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 // TODO: Either need better abstractions or have all GCs use this.
797 if (UseShenandoahGC && ShenandoahFastSyncRoots && MonitorInUseLists) {
798 ObjectSynchronizer::thread_local_used_oops_do(this, f);
799 }
800 }
801
802 void Thread::metadata_handles_do(void f(Metadata*)) {
803 // Only walk the Handles in Thread.
804 if (metadata_handles() != NULL) {
805 for (int i = 0; i< metadata_handles()->length(); i++) {
806 f(metadata_handles()->at(i));
807 }
808 }
809 }
810
811 void Thread::print_on(outputStream* st) const {
812 // get_priority assumes osthread initialized
813 if (osthread() != NULL) {
814 int os_prio;
815 if (os::get_native_priority(this, &os_prio) == OS_OK) {
816 st->print("os_prio=%d ", os_prio);
817 }
818 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
819 ext().print_on(st);
820 osthread()->print_on(st);
821 }
822 debug_only(if (WizardMode) print_owned_locks_on(st);)
823 }
824
825 // Thread::print_on_error() is called by fatal error handler. Don't use
826 // any lock or allocate memory.
827 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
828 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
829
830 if (is_VM_thread()) { st->print("VMThread"); }
831 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
832 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
833 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
834 else { st->print("Thread"); }
835
836 if (is_Named_thread()) {
837 st->print(" \"%s\"", name());
838 }
839
840 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
841 p2i(stack_end()), p2i(stack_base()));
842
843 if (osthread()) {
844 st->print(" [id=%d]", osthread()->thread_id());
845 }
846 }
847
848 #ifdef ASSERT
849 void Thread::print_owned_locks_on(outputStream* st) const {
850 Monitor *cur = _owned_locks;
851 if (cur == NULL) {
852 st->print(" (no locks) ");
853 } else {
854 st->print_cr(" Locks owned:");
855 while (cur) {
856 cur->print_on(st);
857 cur = cur->next();
858 }
859 }
860 }
861
862 static int ref_use_count = 0;
863
864 bool Thread::owns_locks_but_compiled_lock() const {
865 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
866 if (cur != Compile_lock) return true;
867 }
868 return false;
869 }
870
871
872 #endif
873
874 #ifndef PRODUCT
875
876 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
877 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
878 // no threads which allow_vm_block's are held
879 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
880 // Check if current thread is allowed to block at a safepoint
881 if (!(_allow_safepoint_count == 0)) {
882 fatal("Possible safepoint reached by thread that does not allow it");
883 }
884 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
885 fatal("LEAF method calling lock?");
886 }
887
888 #ifdef ASSERT
889 if (potential_vm_operation && is_Java_thread()
890 && !Universe::is_bootstrapping()) {
891 // Make sure we do not hold any locks that the VM thread also uses.
892 // This could potentially lead to deadlocks
893 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
894 // Threads_lock is special, since the safepoint synchronization will not start before this is
895 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
896 // since it is used to transfer control between JavaThreads and the VMThread
897 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
898 if ((cur->allow_vm_block() &&
899 cur != Threads_lock &&
900 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
901 cur != VMOperationRequest_lock &&
902 cur != VMOperationQueue_lock) ||
903 cur->rank() == Mutex::special) {
904 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
905 }
906 }
907 }
908
909 if (GCALotAtAllSafepoints) {
910 // We could enter a safepoint here and thus have a gc
911 InterfaceSupport::check_gc_alot();
912 }
913 #endif
914 }
915 #endif
916
917 bool Thread::is_in_stack(address adr) const {
918 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
919 address end = os::current_stack_pointer();
920 // Allow non Java threads to call this without stack_base
921 if (_stack_base == NULL) return true;
922 if (stack_base() >= adr && adr >= end) return true;
923
924 return false;
925 }
926
927 bool Thread::is_in_usable_stack(address adr) const {
928 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
929 size_t usable_stack_size = _stack_size - stack_guard_size;
930
931 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
932 }
933
934
935 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
936 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
937 // used for compilation in the future. If that change is made, the need for these methods
938 // should be revisited, and they should be removed if possible.
939
940 bool Thread::is_lock_owned(address adr) const {
941 return on_local_stack(adr);
942 }
943
944 bool Thread::set_as_starting_thread() {
945 // NOTE: this must be called inside the main thread.
946 return os::create_main_thread((JavaThread*)this);
947 }
948
949 static void initialize_class(Symbol* class_name, TRAPS) {
950 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
951 InstanceKlass::cast(klass)->initialize(CHECK);
952 }
953
954
955 // Creates the initial ThreadGroup
956 static Handle create_initial_thread_group(TRAPS) {
957 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
958 instanceKlassHandle klass (THREAD, k);
959
960 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
961 {
962 JavaValue result(T_VOID);
963 JavaCalls::call_special(&result,
964 system_instance,
965 klass,
966 vmSymbols::object_initializer_name(),
967 vmSymbols::void_method_signature(),
968 CHECK_NH);
969 }
970 Universe::set_system_thread_group(system_instance());
971
972 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
973 {
974 JavaValue result(T_VOID);
975 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
976 JavaCalls::call_special(&result,
977 main_instance,
978 klass,
979 vmSymbols::object_initializer_name(),
980 vmSymbols::threadgroup_string_void_signature(),
981 system_instance,
982 string,
983 CHECK_NH);
984 }
985 return main_instance;
986 }
987
988 // Creates the initial Thread
989 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
990 TRAPS) {
991 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
992 instanceKlassHandle klass (THREAD, k);
993 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
994
995 java_lang_Thread::set_thread(thread_oop(), thread);
996 java_lang_Thread::set_priority(thread_oop(), NormPriority);
997 thread->set_threadObj(thread_oop());
998
999 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1000
1001 JavaValue result(T_VOID);
1002 JavaCalls::call_special(&result, thread_oop,
1003 klass,
1004 vmSymbols::object_initializer_name(),
1005 vmSymbols::threadgroup_string_void_signature(),
1006 thread_group,
1007 string,
1008 CHECK_NULL);
1009 return thread_oop();
1010 }
1011
1012 char java_runtime_name[128] = "";
1013 char java_runtime_version[128] = "";
1014
1015 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1016 static const char* get_java_runtime_name(TRAPS) {
1017 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1018 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1019 fieldDescriptor fd;
1020 bool found = k != NULL &&
1021 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1022 vmSymbols::string_signature(), &fd);
1023 if (found) {
1024 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1025 if (name_oop == NULL) {
1026 return NULL;
1027 }
1028 const char* name = java_lang_String::as_utf8_string(name_oop,
1029 java_runtime_name,
1030 sizeof(java_runtime_name));
1031 return name;
1032 } else {
1033 return NULL;
1034 }
1035 }
1036
1037 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1038 static const char* get_java_runtime_version(TRAPS) {
1039 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1040 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1041 fieldDescriptor fd;
1042 bool found = k != NULL &&
1043 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1044 vmSymbols::string_signature(), &fd);
1045 if (found) {
1046 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1047 if (name_oop == NULL) {
1048 return NULL;
1049 }
1050 const char* name = java_lang_String::as_utf8_string(name_oop,
1051 java_runtime_version,
1052 sizeof(java_runtime_version));
1053 return name;
1054 } else {
1055 return NULL;
1056 }
1057 }
1058
1059 // General purpose hook into Java code, run once when the VM is initialized.
1060 // The Java library method itself may be changed independently from the VM.
1061 static void call_postVMInitHook(TRAPS) {
1062 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1063 instanceKlassHandle klass (THREAD, k);
1064 if (klass.not_null()) {
1065 JavaValue result(T_VOID);
1066 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1067 vmSymbols::void_method_signature(),
1068 CHECK);
1069 }
1070 }
1071
1072 static void reset_vm_info_property(TRAPS) {
1073 // the vm info string
1074 ResourceMark rm(THREAD);
1075 const char *vm_info = VM_Version::vm_info_string();
1076
1077 // java.lang.System class
1078 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1079 instanceKlassHandle klass (THREAD, k);
1080
1081 // setProperty arguments
1082 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1083 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1084
1085 // return value
1086 JavaValue r(T_OBJECT);
1087
1088 // public static String setProperty(String key, String value);
1089 JavaCalls::call_static(&r,
1090 klass,
1091 vmSymbols::setProperty_name(),
1092 vmSymbols::string_string_string_signature(),
1093 key_str,
1094 value_str,
1095 CHECK);
1096 }
1097
1098
1099 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1100 bool daemon, TRAPS) {
1101 assert(thread_group.not_null(), "thread group should be specified");
1102 assert(threadObj() == NULL, "should only create Java thread object once");
1103
1104 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1105 instanceKlassHandle klass (THREAD, k);
1106 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1107
1108 java_lang_Thread::set_thread(thread_oop(), this);
1109 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1110 set_threadObj(thread_oop());
1111
1112 JavaValue result(T_VOID);
1113 if (thread_name != NULL) {
1114 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1115 // Thread gets assigned specified name and null target
1116 JavaCalls::call_special(&result,
1117 thread_oop,
1118 klass,
1119 vmSymbols::object_initializer_name(),
1120 vmSymbols::threadgroup_string_void_signature(),
1121 thread_group, // Argument 1
1122 name, // Argument 2
1123 THREAD);
1124 } else {
1125 // Thread gets assigned name "Thread-nnn" and null target
1126 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1127 JavaCalls::call_special(&result,
1128 thread_oop,
1129 klass,
1130 vmSymbols::object_initializer_name(),
1131 vmSymbols::threadgroup_runnable_void_signature(),
1132 thread_group, // Argument 1
1133 Handle(), // Argument 2
1134 THREAD);
1135 }
1136
1137
1138 if (daemon) {
1139 java_lang_Thread::set_daemon(thread_oop());
1140 }
1141
1142 if (HAS_PENDING_EXCEPTION) {
1143 return;
1144 }
1145
1146 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1147 Handle threadObj(THREAD, this->threadObj());
1148
1149 JavaCalls::call_special(&result,
1150 thread_group,
1151 group,
1152 vmSymbols::add_method_name(),
1153 vmSymbols::thread_void_signature(),
1154 threadObj, // Arg 1
1155 THREAD);
1156 }
1157
1158 // NamedThread -- non-JavaThread subclasses with multiple
1159 // uniquely named instances should derive from this.
1160 NamedThread::NamedThread() : Thread() {
1161 _name = NULL;
1162 _processed_thread = NULL;
1163 _gc_id = GCId::undefined();
1164 }
1165
1166 NamedThread::~NamedThread() {
1167 if (_name != NULL) {
1168 FREE_C_HEAP_ARRAY(char, _name);
1169 _name = NULL;
1170 }
1171 }
1172
1173 void NamedThread::set_name(const char* format, ...) {
1174 guarantee(_name == NULL, "Only get to set name once.");
1175 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1176 guarantee(_name != NULL, "alloc failure");
1177 va_list ap;
1178 va_start(ap, format);
1179 jio_vsnprintf(_name, max_name_len, format, ap);
1180 va_end(ap);
1181 }
1182
1183 void NamedThread::initialize_named_thread() {
1184 set_native_thread_name(name());
1185 }
1186
1187 void NamedThread::print_on(outputStream* st) const {
1188 st->print("\"%s\" ", name());
1189 Thread::print_on(st);
1190 st->cr();
1191 }
1192
1193
1194 // ======= WatcherThread ========
1195
1196 // The watcher thread exists to simulate timer interrupts. It should
1197 // be replaced by an abstraction over whatever native support for
1198 // timer interrupts exists on the platform.
1199
1200 WatcherThread* WatcherThread::_watcher_thread = NULL;
1201 bool WatcherThread::_startable = false;
1202 volatile bool WatcherThread::_should_terminate = false;
1203
1204 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1205 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1206 if (os::create_thread(this, os::watcher_thread)) {
1207 _watcher_thread = this;
1208
1209 // WatcherThread needs GCLAB for cases when it writes to Java heap,
1210 // and needs the space to evacuate. Have to initialize here, because
1211 // WatcherThread is initialized before the Universe.
1212 if (UseShenandoahGC && UseTLAB) {
1213 gclab().initialize(true);
1214 }
1215
1216 // Set the watcher thread to the highest OS priority which should not be
1217 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1218 // is created. The only normal thread using this priority is the reference
1219 // handler thread, which runs for very short intervals only.
1220 // If the VMThread's priority is not lower than the WatcherThread profiling
1221 // will be inaccurate.
1222 os::set_priority(this, MaxPriority);
1223 if (!DisableStartThread) {
1224 os::start_thread(this);
1225 }
1226 }
1227 }
1228
1229 int WatcherThread::sleep() const {
1230 // The WatcherThread does not participate in the safepoint protocol
1231 // for the PeriodicTask_lock because it is not a JavaThread.
1232 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1233
1234 if (_should_terminate) {
1235 // check for termination before we do any housekeeping or wait
1236 return 0; // we did not sleep.
1237 }
1238
1239 // remaining will be zero if there are no tasks,
1240 // causing the WatcherThread to sleep until a task is
1241 // enrolled
1242 int remaining = PeriodicTask::time_to_wait();
1243 int time_slept = 0;
1244
1245 // we expect this to timeout - we only ever get unparked when
1246 // we should terminate or when a new task has been enrolled
1247 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1248
1249 jlong time_before_loop = os::javaTimeNanos();
1250
1251 while (true) {
1252 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1253 remaining);
1254 jlong now = os::javaTimeNanos();
1255
1256 if (remaining == 0) {
1257 // if we didn't have any tasks we could have waited for a long time
1258 // consider the time_slept zero and reset time_before_loop
1259 time_slept = 0;
1260 time_before_loop = now;
1261 } else {
1262 // need to recalculate since we might have new tasks in _tasks
1263 time_slept = (int) ((now - time_before_loop) / 1000000);
1264 }
1265
1266 // Change to task list or spurious wakeup of some kind
1267 if (timedout || _should_terminate) {
1268 break;
1269 }
1270
1271 remaining = PeriodicTask::time_to_wait();
1272 if (remaining == 0) {
1273 // Last task was just disenrolled so loop around and wait until
1274 // another task gets enrolled
1275 continue;
1276 }
1277
1278 remaining -= time_slept;
1279 if (remaining <= 0) {
1280 break;
1281 }
1282 }
1283
1284 return time_slept;
1285 }
1286
1287 void WatcherThread::run() {
1288 assert(this == watcher_thread(), "just checking");
1289
1290 this->record_stack_base_and_size();
1291 this->set_native_thread_name(this->name());
1292 this->set_active_handles(JNIHandleBlock::allocate_block());
1293 while (true) {
1294 assert(watcher_thread() == Thread::current(), "thread consistency check");
1295 assert(watcher_thread() == this, "thread consistency check");
1296
1297 // Calculate how long it'll be until the next PeriodicTask work
1298 // should be done, and sleep that amount of time.
1299 int time_waited = sleep();
1300
1301 if (is_error_reported()) {
1302 // A fatal error has happened, the error handler(VMError::report_and_die)
1303 // should abort JVM after creating an error log file. However in some
1304 // rare cases, the error handler itself might deadlock. Here we try to
1305 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1306 //
1307 // This code is in WatcherThread because WatcherThread wakes up
1308 // periodically so the fatal error handler doesn't need to do anything;
1309 // also because the WatcherThread is less likely to crash than other
1310 // threads.
1311
1312 for (;;) {
1313 if (!ShowMessageBoxOnError
1314 && (OnError == NULL || OnError[0] == '\0')
1315 && Arguments::abort_hook() == NULL) {
1316 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1317 fdStream err(defaultStream::output_fd());
1318 err.print_raw_cr("# [ timer expired, abort... ]");
1319 // skip atexit/vm_exit/vm_abort hooks
1320 os::die();
1321 }
1322
1323 // Wake up 5 seconds later, the fatal handler may reset OnError or
1324 // ShowMessageBoxOnError when it is ready to abort.
1325 os::sleep(this, 5 * 1000, false);
1326 }
1327 }
1328
1329 if (_should_terminate) {
1330 // check for termination before posting the next tick
1331 break;
1332 }
1333
1334 PeriodicTask::real_time_tick(time_waited);
1335 }
1336
1337 // Signal that it is terminated
1338 {
1339 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1340 _watcher_thread = NULL;
1341 Terminator_lock->notify();
1342 }
1343 }
1344
1345 void WatcherThread::start() {
1346 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1347
1348 if (watcher_thread() == NULL && _startable) {
1349 _should_terminate = false;
1350 // Create the single instance of WatcherThread
1351 new WatcherThread();
1352 }
1353 }
1354
1355 void WatcherThread::make_startable() {
1356 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1357 _startable = true;
1358 }
1359
1360 void WatcherThread::stop() {
1361 {
1362 // Follow normal safepoint aware lock enter protocol since the
1363 // WatcherThread is stopped by another JavaThread.
1364 MutexLocker ml(PeriodicTask_lock);
1365 _should_terminate = true;
1366
1367 WatcherThread* watcher = watcher_thread();
1368 if (watcher != NULL) {
1369 // unpark the WatcherThread so it can see that it should terminate
1370 watcher->unpark();
1371 }
1372 }
1373
1374 MutexLocker mu(Terminator_lock);
1375
1376 while (watcher_thread() != NULL) {
1377 // This wait should make safepoint checks, wait without a timeout,
1378 // and wait as a suspend-equivalent condition.
1379 //
1380 // Note: If the FlatProfiler is running, then this thread is waiting
1381 // for the WatcherThread to terminate and the WatcherThread, via the
1382 // FlatProfiler task, is waiting for the external suspend request on
1383 // this thread to complete. wait_for_ext_suspend_completion() will
1384 // eventually timeout, but that takes time. Making this wait a
1385 // suspend-equivalent condition solves that timeout problem.
1386 //
1387 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1388 Mutex::_as_suspend_equivalent_flag);
1389 }
1390 }
1391
1392 void WatcherThread::unpark() {
1393 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1394 PeriodicTask_lock->notify();
1395 }
1396
1397 void WatcherThread::print_on(outputStream* st) const {
1398 st->print("\"%s\" ", name());
1399 Thread::print_on(st);
1400 st->cr();
1401 }
1402
1403 // ======= JavaThread ========
1404
1405 #if INCLUDE_JVMCI
1406
1407 jlong* JavaThread::_jvmci_old_thread_counters;
1408
1409 bool jvmci_counters_include(JavaThread* thread) {
1410 oop threadObj = thread->threadObj();
1411 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1412 }
1413
1414 void JavaThread::collect_counters(typeArrayOop array) {
1415 if (JVMCICounterSize > 0) {
1416 MutexLocker tl(Threads_lock);
1417 for (int i = 0; i < array->length(); i++) {
1418 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1419 }
1420 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1421 if (jvmci_counters_include(tp)) {
1422 for (int i = 0; i < array->length(); i++) {
1423 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1424 }
1425 }
1426 }
1427 }
1428 }
1429
1430 #endif // INCLUDE_JVMCI
1431
1432 // A JavaThread is a normal Java thread
1433
1434 void JavaThread::initialize() {
1435 // Initialize fields
1436
1437 set_saved_exception_pc(NULL);
1438 set_threadObj(NULL);
1439 _anchor.clear();
1440 set_entry_point(NULL);
1441 set_jni_functions(jni_functions());
1442 set_callee_target(NULL);
1443 set_vm_result(NULL);
1444 set_vm_result_2(NULL);
1445 set_vframe_array_head(NULL);
1446 set_vframe_array_last(NULL);
1447 set_deferred_locals(NULL);
1448 set_deopt_mark(NULL);
1449 set_deopt_compiled_method(NULL);
1450 clear_must_deopt_id();
1451 set_monitor_chunks(NULL);
1452 set_next(NULL);
1453 set_thread_state(_thread_new);
1454 _terminated = _not_terminated;
1455 _privileged_stack_top = NULL;
1456 _array_for_gc = NULL;
1457 _suspend_equivalent = false;
1458 _in_deopt_handler = 0;
1459 _doing_unsafe_access = false;
1460 _stack_guard_state = stack_guard_unused;
1461 #if INCLUDE_JVMCI
1462 _pending_monitorenter = false;
1463 _pending_deoptimization = -1;
1464 _pending_failed_speculation = NULL;
1465 _pending_transfer_to_interpreter = false;
1466 _adjusting_comp_level = false;
1467 _jvmci._alternate_call_target = NULL;
1468 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1469 if (JVMCICounterSize > 0) {
1470 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1471 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1472 } else {
1473 _jvmci_counters = NULL;
1474 }
1475 #endif // INCLUDE_JVMCI
1476 _reserved_stack_activation = NULL; // stack base not known yet
1477 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1478 _exception_pc = 0;
1479 _exception_handler_pc = 0;
1480 _is_method_handle_return = 0;
1481 _jvmti_thread_state= NULL;
1482 _should_post_on_exceptions_flag = JNI_FALSE;
1483 _jvmti_get_loaded_classes_closure = NULL;
1484 _interp_only_mode = 0;
1485 _special_runtime_exit_condition = _no_async_condition;
1486 _pending_async_exception = NULL;
1487 _thread_stat = NULL;
1488 _thread_stat = new ThreadStatistics();
1489 _blocked_on_compilation = false;
1490 _jni_active_critical = 0;
1491 _pending_jni_exception_check_fn = NULL;
1492 _do_not_unlock_if_synchronized = false;
1493 _cached_monitor_info = NULL;
1494 _parker = Parker::Allocate(this);
1495
1496 #ifndef PRODUCT
1497 _jmp_ring_index = 0;
1498 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1499 record_jump(NULL, NULL, NULL, 0);
1500 }
1501 #endif // PRODUCT
1502
1503 set_thread_profiler(NULL);
1504 if (FlatProfiler::is_active()) {
1505 // This is where we would decide to either give each thread it's own profiler
1506 // or use one global one from FlatProfiler,
1507 // or up to some count of the number of profiled threads, etc.
1508 ThreadProfiler* pp = new ThreadProfiler();
1509 pp->engage();
1510 set_thread_profiler(pp);
1511 }
1512
1513 // Setup safepoint state info for this thread
1514 ThreadSafepointState::create(this);
1515
1516 debug_only(_java_call_counter = 0);
1517
1518 // JVMTI PopFrame support
1519 _popframe_condition = popframe_inactive;
1520 _popframe_preserved_args = NULL;
1521 _popframe_preserved_args_size = 0;
1522 _frames_to_pop_failed_realloc = 0;
1523
1524 pd_initialize();
1525 }
1526
1527 #if INCLUDE_ALL_GCS
1528 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1529 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1530 bool JavaThread::_evacuation_in_progress_global = false;
1531 #endif // INCLUDE_ALL_GCS
1532
1533 JavaThread::JavaThread(bool is_attaching_via_jni) :
1534 Thread()
1535 #if INCLUDE_ALL_GCS
1536 , _satb_mark_queue(&_satb_mark_queue_set),
1537 _dirty_card_queue(&_dirty_card_queue_set),
1538 _evacuation_in_progress(_evacuation_in_progress_global)
1539 #endif // INCLUDE_ALL_GCS
1540 {
1541 initialize();
1542 if (is_attaching_via_jni) {
1543 _jni_attach_state = _attaching_via_jni;
1544 } else {
1545 _jni_attach_state = _not_attaching_via_jni;
1546 }
1547 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1548 }
1549
1550 bool JavaThread::reguard_stack(address cur_sp) {
1551 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1552 && _stack_guard_state != stack_guard_reserved_disabled) {
1553 return true; // Stack already guarded or guard pages not needed.
1554 }
1555
1556 if (register_stack_overflow()) {
1557 // For those architectures which have separate register and
1558 // memory stacks, we must check the register stack to see if
1559 // it has overflowed.
1560 return false;
1561 }
1562
1563 // Java code never executes within the yellow zone: the latter is only
1564 // there to provoke an exception during stack banging. If java code
1565 // is executing there, either StackShadowPages should be larger, or
1566 // some exception code in c1, c2 or the interpreter isn't unwinding
1567 // when it should.
1568 guarantee(cur_sp > stack_reserved_zone_base(),
1569 "not enough space to reguard - increase StackShadowPages");
1570 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1571 enable_stack_yellow_reserved_zone();
1572 if (reserved_stack_activation() != stack_base()) {
1573 set_reserved_stack_activation(stack_base());
1574 }
1575 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1576 set_reserved_stack_activation(stack_base());
1577 enable_stack_reserved_zone();
1578 }
1579 return true;
1580 }
1581
1582 bool JavaThread::reguard_stack(void) {
1583 return reguard_stack(os::current_stack_pointer());
1584 }
1585
1586
1587 void JavaThread::block_if_vm_exited() {
1588 if (_terminated == _vm_exited) {
1589 // _vm_exited is set at safepoint, and Threads_lock is never released
1590 // we will block here forever
1591 Threads_lock->lock_without_safepoint_check();
1592 ShouldNotReachHere();
1593 }
1594 }
1595
1596
1597 // Remove this ifdef when C1 is ported to the compiler interface.
1598 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1599 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1600
1601 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1602 Thread()
1603 #if INCLUDE_ALL_GCS
1604 , _satb_mark_queue(&_satb_mark_queue_set),
1605 _dirty_card_queue(&_dirty_card_queue_set),
1606 _evacuation_in_progress(_evacuation_in_progress_global)
1607 #endif // INCLUDE_ALL_GCS
1608 {
1609 initialize();
1610 _jni_attach_state = _not_attaching_via_jni;
1611 set_entry_point(entry_point);
1612 // Create the native thread itself.
1613 // %note runtime_23
1614 os::ThreadType thr_type = os::java_thread;
1615 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1616 os::java_thread;
1617 os::create_thread(this, thr_type, stack_sz);
1618 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1619 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1620 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1621 // the exception consists of creating the exception object & initializing it, initialization
1622 // will leave the VM via a JavaCall and then all locks must be unlocked).
1623 //
1624 // The thread is still suspended when we reach here. Thread must be explicit started
1625 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1626 // by calling Threads:add. The reason why this is not done here, is because the thread
1627 // object must be fully initialized (take a look at JVM_Start)
1628 }
1629
1630 JavaThread::~JavaThread() {
1631
1632 // JSR166 -- return the parker to the free list
1633 Parker::Release(_parker);
1634 _parker = NULL;
1635
1636 // Free any remaining previous UnrollBlock
1637 vframeArray* old_array = vframe_array_last();
1638
1639 if (old_array != NULL) {
1640 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1641 old_array->set_unroll_block(NULL);
1642 delete old_info;
1643 delete old_array;
1644 }
1645
1646 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1647 if (deferred != NULL) {
1648 // This can only happen if thread is destroyed before deoptimization occurs.
1649 assert(deferred->length() != 0, "empty array!");
1650 do {
1651 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1652 deferred->remove_at(0);
1653 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1654 delete dlv;
1655 } while (deferred->length() != 0);
1656 delete deferred;
1657 }
1658
1659 // All Java related clean up happens in exit
1660 ThreadSafepointState::destroy(this);
1661 if (_thread_profiler != NULL) delete _thread_profiler;
1662 if (_thread_stat != NULL) delete _thread_stat;
1663
1664 #if INCLUDE_JVMCI
1665 if (JVMCICounterSize > 0) {
1666 if (jvmci_counters_include(this)) {
1667 for (int i = 0; i < JVMCICounterSize; i++) {
1668 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1669 }
1670 }
1671 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1672 }
1673 #endif // INCLUDE_JVMCI
1674 }
1675
1676
1677 // The first routine called by a new Java thread
1678 void JavaThread::run() {
1679 // initialize thread-local alloc buffer related fields
1680 this->initialize_tlab();
1681
1682 // used to test validity of stack trace backs
1683 this->record_base_of_stack_pointer();
1684
1685 // Record real stack base and size.
1686 this->record_stack_base_and_size();
1687
1688 this->create_stack_guard_pages();
1689
1690 this->cache_global_variables();
1691
1692 // Thread is now sufficient initialized to be handled by the safepoint code as being
1693 // in the VM. Change thread state from _thread_new to _thread_in_vm
1694 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1695
1696 assert(JavaThread::current() == this, "sanity check");
1697 assert(!Thread::current()->owns_locks(), "sanity check");
1698
1699 DTRACE_THREAD_PROBE(start, this);
1700
1701 // This operation might block. We call that after all safepoint checks for a new thread has
1702 // been completed.
1703 this->set_active_handles(JNIHandleBlock::allocate_block());
1704
1705 if (JvmtiExport::should_post_thread_life()) {
1706 JvmtiExport::post_thread_start(this);
1707 }
1708
1709 EventThreadStart event;
1710 if (event.should_commit()) {
1711 event.set_thread(THREAD_TRACE_ID(this));
1712 event.commit();
1713 }
1714
1715 // We call another function to do the rest so we are sure that the stack addresses used
1716 // from there will be lower than the stack base just computed
1717 thread_main_inner();
1718
1719 // Note, thread is no longer valid at this point!
1720 }
1721
1722
1723 void JavaThread::thread_main_inner() {
1724 assert(JavaThread::current() == this, "sanity check");
1725 assert(this->threadObj() != NULL, "just checking");
1726
1727 // Execute thread entry point unless this thread has a pending exception
1728 // or has been stopped before starting.
1729 // Note: Due to JVM_StopThread we can have pending exceptions already!
1730 if (!this->has_pending_exception() &&
1731 !java_lang_Thread::is_stillborn(this->threadObj())) {
1732 {
1733 ResourceMark rm(this);
1734 this->set_native_thread_name(this->get_thread_name());
1735 }
1736 HandleMark hm(this);
1737 this->entry_point()(this, this);
1738 }
1739
1740 DTRACE_THREAD_PROBE(stop, this);
1741
1742 this->exit(false);
1743 delete this;
1744 }
1745
1746
1747 static void ensure_join(JavaThread* thread) {
1748 // We do not need to grap the Threads_lock, since we are operating on ourself.
1749 Handle threadObj(thread, thread->threadObj());
1750 assert(threadObj.not_null(), "java thread object must exist");
1751 ObjectLocker lock(threadObj, thread);
1752 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1753 thread->clear_pending_exception();
1754 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1755 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1756 // Clear the native thread instance - this makes isAlive return false and allows the join()
1757 // to complete once we've done the notify_all below
1758 java_lang_Thread::set_thread(threadObj(), NULL);
1759 lock.notify_all(thread);
1760 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1761 thread->clear_pending_exception();
1762 }
1763
1764
1765 // For any new cleanup additions, please check to see if they need to be applied to
1766 // cleanup_failed_attach_current_thread as well.
1767 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1768 assert(this == JavaThread::current(), "thread consistency check");
1769
1770 HandleMark hm(this);
1771 Handle uncaught_exception(this, this->pending_exception());
1772 this->clear_pending_exception();
1773 Handle threadObj(this, this->threadObj());
1774 assert(threadObj.not_null(), "Java thread object should be created");
1775
1776 if (get_thread_profiler() != NULL) {
1777 get_thread_profiler()->disengage();
1778 ResourceMark rm;
1779 get_thread_profiler()->print(get_thread_name());
1780 }
1781
1782
1783 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1784 {
1785 EXCEPTION_MARK;
1786
1787 CLEAR_PENDING_EXCEPTION;
1788 }
1789 if (!destroy_vm) {
1790 if (uncaught_exception.not_null()) {
1791 EXCEPTION_MARK;
1792 // Call method Thread.dispatchUncaughtException().
1793 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1794 JavaValue result(T_VOID);
1795 JavaCalls::call_virtual(&result,
1796 threadObj, thread_klass,
1797 vmSymbols::dispatchUncaughtException_name(),
1798 vmSymbols::throwable_void_signature(),
1799 uncaught_exception,
1800 THREAD);
1801 if (HAS_PENDING_EXCEPTION) {
1802 ResourceMark rm(this);
1803 jio_fprintf(defaultStream::error_stream(),
1804 "\nException: %s thrown from the UncaughtExceptionHandler"
1805 " in thread \"%s\"\n",
1806 pending_exception()->klass()->external_name(),
1807 get_thread_name());
1808 CLEAR_PENDING_EXCEPTION;
1809 }
1810 }
1811
1812 // Called before the java thread exit since we want to read info
1813 // from java_lang_Thread object
1814 EventThreadEnd event;
1815 if (event.should_commit()) {
1816 event.set_thread(THREAD_TRACE_ID(this));
1817 event.commit();
1818 }
1819
1820 // Call after last event on thread
1821 EVENT_THREAD_EXIT(this);
1822
1823 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1824 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1825 // is deprecated anyhow.
1826 if (!is_Compiler_thread()) {
1827 int count = 3;
1828 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1829 EXCEPTION_MARK;
1830 JavaValue result(T_VOID);
1831 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1832 JavaCalls::call_virtual(&result,
1833 threadObj, thread_klass,
1834 vmSymbols::exit_method_name(),
1835 vmSymbols::void_method_signature(),
1836 THREAD);
1837 CLEAR_PENDING_EXCEPTION;
1838 }
1839 }
1840 // notify JVMTI
1841 if (JvmtiExport::should_post_thread_life()) {
1842 JvmtiExport::post_thread_end(this);
1843 }
1844
1845 // We have notified the agents that we are exiting, before we go on,
1846 // we must check for a pending external suspend request and honor it
1847 // in order to not surprise the thread that made the suspend request.
1848 while (true) {
1849 {
1850 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1851 if (!is_external_suspend()) {
1852 set_terminated(_thread_exiting);
1853 ThreadService::current_thread_exiting(this);
1854 break;
1855 }
1856 // Implied else:
1857 // Things get a little tricky here. We have a pending external
1858 // suspend request, but we are holding the SR_lock so we
1859 // can't just self-suspend. So we temporarily drop the lock
1860 // and then self-suspend.
1861 }
1862
1863 ThreadBlockInVM tbivm(this);
1864 java_suspend_self();
1865
1866 // We're done with this suspend request, but we have to loop around
1867 // and check again. Eventually we will get SR_lock without a pending
1868 // external suspend request and will be able to mark ourselves as
1869 // exiting.
1870 }
1871 // no more external suspends are allowed at this point
1872 } else {
1873 // before_exit() has already posted JVMTI THREAD_END events
1874 }
1875
1876 // Notify waiters on thread object. This has to be done after exit() is called
1877 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1878 // group should have the destroyed bit set before waiters are notified).
1879 ensure_join(this);
1880 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1881
1882 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1883 // held by this thread must be released. The spec does not distinguish
1884 // between JNI-acquired and regular Java monitors. We can only see
1885 // regular Java monitors here if monitor enter-exit matching is broken.
1886 //
1887 // Optionally release any monitors for regular JavaThread exits. This
1888 // is provided as a work around for any bugs in monitor enter-exit
1889 // matching. This can be expensive so it is not enabled by default.
1890 //
1891 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1892 // ObjectSynchronizer::release_monitors_owned_by_thread().
1893 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1894 // Sanity check even though JNI DetachCurrentThread() would have
1895 // returned JNI_ERR if there was a Java frame. JavaThread exit
1896 // should be done executing Java code by the time we get here.
1897 assert(!this->has_last_Java_frame(),
1898 "should not have a Java frame when detaching or exiting");
1899 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1900 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1901 }
1902
1903 // These things needs to be done while we are still a Java Thread. Make sure that thread
1904 // is in a consistent state, in case GC happens
1905 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1906
1907 if (active_handles() != NULL) {
1908 JNIHandleBlock* block = active_handles();
1909 set_active_handles(NULL);
1910 JNIHandleBlock::release_block(block);
1911 }
1912
1913 if (free_handle_block() != NULL) {
1914 JNIHandleBlock* block = free_handle_block();
1915 set_free_handle_block(NULL);
1916 JNIHandleBlock::release_block(block);
1917 }
1918
1919 // These have to be removed while this is still a valid thread.
1920 remove_stack_guard_pages();
1921
1922 if (UseTLAB) {
1923 tlab().make_parsable(true); // retire TLAB
1924 }
1925
1926 if (JvmtiEnv::environments_might_exist()) {
1927 JvmtiExport::cleanup_thread(this);
1928 }
1929
1930 // We must flush any deferred card marks before removing a thread from
1931 // the list of active threads.
1932 Universe::heap()->flush_deferred_store_barrier(this);
1933 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1934
1935 #if INCLUDE_ALL_GCS
1936 // We must flush the G1-related buffers before removing a thread
1937 // from the list of active threads. We must do this after any deferred
1938 // card marks have been flushed (above) so that any entries that are
1939 // added to the thread's dirty card queue as a result are not lost.
1940 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
1941 flush_barrier_queues();
1942 }
1943 if (UseShenandoahGC && UseTLAB) {
1944 gclab().make_parsable(true);
1945 }
1946 #endif // INCLUDE_ALL_GCS
1947
1948 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1949 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1950 os::current_thread_id());
1951
1952 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1953 Threads::remove(this);
1954 }
1955
1956 #if INCLUDE_ALL_GCS
1957 // Flush G1-related queues.
1958 void JavaThread::flush_barrier_queues() {
1959 satb_mark_queue().flush();
1960 dirty_card_queue().flush();
1961 }
1962
1963 void JavaThread::initialize_queues() {
1964 assert(!SafepointSynchronize::is_at_safepoint(),
1965 "we should not be at a safepoint");
1966
1967 SATBMarkQueue& satb_queue = satb_mark_queue();
1968 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1969 // The SATB queue should have been constructed with its active
1970 // field set to false.
1971 assert(!satb_queue.is_active(), "SATB queue should not be active");
1972 assert(satb_queue.is_empty(), "SATB queue should be empty");
1973 // If we are creating the thread during a marking cycle, we should
1974 // set the active field of the SATB queue to true.
1975 if (satb_queue_set.is_active()) {
1976 satb_queue.set_active(true);
1977 }
1978
1979 DirtyCardQueue& dirty_queue = dirty_card_queue();
1980 // The dirty card queue should have been constructed with its
1981 // active field set to true.
1982 assert(dirty_queue.is_active(), "dirty card queue should be active");
1983
1984 _evacuation_in_progress = _evacuation_in_progress_global;
1985 }
1986
1987 bool JavaThread::evacuation_in_progress() const {
1988 return _evacuation_in_progress;
1989 }
1990
1991 void JavaThread::set_evacuation_in_progress(bool in_prog) {
1992 _evacuation_in_progress = in_prog;
1993 }
1994
1995 void JavaThread::set_evacuation_in_progress_all_threads(bool in_prog) {
1996 assert_locked_or_safepoint(Threads_lock);
1997 _evacuation_in_progress_global = in_prog;
1998 for (JavaThread* t = Threads::first(); t != NULL; t = t->next()) {
1999 t->set_evacuation_in_progress(in_prog);
2000 }
2001 }
2002 #endif // INCLUDE_ALL_GCS
2003
2004 void JavaThread::cleanup_failed_attach_current_thread() {
2005 if (get_thread_profiler() != NULL) {
2006 get_thread_profiler()->disengage();
2007 ResourceMark rm;
2008 get_thread_profiler()->print(get_thread_name());
2009 }
2010
2011 if (active_handles() != NULL) {
2012 JNIHandleBlock* block = active_handles();
2013 set_active_handles(NULL);
2014 JNIHandleBlock::release_block(block);
2015 }
2016
2017 if (free_handle_block() != NULL) {
2018 JNIHandleBlock* block = free_handle_block();
2019 set_free_handle_block(NULL);
2020 JNIHandleBlock::release_block(block);
2021 }
2022
2023 // These have to be removed while this is still a valid thread.
2024 remove_stack_guard_pages();
2025
2026 if (UseTLAB) {
2027 tlab().make_parsable(true); // retire TLAB, if any
2028 }
2029
2030 #if INCLUDE_ALL_GCS
2031 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
2032 flush_barrier_queues();
2033 }
2034 if (UseShenandoahGC && UseTLAB) {
2035 gclab().make_parsable(true);
2036 }
2037 #endif // INCLUDE_ALL_GCS
2038
2039 Threads::remove(this);
2040 delete this;
2041 }
2042
2043
2044
2045
2046 JavaThread* JavaThread::active() {
2047 Thread* thread = Thread::current();
2048 if (thread->is_Java_thread()) {
2049 return (JavaThread*) thread;
2050 } else {
2051 assert(thread->is_VM_thread(), "this must be a vm thread");
2052 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2053 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2054 assert(ret->is_Java_thread(), "must be a Java thread");
2055 return ret;
2056 }
2057 }
2058
2059 bool JavaThread::is_lock_owned(address adr) const {
2060 if (Thread::is_lock_owned(adr)) return true;
2061
2062 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2063 if (chunk->contains(adr)) return true;
2064 }
2065
2066 return false;
2067 }
2068
2069
2070 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2071 chunk->set_next(monitor_chunks());
2072 set_monitor_chunks(chunk);
2073 }
2074
2075 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2076 guarantee(monitor_chunks() != NULL, "must be non empty");
2077 if (monitor_chunks() == chunk) {
2078 set_monitor_chunks(chunk->next());
2079 } else {
2080 MonitorChunk* prev = monitor_chunks();
2081 while (prev->next() != chunk) prev = prev->next();
2082 prev->set_next(chunk->next());
2083 }
2084 }
2085
2086 // JVM support.
2087
2088 // Note: this function shouldn't block if it's called in
2089 // _thread_in_native_trans state (such as from
2090 // check_special_condition_for_native_trans()).
2091 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2092
2093 if (has_last_Java_frame() && has_async_condition()) {
2094 // If we are at a polling page safepoint (not a poll return)
2095 // then we must defer async exception because live registers
2096 // will be clobbered by the exception path. Poll return is
2097 // ok because the call we a returning from already collides
2098 // with exception handling registers and so there is no issue.
2099 // (The exception handling path kills call result registers but
2100 // this is ok since the exception kills the result anyway).
2101
2102 if (is_at_poll_safepoint()) {
2103 // if the code we are returning to has deoptimized we must defer
2104 // the exception otherwise live registers get clobbered on the
2105 // exception path before deoptimization is able to retrieve them.
2106 //
2107 RegisterMap map(this, false);
2108 frame caller_fr = last_frame().sender(&map);
2109 assert(caller_fr.is_compiled_frame(), "what?");
2110 if (caller_fr.is_deoptimized_frame()) {
2111 log_info(exceptions)("deferred async exception at compiled safepoint");
2112 return;
2113 }
2114 }
2115 }
2116
2117 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2118 if (condition == _no_async_condition) {
2119 // Conditions have changed since has_special_runtime_exit_condition()
2120 // was called:
2121 // - if we were here only because of an external suspend request,
2122 // then that was taken care of above (or cancelled) so we are done
2123 // - if we were here because of another async request, then it has
2124 // been cleared between the has_special_runtime_exit_condition()
2125 // and now so again we are done
2126 return;
2127 }
2128
2129 // Check for pending async. exception
2130 if (_pending_async_exception != NULL) {
2131 // Only overwrite an already pending exception, if it is not a threadDeath.
2132 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2133
2134 // We cannot call Exceptions::_throw(...) here because we cannot block
2135 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2136
2137 if (log_is_enabled(Info, exceptions)) {
2138 ResourceMark rm;
2139 outputStream* logstream = Log(exceptions)::info_stream();
2140 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2141 if (has_last_Java_frame()) {
2142 frame f = last_frame();
2143 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2144 }
2145 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2146 }
2147 _pending_async_exception = NULL;
2148 clear_has_async_exception();
2149 }
2150 }
2151
2152 if (check_unsafe_error &&
2153 condition == _async_unsafe_access_error && !has_pending_exception()) {
2154 condition = _no_async_condition; // done
2155 switch (thread_state()) {
2156 case _thread_in_vm: {
2157 JavaThread* THREAD = this;
2158 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2159 }
2160 case _thread_in_native: {
2161 ThreadInVMfromNative tiv(this);
2162 JavaThread* THREAD = this;
2163 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2164 }
2165 case _thread_in_Java: {
2166 ThreadInVMfromJava tiv(this);
2167 JavaThread* THREAD = this;
2168 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2169 }
2170 default:
2171 ShouldNotReachHere();
2172 }
2173 }
2174
2175 assert(condition == _no_async_condition || has_pending_exception() ||
2176 (!check_unsafe_error && condition == _async_unsafe_access_error),
2177 "must have handled the async condition, if no exception");
2178 }
2179
2180 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2181 //
2182 // Check for pending external suspend. Internal suspend requests do
2183 // not use handle_special_runtime_exit_condition().
2184 // If JNIEnv proxies are allowed, don't self-suspend if the target
2185 // thread is not the current thread. In older versions of jdbx, jdbx
2186 // threads could call into the VM with another thread's JNIEnv so we
2187 // can be here operating on behalf of a suspended thread (4432884).
2188 bool do_self_suspend = is_external_suspend_with_lock();
2189 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2190 //
2191 // Because thread is external suspended the safepoint code will count
2192 // thread as at a safepoint. This can be odd because we can be here
2193 // as _thread_in_Java which would normally transition to _thread_blocked
2194 // at a safepoint. We would like to mark the thread as _thread_blocked
2195 // before calling java_suspend_self like all other callers of it but
2196 // we must then observe proper safepoint protocol. (We can't leave
2197 // _thread_blocked with a safepoint in progress). However we can be
2198 // here as _thread_in_native_trans so we can't use a normal transition
2199 // constructor/destructor pair because they assert on that type of
2200 // transition. We could do something like:
2201 //
2202 // JavaThreadState state = thread_state();
2203 // set_thread_state(_thread_in_vm);
2204 // {
2205 // ThreadBlockInVM tbivm(this);
2206 // java_suspend_self()
2207 // }
2208 // set_thread_state(_thread_in_vm_trans);
2209 // if (safepoint) block;
2210 // set_thread_state(state);
2211 //
2212 // but that is pretty messy. Instead we just go with the way the
2213 // code has worked before and note that this is the only path to
2214 // java_suspend_self that doesn't put the thread in _thread_blocked
2215 // mode.
2216
2217 frame_anchor()->make_walkable(this);
2218 java_suspend_self();
2219
2220 // We might be here for reasons in addition to the self-suspend request
2221 // so check for other async requests.
2222 }
2223
2224 if (check_asyncs) {
2225 check_and_handle_async_exceptions();
2226 }
2227 }
2228
2229 void JavaThread::send_thread_stop(oop java_throwable) {
2230 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2231 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2232 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2233
2234 // Do not throw asynchronous exceptions against the compiler thread
2235 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2236 if (!can_call_java()) return;
2237
2238 {
2239 // Actually throw the Throwable against the target Thread - however
2240 // only if there is no thread death exception installed already.
2241 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2242 // If the topmost frame is a runtime stub, then we are calling into
2243 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2244 // must deoptimize the caller before continuing, as the compiled exception handler table
2245 // may not be valid
2246 if (has_last_Java_frame()) {
2247 frame f = last_frame();
2248 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2249 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2250 RegisterMap reg_map(this, UseBiasedLocking);
2251 frame compiled_frame = f.sender(®_map);
2252 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2253 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2254 }
2255 }
2256 }
2257
2258 // Set async. pending exception in thread.
2259 set_pending_async_exception(java_throwable);
2260
2261 if (log_is_enabled(Info, exceptions)) {
2262 ResourceMark rm;
2263 log_info(exceptions)("Pending Async. exception installed of type: %s",
2264 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2265 }
2266 // for AbortVMOnException flag
2267 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2268 }
2269 }
2270
2271
2272 // Interrupt thread so it will wake up from a potential wait()
2273 Thread::interrupt(this);
2274 }
2275
2276 // External suspension mechanism.
2277 //
2278 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2279 // to any VM_locks and it is at a transition
2280 // Self-suspension will happen on the transition out of the vm.
2281 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2282 //
2283 // Guarantees on return:
2284 // + Target thread will not execute any new bytecode (that's why we need to
2285 // force a safepoint)
2286 // + Target thread will not enter any new monitors
2287 //
2288 void JavaThread::java_suspend() {
2289 { MutexLocker mu(Threads_lock);
2290 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2291 return;
2292 }
2293 }
2294
2295 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2296 if (!is_external_suspend()) {
2297 // a racing resume has cancelled us; bail out now
2298 return;
2299 }
2300
2301 // suspend is done
2302 uint32_t debug_bits = 0;
2303 // Warning: is_ext_suspend_completed() may temporarily drop the
2304 // SR_lock to allow the thread to reach a stable thread state if
2305 // it is currently in a transient thread state.
2306 if (is_ext_suspend_completed(false /* !called_by_wait */,
2307 SuspendRetryDelay, &debug_bits)) {
2308 return;
2309 }
2310 }
2311
2312 VM_ForceSafepoint vm_suspend;
2313 VMThread::execute(&vm_suspend);
2314 }
2315
2316 // Part II of external suspension.
2317 // A JavaThread self suspends when it detects a pending external suspend
2318 // request. This is usually on transitions. It is also done in places
2319 // where continuing to the next transition would surprise the caller,
2320 // e.g., monitor entry.
2321 //
2322 // Returns the number of times that the thread self-suspended.
2323 //
2324 // Note: DO NOT call java_suspend_self() when you just want to block current
2325 // thread. java_suspend_self() is the second stage of cooperative
2326 // suspension for external suspend requests and should only be used
2327 // to complete an external suspend request.
2328 //
2329 int JavaThread::java_suspend_self() {
2330 int ret = 0;
2331
2332 // we are in the process of exiting so don't suspend
2333 if (is_exiting()) {
2334 clear_external_suspend();
2335 return ret;
2336 }
2337
2338 assert(_anchor.walkable() ||
2339 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2340 "must have walkable stack");
2341
2342 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2343
2344 assert(!this->is_ext_suspended(),
2345 "a thread trying to self-suspend should not already be suspended");
2346
2347 if (this->is_suspend_equivalent()) {
2348 // If we are self-suspending as a result of the lifting of a
2349 // suspend equivalent condition, then the suspend_equivalent
2350 // flag is not cleared until we set the ext_suspended flag so
2351 // that wait_for_ext_suspend_completion() returns consistent
2352 // results.
2353 this->clear_suspend_equivalent();
2354 }
2355
2356 // A racing resume may have cancelled us before we grabbed SR_lock
2357 // above. Or another external suspend request could be waiting for us
2358 // by the time we return from SR_lock()->wait(). The thread
2359 // that requested the suspension may already be trying to walk our
2360 // stack and if we return now, we can change the stack out from under
2361 // it. This would be a "bad thing (TM)" and cause the stack walker
2362 // to crash. We stay self-suspended until there are no more pending
2363 // external suspend requests.
2364 while (is_external_suspend()) {
2365 ret++;
2366 this->set_ext_suspended();
2367
2368 // _ext_suspended flag is cleared by java_resume()
2369 while (is_ext_suspended()) {
2370 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2371 }
2372 }
2373
2374 return ret;
2375 }
2376
2377 #ifdef ASSERT
2378 // verify the JavaThread has not yet been published in the Threads::list, and
2379 // hence doesn't need protection from concurrent access at this stage
2380 void JavaThread::verify_not_published() {
2381 if (!Threads_lock->owned_by_self()) {
2382 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2383 assert(!Threads::includes(this),
2384 "java thread shouldn't have been published yet!");
2385 } else {
2386 assert(!Threads::includes(this),
2387 "java thread shouldn't have been published yet!");
2388 }
2389 }
2390 #endif
2391
2392 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2393 // progress or when _suspend_flags is non-zero.
2394 // Current thread needs to self-suspend if there is a suspend request and/or
2395 // block if a safepoint is in progress.
2396 // Async exception ISN'T checked.
2397 // Note only the ThreadInVMfromNative transition can call this function
2398 // directly and when thread state is _thread_in_native_trans
2399 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2400 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2401
2402 JavaThread *curJT = JavaThread::current();
2403 bool do_self_suspend = thread->is_external_suspend();
2404
2405 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2406
2407 // If JNIEnv proxies are allowed, don't self-suspend if the target
2408 // thread is not the current thread. In older versions of jdbx, jdbx
2409 // threads could call into the VM with another thread's JNIEnv so we
2410 // can be here operating on behalf of a suspended thread (4432884).
2411 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2412 JavaThreadState state = thread->thread_state();
2413
2414 // We mark this thread_blocked state as a suspend-equivalent so
2415 // that a caller to is_ext_suspend_completed() won't be confused.
2416 // The suspend-equivalent state is cleared by java_suspend_self().
2417 thread->set_suspend_equivalent();
2418
2419 // If the safepoint code sees the _thread_in_native_trans state, it will
2420 // wait until the thread changes to other thread state. There is no
2421 // guarantee on how soon we can obtain the SR_lock and complete the
2422 // self-suspend request. It would be a bad idea to let safepoint wait for
2423 // too long. Temporarily change the state to _thread_blocked to
2424 // let the VM thread know that this thread is ready for GC. The problem
2425 // of changing thread state is that safepoint could happen just after
2426 // java_suspend_self() returns after being resumed, and VM thread will
2427 // see the _thread_blocked state. We must check for safepoint
2428 // after restoring the state and make sure we won't leave while a safepoint
2429 // is in progress.
2430 thread->set_thread_state(_thread_blocked);
2431 thread->java_suspend_self();
2432 thread->set_thread_state(state);
2433 // Make sure new state is seen by VM thread
2434 if (os::is_MP()) {
2435 if (UseMembar) {
2436 // Force a fence between the write above and read below
2437 OrderAccess::fence();
2438 } else {
2439 // Must use this rather than serialization page in particular on Windows
2440 InterfaceSupport::serialize_memory(thread);
2441 }
2442 }
2443 }
2444
2445 if (SafepointSynchronize::do_call_back()) {
2446 // If we are safepointing, then block the caller which may not be
2447 // the same as the target thread (see above).
2448 SafepointSynchronize::block(curJT);
2449 }
2450
2451 if (thread->is_deopt_suspend()) {
2452 thread->clear_deopt_suspend();
2453 RegisterMap map(thread, false);
2454 frame f = thread->last_frame();
2455 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2456 f = f.sender(&map);
2457 }
2458 if (f.id() == thread->must_deopt_id()) {
2459 thread->clear_must_deopt_id();
2460 f.deoptimize(thread);
2461 } else {
2462 fatal("missed deoptimization!");
2463 }
2464 }
2465 }
2466
2467 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2468 // progress or when _suspend_flags is non-zero.
2469 // Current thread needs to self-suspend if there is a suspend request and/or
2470 // block if a safepoint is in progress.
2471 // Also check for pending async exception (not including unsafe access error).
2472 // Note only the native==>VM/Java barriers can call this function and when
2473 // thread state is _thread_in_native_trans.
2474 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2475 check_safepoint_and_suspend_for_native_trans(thread);
2476
2477 if (thread->has_async_exception()) {
2478 // We are in _thread_in_native_trans state, don't handle unsafe
2479 // access error since that may block.
2480 thread->check_and_handle_async_exceptions(false);
2481 }
2482 }
2483
2484 // This is a variant of the normal
2485 // check_special_condition_for_native_trans with slightly different
2486 // semantics for use by critical native wrappers. It does all the
2487 // normal checks but also performs the transition back into
2488 // thread_in_Java state. This is required so that critical natives
2489 // can potentially block and perform a GC if they are the last thread
2490 // exiting the GCLocker.
2491 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2492 check_special_condition_for_native_trans(thread);
2493
2494 // Finish the transition
2495 thread->set_thread_state(_thread_in_Java);
2496
2497 if (thread->do_critical_native_unlock()) {
2498 ThreadInVMfromJavaNoAsyncException tiv(thread);
2499 GCLocker::unlock_critical(thread);
2500 thread->clear_critical_native_unlock();
2501 }
2502 }
2503
2504 // We need to guarantee the Threads_lock here, since resumes are not
2505 // allowed during safepoint synchronization
2506 // Can only resume from an external suspension
2507 void JavaThread::java_resume() {
2508 assert_locked_or_safepoint(Threads_lock);
2509
2510 // Sanity check: thread is gone, has started exiting or the thread
2511 // was not externally suspended.
2512 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2513 return;
2514 }
2515
2516 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2517
2518 clear_external_suspend();
2519
2520 if (is_ext_suspended()) {
2521 clear_ext_suspended();
2522 SR_lock()->notify_all();
2523 }
2524 }
2525
2526 size_t JavaThread::_stack_red_zone_size = 0;
2527 size_t JavaThread::_stack_yellow_zone_size = 0;
2528 size_t JavaThread::_stack_reserved_zone_size = 0;
2529 size_t JavaThread::_stack_shadow_zone_size = 0;
2530
2531 void JavaThread::create_stack_guard_pages() {
2532 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2533 address low_addr = stack_end();
2534 size_t len = stack_guard_zone_size();
2535
2536 int must_commit = os::must_commit_stack_guard_pages();
2537 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2538
2539 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2540 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2541 return;
2542 }
2543
2544 if (os::guard_memory((char *) low_addr, len)) {
2545 _stack_guard_state = stack_guard_enabled;
2546 } else {
2547 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2548 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2549 if (os::uncommit_memory((char *) low_addr, len)) {
2550 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2551 }
2552 return;
2553 }
2554
2555 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2556 PTR_FORMAT "-" PTR_FORMAT ".",
2557 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2558 }
2559
2560 void JavaThread::remove_stack_guard_pages() {
2561 assert(Thread::current() == this, "from different thread");
2562 if (_stack_guard_state == stack_guard_unused) return;
2563 address low_addr = stack_end();
2564 size_t len = stack_guard_zone_size();
2565
2566 if (os::must_commit_stack_guard_pages()) {
2567 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2568 _stack_guard_state = stack_guard_unused;
2569 } else {
2570 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2571 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2572 return;
2573 }
2574 } else {
2575 if (_stack_guard_state == stack_guard_unused) return;
2576 if (os::unguard_memory((char *) low_addr, len)) {
2577 _stack_guard_state = stack_guard_unused;
2578 } else {
2579 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2580 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2581 return;
2582 }
2583 }
2584
2585 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2586 PTR_FORMAT "-" PTR_FORMAT ".",
2587 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2588 }
2589
2590 void JavaThread::enable_stack_reserved_zone() {
2591 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2592 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2593
2594 // The base notation is from the stack's point of view, growing downward.
2595 // We need to adjust it to work correctly with guard_memory()
2596 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2597
2598 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2599 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2600
2601 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2602 _stack_guard_state = stack_guard_enabled;
2603 } else {
2604 warning("Attempt to guard stack reserved zone failed.");
2605 }
2606 enable_register_stack_guard();
2607 }
2608
2609 void JavaThread::disable_stack_reserved_zone() {
2610 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2611 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2612
2613 // Simply return if called for a thread that does not use guard pages.
2614 if (_stack_guard_state == stack_guard_unused) return;
2615
2616 // The base notation is from the stack's point of view, growing downward.
2617 // We need to adjust it to work correctly with guard_memory()
2618 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2619
2620 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2621 _stack_guard_state = stack_guard_reserved_disabled;
2622 } else {
2623 warning("Attempt to unguard stack reserved zone failed.");
2624 }
2625 disable_register_stack_guard();
2626 }
2627
2628 void JavaThread::enable_stack_yellow_reserved_zone() {
2629 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2630 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2631
2632 // The base notation is from the stacks point of view, growing downward.
2633 // We need to adjust it to work correctly with guard_memory()
2634 address base = stack_red_zone_base();
2635
2636 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2637 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2638
2639 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2640 _stack_guard_state = stack_guard_enabled;
2641 } else {
2642 warning("Attempt to guard stack yellow zone failed.");
2643 }
2644 enable_register_stack_guard();
2645 }
2646
2647 void JavaThread::disable_stack_yellow_reserved_zone() {
2648 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2649 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2650
2651 // Simply return if called for a thread that does not use guard pages.
2652 if (_stack_guard_state == stack_guard_unused) return;
2653
2654 // The base notation is from the stacks point of view, growing downward.
2655 // We need to adjust it to work correctly with guard_memory()
2656 address base = stack_red_zone_base();
2657
2658 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2659 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2660 } else {
2661 warning("Attempt to unguard stack yellow zone failed.");
2662 }
2663 disable_register_stack_guard();
2664 }
2665
2666 void JavaThread::enable_stack_red_zone() {
2667 // The base notation is from the stacks point of view, growing downward.
2668 // We need to adjust it to work correctly with guard_memory()
2669 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2670 address base = stack_red_zone_base() - stack_red_zone_size();
2671
2672 guarantee(base < stack_base(), "Error calculating stack red zone");
2673 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2674
2675 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2676 warning("Attempt to guard stack red zone failed.");
2677 }
2678 }
2679
2680 void JavaThread::disable_stack_red_zone() {
2681 // The base notation is from the stacks point of view, growing downward.
2682 // We need to adjust it to work correctly with guard_memory()
2683 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2684 address base = stack_red_zone_base() - stack_red_zone_size();
2685 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2686 warning("Attempt to unguard stack red zone failed.");
2687 }
2688 }
2689
2690 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2691 // ignore is there is no stack
2692 if (!has_last_Java_frame()) return;
2693 // traverse the stack frames. Starts from top frame.
2694 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2695 frame* fr = fst.current();
2696 f(fr, fst.register_map());
2697 }
2698 }
2699
2700
2701 #ifndef PRODUCT
2702 // Deoptimization
2703 // Function for testing deoptimization
2704 void JavaThread::deoptimize() {
2705 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2706 StackFrameStream fst(this, UseBiasedLocking);
2707 bool deopt = false; // Dump stack only if a deopt actually happens.
2708 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2709 // Iterate over all frames in the thread and deoptimize
2710 for (; !fst.is_done(); fst.next()) {
2711 if (fst.current()->can_be_deoptimized()) {
2712
2713 if (only_at) {
2714 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2715 // consists of comma or carriage return separated numbers so
2716 // search for the current bci in that string.
2717 address pc = fst.current()->pc();
2718 nmethod* nm = (nmethod*) fst.current()->cb();
2719 ScopeDesc* sd = nm->scope_desc_at(pc);
2720 char buffer[8];
2721 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2722 size_t len = strlen(buffer);
2723 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2724 while (found != NULL) {
2725 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2726 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2727 // Check that the bci found is bracketed by terminators.
2728 break;
2729 }
2730 found = strstr(found + 1, buffer);
2731 }
2732 if (!found) {
2733 continue;
2734 }
2735 }
2736
2737 if (DebugDeoptimization && !deopt) {
2738 deopt = true; // One-time only print before deopt
2739 tty->print_cr("[BEFORE Deoptimization]");
2740 trace_frames();
2741 trace_stack();
2742 }
2743 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2744 }
2745 }
2746
2747 if (DebugDeoptimization && deopt) {
2748 tty->print_cr("[AFTER Deoptimization]");
2749 trace_frames();
2750 }
2751 }
2752
2753
2754 // Make zombies
2755 void JavaThread::make_zombies() {
2756 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2757 if (fst.current()->can_be_deoptimized()) {
2758 // it is a Java nmethod
2759 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2760 nm->make_not_entrant();
2761 }
2762 }
2763 }
2764 #endif // PRODUCT
2765
2766
2767 void JavaThread::deoptimized_wrt_marked_nmethods() {
2768 if (!has_last_Java_frame()) return;
2769 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2770 StackFrameStream fst(this, UseBiasedLocking);
2771 for (; !fst.is_done(); fst.next()) {
2772 if (fst.current()->should_be_deoptimized()) {
2773 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2774 }
2775 }
2776 }
2777
2778
2779 // If the caller is a NamedThread, then remember, in the current scope,
2780 // the given JavaThread in its _processed_thread field.
2781 class RememberProcessedThread: public StackObj {
2782 NamedThread* _cur_thr;
2783 public:
2784 RememberProcessedThread(JavaThread* jthr) {
2785 Thread* thread = Thread::current();
2786 if (thread->is_Named_thread()) {
2787 _cur_thr = (NamedThread *)thread;
2788 _cur_thr->set_processed_thread(jthr);
2789 } else {
2790 _cur_thr = NULL;
2791 }
2792 }
2793
2794 ~RememberProcessedThread() {
2795 if (_cur_thr) {
2796 _cur_thr->set_processed_thread(NULL);
2797 }
2798 }
2799 };
2800
2801 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2802 // Verify that the deferred card marks have been flushed.
2803 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2804
2805 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2806 // since there may be more than one thread using each ThreadProfiler.
2807
2808 // Traverse the GCHandles
2809 Thread::oops_do(f, cf);
2810
2811 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2812
2813 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2814 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2815
2816 if (has_last_Java_frame()) {
2817 // Record JavaThread to GC thread
2818 RememberProcessedThread rpt(this);
2819
2820 // Traverse the privileged stack
2821 if (_privileged_stack_top != NULL) {
2822 _privileged_stack_top->oops_do(f);
2823 }
2824
2825 // traverse the registered growable array
2826 if (_array_for_gc != NULL) {
2827 for (int index = 0; index < _array_for_gc->length(); index++) {
2828 f->do_oop(_array_for_gc->adr_at(index));
2829 }
2830 }
2831
2832 // Traverse the monitor chunks
2833 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2834 chunk->oops_do(f);
2835 }
2836
2837 // Traverse the execution stack
2838 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2839 fst.current()->oops_do(f, cf, fst.register_map());
2840 }
2841 }
2842
2843 // callee_target is never live across a gc point so NULL it here should
2844 // it still contain a methdOop.
2845
2846 set_callee_target(NULL);
2847
2848 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2849 // If we have deferred set_locals there might be oops waiting to be
2850 // written
2851 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2852 if (list != NULL) {
2853 for (int i = 0; i < list->length(); i++) {
2854 list->at(i)->oops_do(f);
2855 }
2856 }
2857
2858 // Traverse instance variables at the end since the GC may be moving things
2859 // around using this function
2860 f->do_oop((oop*) &_threadObj);
2861 f->do_oop((oop*) &_vm_result);
2862 f->do_oop((oop*) &_exception_oop);
2863 f->do_oop((oop*) &_pending_async_exception);
2864
2865 if (jvmti_thread_state() != NULL) {
2866 jvmti_thread_state()->oops_do(f);
2867 }
2868 }
2869
2870 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2871 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2872 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2873
2874 if (has_last_Java_frame()) {
2875 // Traverse the execution stack
2876 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2877 fst.current()->nmethods_do(cf);
2878 }
2879 }
2880 }
2881
2882 void JavaThread::metadata_do(void f(Metadata*)) {
2883 if (has_last_Java_frame()) {
2884 // Traverse the execution stack to call f() on the methods in the stack
2885 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2886 fst.current()->metadata_do(f);
2887 }
2888 } else if (is_Compiler_thread()) {
2889 // need to walk ciMetadata in current compile tasks to keep alive.
2890 CompilerThread* ct = (CompilerThread*)this;
2891 if (ct->env() != NULL) {
2892 ct->env()->metadata_do(f);
2893 }
2894 if (ct->task() != NULL) {
2895 ct->task()->metadata_do(f);
2896 }
2897 }
2898 }
2899
2900 // Printing
2901 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2902 switch (_thread_state) {
2903 case _thread_uninitialized: return "_thread_uninitialized";
2904 case _thread_new: return "_thread_new";
2905 case _thread_new_trans: return "_thread_new_trans";
2906 case _thread_in_native: return "_thread_in_native";
2907 case _thread_in_native_trans: return "_thread_in_native_trans";
2908 case _thread_in_vm: return "_thread_in_vm";
2909 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2910 case _thread_in_Java: return "_thread_in_Java";
2911 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2912 case _thread_blocked: return "_thread_blocked";
2913 case _thread_blocked_trans: return "_thread_blocked_trans";
2914 default: return "unknown thread state";
2915 }
2916 }
2917
2918 #ifndef PRODUCT
2919 void JavaThread::print_thread_state_on(outputStream *st) const {
2920 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2921 };
2922 void JavaThread::print_thread_state() const {
2923 print_thread_state_on(tty);
2924 }
2925 #endif // PRODUCT
2926
2927 // Called by Threads::print() for VM_PrintThreads operation
2928 void JavaThread::print_on(outputStream *st) const {
2929 st->print_raw("\"");
2930 st->print_raw(get_thread_name());
2931 st->print_raw("\" ");
2932 oop thread_oop = threadObj();
2933 if (thread_oop != NULL) {
2934 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2935 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2936 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2937 }
2938 Thread::print_on(st);
2939 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2940 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2941 if (thread_oop != NULL) {
2942 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2943 }
2944 #ifndef PRODUCT
2945 print_thread_state_on(st);
2946 _safepoint_state->print_on(st);
2947 #endif // PRODUCT
2948 if (is_Compiler_thread()) {
2949 CompilerThread* ct = (CompilerThread*)this;
2950 if (ct->task() != NULL) {
2951 st->print(" Compiling: ");
2952 ct->task()->print(st, NULL, true, false);
2953 } else {
2954 st->print(" No compile task");
2955 }
2956 st->cr();
2957 }
2958 }
2959
2960 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2961 st->print("%s", get_thread_name_string(buf, buflen));
2962 }
2963
2964 // Called by fatal error handler. The difference between this and
2965 // JavaThread::print() is that we can't grab lock or allocate memory.
2966 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2967 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2968 oop thread_obj = threadObj();
2969 if (thread_obj != NULL) {
2970 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2971 }
2972 st->print(" [");
2973 st->print("%s", _get_thread_state_name(_thread_state));
2974 if (osthread()) {
2975 st->print(", id=%d", osthread()->thread_id());
2976 }
2977 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2978 p2i(stack_end()), p2i(stack_base()));
2979 st->print("]");
2980 return;
2981 }
2982
2983 // Verification
2984
2985 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2986
2987 void JavaThread::verify() {
2988 // Verify oops in the thread.
2989 oops_do(&VerifyOopClosure::verify_oop, NULL);
2990
2991 // Verify the stack frames.
2992 frames_do(frame_verify);
2993 }
2994
2995 // CR 6300358 (sub-CR 2137150)
2996 // Most callers of this method assume that it can't return NULL but a
2997 // thread may not have a name whilst it is in the process of attaching to
2998 // the VM - see CR 6412693, and there are places where a JavaThread can be
2999 // seen prior to having it's threadObj set (eg JNI attaching threads and
3000 // if vm exit occurs during initialization). These cases can all be accounted
3001 // for such that this method never returns NULL.
3002 const char* JavaThread::get_thread_name() const {
3003 #ifdef ASSERT
3004 // early safepoints can hit while current thread does not yet have TLS
3005 if (!SafepointSynchronize::is_at_safepoint()) {
3006 Thread *cur = Thread::current();
3007 if (!(cur->is_Java_thread() && cur == this)) {
3008 // Current JavaThreads are allowed to get their own name without
3009 // the Threads_lock.
3010 assert_locked_or_safepoint(Threads_lock);
3011 }
3012 }
3013 #endif // ASSERT
3014 return get_thread_name_string();
3015 }
3016
3017 // Returns a non-NULL representation of this thread's name, or a suitable
3018 // descriptive string if there is no set name
3019 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3020 const char* name_str;
3021 oop thread_obj = threadObj();
3022 if (thread_obj != NULL) {
3023 oop name = java_lang_Thread::name(thread_obj);
3024 if (name != NULL) {
3025 if (buf == NULL) {
3026 name_str = java_lang_String::as_utf8_string(name);
3027 } else {
3028 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3029 }
3030 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3031 name_str = "<no-name - thread is attaching>";
3032 } else {
3033 name_str = Thread::name();
3034 }
3035 } else {
3036 name_str = Thread::name();
3037 }
3038 assert(name_str != NULL, "unexpected NULL thread name");
3039 return name_str;
3040 }
3041
3042
3043 const char* JavaThread::get_threadgroup_name() const {
3044 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3045 oop thread_obj = threadObj();
3046 if (thread_obj != NULL) {
3047 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3048 if (thread_group != NULL) {
3049 // ThreadGroup.name can be null
3050 return java_lang_ThreadGroup::name(thread_group);
3051 }
3052 }
3053 return NULL;
3054 }
3055
3056 const char* JavaThread::get_parent_name() const {
3057 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3058 oop thread_obj = threadObj();
3059 if (thread_obj != NULL) {
3060 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3061 if (thread_group != NULL) {
3062 oop parent = java_lang_ThreadGroup::parent(thread_group);
3063 if (parent != NULL) {
3064 // ThreadGroup.name can be null
3065 return java_lang_ThreadGroup::name(parent);
3066 }
3067 }
3068 }
3069 return NULL;
3070 }
3071
3072 ThreadPriority JavaThread::java_priority() const {
3073 oop thr_oop = threadObj();
3074 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3075 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3076 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3077 return priority;
3078 }
3079
3080 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3081
3082 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3083 // Link Java Thread object <-> C++ Thread
3084
3085 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3086 // and put it into a new Handle. The Handle "thread_oop" can then
3087 // be used to pass the C++ thread object to other methods.
3088
3089 // Set the Java level thread object (jthread) field of the
3090 // new thread (a JavaThread *) to C++ thread object using the
3091 // "thread_oop" handle.
3092
3093 // Set the thread field (a JavaThread *) of the
3094 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3095
3096 Handle thread_oop(Thread::current(),
3097 JNIHandles::resolve_non_null(jni_thread));
3098 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3099 "must be initialized");
3100 set_threadObj(thread_oop());
3101 java_lang_Thread::set_thread(thread_oop(), this);
3102
3103 if (prio == NoPriority) {
3104 prio = java_lang_Thread::priority(thread_oop());
3105 assert(prio != NoPriority, "A valid priority should be present");
3106 }
3107
3108 // Push the Java priority down to the native thread; needs Threads_lock
3109 Thread::set_priority(this, prio);
3110
3111 prepare_ext();
3112
3113 // Add the new thread to the Threads list and set it in motion.
3114 // We must have threads lock in order to call Threads::add.
3115 // It is crucial that we do not block before the thread is
3116 // added to the Threads list for if a GC happens, then the java_thread oop
3117 // will not be visited by GC.
3118 Threads::add(this);
3119 }
3120
3121 oop JavaThread::current_park_blocker() {
3122 // Support for JSR-166 locks
3123 oop thread_oop = threadObj();
3124 if (thread_oop != NULL &&
3125 JDK_Version::current().supports_thread_park_blocker()) {
3126 return java_lang_Thread::park_blocker(thread_oop);
3127 }
3128 return NULL;
3129 }
3130
3131
3132 void JavaThread::print_stack_on(outputStream* st) {
3133 if (!has_last_Java_frame()) return;
3134 ResourceMark rm;
3135 HandleMark hm;
3136
3137 RegisterMap reg_map(this);
3138 vframe* start_vf = last_java_vframe(®_map);
3139 int count = 0;
3140 for (vframe* f = start_vf; f; f = f->sender()) {
3141 if (f->is_java_frame()) {
3142 javaVFrame* jvf = javaVFrame::cast(f);
3143 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3144
3145 // Print out lock information
3146 if (JavaMonitorsInStackTrace) {
3147 jvf->print_lock_info_on(st, count);
3148 }
3149 } else {
3150 // Ignore non-Java frames
3151 }
3152
3153 // Bail-out case for too deep stacks
3154 count++;
3155 if (MaxJavaStackTraceDepth == count) return;
3156 }
3157 }
3158
3159
3160 // JVMTI PopFrame support
3161 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3162 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3163 if (in_bytes(size_in_bytes) != 0) {
3164 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3165 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3166 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3167 }
3168 }
3169
3170 void* JavaThread::popframe_preserved_args() {
3171 return _popframe_preserved_args;
3172 }
3173
3174 ByteSize JavaThread::popframe_preserved_args_size() {
3175 return in_ByteSize(_popframe_preserved_args_size);
3176 }
3177
3178 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3179 int sz = in_bytes(popframe_preserved_args_size());
3180 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3181 return in_WordSize(sz / wordSize);
3182 }
3183
3184 void JavaThread::popframe_free_preserved_args() {
3185 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3186 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3187 _popframe_preserved_args = NULL;
3188 _popframe_preserved_args_size = 0;
3189 }
3190
3191 #ifndef PRODUCT
3192
3193 void JavaThread::trace_frames() {
3194 tty->print_cr("[Describe stack]");
3195 int frame_no = 1;
3196 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3197 tty->print(" %d. ", frame_no++);
3198 fst.current()->print_value_on(tty, this);
3199 tty->cr();
3200 }
3201 }
3202
3203 class PrintAndVerifyOopClosure: public OopClosure {
3204 protected:
3205 template <class T> inline void do_oop_work(T* p) {
3206 oop obj = oopDesc::load_decode_heap_oop(p);
3207 if (obj == NULL) return;
3208 tty->print(INTPTR_FORMAT ": ", p2i(p));
3209 if (obj->is_oop_or_null()) {
3210 if (obj->is_objArray()) {
3211 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3212 } else {
3213 obj->print();
3214 }
3215 } else {
3216 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3217 }
3218 tty->cr();
3219 }
3220 public:
3221 virtual void do_oop(oop* p) { do_oop_work(p); }
3222 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3223 };
3224
3225
3226 static void oops_print(frame* f, const RegisterMap *map) {
3227 PrintAndVerifyOopClosure print;
3228 f->print_value();
3229 f->oops_do(&print, NULL, (RegisterMap*)map);
3230 }
3231
3232 // Print our all the locations that contain oops and whether they are
3233 // valid or not. This useful when trying to find the oldest frame
3234 // where an oop has gone bad since the frame walk is from youngest to
3235 // oldest.
3236 void JavaThread::trace_oops() {
3237 tty->print_cr("[Trace oops]");
3238 frames_do(oops_print);
3239 }
3240
3241
3242 #ifdef ASSERT
3243 // Print or validate the layout of stack frames
3244 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3245 ResourceMark rm;
3246 PRESERVE_EXCEPTION_MARK;
3247 FrameValues values;
3248 int frame_no = 0;
3249 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3250 fst.current()->describe(values, ++frame_no);
3251 if (depth == frame_no) break;
3252 }
3253 if (validate_only) {
3254 values.validate();
3255 } else {
3256 tty->print_cr("[Describe stack layout]");
3257 values.print(this);
3258 }
3259 }
3260 #endif
3261
3262 void JavaThread::trace_stack_from(vframe* start_vf) {
3263 ResourceMark rm;
3264 int vframe_no = 1;
3265 for (vframe* f = start_vf; f; f = f->sender()) {
3266 if (f->is_java_frame()) {
3267 javaVFrame::cast(f)->print_activation(vframe_no++);
3268 } else {
3269 f->print();
3270 }
3271 if (vframe_no > StackPrintLimit) {
3272 tty->print_cr("...<more frames>...");
3273 return;
3274 }
3275 }
3276 }
3277
3278
3279 void JavaThread::trace_stack() {
3280 if (!has_last_Java_frame()) return;
3281 ResourceMark rm;
3282 HandleMark hm;
3283 RegisterMap reg_map(this);
3284 trace_stack_from(last_java_vframe(®_map));
3285 }
3286
3287
3288 #endif // PRODUCT
3289
3290
3291 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3292 assert(reg_map != NULL, "a map must be given");
3293 frame f = last_frame();
3294 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3295 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3296 }
3297 return NULL;
3298 }
3299
3300
3301 Klass* JavaThread::security_get_caller_class(int depth) {
3302 vframeStream vfst(this);
3303 vfst.security_get_caller_frame(depth);
3304 if (!vfst.at_end()) {
3305 return vfst.method()->method_holder();
3306 }
3307 return NULL;
3308 }
3309
3310 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3311 assert(thread->is_Compiler_thread(), "must be compiler thread");
3312 CompileBroker::compiler_thread_loop();
3313 }
3314
3315 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3316 NMethodSweeper::sweeper_loop();
3317 }
3318
3319 // Create a CompilerThread
3320 CompilerThread::CompilerThread(CompileQueue* queue,
3321 CompilerCounters* counters)
3322 : JavaThread(&compiler_thread_entry) {
3323 _env = NULL;
3324 _log = NULL;
3325 _task = NULL;
3326 _queue = queue;
3327 _counters = counters;
3328 _buffer_blob = NULL;
3329 _compiler = NULL;
3330
3331 #ifndef PRODUCT
3332 _ideal_graph_printer = NULL;
3333 #endif
3334 }
3335
3336 bool CompilerThread::can_call_java() const {
3337 return _compiler != NULL && _compiler->is_jvmci();
3338 }
3339
3340 // Create sweeper thread
3341 CodeCacheSweeperThread::CodeCacheSweeperThread()
3342 : JavaThread(&sweeper_thread_entry) {
3343 _scanned_compiled_method = NULL;
3344 }
3345
3346 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3347 JavaThread::oops_do(f, cf);
3348 if (_scanned_compiled_method != NULL && cf != NULL) {
3349 // Safepoints can occur when the sweeper is scanning an nmethod so
3350 // process it here to make sure it isn't unloaded in the middle of
3351 // a scan.
3352 cf->do_code_blob(_scanned_compiled_method);
3353 }
3354 }
3355
3356 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3357 JavaThread::nmethods_do(cf);
3358 if (_scanned_compiled_method != NULL && cf != NULL) {
3359 // Safepoints can occur when the sweeper is scanning an nmethod so
3360 // process it here to make sure it isn't unloaded in the middle of
3361 // a scan.
3362 cf->do_code_blob(_scanned_compiled_method);
3363 }
3364 }
3365
3366
3367 // ======= Threads ========
3368
3369 // The Threads class links together all active threads, and provides
3370 // operations over all threads. It is protected by its own Mutex
3371 // lock, which is also used in other contexts to protect thread
3372 // operations from having the thread being operated on from exiting
3373 // and going away unexpectedly (e.g., safepoint synchronization)
3374
3375 JavaThread* Threads::_thread_list = NULL;
3376 int Threads::_number_of_threads = 0;
3377 int Threads::_number_of_non_daemon_threads = 0;
3378 int Threads::_return_code = 0;
3379 int Threads::_thread_claim_parity = 0;
3380 size_t JavaThread::_stack_size_at_create = 0;
3381 #ifdef ASSERT
3382 bool Threads::_vm_complete = false;
3383 #endif
3384
3385 // All JavaThreads
3386 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3387
3388 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3389 void Threads::threads_do(ThreadClosure* tc) {
3390 assert_locked_or_safepoint(Threads_lock);
3391 // ALL_JAVA_THREADS iterates through all JavaThreads
3392 ALL_JAVA_THREADS(p) {
3393 tc->do_thread(p);
3394 }
3395 // Someday we could have a table or list of all non-JavaThreads.
3396 // For now, just manually iterate through them.
3397 tc->do_thread(VMThread::vm_thread());
3398 Universe::heap()->gc_threads_do(tc);
3399 WatcherThread *wt = WatcherThread::watcher_thread();
3400 // Strictly speaking, the following NULL check isn't sufficient to make sure
3401 // the data for WatcherThread is still valid upon being examined. However,
3402 // considering that WatchThread terminates when the VM is on the way to
3403 // exit at safepoint, the chance of the above is extremely small. The right
3404 // way to prevent termination of WatcherThread would be to acquire
3405 // Terminator_lock, but we can't do that without violating the lock rank
3406 // checking in some cases.
3407 if (wt != NULL) {
3408 tc->do_thread(wt);
3409 }
3410
3411 // If CompilerThreads ever become non-JavaThreads, add them here
3412 }
3413
3414 // The system initialization in the library has three phases.
3415 //
3416 // Phase 1: java.lang.System class initialization
3417 // java.lang.System is a primordial class loaded and initialized
3418 // by the VM early during startup. java.lang.System.<clinit>
3419 // only does registerNatives and keeps the rest of the class
3420 // initialization work later until thread initialization completes.
3421 //
3422 // System.initPhase1 initializes the system properties, the static
3423 // fields in, out, and err. Set up java signal handlers, OS-specific
3424 // system settings, and thread group of the main thread.
3425 static void call_initPhase1(TRAPS) {
3426 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3427 instanceKlassHandle klass (THREAD, k);
3428
3429 JavaValue result(T_VOID);
3430 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3431 vmSymbols::void_method_signature(), CHECK);
3432 }
3433
3434 // Phase 2. Module system initialization
3435 // This will initialize the module system. Only java.base classes
3436 // can be loaded until phase 2 completes.
3437 //
3438 // Call System.initPhase2 after the compiler initialization and jsr292
3439 // classes get initialized because module initialization runs a lot of java
3440 // code, that for performance reasons, should be compiled. Also, this will
3441 // enable the startup code to use lambda and other language features in this
3442 // phase and onward.
3443 //
3444 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3445 static void call_initPhase2(TRAPS) {
3446 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime));
3447
3448 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3449 instanceKlassHandle klass (THREAD, k);
3450
3451 JavaValue result(T_INT);
3452 JavaCallArguments args;
3453 args.push_int(DisplayVMOutputToStderr);
3454 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3455 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3456 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3457 if (result.get_jint() != JNI_OK) {
3458 vm_exit_during_initialization(); // no message or exception
3459 }
3460
3461 universe_post_module_init();
3462 }
3463
3464 // Phase 3. final setup - set security manager, system class loader and TCCL
3465 //
3466 // This will instantiate and set the security manager, set the system class
3467 // loader as well as the thread context class loader. The security manager
3468 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3469 // other modules or the application's classpath.
3470 static void call_initPhase3(TRAPS) {
3471 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3472 instanceKlassHandle klass (THREAD, k);
3473
3474 JavaValue result(T_VOID);
3475 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3476 vmSymbols::void_method_signature(), CHECK);
3477 }
3478
3479 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3480 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3481
3482 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3483 create_vm_init_libraries();
3484 }
3485
3486 initialize_class(vmSymbols::java_lang_String(), CHECK);
3487
3488 // Inject CompactStrings value after the static initializers for String ran.
3489 java_lang_String::set_compact_strings(CompactStrings);
3490
3491 // Initialize java_lang.System (needed before creating the thread)
3492 initialize_class(vmSymbols::java_lang_System(), CHECK);
3493 // The VM creates & returns objects of this class. Make sure it's initialized.
3494 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3495 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3496 Handle thread_group = create_initial_thread_group(CHECK);
3497 Universe::set_main_thread_group(thread_group());
3498 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3499 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3500 main_thread->set_threadObj(thread_object);
3501 // Set thread status to running since main thread has
3502 // been started and running.
3503 java_lang_Thread::set_thread_status(thread_object,
3504 java_lang_Thread::RUNNABLE);
3505
3506 // The VM creates objects of this class.
3507 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3508
3509 // The VM preresolves methods to these classes. Make sure that they get initialized
3510 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3511 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3512
3513 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3514 call_initPhase1(CHECK);
3515
3516 // get the Java runtime name after java.lang.System is initialized
3517 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3518 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3519
3520 // an instance of OutOfMemory exception has been allocated earlier
3521 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3522 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3523 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3524 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3525 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3526 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3527 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3528 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3529 }
3530
3531 void Threads::initialize_jsr292_core_classes(TRAPS) {
3532 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3533
3534 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3535 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3536 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3537 }
3538
3539 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3540 extern void JDK_Version_init();
3541
3542 // Preinitialize version info.
3543 VM_Version::early_initialize();
3544
3545 // Check version
3546 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3547
3548 // Initialize library-based TLS
3549 ThreadLocalStorage::init();
3550
3551 // Initialize the output stream module
3552 ostream_init();
3553
3554 // Process java launcher properties.
3555 Arguments::process_sun_java_launcher_properties(args);
3556
3557 // Initialize the os module
3558 os::init();
3559
3560 // Record VM creation timing statistics
3561 TraceVmCreationTime create_vm_timer;
3562 create_vm_timer.start();
3563
3564 // Initialize system properties.
3565 Arguments::init_system_properties();
3566
3567 // So that JDK version can be used as a discriminator when parsing arguments
3568 JDK_Version_init();
3569
3570 // Update/Initialize System properties after JDK version number is known
3571 Arguments::init_version_specific_system_properties();
3572
3573 // Make sure to initialize log configuration *before* parsing arguments
3574 LogConfiguration::initialize(create_vm_timer.begin_time());
3575
3576 // Parse arguments
3577 jint parse_result = Arguments::parse(args);
3578 if (parse_result != JNI_OK) return parse_result;
3579
3580 os::init_before_ergo();
3581
3582 jint ergo_result = Arguments::apply_ergo();
3583 if (ergo_result != JNI_OK) return ergo_result;
3584
3585 // Final check of all ranges after ergonomics which may change values.
3586 if (!CommandLineFlagRangeList::check_ranges()) {
3587 return JNI_EINVAL;
3588 }
3589
3590 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3591 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3592 if (!constraint_result) {
3593 return JNI_EINVAL;
3594 }
3595
3596 CommandLineFlagWriteableList::mark_startup();
3597
3598 if (PauseAtStartup) {
3599 os::pause();
3600 }
3601
3602 HOTSPOT_VM_INIT_BEGIN();
3603
3604 // Timing (must come after argument parsing)
3605 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3606
3607 // Initialize the os module after parsing the args
3608 jint os_init_2_result = os::init_2();
3609 if (os_init_2_result != JNI_OK) return os_init_2_result;
3610
3611 jint adjust_after_os_result = Arguments::adjust_after_os();
3612 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3613
3614 // Initialize output stream logging
3615 ostream_init_log();
3616
3617 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3618 // Must be before create_vm_init_agents()
3619 if (Arguments::init_libraries_at_startup()) {
3620 convert_vm_init_libraries_to_agents();
3621 }
3622
3623 // Launch -agentlib/-agentpath and converted -Xrun agents
3624 if (Arguments::init_agents_at_startup()) {
3625 create_vm_init_agents();
3626 }
3627
3628 // Initialize Threads state
3629 _thread_list = NULL;
3630 _number_of_threads = 0;
3631 _number_of_non_daemon_threads = 0;
3632
3633 // Initialize global data structures and create system classes in heap
3634 vm_init_globals();
3635
3636 #if INCLUDE_JVMCI
3637 if (JVMCICounterSize > 0) {
3638 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3639 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3640 } else {
3641 JavaThread::_jvmci_old_thread_counters = NULL;
3642 }
3643 #endif // INCLUDE_JVMCI
3644
3645 // Attach the main thread to this os thread
3646 JavaThread* main_thread = new JavaThread();
3647 main_thread->set_thread_state(_thread_in_vm);
3648 main_thread->initialize_thread_current();
3649 // must do this before set_active_handles
3650 main_thread->record_stack_base_and_size();
3651 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3652
3653 if (!main_thread->set_as_starting_thread()) {
3654 vm_shutdown_during_initialization(
3655 "Failed necessary internal allocation. Out of swap space");
3656 delete main_thread;
3657 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3658 return JNI_ENOMEM;
3659 }
3660
3661 // Enable guard page *after* os::create_main_thread(), otherwise it would
3662 // crash Linux VM, see notes in os_linux.cpp.
3663 main_thread->create_stack_guard_pages();
3664
3665 // Initialize Java-Level synchronization subsystem
3666 ObjectMonitor::Initialize();
3667
3668 // Initialize global modules
3669 jint status = init_globals();
3670 if (status != JNI_OK) {
3671 delete main_thread;
3672 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3673 return status;
3674 }
3675
3676 if (TRACE_INITIALIZE() != JNI_OK) {
3677 vm_exit_during_initialization("Failed to initialize tracing backend");
3678 }
3679
3680 // Should be done after the heap is fully created
3681 main_thread->cache_global_variables();
3682
3683 HandleMark hm;
3684
3685 { MutexLocker mu(Threads_lock);
3686 Threads::add(main_thread);
3687 }
3688
3689 // Any JVMTI raw monitors entered in onload will transition into
3690 // real raw monitor. VM is setup enough here for raw monitor enter.
3691 JvmtiExport::transition_pending_onload_raw_monitors();
3692
3693 // Create the VMThread
3694 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3695
3696 VMThread::create();
3697 Thread* vmthread = VMThread::vm_thread();
3698
3699 if (!os::create_thread(vmthread, os::vm_thread)) {
3700 vm_exit_during_initialization("Cannot create VM thread. "
3701 "Out of system resources.");
3702 }
3703
3704 // Wait for the VM thread to become ready, and VMThread::run to initialize
3705 // Monitors can have spurious returns, must always check another state flag
3706 {
3707 MutexLocker ml(Notify_lock);
3708 os::start_thread(vmthread);
3709 while (vmthread->active_handles() == NULL) {
3710 Notify_lock->wait();
3711 }
3712 }
3713 }
3714
3715 assert(Universe::is_fully_initialized(), "not initialized");
3716 if (VerifyDuringStartup) {
3717 // Make sure we're starting with a clean slate.
3718 VM_Verify verify_op;
3719 VMThread::execute(&verify_op);
3720 }
3721
3722 Thread* THREAD = Thread::current();
3723
3724 // At this point, the Universe is initialized, but we have not executed
3725 // any byte code. Now is a good time (the only time) to dump out the
3726 // internal state of the JVM for sharing.
3727 if (DumpSharedSpaces) {
3728 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3729 ShouldNotReachHere();
3730 }
3731
3732 // Always call even when there are not JVMTI environments yet, since environments
3733 // may be attached late and JVMTI must track phases of VM execution
3734 JvmtiExport::enter_early_start_phase();
3735
3736 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3737 JvmtiExport::post_early_vm_start();
3738
3739 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3740
3741 // We need this for ClassDataSharing - the initial vm.info property is set
3742 // with the default value of CDS "sharing" which may be reset through
3743 // command line options.
3744 reset_vm_info_property(CHECK_JNI_ERR);
3745
3746 quicken_jni_functions();
3747
3748 // No more stub generation allowed after that point.
3749 StubCodeDesc::freeze();
3750
3751 // Set flag that basic initialization has completed. Used by exceptions and various
3752 // debug stuff, that does not work until all basic classes have been initialized.
3753 set_init_completed();
3754
3755 LogConfiguration::post_initialize();
3756 Metaspace::post_initialize();
3757
3758 HOTSPOT_VM_INIT_END();
3759
3760 // record VM initialization completion time
3761 #if INCLUDE_MANAGEMENT
3762 Management::record_vm_init_completed();
3763 #endif // INCLUDE_MANAGEMENT
3764
3765 // Signal Dispatcher needs to be started before VMInit event is posted
3766 os::signal_init();
3767
3768 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3769 if (!DisableAttachMechanism) {
3770 AttachListener::vm_start();
3771 if (StartAttachListener || AttachListener::init_at_startup()) {
3772 AttachListener::init();
3773 }
3774 }
3775
3776 // Launch -Xrun agents
3777 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3778 // back-end can launch with -Xdebug -Xrunjdwp.
3779 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3780 create_vm_init_libraries();
3781 }
3782
3783 if (CleanChunkPoolAsync) {
3784 Chunk::start_chunk_pool_cleaner_task();
3785 }
3786
3787 // initialize compiler(s)
3788 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3789 CompileBroker::compilation_init(CHECK_JNI_ERR);
3790 #endif
3791
3792 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3793 // It is done after compilers are initialized, because otherwise compilations of
3794 // signature polymorphic MH intrinsics can be missed
3795 // (see SystemDictionary::find_method_handle_intrinsic).
3796 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3797
3798 // This will initialize the module system. Only java.base classes can be
3799 // loaded until phase 2 completes
3800 call_initPhase2(CHECK_JNI_ERR);
3801
3802 // Always call even when there are not JVMTI environments yet, since environments
3803 // may be attached late and JVMTI must track phases of VM execution
3804 JvmtiExport::enter_start_phase();
3805
3806 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3807 JvmtiExport::post_vm_start();
3808
3809 // Final system initialization including security manager and system class loader
3810 call_initPhase3(CHECK_JNI_ERR);
3811
3812 // cache the system class loader
3813 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3814
3815 #if INCLUDE_JVMCI
3816 if (EnableJVMCI) {
3817 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3818 // The JVMCI Java initialization code will read this flag and
3819 // do the printing if it's set.
3820 bool init = JVMCIPrintProperties;
3821
3822 if (!init) {
3823 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3824 // compilations via JVMCI will not actually block until JVMCI is initialized.
3825 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3826 }
3827
3828 if (init) {
3829 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3830 }
3831 }
3832 #endif
3833
3834 // Always call even when there are not JVMTI environments yet, since environments
3835 // may be attached late and JVMTI must track phases of VM execution
3836 JvmtiExport::enter_live_phase();
3837
3838 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3839 JvmtiExport::post_vm_initialized();
3840
3841 if (TRACE_START() != JNI_OK) {
3842 vm_exit_during_initialization("Failed to start tracing backend.");
3843 }
3844
3845 #if INCLUDE_MANAGEMENT
3846 Management::initialize(THREAD);
3847
3848 if (HAS_PENDING_EXCEPTION) {
3849 // management agent fails to start possibly due to
3850 // configuration problem and is responsible for printing
3851 // stack trace if appropriate. Simply exit VM.
3852 vm_exit(1);
3853 }
3854 #endif // INCLUDE_MANAGEMENT
3855
3856 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3857 if (MemProfiling) MemProfiler::engage();
3858 StatSampler::engage();
3859 if (CheckJNICalls) JniPeriodicChecker::engage();
3860
3861 BiasedLocking::init();
3862
3863 #if INCLUDE_RTM_OPT
3864 RTMLockingCounters::init();
3865 #endif
3866
3867 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3868 call_postVMInitHook(THREAD);
3869 // The Java side of PostVMInitHook.run must deal with all
3870 // exceptions and provide means of diagnosis.
3871 if (HAS_PENDING_EXCEPTION) {
3872 CLEAR_PENDING_EXCEPTION;
3873 }
3874 }
3875
3876 {
3877 MutexLocker ml(PeriodicTask_lock);
3878 // Make sure the WatcherThread can be started by WatcherThread::start()
3879 // or by dynamic enrollment.
3880 WatcherThread::make_startable();
3881 // Start up the WatcherThread if there are any periodic tasks
3882 // NOTE: All PeriodicTasks should be registered by now. If they
3883 // aren't, late joiners might appear to start slowly (we might
3884 // take a while to process their first tick).
3885 if (PeriodicTask::num_tasks() > 0) {
3886 WatcherThread::start();
3887 }
3888 }
3889
3890 create_vm_timer.end();
3891 #ifdef ASSERT
3892 _vm_complete = true;
3893 #endif
3894 return JNI_OK;
3895 }
3896
3897 // type for the Agent_OnLoad and JVM_OnLoad entry points
3898 extern "C" {
3899 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3900 }
3901 // Find a command line agent library and return its entry point for
3902 // -agentlib: -agentpath: -Xrun
3903 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3904 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3905 const char *on_load_symbols[],
3906 size_t num_symbol_entries) {
3907 OnLoadEntry_t on_load_entry = NULL;
3908 void *library = NULL;
3909
3910 if (!agent->valid()) {
3911 char buffer[JVM_MAXPATHLEN];
3912 char ebuf[1024] = "";
3913 const char *name = agent->name();
3914 const char *msg = "Could not find agent library ";
3915
3916 // First check to see if agent is statically linked into executable
3917 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3918 library = agent->os_lib();
3919 } else if (agent->is_absolute_path()) {
3920 library = os::dll_load(name, ebuf, sizeof ebuf);
3921 if (library == NULL) {
3922 const char *sub_msg = " in absolute path, with error: ";
3923 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3924 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3925 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3926 // If we can't find the agent, exit.
3927 vm_exit_during_initialization(buf, NULL);
3928 FREE_C_HEAP_ARRAY(char, buf);
3929 }
3930 } else {
3931 // Try to load the agent from the standard dll directory
3932 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3933 name)) {
3934 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3935 }
3936 if (library == NULL) { // Try the local directory
3937 char ns[1] = {0};
3938 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3939 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3940 }
3941 if (library == NULL) {
3942 const char *sub_msg = " on the library path, with error: ";
3943 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3944 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3945 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3946 // If we can't find the agent, exit.
3947 vm_exit_during_initialization(buf, NULL);
3948 FREE_C_HEAP_ARRAY(char, buf);
3949 }
3950 }
3951 }
3952 agent->set_os_lib(library);
3953 agent->set_valid();
3954 }
3955
3956 // Find the OnLoad function.
3957 on_load_entry =
3958 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3959 false,
3960 on_load_symbols,
3961 num_symbol_entries));
3962 return on_load_entry;
3963 }
3964
3965 // Find the JVM_OnLoad entry point
3966 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3967 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3968 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3969 }
3970
3971 // Find the Agent_OnLoad entry point
3972 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3973 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3974 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3975 }
3976
3977 // For backwards compatibility with -Xrun
3978 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3979 // treated like -agentpath:
3980 // Must be called before agent libraries are created
3981 void Threads::convert_vm_init_libraries_to_agents() {
3982 AgentLibrary* agent;
3983 AgentLibrary* next;
3984
3985 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3986 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3987 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3988
3989 // If there is an JVM_OnLoad function it will get called later,
3990 // otherwise see if there is an Agent_OnLoad
3991 if (on_load_entry == NULL) {
3992 on_load_entry = lookup_agent_on_load(agent);
3993 if (on_load_entry != NULL) {
3994 // switch it to the agent list -- so that Agent_OnLoad will be called,
3995 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3996 Arguments::convert_library_to_agent(agent);
3997 } else {
3998 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3999 }
4000 }
4001 }
4002 }
4003
4004 // Create agents for -agentlib: -agentpath: and converted -Xrun
4005 // Invokes Agent_OnLoad
4006 // Called very early -- before JavaThreads exist
4007 void Threads::create_vm_init_agents() {
4008 extern struct JavaVM_ main_vm;
4009 AgentLibrary* agent;
4010
4011 JvmtiExport::enter_onload_phase();
4012
4013 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4014 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4015
4016 if (on_load_entry != NULL) {
4017 // Invoke the Agent_OnLoad function
4018 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4019 if (err != JNI_OK) {
4020 vm_exit_during_initialization("agent library failed to init", agent->name());
4021 }
4022 } else {
4023 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4024 }
4025 }
4026 JvmtiExport::enter_primordial_phase();
4027 }
4028
4029 extern "C" {
4030 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4031 }
4032
4033 void Threads::shutdown_vm_agents() {
4034 // Send any Agent_OnUnload notifications
4035 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4036 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4037 extern struct JavaVM_ main_vm;
4038 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4039
4040 // Find the Agent_OnUnload function.
4041 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4042 os::find_agent_function(agent,
4043 false,
4044 on_unload_symbols,
4045 num_symbol_entries));
4046
4047 // Invoke the Agent_OnUnload function
4048 if (unload_entry != NULL) {
4049 JavaThread* thread = JavaThread::current();
4050 ThreadToNativeFromVM ttn(thread);
4051 HandleMark hm(thread);
4052 (*unload_entry)(&main_vm);
4053 }
4054 }
4055 }
4056
4057 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4058 // Invokes JVM_OnLoad
4059 void Threads::create_vm_init_libraries() {
4060 extern struct JavaVM_ main_vm;
4061 AgentLibrary* agent;
4062
4063 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4064 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4065
4066 if (on_load_entry != NULL) {
4067 // Invoke the JVM_OnLoad function
4068 JavaThread* thread = JavaThread::current();
4069 ThreadToNativeFromVM ttn(thread);
4070 HandleMark hm(thread);
4071 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4072 if (err != JNI_OK) {
4073 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4074 }
4075 } else {
4076 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4077 }
4078 }
4079 }
4080
4081 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4082 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4083
4084 JavaThread* java_thread = NULL;
4085 // Sequential search for now. Need to do better optimization later.
4086 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4087 oop tobj = thread->threadObj();
4088 if (!thread->is_exiting() &&
4089 tobj != NULL &&
4090 java_tid == java_lang_Thread::thread_id(tobj)) {
4091 java_thread = thread;
4092 break;
4093 }
4094 }
4095 return java_thread;
4096 }
4097
4098
4099 // Last thread running calls java.lang.Shutdown.shutdown()
4100 void JavaThread::invoke_shutdown_hooks() {
4101 HandleMark hm(this);
4102
4103 // We could get here with a pending exception, if so clear it now.
4104 if (this->has_pending_exception()) {
4105 this->clear_pending_exception();
4106 }
4107
4108 EXCEPTION_MARK;
4109 Klass* k =
4110 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4111 THREAD);
4112 if (k != NULL) {
4113 // SystemDictionary::resolve_or_null will return null if there was
4114 // an exception. If we cannot load the Shutdown class, just don't
4115 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4116 // and finalizers (if runFinalizersOnExit is set) won't be run.
4117 // Note that if a shutdown hook was registered or runFinalizersOnExit
4118 // was called, the Shutdown class would have already been loaded
4119 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4120 instanceKlassHandle shutdown_klass (THREAD, k);
4121 JavaValue result(T_VOID);
4122 JavaCalls::call_static(&result,
4123 shutdown_klass,
4124 vmSymbols::shutdown_method_name(),
4125 vmSymbols::void_method_signature(),
4126 THREAD);
4127 }
4128 CLEAR_PENDING_EXCEPTION;
4129 }
4130
4131 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4132 // the program falls off the end of main(). Another VM exit path is through
4133 // vm_exit() when the program calls System.exit() to return a value or when
4134 // there is a serious error in VM. The two shutdown paths are not exactly
4135 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4136 // and VM_Exit op at VM level.
4137 //
4138 // Shutdown sequence:
4139 // + Shutdown native memory tracking if it is on
4140 // + Wait until we are the last non-daemon thread to execute
4141 // <-- every thing is still working at this moment -->
4142 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4143 // shutdown hooks, run finalizers if finalization-on-exit
4144 // + Call before_exit(), prepare for VM exit
4145 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4146 // currently the only user of this mechanism is File.deleteOnExit())
4147 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4148 // post thread end and vm death events to JVMTI,
4149 // stop signal thread
4150 // + Call JavaThread::exit(), it will:
4151 // > release JNI handle blocks, remove stack guard pages
4152 // > remove this thread from Threads list
4153 // <-- no more Java code from this thread after this point -->
4154 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4155 // the compiler threads at safepoint
4156 // <-- do not use anything that could get blocked by Safepoint -->
4157 // + Disable tracing at JNI/JVM barriers
4158 // + Set _vm_exited flag for threads that are still running native code
4159 // + Delete this thread
4160 // + Call exit_globals()
4161 // > deletes tty
4162 // > deletes PerfMemory resources
4163 // + Return to caller
4164
4165 bool Threads::destroy_vm() {
4166 JavaThread* thread = JavaThread::current();
4167
4168 #ifdef ASSERT
4169 _vm_complete = false;
4170 #endif
4171 // Wait until we are the last non-daemon thread to execute
4172 { MutexLocker nu(Threads_lock);
4173 while (Threads::number_of_non_daemon_threads() > 1)
4174 // This wait should make safepoint checks, wait without a timeout,
4175 // and wait as a suspend-equivalent condition.
4176 //
4177 // Note: If the FlatProfiler is running and this thread is waiting
4178 // for another non-daemon thread to finish, then the FlatProfiler
4179 // is waiting for the external suspend request on this thread to
4180 // complete. wait_for_ext_suspend_completion() will eventually
4181 // timeout, but that takes time. Making this wait a suspend-
4182 // equivalent condition solves that timeout problem.
4183 //
4184 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4185 Mutex::_as_suspend_equivalent_flag);
4186 }
4187
4188 // Hang forever on exit if we are reporting an error.
4189 if (ShowMessageBoxOnError && is_error_reported()) {
4190 os::infinite_sleep();
4191 }
4192 os::wait_for_keypress_at_exit();
4193
4194 // run Java level shutdown hooks
4195 thread->invoke_shutdown_hooks();
4196
4197 before_exit(thread);
4198
4199 thread->exit(true);
4200
4201 // Stop VM thread.
4202 {
4203 // 4945125 The vm thread comes to a safepoint during exit.
4204 // GC vm_operations can get caught at the safepoint, and the
4205 // heap is unparseable if they are caught. Grab the Heap_lock
4206 // to prevent this. The GC vm_operations will not be able to
4207 // queue until after the vm thread is dead. After this point,
4208 // we'll never emerge out of the safepoint before the VM exits.
4209
4210 MutexLocker ml(Heap_lock);
4211
4212 VMThread::wait_for_vm_thread_exit();
4213 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4214 VMThread::destroy();
4215 }
4216
4217 // clean up ideal graph printers
4218 #if defined(COMPILER2) && !defined(PRODUCT)
4219 IdealGraphPrinter::clean_up();
4220 #endif
4221
4222 // Now, all Java threads are gone except daemon threads. Daemon threads
4223 // running Java code or in VM are stopped by the Safepoint. However,
4224 // daemon threads executing native code are still running. But they
4225 // will be stopped at native=>Java/VM barriers. Note that we can't
4226 // simply kill or suspend them, as it is inherently deadlock-prone.
4227
4228 VM_Exit::set_vm_exited();
4229
4230 notify_vm_shutdown();
4231
4232 delete thread;
4233
4234 #if INCLUDE_JVMCI
4235 if (JVMCICounterSize > 0) {
4236 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4237 }
4238 #endif
4239
4240 // exit_globals() will delete tty
4241 exit_globals();
4242
4243 LogConfiguration::finalize();
4244
4245 return true;
4246 }
4247
4248
4249 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4250 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4251 return is_supported_jni_version(version);
4252 }
4253
4254
4255 jboolean Threads::is_supported_jni_version(jint version) {
4256 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4257 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4258 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4259 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4260 if (version == JNI_VERSION_9) return JNI_TRUE;
4261 return JNI_FALSE;
4262 }
4263
4264
4265 void Threads::add(JavaThread* p, bool force_daemon) {
4266 // The threads lock must be owned at this point
4267 assert_locked_or_safepoint(Threads_lock);
4268
4269 // See the comment for this method in thread.hpp for its purpose and
4270 // why it is called here.
4271 p->initialize_queues();
4272 p->set_next(_thread_list);
4273 _thread_list = p;
4274 _number_of_threads++;
4275 oop threadObj = p->threadObj();
4276 bool daemon = true;
4277 // Bootstrapping problem: threadObj can be null for initial
4278 // JavaThread (or for threads attached via JNI)
4279 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4280 _number_of_non_daemon_threads++;
4281 daemon = false;
4282 }
4283
4284 ThreadService::add_thread(p, daemon);
4285
4286 // Possible GC point.
4287 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4288 }
4289
4290 void Threads::remove(JavaThread* p) {
4291 // Extra scope needed for Thread_lock, so we can check
4292 // that we do not remove thread without safepoint code notice
4293 { MutexLocker ml(Threads_lock);
4294
4295 assert(includes(p), "p must be present");
4296
4297 JavaThread* current = _thread_list;
4298 JavaThread* prev = NULL;
4299
4300 while (current != p) {
4301 prev = current;
4302 current = current->next();
4303 }
4304
4305 if (prev) {
4306 prev->set_next(current->next());
4307 } else {
4308 _thread_list = p->next();
4309 }
4310 _number_of_threads--;
4311 oop threadObj = p->threadObj();
4312 bool daemon = true;
4313 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4314 _number_of_non_daemon_threads--;
4315 daemon = false;
4316
4317 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4318 // on destroy_vm will wake up.
4319 if (number_of_non_daemon_threads() == 1) {
4320 Threads_lock->notify_all();
4321 }
4322 }
4323 ThreadService::remove_thread(p, daemon);
4324
4325 // Make sure that safepoint code disregard this thread. This is needed since
4326 // the thread might mess around with locks after this point. This can cause it
4327 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4328 // of this thread since it is removed from the queue.
4329 p->set_terminated_value();
4330 } // unlock Threads_lock
4331
4332 // Since Events::log uses a lock, we grab it outside the Threads_lock
4333 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4334 }
4335
4336 // Threads_lock must be held when this is called (or must be called during a safepoint)
4337 bool Threads::includes(JavaThread* p) {
4338 assert(Threads_lock->is_locked(), "sanity check");
4339 ALL_JAVA_THREADS(q) {
4340 if (q == p) {
4341 return true;
4342 }
4343 }
4344 return false;
4345 }
4346
4347 // Operations on the Threads list for GC. These are not explicitly locked,
4348 // but the garbage collector must provide a safe context for them to run.
4349 // In particular, these things should never be called when the Threads_lock
4350 // is held by some other thread. (Note: the Safepoint abstraction also
4351 // uses the Threads_lock to guarantee this property. It also makes sure that
4352 // all threads gets blocked when exiting or starting).
4353
4354 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4355 ALL_JAVA_THREADS(p) {
4356 p->oops_do(f, cf);
4357 }
4358 VMThread::vm_thread()->oops_do(f, cf);
4359 }
4360
4361 void Threads::change_thread_claim_parity() {
4362 // Set the new claim parity.
4363 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4364 "Not in range.");
4365 _thread_claim_parity++;
4366 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4367 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4368 "Not in range.");
4369 }
4370
4371 #ifdef ASSERT
4372 void Threads::assert_all_threads_claimed() {
4373 ALL_JAVA_THREADS(p) {
4374 const int thread_parity = p->oops_do_parity();
4375 assert((thread_parity == _thread_claim_parity),
4376 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4377 }
4378 }
4379 #endif // ASSERT
4380
4381 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4382 int cp = Threads::thread_claim_parity();
4383 ALL_JAVA_THREADS(p) {
4384 if (p->claim_oops_do(is_par, cp)) {
4385 p->oops_do(f, cf);
4386 }
4387 }
4388 VMThread* vmt = VMThread::vm_thread();
4389 if (vmt->claim_oops_do(is_par, cp)) {
4390 vmt->oops_do(f, cf);
4391 }
4392 }
4393
4394 #if INCLUDE_ALL_GCS
4395 // Used by ParallelScavenge
4396 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4397 ALL_JAVA_THREADS(p) {
4398 q->enqueue(new ThreadRootsTask(p));
4399 }
4400 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4401 }
4402
4403 // Used by Parallel Old
4404 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4405 ALL_JAVA_THREADS(p) {
4406 q->enqueue(new ThreadRootsMarkingTask(p));
4407 }
4408 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4409 }
4410 #endif // INCLUDE_ALL_GCS
4411
4412 void Threads::nmethods_do(CodeBlobClosure* cf) {
4413 ALL_JAVA_THREADS(p) {
4414 // This is used by the code cache sweeper to mark nmethods that are active
4415 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4416 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4417 if(!p->is_Code_cache_sweeper_thread()) {
4418 p->nmethods_do(cf);
4419 }
4420 }
4421 }
4422
4423 void Threads::metadata_do(void f(Metadata*)) {
4424 ALL_JAVA_THREADS(p) {
4425 p->metadata_do(f);
4426 }
4427 }
4428
4429 class ThreadHandlesClosure : public ThreadClosure {
4430 void (*_f)(Metadata*);
4431 public:
4432 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4433 virtual void do_thread(Thread* thread) {
4434 thread->metadata_handles_do(_f);
4435 }
4436 };
4437
4438 void Threads::metadata_handles_do(void f(Metadata*)) {
4439 // Only walk the Handles in Thread.
4440 ThreadHandlesClosure handles_closure(f);
4441 threads_do(&handles_closure);
4442 }
4443
4444 void Threads::deoptimized_wrt_marked_nmethods() {
4445 ALL_JAVA_THREADS(p) {
4446 p->deoptimized_wrt_marked_nmethods();
4447 }
4448 }
4449
4450
4451 // Get count Java threads that are waiting to enter the specified monitor.
4452 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4453 address monitor,
4454 bool doLock) {
4455 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4456 "must grab Threads_lock or be at safepoint");
4457 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4458
4459 int i = 0;
4460 {
4461 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4462 ALL_JAVA_THREADS(p) {
4463 if (!p->can_call_java()) continue;
4464
4465 address pending = (address)p->current_pending_monitor();
4466 if (pending == monitor) { // found a match
4467 if (i < count) result->append(p); // save the first count matches
4468 i++;
4469 }
4470 }
4471 }
4472 return result;
4473 }
4474
4475
4476 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4477 bool doLock) {
4478 assert(doLock ||
4479 Threads_lock->owned_by_self() ||
4480 SafepointSynchronize::is_at_safepoint(),
4481 "must grab Threads_lock or be at safepoint");
4482
4483 // NULL owner means not locked so we can skip the search
4484 if (owner == NULL) return NULL;
4485
4486 {
4487 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4488 ALL_JAVA_THREADS(p) {
4489 // first, see if owner is the address of a Java thread
4490 if (owner == (address)p) return p;
4491 }
4492 }
4493 // Cannot assert on lack of success here since this function may be
4494 // used by code that is trying to report useful problem information
4495 // like deadlock detection.
4496 if (UseHeavyMonitors) return NULL;
4497
4498 // If we didn't find a matching Java thread and we didn't force use of
4499 // heavyweight monitors, then the owner is the stack address of the
4500 // Lock Word in the owning Java thread's stack.
4501 //
4502 JavaThread* the_owner = NULL;
4503 {
4504 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4505 ALL_JAVA_THREADS(q) {
4506 if (q->is_lock_owned(owner)) {
4507 the_owner = q;
4508 break;
4509 }
4510 }
4511 }
4512 // cannot assert on lack of success here; see above comment
4513 return the_owner;
4514 }
4515
4516 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4517 void Threads::print_on(outputStream* st, bool print_stacks,
4518 bool internal_format, bool print_concurrent_locks) {
4519 char buf[32];
4520 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4521
4522 st->print_cr("Full thread dump %s (%s %s):",
4523 Abstract_VM_Version::vm_name(),
4524 Abstract_VM_Version::vm_release(),
4525 Abstract_VM_Version::vm_info_string());
4526 st->cr();
4527
4528 #if INCLUDE_SERVICES
4529 // Dump concurrent locks
4530 ConcurrentLocksDump concurrent_locks;
4531 if (print_concurrent_locks) {
4532 concurrent_locks.dump_at_safepoint();
4533 }
4534 #endif // INCLUDE_SERVICES
4535
4536 ALL_JAVA_THREADS(p) {
4537 ResourceMark rm;
4538 p->print_on(st);
4539 if (print_stacks) {
4540 if (internal_format) {
4541 p->trace_stack();
4542 } else {
4543 p->print_stack_on(st);
4544 }
4545 }
4546 st->cr();
4547 #if INCLUDE_SERVICES
4548 if (print_concurrent_locks) {
4549 concurrent_locks.print_locks_on(p, st);
4550 }
4551 #endif // INCLUDE_SERVICES
4552 }
4553
4554 VMThread::vm_thread()->print_on(st);
4555 st->cr();
4556 Universe::heap()->print_gc_threads_on(st);
4557 WatcherThread* wt = WatcherThread::watcher_thread();
4558 if (wt != NULL) {
4559 wt->print_on(st);
4560 st->cr();
4561 }
4562 st->flush();
4563 }
4564
4565 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4566 int buflen, bool* found_current) {
4567 if (this_thread != NULL) {
4568 bool is_current = (current == this_thread);
4569 *found_current = *found_current || is_current;
4570 st->print("%s", is_current ? "=>" : " ");
4571
4572 st->print(PTR_FORMAT, p2i(this_thread));
4573 st->print(" ");
4574 this_thread->print_on_error(st, buf, buflen);
4575 st->cr();
4576 }
4577 }
4578
4579 class PrintOnErrorClosure : public ThreadClosure {
4580 outputStream* _st;
4581 Thread* _current;
4582 char* _buf;
4583 int _buflen;
4584 bool* _found_current;
4585 public:
4586 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4587 int buflen, bool* found_current) :
4588 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4589
4590 virtual void do_thread(Thread* thread) {
4591 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4592 }
4593 };
4594
4595 // Threads::print_on_error() is called by fatal error handler. It's possible
4596 // that VM is not at safepoint and/or current thread is inside signal handler.
4597 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4598 // memory (even in resource area), it might deadlock the error handler.
4599 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4600 int buflen) {
4601 bool found_current = false;
4602 st->print_cr("Java Threads: ( => current thread )");
4603 ALL_JAVA_THREADS(thread) {
4604 print_on_error(thread, st, current, buf, buflen, &found_current);
4605 }
4606 st->cr();
4607
4608 st->print_cr("Other Threads:");
4609 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4610 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4611
4612 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4613 Universe::heap()->gc_threads_do(&print_closure);
4614
4615 if (!found_current) {
4616 st->cr();
4617 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4618 current->print_on_error(st, buf, buflen);
4619 st->cr();
4620 }
4621 st->cr();
4622 st->print_cr("Threads with active compile tasks:");
4623 print_threads_compiling(st, buf, buflen);
4624 }
4625
4626 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4627 ALL_JAVA_THREADS(thread) {
4628 if (thread->is_Compiler_thread()) {
4629 CompilerThread* ct = (CompilerThread*) thread;
4630 if (ct->task() != NULL) {
4631 thread->print_name_on_error(st, buf, buflen);
4632 ct->task()->print(st, NULL, true, true);
4633 }
4634 }
4635 }
4636 }
4637
4638
4639 // Internal SpinLock and Mutex
4640 // Based on ParkEvent
4641
4642 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4643 //
4644 // We employ SpinLocks _only for low-contention, fixed-length
4645 // short-duration critical sections where we're concerned
4646 // about native mutex_t or HotSpot Mutex:: latency.
4647 // The mux construct provides a spin-then-block mutual exclusion
4648 // mechanism.
4649 //
4650 // Testing has shown that contention on the ListLock guarding gFreeList
4651 // is common. If we implement ListLock as a simple SpinLock it's common
4652 // for the JVM to devolve to yielding with little progress. This is true
4653 // despite the fact that the critical sections protected by ListLock are
4654 // extremely short.
4655 //
4656 // TODO-FIXME: ListLock should be of type SpinLock.
4657 // We should make this a 1st-class type, integrated into the lock
4658 // hierarchy as leaf-locks. Critically, the SpinLock structure
4659 // should have sufficient padding to avoid false-sharing and excessive
4660 // cache-coherency traffic.
4661
4662
4663 typedef volatile int SpinLockT;
4664
4665 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4666 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4667 return; // normal fast-path return
4668 }
4669
4670 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4671 TEVENT(SpinAcquire - ctx);
4672 int ctr = 0;
4673 int Yields = 0;
4674 for (;;) {
4675 while (*adr != 0) {
4676 ++ctr;
4677 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4678 if (Yields > 5) {
4679 os::naked_short_sleep(1);
4680 } else {
4681 os::naked_yield();
4682 ++Yields;
4683 }
4684 } else {
4685 SpinPause();
4686 }
4687 }
4688 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4689 }
4690 }
4691
4692 void Thread::SpinRelease(volatile int * adr) {
4693 assert(*adr != 0, "invariant");
4694 OrderAccess::fence(); // guarantee at least release consistency.
4695 // Roach-motel semantics.
4696 // It's safe if subsequent LDs and STs float "up" into the critical section,
4697 // but prior LDs and STs within the critical section can't be allowed
4698 // to reorder or float past the ST that releases the lock.
4699 // Loads and stores in the critical section - which appear in program
4700 // order before the store that releases the lock - must also appear
4701 // before the store that releases the lock in memory visibility order.
4702 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4703 // the ST of 0 into the lock-word which releases the lock, so fence
4704 // more than covers this on all platforms.
4705 *adr = 0;
4706 }
4707
4708 // muxAcquire and muxRelease:
4709 //
4710 // * muxAcquire and muxRelease support a single-word lock-word construct.
4711 // The LSB of the word is set IFF the lock is held.
4712 // The remainder of the word points to the head of a singly-linked list
4713 // of threads blocked on the lock.
4714 //
4715 // * The current implementation of muxAcquire-muxRelease uses its own
4716 // dedicated Thread._MuxEvent instance. If we're interested in
4717 // minimizing the peak number of extant ParkEvent instances then
4718 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4719 // as certain invariants were satisfied. Specifically, care would need
4720 // to be taken with regards to consuming unpark() "permits".
4721 // A safe rule of thumb is that a thread would never call muxAcquire()
4722 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4723 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4724 // consume an unpark() permit intended for monitorenter, for instance.
4725 // One way around this would be to widen the restricted-range semaphore
4726 // implemented in park(). Another alternative would be to provide
4727 // multiple instances of the PlatformEvent() for each thread. One
4728 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4729 //
4730 // * Usage:
4731 // -- Only as leaf locks
4732 // -- for short-term locking only as muxAcquire does not perform
4733 // thread state transitions.
4734 //
4735 // Alternatives:
4736 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4737 // but with parking or spin-then-park instead of pure spinning.
4738 // * Use Taura-Oyama-Yonenzawa locks.
4739 // * It's possible to construct a 1-0 lock if we encode the lockword as
4740 // (List,LockByte). Acquire will CAS the full lockword while Release
4741 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4742 // acquiring threads use timers (ParkTimed) to detect and recover from
4743 // the stranding window. Thread/Node structures must be aligned on 256-byte
4744 // boundaries by using placement-new.
4745 // * Augment MCS with advisory back-link fields maintained with CAS().
4746 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4747 // The validity of the backlinks must be ratified before we trust the value.
4748 // If the backlinks are invalid the exiting thread must back-track through the
4749 // the forward links, which are always trustworthy.
4750 // * Add a successor indication. The LockWord is currently encoded as
4751 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4752 // to provide the usual futile-wakeup optimization.
4753 // See RTStt for details.
4754 // * Consider schedctl.sc_nopreempt to cover the critical section.
4755 //
4756
4757
4758 typedef volatile intptr_t MutexT; // Mux Lock-word
4759 enum MuxBits { LOCKBIT = 1 };
4760
4761 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4762 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4763 if (w == 0) return;
4764 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4765 return;
4766 }
4767
4768 TEVENT(muxAcquire - Contention);
4769 ParkEvent * const Self = Thread::current()->_MuxEvent;
4770 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4771 for (;;) {
4772 int its = (os::is_MP() ? 100 : 0) + 1;
4773
4774 // Optional spin phase: spin-then-park strategy
4775 while (--its >= 0) {
4776 w = *Lock;
4777 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4778 return;
4779 }
4780 }
4781
4782 Self->reset();
4783 Self->OnList = intptr_t(Lock);
4784 // The following fence() isn't _strictly necessary as the subsequent
4785 // CAS() both serializes execution and ratifies the fetched *Lock value.
4786 OrderAccess::fence();
4787 for (;;) {
4788 w = *Lock;
4789 if ((w & LOCKBIT) == 0) {
4790 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4791 Self->OnList = 0; // hygiene - allows stronger asserts
4792 return;
4793 }
4794 continue; // Interference -- *Lock changed -- Just retry
4795 }
4796 assert(w & LOCKBIT, "invariant");
4797 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4798 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4799 }
4800
4801 while (Self->OnList != 0) {
4802 Self->park();
4803 }
4804 }
4805 }
4806
4807 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4808 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4809 if (w == 0) return;
4810 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4811 return;
4812 }
4813
4814 TEVENT(muxAcquire - Contention);
4815 ParkEvent * ReleaseAfter = NULL;
4816 if (ev == NULL) {
4817 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4818 }
4819 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4820 for (;;) {
4821 guarantee(ev->OnList == 0, "invariant");
4822 int its = (os::is_MP() ? 100 : 0) + 1;
4823
4824 // Optional spin phase: spin-then-park strategy
4825 while (--its >= 0) {
4826 w = *Lock;
4827 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4828 if (ReleaseAfter != NULL) {
4829 ParkEvent::Release(ReleaseAfter);
4830 }
4831 return;
4832 }
4833 }
4834
4835 ev->reset();
4836 ev->OnList = intptr_t(Lock);
4837 // The following fence() isn't _strictly necessary as the subsequent
4838 // CAS() both serializes execution and ratifies the fetched *Lock value.
4839 OrderAccess::fence();
4840 for (;;) {
4841 w = *Lock;
4842 if ((w & LOCKBIT) == 0) {
4843 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4844 ev->OnList = 0;
4845 // We call ::Release while holding the outer lock, thus
4846 // artificially lengthening the critical section.
4847 // Consider deferring the ::Release() until the subsequent unlock(),
4848 // after we've dropped the outer lock.
4849 if (ReleaseAfter != NULL) {
4850 ParkEvent::Release(ReleaseAfter);
4851 }
4852 return;
4853 }
4854 continue; // Interference -- *Lock changed -- Just retry
4855 }
4856 assert(w & LOCKBIT, "invariant");
4857 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4858 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4859 }
4860
4861 while (ev->OnList != 0) {
4862 ev->park();
4863 }
4864 }
4865 }
4866
4867 // Release() must extract a successor from the list and then wake that thread.
4868 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4869 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4870 // Release() would :
4871 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4872 // (B) Extract a successor from the private list "in-hand"
4873 // (C) attempt to CAS() the residual back into *Lock over null.
4874 // If there were any newly arrived threads and the CAS() would fail.
4875 // In that case Release() would detach the RATs, re-merge the list in-hand
4876 // with the RATs and repeat as needed. Alternately, Release() might
4877 // detach and extract a successor, but then pass the residual list to the wakee.
4878 // The wakee would be responsible for reattaching and remerging before it
4879 // competed for the lock.
4880 //
4881 // Both "pop" and DMR are immune from ABA corruption -- there can be
4882 // multiple concurrent pushers, but only one popper or detacher.
4883 // This implementation pops from the head of the list. This is unfair,
4884 // but tends to provide excellent throughput as hot threads remain hot.
4885 // (We wake recently run threads first).
4886 //
4887 // All paths through muxRelease() will execute a CAS.
4888 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4889 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4890 // executed within the critical section are complete and globally visible before the
4891 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4892 void Thread::muxRelease(volatile intptr_t * Lock) {
4893 for (;;) {
4894 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4895 assert(w & LOCKBIT, "invariant");
4896 if (w == LOCKBIT) return;
4897 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4898 assert(List != NULL, "invariant");
4899 assert(List->OnList == intptr_t(Lock), "invariant");
4900 ParkEvent * const nxt = List->ListNext;
4901 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4902
4903 // The following CAS() releases the lock and pops the head element.
4904 // The CAS() also ratifies the previously fetched lock-word value.
4905 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4906 continue;
4907 }
4908 List->OnList = 0;
4909 OrderAccess::fence();
4910 List->unpark();
4911 return;
4912 }
4913 }
4914
4915
4916 void Threads::verify() {
4917 ALL_JAVA_THREADS(p) {
4918 p->verify();
4919 }
4920 VMThread* thread = VMThread::vm_thread();
4921 if (thread != NULL) thread->verify();
4922 }