261
262 _OnTrap = 0;
263 _schedctl = NULL;
264 _Stalled = 0;
265 _TypeTag = 0x2BAD;
266
267 // Many of the following fields are effectively final - immutable
268 // Note that nascent threads can't use the Native Monitor-Mutex
269 // construct until the _MutexEvent is initialized ...
270 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
271 // we might instead use a stack of ParkEvents that we could provision on-demand.
272 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
273 // and ::Release()
274 _ParkEvent = ParkEvent::Allocate(this);
275 _SleepEvent = ParkEvent::Allocate(this);
276 _MutexEvent = ParkEvent::Allocate(this);
277 _MuxEvent = ParkEvent::Allocate(this);
278
279 #ifdef CHECK_UNHANDLED_OOPS
280 if (CheckUnhandledOops) {
281 _unhandled_oops = new UnhandledOops(this);
282 }
283 #endif // CHECK_UNHANDLED_OOPS
284 #ifdef ASSERT
285 if (UseBiasedLocking) {
286 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
287 assert(this == _real_malloc_address ||
288 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
289 "bug in forced alignment of thread objects");
290 }
291 #endif // ASSERT
292 }
293
294 void Thread::initialize_thread_current() {
295 #ifndef USE_LIBRARY_BASED_TLS_ONLY
296 assert(_thr_current == NULL, "Thread::current already initialized");
297 _thr_current = this;
298 #endif
299 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
300 ThreadLocalStorage::set_thread(this);
301 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
302 }
303
304 void Thread::clear_thread_current() {
305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
306 #ifndef USE_LIBRARY_BASED_TLS_ONLY
307 _thr_current = NULL;
308 #endif
309 ThreadLocalStorage::set_thread(NULL);
310 }
311
312 void Thread::record_stack_base_and_size() {
313 set_stack_base(os::current_stack_base());
314 set_stack_size(os::current_stack_size());
315 // CR 7190089: on Solaris, primordial thread's stack is adjusted
316 // in initialize_thread(). Without the adjustment, stack size is
317 // incorrect if stack is set to unlimited (ulimit -s unlimited).
318 // So far, only Solaris has real implementation of initialize_thread().
319 //
320 // set up any platform-specific state.
321 os::initialize_thread(this);
322
323 // Set stack limits after thread is initialized.
324 if (is_Java_thread()) {
325 ((JavaThread*) this)->set_stack_overflow_limit();
326 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
327 }
328 #if INCLUDE_NMT
329 // record thread's native stack, stack grows downward
330 MemTracker::record_thread_stack(stack_end(), stack_size());
331 #endif // INCLUDE_NMT
332 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
333 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
334 os::current_thread_id(), p2i(stack_base() - stack_size()),
335 p2i(stack_base()), stack_size()/1024);
336 }
337
338
339 Thread::~Thread() {
340 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
341 ObjectSynchronizer::omFlush(this);
342
343 EVENT_THREAD_DESTRUCT(this);
344
345 // stack_base can be NULL if the thread is never started or exited before
346 // record_stack_base_and_size called. Although, we would like to ensure
347 // that all started threads do call record_stack_base_and_size(), there is
348 // not proper way to enforce that.
349 #if INCLUDE_NMT
350 if (_stack_base != NULL) {
351 MemTracker::release_thread_stack(stack_end(), stack_size());
352 #ifdef ASSERT
353 set_stack_base(NULL);
354 #endif
355 }
356 #endif // INCLUDE_NMT
357
358 // deallocate data structures
359 delete resource_area();
360 // since the handle marks are using the handle area, we have to deallocated the root
361 // handle mark before deallocating the thread's handle area,
362 assert(last_handle_mark() != NULL, "check we have an element");
363 delete last_handle_mark();
364 assert(last_handle_mark() == NULL, "check we have reached the end");
365
366 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
367 // We NULL out the fields for good hygiene.
368 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
369 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
370 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
371 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
372
373 delete handle_area();
374 delete metadata_handles();
375
376 // SR_handler uses this as a termination indicator -
377 // needs to happen before os::free_thread()
378 delete _SR_lock;
379 _SR_lock = NULL;
380
381 // osthread() can be NULL, if creation of thread failed.
382 if (osthread() != NULL) os::free_thread(osthread());
383
384 // clear Thread::current if thread is deleting itself.
385 // Needed to ensure JNI correctly detects non-attached threads.
386 if (this == Thread::current()) {
387 clear_thread_current();
388 }
389
390 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
391 }
392
393 // NOTE: dummy function for assertion purpose.
394 void Thread::run() {
395 ShouldNotReachHere();
396 }
397
398 #ifdef ASSERT
399 // Private method to check for dangling thread pointer
400 void check_for_dangling_thread_pointer(Thread *thread) {
401 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
402 "possibility of dangling Thread pointer");
403 }
404 #endif
405
406 ThreadPriority Thread::get_priority(const Thread* const thread) {
407 ThreadPriority priority;
408 // Can return an error!
409 (void)os::get_priority(thread, priority);
410 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
411 return priority;
412 }
413
414 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
415 debug_only(check_for_dangling_thread_pointer(thread);)
416 // Can return an error!
417 (void)os::set_priority(thread, priority);
418 }
419
420
421 void Thread::start(Thread* thread) {
422 // Start is different from resume in that its safety is guaranteed by context or
423 // being called from a Java method synchronized on the Thread object.
424 if (!DisableStartThread) {
425 if (thread->is_Java_thread()) {
426 // Initialize the thread state to RUNNABLE before starting this thread.
427 // Can not set it after the thread started because we do not know the
428 // exact thread state at that time. It could be in MONITOR_WAIT or
429 // in SLEEPING or some other state.
430 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
431 java_lang_Thread::RUNNABLE);
432 }
433 os::start_thread(thread);
434 }
435 }
436
437 // Enqueue a VM_Operation to do the job for us - sometime later
438 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
439 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
440 VMThread::execute(vm_stop);
441 }
442
443
444 // Check if an external suspend request has completed (or has been
445 // cancelled). Returns true if the thread is externally suspended and
446 // false otherwise.
447 //
448 // The bits parameter returns information about the code path through
449 // the routine. Useful for debugging:
450 //
451 // set in is_ext_suspend_completed():
452 // 0x00000001 - routine was entered
453 // 0x00000010 - routine return false at end
454 // 0x00000100 - thread exited (return false)
455 // 0x00000200 - suspend request cancelled (return false)
456 // 0x00000400 - thread suspended (return true)
457 // 0x00001000 - thread is in a suspend equivalent state (return true)
458 // 0x00002000 - thread is native and walkable (return true)
459 // 0x00004000 - thread is native_trans and walkable (needed retry)
460 //
461 // set in wait_for_ext_suspend_completion():
462 // 0x00010000 - routine was entered
463 // 0x00020000 - suspend request cancelled before loop (return false)
464 // 0x00040000 - thread suspended before loop (return true)
465 // 0x00080000 - suspend request cancelled in loop (return false)
466 // 0x00100000 - thread suspended in loop (return true)
467 // 0x00200000 - suspend not completed during retry loop (return false)
468
469 // Helper class for tracing suspend wait debug bits.
470 //
471 // 0x00000100 indicates that the target thread exited before it could
472 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
473 // 0x00080000 each indicate a cancelled suspend request so they don't
474 // count as wait failures either.
475 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
476
477 class TraceSuspendDebugBits : public StackObj {
478 private:
479 JavaThread * jt;
480 bool is_wait;
481 bool called_by_wait; // meaningful when !is_wait
482 uint32_t * bits;
483
484 public:
485 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
486 uint32_t *_bits) {
487 jt = _jt;
488 is_wait = _is_wait;
489 called_by_wait = _called_by_wait;
490 bits = _bits;
491 }
492
493 ~TraceSuspendDebugBits() {
494 if (!is_wait) {
495 #if 1
496 // By default, don't trace bits for is_ext_suspend_completed() calls.
497 // That trace is very chatty.
498 return;
499 #else
500 if (!called_by_wait) {
501 // If tracing for is_ext_suspend_completed() is enabled, then only
502 // trace calls to it from wait_for_ext_suspend_completion()
503 return;
504 }
505 #endif
506 }
507
508 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
509 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
510 MutexLocker ml(Threads_lock); // needed for get_thread_name()
511 ResourceMark rm;
512
513 tty->print_cr(
514 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
515 jt->get_thread_name(), *bits);
516
517 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
518 }
519 }
520 }
521 };
522 #undef DEBUG_FALSE_BITS
523
524
525 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
526 uint32_t *bits) {
527 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
528
529 bool did_trans_retry = false; // only do thread_in_native_trans retry once
530 bool do_trans_retry; // flag to force the retry
531
532 *bits |= 0x00000001;
533
534 do {
535 do_trans_retry = false;
536
537 if (is_exiting()) {
538 // Thread is in the process of exiting. This is always checked
539 // first to reduce the risk of dereferencing a freed JavaThread.
540 *bits |= 0x00000100;
541 return false;
542 }
543
544 if (!is_external_suspend()) {
545 // Suspend request is cancelled. This is always checked before
546 // is_ext_suspended() to reduce the risk of a rogue resume
547 // confusing the thread that made the suspend request.
548 *bits |= 0x00000200;
549 return false;
550 }
551
552 if (is_ext_suspended()) {
553 // thread is suspended
554 *bits |= 0x00000400;
555 return true;
556 }
557
558 // Now that we no longer do hard suspends of threads running
559 // native code, the target thread can be changing thread state
560 // while we are in this routine:
561 //
562 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
563 //
564 // We save a copy of the thread state as observed at this moment
565 // and make our decision about suspend completeness based on the
566 // copy. This closes the race where the thread state is seen as
567 // _thread_in_native_trans in the if-thread_blocked check, but is
568 // seen as _thread_blocked in if-thread_in_native_trans check.
569 JavaThreadState save_state = thread_state();
570
571 if (save_state == _thread_blocked && is_suspend_equivalent()) {
572 // If the thread's state is _thread_blocked and this blocking
573 // condition is known to be equivalent to a suspend, then we can
574 // consider the thread to be externally suspended. This means that
575 // the code that sets _thread_blocked has been modified to do
576 // self-suspension if the blocking condition releases. We also
577 // used to check for CONDVAR_WAIT here, but that is now covered by
578 // the _thread_blocked with self-suspension check.
579 //
580 // Return true since we wouldn't be here unless there was still an
581 // external suspend request.
582 *bits |= 0x00001000;
583 return true;
584 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
585 // Threads running native code will self-suspend on native==>VM/Java
586 // transitions. If its stack is walkable (should always be the case
587 // unless this function is called before the actual java_suspend()
588 // call), then the wait is done.
589 *bits |= 0x00002000;
590 return true;
591 } else if (!called_by_wait && !did_trans_retry &&
592 save_state == _thread_in_native_trans &&
593 frame_anchor()->walkable()) {
594 // The thread is transitioning from thread_in_native to another
595 // thread state. check_safepoint_and_suspend_for_native_trans()
596 // will force the thread to self-suspend. If it hasn't gotten
597 // there yet we may have caught the thread in-between the native
598 // code check above and the self-suspend. Lucky us. If we were
599 // called by wait_for_ext_suspend_completion(), then it
600 // will be doing the retries so we don't have to.
601 //
602 // Since we use the saved thread state in the if-statement above,
603 // there is a chance that the thread has already transitioned to
604 // _thread_blocked by the time we get here. In that case, we will
605 // make a single unnecessary pass through the logic below. This
606 // doesn't hurt anything since we still do the trans retry.
607
608 *bits |= 0x00004000;
609
610 // Once the thread leaves thread_in_native_trans for another
611 // thread state, we break out of this retry loop. We shouldn't
612 // need this flag to prevent us from getting back here, but
613 // sometimes paranoia is good.
614 did_trans_retry = true;
615
616 // We wait for the thread to transition to a more usable state.
617 for (int i = 1; i <= SuspendRetryCount; i++) {
618 // We used to do an "os::yield_all(i)" call here with the intention
619 // that yielding would increase on each retry. However, the parameter
620 // is ignored on Linux which means the yield didn't scale up. Waiting
621 // on the SR_lock below provides a much more predictable scale up for
622 // the delay. It also provides a simple/direct point to check for any
623 // safepoint requests from the VMThread
624
625 // temporarily drops SR_lock while doing wait with safepoint check
626 // (if we're a JavaThread - the WatcherThread can also call this)
627 // and increase delay with each retry
628 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
629
630 // check the actual thread state instead of what we saved above
631 if (thread_state() != _thread_in_native_trans) {
632 // the thread has transitioned to another thread state so
633 // try all the checks (except this one) one more time.
634 do_trans_retry = true;
635 break;
636 }
637 } // end retry loop
638
639
640 }
641 } while (do_trans_retry);
642
643 *bits |= 0x00000010;
644 return false;
645 }
646
647 // Wait for an external suspend request to complete (or be cancelled).
648 // Returns true if the thread is externally suspended and false otherwise.
649 //
650 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
651 uint32_t *bits) {
652 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
653 false /* !called_by_wait */, bits);
654
655 // local flag copies to minimize SR_lock hold time
656 bool is_suspended;
657 bool pending;
658 uint32_t reset_bits;
659
660 // set a marker so is_ext_suspend_completed() knows we are the caller
661 *bits |= 0x00010000;
662
663 // We use reset_bits to reinitialize the bits value at the top of
664 // each retry loop. This allows the caller to make use of any
665 // unused bits for their own marking purposes.
666 reset_bits = *bits;
667
668 {
669 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
670 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
671 delay, bits);
672 pending = is_external_suspend();
673 }
674 // must release SR_lock to allow suspension to complete
675
676 if (!pending) {
677 // A cancelled suspend request is the only false return from
678 // is_ext_suspend_completed() that keeps us from entering the
679 // retry loop.
680 *bits |= 0x00020000;
681 return false;
682 }
683
684 if (is_suspended) {
685 *bits |= 0x00040000;
686 return true;
687 }
688
689 for (int i = 1; i <= retries; i++) {
690 *bits = reset_bits; // reinit to only track last retry
691
692 // We used to do an "os::yield_all(i)" call here with the intention
693 // that yielding would increase on each retry. However, the parameter
694 // is ignored on Linux which means the yield didn't scale up. Waiting
695 // on the SR_lock below provides a much more predictable scale up for
696 // the delay. It also provides a simple/direct point to check for any
697 // safepoint requests from the VMThread
698
699 {
700 MutexLocker ml(SR_lock());
701 // wait with safepoint check (if we're a JavaThread - the WatcherThread
702 // can also call this) and increase delay with each retry
703 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
704
705 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
706 delay, bits);
707
708 // It is possible for the external suspend request to be cancelled
709 // (by a resume) before the actual suspend operation is completed.
710 // Refresh our local copy to see if we still need to wait.
711 pending = is_external_suspend();
712 }
713
714 if (!pending) {
715 // A cancelled suspend request is the only false return from
716 // is_ext_suspend_completed() that keeps us from staying in the
717 // retry loop.
718 *bits |= 0x00080000;
719 return false;
720 }
721
722 if (is_suspended) {
723 *bits |= 0x00100000;
724 return true;
725 }
726 } // end retry loop
727
728 // thread did not suspend after all our retries
729 *bits |= 0x00200000;
730 return false;
731 }
732
733 #ifndef PRODUCT
734 void JavaThread::record_jump(address target, address instr, const char* file,
735 int line) {
736
737 // This should not need to be atomic as the only way for simultaneous
738 // updates is via interrupts. Even then this should be rare or non-existent
739 // and we don't care that much anyway.
740
741 int index = _jmp_ring_index;
742 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
743 _jmp_ring[index]._target = (intptr_t) target;
744 _jmp_ring[index]._instruction = (intptr_t) instr;
745 _jmp_ring[index]._file = file;
746 _jmp_ring[index]._line = line;
747 }
748 #endif // PRODUCT
749
750 // Called by flat profiler
751 // Callers have already called wait_for_ext_suspend_completion
752 // The assertion for that is currently too complex to put here:
753 bool JavaThread::profile_last_Java_frame(frame* _fr) {
754 bool gotframe = false;
755 // self suspension saves needed state.
756 if (has_last_Java_frame() && _anchor.walkable()) {
757 *_fr = pd_last_frame();
758 gotframe = true;
759 }
760 return gotframe;
761 }
762
763 void Thread::interrupt(Thread* thread) {
764 debug_only(check_for_dangling_thread_pointer(thread);)
765 os::interrupt(thread);
766 }
767
768 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
769 debug_only(check_for_dangling_thread_pointer(thread);)
770 // Note: If clear_interrupted==false, this simply fetches and
771 // returns the value of the field osthread()->interrupted().
772 return os::is_interrupted(thread, clear_interrupted);
773 }
774
775
776 // GC Support
777 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
778 jint thread_parity = _oops_do_parity;
779 if (thread_parity != strong_roots_parity) {
780 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
781 if (res == thread_parity) {
782 return true;
783 } else {
784 guarantee(res == strong_roots_parity, "Or else what?");
785 return false;
786 }
787 }
788 return false;
789 }
790
791 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
792 active_handles()->oops_do(f);
793 // Do oop for ThreadShadow
794 f->do_oop((oop*)&_pending_exception);
795 handle_area()->oops_do(f);
796 }
797
798 void Thread::metadata_handles_do(void f(Metadata*)) {
799 // Only walk the Handles in Thread.
800 if (metadata_handles() != NULL) {
801 for (int i = 0; i< metadata_handles()->length(); i++) {
802 f(metadata_handles()->at(i));
803 }
804 }
805 }
806
807 void Thread::print_on(outputStream* st) const {
808 // get_priority assumes osthread initialized
809 if (osthread() != NULL) {
810 int os_prio;
811 if (os::get_native_priority(this, &os_prio) == OS_OK) {
812 st->print("os_prio=%d ", os_prio);
813 }
814 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
815 ext().print_on(st);
816 osthread()->print_on(st);
817 }
818 debug_only(if (WizardMode) print_owned_locks_on(st);)
819 }
820
821 // Thread::print_on_error() is called by fatal error handler. Don't use
822 // any lock or allocate memory.
823 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
824 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
825
826 if (is_VM_thread()) { st->print("VMThread"); }
827 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
828 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
829 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
830 else { st->print("Thread"); }
831
832 if (is_Named_thread()) {
833 st->print(" \"%s\"", name());
834 }
835
836 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
837 p2i(stack_end()), p2i(stack_base()));
838
839 if (osthread()) {
840 st->print(" [id=%d]", osthread()->thread_id());
841 }
842 }
843
844 #ifdef ASSERT
845 void Thread::print_owned_locks_on(outputStream* st) const {
846 Monitor *cur = _owned_locks;
847 if (cur == NULL) {
848 st->print(" (no locks) ");
849 } else {
850 st->print_cr(" Locks owned:");
851 while (cur) {
852 cur->print_on(st);
853 cur = cur->next();
854 }
855 }
856 }
857
858 static int ref_use_count = 0;
859
860 bool Thread::owns_locks_but_compiled_lock() const {
861 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
862 if (cur != Compile_lock) return true;
863 }
864 return false;
865 }
866
867
868 #endif
869
870 #ifndef PRODUCT
871
872 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
873 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
874 // no threads which allow_vm_block's are held
875 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
876 // Check if current thread is allowed to block at a safepoint
877 if (!(_allow_safepoint_count == 0)) {
878 fatal("Possible safepoint reached by thread that does not allow it");
879 }
880 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
881 fatal("LEAF method calling lock?");
882 }
883
884 #ifdef ASSERT
885 if (potential_vm_operation && is_Java_thread()
886 && !Universe::is_bootstrapping()) {
887 // Make sure we do not hold any locks that the VM thread also uses.
888 // This could potentially lead to deadlocks
889 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
890 // Threads_lock is special, since the safepoint synchronization will not start before this is
891 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
892 // since it is used to transfer control between JavaThreads and the VMThread
893 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
894 if ((cur->allow_vm_block() &&
895 cur != Threads_lock &&
896 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
897 cur != VMOperationRequest_lock &&
898 cur != VMOperationQueue_lock) ||
899 cur->rank() == Mutex::special) {
900 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
901 }
902 }
903 }
904
905 if (GCALotAtAllSafepoints) {
906 // We could enter a safepoint here and thus have a gc
907 InterfaceSupport::check_gc_alot();
908 }
909 #endif
910 }
911 #endif
912
913 bool Thread::is_in_stack(address adr) const {
914 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
915 address end = os::current_stack_pointer();
916 // Allow non Java threads to call this without stack_base
917 if (_stack_base == NULL) return true;
918 if (stack_base() >= adr && adr >= end) return true;
919
920 return false;
921 }
922
923 bool Thread::is_in_usable_stack(address adr) const {
924 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
925 size_t usable_stack_size = _stack_size - stack_guard_size;
926
927 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
928 }
929
930
931 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
932 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
933 // used for compilation in the future. If that change is made, the need for these methods
934 // should be revisited, and they should be removed if possible.
935
936 bool Thread::is_lock_owned(address adr) const {
937 return on_local_stack(adr);
938 }
939
940 bool Thread::set_as_starting_thread() {
941 // NOTE: this must be called inside the main thread.
942 return os::create_main_thread((JavaThread*)this);
943 }
944
945 static void initialize_class(Symbol* class_name, TRAPS) {
946 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
947 InstanceKlass::cast(klass)->initialize(CHECK);
948 }
949
950
951 // Creates the initial ThreadGroup
952 static Handle create_initial_thread_group(TRAPS) {
953 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
954 instanceKlassHandle klass (THREAD, k);
955
956 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
957 {
958 JavaValue result(T_VOID);
959 JavaCalls::call_special(&result,
960 system_instance,
961 klass,
962 vmSymbols::object_initializer_name(),
963 vmSymbols::void_method_signature(),
964 CHECK_NH);
965 }
966 Universe::set_system_thread_group(system_instance());
967
968 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
969 {
970 JavaValue result(T_VOID);
971 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
972 JavaCalls::call_special(&result,
973 main_instance,
974 klass,
975 vmSymbols::object_initializer_name(),
976 vmSymbols::threadgroup_string_void_signature(),
977 system_instance,
978 string,
979 CHECK_NH);
980 }
981 return main_instance;
982 }
983
984 // Creates the initial Thread
985 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
986 TRAPS) {
987 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
988 instanceKlassHandle klass (THREAD, k);
989 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
990
991 java_lang_Thread::set_thread(thread_oop(), thread);
992 java_lang_Thread::set_priority(thread_oop(), NormPriority);
993 thread->set_threadObj(thread_oop());
994
995 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
996
997 JavaValue result(T_VOID);
998 JavaCalls::call_special(&result, thread_oop,
999 klass,
1000 vmSymbols::object_initializer_name(),
1001 vmSymbols::threadgroup_string_void_signature(),
1002 thread_group,
1003 string,
1004 CHECK_NULL);
1005 return thread_oop();
1006 }
1007
1008 char java_runtime_name[128] = "";
1009 char java_runtime_version[128] = "";
1010
1011 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1012 static const char* get_java_runtime_name(TRAPS) {
1013 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1014 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1015 fieldDescriptor fd;
1016 bool found = k != NULL &&
1017 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1018 vmSymbols::string_signature(), &fd);
1019 if (found) {
1020 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1021 if (name_oop == NULL) {
1022 return NULL;
1023 }
1024 const char* name = java_lang_String::as_utf8_string(name_oop,
1025 java_runtime_name,
1026 sizeof(java_runtime_name));
1027 return name;
1028 } else {
1029 return NULL;
1030 }
1031 }
1032
1033 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1034 static const char* get_java_runtime_version(TRAPS) {
1035 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1036 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1037 fieldDescriptor fd;
1038 bool found = k != NULL &&
1039 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1040 vmSymbols::string_signature(), &fd);
1041 if (found) {
1042 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1043 if (name_oop == NULL) {
1044 return NULL;
1045 }
1046 const char* name = java_lang_String::as_utf8_string(name_oop,
1047 java_runtime_version,
1048 sizeof(java_runtime_version));
1049 return name;
1050 } else {
1051 return NULL;
1052 }
1053 }
1054
1055 // General purpose hook into Java code, run once when the VM is initialized.
1056 // The Java library method itself may be changed independently from the VM.
1057 static void call_postVMInitHook(TRAPS) {
1058 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1059 instanceKlassHandle klass (THREAD, k);
1060 if (klass.not_null()) {
1061 JavaValue result(T_VOID);
1062 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1063 vmSymbols::void_method_signature(),
1064 CHECK);
1065 }
1066 }
1067
1068 static void reset_vm_info_property(TRAPS) {
1069 // the vm info string
1070 ResourceMark rm(THREAD);
1071 const char *vm_info = VM_Version::vm_info_string();
1072
1073 // java.lang.System class
1074 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1075 instanceKlassHandle klass (THREAD, k);
1076
1077 // setProperty arguments
1078 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1079 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1080
1081 // return value
1082 JavaValue r(T_OBJECT);
1083
1084 // public static String setProperty(String key, String value);
1085 JavaCalls::call_static(&r,
1086 klass,
1087 vmSymbols::setProperty_name(),
1088 vmSymbols::string_string_string_signature(),
1089 key_str,
1090 value_str,
1091 CHECK);
1092 }
1093
1094
1095 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1096 bool daemon, TRAPS) {
1097 assert(thread_group.not_null(), "thread group should be specified");
1098 assert(threadObj() == NULL, "should only create Java thread object once");
1099
1100 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1101 instanceKlassHandle klass (THREAD, k);
1102 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1103
1104 java_lang_Thread::set_thread(thread_oop(), this);
1105 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1106 set_threadObj(thread_oop());
1107
1108 JavaValue result(T_VOID);
1109 if (thread_name != NULL) {
1110 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1111 // Thread gets assigned specified name and null target
1112 JavaCalls::call_special(&result,
1113 thread_oop,
1114 klass,
1115 vmSymbols::object_initializer_name(),
1116 vmSymbols::threadgroup_string_void_signature(),
1117 thread_group, // Argument 1
1118 name, // Argument 2
1119 THREAD);
1120 } else {
1121 // Thread gets assigned name "Thread-nnn" and null target
1122 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1123 JavaCalls::call_special(&result,
1124 thread_oop,
1125 klass,
1126 vmSymbols::object_initializer_name(),
1127 vmSymbols::threadgroup_runnable_void_signature(),
1128 thread_group, // Argument 1
1129 Handle(), // Argument 2
1130 THREAD);
1131 }
1132
1133
1134 if (daemon) {
1135 java_lang_Thread::set_daemon(thread_oop());
1136 }
1137
1138 if (HAS_PENDING_EXCEPTION) {
1139 return;
1140 }
1141
1142 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1143 Handle threadObj(THREAD, this->threadObj());
1144
1145 JavaCalls::call_special(&result,
1146 thread_group,
1147 group,
1148 vmSymbols::add_method_name(),
1149 vmSymbols::thread_void_signature(),
1150 threadObj, // Arg 1
1151 THREAD);
1152 }
1153
1154 // NamedThread -- non-JavaThread subclasses with multiple
1155 // uniquely named instances should derive from this.
1156 NamedThread::NamedThread() : Thread() {
1157 _name = NULL;
1158 _processed_thread = NULL;
1159 _gc_id = GCId::undefined();
1160 }
1161
1162 NamedThread::~NamedThread() {
1163 if (_name != NULL) {
1164 FREE_C_HEAP_ARRAY(char, _name);
1165 _name = NULL;
1166 }
1167 }
1168
1169 void NamedThread::set_name(const char* format, ...) {
1170 guarantee(_name == NULL, "Only get to set name once.");
1171 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1172 guarantee(_name != NULL, "alloc failure");
1173 va_list ap;
1174 va_start(ap, format);
1175 jio_vsnprintf(_name, max_name_len, format, ap);
1176 va_end(ap);
1177 }
1178
1179 void NamedThread::initialize_named_thread() {
1180 set_native_thread_name(name());
1181 }
1182
1183 void NamedThread::print_on(outputStream* st) const {
1184 st->print("\"%s\" ", name());
1185 Thread::print_on(st);
1186 st->cr();
1187 }
1188
1189
1190 // ======= WatcherThread ========
1191
1192 // The watcher thread exists to simulate timer interrupts. It should
1193 // be replaced by an abstraction over whatever native support for
1194 // timer interrupts exists on the platform.
1195
1196 WatcherThread* WatcherThread::_watcher_thread = NULL;
1197 bool WatcherThread::_startable = false;
1198 volatile bool WatcherThread::_should_terminate = false;
1199
1200 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1201 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1202 if (os::create_thread(this, os::watcher_thread)) {
1203 _watcher_thread = this;
1204
1205 // WatcherThread needs GCLAB for cases when it writes to Java heap,
1206 // and needs the space to evacuate. Have to initialize here, because
1207 // WatcherThread is initialized before the Universe.
1208 if (UseShenandoahGC && UseTLAB) {
1209 gclab().initialize(true);
1210 }
1211
1212 // Set the watcher thread to the highest OS priority which should not be
1213 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1214 // is created. The only normal thread using this priority is the reference
1215 // handler thread, which runs for very short intervals only.
1216 // If the VMThread's priority is not lower than the WatcherThread profiling
1217 // will be inaccurate.
1218 os::set_priority(this, MaxPriority);
1219 if (!DisableStartThread) {
1220 os::start_thread(this);
1221 }
1222 }
1223 }
1224
1225 int WatcherThread::sleep() const {
1226 // The WatcherThread does not participate in the safepoint protocol
1227 // for the PeriodicTask_lock because it is not a JavaThread.
1228 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1229
1230 if (_should_terminate) {
1231 // check for termination before we do any housekeeping or wait
1232 return 0; // we did not sleep.
1233 }
1234
1235 // remaining will be zero if there are no tasks,
1236 // causing the WatcherThread to sleep until a task is
1237 // enrolled
1238 int remaining = PeriodicTask::time_to_wait();
1239 int time_slept = 0;
1240
1241 // we expect this to timeout - we only ever get unparked when
1242 // we should terminate or when a new task has been enrolled
1243 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1244
1245 jlong time_before_loop = os::javaTimeNanos();
1246
1247 while (true) {
1248 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1249 remaining);
1250 jlong now = os::javaTimeNanos();
1251
1252 if (remaining == 0) {
1253 // if we didn't have any tasks we could have waited for a long time
1254 // consider the time_slept zero and reset time_before_loop
1255 time_slept = 0;
1256 time_before_loop = now;
1257 } else {
1258 // need to recalculate since we might have new tasks in _tasks
1259 time_slept = (int) ((now - time_before_loop) / 1000000);
1260 }
1261
1262 // Change to task list or spurious wakeup of some kind
1263 if (timedout || _should_terminate) {
1264 break;
1265 }
1266
1267 remaining = PeriodicTask::time_to_wait();
1268 if (remaining == 0) {
1269 // Last task was just disenrolled so loop around and wait until
1270 // another task gets enrolled
1271 continue;
1272 }
1273
1274 remaining -= time_slept;
1275 if (remaining <= 0) {
1276 break;
1277 }
1278 }
1279
1280 return time_slept;
1281 }
1282
1283 void WatcherThread::run() {
1284 assert(this == watcher_thread(), "just checking");
1285
1286 this->record_stack_base_and_size();
1287 this->set_native_thread_name(this->name());
1288 this->set_active_handles(JNIHandleBlock::allocate_block());
1289 while (true) {
1290 assert(watcher_thread() == Thread::current(), "thread consistency check");
1291 assert(watcher_thread() == this, "thread consistency check");
1292
1293 // Calculate how long it'll be until the next PeriodicTask work
1294 // should be done, and sleep that amount of time.
1295 int time_waited = sleep();
1296
1297 if (is_error_reported()) {
1298 // A fatal error has happened, the error handler(VMError::report_and_die)
1299 // should abort JVM after creating an error log file. However in some
1300 // rare cases, the error handler itself might deadlock. Here we try to
1301 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1302 //
1303 // This code is in WatcherThread because WatcherThread wakes up
1304 // periodically so the fatal error handler doesn't need to do anything;
1305 // also because the WatcherThread is less likely to crash than other
1306 // threads.
1307
1308 for (;;) {
1309 if (!ShowMessageBoxOnError
1310 && (OnError == NULL || OnError[0] == '\0')
1311 && Arguments::abort_hook() == NULL) {
1312 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1313 fdStream err(defaultStream::output_fd());
1314 err.print_raw_cr("# [ timer expired, abort... ]");
1315 // skip atexit/vm_exit/vm_abort hooks
1316 os::die();
1317 }
1318
1319 // Wake up 5 seconds later, the fatal handler may reset OnError or
1320 // ShowMessageBoxOnError when it is ready to abort.
1321 os::sleep(this, 5 * 1000, false);
1322 }
1323 }
1324
1325 if (_should_terminate) {
1326 // check for termination before posting the next tick
1327 break;
1328 }
1329
1330 PeriodicTask::real_time_tick(time_waited);
1331 }
1332
1333 // Signal that it is terminated
1334 {
1335 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1336 _watcher_thread = NULL;
1337 Terminator_lock->notify();
1338 }
1339 }
1340
1341 void WatcherThread::start() {
1342 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1343
1344 if (watcher_thread() == NULL && _startable) {
1345 _should_terminate = false;
1346 // Create the single instance of WatcherThread
1347 new WatcherThread();
1348 }
1349 }
1350
1351 void WatcherThread::make_startable() {
1352 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1353 _startable = true;
1354 }
1355
1356 void WatcherThread::stop() {
1357 {
1358 // Follow normal safepoint aware lock enter protocol since the
1359 // WatcherThread is stopped by another JavaThread.
1360 MutexLocker ml(PeriodicTask_lock);
1361 _should_terminate = true;
1362
1363 WatcherThread* watcher = watcher_thread();
1364 if (watcher != NULL) {
1365 // unpark the WatcherThread so it can see that it should terminate
1366 watcher->unpark();
1367 }
1368 }
1369
1370 MutexLocker mu(Terminator_lock);
1371
1372 while (watcher_thread() != NULL) {
1373 // This wait should make safepoint checks, wait without a timeout,
1374 // and wait as a suspend-equivalent condition.
1375 //
1376 // Note: If the FlatProfiler is running, then this thread is waiting
1377 // for the WatcherThread to terminate and the WatcherThread, via the
1378 // FlatProfiler task, is waiting for the external suspend request on
1379 // this thread to complete. wait_for_ext_suspend_completion() will
1380 // eventually timeout, but that takes time. Making this wait a
1381 // suspend-equivalent condition solves that timeout problem.
1382 //
1383 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1384 Mutex::_as_suspend_equivalent_flag);
1385 }
1386 }
1387
1388 void WatcherThread::unpark() {
1389 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1390 PeriodicTask_lock->notify();
1391 }
1392
1393 void WatcherThread::print_on(outputStream* st) const {
1394 st->print("\"%s\" ", name());
1395 Thread::print_on(st);
1396 st->cr();
1397 }
1398
1399 // ======= JavaThread ========
1400
1401 #if INCLUDE_JVMCI
1402
1403 jlong* JavaThread::_jvmci_old_thread_counters;
1404
1405 bool jvmci_counters_include(JavaThread* thread) {
1406 oop threadObj = thread->threadObj();
1407 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1408 }
1409
1410 void JavaThread::collect_counters(typeArrayOop array) {
1411 if (JVMCICounterSize > 0) {
1412 MutexLocker tl(Threads_lock);
1413 for (int i = 0; i < array->length(); i++) {
1414 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1415 }
1416 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1417 if (jvmci_counters_include(tp)) {
1418 for (int i = 0; i < array->length(); i++) {
1419 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1420 }
1421 }
1422 }
1423 }
1424 }
1425
1426 #endif // INCLUDE_JVMCI
1427
1428 // A JavaThread is a normal Java thread
1429
1430 void JavaThread::initialize() {
1431 // Initialize fields
1432
1433 set_saved_exception_pc(NULL);
1434 set_threadObj(NULL);
1435 _anchor.clear();
1436 set_entry_point(NULL);
1437 set_jni_functions(jni_functions());
1438 set_callee_target(NULL);
1439 set_vm_result(NULL);
1440 set_vm_result_2(NULL);
1441 set_vframe_array_head(NULL);
1442 set_vframe_array_last(NULL);
1443 set_deferred_locals(NULL);
1444 set_deopt_mark(NULL);
1445 set_deopt_compiled_method(NULL);
1446 clear_must_deopt_id();
1447 set_monitor_chunks(NULL);
1448 set_next(NULL);
1449 set_thread_state(_thread_new);
1450 _terminated = _not_terminated;
1451 _privileged_stack_top = NULL;
1452 _array_for_gc = NULL;
1453 _suspend_equivalent = false;
1454 _in_deopt_handler = 0;
1455 _doing_unsafe_access = false;
1456 _stack_guard_state = stack_guard_unused;
1457 #if INCLUDE_JVMCI
1458 _pending_monitorenter = false;
1459 _pending_deoptimization = -1;
1460 _pending_failed_speculation = NULL;
1461 _pending_transfer_to_interpreter = false;
1462 _adjusting_comp_level = false;
1463 _jvmci._alternate_call_target = NULL;
1464 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1465 if (JVMCICounterSize > 0) {
1466 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1467 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1468 } else {
1469 _jvmci_counters = NULL;
1470 }
1471 #endif // INCLUDE_JVMCI
1472 _reserved_stack_activation = NULL; // stack base not known yet
1473 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1474 _exception_pc = 0;
1475 _exception_handler_pc = 0;
1476 _is_method_handle_return = 0;
1477 _jvmti_thread_state= NULL;
1478 _should_post_on_exceptions_flag = JNI_FALSE;
1479 _jvmti_get_loaded_classes_closure = NULL;
1480 _interp_only_mode = 0;
1481 _special_runtime_exit_condition = _no_async_condition;
1482 _pending_async_exception = NULL;
1483 _thread_stat = NULL;
1484 _thread_stat = new ThreadStatistics();
1485 _blocked_on_compilation = false;
1486 _jni_active_critical = 0;
1487 _pending_jni_exception_check_fn = NULL;
1488 _do_not_unlock_if_synchronized = false;
1489 _cached_monitor_info = NULL;
1490 _parker = Parker::Allocate(this);
1491
1492 #ifndef PRODUCT
1493 _jmp_ring_index = 0;
1494 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1495 record_jump(NULL, NULL, NULL, 0);
1496 }
1497 #endif // PRODUCT
1498
1499 set_thread_profiler(NULL);
1500 if (FlatProfiler::is_active()) {
1501 // This is where we would decide to either give each thread it's own profiler
1502 // or use one global one from FlatProfiler,
1503 // or up to some count of the number of profiled threads, etc.
1504 ThreadProfiler* pp = new ThreadProfiler();
1505 pp->engage();
1506 set_thread_profiler(pp);
1507 }
1508
1509 // Setup safepoint state info for this thread
1510 ThreadSafepointState::create(this);
1511
1512 debug_only(_java_call_counter = 0);
1513
1514 // JVMTI PopFrame support
1515 _popframe_condition = popframe_inactive;
1516 _popframe_preserved_args = NULL;
1517 _popframe_preserved_args_size = 0;
1518 _frames_to_pop_failed_realloc = 0;
1519
1520 pd_initialize();
1521 }
1522
1523 #if INCLUDE_ALL_GCS
1524 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1525 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1526 bool JavaThread::_evacuation_in_progress_global = false;
1527 #endif // INCLUDE_ALL_GCS
1528
1529 JavaThread::JavaThread(bool is_attaching_via_jni) :
1530 Thread()
1531 #if INCLUDE_ALL_GCS
1532 , _satb_mark_queue(&_satb_mark_queue_set),
1533 _dirty_card_queue(&_dirty_card_queue_set),
1534 _evacuation_in_progress(_evacuation_in_progress_global)
1535 #endif // INCLUDE_ALL_GCS
1536 {
1537 initialize();
1538 if (is_attaching_via_jni) {
1539 _jni_attach_state = _attaching_via_jni;
1540 } else {
1541 _jni_attach_state = _not_attaching_via_jni;
1542 }
1543 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1544 }
1545
1546 bool JavaThread::reguard_stack(address cur_sp) {
1547 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1548 && _stack_guard_state != stack_guard_reserved_disabled) {
1549 return true; // Stack already guarded or guard pages not needed.
1550 }
1551
1552 if (register_stack_overflow()) {
1553 // For those architectures which have separate register and
1554 // memory stacks, we must check the register stack to see if
1555 // it has overflowed.
1556 return false;
1557 }
1558
1559 // Java code never executes within the yellow zone: the latter is only
1560 // there to provoke an exception during stack banging. If java code
1561 // is executing there, either StackShadowPages should be larger, or
1562 // some exception code in c1, c2 or the interpreter isn't unwinding
1563 // when it should.
1564 guarantee(cur_sp > stack_reserved_zone_base(),
1565 "not enough space to reguard - increase StackShadowPages");
1566 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1567 enable_stack_yellow_reserved_zone();
1568 if (reserved_stack_activation() != stack_base()) {
1569 set_reserved_stack_activation(stack_base());
1570 }
1571 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1572 set_reserved_stack_activation(stack_base());
1573 enable_stack_reserved_zone();
1574 }
1575 return true;
1576 }
1577
1578 bool JavaThread::reguard_stack(void) {
1579 return reguard_stack(os::current_stack_pointer());
1580 }
1581
1582
1583 void JavaThread::block_if_vm_exited() {
1584 if (_terminated == _vm_exited) {
1585 // _vm_exited is set at safepoint, and Threads_lock is never released
1586 // we will block here forever
1587 Threads_lock->lock_without_safepoint_check();
1588 ShouldNotReachHere();
1589 }
1590 }
1591
1592
1593 // Remove this ifdef when C1 is ported to the compiler interface.
1594 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1595 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1596
1597 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1598 Thread()
1599 #if INCLUDE_ALL_GCS
1600 , _satb_mark_queue(&_satb_mark_queue_set),
1601 _dirty_card_queue(&_dirty_card_queue_set),
1602 _evacuation_in_progress(_evacuation_in_progress_global)
1603 #endif // INCLUDE_ALL_GCS
1604 {
1605 initialize();
1606 _jni_attach_state = _not_attaching_via_jni;
1607 set_entry_point(entry_point);
1608 // Create the native thread itself.
1609 // %note runtime_23
1610 os::ThreadType thr_type = os::java_thread;
1611 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1612 os::java_thread;
1613 os::create_thread(this, thr_type, stack_sz);
1614 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1615 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1616 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1617 // the exception consists of creating the exception object & initializing it, initialization
1618 // will leave the VM via a JavaCall and then all locks must be unlocked).
1619 //
1620 // The thread is still suspended when we reach here. Thread must be explicit started
1621 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1622 // by calling Threads:add. The reason why this is not done here, is because the thread
1623 // object must be fully initialized (take a look at JVM_Start)
1624 }
1625
1626 JavaThread::~JavaThread() {
1627
1628 // JSR166 -- return the parker to the free list
1629 Parker::Release(_parker);
1630 _parker = NULL;
1631
1632 // Free any remaining previous UnrollBlock
1633 vframeArray* old_array = vframe_array_last();
1634
1635 if (old_array != NULL) {
1636 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1637 old_array->set_unroll_block(NULL);
1638 delete old_info;
1639 delete old_array;
1640 }
1641
1642 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1643 if (deferred != NULL) {
1644 // This can only happen if thread is destroyed before deoptimization occurs.
1645 assert(deferred->length() != 0, "empty array!");
1646 do {
1647 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1648 deferred->remove_at(0);
1649 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1650 delete dlv;
1651 } while (deferred->length() != 0);
1652 delete deferred;
1653 }
1654
1655 // All Java related clean up happens in exit
1656 ThreadSafepointState::destroy(this);
1657 if (_thread_profiler != NULL) delete _thread_profiler;
1658 if (_thread_stat != NULL) delete _thread_stat;
1659
1660 #if INCLUDE_JVMCI
1661 if (JVMCICounterSize > 0) {
1662 if (jvmci_counters_include(this)) {
1663 for (int i = 0; i < JVMCICounterSize; i++) {
1664 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1665 }
1666 }
1667 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1668 }
1669 #endif // INCLUDE_JVMCI
1670 }
1671
1672
1673 // The first routine called by a new Java thread
1674 void JavaThread::run() {
1675 // initialize thread-local alloc buffer related fields
1676 this->initialize_tlab();
1677
1678 // used to test validity of stack trace backs
1679 this->record_base_of_stack_pointer();
1680
1681 // Record real stack base and size.
1682 this->record_stack_base_and_size();
1683
1684 this->create_stack_guard_pages();
1685
1686 this->cache_global_variables();
1687
1688 // Thread is now sufficient initialized to be handled by the safepoint code as being
1689 // in the VM. Change thread state from _thread_new to _thread_in_vm
1690 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1691
1692 assert(JavaThread::current() == this, "sanity check");
1693 assert(!Thread::current()->owns_locks(), "sanity check");
1694
1695 DTRACE_THREAD_PROBE(start, this);
1696
1697 // This operation might block. We call that after all safepoint checks for a new thread has
1698 // been completed.
1699 this->set_active_handles(JNIHandleBlock::allocate_block());
1700
1701 if (JvmtiExport::should_post_thread_life()) {
1702 JvmtiExport::post_thread_start(this);
1703 }
1704
1705 EventThreadStart event;
1706 if (event.should_commit()) {
1707 event.set_thread(THREAD_TRACE_ID(this));
1708 event.commit();
1709 }
1710
1711 // We call another function to do the rest so we are sure that the stack addresses used
1712 // from there will be lower than the stack base just computed
1713 thread_main_inner();
1714
1715 // Note, thread is no longer valid at this point!
1716 }
1717
1718
1719 void JavaThread::thread_main_inner() {
1720 assert(JavaThread::current() == this, "sanity check");
1721 assert(this->threadObj() != NULL, "just checking");
1722
1723 // Execute thread entry point unless this thread has a pending exception
1724 // or has been stopped before starting.
1725 // Note: Due to JVM_StopThread we can have pending exceptions already!
1726 if (!this->has_pending_exception() &&
1727 !java_lang_Thread::is_stillborn(this->threadObj())) {
1728 {
1729 ResourceMark rm(this);
1730 this->set_native_thread_name(this->get_thread_name());
1731 }
1732 HandleMark hm(this);
1733 this->entry_point()(this, this);
1734 }
1735
1736 DTRACE_THREAD_PROBE(stop, this);
1737
1738 this->exit(false);
1739 delete this;
1740 }
1741
1742
1743 static void ensure_join(JavaThread* thread) {
1744 // We do not need to grap the Threads_lock, since we are operating on ourself.
1745 Handle threadObj(thread, thread->threadObj());
1746 assert(threadObj.not_null(), "java thread object must exist");
1747 ObjectLocker lock(threadObj, thread);
1748 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1749 thread->clear_pending_exception();
1750 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1751 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1752 // Clear the native thread instance - this makes isAlive return false and allows the join()
1753 // to complete once we've done the notify_all below
1754 java_lang_Thread::set_thread(threadObj(), NULL);
1755 lock.notify_all(thread);
1756 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1757 thread->clear_pending_exception();
1758 }
1759
1760
1761 // For any new cleanup additions, please check to see if they need to be applied to
1762 // cleanup_failed_attach_current_thread as well.
1763 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1764 assert(this == JavaThread::current(), "thread consistency check");
1765
1766 HandleMark hm(this);
1767 Handle uncaught_exception(this, this->pending_exception());
1768 this->clear_pending_exception();
1769 Handle threadObj(this, this->threadObj());
1770 assert(threadObj.not_null(), "Java thread object should be created");
1771
1772 if (get_thread_profiler() != NULL) {
1773 get_thread_profiler()->disengage();
1774 ResourceMark rm;
1775 get_thread_profiler()->print(get_thread_name());
1776 }
1777
1778
1779 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1780 {
1781 EXCEPTION_MARK;
1782
1783 CLEAR_PENDING_EXCEPTION;
1784 }
1785 if (!destroy_vm) {
1786 if (uncaught_exception.not_null()) {
1787 EXCEPTION_MARK;
1788 // Call method Thread.dispatchUncaughtException().
1789 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1790 JavaValue result(T_VOID);
1791 JavaCalls::call_virtual(&result,
1792 threadObj, thread_klass,
1793 vmSymbols::dispatchUncaughtException_name(),
1794 vmSymbols::throwable_void_signature(),
1795 uncaught_exception,
1796 THREAD);
1797 if (HAS_PENDING_EXCEPTION) {
1798 ResourceMark rm(this);
1799 jio_fprintf(defaultStream::error_stream(),
1800 "\nException: %s thrown from the UncaughtExceptionHandler"
1801 " in thread \"%s\"\n",
1802 pending_exception()->klass()->external_name(),
1803 get_thread_name());
1804 CLEAR_PENDING_EXCEPTION;
1805 }
1806 }
1807
1808 // Called before the java thread exit since we want to read info
1809 // from java_lang_Thread object
1810 EventThreadEnd event;
1811 if (event.should_commit()) {
1812 event.set_thread(THREAD_TRACE_ID(this));
1813 event.commit();
1814 }
1815
1816 // Call after last event on thread
1817 EVENT_THREAD_EXIT(this);
1818
1819 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1820 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1821 // is deprecated anyhow.
1822 if (!is_Compiler_thread()) {
1823 int count = 3;
1824 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1825 EXCEPTION_MARK;
1826 JavaValue result(T_VOID);
1827 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1828 JavaCalls::call_virtual(&result,
1829 threadObj, thread_klass,
1830 vmSymbols::exit_method_name(),
1831 vmSymbols::void_method_signature(),
1832 THREAD);
1833 CLEAR_PENDING_EXCEPTION;
1834 }
1835 }
1836 // notify JVMTI
1837 if (JvmtiExport::should_post_thread_life()) {
1838 JvmtiExport::post_thread_end(this);
1839 }
1840
1841 // We have notified the agents that we are exiting, before we go on,
1842 // we must check for a pending external suspend request and honor it
1843 // in order to not surprise the thread that made the suspend request.
1844 while (true) {
1845 {
1846 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1847 if (!is_external_suspend()) {
1848 set_terminated(_thread_exiting);
1849 ThreadService::current_thread_exiting(this);
1850 break;
1851 }
1852 // Implied else:
1853 // Things get a little tricky here. We have a pending external
1854 // suspend request, but we are holding the SR_lock so we
1855 // can't just self-suspend. So we temporarily drop the lock
1856 // and then self-suspend.
1857 }
1858
1859 ThreadBlockInVM tbivm(this);
1860 java_suspend_self();
1861
1862 // We're done with this suspend request, but we have to loop around
1863 // and check again. Eventually we will get SR_lock without a pending
1864 // external suspend request and will be able to mark ourselves as
1865 // exiting.
1866 }
1867 // no more external suspends are allowed at this point
1868 } else {
1869 // before_exit() has already posted JVMTI THREAD_END events
1870 }
1871
1872 // Notify waiters on thread object. This has to be done after exit() is called
1873 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1874 // group should have the destroyed bit set before waiters are notified).
1875 ensure_join(this);
1876 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1877
1878 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1879 // held by this thread must be released. The spec does not distinguish
1880 // between JNI-acquired and regular Java monitors. We can only see
1881 // regular Java monitors here if monitor enter-exit matching is broken.
1882 //
1883 // Optionally release any monitors for regular JavaThread exits. This
1884 // is provided as a work around for any bugs in monitor enter-exit
1885 // matching. This can be expensive so it is not enabled by default.
1886 //
1887 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1888 // ObjectSynchronizer::release_monitors_owned_by_thread().
1889 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1890 // Sanity check even though JNI DetachCurrentThread() would have
1891 // returned JNI_ERR if there was a Java frame. JavaThread exit
1892 // should be done executing Java code by the time we get here.
1893 assert(!this->has_last_Java_frame(),
1894 "should not have a Java frame when detaching or exiting");
1895 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1896 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1897 }
1898
1899 // These things needs to be done while we are still a Java Thread. Make sure that thread
1900 // is in a consistent state, in case GC happens
1901 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1902
1903 if (active_handles() != NULL) {
1904 JNIHandleBlock* block = active_handles();
1905 set_active_handles(NULL);
1906 JNIHandleBlock::release_block(block);
1907 }
1908
1909 if (free_handle_block() != NULL) {
1910 JNIHandleBlock* block = free_handle_block();
1911 set_free_handle_block(NULL);
1912 JNIHandleBlock::release_block(block);
1913 }
1914
1915 // These have to be removed while this is still a valid thread.
1916 remove_stack_guard_pages();
1917
1918 if (UseTLAB) {
1919 tlab().make_parsable(true); // retire TLAB
1920 }
1921
1922 if (JvmtiEnv::environments_might_exist()) {
1923 JvmtiExport::cleanup_thread(this);
1924 }
1925
1926 // We must flush any deferred card marks before removing a thread from
1927 // the list of active threads.
1928 Universe::heap()->flush_deferred_store_barrier(this);
1929 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1930
1931 #if INCLUDE_ALL_GCS
1932 // We must flush the G1-related buffers before removing a thread
1933 // from the list of active threads. We must do this after any deferred
1934 // card marks have been flushed (above) so that any entries that are
1935 // added to the thread's dirty card queue as a result are not lost.
1936 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
1937 flush_barrier_queues();
1938 }
1939 if (UseShenandoahGC && UseTLAB) {
1940 gclab().make_parsable(true);
1941 }
1942 #endif // INCLUDE_ALL_GCS
1943
1944 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1945 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1946 os::current_thread_id());
1947
1948 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1949 Threads::remove(this);
1950 }
1951
1952 #if INCLUDE_ALL_GCS
1953 // Flush G1-related queues.
1954 void JavaThread::flush_barrier_queues() {
1955 satb_mark_queue().flush();
1956 dirty_card_queue().flush();
1957 }
1958
1959 void JavaThread::initialize_queues() {
1960 assert(!SafepointSynchronize::is_at_safepoint(),
1961 "we should not be at a safepoint");
1962
1963 SATBMarkQueue& satb_queue = satb_mark_queue();
1964 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1965 // The SATB queue should have been constructed with its active
1966 // field set to false.
1967 assert(!satb_queue.is_active(), "SATB queue should not be active");
1968 assert(satb_queue.is_empty(), "SATB queue should be empty");
1969 // If we are creating the thread during a marking cycle, we should
1970 // set the active field of the SATB queue to true.
1971 if (satb_queue_set.is_active()) {
1972 satb_queue.set_active(true);
1973 }
1974
1975 DirtyCardQueue& dirty_queue = dirty_card_queue();
1976 // The dirty card queue should have been constructed with its
1977 // active field set to true.
1978 assert(dirty_queue.is_active(), "dirty card queue should be active");
1979
1980 _evacuation_in_progress = _evacuation_in_progress_global;
1981 }
1982
1983 bool JavaThread::evacuation_in_progress() const {
1984 return _evacuation_in_progress;
1985 }
1986
1987 void JavaThread::set_evacuation_in_progress(bool in_prog) {
1988 _evacuation_in_progress = in_prog;
1989 }
1990
1991 void JavaThread::set_evacuation_in_progress_all_threads(bool in_prog) {
1992 assert_locked_or_safepoint(Threads_lock);
1993 _evacuation_in_progress_global = in_prog;
1994 for (JavaThread* t = Threads::first(); t != NULL; t = t->next()) {
1995 t->set_evacuation_in_progress(in_prog);
1996 }
1997 }
1998 #endif // INCLUDE_ALL_GCS
1999
2000 void JavaThread::cleanup_failed_attach_current_thread() {
2001 if (get_thread_profiler() != NULL) {
2002 get_thread_profiler()->disengage();
2003 ResourceMark rm;
2004 get_thread_profiler()->print(get_thread_name());
2005 }
2006
2007 if (active_handles() != NULL) {
2008 JNIHandleBlock* block = active_handles();
2009 set_active_handles(NULL);
2010 JNIHandleBlock::release_block(block);
2011 }
2012
2013 if (free_handle_block() != NULL) {
2014 JNIHandleBlock* block = free_handle_block();
2015 set_free_handle_block(NULL);
2016 JNIHandleBlock::release_block(block);
2017 }
2018
2019 // These have to be removed while this is still a valid thread.
2020 remove_stack_guard_pages();
2021
2022 if (UseTLAB) {
2023 tlab().make_parsable(true); // retire TLAB, if any
2024 }
2025
2026 #if INCLUDE_ALL_GCS
2027 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
2028 flush_barrier_queues();
2029 }
2030 if (UseShenandoahGC && UseTLAB) {
2031 gclab().make_parsable(true);
2032 }
2033 #endif // INCLUDE_ALL_GCS
2034
2035 Threads::remove(this);
2036 delete this;
2037 }
2038
2039
2040
2041
2042 JavaThread* JavaThread::active() {
2043 Thread* thread = Thread::current();
2044 if (thread->is_Java_thread()) {
2045 return (JavaThread*) thread;
2046 } else {
2047 assert(thread->is_VM_thread(), "this must be a vm thread");
2048 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2049 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2050 assert(ret->is_Java_thread(), "must be a Java thread");
2051 return ret;
2052 }
2053 }
2054
2055 bool JavaThread::is_lock_owned(address adr) const {
2056 if (Thread::is_lock_owned(adr)) return true;
2057
2058 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2059 if (chunk->contains(adr)) return true;
2060 }
2061
2062 return false;
2063 }
2064
2065
2066 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2067 chunk->set_next(monitor_chunks());
2068 set_monitor_chunks(chunk);
2069 }
2070
2071 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2072 guarantee(monitor_chunks() != NULL, "must be non empty");
2073 if (monitor_chunks() == chunk) {
2074 set_monitor_chunks(chunk->next());
2075 } else {
2076 MonitorChunk* prev = monitor_chunks();
2077 while (prev->next() != chunk) prev = prev->next();
2078 prev->set_next(chunk->next());
2079 }
2080 }
2081
2082 // JVM support.
2083
2084 // Note: this function shouldn't block if it's called in
2085 // _thread_in_native_trans state (such as from
2086 // check_special_condition_for_native_trans()).
2087 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2088
2089 if (has_last_Java_frame() && has_async_condition()) {
2090 // If we are at a polling page safepoint (not a poll return)
2091 // then we must defer async exception because live registers
2092 // will be clobbered by the exception path. Poll return is
2093 // ok because the call we a returning from already collides
2094 // with exception handling registers and so there is no issue.
2095 // (The exception handling path kills call result registers but
2096 // this is ok since the exception kills the result anyway).
2097
2098 if (is_at_poll_safepoint()) {
2099 // if the code we are returning to has deoptimized we must defer
2100 // the exception otherwise live registers get clobbered on the
2101 // exception path before deoptimization is able to retrieve them.
2102 //
2103 RegisterMap map(this, false);
2104 frame caller_fr = last_frame().sender(&map);
2105 assert(caller_fr.is_compiled_frame(), "what?");
2106 if (caller_fr.is_deoptimized_frame()) {
2107 log_info(exceptions)("deferred async exception at compiled safepoint");
2108 return;
2109 }
2110 }
2111 }
2112
2113 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2114 if (condition == _no_async_condition) {
2115 // Conditions have changed since has_special_runtime_exit_condition()
2116 // was called:
2117 // - if we were here only because of an external suspend request,
2118 // then that was taken care of above (or cancelled) so we are done
2119 // - if we were here because of another async request, then it has
2120 // been cleared between the has_special_runtime_exit_condition()
2121 // and now so again we are done
2122 return;
2123 }
2124
2125 // Check for pending async. exception
2126 if (_pending_async_exception != NULL) {
2127 // Only overwrite an already pending exception, if it is not a threadDeath.
2128 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2129
2130 // We cannot call Exceptions::_throw(...) here because we cannot block
2131 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2132
2133 if (log_is_enabled(Info, exceptions)) {
2134 ResourceMark rm;
2135 outputStream* logstream = Log(exceptions)::info_stream();
2136 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2137 if (has_last_Java_frame()) {
2138 frame f = last_frame();
2139 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2140 }
2141 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2142 }
2143 _pending_async_exception = NULL;
2144 clear_has_async_exception();
2145 }
2146 }
2147
2148 if (check_unsafe_error &&
2149 condition == _async_unsafe_access_error && !has_pending_exception()) {
2150 condition = _no_async_condition; // done
2151 switch (thread_state()) {
2152 case _thread_in_vm: {
2153 JavaThread* THREAD = this;
2154 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2155 }
2156 case _thread_in_native: {
2157 ThreadInVMfromNative tiv(this);
2158 JavaThread* THREAD = this;
2159 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2160 }
2161 case _thread_in_Java: {
2162 ThreadInVMfromJava tiv(this);
2163 JavaThread* THREAD = this;
2164 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2165 }
2166 default:
2167 ShouldNotReachHere();
2168 }
2169 }
2170
2171 assert(condition == _no_async_condition || has_pending_exception() ||
2172 (!check_unsafe_error && condition == _async_unsafe_access_error),
2173 "must have handled the async condition, if no exception");
2174 }
2175
2176 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2177 //
2178 // Check for pending external suspend. Internal suspend requests do
2179 // not use handle_special_runtime_exit_condition().
2180 // If JNIEnv proxies are allowed, don't self-suspend if the target
2181 // thread is not the current thread. In older versions of jdbx, jdbx
2182 // threads could call into the VM with another thread's JNIEnv so we
2183 // can be here operating on behalf of a suspended thread (4432884).
2184 bool do_self_suspend = is_external_suspend_with_lock();
2185 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2186 //
2187 // Because thread is external suspended the safepoint code will count
2188 // thread as at a safepoint. This can be odd because we can be here
2189 // as _thread_in_Java which would normally transition to _thread_blocked
2190 // at a safepoint. We would like to mark the thread as _thread_blocked
2191 // before calling java_suspend_self like all other callers of it but
2192 // we must then observe proper safepoint protocol. (We can't leave
2193 // _thread_blocked with a safepoint in progress). However we can be
2194 // here as _thread_in_native_trans so we can't use a normal transition
2195 // constructor/destructor pair because they assert on that type of
2196 // transition. We could do something like:
2197 //
2198 // JavaThreadState state = thread_state();
2199 // set_thread_state(_thread_in_vm);
2200 // {
2201 // ThreadBlockInVM tbivm(this);
2202 // java_suspend_self()
2203 // }
2204 // set_thread_state(_thread_in_vm_trans);
2205 // if (safepoint) block;
2206 // set_thread_state(state);
2207 //
2208 // but that is pretty messy. Instead we just go with the way the
2209 // code has worked before and note that this is the only path to
2210 // java_suspend_self that doesn't put the thread in _thread_blocked
2211 // mode.
2212
2213 frame_anchor()->make_walkable(this);
2214 java_suspend_self();
2215
2216 // We might be here for reasons in addition to the self-suspend request
2217 // so check for other async requests.
2218 }
2219
2220 if (check_asyncs) {
2221 check_and_handle_async_exceptions();
2222 }
2223 }
2224
2225 void JavaThread::send_thread_stop(oop java_throwable) {
2226 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2227 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2228 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2229
2230 // Do not throw asynchronous exceptions against the compiler thread
2231 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2232 if (!can_call_java()) return;
2233
2234 {
2235 // Actually throw the Throwable against the target Thread - however
2236 // only if there is no thread death exception installed already.
2237 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2238 // If the topmost frame is a runtime stub, then we are calling into
2239 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2240 // must deoptimize the caller before continuing, as the compiled exception handler table
2241 // may not be valid
2242 if (has_last_Java_frame()) {
2243 frame f = last_frame();
2244 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2245 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2246 RegisterMap reg_map(this, UseBiasedLocking);
2247 frame compiled_frame = f.sender(®_map);
2248 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2249 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2250 }
2251 }
2252 }
2253
2254 // Set async. pending exception in thread.
2255 set_pending_async_exception(java_throwable);
2256
2257 if (log_is_enabled(Info, exceptions)) {
2258 ResourceMark rm;
2259 log_info(exceptions)("Pending Async. exception installed of type: %s",
2260 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2261 }
2262 // for AbortVMOnException flag
2263 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2264 }
2265 }
2266
2267
2268 // Interrupt thread so it will wake up from a potential wait()
2269 Thread::interrupt(this);
2270 }
2271
2272 // External suspension mechanism.
2273 //
2274 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2275 // to any VM_locks and it is at a transition
2276 // Self-suspension will happen on the transition out of the vm.
2277 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2278 //
2279 // Guarantees on return:
2280 // + Target thread will not execute any new bytecode (that's why we need to
2281 // force a safepoint)
2282 // + Target thread will not enter any new monitors
2283 //
2284 void JavaThread::java_suspend() {
2285 { MutexLocker mu(Threads_lock);
2286 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2287 return;
2288 }
2289 }
2290
2291 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2292 if (!is_external_suspend()) {
2293 // a racing resume has cancelled us; bail out now
2294 return;
2295 }
2296
2297 // suspend is done
2298 uint32_t debug_bits = 0;
2299 // Warning: is_ext_suspend_completed() may temporarily drop the
2300 // SR_lock to allow the thread to reach a stable thread state if
2301 // it is currently in a transient thread state.
2302 if (is_ext_suspend_completed(false /* !called_by_wait */,
2303 SuspendRetryDelay, &debug_bits)) {
2304 return;
2305 }
2306 }
2307
2308 VM_ForceSafepoint vm_suspend;
2309 VMThread::execute(&vm_suspend);
2310 }
2311
2312 // Part II of external suspension.
2313 // A JavaThread self suspends when it detects a pending external suspend
2314 // request. This is usually on transitions. It is also done in places
2315 // where continuing to the next transition would surprise the caller,
2316 // e.g., monitor entry.
2317 //
2318 // Returns the number of times that the thread self-suspended.
2319 //
2320 // Note: DO NOT call java_suspend_self() when you just want to block current
2321 // thread. java_suspend_self() is the second stage of cooperative
2322 // suspension for external suspend requests and should only be used
2323 // to complete an external suspend request.
2324 //
2325 int JavaThread::java_suspend_self() {
2326 int ret = 0;
2327
2328 // we are in the process of exiting so don't suspend
2329 if (is_exiting()) {
2330 clear_external_suspend();
2331 return ret;
2332 }
2333
2334 assert(_anchor.walkable() ||
2335 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2336 "must have walkable stack");
2337
2338 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2339
2340 assert(!this->is_ext_suspended(),
2341 "a thread trying to self-suspend should not already be suspended");
2342
2343 if (this->is_suspend_equivalent()) {
2344 // If we are self-suspending as a result of the lifting of a
2345 // suspend equivalent condition, then the suspend_equivalent
2346 // flag is not cleared until we set the ext_suspended flag so
2347 // that wait_for_ext_suspend_completion() returns consistent
2348 // results.
2349 this->clear_suspend_equivalent();
2350 }
2351
2352 // A racing resume may have cancelled us before we grabbed SR_lock
2353 // above. Or another external suspend request could be waiting for us
2354 // by the time we return from SR_lock()->wait(). The thread
2355 // that requested the suspension may already be trying to walk our
2356 // stack and if we return now, we can change the stack out from under
2357 // it. This would be a "bad thing (TM)" and cause the stack walker
2358 // to crash. We stay self-suspended until there are no more pending
2359 // external suspend requests.
2360 while (is_external_suspend()) {
2361 ret++;
2362 this->set_ext_suspended();
2363
2364 // _ext_suspended flag is cleared by java_resume()
2365 while (is_ext_suspended()) {
2366 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2367 }
2368 }
2369
2370 return ret;
2371 }
2372
2373 #ifdef ASSERT
2374 // verify the JavaThread has not yet been published in the Threads::list, and
2375 // hence doesn't need protection from concurrent access at this stage
2376 void JavaThread::verify_not_published() {
2377 if (!Threads_lock->owned_by_self()) {
2378 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2379 assert(!Threads::includes(this),
2380 "java thread shouldn't have been published yet!");
2381 } else {
2382 assert(!Threads::includes(this),
2383 "java thread shouldn't have been published yet!");
2384 }
2385 }
2386 #endif
2387
2388 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2389 // progress or when _suspend_flags is non-zero.
2390 // Current thread needs to self-suspend if there is a suspend request and/or
2391 // block if a safepoint is in progress.
2392 // Async exception ISN'T checked.
2393 // Note only the ThreadInVMfromNative transition can call this function
2394 // directly and when thread state is _thread_in_native_trans
2395 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2396 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2397
2398 JavaThread *curJT = JavaThread::current();
2399 bool do_self_suspend = thread->is_external_suspend();
2400
2401 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2402
2403 // If JNIEnv proxies are allowed, don't self-suspend if the target
2404 // thread is not the current thread. In older versions of jdbx, jdbx
2405 // threads could call into the VM with another thread's JNIEnv so we
2406 // can be here operating on behalf of a suspended thread (4432884).
2407 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2408 JavaThreadState state = thread->thread_state();
2409
2410 // We mark this thread_blocked state as a suspend-equivalent so
2411 // that a caller to is_ext_suspend_completed() won't be confused.
2412 // The suspend-equivalent state is cleared by java_suspend_self().
2413 thread->set_suspend_equivalent();
2414
2415 // If the safepoint code sees the _thread_in_native_trans state, it will
2416 // wait until the thread changes to other thread state. There is no
2417 // guarantee on how soon we can obtain the SR_lock and complete the
2418 // self-suspend request. It would be a bad idea to let safepoint wait for
2419 // too long. Temporarily change the state to _thread_blocked to
2420 // let the VM thread know that this thread is ready for GC. The problem
2421 // of changing thread state is that safepoint could happen just after
2422 // java_suspend_self() returns after being resumed, and VM thread will
2423 // see the _thread_blocked state. We must check for safepoint
2424 // after restoring the state and make sure we won't leave while a safepoint
2425 // is in progress.
2426 thread->set_thread_state(_thread_blocked);
2427 thread->java_suspend_self();
2428 thread->set_thread_state(state);
2429 // Make sure new state is seen by VM thread
2430 if (os::is_MP()) {
2431 if (UseMembar) {
2432 // Force a fence between the write above and read below
2433 OrderAccess::fence();
2434 } else {
2435 // Must use this rather than serialization page in particular on Windows
2436 InterfaceSupport::serialize_memory(thread);
2437 }
2438 }
2439 }
2440
2441 if (SafepointSynchronize::do_call_back()) {
2442 // If we are safepointing, then block the caller which may not be
2443 // the same as the target thread (see above).
2444 SafepointSynchronize::block(curJT);
2445 }
2446
2447 if (thread->is_deopt_suspend()) {
2448 thread->clear_deopt_suspend();
2449 RegisterMap map(thread, false);
2450 frame f = thread->last_frame();
2451 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2452 f = f.sender(&map);
2453 }
2454 if (f.id() == thread->must_deopt_id()) {
2455 thread->clear_must_deopt_id();
2456 f.deoptimize(thread);
2457 } else {
2458 fatal("missed deoptimization!");
2459 }
2460 }
2461 }
2462
2463 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2464 // progress or when _suspend_flags is non-zero.
2465 // Current thread needs to self-suspend if there is a suspend request and/or
2466 // block if a safepoint is in progress.
2467 // Also check for pending async exception (not including unsafe access error).
2468 // Note only the native==>VM/Java barriers can call this function and when
2469 // thread state is _thread_in_native_trans.
2470 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2471 check_safepoint_and_suspend_for_native_trans(thread);
2472
2473 if (thread->has_async_exception()) {
2474 // We are in _thread_in_native_trans state, don't handle unsafe
2475 // access error since that may block.
2476 thread->check_and_handle_async_exceptions(false);
2477 }
2478 }
2479
2480 // This is a variant of the normal
2481 // check_special_condition_for_native_trans with slightly different
2482 // semantics for use by critical native wrappers. It does all the
2483 // normal checks but also performs the transition back into
2484 // thread_in_Java state. This is required so that critical natives
2485 // can potentially block and perform a GC if they are the last thread
2486 // exiting the GCLocker.
2487 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2488 check_special_condition_for_native_trans(thread);
2489
2490 // Finish the transition
2491 thread->set_thread_state(_thread_in_Java);
2492
2493 if (thread->do_critical_native_unlock()) {
2494 ThreadInVMfromJavaNoAsyncException tiv(thread);
2495 GCLocker::unlock_critical(thread);
2496 thread->clear_critical_native_unlock();
2497 }
2498 }
2499
2500 // We need to guarantee the Threads_lock here, since resumes are not
2501 // allowed during safepoint synchronization
2502 // Can only resume from an external suspension
2503 void JavaThread::java_resume() {
2504 assert_locked_or_safepoint(Threads_lock);
2505
2506 // Sanity check: thread is gone, has started exiting or the thread
2507 // was not externally suspended.
2508 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2509 return;
2510 }
2511
2512 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2513
2514 clear_external_suspend();
2515
2516 if (is_ext_suspended()) {
2517 clear_ext_suspended();
2518 SR_lock()->notify_all();
2519 }
2520 }
2521
2522 size_t JavaThread::_stack_red_zone_size = 0;
2523 size_t JavaThread::_stack_yellow_zone_size = 0;
2524 size_t JavaThread::_stack_reserved_zone_size = 0;
2525 size_t JavaThread::_stack_shadow_zone_size = 0;
2526
2527 void JavaThread::create_stack_guard_pages() {
2528 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2529 address low_addr = stack_end();
2530 size_t len = stack_guard_zone_size();
2531
2532 int must_commit = os::must_commit_stack_guard_pages();
2533 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2534
2535 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2536 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2537 return;
2538 }
2539
2540 if (os::guard_memory((char *) low_addr, len)) {
2541 _stack_guard_state = stack_guard_enabled;
2542 } else {
2543 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2544 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2545 if (os::uncommit_memory((char *) low_addr, len)) {
2546 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2547 }
2548 return;
2549 }
2550
2551 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2552 PTR_FORMAT "-" PTR_FORMAT ".",
2553 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2554 }
2555
2556 void JavaThread::remove_stack_guard_pages() {
2557 assert(Thread::current() == this, "from different thread");
2558 if (_stack_guard_state == stack_guard_unused) return;
2559 address low_addr = stack_end();
2560 size_t len = stack_guard_zone_size();
2561
2562 if (os::must_commit_stack_guard_pages()) {
2563 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2564 _stack_guard_state = stack_guard_unused;
2565 } else {
2566 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2567 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2568 return;
2569 }
2570 } else {
2571 if (_stack_guard_state == stack_guard_unused) return;
2572 if (os::unguard_memory((char *) low_addr, len)) {
2573 _stack_guard_state = stack_guard_unused;
2574 } else {
2575 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2576 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2577 return;
2578 }
2579 }
2580
2581 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2582 PTR_FORMAT "-" PTR_FORMAT ".",
2583 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2584 }
2585
2586 void JavaThread::enable_stack_reserved_zone() {
2587 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2588 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2589
2590 // The base notation is from the stack's point of view, growing downward.
2591 // We need to adjust it to work correctly with guard_memory()
2592 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2593
2594 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2595 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2596
2597 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2598 _stack_guard_state = stack_guard_enabled;
2599 } else {
2600 warning("Attempt to guard stack reserved zone failed.");
2601 }
2602 enable_register_stack_guard();
2603 }
2604
2605 void JavaThread::disable_stack_reserved_zone() {
2606 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2607 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2608
2609 // Simply return if called for a thread that does not use guard pages.
2610 if (_stack_guard_state == stack_guard_unused) return;
2611
2612 // The base notation is from the stack's point of view, growing downward.
2613 // We need to adjust it to work correctly with guard_memory()
2614 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2615
2616 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2617 _stack_guard_state = stack_guard_reserved_disabled;
2618 } else {
2619 warning("Attempt to unguard stack reserved zone failed.");
2620 }
2621 disable_register_stack_guard();
2622 }
2623
2624 void JavaThread::enable_stack_yellow_reserved_zone() {
2625 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2626 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2627
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 address base = stack_red_zone_base();
2631
2632 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2633 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2634
2635 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2636 _stack_guard_state = stack_guard_enabled;
2637 } else {
2638 warning("Attempt to guard stack yellow zone failed.");
2639 }
2640 enable_register_stack_guard();
2641 }
2642
2643 void JavaThread::disable_stack_yellow_reserved_zone() {
2644 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2645 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2646
2647 // Simply return if called for a thread that does not use guard pages.
2648 if (_stack_guard_state == stack_guard_unused) return;
2649
2650 // The base notation is from the stacks point of view, growing downward.
2651 // We need to adjust it to work correctly with guard_memory()
2652 address base = stack_red_zone_base();
2653
2654 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2655 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2656 } else {
2657 warning("Attempt to unguard stack yellow zone failed.");
2658 }
2659 disable_register_stack_guard();
2660 }
2661
2662 void JavaThread::enable_stack_red_zone() {
2663 // The base notation is from the stacks point of view, growing downward.
2664 // We need to adjust it to work correctly with guard_memory()
2665 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2666 address base = stack_red_zone_base() - stack_red_zone_size();
2667
2668 guarantee(base < stack_base(), "Error calculating stack red zone");
2669 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2670
2671 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2672 warning("Attempt to guard stack red zone failed.");
2673 }
2674 }
2675
2676 void JavaThread::disable_stack_red_zone() {
2677 // The base notation is from the stacks point of view, growing downward.
2678 // We need to adjust it to work correctly with guard_memory()
2679 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2680 address base = stack_red_zone_base() - stack_red_zone_size();
2681 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2682 warning("Attempt to unguard stack red zone failed.");
2683 }
2684 }
2685
2686 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2687 // ignore is there is no stack
2688 if (!has_last_Java_frame()) return;
2689 // traverse the stack frames. Starts from top frame.
2690 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2691 frame* fr = fst.current();
2692 f(fr, fst.register_map());
2693 }
2694 }
2695
2696
2697 #ifndef PRODUCT
2698 // Deoptimization
2699 // Function for testing deoptimization
2700 void JavaThread::deoptimize() {
2701 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2702 StackFrameStream fst(this, UseBiasedLocking);
2703 bool deopt = false; // Dump stack only if a deopt actually happens.
2704 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2705 // Iterate over all frames in the thread and deoptimize
2706 for (; !fst.is_done(); fst.next()) {
2707 if (fst.current()->can_be_deoptimized()) {
2708
2709 if (only_at) {
2710 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2711 // consists of comma or carriage return separated numbers so
2712 // search for the current bci in that string.
2713 address pc = fst.current()->pc();
2714 nmethod* nm = (nmethod*) fst.current()->cb();
2715 ScopeDesc* sd = nm->scope_desc_at(pc);
2716 char buffer[8];
2717 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2718 size_t len = strlen(buffer);
2719 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2720 while (found != NULL) {
2721 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2722 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2723 // Check that the bci found is bracketed by terminators.
2724 break;
2725 }
2726 found = strstr(found + 1, buffer);
2727 }
2728 if (!found) {
2729 continue;
2730 }
2731 }
2732
2733 if (DebugDeoptimization && !deopt) {
2734 deopt = true; // One-time only print before deopt
2735 tty->print_cr("[BEFORE Deoptimization]");
2736 trace_frames();
2737 trace_stack();
2738 }
2739 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2740 }
2741 }
2742
2743 if (DebugDeoptimization && deopt) {
2744 tty->print_cr("[AFTER Deoptimization]");
2745 trace_frames();
2746 }
2747 }
2748
2749
2750 // Make zombies
2751 void JavaThread::make_zombies() {
2752 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2753 if (fst.current()->can_be_deoptimized()) {
2754 // it is a Java nmethod
2755 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2756 nm->make_not_entrant();
2757 }
2758 }
2759 }
2760 #endif // PRODUCT
2761
2762
2763 void JavaThread::deoptimized_wrt_marked_nmethods() {
2764 if (!has_last_Java_frame()) return;
2765 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2766 StackFrameStream fst(this, UseBiasedLocking);
2767 for (; !fst.is_done(); fst.next()) {
2768 if (fst.current()->should_be_deoptimized()) {
2769 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2770 }
2771 }
2772 }
2773
2774
2775 // If the caller is a NamedThread, then remember, in the current scope,
2776 // the given JavaThread in its _processed_thread field.
2777 class RememberProcessedThread: public StackObj {
2778 NamedThread* _cur_thr;
2779 public:
2780 RememberProcessedThread(JavaThread* jthr) {
2781 Thread* thread = Thread::current();
2782 if (thread->is_Named_thread()) {
2783 _cur_thr = (NamedThread *)thread;
2784 _cur_thr->set_processed_thread(jthr);
2785 } else {
2786 _cur_thr = NULL;
2787 }
2788 }
2789
2790 ~RememberProcessedThread() {
2791 if (_cur_thr) {
2792 _cur_thr->set_processed_thread(NULL);
2793 }
2794 }
2795 };
2796
2797 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2798 // Verify that the deferred card marks have been flushed.
2799 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2800
2801 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2802 // since there may be more than one thread using each ThreadProfiler.
2803
2804 // Traverse the GCHandles
2805 Thread::oops_do(f, cf);
2806
2807 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2808
2809 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2810 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2811
2812 if (has_last_Java_frame()) {
2813 // Record JavaThread to GC thread
2814 RememberProcessedThread rpt(this);
2815
2816 // Traverse the privileged stack
2817 if (_privileged_stack_top != NULL) {
2818 _privileged_stack_top->oops_do(f);
2819 }
2820
2821 // traverse the registered growable array
2822 if (_array_for_gc != NULL) {
2823 for (int index = 0; index < _array_for_gc->length(); index++) {
2824 f->do_oop(_array_for_gc->adr_at(index));
2825 }
2826 }
2827
2828 // Traverse the monitor chunks
2829 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2830 chunk->oops_do(f);
2831 }
2832
2833 // Traverse the execution stack
2834 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2835 fst.current()->oops_do(f, cf, fst.register_map());
2836 }
2837 }
2838
2839 // callee_target is never live across a gc point so NULL it here should
2840 // it still contain a methdOop.
2841
2842 set_callee_target(NULL);
2843
2844 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2845 // If we have deferred set_locals there might be oops waiting to be
2846 // written
2847 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2848 if (list != NULL) {
2849 for (int i = 0; i < list->length(); i++) {
2850 list->at(i)->oops_do(f);
2851 }
2852 }
2853
2854 // Traverse instance variables at the end since the GC may be moving things
2855 // around using this function
2856 f->do_oop((oop*) &_threadObj);
2857 f->do_oop((oop*) &_vm_result);
2858 f->do_oop((oop*) &_exception_oop);
2859 f->do_oop((oop*) &_pending_async_exception);
2860
2861 if (jvmti_thread_state() != NULL) {
2862 jvmti_thread_state()->oops_do(f);
2863 }
2864 }
2865
2866 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2867 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2868 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2869
2870 if (has_last_Java_frame()) {
2871 // Traverse the execution stack
2872 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2873 fst.current()->nmethods_do(cf);
2874 }
2875 }
2876 }
2877
2878 void JavaThread::metadata_do(void f(Metadata*)) {
2879 if (has_last_Java_frame()) {
2880 // Traverse the execution stack to call f() on the methods in the stack
2881 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2882 fst.current()->metadata_do(f);
2883 }
2884 } else if (is_Compiler_thread()) {
2885 // need to walk ciMetadata in current compile tasks to keep alive.
2886 CompilerThread* ct = (CompilerThread*)this;
2887 if (ct->env() != NULL) {
2888 ct->env()->metadata_do(f);
2889 }
2890 if (ct->task() != NULL) {
2891 ct->task()->metadata_do(f);
2892 }
2893 }
2894 }
2895
2896 // Printing
2897 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2898 switch (_thread_state) {
2899 case _thread_uninitialized: return "_thread_uninitialized";
2900 case _thread_new: return "_thread_new";
2901 case _thread_new_trans: return "_thread_new_trans";
2902 case _thread_in_native: return "_thread_in_native";
2903 case _thread_in_native_trans: return "_thread_in_native_trans";
2904 case _thread_in_vm: return "_thread_in_vm";
2905 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2906 case _thread_in_Java: return "_thread_in_Java";
2907 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2908 case _thread_blocked: return "_thread_blocked";
2909 case _thread_blocked_trans: return "_thread_blocked_trans";
2910 default: return "unknown thread state";
2911 }
2912 }
2913
2914 #ifndef PRODUCT
2915 void JavaThread::print_thread_state_on(outputStream *st) const {
2916 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2917 };
2918 void JavaThread::print_thread_state() const {
2919 print_thread_state_on(tty);
2920 }
2921 #endif // PRODUCT
2922
2923 // Called by Threads::print() for VM_PrintThreads operation
2924 void JavaThread::print_on(outputStream *st) const {
2925 st->print_raw("\"");
2926 st->print_raw(get_thread_name());
2927 st->print_raw("\" ");
2928 oop thread_oop = threadObj();
2929 if (thread_oop != NULL) {
2930 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2931 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2932 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2933 }
2934 Thread::print_on(st);
2935 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2936 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2937 if (thread_oop != NULL) {
2938 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2939 }
2940 #ifndef PRODUCT
2941 print_thread_state_on(st);
2942 _safepoint_state->print_on(st);
2943 #endif // PRODUCT
2944 if (is_Compiler_thread()) {
2945 CompilerThread* ct = (CompilerThread*)this;
2946 if (ct->task() != NULL) {
2947 st->print(" Compiling: ");
2948 ct->task()->print(st, NULL, true, false);
2949 } else {
2950 st->print(" No compile task");
2951 }
2952 st->cr();
2953 }
2954 }
2955
2956 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2957 st->print("%s", get_thread_name_string(buf, buflen));
2958 }
2959
2960 // Called by fatal error handler. The difference between this and
2961 // JavaThread::print() is that we can't grab lock or allocate memory.
2962 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2963 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2964 oop thread_obj = threadObj();
2965 if (thread_obj != NULL) {
2966 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2967 }
2968 st->print(" [");
2969 st->print("%s", _get_thread_state_name(_thread_state));
2970 if (osthread()) {
2971 st->print(", id=%d", osthread()->thread_id());
2972 }
2973 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2974 p2i(stack_end()), p2i(stack_base()));
2975 st->print("]");
2976 return;
2977 }
2978
2979 // Verification
2980
2981 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2982
2983 void JavaThread::verify() {
2984 // Verify oops in the thread.
2985 oops_do(&VerifyOopClosure::verify_oop, NULL);
2986
2987 // Verify the stack frames.
2988 frames_do(frame_verify);
2989 }
2990
2991 // CR 6300358 (sub-CR 2137150)
2992 // Most callers of this method assume that it can't return NULL but a
2993 // thread may not have a name whilst it is in the process of attaching to
2994 // the VM - see CR 6412693, and there are places where a JavaThread can be
2995 // seen prior to having it's threadObj set (eg JNI attaching threads and
2996 // if vm exit occurs during initialization). These cases can all be accounted
2997 // for such that this method never returns NULL.
2998 const char* JavaThread::get_thread_name() const {
2999 #ifdef ASSERT
3000 // early safepoints can hit while current thread does not yet have TLS
3001 if (!SafepointSynchronize::is_at_safepoint()) {
3002 Thread *cur = Thread::current();
3003 if (!(cur->is_Java_thread() && cur == this)) {
3004 // Current JavaThreads are allowed to get their own name without
3005 // the Threads_lock.
3006 assert_locked_or_safepoint(Threads_lock);
3007 }
3008 }
3009 #endif // ASSERT
3010 return get_thread_name_string();
3011 }
3012
3013 // Returns a non-NULL representation of this thread's name, or a suitable
3014 // descriptive string if there is no set name
3015 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3016 const char* name_str;
3017 oop thread_obj = threadObj();
3018 if (thread_obj != NULL) {
3019 oop name = java_lang_Thread::name(thread_obj);
3020 if (name != NULL) {
3021 if (buf == NULL) {
3022 name_str = java_lang_String::as_utf8_string(name);
3023 } else {
3024 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3025 }
3026 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3027 name_str = "<no-name - thread is attaching>";
3028 } else {
3029 name_str = Thread::name();
3030 }
3031 } else {
3032 name_str = Thread::name();
3033 }
3034 assert(name_str != NULL, "unexpected NULL thread name");
3035 return name_str;
3036 }
3037
3038
3039 const char* JavaThread::get_threadgroup_name() const {
3040 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3041 oop thread_obj = threadObj();
3042 if (thread_obj != NULL) {
3043 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3044 if (thread_group != NULL) {
3045 // ThreadGroup.name can be null
3046 return java_lang_ThreadGroup::name(thread_group);
3047 }
3048 }
3049 return NULL;
3050 }
3051
3052 const char* JavaThread::get_parent_name() const {
3053 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3054 oop thread_obj = threadObj();
3055 if (thread_obj != NULL) {
3056 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3057 if (thread_group != NULL) {
3058 oop parent = java_lang_ThreadGroup::parent(thread_group);
3059 if (parent != NULL) {
3060 // ThreadGroup.name can be null
3061 return java_lang_ThreadGroup::name(parent);
3062 }
3063 }
3064 }
3065 return NULL;
3066 }
3067
3068 ThreadPriority JavaThread::java_priority() const {
3069 oop thr_oop = threadObj();
3070 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3071 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3072 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3073 return priority;
3074 }
3075
3076 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3077
3078 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3079 // Link Java Thread object <-> C++ Thread
3080
3081 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3082 // and put it into a new Handle. The Handle "thread_oop" can then
3083 // be used to pass the C++ thread object to other methods.
3084
3085 // Set the Java level thread object (jthread) field of the
3086 // new thread (a JavaThread *) to C++ thread object using the
3087 // "thread_oop" handle.
3088
3089 // Set the thread field (a JavaThread *) of the
3090 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3091
3092 Handle thread_oop(Thread::current(),
3093 JNIHandles::resolve_non_null(jni_thread));
3094 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3095 "must be initialized");
3096 set_threadObj(thread_oop());
3097 java_lang_Thread::set_thread(thread_oop(), this);
3098
3099 if (prio == NoPriority) {
3100 prio = java_lang_Thread::priority(thread_oop());
3101 assert(prio != NoPriority, "A valid priority should be present");
3102 }
3103
3104 // Push the Java priority down to the native thread; needs Threads_lock
3105 Thread::set_priority(this, prio);
3106
3107 prepare_ext();
3108
3109 // Add the new thread to the Threads list and set it in motion.
3110 // We must have threads lock in order to call Threads::add.
3111 // It is crucial that we do not block before the thread is
3112 // added to the Threads list for if a GC happens, then the java_thread oop
3113 // will not be visited by GC.
3114 Threads::add(this);
3115 }
3116
3117 oop JavaThread::current_park_blocker() {
3118 // Support for JSR-166 locks
3119 oop thread_oop = threadObj();
3120 if (thread_oop != NULL &&
3121 JDK_Version::current().supports_thread_park_blocker()) {
3122 return java_lang_Thread::park_blocker(thread_oop);
3123 }
3124 return NULL;
3125 }
3126
3127
3128 void JavaThread::print_stack_on(outputStream* st) {
3129 if (!has_last_Java_frame()) return;
3130 ResourceMark rm;
3131 HandleMark hm;
3132
3133 RegisterMap reg_map(this);
3134 vframe* start_vf = last_java_vframe(®_map);
3135 int count = 0;
3136 for (vframe* f = start_vf; f; f = f->sender()) {
3137 if (f->is_java_frame()) {
3138 javaVFrame* jvf = javaVFrame::cast(f);
3139 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3140
3141 // Print out lock information
3142 if (JavaMonitorsInStackTrace) {
3143 jvf->print_lock_info_on(st, count);
3144 }
3145 } else {
3146 // Ignore non-Java frames
3147 }
3148
3149 // Bail-out case for too deep stacks
3150 count++;
3151 if (MaxJavaStackTraceDepth == count) return;
3152 }
3153 }
3154
3155
3156 // JVMTI PopFrame support
3157 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3158 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3159 if (in_bytes(size_in_bytes) != 0) {
3160 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3161 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3162 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3163 }
3164 }
3165
3166 void* JavaThread::popframe_preserved_args() {
3167 return _popframe_preserved_args;
3168 }
3169
3170 ByteSize JavaThread::popframe_preserved_args_size() {
3171 return in_ByteSize(_popframe_preserved_args_size);
3172 }
3173
3174 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3175 int sz = in_bytes(popframe_preserved_args_size());
3176 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3177 return in_WordSize(sz / wordSize);
3178 }
3179
3180 void JavaThread::popframe_free_preserved_args() {
3181 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3182 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3183 _popframe_preserved_args = NULL;
3184 _popframe_preserved_args_size = 0;
3185 }
3186
3187 #ifndef PRODUCT
3188
3189 void JavaThread::trace_frames() {
3190 tty->print_cr("[Describe stack]");
3191 int frame_no = 1;
3192 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3193 tty->print(" %d. ", frame_no++);
3194 fst.current()->print_value_on(tty, this);
3195 tty->cr();
3196 }
3197 }
3198
3199 class PrintAndVerifyOopClosure: public OopClosure {
3200 protected:
3201 template <class T> inline void do_oop_work(T* p) {
3202 oop obj = oopDesc::load_decode_heap_oop(p);
3203 if (obj == NULL) return;
3204 tty->print(INTPTR_FORMAT ": ", p2i(p));
3205 if (obj->is_oop_or_null()) {
3206 if (obj->is_objArray()) {
3207 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3208 } else {
3209 obj->print();
3210 }
3211 } else {
3212 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3213 }
3214 tty->cr();
3215 }
3216 public:
3217 virtual void do_oop(oop* p) { do_oop_work(p); }
3218 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3219 };
3220
3221
3222 static void oops_print(frame* f, const RegisterMap *map) {
3223 PrintAndVerifyOopClosure print;
3224 f->print_value();
3225 f->oops_do(&print, NULL, (RegisterMap*)map);
3226 }
3227
3228 // Print our all the locations that contain oops and whether they are
3229 // valid or not. This useful when trying to find the oldest frame
3230 // where an oop has gone bad since the frame walk is from youngest to
3231 // oldest.
3232 void JavaThread::trace_oops() {
3233 tty->print_cr("[Trace oops]");
3234 frames_do(oops_print);
3235 }
3236
3237
3238 #ifdef ASSERT
3239 // Print or validate the layout of stack frames
3240 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3241 ResourceMark rm;
3242 PRESERVE_EXCEPTION_MARK;
3243 FrameValues values;
3244 int frame_no = 0;
3245 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3246 fst.current()->describe(values, ++frame_no);
3247 if (depth == frame_no) break;
3248 }
3249 if (validate_only) {
3250 values.validate();
3251 } else {
3252 tty->print_cr("[Describe stack layout]");
3253 values.print(this);
3254 }
3255 }
3256 #endif
3257
3258 void JavaThread::trace_stack_from(vframe* start_vf) {
3259 ResourceMark rm;
3260 int vframe_no = 1;
3261 for (vframe* f = start_vf; f; f = f->sender()) {
3262 if (f->is_java_frame()) {
3263 javaVFrame::cast(f)->print_activation(vframe_no++);
3264 } else {
3265 f->print();
3266 }
3267 if (vframe_no > StackPrintLimit) {
3268 tty->print_cr("...<more frames>...");
3269 return;
3270 }
3271 }
3272 }
3273
3274
3275 void JavaThread::trace_stack() {
3276 if (!has_last_Java_frame()) return;
3277 ResourceMark rm;
3278 HandleMark hm;
3279 RegisterMap reg_map(this);
3280 trace_stack_from(last_java_vframe(®_map));
3281 }
3282
3283
3284 #endif // PRODUCT
3285
3286
3287 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3288 assert(reg_map != NULL, "a map must be given");
3289 frame f = last_frame();
3290 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3291 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3292 }
3293 return NULL;
3294 }
3295
3296
3297 Klass* JavaThread::security_get_caller_class(int depth) {
3298 vframeStream vfst(this);
3299 vfst.security_get_caller_frame(depth);
3300 if (!vfst.at_end()) {
3301 return vfst.method()->method_holder();
3302 }
3303 return NULL;
3304 }
3305
3306 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3307 assert(thread->is_Compiler_thread(), "must be compiler thread");
3308 CompileBroker::compiler_thread_loop();
3309 }
3310
3311 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3312 NMethodSweeper::sweeper_loop();
3313 }
3314
3315 // Create a CompilerThread
3316 CompilerThread::CompilerThread(CompileQueue* queue,
3317 CompilerCounters* counters)
3318 : JavaThread(&compiler_thread_entry) {
3319 _env = NULL;
3320 _log = NULL;
3321 _task = NULL;
3322 _queue = queue;
3323 _counters = counters;
3324 _buffer_blob = NULL;
3325 _compiler = NULL;
3326
3327 #ifndef PRODUCT
3328 _ideal_graph_printer = NULL;
3329 #endif
3330 }
3331
3332 bool CompilerThread::can_call_java() const {
3333 return _compiler != NULL && _compiler->is_jvmci();
3334 }
3335
3336 // Create sweeper thread
3337 CodeCacheSweeperThread::CodeCacheSweeperThread()
3338 : JavaThread(&sweeper_thread_entry) {
3339 _scanned_compiled_method = NULL;
3340 }
3341
3342 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3343 JavaThread::oops_do(f, cf);
3344 if (_scanned_compiled_method != NULL && cf != NULL) {
3345 // Safepoints can occur when the sweeper is scanning an nmethod so
3346 // process it here to make sure it isn't unloaded in the middle of
3347 // a scan.
3348 cf->do_code_blob(_scanned_compiled_method);
3349 }
3350 }
3351
3352 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3353 JavaThread::nmethods_do(cf);
3354 if (_scanned_compiled_method != NULL && cf != NULL) {
3355 // Safepoints can occur when the sweeper is scanning an nmethod so
3356 // process it here to make sure it isn't unloaded in the middle of
3357 // a scan.
3358 cf->do_code_blob(_scanned_compiled_method);
3359 }
3360 }
3361
3362
3363 // ======= Threads ========
3364
3365 // The Threads class links together all active threads, and provides
3366 // operations over all threads. It is protected by its own Mutex
3367 // lock, which is also used in other contexts to protect thread
3368 // operations from having the thread being operated on from exiting
3369 // and going away unexpectedly (e.g., safepoint synchronization)
3370
3371 JavaThread* Threads::_thread_list = NULL;
3372 int Threads::_number_of_threads = 0;
3373 int Threads::_number_of_non_daemon_threads = 0;
3374 int Threads::_return_code = 0;
3375 int Threads::_thread_claim_parity = 0;
3376 size_t JavaThread::_stack_size_at_create = 0;
3377 #ifdef ASSERT
3378 bool Threads::_vm_complete = false;
3379 #endif
3380
3381 // All JavaThreads
3382 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3383
3384 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3385 void Threads::threads_do(ThreadClosure* tc) {
3386 assert_locked_or_safepoint(Threads_lock);
3387 // ALL_JAVA_THREADS iterates through all JavaThreads
3388 ALL_JAVA_THREADS(p) {
3389 tc->do_thread(p);
3390 }
3391 // Someday we could have a table or list of all non-JavaThreads.
3392 // For now, just manually iterate through them.
3393 tc->do_thread(VMThread::vm_thread());
3394 Universe::heap()->gc_threads_do(tc);
3395 WatcherThread *wt = WatcherThread::watcher_thread();
3396 // Strictly speaking, the following NULL check isn't sufficient to make sure
3397 // the data for WatcherThread is still valid upon being examined. However,
3398 // considering that WatchThread terminates when the VM is on the way to
3399 // exit at safepoint, the chance of the above is extremely small. The right
3400 // way to prevent termination of WatcherThread would be to acquire
3401 // Terminator_lock, but we can't do that without violating the lock rank
3402 // checking in some cases.
3403 if (wt != NULL) {
3404 tc->do_thread(wt);
3405 }
3406
3407 // If CompilerThreads ever become non-JavaThreads, add them here
3408 }
3409
3410 // The system initialization in the library has three phases.
3411 //
3412 // Phase 1: java.lang.System class initialization
3413 // java.lang.System is a primordial class loaded and initialized
3414 // by the VM early during startup. java.lang.System.<clinit>
3415 // only does registerNatives and keeps the rest of the class
3416 // initialization work later until thread initialization completes.
3417 //
3418 // System.initPhase1 initializes the system properties, the static
3419 // fields in, out, and err. Set up java signal handlers, OS-specific
3420 // system settings, and thread group of the main thread.
3421 static void call_initPhase1(TRAPS) {
3422 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3423 instanceKlassHandle klass (THREAD, k);
3424
3425 JavaValue result(T_VOID);
3426 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3427 vmSymbols::void_method_signature(), CHECK);
3428 }
3429
3430 // Phase 2. Module system initialization
3431 // This will initialize the module system. Only java.base classes
3432 // can be loaded until phase 2 completes.
3433 //
3434 // Call System.initPhase2 after the compiler initialization and jsr292
3435 // classes get initialized because module initialization runs a lot of java
3436 // code, that for performance reasons, should be compiled. Also, this will
3437 // enable the startup code to use lambda and other language features in this
3438 // phase and onward.
3439 //
3440 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3441 static void call_initPhase2(TRAPS) {
3442 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime));
3443
3444 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3445 instanceKlassHandle klass (THREAD, k);
3446
3447 JavaValue result(T_INT);
3448 JavaCallArguments args;
3449 args.push_int(DisplayVMOutputToStderr);
3450 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3451 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3452 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3453 if (result.get_jint() != JNI_OK) {
3454 vm_exit_during_initialization(); // no message or exception
3455 }
3456
3457 universe_post_module_init();
3458 }
3459
3460 // Phase 3. final setup - set security manager, system class loader and TCCL
3461 //
3462 // This will instantiate and set the security manager, set the system class
3463 // loader as well as the thread context class loader. The security manager
3464 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3465 // other modules or the application's classpath.
3466 static void call_initPhase3(TRAPS) {
3467 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3468 instanceKlassHandle klass (THREAD, k);
3469
3470 JavaValue result(T_VOID);
3471 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3472 vmSymbols::void_method_signature(), CHECK);
3473 }
3474
3475 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3476 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3477
3478 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3479 create_vm_init_libraries();
3480 }
3481
3482 initialize_class(vmSymbols::java_lang_String(), CHECK);
3483
3484 // Inject CompactStrings value after the static initializers for String ran.
3485 java_lang_String::set_compact_strings(CompactStrings);
3486
3487 // Initialize java_lang.System (needed before creating the thread)
3488 initialize_class(vmSymbols::java_lang_System(), CHECK);
3489 // The VM creates & returns objects of this class. Make sure it's initialized.
3490 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3491 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3492 Handle thread_group = create_initial_thread_group(CHECK);
3493 Universe::set_main_thread_group(thread_group());
3494 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3495 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3496 main_thread->set_threadObj(thread_object);
3497 // Set thread status to running since main thread has
3498 // been started and running.
3499 java_lang_Thread::set_thread_status(thread_object,
3500 java_lang_Thread::RUNNABLE);
3501
3502 // The VM creates objects of this class.
3503 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3504
3505 // The VM preresolves methods to these classes. Make sure that they get initialized
3506 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3507 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3508
3509 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3510 call_initPhase1(CHECK);
3511
3512 // get the Java runtime name after java.lang.System is initialized
3513 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3514 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3515
3516 // an instance of OutOfMemory exception has been allocated earlier
3517 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3518 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3519 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3520 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3521 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3522 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3523 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3524 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3525 }
3526
3527 void Threads::initialize_jsr292_core_classes(TRAPS) {
3528 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3529
3530 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3531 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3532 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3533 }
3534
3535 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3536 extern void JDK_Version_init();
3537
3538 // Preinitialize version info.
3539 VM_Version::early_initialize();
3540
3541 // Check version
3542 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3543
3544 // Initialize library-based TLS
3545 ThreadLocalStorage::init();
3546
3547 // Initialize the output stream module
3548 ostream_init();
3549
3550 // Process java launcher properties.
3551 Arguments::process_sun_java_launcher_properties(args);
3552
3553 // Initialize the os module
3554 os::init();
3555
3556 // Record VM creation timing statistics
3557 TraceVmCreationTime create_vm_timer;
3558 create_vm_timer.start();
3559
3560 // Initialize system properties.
3561 Arguments::init_system_properties();
3562
3563 // So that JDK version can be used as a discriminator when parsing arguments
3564 JDK_Version_init();
3565
3566 // Update/Initialize System properties after JDK version number is known
3567 Arguments::init_version_specific_system_properties();
3568
3569 // Make sure to initialize log configuration *before* parsing arguments
3570 LogConfiguration::initialize(create_vm_timer.begin_time());
3571
3572 // Parse arguments
3573 jint parse_result = Arguments::parse(args);
3574 if (parse_result != JNI_OK) return parse_result;
3575
3576 os::init_before_ergo();
3577
3578 jint ergo_result = Arguments::apply_ergo();
3579 if (ergo_result != JNI_OK) return ergo_result;
3580
3581 // Final check of all ranges after ergonomics which may change values.
3582 if (!CommandLineFlagRangeList::check_ranges()) {
3583 return JNI_EINVAL;
3584 }
3585
3586 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3587 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3588 if (!constraint_result) {
3589 return JNI_EINVAL;
3590 }
3591
3592 CommandLineFlagWriteableList::mark_startup();
3593
3594 if (PauseAtStartup) {
3595 os::pause();
3596 }
3597
3598 HOTSPOT_VM_INIT_BEGIN();
3599
3600 // Timing (must come after argument parsing)
3601 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3602
3603 // Initialize the os module after parsing the args
3604 jint os_init_2_result = os::init_2();
3605 if (os_init_2_result != JNI_OK) return os_init_2_result;
3606
3607 jint adjust_after_os_result = Arguments::adjust_after_os();
3608 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3609
3610 // Initialize output stream logging
3611 ostream_init_log();
3612
3613 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3614 // Must be before create_vm_init_agents()
3615 if (Arguments::init_libraries_at_startup()) {
3616 convert_vm_init_libraries_to_agents();
3617 }
3618
3619 // Launch -agentlib/-agentpath and converted -Xrun agents
3620 if (Arguments::init_agents_at_startup()) {
3621 create_vm_init_agents();
3622 }
3623
3624 // Initialize Threads state
3625 _thread_list = NULL;
3626 _number_of_threads = 0;
3627 _number_of_non_daemon_threads = 0;
3628
3629 // Initialize global data structures and create system classes in heap
3630 vm_init_globals();
3631
3632 #if INCLUDE_JVMCI
3633 if (JVMCICounterSize > 0) {
3634 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3635 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3636 } else {
3637 JavaThread::_jvmci_old_thread_counters = NULL;
3638 }
3639 #endif // INCLUDE_JVMCI
3640
3641 // Attach the main thread to this os thread
3642 JavaThread* main_thread = new JavaThread();
3643 main_thread->set_thread_state(_thread_in_vm);
3644 main_thread->initialize_thread_current();
3645 // must do this before set_active_handles
3646 main_thread->record_stack_base_and_size();
3647 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3648
3649 if (!main_thread->set_as_starting_thread()) {
3650 vm_shutdown_during_initialization(
3651 "Failed necessary internal allocation. Out of swap space");
3652 delete main_thread;
3653 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3654 return JNI_ENOMEM;
3655 }
3656
3657 // Enable guard page *after* os::create_main_thread(), otherwise it would
3658 // crash Linux VM, see notes in os_linux.cpp.
3659 main_thread->create_stack_guard_pages();
3660
3661 // Initialize Java-Level synchronization subsystem
3662 ObjectMonitor::Initialize();
3663
3664 // Initialize global modules
3665 jint status = init_globals();
3666 if (status != JNI_OK) {
3667 delete main_thread;
3668 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3669 return status;
3670 }
3671
3672 if (TRACE_INITIALIZE() != JNI_OK) {
3673 vm_exit_during_initialization("Failed to initialize tracing backend");
3674 }
3675
3676 // Should be done after the heap is fully created
3677 main_thread->cache_global_variables();
3678
3679 HandleMark hm;
3680
3681 { MutexLocker mu(Threads_lock);
3682 Threads::add(main_thread);
3683 }
3684
3685 // Any JVMTI raw monitors entered in onload will transition into
3686 // real raw monitor. VM is setup enough here for raw monitor enter.
3687 JvmtiExport::transition_pending_onload_raw_monitors();
3688
3689 // Create the VMThread
3690 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3691
3692 VMThread::create();
3693 Thread* vmthread = VMThread::vm_thread();
3694
3695 if (!os::create_thread(vmthread, os::vm_thread)) {
3696 vm_exit_during_initialization("Cannot create VM thread. "
3697 "Out of system resources.");
3698 }
3699
3700 // Wait for the VM thread to become ready, and VMThread::run to initialize
3701 // Monitors can have spurious returns, must always check another state flag
3702 {
3703 MutexLocker ml(Notify_lock);
3704 os::start_thread(vmthread);
3705 while (vmthread->active_handles() == NULL) {
3706 Notify_lock->wait();
3707 }
3708 }
3709 }
3710
3711 assert(Universe::is_fully_initialized(), "not initialized");
3712 if (VerifyDuringStartup) {
3713 // Make sure we're starting with a clean slate.
3714 VM_Verify verify_op;
3715 VMThread::execute(&verify_op);
3716 }
3717
3718 Thread* THREAD = Thread::current();
3719
3720 // At this point, the Universe is initialized, but we have not executed
3721 // any byte code. Now is a good time (the only time) to dump out the
3722 // internal state of the JVM for sharing.
3723 if (DumpSharedSpaces) {
3724 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3725 ShouldNotReachHere();
3726 }
3727
3728 // Always call even when there are not JVMTI environments yet, since environments
3729 // may be attached late and JVMTI must track phases of VM execution
3730 JvmtiExport::enter_early_start_phase();
3731
3732 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3733 JvmtiExport::post_early_vm_start();
3734
3735 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3736
3737 // We need this for ClassDataSharing - the initial vm.info property is set
3738 // with the default value of CDS "sharing" which may be reset through
3739 // command line options.
3740 reset_vm_info_property(CHECK_JNI_ERR);
3741
3742 quicken_jni_functions();
3743
3744 // No more stub generation allowed after that point.
3745 StubCodeDesc::freeze();
3746
3747 // Set flag that basic initialization has completed. Used by exceptions and various
3748 // debug stuff, that does not work until all basic classes have been initialized.
3749 set_init_completed();
3750
3751 LogConfiguration::post_initialize();
3752 Metaspace::post_initialize();
3753
3754 HOTSPOT_VM_INIT_END();
3755
3756 // record VM initialization completion time
3757 #if INCLUDE_MANAGEMENT
3758 Management::record_vm_init_completed();
3759 #endif // INCLUDE_MANAGEMENT
3760
3761 // Signal Dispatcher needs to be started before VMInit event is posted
3762 os::signal_init();
3763
3764 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3765 if (!DisableAttachMechanism) {
3766 AttachListener::vm_start();
3767 if (StartAttachListener || AttachListener::init_at_startup()) {
3768 AttachListener::init();
3769 }
3770 }
3771
3772 // Launch -Xrun agents
3773 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3774 // back-end can launch with -Xdebug -Xrunjdwp.
3775 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3776 create_vm_init_libraries();
3777 }
3778
3779 if (CleanChunkPoolAsync) {
3780 Chunk::start_chunk_pool_cleaner_task();
3781 }
3782
3783 // initialize compiler(s)
3784 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3785 CompileBroker::compilation_init(CHECK_JNI_ERR);
3786 #endif
3787
3788 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3789 // It is done after compilers are initialized, because otherwise compilations of
3790 // signature polymorphic MH intrinsics can be missed
3791 // (see SystemDictionary::find_method_handle_intrinsic).
3792 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3793
3794 // This will initialize the module system. Only java.base classes can be
3795 // loaded until phase 2 completes
3796 call_initPhase2(CHECK_JNI_ERR);
3797
3798 // Always call even when there are not JVMTI environments yet, since environments
3799 // may be attached late and JVMTI must track phases of VM execution
3800 JvmtiExport::enter_start_phase();
3801
3802 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3803 JvmtiExport::post_vm_start();
3804
3805 // Final system initialization including security manager and system class loader
3806 call_initPhase3(CHECK_JNI_ERR);
3807
3808 // cache the system class loader
3809 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3810
3811 #if INCLUDE_JVMCI
3812 if (EnableJVMCI) {
3813 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3814 // The JVMCI Java initialization code will read this flag and
3815 // do the printing if it's set.
3816 bool init = JVMCIPrintProperties;
3817
3818 if (!init) {
3819 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3820 // compilations via JVMCI will not actually block until JVMCI is initialized.
3821 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3822 }
3823
3824 if (init) {
3825 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3826 }
3827 }
3828 #endif
3829
3830 // Always call even when there are not JVMTI environments yet, since environments
3831 // may be attached late and JVMTI must track phases of VM execution
3832 JvmtiExport::enter_live_phase();
3833
3834 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3835 JvmtiExport::post_vm_initialized();
3836
3837 if (TRACE_START() != JNI_OK) {
3838 vm_exit_during_initialization("Failed to start tracing backend.");
3839 }
3840
3841 #if INCLUDE_MANAGEMENT
3842 Management::initialize(THREAD);
3843
3844 if (HAS_PENDING_EXCEPTION) {
3845 // management agent fails to start possibly due to
3846 // configuration problem and is responsible for printing
3847 // stack trace if appropriate. Simply exit VM.
3848 vm_exit(1);
3849 }
3850 #endif // INCLUDE_MANAGEMENT
3851
3852 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3853 if (MemProfiling) MemProfiler::engage();
3854 StatSampler::engage();
3855 if (CheckJNICalls) JniPeriodicChecker::engage();
3856
3857 BiasedLocking::init();
3858
3859 #if INCLUDE_RTM_OPT
3860 RTMLockingCounters::init();
3861 #endif
3862
3863 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3864 call_postVMInitHook(THREAD);
3865 // The Java side of PostVMInitHook.run must deal with all
3866 // exceptions and provide means of diagnosis.
3867 if (HAS_PENDING_EXCEPTION) {
3868 CLEAR_PENDING_EXCEPTION;
3869 }
3870 }
3871
3872 {
3873 MutexLocker ml(PeriodicTask_lock);
3874 // Make sure the WatcherThread can be started by WatcherThread::start()
3875 // or by dynamic enrollment.
3876 WatcherThread::make_startable();
3877 // Start up the WatcherThread if there are any periodic tasks
3878 // NOTE: All PeriodicTasks should be registered by now. If they
3879 // aren't, late joiners might appear to start slowly (we might
3880 // take a while to process their first tick).
3881 if (PeriodicTask::num_tasks() > 0) {
3882 WatcherThread::start();
3883 }
3884 }
3885
3886 create_vm_timer.end();
3887 #ifdef ASSERT
3888 _vm_complete = true;
3889 #endif
3890 return JNI_OK;
3891 }
3892
3893 // type for the Agent_OnLoad and JVM_OnLoad entry points
3894 extern "C" {
3895 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3896 }
3897 // Find a command line agent library and return its entry point for
3898 // -agentlib: -agentpath: -Xrun
3899 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3900 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3901 const char *on_load_symbols[],
3902 size_t num_symbol_entries) {
3903 OnLoadEntry_t on_load_entry = NULL;
3904 void *library = NULL;
3905
3906 if (!agent->valid()) {
3907 char buffer[JVM_MAXPATHLEN];
3908 char ebuf[1024] = "";
3909 const char *name = agent->name();
3910 const char *msg = "Could not find agent library ";
3911
3912 // First check to see if agent is statically linked into executable
3913 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3914 library = agent->os_lib();
3915 } else if (agent->is_absolute_path()) {
3916 library = os::dll_load(name, ebuf, sizeof ebuf);
3917 if (library == NULL) {
3918 const char *sub_msg = " in absolute path, with error: ";
3919 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3920 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3921 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3922 // If we can't find the agent, exit.
3923 vm_exit_during_initialization(buf, NULL);
3924 FREE_C_HEAP_ARRAY(char, buf);
3925 }
3926 } else {
3927 // Try to load the agent from the standard dll directory
3928 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3929 name)) {
3930 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3931 }
3932 if (library == NULL) { // Try the local directory
3933 char ns[1] = {0};
3934 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3935 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3936 }
3937 if (library == NULL) {
3938 const char *sub_msg = " on the library path, with error: ";
3939 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3940 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3941 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3942 // If we can't find the agent, exit.
3943 vm_exit_during_initialization(buf, NULL);
3944 FREE_C_HEAP_ARRAY(char, buf);
3945 }
3946 }
3947 }
3948 agent->set_os_lib(library);
3949 agent->set_valid();
3950 }
3951
3952 // Find the OnLoad function.
3953 on_load_entry =
3954 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3955 false,
3956 on_load_symbols,
3957 num_symbol_entries));
3958 return on_load_entry;
3959 }
3960
3961 // Find the JVM_OnLoad entry point
3962 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3963 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3964 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3965 }
3966
3967 // Find the Agent_OnLoad entry point
3968 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3969 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3970 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3971 }
3972
3973 // For backwards compatibility with -Xrun
3974 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3975 // treated like -agentpath:
3976 // Must be called before agent libraries are created
3977 void Threads::convert_vm_init_libraries_to_agents() {
3978 AgentLibrary* agent;
3979 AgentLibrary* next;
3980
3981 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3982 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3983 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3984
3985 // If there is an JVM_OnLoad function it will get called later,
3986 // otherwise see if there is an Agent_OnLoad
3987 if (on_load_entry == NULL) {
3988 on_load_entry = lookup_agent_on_load(agent);
3989 if (on_load_entry != NULL) {
3990 // switch it to the agent list -- so that Agent_OnLoad will be called,
3991 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3992 Arguments::convert_library_to_agent(agent);
3993 } else {
3994 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3995 }
3996 }
3997 }
3998 }
3999
4000 // Create agents for -agentlib: -agentpath: and converted -Xrun
4001 // Invokes Agent_OnLoad
4002 // Called very early -- before JavaThreads exist
4003 void Threads::create_vm_init_agents() {
4004 extern struct JavaVM_ main_vm;
4005 AgentLibrary* agent;
4006
4007 JvmtiExport::enter_onload_phase();
4008
4009 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4010 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4011
4012 if (on_load_entry != NULL) {
4013 // Invoke the Agent_OnLoad function
4014 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4015 if (err != JNI_OK) {
4016 vm_exit_during_initialization("agent library failed to init", agent->name());
4017 }
4018 } else {
4019 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4020 }
4021 }
4022 JvmtiExport::enter_primordial_phase();
4023 }
4024
4025 extern "C" {
4026 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4027 }
4028
4029 void Threads::shutdown_vm_agents() {
4030 // Send any Agent_OnUnload notifications
4031 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4032 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4033 extern struct JavaVM_ main_vm;
4034 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4035
4036 // Find the Agent_OnUnload function.
4037 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4038 os::find_agent_function(agent,
4039 false,
4040 on_unload_symbols,
4041 num_symbol_entries));
4042
4043 // Invoke the Agent_OnUnload function
4044 if (unload_entry != NULL) {
4045 JavaThread* thread = JavaThread::current();
4046 ThreadToNativeFromVM ttn(thread);
4047 HandleMark hm(thread);
4048 (*unload_entry)(&main_vm);
4049 }
4050 }
4051 }
4052
4053 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4054 // Invokes JVM_OnLoad
4055 void Threads::create_vm_init_libraries() {
4056 extern struct JavaVM_ main_vm;
4057 AgentLibrary* agent;
4058
4059 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4060 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4061
4062 if (on_load_entry != NULL) {
4063 // Invoke the JVM_OnLoad function
4064 JavaThread* thread = JavaThread::current();
4065 ThreadToNativeFromVM ttn(thread);
4066 HandleMark hm(thread);
4067 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4068 if (err != JNI_OK) {
4069 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4070 }
4071 } else {
4072 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4073 }
4074 }
4075 }
4076
4077 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4078 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4079
4080 JavaThread* java_thread = NULL;
4081 // Sequential search for now. Need to do better optimization later.
4082 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4083 oop tobj = thread->threadObj();
4084 if (!thread->is_exiting() &&
4085 tobj != NULL &&
4086 java_tid == java_lang_Thread::thread_id(tobj)) {
4087 java_thread = thread;
4088 break;
4089 }
4090 }
4091 return java_thread;
4092 }
4093
4094
4095 // Last thread running calls java.lang.Shutdown.shutdown()
4096 void JavaThread::invoke_shutdown_hooks() {
4097 HandleMark hm(this);
4098
4099 // We could get here with a pending exception, if so clear it now.
4100 if (this->has_pending_exception()) {
4101 this->clear_pending_exception();
4102 }
4103
4104 EXCEPTION_MARK;
4105 Klass* k =
4106 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4107 THREAD);
4108 if (k != NULL) {
4109 // SystemDictionary::resolve_or_null will return null if there was
4110 // an exception. If we cannot load the Shutdown class, just don't
4111 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4112 // and finalizers (if runFinalizersOnExit is set) won't be run.
4113 // Note that if a shutdown hook was registered or runFinalizersOnExit
4114 // was called, the Shutdown class would have already been loaded
4115 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4116 instanceKlassHandle shutdown_klass (THREAD, k);
4117 JavaValue result(T_VOID);
4118 JavaCalls::call_static(&result,
4119 shutdown_klass,
4120 vmSymbols::shutdown_method_name(),
4121 vmSymbols::void_method_signature(),
4122 THREAD);
4123 }
4124 CLEAR_PENDING_EXCEPTION;
4125 }
4126
4127 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4128 // the program falls off the end of main(). Another VM exit path is through
4129 // vm_exit() when the program calls System.exit() to return a value or when
4130 // there is a serious error in VM. The two shutdown paths are not exactly
4131 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4132 // and VM_Exit op at VM level.
4133 //
4134 // Shutdown sequence:
4135 // + Shutdown native memory tracking if it is on
4136 // + Wait until we are the last non-daemon thread to execute
4137 // <-- every thing is still working at this moment -->
4138 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4139 // shutdown hooks, run finalizers if finalization-on-exit
4140 // + Call before_exit(), prepare for VM exit
4141 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4142 // currently the only user of this mechanism is File.deleteOnExit())
4143 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4144 // post thread end and vm death events to JVMTI,
4145 // stop signal thread
4146 // + Call JavaThread::exit(), it will:
4147 // > release JNI handle blocks, remove stack guard pages
4148 // > remove this thread from Threads list
4149 // <-- no more Java code from this thread after this point -->
4150 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4151 // the compiler threads at safepoint
4152 // <-- do not use anything that could get blocked by Safepoint -->
4153 // + Disable tracing at JNI/JVM barriers
4154 // + Set _vm_exited flag for threads that are still running native code
4155 // + Delete this thread
4156 // + Call exit_globals()
4157 // > deletes tty
4158 // > deletes PerfMemory resources
4159 // + Return to caller
4160
4161 bool Threads::destroy_vm() {
4162 JavaThread* thread = JavaThread::current();
4163
4164 #ifdef ASSERT
4165 _vm_complete = false;
4166 #endif
4167 // Wait until we are the last non-daemon thread to execute
4168 { MutexLocker nu(Threads_lock);
4169 while (Threads::number_of_non_daemon_threads() > 1)
4170 // This wait should make safepoint checks, wait without a timeout,
4171 // and wait as a suspend-equivalent condition.
4172 //
4173 // Note: If the FlatProfiler is running and this thread is waiting
4174 // for another non-daemon thread to finish, then the FlatProfiler
4175 // is waiting for the external suspend request on this thread to
4176 // complete. wait_for_ext_suspend_completion() will eventually
4177 // timeout, but that takes time. Making this wait a suspend-
4178 // equivalent condition solves that timeout problem.
4179 //
4180 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4181 Mutex::_as_suspend_equivalent_flag);
4182 }
4183
4184 // Hang forever on exit if we are reporting an error.
4185 if (ShowMessageBoxOnError && is_error_reported()) {
4186 os::infinite_sleep();
4187 }
4188 os::wait_for_keypress_at_exit();
4189
4190 // run Java level shutdown hooks
4191 thread->invoke_shutdown_hooks();
4192
4193 before_exit(thread);
4194
4195 thread->exit(true);
4196
4197 // Stop VM thread.
4198 {
4199 // 4945125 The vm thread comes to a safepoint during exit.
4200 // GC vm_operations can get caught at the safepoint, and the
4201 // heap is unparseable if they are caught. Grab the Heap_lock
4202 // to prevent this. The GC vm_operations will not be able to
4203 // queue until after the vm thread is dead. After this point,
4204 // we'll never emerge out of the safepoint before the VM exits.
4205
4206 MutexLocker ml(Heap_lock);
4207
4208 VMThread::wait_for_vm_thread_exit();
4209 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4210 VMThread::destroy();
4211 }
4212
4213 // clean up ideal graph printers
4214 #if defined(COMPILER2) && !defined(PRODUCT)
4215 IdealGraphPrinter::clean_up();
4216 #endif
4217
4218 // Now, all Java threads are gone except daemon threads. Daemon threads
4219 // running Java code or in VM are stopped by the Safepoint. However,
4220 // daemon threads executing native code are still running. But they
4221 // will be stopped at native=>Java/VM barriers. Note that we can't
4222 // simply kill or suspend them, as it is inherently deadlock-prone.
4223
4224 VM_Exit::set_vm_exited();
4225
4226 notify_vm_shutdown();
4227
4228 delete thread;
4229
4230 #if INCLUDE_JVMCI
4231 if (JVMCICounterSize > 0) {
4232 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4233 }
4234 #endif
4235
4236 // exit_globals() will delete tty
4237 exit_globals();
4238
4239 LogConfiguration::finalize();
4240
4241 return true;
4242 }
4243
4244
4245 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4246 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4247 return is_supported_jni_version(version);
4248 }
4249
4250
4251 jboolean Threads::is_supported_jni_version(jint version) {
4252 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4253 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4254 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4255 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4256 if (version == JNI_VERSION_9) return JNI_TRUE;
4257 return JNI_FALSE;
4258 }
4259
4260
4261 void Threads::add(JavaThread* p, bool force_daemon) {
4262 // The threads lock must be owned at this point
4263 assert_locked_or_safepoint(Threads_lock);
4264
4265 // See the comment for this method in thread.hpp for its purpose and
4266 // why it is called here.
4267 p->initialize_queues();
4268 p->set_next(_thread_list);
4269 _thread_list = p;
4270 _number_of_threads++;
4271 oop threadObj = p->threadObj();
4272 bool daemon = true;
4273 // Bootstrapping problem: threadObj can be null for initial
4274 // JavaThread (or for threads attached via JNI)
4275 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4276 _number_of_non_daemon_threads++;
4277 daemon = false;
4278 }
4279
4280 ThreadService::add_thread(p, daemon);
4281
4282 // Possible GC point.
4283 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4284 }
4285
4286 void Threads::remove(JavaThread* p) {
4287 // Extra scope needed for Thread_lock, so we can check
4288 // that we do not remove thread without safepoint code notice
4289 { MutexLocker ml(Threads_lock);
4290
4291 assert(includes(p), "p must be present");
4292
4293 JavaThread* current = _thread_list;
4294 JavaThread* prev = NULL;
4295
4296 while (current != p) {
4297 prev = current;
4298 current = current->next();
4299 }
4300
4301 if (prev) {
4302 prev->set_next(current->next());
4303 } else {
4304 _thread_list = p->next();
4305 }
4306 _number_of_threads--;
4307 oop threadObj = p->threadObj();
4308 bool daemon = true;
4309 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4310 _number_of_non_daemon_threads--;
4311 daemon = false;
4312
4313 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4314 // on destroy_vm will wake up.
4315 if (number_of_non_daemon_threads() == 1) {
4316 Threads_lock->notify_all();
4317 }
4318 }
4319 ThreadService::remove_thread(p, daemon);
4320
4321 // Make sure that safepoint code disregard this thread. This is needed since
4322 // the thread might mess around with locks after this point. This can cause it
4323 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4324 // of this thread since it is removed from the queue.
4325 p->set_terminated_value();
4326 } // unlock Threads_lock
4327
4328 // Since Events::log uses a lock, we grab it outside the Threads_lock
4329 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4330 }
4331
4332 // Threads_lock must be held when this is called (or must be called during a safepoint)
4333 bool Threads::includes(JavaThread* p) {
4334 assert(Threads_lock->is_locked(), "sanity check");
4335 ALL_JAVA_THREADS(q) {
4336 if (q == p) {
4337 return true;
4338 }
4339 }
4340 return false;
4341 }
4342
4343 // Operations on the Threads list for GC. These are not explicitly locked,
4344 // but the garbage collector must provide a safe context for them to run.
4345 // In particular, these things should never be called when the Threads_lock
4346 // is held by some other thread. (Note: the Safepoint abstraction also
4347 // uses the Threads_lock to guarantee this property. It also makes sure that
4348 // all threads gets blocked when exiting or starting).
4349
4350 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4351 ALL_JAVA_THREADS(p) {
4352 p->oops_do(f, cf);
4353 }
4354 VMThread::vm_thread()->oops_do(f, cf);
4355 }
4356
4357 void Threads::change_thread_claim_parity() {
4358 // Set the new claim parity.
4359 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4360 "Not in range.");
4361 _thread_claim_parity++;
4362 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4363 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4364 "Not in range.");
4365 }
4366
4367 #ifdef ASSERT
4368 void Threads::assert_all_threads_claimed() {
4369 ALL_JAVA_THREADS(p) {
4370 const int thread_parity = p->oops_do_parity();
4371 assert((thread_parity == _thread_claim_parity),
4372 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4373 }
4374 }
4375 #endif // ASSERT
4376
4377 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4378 int cp = Threads::thread_claim_parity();
4379 ALL_JAVA_THREADS(p) {
4380 if (p->claim_oops_do(is_par, cp)) {
4381 p->oops_do(f, cf);
4382 }
4383 }
4384 VMThread* vmt = VMThread::vm_thread();
4385 if (vmt->claim_oops_do(is_par, cp)) {
4386 vmt->oops_do(f, cf);
4387 }
4388 }
4389
4390 #if INCLUDE_ALL_GCS
4391 // Used by ParallelScavenge
4392 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4393 ALL_JAVA_THREADS(p) {
4394 q->enqueue(new ThreadRootsTask(p));
4395 }
4396 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4397 }
4398
4399 // Used by Parallel Old
4400 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4401 ALL_JAVA_THREADS(p) {
4402 q->enqueue(new ThreadRootsMarkingTask(p));
4403 }
4404 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4405 }
4406 #endif // INCLUDE_ALL_GCS
4407
4408 void Threads::nmethods_do(CodeBlobClosure* cf) {
4409 ALL_JAVA_THREADS(p) {
4410 // This is used by the code cache sweeper to mark nmethods that are active
4411 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4412 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4413 if(!p->is_Code_cache_sweeper_thread()) {
4414 p->nmethods_do(cf);
4415 }
4416 }
4417 }
4418
4419 void Threads::metadata_do(void f(Metadata*)) {
4420 ALL_JAVA_THREADS(p) {
4421 p->metadata_do(f);
4422 }
4423 }
4424
4425 class ThreadHandlesClosure : public ThreadClosure {
4426 void (*_f)(Metadata*);
4427 public:
4428 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4429 virtual void do_thread(Thread* thread) {
4430 thread->metadata_handles_do(_f);
4431 }
4432 };
4433
4434 void Threads::metadata_handles_do(void f(Metadata*)) {
4435 // Only walk the Handles in Thread.
4436 ThreadHandlesClosure handles_closure(f);
4437 threads_do(&handles_closure);
4438 }
4439
4440 void Threads::deoptimized_wrt_marked_nmethods() {
4441 ALL_JAVA_THREADS(p) {
4442 p->deoptimized_wrt_marked_nmethods();
4443 }
4444 }
4445
4446
4447 // Get count Java threads that are waiting to enter the specified monitor.
4448 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4449 address monitor,
4450 bool doLock) {
4451 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4452 "must grab Threads_lock or be at safepoint");
4453 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4454
4455 int i = 0;
4456 {
4457 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4458 ALL_JAVA_THREADS(p) {
4459 if (!p->can_call_java()) continue;
4460
4461 address pending = (address)p->current_pending_monitor();
4462 if (pending == monitor) { // found a match
4463 if (i < count) result->append(p); // save the first count matches
4464 i++;
4465 }
4466 }
4467 }
4468 return result;
4469 }
4470
4471
4472 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4473 bool doLock) {
4474 assert(doLock ||
4475 Threads_lock->owned_by_self() ||
4476 SafepointSynchronize::is_at_safepoint(),
4477 "must grab Threads_lock or be at safepoint");
4478
4479 // NULL owner means not locked so we can skip the search
4480 if (owner == NULL) return NULL;
4481
4482 {
4483 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4484 ALL_JAVA_THREADS(p) {
4485 // first, see if owner is the address of a Java thread
4486 if (owner == (address)p) return p;
4487 }
4488 }
4489 // Cannot assert on lack of success here since this function may be
4490 // used by code that is trying to report useful problem information
4491 // like deadlock detection.
4492 if (UseHeavyMonitors) return NULL;
4493
4494 // If we didn't find a matching Java thread and we didn't force use of
4495 // heavyweight monitors, then the owner is the stack address of the
4496 // Lock Word in the owning Java thread's stack.
4497 //
4498 JavaThread* the_owner = NULL;
4499 {
4500 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4501 ALL_JAVA_THREADS(q) {
4502 if (q->is_lock_owned(owner)) {
4503 the_owner = q;
4504 break;
4505 }
4506 }
4507 }
4508 // cannot assert on lack of success here; see above comment
4509 return the_owner;
4510 }
4511
4512 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4513 void Threads::print_on(outputStream* st, bool print_stacks,
4514 bool internal_format, bool print_concurrent_locks) {
4515 char buf[32];
4516 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4517
4518 st->print_cr("Full thread dump %s (%s %s):",
4519 Abstract_VM_Version::vm_name(),
4520 Abstract_VM_Version::vm_release(),
4521 Abstract_VM_Version::vm_info_string());
4522 st->cr();
4523
4524 #if INCLUDE_SERVICES
4525 // Dump concurrent locks
4526 ConcurrentLocksDump concurrent_locks;
4527 if (print_concurrent_locks) {
4528 concurrent_locks.dump_at_safepoint();
4529 }
4530 #endif // INCLUDE_SERVICES
4531
4532 ALL_JAVA_THREADS(p) {
4533 ResourceMark rm;
4534 p->print_on(st);
4535 if (print_stacks) {
4536 if (internal_format) {
4537 p->trace_stack();
4538 } else {
4539 p->print_stack_on(st);
4540 }
4541 }
4542 st->cr();
4543 #if INCLUDE_SERVICES
4544 if (print_concurrent_locks) {
4545 concurrent_locks.print_locks_on(p, st);
4546 }
4547 #endif // INCLUDE_SERVICES
4548 }
4549
4550 VMThread::vm_thread()->print_on(st);
4551 st->cr();
4552 Universe::heap()->print_gc_threads_on(st);
4553 WatcherThread* wt = WatcherThread::watcher_thread();
4554 if (wt != NULL) {
4555 wt->print_on(st);
4556 st->cr();
4557 }
4558 st->flush();
4559 }
4560
4561 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4562 int buflen, bool* found_current) {
4563 if (this_thread != NULL) {
4564 bool is_current = (current == this_thread);
4565 *found_current = *found_current || is_current;
4566 st->print("%s", is_current ? "=>" : " ");
4567
4568 st->print(PTR_FORMAT, p2i(this_thread));
4569 st->print(" ");
4570 this_thread->print_on_error(st, buf, buflen);
4571 st->cr();
4572 }
4573 }
4574
4575 class PrintOnErrorClosure : public ThreadClosure {
4576 outputStream* _st;
4577 Thread* _current;
4578 char* _buf;
4579 int _buflen;
4580 bool* _found_current;
4581 public:
4582 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4583 int buflen, bool* found_current) :
4584 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4585
4586 virtual void do_thread(Thread* thread) {
4587 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4588 }
4589 };
4590
4591 // Threads::print_on_error() is called by fatal error handler. It's possible
4592 // that VM is not at safepoint and/or current thread is inside signal handler.
4593 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4594 // memory (even in resource area), it might deadlock the error handler.
4595 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4596 int buflen) {
4597 bool found_current = false;
4598 st->print_cr("Java Threads: ( => current thread )");
4599 ALL_JAVA_THREADS(thread) {
4600 print_on_error(thread, st, current, buf, buflen, &found_current);
4601 }
4602 st->cr();
4603
4604 st->print_cr("Other Threads:");
4605 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4606 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4607
4608 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4609 Universe::heap()->gc_threads_do(&print_closure);
4610
4611 if (!found_current) {
4612 st->cr();
4613 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4614 current->print_on_error(st, buf, buflen);
4615 st->cr();
4616 }
4617 st->cr();
4618 st->print_cr("Threads with active compile tasks:");
4619 print_threads_compiling(st, buf, buflen);
4620 }
4621
4622 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4623 ALL_JAVA_THREADS(thread) {
4624 if (thread->is_Compiler_thread()) {
4625 CompilerThread* ct = (CompilerThread*) thread;
4626 if (ct->task() != NULL) {
4627 thread->print_name_on_error(st, buf, buflen);
4628 ct->task()->print(st, NULL, true, true);
4629 }
4630 }
4631 }
4632 }
4633
4634
4635 // Internal SpinLock and Mutex
4636 // Based on ParkEvent
4637
4638 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4639 //
4640 // We employ SpinLocks _only for low-contention, fixed-length
4641 // short-duration critical sections where we're concerned
4642 // about native mutex_t or HotSpot Mutex:: latency.
4643 // The mux construct provides a spin-then-block mutual exclusion
4644 // mechanism.
4645 //
4646 // Testing has shown that contention on the ListLock guarding gFreeList
4647 // is common. If we implement ListLock as a simple SpinLock it's common
4648 // for the JVM to devolve to yielding with little progress. This is true
4649 // despite the fact that the critical sections protected by ListLock are
4650 // extremely short.
4651 //
4652 // TODO-FIXME: ListLock should be of type SpinLock.
4653 // We should make this a 1st-class type, integrated into the lock
4654 // hierarchy as leaf-locks. Critically, the SpinLock structure
4655 // should have sufficient padding to avoid false-sharing and excessive
4656 // cache-coherency traffic.
4657
4658
4659 typedef volatile int SpinLockT;
4660
4661 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4662 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4663 return; // normal fast-path return
4664 }
4665
4666 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4667 TEVENT(SpinAcquire - ctx);
4668 int ctr = 0;
4669 int Yields = 0;
4670 for (;;) {
4671 while (*adr != 0) {
4672 ++ctr;
4673 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4674 if (Yields > 5) {
4675 os::naked_short_sleep(1);
4676 } else {
4677 os::naked_yield();
4678 ++Yields;
4679 }
4680 } else {
4681 SpinPause();
4682 }
4683 }
4684 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4685 }
4686 }
4687
4688 void Thread::SpinRelease(volatile int * adr) {
4689 assert(*adr != 0, "invariant");
4690 OrderAccess::fence(); // guarantee at least release consistency.
4691 // Roach-motel semantics.
4692 // It's safe if subsequent LDs and STs float "up" into the critical section,
4693 // but prior LDs and STs within the critical section can't be allowed
4694 // to reorder or float past the ST that releases the lock.
4695 // Loads and stores in the critical section - which appear in program
4696 // order before the store that releases the lock - must also appear
4697 // before the store that releases the lock in memory visibility order.
4698 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4699 // the ST of 0 into the lock-word which releases the lock, so fence
4700 // more than covers this on all platforms.
4701 *adr = 0;
4702 }
4703
4704 // muxAcquire and muxRelease:
4705 //
4706 // * muxAcquire and muxRelease support a single-word lock-word construct.
4707 // The LSB of the word is set IFF the lock is held.
4708 // The remainder of the word points to the head of a singly-linked list
4709 // of threads blocked on the lock.
4710 //
4711 // * The current implementation of muxAcquire-muxRelease uses its own
4712 // dedicated Thread._MuxEvent instance. If we're interested in
4713 // minimizing the peak number of extant ParkEvent instances then
4714 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4715 // as certain invariants were satisfied. Specifically, care would need
4716 // to be taken with regards to consuming unpark() "permits".
4717 // A safe rule of thumb is that a thread would never call muxAcquire()
4718 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4719 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4720 // consume an unpark() permit intended for monitorenter, for instance.
4721 // One way around this would be to widen the restricted-range semaphore
4722 // implemented in park(). Another alternative would be to provide
4723 // multiple instances of the PlatformEvent() for each thread. One
4724 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4725 //
4726 // * Usage:
4727 // -- Only as leaf locks
4728 // -- for short-term locking only as muxAcquire does not perform
4729 // thread state transitions.
4730 //
4731 // Alternatives:
4732 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4733 // but with parking or spin-then-park instead of pure spinning.
4734 // * Use Taura-Oyama-Yonenzawa locks.
4735 // * It's possible to construct a 1-0 lock if we encode the lockword as
4736 // (List,LockByte). Acquire will CAS the full lockword while Release
4737 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4738 // acquiring threads use timers (ParkTimed) to detect and recover from
4739 // the stranding window. Thread/Node structures must be aligned on 256-byte
4740 // boundaries by using placement-new.
4741 // * Augment MCS with advisory back-link fields maintained with CAS().
4742 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4743 // The validity of the backlinks must be ratified before we trust the value.
4744 // If the backlinks are invalid the exiting thread must back-track through the
4745 // the forward links, which are always trustworthy.
4746 // * Add a successor indication. The LockWord is currently encoded as
4747 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4748 // to provide the usual futile-wakeup optimization.
4749 // See RTStt for details.
4750 // * Consider schedctl.sc_nopreempt to cover the critical section.
4751 //
4752
4753
4754 typedef volatile intptr_t MutexT; // Mux Lock-word
4755 enum MuxBits { LOCKBIT = 1 };
4756
4757 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4758 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4759 if (w == 0) return;
4760 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4761 return;
4762 }
4763
4764 TEVENT(muxAcquire - Contention);
4765 ParkEvent * const Self = Thread::current()->_MuxEvent;
4766 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4767 for (;;) {
4768 int its = (os::is_MP() ? 100 : 0) + 1;
4769
4770 // Optional spin phase: spin-then-park strategy
4771 while (--its >= 0) {
4772 w = *Lock;
4773 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4774 return;
4775 }
4776 }
4777
4778 Self->reset();
4779 Self->OnList = intptr_t(Lock);
4780 // The following fence() isn't _strictly necessary as the subsequent
4781 // CAS() both serializes execution and ratifies the fetched *Lock value.
4782 OrderAccess::fence();
4783 for (;;) {
4784 w = *Lock;
4785 if ((w & LOCKBIT) == 0) {
4786 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4787 Self->OnList = 0; // hygiene - allows stronger asserts
4788 return;
4789 }
4790 continue; // Interference -- *Lock changed -- Just retry
4791 }
4792 assert(w & LOCKBIT, "invariant");
4793 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4794 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4795 }
4796
4797 while (Self->OnList != 0) {
4798 Self->park();
4799 }
4800 }
4801 }
4802
4803 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4804 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4805 if (w == 0) return;
4806 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4807 return;
4808 }
4809
4810 TEVENT(muxAcquire - Contention);
4811 ParkEvent * ReleaseAfter = NULL;
4812 if (ev == NULL) {
4813 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4814 }
4815 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4816 for (;;) {
4817 guarantee(ev->OnList == 0, "invariant");
4818 int its = (os::is_MP() ? 100 : 0) + 1;
4819
4820 // Optional spin phase: spin-then-park strategy
4821 while (--its >= 0) {
4822 w = *Lock;
4823 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4824 if (ReleaseAfter != NULL) {
4825 ParkEvent::Release(ReleaseAfter);
4826 }
4827 return;
4828 }
4829 }
4830
4831 ev->reset();
4832 ev->OnList = intptr_t(Lock);
4833 // The following fence() isn't _strictly necessary as the subsequent
4834 // CAS() both serializes execution and ratifies the fetched *Lock value.
4835 OrderAccess::fence();
4836 for (;;) {
4837 w = *Lock;
4838 if ((w & LOCKBIT) == 0) {
4839 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4840 ev->OnList = 0;
4841 // We call ::Release while holding the outer lock, thus
4842 // artificially lengthening the critical section.
4843 // Consider deferring the ::Release() until the subsequent unlock(),
4844 // after we've dropped the outer lock.
4845 if (ReleaseAfter != NULL) {
4846 ParkEvent::Release(ReleaseAfter);
4847 }
4848 return;
4849 }
4850 continue; // Interference -- *Lock changed -- Just retry
4851 }
4852 assert(w & LOCKBIT, "invariant");
4853 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4854 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4855 }
4856
4857 while (ev->OnList != 0) {
4858 ev->park();
4859 }
4860 }
4861 }
4862
4863 // Release() must extract a successor from the list and then wake that thread.
4864 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4865 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4866 // Release() would :
4867 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4868 // (B) Extract a successor from the private list "in-hand"
4869 // (C) attempt to CAS() the residual back into *Lock over null.
4870 // If there were any newly arrived threads and the CAS() would fail.
4871 // In that case Release() would detach the RATs, re-merge the list in-hand
4872 // with the RATs and repeat as needed. Alternately, Release() might
4873 // detach and extract a successor, but then pass the residual list to the wakee.
4874 // The wakee would be responsible for reattaching and remerging before it
4875 // competed for the lock.
4876 //
4877 // Both "pop" and DMR are immune from ABA corruption -- there can be
4878 // multiple concurrent pushers, but only one popper or detacher.
4879 // This implementation pops from the head of the list. This is unfair,
4880 // but tends to provide excellent throughput as hot threads remain hot.
4881 // (We wake recently run threads first).
4882 //
4883 // All paths through muxRelease() will execute a CAS.
4884 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4885 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4886 // executed within the critical section are complete and globally visible before the
4887 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4888 void Thread::muxRelease(volatile intptr_t * Lock) {
4889 for (;;) {
4890 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4891 assert(w & LOCKBIT, "invariant");
4892 if (w == LOCKBIT) return;
4893 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4894 assert(List != NULL, "invariant");
4895 assert(List->OnList == intptr_t(Lock), "invariant");
4896 ParkEvent * const nxt = List->ListNext;
4897 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4898
4899 // The following CAS() releases the lock and pops the head element.
4900 // The CAS() also ratifies the previously fetched lock-word value.
4901 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4902 continue;
4903 }
4904 List->OnList = 0;
4905 OrderAccess::fence();
4906 List->unpark();
4907 return;
4908 }
4909 }
4910
4911
4912 void Threads::verify() {
4913 ALL_JAVA_THREADS(p) {
4914 p->verify();
4915 }
4916 VMThread* thread = VMThread::vm_thread();
4917 if (thread != NULL) thread->verify();
4918 }