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 "logging/logStream.hpp"
45 #include "memory/metaspaceShared.hpp"
46 #include "memory/oopFactory.hpp"
47 #include "memory/resourceArea.hpp"
48 #include "memory/universe.inline.hpp"
49 #include "oops/instanceKlass.hpp"
50 #include "oops/objArrayOop.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/symbol.hpp"
53 #include "oops/verifyOopClosure.hpp"
54 #include "prims/jvm.h"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagWriteableList.hpp"
64 #include "runtime/commandLineFlagRangeList.hpp"
65 #include "runtime/deoptimization.hpp"
66 #include "runtime/frame.inline.hpp"
67 #include "runtime/globals.hpp"
68 #include "runtime/handshake.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/interfaceSupport.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/jniPeriodicChecker.hpp"
74 #include "runtime/timerTrace.hpp"
75 #include "runtime/memprofiler.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/objectMonitor.hpp"
78 #include "runtime/orderAccess.inline.hpp"
79 #include "runtime/osThread.hpp"
80 #include "runtime/safepoint.hpp"
81 #include "runtime/safepointMechanism.inline.hpp"
82 #include "runtime/sharedRuntime.hpp"
83 #include "runtime/statSampler.hpp"
84 #include "runtime/stubRoutines.hpp"
85 #include "runtime/sweeper.hpp"
86 #include "runtime/task.hpp"
87 #include "runtime/thread.inline.hpp"
88 #include "runtime/threadCritical.hpp"
89 #include "runtime/vframe.hpp"
90 #include "runtime/vframeArray.hpp"
91 #include "runtime/vframe_hp.hpp"
92 #include "runtime/vmThread.hpp"
93 #include "runtime/vm_operations.hpp"
94 #include "runtime/vm_version.hpp"
95 #include "services/attachListener.hpp"
96 #include "services/management.hpp"
97 #include "services/memTracker.hpp"
98 #include "services/threadService.hpp"
99 #include "trace/traceMacros.hpp"
100 #include "trace/tracing.hpp"
101 #include "utilities/align.hpp"
102 #include "utilities/defaultStream.hpp"
103 #include "utilities/dtrace.hpp"
104 #include "utilities/events.hpp"
105 #include "utilities/macros.hpp"
106 #include "utilities/preserveException.hpp"
107 #include "utilities/vmError.hpp"
108 #if INCLUDE_ALL_GCS
109 #include "gc/cms/concurrentMarkSweepThread.hpp"
110 #include "gc/g1/concurrentMarkThread.inline.hpp"
111 #include "gc/parallel/pcTasks.hpp"
112 #endif // INCLUDE_ALL_GCS
113 #if INCLUDE_JVMCI
114 #include "jvmci/jvmciCompiler.hpp"
115 #include "jvmci/jvmciRuntime.hpp"
116 #include "logging/logHandle.hpp"
117 #endif
118 #ifdef COMPILER1
119 #include "c1/c1_Compiler.hpp"
120 #endif
121 #ifdef COMPILER2
122 #include "opto/c2compiler.hpp"
123 #include "opto/idealGraphPrinter.hpp"
124 #endif
125 #if INCLUDE_RTM_OPT
126 #include "runtime/rtmLocking.hpp"
127 #endif
128
129 // Initialization after module runtime initialization
130 void universe_post_module_init(); // must happen after call_initPhase2
131
132 #ifdef DTRACE_ENABLED
133
134 // Only bother with this argument setup if dtrace is available
135
136 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
137 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
138
139 #define DTRACE_THREAD_PROBE(probe, javathread) \
140 { \
141 ResourceMark rm(this); \
142 int len = 0; \
143 const char* name = (javathread)->get_thread_name(); \
144 len = strlen(name); \
145 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
146 (char *) name, len, \
147 java_lang_Thread::thread_id((javathread)->threadObj()), \
148 (uintptr_t) (javathread)->osthread()->thread_id(), \
149 java_lang_Thread::is_daemon((javathread)->threadObj())); \
150 }
151
152 #else // ndef DTRACE_ENABLED
153
154 #define DTRACE_THREAD_PROBE(probe, javathread)
155
156 #endif // ndef DTRACE_ENABLED
157
158 #ifndef USE_LIBRARY_BASED_TLS_ONLY
159 // Current thread is maintained as a thread-local variable
160 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
161 #endif
162 // Class hierarchy
163 // - Thread
164 // - VMThread
165 // - WatcherThread
166 // - ConcurrentMarkSweepThread
167 // - JavaThread
168 // - CompilerThread
169
170 // ======= Thread ========
171 // Support for forcing alignment of thread objects for biased locking
172 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
173 if (UseBiasedLocking) {
174 const int alignment = markOopDesc::biased_lock_alignment;
175 size_t aligned_size = size + (alignment - sizeof(intptr_t));
176 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
177 : AllocateHeap(aligned_size, flags, CURRENT_PC,
178 AllocFailStrategy::RETURN_NULL);
179 void* aligned_addr = align_up(real_malloc_addr, alignment);
180 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
181 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
182 "JavaThread alignment code overflowed allocated storage");
183 if (aligned_addr != real_malloc_addr) {
184 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
185 p2i(real_malloc_addr),
186 p2i(aligned_addr));
187 }
188 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
189 return aligned_addr;
190 } else {
191 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
192 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
193 }
194 }
195
196 void Thread::operator delete(void* p) {
197 if (UseBiasedLocking) {
198 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
199 FreeHeap(real_malloc_addr);
200 } else {
201 FreeHeap(p);
202 }
203 }
204
205
206 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
207 // JavaThread
208
209
210 Thread::Thread() {
211 // stack and get_thread
212 set_stack_base(NULL);
213 set_stack_size(0);
214 set_self_raw_id(0);
215 set_lgrp_id(-1);
216 DEBUG_ONLY(clear_suspendible_thread();)
217
218 // allocated data structures
219 set_osthread(NULL);
220 set_resource_area(new (mtThread)ResourceArea());
221 DEBUG_ONLY(_current_resource_mark = NULL;)
222 set_handle_area(new (mtThread) HandleArea(NULL));
223 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
224 set_active_handles(NULL);
225 set_free_handle_block(NULL);
226 set_last_handle_mark(NULL);
227
228 // This initial value ==> never claimed.
229 _oops_do_parity = 0;
230
231 // the handle mark links itself to last_handle_mark
232 new HandleMark(this);
233
234 // plain initialization
235 debug_only(_owned_locks = NULL;)
236 debug_only(_allow_allocation_count = 0;)
237 NOT_PRODUCT(_allow_safepoint_count = 0;)
238 NOT_PRODUCT(_skip_gcalot = false;)
239 _jvmti_env_iteration_count = 0;
240 set_allocated_bytes(0);
241 _vm_operation_started_count = 0;
242 _vm_operation_completed_count = 0;
243 _current_pending_monitor = NULL;
244 _current_pending_monitor_is_from_java = true;
245 _current_waiting_monitor = NULL;
246 _num_nested_signal = 0;
247 omFreeList = NULL;
248 omFreeCount = 0;
249 omFreeProvision = 32;
250 omInUseList = NULL;
251 omInUseCount = 0;
252
253 #ifdef ASSERT
254 _visited_for_critical_count = false;
255 #endif
256
257 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
258 Monitor::_safepoint_check_sometimes);
259 _suspend_flags = 0;
260
261 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
262 _hashStateX = os::random();
263 _hashStateY = 842502087;
264 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
265 _hashStateW = 273326509;
266
267 _OnTrap = 0;
268 _schedctl = NULL;
269 _Stalled = 0;
270 _TypeTag = 0x2BAD;
271
272 // Many of the following fields are effectively final - immutable
273 // Note that nascent threads can't use the Native Monitor-Mutex
274 // construct until the _MutexEvent is initialized ...
275 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
276 // we might instead use a stack of ParkEvents that we could provision on-demand.
277 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
278 // and ::Release()
279 _ParkEvent = ParkEvent::Allocate(this);
280 _SleepEvent = ParkEvent::Allocate(this);
281 _MutexEvent = ParkEvent::Allocate(this);
282 _MuxEvent = ParkEvent::Allocate(this);
283
284 #ifdef CHECK_UNHANDLED_OOPS
285 if (CheckUnhandledOops) {
286 _unhandled_oops = new UnhandledOops(this);
287 }
288 #endif // CHECK_UNHANDLED_OOPS
289 #ifdef ASSERT
290 if (UseBiasedLocking) {
291 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
292 assert(this == _real_malloc_address ||
293 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
294 "bug in forced alignment of thread objects");
295 }
296 #endif // ASSERT
297 }
298
299 void Thread::initialize_thread_current() {
300 #ifndef USE_LIBRARY_BASED_TLS_ONLY
301 assert(_thr_current == NULL, "Thread::current already initialized");
302 _thr_current = this;
303 #endif
304 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
305 ThreadLocalStorage::set_thread(this);
306 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
307 }
308
309 void Thread::clear_thread_current() {
310 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
311 #ifndef USE_LIBRARY_BASED_TLS_ONLY
312 _thr_current = NULL;
313 #endif
314 ThreadLocalStorage::set_thread(NULL);
315 }
316
317 void Thread::record_stack_base_and_size() {
318 set_stack_base(os::current_stack_base());
319 set_stack_size(os::current_stack_size());
320 // CR 7190089: on Solaris, primordial thread's stack is adjusted
321 // in initialize_thread(). Without the adjustment, stack size is
322 // incorrect if stack is set to unlimited (ulimit -s unlimited).
323 // So far, only Solaris has real implementation of initialize_thread().
324 //
325 // set up any platform-specific state.
326 os::initialize_thread(this);
327
328 // Set stack limits after thread is initialized.
329 if (is_Java_thread()) {
330 ((JavaThread*) this)->set_stack_overflow_limit();
331 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
332 }
333 #if INCLUDE_NMT
334 // record thread's native stack, stack grows downward
335 MemTracker::record_thread_stack(stack_end(), stack_size());
336 #endif // INCLUDE_NMT
337 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
338 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
339 os::current_thread_id(), p2i(stack_base() - stack_size()),
340 p2i(stack_base()), stack_size()/1024);
341 }
342
343
344 Thread::~Thread() {
345 EVENT_THREAD_DESTRUCT(this);
346
347 // stack_base can be NULL if the thread is never started or exited before
348 // record_stack_base_and_size called. Although, we would like to ensure
349 // that all started threads do call record_stack_base_and_size(), there is
350 // not proper way to enforce that.
351 #if INCLUDE_NMT
352 if (_stack_base != NULL) {
353 MemTracker::release_thread_stack(stack_end(), stack_size());
354 #ifdef ASSERT
355 set_stack_base(NULL);
356 #endif
357 }
358 #endif // INCLUDE_NMT
359
360 // deallocate data structures
361 delete resource_area();
362 // since the handle marks are using the handle area, we have to deallocated the root
363 // handle mark before deallocating the thread's handle area,
364 assert(last_handle_mark() != NULL, "check we have an element");
365 delete last_handle_mark();
366 assert(last_handle_mark() == NULL, "check we have reached the end");
367
368 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
369 // We NULL out the fields for good hygiene.
370 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
371 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
372 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
373 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
374
375 delete handle_area();
376 delete metadata_handles();
377
378 // SR_handler uses this as a termination indicator -
379 // needs to happen before os::free_thread()
380 delete _SR_lock;
381 _SR_lock = NULL;
382
383 // osthread() can be NULL, if creation of thread failed.
384 if (osthread() != NULL) os::free_thread(osthread());
385
386 // clear Thread::current if thread is deleting itself.
387 // Needed to ensure JNI correctly detects non-attached threads.
388 if (this == Thread::current()) {
389 clear_thread_current();
390 }
391
392 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
393 }
394
395 // NOTE: dummy function for assertion purpose.
396 void Thread::run() {
397 ShouldNotReachHere();
398 }
399
400 #ifdef ASSERT
401 // Private method to check for dangling thread pointer
402 void check_for_dangling_thread_pointer(Thread *thread) {
403 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
404 "possibility of dangling Thread pointer");
405 }
406 #endif
407
408 ThreadPriority Thread::get_priority(const Thread* const thread) {
409 ThreadPriority priority;
410 // Can return an error!
411 (void)os::get_priority(thread, priority);
412 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
413 return priority;
414 }
415
416 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
417 debug_only(check_for_dangling_thread_pointer(thread);)
418 // Can return an error!
419 (void)os::set_priority(thread, priority);
420 }
421
422
423 void Thread::start(Thread* thread) {
424 // Start is different from resume in that its safety is guaranteed by context or
425 // being called from a Java method synchronized on the Thread object.
426 if (!DisableStartThread) {
427 if (thread->is_Java_thread()) {
428 // Initialize the thread state to RUNNABLE before starting this thread.
429 // Can not set it after the thread started because we do not know the
430 // exact thread state at that time. It could be in MONITOR_WAIT or
431 // in SLEEPING or some other state.
432 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
433 java_lang_Thread::RUNNABLE);
434 }
435 os::start_thread(thread);
436 }
437 }
438
439 // Enqueue a VM_Operation to do the job for us - sometime later
440 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
441 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
442 VMThread::execute(vm_stop);
443 }
444
445
446 // Check if an external suspend request has completed (or has been
447 // cancelled). Returns true if the thread is externally suspended and
448 // false otherwise.
449 //
450 // The bits parameter returns information about the code path through
451 // the routine. Useful for debugging:
452 //
453 // set in is_ext_suspend_completed():
454 // 0x00000001 - routine was entered
455 // 0x00000010 - routine return false at end
456 // 0x00000100 - thread exited (return false)
457 // 0x00000200 - suspend request cancelled (return false)
458 // 0x00000400 - thread suspended (return true)
459 // 0x00001000 - thread is in a suspend equivalent state (return true)
460 // 0x00002000 - thread is native and walkable (return true)
461 // 0x00004000 - thread is native_trans and walkable (needed retry)
462 //
463 // set in wait_for_ext_suspend_completion():
464 // 0x00010000 - routine was entered
465 // 0x00020000 - suspend request cancelled before loop (return false)
466 // 0x00040000 - thread suspended before loop (return true)
467 // 0x00080000 - suspend request cancelled in loop (return false)
468 // 0x00100000 - thread suspended in loop (return true)
469 // 0x00200000 - suspend not completed during retry loop (return false)
470
471 // Helper class for tracing suspend wait debug bits.
472 //
473 // 0x00000100 indicates that the target thread exited before it could
474 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
475 // 0x00080000 each indicate a cancelled suspend request so they don't
476 // count as wait failures either.
477 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
478
479 class TraceSuspendDebugBits : public StackObj {
480 private:
481 JavaThread * jt;
482 bool is_wait;
483 bool called_by_wait; // meaningful when !is_wait
484 uint32_t * bits;
485
486 public:
487 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
488 uint32_t *_bits) {
489 jt = _jt;
490 is_wait = _is_wait;
491 called_by_wait = _called_by_wait;
492 bits = _bits;
493 }
494
495 ~TraceSuspendDebugBits() {
496 if (!is_wait) {
497 #if 1
498 // By default, don't trace bits for is_ext_suspend_completed() calls.
499 // That trace is very chatty.
500 return;
501 #else
502 if (!called_by_wait) {
503 // If tracing for is_ext_suspend_completed() is enabled, then only
504 // trace calls to it from wait_for_ext_suspend_completion()
505 return;
506 }
507 #endif
508 }
509
510 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
511 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
512 MutexLocker ml(Threads_lock); // needed for get_thread_name()
513 ResourceMark rm;
514
515 tty->print_cr(
516 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
517 jt->get_thread_name(), *bits);
518
519 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
520 }
521 }
522 }
523 };
524 #undef DEBUG_FALSE_BITS
525
526
527 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
528 uint32_t *bits) {
529 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
530
531 bool did_trans_retry = false; // only do thread_in_native_trans retry once
532 bool do_trans_retry; // flag to force the retry
533
534 *bits |= 0x00000001;
535
536 do {
537 do_trans_retry = false;
538
539 if (is_exiting()) {
540 // Thread is in the process of exiting. This is always checked
541 // first to reduce the risk of dereferencing a freed JavaThread.
542 *bits |= 0x00000100;
543 return false;
544 }
545
546 if (!is_external_suspend()) {
547 // Suspend request is cancelled. This is always checked before
548 // is_ext_suspended() to reduce the risk of a rogue resume
549 // confusing the thread that made the suspend request.
550 *bits |= 0x00000200;
551 return false;
552 }
553
554 if (is_ext_suspended()) {
555 // thread is suspended
556 *bits |= 0x00000400;
557 return true;
558 }
559
560 // Now that we no longer do hard suspends of threads running
561 // native code, the target thread can be changing thread state
562 // while we are in this routine:
563 //
564 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
565 //
566 // We save a copy of the thread state as observed at this moment
567 // and make our decision about suspend completeness based on the
568 // copy. This closes the race where the thread state is seen as
569 // _thread_in_native_trans in the if-thread_blocked check, but is
570 // seen as _thread_blocked in if-thread_in_native_trans check.
571 JavaThreadState save_state = thread_state();
572
573 if (save_state == _thread_blocked && is_suspend_equivalent()) {
574 // If the thread's state is _thread_blocked and this blocking
575 // condition is known to be equivalent to a suspend, then we can
576 // consider the thread to be externally suspended. This means that
577 // the code that sets _thread_blocked has been modified to do
578 // self-suspension if the blocking condition releases. We also
579 // used to check for CONDVAR_WAIT here, but that is now covered by
580 // the _thread_blocked with self-suspension check.
581 //
582 // Return true since we wouldn't be here unless there was still an
583 // external suspend request.
584 *bits |= 0x00001000;
585 return true;
586 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
587 // Threads running native code will self-suspend on native==>VM/Java
588 // transitions. If its stack is walkable (should always be the case
589 // unless this function is called before the actual java_suspend()
590 // call), then the wait is done.
591 *bits |= 0x00002000;
592 return true;
593 } else if (!called_by_wait && !did_trans_retry &&
594 save_state == _thread_in_native_trans &&
595 frame_anchor()->walkable()) {
596 // The thread is transitioning from thread_in_native to another
597 // thread state. check_safepoint_and_suspend_for_native_trans()
598 // will force the thread to self-suspend. If it hasn't gotten
599 // there yet we may have caught the thread in-between the native
600 // code check above and the self-suspend. Lucky us. If we were
601 // called by wait_for_ext_suspend_completion(), then it
602 // will be doing the retries so we don't have to.
603 //
604 // Since we use the saved thread state in the if-statement above,
605 // there is a chance that the thread has already transitioned to
606 // _thread_blocked by the time we get here. In that case, we will
607 // make a single unnecessary pass through the logic below. This
608 // doesn't hurt anything since we still do the trans retry.
609
610 *bits |= 0x00004000;
611
612 // Once the thread leaves thread_in_native_trans for another
613 // thread state, we break out of this retry loop. We shouldn't
614 // need this flag to prevent us from getting back here, but
615 // sometimes paranoia is good.
616 did_trans_retry = true;
617
618 // We wait for the thread to transition to a more usable state.
619 for (int i = 1; i <= SuspendRetryCount; i++) {
620 // We used to do an "os::yield_all(i)" call here with the intention
621 // that yielding would increase on each retry. However, the parameter
622 // is ignored on Linux which means the yield didn't scale up. Waiting
623 // on the SR_lock below provides a much more predictable scale up for
624 // the delay. It also provides a simple/direct point to check for any
625 // safepoint requests from the VMThread
626
627 // temporarily drops SR_lock while doing wait with safepoint check
628 // (if we're a JavaThread - the WatcherThread can also call this)
629 // and increase delay with each retry
630 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
631
632 // check the actual thread state instead of what we saved above
633 if (thread_state() != _thread_in_native_trans) {
634 // the thread has transitioned to another thread state so
635 // try all the checks (except this one) one more time.
636 do_trans_retry = true;
637 break;
638 }
639 } // end retry loop
640
641
642 }
643 } while (do_trans_retry);
644
645 *bits |= 0x00000010;
646 return false;
647 }
648
649 // Wait for an external suspend request to complete (or be cancelled).
650 // Returns true if the thread is externally suspended and false otherwise.
651 //
652 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
653 uint32_t *bits) {
654 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
655 false /* !called_by_wait */, bits);
656
657 // local flag copies to minimize SR_lock hold time
658 bool is_suspended;
659 bool pending;
660 uint32_t reset_bits;
661
662 // set a marker so is_ext_suspend_completed() knows we are the caller
663 *bits |= 0x00010000;
664
665 // We use reset_bits to reinitialize the bits value at the top of
666 // each retry loop. This allows the caller to make use of any
667 // unused bits for their own marking purposes.
668 reset_bits = *bits;
669
670 {
671 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
672 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
673 delay, bits);
674 pending = is_external_suspend();
675 }
676 // must release SR_lock to allow suspension to complete
677
678 if (!pending) {
679 // A cancelled suspend request is the only false return from
680 // is_ext_suspend_completed() that keeps us from entering the
681 // retry loop.
682 *bits |= 0x00020000;
683 return false;
684 }
685
686 if (is_suspended) {
687 *bits |= 0x00040000;
688 return true;
689 }
690
691 for (int i = 1; i <= retries; i++) {
692 *bits = reset_bits; // reinit to only track last retry
693
694 // We used to do an "os::yield_all(i)" call here with the intention
695 // that yielding would increase on each retry. However, the parameter
696 // is ignored on Linux which means the yield didn't scale up. Waiting
697 // on the SR_lock below provides a much more predictable scale up for
698 // the delay. It also provides a simple/direct point to check for any
699 // safepoint requests from the VMThread
700
701 {
702 MutexLocker ml(SR_lock());
703 // wait with safepoint check (if we're a JavaThread - the WatcherThread
704 // can also call this) and increase delay with each retry
705 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
706
707 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
708 delay, bits);
709
710 // It is possible for the external suspend request to be cancelled
711 // (by a resume) before the actual suspend operation is completed.
712 // Refresh our local copy to see if we still need to wait.
713 pending = is_external_suspend();
714 }
715
716 if (!pending) {
717 // A cancelled suspend request is the only false return from
718 // is_ext_suspend_completed() that keeps us from staying in the
719 // retry loop.
720 *bits |= 0x00080000;
721 return false;
722 }
723
724 if (is_suspended) {
725 *bits |= 0x00100000;
726 return true;
727 }
728 } // end retry loop
729
730 // thread did not suspend after all our retries
731 *bits |= 0x00200000;
732 return false;
733 }
734
735 #ifndef PRODUCT
736 void JavaThread::record_jump(address target, address instr, const char* file,
737 int line) {
738
739 // This should not need to be atomic as the only way for simultaneous
740 // updates is via interrupts. Even then this should be rare or non-existent
741 // and we don't care that much anyway.
742
743 int index = _jmp_ring_index;
744 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
745 _jmp_ring[index]._target = (intptr_t) target;
746 _jmp_ring[index]._instruction = (intptr_t) instr;
747 _jmp_ring[index]._file = file;
748 _jmp_ring[index]._line = line;
749 }
750 #endif // PRODUCT
751
752 void Thread::interrupt(Thread* thread) {
753 debug_only(check_for_dangling_thread_pointer(thread);)
754 os::interrupt(thread);
755 }
756
757 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
758 debug_only(check_for_dangling_thread_pointer(thread);)
759 // Note: If clear_interrupted==false, this simply fetches and
760 // returns the value of the field osthread()->interrupted().
761 return os::is_interrupted(thread, clear_interrupted);
762 }
763
764
765 // GC Support
766 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
767 jint thread_parity = _oops_do_parity;
768 if (thread_parity != strong_roots_parity) {
769 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
770 if (res == thread_parity) {
771 return true;
772 } else {
773 guarantee(res == strong_roots_parity, "Or else what?");
774 return false;
775 }
776 }
777 return false;
778 }
779
780 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
781 active_handles()->oops_do(f);
782 // Do oop for ThreadShadow
783 f->do_oop((oop*)&_pending_exception);
784 handle_area()->oops_do(f);
785
786 if (MonitorInUseLists) {
787 // When using thread local monitor lists, we scan them here,
788 // and the remaining global monitors in ObjectSynchronizer::oops_do().
789 ObjectSynchronizer::thread_local_used_oops_do(this, f);
790 }
791 }
792
793 void Thread::metadata_handles_do(void f(Metadata*)) {
794 // Only walk the Handles in Thread.
795 if (metadata_handles() != NULL) {
796 for (int i = 0; i< metadata_handles()->length(); i++) {
797 f(metadata_handles()->at(i));
798 }
799 }
800 }
801
802 void Thread::print_on(outputStream* st) const {
803 // get_priority assumes osthread initialized
804 if (osthread() != NULL) {
805 int os_prio;
806 if (os::get_native_priority(this, &os_prio) == OS_OK) {
807 st->print("os_prio=%d ", os_prio);
808 }
809 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
810 ext().print_on(st);
811 osthread()->print_on(st);
812 }
813 debug_only(if (WizardMode) print_owned_locks_on(st);)
814 }
815
816 // Thread::print_on_error() is called by fatal error handler. Don't use
817 // any lock or allocate memory.
818 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
819 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
820
821 if (is_VM_thread()) { st->print("VMThread"); }
822 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
823 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
824 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
825 else { st->print("Thread"); }
826
827 if (is_Named_thread()) {
828 st->print(" \"%s\"", name());
829 }
830
831 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
832 p2i(stack_end()), p2i(stack_base()));
833
834 if (osthread()) {
835 st->print(" [id=%d]", osthread()->thread_id());
836 }
837 }
838
839 void Thread::print_value_on(outputStream* st) const {
840 if (is_Named_thread()) {
841 st->print(" \"%s\" ", name());
842 }
843 st->print(INTPTR_FORMAT, p2i(this)); // print address
844 }
845
846 #ifdef ASSERT
847 void Thread::print_owned_locks_on(outputStream* st) const {
848 Monitor *cur = _owned_locks;
849 if (cur == NULL) {
850 st->print(" (no locks) ");
851 } else {
852 st->print_cr(" Locks owned:");
853 while (cur) {
854 cur->print_on(st);
855 cur = cur->next();
856 }
857 }
858 }
859
860 static int ref_use_count = 0;
861
862 bool Thread::owns_locks_but_compiled_lock() const {
863 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
864 if (cur != Compile_lock) return true;
865 }
866 return false;
867 }
868
869
870 #endif
871
872 #ifndef PRODUCT
873
874 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
875 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
876 // no threads which allow_vm_block's are held
877 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
878 // Check if current thread is allowed to block at a safepoint
879 if (!(_allow_safepoint_count == 0)) {
880 fatal("Possible safepoint reached by thread that does not allow it");
881 }
882 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
883 fatal("LEAF method calling lock?");
884 }
885
886 #ifdef ASSERT
887 if (potential_vm_operation && is_Java_thread()
888 && !Universe::is_bootstrapping()) {
889 // Make sure we do not hold any locks that the VM thread also uses.
890 // This could potentially lead to deadlocks
891 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
892 // Threads_lock is special, since the safepoint synchronization will not start before this is
893 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
894 // since it is used to transfer control between JavaThreads and the VMThread
895 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
896 if ((cur->allow_vm_block() &&
897 cur != Threads_lock &&
898 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
899 cur != VMOperationRequest_lock &&
900 cur != VMOperationQueue_lock) ||
901 cur->rank() == Mutex::special) {
902 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
903 }
904 }
905 }
906
907 if (GCALotAtAllSafepoints) {
908 // We could enter a safepoint here and thus have a gc
909 InterfaceSupport::check_gc_alot();
910 }
911 #endif
912 }
913 #endif
914
915 bool Thread::is_in_stack(address adr) const {
916 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
917 address end = os::current_stack_pointer();
918 // Allow non Java threads to call this without stack_base
919 if (_stack_base == NULL) return true;
920 if (stack_base() >= adr && adr >= end) return true;
921
922 return false;
923 }
924
925 bool Thread::is_in_usable_stack(address adr) const {
926 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
927 size_t usable_stack_size = _stack_size - stack_guard_size;
928
929 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
930 }
931
932
933 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
934 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
935 // used for compilation in the future. If that change is made, the need for these methods
936 // should be revisited, and they should be removed if possible.
937
938 bool Thread::is_lock_owned(address adr) const {
939 return on_local_stack(adr);
940 }
941
942 bool Thread::set_as_starting_thread() {
943 // NOTE: this must be called inside the main thread.
944 return os::create_main_thread((JavaThread*)this);
945 }
946
947 static void initialize_class(Symbol* class_name, TRAPS) {
948 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
949 InstanceKlass::cast(klass)->initialize(CHECK);
950 }
951
952
953 // Creates the initial ThreadGroup
954 static Handle create_initial_thread_group(TRAPS) {
955 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
956 InstanceKlass* ik = InstanceKlass::cast(k);
957
958 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
959 {
960 JavaValue result(T_VOID);
961 JavaCalls::call_special(&result,
962 system_instance,
963 ik,
964 vmSymbols::object_initializer_name(),
965 vmSymbols::void_method_signature(),
966 CHECK_NH);
967 }
968 Universe::set_system_thread_group(system_instance());
969
970 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
971 {
972 JavaValue result(T_VOID);
973 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
974 JavaCalls::call_special(&result,
975 main_instance,
976 ik,
977 vmSymbols::object_initializer_name(),
978 vmSymbols::threadgroup_string_void_signature(),
979 system_instance,
980 string,
981 CHECK_NH);
982 }
983 return main_instance;
984 }
985
986 // Creates the initial Thread
987 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
988 TRAPS) {
989 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
990 InstanceKlass* ik = InstanceKlass::cast(k);
991 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
992
993 java_lang_Thread::set_thread(thread_oop(), thread);
994 java_lang_Thread::set_priority(thread_oop(), NormPriority);
995 thread->set_threadObj(thread_oop());
996
997 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
998
999 JavaValue result(T_VOID);
1000 JavaCalls::call_special(&result, thread_oop,
1001 ik,
1002 vmSymbols::object_initializer_name(),
1003 vmSymbols::threadgroup_string_void_signature(),
1004 thread_group,
1005 string,
1006 CHECK_NULL);
1007 return thread_oop();
1008 }
1009
1010 char java_runtime_name[128] = "";
1011 char java_runtime_version[128] = "";
1012
1013 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1014 static const char* get_java_runtime_name(TRAPS) {
1015 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1016 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1017 fieldDescriptor fd;
1018 bool found = k != NULL &&
1019 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1020 vmSymbols::string_signature(), &fd);
1021 if (found) {
1022 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1023 if (name_oop == NULL) {
1024 return NULL;
1025 }
1026 const char* name = java_lang_String::as_utf8_string(name_oop,
1027 java_runtime_name,
1028 sizeof(java_runtime_name));
1029 return name;
1030 } else {
1031 return NULL;
1032 }
1033 }
1034
1035 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1036 static const char* get_java_runtime_version(TRAPS) {
1037 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1038 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1039 fieldDescriptor fd;
1040 bool found = k != NULL &&
1041 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1042 vmSymbols::string_signature(), &fd);
1043 if (found) {
1044 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1045 if (name_oop == NULL) {
1046 return NULL;
1047 }
1048 const char* name = java_lang_String::as_utf8_string(name_oop,
1049 java_runtime_version,
1050 sizeof(java_runtime_version));
1051 return name;
1052 } else {
1053 return NULL;
1054 }
1055 }
1056
1057 // General purpose hook into Java code, run once when the VM is initialized.
1058 // The Java library method itself may be changed independently from the VM.
1059 static void call_postVMInitHook(TRAPS) {
1060 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1061 if (klass != NULL) {
1062 JavaValue result(T_VOID);
1063 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1064 vmSymbols::void_method_signature(),
1065 CHECK);
1066 }
1067 }
1068
1069 static void reset_vm_info_property(TRAPS) {
1070 // the vm info string
1071 ResourceMark rm(THREAD);
1072 const char *vm_info = VM_Version::vm_info_string();
1073
1074 // java.lang.System class
1075 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1076
1077 // setProperty arguments
1078 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1079 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1080
1081 // return value
1082 JavaValue r(T_OBJECT);
1083
1084 // public static String setProperty(String key, String value);
1085 JavaCalls::call_static(&r,
1086 klass,
1087 vmSymbols::setProperty_name(),
1088 vmSymbols::string_string_string_signature(),
1089 key_str,
1090 value_str,
1091 CHECK);
1092 }
1093
1094
1095 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1096 bool daemon, TRAPS) {
1097 assert(thread_group.not_null(), "thread group should be specified");
1098 assert(threadObj() == NULL, "should only create Java thread object once");
1099
1100 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1101 InstanceKlass* ik = InstanceKlass::cast(k);
1102 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1103
1104 java_lang_Thread::set_thread(thread_oop(), this);
1105 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1106 set_threadObj(thread_oop());
1107
1108 JavaValue result(T_VOID);
1109 if (thread_name != NULL) {
1110 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1111 // Thread gets assigned specified name and null target
1112 JavaCalls::call_special(&result,
1113 thread_oop,
1114 ik,
1115 vmSymbols::object_initializer_name(),
1116 vmSymbols::threadgroup_string_void_signature(),
1117 thread_group, // Argument 1
1118 name, // Argument 2
1119 THREAD);
1120 } else {
1121 // Thread gets assigned name "Thread-nnn" and null target
1122 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1123 JavaCalls::call_special(&result,
1124 thread_oop,
1125 ik,
1126 vmSymbols::object_initializer_name(),
1127 vmSymbols::threadgroup_runnable_void_signature(),
1128 thread_group, // Argument 1
1129 Handle(), // Argument 2
1130 THREAD);
1131 }
1132
1133
1134 if (daemon) {
1135 java_lang_Thread::set_daemon(thread_oop());
1136 }
1137
1138 if (HAS_PENDING_EXCEPTION) {
1139 return;
1140 }
1141
1142 Klass* group = SystemDictionary::ThreadGroup_klass();
1143 Handle threadObj(THREAD, this->threadObj());
1144
1145 JavaCalls::call_special(&result,
1146 thread_group,
1147 group,
1148 vmSymbols::add_method_name(),
1149 vmSymbols::thread_void_signature(),
1150 threadObj, // Arg 1
1151 THREAD);
1152 }
1153
1154 // NamedThread -- non-JavaThread subclasses with multiple
1155 // uniquely named instances should derive from this.
1156 NamedThread::NamedThread() : Thread() {
1157 _name = NULL;
1158 _processed_thread = NULL;
1159 _gc_id = GCId::undefined();
1160 }
1161
1162 NamedThread::~NamedThread() {
1163 if (_name != NULL) {
1164 FREE_C_HEAP_ARRAY(char, _name);
1165 _name = NULL;
1166 }
1167 }
1168
1169 void NamedThread::set_name(const char* format, ...) {
1170 guarantee(_name == NULL, "Only get to set name once.");
1171 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1172 guarantee(_name != NULL, "alloc failure");
1173 va_list ap;
1174 va_start(ap, format);
1175 jio_vsnprintf(_name, max_name_len, format, ap);
1176 va_end(ap);
1177 }
1178
1179 void NamedThread::initialize_named_thread() {
1180 set_native_thread_name(name());
1181 }
1182
1183 void NamedThread::print_on(outputStream* st) const {
1184 st->print("\"%s\" ", name());
1185 Thread::print_on(st);
1186 st->cr();
1187 }
1188
1189
1190 // ======= WatcherThread ========
1191
1192 // The watcher thread exists to simulate timer interrupts. It should
1193 // be replaced by an abstraction over whatever native support for
1194 // timer interrupts exists on the platform.
1195
1196 WatcherThread* WatcherThread::_watcher_thread = NULL;
1197 bool WatcherThread::_startable = false;
1198 volatile bool WatcherThread::_should_terminate = false;
1199
1200 WatcherThread::WatcherThread() : Thread() {
1201 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1202 if (os::create_thread(this, os::watcher_thread)) {
1203 _watcher_thread = this;
1204
1205 // Set the watcher thread to the highest OS priority which should not be
1206 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1207 // is created. The only normal thread using this priority is the reference
1208 // handler thread, which runs for very short intervals only.
1209 // If the VMThread's priority is not lower than the WatcherThread profiling
1210 // will be inaccurate.
1211 os::set_priority(this, MaxPriority);
1212 if (!DisableStartThread) {
1213 os::start_thread(this);
1214 }
1215 }
1216 }
1217
1218 int WatcherThread::sleep() const {
1219 // The WatcherThread does not participate in the safepoint protocol
1220 // for the PeriodicTask_lock because it is not a JavaThread.
1221 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1222
1223 if (_should_terminate) {
1224 // check for termination before we do any housekeeping or wait
1225 return 0; // we did not sleep.
1226 }
1227
1228 // remaining will be zero if there are no tasks,
1229 // causing the WatcherThread to sleep until a task is
1230 // enrolled
1231 int remaining = PeriodicTask::time_to_wait();
1232 int time_slept = 0;
1233
1234 // we expect this to timeout - we only ever get unparked when
1235 // we should terminate or when a new task has been enrolled
1236 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1237
1238 jlong time_before_loop = os::javaTimeNanos();
1239
1240 while (true) {
1241 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1242 remaining);
1243 jlong now = os::javaTimeNanos();
1244
1245 if (remaining == 0) {
1246 // if we didn't have any tasks we could have waited for a long time
1247 // consider the time_slept zero and reset time_before_loop
1248 time_slept = 0;
1249 time_before_loop = now;
1250 } else {
1251 // need to recalculate since we might have new tasks in _tasks
1252 time_slept = (int) ((now - time_before_loop) / 1000000);
1253 }
1254
1255 // Change to task list or spurious wakeup of some kind
1256 if (timedout || _should_terminate) {
1257 break;
1258 }
1259
1260 remaining = PeriodicTask::time_to_wait();
1261 if (remaining == 0) {
1262 // Last task was just disenrolled so loop around and wait until
1263 // another task gets enrolled
1264 continue;
1265 }
1266
1267 remaining -= time_slept;
1268 if (remaining <= 0) {
1269 break;
1270 }
1271 }
1272
1273 return time_slept;
1274 }
1275
1276 void WatcherThread::run() {
1277 assert(this == watcher_thread(), "just checking");
1278
1279 this->record_stack_base_and_size();
1280 this->set_native_thread_name(this->name());
1281 this->set_active_handles(JNIHandleBlock::allocate_block());
1282 while (true) {
1283 assert(watcher_thread() == Thread::current(), "thread consistency check");
1284 assert(watcher_thread() == this, "thread consistency check");
1285
1286 // Calculate how long it'll be until the next PeriodicTask work
1287 // should be done, and sleep that amount of time.
1288 int time_waited = sleep();
1289
1290 if (VMError::is_error_reported()) {
1291 // A fatal error has happened, the error handler(VMError::report_and_die)
1292 // should abort JVM after creating an error log file. However in some
1293 // rare cases, the error handler itself might deadlock. Here periodically
1294 // check for error reporting timeouts, and if it happens, just proceed to
1295 // abort the VM.
1296
1297 // This code is in WatcherThread because WatcherThread wakes up
1298 // periodically so the fatal error handler doesn't need to do anything;
1299 // also because the WatcherThread is less likely to crash than other
1300 // threads.
1301
1302 for (;;) {
1303 // Note: we use naked sleep in this loop because we want to avoid using
1304 // any kind of VM infrastructure which may be broken at this point.
1305 if (VMError::check_timeout()) {
1306 // We hit error reporting timeout. Error reporting was interrupted and
1307 // will be wrapping things up now (closing files etc). Give it some more
1308 // time, then quit the VM.
1309 os::naked_short_sleep(200);
1310 // Print a message to stderr.
1311 fdStream err(defaultStream::output_fd());
1312 err.print_raw_cr("# [ timer expired, abort... ]");
1313 // skip atexit/vm_exit/vm_abort hooks
1314 os::die();
1315 }
1316
1317 // Wait a second, then recheck for timeout.
1318 os::naked_short_sleep(999);
1319 }
1320 }
1321
1322 if (_should_terminate) {
1323 // check for termination before posting the next tick
1324 break;
1325 }
1326
1327 PeriodicTask::real_time_tick(time_waited);
1328 }
1329
1330 // Signal that it is terminated
1331 {
1332 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1333 _watcher_thread = NULL;
1334 Terminator_lock->notify();
1335 }
1336 }
1337
1338 void WatcherThread::start() {
1339 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1340
1341 if (watcher_thread() == NULL && _startable) {
1342 _should_terminate = false;
1343 // Create the single instance of WatcherThread
1344 new WatcherThread();
1345 }
1346 }
1347
1348 void WatcherThread::make_startable() {
1349 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1350 _startable = true;
1351 }
1352
1353 void WatcherThread::stop() {
1354 {
1355 // Follow normal safepoint aware lock enter protocol since the
1356 // WatcherThread is stopped by another JavaThread.
1357 MutexLocker ml(PeriodicTask_lock);
1358 _should_terminate = true;
1359
1360 WatcherThread* watcher = watcher_thread();
1361 if (watcher != NULL) {
1362 // unpark the WatcherThread so it can see that it should terminate
1363 watcher->unpark();
1364 }
1365 }
1366
1367 MutexLocker mu(Terminator_lock);
1368
1369 while (watcher_thread() != NULL) {
1370 // This wait should make safepoint checks, wait without a timeout,
1371 // and wait as a suspend-equivalent condition.
1372 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1373 Mutex::_as_suspend_equivalent_flag);
1374 }
1375 }
1376
1377 void WatcherThread::unpark() {
1378 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1379 PeriodicTask_lock->notify();
1380 }
1381
1382 void WatcherThread::print_on(outputStream* st) const {
1383 st->print("\"%s\" ", name());
1384 Thread::print_on(st);
1385 st->cr();
1386 }
1387
1388 // ======= JavaThread ========
1389
1390 #if INCLUDE_JVMCI
1391
1392 jlong* JavaThread::_jvmci_old_thread_counters;
1393
1394 bool jvmci_counters_include(JavaThread* thread) {
1395 oop threadObj = thread->threadObj();
1396 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1397 }
1398
1399 void JavaThread::collect_counters(typeArrayOop array) {
1400 if (JVMCICounterSize > 0) {
1401 MutexLocker tl(Threads_lock);
1402 for (int i = 0; i < array->length(); i++) {
1403 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1404 }
1405 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1406 if (jvmci_counters_include(tp)) {
1407 for (int i = 0; i < array->length(); i++) {
1408 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1409 }
1410 }
1411 }
1412 }
1413 }
1414
1415 #endif // INCLUDE_JVMCI
1416
1417 // A JavaThread is a normal Java thread
1418
1419 void JavaThread::initialize() {
1420 // Initialize fields
1421
1422 set_saved_exception_pc(NULL);
1423 set_threadObj(NULL);
1424 _anchor.clear();
1425 set_entry_point(NULL);
1426 set_jni_functions(jni_functions());
1427 set_callee_target(NULL);
1428 set_vm_result(NULL);
1429 set_vm_result_2(NULL);
1430 set_vframe_array_head(NULL);
1431 set_vframe_array_last(NULL);
1432 set_deferred_locals(NULL);
1433 set_deopt_mark(NULL);
1434 set_deopt_compiled_method(NULL);
1435 clear_must_deopt_id();
1436 set_monitor_chunks(NULL);
1437 set_next(NULL);
1438 set_thread_state(_thread_new);
1439 _terminated = _not_terminated;
1440 _privileged_stack_top = NULL;
1441 _array_for_gc = NULL;
1442 _suspend_equivalent = false;
1443 _in_deopt_handler = 0;
1444 _doing_unsafe_access = false;
1445 _stack_guard_state = stack_guard_unused;
1446 #if INCLUDE_JVMCI
1447 _pending_monitorenter = false;
1448 _pending_deoptimization = -1;
1449 _pending_failed_speculation = NULL;
1450 _pending_transfer_to_interpreter = false;
1451 _adjusting_comp_level = false;
1452 _jvmci._alternate_call_target = NULL;
1453 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1454 if (JVMCICounterSize > 0) {
1455 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1456 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1457 } else {
1458 _jvmci_counters = NULL;
1459 }
1460 #endif // INCLUDE_JVMCI
1461 _reserved_stack_activation = NULL; // stack base not known yet
1462 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1463 _exception_pc = 0;
1464 _exception_handler_pc = 0;
1465 _is_method_handle_return = 0;
1466 _jvmti_thread_state= NULL;
1467 _should_post_on_exceptions_flag = JNI_FALSE;
1468 _jvmti_get_loaded_classes_closure = NULL;
1469 _interp_only_mode = 0;
1470 _special_runtime_exit_condition = _no_async_condition;
1471 _pending_async_exception = NULL;
1472 _thread_stat = NULL;
1473 _thread_stat = new ThreadStatistics();
1474 _blocked_on_compilation = false;
1475 _jni_active_critical = 0;
1476 _pending_jni_exception_check_fn = NULL;
1477 _do_not_unlock_if_synchronized = false;
1478 _cached_monitor_info = NULL;
1479 _parker = Parker::Allocate(this);
1480
1481 #ifndef PRODUCT
1482 _jmp_ring_index = 0;
1483 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1484 record_jump(NULL, NULL, NULL, 0);
1485 }
1486 #endif // PRODUCT
1487
1488 // Setup safepoint state info for this thread
1489 ThreadSafepointState::create(this);
1490
1491 debug_only(_java_call_counter = 0);
1492
1493 // JVMTI PopFrame support
1494 _popframe_condition = popframe_inactive;
1495 _popframe_preserved_args = NULL;
1496 _popframe_preserved_args_size = 0;
1497 _frames_to_pop_failed_realloc = 0;
1498
1499 if (SafepointMechanism::uses_thread_local_poll()) {
1500 SafepointMechanism::initialize_header(this);
1501 }
1502
1503 pd_initialize();
1504 }
1505
1506 #if INCLUDE_ALL_GCS
1507 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1508 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1509 #endif // INCLUDE_ALL_GCS
1510
1511 JavaThread::JavaThread(bool is_attaching_via_jni) :
1512 Thread()
1513 #if INCLUDE_ALL_GCS
1514 , _satb_mark_queue(&_satb_mark_queue_set),
1515 _dirty_card_queue(&_dirty_card_queue_set)
1516 #endif // INCLUDE_ALL_GCS
1517 {
1518 initialize();
1519 if (is_attaching_via_jni) {
1520 _jni_attach_state = _attaching_via_jni;
1521 } else {
1522 _jni_attach_state = _not_attaching_via_jni;
1523 }
1524 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1525 }
1526
1527 bool JavaThread::reguard_stack(address cur_sp) {
1528 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1529 && _stack_guard_state != stack_guard_reserved_disabled) {
1530 return true; // Stack already guarded or guard pages not needed.
1531 }
1532
1533 if (register_stack_overflow()) {
1534 // For those architectures which have separate register and
1535 // memory stacks, we must check the register stack to see if
1536 // it has overflowed.
1537 return false;
1538 }
1539
1540 // Java code never executes within the yellow zone: the latter is only
1541 // there to provoke an exception during stack banging. If java code
1542 // is executing there, either StackShadowPages should be larger, or
1543 // some exception code in c1, c2 or the interpreter isn't unwinding
1544 // when it should.
1545 guarantee(cur_sp > stack_reserved_zone_base(),
1546 "not enough space to reguard - increase StackShadowPages");
1547 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1548 enable_stack_yellow_reserved_zone();
1549 if (reserved_stack_activation() != stack_base()) {
1550 set_reserved_stack_activation(stack_base());
1551 }
1552 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1553 set_reserved_stack_activation(stack_base());
1554 enable_stack_reserved_zone();
1555 }
1556 return true;
1557 }
1558
1559 bool JavaThread::reguard_stack(void) {
1560 return reguard_stack(os::current_stack_pointer());
1561 }
1562
1563
1564 void JavaThread::block_if_vm_exited() {
1565 if (_terminated == _vm_exited) {
1566 // _vm_exited is set at safepoint, and Threads_lock is never released
1567 // we will block here forever
1568 Threads_lock->lock_without_safepoint_check();
1569 ShouldNotReachHere();
1570 }
1571 }
1572
1573
1574 // Remove this ifdef when C1 is ported to the compiler interface.
1575 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1576 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1577
1578 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1579 Thread()
1580 #if INCLUDE_ALL_GCS
1581 , _satb_mark_queue(&_satb_mark_queue_set),
1582 _dirty_card_queue(&_dirty_card_queue_set)
1583 #endif // INCLUDE_ALL_GCS
1584 {
1585 initialize();
1586 _jni_attach_state = _not_attaching_via_jni;
1587 set_entry_point(entry_point);
1588 // Create the native thread itself.
1589 // %note runtime_23
1590 os::ThreadType thr_type = os::java_thread;
1591 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1592 os::java_thread;
1593 os::create_thread(this, thr_type, stack_sz);
1594 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1595 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1596 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1597 // the exception consists of creating the exception object & initializing it, initialization
1598 // will leave the VM via a JavaCall and then all locks must be unlocked).
1599 //
1600 // The thread is still suspended when we reach here. Thread must be explicit started
1601 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1602 // by calling Threads:add. The reason why this is not done here, is because the thread
1603 // object must be fully initialized (take a look at JVM_Start)
1604 }
1605
1606 JavaThread::~JavaThread() {
1607
1608 // JSR166 -- return the parker to the free list
1609 Parker::Release(_parker);
1610 _parker = NULL;
1611
1612 // Free any remaining previous UnrollBlock
1613 vframeArray* old_array = vframe_array_last();
1614
1615 if (old_array != NULL) {
1616 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1617 old_array->set_unroll_block(NULL);
1618 delete old_info;
1619 delete old_array;
1620 }
1621
1622 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1623 if (deferred != NULL) {
1624 // This can only happen if thread is destroyed before deoptimization occurs.
1625 assert(deferred->length() != 0, "empty array!");
1626 do {
1627 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1628 deferred->remove_at(0);
1629 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1630 delete dlv;
1631 } while (deferred->length() != 0);
1632 delete deferred;
1633 }
1634
1635 // All Java related clean up happens in exit
1636 ThreadSafepointState::destroy(this);
1637 if (_thread_stat != NULL) delete _thread_stat;
1638
1639 #if INCLUDE_JVMCI
1640 if (JVMCICounterSize > 0) {
1641 if (jvmci_counters_include(this)) {
1642 for (int i = 0; i < JVMCICounterSize; i++) {
1643 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1644 }
1645 }
1646 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1647 }
1648 #endif // INCLUDE_JVMCI
1649 }
1650
1651
1652 // The first routine called by a new Java thread
1653 void JavaThread::run() {
1654 // initialize thread-local alloc buffer related fields
1655 this->initialize_tlab();
1656
1657 // used to test validity of stack trace backs
1658 this->record_base_of_stack_pointer();
1659
1660 // Record real stack base and size.
1661 this->record_stack_base_and_size();
1662
1663 this->create_stack_guard_pages();
1664
1665 this->cache_global_variables();
1666
1667 // Thread is now sufficient initialized to be handled by the safepoint code as being
1668 // in the VM. Change thread state from _thread_new to _thread_in_vm
1669 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1670
1671 assert(JavaThread::current() == this, "sanity check");
1672 assert(!Thread::current()->owns_locks(), "sanity check");
1673
1674 DTRACE_THREAD_PROBE(start, this);
1675
1676 // This operation might block. We call that after all safepoint checks for a new thread has
1677 // been completed.
1678 this->set_active_handles(JNIHandleBlock::allocate_block());
1679
1680 if (JvmtiExport::should_post_thread_life()) {
1681 JvmtiExport::post_thread_start(this);
1682 }
1683
1684 EventThreadStart event;
1685 if (event.should_commit()) {
1686 event.set_thread(THREAD_TRACE_ID(this));
1687 event.commit();
1688 }
1689
1690 // We call another function to do the rest so we are sure that the stack addresses used
1691 // from there will be lower than the stack base just computed
1692 thread_main_inner();
1693
1694 // Note, thread is no longer valid at this point!
1695 }
1696
1697
1698 void JavaThread::thread_main_inner() {
1699 assert(JavaThread::current() == this, "sanity check");
1700 assert(this->threadObj() != NULL, "just checking");
1701
1702 // Execute thread entry point unless this thread has a pending exception
1703 // or has been stopped before starting.
1704 // Note: Due to JVM_StopThread we can have pending exceptions already!
1705 if (!this->has_pending_exception() &&
1706 !java_lang_Thread::is_stillborn(this->threadObj())) {
1707 {
1708 ResourceMark rm(this);
1709 this->set_native_thread_name(this->get_thread_name());
1710 }
1711 HandleMark hm(this);
1712 this->entry_point()(this, this);
1713 }
1714
1715 DTRACE_THREAD_PROBE(stop, this);
1716
1717 this->exit(false);
1718 delete this;
1719 }
1720
1721
1722 static void ensure_join(JavaThread* thread) {
1723 // We do not need to grap the Threads_lock, since we are operating on ourself.
1724 Handle threadObj(thread, thread->threadObj());
1725 assert(threadObj.not_null(), "java thread object must exist");
1726 ObjectLocker lock(threadObj, thread);
1727 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1728 thread->clear_pending_exception();
1729 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1730 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1731 // Clear the native thread instance - this makes isAlive return false and allows the join()
1732 // to complete once we've done the notify_all below
1733 java_lang_Thread::set_thread(threadObj(), NULL);
1734 lock.notify_all(thread);
1735 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1736 thread->clear_pending_exception();
1737 }
1738
1739
1740 // For any new cleanup additions, please check to see if they need to be applied to
1741 // cleanup_failed_attach_current_thread as well.
1742 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1743 assert(this == JavaThread::current(), "thread consistency check");
1744
1745 HandleMark hm(this);
1746 Handle uncaught_exception(this, this->pending_exception());
1747 this->clear_pending_exception();
1748 Handle threadObj(this, this->threadObj());
1749 assert(threadObj.not_null(), "Java thread object should be created");
1750
1751 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1752 {
1753 EXCEPTION_MARK;
1754
1755 CLEAR_PENDING_EXCEPTION;
1756 }
1757 if (!destroy_vm) {
1758 if (uncaught_exception.not_null()) {
1759 EXCEPTION_MARK;
1760 // Call method Thread.dispatchUncaughtException().
1761 Klass* thread_klass = SystemDictionary::Thread_klass();
1762 JavaValue result(T_VOID);
1763 JavaCalls::call_virtual(&result,
1764 threadObj, thread_klass,
1765 vmSymbols::dispatchUncaughtException_name(),
1766 vmSymbols::throwable_void_signature(),
1767 uncaught_exception,
1768 THREAD);
1769 if (HAS_PENDING_EXCEPTION) {
1770 ResourceMark rm(this);
1771 jio_fprintf(defaultStream::error_stream(),
1772 "\nException: %s thrown from the UncaughtExceptionHandler"
1773 " in thread \"%s\"\n",
1774 pending_exception()->klass()->external_name(),
1775 get_thread_name());
1776 CLEAR_PENDING_EXCEPTION;
1777 }
1778 }
1779
1780 // Called before the java thread exit since we want to read info
1781 // from java_lang_Thread object
1782 EventThreadEnd event;
1783 if (event.should_commit()) {
1784 event.set_thread(THREAD_TRACE_ID(this));
1785 event.commit();
1786 }
1787
1788 // Call after last event on thread
1789 EVENT_THREAD_EXIT(this);
1790
1791 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1792 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1793 // is deprecated anyhow.
1794 if (!is_Compiler_thread()) {
1795 int count = 3;
1796 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1797 EXCEPTION_MARK;
1798 JavaValue result(T_VOID);
1799 Klass* thread_klass = SystemDictionary::Thread_klass();
1800 JavaCalls::call_virtual(&result,
1801 threadObj, thread_klass,
1802 vmSymbols::exit_method_name(),
1803 vmSymbols::void_method_signature(),
1804 THREAD);
1805 CLEAR_PENDING_EXCEPTION;
1806 }
1807 }
1808 // notify JVMTI
1809 if (JvmtiExport::should_post_thread_life()) {
1810 JvmtiExport::post_thread_end(this);
1811 }
1812
1813 // We have notified the agents that we are exiting, before we go on,
1814 // we must check for a pending external suspend request and honor it
1815 // in order to not surprise the thread that made the suspend request.
1816 while (true) {
1817 {
1818 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1819 if (!is_external_suspend()) {
1820 set_terminated(_thread_exiting);
1821 ThreadService::current_thread_exiting(this);
1822 break;
1823 }
1824 // Implied else:
1825 // Things get a little tricky here. We have a pending external
1826 // suspend request, but we are holding the SR_lock so we
1827 // can't just self-suspend. So we temporarily drop the lock
1828 // and then self-suspend.
1829 }
1830
1831 ThreadBlockInVM tbivm(this);
1832 java_suspend_self();
1833
1834 // We're done with this suspend request, but we have to loop around
1835 // and check again. Eventually we will get SR_lock without a pending
1836 // external suspend request and will be able to mark ourselves as
1837 // exiting.
1838 }
1839 // no more external suspends are allowed at this point
1840 } else {
1841 // before_exit() has already posted JVMTI THREAD_END events
1842 }
1843
1844 // Notify waiters on thread object. This has to be done after exit() is called
1845 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1846 // group should have the destroyed bit set before waiters are notified).
1847 ensure_join(this);
1848 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1849
1850 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1851 // held by this thread must be released. The spec does not distinguish
1852 // between JNI-acquired and regular Java monitors. We can only see
1853 // regular Java monitors here if monitor enter-exit matching is broken.
1854 //
1855 // Optionally release any monitors for regular JavaThread exits. This
1856 // is provided as a work around for any bugs in monitor enter-exit
1857 // matching. This can be expensive so it is not enabled by default.
1858 //
1859 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1860 // ObjectSynchronizer::release_monitors_owned_by_thread().
1861 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1862 // Sanity check even though JNI DetachCurrentThread() would have
1863 // returned JNI_ERR if there was a Java frame. JavaThread exit
1864 // should be done executing Java code by the time we get here.
1865 assert(!this->has_last_Java_frame(),
1866 "should not have a Java frame when detaching or exiting");
1867 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1868 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1869 }
1870
1871 // These things needs to be done while we are still a Java Thread. Make sure that thread
1872 // is in a consistent state, in case GC happens
1873 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1874
1875 if (active_handles() != NULL) {
1876 JNIHandleBlock* block = active_handles();
1877 set_active_handles(NULL);
1878 JNIHandleBlock::release_block(block);
1879 }
1880
1881 if (free_handle_block() != NULL) {
1882 JNIHandleBlock* block = free_handle_block();
1883 set_free_handle_block(NULL);
1884 JNIHandleBlock::release_block(block);
1885 }
1886
1887 // These have to be removed while this is still a valid thread.
1888 remove_stack_guard_pages();
1889
1890 if (UseTLAB) {
1891 tlab().make_parsable(true); // retire TLAB
1892 }
1893
1894 if (JvmtiEnv::environments_might_exist()) {
1895 JvmtiExport::cleanup_thread(this);
1896 }
1897
1898 // We must flush any deferred card marks before removing a thread from
1899 // the list of active threads.
1900 Universe::heap()->flush_deferred_store_barrier(this);
1901 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1902
1903 #if INCLUDE_ALL_GCS
1904 // We must flush the G1-related buffers before removing a thread
1905 // from the list of active threads. We must do this after any deferred
1906 // card marks have been flushed (above) so that any entries that are
1907 // added to the thread's dirty card queue as a result are not lost.
1908 if (UseG1GC) {
1909 flush_barrier_queues();
1910 }
1911 #endif // INCLUDE_ALL_GCS
1912
1913 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1914 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1915 os::current_thread_id());
1916
1917 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1918 Threads::remove(this);
1919
1920 // If someone set a handshake on us just as we entered exit path, we simple cancel it.
1921 if (ThreadLocalHandshakes) {
1922 cancel_handshake();
1923 }
1924 }
1925
1926 #if INCLUDE_ALL_GCS
1927 // Flush G1-related queues.
1928 void JavaThread::flush_barrier_queues() {
1929 satb_mark_queue().flush();
1930 dirty_card_queue().flush();
1931 }
1932
1933 void JavaThread::initialize_queues() {
1934 assert(!SafepointSynchronize::is_at_safepoint(),
1935 "we should not be at a safepoint");
1936
1937 SATBMarkQueue& satb_queue = satb_mark_queue();
1938 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1939 // The SATB queue should have been constructed with its active
1940 // field set to false.
1941 assert(!satb_queue.is_active(), "SATB queue should not be active");
1942 assert(satb_queue.is_empty(), "SATB queue should be empty");
1943 // If we are creating the thread during a marking cycle, we should
1944 // set the active field of the SATB queue to true.
1945 if (satb_queue_set.is_active()) {
1946 satb_queue.set_active(true);
1947 }
1948
1949 DirtyCardQueue& dirty_queue = dirty_card_queue();
1950 // The dirty card queue should have been constructed with its
1951 // active field set to true.
1952 assert(dirty_queue.is_active(), "dirty card queue should be active");
1953 }
1954 #endif // INCLUDE_ALL_GCS
1955
1956 void JavaThread::cleanup_failed_attach_current_thread() {
1957 if (active_handles() != NULL) {
1958 JNIHandleBlock* block = active_handles();
1959 set_active_handles(NULL);
1960 JNIHandleBlock::release_block(block);
1961 }
1962
1963 if (free_handle_block() != NULL) {
1964 JNIHandleBlock* block = free_handle_block();
1965 set_free_handle_block(NULL);
1966 JNIHandleBlock::release_block(block);
1967 }
1968
1969 // These have to be removed while this is still a valid thread.
1970 remove_stack_guard_pages();
1971
1972 if (UseTLAB) {
1973 tlab().make_parsable(true); // retire TLAB, if any
1974 }
1975
1976 #if INCLUDE_ALL_GCS
1977 if (UseG1GC) {
1978 flush_barrier_queues();
1979 }
1980 #endif // INCLUDE_ALL_GCS
1981
1982 Threads::remove(this);
1983 delete this;
1984 }
1985
1986
1987
1988
1989 JavaThread* JavaThread::active() {
1990 Thread* thread = Thread::current();
1991 if (thread->is_Java_thread()) {
1992 return (JavaThread*) thread;
1993 } else {
1994 assert(thread->is_VM_thread(), "this must be a vm thread");
1995 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1996 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1997 assert(ret->is_Java_thread(), "must be a Java thread");
1998 return ret;
1999 }
2000 }
2001
2002 bool JavaThread::is_lock_owned(address adr) const {
2003 if (Thread::is_lock_owned(adr)) return true;
2004
2005 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2006 if (chunk->contains(adr)) return true;
2007 }
2008
2009 return false;
2010 }
2011
2012
2013 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2014 chunk->set_next(monitor_chunks());
2015 set_monitor_chunks(chunk);
2016 }
2017
2018 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2019 guarantee(monitor_chunks() != NULL, "must be non empty");
2020 if (monitor_chunks() == chunk) {
2021 set_monitor_chunks(chunk->next());
2022 } else {
2023 MonitorChunk* prev = monitor_chunks();
2024 while (prev->next() != chunk) prev = prev->next();
2025 prev->set_next(chunk->next());
2026 }
2027 }
2028
2029 // JVM support.
2030
2031 // Note: this function shouldn't block if it's called in
2032 // _thread_in_native_trans state (such as from
2033 // check_special_condition_for_native_trans()).
2034 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2035
2036 if (has_last_Java_frame() && has_async_condition()) {
2037 // If we are at a polling page safepoint (not a poll return)
2038 // then we must defer async exception because live registers
2039 // will be clobbered by the exception path. Poll return is
2040 // ok because the call we a returning from already collides
2041 // with exception handling registers and so there is no issue.
2042 // (The exception handling path kills call result registers but
2043 // this is ok since the exception kills the result anyway).
2044
2045 if (is_at_poll_safepoint()) {
2046 // if the code we are returning to has deoptimized we must defer
2047 // the exception otherwise live registers get clobbered on the
2048 // exception path before deoptimization is able to retrieve them.
2049 //
2050 RegisterMap map(this, false);
2051 frame caller_fr = last_frame().sender(&map);
2052 assert(caller_fr.is_compiled_frame(), "what?");
2053 if (caller_fr.is_deoptimized_frame()) {
2054 log_info(exceptions)("deferred async exception at compiled safepoint");
2055 return;
2056 }
2057 }
2058 }
2059
2060 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2061 if (condition == _no_async_condition) {
2062 // Conditions have changed since has_special_runtime_exit_condition()
2063 // was called:
2064 // - if we were here only because of an external suspend request,
2065 // then that was taken care of above (or cancelled) so we are done
2066 // - if we were here because of another async request, then it has
2067 // been cleared between the has_special_runtime_exit_condition()
2068 // and now so again we are done
2069 return;
2070 }
2071
2072 // Check for pending async. exception
2073 if (_pending_async_exception != NULL) {
2074 // Only overwrite an already pending exception, if it is not a threadDeath.
2075 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2076
2077 // We cannot call Exceptions::_throw(...) here because we cannot block
2078 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2079
2080 LogTarget(Info, exceptions) lt;
2081 if (lt.is_enabled()) {
2082 ResourceMark rm;
2083 LogStream ls(lt);
2084 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2085 if (has_last_Java_frame()) {
2086 frame f = last_frame();
2087 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2088 }
2089 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2090 }
2091 _pending_async_exception = NULL;
2092 clear_has_async_exception();
2093 }
2094 }
2095
2096 if (check_unsafe_error &&
2097 condition == _async_unsafe_access_error && !has_pending_exception()) {
2098 condition = _no_async_condition; // done
2099 switch (thread_state()) {
2100 case _thread_in_vm: {
2101 JavaThread* THREAD = this;
2102 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2103 }
2104 case _thread_in_native: {
2105 ThreadInVMfromNative tiv(this);
2106 JavaThread* THREAD = this;
2107 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2108 }
2109 case _thread_in_Java: {
2110 ThreadInVMfromJava tiv(this);
2111 JavaThread* THREAD = this;
2112 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2113 }
2114 default:
2115 ShouldNotReachHere();
2116 }
2117 }
2118
2119 assert(condition == _no_async_condition || has_pending_exception() ||
2120 (!check_unsafe_error && condition == _async_unsafe_access_error),
2121 "must have handled the async condition, if no exception");
2122 }
2123
2124 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2125 //
2126 // Check for pending external suspend. Internal suspend requests do
2127 // not use handle_special_runtime_exit_condition().
2128 // If JNIEnv proxies are allowed, don't self-suspend if the target
2129 // thread is not the current thread. In older versions of jdbx, jdbx
2130 // threads could call into the VM with another thread's JNIEnv so we
2131 // can be here operating on behalf of a suspended thread (4432884).
2132 bool do_self_suspend = is_external_suspend_with_lock();
2133 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2134 //
2135 // Because thread is external suspended the safepoint code will count
2136 // thread as at a safepoint. This can be odd because we can be here
2137 // as _thread_in_Java which would normally transition to _thread_blocked
2138 // at a safepoint. We would like to mark the thread as _thread_blocked
2139 // before calling java_suspend_self like all other callers of it but
2140 // we must then observe proper safepoint protocol. (We can't leave
2141 // _thread_blocked with a safepoint in progress). However we can be
2142 // here as _thread_in_native_trans so we can't use a normal transition
2143 // constructor/destructor pair because they assert on that type of
2144 // transition. We could do something like:
2145 //
2146 // JavaThreadState state = thread_state();
2147 // set_thread_state(_thread_in_vm);
2148 // {
2149 // ThreadBlockInVM tbivm(this);
2150 // java_suspend_self()
2151 // }
2152 // set_thread_state(_thread_in_vm_trans);
2153 // if (safepoint) block;
2154 // set_thread_state(state);
2155 //
2156 // but that is pretty messy. Instead we just go with the way the
2157 // code has worked before and note that this is the only path to
2158 // java_suspend_self that doesn't put the thread in _thread_blocked
2159 // mode.
2160
2161 frame_anchor()->make_walkable(this);
2162 java_suspend_self();
2163
2164 // We might be here for reasons in addition to the self-suspend request
2165 // so check for other async requests.
2166 }
2167
2168 if (check_asyncs) {
2169 check_and_handle_async_exceptions();
2170 }
2171 #if INCLUDE_TRACE
2172 if (is_trace_suspend()) {
2173 TRACE_SUSPEND_THREAD(this);
2174 }
2175 #endif
2176 }
2177
2178 void JavaThread::send_thread_stop(oop java_throwable) {
2179 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2180 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2181 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2182
2183 // Do not throw asynchronous exceptions against the compiler thread
2184 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2185 if (!can_call_java()) return;
2186
2187 {
2188 // Actually throw the Throwable against the target Thread - however
2189 // only if there is no thread death exception installed already.
2190 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2191 // If the topmost frame is a runtime stub, then we are calling into
2192 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2193 // must deoptimize the caller before continuing, as the compiled exception handler table
2194 // may not be valid
2195 if (has_last_Java_frame()) {
2196 frame f = last_frame();
2197 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2198 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2199 RegisterMap reg_map(this, UseBiasedLocking);
2200 frame compiled_frame = f.sender(®_map);
2201 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2202 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2203 }
2204 }
2205 }
2206
2207 // Set async. pending exception in thread.
2208 set_pending_async_exception(java_throwable);
2209
2210 if (log_is_enabled(Info, exceptions)) {
2211 ResourceMark rm;
2212 log_info(exceptions)("Pending Async. exception installed of type: %s",
2213 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2214 }
2215 // for AbortVMOnException flag
2216 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2217 }
2218 }
2219
2220
2221 // Interrupt thread so it will wake up from a potential wait()
2222 Thread::interrupt(this);
2223 }
2224
2225 // External suspension mechanism.
2226 //
2227 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2228 // to any VM_locks and it is at a transition
2229 // Self-suspension will happen on the transition out of the vm.
2230 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2231 //
2232 // Guarantees on return:
2233 // + Target thread will not execute any new bytecode (that's why we need to
2234 // force a safepoint)
2235 // + Target thread will not enter any new monitors
2236 //
2237 void JavaThread::java_suspend() {
2238 { MutexLocker mu(Threads_lock);
2239 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2240 return;
2241 }
2242 }
2243
2244 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2245 if (!is_external_suspend()) {
2246 // a racing resume has cancelled us; bail out now
2247 return;
2248 }
2249
2250 // suspend is done
2251 uint32_t debug_bits = 0;
2252 // Warning: is_ext_suspend_completed() may temporarily drop the
2253 // SR_lock to allow the thread to reach a stable thread state if
2254 // it is currently in a transient thread state.
2255 if (is_ext_suspend_completed(false /* !called_by_wait */,
2256 SuspendRetryDelay, &debug_bits)) {
2257 return;
2258 }
2259 }
2260
2261 VM_ThreadSuspend vm_suspend;
2262 VMThread::execute(&vm_suspend);
2263 }
2264
2265 // Part II of external suspension.
2266 // A JavaThread self suspends when it detects a pending external suspend
2267 // request. This is usually on transitions. It is also done in places
2268 // where continuing to the next transition would surprise the caller,
2269 // e.g., monitor entry.
2270 //
2271 // Returns the number of times that the thread self-suspended.
2272 //
2273 // Note: DO NOT call java_suspend_self() when you just want to block current
2274 // thread. java_suspend_self() is the second stage of cooperative
2275 // suspension for external suspend requests and should only be used
2276 // to complete an external suspend request.
2277 //
2278 int JavaThread::java_suspend_self() {
2279 int ret = 0;
2280
2281 // we are in the process of exiting so don't suspend
2282 if (is_exiting()) {
2283 clear_external_suspend();
2284 return ret;
2285 }
2286
2287 assert(_anchor.walkable() ||
2288 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2289 "must have walkable stack");
2290
2291 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2292
2293 assert(!this->is_ext_suspended(),
2294 "a thread trying to self-suspend should not already be suspended");
2295
2296 if (this->is_suspend_equivalent()) {
2297 // If we are self-suspending as a result of the lifting of a
2298 // suspend equivalent condition, then the suspend_equivalent
2299 // flag is not cleared until we set the ext_suspended flag so
2300 // that wait_for_ext_suspend_completion() returns consistent
2301 // results.
2302 this->clear_suspend_equivalent();
2303 }
2304
2305 // A racing resume may have cancelled us before we grabbed SR_lock
2306 // above. Or another external suspend request could be waiting for us
2307 // by the time we return from SR_lock()->wait(). The thread
2308 // that requested the suspension may already be trying to walk our
2309 // stack and if we return now, we can change the stack out from under
2310 // it. This would be a "bad thing (TM)" and cause the stack walker
2311 // to crash. We stay self-suspended until there are no more pending
2312 // external suspend requests.
2313 while (is_external_suspend()) {
2314 ret++;
2315 this->set_ext_suspended();
2316
2317 // _ext_suspended flag is cleared by java_resume()
2318 while (is_ext_suspended()) {
2319 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2320 }
2321 }
2322
2323 return ret;
2324 }
2325
2326 #ifdef ASSERT
2327 // verify the JavaThread has not yet been published in the Threads::list, and
2328 // hence doesn't need protection from concurrent access at this stage
2329 void JavaThread::verify_not_published() {
2330 if (!Threads_lock->owned_by_self()) {
2331 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2332 assert(!Threads::includes(this),
2333 "java thread shouldn't have been published yet!");
2334 } else {
2335 assert(!Threads::includes(this),
2336 "java thread shouldn't have been published yet!");
2337 }
2338 }
2339 #endif
2340
2341 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2342 // progress or when _suspend_flags is non-zero.
2343 // Current thread needs to self-suspend if there is a suspend request and/or
2344 // block if a safepoint is in progress.
2345 // Async exception ISN'T checked.
2346 // Note only the ThreadInVMfromNative transition can call this function
2347 // directly and when thread state is _thread_in_native_trans
2348 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2349 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2350
2351 JavaThread *curJT = JavaThread::current();
2352 bool do_self_suspend = thread->is_external_suspend();
2353
2354 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2355
2356 // If JNIEnv proxies are allowed, don't self-suspend if the target
2357 // thread is not the current thread. In older versions of jdbx, jdbx
2358 // threads could call into the VM with another thread's JNIEnv so we
2359 // can be here operating on behalf of a suspended thread (4432884).
2360 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2361 JavaThreadState state = thread->thread_state();
2362
2363 // We mark this thread_blocked state as a suspend-equivalent so
2364 // that a caller to is_ext_suspend_completed() won't be confused.
2365 // The suspend-equivalent state is cleared by java_suspend_self().
2366 thread->set_suspend_equivalent();
2367
2368 // If the safepoint code sees the _thread_in_native_trans state, it will
2369 // wait until the thread changes to other thread state. There is no
2370 // guarantee on how soon we can obtain the SR_lock and complete the
2371 // self-suspend request. It would be a bad idea to let safepoint wait for
2372 // too long. Temporarily change the state to _thread_blocked to
2373 // let the VM thread know that this thread is ready for GC. The problem
2374 // of changing thread state is that safepoint could happen just after
2375 // java_suspend_self() returns after being resumed, and VM thread will
2376 // see the _thread_blocked state. We must check for safepoint
2377 // after restoring the state and make sure we won't leave while a safepoint
2378 // is in progress.
2379 thread->set_thread_state(_thread_blocked);
2380 thread->java_suspend_self();
2381 thread->set_thread_state(state);
2382
2383 InterfaceSupport::serialize_thread_state_with_handler(thread);
2384 }
2385
2386 SafepointMechanism::block_if_requested(curJT);
2387
2388 if (thread->is_deopt_suspend()) {
2389 thread->clear_deopt_suspend();
2390 RegisterMap map(thread, false);
2391 frame f = thread->last_frame();
2392 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2393 f = f.sender(&map);
2394 }
2395 if (f.id() == thread->must_deopt_id()) {
2396 thread->clear_must_deopt_id();
2397 f.deoptimize(thread);
2398 } else {
2399 fatal("missed deoptimization!");
2400 }
2401 }
2402 #if INCLUDE_TRACE
2403 if (thread->is_trace_suspend()) {
2404 TRACE_SUSPEND_THREAD(thread);
2405 }
2406 #endif
2407 }
2408
2409 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2410 // progress or when _suspend_flags is non-zero.
2411 // Current thread needs to self-suspend if there is a suspend request and/or
2412 // block if a safepoint is in progress.
2413 // Also check for pending async exception (not including unsafe access error).
2414 // Note only the native==>VM/Java barriers can call this function and when
2415 // thread state is _thread_in_native_trans.
2416 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2417 check_safepoint_and_suspend_for_native_trans(thread);
2418
2419 if (thread->has_async_exception()) {
2420 // We are in _thread_in_native_trans state, don't handle unsafe
2421 // access error since that may block.
2422 thread->check_and_handle_async_exceptions(false);
2423 }
2424 }
2425
2426 // This is a variant of the normal
2427 // check_special_condition_for_native_trans with slightly different
2428 // semantics for use by critical native wrappers. It does all the
2429 // normal checks but also performs the transition back into
2430 // thread_in_Java state. This is required so that critical natives
2431 // can potentially block and perform a GC if they are the last thread
2432 // exiting the GCLocker.
2433 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2434 check_special_condition_for_native_trans(thread);
2435
2436 // Finish the transition
2437 thread->set_thread_state(_thread_in_Java);
2438
2439 if (thread->do_critical_native_unlock()) {
2440 ThreadInVMfromJavaNoAsyncException tiv(thread);
2441 GCLocker::unlock_critical(thread);
2442 thread->clear_critical_native_unlock();
2443 }
2444 }
2445
2446 // We need to guarantee the Threads_lock here, since resumes are not
2447 // allowed during safepoint synchronization
2448 // Can only resume from an external suspension
2449 void JavaThread::java_resume() {
2450 assert_locked_or_safepoint(Threads_lock);
2451
2452 // Sanity check: thread is gone, has started exiting or the thread
2453 // was not externally suspended.
2454 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2455 return;
2456 }
2457
2458 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2459
2460 clear_external_suspend();
2461
2462 if (is_ext_suspended()) {
2463 clear_ext_suspended();
2464 SR_lock()->notify_all();
2465 }
2466 }
2467
2468 size_t JavaThread::_stack_red_zone_size = 0;
2469 size_t JavaThread::_stack_yellow_zone_size = 0;
2470 size_t JavaThread::_stack_reserved_zone_size = 0;
2471 size_t JavaThread::_stack_shadow_zone_size = 0;
2472
2473 void JavaThread::create_stack_guard_pages() {
2474 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2475 address low_addr = stack_end();
2476 size_t len = stack_guard_zone_size();
2477
2478 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2479 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2480
2481 int must_commit = os::must_commit_stack_guard_pages();
2482 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2483
2484 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2485 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2486 return;
2487 }
2488
2489 if (os::guard_memory((char *) low_addr, len)) {
2490 _stack_guard_state = stack_guard_enabled;
2491 } else {
2492 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2493 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2494 if (os::uncommit_memory((char *) low_addr, len)) {
2495 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2496 }
2497 return;
2498 }
2499
2500 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2501 PTR_FORMAT "-" PTR_FORMAT ".",
2502 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2503 }
2504
2505 void JavaThread::remove_stack_guard_pages() {
2506 assert(Thread::current() == this, "from different thread");
2507 if (_stack_guard_state == stack_guard_unused) return;
2508 address low_addr = stack_end();
2509 size_t len = stack_guard_zone_size();
2510
2511 if (os::must_commit_stack_guard_pages()) {
2512 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2513 _stack_guard_state = stack_guard_unused;
2514 } else {
2515 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2516 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2517 return;
2518 }
2519 } else {
2520 if (_stack_guard_state == stack_guard_unused) return;
2521 if (os::unguard_memory((char *) low_addr, len)) {
2522 _stack_guard_state = stack_guard_unused;
2523 } else {
2524 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2525 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2526 return;
2527 }
2528 }
2529
2530 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2531 PTR_FORMAT "-" PTR_FORMAT ".",
2532 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2533 }
2534
2535 void JavaThread::enable_stack_reserved_zone() {
2536 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2537 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2538
2539 // The base notation is from the stack's point of view, growing downward.
2540 // We need to adjust it to work correctly with guard_memory()
2541 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2542
2543 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2544 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2545
2546 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2547 _stack_guard_state = stack_guard_enabled;
2548 } else {
2549 warning("Attempt to guard stack reserved zone failed.");
2550 }
2551 enable_register_stack_guard();
2552 }
2553
2554 void JavaThread::disable_stack_reserved_zone() {
2555 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2556 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2557
2558 // Simply return if called for a thread that does not use guard pages.
2559 if (_stack_guard_state == stack_guard_unused) return;
2560
2561 // The base notation is from the stack's point of view, growing downward.
2562 // We need to adjust it to work correctly with guard_memory()
2563 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2564
2565 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2566 _stack_guard_state = stack_guard_reserved_disabled;
2567 } else {
2568 warning("Attempt to unguard stack reserved zone failed.");
2569 }
2570 disable_register_stack_guard();
2571 }
2572
2573 void JavaThread::enable_stack_yellow_reserved_zone() {
2574 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2575 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2576
2577 // The base notation is from the stacks point of view, growing downward.
2578 // We need to adjust it to work correctly with guard_memory()
2579 address base = stack_red_zone_base();
2580
2581 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2582 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2583
2584 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2585 _stack_guard_state = stack_guard_enabled;
2586 } else {
2587 warning("Attempt to guard stack yellow zone failed.");
2588 }
2589 enable_register_stack_guard();
2590 }
2591
2592 void JavaThread::disable_stack_yellow_reserved_zone() {
2593 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2594 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2595
2596 // Simply return if called for a thread that does not use guard pages.
2597 if (_stack_guard_state == stack_guard_unused) return;
2598
2599 // The base notation is from the stacks point of view, growing downward.
2600 // We need to adjust it to work correctly with guard_memory()
2601 address base = stack_red_zone_base();
2602
2603 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2604 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2605 } else {
2606 warning("Attempt to unguard stack yellow zone failed.");
2607 }
2608 disable_register_stack_guard();
2609 }
2610
2611 void JavaThread::enable_stack_red_zone() {
2612 // The base notation is from the stacks point of view, growing downward.
2613 // We need to adjust it to work correctly with guard_memory()
2614 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2615 address base = stack_red_zone_base() - stack_red_zone_size();
2616
2617 guarantee(base < stack_base(), "Error calculating stack red zone");
2618 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2619
2620 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2621 warning("Attempt to guard stack red zone failed.");
2622 }
2623 }
2624
2625 void JavaThread::disable_stack_red_zone() {
2626 // The base notation is from the stacks point of view, growing downward.
2627 // We need to adjust it to work correctly with guard_memory()
2628 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2629 address base = stack_red_zone_base() - stack_red_zone_size();
2630 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2631 warning("Attempt to unguard stack red zone failed.");
2632 }
2633 }
2634
2635 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2636 // ignore is there is no stack
2637 if (!has_last_Java_frame()) return;
2638 // traverse the stack frames. Starts from top frame.
2639 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2640 frame* fr = fst.current();
2641 f(fr, fst.register_map());
2642 }
2643 }
2644
2645
2646 #ifndef PRODUCT
2647 // Deoptimization
2648 // Function for testing deoptimization
2649 void JavaThread::deoptimize() {
2650 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2651 StackFrameStream fst(this, UseBiasedLocking);
2652 bool deopt = false; // Dump stack only if a deopt actually happens.
2653 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2654 // Iterate over all frames in the thread and deoptimize
2655 for (; !fst.is_done(); fst.next()) {
2656 if (fst.current()->can_be_deoptimized()) {
2657
2658 if (only_at) {
2659 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2660 // consists of comma or carriage return separated numbers so
2661 // search for the current bci in that string.
2662 address pc = fst.current()->pc();
2663 nmethod* nm = (nmethod*) fst.current()->cb();
2664 ScopeDesc* sd = nm->scope_desc_at(pc);
2665 char buffer[8];
2666 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2667 size_t len = strlen(buffer);
2668 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2669 while (found != NULL) {
2670 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2671 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2672 // Check that the bci found is bracketed by terminators.
2673 break;
2674 }
2675 found = strstr(found + 1, buffer);
2676 }
2677 if (!found) {
2678 continue;
2679 }
2680 }
2681
2682 if (DebugDeoptimization && !deopt) {
2683 deopt = true; // One-time only print before deopt
2684 tty->print_cr("[BEFORE Deoptimization]");
2685 trace_frames();
2686 trace_stack();
2687 }
2688 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2689 }
2690 }
2691
2692 if (DebugDeoptimization && deopt) {
2693 tty->print_cr("[AFTER Deoptimization]");
2694 trace_frames();
2695 }
2696 }
2697
2698
2699 // Make zombies
2700 void JavaThread::make_zombies() {
2701 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2702 if (fst.current()->can_be_deoptimized()) {
2703 // it is a Java nmethod
2704 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2705 nm->make_not_entrant();
2706 }
2707 }
2708 }
2709 #endif // PRODUCT
2710
2711
2712 void JavaThread::deoptimized_wrt_marked_nmethods() {
2713 if (!has_last_Java_frame()) return;
2714 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2715 StackFrameStream fst(this, UseBiasedLocking);
2716 for (; !fst.is_done(); fst.next()) {
2717 if (fst.current()->should_be_deoptimized()) {
2718 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2719 }
2720 }
2721 }
2722
2723
2724 // If the caller is a NamedThread, then remember, in the current scope,
2725 // the given JavaThread in its _processed_thread field.
2726 class RememberProcessedThread: public StackObj {
2727 NamedThread* _cur_thr;
2728 public:
2729 RememberProcessedThread(JavaThread* jthr) {
2730 Thread* thread = Thread::current();
2731 if (thread->is_Named_thread()) {
2732 _cur_thr = (NamedThread *)thread;
2733 _cur_thr->set_processed_thread(jthr);
2734 } else {
2735 _cur_thr = NULL;
2736 }
2737 }
2738
2739 ~RememberProcessedThread() {
2740 if (_cur_thr) {
2741 _cur_thr->set_processed_thread(NULL);
2742 }
2743 }
2744 };
2745
2746 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2747 // Verify that the deferred card marks have been flushed.
2748 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2749
2750 // Traverse the GCHandles
2751 Thread::oops_do(f, cf);
2752
2753 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2754
2755 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2756 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2757
2758 if (has_last_Java_frame()) {
2759 // Record JavaThread to GC thread
2760 RememberProcessedThread rpt(this);
2761
2762 // Traverse the privileged stack
2763 if (_privileged_stack_top != NULL) {
2764 _privileged_stack_top->oops_do(f);
2765 }
2766
2767 // traverse the registered growable array
2768 if (_array_for_gc != NULL) {
2769 for (int index = 0; index < _array_for_gc->length(); index++) {
2770 f->do_oop(_array_for_gc->adr_at(index));
2771 }
2772 }
2773
2774 // Traverse the monitor chunks
2775 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2776 chunk->oops_do(f);
2777 }
2778
2779 // Traverse the execution stack
2780 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2781 fst.current()->oops_do(f, cf, fst.register_map());
2782 }
2783 }
2784
2785 // callee_target is never live across a gc point so NULL it here should
2786 // it still contain a methdOop.
2787
2788 set_callee_target(NULL);
2789
2790 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2791 // If we have deferred set_locals there might be oops waiting to be
2792 // written
2793 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2794 if (list != NULL) {
2795 for (int i = 0; i < list->length(); i++) {
2796 list->at(i)->oops_do(f);
2797 }
2798 }
2799
2800 // Traverse instance variables at the end since the GC may be moving things
2801 // around using this function
2802 f->do_oop((oop*) &_threadObj);
2803 f->do_oop((oop*) &_vm_result);
2804 f->do_oop((oop*) &_exception_oop);
2805 f->do_oop((oop*) &_pending_async_exception);
2806
2807 if (jvmti_thread_state() != NULL) {
2808 jvmti_thread_state()->oops_do(f);
2809 }
2810 }
2811
2812 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2813 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2814 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2815
2816 if (has_last_Java_frame()) {
2817 // Traverse the execution stack
2818 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2819 fst.current()->nmethods_do(cf);
2820 }
2821 }
2822 }
2823
2824 void JavaThread::metadata_do(void f(Metadata*)) {
2825 if (has_last_Java_frame()) {
2826 // Traverse the execution stack to call f() on the methods in the stack
2827 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2828 fst.current()->metadata_do(f);
2829 }
2830 } else if (is_Compiler_thread()) {
2831 // need to walk ciMetadata in current compile tasks to keep alive.
2832 CompilerThread* ct = (CompilerThread*)this;
2833 if (ct->env() != NULL) {
2834 ct->env()->metadata_do(f);
2835 }
2836 if (ct->task() != NULL) {
2837 ct->task()->metadata_do(f);
2838 }
2839 }
2840 }
2841
2842 // Printing
2843 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2844 switch (_thread_state) {
2845 case _thread_uninitialized: return "_thread_uninitialized";
2846 case _thread_new: return "_thread_new";
2847 case _thread_new_trans: return "_thread_new_trans";
2848 case _thread_in_native: return "_thread_in_native";
2849 case _thread_in_native_trans: return "_thread_in_native_trans";
2850 case _thread_in_vm: return "_thread_in_vm";
2851 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2852 case _thread_in_Java: return "_thread_in_Java";
2853 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2854 case _thread_blocked: return "_thread_blocked";
2855 case _thread_blocked_trans: return "_thread_blocked_trans";
2856 default: return "unknown thread state";
2857 }
2858 }
2859
2860 #ifndef PRODUCT
2861 void JavaThread::print_thread_state_on(outputStream *st) const {
2862 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2863 };
2864 void JavaThread::print_thread_state() const {
2865 print_thread_state_on(tty);
2866 }
2867 #endif // PRODUCT
2868
2869 // Called by Threads::print() for VM_PrintThreads operation
2870 void JavaThread::print_on(outputStream *st) const {
2871 st->print_raw("\"");
2872 st->print_raw(get_thread_name());
2873 st->print_raw("\" ");
2874 oop thread_oop = threadObj();
2875 if (thread_oop != NULL) {
2876 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2877 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2878 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2879 }
2880 Thread::print_on(st);
2881 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2882 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2883 if (thread_oop != NULL) {
2884 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2885 }
2886 #ifndef PRODUCT
2887 print_thread_state_on(st);
2888 _safepoint_state->print_on(st);
2889 #endif // PRODUCT
2890 if (is_Compiler_thread()) {
2891 CompilerThread* ct = (CompilerThread*)this;
2892 if (ct->task() != NULL) {
2893 st->print(" Compiling: ");
2894 ct->task()->print(st, NULL, true, false);
2895 } else {
2896 st->print(" No compile task");
2897 }
2898 st->cr();
2899 }
2900 }
2901
2902 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2903 st->print("%s", get_thread_name_string(buf, buflen));
2904 }
2905
2906 // Called by fatal error handler. The difference between this and
2907 // JavaThread::print() is that we can't grab lock or allocate memory.
2908 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2909 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2910 oop thread_obj = threadObj();
2911 if (thread_obj != NULL) {
2912 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2913 }
2914 st->print(" [");
2915 st->print("%s", _get_thread_state_name(_thread_state));
2916 if (osthread()) {
2917 st->print(", id=%d", osthread()->thread_id());
2918 }
2919 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2920 p2i(stack_end()), p2i(stack_base()));
2921 st->print("]");
2922 return;
2923 }
2924
2925 // Verification
2926
2927 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2928
2929 void JavaThread::verify() {
2930 // Verify oops in the thread.
2931 oops_do(&VerifyOopClosure::verify_oop, NULL);
2932
2933 // Verify the stack frames.
2934 frames_do(frame_verify);
2935 }
2936
2937 // CR 6300358 (sub-CR 2137150)
2938 // Most callers of this method assume that it can't return NULL but a
2939 // thread may not have a name whilst it is in the process of attaching to
2940 // the VM - see CR 6412693, and there are places where a JavaThread can be
2941 // seen prior to having it's threadObj set (eg JNI attaching threads and
2942 // if vm exit occurs during initialization). These cases can all be accounted
2943 // for such that this method never returns NULL.
2944 const char* JavaThread::get_thread_name() const {
2945 #ifdef ASSERT
2946 // early safepoints can hit while current thread does not yet have TLS
2947 if (!SafepointSynchronize::is_at_safepoint()) {
2948 Thread *cur = Thread::current();
2949 if (!(cur->is_Java_thread() && cur == this)) {
2950 // Current JavaThreads are allowed to get their own name without
2951 // the Threads_lock.
2952 assert_locked_or_safepoint(Threads_lock);
2953 }
2954 }
2955 #endif // ASSERT
2956 return get_thread_name_string();
2957 }
2958
2959 // Returns a non-NULL representation of this thread's name, or a suitable
2960 // descriptive string if there is no set name
2961 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2962 const char* name_str;
2963 oop thread_obj = threadObj();
2964 if (thread_obj != NULL) {
2965 oop name = java_lang_Thread::name(thread_obj);
2966 if (name != NULL) {
2967 if (buf == NULL) {
2968 name_str = java_lang_String::as_utf8_string(name);
2969 } else {
2970 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2971 }
2972 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2973 name_str = "<no-name - thread is attaching>";
2974 } else {
2975 name_str = Thread::name();
2976 }
2977 } else {
2978 name_str = Thread::name();
2979 }
2980 assert(name_str != NULL, "unexpected NULL thread name");
2981 return name_str;
2982 }
2983
2984
2985 const char* JavaThread::get_threadgroup_name() const {
2986 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2987 oop thread_obj = threadObj();
2988 if (thread_obj != NULL) {
2989 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2990 if (thread_group != NULL) {
2991 // ThreadGroup.name can be null
2992 return java_lang_ThreadGroup::name(thread_group);
2993 }
2994 }
2995 return NULL;
2996 }
2997
2998 const char* JavaThread::get_parent_name() const {
2999 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3000 oop thread_obj = threadObj();
3001 if (thread_obj != NULL) {
3002 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3003 if (thread_group != NULL) {
3004 oop parent = java_lang_ThreadGroup::parent(thread_group);
3005 if (parent != NULL) {
3006 // ThreadGroup.name can be null
3007 return java_lang_ThreadGroup::name(parent);
3008 }
3009 }
3010 }
3011 return NULL;
3012 }
3013
3014 ThreadPriority JavaThread::java_priority() const {
3015 oop thr_oop = threadObj();
3016 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3017 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3018 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3019 return priority;
3020 }
3021
3022 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3023
3024 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3025 // Link Java Thread object <-> C++ Thread
3026
3027 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3028 // and put it into a new Handle. The Handle "thread_oop" can then
3029 // be used to pass the C++ thread object to other methods.
3030
3031 // Set the Java level thread object (jthread) field of the
3032 // new thread (a JavaThread *) to C++ thread object using the
3033 // "thread_oop" handle.
3034
3035 // Set the thread field (a JavaThread *) of the
3036 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3037
3038 Handle thread_oop(Thread::current(),
3039 JNIHandles::resolve_non_null(jni_thread));
3040 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3041 "must be initialized");
3042 set_threadObj(thread_oop());
3043 java_lang_Thread::set_thread(thread_oop(), this);
3044
3045 if (prio == NoPriority) {
3046 prio = java_lang_Thread::priority(thread_oop());
3047 assert(prio != NoPriority, "A valid priority should be present");
3048 }
3049
3050 // Push the Java priority down to the native thread; needs Threads_lock
3051 Thread::set_priority(this, prio);
3052
3053 prepare_ext();
3054
3055 // Add the new thread to the Threads list and set it in motion.
3056 // We must have threads lock in order to call Threads::add.
3057 // It is crucial that we do not block before the thread is
3058 // added to the Threads list for if a GC happens, then the java_thread oop
3059 // will not be visited by GC.
3060 Threads::add(this);
3061 }
3062
3063 oop JavaThread::current_park_blocker() {
3064 // Support for JSR-166 locks
3065 oop thread_oop = threadObj();
3066 if (thread_oop != NULL &&
3067 JDK_Version::current().supports_thread_park_blocker()) {
3068 return java_lang_Thread::park_blocker(thread_oop);
3069 }
3070 return NULL;
3071 }
3072
3073
3074 void JavaThread::print_stack_on(outputStream* st) {
3075 if (!has_last_Java_frame()) return;
3076 ResourceMark rm;
3077 HandleMark hm;
3078
3079 RegisterMap reg_map(this);
3080 vframe* start_vf = last_java_vframe(®_map);
3081 int count = 0;
3082 for (vframe* f = start_vf; f; f = f->sender()) {
3083 if (f->is_java_frame()) {
3084 javaVFrame* jvf = javaVFrame::cast(f);
3085 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3086
3087 // Print out lock information
3088 if (JavaMonitorsInStackTrace) {
3089 jvf->print_lock_info_on(st, count);
3090 }
3091 } else {
3092 // Ignore non-Java frames
3093 }
3094
3095 // Bail-out case for too deep stacks
3096 count++;
3097 if (MaxJavaStackTraceDepth == count) return;
3098 }
3099 }
3100
3101
3102 // JVMTI PopFrame support
3103 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3104 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3105 if (in_bytes(size_in_bytes) != 0) {
3106 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3107 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3108 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3109 }
3110 }
3111
3112 void* JavaThread::popframe_preserved_args() {
3113 return _popframe_preserved_args;
3114 }
3115
3116 ByteSize JavaThread::popframe_preserved_args_size() {
3117 return in_ByteSize(_popframe_preserved_args_size);
3118 }
3119
3120 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3121 int sz = in_bytes(popframe_preserved_args_size());
3122 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3123 return in_WordSize(sz / wordSize);
3124 }
3125
3126 void JavaThread::popframe_free_preserved_args() {
3127 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3128 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3129 _popframe_preserved_args = NULL;
3130 _popframe_preserved_args_size = 0;
3131 }
3132
3133 #ifndef PRODUCT
3134
3135 void JavaThread::trace_frames() {
3136 tty->print_cr("[Describe stack]");
3137 int frame_no = 1;
3138 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3139 tty->print(" %d. ", frame_no++);
3140 fst.current()->print_value_on(tty, this);
3141 tty->cr();
3142 }
3143 }
3144
3145 class PrintAndVerifyOopClosure: public OopClosure {
3146 protected:
3147 template <class T> inline void do_oop_work(T* p) {
3148 oop obj = oopDesc::load_decode_heap_oop(p);
3149 if (obj == NULL) return;
3150 tty->print(INTPTR_FORMAT ": ", p2i(p));
3151 if (oopDesc::is_oop_or_null(obj)) {
3152 if (obj->is_objArray()) {
3153 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3154 } else {
3155 obj->print();
3156 }
3157 } else {
3158 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3159 }
3160 tty->cr();
3161 }
3162 public:
3163 virtual void do_oop(oop* p) { do_oop_work(p); }
3164 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3165 };
3166
3167
3168 static void oops_print(frame* f, const RegisterMap *map) {
3169 PrintAndVerifyOopClosure print;
3170 f->print_value();
3171 f->oops_do(&print, NULL, (RegisterMap*)map);
3172 }
3173
3174 // Print our all the locations that contain oops and whether they are
3175 // valid or not. This useful when trying to find the oldest frame
3176 // where an oop has gone bad since the frame walk is from youngest to
3177 // oldest.
3178 void JavaThread::trace_oops() {
3179 tty->print_cr("[Trace oops]");
3180 frames_do(oops_print);
3181 }
3182
3183
3184 #ifdef ASSERT
3185 // Print or validate the layout of stack frames
3186 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3187 ResourceMark rm;
3188 PRESERVE_EXCEPTION_MARK;
3189 FrameValues values;
3190 int frame_no = 0;
3191 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3192 fst.current()->describe(values, ++frame_no);
3193 if (depth == frame_no) break;
3194 }
3195 if (validate_only) {
3196 values.validate();
3197 } else {
3198 tty->print_cr("[Describe stack layout]");
3199 values.print(this);
3200 }
3201 }
3202 #endif
3203
3204 void JavaThread::trace_stack_from(vframe* start_vf) {
3205 ResourceMark rm;
3206 int vframe_no = 1;
3207 for (vframe* f = start_vf; f; f = f->sender()) {
3208 if (f->is_java_frame()) {
3209 javaVFrame::cast(f)->print_activation(vframe_no++);
3210 } else {
3211 f->print();
3212 }
3213 if (vframe_no > StackPrintLimit) {
3214 tty->print_cr("...<more frames>...");
3215 return;
3216 }
3217 }
3218 }
3219
3220
3221 void JavaThread::trace_stack() {
3222 if (!has_last_Java_frame()) return;
3223 ResourceMark rm;
3224 HandleMark hm;
3225 RegisterMap reg_map(this);
3226 trace_stack_from(last_java_vframe(®_map));
3227 }
3228
3229
3230 #endif // PRODUCT
3231
3232
3233 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3234 assert(reg_map != NULL, "a map must be given");
3235 frame f = last_frame();
3236 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3237 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3238 }
3239 return NULL;
3240 }
3241
3242
3243 Klass* JavaThread::security_get_caller_class(int depth) {
3244 vframeStream vfst(this);
3245 vfst.security_get_caller_frame(depth);
3246 if (!vfst.at_end()) {
3247 return vfst.method()->method_holder();
3248 }
3249 return NULL;
3250 }
3251
3252 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3253 assert(thread->is_Compiler_thread(), "must be compiler thread");
3254 CompileBroker::compiler_thread_loop();
3255 }
3256
3257 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3258 NMethodSweeper::sweeper_loop();
3259 }
3260
3261 // Create a CompilerThread
3262 CompilerThread::CompilerThread(CompileQueue* queue,
3263 CompilerCounters* counters)
3264 : JavaThread(&compiler_thread_entry) {
3265 _env = NULL;
3266 _log = NULL;
3267 _task = NULL;
3268 _queue = queue;
3269 _counters = counters;
3270 _buffer_blob = NULL;
3271 _compiler = NULL;
3272
3273 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3274 resource_area()->bias_to(mtCompiler);
3275
3276 #ifndef PRODUCT
3277 _ideal_graph_printer = NULL;
3278 #endif
3279 }
3280
3281 bool CompilerThread::can_call_java() const {
3282 return _compiler != NULL && _compiler->is_jvmci();
3283 }
3284
3285 // Create sweeper thread
3286 CodeCacheSweeperThread::CodeCacheSweeperThread()
3287 : JavaThread(&sweeper_thread_entry) {
3288 _scanned_compiled_method = NULL;
3289 }
3290
3291 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3292 JavaThread::oops_do(f, cf);
3293 if (_scanned_compiled_method != NULL && cf != NULL) {
3294 // Safepoints can occur when the sweeper is scanning an nmethod so
3295 // process it here to make sure it isn't unloaded in the middle of
3296 // a scan.
3297 cf->do_code_blob(_scanned_compiled_method);
3298 }
3299 }
3300
3301 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3302 JavaThread::nmethods_do(cf);
3303 if (_scanned_compiled_method != NULL && cf != NULL) {
3304 // Safepoints can occur when the sweeper is scanning an nmethod so
3305 // process it here to make sure it isn't unloaded in the middle of
3306 // a scan.
3307 cf->do_code_blob(_scanned_compiled_method);
3308 }
3309 }
3310
3311
3312 // ======= Threads ========
3313
3314 // The Threads class links together all active threads, and provides
3315 // operations over all threads. It is protected by its own Mutex
3316 // lock, which is also used in other contexts to protect thread
3317 // operations from having the thread being operated on from exiting
3318 // and going away unexpectedly (e.g., safepoint synchronization)
3319
3320 JavaThread* Threads::_thread_list = NULL;
3321 int Threads::_number_of_threads = 0;
3322 int Threads::_number_of_non_daemon_threads = 0;
3323 int Threads::_return_code = 0;
3324 int Threads::_thread_claim_parity = 0;
3325 size_t JavaThread::_stack_size_at_create = 0;
3326 #ifdef ASSERT
3327 bool Threads::_vm_complete = false;
3328 #endif
3329
3330 // All JavaThreads
3331 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3332
3333 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3334 void Threads::threads_do(ThreadClosure* tc) {
3335 assert_locked_or_safepoint(Threads_lock);
3336 // ALL_JAVA_THREADS iterates through all JavaThreads
3337 ALL_JAVA_THREADS(p) {
3338 tc->do_thread(p);
3339 }
3340 // Someday we could have a table or list of all non-JavaThreads.
3341 // For now, just manually iterate through them.
3342 tc->do_thread(VMThread::vm_thread());
3343 Universe::heap()->gc_threads_do(tc);
3344 WatcherThread *wt = WatcherThread::watcher_thread();
3345 // Strictly speaking, the following NULL check isn't sufficient to make sure
3346 // the data for WatcherThread is still valid upon being examined. However,
3347 // considering that WatchThread terminates when the VM is on the way to
3348 // exit at safepoint, the chance of the above is extremely small. The right
3349 // way to prevent termination of WatcherThread would be to acquire
3350 // Terminator_lock, but we can't do that without violating the lock rank
3351 // checking in some cases.
3352 if (wt != NULL) {
3353 tc->do_thread(wt);
3354 }
3355
3356 // If CompilerThreads ever become non-JavaThreads, add them here
3357 }
3358
3359 void Threads::parallel_java_threads_do(ThreadClosure* tc) {
3360 int cp = Threads::thread_claim_parity();
3361 ALL_JAVA_THREADS(p) {
3362 if (p->claim_oops_do(true, cp)) {
3363 tc->do_thread(p);
3364 }
3365 }
3366 // Thread claiming protocol requires us to claim the same interesting
3367 // threads on all paths. Notably, Threads::possibly_parallel_threads_do
3368 // claims all Java threads *and* the VMThread. To avoid breaking the
3369 // claiming protocol, we have to claim VMThread on this path too, even
3370 // if we do not apply the closure to the VMThread.
3371 VMThread* vmt = VMThread::vm_thread();
3372 (void)vmt->claim_oops_do(true, cp);
3373 }
3374
3375 // The system initialization in the library has three phases.
3376 //
3377 // Phase 1: java.lang.System class initialization
3378 // java.lang.System is a primordial class loaded and initialized
3379 // by the VM early during startup. java.lang.System.<clinit>
3380 // only does registerNatives and keeps the rest of the class
3381 // initialization work later until thread initialization completes.
3382 //
3383 // System.initPhase1 initializes the system properties, the static
3384 // fields in, out, and err. Set up java signal handlers, OS-specific
3385 // system settings, and thread group of the main thread.
3386 static void call_initPhase1(TRAPS) {
3387 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3388 JavaValue result(T_VOID);
3389 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3390 vmSymbols::void_method_signature(), CHECK);
3391 }
3392
3393 // Phase 2. Module system initialization
3394 // This will initialize the module system. Only java.base classes
3395 // can be loaded until phase 2 completes.
3396 //
3397 // Call System.initPhase2 after the compiler initialization and jsr292
3398 // classes get initialized because module initialization runs a lot of java
3399 // code, that for performance reasons, should be compiled. Also, this will
3400 // enable the startup code to use lambda and other language features in this
3401 // phase and onward.
3402 //
3403 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3404 static void call_initPhase2(TRAPS) {
3405 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3406
3407 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3408
3409 JavaValue result(T_INT);
3410 JavaCallArguments args;
3411 args.push_int(DisplayVMOutputToStderr);
3412 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3413 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3414 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3415 if (result.get_jint() != JNI_OK) {
3416 vm_exit_during_initialization(); // no message or exception
3417 }
3418
3419 universe_post_module_init();
3420 }
3421
3422 // Phase 3. final setup - set security manager, system class loader and TCCL
3423 //
3424 // This will instantiate and set the security manager, set the system class
3425 // loader as well as the thread context class loader. The security manager
3426 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3427 // other modules or the application's classpath.
3428 static void call_initPhase3(TRAPS) {
3429 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3430 JavaValue result(T_VOID);
3431 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3432 vmSymbols::void_method_signature(), CHECK);
3433 }
3434
3435 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3436 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3437
3438 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3439 create_vm_init_libraries();
3440 }
3441
3442 initialize_class(vmSymbols::java_lang_String(), CHECK);
3443
3444 // Inject CompactStrings value after the static initializers for String ran.
3445 java_lang_String::set_compact_strings(CompactStrings);
3446
3447 // Initialize java_lang.System (needed before creating the thread)
3448 initialize_class(vmSymbols::java_lang_System(), CHECK);
3449 // The VM creates & returns objects of this class. Make sure it's initialized.
3450 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3451 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3452 Handle thread_group = create_initial_thread_group(CHECK);
3453 Universe::set_main_thread_group(thread_group());
3454 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3455 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3456 main_thread->set_threadObj(thread_object);
3457 // Set thread status to running since main thread has
3458 // been started and running.
3459 java_lang_Thread::set_thread_status(thread_object,
3460 java_lang_Thread::RUNNABLE);
3461
3462 // The VM creates objects of this class.
3463 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3464
3465 // The VM preresolves methods to these classes. Make sure that they get initialized
3466 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3467 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3468
3469 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3470 call_initPhase1(CHECK);
3471
3472 // get the Java runtime name after java.lang.System is initialized
3473 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3474 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3475
3476 // an instance of OutOfMemory exception has been allocated earlier
3477 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3478 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3479 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3480 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3481 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3482 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3483 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3484 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3485 }
3486
3487 void Threads::initialize_jsr292_core_classes(TRAPS) {
3488 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3489
3490 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3491 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3492 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3493 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3494 }
3495
3496 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3497 extern void JDK_Version_init();
3498
3499 // Preinitialize version info.
3500 VM_Version::early_initialize();
3501
3502 // Check version
3503 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3504
3505 // Initialize library-based TLS
3506 ThreadLocalStorage::init();
3507
3508 // Initialize the output stream module
3509 ostream_init();
3510
3511 // Process java launcher properties.
3512 Arguments::process_sun_java_launcher_properties(args);
3513
3514 // Initialize the os module
3515 os::init();
3516
3517 // Record VM creation timing statistics
3518 TraceVmCreationTime create_vm_timer;
3519 create_vm_timer.start();
3520
3521 // Initialize system properties.
3522 Arguments::init_system_properties();
3523
3524 // So that JDK version can be used as a discriminator when parsing arguments
3525 JDK_Version_init();
3526
3527 // Update/Initialize System properties after JDK version number is known
3528 Arguments::init_version_specific_system_properties();
3529
3530 // Make sure to initialize log configuration *before* parsing arguments
3531 LogConfiguration::initialize(create_vm_timer.begin_time());
3532
3533 // Parse arguments
3534 jint parse_result = Arguments::parse(args);
3535 if (parse_result != JNI_OK) return parse_result;
3536
3537 os::init_before_ergo();
3538
3539 jint ergo_result = Arguments::apply_ergo();
3540 if (ergo_result != JNI_OK) return ergo_result;
3541
3542 // Final check of all ranges after ergonomics which may change values.
3543 if (!CommandLineFlagRangeList::check_ranges()) {
3544 return JNI_EINVAL;
3545 }
3546
3547 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3548 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3549 if (!constraint_result) {
3550 return JNI_EINVAL;
3551 }
3552
3553 CommandLineFlagWriteableList::mark_startup();
3554
3555 if (PauseAtStartup) {
3556 os::pause();
3557 }
3558
3559 HOTSPOT_VM_INIT_BEGIN();
3560
3561 // Timing (must come after argument parsing)
3562 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3563
3564 SafepointMechanism::initialize();
3565
3566 // Initialize the os module after parsing the args
3567 jint os_init_2_result = os::init_2();
3568 if (os_init_2_result != JNI_OK) return os_init_2_result;
3569
3570 jint adjust_after_os_result = Arguments::adjust_after_os();
3571 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3572
3573 // Initialize output stream logging
3574 ostream_init_log();
3575
3576 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3577 // Must be before create_vm_init_agents()
3578 if (Arguments::init_libraries_at_startup()) {
3579 convert_vm_init_libraries_to_agents();
3580 }
3581
3582 // Launch -agentlib/-agentpath and converted -Xrun agents
3583 if (Arguments::init_agents_at_startup()) {
3584 create_vm_init_agents();
3585 }
3586
3587 // Initialize Threads state
3588 _thread_list = NULL;
3589 _number_of_threads = 0;
3590 _number_of_non_daemon_threads = 0;
3591
3592 // Initialize global data structures and create system classes in heap
3593 vm_init_globals();
3594
3595 #if INCLUDE_JVMCI
3596 if (JVMCICounterSize > 0) {
3597 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3598 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3599 } else {
3600 JavaThread::_jvmci_old_thread_counters = NULL;
3601 }
3602 #endif // INCLUDE_JVMCI
3603
3604 // Attach the main thread to this os thread
3605 JavaThread* main_thread = new JavaThread();
3606 main_thread->set_thread_state(_thread_in_vm);
3607 main_thread->initialize_thread_current();
3608 // must do this before set_active_handles
3609 main_thread->record_stack_base_and_size();
3610 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3611
3612 if (!main_thread->set_as_starting_thread()) {
3613 vm_shutdown_during_initialization(
3614 "Failed necessary internal allocation. Out of swap space");
3615 delete main_thread;
3616 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3617 return JNI_ENOMEM;
3618 }
3619
3620 // Enable guard page *after* os::create_main_thread(), otherwise it would
3621 // crash Linux VM, see notes in os_linux.cpp.
3622 main_thread->create_stack_guard_pages();
3623
3624 // Initialize Java-Level synchronization subsystem
3625 ObjectMonitor::Initialize();
3626
3627 // Initialize global modules
3628 jint status = init_globals();
3629 if (status != JNI_OK) {
3630 delete main_thread;
3631 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3632 return status;
3633 }
3634
3635 if (TRACE_INITIALIZE() != JNI_OK) {
3636 vm_exit_during_initialization("Failed to initialize tracing backend");
3637 }
3638
3639 // Should be done after the heap is fully created
3640 main_thread->cache_global_variables();
3641
3642 HandleMark hm;
3643
3644 { MutexLocker mu(Threads_lock);
3645 Threads::add(main_thread);
3646 }
3647
3648 // Any JVMTI raw monitors entered in onload will transition into
3649 // real raw monitor. VM is setup enough here for raw monitor enter.
3650 JvmtiExport::transition_pending_onload_raw_monitors();
3651
3652 // Create the VMThread
3653 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3654
3655 VMThread::create();
3656 Thread* vmthread = VMThread::vm_thread();
3657
3658 if (!os::create_thread(vmthread, os::vm_thread)) {
3659 vm_exit_during_initialization("Cannot create VM thread. "
3660 "Out of system resources.");
3661 }
3662
3663 // Wait for the VM thread to become ready, and VMThread::run to initialize
3664 // Monitors can have spurious returns, must always check another state flag
3665 {
3666 MutexLocker ml(Notify_lock);
3667 os::start_thread(vmthread);
3668 while (vmthread->active_handles() == NULL) {
3669 Notify_lock->wait();
3670 }
3671 }
3672 }
3673
3674 assert(Universe::is_fully_initialized(), "not initialized");
3675 if (VerifyDuringStartup) {
3676 // Make sure we're starting with a clean slate.
3677 VM_Verify verify_op;
3678 VMThread::execute(&verify_op);
3679 }
3680
3681 Thread* THREAD = Thread::current();
3682
3683 // Always call even when there are not JVMTI environments yet, since environments
3684 // may be attached late and JVMTI must track phases of VM execution
3685 JvmtiExport::enter_early_start_phase();
3686
3687 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3688 JvmtiExport::post_early_vm_start();
3689
3690 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3691
3692 // We need this for ClassDataSharing - the initial vm.info property is set
3693 // with the default value of CDS "sharing" which may be reset through
3694 // command line options.
3695 reset_vm_info_property(CHECK_JNI_ERR);
3696
3697 quicken_jni_functions();
3698
3699 // No more stub generation allowed after that point.
3700 StubCodeDesc::freeze();
3701
3702 // Set flag that basic initialization has completed. Used by exceptions and various
3703 // debug stuff, that does not work until all basic classes have been initialized.
3704 set_init_completed();
3705
3706 LogConfiguration::post_initialize();
3707 Metaspace::post_initialize();
3708
3709 HOTSPOT_VM_INIT_END();
3710
3711 // record VM initialization completion time
3712 #if INCLUDE_MANAGEMENT
3713 Management::record_vm_init_completed();
3714 #endif // INCLUDE_MANAGEMENT
3715
3716 // Signal Dispatcher needs to be started before VMInit event is posted
3717 os::signal_init(CHECK_JNI_ERR);
3718
3719 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3720 if (!DisableAttachMechanism) {
3721 AttachListener::vm_start();
3722 if (StartAttachListener || AttachListener::init_at_startup()) {
3723 AttachListener::init();
3724 }
3725 }
3726
3727 // Launch -Xrun agents
3728 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3729 // back-end can launch with -Xdebug -Xrunjdwp.
3730 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3731 create_vm_init_libraries();
3732 }
3733
3734 if (CleanChunkPoolAsync) {
3735 Chunk::start_chunk_pool_cleaner_task();
3736 }
3737
3738 // initialize compiler(s)
3739 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3740 CompileBroker::compilation_init(CHECK_JNI_ERR);
3741 #endif
3742
3743 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3744 // It is done after compilers are initialized, because otherwise compilations of
3745 // signature polymorphic MH intrinsics can be missed
3746 // (see SystemDictionary::find_method_handle_intrinsic).
3747 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3748
3749 // This will initialize the module system. Only java.base classes can be
3750 // loaded until phase 2 completes
3751 call_initPhase2(CHECK_JNI_ERR);
3752
3753 // Always call even when there are not JVMTI environments yet, since environments
3754 // may be attached late and JVMTI must track phases of VM execution
3755 JvmtiExport::enter_start_phase();
3756
3757 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3758 JvmtiExport::post_vm_start();
3759
3760 // Final system initialization including security manager and system class loader
3761 call_initPhase3(CHECK_JNI_ERR);
3762
3763 // cache the system and platform class loaders
3764 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3765
3766 #if INCLUDE_JVMCI
3767 if (EnableJVMCI) {
3768 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3769 // The JVMCI Java initialization code will read this flag and
3770 // do the printing if it's set.
3771 bool init = JVMCIPrintProperties;
3772
3773 if (!init) {
3774 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3775 // compilations via JVMCI will not actually block until JVMCI is initialized.
3776 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3777 }
3778
3779 if (init) {
3780 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3781 }
3782 }
3783 #endif
3784
3785 // Always call even when there are not JVMTI environments yet, since environments
3786 // may be attached late and JVMTI must track phases of VM execution
3787 JvmtiExport::enter_live_phase();
3788
3789 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3790 JvmtiExport::post_vm_initialized();
3791
3792 if (TRACE_START() != JNI_OK) {
3793 vm_exit_during_initialization("Failed to start tracing backend.");
3794 }
3795
3796 #if INCLUDE_MANAGEMENT
3797 Management::initialize(THREAD);
3798
3799 if (HAS_PENDING_EXCEPTION) {
3800 // management agent fails to start possibly due to
3801 // configuration problem and is responsible for printing
3802 // stack trace if appropriate. Simply exit VM.
3803 vm_exit(1);
3804 }
3805 #endif // INCLUDE_MANAGEMENT
3806
3807 if (MemProfiling) MemProfiler::engage();
3808 StatSampler::engage();
3809 if (CheckJNICalls) JniPeriodicChecker::engage();
3810
3811 BiasedLocking::init();
3812
3813 #if INCLUDE_RTM_OPT
3814 RTMLockingCounters::init();
3815 #endif
3816
3817 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3818 call_postVMInitHook(THREAD);
3819 // The Java side of PostVMInitHook.run must deal with all
3820 // exceptions and provide means of diagnosis.
3821 if (HAS_PENDING_EXCEPTION) {
3822 CLEAR_PENDING_EXCEPTION;
3823 }
3824 }
3825
3826 {
3827 MutexLocker ml(PeriodicTask_lock);
3828 // Make sure the WatcherThread can be started by WatcherThread::start()
3829 // or by dynamic enrollment.
3830 WatcherThread::make_startable();
3831 // Start up the WatcherThread if there are any periodic tasks
3832 // NOTE: All PeriodicTasks should be registered by now. If they
3833 // aren't, late joiners might appear to start slowly (we might
3834 // take a while to process their first tick).
3835 if (PeriodicTask::num_tasks() > 0) {
3836 WatcherThread::start();
3837 }
3838 }
3839
3840 create_vm_timer.end();
3841 #ifdef ASSERT
3842 _vm_complete = true;
3843 #endif
3844
3845 if (DumpSharedSpaces) {
3846 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3847 ShouldNotReachHere();
3848 }
3849
3850 return JNI_OK;
3851 }
3852
3853 // type for the Agent_OnLoad and JVM_OnLoad entry points
3854 extern "C" {
3855 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3856 }
3857 // Find a command line agent library and return its entry point for
3858 // -agentlib: -agentpath: -Xrun
3859 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3860 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3861 const char *on_load_symbols[],
3862 size_t num_symbol_entries) {
3863 OnLoadEntry_t on_load_entry = NULL;
3864 void *library = NULL;
3865
3866 if (!agent->valid()) {
3867 char buffer[JVM_MAXPATHLEN];
3868 char ebuf[1024] = "";
3869 const char *name = agent->name();
3870 const char *msg = "Could not find agent library ";
3871
3872 // First check to see if agent is statically linked into executable
3873 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3874 library = agent->os_lib();
3875 } else if (agent->is_absolute_path()) {
3876 library = os::dll_load(name, ebuf, sizeof ebuf);
3877 if (library == NULL) {
3878 const char *sub_msg = " in absolute path, with error: ";
3879 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3880 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3881 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3882 // If we can't find the agent, exit.
3883 vm_exit_during_initialization(buf, NULL);
3884 FREE_C_HEAP_ARRAY(char, buf);
3885 }
3886 } else {
3887 // Try to load the agent from the standard dll directory
3888 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3889 name)) {
3890 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3891 }
3892 if (library == NULL) { // Try the library path directory.
3893 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3894 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3895 }
3896 if (library == NULL) {
3897 const char *sub_msg = " on the library path, with error: ";
3898 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3899 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3900 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3901 // If we can't find the agent, exit.
3902 vm_exit_during_initialization(buf, NULL);
3903 FREE_C_HEAP_ARRAY(char, buf);
3904 }
3905 }
3906 }
3907 agent->set_os_lib(library);
3908 agent->set_valid();
3909 }
3910
3911 // Find the OnLoad function.
3912 on_load_entry =
3913 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3914 false,
3915 on_load_symbols,
3916 num_symbol_entries));
3917 return on_load_entry;
3918 }
3919
3920 // Find the JVM_OnLoad entry point
3921 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3922 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3923 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3924 }
3925
3926 // Find the Agent_OnLoad entry point
3927 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3928 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3929 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3930 }
3931
3932 // For backwards compatibility with -Xrun
3933 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3934 // treated like -agentpath:
3935 // Must be called before agent libraries are created
3936 void Threads::convert_vm_init_libraries_to_agents() {
3937 AgentLibrary* agent;
3938 AgentLibrary* next;
3939
3940 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3941 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3942 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3943
3944 // If there is an JVM_OnLoad function it will get called later,
3945 // otherwise see if there is an Agent_OnLoad
3946 if (on_load_entry == NULL) {
3947 on_load_entry = lookup_agent_on_load(agent);
3948 if (on_load_entry != NULL) {
3949 // switch it to the agent list -- so that Agent_OnLoad will be called,
3950 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3951 Arguments::convert_library_to_agent(agent);
3952 } else {
3953 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3954 }
3955 }
3956 }
3957 }
3958
3959 // Create agents for -agentlib: -agentpath: and converted -Xrun
3960 // Invokes Agent_OnLoad
3961 // Called very early -- before JavaThreads exist
3962 void Threads::create_vm_init_agents() {
3963 extern struct JavaVM_ main_vm;
3964 AgentLibrary* agent;
3965
3966 JvmtiExport::enter_onload_phase();
3967
3968 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3969 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3970
3971 if (on_load_entry != NULL) {
3972 // Invoke the Agent_OnLoad function
3973 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3974 if (err != JNI_OK) {
3975 vm_exit_during_initialization("agent library failed to init", agent->name());
3976 }
3977 } else {
3978 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3979 }
3980 }
3981 JvmtiExport::enter_primordial_phase();
3982 }
3983
3984 extern "C" {
3985 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3986 }
3987
3988 void Threads::shutdown_vm_agents() {
3989 // Send any Agent_OnUnload notifications
3990 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3991 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3992 extern struct JavaVM_ main_vm;
3993 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3994
3995 // Find the Agent_OnUnload function.
3996 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3997 os::find_agent_function(agent,
3998 false,
3999 on_unload_symbols,
4000 num_symbol_entries));
4001
4002 // Invoke the Agent_OnUnload function
4003 if (unload_entry != NULL) {
4004 JavaThread* thread = JavaThread::current();
4005 ThreadToNativeFromVM ttn(thread);
4006 HandleMark hm(thread);
4007 (*unload_entry)(&main_vm);
4008 }
4009 }
4010 }
4011
4012 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4013 // Invokes JVM_OnLoad
4014 void Threads::create_vm_init_libraries() {
4015 extern struct JavaVM_ main_vm;
4016 AgentLibrary* agent;
4017
4018 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4019 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4020
4021 if (on_load_entry != NULL) {
4022 // Invoke the JVM_OnLoad function
4023 JavaThread* thread = JavaThread::current();
4024 ThreadToNativeFromVM ttn(thread);
4025 HandleMark hm(thread);
4026 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4027 if (err != JNI_OK) {
4028 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4029 }
4030 } else {
4031 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4032 }
4033 }
4034 }
4035
4036 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4037 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4038
4039 JavaThread* java_thread = NULL;
4040 // Sequential search for now. Need to do better optimization later.
4041 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4042 oop tobj = thread->threadObj();
4043 if (!thread->is_exiting() &&
4044 tobj != NULL &&
4045 java_tid == java_lang_Thread::thread_id(tobj)) {
4046 java_thread = thread;
4047 break;
4048 }
4049 }
4050 return java_thread;
4051 }
4052
4053
4054 // Last thread running calls java.lang.Shutdown.shutdown()
4055 void JavaThread::invoke_shutdown_hooks() {
4056 HandleMark hm(this);
4057
4058 // We could get here with a pending exception, if so clear it now.
4059 if (this->has_pending_exception()) {
4060 this->clear_pending_exception();
4061 }
4062
4063 EXCEPTION_MARK;
4064 Klass* shutdown_klass =
4065 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4066 THREAD);
4067 if (shutdown_klass != NULL) {
4068 // SystemDictionary::resolve_or_null will return null if there was
4069 // an exception. If we cannot load the Shutdown class, just don't
4070 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4071 // and finalizers (if runFinalizersOnExit is set) won't be run.
4072 // Note that if a shutdown hook was registered or runFinalizersOnExit
4073 // was called, the Shutdown class would have already been loaded
4074 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4075 JavaValue result(T_VOID);
4076 JavaCalls::call_static(&result,
4077 shutdown_klass,
4078 vmSymbols::shutdown_method_name(),
4079 vmSymbols::void_method_signature(),
4080 THREAD);
4081 }
4082 CLEAR_PENDING_EXCEPTION;
4083 }
4084
4085 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4086 // the program falls off the end of main(). Another VM exit path is through
4087 // vm_exit() when the program calls System.exit() to return a value or when
4088 // there is a serious error in VM. The two shutdown paths are not exactly
4089 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4090 // and VM_Exit op at VM level.
4091 //
4092 // Shutdown sequence:
4093 // + Shutdown native memory tracking if it is on
4094 // + Wait until we are the last non-daemon thread to execute
4095 // <-- every thing is still working at this moment -->
4096 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4097 // shutdown hooks, run finalizers if finalization-on-exit
4098 // + Call before_exit(), prepare for VM exit
4099 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4100 // currently the only user of this mechanism is File.deleteOnExit())
4101 // > stop StatSampler, watcher thread, CMS threads,
4102 // post thread end and vm death events to JVMTI,
4103 // stop signal thread
4104 // + Call JavaThread::exit(), it will:
4105 // > release JNI handle blocks, remove stack guard pages
4106 // > remove this thread from Threads list
4107 // <-- no more Java code from this thread after this point -->
4108 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4109 // the compiler threads at safepoint
4110 // <-- do not use anything that could get blocked by Safepoint -->
4111 // + Disable tracing at JNI/JVM barriers
4112 // + Set _vm_exited flag for threads that are still running native code
4113 // + Delete this thread
4114 // + Call exit_globals()
4115 // > deletes tty
4116 // > deletes PerfMemory resources
4117 // + Return to caller
4118
4119 bool Threads::destroy_vm() {
4120 JavaThread* thread = JavaThread::current();
4121
4122 #ifdef ASSERT
4123 _vm_complete = false;
4124 #endif
4125 // Wait until we are the last non-daemon thread to execute
4126 { MutexLocker nu(Threads_lock);
4127 while (Threads::number_of_non_daemon_threads() > 1)
4128 // This wait should make safepoint checks, wait without a timeout,
4129 // and wait as a suspend-equivalent condition.
4130 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4131 Mutex::_as_suspend_equivalent_flag);
4132 }
4133
4134 // Hang forever on exit if we are reporting an error.
4135 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4136 os::infinite_sleep();
4137 }
4138 os::wait_for_keypress_at_exit();
4139
4140 // run Java level shutdown hooks
4141 thread->invoke_shutdown_hooks();
4142
4143 before_exit(thread);
4144
4145 thread->exit(true);
4146
4147 // Stop VM thread.
4148 {
4149 // 4945125 The vm thread comes to a safepoint during exit.
4150 // GC vm_operations can get caught at the safepoint, and the
4151 // heap is unparseable if they are caught. Grab the Heap_lock
4152 // to prevent this. The GC vm_operations will not be able to
4153 // queue until after the vm thread is dead. After this point,
4154 // we'll never emerge out of the safepoint before the VM exits.
4155
4156 MutexLocker ml(Heap_lock);
4157
4158 VMThread::wait_for_vm_thread_exit();
4159 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4160 VMThread::destroy();
4161 }
4162
4163 // clean up ideal graph printers
4164 #if defined(COMPILER2) && !defined(PRODUCT)
4165 IdealGraphPrinter::clean_up();
4166 #endif
4167
4168 // Now, all Java threads are gone except daemon threads. Daemon threads
4169 // running Java code or in VM are stopped by the Safepoint. However,
4170 // daemon threads executing native code are still running. But they
4171 // will be stopped at native=>Java/VM barriers. Note that we can't
4172 // simply kill or suspend them, as it is inherently deadlock-prone.
4173
4174 VM_Exit::set_vm_exited();
4175
4176 notify_vm_shutdown();
4177
4178 delete thread;
4179
4180 #if INCLUDE_JVMCI
4181 if (JVMCICounterSize > 0) {
4182 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4183 }
4184 #endif
4185
4186 // exit_globals() will delete tty
4187 exit_globals();
4188
4189 LogConfiguration::finalize();
4190
4191 return true;
4192 }
4193
4194
4195 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4196 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4197 return is_supported_jni_version(version);
4198 }
4199
4200
4201 jboolean Threads::is_supported_jni_version(jint version) {
4202 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4203 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4204 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4205 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4206 if (version == JNI_VERSION_9) return JNI_TRUE;
4207 if (version == JNI_VERSION_10) return JNI_TRUE;
4208 return JNI_FALSE;
4209 }
4210
4211
4212 void Threads::add(JavaThread* p, bool force_daemon) {
4213 // The threads lock must be owned at this point
4214 assert_locked_or_safepoint(Threads_lock);
4215
4216 // See the comment for this method in thread.hpp for its purpose and
4217 // why it is called here.
4218 p->initialize_queues();
4219 p->set_next(_thread_list);
4220 _thread_list = p;
4221 _number_of_threads++;
4222 oop threadObj = p->threadObj();
4223 bool daemon = true;
4224 // Bootstrapping problem: threadObj can be null for initial
4225 // JavaThread (or for threads attached via JNI)
4226 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4227 _number_of_non_daemon_threads++;
4228 daemon = false;
4229 }
4230
4231 ThreadService::add_thread(p, daemon);
4232
4233 // Possible GC point.
4234 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4235 }
4236
4237 void Threads::remove(JavaThread* p) {
4238
4239 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4240 ObjectSynchronizer::omFlush(p);
4241
4242 // Extra scope needed for Thread_lock, so we can check
4243 // that we do not remove thread without safepoint code notice
4244 { MutexLocker ml(Threads_lock);
4245
4246 assert(includes(p), "p must be present");
4247
4248 JavaThread* current = _thread_list;
4249 JavaThread* prev = NULL;
4250
4251 while (current != p) {
4252 prev = current;
4253 current = current->next();
4254 }
4255
4256 if (prev) {
4257 prev->set_next(current->next());
4258 } else {
4259 _thread_list = p->next();
4260 }
4261 _number_of_threads--;
4262 oop threadObj = p->threadObj();
4263 bool daemon = true;
4264 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4265 _number_of_non_daemon_threads--;
4266 daemon = false;
4267
4268 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4269 // on destroy_vm will wake up.
4270 if (number_of_non_daemon_threads() == 1) {
4271 Threads_lock->notify_all();
4272 }
4273 }
4274 ThreadService::remove_thread(p, daemon);
4275
4276 // Make sure that safepoint code disregard this thread. This is needed since
4277 // the thread might mess around with locks after this point. This can cause it
4278 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4279 // of this thread since it is removed from the queue.
4280 p->set_terminated_value();
4281 } // unlock Threads_lock
4282
4283 // Since Events::log uses a lock, we grab it outside the Threads_lock
4284 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4285 }
4286
4287 // Threads_lock must be held when this is called (or must be called during a safepoint)
4288 bool Threads::includes(JavaThread* p) {
4289 assert(Threads_lock->is_locked(), "sanity check");
4290 ALL_JAVA_THREADS(q) {
4291 if (q == p) {
4292 return true;
4293 }
4294 }
4295 return false;
4296 }
4297
4298 // Operations on the Threads list for GC. These are not explicitly locked,
4299 // but the garbage collector must provide a safe context for them to run.
4300 // In particular, these things should never be called when the Threads_lock
4301 // is held by some other thread. (Note: the Safepoint abstraction also
4302 // uses the Threads_lock to guarantee this property. It also makes sure that
4303 // all threads gets blocked when exiting or starting).
4304
4305 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4306 ALL_JAVA_THREADS(p) {
4307 p->oops_do(f, cf);
4308 }
4309 VMThread::vm_thread()->oops_do(f, cf);
4310 }
4311
4312 void Threads::change_thread_claim_parity() {
4313 // Set the new claim parity.
4314 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4315 "Not in range.");
4316 _thread_claim_parity++;
4317 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4318 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4319 "Not in range.");
4320 }
4321
4322 #ifdef ASSERT
4323 void Threads::assert_all_threads_claimed() {
4324 ALL_JAVA_THREADS(p) {
4325 const int thread_parity = p->oops_do_parity();
4326 assert((thread_parity == _thread_claim_parity),
4327 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4328 }
4329 VMThread* vmt = VMThread::vm_thread();
4330 const int thread_parity = vmt->oops_do_parity();
4331 assert((thread_parity == _thread_claim_parity),
4332 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4333 }
4334 #endif // ASSERT
4335
4336 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4337 int cp = Threads::thread_claim_parity();
4338 ALL_JAVA_THREADS(p) {
4339 if (p->claim_oops_do(is_par, cp)) {
4340 p->oops_do(f, cf);
4341 }
4342 }
4343 VMThread* vmt = VMThread::vm_thread();
4344 if (vmt->claim_oops_do(is_par, cp)) {
4345 vmt->oops_do(f, cf);
4346 }
4347 }
4348
4349 #if INCLUDE_ALL_GCS
4350 // Used by ParallelScavenge
4351 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4352 ALL_JAVA_THREADS(p) {
4353 q->enqueue(new ThreadRootsTask(p));
4354 }
4355 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4356 }
4357
4358 // Used by Parallel Old
4359 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4360 ALL_JAVA_THREADS(p) {
4361 q->enqueue(new ThreadRootsMarkingTask(p));
4362 }
4363 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4364 }
4365 #endif // INCLUDE_ALL_GCS
4366
4367 void Threads::nmethods_do(CodeBlobClosure* cf) {
4368 ALL_JAVA_THREADS(p) {
4369 // This is used by the code cache sweeper to mark nmethods that are active
4370 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4371 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4372 if(!p->is_Code_cache_sweeper_thread()) {
4373 p->nmethods_do(cf);
4374 }
4375 }
4376 }
4377
4378 void Threads::metadata_do(void f(Metadata*)) {
4379 ALL_JAVA_THREADS(p) {
4380 p->metadata_do(f);
4381 }
4382 }
4383
4384 class ThreadHandlesClosure : public ThreadClosure {
4385 void (*_f)(Metadata*);
4386 public:
4387 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4388 virtual void do_thread(Thread* thread) {
4389 thread->metadata_handles_do(_f);
4390 }
4391 };
4392
4393 void Threads::metadata_handles_do(void f(Metadata*)) {
4394 // Only walk the Handles in Thread.
4395 ThreadHandlesClosure handles_closure(f);
4396 threads_do(&handles_closure);
4397 }
4398
4399 void Threads::deoptimized_wrt_marked_nmethods() {
4400 ALL_JAVA_THREADS(p) {
4401 p->deoptimized_wrt_marked_nmethods();
4402 }
4403 }
4404
4405
4406 // Get count Java threads that are waiting to enter the specified monitor.
4407 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4408 address monitor,
4409 bool doLock) {
4410 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4411 "must grab Threads_lock or be at safepoint");
4412 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4413
4414 int i = 0;
4415 {
4416 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4417 ALL_JAVA_THREADS(p) {
4418 if (!p->can_call_java()) continue;
4419
4420 address pending = (address)p->current_pending_monitor();
4421 if (pending == monitor) { // found a match
4422 if (i < count) result->append(p); // save the first count matches
4423 i++;
4424 }
4425 }
4426 }
4427 return result;
4428 }
4429
4430
4431 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4432 bool doLock) {
4433 assert(doLock ||
4434 Threads_lock->owned_by_self() ||
4435 SafepointSynchronize::is_at_safepoint(),
4436 "must grab Threads_lock or be at safepoint");
4437
4438 // NULL owner means not locked so we can skip the search
4439 if (owner == NULL) return NULL;
4440
4441 {
4442 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4443 ALL_JAVA_THREADS(p) {
4444 // first, see if owner is the address of a Java thread
4445 if (owner == (address)p) return p;
4446 }
4447 }
4448 // Cannot assert on lack of success here since this function may be
4449 // used by code that is trying to report useful problem information
4450 // like deadlock detection.
4451 if (UseHeavyMonitors) return NULL;
4452
4453 // If we didn't find a matching Java thread and we didn't force use of
4454 // heavyweight monitors, then the owner is the stack address of the
4455 // Lock Word in the owning Java thread's stack.
4456 //
4457 JavaThread* the_owner = NULL;
4458 {
4459 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4460 ALL_JAVA_THREADS(q) {
4461 if (q->is_lock_owned(owner)) {
4462 the_owner = q;
4463 break;
4464 }
4465 }
4466 }
4467 // cannot assert on lack of success here; see above comment
4468 return the_owner;
4469 }
4470
4471 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4472 void Threads::print_on(outputStream* st, bool print_stacks,
4473 bool internal_format, bool print_concurrent_locks) {
4474 char buf[32];
4475 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4476
4477 st->print_cr("Full thread dump %s (%s %s):",
4478 Abstract_VM_Version::vm_name(),
4479 Abstract_VM_Version::vm_release(),
4480 Abstract_VM_Version::vm_info_string());
4481 st->cr();
4482
4483 #if INCLUDE_SERVICES
4484 // Dump concurrent locks
4485 ConcurrentLocksDump concurrent_locks;
4486 if (print_concurrent_locks) {
4487 concurrent_locks.dump_at_safepoint();
4488 }
4489 #endif // INCLUDE_SERVICES
4490
4491 ALL_JAVA_THREADS(p) {
4492 ResourceMark rm;
4493 p->print_on(st);
4494 if (print_stacks) {
4495 if (internal_format) {
4496 p->trace_stack();
4497 } else {
4498 p->print_stack_on(st);
4499 }
4500 }
4501 st->cr();
4502 #if INCLUDE_SERVICES
4503 if (print_concurrent_locks) {
4504 concurrent_locks.print_locks_on(p, st);
4505 }
4506 #endif // INCLUDE_SERVICES
4507 }
4508
4509 VMThread::vm_thread()->print_on(st);
4510 st->cr();
4511 Universe::heap()->print_gc_threads_on(st);
4512 WatcherThread* wt = WatcherThread::watcher_thread();
4513 if (wt != NULL) {
4514 wt->print_on(st);
4515 st->cr();
4516 }
4517 st->flush();
4518 }
4519
4520 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4521 int buflen, bool* found_current) {
4522 if (this_thread != NULL) {
4523 bool is_current = (current == this_thread);
4524 *found_current = *found_current || is_current;
4525 st->print("%s", is_current ? "=>" : " ");
4526
4527 st->print(PTR_FORMAT, p2i(this_thread));
4528 st->print(" ");
4529 this_thread->print_on_error(st, buf, buflen);
4530 st->cr();
4531 }
4532 }
4533
4534 class PrintOnErrorClosure : public ThreadClosure {
4535 outputStream* _st;
4536 Thread* _current;
4537 char* _buf;
4538 int _buflen;
4539 bool* _found_current;
4540 public:
4541 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4542 int buflen, bool* found_current) :
4543 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4544
4545 virtual void do_thread(Thread* thread) {
4546 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4547 }
4548 };
4549
4550 // Threads::print_on_error() is called by fatal error handler. It's possible
4551 // that VM is not at safepoint and/or current thread is inside signal handler.
4552 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4553 // memory (even in resource area), it might deadlock the error handler.
4554 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4555 int buflen) {
4556 bool found_current = false;
4557 st->print_cr("Java Threads: ( => current thread )");
4558 ALL_JAVA_THREADS(thread) {
4559 print_on_error(thread, st, current, buf, buflen, &found_current);
4560 }
4561 st->cr();
4562
4563 st->print_cr("Other Threads:");
4564 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4565 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4566
4567 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4568 Universe::heap()->gc_threads_do(&print_closure);
4569
4570 if (!found_current) {
4571 st->cr();
4572 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4573 current->print_on_error(st, buf, buflen);
4574 st->cr();
4575 }
4576 st->cr();
4577 st->print_cr("Threads with active compile tasks:");
4578 print_threads_compiling(st, buf, buflen);
4579 }
4580
4581 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4582 ALL_JAVA_THREADS(thread) {
4583 if (thread->is_Compiler_thread()) {
4584 CompilerThread* ct = (CompilerThread*) thread;
4585 if (ct->task() != NULL) {
4586 thread->print_name_on_error(st, buf, buflen);
4587 ct->task()->print(st, NULL, true, true);
4588 }
4589 }
4590 }
4591 }
4592
4593
4594 // Internal SpinLock and Mutex
4595 // Based on ParkEvent
4596
4597 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4598 //
4599 // We employ SpinLocks _only for low-contention, fixed-length
4600 // short-duration critical sections where we're concerned
4601 // about native mutex_t or HotSpot Mutex:: latency.
4602 // The mux construct provides a spin-then-block mutual exclusion
4603 // mechanism.
4604 //
4605 // Testing has shown that contention on the ListLock guarding gFreeList
4606 // is common. If we implement ListLock as a simple SpinLock it's common
4607 // for the JVM to devolve to yielding with little progress. This is true
4608 // despite the fact that the critical sections protected by ListLock are
4609 // extremely short.
4610 //
4611 // TODO-FIXME: ListLock should be of type SpinLock.
4612 // We should make this a 1st-class type, integrated into the lock
4613 // hierarchy as leaf-locks. Critically, the SpinLock structure
4614 // should have sufficient padding to avoid false-sharing and excessive
4615 // cache-coherency traffic.
4616
4617
4618 typedef volatile int SpinLockT;
4619
4620 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4621 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4622 return; // normal fast-path return
4623 }
4624
4625 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4626 TEVENT(SpinAcquire - ctx);
4627 int ctr = 0;
4628 int Yields = 0;
4629 for (;;) {
4630 while (*adr != 0) {
4631 ++ctr;
4632 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4633 if (Yields > 5) {
4634 os::naked_short_sleep(1);
4635 } else {
4636 os::naked_yield();
4637 ++Yields;
4638 }
4639 } else {
4640 SpinPause();
4641 }
4642 }
4643 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4644 }
4645 }
4646
4647 void Thread::SpinRelease(volatile int * adr) {
4648 assert(*adr != 0, "invariant");
4649 OrderAccess::fence(); // guarantee at least release consistency.
4650 // Roach-motel semantics.
4651 // It's safe if subsequent LDs and STs float "up" into the critical section,
4652 // but prior LDs and STs within the critical section can't be allowed
4653 // to reorder or float past the ST that releases the lock.
4654 // Loads and stores in the critical section - which appear in program
4655 // order before the store that releases the lock - must also appear
4656 // before the store that releases the lock in memory visibility order.
4657 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4658 // the ST of 0 into the lock-word which releases the lock, so fence
4659 // more than covers this on all platforms.
4660 *adr = 0;
4661 }
4662
4663 // muxAcquire and muxRelease:
4664 //
4665 // * muxAcquire and muxRelease support a single-word lock-word construct.
4666 // The LSB of the word is set IFF the lock is held.
4667 // The remainder of the word points to the head of a singly-linked list
4668 // of threads blocked on the lock.
4669 //
4670 // * The current implementation of muxAcquire-muxRelease uses its own
4671 // dedicated Thread._MuxEvent instance. If we're interested in
4672 // minimizing the peak number of extant ParkEvent instances then
4673 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4674 // as certain invariants were satisfied. Specifically, care would need
4675 // to be taken with regards to consuming unpark() "permits".
4676 // A safe rule of thumb is that a thread would never call muxAcquire()
4677 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4678 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4679 // consume an unpark() permit intended for monitorenter, for instance.
4680 // One way around this would be to widen the restricted-range semaphore
4681 // implemented in park(). Another alternative would be to provide
4682 // multiple instances of the PlatformEvent() for each thread. One
4683 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4684 //
4685 // * Usage:
4686 // -- Only as leaf locks
4687 // -- for short-term locking only as muxAcquire does not perform
4688 // thread state transitions.
4689 //
4690 // Alternatives:
4691 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4692 // but with parking or spin-then-park instead of pure spinning.
4693 // * Use Taura-Oyama-Yonenzawa locks.
4694 // * It's possible to construct a 1-0 lock if we encode the lockword as
4695 // (List,LockByte). Acquire will CAS the full lockword while Release
4696 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4697 // acquiring threads use timers (ParkTimed) to detect and recover from
4698 // the stranding window. Thread/Node structures must be aligned on 256-byte
4699 // boundaries by using placement-new.
4700 // * Augment MCS with advisory back-link fields maintained with CAS().
4701 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4702 // The validity of the backlinks must be ratified before we trust the value.
4703 // If the backlinks are invalid the exiting thread must back-track through the
4704 // the forward links, which are always trustworthy.
4705 // * Add a successor indication. The LockWord is currently encoded as
4706 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4707 // to provide the usual futile-wakeup optimization.
4708 // See RTStt for details.
4709 // * Consider schedctl.sc_nopreempt to cover the critical section.
4710 //
4711
4712
4713 typedef volatile intptr_t MutexT; // Mux Lock-word
4714 enum MuxBits { LOCKBIT = 1 };
4715
4716 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4717 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4718 if (w == 0) return;
4719 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4720 return;
4721 }
4722
4723 TEVENT(muxAcquire - Contention);
4724 ParkEvent * const Self = Thread::current()->_MuxEvent;
4725 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4726 for (;;) {
4727 int its = (os::is_MP() ? 100 : 0) + 1;
4728
4729 // Optional spin phase: spin-then-park strategy
4730 while (--its >= 0) {
4731 w = *Lock;
4732 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4733 return;
4734 }
4735 }
4736
4737 Self->reset();
4738 Self->OnList = intptr_t(Lock);
4739 // The following fence() isn't _strictly necessary as the subsequent
4740 // CAS() both serializes execution and ratifies the fetched *Lock value.
4741 OrderAccess::fence();
4742 for (;;) {
4743 w = *Lock;
4744 if ((w & LOCKBIT) == 0) {
4745 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4746 Self->OnList = 0; // hygiene - allows stronger asserts
4747 return;
4748 }
4749 continue; // Interference -- *Lock changed -- Just retry
4750 }
4751 assert(w & LOCKBIT, "invariant");
4752 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4753 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4754 }
4755
4756 while (Self->OnList != 0) {
4757 Self->park();
4758 }
4759 }
4760 }
4761
4762 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4763 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4764 if (w == 0) return;
4765 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4766 return;
4767 }
4768
4769 TEVENT(muxAcquire - Contention);
4770 ParkEvent * ReleaseAfter = NULL;
4771 if (ev == NULL) {
4772 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4773 }
4774 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4775 for (;;) {
4776 guarantee(ev->OnList == 0, "invariant");
4777 int its = (os::is_MP() ? 100 : 0) + 1;
4778
4779 // Optional spin phase: spin-then-park strategy
4780 while (--its >= 0) {
4781 w = *Lock;
4782 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4783 if (ReleaseAfter != NULL) {
4784 ParkEvent::Release(ReleaseAfter);
4785 }
4786 return;
4787 }
4788 }
4789
4790 ev->reset();
4791 ev->OnList = intptr_t(Lock);
4792 // The following fence() isn't _strictly necessary as the subsequent
4793 // CAS() both serializes execution and ratifies the fetched *Lock value.
4794 OrderAccess::fence();
4795 for (;;) {
4796 w = *Lock;
4797 if ((w & LOCKBIT) == 0) {
4798 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4799 ev->OnList = 0;
4800 // We call ::Release while holding the outer lock, thus
4801 // artificially lengthening the critical section.
4802 // Consider deferring the ::Release() until the subsequent unlock(),
4803 // after we've dropped the outer lock.
4804 if (ReleaseAfter != NULL) {
4805 ParkEvent::Release(ReleaseAfter);
4806 }
4807 return;
4808 }
4809 continue; // Interference -- *Lock changed -- Just retry
4810 }
4811 assert(w & LOCKBIT, "invariant");
4812 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4813 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4814 }
4815
4816 while (ev->OnList != 0) {
4817 ev->park();
4818 }
4819 }
4820 }
4821
4822 // Release() must extract a successor from the list and then wake that thread.
4823 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4824 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4825 // Release() would :
4826 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4827 // (B) Extract a successor from the private list "in-hand"
4828 // (C) attempt to CAS() the residual back into *Lock over null.
4829 // If there were any newly arrived threads and the CAS() would fail.
4830 // In that case Release() would detach the RATs, re-merge the list in-hand
4831 // with the RATs and repeat as needed. Alternately, Release() might
4832 // detach and extract a successor, but then pass the residual list to the wakee.
4833 // The wakee would be responsible for reattaching and remerging before it
4834 // competed for the lock.
4835 //
4836 // Both "pop" and DMR are immune from ABA corruption -- there can be
4837 // multiple concurrent pushers, but only one popper or detacher.
4838 // This implementation pops from the head of the list. This is unfair,
4839 // but tends to provide excellent throughput as hot threads remain hot.
4840 // (We wake recently run threads first).
4841 //
4842 // All paths through muxRelease() will execute a CAS.
4843 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4844 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4845 // executed within the critical section are complete and globally visible before the
4846 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4847 void Thread::muxRelease(volatile intptr_t * Lock) {
4848 for (;;) {
4849 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4850 assert(w & LOCKBIT, "invariant");
4851 if (w == LOCKBIT) return;
4852 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4853 assert(List != NULL, "invariant");
4854 assert(List->OnList == intptr_t(Lock), "invariant");
4855 ParkEvent * const nxt = List->ListNext;
4856 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4857
4858 // The following CAS() releases the lock and pops the head element.
4859 // The CAS() also ratifies the previously fetched lock-word value.
4860 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4861 continue;
4862 }
4863 List->OnList = 0;
4864 OrderAccess::fence();
4865 List->unpark();
4866 return;
4867 }
4868 }
4869
4870
4871 void Threads::verify() {
4872 ALL_JAVA_THREADS(p) {
4873 p->verify();
4874 }
4875 VMThread* thread = VMThread::vm_thread();
4876 if (thread != NULL) thread->verify();
4877 }