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/fprofiler.hpp"
67 #include "runtime/frame.inline.hpp"
68 #include "runtime/globals.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/sharedRuntime.hpp"
82 #include "runtime/statSampler.hpp"
83 #include "runtime/stubRoutines.hpp"
84 #include "runtime/sweeper.hpp"
85 #include "runtime/task.hpp"
86 #include "runtime/thread.inline.hpp"
87 #include "runtime/threadCritical.hpp"
88 #include "runtime/vframe.hpp"
89 #include "runtime/vframeArray.hpp"
90 #include "runtime/vframe_hp.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "runtime/vm_operations.hpp"
93 #include "runtime/vm_version.hpp"
94 #include "services/attachListener.hpp"
95 #include "services/management.hpp"
96 #include "services/memTracker.hpp"
97 #include "services/threadService.hpp"
98 #include "trace/traceMacros.hpp"
99 #include "trace/tracing.hpp"
100 #include "utilities/align.hpp"
101 #include "utilities/defaultStream.hpp"
102 #include "utilities/dtrace.hpp"
103 #include "utilities/events.hpp"
104 #include "utilities/macros.hpp"
105 #include "utilities/preserveException.hpp"
106 #include "utilities/vmError.hpp"
107 #if INCLUDE_ALL_GCS
108 #include "gc/cms/concurrentMarkSweepThread.hpp"
109 #include "gc/g1/concurrentMarkThread.inline.hpp"
110 #include "gc/parallel/pcTasks.hpp"
111 #endif // INCLUDE_ALL_GCS
112 #if INCLUDE_JVMCI
113 #include "jvmci/jvmciCompiler.hpp"
114 #include "jvmci/jvmciRuntime.hpp"
115 #include "logging/logHandle.hpp"
116 #endif
117 #ifdef COMPILER1
118 #include "c1/c1_Compiler.hpp"
119 #endif
120 #ifdef COMPILER2
121 #include "opto/c2compiler.hpp"
122 #include "opto/idealGraphPrinter.hpp"
123 #endif
124 #if INCLUDE_RTM_OPT
125 #include "runtime/rtmLocking.hpp"
126 #endif
127
128 // Initialization after module runtime initialization
129 void universe_post_module_init(); // must happen after call_initPhase2
130
131 #ifdef DTRACE_ENABLED
132
133 // Only bother with this argument setup if dtrace is available
134
135 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
136 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
137
138 #define DTRACE_THREAD_PROBE(probe, javathread) \
139 { \
140 ResourceMark rm(this); \
141 int len = 0; \
142 const char* name = (javathread)->get_thread_name(); \
143 len = strlen(name); \
144 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
145 (char *) name, len, \
146 java_lang_Thread::thread_id((javathread)->threadObj()), \
147 (uintptr_t) (javathread)->osthread()->thread_id(), \
148 java_lang_Thread::is_daemon((javathread)->threadObj())); \
149 }
150
151 #else // ndef DTRACE_ENABLED
152
153 #define DTRACE_THREAD_PROBE(probe, javathread)
154
155 #endif // ndef DTRACE_ENABLED
156
157 #ifndef USE_LIBRARY_BASED_TLS_ONLY
158 // Current thread is maintained as a thread-local variable
159 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
160 #endif
161 // Class hierarchy
162 // - Thread
163 // - VMThread
164 // - WatcherThread
165 // - ConcurrentMarkSweepThread
166 // - JavaThread
167 // - CompilerThread
168
169 // ======= Thread ========
170 // Support for forcing alignment of thread objects for biased locking
171 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
172 if (UseBiasedLocking) {
173 const int alignment = markOopDesc::biased_lock_alignment;
174 size_t aligned_size = size + (alignment - sizeof(intptr_t));
175 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
176 : AllocateHeap(aligned_size, flags, CURRENT_PC,
177 AllocFailStrategy::RETURN_NULL);
178 void* aligned_addr = align_up(real_malloc_addr, alignment);
179 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
180 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
181 "JavaThread alignment code overflowed allocated storage");
182 if (aligned_addr != real_malloc_addr) {
183 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
184 p2i(real_malloc_addr),
185 p2i(aligned_addr));
186 }
187 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
188 return aligned_addr;
189 } else {
190 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
191 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
192 }
193 }
194
195 void Thread::operator delete(void* p) {
196 if (UseBiasedLocking) {
197 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
198 FreeHeap(real_malloc_addr);
199 } else {
200 FreeHeap(p);
201 }
202 }
203
204
205 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
206 // JavaThread
207
208
209 Thread::Thread() {
210 // stack and get_thread
211 set_stack_base(NULL);
212 set_stack_size(0);
213 set_self_raw_id(0);
214 set_lgrp_id(-1);
215 DEBUG_ONLY(clear_suspendible_thread();)
216
217 // allocated data structures
218 set_osthread(NULL);
219 set_resource_area(new (mtThread)ResourceArea());
220 DEBUG_ONLY(_current_resource_mark = NULL;)
221 set_handle_area(new (mtThread) HandleArea(NULL));
222 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
223 set_active_handles(NULL);
224 set_free_handle_block(NULL);
225 set_last_handle_mark(NULL);
226
227 // This initial value ==> never claimed.
228 _oops_do_parity = 0;
229
230 // the handle mark links itself to last_handle_mark
231 new HandleMark(this);
232
233 // plain initialization
234 debug_only(_owned_locks = NULL;)
235 debug_only(_allow_allocation_count = 0;)
236 NOT_PRODUCT(_allow_safepoint_count = 0;)
237 NOT_PRODUCT(_skip_gcalot = false;)
238 _jvmti_env_iteration_count = 0;
239 set_allocated_bytes(0);
240 _vm_operation_started_count = 0;
241 _vm_operation_completed_count = 0;
242 _current_pending_monitor = NULL;
243 _current_pending_monitor_is_from_java = true;
244 _current_waiting_monitor = NULL;
245 _num_nested_signal = 0;
246 omFreeList = NULL;
247 omFreeCount = 0;
248 omFreeProvision = 32;
249 omInUseList = NULL;
250 omInUseCount = 0;
251
252 #ifdef ASSERT
253 _visited_for_critical_count = false;
254 #endif
255
256 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
257 Monitor::_safepoint_check_sometimes);
258 _suspend_flags = 0;
259
260 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
261 _hashStateX = os::random();
262 _hashStateY = 842502087;
263 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
264 _hashStateW = 273326509;
265
266 _OnTrap = 0;
267 _schedctl = NULL;
268 _Stalled = 0;
269 _TypeTag = 0x2BAD;
270
271 // Many of the following fields are effectively final - immutable
272 // Note that nascent threads can't use the Native Monitor-Mutex
273 // construct until the _MutexEvent is initialized ...
274 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
275 // we might instead use a stack of ParkEvents that we could provision on-demand.
276 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
277 // and ::Release()
278 _ParkEvent = ParkEvent::Allocate(this);
279 _SleepEvent = ParkEvent::Allocate(this);
280 _MutexEvent = ParkEvent::Allocate(this);
281 _MuxEvent = ParkEvent::Allocate(this);
282
283 #ifdef CHECK_UNHANDLED_OOPS
284 if (CheckUnhandledOops) {
285 _unhandled_oops = new UnhandledOops(this);
286 }
287 #endif // CHECK_UNHANDLED_OOPS
288 #ifdef ASSERT
289 if (UseBiasedLocking) {
290 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
291 assert(this == _real_malloc_address ||
292 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
293 "bug in forced alignment of thread objects");
294 }
295 #endif // ASSERT
296 }
297
298 void Thread::initialize_thread_current() {
299 #ifndef USE_LIBRARY_BASED_TLS_ONLY
300 assert(_thr_current == NULL, "Thread::current already initialized");
301 _thr_current = this;
302 #endif
303 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
304 ThreadLocalStorage::set_thread(this);
305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
306 }
307
308 void Thread::clear_thread_current() {
309 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
310 #ifndef USE_LIBRARY_BASED_TLS_ONLY
311 _thr_current = NULL;
312 #endif
313 ThreadLocalStorage::set_thread(NULL);
314 }
315
316 void Thread::record_stack_base_and_size() {
317 set_stack_base(os::current_stack_base());
318 set_stack_size(os::current_stack_size());
319 // CR 7190089: on Solaris, primordial thread's stack is adjusted
320 // in initialize_thread(). Without the adjustment, stack size is
321 // incorrect if stack is set to unlimited (ulimit -s unlimited).
322 // So far, only Solaris has real implementation of initialize_thread().
323 //
324 // set up any platform-specific state.
325 os::initialize_thread(this);
326
327 // Set stack limits after thread is initialized.
328 if (is_Java_thread()) {
329 ((JavaThread*) this)->set_stack_overflow_limit();
330 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
331 }
332 #if INCLUDE_NMT
333 // record thread's native stack, stack grows downward
334 MemTracker::record_thread_stack(stack_end(), stack_size());
335 #endif // INCLUDE_NMT
336 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
337 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
338 os::current_thread_id(), p2i(stack_base() - stack_size()),
339 p2i(stack_base()), stack_size()/1024);
340 }
341
342
343 Thread::~Thread() {
344 EVENT_THREAD_DESTRUCT(this);
345
346 // stack_base can be NULL if the thread is never started or exited before
347 // record_stack_base_and_size called. Although, we would like to ensure
348 // that all started threads do call record_stack_base_and_size(), there is
349 // not proper way to enforce that.
350 #if INCLUDE_NMT
351 if (_stack_base != NULL) {
352 MemTracker::release_thread_stack(stack_end(), stack_size());
353 #ifdef ASSERT
354 set_stack_base(NULL);
355 #endif
356 }
357 #endif // INCLUDE_NMT
358
359 // deallocate data structures
360 delete resource_area();
361 // since the handle marks are using the handle area, we have to deallocated the root
362 // handle mark before deallocating the thread's handle area,
363 assert(last_handle_mark() != NULL, "check we have an element");
364 delete last_handle_mark();
365 assert(last_handle_mark() == NULL, "check we have reached the end");
366
367 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
368 // We NULL out the fields for good hygiene.
369 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
370 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
371 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
372 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
373
374 delete handle_area();
375 delete metadata_handles();
376
377 // SR_handler uses this as a termination indicator -
378 // needs to happen before os::free_thread()
379 delete _SR_lock;
380 _SR_lock = NULL;
381
382 // osthread() can be NULL, if creation of thread failed.
383 if (osthread() != NULL) os::free_thread(osthread());
384
385 // clear Thread::current if thread is deleting itself.
386 // Needed to ensure JNI correctly detects non-attached threads.
387 if (this == Thread::current()) {
388 clear_thread_current();
389 }
390
391 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
392 }
393
394 // NOTE: dummy function for assertion purpose.
395 void Thread::run() {
396 ShouldNotReachHere();
397 }
398
399 #ifdef ASSERT
400 // Private method to check for dangling thread pointer
401 void check_for_dangling_thread_pointer(Thread *thread) {
402 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
403 "possibility of dangling Thread pointer");
404 }
405 #endif
406
407 ThreadPriority Thread::get_priority(const Thread* const thread) {
408 ThreadPriority priority;
409 // Can return an error!
410 (void)os::get_priority(thread, priority);
411 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
412 return priority;
413 }
414
415 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
416 debug_only(check_for_dangling_thread_pointer(thread);)
417 // Can return an error!
418 (void)os::set_priority(thread, priority);
419 }
420
421
422 void Thread::start(Thread* thread) {
423 // Start is different from resume in that its safety is guaranteed by context or
424 // being called from a Java method synchronized on the Thread object.
425 if (!DisableStartThread) {
426 if (thread->is_Java_thread()) {
427 // Initialize the thread state to RUNNABLE before starting this thread.
428 // Can not set it after the thread started because we do not know the
429 // exact thread state at that time. It could be in MONITOR_WAIT or
430 // in SLEEPING or some other state.
431 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
432 java_lang_Thread::RUNNABLE);
433 }
434 os::start_thread(thread);
435 }
436 }
437
438 // Enqueue a VM_Operation to do the job for us - sometime later
439 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
440 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
441 VMThread::execute(vm_stop);
442 }
443
444
445 // Check if an external suspend request has completed (or has been
446 // cancelled). Returns true if the thread is externally suspended and
447 // false otherwise.
448 //
449 // The bits parameter returns information about the code path through
450 // the routine. Useful for debugging:
451 //
452 // set in is_ext_suspend_completed():
453 // 0x00000001 - routine was entered
454 // 0x00000010 - routine return false at end
455 // 0x00000100 - thread exited (return false)
456 // 0x00000200 - suspend request cancelled (return false)
457 // 0x00000400 - thread suspended (return true)
458 // 0x00001000 - thread is in a suspend equivalent state (return true)
459 // 0x00002000 - thread is native and walkable (return true)
460 // 0x00004000 - thread is native_trans and walkable (needed retry)
461 //
462 // set in wait_for_ext_suspend_completion():
463 // 0x00010000 - routine was entered
464 // 0x00020000 - suspend request cancelled before loop (return false)
465 // 0x00040000 - thread suspended before loop (return true)
466 // 0x00080000 - suspend request cancelled in loop (return false)
467 // 0x00100000 - thread suspended in loop (return true)
468 // 0x00200000 - suspend not completed during retry loop (return false)
469
470 // Helper class for tracing suspend wait debug bits.
471 //
472 // 0x00000100 indicates that the target thread exited before it could
473 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
474 // 0x00080000 each indicate a cancelled suspend request so they don't
475 // count as wait failures either.
476 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
477
478 class TraceSuspendDebugBits : public StackObj {
479 private:
480 JavaThread * jt;
481 bool is_wait;
482 bool called_by_wait; // meaningful when !is_wait
483 uint32_t * bits;
484
485 public:
486 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
487 uint32_t *_bits) {
488 jt = _jt;
489 is_wait = _is_wait;
490 called_by_wait = _called_by_wait;
491 bits = _bits;
492 }
493
494 ~TraceSuspendDebugBits() {
495 if (!is_wait) {
496 #if 1
497 // By default, don't trace bits for is_ext_suspend_completed() calls.
498 // That trace is very chatty.
499 return;
500 #else
501 if (!called_by_wait) {
502 // If tracing for is_ext_suspend_completed() is enabled, then only
503 // trace calls to it from wait_for_ext_suspend_completion()
504 return;
505 }
506 #endif
507 }
508
509 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
510 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
511 MutexLocker ml(Threads_lock); // needed for get_thread_name()
512 ResourceMark rm;
513
514 tty->print_cr(
515 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
516 jt->get_thread_name(), *bits);
517
518 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
519 }
520 }
521 }
522 };
523 #undef DEBUG_FALSE_BITS
524
525
526 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
527 uint32_t *bits) {
528 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
529
530 bool did_trans_retry = false; // only do thread_in_native_trans retry once
531 bool do_trans_retry; // flag to force the retry
532
533 *bits |= 0x00000001;
534
535 do {
536 do_trans_retry = false;
537
538 if (is_exiting()) {
539 // Thread is in the process of exiting. This is always checked
540 // first to reduce the risk of dereferencing a freed JavaThread.
541 *bits |= 0x00000100;
542 return false;
543 }
544
545 if (!is_external_suspend()) {
546 // Suspend request is cancelled. This is always checked before
547 // is_ext_suspended() to reduce the risk of a rogue resume
548 // confusing the thread that made the suspend request.
549 *bits |= 0x00000200;
550 return false;
551 }
552
553 if (is_ext_suspended()) {
554 // thread is suspended
555 *bits |= 0x00000400;
556 return true;
557 }
558
559 // Now that we no longer do hard suspends of threads running
560 // native code, the target thread can be changing thread state
561 // while we are in this routine:
562 //
563 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
564 //
565 // We save a copy of the thread state as observed at this moment
566 // and make our decision about suspend completeness based on the
567 // copy. This closes the race where the thread state is seen as
568 // _thread_in_native_trans in the if-thread_blocked check, but is
569 // seen as _thread_blocked in if-thread_in_native_trans check.
570 JavaThreadState save_state = thread_state();
571
572 if (save_state == _thread_blocked && is_suspend_equivalent()) {
573 // If the thread's state is _thread_blocked and this blocking
574 // condition is known to be equivalent to a suspend, then we can
575 // consider the thread to be externally suspended. This means that
576 // the code that sets _thread_blocked has been modified to do
577 // self-suspension if the blocking condition releases. We also
578 // used to check for CONDVAR_WAIT here, but that is now covered by
579 // the _thread_blocked with self-suspension check.
580 //
581 // Return true since we wouldn't be here unless there was still an
582 // external suspend request.
583 *bits |= 0x00001000;
584 return true;
585 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
586 // Threads running native code will self-suspend on native==>VM/Java
587 // transitions. If its stack is walkable (should always be the case
588 // unless this function is called before the actual java_suspend()
589 // call), then the wait is done.
590 *bits |= 0x00002000;
591 return true;
592 } else if (!called_by_wait && !did_trans_retry &&
593 save_state == _thread_in_native_trans &&
594 frame_anchor()->walkable()) {
595 // The thread is transitioning from thread_in_native to another
596 // thread state. check_safepoint_and_suspend_for_native_trans()
597 // will force the thread to self-suspend. If it hasn't gotten
598 // there yet we may have caught the thread in-between the native
599 // code check above and the self-suspend. Lucky us. If we were
600 // called by wait_for_ext_suspend_completion(), then it
601 // will be doing the retries so we don't have to.
602 //
603 // Since we use the saved thread state in the if-statement above,
604 // there is a chance that the thread has already transitioned to
605 // _thread_blocked by the time we get here. In that case, we will
606 // make a single unnecessary pass through the logic below. This
607 // doesn't hurt anything since we still do the trans retry.
608
609 *bits |= 0x00004000;
610
611 // Once the thread leaves thread_in_native_trans for another
612 // thread state, we break out of this retry loop. We shouldn't
613 // need this flag to prevent us from getting back here, but
614 // sometimes paranoia is good.
615 did_trans_retry = true;
616
617 // We wait for the thread to transition to a more usable state.
618 for (int i = 1; i <= SuspendRetryCount; i++) {
619 // We used to do an "os::yield_all(i)" call here with the intention
620 // that yielding would increase on each retry. However, the parameter
621 // is ignored on Linux which means the yield didn't scale up. Waiting
622 // on the SR_lock below provides a much more predictable scale up for
623 // the delay. It also provides a simple/direct point to check for any
624 // safepoint requests from the VMThread
625
626 // temporarily drops SR_lock while doing wait with safepoint check
627 // (if we're a JavaThread - the WatcherThread can also call this)
628 // and increase delay with each retry
629 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
630
631 // check the actual thread state instead of what we saved above
632 if (thread_state() != _thread_in_native_trans) {
633 // the thread has transitioned to another thread state so
634 // try all the checks (except this one) one more time.
635 do_trans_retry = true;
636 break;
637 }
638 } // end retry loop
639
640
641 }
642 } while (do_trans_retry);
643
644 *bits |= 0x00000010;
645 return false;
646 }
647
648 // Wait for an external suspend request to complete (or be cancelled).
649 // Returns true if the thread is externally suspended and false otherwise.
650 //
651 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
652 uint32_t *bits) {
653 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
654 false /* !called_by_wait */, bits);
655
656 // local flag copies to minimize SR_lock hold time
657 bool is_suspended;
658 bool pending;
659 uint32_t reset_bits;
660
661 // set a marker so is_ext_suspend_completed() knows we are the caller
662 *bits |= 0x00010000;
663
664 // We use reset_bits to reinitialize the bits value at the top of
665 // each retry loop. This allows the caller to make use of any
666 // unused bits for their own marking purposes.
667 reset_bits = *bits;
668
669 {
670 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
671 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
672 delay, bits);
673 pending = is_external_suspend();
674 }
675 // must release SR_lock to allow suspension to complete
676
677 if (!pending) {
678 // A cancelled suspend request is the only false return from
679 // is_ext_suspend_completed() that keeps us from entering the
680 // retry loop.
681 *bits |= 0x00020000;
682 return false;
683 }
684
685 if (is_suspended) {
686 *bits |= 0x00040000;
687 return true;
688 }
689
690 for (int i = 1; i <= retries; i++) {
691 *bits = reset_bits; // reinit to only track last retry
692
693 // We used to do an "os::yield_all(i)" call here with the intention
694 // that yielding would increase on each retry. However, the parameter
695 // is ignored on Linux which means the yield didn't scale up. Waiting
696 // on the SR_lock below provides a much more predictable scale up for
697 // the delay. It also provides a simple/direct point to check for any
698 // safepoint requests from the VMThread
699
700 {
701 MutexLocker ml(SR_lock());
702 // wait with safepoint check (if we're a JavaThread - the WatcherThread
703 // can also call this) and increase delay with each retry
704 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
705
706 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
707 delay, bits);
708
709 // It is possible for the external suspend request to be cancelled
710 // (by a resume) before the actual suspend operation is completed.
711 // Refresh our local copy to see if we still need to wait.
712 pending = is_external_suspend();
713 }
714
715 if (!pending) {
716 // A cancelled suspend request is the only false return from
717 // is_ext_suspend_completed() that keeps us from staying in the
718 // retry loop.
719 *bits |= 0x00080000;
720 return false;
721 }
722
723 if (is_suspended) {
724 *bits |= 0x00100000;
725 return true;
726 }
727 } // end retry loop
728
729 // thread did not suspend after all our retries
730 *bits |= 0x00200000;
731 return false;
732 }
733
734 #ifndef PRODUCT
735 void JavaThread::record_jump(address target, address instr, const char* file,
736 int line) {
737
738 // This should not need to be atomic as the only way for simultaneous
739 // updates is via interrupts. Even then this should be rare or non-existent
740 // and we don't care that much anyway.
741
742 int index = _jmp_ring_index;
743 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
744 _jmp_ring[index]._target = (intptr_t) target;
745 _jmp_ring[index]._instruction = (intptr_t) instr;
746 _jmp_ring[index]._file = file;
747 _jmp_ring[index]._line = line;
748 }
749 #endif // PRODUCT
750
751 // Called by flat profiler
752 // Callers have already called wait_for_ext_suspend_completion
753 // The assertion for that is currently too complex to put here:
754 bool JavaThread::profile_last_Java_frame(frame* _fr) {
755 bool gotframe = false;
756 // self suspension saves needed state.
757 if (has_last_Java_frame() && _anchor.walkable()) {
758 *_fr = pd_last_frame();
759 gotframe = true;
760 }
761 return gotframe;
762 }
763
764 void Thread::interrupt(Thread* thread) {
765 debug_only(check_for_dangling_thread_pointer(thread);)
766 os::interrupt(thread);
767 }
768
769 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
770 debug_only(check_for_dangling_thread_pointer(thread);)
771 // Note: If clear_interrupted==false, this simply fetches and
772 // returns the value of the field osthread()->interrupted().
773 return os::is_interrupted(thread, clear_interrupted);
774 }
775
776
777 // GC Support
778 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
779 jint thread_parity = _oops_do_parity;
780 if (thread_parity != strong_roots_parity) {
781 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
782 if (res == thread_parity) {
783 return true;
784 } else {
785 guarantee(res == strong_roots_parity, "Or else what?");
786 return false;
787 }
788 }
789 return false;
790 }
791
792 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
793 active_handles()->oops_do(f);
794 // Do oop for ThreadShadow
795 f->do_oop((oop*)&_pending_exception);
796 handle_area()->oops_do(f);
797
798 if (MonitorInUseLists) {
799 // When using thread local monitor lists, we scan them here,
800 // and the remaining global monitors in ObjectSynchronizer::oops_do().
801 ObjectSynchronizer::thread_local_used_oops_do(this, f);
802 }
803 }
804
805 void Thread::metadata_handles_do(void f(Metadata*)) {
806 // Only walk the Handles in Thread.
807 if (metadata_handles() != NULL) {
808 for (int i = 0; i< metadata_handles()->length(); i++) {
809 f(metadata_handles()->at(i));
810 }
811 }
812 }
813
814 void Thread::print_on(outputStream* st) const {
815 // get_priority assumes osthread initialized
816 if (osthread() != NULL) {
817 int os_prio;
818 if (os::get_native_priority(this, &os_prio) == OS_OK) {
819 st->print("os_prio=%d ", os_prio);
820 }
821 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
822 ext().print_on(st);
823 osthread()->print_on(st);
824 }
825 debug_only(if (WizardMode) print_owned_locks_on(st);)
826 }
827
828 // Thread::print_on_error() is called by fatal error handler. Don't use
829 // any lock or allocate memory.
830 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
831 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
832
833 if (is_VM_thread()) { st->print("VMThread"); }
834 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
835 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
836 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
837 else { st->print("Thread"); }
838
839 if (is_Named_thread()) {
840 st->print(" \"%s\"", name());
841 }
842
843 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
844 p2i(stack_end()), p2i(stack_base()));
845
846 if (osthread()) {
847 st->print(" [id=%d]", osthread()->thread_id());
848 }
849 }
850
851 #ifdef ASSERT
852 void Thread::print_owned_locks_on(outputStream* st) const {
853 Monitor *cur = _owned_locks;
854 if (cur == NULL) {
855 st->print(" (no locks) ");
856 } else {
857 st->print_cr(" Locks owned:");
858 while (cur) {
859 cur->print_on(st);
860 cur = cur->next();
861 }
862 }
863 }
864
865 static int ref_use_count = 0;
866
867 bool Thread::owns_locks_but_compiled_lock() const {
868 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
869 if (cur != Compile_lock) return true;
870 }
871 return false;
872 }
873
874
875 #endif
876
877 #ifndef PRODUCT
878
879 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
880 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
881 // no threads which allow_vm_block's are held
882 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
883 // Check if current thread is allowed to block at a safepoint
884 if (!(_allow_safepoint_count == 0)) {
885 fatal("Possible safepoint reached by thread that does not allow it");
886 }
887 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
888 fatal("LEAF method calling lock?");
889 }
890
891 #ifdef ASSERT
892 if (potential_vm_operation && is_Java_thread()
893 && !Universe::is_bootstrapping()) {
894 // Make sure we do not hold any locks that the VM thread also uses.
895 // This could potentially lead to deadlocks
896 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
897 // Threads_lock is special, since the safepoint synchronization will not start before this is
898 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
899 // since it is used to transfer control between JavaThreads and the VMThread
900 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
901 if ((cur->allow_vm_block() &&
902 cur != Threads_lock &&
903 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
904 cur != VMOperationRequest_lock &&
905 cur != VMOperationQueue_lock) ||
906 cur->rank() == Mutex::special) {
907 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
908 }
909 }
910 }
911
912 if (GCALotAtAllSafepoints) {
913 // We could enter a safepoint here and thus have a gc
914 InterfaceSupport::check_gc_alot();
915 }
916 #endif
917 }
918 #endif
919
920 bool Thread::is_in_stack(address adr) const {
921 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
922 address end = os::current_stack_pointer();
923 // Allow non Java threads to call this without stack_base
924 if (_stack_base == NULL) return true;
925 if (stack_base() >= adr && adr >= end) return true;
926
927 return false;
928 }
929
930 bool Thread::is_in_usable_stack(address adr) const {
931 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
932 size_t usable_stack_size = _stack_size - stack_guard_size;
933
934 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
935 }
936
937
938 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
939 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
940 // used for compilation in the future. If that change is made, the need for these methods
941 // should be revisited, and they should be removed if possible.
942
943 bool Thread::is_lock_owned(address adr) const {
944 return on_local_stack(adr);
945 }
946
947 bool Thread::set_as_starting_thread() {
948 // NOTE: this must be called inside the main thread.
949 return os::create_main_thread((JavaThread*)this);
950 }
951
952 static void initialize_class(Symbol* class_name, TRAPS) {
953 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
954 InstanceKlass::cast(klass)->initialize(CHECK);
955 }
956
957
958 // Creates the initial ThreadGroup
959 static Handle create_initial_thread_group(TRAPS) {
960 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
961 InstanceKlass* ik = InstanceKlass::cast(k);
962
963 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
964 {
965 JavaValue result(T_VOID);
966 JavaCalls::call_special(&result,
967 system_instance,
968 ik,
969 vmSymbols::object_initializer_name(),
970 vmSymbols::void_method_signature(),
971 CHECK_NH);
972 }
973 Universe::set_system_thread_group(system_instance());
974
975 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
976 {
977 JavaValue result(T_VOID);
978 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
979 JavaCalls::call_special(&result,
980 main_instance,
981 ik,
982 vmSymbols::object_initializer_name(),
983 vmSymbols::threadgroup_string_void_signature(),
984 system_instance,
985 string,
986 CHECK_NH);
987 }
988 return main_instance;
989 }
990
991 // Creates the initial Thread
992 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
993 TRAPS) {
994 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
995 InstanceKlass* ik = InstanceKlass::cast(k);
996 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
997
998 java_lang_Thread::set_thread(thread_oop(), thread);
999 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1000 thread->set_threadObj(thread_oop());
1001
1002 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1003
1004 JavaValue result(T_VOID);
1005 JavaCalls::call_special(&result, thread_oop,
1006 ik,
1007 vmSymbols::object_initializer_name(),
1008 vmSymbols::threadgroup_string_void_signature(),
1009 thread_group,
1010 string,
1011 CHECK_NULL);
1012 return thread_oop();
1013 }
1014
1015 char java_runtime_name[128] = "";
1016 char java_runtime_version[128] = "";
1017
1018 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1019 static const char* get_java_runtime_name(TRAPS) {
1020 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1021 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1022 fieldDescriptor fd;
1023 bool found = k != NULL &&
1024 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1025 vmSymbols::string_signature(), &fd);
1026 if (found) {
1027 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1028 if (name_oop == NULL) {
1029 return NULL;
1030 }
1031 const char* name = java_lang_String::as_utf8_string(name_oop,
1032 java_runtime_name,
1033 sizeof(java_runtime_name));
1034 return name;
1035 } else {
1036 return NULL;
1037 }
1038 }
1039
1040 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1041 static const char* get_java_runtime_version(TRAPS) {
1042 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1043 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1044 fieldDescriptor fd;
1045 bool found = k != NULL &&
1046 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1047 vmSymbols::string_signature(), &fd);
1048 if (found) {
1049 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1050 if (name_oop == NULL) {
1051 return NULL;
1052 }
1053 const char* name = java_lang_String::as_utf8_string(name_oop,
1054 java_runtime_version,
1055 sizeof(java_runtime_version));
1056 return name;
1057 } else {
1058 return NULL;
1059 }
1060 }
1061
1062 // General purpose hook into Java code, run once when the VM is initialized.
1063 // The Java library method itself may be changed independently from the VM.
1064 static void call_postVMInitHook(TRAPS) {
1065 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1066 if (klass != NULL) {
1067 JavaValue result(T_VOID);
1068 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1069 vmSymbols::void_method_signature(),
1070 CHECK);
1071 }
1072 }
1073
1074 static void reset_vm_info_property(TRAPS) {
1075 // the vm info string
1076 ResourceMark rm(THREAD);
1077 const char *vm_info = VM_Version::vm_info_string();
1078
1079 // java.lang.System class
1080 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1081
1082 // setProperty arguments
1083 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1084 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1085
1086 // return value
1087 JavaValue r(T_OBJECT);
1088
1089 // public static String setProperty(String key, String value);
1090 JavaCalls::call_static(&r,
1091 klass,
1092 vmSymbols::setProperty_name(),
1093 vmSymbols::string_string_string_signature(),
1094 key_str,
1095 value_str,
1096 CHECK);
1097 }
1098
1099
1100 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1101 bool daemon, TRAPS) {
1102 assert(thread_group.not_null(), "thread group should be specified");
1103 assert(threadObj() == NULL, "should only create Java thread object once");
1104
1105 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1106 InstanceKlass* ik = InstanceKlass::cast(k);
1107 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1108
1109 java_lang_Thread::set_thread(thread_oop(), this);
1110 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1111 set_threadObj(thread_oop());
1112
1113 JavaValue result(T_VOID);
1114 if (thread_name != NULL) {
1115 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1116 // Thread gets assigned specified name and null target
1117 JavaCalls::call_special(&result,
1118 thread_oop,
1119 ik,
1120 vmSymbols::object_initializer_name(),
1121 vmSymbols::threadgroup_string_void_signature(),
1122 thread_group, // Argument 1
1123 name, // Argument 2
1124 THREAD);
1125 } else {
1126 // Thread gets assigned name "Thread-nnn" and null target
1127 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1128 JavaCalls::call_special(&result,
1129 thread_oop,
1130 ik,
1131 vmSymbols::object_initializer_name(),
1132 vmSymbols::threadgroup_runnable_void_signature(),
1133 thread_group, // Argument 1
1134 Handle(), // Argument 2
1135 THREAD);
1136 }
1137
1138
1139 if (daemon) {
1140 java_lang_Thread::set_daemon(thread_oop());
1141 }
1142
1143 if (HAS_PENDING_EXCEPTION) {
1144 return;
1145 }
1146
1147 Klass* group = SystemDictionary::ThreadGroup_klass();
1148 Handle threadObj(THREAD, this->threadObj());
1149
1150 JavaCalls::call_special(&result,
1151 thread_group,
1152 group,
1153 vmSymbols::add_method_name(),
1154 vmSymbols::thread_void_signature(),
1155 threadObj, // Arg 1
1156 THREAD);
1157 }
1158
1159 // NamedThread -- non-JavaThread subclasses with multiple
1160 // uniquely named instances should derive from this.
1161 NamedThread::NamedThread() : Thread() {
1162 _name = NULL;
1163 _processed_thread = NULL;
1164 _gc_id = GCId::undefined();
1165 }
1166
1167 NamedThread::~NamedThread() {
1168 if (_name != NULL) {
1169 FREE_C_HEAP_ARRAY(char, _name);
1170 _name = NULL;
1171 }
1172 }
1173
1174 void NamedThread::set_name(const char* format, ...) {
1175 guarantee(_name == NULL, "Only get to set name once.");
1176 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1177 guarantee(_name != NULL, "alloc failure");
1178 va_list ap;
1179 va_start(ap, format);
1180 jio_vsnprintf(_name, max_name_len, format, ap);
1181 va_end(ap);
1182 }
1183
1184 void NamedThread::initialize_named_thread() {
1185 set_native_thread_name(name());
1186 }
1187
1188 void NamedThread::print_on(outputStream* st) const {
1189 st->print("\"%s\" ", name());
1190 Thread::print_on(st);
1191 st->cr();
1192 }
1193
1194
1195 // ======= WatcherThread ========
1196
1197 // The watcher thread exists to simulate timer interrupts. It should
1198 // be replaced by an abstraction over whatever native support for
1199 // timer interrupts exists on the platform.
1200
1201 WatcherThread* WatcherThread::_watcher_thread = NULL;
1202 bool WatcherThread::_startable = false;
1203 volatile bool WatcherThread::_should_terminate = false;
1204
1205 WatcherThread::WatcherThread() : Thread() {
1206 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1207 if (os::create_thread(this, os::watcher_thread)) {
1208 _watcher_thread = this;
1209
1210 // Set the watcher thread to the highest OS priority which should not be
1211 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1212 // is created. The only normal thread using this priority is the reference
1213 // handler thread, which runs for very short intervals only.
1214 // If the VMThread's priority is not lower than the WatcherThread profiling
1215 // will be inaccurate.
1216 os::set_priority(this, MaxPriority);
1217 if (!DisableStartThread) {
1218 os::start_thread(this);
1219 }
1220 }
1221 }
1222
1223 int WatcherThread::sleep() const {
1224 // The WatcherThread does not participate in the safepoint protocol
1225 // for the PeriodicTask_lock because it is not a JavaThread.
1226 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1227
1228 if (_should_terminate) {
1229 // check for termination before we do any housekeeping or wait
1230 return 0; // we did not sleep.
1231 }
1232
1233 // remaining will be zero if there are no tasks,
1234 // causing the WatcherThread to sleep until a task is
1235 // enrolled
1236 int remaining = PeriodicTask::time_to_wait();
1237 int time_slept = 0;
1238
1239 // we expect this to timeout - we only ever get unparked when
1240 // we should terminate or when a new task has been enrolled
1241 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1242
1243 jlong time_before_loop = os::javaTimeNanos();
1244
1245 while (true) {
1246 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1247 remaining);
1248 jlong now = os::javaTimeNanos();
1249
1250 if (remaining == 0) {
1251 // if we didn't have any tasks we could have waited for a long time
1252 // consider the time_slept zero and reset time_before_loop
1253 time_slept = 0;
1254 time_before_loop = now;
1255 } else {
1256 // need to recalculate since we might have new tasks in _tasks
1257 time_slept = (int) ((now - time_before_loop) / 1000000);
1258 }
1259
1260 // Change to task list or spurious wakeup of some kind
1261 if (timedout || _should_terminate) {
1262 break;
1263 }
1264
1265 remaining = PeriodicTask::time_to_wait();
1266 if (remaining == 0) {
1267 // Last task was just disenrolled so loop around and wait until
1268 // another task gets enrolled
1269 continue;
1270 }
1271
1272 remaining -= time_slept;
1273 if (remaining <= 0) {
1274 break;
1275 }
1276 }
1277
1278 return time_slept;
1279 }
1280
1281 void WatcherThread::run() {
1282 assert(this == watcher_thread(), "just checking");
1283
1284 this->record_stack_base_and_size();
1285 this->set_native_thread_name(this->name());
1286 this->set_active_handles(JNIHandleBlock::allocate_block());
1287 while (true) {
1288 assert(watcher_thread() == Thread::current(), "thread consistency check");
1289 assert(watcher_thread() == this, "thread consistency check");
1290
1291 // Calculate how long it'll be until the next PeriodicTask work
1292 // should be done, and sleep that amount of time.
1293 int time_waited = sleep();
1294
1295 if (VMError::is_error_reported()) {
1296 // A fatal error has happened, the error handler(VMError::report_and_die)
1297 // should abort JVM after creating an error log file. However in some
1298 // rare cases, the error handler itself might deadlock. Here periodically
1299 // check for error reporting timeouts, and if it happens, just proceed to
1300 // abort the VM.
1301
1302 // This code is in WatcherThread because WatcherThread wakes up
1303 // periodically so the fatal error handler doesn't need to do anything;
1304 // also because the WatcherThread is less likely to crash than other
1305 // threads.
1306
1307 for (;;) {
1308 // Note: we use naked sleep in this loop because we want to avoid using
1309 // any kind of VM infrastructure which may be broken at this point.
1310 if (VMError::check_timeout()) {
1311 // We hit error reporting timeout. Error reporting was interrupted and
1312 // will be wrapping things up now (closing files etc). Give it some more
1313 // time, then quit the VM.
1314 os::naked_short_sleep(200);
1315 // Print a message to stderr.
1316 fdStream err(defaultStream::output_fd());
1317 err.print_raw_cr("# [ timer expired, abort... ]");
1318 // skip atexit/vm_exit/vm_abort hooks
1319 os::die();
1320 }
1321
1322 // Wait a second, then recheck for timeout.
1323 os::naked_short_sleep(999);
1324 }
1325 }
1326
1327 if (_should_terminate) {
1328 // check for termination before posting the next tick
1329 break;
1330 }
1331
1332 PeriodicTask::real_time_tick(time_waited);
1333 }
1334
1335 // Signal that it is terminated
1336 {
1337 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1338 _watcher_thread = NULL;
1339 Terminator_lock->notify();
1340 }
1341 }
1342
1343 void WatcherThread::start() {
1344 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1345
1346 if (watcher_thread() == NULL && _startable) {
1347 _should_terminate = false;
1348 // Create the single instance of WatcherThread
1349 new WatcherThread();
1350 }
1351 }
1352
1353 void WatcherThread::make_startable() {
1354 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1355 _startable = true;
1356 }
1357
1358 void WatcherThread::stop() {
1359 {
1360 // Follow normal safepoint aware lock enter protocol since the
1361 // WatcherThread is stopped by another JavaThread.
1362 MutexLocker ml(PeriodicTask_lock);
1363 _should_terminate = true;
1364
1365 WatcherThread* watcher = watcher_thread();
1366 if (watcher != NULL) {
1367 // unpark the WatcherThread so it can see that it should terminate
1368 watcher->unpark();
1369 }
1370 }
1371
1372 MutexLocker mu(Terminator_lock);
1373
1374 while (watcher_thread() != NULL) {
1375 // This wait should make safepoint checks, wait without a timeout,
1376 // and wait as a suspend-equivalent condition.
1377 //
1378 // Note: If the FlatProfiler is running, then this thread is waiting
1379 // for the WatcherThread to terminate and the WatcherThread, via the
1380 // FlatProfiler task, is waiting for the external suspend request on
1381 // this thread to complete. wait_for_ext_suspend_completion() will
1382 // eventually timeout, but that takes time. Making this wait a
1383 // suspend-equivalent condition solves that timeout problem.
1384 //
1385 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1386 Mutex::_as_suspend_equivalent_flag);
1387 }
1388 }
1389
1390 void WatcherThread::unpark() {
1391 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1392 PeriodicTask_lock->notify();
1393 }
1394
1395 void WatcherThread::print_on(outputStream* st) const {
1396 st->print("\"%s\" ", name());
1397 Thread::print_on(st);
1398 st->cr();
1399 }
1400
1401 // ======= JavaThread ========
1402
1403 #if INCLUDE_JVMCI
1404
1405 jlong* JavaThread::_jvmci_old_thread_counters;
1406
1407 bool jvmci_counters_include(JavaThread* thread) {
1408 oop threadObj = thread->threadObj();
1409 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1410 }
1411
1412 void JavaThread::collect_counters(typeArrayOop array) {
1413 if (JVMCICounterSize > 0) {
1414 MutexLocker tl(Threads_lock);
1415 for (int i = 0; i < array->length(); i++) {
1416 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1417 }
1418 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1419 if (jvmci_counters_include(tp)) {
1420 for (int i = 0; i < array->length(); i++) {
1421 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1422 }
1423 }
1424 }
1425 }
1426 }
1427
1428 #endif // INCLUDE_JVMCI
1429
1430 // A JavaThread is a normal Java thread
1431
1432 void JavaThread::initialize() {
1433 // Initialize fields
1434
1435 set_saved_exception_pc(NULL);
1436 set_threadObj(NULL);
1437 _anchor.clear();
1438 set_entry_point(NULL);
1439 set_jni_functions(jni_functions());
1440 set_callee_target(NULL);
1441 set_vm_result(NULL);
1442 set_vm_result_2(NULL);
1443 set_vframe_array_head(NULL);
1444 set_vframe_array_last(NULL);
1445 set_deferred_locals(NULL);
1446 set_deopt_mark(NULL);
1447 set_deopt_compiled_method(NULL);
1448 clear_must_deopt_id();
1449 set_monitor_chunks(NULL);
1450 set_next(NULL);
1451 set_thread_state(_thread_new);
1452 _terminated = _not_terminated;
1453 _privileged_stack_top = NULL;
1454 _array_for_gc = NULL;
1455 _suspend_equivalent = false;
1456 _in_deopt_handler = 0;
1457 _doing_unsafe_access = false;
1458 _stack_guard_state = stack_guard_unused;
1459 #if INCLUDE_JVMCI
1460 _pending_monitorenter = false;
1461 _pending_deoptimization = -1;
1462 _pending_failed_speculation = NULL;
1463 _pending_transfer_to_interpreter = false;
1464 _adjusting_comp_level = false;
1465 _jvmci._alternate_call_target = NULL;
1466 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1467 if (JVMCICounterSize > 0) {
1468 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1469 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1470 } else {
1471 _jvmci_counters = NULL;
1472 }
1473 #endif // INCLUDE_JVMCI
1474 _reserved_stack_activation = NULL; // stack base not known yet
1475 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1476 _exception_pc = 0;
1477 _exception_handler_pc = 0;
1478 _is_method_handle_return = 0;
1479 _jvmti_thread_state= NULL;
1480 _should_post_on_exceptions_flag = JNI_FALSE;
1481 _jvmti_get_loaded_classes_closure = NULL;
1482 _interp_only_mode = 0;
1483 _special_runtime_exit_condition = _no_async_condition;
1484 _pending_async_exception = NULL;
1485 _thread_stat = NULL;
1486 _thread_stat = new ThreadStatistics();
1487 _blocked_on_compilation = false;
1488 _jni_active_critical = 0;
1489 _pending_jni_exception_check_fn = NULL;
1490 _do_not_unlock_if_synchronized = false;
1491 _cached_monitor_info = NULL;
1492 _parker = Parker::Allocate(this);
1493
1494 #ifndef PRODUCT
1495 _jmp_ring_index = 0;
1496 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1497 record_jump(NULL, NULL, NULL, 0);
1498 }
1499 #endif // PRODUCT
1500
1501 set_thread_profiler(NULL);
1502 if (FlatProfiler::is_active()) {
1503 // This is where we would decide to either give each thread it's own profiler
1504 // or use one global one from FlatProfiler,
1505 // or up to some count of the number of profiled threads, etc.
1506 ThreadProfiler* pp = new ThreadProfiler();
1507 pp->engage();
1508 set_thread_profiler(pp);
1509 }
1510
1511 // Setup safepoint state info for this thread
1512 ThreadSafepointState::create(this);
1513
1514 debug_only(_java_call_counter = 0);
1515
1516 // JVMTI PopFrame support
1517 _popframe_condition = popframe_inactive;
1518 _popframe_preserved_args = NULL;
1519 _popframe_preserved_args_size = 0;
1520 _frames_to_pop_failed_realloc = 0;
1521
1522 pd_initialize();
1523 }
1524
1525 #if INCLUDE_ALL_GCS
1526 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1527 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1528 #endif // INCLUDE_ALL_GCS
1529
1530 JavaThread::JavaThread(bool is_attaching_via_jni) :
1531 Thread()
1532 #if INCLUDE_ALL_GCS
1533 , _satb_mark_queue(&_satb_mark_queue_set),
1534 _dirty_card_queue(&_dirty_card_queue_set)
1535 #endif // INCLUDE_ALL_GCS
1536 {
1537 initialize();
1538 if (is_attaching_via_jni) {
1539 _jni_attach_state = _attaching_via_jni;
1540 } else {
1541 _jni_attach_state = _not_attaching_via_jni;
1542 }
1543 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1544 }
1545
1546 bool JavaThread::reguard_stack(address cur_sp) {
1547 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1548 && _stack_guard_state != stack_guard_reserved_disabled) {
1549 return true; // Stack already guarded or guard pages not needed.
1550 }
1551
1552 if (register_stack_overflow()) {
1553 // For those architectures which have separate register and
1554 // memory stacks, we must check the register stack to see if
1555 // it has overflowed.
1556 return false;
1557 }
1558
1559 // Java code never executes within the yellow zone: the latter is only
1560 // there to provoke an exception during stack banging. If java code
1561 // is executing there, either StackShadowPages should be larger, or
1562 // some exception code in c1, c2 or the interpreter isn't unwinding
1563 // when it should.
1564 guarantee(cur_sp > stack_reserved_zone_base(),
1565 "not enough space to reguard - increase StackShadowPages");
1566 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1567 enable_stack_yellow_reserved_zone();
1568 if (reserved_stack_activation() != stack_base()) {
1569 set_reserved_stack_activation(stack_base());
1570 }
1571 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1572 set_reserved_stack_activation(stack_base());
1573 enable_stack_reserved_zone();
1574 }
1575 return true;
1576 }
1577
1578 bool JavaThread::reguard_stack(void) {
1579 return reguard_stack(os::current_stack_pointer());
1580 }
1581
1582
1583 void JavaThread::block_if_vm_exited() {
1584 if (_terminated == _vm_exited) {
1585 // _vm_exited is set at safepoint, and Threads_lock is never released
1586 // we will block here forever
1587 Threads_lock->lock_without_safepoint_check();
1588 ShouldNotReachHere();
1589 }
1590 }
1591
1592
1593 // Remove this ifdef when C1 is ported to the compiler interface.
1594 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1595 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1596
1597 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1598 Thread()
1599 #if INCLUDE_ALL_GCS
1600 , _satb_mark_queue(&_satb_mark_queue_set),
1601 _dirty_card_queue(&_dirty_card_queue_set)
1602 #endif // INCLUDE_ALL_GCS
1603 {
1604 initialize();
1605 _jni_attach_state = _not_attaching_via_jni;
1606 set_entry_point(entry_point);
1607 // Create the native thread itself.
1608 // %note runtime_23
1609 os::ThreadType thr_type = os::java_thread;
1610 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1611 os::java_thread;
1612 os::create_thread(this, thr_type, stack_sz);
1613 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1614 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1615 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1616 // the exception consists of creating the exception object & initializing it, initialization
1617 // will leave the VM via a JavaCall and then all locks must be unlocked).
1618 //
1619 // The thread is still suspended when we reach here. Thread must be explicit started
1620 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1621 // by calling Threads:add. The reason why this is not done here, is because the thread
1622 // object must be fully initialized (take a look at JVM_Start)
1623 }
1624
1625 JavaThread::~JavaThread() {
1626
1627 // JSR166 -- return the parker to the free list
1628 Parker::Release(_parker);
1629 _parker = NULL;
1630
1631 // Free any remaining previous UnrollBlock
1632 vframeArray* old_array = vframe_array_last();
1633
1634 if (old_array != NULL) {
1635 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1636 old_array->set_unroll_block(NULL);
1637 delete old_info;
1638 delete old_array;
1639 }
1640
1641 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1642 if (deferred != NULL) {
1643 // This can only happen if thread is destroyed before deoptimization occurs.
1644 assert(deferred->length() != 0, "empty array!");
1645 do {
1646 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1647 deferred->remove_at(0);
1648 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1649 delete dlv;
1650 } while (deferred->length() != 0);
1651 delete deferred;
1652 }
1653
1654 // All Java related clean up happens in exit
1655 ThreadSafepointState::destroy(this);
1656 if (_thread_profiler != NULL) delete _thread_profiler;
1657 if (_thread_stat != NULL) delete _thread_stat;
1658
1659 #if INCLUDE_JVMCI
1660 if (JVMCICounterSize > 0) {
1661 if (jvmci_counters_include(this)) {
1662 for (int i = 0; i < JVMCICounterSize; i++) {
1663 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1664 }
1665 }
1666 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1667 }
1668 #endif // INCLUDE_JVMCI
1669 }
1670
1671
1672 // The first routine called by a new Java thread
1673 void JavaThread::run() {
1674 // initialize thread-local alloc buffer related fields
1675 this->initialize_tlab();
1676
1677 // used to test validity of stack trace backs
1678 this->record_base_of_stack_pointer();
1679
1680 // Record real stack base and size.
1681 this->record_stack_base_and_size();
1682
1683 this->create_stack_guard_pages();
1684
1685 this->cache_global_variables();
1686
1687 // Thread is now sufficient initialized to be handled by the safepoint code as being
1688 // in the VM. Change thread state from _thread_new to _thread_in_vm
1689 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1690
1691 assert(JavaThread::current() == this, "sanity check");
1692 assert(!Thread::current()->owns_locks(), "sanity check");
1693
1694 DTRACE_THREAD_PROBE(start, this);
1695
1696 // This operation might block. We call that after all safepoint checks for a new thread has
1697 // been completed.
1698 this->set_active_handles(JNIHandleBlock::allocate_block());
1699
1700 if (JvmtiExport::should_post_thread_life()) {
1701 JvmtiExport::post_thread_start(this);
1702 }
1703
1704 EventThreadStart event;
1705 if (event.should_commit()) {
1706 event.set_thread(THREAD_TRACE_ID(this));
1707 event.commit();
1708 }
1709
1710 // We call another function to do the rest so we are sure that the stack addresses used
1711 // from there will be lower than the stack base just computed
1712 thread_main_inner();
1713
1714 // Note, thread is no longer valid at this point!
1715 }
1716
1717
1718 void JavaThread::thread_main_inner() {
1719 assert(JavaThread::current() == this, "sanity check");
1720 assert(this->threadObj() != NULL, "just checking");
1721
1722 // Execute thread entry point unless this thread has a pending exception
1723 // or has been stopped before starting.
1724 // Note: Due to JVM_StopThread we can have pending exceptions already!
1725 if (!this->has_pending_exception() &&
1726 !java_lang_Thread::is_stillborn(this->threadObj())) {
1727 {
1728 ResourceMark rm(this);
1729 this->set_native_thread_name(this->get_thread_name());
1730 }
1731 HandleMark hm(this);
1732 this->entry_point()(this, this);
1733 }
1734
1735 DTRACE_THREAD_PROBE(stop, this);
1736
1737 this->exit(false);
1738 delete this;
1739 }
1740
1741
1742 static void ensure_join(JavaThread* thread) {
1743 // We do not need to grap the Threads_lock, since we are operating on ourself.
1744 Handle threadObj(thread, thread->threadObj());
1745 assert(threadObj.not_null(), "java thread object must exist");
1746 ObjectLocker lock(threadObj, thread);
1747 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1748 thread->clear_pending_exception();
1749 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1750 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1751 // Clear the native thread instance - this makes isAlive return false and allows the join()
1752 // to complete once we've done the notify_all below
1753 java_lang_Thread::set_thread(threadObj(), NULL);
1754 lock.notify_all(thread);
1755 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1756 thread->clear_pending_exception();
1757 }
1758
1759
1760 // For any new cleanup additions, please check to see if they need to be applied to
1761 // cleanup_failed_attach_current_thread as well.
1762 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1763 assert(this == JavaThread::current(), "thread consistency check");
1764
1765 HandleMark hm(this);
1766 Handle uncaught_exception(this, this->pending_exception());
1767 this->clear_pending_exception();
1768 Handle threadObj(this, this->threadObj());
1769 assert(threadObj.not_null(), "Java thread object should be created");
1770
1771 if (get_thread_profiler() != NULL) {
1772 get_thread_profiler()->disengage();
1773 ResourceMark rm;
1774 get_thread_profiler()->print(get_thread_name());
1775 }
1776
1777
1778 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1779 {
1780 EXCEPTION_MARK;
1781
1782 CLEAR_PENDING_EXCEPTION;
1783 }
1784 if (!destroy_vm) {
1785 if (uncaught_exception.not_null()) {
1786 EXCEPTION_MARK;
1787 // Call method Thread.dispatchUncaughtException().
1788 Klass* thread_klass = SystemDictionary::Thread_klass();
1789 JavaValue result(T_VOID);
1790 JavaCalls::call_virtual(&result,
1791 threadObj, thread_klass,
1792 vmSymbols::dispatchUncaughtException_name(),
1793 vmSymbols::throwable_void_signature(),
1794 uncaught_exception,
1795 THREAD);
1796 if (HAS_PENDING_EXCEPTION) {
1797 ResourceMark rm(this);
1798 jio_fprintf(defaultStream::error_stream(),
1799 "\nException: %s thrown from the UncaughtExceptionHandler"
1800 " in thread \"%s\"\n",
1801 pending_exception()->klass()->external_name(),
1802 get_thread_name());
1803 CLEAR_PENDING_EXCEPTION;
1804 }
1805 }
1806
1807 // Called before the java thread exit since we want to read info
1808 // from java_lang_Thread object
1809 EventThreadEnd event;
1810 if (event.should_commit()) {
1811 event.set_thread(THREAD_TRACE_ID(this));
1812 event.commit();
1813 }
1814
1815 // Call after last event on thread
1816 EVENT_THREAD_EXIT(this);
1817
1818 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1819 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1820 // is deprecated anyhow.
1821 if (!is_Compiler_thread()) {
1822 int count = 3;
1823 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1824 EXCEPTION_MARK;
1825 JavaValue result(T_VOID);
1826 Klass* thread_klass = SystemDictionary::Thread_klass();
1827 JavaCalls::call_virtual(&result,
1828 threadObj, thread_klass,
1829 vmSymbols::exit_method_name(),
1830 vmSymbols::void_method_signature(),
1831 THREAD);
1832 CLEAR_PENDING_EXCEPTION;
1833 }
1834 }
1835 // notify JVMTI
1836 if (JvmtiExport::should_post_thread_life()) {
1837 JvmtiExport::post_thread_end(this);
1838 }
1839
1840 // We have notified the agents that we are exiting, before we go on,
1841 // we must check for a pending external suspend request and honor it
1842 // in order to not surprise the thread that made the suspend request.
1843 while (true) {
1844 {
1845 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1846 if (!is_external_suspend()) {
1847 set_terminated(_thread_exiting);
1848 ThreadService::current_thread_exiting(this);
1849 break;
1850 }
1851 // Implied else:
1852 // Things get a little tricky here. We have a pending external
1853 // suspend request, but we are holding the SR_lock so we
1854 // can't just self-suspend. So we temporarily drop the lock
1855 // and then self-suspend.
1856 }
1857
1858 ThreadBlockInVM tbivm(this);
1859 java_suspend_self();
1860
1861 // We're done with this suspend request, but we have to loop around
1862 // and check again. Eventually we will get SR_lock without a pending
1863 // external suspend request and will be able to mark ourselves as
1864 // exiting.
1865 }
1866 // no more external suspends are allowed at this point
1867 } else {
1868 // before_exit() has already posted JVMTI THREAD_END events
1869 }
1870
1871 // Notify waiters on thread object. This has to be done after exit() is called
1872 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1873 // group should have the destroyed bit set before waiters are notified).
1874 ensure_join(this);
1875 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1876
1877 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1878 // held by this thread must be released. The spec does not distinguish
1879 // between JNI-acquired and regular Java monitors. We can only see
1880 // regular Java monitors here if monitor enter-exit matching is broken.
1881 //
1882 // Optionally release any monitors for regular JavaThread exits. This
1883 // is provided as a work around for any bugs in monitor enter-exit
1884 // matching. This can be expensive so it is not enabled by default.
1885 //
1886 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1887 // ObjectSynchronizer::release_monitors_owned_by_thread().
1888 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1889 // Sanity check even though JNI DetachCurrentThread() would have
1890 // returned JNI_ERR if there was a Java frame. JavaThread exit
1891 // should be done executing Java code by the time we get here.
1892 assert(!this->has_last_Java_frame(),
1893 "should not have a Java frame when detaching or exiting");
1894 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1895 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1896 }
1897
1898 // These things needs to be done while we are still a Java Thread. Make sure that thread
1899 // is in a consistent state, in case GC happens
1900 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1901
1902 if (active_handles() != NULL) {
1903 JNIHandleBlock* block = active_handles();
1904 set_active_handles(NULL);
1905 JNIHandleBlock::release_block(block);
1906 }
1907
1908 if (free_handle_block() != NULL) {
1909 JNIHandleBlock* block = free_handle_block();
1910 set_free_handle_block(NULL);
1911 JNIHandleBlock::release_block(block);
1912 }
1913
1914 // These have to be removed while this is still a valid thread.
1915 remove_stack_guard_pages();
1916
1917 if (UseTLAB) {
1918 tlab().make_parsable(true); // retire TLAB
1919 }
1920
1921 if (JvmtiEnv::environments_might_exist()) {
1922 JvmtiExport::cleanup_thread(this);
1923 }
1924
1925 // We must flush any deferred card marks before removing a thread from
1926 // the list of active threads.
1927 Universe::heap()->flush_deferred_store_barrier(this);
1928 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1929
1930 #if INCLUDE_ALL_GCS
1931 // We must flush the G1-related buffers before removing a thread
1932 // from the list of active threads. We must do this after any deferred
1933 // card marks have been flushed (above) so that any entries that are
1934 // added to the thread's dirty card queue as a result are not lost.
1935 if (UseG1GC) {
1936 flush_barrier_queues();
1937 }
1938 #endif // INCLUDE_ALL_GCS
1939
1940 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1941 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1942 os::current_thread_id());
1943
1944 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1945 Threads::remove(this);
1946 }
1947
1948 #if INCLUDE_ALL_GCS
1949 // Flush G1-related queues.
1950 void JavaThread::flush_barrier_queues() {
1951 satb_mark_queue().flush();
1952 dirty_card_queue().flush();
1953 }
1954
1955 void JavaThread::initialize_queues() {
1956 assert(!SafepointSynchronize::is_at_safepoint(),
1957 "we should not be at a safepoint");
1958
1959 SATBMarkQueue& satb_queue = satb_mark_queue();
1960 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1961 // The SATB queue should have been constructed with its active
1962 // field set to false.
1963 assert(!satb_queue.is_active(), "SATB queue should not be active");
1964 assert(satb_queue.is_empty(), "SATB queue should be empty");
1965 // If we are creating the thread during a marking cycle, we should
1966 // set the active field of the SATB queue to true.
1967 if (satb_queue_set.is_active()) {
1968 satb_queue.set_active(true);
1969 }
1970
1971 DirtyCardQueue& dirty_queue = dirty_card_queue();
1972 // The dirty card queue should have been constructed with its
1973 // active field set to true.
1974 assert(dirty_queue.is_active(), "dirty card queue should be active");
1975 }
1976 #endif // INCLUDE_ALL_GCS
1977
1978 void JavaThread::cleanup_failed_attach_current_thread() {
1979 if (get_thread_profiler() != NULL) {
1980 get_thread_profiler()->disengage();
1981 ResourceMark rm;
1982 get_thread_profiler()->print(get_thread_name());
1983 }
1984
1985 if (active_handles() != NULL) {
1986 JNIHandleBlock* block = active_handles();
1987 set_active_handles(NULL);
1988 JNIHandleBlock::release_block(block);
1989 }
1990
1991 if (free_handle_block() != NULL) {
1992 JNIHandleBlock* block = free_handle_block();
1993 set_free_handle_block(NULL);
1994 JNIHandleBlock::release_block(block);
1995 }
1996
1997 // These have to be removed while this is still a valid thread.
1998 remove_stack_guard_pages();
1999
2000 if (UseTLAB) {
2001 tlab().make_parsable(true); // retire TLAB, if any
2002 }
2003
2004 #if INCLUDE_ALL_GCS
2005 if (UseG1GC) {
2006 flush_barrier_queues();
2007 }
2008 #endif // INCLUDE_ALL_GCS
2009
2010 Threads::remove(this);
2011 delete this;
2012 }
2013
2014
2015
2016
2017 JavaThread* JavaThread::active() {
2018 Thread* thread = Thread::current();
2019 if (thread->is_Java_thread()) {
2020 return (JavaThread*) thread;
2021 } else {
2022 assert(thread->is_VM_thread(), "this must be a vm thread");
2023 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2024 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2025 assert(ret->is_Java_thread(), "must be a Java thread");
2026 return ret;
2027 }
2028 }
2029
2030 bool JavaThread::is_lock_owned(address adr) const {
2031 if (Thread::is_lock_owned(adr)) return true;
2032
2033 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2034 if (chunk->contains(adr)) return true;
2035 }
2036
2037 return false;
2038 }
2039
2040
2041 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2042 chunk->set_next(monitor_chunks());
2043 set_monitor_chunks(chunk);
2044 }
2045
2046 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2047 guarantee(monitor_chunks() != NULL, "must be non empty");
2048 if (monitor_chunks() == chunk) {
2049 set_monitor_chunks(chunk->next());
2050 } else {
2051 MonitorChunk* prev = monitor_chunks();
2052 while (prev->next() != chunk) prev = prev->next();
2053 prev->set_next(chunk->next());
2054 }
2055 }
2056
2057 // JVM support.
2058
2059 // Note: this function shouldn't block if it's called in
2060 // _thread_in_native_trans state (such as from
2061 // check_special_condition_for_native_trans()).
2062 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2063
2064 if (has_last_Java_frame() && has_async_condition()) {
2065 // If we are at a polling page safepoint (not a poll return)
2066 // then we must defer async exception because live registers
2067 // will be clobbered by the exception path. Poll return is
2068 // ok because the call we a returning from already collides
2069 // with exception handling registers and so there is no issue.
2070 // (The exception handling path kills call result registers but
2071 // this is ok since the exception kills the result anyway).
2072
2073 if (is_at_poll_safepoint()) {
2074 // if the code we are returning to has deoptimized we must defer
2075 // the exception otherwise live registers get clobbered on the
2076 // exception path before deoptimization is able to retrieve them.
2077 //
2078 RegisterMap map(this, false);
2079 frame caller_fr = last_frame().sender(&map);
2080 assert(caller_fr.is_compiled_frame(), "what?");
2081 if (caller_fr.is_deoptimized_frame()) {
2082 log_info(exceptions)("deferred async exception at compiled safepoint");
2083 return;
2084 }
2085 }
2086 }
2087
2088 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2089 if (condition == _no_async_condition) {
2090 // Conditions have changed since has_special_runtime_exit_condition()
2091 // was called:
2092 // - if we were here only because of an external suspend request,
2093 // then that was taken care of above (or cancelled) so we are done
2094 // - if we were here because of another async request, then it has
2095 // been cleared between the has_special_runtime_exit_condition()
2096 // and now so again we are done
2097 return;
2098 }
2099
2100 // Check for pending async. exception
2101 if (_pending_async_exception != NULL) {
2102 // Only overwrite an already pending exception, if it is not a threadDeath.
2103 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2104
2105 // We cannot call Exceptions::_throw(...) here because we cannot block
2106 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2107
2108 LogTarget(Info, exceptions) lt;
2109 if (lt.is_enabled()) {
2110 ResourceMark rm;
2111 LogStream ls(lt);
2112 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2113 if (has_last_Java_frame()) {
2114 frame f = last_frame();
2115 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2116 }
2117 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2118 }
2119 _pending_async_exception = NULL;
2120 clear_has_async_exception();
2121 }
2122 }
2123
2124 if (check_unsafe_error &&
2125 condition == _async_unsafe_access_error && !has_pending_exception()) {
2126 condition = _no_async_condition; // done
2127 switch (thread_state()) {
2128 case _thread_in_vm: {
2129 JavaThread* THREAD = this;
2130 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2131 }
2132 case _thread_in_native: {
2133 ThreadInVMfromNative tiv(this);
2134 JavaThread* THREAD = this;
2135 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2136 }
2137 case _thread_in_Java: {
2138 ThreadInVMfromJava tiv(this);
2139 JavaThread* THREAD = this;
2140 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2141 }
2142 default:
2143 ShouldNotReachHere();
2144 }
2145 }
2146
2147 assert(condition == _no_async_condition || has_pending_exception() ||
2148 (!check_unsafe_error && condition == _async_unsafe_access_error),
2149 "must have handled the async condition, if no exception");
2150 }
2151
2152 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2153 //
2154 // Check for pending external suspend. Internal suspend requests do
2155 // not use handle_special_runtime_exit_condition().
2156 // If JNIEnv proxies are allowed, don't self-suspend if the target
2157 // thread is not the current thread. In older versions of jdbx, jdbx
2158 // threads could call into the VM with another thread's JNIEnv so we
2159 // can be here operating on behalf of a suspended thread (4432884).
2160 bool do_self_suspend = is_external_suspend_with_lock();
2161 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2162 //
2163 // Because thread is external suspended the safepoint code will count
2164 // thread as at a safepoint. This can be odd because we can be here
2165 // as _thread_in_Java which would normally transition to _thread_blocked
2166 // at a safepoint. We would like to mark the thread as _thread_blocked
2167 // before calling java_suspend_self like all other callers of it but
2168 // we must then observe proper safepoint protocol. (We can't leave
2169 // _thread_blocked with a safepoint in progress). However we can be
2170 // here as _thread_in_native_trans so we can't use a normal transition
2171 // constructor/destructor pair because they assert on that type of
2172 // transition. We could do something like:
2173 //
2174 // JavaThreadState state = thread_state();
2175 // set_thread_state(_thread_in_vm);
2176 // {
2177 // ThreadBlockInVM tbivm(this);
2178 // java_suspend_self()
2179 // }
2180 // set_thread_state(_thread_in_vm_trans);
2181 // if (safepoint) block;
2182 // set_thread_state(state);
2183 //
2184 // but that is pretty messy. Instead we just go with the way the
2185 // code has worked before and note that this is the only path to
2186 // java_suspend_self that doesn't put the thread in _thread_blocked
2187 // mode.
2188
2189 frame_anchor()->make_walkable(this);
2190 java_suspend_self();
2191
2192 // We might be here for reasons in addition to the self-suspend request
2193 // so check for other async requests.
2194 }
2195
2196 if (check_asyncs) {
2197 check_and_handle_async_exceptions();
2198 }
2199 #if INCLUDE_TRACE
2200 if (is_trace_suspend()) {
2201 TRACE_SUSPEND_THREAD(this);
2202 }
2203 #endif
2204 }
2205
2206 void JavaThread::send_thread_stop(oop java_throwable) {
2207 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2208 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2209 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2210
2211 // Do not throw asynchronous exceptions against the compiler thread
2212 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2213 if (!can_call_java()) return;
2214
2215 {
2216 // Actually throw the Throwable against the target Thread - however
2217 // only if there is no thread death exception installed already.
2218 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2219 // If the topmost frame is a runtime stub, then we are calling into
2220 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2221 // must deoptimize the caller before continuing, as the compiled exception handler table
2222 // may not be valid
2223 if (has_last_Java_frame()) {
2224 frame f = last_frame();
2225 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2226 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2227 RegisterMap reg_map(this, UseBiasedLocking);
2228 frame compiled_frame = f.sender(®_map);
2229 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2230 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2231 }
2232 }
2233 }
2234
2235 // Set async. pending exception in thread.
2236 set_pending_async_exception(java_throwable);
2237
2238 if (log_is_enabled(Info, exceptions)) {
2239 ResourceMark rm;
2240 log_info(exceptions)("Pending Async. exception installed of type: %s",
2241 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2242 }
2243 // for AbortVMOnException flag
2244 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2245 }
2246 }
2247
2248
2249 // Interrupt thread so it will wake up from a potential wait()
2250 Thread::interrupt(this);
2251 }
2252
2253 // External suspension mechanism.
2254 //
2255 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2256 // to any VM_locks and it is at a transition
2257 // Self-suspension will happen on the transition out of the vm.
2258 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2259 //
2260 // Guarantees on return:
2261 // + Target thread will not execute any new bytecode (that's why we need to
2262 // force a safepoint)
2263 // + Target thread will not enter any new monitors
2264 //
2265 void JavaThread::java_suspend() {
2266 { MutexLocker mu(Threads_lock);
2267 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2268 return;
2269 }
2270 }
2271
2272 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2273 if (!is_external_suspend()) {
2274 // a racing resume has cancelled us; bail out now
2275 return;
2276 }
2277
2278 // suspend is done
2279 uint32_t debug_bits = 0;
2280 // Warning: is_ext_suspend_completed() may temporarily drop the
2281 // SR_lock to allow the thread to reach a stable thread state if
2282 // it is currently in a transient thread state.
2283 if (is_ext_suspend_completed(false /* !called_by_wait */,
2284 SuspendRetryDelay, &debug_bits)) {
2285 return;
2286 }
2287 }
2288
2289 VM_ThreadSuspend vm_suspend;
2290 VMThread::execute(&vm_suspend);
2291 }
2292
2293 // Part II of external suspension.
2294 // A JavaThread self suspends when it detects a pending external suspend
2295 // request. This is usually on transitions. It is also done in places
2296 // where continuing to the next transition would surprise the caller,
2297 // e.g., monitor entry.
2298 //
2299 // Returns the number of times that the thread self-suspended.
2300 //
2301 // Note: DO NOT call java_suspend_self() when you just want to block current
2302 // thread. java_suspend_self() is the second stage of cooperative
2303 // suspension for external suspend requests and should only be used
2304 // to complete an external suspend request.
2305 //
2306 int JavaThread::java_suspend_self() {
2307 int ret = 0;
2308
2309 // we are in the process of exiting so don't suspend
2310 if (is_exiting()) {
2311 clear_external_suspend();
2312 return ret;
2313 }
2314
2315 assert(_anchor.walkable() ||
2316 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2317 "must have walkable stack");
2318
2319 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2320
2321 assert(!this->is_ext_suspended(),
2322 "a thread trying to self-suspend should not already be suspended");
2323
2324 if (this->is_suspend_equivalent()) {
2325 // If we are self-suspending as a result of the lifting of a
2326 // suspend equivalent condition, then the suspend_equivalent
2327 // flag is not cleared until we set the ext_suspended flag so
2328 // that wait_for_ext_suspend_completion() returns consistent
2329 // results.
2330 this->clear_suspend_equivalent();
2331 }
2332
2333 // A racing resume may have cancelled us before we grabbed SR_lock
2334 // above. Or another external suspend request could be waiting for us
2335 // by the time we return from SR_lock()->wait(). The thread
2336 // that requested the suspension may already be trying to walk our
2337 // stack and if we return now, we can change the stack out from under
2338 // it. This would be a "bad thing (TM)" and cause the stack walker
2339 // to crash. We stay self-suspended until there are no more pending
2340 // external suspend requests.
2341 while (is_external_suspend()) {
2342 ret++;
2343 this->set_ext_suspended();
2344
2345 // _ext_suspended flag is cleared by java_resume()
2346 while (is_ext_suspended()) {
2347 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2348 }
2349 }
2350
2351 return ret;
2352 }
2353
2354 #ifdef ASSERT
2355 // verify the JavaThread has not yet been published in the Threads::list, and
2356 // hence doesn't need protection from concurrent access at this stage
2357 void JavaThread::verify_not_published() {
2358 if (!Threads_lock->owned_by_self()) {
2359 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2360 assert(!Threads::includes(this),
2361 "java thread shouldn't have been published yet!");
2362 } else {
2363 assert(!Threads::includes(this),
2364 "java thread shouldn't have been published yet!");
2365 }
2366 }
2367 #endif
2368
2369 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2370 // progress or when _suspend_flags is non-zero.
2371 // Current thread needs to self-suspend if there is a suspend request and/or
2372 // block if a safepoint is in progress.
2373 // Async exception ISN'T checked.
2374 // Note only the ThreadInVMfromNative transition can call this function
2375 // directly and when thread state is _thread_in_native_trans
2376 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2377 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2378
2379 JavaThread *curJT = JavaThread::current();
2380 bool do_self_suspend = thread->is_external_suspend();
2381
2382 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2383
2384 // If JNIEnv proxies are allowed, don't self-suspend if the target
2385 // thread is not the current thread. In older versions of jdbx, jdbx
2386 // threads could call into the VM with another thread's JNIEnv so we
2387 // can be here operating on behalf of a suspended thread (4432884).
2388 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2389 JavaThreadState state = thread->thread_state();
2390
2391 // We mark this thread_blocked state as a suspend-equivalent so
2392 // that a caller to is_ext_suspend_completed() won't be confused.
2393 // The suspend-equivalent state is cleared by java_suspend_self().
2394 thread->set_suspend_equivalent();
2395
2396 // If the safepoint code sees the _thread_in_native_trans state, it will
2397 // wait until the thread changes to other thread state. There is no
2398 // guarantee on how soon we can obtain the SR_lock and complete the
2399 // self-suspend request. It would be a bad idea to let safepoint wait for
2400 // too long. Temporarily change the state to _thread_blocked to
2401 // let the VM thread know that this thread is ready for GC. The problem
2402 // of changing thread state is that safepoint could happen just after
2403 // java_suspend_self() returns after being resumed, and VM thread will
2404 // see the _thread_blocked state. We must check for safepoint
2405 // after restoring the state and make sure we won't leave while a safepoint
2406 // is in progress.
2407 thread->set_thread_state(_thread_blocked);
2408 thread->java_suspend_self();
2409 thread->set_thread_state(state);
2410
2411 InterfaceSupport::serialize_thread_state_with_handler(thread);
2412 }
2413
2414 if (SafepointSynchronize::do_call_back()) {
2415 // If we are safepointing, then block the caller which may not be
2416 // the same as the target thread (see above).
2417 SafepointSynchronize::block(curJT);
2418 }
2419
2420 if (thread->is_deopt_suspend()) {
2421 thread->clear_deopt_suspend();
2422 RegisterMap map(thread, false);
2423 frame f = thread->last_frame();
2424 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2425 f = f.sender(&map);
2426 }
2427 if (f.id() == thread->must_deopt_id()) {
2428 thread->clear_must_deopt_id();
2429 f.deoptimize(thread);
2430 } else {
2431 fatal("missed deoptimization!");
2432 }
2433 }
2434 #if INCLUDE_TRACE
2435 if (thread->is_trace_suspend()) {
2436 TRACE_SUSPEND_THREAD(thread);
2437 }
2438 #endif
2439 }
2440
2441 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2442 // progress or when _suspend_flags is non-zero.
2443 // Current thread needs to self-suspend if there is a suspend request and/or
2444 // block if a safepoint is in progress.
2445 // Also check for pending async exception (not including unsafe access error).
2446 // Note only the native==>VM/Java barriers can call this function and when
2447 // thread state is _thread_in_native_trans.
2448 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2449 check_safepoint_and_suspend_for_native_trans(thread);
2450
2451 if (thread->has_async_exception()) {
2452 // We are in _thread_in_native_trans state, don't handle unsafe
2453 // access error since that may block.
2454 thread->check_and_handle_async_exceptions(false);
2455 }
2456 }
2457
2458 // This is a variant of the normal
2459 // check_special_condition_for_native_trans with slightly different
2460 // semantics for use by critical native wrappers. It does all the
2461 // normal checks but also performs the transition back into
2462 // thread_in_Java state. This is required so that critical natives
2463 // can potentially block and perform a GC if they are the last thread
2464 // exiting the GCLocker.
2465 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2466 check_special_condition_for_native_trans(thread);
2467
2468 // Finish the transition
2469 thread->set_thread_state(_thread_in_Java);
2470
2471 if (thread->do_critical_native_unlock()) {
2472 ThreadInVMfromJavaNoAsyncException tiv(thread);
2473 GCLocker::unlock_critical(thread);
2474 thread->clear_critical_native_unlock();
2475 }
2476 }
2477
2478 // We need to guarantee the Threads_lock here, since resumes are not
2479 // allowed during safepoint synchronization
2480 // Can only resume from an external suspension
2481 void JavaThread::java_resume() {
2482 assert_locked_or_safepoint(Threads_lock);
2483
2484 // Sanity check: thread is gone, has started exiting or the thread
2485 // was not externally suspended.
2486 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2487 return;
2488 }
2489
2490 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2491
2492 clear_external_suspend();
2493
2494 if (is_ext_suspended()) {
2495 clear_ext_suspended();
2496 SR_lock()->notify_all();
2497 }
2498 }
2499
2500 size_t JavaThread::_stack_red_zone_size = 0;
2501 size_t JavaThread::_stack_yellow_zone_size = 0;
2502 size_t JavaThread::_stack_reserved_zone_size = 0;
2503 size_t JavaThread::_stack_shadow_zone_size = 0;
2504
2505 void JavaThread::create_stack_guard_pages() {
2506 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2507 address low_addr = stack_end();
2508 size_t len = stack_guard_zone_size();
2509
2510 int must_commit = os::must_commit_stack_guard_pages();
2511 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2512
2513 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2514 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2515 return;
2516 }
2517
2518 if (os::guard_memory((char *) low_addr, len)) {
2519 _stack_guard_state = stack_guard_enabled;
2520 } else {
2521 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2522 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2523 if (os::uncommit_memory((char *) low_addr, len)) {
2524 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2525 }
2526 return;
2527 }
2528
2529 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2530 PTR_FORMAT "-" PTR_FORMAT ".",
2531 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2532 }
2533
2534 void JavaThread::remove_stack_guard_pages() {
2535 assert(Thread::current() == this, "from different thread");
2536 if (_stack_guard_state == stack_guard_unused) return;
2537 address low_addr = stack_end();
2538 size_t len = stack_guard_zone_size();
2539
2540 if (os::must_commit_stack_guard_pages()) {
2541 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2542 _stack_guard_state = stack_guard_unused;
2543 } else {
2544 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2545 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2546 return;
2547 }
2548 } else {
2549 if (_stack_guard_state == stack_guard_unused) return;
2550 if (os::unguard_memory((char *) low_addr, len)) {
2551 _stack_guard_state = stack_guard_unused;
2552 } else {
2553 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2554 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2555 return;
2556 }
2557 }
2558
2559 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2560 PTR_FORMAT "-" PTR_FORMAT ".",
2561 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2562 }
2563
2564 void JavaThread::enable_stack_reserved_zone() {
2565 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2566 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2567
2568 // The base notation is from the stack's point of view, growing downward.
2569 // We need to adjust it to work correctly with guard_memory()
2570 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2571
2572 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2573 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2574
2575 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2576 _stack_guard_state = stack_guard_enabled;
2577 } else {
2578 warning("Attempt to guard stack reserved zone failed.");
2579 }
2580 enable_register_stack_guard();
2581 }
2582
2583 void JavaThread::disable_stack_reserved_zone() {
2584 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2585 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2586
2587 // Simply return if called for a thread that does not use guard pages.
2588 if (_stack_guard_state == stack_guard_unused) return;
2589
2590 // The base notation is from the stack's point of view, growing downward.
2591 // We need to adjust it to work correctly with guard_memory()
2592 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2593
2594 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2595 _stack_guard_state = stack_guard_reserved_disabled;
2596 } else {
2597 warning("Attempt to unguard stack reserved zone failed.");
2598 }
2599 disable_register_stack_guard();
2600 }
2601
2602 void JavaThread::enable_stack_yellow_reserved_zone() {
2603 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2604 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2605
2606 // The base notation is from the stacks point of view, growing downward.
2607 // We need to adjust it to work correctly with guard_memory()
2608 address base = stack_red_zone_base();
2609
2610 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2611 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2612
2613 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2614 _stack_guard_state = stack_guard_enabled;
2615 } else {
2616 warning("Attempt to guard stack yellow zone failed.");
2617 }
2618 enable_register_stack_guard();
2619 }
2620
2621 void JavaThread::disable_stack_yellow_reserved_zone() {
2622 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2623 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2624
2625 // Simply return if called for a thread that does not use guard pages.
2626 if (_stack_guard_state == stack_guard_unused) return;
2627
2628 // The base notation is from the stacks point of view, growing downward.
2629 // We need to adjust it to work correctly with guard_memory()
2630 address base = stack_red_zone_base();
2631
2632 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2633 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2634 } else {
2635 warning("Attempt to unguard stack yellow zone failed.");
2636 }
2637 disable_register_stack_guard();
2638 }
2639
2640 void JavaThread::enable_stack_red_zone() {
2641 // The base notation is from the stacks point of view, growing downward.
2642 // We need to adjust it to work correctly with guard_memory()
2643 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2644 address base = stack_red_zone_base() - stack_red_zone_size();
2645
2646 guarantee(base < stack_base(), "Error calculating stack red zone");
2647 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2648
2649 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2650 warning("Attempt to guard stack red zone failed.");
2651 }
2652 }
2653
2654 void JavaThread::disable_stack_red_zone() {
2655 // The base notation is from the stacks point of view, growing downward.
2656 // We need to adjust it to work correctly with guard_memory()
2657 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2658 address base = stack_red_zone_base() - stack_red_zone_size();
2659 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2660 warning("Attempt to unguard stack red zone failed.");
2661 }
2662 }
2663
2664 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2665 // ignore is there is no stack
2666 if (!has_last_Java_frame()) return;
2667 // traverse the stack frames. Starts from top frame.
2668 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2669 frame* fr = fst.current();
2670 f(fr, fst.register_map());
2671 }
2672 }
2673
2674
2675 #ifndef PRODUCT
2676 // Deoptimization
2677 // Function for testing deoptimization
2678 void JavaThread::deoptimize() {
2679 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2680 StackFrameStream fst(this, UseBiasedLocking);
2681 bool deopt = false; // Dump stack only if a deopt actually happens.
2682 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2683 // Iterate over all frames in the thread and deoptimize
2684 for (; !fst.is_done(); fst.next()) {
2685 if (fst.current()->can_be_deoptimized()) {
2686
2687 if (only_at) {
2688 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2689 // consists of comma or carriage return separated numbers so
2690 // search for the current bci in that string.
2691 address pc = fst.current()->pc();
2692 nmethod* nm = (nmethod*) fst.current()->cb();
2693 ScopeDesc* sd = nm->scope_desc_at(pc);
2694 char buffer[8];
2695 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2696 size_t len = strlen(buffer);
2697 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2698 while (found != NULL) {
2699 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2700 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2701 // Check that the bci found is bracketed by terminators.
2702 break;
2703 }
2704 found = strstr(found + 1, buffer);
2705 }
2706 if (!found) {
2707 continue;
2708 }
2709 }
2710
2711 if (DebugDeoptimization && !deopt) {
2712 deopt = true; // One-time only print before deopt
2713 tty->print_cr("[BEFORE Deoptimization]");
2714 trace_frames();
2715 trace_stack();
2716 }
2717 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2718 }
2719 }
2720
2721 if (DebugDeoptimization && deopt) {
2722 tty->print_cr("[AFTER Deoptimization]");
2723 trace_frames();
2724 }
2725 }
2726
2727
2728 // Make zombies
2729 void JavaThread::make_zombies() {
2730 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2731 if (fst.current()->can_be_deoptimized()) {
2732 // it is a Java nmethod
2733 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2734 nm->make_not_entrant();
2735 }
2736 }
2737 }
2738 #endif // PRODUCT
2739
2740
2741 void JavaThread::deoptimized_wrt_marked_nmethods() {
2742 if (!has_last_Java_frame()) return;
2743 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2744 StackFrameStream fst(this, UseBiasedLocking);
2745 for (; !fst.is_done(); fst.next()) {
2746 if (fst.current()->should_be_deoptimized()) {
2747 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2748 }
2749 }
2750 }
2751
2752
2753 // If the caller is a NamedThread, then remember, in the current scope,
2754 // the given JavaThread in its _processed_thread field.
2755 class RememberProcessedThread: public StackObj {
2756 NamedThread* _cur_thr;
2757 public:
2758 RememberProcessedThread(JavaThread* jthr) {
2759 Thread* thread = Thread::current();
2760 if (thread->is_Named_thread()) {
2761 _cur_thr = (NamedThread *)thread;
2762 _cur_thr->set_processed_thread(jthr);
2763 } else {
2764 _cur_thr = NULL;
2765 }
2766 }
2767
2768 ~RememberProcessedThread() {
2769 if (_cur_thr) {
2770 _cur_thr->set_processed_thread(NULL);
2771 }
2772 }
2773 };
2774
2775 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2776 // Verify that the deferred card marks have been flushed.
2777 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2778
2779 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2780 // since there may be more than one thread using each ThreadProfiler.
2781
2782 // Traverse the GCHandles
2783 Thread::oops_do(f, cf);
2784
2785 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2786
2787 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2788 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2789
2790 if (has_last_Java_frame()) {
2791 // Record JavaThread to GC thread
2792 RememberProcessedThread rpt(this);
2793
2794 // Traverse the privileged stack
2795 if (_privileged_stack_top != NULL) {
2796 _privileged_stack_top->oops_do(f);
2797 }
2798
2799 // traverse the registered growable array
2800 if (_array_for_gc != NULL) {
2801 for (int index = 0; index < _array_for_gc->length(); index++) {
2802 f->do_oop(_array_for_gc->adr_at(index));
2803 }
2804 }
2805
2806 // Traverse the monitor chunks
2807 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2808 chunk->oops_do(f);
2809 }
2810
2811 // Traverse the execution stack
2812 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2813 fst.current()->oops_do(f, cf, fst.register_map());
2814 }
2815 }
2816
2817 // callee_target is never live across a gc point so NULL it here should
2818 // it still contain a methdOop.
2819
2820 set_callee_target(NULL);
2821
2822 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2823 // If we have deferred set_locals there might be oops waiting to be
2824 // written
2825 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2826 if (list != NULL) {
2827 for (int i = 0; i < list->length(); i++) {
2828 list->at(i)->oops_do(f);
2829 }
2830 }
2831
2832 // Traverse instance variables at the end since the GC may be moving things
2833 // around using this function
2834 f->do_oop((oop*) &_threadObj);
2835 f->do_oop((oop*) &_vm_result);
2836 f->do_oop((oop*) &_exception_oop);
2837 f->do_oop((oop*) &_pending_async_exception);
2838
2839 if (jvmti_thread_state() != NULL) {
2840 jvmti_thread_state()->oops_do(f);
2841 }
2842 }
2843
2844 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2845 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2846 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2847
2848 if (has_last_Java_frame()) {
2849 // Traverse the execution stack
2850 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2851 fst.current()->nmethods_do(cf);
2852 }
2853 }
2854 }
2855
2856 void JavaThread::metadata_do(void f(Metadata*)) {
2857 if (has_last_Java_frame()) {
2858 // Traverse the execution stack to call f() on the methods in the stack
2859 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2860 fst.current()->metadata_do(f);
2861 }
2862 } else if (is_Compiler_thread()) {
2863 // need to walk ciMetadata in current compile tasks to keep alive.
2864 CompilerThread* ct = (CompilerThread*)this;
2865 if (ct->env() != NULL) {
2866 ct->env()->metadata_do(f);
2867 }
2868 if (ct->task() != NULL) {
2869 ct->task()->metadata_do(f);
2870 }
2871 }
2872 }
2873
2874 // Printing
2875 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2876 switch (_thread_state) {
2877 case _thread_uninitialized: return "_thread_uninitialized";
2878 case _thread_new: return "_thread_new";
2879 case _thread_new_trans: return "_thread_new_trans";
2880 case _thread_in_native: return "_thread_in_native";
2881 case _thread_in_native_trans: return "_thread_in_native_trans";
2882 case _thread_in_vm: return "_thread_in_vm";
2883 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2884 case _thread_in_Java: return "_thread_in_Java";
2885 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2886 case _thread_blocked: return "_thread_blocked";
2887 case _thread_blocked_trans: return "_thread_blocked_trans";
2888 default: return "unknown thread state";
2889 }
2890 }
2891
2892 #ifndef PRODUCT
2893 void JavaThread::print_thread_state_on(outputStream *st) const {
2894 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2895 };
2896 void JavaThread::print_thread_state() const {
2897 print_thread_state_on(tty);
2898 }
2899 #endif // PRODUCT
2900
2901 // Called by Threads::print() for VM_PrintThreads operation
2902 void JavaThread::print_on(outputStream *st) const {
2903 st->print_raw("\"");
2904 st->print_raw(get_thread_name());
2905 st->print_raw("\" ");
2906 oop thread_oop = threadObj();
2907 if (thread_oop != NULL) {
2908 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2909 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2910 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2911 }
2912 Thread::print_on(st);
2913 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2914 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2915 if (thread_oop != NULL) {
2916 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2917 }
2918 #ifndef PRODUCT
2919 print_thread_state_on(st);
2920 _safepoint_state->print_on(st);
2921 #endif // PRODUCT
2922 if (is_Compiler_thread()) {
2923 CompilerThread* ct = (CompilerThread*)this;
2924 if (ct->task() != NULL) {
2925 st->print(" Compiling: ");
2926 ct->task()->print(st, NULL, true, false);
2927 } else {
2928 st->print(" No compile task");
2929 }
2930 st->cr();
2931 }
2932 }
2933
2934 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2935 st->print("%s", get_thread_name_string(buf, buflen));
2936 }
2937
2938 // Called by fatal error handler. The difference between this and
2939 // JavaThread::print() is that we can't grab lock or allocate memory.
2940 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2941 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2942 oop thread_obj = threadObj();
2943 if (thread_obj != NULL) {
2944 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2945 }
2946 st->print(" [");
2947 st->print("%s", _get_thread_state_name(_thread_state));
2948 if (osthread()) {
2949 st->print(", id=%d", osthread()->thread_id());
2950 }
2951 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2952 p2i(stack_end()), p2i(stack_base()));
2953 st->print("]");
2954 return;
2955 }
2956
2957 // Verification
2958
2959 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2960
2961 void JavaThread::verify() {
2962 // Verify oops in the thread.
2963 oops_do(&VerifyOopClosure::verify_oop, NULL);
2964
2965 // Verify the stack frames.
2966 frames_do(frame_verify);
2967 }
2968
2969 // CR 6300358 (sub-CR 2137150)
2970 // Most callers of this method assume that it can't return NULL but a
2971 // thread may not have a name whilst it is in the process of attaching to
2972 // the VM - see CR 6412693, and there are places where a JavaThread can be
2973 // seen prior to having it's threadObj set (eg JNI attaching threads and
2974 // if vm exit occurs during initialization). These cases can all be accounted
2975 // for such that this method never returns NULL.
2976 const char* JavaThread::get_thread_name() const {
2977 #ifdef ASSERT
2978 // early safepoints can hit while current thread does not yet have TLS
2979 if (!SafepointSynchronize::is_at_safepoint()) {
2980 Thread *cur = Thread::current();
2981 if (!(cur->is_Java_thread() && cur == this)) {
2982 // Current JavaThreads are allowed to get their own name without
2983 // the Threads_lock.
2984 assert_locked_or_safepoint(Threads_lock);
2985 }
2986 }
2987 #endif // ASSERT
2988 return get_thread_name_string();
2989 }
2990
2991 // Returns a non-NULL representation of this thread's name, or a suitable
2992 // descriptive string if there is no set name
2993 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2994 const char* name_str;
2995 oop thread_obj = threadObj();
2996 if (thread_obj != NULL) {
2997 oop name = java_lang_Thread::name(thread_obj);
2998 if (name != NULL) {
2999 if (buf == NULL) {
3000 name_str = java_lang_String::as_utf8_string(name);
3001 } else {
3002 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3003 }
3004 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3005 name_str = "<no-name - thread is attaching>";
3006 } else {
3007 name_str = Thread::name();
3008 }
3009 } else {
3010 name_str = Thread::name();
3011 }
3012 assert(name_str != NULL, "unexpected NULL thread name");
3013 return name_str;
3014 }
3015
3016
3017 const char* JavaThread::get_threadgroup_name() const {
3018 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3019 oop thread_obj = threadObj();
3020 if (thread_obj != NULL) {
3021 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3022 if (thread_group != NULL) {
3023 // ThreadGroup.name can be null
3024 return java_lang_ThreadGroup::name(thread_group);
3025 }
3026 }
3027 return NULL;
3028 }
3029
3030 const char* JavaThread::get_parent_name() const {
3031 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3032 oop thread_obj = threadObj();
3033 if (thread_obj != NULL) {
3034 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3035 if (thread_group != NULL) {
3036 oop parent = java_lang_ThreadGroup::parent(thread_group);
3037 if (parent != NULL) {
3038 // ThreadGroup.name can be null
3039 return java_lang_ThreadGroup::name(parent);
3040 }
3041 }
3042 }
3043 return NULL;
3044 }
3045
3046 ThreadPriority JavaThread::java_priority() const {
3047 oop thr_oop = threadObj();
3048 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3049 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3050 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3051 return priority;
3052 }
3053
3054 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3055
3056 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3057 // Link Java Thread object <-> C++ Thread
3058
3059 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3060 // and put it into a new Handle. The Handle "thread_oop" can then
3061 // be used to pass the C++ thread object to other methods.
3062
3063 // Set the Java level thread object (jthread) field of the
3064 // new thread (a JavaThread *) to C++ thread object using the
3065 // "thread_oop" handle.
3066
3067 // Set the thread field (a JavaThread *) of the
3068 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3069
3070 Handle thread_oop(Thread::current(),
3071 JNIHandles::resolve_non_null(jni_thread));
3072 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3073 "must be initialized");
3074 set_threadObj(thread_oop());
3075 java_lang_Thread::set_thread(thread_oop(), this);
3076
3077 if (prio == NoPriority) {
3078 prio = java_lang_Thread::priority(thread_oop());
3079 assert(prio != NoPriority, "A valid priority should be present");
3080 }
3081
3082 // Push the Java priority down to the native thread; needs Threads_lock
3083 Thread::set_priority(this, prio);
3084
3085 prepare_ext();
3086
3087 // Add the new thread to the Threads list and set it in motion.
3088 // We must have threads lock in order to call Threads::add.
3089 // It is crucial that we do not block before the thread is
3090 // added to the Threads list for if a GC happens, then the java_thread oop
3091 // will not be visited by GC.
3092 Threads::add(this);
3093 }
3094
3095 oop JavaThread::current_park_blocker() {
3096 // Support for JSR-166 locks
3097 oop thread_oop = threadObj();
3098 if (thread_oop != NULL &&
3099 JDK_Version::current().supports_thread_park_blocker()) {
3100 return java_lang_Thread::park_blocker(thread_oop);
3101 }
3102 return NULL;
3103 }
3104
3105
3106 void JavaThread::print_stack_on(outputStream* st) {
3107 if (!has_last_Java_frame()) return;
3108 ResourceMark rm;
3109 HandleMark hm;
3110
3111 RegisterMap reg_map(this);
3112 vframe* start_vf = last_java_vframe(®_map);
3113 int count = 0;
3114 for (vframe* f = start_vf; f; f = f->sender()) {
3115 if (f->is_java_frame()) {
3116 javaVFrame* jvf = javaVFrame::cast(f);
3117 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3118
3119 // Print out lock information
3120 if (JavaMonitorsInStackTrace) {
3121 jvf->print_lock_info_on(st, count);
3122 }
3123 } else {
3124 // Ignore non-Java frames
3125 }
3126
3127 // Bail-out case for too deep stacks
3128 count++;
3129 if (MaxJavaStackTraceDepth == count) return;
3130 }
3131 }
3132
3133
3134 // JVMTI PopFrame support
3135 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3136 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3137 if (in_bytes(size_in_bytes) != 0) {
3138 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3139 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3140 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3141 }
3142 }
3143
3144 void* JavaThread::popframe_preserved_args() {
3145 return _popframe_preserved_args;
3146 }
3147
3148 ByteSize JavaThread::popframe_preserved_args_size() {
3149 return in_ByteSize(_popframe_preserved_args_size);
3150 }
3151
3152 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3153 int sz = in_bytes(popframe_preserved_args_size());
3154 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3155 return in_WordSize(sz / wordSize);
3156 }
3157
3158 void JavaThread::popframe_free_preserved_args() {
3159 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3160 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3161 _popframe_preserved_args = NULL;
3162 _popframe_preserved_args_size = 0;
3163 }
3164
3165 #ifndef PRODUCT
3166
3167 void JavaThread::trace_frames() {
3168 tty->print_cr("[Describe stack]");
3169 int frame_no = 1;
3170 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3171 tty->print(" %d. ", frame_no++);
3172 fst.current()->print_value_on(tty, this);
3173 tty->cr();
3174 }
3175 }
3176
3177 class PrintAndVerifyOopClosure: public OopClosure {
3178 protected:
3179 template <class T> inline void do_oop_work(T* p) {
3180 oop obj = oopDesc::load_decode_heap_oop(p);
3181 if (obj == NULL) return;
3182 tty->print(INTPTR_FORMAT ": ", p2i(p));
3183 if (obj->is_oop_or_null()) {
3184 if (obj->is_objArray()) {
3185 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3186 } else {
3187 obj->print();
3188 }
3189 } else {
3190 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3191 }
3192 tty->cr();
3193 }
3194 public:
3195 virtual void do_oop(oop* p) { do_oop_work(p); }
3196 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3197 };
3198
3199
3200 static void oops_print(frame* f, const RegisterMap *map) {
3201 PrintAndVerifyOopClosure print;
3202 f->print_value();
3203 f->oops_do(&print, NULL, (RegisterMap*)map);
3204 }
3205
3206 // Print our all the locations that contain oops and whether they are
3207 // valid or not. This useful when trying to find the oldest frame
3208 // where an oop has gone bad since the frame walk is from youngest to
3209 // oldest.
3210 void JavaThread::trace_oops() {
3211 tty->print_cr("[Trace oops]");
3212 frames_do(oops_print);
3213 }
3214
3215
3216 #ifdef ASSERT
3217 // Print or validate the layout of stack frames
3218 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3219 ResourceMark rm;
3220 PRESERVE_EXCEPTION_MARK;
3221 FrameValues values;
3222 int frame_no = 0;
3223 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3224 fst.current()->describe(values, ++frame_no);
3225 if (depth == frame_no) break;
3226 }
3227 if (validate_only) {
3228 values.validate();
3229 } else {
3230 tty->print_cr("[Describe stack layout]");
3231 values.print(this);
3232 }
3233 }
3234 #endif
3235
3236 void JavaThread::trace_stack_from(vframe* start_vf) {
3237 ResourceMark rm;
3238 int vframe_no = 1;
3239 for (vframe* f = start_vf; f; f = f->sender()) {
3240 if (f->is_java_frame()) {
3241 javaVFrame::cast(f)->print_activation(vframe_no++);
3242 } else {
3243 f->print();
3244 }
3245 if (vframe_no > StackPrintLimit) {
3246 tty->print_cr("...<more frames>...");
3247 return;
3248 }
3249 }
3250 }
3251
3252
3253 void JavaThread::trace_stack() {
3254 if (!has_last_Java_frame()) return;
3255 ResourceMark rm;
3256 HandleMark hm;
3257 RegisterMap reg_map(this);
3258 trace_stack_from(last_java_vframe(®_map));
3259 }
3260
3261
3262 #endif // PRODUCT
3263
3264
3265 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3266 assert(reg_map != NULL, "a map must be given");
3267 frame f = last_frame();
3268 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3269 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3270 }
3271 return NULL;
3272 }
3273
3274
3275 Klass* JavaThread::security_get_caller_class(int depth) {
3276 vframeStream vfst(this);
3277 vfst.security_get_caller_frame(depth);
3278 if (!vfst.at_end()) {
3279 return vfst.method()->method_holder();
3280 }
3281 return NULL;
3282 }
3283
3284 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3285 assert(thread->is_Compiler_thread(), "must be compiler thread");
3286 CompileBroker::compiler_thread_loop();
3287 }
3288
3289 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3290 NMethodSweeper::sweeper_loop();
3291 }
3292
3293 // Create a CompilerThread
3294 CompilerThread::CompilerThread(CompileQueue* queue,
3295 CompilerCounters* counters)
3296 : JavaThread(&compiler_thread_entry) {
3297 _env = NULL;
3298 _log = NULL;
3299 _task = NULL;
3300 _queue = queue;
3301 _counters = counters;
3302 _buffer_blob = NULL;
3303 _compiler = NULL;
3304
3305 #ifndef PRODUCT
3306 _ideal_graph_printer = NULL;
3307 #endif
3308 }
3309
3310 bool CompilerThread::can_call_java() const {
3311 return _compiler != NULL && _compiler->is_jvmci();
3312 }
3313
3314 // Create sweeper thread
3315 CodeCacheSweeperThread::CodeCacheSweeperThread()
3316 : JavaThread(&sweeper_thread_entry) {
3317 _scanned_compiled_method = NULL;
3318 }
3319
3320 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3321 JavaThread::oops_do(f, cf);
3322 if (_scanned_compiled_method != NULL && cf != NULL) {
3323 // Safepoints can occur when the sweeper is scanning an nmethod so
3324 // process it here to make sure it isn't unloaded in the middle of
3325 // a scan.
3326 cf->do_code_blob(_scanned_compiled_method);
3327 }
3328 }
3329
3330 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3331 JavaThread::nmethods_do(cf);
3332 if (_scanned_compiled_method != NULL && cf != NULL) {
3333 // Safepoints can occur when the sweeper is scanning an nmethod so
3334 // process it here to make sure it isn't unloaded in the middle of
3335 // a scan.
3336 cf->do_code_blob(_scanned_compiled_method);
3337 }
3338 }
3339
3340
3341 // ======= Threads ========
3342
3343 // The Threads class links together all active threads, and provides
3344 // operations over all threads. It is protected by its own Mutex
3345 // lock, which is also used in other contexts to protect thread
3346 // operations from having the thread being operated on from exiting
3347 // and going away unexpectedly (e.g., safepoint synchronization)
3348
3349 JavaThread* Threads::_thread_list = NULL;
3350 int Threads::_number_of_threads = 0;
3351 int Threads::_number_of_non_daemon_threads = 0;
3352 int Threads::_return_code = 0;
3353 int Threads::_thread_claim_parity = 0;
3354 size_t JavaThread::_stack_size_at_create = 0;
3355 #ifdef ASSERT
3356 bool Threads::_vm_complete = false;
3357 #endif
3358
3359 // All JavaThreads
3360 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3361
3362 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3363 void Threads::threads_do(ThreadClosure* tc) {
3364 assert_locked_or_safepoint(Threads_lock);
3365 // ALL_JAVA_THREADS iterates through all JavaThreads
3366 ALL_JAVA_THREADS(p) {
3367 tc->do_thread(p);
3368 }
3369 // Someday we could have a table or list of all non-JavaThreads.
3370 // For now, just manually iterate through them.
3371 tc->do_thread(VMThread::vm_thread());
3372 Universe::heap()->gc_threads_do(tc);
3373 WatcherThread *wt = WatcherThread::watcher_thread();
3374 // Strictly speaking, the following NULL check isn't sufficient to make sure
3375 // the data for WatcherThread is still valid upon being examined. However,
3376 // considering that WatchThread terminates when the VM is on the way to
3377 // exit at safepoint, the chance of the above is extremely small. The right
3378 // way to prevent termination of WatcherThread would be to acquire
3379 // Terminator_lock, but we can't do that without violating the lock rank
3380 // checking in some cases.
3381 if (wt != NULL) {
3382 tc->do_thread(wt);
3383 }
3384
3385 // If CompilerThreads ever become non-JavaThreads, add them here
3386 }
3387
3388 void Threads::parallel_java_threads_do(ThreadClosure* tc) {
3389 int cp = Threads::thread_claim_parity();
3390 ALL_JAVA_THREADS(p) {
3391 if (p->claim_oops_do(true, cp)) {
3392 tc->do_thread(p);
3393 }
3394 }
3395 // Thread claiming protocol requires us to claim the same interesting
3396 // threads on all paths. Notably, Threads::possibly_parallel_threads_do
3397 // claims all Java threads *and* the VMThread. To avoid breaking the
3398 // claiming protocol, we have to claim VMThread on this path too, even
3399 // if we do not apply the closure to the VMThread.
3400 VMThread* vmt = VMThread::vm_thread();
3401 (void)vmt->claim_oops_do(true, cp);
3402 }
3403
3404 // The system initialization in the library has three phases.
3405 //
3406 // Phase 1: java.lang.System class initialization
3407 // java.lang.System is a primordial class loaded and initialized
3408 // by the VM early during startup. java.lang.System.<clinit>
3409 // only does registerNatives and keeps the rest of the class
3410 // initialization work later until thread initialization completes.
3411 //
3412 // System.initPhase1 initializes the system properties, the static
3413 // fields in, out, and err. Set up java signal handlers, OS-specific
3414 // system settings, and thread group of the main thread.
3415 static void call_initPhase1(TRAPS) {
3416 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3417 JavaValue result(T_VOID);
3418 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3419 vmSymbols::void_method_signature(), CHECK);
3420 }
3421
3422 // Phase 2. Module system initialization
3423 // This will initialize the module system. Only java.base classes
3424 // can be loaded until phase 2 completes.
3425 //
3426 // Call System.initPhase2 after the compiler initialization and jsr292
3427 // classes get initialized because module initialization runs a lot of java
3428 // code, that for performance reasons, should be compiled. Also, this will
3429 // enable the startup code to use lambda and other language features in this
3430 // phase and onward.
3431 //
3432 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3433 static void call_initPhase2(TRAPS) {
3434 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3435
3436 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3437
3438 JavaValue result(T_INT);
3439 JavaCallArguments args;
3440 args.push_int(DisplayVMOutputToStderr);
3441 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3442 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3443 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3444 if (result.get_jint() != JNI_OK) {
3445 vm_exit_during_initialization(); // no message or exception
3446 }
3447
3448 universe_post_module_init();
3449 }
3450
3451 // Phase 3. final setup - set security manager, system class loader and TCCL
3452 //
3453 // This will instantiate and set the security manager, set the system class
3454 // loader as well as the thread context class loader. The security manager
3455 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3456 // other modules or the application's classpath.
3457 static void call_initPhase3(TRAPS) {
3458 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3459 JavaValue result(T_VOID);
3460 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3461 vmSymbols::void_method_signature(), CHECK);
3462 }
3463
3464 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3465 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3466
3467 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3468 create_vm_init_libraries();
3469 }
3470
3471 initialize_class(vmSymbols::java_lang_String(), CHECK);
3472
3473 // Inject CompactStrings value after the static initializers for String ran.
3474 java_lang_String::set_compact_strings(CompactStrings);
3475
3476 // Initialize java_lang.System (needed before creating the thread)
3477 initialize_class(vmSymbols::java_lang_System(), CHECK);
3478 // The VM creates & returns objects of this class. Make sure it's initialized.
3479 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3480 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3481 Handle thread_group = create_initial_thread_group(CHECK);
3482 Universe::set_main_thread_group(thread_group());
3483 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3484 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3485 main_thread->set_threadObj(thread_object);
3486 // Set thread status to running since main thread has
3487 // been started and running.
3488 java_lang_Thread::set_thread_status(thread_object,
3489 java_lang_Thread::RUNNABLE);
3490
3491 // The VM creates objects of this class.
3492 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3493
3494 // The VM preresolves methods to these classes. Make sure that they get initialized
3495 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3496 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3497
3498 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3499 call_initPhase1(CHECK);
3500
3501 // get the Java runtime name after java.lang.System is initialized
3502 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3503 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3504
3505 // an instance of OutOfMemory exception has been allocated earlier
3506 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3507 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3508 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3509 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3510 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3511 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3512 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3513 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3514 }
3515
3516 void Threads::initialize_jsr292_core_classes(TRAPS) {
3517 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3518
3519 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3520 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3521 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3522 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3523 }
3524
3525 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3526 extern void JDK_Version_init();
3527
3528 // Preinitialize version info.
3529 VM_Version::early_initialize();
3530
3531 // Check version
3532 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3533
3534 // Initialize library-based TLS
3535 ThreadLocalStorage::init();
3536
3537 // Initialize the output stream module
3538 ostream_init();
3539
3540 // Process java launcher properties.
3541 Arguments::process_sun_java_launcher_properties(args);
3542
3543 // Initialize the os module
3544 os::init();
3545
3546 // Record VM creation timing statistics
3547 TraceVmCreationTime create_vm_timer;
3548 create_vm_timer.start();
3549
3550 // Initialize system properties.
3551 Arguments::init_system_properties();
3552
3553 // So that JDK version can be used as a discriminator when parsing arguments
3554 JDK_Version_init();
3555
3556 // Update/Initialize System properties after JDK version number is known
3557 Arguments::init_version_specific_system_properties();
3558
3559 // Make sure to initialize log configuration *before* parsing arguments
3560 LogConfiguration::initialize(create_vm_timer.begin_time());
3561
3562 // Parse arguments
3563 jint parse_result = Arguments::parse(args);
3564 if (parse_result != JNI_OK) return parse_result;
3565
3566 os::init_before_ergo();
3567
3568 jint ergo_result = Arguments::apply_ergo();
3569 if (ergo_result != JNI_OK) return ergo_result;
3570
3571 // Final check of all ranges after ergonomics which may change values.
3572 if (!CommandLineFlagRangeList::check_ranges()) {
3573 return JNI_EINVAL;
3574 }
3575
3576 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3577 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3578 if (!constraint_result) {
3579 return JNI_EINVAL;
3580 }
3581
3582 CommandLineFlagWriteableList::mark_startup();
3583
3584 if (PauseAtStartup) {
3585 os::pause();
3586 }
3587
3588 HOTSPOT_VM_INIT_BEGIN();
3589
3590 // Timing (must come after argument parsing)
3591 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3592
3593 // Initialize the os module after parsing the args
3594 jint os_init_2_result = os::init_2();
3595 if (os_init_2_result != JNI_OK) return os_init_2_result;
3596
3597 jint adjust_after_os_result = Arguments::adjust_after_os();
3598 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3599
3600 // Initialize output stream logging
3601 ostream_init_log();
3602
3603 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3604 // Must be before create_vm_init_agents()
3605 if (Arguments::init_libraries_at_startup()) {
3606 convert_vm_init_libraries_to_agents();
3607 }
3608
3609 // Launch -agentlib/-agentpath and converted -Xrun agents
3610 if (Arguments::init_agents_at_startup()) {
3611 create_vm_init_agents();
3612 }
3613
3614 // Initialize Threads state
3615 _thread_list = NULL;
3616 _number_of_threads = 0;
3617 _number_of_non_daemon_threads = 0;
3618
3619 // Initialize global data structures and create system classes in heap
3620 vm_init_globals();
3621
3622 #if INCLUDE_JVMCI
3623 if (JVMCICounterSize > 0) {
3624 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3625 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3626 } else {
3627 JavaThread::_jvmci_old_thread_counters = NULL;
3628 }
3629 #endif // INCLUDE_JVMCI
3630
3631 // Attach the main thread to this os thread
3632 JavaThread* main_thread = new JavaThread();
3633 main_thread->set_thread_state(_thread_in_vm);
3634 main_thread->initialize_thread_current();
3635 // must do this before set_active_handles
3636 main_thread->record_stack_base_and_size();
3637 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3638
3639 if (!main_thread->set_as_starting_thread()) {
3640 vm_shutdown_during_initialization(
3641 "Failed necessary internal allocation. Out of swap space");
3642 delete main_thread;
3643 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3644 return JNI_ENOMEM;
3645 }
3646
3647 // Enable guard page *after* os::create_main_thread(), otherwise it would
3648 // crash Linux VM, see notes in os_linux.cpp.
3649 main_thread->create_stack_guard_pages();
3650
3651 // Initialize Java-Level synchronization subsystem
3652 ObjectMonitor::Initialize();
3653
3654 // Initialize global modules
3655 jint status = init_globals();
3656 if (status != JNI_OK) {
3657 delete main_thread;
3658 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3659 return status;
3660 }
3661
3662 if (TRACE_INITIALIZE() != JNI_OK) {
3663 vm_exit_during_initialization("Failed to initialize tracing backend");
3664 }
3665
3666 // Should be done after the heap is fully created
3667 main_thread->cache_global_variables();
3668
3669 HandleMark hm;
3670
3671 { MutexLocker mu(Threads_lock);
3672 Threads::add(main_thread);
3673 }
3674
3675 // Any JVMTI raw monitors entered in onload will transition into
3676 // real raw monitor. VM is setup enough here for raw monitor enter.
3677 JvmtiExport::transition_pending_onload_raw_monitors();
3678
3679 // Create the VMThread
3680 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3681
3682 VMThread::create();
3683 Thread* vmthread = VMThread::vm_thread();
3684
3685 if (!os::create_thread(vmthread, os::vm_thread)) {
3686 vm_exit_during_initialization("Cannot create VM thread. "
3687 "Out of system resources.");
3688 }
3689
3690 // Wait for the VM thread to become ready, and VMThread::run to initialize
3691 // Monitors can have spurious returns, must always check another state flag
3692 {
3693 MutexLocker ml(Notify_lock);
3694 os::start_thread(vmthread);
3695 while (vmthread->active_handles() == NULL) {
3696 Notify_lock->wait();
3697 }
3698 }
3699 }
3700
3701 assert(Universe::is_fully_initialized(), "not initialized");
3702 if (VerifyDuringStartup) {
3703 // Make sure we're starting with a clean slate.
3704 VM_Verify verify_op;
3705 VMThread::execute(&verify_op);
3706 }
3707
3708 Thread* THREAD = Thread::current();
3709
3710 // At this point, the Universe is initialized, but we have not executed
3711 // any byte code. Now is a good time (the only time) to dump out the
3712 // internal state of the JVM for sharing.
3713 if (DumpSharedSpaces) {
3714 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3715 ShouldNotReachHere();
3716 }
3717
3718 // Always call even when there are not JVMTI environments yet, since environments
3719 // may be attached late and JVMTI must track phases of VM execution
3720 JvmtiExport::enter_early_start_phase();
3721
3722 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3723 JvmtiExport::post_early_vm_start();
3724
3725 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3726
3727 // We need this for ClassDataSharing - the initial vm.info property is set
3728 // with the default value of CDS "sharing" which may be reset through
3729 // command line options.
3730 reset_vm_info_property(CHECK_JNI_ERR);
3731
3732 quicken_jni_functions();
3733
3734 // No more stub generation allowed after that point.
3735 StubCodeDesc::freeze();
3736
3737 // Set flag that basic initialization has completed. Used by exceptions and various
3738 // debug stuff, that does not work until all basic classes have been initialized.
3739 set_init_completed();
3740
3741 LogConfiguration::post_initialize();
3742 Metaspace::post_initialize();
3743
3744 HOTSPOT_VM_INIT_END();
3745
3746 // record VM initialization completion time
3747 #if INCLUDE_MANAGEMENT
3748 Management::record_vm_init_completed();
3749 #endif // INCLUDE_MANAGEMENT
3750
3751 // Signal Dispatcher needs to be started before VMInit event is posted
3752 os::signal_init(CHECK_JNI_ERR);
3753
3754 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3755 if (!DisableAttachMechanism) {
3756 AttachListener::vm_start();
3757 if (StartAttachListener || AttachListener::init_at_startup()) {
3758 AttachListener::init();
3759 }
3760 }
3761
3762 // Launch -Xrun agents
3763 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3764 // back-end can launch with -Xdebug -Xrunjdwp.
3765 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3766 create_vm_init_libraries();
3767 }
3768
3769 if (CleanChunkPoolAsync) {
3770 Chunk::start_chunk_pool_cleaner_task();
3771 }
3772
3773 // initialize compiler(s)
3774 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3775 CompileBroker::compilation_init(CHECK_JNI_ERR);
3776 #endif
3777
3778 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3779 // It is done after compilers are initialized, because otherwise compilations of
3780 // signature polymorphic MH intrinsics can be missed
3781 // (see SystemDictionary::find_method_handle_intrinsic).
3782 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3783
3784 // This will initialize the module system. Only java.base classes can be
3785 // loaded until phase 2 completes
3786 call_initPhase2(CHECK_JNI_ERR);
3787
3788 // Always call even when there are not JVMTI environments yet, since environments
3789 // may be attached late and JVMTI must track phases of VM execution
3790 JvmtiExport::enter_start_phase();
3791
3792 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3793 JvmtiExport::post_vm_start();
3794
3795 // Final system initialization including security manager and system class loader
3796 call_initPhase3(CHECK_JNI_ERR);
3797
3798 // cache the system class loader
3799 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3800
3801 #if INCLUDE_JVMCI
3802 if (EnableJVMCI) {
3803 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3804 // The JVMCI Java initialization code will read this flag and
3805 // do the printing if it's set.
3806 bool init = JVMCIPrintProperties;
3807
3808 if (!init) {
3809 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3810 // compilations via JVMCI will not actually block until JVMCI is initialized.
3811 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3812 }
3813
3814 if (init) {
3815 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3816 }
3817 }
3818 #endif
3819
3820 // Always call even when there are not JVMTI environments yet, since environments
3821 // may be attached late and JVMTI must track phases of VM execution
3822 JvmtiExport::enter_live_phase();
3823
3824 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3825 JvmtiExport::post_vm_initialized();
3826
3827 if (TRACE_START() != JNI_OK) {
3828 vm_exit_during_initialization("Failed to start tracing backend.");
3829 }
3830
3831 #if INCLUDE_MANAGEMENT
3832 Management::initialize(THREAD);
3833
3834 if (HAS_PENDING_EXCEPTION) {
3835 // management agent fails to start possibly due to
3836 // configuration problem and is responsible for printing
3837 // stack trace if appropriate. Simply exit VM.
3838 vm_exit(1);
3839 }
3840 #endif // INCLUDE_MANAGEMENT
3841
3842 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3843 if (MemProfiling) MemProfiler::engage();
3844 StatSampler::engage();
3845 if (CheckJNICalls) JniPeriodicChecker::engage();
3846
3847 BiasedLocking::init();
3848
3849 #if INCLUDE_RTM_OPT
3850 RTMLockingCounters::init();
3851 #endif
3852
3853 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3854 call_postVMInitHook(THREAD);
3855 // The Java side of PostVMInitHook.run must deal with all
3856 // exceptions and provide means of diagnosis.
3857 if (HAS_PENDING_EXCEPTION) {
3858 CLEAR_PENDING_EXCEPTION;
3859 }
3860 }
3861
3862 {
3863 MutexLocker ml(PeriodicTask_lock);
3864 // Make sure the WatcherThread can be started by WatcherThread::start()
3865 // or by dynamic enrollment.
3866 WatcherThread::make_startable();
3867 // Start up the WatcherThread if there are any periodic tasks
3868 // NOTE: All PeriodicTasks should be registered by now. If they
3869 // aren't, late joiners might appear to start slowly (we might
3870 // take a while to process their first tick).
3871 if (PeriodicTask::num_tasks() > 0) {
3872 WatcherThread::start();
3873 }
3874 }
3875
3876 create_vm_timer.end();
3877 #ifdef ASSERT
3878 _vm_complete = true;
3879 #endif
3880 return JNI_OK;
3881 }
3882
3883 // type for the Agent_OnLoad and JVM_OnLoad entry points
3884 extern "C" {
3885 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3886 }
3887 // Find a command line agent library and return its entry point for
3888 // -agentlib: -agentpath: -Xrun
3889 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3890 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3891 const char *on_load_symbols[],
3892 size_t num_symbol_entries) {
3893 OnLoadEntry_t on_load_entry = NULL;
3894 void *library = NULL;
3895
3896 if (!agent->valid()) {
3897 char buffer[JVM_MAXPATHLEN];
3898 char ebuf[1024] = "";
3899 const char *name = agent->name();
3900 const char *msg = "Could not find agent library ";
3901
3902 // First check to see if agent is statically linked into executable
3903 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3904 library = agent->os_lib();
3905 } else if (agent->is_absolute_path()) {
3906 library = os::dll_load(name, ebuf, sizeof ebuf);
3907 if (library == NULL) {
3908 const char *sub_msg = " in absolute path, with error: ";
3909 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3910 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3911 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3912 // If we can't find the agent, exit.
3913 vm_exit_during_initialization(buf, NULL);
3914 FREE_C_HEAP_ARRAY(char, buf);
3915 }
3916 } else {
3917 // Try to load the agent from the standard dll directory
3918 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3919 name)) {
3920 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3921 }
3922 if (library == NULL) { // Try the local directory
3923 char ns[1] = {0};
3924 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3925 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3926 }
3927 if (library == NULL) {
3928 const char *sub_msg = " on the library path, with error: ";
3929 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3930 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3931 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3932 // If we can't find the agent, exit.
3933 vm_exit_during_initialization(buf, NULL);
3934 FREE_C_HEAP_ARRAY(char, buf);
3935 }
3936 }
3937 }
3938 agent->set_os_lib(library);
3939 agent->set_valid();
3940 }
3941
3942 // Find the OnLoad function.
3943 on_load_entry =
3944 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3945 false,
3946 on_load_symbols,
3947 num_symbol_entries));
3948 return on_load_entry;
3949 }
3950
3951 // Find the JVM_OnLoad entry point
3952 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3953 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3954 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3955 }
3956
3957 // Find the Agent_OnLoad entry point
3958 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3959 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3960 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3961 }
3962
3963 // For backwards compatibility with -Xrun
3964 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3965 // treated like -agentpath:
3966 // Must be called before agent libraries are created
3967 void Threads::convert_vm_init_libraries_to_agents() {
3968 AgentLibrary* agent;
3969 AgentLibrary* next;
3970
3971 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3972 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3973 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3974
3975 // If there is an JVM_OnLoad function it will get called later,
3976 // otherwise see if there is an Agent_OnLoad
3977 if (on_load_entry == NULL) {
3978 on_load_entry = lookup_agent_on_load(agent);
3979 if (on_load_entry != NULL) {
3980 // switch it to the agent list -- so that Agent_OnLoad will be called,
3981 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3982 Arguments::convert_library_to_agent(agent);
3983 } else {
3984 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3985 }
3986 }
3987 }
3988 }
3989
3990 // Create agents for -agentlib: -agentpath: and converted -Xrun
3991 // Invokes Agent_OnLoad
3992 // Called very early -- before JavaThreads exist
3993 void Threads::create_vm_init_agents() {
3994 extern struct JavaVM_ main_vm;
3995 AgentLibrary* agent;
3996
3997 JvmtiExport::enter_onload_phase();
3998
3999 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4000 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4001
4002 if (on_load_entry != NULL) {
4003 // Invoke the Agent_OnLoad function
4004 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4005 if (err != JNI_OK) {
4006 vm_exit_during_initialization("agent library failed to init", agent->name());
4007 }
4008 } else {
4009 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4010 }
4011 }
4012 JvmtiExport::enter_primordial_phase();
4013 }
4014
4015 extern "C" {
4016 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4017 }
4018
4019 void Threads::shutdown_vm_agents() {
4020 // Send any Agent_OnUnload notifications
4021 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4022 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4023 extern struct JavaVM_ main_vm;
4024 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4025
4026 // Find the Agent_OnUnload function.
4027 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4028 os::find_agent_function(agent,
4029 false,
4030 on_unload_symbols,
4031 num_symbol_entries));
4032
4033 // Invoke the Agent_OnUnload function
4034 if (unload_entry != NULL) {
4035 JavaThread* thread = JavaThread::current();
4036 ThreadToNativeFromVM ttn(thread);
4037 HandleMark hm(thread);
4038 (*unload_entry)(&main_vm);
4039 }
4040 }
4041 }
4042
4043 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4044 // Invokes JVM_OnLoad
4045 void Threads::create_vm_init_libraries() {
4046 extern struct JavaVM_ main_vm;
4047 AgentLibrary* agent;
4048
4049 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4050 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4051
4052 if (on_load_entry != NULL) {
4053 // Invoke the JVM_OnLoad function
4054 JavaThread* thread = JavaThread::current();
4055 ThreadToNativeFromVM ttn(thread);
4056 HandleMark hm(thread);
4057 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4058 if (err != JNI_OK) {
4059 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4060 }
4061 } else {
4062 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4063 }
4064 }
4065 }
4066
4067 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4068 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4069
4070 JavaThread* java_thread = NULL;
4071 // Sequential search for now. Need to do better optimization later.
4072 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4073 oop tobj = thread->threadObj();
4074 if (!thread->is_exiting() &&
4075 tobj != NULL &&
4076 java_tid == java_lang_Thread::thread_id(tobj)) {
4077 java_thread = thread;
4078 break;
4079 }
4080 }
4081 return java_thread;
4082 }
4083
4084
4085 // Last thread running calls java.lang.Shutdown.shutdown()
4086 void JavaThread::invoke_shutdown_hooks() {
4087 HandleMark hm(this);
4088
4089 // We could get here with a pending exception, if so clear it now.
4090 if (this->has_pending_exception()) {
4091 this->clear_pending_exception();
4092 }
4093
4094 EXCEPTION_MARK;
4095 Klass* shutdown_klass =
4096 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4097 THREAD);
4098 if (shutdown_klass != NULL) {
4099 // SystemDictionary::resolve_or_null will return null if there was
4100 // an exception. If we cannot load the Shutdown class, just don't
4101 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4102 // and finalizers (if runFinalizersOnExit is set) won't be run.
4103 // Note that if a shutdown hook was registered or runFinalizersOnExit
4104 // was called, the Shutdown class would have already been loaded
4105 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4106 JavaValue result(T_VOID);
4107 JavaCalls::call_static(&result,
4108 shutdown_klass,
4109 vmSymbols::shutdown_method_name(),
4110 vmSymbols::void_method_signature(),
4111 THREAD);
4112 }
4113 CLEAR_PENDING_EXCEPTION;
4114 }
4115
4116 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4117 // the program falls off the end of main(). Another VM exit path is through
4118 // vm_exit() when the program calls System.exit() to return a value or when
4119 // there is a serious error in VM. The two shutdown paths are not exactly
4120 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4121 // and VM_Exit op at VM level.
4122 //
4123 // Shutdown sequence:
4124 // + Shutdown native memory tracking if it is on
4125 // + Wait until we are the last non-daemon thread to execute
4126 // <-- every thing is still working at this moment -->
4127 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4128 // shutdown hooks, run finalizers if finalization-on-exit
4129 // + Call before_exit(), prepare for VM exit
4130 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4131 // currently the only user of this mechanism is File.deleteOnExit())
4132 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4133 // post thread end and vm death events to JVMTI,
4134 // stop signal thread
4135 // + Call JavaThread::exit(), it will:
4136 // > release JNI handle blocks, remove stack guard pages
4137 // > remove this thread from Threads list
4138 // <-- no more Java code from this thread after this point -->
4139 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4140 // the compiler threads at safepoint
4141 // <-- do not use anything that could get blocked by Safepoint -->
4142 // + Disable tracing at JNI/JVM barriers
4143 // + Set _vm_exited flag for threads that are still running native code
4144 // + Delete this thread
4145 // + Call exit_globals()
4146 // > deletes tty
4147 // > deletes PerfMemory resources
4148 // + Return to caller
4149
4150 bool Threads::destroy_vm() {
4151 JavaThread* thread = JavaThread::current();
4152
4153 #ifdef ASSERT
4154 _vm_complete = false;
4155 #endif
4156 // Wait until we are the last non-daemon thread to execute
4157 { MutexLocker nu(Threads_lock);
4158 while (Threads::number_of_non_daemon_threads() > 1)
4159 // This wait should make safepoint checks, wait without a timeout,
4160 // and wait as a suspend-equivalent condition.
4161 //
4162 // Note: If the FlatProfiler is running and this thread is waiting
4163 // for another non-daemon thread to finish, then the FlatProfiler
4164 // is waiting for the external suspend request on this thread to
4165 // complete. wait_for_ext_suspend_completion() will eventually
4166 // timeout, but that takes time. Making this wait a suspend-
4167 // equivalent condition solves that timeout problem.
4168 //
4169 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4170 Mutex::_as_suspend_equivalent_flag);
4171 }
4172
4173 // Hang forever on exit if we are reporting an error.
4174 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4175 os::infinite_sleep();
4176 }
4177 os::wait_for_keypress_at_exit();
4178
4179 // run Java level shutdown hooks
4180 thread->invoke_shutdown_hooks();
4181
4182 before_exit(thread);
4183
4184 thread->exit(true);
4185
4186 // Stop VM thread.
4187 {
4188 // 4945125 The vm thread comes to a safepoint during exit.
4189 // GC vm_operations can get caught at the safepoint, and the
4190 // heap is unparseable if they are caught. Grab the Heap_lock
4191 // to prevent this. The GC vm_operations will not be able to
4192 // queue until after the vm thread is dead. After this point,
4193 // we'll never emerge out of the safepoint before the VM exits.
4194
4195 MutexLocker ml(Heap_lock);
4196
4197 VMThread::wait_for_vm_thread_exit();
4198 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4199 VMThread::destroy();
4200 }
4201
4202 // clean up ideal graph printers
4203 #if defined(COMPILER2) && !defined(PRODUCT)
4204 IdealGraphPrinter::clean_up();
4205 #endif
4206
4207 // Now, all Java threads are gone except daemon threads. Daemon threads
4208 // running Java code or in VM are stopped by the Safepoint. However,
4209 // daemon threads executing native code are still running. But they
4210 // will be stopped at native=>Java/VM barriers. Note that we can't
4211 // simply kill or suspend them, as it is inherently deadlock-prone.
4212
4213 VM_Exit::set_vm_exited();
4214
4215 notify_vm_shutdown();
4216
4217 delete thread;
4218
4219 #if INCLUDE_JVMCI
4220 if (JVMCICounterSize > 0) {
4221 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4222 }
4223 #endif
4224
4225 // exit_globals() will delete tty
4226 exit_globals();
4227
4228 LogConfiguration::finalize();
4229
4230 return true;
4231 }
4232
4233
4234 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4235 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4236 return is_supported_jni_version(version);
4237 }
4238
4239
4240 jboolean Threads::is_supported_jni_version(jint version) {
4241 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4242 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4243 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4244 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4245 if (version == JNI_VERSION_9) return JNI_TRUE;
4246 return JNI_FALSE;
4247 }
4248
4249
4250 void Threads::add(JavaThread* p, bool force_daemon) {
4251 // The threads lock must be owned at this point
4252 assert_locked_or_safepoint(Threads_lock);
4253
4254 // See the comment for this method in thread.hpp for its purpose and
4255 // why it is called here.
4256 p->initialize_queues();
4257 p->set_next(_thread_list);
4258 _thread_list = p;
4259 _number_of_threads++;
4260 oop threadObj = p->threadObj();
4261 bool daemon = true;
4262 // Bootstrapping problem: threadObj can be null for initial
4263 // JavaThread (or for threads attached via JNI)
4264 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4265 _number_of_non_daemon_threads++;
4266 daemon = false;
4267 }
4268
4269 ThreadService::add_thread(p, daemon);
4270
4271 // Possible GC point.
4272 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4273 }
4274
4275 void Threads::remove(JavaThread* p) {
4276
4277 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4278 ObjectSynchronizer::omFlush(p);
4279
4280 // Extra scope needed for Thread_lock, so we can check
4281 // that we do not remove thread without safepoint code notice
4282 { MutexLocker ml(Threads_lock);
4283
4284 assert(includes(p), "p must be present");
4285
4286 JavaThread* current = _thread_list;
4287 JavaThread* prev = NULL;
4288
4289 while (current != p) {
4290 prev = current;
4291 current = current->next();
4292 }
4293
4294 if (prev) {
4295 prev->set_next(current->next());
4296 } else {
4297 _thread_list = p->next();
4298 }
4299 _number_of_threads--;
4300 oop threadObj = p->threadObj();
4301 bool daemon = true;
4302 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4303 _number_of_non_daemon_threads--;
4304 daemon = false;
4305
4306 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4307 // on destroy_vm will wake up.
4308 if (number_of_non_daemon_threads() == 1) {
4309 Threads_lock->notify_all();
4310 }
4311 }
4312 ThreadService::remove_thread(p, daemon);
4313
4314 // Make sure that safepoint code disregard this thread. This is needed since
4315 // the thread might mess around with locks after this point. This can cause it
4316 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4317 // of this thread since it is removed from the queue.
4318 p->set_terminated_value();
4319 } // unlock Threads_lock
4320
4321 // Since Events::log uses a lock, we grab it outside the Threads_lock
4322 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4323 }
4324
4325 // Threads_lock must be held when this is called (or must be called during a safepoint)
4326 bool Threads::includes(JavaThread* p) {
4327 assert(Threads_lock->is_locked(), "sanity check");
4328 ALL_JAVA_THREADS(q) {
4329 if (q == p) {
4330 return true;
4331 }
4332 }
4333 return false;
4334 }
4335
4336 // Operations on the Threads list for GC. These are not explicitly locked,
4337 // but the garbage collector must provide a safe context for them to run.
4338 // In particular, these things should never be called when the Threads_lock
4339 // is held by some other thread. (Note: the Safepoint abstraction also
4340 // uses the Threads_lock to guarantee this property. It also makes sure that
4341 // all threads gets blocked when exiting or starting).
4342
4343 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4344 ALL_JAVA_THREADS(p) {
4345 p->oops_do(f, cf);
4346 }
4347 VMThread::vm_thread()->oops_do(f, cf);
4348 }
4349
4350 void Threads::change_thread_claim_parity() {
4351 // Set the new claim parity.
4352 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4353 "Not in range.");
4354 _thread_claim_parity++;
4355 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4356 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4357 "Not in range.");
4358 }
4359
4360 #ifdef ASSERT
4361 void Threads::assert_all_threads_claimed() {
4362 ALL_JAVA_THREADS(p) {
4363 const int thread_parity = p->oops_do_parity();
4364 assert((thread_parity == _thread_claim_parity),
4365 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4366 }
4367 VMThread* vmt = VMThread::vm_thread();
4368 const int thread_parity = vmt->oops_do_parity();
4369 assert((thread_parity == _thread_claim_parity),
4370 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4371 }
4372 #endif // ASSERT
4373
4374 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4375 int cp = Threads::thread_claim_parity();
4376 ALL_JAVA_THREADS(p) {
4377 if (p->claim_oops_do(is_par, cp)) {
4378 p->oops_do(f, cf);
4379 }
4380 }
4381 VMThread* vmt = VMThread::vm_thread();
4382 if (vmt->claim_oops_do(is_par, cp)) {
4383 vmt->oops_do(f, cf);
4384 }
4385 }
4386
4387 #if INCLUDE_ALL_GCS
4388 // Used by ParallelScavenge
4389 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4390 ALL_JAVA_THREADS(p) {
4391 q->enqueue(new ThreadRootsTask(p));
4392 }
4393 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4394 }
4395
4396 // Used by Parallel Old
4397 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4398 ALL_JAVA_THREADS(p) {
4399 q->enqueue(new ThreadRootsMarkingTask(p));
4400 }
4401 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4402 }
4403 #endif // INCLUDE_ALL_GCS
4404
4405 void Threads::nmethods_do(CodeBlobClosure* cf) {
4406 ALL_JAVA_THREADS(p) {
4407 // This is used by the code cache sweeper to mark nmethods that are active
4408 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4409 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4410 if(!p->is_Code_cache_sweeper_thread()) {
4411 p->nmethods_do(cf);
4412 }
4413 }
4414 }
4415
4416 void Threads::metadata_do(void f(Metadata*)) {
4417 ALL_JAVA_THREADS(p) {
4418 p->metadata_do(f);
4419 }
4420 }
4421
4422 class ThreadHandlesClosure : public ThreadClosure {
4423 void (*_f)(Metadata*);
4424 public:
4425 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4426 virtual void do_thread(Thread* thread) {
4427 thread->metadata_handles_do(_f);
4428 }
4429 };
4430
4431 void Threads::metadata_handles_do(void f(Metadata*)) {
4432 // Only walk the Handles in Thread.
4433 ThreadHandlesClosure handles_closure(f);
4434 threads_do(&handles_closure);
4435 }
4436
4437 void Threads::deoptimized_wrt_marked_nmethods() {
4438 ALL_JAVA_THREADS(p) {
4439 p->deoptimized_wrt_marked_nmethods();
4440 }
4441 }
4442
4443
4444 // Get count Java threads that are waiting to enter the specified monitor.
4445 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4446 address monitor,
4447 bool doLock) {
4448 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4449 "must grab Threads_lock or be at safepoint");
4450 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4451
4452 int i = 0;
4453 {
4454 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4455 ALL_JAVA_THREADS(p) {
4456 if (!p->can_call_java()) continue;
4457
4458 address pending = (address)p->current_pending_monitor();
4459 if (pending == monitor) { // found a match
4460 if (i < count) result->append(p); // save the first count matches
4461 i++;
4462 }
4463 }
4464 }
4465 return result;
4466 }
4467
4468
4469 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4470 bool doLock) {
4471 assert(doLock ||
4472 Threads_lock->owned_by_self() ||
4473 SafepointSynchronize::is_at_safepoint(),
4474 "must grab Threads_lock or be at safepoint");
4475
4476 // NULL owner means not locked so we can skip the search
4477 if (owner == NULL) return NULL;
4478
4479 {
4480 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4481 ALL_JAVA_THREADS(p) {
4482 // first, see if owner is the address of a Java thread
4483 if (owner == (address)p) return p;
4484 }
4485 }
4486 // Cannot assert on lack of success here since this function may be
4487 // used by code that is trying to report useful problem information
4488 // like deadlock detection.
4489 if (UseHeavyMonitors) return NULL;
4490
4491 // If we didn't find a matching Java thread and we didn't force use of
4492 // heavyweight monitors, then the owner is the stack address of the
4493 // Lock Word in the owning Java thread's stack.
4494 //
4495 JavaThread* the_owner = NULL;
4496 {
4497 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4498 ALL_JAVA_THREADS(q) {
4499 if (q->is_lock_owned(owner)) {
4500 the_owner = q;
4501 break;
4502 }
4503 }
4504 }
4505 // cannot assert on lack of success here; see above comment
4506 return the_owner;
4507 }
4508
4509 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4510 void Threads::print_on(outputStream* st, bool print_stacks,
4511 bool internal_format, bool print_concurrent_locks) {
4512 char buf[32];
4513 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4514
4515 st->print_cr("Full thread dump %s (%s %s):",
4516 Abstract_VM_Version::vm_name(),
4517 Abstract_VM_Version::vm_release(),
4518 Abstract_VM_Version::vm_info_string());
4519 st->cr();
4520
4521 #if INCLUDE_SERVICES
4522 // Dump concurrent locks
4523 ConcurrentLocksDump concurrent_locks;
4524 if (print_concurrent_locks) {
4525 concurrent_locks.dump_at_safepoint();
4526 }
4527 #endif // INCLUDE_SERVICES
4528
4529 ALL_JAVA_THREADS(p) {
4530 ResourceMark rm;
4531 p->print_on(st);
4532 if (print_stacks) {
4533 if (internal_format) {
4534 p->trace_stack();
4535 } else {
4536 p->print_stack_on(st);
4537 }
4538 }
4539 st->cr();
4540 #if INCLUDE_SERVICES
4541 if (print_concurrent_locks) {
4542 concurrent_locks.print_locks_on(p, st);
4543 }
4544 #endif // INCLUDE_SERVICES
4545 }
4546
4547 VMThread::vm_thread()->print_on(st);
4548 st->cr();
4549 Universe::heap()->print_gc_threads_on(st);
4550 WatcherThread* wt = WatcherThread::watcher_thread();
4551 if (wt != NULL) {
4552 wt->print_on(st);
4553 st->cr();
4554 }
4555 st->flush();
4556 }
4557
4558 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4559 int buflen, bool* found_current) {
4560 if (this_thread != NULL) {
4561 bool is_current = (current == this_thread);
4562 *found_current = *found_current || is_current;
4563 st->print("%s", is_current ? "=>" : " ");
4564
4565 st->print(PTR_FORMAT, p2i(this_thread));
4566 st->print(" ");
4567 this_thread->print_on_error(st, buf, buflen);
4568 st->cr();
4569 }
4570 }
4571
4572 class PrintOnErrorClosure : public ThreadClosure {
4573 outputStream* _st;
4574 Thread* _current;
4575 char* _buf;
4576 int _buflen;
4577 bool* _found_current;
4578 public:
4579 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4580 int buflen, bool* found_current) :
4581 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4582
4583 virtual void do_thread(Thread* thread) {
4584 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4585 }
4586 };
4587
4588 // Threads::print_on_error() is called by fatal error handler. It's possible
4589 // that VM is not at safepoint and/or current thread is inside signal handler.
4590 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4591 // memory (even in resource area), it might deadlock the error handler.
4592 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4593 int buflen) {
4594 bool found_current = false;
4595 st->print_cr("Java Threads: ( => current thread )");
4596 ALL_JAVA_THREADS(thread) {
4597 print_on_error(thread, st, current, buf, buflen, &found_current);
4598 }
4599 st->cr();
4600
4601 st->print_cr("Other Threads:");
4602 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4603 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4604
4605 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4606 Universe::heap()->gc_threads_do(&print_closure);
4607
4608 if (!found_current) {
4609 st->cr();
4610 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4611 current->print_on_error(st, buf, buflen);
4612 st->cr();
4613 }
4614 st->cr();
4615 st->print_cr("Threads with active compile tasks:");
4616 print_threads_compiling(st, buf, buflen);
4617 }
4618
4619 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4620 ALL_JAVA_THREADS(thread) {
4621 if (thread->is_Compiler_thread()) {
4622 CompilerThread* ct = (CompilerThread*) thread;
4623 if (ct->task() != NULL) {
4624 thread->print_name_on_error(st, buf, buflen);
4625 ct->task()->print(st, NULL, true, true);
4626 }
4627 }
4628 }
4629 }
4630
4631
4632 // Internal SpinLock and Mutex
4633 // Based on ParkEvent
4634
4635 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4636 //
4637 // We employ SpinLocks _only for low-contention, fixed-length
4638 // short-duration critical sections where we're concerned
4639 // about native mutex_t or HotSpot Mutex:: latency.
4640 // The mux construct provides a spin-then-block mutual exclusion
4641 // mechanism.
4642 //
4643 // Testing has shown that contention on the ListLock guarding gFreeList
4644 // is common. If we implement ListLock as a simple SpinLock it's common
4645 // for the JVM to devolve to yielding with little progress. This is true
4646 // despite the fact that the critical sections protected by ListLock are
4647 // extremely short.
4648 //
4649 // TODO-FIXME: ListLock should be of type SpinLock.
4650 // We should make this a 1st-class type, integrated into the lock
4651 // hierarchy as leaf-locks. Critically, the SpinLock structure
4652 // should have sufficient padding to avoid false-sharing and excessive
4653 // cache-coherency traffic.
4654
4655
4656 typedef volatile int SpinLockT;
4657
4658 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4659 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4660 return; // normal fast-path return
4661 }
4662
4663 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4664 TEVENT(SpinAcquire - ctx);
4665 int ctr = 0;
4666 int Yields = 0;
4667 for (;;) {
4668 while (*adr != 0) {
4669 ++ctr;
4670 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4671 if (Yields > 5) {
4672 os::naked_short_sleep(1);
4673 } else {
4674 os::naked_yield();
4675 ++Yields;
4676 }
4677 } else {
4678 SpinPause();
4679 }
4680 }
4681 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4682 }
4683 }
4684
4685 void Thread::SpinRelease(volatile int * adr) {
4686 assert(*adr != 0, "invariant");
4687 OrderAccess::fence(); // guarantee at least release consistency.
4688 // Roach-motel semantics.
4689 // It's safe if subsequent LDs and STs float "up" into the critical section,
4690 // but prior LDs and STs within the critical section can't be allowed
4691 // to reorder or float past the ST that releases the lock.
4692 // Loads and stores in the critical section - which appear in program
4693 // order before the store that releases the lock - must also appear
4694 // before the store that releases the lock in memory visibility order.
4695 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4696 // the ST of 0 into the lock-word which releases the lock, so fence
4697 // more than covers this on all platforms.
4698 *adr = 0;
4699 }
4700
4701 // muxAcquire and muxRelease:
4702 //
4703 // * muxAcquire and muxRelease support a single-word lock-word construct.
4704 // The LSB of the word is set IFF the lock is held.
4705 // The remainder of the word points to the head of a singly-linked list
4706 // of threads blocked on the lock.
4707 //
4708 // * The current implementation of muxAcquire-muxRelease uses its own
4709 // dedicated Thread._MuxEvent instance. If we're interested in
4710 // minimizing the peak number of extant ParkEvent instances then
4711 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4712 // as certain invariants were satisfied. Specifically, care would need
4713 // to be taken with regards to consuming unpark() "permits".
4714 // A safe rule of thumb is that a thread would never call muxAcquire()
4715 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4716 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4717 // consume an unpark() permit intended for monitorenter, for instance.
4718 // One way around this would be to widen the restricted-range semaphore
4719 // implemented in park(). Another alternative would be to provide
4720 // multiple instances of the PlatformEvent() for each thread. One
4721 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4722 //
4723 // * Usage:
4724 // -- Only as leaf locks
4725 // -- for short-term locking only as muxAcquire does not perform
4726 // thread state transitions.
4727 //
4728 // Alternatives:
4729 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4730 // but with parking or spin-then-park instead of pure spinning.
4731 // * Use Taura-Oyama-Yonenzawa locks.
4732 // * It's possible to construct a 1-0 lock if we encode the lockword as
4733 // (List,LockByte). Acquire will CAS the full lockword while Release
4734 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4735 // acquiring threads use timers (ParkTimed) to detect and recover from
4736 // the stranding window. Thread/Node structures must be aligned on 256-byte
4737 // boundaries by using placement-new.
4738 // * Augment MCS with advisory back-link fields maintained with CAS().
4739 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4740 // The validity of the backlinks must be ratified before we trust the value.
4741 // If the backlinks are invalid the exiting thread must back-track through the
4742 // the forward links, which are always trustworthy.
4743 // * Add a successor indication. The LockWord is currently encoded as
4744 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4745 // to provide the usual futile-wakeup optimization.
4746 // See RTStt for details.
4747 // * Consider schedctl.sc_nopreempt to cover the critical section.
4748 //
4749
4750
4751 typedef volatile intptr_t MutexT; // Mux Lock-word
4752 enum MuxBits { LOCKBIT = 1 };
4753
4754 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4755 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4756 if (w == 0) return;
4757 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4758 return;
4759 }
4760
4761 TEVENT(muxAcquire - Contention);
4762 ParkEvent * const Self = Thread::current()->_MuxEvent;
4763 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4764 for (;;) {
4765 int its = (os::is_MP() ? 100 : 0) + 1;
4766
4767 // Optional spin phase: spin-then-park strategy
4768 while (--its >= 0) {
4769 w = *Lock;
4770 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4771 return;
4772 }
4773 }
4774
4775 Self->reset();
4776 Self->OnList = intptr_t(Lock);
4777 // The following fence() isn't _strictly necessary as the subsequent
4778 // CAS() both serializes execution and ratifies the fetched *Lock value.
4779 OrderAccess::fence();
4780 for (;;) {
4781 w = *Lock;
4782 if ((w & LOCKBIT) == 0) {
4783 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4784 Self->OnList = 0; // hygiene - allows stronger asserts
4785 return;
4786 }
4787 continue; // Interference -- *Lock changed -- Just retry
4788 }
4789 assert(w & LOCKBIT, "invariant");
4790 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4791 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4792 }
4793
4794 while (Self->OnList != 0) {
4795 Self->park();
4796 }
4797 }
4798 }
4799
4800 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4801 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4802 if (w == 0) return;
4803 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4804 return;
4805 }
4806
4807 TEVENT(muxAcquire - Contention);
4808 ParkEvent * ReleaseAfter = NULL;
4809 if (ev == NULL) {
4810 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4811 }
4812 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4813 for (;;) {
4814 guarantee(ev->OnList == 0, "invariant");
4815 int its = (os::is_MP() ? 100 : 0) + 1;
4816
4817 // Optional spin phase: spin-then-park strategy
4818 while (--its >= 0) {
4819 w = *Lock;
4820 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4821 if (ReleaseAfter != NULL) {
4822 ParkEvent::Release(ReleaseAfter);
4823 }
4824 return;
4825 }
4826 }
4827
4828 ev->reset();
4829 ev->OnList = intptr_t(Lock);
4830 // The following fence() isn't _strictly necessary as the subsequent
4831 // CAS() both serializes execution and ratifies the fetched *Lock value.
4832 OrderAccess::fence();
4833 for (;;) {
4834 w = *Lock;
4835 if ((w & LOCKBIT) == 0) {
4836 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4837 ev->OnList = 0;
4838 // We call ::Release while holding the outer lock, thus
4839 // artificially lengthening the critical section.
4840 // Consider deferring the ::Release() until the subsequent unlock(),
4841 // after we've dropped the outer lock.
4842 if (ReleaseAfter != NULL) {
4843 ParkEvent::Release(ReleaseAfter);
4844 }
4845 return;
4846 }
4847 continue; // Interference -- *Lock changed -- Just retry
4848 }
4849 assert(w & LOCKBIT, "invariant");
4850 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4851 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4852 }
4853
4854 while (ev->OnList != 0) {
4855 ev->park();
4856 }
4857 }
4858 }
4859
4860 // Release() must extract a successor from the list and then wake that thread.
4861 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4862 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4863 // Release() would :
4864 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4865 // (B) Extract a successor from the private list "in-hand"
4866 // (C) attempt to CAS() the residual back into *Lock over null.
4867 // If there were any newly arrived threads and the CAS() would fail.
4868 // In that case Release() would detach the RATs, re-merge the list in-hand
4869 // with the RATs and repeat as needed. Alternately, Release() might
4870 // detach and extract a successor, but then pass the residual list to the wakee.
4871 // The wakee would be responsible for reattaching and remerging before it
4872 // competed for the lock.
4873 //
4874 // Both "pop" and DMR are immune from ABA corruption -- there can be
4875 // multiple concurrent pushers, but only one popper or detacher.
4876 // This implementation pops from the head of the list. This is unfair,
4877 // but tends to provide excellent throughput as hot threads remain hot.
4878 // (We wake recently run threads first).
4879 //
4880 // All paths through muxRelease() will execute a CAS.
4881 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4882 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4883 // executed within the critical section are complete and globally visible before the
4884 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4885 void Thread::muxRelease(volatile intptr_t * Lock) {
4886 for (;;) {
4887 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4888 assert(w & LOCKBIT, "invariant");
4889 if (w == LOCKBIT) return;
4890 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4891 assert(List != NULL, "invariant");
4892 assert(List->OnList == intptr_t(Lock), "invariant");
4893 ParkEvent * const nxt = List->ListNext;
4894 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4895
4896 // The following CAS() releases the lock and pops the head element.
4897 // The CAS() also ratifies the previously fetched lock-word value.
4898 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4899 continue;
4900 }
4901 List->OnList = 0;
4902 OrderAccess::fence();
4903 List->unpark();
4904 return;
4905 }
4906 }
4907
4908
4909 void Threads::verify() {
4910 ALL_JAVA_THREADS(p) {
4911 p->verify();
4912 }
4913 VMThread* thread = VMThread::vm_thread();
4914 if (thread != NULL) thread->verify();
4915 }