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 (DeflateIdleMonitorsPerThread) {
798 ObjectSynchronizer::deflate_idle_monitors_per_thread(this);
799 }
800 if (UseShenandoahGC && ShenandoahFastSyncRoots && MonitorInUseLists) {
801 ObjectSynchronizer::thread_local_used_oops_do(this, f);
802 }
803 }
804
805 void Thread::metadata_handles_do(void f(Metadata*)) {
806 // Only walk the Handles in Thread.
807 if (metadata_handles() != NULL) {
808 for (int i = 0; i< metadata_handles()->length(); i++) {
809 f(metadata_handles()->at(i));
810 }
811 }
812 }
813
814 void Thread::print_on(outputStream* st) const {
815 // get_priority assumes osthread initialized
816 if (osthread() != NULL) {
817 int os_prio;
818 if (os::get_native_priority(this, &os_prio) == OS_OK) {
819 st->print("os_prio=%d ", os_prio);
820 }
821 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
822 ext().print_on(st);
823 osthread()->print_on(st);
824 }
825 debug_only(if (WizardMode) print_owned_locks_on(st);)
826 }
827
828 // Thread::print_on_error() is called by fatal error handler. Don't use
829 // any lock or allocate memory.
830 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
831 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
832
833 if (is_VM_thread()) { st->print("VMThread"); }
834 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
835 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
836 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
837 else { st->print("Thread"); }
838
839 if (is_Named_thread()) {
840 st->print(" \"%s\"", name());
841 }
842
843 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
844 p2i(stack_end()), p2i(stack_base()));
845
846 if (osthread()) {
847 st->print(" [id=%d]", osthread()->thread_id());
848 }
849 }
850
851 #ifdef ASSERT
852 void Thread::print_owned_locks_on(outputStream* st) const {
853 Monitor *cur = _owned_locks;
854 if (cur == NULL) {
855 st->print(" (no locks) ");
856 } else {
857 st->print_cr(" Locks owned:");
858 while (cur) {
859 cur->print_on(st);
860 cur = cur->next();
861 }
862 }
863 }
864
865 static int ref_use_count = 0;
866
867 bool Thread::owns_locks_but_compiled_lock() const {
868 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
869 if (cur != Compile_lock) return true;
870 }
871 return false;
872 }
873
874
875 #endif
876
877 #ifndef PRODUCT
878
879 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
880 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
881 // no threads which allow_vm_block's are held
882 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
883 // Check if current thread is allowed to block at a safepoint
884 if (!(_allow_safepoint_count == 0)) {
885 fatal("Possible safepoint reached by thread that does not allow it");
886 }
887 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
888 fatal("LEAF method calling lock?");
889 }
890
891 #ifdef ASSERT
892 if (potential_vm_operation && is_Java_thread()
893 && !Universe::is_bootstrapping()) {
894 // Make sure we do not hold any locks that the VM thread also uses.
895 // This could potentially lead to deadlocks
896 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
897 // Threads_lock is special, since the safepoint synchronization will not start before this is
898 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
899 // since it is used to transfer control between JavaThreads and the VMThread
900 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
901 if ((cur->allow_vm_block() &&
902 cur != Threads_lock &&
903 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
904 cur != VMOperationRequest_lock &&
905 cur != VMOperationQueue_lock) ||
906 cur->rank() == Mutex::special) {
907 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
908 }
909 }
910 }
911
912 if (GCALotAtAllSafepoints) {
913 // We could enter a safepoint here and thus have a gc
914 InterfaceSupport::check_gc_alot();
915 }
916 #endif
917 }
918 #endif
919
920 bool Thread::is_in_stack(address adr) const {
921 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
922 address end = os::current_stack_pointer();
923 // Allow non Java threads to call this without stack_base
924 if (_stack_base == NULL) return true;
925 if (stack_base() >= adr && adr >= end) return true;
926
927 return false;
928 }
929
930 bool Thread::is_in_usable_stack(address adr) const {
931 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
932 size_t usable_stack_size = _stack_size - stack_guard_size;
933
934 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
935 }
936
937
938 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
939 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
940 // used for compilation in the future. If that change is made, the need for these methods
941 // should be revisited, and they should be removed if possible.
942
943 bool Thread::is_lock_owned(address adr) const {
944 return on_local_stack(adr);
945 }
946
947 bool Thread::set_as_starting_thread() {
948 // NOTE: this must be called inside the main thread.
949 return os::create_main_thread((JavaThread*)this);
950 }
951
952 static void initialize_class(Symbol* class_name, TRAPS) {
953 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
954 InstanceKlass::cast(klass)->initialize(CHECK);
955 }
956
957
958 // Creates the initial ThreadGroup
959 static Handle create_initial_thread_group(TRAPS) {
960 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
961 instanceKlassHandle klass (THREAD, k);
962
963 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
964 {
965 JavaValue result(T_VOID);
966 JavaCalls::call_special(&result,
967 system_instance,
968 klass,
969 vmSymbols::object_initializer_name(),
970 vmSymbols::void_method_signature(),
971 CHECK_NH);
972 }
973 Universe::set_system_thread_group(system_instance());
974
975 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
976 {
977 JavaValue result(T_VOID);
978 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
979 JavaCalls::call_special(&result,
980 main_instance,
981 klass,
982 vmSymbols::object_initializer_name(),
983 vmSymbols::threadgroup_string_void_signature(),
984 system_instance,
985 string,
986 CHECK_NH);
987 }
988 return main_instance;
989 }
990
991 // Creates the initial Thread
992 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
993 TRAPS) {
994 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
995 instanceKlassHandle klass (THREAD, k);
996 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
997
998 java_lang_Thread::set_thread(thread_oop(), thread);
999 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1000 thread->set_threadObj(thread_oop());
1001
1002 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1003
1004 JavaValue result(T_VOID);
1005 JavaCalls::call_special(&result, thread_oop,
1006 klass,
1007 vmSymbols::object_initializer_name(),
1008 vmSymbols::threadgroup_string_void_signature(),
1009 thread_group,
1010 string,
1011 CHECK_NULL);
1012 return thread_oop();
1013 }
1014
1015 char java_runtime_name[128] = "";
1016 char java_runtime_version[128] = "";
1017
1018 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1019 static const char* get_java_runtime_name(TRAPS) {
1020 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1021 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1022 fieldDescriptor fd;
1023 bool found = k != NULL &&
1024 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1025 vmSymbols::string_signature(), &fd);
1026 if (found) {
1027 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1028 if (name_oop == NULL) {
1029 return NULL;
1030 }
1031 const char* name = java_lang_String::as_utf8_string(name_oop,
1032 java_runtime_name,
1033 sizeof(java_runtime_name));
1034 return name;
1035 } else {
1036 return NULL;
1037 }
1038 }
1039
1040 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1041 static const char* get_java_runtime_version(TRAPS) {
1042 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1043 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1044 fieldDescriptor fd;
1045 bool found = k != NULL &&
1046 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1047 vmSymbols::string_signature(), &fd);
1048 if (found) {
1049 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1050 if (name_oop == NULL) {
1051 return NULL;
1052 }
1053 const char* name = java_lang_String::as_utf8_string(name_oop,
1054 java_runtime_version,
1055 sizeof(java_runtime_version));
1056 return name;
1057 } else {
1058 return NULL;
1059 }
1060 }
1061
1062 // General purpose hook into Java code, run once when the VM is initialized.
1063 // The Java library method itself may be changed independently from the VM.
1064 static void call_postVMInitHook(TRAPS) {
1065 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1066 instanceKlassHandle klass (THREAD, k);
1067 if (klass.not_null()) {
1068 JavaValue result(T_VOID);
1069 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1070 vmSymbols::void_method_signature(),
1071 CHECK);
1072 }
1073 }
1074
1075 static void reset_vm_info_property(TRAPS) {
1076 // the vm info string
1077 ResourceMark rm(THREAD);
1078 const char *vm_info = VM_Version::vm_info_string();
1079
1080 // java.lang.System class
1081 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1082 instanceKlassHandle klass (THREAD, k);
1083
1084 // setProperty arguments
1085 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1086 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1087
1088 // return value
1089 JavaValue r(T_OBJECT);
1090
1091 // public static String setProperty(String key, String value);
1092 JavaCalls::call_static(&r,
1093 klass,
1094 vmSymbols::setProperty_name(),
1095 vmSymbols::string_string_string_signature(),
1096 key_str,
1097 value_str,
1098 CHECK);
1099 }
1100
1101
1102 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1103 bool daemon, TRAPS) {
1104 assert(thread_group.not_null(), "thread group should be specified");
1105 assert(threadObj() == NULL, "should only create Java thread object once");
1106
1107 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1108 instanceKlassHandle klass (THREAD, k);
1109 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1110
1111 java_lang_Thread::set_thread(thread_oop(), this);
1112 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1113 set_threadObj(thread_oop());
1114
1115 JavaValue result(T_VOID);
1116 if (thread_name != NULL) {
1117 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1118 // Thread gets assigned specified name and null target
1119 JavaCalls::call_special(&result,
1120 thread_oop,
1121 klass,
1122 vmSymbols::object_initializer_name(),
1123 vmSymbols::threadgroup_string_void_signature(),
1124 thread_group, // Argument 1
1125 name, // Argument 2
1126 THREAD);
1127 } else {
1128 // Thread gets assigned name "Thread-nnn" and null target
1129 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1130 JavaCalls::call_special(&result,
1131 thread_oop,
1132 klass,
1133 vmSymbols::object_initializer_name(),
1134 vmSymbols::threadgroup_runnable_void_signature(),
1135 thread_group, // Argument 1
1136 Handle(), // Argument 2
1137 THREAD);
1138 }
1139
1140
1141 if (daemon) {
1142 java_lang_Thread::set_daemon(thread_oop());
1143 }
1144
1145 if (HAS_PENDING_EXCEPTION) {
1146 return;
1147 }
1148
1149 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1150 Handle threadObj(THREAD, this->threadObj());
1151
1152 JavaCalls::call_special(&result,
1153 thread_group,
1154 group,
1155 vmSymbols::add_method_name(),
1156 vmSymbols::thread_void_signature(),
1157 threadObj, // Arg 1
1158 THREAD);
1159 }
1160
1161 // NamedThread -- non-JavaThread subclasses with multiple
1162 // uniquely named instances should derive from this.
1163 NamedThread::NamedThread() : Thread() {
1164 _name = NULL;
1165 _processed_thread = NULL;
1166 _gc_id = GCId::undefined();
1167 }
1168
1169 NamedThread::~NamedThread() {
1170 if (_name != NULL) {
1171 FREE_C_HEAP_ARRAY(char, _name);
1172 _name = NULL;
1173 }
1174 }
1175
1176 void NamedThread::set_name(const char* format, ...) {
1177 guarantee(_name == NULL, "Only get to set name once.");
1178 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1179 guarantee(_name != NULL, "alloc failure");
1180 va_list ap;
1181 va_start(ap, format);
1182 jio_vsnprintf(_name, max_name_len, format, ap);
1183 va_end(ap);
1184 }
1185
1186 void NamedThread::initialize_named_thread() {
1187 set_native_thread_name(name());
1188 }
1189
1190 void NamedThread::print_on(outputStream* st) const {
1191 st->print("\"%s\" ", name());
1192 Thread::print_on(st);
1193 st->cr();
1194 }
1195
1196
1197 // ======= WatcherThread ========
1198
1199 // The watcher thread exists to simulate timer interrupts. It should
1200 // be replaced by an abstraction over whatever native support for
1201 // timer interrupts exists on the platform.
1202
1203 WatcherThread* WatcherThread::_watcher_thread = NULL;
1204 bool WatcherThread::_startable = false;
1205 volatile bool WatcherThread::_should_terminate = false;
1206
1207 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1208 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1209 if (os::create_thread(this, os::watcher_thread)) {
1210 _watcher_thread = this;
1211
1212 // WatcherThread needs GCLAB for cases when it writes to Java heap,
1213 // and needs the space to evacuate. Have to initialize here, because
1214 // WatcherThread is initialized before the Universe.
1215 if (UseShenandoahGC && UseTLAB) {
1216 gclab().initialize(true);
1217 }
1218
1219 // Set the watcher thread to the highest OS priority which should not be
1220 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1221 // is created. The only normal thread using this priority is the reference
1222 // handler thread, which runs for very short intervals only.
1223 // If the VMThread's priority is not lower than the WatcherThread profiling
1224 // will be inaccurate.
1225 os::set_priority(this, MaxPriority);
1226 if (!DisableStartThread) {
1227 os::start_thread(this);
1228 }
1229 }
1230 }
1231
1232 int WatcherThread::sleep() const {
1233 // The WatcherThread does not participate in the safepoint protocol
1234 // for the PeriodicTask_lock because it is not a JavaThread.
1235 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1236
1237 if (_should_terminate) {
1238 // check for termination before we do any housekeeping or wait
1239 return 0; // we did not sleep.
1240 }
1241
1242 // remaining will be zero if there are no tasks,
1243 // causing the WatcherThread to sleep until a task is
1244 // enrolled
1245 int remaining = PeriodicTask::time_to_wait();
1246 int time_slept = 0;
1247
1248 // we expect this to timeout - we only ever get unparked when
1249 // we should terminate or when a new task has been enrolled
1250 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1251
1252 jlong time_before_loop = os::javaTimeNanos();
1253
1254 while (true) {
1255 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1256 remaining);
1257 jlong now = os::javaTimeNanos();
1258
1259 if (remaining == 0) {
1260 // if we didn't have any tasks we could have waited for a long time
1261 // consider the time_slept zero and reset time_before_loop
1262 time_slept = 0;
1263 time_before_loop = now;
1264 } else {
1265 // need to recalculate since we might have new tasks in _tasks
1266 time_slept = (int) ((now - time_before_loop) / 1000000);
1267 }
1268
1269 // Change to task list or spurious wakeup of some kind
1270 if (timedout || _should_terminate) {
1271 break;
1272 }
1273
1274 remaining = PeriodicTask::time_to_wait();
1275 if (remaining == 0) {
1276 // Last task was just disenrolled so loop around and wait until
1277 // another task gets enrolled
1278 continue;
1279 }
1280
1281 remaining -= time_slept;
1282 if (remaining <= 0) {
1283 break;
1284 }
1285 }
1286
1287 return time_slept;
1288 }
1289
1290 void WatcherThread::run() {
1291 assert(this == watcher_thread(), "just checking");
1292
1293 this->record_stack_base_and_size();
1294 this->set_native_thread_name(this->name());
1295 this->set_active_handles(JNIHandleBlock::allocate_block());
1296 while (true) {
1297 assert(watcher_thread() == Thread::current(), "thread consistency check");
1298 assert(watcher_thread() == this, "thread consistency check");
1299
1300 // Calculate how long it'll be until the next PeriodicTask work
1301 // should be done, and sleep that amount of time.
1302 int time_waited = sleep();
1303
1304 if (is_error_reported()) {
1305 // A fatal error has happened, the error handler(VMError::report_and_die)
1306 // should abort JVM after creating an error log file. However in some
1307 // rare cases, the error handler itself might deadlock. Here we try to
1308 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1309 //
1310 // This code is in WatcherThread because WatcherThread wakes up
1311 // periodically so the fatal error handler doesn't need to do anything;
1312 // also because the WatcherThread is less likely to crash than other
1313 // threads.
1314
1315 for (;;) {
1316 if (!ShowMessageBoxOnError
1317 && (OnError == NULL || OnError[0] == '\0')
1318 && Arguments::abort_hook() == NULL) {
1319 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1320 fdStream err(defaultStream::output_fd());
1321 err.print_raw_cr("# [ timer expired, abort... ]");
1322 // skip atexit/vm_exit/vm_abort hooks
1323 os::die();
1324 }
1325
1326 // Wake up 5 seconds later, the fatal handler may reset OnError or
1327 // ShowMessageBoxOnError when it is ready to abort.
1328 os::sleep(this, 5 * 1000, false);
1329 }
1330 }
1331
1332 if (_should_terminate) {
1333 // check for termination before posting the next tick
1334 break;
1335 }
1336
1337 PeriodicTask::real_time_tick(time_waited);
1338 }
1339
1340 // Signal that it is terminated
1341 {
1342 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1343 _watcher_thread = NULL;
1344 Terminator_lock->notify();
1345 }
1346 }
1347
1348 void WatcherThread::start() {
1349 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1350
1351 if (watcher_thread() == NULL && _startable) {
1352 _should_terminate = false;
1353 // Create the single instance of WatcherThread
1354 new WatcherThread();
1355 }
1356 }
1357
1358 void WatcherThread::make_startable() {
1359 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1360 _startable = true;
1361 }
1362
1363 void WatcherThread::stop() {
1364 {
1365 // Follow normal safepoint aware lock enter protocol since the
1366 // WatcherThread is stopped by another JavaThread.
1367 MutexLocker ml(PeriodicTask_lock);
1368 _should_terminate = true;
1369
1370 WatcherThread* watcher = watcher_thread();
1371 if (watcher != NULL) {
1372 // unpark the WatcherThread so it can see that it should terminate
1373 watcher->unpark();
1374 }
1375 }
1376
1377 MutexLocker mu(Terminator_lock);
1378
1379 while (watcher_thread() != NULL) {
1380 // This wait should make safepoint checks, wait without a timeout,
1381 // and wait as a suspend-equivalent condition.
1382 //
1383 // Note: If the FlatProfiler is running, then this thread is waiting
1384 // for the WatcherThread to terminate and the WatcherThread, via the
1385 // FlatProfiler task, is waiting for the external suspend request on
1386 // this thread to complete. wait_for_ext_suspend_completion() will
1387 // eventually timeout, but that takes time. Making this wait a
1388 // suspend-equivalent condition solves that timeout problem.
1389 //
1390 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1391 Mutex::_as_suspend_equivalent_flag);
1392 }
1393 }
1394
1395 void WatcherThread::unpark() {
1396 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1397 PeriodicTask_lock->notify();
1398 }
1399
1400 void WatcherThread::print_on(outputStream* st) const {
1401 st->print("\"%s\" ", name());
1402 Thread::print_on(st);
1403 st->cr();
1404 }
1405
1406 // ======= JavaThread ========
1407
1408 #if INCLUDE_JVMCI
1409
1410 jlong* JavaThread::_jvmci_old_thread_counters;
1411
1412 bool jvmci_counters_include(JavaThread* thread) {
1413 oop threadObj = thread->threadObj();
1414 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1415 }
1416
1417 void JavaThread::collect_counters(typeArrayOop array) {
1418 if (JVMCICounterSize > 0) {
1419 MutexLocker tl(Threads_lock);
1420 for (int i = 0; i < array->length(); i++) {
1421 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1422 }
1423 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1424 if (jvmci_counters_include(tp)) {
1425 for (int i = 0; i < array->length(); i++) {
1426 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1427 }
1428 }
1429 }
1430 }
1431 }
1432
1433 #endif // INCLUDE_JVMCI
1434
1435 // A JavaThread is a normal Java thread
1436
1437 void JavaThread::initialize() {
1438 // Initialize fields
1439
1440 set_saved_exception_pc(NULL);
1441 set_threadObj(NULL);
1442 _anchor.clear();
1443 set_entry_point(NULL);
1444 set_jni_functions(jni_functions());
1445 set_callee_target(NULL);
1446 set_vm_result(NULL);
1447 set_vm_result_2(NULL);
1448 set_vframe_array_head(NULL);
1449 set_vframe_array_last(NULL);
1450 set_deferred_locals(NULL);
1451 set_deopt_mark(NULL);
1452 set_deopt_compiled_method(NULL);
1453 clear_must_deopt_id();
1454 set_monitor_chunks(NULL);
1455 set_next(NULL);
1456 set_thread_state(_thread_new);
1457 _terminated = _not_terminated;
1458 _privileged_stack_top = NULL;
1459 _array_for_gc = NULL;
1460 _suspend_equivalent = false;
1461 _in_deopt_handler = 0;
1462 _doing_unsafe_access = false;
1463 _stack_guard_state = stack_guard_unused;
1464 #if INCLUDE_JVMCI
1465 _pending_monitorenter = false;
1466 _pending_deoptimization = -1;
1467 _pending_failed_speculation = NULL;
1468 _pending_transfer_to_interpreter = false;
1469 _adjusting_comp_level = false;
1470 _jvmci._alternate_call_target = NULL;
1471 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1472 if (JVMCICounterSize > 0) {
1473 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1474 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1475 } else {
1476 _jvmci_counters = NULL;
1477 }
1478 #endif // INCLUDE_JVMCI
1479 _reserved_stack_activation = NULL; // stack base not known yet
1480 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1481 _exception_pc = 0;
1482 _exception_handler_pc = 0;
1483 _is_method_handle_return = 0;
1484 _jvmti_thread_state= NULL;
1485 _should_post_on_exceptions_flag = JNI_FALSE;
1486 _jvmti_get_loaded_classes_closure = NULL;
1487 _interp_only_mode = 0;
1488 _special_runtime_exit_condition = _no_async_condition;
1489 _pending_async_exception = NULL;
1490 _thread_stat = NULL;
1491 _thread_stat = new ThreadStatistics();
1492 _blocked_on_compilation = false;
1493 _jni_active_critical = 0;
1494 _pending_jni_exception_check_fn = NULL;
1495 _do_not_unlock_if_synchronized = false;
1496 _cached_monitor_info = NULL;
1497 _parker = Parker::Allocate(this);
1498
1499 #ifndef PRODUCT
1500 _jmp_ring_index = 0;
1501 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1502 record_jump(NULL, NULL, NULL, 0);
1503 }
1504 #endif // PRODUCT
1505
1506 set_thread_profiler(NULL);
1507 if (FlatProfiler::is_active()) {
1508 // This is where we would decide to either give each thread it's own profiler
1509 // or use one global one from FlatProfiler,
1510 // or up to some count of the number of profiled threads, etc.
1511 ThreadProfiler* pp = new ThreadProfiler();
1512 pp->engage();
1513 set_thread_profiler(pp);
1514 }
1515
1516 // Setup safepoint state info for this thread
1517 ThreadSafepointState::create(this);
1518
1519 debug_only(_java_call_counter = 0);
1520
1521 // JVMTI PopFrame support
1522 _popframe_condition = popframe_inactive;
1523 _popframe_preserved_args = NULL;
1524 _popframe_preserved_args_size = 0;
1525 _frames_to_pop_failed_realloc = 0;
1526
1527 pd_initialize();
1528 }
1529
1530 #if INCLUDE_ALL_GCS
1531 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1532 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1533 bool JavaThread::_evacuation_in_progress_global = false;
1534 #endif // INCLUDE_ALL_GCS
1535
1536 JavaThread::JavaThread(bool is_attaching_via_jni) :
1537 Thread()
1538 #if INCLUDE_ALL_GCS
1539 , _satb_mark_queue(&_satb_mark_queue_set),
1540 _dirty_card_queue(&_dirty_card_queue_set),
1541 _evacuation_in_progress(_evacuation_in_progress_global)
1542 #endif // INCLUDE_ALL_GCS
1543 {
1544 initialize();
1545 if (is_attaching_via_jni) {
1546 _jni_attach_state = _attaching_via_jni;
1547 } else {
1548 _jni_attach_state = _not_attaching_via_jni;
1549 }
1550 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1551 }
1552
1553 bool JavaThread::reguard_stack(address cur_sp) {
1554 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1555 && _stack_guard_state != stack_guard_reserved_disabled) {
1556 return true; // Stack already guarded or guard pages not needed.
1557 }
1558
1559 if (register_stack_overflow()) {
1560 // For those architectures which have separate register and
1561 // memory stacks, we must check the register stack to see if
1562 // it has overflowed.
1563 return false;
1564 }
1565
1566 // Java code never executes within the yellow zone: the latter is only
1567 // there to provoke an exception during stack banging. If java code
1568 // is executing there, either StackShadowPages should be larger, or
1569 // some exception code in c1, c2 or the interpreter isn't unwinding
1570 // when it should.
1571 guarantee(cur_sp > stack_reserved_zone_base(),
1572 "not enough space to reguard - increase StackShadowPages");
1573 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1574 enable_stack_yellow_reserved_zone();
1575 if (reserved_stack_activation() != stack_base()) {
1576 set_reserved_stack_activation(stack_base());
1577 }
1578 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1579 set_reserved_stack_activation(stack_base());
1580 enable_stack_reserved_zone();
1581 }
1582 return true;
1583 }
1584
1585 bool JavaThread::reguard_stack(void) {
1586 return reguard_stack(os::current_stack_pointer());
1587 }
1588
1589
1590 void JavaThread::block_if_vm_exited() {
1591 if (_terminated == _vm_exited) {
1592 // _vm_exited is set at safepoint, and Threads_lock is never released
1593 // we will block here forever
1594 Threads_lock->lock_without_safepoint_check();
1595 ShouldNotReachHere();
1596 }
1597 }
1598
1599
1600 // Remove this ifdef when C1 is ported to the compiler interface.
1601 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1602 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1603
1604 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1605 Thread()
1606 #if INCLUDE_ALL_GCS
1607 , _satb_mark_queue(&_satb_mark_queue_set),
1608 _dirty_card_queue(&_dirty_card_queue_set),
1609 _evacuation_in_progress(_evacuation_in_progress_global)
1610 #endif // INCLUDE_ALL_GCS
1611 {
1612 initialize();
1613 _jni_attach_state = _not_attaching_via_jni;
1614 set_entry_point(entry_point);
1615 // Create the native thread itself.
1616 // %note runtime_23
1617 os::ThreadType thr_type = os::java_thread;
1618 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1619 os::java_thread;
1620 os::create_thread(this, thr_type, stack_sz);
1621 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1622 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1623 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1624 // the exception consists of creating the exception object & initializing it, initialization
1625 // will leave the VM via a JavaCall and then all locks must be unlocked).
1626 //
1627 // The thread is still suspended when we reach here. Thread must be explicit started
1628 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1629 // by calling Threads:add. The reason why this is not done here, is because the thread
1630 // object must be fully initialized (take a look at JVM_Start)
1631 }
1632
1633 JavaThread::~JavaThread() {
1634
1635 // JSR166 -- return the parker to the free list
1636 Parker::Release(_parker);
1637 _parker = NULL;
1638
1639 // Free any remaining previous UnrollBlock
1640 vframeArray* old_array = vframe_array_last();
1641
1642 if (old_array != NULL) {
1643 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1644 old_array->set_unroll_block(NULL);
1645 delete old_info;
1646 delete old_array;
1647 }
1648
1649 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1650 if (deferred != NULL) {
1651 // This can only happen if thread is destroyed before deoptimization occurs.
1652 assert(deferred->length() != 0, "empty array!");
1653 do {
1654 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1655 deferred->remove_at(0);
1656 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1657 delete dlv;
1658 } while (deferred->length() != 0);
1659 delete deferred;
1660 }
1661
1662 // All Java related clean up happens in exit
1663 ThreadSafepointState::destroy(this);
1664 if (_thread_profiler != NULL) delete _thread_profiler;
1665 if (_thread_stat != NULL) delete _thread_stat;
1666
1667 #if INCLUDE_JVMCI
1668 if (JVMCICounterSize > 0) {
1669 if (jvmci_counters_include(this)) {
1670 for (int i = 0; i < JVMCICounterSize; i++) {
1671 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1672 }
1673 }
1674 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1675 }
1676 #endif // INCLUDE_JVMCI
1677 }
1678
1679
1680 // The first routine called by a new Java thread
1681 void JavaThread::run() {
1682 // initialize thread-local alloc buffer related fields
1683 this->initialize_tlab();
1684
1685 // used to test validity of stack trace backs
1686 this->record_base_of_stack_pointer();
1687
1688 // Record real stack base and size.
1689 this->record_stack_base_and_size();
1690
1691 this->create_stack_guard_pages();
1692
1693 this->cache_global_variables();
1694
1695 // Thread is now sufficient initialized to be handled by the safepoint code as being
1696 // in the VM. Change thread state from _thread_new to _thread_in_vm
1697 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1698
1699 assert(JavaThread::current() == this, "sanity check");
1700 assert(!Thread::current()->owns_locks(), "sanity check");
1701
1702 DTRACE_THREAD_PROBE(start, this);
1703
1704 // This operation might block. We call that after all safepoint checks for a new thread has
1705 // been completed.
1706 this->set_active_handles(JNIHandleBlock::allocate_block());
1707
1708 if (JvmtiExport::should_post_thread_life()) {
1709 JvmtiExport::post_thread_start(this);
1710 }
1711
1712 EventThreadStart event;
1713 if (event.should_commit()) {
1714 event.set_thread(THREAD_TRACE_ID(this));
1715 event.commit();
1716 }
1717
1718 // We call another function to do the rest so we are sure that the stack addresses used
1719 // from there will be lower than the stack base just computed
1720 thread_main_inner();
1721
1722 // Note, thread is no longer valid at this point!
1723 }
1724
1725
1726 void JavaThread::thread_main_inner() {
1727 assert(JavaThread::current() == this, "sanity check");
1728 assert(this->threadObj() != NULL, "just checking");
1729
1730 // Execute thread entry point unless this thread has a pending exception
1731 // or has been stopped before starting.
1732 // Note: Due to JVM_StopThread we can have pending exceptions already!
1733 if (!this->has_pending_exception() &&
1734 !java_lang_Thread::is_stillborn(this->threadObj())) {
1735 {
1736 ResourceMark rm(this);
1737 this->set_native_thread_name(this->get_thread_name());
1738 }
1739 HandleMark hm(this);
1740 this->entry_point()(this, this);
1741 }
1742
1743 DTRACE_THREAD_PROBE(stop, this);
1744
1745 this->exit(false);
1746 delete this;
1747 }
1748
1749
1750 static void ensure_join(JavaThread* thread) {
1751 // We do not need to grap the Threads_lock, since we are operating on ourself.
1752 Handle threadObj(thread, thread->threadObj());
1753 assert(threadObj.not_null(), "java thread object must exist");
1754 ObjectLocker lock(threadObj, thread);
1755 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1756 thread->clear_pending_exception();
1757 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1758 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1759 // Clear the native thread instance - this makes isAlive return false and allows the join()
1760 // to complete once we've done the notify_all below
1761 java_lang_Thread::set_thread(threadObj(), NULL);
1762 lock.notify_all(thread);
1763 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1764 thread->clear_pending_exception();
1765 }
1766
1767
1768 // For any new cleanup additions, please check to see if they need to be applied to
1769 // cleanup_failed_attach_current_thread as well.
1770 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1771 assert(this == JavaThread::current(), "thread consistency check");
1772
1773 HandleMark hm(this);
1774 Handle uncaught_exception(this, this->pending_exception());
1775 this->clear_pending_exception();
1776 Handle threadObj(this, this->threadObj());
1777 assert(threadObj.not_null(), "Java thread object should be created");
1778
1779 if (get_thread_profiler() != NULL) {
1780 get_thread_profiler()->disengage();
1781 ResourceMark rm;
1782 get_thread_profiler()->print(get_thread_name());
1783 }
1784
1785
1786 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1787 {
1788 EXCEPTION_MARK;
1789
1790 CLEAR_PENDING_EXCEPTION;
1791 }
1792 if (!destroy_vm) {
1793 if (uncaught_exception.not_null()) {
1794 EXCEPTION_MARK;
1795 // Call method Thread.dispatchUncaughtException().
1796 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1797 JavaValue result(T_VOID);
1798 JavaCalls::call_virtual(&result,
1799 threadObj, thread_klass,
1800 vmSymbols::dispatchUncaughtException_name(),
1801 vmSymbols::throwable_void_signature(),
1802 uncaught_exception,
1803 THREAD);
1804 if (HAS_PENDING_EXCEPTION) {
1805 ResourceMark rm(this);
1806 jio_fprintf(defaultStream::error_stream(),
1807 "\nException: %s thrown from the UncaughtExceptionHandler"
1808 " in thread \"%s\"\n",
1809 pending_exception()->klass()->external_name(),
1810 get_thread_name());
1811 CLEAR_PENDING_EXCEPTION;
1812 }
1813 }
1814
1815 // Called before the java thread exit since we want to read info
1816 // from java_lang_Thread object
1817 EventThreadEnd event;
1818 if (event.should_commit()) {
1819 event.set_thread(THREAD_TRACE_ID(this));
1820 event.commit();
1821 }
1822
1823 // Call after last event on thread
1824 EVENT_THREAD_EXIT(this);
1825
1826 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1827 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1828 // is deprecated anyhow.
1829 if (!is_Compiler_thread()) {
1830 int count = 3;
1831 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1832 EXCEPTION_MARK;
1833 JavaValue result(T_VOID);
1834 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1835 JavaCalls::call_virtual(&result,
1836 threadObj, thread_klass,
1837 vmSymbols::exit_method_name(),
1838 vmSymbols::void_method_signature(),
1839 THREAD);
1840 CLEAR_PENDING_EXCEPTION;
1841 }
1842 }
1843 // notify JVMTI
1844 if (JvmtiExport::should_post_thread_life()) {
1845 JvmtiExport::post_thread_end(this);
1846 }
1847
1848 // We have notified the agents that we are exiting, before we go on,
1849 // we must check for a pending external suspend request and honor it
1850 // in order to not surprise the thread that made the suspend request.
1851 while (true) {
1852 {
1853 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1854 if (!is_external_suspend()) {
1855 set_terminated(_thread_exiting);
1856 ThreadService::current_thread_exiting(this);
1857 break;
1858 }
1859 // Implied else:
1860 // Things get a little tricky here. We have a pending external
1861 // suspend request, but we are holding the SR_lock so we
1862 // can't just self-suspend. So we temporarily drop the lock
1863 // and then self-suspend.
1864 }
1865
1866 ThreadBlockInVM tbivm(this);
1867 java_suspend_self();
1868
1869 // We're done with this suspend request, but we have to loop around
1870 // and check again. Eventually we will get SR_lock without a pending
1871 // external suspend request and will be able to mark ourselves as
1872 // exiting.
1873 }
1874 // no more external suspends are allowed at this point
1875 } else {
1876 // before_exit() has already posted JVMTI THREAD_END events
1877 }
1878
1879 // Notify waiters on thread object. This has to be done after exit() is called
1880 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1881 // group should have the destroyed bit set before waiters are notified).
1882 ensure_join(this);
1883 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1884
1885 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1886 // held by this thread must be released. The spec does not distinguish
1887 // between JNI-acquired and regular Java monitors. We can only see
1888 // regular Java monitors here if monitor enter-exit matching is broken.
1889 //
1890 // Optionally release any monitors for regular JavaThread exits. This
1891 // is provided as a work around for any bugs in monitor enter-exit
1892 // matching. This can be expensive so it is not enabled by default.
1893 //
1894 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1895 // ObjectSynchronizer::release_monitors_owned_by_thread().
1896 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1897 // Sanity check even though JNI DetachCurrentThread() would have
1898 // returned JNI_ERR if there was a Java frame. JavaThread exit
1899 // should be done executing Java code by the time we get here.
1900 assert(!this->has_last_Java_frame(),
1901 "should not have a Java frame when detaching or exiting");
1902 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1903 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1904 }
1905
1906 // These things needs to be done while we are still a Java Thread. Make sure that thread
1907 // is in a consistent state, in case GC happens
1908 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1909
1910 if (active_handles() != NULL) {
1911 JNIHandleBlock* block = active_handles();
1912 set_active_handles(NULL);
1913 JNIHandleBlock::release_block(block);
1914 }
1915
1916 if (free_handle_block() != NULL) {
1917 JNIHandleBlock* block = free_handle_block();
1918 set_free_handle_block(NULL);
1919 JNIHandleBlock::release_block(block);
1920 }
1921
1922 // These have to be removed while this is still a valid thread.
1923 remove_stack_guard_pages();
1924
1925 if (UseTLAB) {
1926 tlab().make_parsable(true); // retire TLAB
1927 }
1928
1929 if (JvmtiEnv::environments_might_exist()) {
1930 JvmtiExport::cleanup_thread(this);
1931 }
1932
1933 // We must flush any deferred card marks before removing a thread from
1934 // the list of active threads.
1935 Universe::heap()->flush_deferred_store_barrier(this);
1936 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1937
1938 #if INCLUDE_ALL_GCS
1939 // We must flush the G1-related buffers before removing a thread
1940 // from the list of active threads. We must do this after any deferred
1941 // card marks have been flushed (above) so that any entries that are
1942 // added to the thread's dirty card queue as a result are not lost.
1943 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
1944 flush_barrier_queues();
1945 }
1946 if (UseShenandoahGC && UseTLAB) {
1947 gclab().make_parsable(true);
1948 }
1949 #endif // INCLUDE_ALL_GCS
1950
1951 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1952 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1953 os::current_thread_id());
1954
1955 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1956 Threads::remove(this);
1957 }
1958
1959 #if INCLUDE_ALL_GCS
1960 // Flush G1-related queues.
1961 void JavaThread::flush_barrier_queues() {
1962 satb_mark_queue().flush();
1963 dirty_card_queue().flush();
1964 }
1965
1966 void JavaThread::initialize_queues() {
1967 assert(!SafepointSynchronize::is_at_safepoint(),
1968 "we should not be at a safepoint");
1969
1970 SATBMarkQueue& satb_queue = satb_mark_queue();
1971 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1972 // The SATB queue should have been constructed with its active
1973 // field set to false.
1974 assert(!satb_queue.is_active(), "SATB queue should not be active");
1975 assert(satb_queue.is_empty(), "SATB queue should be empty");
1976 // If we are creating the thread during a marking cycle, we should
1977 // set the active field of the SATB queue to true.
1978 if (satb_queue_set.is_active()) {
1979 satb_queue.set_active(true);
1980 }
1981
1982 DirtyCardQueue& dirty_queue = dirty_card_queue();
1983 // The dirty card queue should have been constructed with its
1984 // active field set to true.
1985 assert(dirty_queue.is_active(), "dirty card queue should be active");
1986
1987 _evacuation_in_progress = _evacuation_in_progress_global;
1988 }
1989
1990 bool JavaThread::evacuation_in_progress() const {
1991 return _evacuation_in_progress;
1992 }
1993
1994 void JavaThread::set_evacuation_in_progress(bool in_prog) {
1995 _evacuation_in_progress = in_prog;
1996 }
1997
1998 void JavaThread::set_evacuation_in_progress_all_threads(bool in_prog) {
1999 assert_locked_or_safepoint(Threads_lock);
2000 _evacuation_in_progress_global = in_prog;
2001 for (JavaThread* t = Threads::first(); t != NULL; t = t->next()) {
2002 t->set_evacuation_in_progress(in_prog);
2003 }
2004 }
2005 #endif // INCLUDE_ALL_GCS
2006
2007 void JavaThread::cleanup_failed_attach_current_thread() {
2008 if (get_thread_profiler() != NULL) {
2009 get_thread_profiler()->disengage();
2010 ResourceMark rm;
2011 get_thread_profiler()->print(get_thread_name());
2012 }
2013
2014 if (active_handles() != NULL) {
2015 JNIHandleBlock* block = active_handles();
2016 set_active_handles(NULL);
2017 JNIHandleBlock::release_block(block);
2018 }
2019
2020 if (free_handle_block() != NULL) {
2021 JNIHandleBlock* block = free_handle_block();
2022 set_free_handle_block(NULL);
2023 JNIHandleBlock::release_block(block);
2024 }
2025
2026 // These have to be removed while this is still a valid thread.
2027 remove_stack_guard_pages();
2028
2029 if (UseTLAB) {
2030 tlab().make_parsable(true); // retire TLAB, if any
2031 }
2032
2033 #if INCLUDE_ALL_GCS
2034 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
2035 flush_barrier_queues();
2036 }
2037 if (UseShenandoahGC && UseTLAB) {
2038 gclab().make_parsable(true);
2039 }
2040 #endif // INCLUDE_ALL_GCS
2041
2042 Threads::remove(this);
2043 delete this;
2044 }
2045
2046
2047
2048
2049 JavaThread* JavaThread::active() {
2050 Thread* thread = Thread::current();
2051 if (thread->is_Java_thread()) {
2052 return (JavaThread*) thread;
2053 } else {
2054 assert(thread->is_VM_thread(), "this must be a vm thread");
2055 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2056 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2057 assert(ret->is_Java_thread(), "must be a Java thread");
2058 return ret;
2059 }
2060 }
2061
2062 bool JavaThread::is_lock_owned(address adr) const {
2063 if (Thread::is_lock_owned(adr)) return true;
2064
2065 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2066 if (chunk->contains(adr)) return true;
2067 }
2068
2069 return false;
2070 }
2071
2072
2073 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2074 chunk->set_next(monitor_chunks());
2075 set_monitor_chunks(chunk);
2076 }
2077
2078 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2079 guarantee(monitor_chunks() != NULL, "must be non empty");
2080 if (monitor_chunks() == chunk) {
2081 set_monitor_chunks(chunk->next());
2082 } else {
2083 MonitorChunk* prev = monitor_chunks();
2084 while (prev->next() != chunk) prev = prev->next();
2085 prev->set_next(chunk->next());
2086 }
2087 }
2088
2089 // JVM support.
2090
2091 // Note: this function shouldn't block if it's called in
2092 // _thread_in_native_trans state (such as from
2093 // check_special_condition_for_native_trans()).
2094 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2095
2096 if (has_last_Java_frame() && has_async_condition()) {
2097 // If we are at a polling page safepoint (not a poll return)
2098 // then we must defer async exception because live registers
2099 // will be clobbered by the exception path. Poll return is
2100 // ok because the call we a returning from already collides
2101 // with exception handling registers and so there is no issue.
2102 // (The exception handling path kills call result registers but
2103 // this is ok since the exception kills the result anyway).
2104
2105 if (is_at_poll_safepoint()) {
2106 // if the code we are returning to has deoptimized we must defer
2107 // the exception otherwise live registers get clobbered on the
2108 // exception path before deoptimization is able to retrieve them.
2109 //
2110 RegisterMap map(this, false);
2111 frame caller_fr = last_frame().sender(&map);
2112 assert(caller_fr.is_compiled_frame(), "what?");
2113 if (caller_fr.is_deoptimized_frame()) {
2114 log_info(exceptions)("deferred async exception at compiled safepoint");
2115 return;
2116 }
2117 }
2118 }
2119
2120 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2121 if (condition == _no_async_condition) {
2122 // Conditions have changed since has_special_runtime_exit_condition()
2123 // was called:
2124 // - if we were here only because of an external suspend request,
2125 // then that was taken care of above (or cancelled) so we are done
2126 // - if we were here because of another async request, then it has
2127 // been cleared between the has_special_runtime_exit_condition()
2128 // and now so again we are done
2129 return;
2130 }
2131
2132 // Check for pending async. exception
2133 if (_pending_async_exception != NULL) {
2134 // Only overwrite an already pending exception, if it is not a threadDeath.
2135 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2136
2137 // We cannot call Exceptions::_throw(...) here because we cannot block
2138 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2139
2140 if (log_is_enabled(Info, exceptions)) {
2141 ResourceMark rm;
2142 outputStream* logstream = Log(exceptions)::info_stream();
2143 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2144 if (has_last_Java_frame()) {
2145 frame f = last_frame();
2146 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2147 }
2148 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2149 }
2150 _pending_async_exception = NULL;
2151 clear_has_async_exception();
2152 }
2153 }
2154
2155 if (check_unsafe_error &&
2156 condition == _async_unsafe_access_error && !has_pending_exception()) {
2157 condition = _no_async_condition; // done
2158 switch (thread_state()) {
2159 case _thread_in_vm: {
2160 JavaThread* THREAD = this;
2161 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2162 }
2163 case _thread_in_native: {
2164 ThreadInVMfromNative tiv(this);
2165 JavaThread* THREAD = this;
2166 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2167 }
2168 case _thread_in_Java: {
2169 ThreadInVMfromJava tiv(this);
2170 JavaThread* THREAD = this;
2171 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2172 }
2173 default:
2174 ShouldNotReachHere();
2175 }
2176 }
2177
2178 assert(condition == _no_async_condition || has_pending_exception() ||
2179 (!check_unsafe_error && condition == _async_unsafe_access_error),
2180 "must have handled the async condition, if no exception");
2181 }
2182
2183 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2184 //
2185 // Check for pending external suspend. Internal suspend requests do
2186 // not use handle_special_runtime_exit_condition().
2187 // If JNIEnv proxies are allowed, don't self-suspend if the target
2188 // thread is not the current thread. In older versions of jdbx, jdbx
2189 // threads could call into the VM with another thread's JNIEnv so we
2190 // can be here operating on behalf of a suspended thread (4432884).
2191 bool do_self_suspend = is_external_suspend_with_lock();
2192 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2193 //
2194 // Because thread is external suspended the safepoint code will count
2195 // thread as at a safepoint. This can be odd because we can be here
2196 // as _thread_in_Java which would normally transition to _thread_blocked
2197 // at a safepoint. We would like to mark the thread as _thread_blocked
2198 // before calling java_suspend_self like all other callers of it but
2199 // we must then observe proper safepoint protocol. (We can't leave
2200 // _thread_blocked with a safepoint in progress). However we can be
2201 // here as _thread_in_native_trans so we can't use a normal transition
2202 // constructor/destructor pair because they assert on that type of
2203 // transition. We could do something like:
2204 //
2205 // JavaThreadState state = thread_state();
2206 // set_thread_state(_thread_in_vm);
2207 // {
2208 // ThreadBlockInVM tbivm(this);
2209 // java_suspend_self()
2210 // }
2211 // set_thread_state(_thread_in_vm_trans);
2212 // if (safepoint) block;
2213 // set_thread_state(state);
2214 //
2215 // but that is pretty messy. Instead we just go with the way the
2216 // code has worked before and note that this is the only path to
2217 // java_suspend_self that doesn't put the thread in _thread_blocked
2218 // mode.
2219
2220 frame_anchor()->make_walkable(this);
2221 java_suspend_self();
2222
2223 // We might be here for reasons in addition to the self-suspend request
2224 // so check for other async requests.
2225 }
2226
2227 if (check_asyncs) {
2228 check_and_handle_async_exceptions();
2229 }
2230 }
2231
2232 void JavaThread::send_thread_stop(oop java_throwable) {
2233 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2234 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2235 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2236
2237 // Do not throw asynchronous exceptions against the compiler thread
2238 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2239 if (!can_call_java()) return;
2240
2241 {
2242 // Actually throw the Throwable against the target Thread - however
2243 // only if there is no thread death exception installed already.
2244 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2245 // If the topmost frame is a runtime stub, then we are calling into
2246 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2247 // must deoptimize the caller before continuing, as the compiled exception handler table
2248 // may not be valid
2249 if (has_last_Java_frame()) {
2250 frame f = last_frame();
2251 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2252 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2253 RegisterMap reg_map(this, UseBiasedLocking);
2254 frame compiled_frame = f.sender(®_map);
2255 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2256 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2257 }
2258 }
2259 }
2260
2261 // Set async. pending exception in thread.
2262 set_pending_async_exception(java_throwable);
2263
2264 if (log_is_enabled(Info, exceptions)) {
2265 ResourceMark rm;
2266 log_info(exceptions)("Pending Async. exception installed of type: %s",
2267 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2268 }
2269 // for AbortVMOnException flag
2270 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2271 }
2272 }
2273
2274
2275 // Interrupt thread so it will wake up from a potential wait()
2276 Thread::interrupt(this);
2277 }
2278
2279 // External suspension mechanism.
2280 //
2281 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2282 // to any VM_locks and it is at a transition
2283 // Self-suspension will happen on the transition out of the vm.
2284 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2285 //
2286 // Guarantees on return:
2287 // + Target thread will not execute any new bytecode (that's why we need to
2288 // force a safepoint)
2289 // + Target thread will not enter any new monitors
2290 //
2291 void JavaThread::java_suspend() {
2292 { MutexLocker mu(Threads_lock);
2293 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2294 return;
2295 }
2296 }
2297
2298 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2299 if (!is_external_suspend()) {
2300 // a racing resume has cancelled us; bail out now
2301 return;
2302 }
2303
2304 // suspend is done
2305 uint32_t debug_bits = 0;
2306 // Warning: is_ext_suspend_completed() may temporarily drop the
2307 // SR_lock to allow the thread to reach a stable thread state if
2308 // it is currently in a transient thread state.
2309 if (is_ext_suspend_completed(false /* !called_by_wait */,
2310 SuspendRetryDelay, &debug_bits)) {
2311 return;
2312 }
2313 }
2314
2315 VM_ForceSafepoint vm_suspend;
2316 VMThread::execute(&vm_suspend);
2317 }
2318
2319 // Part II of external suspension.
2320 // A JavaThread self suspends when it detects a pending external suspend
2321 // request. This is usually on transitions. It is also done in places
2322 // where continuing to the next transition would surprise the caller,
2323 // e.g., monitor entry.
2324 //
2325 // Returns the number of times that the thread self-suspended.
2326 //
2327 // Note: DO NOT call java_suspend_self() when you just want to block current
2328 // thread. java_suspend_self() is the second stage of cooperative
2329 // suspension for external suspend requests and should only be used
2330 // to complete an external suspend request.
2331 //
2332 int JavaThread::java_suspend_self() {
2333 int ret = 0;
2334
2335 // we are in the process of exiting so don't suspend
2336 if (is_exiting()) {
2337 clear_external_suspend();
2338 return ret;
2339 }
2340
2341 assert(_anchor.walkable() ||
2342 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2343 "must have walkable stack");
2344
2345 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2346
2347 assert(!this->is_ext_suspended(),
2348 "a thread trying to self-suspend should not already be suspended");
2349
2350 if (this->is_suspend_equivalent()) {
2351 // If we are self-suspending as a result of the lifting of a
2352 // suspend equivalent condition, then the suspend_equivalent
2353 // flag is not cleared until we set the ext_suspended flag so
2354 // that wait_for_ext_suspend_completion() returns consistent
2355 // results.
2356 this->clear_suspend_equivalent();
2357 }
2358
2359 // A racing resume may have cancelled us before we grabbed SR_lock
2360 // above. Or another external suspend request could be waiting for us
2361 // by the time we return from SR_lock()->wait(). The thread
2362 // that requested the suspension may already be trying to walk our
2363 // stack and if we return now, we can change the stack out from under
2364 // it. This would be a "bad thing (TM)" and cause the stack walker
2365 // to crash. We stay self-suspended until there are no more pending
2366 // external suspend requests.
2367 while (is_external_suspend()) {
2368 ret++;
2369 this->set_ext_suspended();
2370
2371 // _ext_suspended flag is cleared by java_resume()
2372 while (is_ext_suspended()) {
2373 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2374 }
2375 }
2376
2377 return ret;
2378 }
2379
2380 #ifdef ASSERT
2381 // verify the JavaThread has not yet been published in the Threads::list, and
2382 // hence doesn't need protection from concurrent access at this stage
2383 void JavaThread::verify_not_published() {
2384 if (!Threads_lock->owned_by_self()) {
2385 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2386 assert(!Threads::includes(this),
2387 "java thread shouldn't have been published yet!");
2388 } else {
2389 assert(!Threads::includes(this),
2390 "java thread shouldn't have been published yet!");
2391 }
2392 }
2393 #endif
2394
2395 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2396 // progress or when _suspend_flags is non-zero.
2397 // Current thread needs to self-suspend if there is a suspend request and/or
2398 // block if a safepoint is in progress.
2399 // Async exception ISN'T checked.
2400 // Note only the ThreadInVMfromNative transition can call this function
2401 // directly and when thread state is _thread_in_native_trans
2402 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2403 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2404
2405 JavaThread *curJT = JavaThread::current();
2406 bool do_self_suspend = thread->is_external_suspend();
2407
2408 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2409
2410 // If JNIEnv proxies are allowed, don't self-suspend if the target
2411 // thread is not the current thread. In older versions of jdbx, jdbx
2412 // threads could call into the VM with another thread's JNIEnv so we
2413 // can be here operating on behalf of a suspended thread (4432884).
2414 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2415 JavaThreadState state = thread->thread_state();
2416
2417 // We mark this thread_blocked state as a suspend-equivalent so
2418 // that a caller to is_ext_suspend_completed() won't be confused.
2419 // The suspend-equivalent state is cleared by java_suspend_self().
2420 thread->set_suspend_equivalent();
2421
2422 // If the safepoint code sees the _thread_in_native_trans state, it will
2423 // wait until the thread changes to other thread state. There is no
2424 // guarantee on how soon we can obtain the SR_lock and complete the
2425 // self-suspend request. It would be a bad idea to let safepoint wait for
2426 // too long. Temporarily change the state to _thread_blocked to
2427 // let the VM thread know that this thread is ready for GC. The problem
2428 // of changing thread state is that safepoint could happen just after
2429 // java_suspend_self() returns after being resumed, and VM thread will
2430 // see the _thread_blocked state. We must check for safepoint
2431 // after restoring the state and make sure we won't leave while a safepoint
2432 // is in progress.
2433 thread->set_thread_state(_thread_blocked);
2434 thread->java_suspend_self();
2435 thread->set_thread_state(state);
2436 // Make sure new state is seen by VM thread
2437 if (os::is_MP()) {
2438 if (UseMembar) {
2439 // Force a fence between the write above and read below
2440 OrderAccess::fence();
2441 } else {
2442 // Must use this rather than serialization page in particular on Windows
2443 InterfaceSupport::serialize_memory(thread);
2444 }
2445 }
2446 }
2447
2448 if (SafepointSynchronize::do_call_back()) {
2449 // If we are safepointing, then block the caller which may not be
2450 // the same as the target thread (see above).
2451 SafepointSynchronize::block(curJT);
2452 }
2453
2454 if (thread->is_deopt_suspend()) {
2455 thread->clear_deopt_suspend();
2456 RegisterMap map(thread, false);
2457 frame f = thread->last_frame();
2458 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2459 f = f.sender(&map);
2460 }
2461 if (f.id() == thread->must_deopt_id()) {
2462 thread->clear_must_deopt_id();
2463 f.deoptimize(thread);
2464 } else {
2465 fatal("missed deoptimization!");
2466 }
2467 }
2468 }
2469
2470 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2471 // progress or when _suspend_flags is non-zero.
2472 // Current thread needs to self-suspend if there is a suspend request and/or
2473 // block if a safepoint is in progress.
2474 // Also check for pending async exception (not including unsafe access error).
2475 // Note only the native==>VM/Java barriers can call this function and when
2476 // thread state is _thread_in_native_trans.
2477 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2478 check_safepoint_and_suspend_for_native_trans(thread);
2479
2480 if (thread->has_async_exception()) {
2481 // We are in _thread_in_native_trans state, don't handle unsafe
2482 // access error since that may block.
2483 thread->check_and_handle_async_exceptions(false);
2484 }
2485 }
2486
2487 // This is a variant of the normal
2488 // check_special_condition_for_native_trans with slightly different
2489 // semantics for use by critical native wrappers. It does all the
2490 // normal checks but also performs the transition back into
2491 // thread_in_Java state. This is required so that critical natives
2492 // can potentially block and perform a GC if they are the last thread
2493 // exiting the GCLocker.
2494 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2495 check_special_condition_for_native_trans(thread);
2496
2497 // Finish the transition
2498 thread->set_thread_state(_thread_in_Java);
2499
2500 if (thread->do_critical_native_unlock()) {
2501 ThreadInVMfromJavaNoAsyncException tiv(thread);
2502 GCLocker::unlock_critical(thread);
2503 thread->clear_critical_native_unlock();
2504 }
2505 }
2506
2507 // We need to guarantee the Threads_lock here, since resumes are not
2508 // allowed during safepoint synchronization
2509 // Can only resume from an external suspension
2510 void JavaThread::java_resume() {
2511 assert_locked_or_safepoint(Threads_lock);
2512
2513 // Sanity check: thread is gone, has started exiting or the thread
2514 // was not externally suspended.
2515 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2516 return;
2517 }
2518
2519 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2520
2521 clear_external_suspend();
2522
2523 if (is_ext_suspended()) {
2524 clear_ext_suspended();
2525 SR_lock()->notify_all();
2526 }
2527 }
2528
2529 size_t JavaThread::_stack_red_zone_size = 0;
2530 size_t JavaThread::_stack_yellow_zone_size = 0;
2531 size_t JavaThread::_stack_reserved_zone_size = 0;
2532 size_t JavaThread::_stack_shadow_zone_size = 0;
2533
2534 void JavaThread::create_stack_guard_pages() {
2535 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2536 address low_addr = stack_end();
2537 size_t len = stack_guard_zone_size();
2538
2539 int must_commit = os::must_commit_stack_guard_pages();
2540 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2541
2542 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2543 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2544 return;
2545 }
2546
2547 if (os::guard_memory((char *) low_addr, len)) {
2548 _stack_guard_state = stack_guard_enabled;
2549 } else {
2550 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2551 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2552 if (os::uncommit_memory((char *) low_addr, len)) {
2553 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2554 }
2555 return;
2556 }
2557
2558 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2559 PTR_FORMAT "-" PTR_FORMAT ".",
2560 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2561 }
2562
2563 void JavaThread::remove_stack_guard_pages() {
2564 assert(Thread::current() == this, "from different thread");
2565 if (_stack_guard_state == stack_guard_unused) return;
2566 address low_addr = stack_end();
2567 size_t len = stack_guard_zone_size();
2568
2569 if (os::must_commit_stack_guard_pages()) {
2570 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2571 _stack_guard_state = stack_guard_unused;
2572 } else {
2573 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2574 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2575 return;
2576 }
2577 } else {
2578 if (_stack_guard_state == stack_guard_unused) return;
2579 if (os::unguard_memory((char *) low_addr, len)) {
2580 _stack_guard_state = stack_guard_unused;
2581 } else {
2582 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2583 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2584 return;
2585 }
2586 }
2587
2588 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2589 PTR_FORMAT "-" PTR_FORMAT ".",
2590 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2591 }
2592
2593 void JavaThread::enable_stack_reserved_zone() {
2594 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2595 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2596
2597 // The base notation is from the stack's point of view, growing downward.
2598 // We need to adjust it to work correctly with guard_memory()
2599 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2600
2601 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2602 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2603
2604 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2605 _stack_guard_state = stack_guard_enabled;
2606 } else {
2607 warning("Attempt to guard stack reserved zone failed.");
2608 }
2609 enable_register_stack_guard();
2610 }
2611
2612 void JavaThread::disable_stack_reserved_zone() {
2613 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2614 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2615
2616 // Simply return if called for a thread that does not use guard pages.
2617 if (_stack_guard_state == stack_guard_unused) return;
2618
2619 // The base notation is from the stack's point of view, growing downward.
2620 // We need to adjust it to work correctly with guard_memory()
2621 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2622
2623 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2624 _stack_guard_state = stack_guard_reserved_disabled;
2625 } else {
2626 warning("Attempt to unguard stack reserved zone failed.");
2627 }
2628 disable_register_stack_guard();
2629 }
2630
2631 void JavaThread::enable_stack_yellow_reserved_zone() {
2632 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2633 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2634
2635 // The base notation is from the stacks point of view, growing downward.
2636 // We need to adjust it to work correctly with guard_memory()
2637 address base = stack_red_zone_base();
2638
2639 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2640 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2641
2642 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2643 _stack_guard_state = stack_guard_enabled;
2644 } else {
2645 warning("Attempt to guard stack yellow zone failed.");
2646 }
2647 enable_register_stack_guard();
2648 }
2649
2650 void JavaThread::disable_stack_yellow_reserved_zone() {
2651 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2652 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2653
2654 // Simply return if called for a thread that does not use guard pages.
2655 if (_stack_guard_state == stack_guard_unused) return;
2656
2657 // The base notation is from the stacks point of view, growing downward.
2658 // We need to adjust it to work correctly with guard_memory()
2659 address base = stack_red_zone_base();
2660
2661 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2662 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2663 } else {
2664 warning("Attempt to unguard stack yellow zone failed.");
2665 }
2666 disable_register_stack_guard();
2667 }
2668
2669 void JavaThread::enable_stack_red_zone() {
2670 // The base notation is from the stacks point of view, growing downward.
2671 // We need to adjust it to work correctly with guard_memory()
2672 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2673 address base = stack_red_zone_base() - stack_red_zone_size();
2674
2675 guarantee(base < stack_base(), "Error calculating stack red zone");
2676 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2677
2678 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2679 warning("Attempt to guard stack red zone failed.");
2680 }
2681 }
2682
2683 void JavaThread::disable_stack_red_zone() {
2684 // The base notation is from the stacks point of view, growing downward.
2685 // We need to adjust it to work correctly with guard_memory()
2686 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2687 address base = stack_red_zone_base() - stack_red_zone_size();
2688 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2689 warning("Attempt to unguard stack red zone failed.");
2690 }
2691 }
2692
2693 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2694 // ignore is there is no stack
2695 if (!has_last_Java_frame()) return;
2696 // traverse the stack frames. Starts from top frame.
2697 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2698 frame* fr = fst.current();
2699 f(fr, fst.register_map());
2700 }
2701 }
2702
2703
2704 #ifndef PRODUCT
2705 // Deoptimization
2706 // Function for testing deoptimization
2707 void JavaThread::deoptimize() {
2708 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2709 StackFrameStream fst(this, UseBiasedLocking);
2710 bool deopt = false; // Dump stack only if a deopt actually happens.
2711 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2712 // Iterate over all frames in the thread and deoptimize
2713 for (; !fst.is_done(); fst.next()) {
2714 if (fst.current()->can_be_deoptimized()) {
2715
2716 if (only_at) {
2717 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2718 // consists of comma or carriage return separated numbers so
2719 // search for the current bci in that string.
2720 address pc = fst.current()->pc();
2721 nmethod* nm = (nmethod*) fst.current()->cb();
2722 ScopeDesc* sd = nm->scope_desc_at(pc);
2723 char buffer[8];
2724 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2725 size_t len = strlen(buffer);
2726 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2727 while (found != NULL) {
2728 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2729 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2730 // Check that the bci found is bracketed by terminators.
2731 break;
2732 }
2733 found = strstr(found + 1, buffer);
2734 }
2735 if (!found) {
2736 continue;
2737 }
2738 }
2739
2740 if (DebugDeoptimization && !deopt) {
2741 deopt = true; // One-time only print before deopt
2742 tty->print_cr("[BEFORE Deoptimization]");
2743 trace_frames();
2744 trace_stack();
2745 }
2746 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2747 }
2748 }
2749
2750 if (DebugDeoptimization && deopt) {
2751 tty->print_cr("[AFTER Deoptimization]");
2752 trace_frames();
2753 }
2754 }
2755
2756
2757 // Make zombies
2758 void JavaThread::make_zombies() {
2759 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2760 if (fst.current()->can_be_deoptimized()) {
2761 // it is a Java nmethod
2762 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2763 nm->make_not_entrant();
2764 }
2765 }
2766 }
2767 #endif // PRODUCT
2768
2769
2770 void JavaThread::deoptimized_wrt_marked_nmethods() {
2771 if (!has_last_Java_frame()) return;
2772 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2773 StackFrameStream fst(this, UseBiasedLocking);
2774 for (; !fst.is_done(); fst.next()) {
2775 if (fst.current()->should_be_deoptimized()) {
2776 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2777 }
2778 }
2779 }
2780
2781
2782 // If the caller is a NamedThread, then remember, in the current scope,
2783 // the given JavaThread in its _processed_thread field.
2784 class RememberProcessedThread: public StackObj {
2785 NamedThread* _cur_thr;
2786 public:
2787 RememberProcessedThread(JavaThread* jthr) {
2788 Thread* thread = Thread::current();
2789 if (thread->is_Named_thread()) {
2790 _cur_thr = (NamedThread *)thread;
2791 _cur_thr->set_processed_thread(jthr);
2792 } else {
2793 _cur_thr = NULL;
2794 }
2795 }
2796
2797 ~RememberProcessedThread() {
2798 if (_cur_thr) {
2799 _cur_thr->set_processed_thread(NULL);
2800 }
2801 }
2802 };
2803
2804 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2805 // Verify that the deferred card marks have been flushed.
2806 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2807
2808 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2809 // since there may be more than one thread using each ThreadProfiler.
2810
2811 // Traverse the GCHandles
2812 Thread::oops_do(f, cf);
2813
2814 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2815
2816 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2817 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2818
2819 if (has_last_Java_frame()) {
2820 // Record JavaThread to GC thread
2821 RememberProcessedThread rpt(this);
2822
2823 // Traverse the privileged stack
2824 if (_privileged_stack_top != NULL) {
2825 _privileged_stack_top->oops_do(f);
2826 }
2827
2828 // traverse the registered growable array
2829 if (_array_for_gc != NULL) {
2830 for (int index = 0; index < _array_for_gc->length(); index++) {
2831 f->do_oop(_array_for_gc->adr_at(index));
2832 }
2833 }
2834
2835 // Traverse the monitor chunks
2836 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2837 chunk->oops_do(f);
2838 }
2839
2840 // Traverse the execution stack
2841 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2842 fst.current()->oops_do(f, cf, fst.register_map());
2843 }
2844 }
2845
2846 // callee_target is never live across a gc point so NULL it here should
2847 // it still contain a methdOop.
2848
2849 set_callee_target(NULL);
2850
2851 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2852 // If we have deferred set_locals there might be oops waiting to be
2853 // written
2854 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2855 if (list != NULL) {
2856 for (int i = 0; i < list->length(); i++) {
2857 list->at(i)->oops_do(f);
2858 }
2859 }
2860
2861 // Traverse instance variables at the end since the GC may be moving things
2862 // around using this function
2863 f->do_oop((oop*) &_threadObj);
2864 f->do_oop((oop*) &_vm_result);
2865 f->do_oop((oop*) &_exception_oop);
2866 f->do_oop((oop*) &_pending_async_exception);
2867
2868 if (jvmti_thread_state() != NULL) {
2869 jvmti_thread_state()->oops_do(f);
2870 }
2871 }
2872
2873 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2874 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2875 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2876
2877 if (has_last_Java_frame()) {
2878 // Traverse the execution stack
2879 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2880 fst.current()->nmethods_do(cf);
2881 }
2882 }
2883 }
2884
2885 void JavaThread::metadata_do(void f(Metadata*)) {
2886 if (has_last_Java_frame()) {
2887 // Traverse the execution stack to call f() on the methods in the stack
2888 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2889 fst.current()->metadata_do(f);
2890 }
2891 } else if (is_Compiler_thread()) {
2892 // need to walk ciMetadata in current compile tasks to keep alive.
2893 CompilerThread* ct = (CompilerThread*)this;
2894 if (ct->env() != NULL) {
2895 ct->env()->metadata_do(f);
2896 }
2897 if (ct->task() != NULL) {
2898 ct->task()->metadata_do(f);
2899 }
2900 }
2901 }
2902
2903 // Printing
2904 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2905 switch (_thread_state) {
2906 case _thread_uninitialized: return "_thread_uninitialized";
2907 case _thread_new: return "_thread_new";
2908 case _thread_new_trans: return "_thread_new_trans";
2909 case _thread_in_native: return "_thread_in_native";
2910 case _thread_in_native_trans: return "_thread_in_native_trans";
2911 case _thread_in_vm: return "_thread_in_vm";
2912 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2913 case _thread_in_Java: return "_thread_in_Java";
2914 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2915 case _thread_blocked: return "_thread_blocked";
2916 case _thread_blocked_trans: return "_thread_blocked_trans";
2917 default: return "unknown thread state";
2918 }
2919 }
2920
2921 #ifndef PRODUCT
2922 void JavaThread::print_thread_state_on(outputStream *st) const {
2923 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2924 };
2925 void JavaThread::print_thread_state() const {
2926 print_thread_state_on(tty);
2927 }
2928 #endif // PRODUCT
2929
2930 // Called by Threads::print() for VM_PrintThreads operation
2931 void JavaThread::print_on(outputStream *st) const {
2932 st->print_raw("\"");
2933 st->print_raw(get_thread_name());
2934 st->print_raw("\" ");
2935 oop thread_oop = threadObj();
2936 if (thread_oop != NULL) {
2937 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2938 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2939 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2940 }
2941 Thread::print_on(st);
2942 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2943 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2944 if (thread_oop != NULL) {
2945 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2946 }
2947 #ifndef PRODUCT
2948 print_thread_state_on(st);
2949 _safepoint_state->print_on(st);
2950 #endif // PRODUCT
2951 if (is_Compiler_thread()) {
2952 CompilerThread* ct = (CompilerThread*)this;
2953 if (ct->task() != NULL) {
2954 st->print(" Compiling: ");
2955 ct->task()->print(st, NULL, true, false);
2956 } else {
2957 st->print(" No compile task");
2958 }
2959 st->cr();
2960 }
2961 }
2962
2963 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2964 st->print("%s", get_thread_name_string(buf, buflen));
2965 }
2966
2967 // Called by fatal error handler. The difference between this and
2968 // JavaThread::print() is that we can't grab lock or allocate memory.
2969 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2970 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2971 oop thread_obj = threadObj();
2972 if (thread_obj != NULL) {
2973 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2974 }
2975 st->print(" [");
2976 st->print("%s", _get_thread_state_name(_thread_state));
2977 if (osthread()) {
2978 st->print(", id=%d", osthread()->thread_id());
2979 }
2980 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2981 p2i(stack_end()), p2i(stack_base()));
2982 st->print("]");
2983 return;
2984 }
2985
2986 // Verification
2987
2988 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2989
2990 void JavaThread::verify() {
2991 // Verify oops in the thread.
2992 oops_do(&VerifyOopClosure::verify_oop, NULL);
2993
2994 // Verify the stack frames.
2995 frames_do(frame_verify);
2996 }
2997
2998 // CR 6300358 (sub-CR 2137150)
2999 // Most callers of this method assume that it can't return NULL but a
3000 // thread may not have a name whilst it is in the process of attaching to
3001 // the VM - see CR 6412693, and there are places where a JavaThread can be
3002 // seen prior to having it's threadObj set (eg JNI attaching threads and
3003 // if vm exit occurs during initialization). These cases can all be accounted
3004 // for such that this method never returns NULL.
3005 const char* JavaThread::get_thread_name() const {
3006 #ifdef ASSERT
3007 // early safepoints can hit while current thread does not yet have TLS
3008 if (!SafepointSynchronize::is_at_safepoint()) {
3009 Thread *cur = Thread::current();
3010 if (!(cur->is_Java_thread() && cur == this)) {
3011 // Current JavaThreads are allowed to get their own name without
3012 // the Threads_lock.
3013 assert_locked_or_safepoint(Threads_lock);
3014 }
3015 }
3016 #endif // ASSERT
3017 return get_thread_name_string();
3018 }
3019
3020 // Returns a non-NULL representation of this thread's name, or a suitable
3021 // descriptive string if there is no set name
3022 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3023 const char* name_str;
3024 oop thread_obj = threadObj();
3025 if (thread_obj != NULL) {
3026 oop name = java_lang_Thread::name(thread_obj);
3027 if (name != NULL) {
3028 if (buf == NULL) {
3029 name_str = java_lang_String::as_utf8_string(name);
3030 } else {
3031 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3032 }
3033 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3034 name_str = "<no-name - thread is attaching>";
3035 } else {
3036 name_str = Thread::name();
3037 }
3038 } else {
3039 name_str = Thread::name();
3040 }
3041 assert(name_str != NULL, "unexpected NULL thread name");
3042 return name_str;
3043 }
3044
3045
3046 const char* JavaThread::get_threadgroup_name() const {
3047 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3048 oop thread_obj = threadObj();
3049 if (thread_obj != NULL) {
3050 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3051 if (thread_group != NULL) {
3052 // ThreadGroup.name can be null
3053 return java_lang_ThreadGroup::name(thread_group);
3054 }
3055 }
3056 return NULL;
3057 }
3058
3059 const char* JavaThread::get_parent_name() const {
3060 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3061 oop thread_obj = threadObj();
3062 if (thread_obj != NULL) {
3063 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3064 if (thread_group != NULL) {
3065 oop parent = java_lang_ThreadGroup::parent(thread_group);
3066 if (parent != NULL) {
3067 // ThreadGroup.name can be null
3068 return java_lang_ThreadGroup::name(parent);
3069 }
3070 }
3071 }
3072 return NULL;
3073 }
3074
3075 ThreadPriority JavaThread::java_priority() const {
3076 oop thr_oop = threadObj();
3077 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3078 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3079 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3080 return priority;
3081 }
3082
3083 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3084
3085 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3086 // Link Java Thread object <-> C++ Thread
3087
3088 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3089 // and put it into a new Handle. The Handle "thread_oop" can then
3090 // be used to pass the C++ thread object to other methods.
3091
3092 // Set the Java level thread object (jthread) field of the
3093 // new thread (a JavaThread *) to C++ thread object using the
3094 // "thread_oop" handle.
3095
3096 // Set the thread field (a JavaThread *) of the
3097 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3098
3099 Handle thread_oop(Thread::current(),
3100 JNIHandles::resolve_non_null(jni_thread));
3101 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3102 "must be initialized");
3103 set_threadObj(thread_oop());
3104 java_lang_Thread::set_thread(thread_oop(), this);
3105
3106 if (prio == NoPriority) {
3107 prio = java_lang_Thread::priority(thread_oop());
3108 assert(prio != NoPriority, "A valid priority should be present");
3109 }
3110
3111 // Push the Java priority down to the native thread; needs Threads_lock
3112 Thread::set_priority(this, prio);
3113
3114 prepare_ext();
3115
3116 // Add the new thread to the Threads list and set it in motion.
3117 // We must have threads lock in order to call Threads::add.
3118 // It is crucial that we do not block before the thread is
3119 // added to the Threads list for if a GC happens, then the java_thread oop
3120 // will not be visited by GC.
3121 Threads::add(this);
3122 }
3123
3124 oop JavaThread::current_park_blocker() {
3125 // Support for JSR-166 locks
3126 oop thread_oop = threadObj();
3127 if (thread_oop != NULL &&
3128 JDK_Version::current().supports_thread_park_blocker()) {
3129 return java_lang_Thread::park_blocker(thread_oop);
3130 }
3131 return NULL;
3132 }
3133
3134
3135 void JavaThread::print_stack_on(outputStream* st) {
3136 if (!has_last_Java_frame()) return;
3137 ResourceMark rm;
3138 HandleMark hm;
3139
3140 RegisterMap reg_map(this);
3141 vframe* start_vf = last_java_vframe(®_map);
3142 int count = 0;
3143 for (vframe* f = start_vf; f; f = f->sender()) {
3144 if (f->is_java_frame()) {
3145 javaVFrame* jvf = javaVFrame::cast(f);
3146 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3147
3148 // Print out lock information
3149 if (JavaMonitorsInStackTrace) {
3150 jvf->print_lock_info_on(st, count);
3151 }
3152 } else {
3153 // Ignore non-Java frames
3154 }
3155
3156 // Bail-out case for too deep stacks
3157 count++;
3158 if (MaxJavaStackTraceDepth == count) return;
3159 }
3160 }
3161
3162
3163 // JVMTI PopFrame support
3164 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3165 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3166 if (in_bytes(size_in_bytes) != 0) {
3167 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3168 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3169 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3170 }
3171 }
3172
3173 void* JavaThread::popframe_preserved_args() {
3174 return _popframe_preserved_args;
3175 }
3176
3177 ByteSize JavaThread::popframe_preserved_args_size() {
3178 return in_ByteSize(_popframe_preserved_args_size);
3179 }
3180
3181 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3182 int sz = in_bytes(popframe_preserved_args_size());
3183 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3184 return in_WordSize(sz / wordSize);
3185 }
3186
3187 void JavaThread::popframe_free_preserved_args() {
3188 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3189 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3190 _popframe_preserved_args = NULL;
3191 _popframe_preserved_args_size = 0;
3192 }
3193
3194 #ifndef PRODUCT
3195
3196 void JavaThread::trace_frames() {
3197 tty->print_cr("[Describe stack]");
3198 int frame_no = 1;
3199 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3200 tty->print(" %d. ", frame_no++);
3201 fst.current()->print_value_on(tty, this);
3202 tty->cr();
3203 }
3204 }
3205
3206 class PrintAndVerifyOopClosure: public OopClosure {
3207 protected:
3208 template <class T> inline void do_oop_work(T* p) {
3209 oop obj = oopDesc::load_decode_heap_oop(p);
3210 if (obj == NULL) return;
3211 tty->print(INTPTR_FORMAT ": ", p2i(p));
3212 if (obj->is_oop_or_null()) {
3213 if (obj->is_objArray()) {
3214 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3215 } else {
3216 obj->print();
3217 }
3218 } else {
3219 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3220 }
3221 tty->cr();
3222 }
3223 public:
3224 virtual void do_oop(oop* p) { do_oop_work(p); }
3225 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3226 };
3227
3228
3229 static void oops_print(frame* f, const RegisterMap *map) {
3230 PrintAndVerifyOopClosure print;
3231 f->print_value();
3232 f->oops_do(&print, NULL, (RegisterMap*)map);
3233 }
3234
3235 // Print our all the locations that contain oops and whether they are
3236 // valid or not. This useful when trying to find the oldest frame
3237 // where an oop has gone bad since the frame walk is from youngest to
3238 // oldest.
3239 void JavaThread::trace_oops() {
3240 tty->print_cr("[Trace oops]");
3241 frames_do(oops_print);
3242 }
3243
3244
3245 #ifdef ASSERT
3246 // Print or validate the layout of stack frames
3247 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3248 ResourceMark rm;
3249 PRESERVE_EXCEPTION_MARK;
3250 FrameValues values;
3251 int frame_no = 0;
3252 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3253 fst.current()->describe(values, ++frame_no);
3254 if (depth == frame_no) break;
3255 }
3256 if (validate_only) {
3257 values.validate();
3258 } else {
3259 tty->print_cr("[Describe stack layout]");
3260 values.print(this);
3261 }
3262 }
3263 #endif
3264
3265 void JavaThread::trace_stack_from(vframe* start_vf) {
3266 ResourceMark rm;
3267 int vframe_no = 1;
3268 for (vframe* f = start_vf; f; f = f->sender()) {
3269 if (f->is_java_frame()) {
3270 javaVFrame::cast(f)->print_activation(vframe_no++);
3271 } else {
3272 f->print();
3273 }
3274 if (vframe_no > StackPrintLimit) {
3275 tty->print_cr("...<more frames>...");
3276 return;
3277 }
3278 }
3279 }
3280
3281
3282 void JavaThread::trace_stack() {
3283 if (!has_last_Java_frame()) return;
3284 ResourceMark rm;
3285 HandleMark hm;
3286 RegisterMap reg_map(this);
3287 trace_stack_from(last_java_vframe(®_map));
3288 }
3289
3290
3291 #endif // PRODUCT
3292
3293
3294 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3295 assert(reg_map != NULL, "a map must be given");
3296 frame f = last_frame();
3297 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3298 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3299 }
3300 return NULL;
3301 }
3302
3303
3304 Klass* JavaThread::security_get_caller_class(int depth) {
3305 vframeStream vfst(this);
3306 vfst.security_get_caller_frame(depth);
3307 if (!vfst.at_end()) {
3308 return vfst.method()->method_holder();
3309 }
3310 return NULL;
3311 }
3312
3313 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3314 assert(thread->is_Compiler_thread(), "must be compiler thread");
3315 CompileBroker::compiler_thread_loop();
3316 }
3317
3318 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3319 NMethodSweeper::sweeper_loop();
3320 }
3321
3322 // Create a CompilerThread
3323 CompilerThread::CompilerThread(CompileQueue* queue,
3324 CompilerCounters* counters)
3325 : JavaThread(&compiler_thread_entry) {
3326 _env = NULL;
3327 _log = NULL;
3328 _task = NULL;
3329 _queue = queue;
3330 _counters = counters;
3331 _buffer_blob = NULL;
3332 _compiler = NULL;
3333
3334 #ifndef PRODUCT
3335 _ideal_graph_printer = NULL;
3336 #endif
3337 }
3338
3339 bool CompilerThread::can_call_java() const {
3340 return _compiler != NULL && _compiler->is_jvmci();
3341 }
3342
3343 // Create sweeper thread
3344 CodeCacheSweeperThread::CodeCacheSweeperThread()
3345 : JavaThread(&sweeper_thread_entry) {
3346 _scanned_compiled_method = NULL;
3347 }
3348
3349 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3350 JavaThread::oops_do(f, cf);
3351 if (_scanned_compiled_method != NULL && cf != NULL) {
3352 // Safepoints can occur when the sweeper is scanning an nmethod so
3353 // process it here to make sure it isn't unloaded in the middle of
3354 // a scan.
3355 cf->do_code_blob(_scanned_compiled_method);
3356 }
3357 }
3358
3359 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3360 JavaThread::nmethods_do(cf);
3361 if (_scanned_compiled_method != NULL && cf != NULL) {
3362 // Safepoints can occur when the sweeper is scanning an nmethod so
3363 // process it here to make sure it isn't unloaded in the middle of
3364 // a scan.
3365 cf->do_code_blob(_scanned_compiled_method);
3366 }
3367 }
3368
3369
3370 // ======= Threads ========
3371
3372 // The Threads class links together all active threads, and provides
3373 // operations over all threads. It is protected by its own Mutex
3374 // lock, which is also used in other contexts to protect thread
3375 // operations from having the thread being operated on from exiting
3376 // and going away unexpectedly (e.g., safepoint synchronization)
3377
3378 JavaThread* Threads::_thread_list = NULL;
3379 int Threads::_number_of_threads = 0;
3380 int Threads::_number_of_non_daemon_threads = 0;
3381 int Threads::_return_code = 0;
3382 int Threads::_thread_claim_parity = 0;
3383 size_t JavaThread::_stack_size_at_create = 0;
3384 #ifdef ASSERT
3385 bool Threads::_vm_complete = false;
3386 #endif
3387
3388 // All JavaThreads
3389 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3390
3391 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3392 void Threads::threads_do(ThreadClosure* tc) {
3393 assert_locked_or_safepoint(Threads_lock);
3394 // ALL_JAVA_THREADS iterates through all JavaThreads
3395 ALL_JAVA_THREADS(p) {
3396 tc->do_thread(p);
3397 }
3398 // Someday we could have a table or list of all non-JavaThreads.
3399 // For now, just manually iterate through them.
3400 tc->do_thread(VMThread::vm_thread());
3401 Universe::heap()->gc_threads_do(tc);
3402 WatcherThread *wt = WatcherThread::watcher_thread();
3403 // Strictly speaking, the following NULL check isn't sufficient to make sure
3404 // the data for WatcherThread is still valid upon being examined. However,
3405 // considering that WatchThread terminates when the VM is on the way to
3406 // exit at safepoint, the chance of the above is extremely small. The right
3407 // way to prevent termination of WatcherThread would be to acquire
3408 // Terminator_lock, but we can't do that without violating the lock rank
3409 // checking in some cases.
3410 if (wt != NULL) {
3411 tc->do_thread(wt);
3412 }
3413
3414 // If CompilerThreads ever become non-JavaThreads, add them here
3415 }
3416
3417 // The system initialization in the library has three phases.
3418 //
3419 // Phase 1: java.lang.System class initialization
3420 // java.lang.System is a primordial class loaded and initialized
3421 // by the VM early during startup. java.lang.System.<clinit>
3422 // only does registerNatives and keeps the rest of the class
3423 // initialization work later until thread initialization completes.
3424 //
3425 // System.initPhase1 initializes the system properties, the static
3426 // fields in, out, and err. Set up java signal handlers, OS-specific
3427 // system settings, and thread group of the main thread.
3428 static void call_initPhase1(TRAPS) {
3429 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3430 instanceKlassHandle klass (THREAD, k);
3431
3432 JavaValue result(T_VOID);
3433 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3434 vmSymbols::void_method_signature(), CHECK);
3435 }
3436
3437 // Phase 2. Module system initialization
3438 // This will initialize the module system. Only java.base classes
3439 // can be loaded until phase 2 completes.
3440 //
3441 // Call System.initPhase2 after the compiler initialization and jsr292
3442 // classes get initialized because module initialization runs a lot of java
3443 // code, that for performance reasons, should be compiled. Also, this will
3444 // enable the startup code to use lambda and other language features in this
3445 // phase and onward.
3446 //
3447 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3448 static void call_initPhase2(TRAPS) {
3449 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime));
3450
3451 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3452 instanceKlassHandle klass (THREAD, k);
3453
3454 JavaValue result(T_INT);
3455 JavaCallArguments args;
3456 args.push_int(DisplayVMOutputToStderr);
3457 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3458 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3459 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3460 if (result.get_jint() != JNI_OK) {
3461 vm_exit_during_initialization(); // no message or exception
3462 }
3463
3464 universe_post_module_init();
3465 }
3466
3467 // Phase 3. final setup - set security manager, system class loader and TCCL
3468 //
3469 // This will instantiate and set the security manager, set the system class
3470 // loader as well as the thread context class loader. The security manager
3471 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3472 // other modules or the application's classpath.
3473 static void call_initPhase3(TRAPS) {
3474 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3475 instanceKlassHandle klass (THREAD, k);
3476
3477 JavaValue result(T_VOID);
3478 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3479 vmSymbols::void_method_signature(), CHECK);
3480 }
3481
3482 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3483 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3484
3485 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3486 create_vm_init_libraries();
3487 }
3488
3489 initialize_class(vmSymbols::java_lang_String(), CHECK);
3490
3491 // Inject CompactStrings value after the static initializers for String ran.
3492 java_lang_String::set_compact_strings(CompactStrings);
3493
3494 // Initialize java_lang.System (needed before creating the thread)
3495 initialize_class(vmSymbols::java_lang_System(), CHECK);
3496 // The VM creates & returns objects of this class. Make sure it's initialized.
3497 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3498 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3499 Handle thread_group = create_initial_thread_group(CHECK);
3500 Universe::set_main_thread_group(thread_group());
3501 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3502 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3503 main_thread->set_threadObj(thread_object);
3504 // Set thread status to running since main thread has
3505 // been started and running.
3506 java_lang_Thread::set_thread_status(thread_object,
3507 java_lang_Thread::RUNNABLE);
3508
3509 // The VM creates objects of this class.
3510 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3511
3512 // The VM preresolves methods to these classes. Make sure that they get initialized
3513 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3514 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3515
3516 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3517 call_initPhase1(CHECK);
3518
3519 // get the Java runtime name after java.lang.System is initialized
3520 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3521 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3522
3523 // an instance of OutOfMemory exception has been allocated earlier
3524 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3525 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3526 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3527 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3528 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3529 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3530 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3531 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3532 }
3533
3534 void Threads::initialize_jsr292_core_classes(TRAPS) {
3535 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3536
3537 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3538 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3539 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3540 }
3541
3542 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3543 extern void JDK_Version_init();
3544
3545 // Preinitialize version info.
3546 VM_Version::early_initialize();
3547
3548 // Check version
3549 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3550
3551 // Initialize library-based TLS
3552 ThreadLocalStorage::init();
3553
3554 // Initialize the output stream module
3555 ostream_init();
3556
3557 // Process java launcher properties.
3558 Arguments::process_sun_java_launcher_properties(args);
3559
3560 // Initialize the os module
3561 os::init();
3562
3563 // Record VM creation timing statistics
3564 TraceVmCreationTime create_vm_timer;
3565 create_vm_timer.start();
3566
3567 // Initialize system properties.
3568 Arguments::init_system_properties();
3569
3570 // So that JDK version can be used as a discriminator when parsing arguments
3571 JDK_Version_init();
3572
3573 // Update/Initialize System properties after JDK version number is known
3574 Arguments::init_version_specific_system_properties();
3575
3576 // Make sure to initialize log configuration *before* parsing arguments
3577 LogConfiguration::initialize(create_vm_timer.begin_time());
3578
3579 // Parse arguments
3580 jint parse_result = Arguments::parse(args);
3581 if (parse_result != JNI_OK) return parse_result;
3582
3583 os::init_before_ergo();
3584
3585 jint ergo_result = Arguments::apply_ergo();
3586 if (ergo_result != JNI_OK) return ergo_result;
3587
3588 // Final check of all ranges after ergonomics which may change values.
3589 if (!CommandLineFlagRangeList::check_ranges()) {
3590 return JNI_EINVAL;
3591 }
3592
3593 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3594 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3595 if (!constraint_result) {
3596 return JNI_EINVAL;
3597 }
3598
3599 CommandLineFlagWriteableList::mark_startup();
3600
3601 if (PauseAtStartup) {
3602 os::pause();
3603 }
3604
3605 HOTSPOT_VM_INIT_BEGIN();
3606
3607 // Timing (must come after argument parsing)
3608 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3609
3610 // Initialize the os module after parsing the args
3611 jint os_init_2_result = os::init_2();
3612 if (os_init_2_result != JNI_OK) return os_init_2_result;
3613
3614 jint adjust_after_os_result = Arguments::adjust_after_os();
3615 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3616
3617 // Initialize output stream logging
3618 ostream_init_log();
3619
3620 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3621 // Must be before create_vm_init_agents()
3622 if (Arguments::init_libraries_at_startup()) {
3623 convert_vm_init_libraries_to_agents();
3624 }
3625
3626 // Launch -agentlib/-agentpath and converted -Xrun agents
3627 if (Arguments::init_agents_at_startup()) {
3628 create_vm_init_agents();
3629 }
3630
3631 // Initialize Threads state
3632 _thread_list = NULL;
3633 _number_of_threads = 0;
3634 _number_of_non_daemon_threads = 0;
3635
3636 // Initialize global data structures and create system classes in heap
3637 vm_init_globals();
3638
3639 #if INCLUDE_JVMCI
3640 if (JVMCICounterSize > 0) {
3641 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3642 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3643 } else {
3644 JavaThread::_jvmci_old_thread_counters = NULL;
3645 }
3646 #endif // INCLUDE_JVMCI
3647
3648 // Attach the main thread to this os thread
3649 JavaThread* main_thread = new JavaThread();
3650 main_thread->set_thread_state(_thread_in_vm);
3651 main_thread->initialize_thread_current();
3652 // must do this before set_active_handles
3653 main_thread->record_stack_base_and_size();
3654 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3655
3656 if (!main_thread->set_as_starting_thread()) {
3657 vm_shutdown_during_initialization(
3658 "Failed necessary internal allocation. Out of swap space");
3659 delete main_thread;
3660 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3661 return JNI_ENOMEM;
3662 }
3663
3664 // Enable guard page *after* os::create_main_thread(), otherwise it would
3665 // crash Linux VM, see notes in os_linux.cpp.
3666 main_thread->create_stack_guard_pages();
3667
3668 // Initialize Java-Level synchronization subsystem
3669 ObjectMonitor::Initialize();
3670
3671 // Initialize global modules
3672 jint status = init_globals();
3673 if (status != JNI_OK) {
3674 delete main_thread;
3675 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3676 return status;
3677 }
3678
3679 if (TRACE_INITIALIZE() != JNI_OK) {
3680 vm_exit_during_initialization("Failed to initialize tracing backend");
3681 }
3682
3683 // Should be done after the heap is fully created
3684 main_thread->cache_global_variables();
3685
3686 HandleMark hm;
3687
3688 { MutexLocker mu(Threads_lock);
3689 Threads::add(main_thread);
3690 }
3691
3692 // Any JVMTI raw monitors entered in onload will transition into
3693 // real raw monitor. VM is setup enough here for raw monitor enter.
3694 JvmtiExport::transition_pending_onload_raw_monitors();
3695
3696 // Create the VMThread
3697 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3698
3699 VMThread::create();
3700 Thread* vmthread = VMThread::vm_thread();
3701
3702 if (!os::create_thread(vmthread, os::vm_thread)) {
3703 vm_exit_during_initialization("Cannot create VM thread. "
3704 "Out of system resources.");
3705 }
3706
3707 // Wait for the VM thread to become ready, and VMThread::run to initialize
3708 // Monitors can have spurious returns, must always check another state flag
3709 {
3710 MutexLocker ml(Notify_lock);
3711 os::start_thread(vmthread);
3712 while (vmthread->active_handles() == NULL) {
3713 Notify_lock->wait();
3714 }
3715 }
3716 }
3717
3718 assert(Universe::is_fully_initialized(), "not initialized");
3719 if (VerifyDuringStartup) {
3720 // Make sure we're starting with a clean slate.
3721 VM_Verify verify_op;
3722 VMThread::execute(&verify_op);
3723 }
3724
3725 Thread* THREAD = Thread::current();
3726
3727 // At this point, the Universe is initialized, but we have not executed
3728 // any byte code. Now is a good time (the only time) to dump out the
3729 // internal state of the JVM for sharing.
3730 if (DumpSharedSpaces) {
3731 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3732 ShouldNotReachHere();
3733 }
3734
3735 // Always call even when there are not JVMTI environments yet, since environments
3736 // may be attached late and JVMTI must track phases of VM execution
3737 JvmtiExport::enter_early_start_phase();
3738
3739 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3740 JvmtiExport::post_early_vm_start();
3741
3742 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3743
3744 // We need this for ClassDataSharing - the initial vm.info property is set
3745 // with the default value of CDS "sharing" which may be reset through
3746 // command line options.
3747 reset_vm_info_property(CHECK_JNI_ERR);
3748
3749 quicken_jni_functions();
3750
3751 // No more stub generation allowed after that point.
3752 StubCodeDesc::freeze();
3753
3754 // Set flag that basic initialization has completed. Used by exceptions and various
3755 // debug stuff, that does not work until all basic classes have been initialized.
3756 set_init_completed();
3757
3758 LogConfiguration::post_initialize();
3759 Metaspace::post_initialize();
3760
3761 HOTSPOT_VM_INIT_END();
3762
3763 // record VM initialization completion time
3764 #if INCLUDE_MANAGEMENT
3765 Management::record_vm_init_completed();
3766 #endif // INCLUDE_MANAGEMENT
3767
3768 // Signal Dispatcher needs to be started before VMInit event is posted
3769 os::signal_init();
3770
3771 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3772 if (!DisableAttachMechanism) {
3773 AttachListener::vm_start();
3774 if (StartAttachListener || AttachListener::init_at_startup()) {
3775 AttachListener::init();
3776 }
3777 }
3778
3779 // Launch -Xrun agents
3780 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3781 // back-end can launch with -Xdebug -Xrunjdwp.
3782 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3783 create_vm_init_libraries();
3784 }
3785
3786 if (CleanChunkPoolAsync) {
3787 Chunk::start_chunk_pool_cleaner_task();
3788 }
3789
3790 // initialize compiler(s)
3791 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3792 CompileBroker::compilation_init(CHECK_JNI_ERR);
3793 #endif
3794
3795 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3796 // It is done after compilers are initialized, because otherwise compilations of
3797 // signature polymorphic MH intrinsics can be missed
3798 // (see SystemDictionary::find_method_handle_intrinsic).
3799 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3800
3801 // This will initialize the module system. Only java.base classes can be
3802 // loaded until phase 2 completes
3803 call_initPhase2(CHECK_JNI_ERR);
3804
3805 // Always call even when there are not JVMTI environments yet, since environments
3806 // may be attached late and JVMTI must track phases of VM execution
3807 JvmtiExport::enter_start_phase();
3808
3809 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3810 JvmtiExport::post_vm_start();
3811
3812 // Final system initialization including security manager and system class loader
3813 call_initPhase3(CHECK_JNI_ERR);
3814
3815 // cache the system class loader
3816 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3817
3818 #if INCLUDE_JVMCI
3819 if (EnableJVMCI) {
3820 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3821 // The JVMCI Java initialization code will read this flag and
3822 // do the printing if it's set.
3823 bool init = JVMCIPrintProperties;
3824
3825 if (!init) {
3826 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3827 // compilations via JVMCI will not actually block until JVMCI is initialized.
3828 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3829 }
3830
3831 if (init) {
3832 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3833 }
3834 }
3835 #endif
3836
3837 // Always call even when there are not JVMTI environments yet, since environments
3838 // may be attached late and JVMTI must track phases of VM execution
3839 JvmtiExport::enter_live_phase();
3840
3841 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3842 JvmtiExport::post_vm_initialized();
3843
3844 if (TRACE_START() != JNI_OK) {
3845 vm_exit_during_initialization("Failed to start tracing backend.");
3846 }
3847
3848 #if INCLUDE_MANAGEMENT
3849 Management::initialize(THREAD);
3850
3851 if (HAS_PENDING_EXCEPTION) {
3852 // management agent fails to start possibly due to
3853 // configuration problem and is responsible for printing
3854 // stack trace if appropriate. Simply exit VM.
3855 vm_exit(1);
3856 }
3857 #endif // INCLUDE_MANAGEMENT
3858
3859 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3860 if (MemProfiling) MemProfiler::engage();
3861 StatSampler::engage();
3862 if (CheckJNICalls) JniPeriodicChecker::engage();
3863
3864 BiasedLocking::init();
3865
3866 #if INCLUDE_RTM_OPT
3867 RTMLockingCounters::init();
3868 #endif
3869
3870 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3871 call_postVMInitHook(THREAD);
3872 // The Java side of PostVMInitHook.run must deal with all
3873 // exceptions and provide means of diagnosis.
3874 if (HAS_PENDING_EXCEPTION) {
3875 CLEAR_PENDING_EXCEPTION;
3876 }
3877 }
3878
3879 {
3880 MutexLocker ml(PeriodicTask_lock);
3881 // Make sure the WatcherThread can be started by WatcherThread::start()
3882 // or by dynamic enrollment.
3883 WatcherThread::make_startable();
3884 // Start up the WatcherThread if there are any periodic tasks
3885 // NOTE: All PeriodicTasks should be registered by now. If they
3886 // aren't, late joiners might appear to start slowly (we might
3887 // take a while to process their first tick).
3888 if (PeriodicTask::num_tasks() > 0) {
3889 WatcherThread::start();
3890 }
3891 }
3892
3893 create_vm_timer.end();
3894 #ifdef ASSERT
3895 _vm_complete = true;
3896 #endif
3897 return JNI_OK;
3898 }
3899
3900 // type for the Agent_OnLoad and JVM_OnLoad entry points
3901 extern "C" {
3902 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3903 }
3904 // Find a command line agent library and return its entry point for
3905 // -agentlib: -agentpath: -Xrun
3906 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3907 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3908 const char *on_load_symbols[],
3909 size_t num_symbol_entries) {
3910 OnLoadEntry_t on_load_entry = NULL;
3911 void *library = NULL;
3912
3913 if (!agent->valid()) {
3914 char buffer[JVM_MAXPATHLEN];
3915 char ebuf[1024] = "";
3916 const char *name = agent->name();
3917 const char *msg = "Could not find agent library ";
3918
3919 // First check to see if agent is statically linked into executable
3920 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3921 library = agent->os_lib();
3922 } else if (agent->is_absolute_path()) {
3923 library = os::dll_load(name, ebuf, sizeof ebuf);
3924 if (library == NULL) {
3925 const char *sub_msg = " in absolute path, with error: ";
3926 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3927 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3928 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3929 // If we can't find the agent, exit.
3930 vm_exit_during_initialization(buf, NULL);
3931 FREE_C_HEAP_ARRAY(char, buf);
3932 }
3933 } else {
3934 // Try to load the agent from the standard dll directory
3935 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3936 name)) {
3937 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3938 }
3939 if (library == NULL) { // Try the local directory
3940 char ns[1] = {0};
3941 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3942 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3943 }
3944 if (library == NULL) {
3945 const char *sub_msg = " on the library path, with error: ";
3946 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3947 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3948 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3949 // If we can't find the agent, exit.
3950 vm_exit_during_initialization(buf, NULL);
3951 FREE_C_HEAP_ARRAY(char, buf);
3952 }
3953 }
3954 }
3955 agent->set_os_lib(library);
3956 agent->set_valid();
3957 }
3958
3959 // Find the OnLoad function.
3960 on_load_entry =
3961 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3962 false,
3963 on_load_symbols,
3964 num_symbol_entries));
3965 return on_load_entry;
3966 }
3967
3968 // Find the JVM_OnLoad entry point
3969 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3970 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3971 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3972 }
3973
3974 // Find the Agent_OnLoad entry point
3975 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3976 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3977 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3978 }
3979
3980 // For backwards compatibility with -Xrun
3981 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3982 // treated like -agentpath:
3983 // Must be called before agent libraries are created
3984 void Threads::convert_vm_init_libraries_to_agents() {
3985 AgentLibrary* agent;
3986 AgentLibrary* next;
3987
3988 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3989 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3990 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3991
3992 // If there is an JVM_OnLoad function it will get called later,
3993 // otherwise see if there is an Agent_OnLoad
3994 if (on_load_entry == NULL) {
3995 on_load_entry = lookup_agent_on_load(agent);
3996 if (on_load_entry != NULL) {
3997 // switch it to the agent list -- so that Agent_OnLoad will be called,
3998 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3999 Arguments::convert_library_to_agent(agent);
4000 } else {
4001 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4002 }
4003 }
4004 }
4005 }
4006
4007 // Create agents for -agentlib: -agentpath: and converted -Xrun
4008 // Invokes Agent_OnLoad
4009 // Called very early -- before JavaThreads exist
4010 void Threads::create_vm_init_agents() {
4011 extern struct JavaVM_ main_vm;
4012 AgentLibrary* agent;
4013
4014 JvmtiExport::enter_onload_phase();
4015
4016 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4017 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4018
4019 if (on_load_entry != NULL) {
4020 // Invoke the Agent_OnLoad function
4021 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4022 if (err != JNI_OK) {
4023 vm_exit_during_initialization("agent library failed to init", agent->name());
4024 }
4025 } else {
4026 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4027 }
4028 }
4029 JvmtiExport::enter_primordial_phase();
4030 }
4031
4032 extern "C" {
4033 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4034 }
4035
4036 void Threads::shutdown_vm_agents() {
4037 // Send any Agent_OnUnload notifications
4038 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4039 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4040 extern struct JavaVM_ main_vm;
4041 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4042
4043 // Find the Agent_OnUnload function.
4044 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4045 os::find_agent_function(agent,
4046 false,
4047 on_unload_symbols,
4048 num_symbol_entries));
4049
4050 // Invoke the Agent_OnUnload function
4051 if (unload_entry != NULL) {
4052 JavaThread* thread = JavaThread::current();
4053 ThreadToNativeFromVM ttn(thread);
4054 HandleMark hm(thread);
4055 (*unload_entry)(&main_vm);
4056 }
4057 }
4058 }
4059
4060 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4061 // Invokes JVM_OnLoad
4062 void Threads::create_vm_init_libraries() {
4063 extern struct JavaVM_ main_vm;
4064 AgentLibrary* agent;
4065
4066 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4067 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4068
4069 if (on_load_entry != NULL) {
4070 // Invoke the JVM_OnLoad function
4071 JavaThread* thread = JavaThread::current();
4072 ThreadToNativeFromVM ttn(thread);
4073 HandleMark hm(thread);
4074 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4075 if (err != JNI_OK) {
4076 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4077 }
4078 } else {
4079 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4080 }
4081 }
4082 }
4083
4084 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4085 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4086
4087 JavaThread* java_thread = NULL;
4088 // Sequential search for now. Need to do better optimization later.
4089 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4090 oop tobj = thread->threadObj();
4091 if (!thread->is_exiting() &&
4092 tobj != NULL &&
4093 java_tid == java_lang_Thread::thread_id(tobj)) {
4094 java_thread = thread;
4095 break;
4096 }
4097 }
4098 return java_thread;
4099 }
4100
4101
4102 // Last thread running calls java.lang.Shutdown.shutdown()
4103 void JavaThread::invoke_shutdown_hooks() {
4104 HandleMark hm(this);
4105
4106 // We could get here with a pending exception, if so clear it now.
4107 if (this->has_pending_exception()) {
4108 this->clear_pending_exception();
4109 }
4110
4111 EXCEPTION_MARK;
4112 Klass* k =
4113 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4114 THREAD);
4115 if (k != NULL) {
4116 // SystemDictionary::resolve_or_null will return null if there was
4117 // an exception. If we cannot load the Shutdown class, just don't
4118 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4119 // and finalizers (if runFinalizersOnExit is set) won't be run.
4120 // Note that if a shutdown hook was registered or runFinalizersOnExit
4121 // was called, the Shutdown class would have already been loaded
4122 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4123 instanceKlassHandle shutdown_klass (THREAD, k);
4124 JavaValue result(T_VOID);
4125 JavaCalls::call_static(&result,
4126 shutdown_klass,
4127 vmSymbols::shutdown_method_name(),
4128 vmSymbols::void_method_signature(),
4129 THREAD);
4130 }
4131 CLEAR_PENDING_EXCEPTION;
4132 }
4133
4134 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4135 // the program falls off the end of main(). Another VM exit path is through
4136 // vm_exit() when the program calls System.exit() to return a value or when
4137 // there is a serious error in VM. The two shutdown paths are not exactly
4138 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4139 // and VM_Exit op at VM level.
4140 //
4141 // Shutdown sequence:
4142 // + Shutdown native memory tracking if it is on
4143 // + Wait until we are the last non-daemon thread to execute
4144 // <-- every thing is still working at this moment -->
4145 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4146 // shutdown hooks, run finalizers if finalization-on-exit
4147 // + Call before_exit(), prepare for VM exit
4148 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4149 // currently the only user of this mechanism is File.deleteOnExit())
4150 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4151 // post thread end and vm death events to JVMTI,
4152 // stop signal thread
4153 // + Call JavaThread::exit(), it will:
4154 // > release JNI handle blocks, remove stack guard pages
4155 // > remove this thread from Threads list
4156 // <-- no more Java code from this thread after this point -->
4157 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4158 // the compiler threads at safepoint
4159 // <-- do not use anything that could get blocked by Safepoint -->
4160 // + Disable tracing at JNI/JVM barriers
4161 // + Set _vm_exited flag for threads that are still running native code
4162 // + Delete this thread
4163 // + Call exit_globals()
4164 // > deletes tty
4165 // > deletes PerfMemory resources
4166 // + Return to caller
4167
4168 bool Threads::destroy_vm() {
4169 JavaThread* thread = JavaThread::current();
4170
4171 #ifdef ASSERT
4172 _vm_complete = false;
4173 #endif
4174 // Wait until we are the last non-daemon thread to execute
4175 { MutexLocker nu(Threads_lock);
4176 while (Threads::number_of_non_daemon_threads() > 1)
4177 // This wait should make safepoint checks, wait without a timeout,
4178 // and wait as a suspend-equivalent condition.
4179 //
4180 // Note: If the FlatProfiler is running and this thread is waiting
4181 // for another non-daemon thread to finish, then the FlatProfiler
4182 // is waiting for the external suspend request on this thread to
4183 // complete. wait_for_ext_suspend_completion() will eventually
4184 // timeout, but that takes time. Making this wait a suspend-
4185 // equivalent condition solves that timeout problem.
4186 //
4187 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4188 Mutex::_as_suspend_equivalent_flag);
4189 }
4190
4191 // Hang forever on exit if we are reporting an error.
4192 if (ShowMessageBoxOnError && is_error_reported()) {
4193 os::infinite_sleep();
4194 }
4195 os::wait_for_keypress_at_exit();
4196
4197 // run Java level shutdown hooks
4198 thread->invoke_shutdown_hooks();
4199
4200 before_exit(thread);
4201
4202 thread->exit(true);
4203
4204 // Stop VM thread.
4205 {
4206 // 4945125 The vm thread comes to a safepoint during exit.
4207 // GC vm_operations can get caught at the safepoint, and the
4208 // heap is unparseable if they are caught. Grab the Heap_lock
4209 // to prevent this. The GC vm_operations will not be able to
4210 // queue until after the vm thread is dead. After this point,
4211 // we'll never emerge out of the safepoint before the VM exits.
4212
4213 MutexLocker ml(Heap_lock);
4214
4215 VMThread::wait_for_vm_thread_exit();
4216 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4217 VMThread::destroy();
4218 }
4219
4220 // clean up ideal graph printers
4221 #if defined(COMPILER2) && !defined(PRODUCT)
4222 IdealGraphPrinter::clean_up();
4223 #endif
4224
4225 // Now, all Java threads are gone except daemon threads. Daemon threads
4226 // running Java code or in VM are stopped by the Safepoint. However,
4227 // daemon threads executing native code are still running. But they
4228 // will be stopped at native=>Java/VM barriers. Note that we can't
4229 // simply kill or suspend them, as it is inherently deadlock-prone.
4230
4231 VM_Exit::set_vm_exited();
4232
4233 notify_vm_shutdown();
4234
4235 delete thread;
4236
4237 #if INCLUDE_JVMCI
4238 if (JVMCICounterSize > 0) {
4239 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4240 }
4241 #endif
4242
4243 // exit_globals() will delete tty
4244 exit_globals();
4245
4246 LogConfiguration::finalize();
4247
4248 return true;
4249 }
4250
4251
4252 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4253 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4254 return is_supported_jni_version(version);
4255 }
4256
4257
4258 jboolean Threads::is_supported_jni_version(jint version) {
4259 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4260 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4261 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4262 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4263 if (version == JNI_VERSION_9) return JNI_TRUE;
4264 return JNI_FALSE;
4265 }
4266
4267
4268 void Threads::add(JavaThread* p, bool force_daemon) {
4269 // The threads lock must be owned at this point
4270 assert_locked_or_safepoint(Threads_lock);
4271
4272 // See the comment for this method in thread.hpp for its purpose and
4273 // why it is called here.
4274 p->initialize_queues();
4275 p->set_next(_thread_list);
4276 _thread_list = p;
4277 _number_of_threads++;
4278 oop threadObj = p->threadObj();
4279 bool daemon = true;
4280 // Bootstrapping problem: threadObj can be null for initial
4281 // JavaThread (or for threads attached via JNI)
4282 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4283 _number_of_non_daemon_threads++;
4284 daemon = false;
4285 }
4286
4287 ThreadService::add_thread(p, daemon);
4288
4289 // Possible GC point.
4290 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4291 }
4292
4293 void Threads::remove(JavaThread* p) {
4294 // Extra scope needed for Thread_lock, so we can check
4295 // that we do not remove thread without safepoint code notice
4296 { MutexLocker ml(Threads_lock);
4297
4298 assert(includes(p), "p must be present");
4299
4300 JavaThread* current = _thread_list;
4301 JavaThread* prev = NULL;
4302
4303 while (current != p) {
4304 prev = current;
4305 current = current->next();
4306 }
4307
4308 if (prev) {
4309 prev->set_next(current->next());
4310 } else {
4311 _thread_list = p->next();
4312 }
4313 _number_of_threads--;
4314 oop threadObj = p->threadObj();
4315 bool daemon = true;
4316 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4317 _number_of_non_daemon_threads--;
4318 daemon = false;
4319
4320 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4321 // on destroy_vm will wake up.
4322 if (number_of_non_daemon_threads() == 1) {
4323 Threads_lock->notify_all();
4324 }
4325 }
4326 ThreadService::remove_thread(p, daemon);
4327
4328 // Make sure that safepoint code disregard this thread. This is needed since
4329 // the thread might mess around with locks after this point. This can cause it
4330 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4331 // of this thread since it is removed from the queue.
4332 p->set_terminated_value();
4333 } // unlock Threads_lock
4334
4335 // Since Events::log uses a lock, we grab it outside the Threads_lock
4336 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4337 }
4338
4339 // Threads_lock must be held when this is called (or must be called during a safepoint)
4340 bool Threads::includes(JavaThread* p) {
4341 assert(Threads_lock->is_locked(), "sanity check");
4342 ALL_JAVA_THREADS(q) {
4343 if (q == p) {
4344 return true;
4345 }
4346 }
4347 return false;
4348 }
4349
4350 // Operations on the Threads list for GC. These are not explicitly locked,
4351 // but the garbage collector must provide a safe context for them to run.
4352 // In particular, these things should never be called when the Threads_lock
4353 // is held by some other thread. (Note: the Safepoint abstraction also
4354 // uses the Threads_lock to guarantee this property. It also makes sure that
4355 // all threads gets blocked when exiting or starting).
4356
4357 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4358 ALL_JAVA_THREADS(p) {
4359 p->oops_do(f, cf);
4360 }
4361 VMThread::vm_thread()->oops_do(f, cf);
4362 }
4363
4364 void Threads::change_thread_claim_parity() {
4365 // Set the new claim parity.
4366 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4367 "Not in range.");
4368 _thread_claim_parity++;
4369 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4370 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4371 "Not in range.");
4372 }
4373
4374 #ifdef ASSERT
4375 void Threads::assert_all_threads_claimed() {
4376 ALL_JAVA_THREADS(p) {
4377 const int thread_parity = p->oops_do_parity();
4378 assert((thread_parity == _thread_claim_parity),
4379 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4380 }
4381 }
4382 #endif // ASSERT
4383
4384 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4385 int cp = Threads::thread_claim_parity();
4386 ALL_JAVA_THREADS(p) {
4387 if (p->claim_oops_do(is_par, cp)) {
4388 p->oops_do(f, cf);
4389 }
4390 }
4391 VMThread* vmt = VMThread::vm_thread();
4392 if (vmt->claim_oops_do(is_par, cp)) {
4393 vmt->oops_do(f, cf);
4394 }
4395 }
4396
4397 #if INCLUDE_ALL_GCS
4398 // Used by ParallelScavenge
4399 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4400 ALL_JAVA_THREADS(p) {
4401 q->enqueue(new ThreadRootsTask(p));
4402 }
4403 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4404 }
4405
4406 // Used by Parallel Old
4407 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4408 ALL_JAVA_THREADS(p) {
4409 q->enqueue(new ThreadRootsMarkingTask(p));
4410 }
4411 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4412 }
4413 #endif // INCLUDE_ALL_GCS
4414
4415 void Threads::nmethods_do(CodeBlobClosure* cf) {
4416 ALL_JAVA_THREADS(p) {
4417 // This is used by the code cache sweeper to mark nmethods that are active
4418 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4419 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4420 if(!p->is_Code_cache_sweeper_thread()) {
4421 p->nmethods_do(cf);
4422 }
4423 }
4424 }
4425
4426 void Threads::metadata_do(void f(Metadata*)) {
4427 ALL_JAVA_THREADS(p) {
4428 p->metadata_do(f);
4429 }
4430 }
4431
4432 class ThreadHandlesClosure : public ThreadClosure {
4433 void (*_f)(Metadata*);
4434 public:
4435 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4436 virtual void do_thread(Thread* thread) {
4437 thread->metadata_handles_do(_f);
4438 }
4439 };
4440
4441 void Threads::metadata_handles_do(void f(Metadata*)) {
4442 // Only walk the Handles in Thread.
4443 ThreadHandlesClosure handles_closure(f);
4444 threads_do(&handles_closure);
4445 }
4446
4447 void Threads::deoptimized_wrt_marked_nmethods() {
4448 ALL_JAVA_THREADS(p) {
4449 p->deoptimized_wrt_marked_nmethods();
4450 }
4451 }
4452
4453
4454 // Get count Java threads that are waiting to enter the specified monitor.
4455 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4456 address monitor,
4457 bool doLock) {
4458 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4459 "must grab Threads_lock or be at safepoint");
4460 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4461
4462 int i = 0;
4463 {
4464 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4465 ALL_JAVA_THREADS(p) {
4466 if (!p->can_call_java()) continue;
4467
4468 address pending = (address)p->current_pending_monitor();
4469 if (pending == monitor) { // found a match
4470 if (i < count) result->append(p); // save the first count matches
4471 i++;
4472 }
4473 }
4474 }
4475 return result;
4476 }
4477
4478
4479 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4480 bool doLock) {
4481 assert(doLock ||
4482 Threads_lock->owned_by_self() ||
4483 SafepointSynchronize::is_at_safepoint(),
4484 "must grab Threads_lock or be at safepoint");
4485
4486 // NULL owner means not locked so we can skip the search
4487 if (owner == NULL) return NULL;
4488
4489 {
4490 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4491 ALL_JAVA_THREADS(p) {
4492 // first, see if owner is the address of a Java thread
4493 if (owner == (address)p) return p;
4494 }
4495 }
4496 // Cannot assert on lack of success here since this function may be
4497 // used by code that is trying to report useful problem information
4498 // like deadlock detection.
4499 if (UseHeavyMonitors) return NULL;
4500
4501 // If we didn't find a matching Java thread and we didn't force use of
4502 // heavyweight monitors, then the owner is the stack address of the
4503 // Lock Word in the owning Java thread's stack.
4504 //
4505 JavaThread* the_owner = NULL;
4506 {
4507 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4508 ALL_JAVA_THREADS(q) {
4509 if (q->is_lock_owned(owner)) {
4510 the_owner = q;
4511 break;
4512 }
4513 }
4514 }
4515 // cannot assert on lack of success here; see above comment
4516 return the_owner;
4517 }
4518
4519 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4520 void Threads::print_on(outputStream* st, bool print_stacks,
4521 bool internal_format, bool print_concurrent_locks) {
4522 char buf[32];
4523 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4524
4525 st->print_cr("Full thread dump %s (%s %s):",
4526 Abstract_VM_Version::vm_name(),
4527 Abstract_VM_Version::vm_release(),
4528 Abstract_VM_Version::vm_info_string());
4529 st->cr();
4530
4531 #if INCLUDE_SERVICES
4532 // Dump concurrent locks
4533 ConcurrentLocksDump concurrent_locks;
4534 if (print_concurrent_locks) {
4535 concurrent_locks.dump_at_safepoint();
4536 }
4537 #endif // INCLUDE_SERVICES
4538
4539 ALL_JAVA_THREADS(p) {
4540 ResourceMark rm;
4541 p->print_on(st);
4542 if (print_stacks) {
4543 if (internal_format) {
4544 p->trace_stack();
4545 } else {
4546 p->print_stack_on(st);
4547 }
4548 }
4549 st->cr();
4550 #if INCLUDE_SERVICES
4551 if (print_concurrent_locks) {
4552 concurrent_locks.print_locks_on(p, st);
4553 }
4554 #endif // INCLUDE_SERVICES
4555 }
4556
4557 VMThread::vm_thread()->print_on(st);
4558 st->cr();
4559 Universe::heap()->print_gc_threads_on(st);
4560 WatcherThread* wt = WatcherThread::watcher_thread();
4561 if (wt != NULL) {
4562 wt->print_on(st);
4563 st->cr();
4564 }
4565 st->flush();
4566 }
4567
4568 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4569 int buflen, bool* found_current) {
4570 if (this_thread != NULL) {
4571 bool is_current = (current == this_thread);
4572 *found_current = *found_current || is_current;
4573 st->print("%s", is_current ? "=>" : " ");
4574
4575 st->print(PTR_FORMAT, p2i(this_thread));
4576 st->print(" ");
4577 this_thread->print_on_error(st, buf, buflen);
4578 st->cr();
4579 }
4580 }
4581
4582 class PrintOnErrorClosure : public ThreadClosure {
4583 outputStream* _st;
4584 Thread* _current;
4585 char* _buf;
4586 int _buflen;
4587 bool* _found_current;
4588 public:
4589 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4590 int buflen, bool* found_current) :
4591 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4592
4593 virtual void do_thread(Thread* thread) {
4594 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4595 }
4596 };
4597
4598 // Threads::print_on_error() is called by fatal error handler. It's possible
4599 // that VM is not at safepoint and/or current thread is inside signal handler.
4600 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4601 // memory (even in resource area), it might deadlock the error handler.
4602 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4603 int buflen) {
4604 bool found_current = false;
4605 st->print_cr("Java Threads: ( => current thread )");
4606 ALL_JAVA_THREADS(thread) {
4607 print_on_error(thread, st, current, buf, buflen, &found_current);
4608 }
4609 st->cr();
4610
4611 st->print_cr("Other Threads:");
4612 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4613 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4614
4615 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4616 Universe::heap()->gc_threads_do(&print_closure);
4617
4618 if (!found_current) {
4619 st->cr();
4620 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4621 current->print_on_error(st, buf, buflen);
4622 st->cr();
4623 }
4624 st->cr();
4625 st->print_cr("Threads with active compile tasks:");
4626 print_threads_compiling(st, buf, buflen);
4627 }
4628
4629 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4630 ALL_JAVA_THREADS(thread) {
4631 if (thread->is_Compiler_thread()) {
4632 CompilerThread* ct = (CompilerThread*) thread;
4633 if (ct->task() != NULL) {
4634 thread->print_name_on_error(st, buf, buflen);
4635 ct->task()->print(st, NULL, true, true);
4636 }
4637 }
4638 }
4639 }
4640
4641
4642 // Internal SpinLock and Mutex
4643 // Based on ParkEvent
4644
4645 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4646 //
4647 // We employ SpinLocks _only for low-contention, fixed-length
4648 // short-duration critical sections where we're concerned
4649 // about native mutex_t or HotSpot Mutex:: latency.
4650 // The mux construct provides a spin-then-block mutual exclusion
4651 // mechanism.
4652 //
4653 // Testing has shown that contention on the ListLock guarding gFreeList
4654 // is common. If we implement ListLock as a simple SpinLock it's common
4655 // for the JVM to devolve to yielding with little progress. This is true
4656 // despite the fact that the critical sections protected by ListLock are
4657 // extremely short.
4658 //
4659 // TODO-FIXME: ListLock should be of type SpinLock.
4660 // We should make this a 1st-class type, integrated into the lock
4661 // hierarchy as leaf-locks. Critically, the SpinLock structure
4662 // should have sufficient padding to avoid false-sharing and excessive
4663 // cache-coherency traffic.
4664
4665
4666 typedef volatile int SpinLockT;
4667
4668 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4669 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4670 return; // normal fast-path return
4671 }
4672
4673 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4674 TEVENT(SpinAcquire - ctx);
4675 int ctr = 0;
4676 int Yields = 0;
4677 for (;;) {
4678 while (*adr != 0) {
4679 ++ctr;
4680 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4681 if (Yields > 5) {
4682 os::naked_short_sleep(1);
4683 } else {
4684 os::naked_yield();
4685 ++Yields;
4686 }
4687 } else {
4688 SpinPause();
4689 }
4690 }
4691 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4692 }
4693 }
4694
4695 void Thread::SpinRelease(volatile int * adr) {
4696 assert(*adr != 0, "invariant");
4697 OrderAccess::fence(); // guarantee at least release consistency.
4698 // Roach-motel semantics.
4699 // It's safe if subsequent LDs and STs float "up" into the critical section,
4700 // but prior LDs and STs within the critical section can't be allowed
4701 // to reorder or float past the ST that releases the lock.
4702 // Loads and stores in the critical section - which appear in program
4703 // order before the store that releases the lock - must also appear
4704 // before the store that releases the lock in memory visibility order.
4705 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4706 // the ST of 0 into the lock-word which releases the lock, so fence
4707 // more than covers this on all platforms.
4708 *adr = 0;
4709 }
4710
4711 // muxAcquire and muxRelease:
4712 //
4713 // * muxAcquire and muxRelease support a single-word lock-word construct.
4714 // The LSB of the word is set IFF the lock is held.
4715 // The remainder of the word points to the head of a singly-linked list
4716 // of threads blocked on the lock.
4717 //
4718 // * The current implementation of muxAcquire-muxRelease uses its own
4719 // dedicated Thread._MuxEvent instance. If we're interested in
4720 // minimizing the peak number of extant ParkEvent instances then
4721 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4722 // as certain invariants were satisfied. Specifically, care would need
4723 // to be taken with regards to consuming unpark() "permits".
4724 // A safe rule of thumb is that a thread would never call muxAcquire()
4725 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4726 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4727 // consume an unpark() permit intended for monitorenter, for instance.
4728 // One way around this would be to widen the restricted-range semaphore
4729 // implemented in park(). Another alternative would be to provide
4730 // multiple instances of the PlatformEvent() for each thread. One
4731 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4732 //
4733 // * Usage:
4734 // -- Only as leaf locks
4735 // -- for short-term locking only as muxAcquire does not perform
4736 // thread state transitions.
4737 //
4738 // Alternatives:
4739 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4740 // but with parking or spin-then-park instead of pure spinning.
4741 // * Use Taura-Oyama-Yonenzawa locks.
4742 // * It's possible to construct a 1-0 lock if we encode the lockword as
4743 // (List,LockByte). Acquire will CAS the full lockword while Release
4744 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4745 // acquiring threads use timers (ParkTimed) to detect and recover from
4746 // the stranding window. Thread/Node structures must be aligned on 256-byte
4747 // boundaries by using placement-new.
4748 // * Augment MCS with advisory back-link fields maintained with CAS().
4749 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4750 // The validity of the backlinks must be ratified before we trust the value.
4751 // If the backlinks are invalid the exiting thread must back-track through the
4752 // the forward links, which are always trustworthy.
4753 // * Add a successor indication. The LockWord is currently encoded as
4754 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4755 // to provide the usual futile-wakeup optimization.
4756 // See RTStt for details.
4757 // * Consider schedctl.sc_nopreempt to cover the critical section.
4758 //
4759
4760
4761 typedef volatile intptr_t MutexT; // Mux Lock-word
4762 enum MuxBits { LOCKBIT = 1 };
4763
4764 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4765 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4766 if (w == 0) return;
4767 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4768 return;
4769 }
4770
4771 TEVENT(muxAcquire - Contention);
4772 ParkEvent * const Self = Thread::current()->_MuxEvent;
4773 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4774 for (;;) {
4775 int its = (os::is_MP() ? 100 : 0) + 1;
4776
4777 // Optional spin phase: spin-then-park strategy
4778 while (--its >= 0) {
4779 w = *Lock;
4780 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4781 return;
4782 }
4783 }
4784
4785 Self->reset();
4786 Self->OnList = intptr_t(Lock);
4787 // The following fence() isn't _strictly necessary as the subsequent
4788 // CAS() both serializes execution and ratifies the fetched *Lock value.
4789 OrderAccess::fence();
4790 for (;;) {
4791 w = *Lock;
4792 if ((w & LOCKBIT) == 0) {
4793 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4794 Self->OnList = 0; // hygiene - allows stronger asserts
4795 return;
4796 }
4797 continue; // Interference -- *Lock changed -- Just retry
4798 }
4799 assert(w & LOCKBIT, "invariant");
4800 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4801 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4802 }
4803
4804 while (Self->OnList != 0) {
4805 Self->park();
4806 }
4807 }
4808 }
4809
4810 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4811 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4812 if (w == 0) return;
4813 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4814 return;
4815 }
4816
4817 TEVENT(muxAcquire - Contention);
4818 ParkEvent * ReleaseAfter = NULL;
4819 if (ev == NULL) {
4820 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4821 }
4822 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4823 for (;;) {
4824 guarantee(ev->OnList == 0, "invariant");
4825 int its = (os::is_MP() ? 100 : 0) + 1;
4826
4827 // Optional spin phase: spin-then-park strategy
4828 while (--its >= 0) {
4829 w = *Lock;
4830 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4831 if (ReleaseAfter != NULL) {
4832 ParkEvent::Release(ReleaseAfter);
4833 }
4834 return;
4835 }
4836 }
4837
4838 ev->reset();
4839 ev->OnList = intptr_t(Lock);
4840 // The following fence() isn't _strictly necessary as the subsequent
4841 // CAS() both serializes execution and ratifies the fetched *Lock value.
4842 OrderAccess::fence();
4843 for (;;) {
4844 w = *Lock;
4845 if ((w & LOCKBIT) == 0) {
4846 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4847 ev->OnList = 0;
4848 // We call ::Release while holding the outer lock, thus
4849 // artificially lengthening the critical section.
4850 // Consider deferring the ::Release() until the subsequent unlock(),
4851 // after we've dropped the outer lock.
4852 if (ReleaseAfter != NULL) {
4853 ParkEvent::Release(ReleaseAfter);
4854 }
4855 return;
4856 }
4857 continue; // Interference -- *Lock changed -- Just retry
4858 }
4859 assert(w & LOCKBIT, "invariant");
4860 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4861 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4862 }
4863
4864 while (ev->OnList != 0) {
4865 ev->park();
4866 }
4867 }
4868 }
4869
4870 // Release() must extract a successor from the list and then wake that thread.
4871 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4872 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4873 // Release() would :
4874 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4875 // (B) Extract a successor from the private list "in-hand"
4876 // (C) attempt to CAS() the residual back into *Lock over null.
4877 // If there were any newly arrived threads and the CAS() would fail.
4878 // In that case Release() would detach the RATs, re-merge the list in-hand
4879 // with the RATs and repeat as needed. Alternately, Release() might
4880 // detach and extract a successor, but then pass the residual list to the wakee.
4881 // The wakee would be responsible for reattaching and remerging before it
4882 // competed for the lock.
4883 //
4884 // Both "pop" and DMR are immune from ABA corruption -- there can be
4885 // multiple concurrent pushers, but only one popper or detacher.
4886 // This implementation pops from the head of the list. This is unfair,
4887 // but tends to provide excellent throughput as hot threads remain hot.
4888 // (We wake recently run threads first).
4889 //
4890 // All paths through muxRelease() will execute a CAS.
4891 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4892 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4893 // executed within the critical section are complete and globally visible before the
4894 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4895 void Thread::muxRelease(volatile intptr_t * Lock) {
4896 for (;;) {
4897 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4898 assert(w & LOCKBIT, "invariant");
4899 if (w == LOCKBIT) return;
4900 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4901 assert(List != NULL, "invariant");
4902 assert(List->OnList == intptr_t(Lock), "invariant");
4903 ParkEvent * const nxt = List->ListNext;
4904 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4905
4906 // The following CAS() releases the lock and pops the head element.
4907 // The CAS() also ratifies the previously fetched lock-word value.
4908 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4909 continue;
4910 }
4911 List->OnList = 0;
4912 OrderAccess::fence();
4913 List->unpark();
4914 return;
4915 }
4916 }
4917
4918
4919 void Threads::verify() {
4920 ALL_JAVA_THREADS(p) {
4921 p->verify();
4922 }
4923 VMThread* thread = VMThread::vm_thread();
4924 if (thread != NULL) thread->verify();
4925 }