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/valueKlass.hpp"
54 #include "oops/verifyOopClosure.hpp"
55 #include "prims/jvm.h"
56 #include "prims/jvm_misc.hpp"
57 #include "prims/jvmtiExport.hpp"
58 #include "prims/jvmtiThreadState.hpp"
59 #include "prims/privilegedStack.hpp"
60 #include "runtime/arguments.hpp"
61 #include "runtime/atomic.hpp"
62 #include "runtime/biasedLocking.hpp"
63 #include "runtime/commandLineFlagConstraintList.hpp"
64 #include "runtime/commandLineFlagWriteableList.hpp"
65 #include "runtime/commandLineFlagRangeList.hpp"
66 #include "runtime/deoptimization.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 _buffered_values_dealiaser = NULL;
284
285 #ifdef CHECK_UNHANDLED_OOPS
286 if (CheckUnhandledOops) {
287 _unhandled_oops = new UnhandledOops(this);
288 }
289 #endif // CHECK_UNHANDLED_OOPS
290 #ifdef ASSERT
291 if (UseBiasedLocking) {
292 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
293 assert(this == _real_malloc_address ||
294 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
295 "bug in forced alignment of thread objects");
296 }
297 #endif // ASSERT
298 }
299
300 void Thread::initialize_thread_current() {
301 #ifndef USE_LIBRARY_BASED_TLS_ONLY
302 assert(_thr_current == NULL, "Thread::current already initialized");
303 _thr_current = this;
304 #endif
305 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
306 ThreadLocalStorage::set_thread(this);
307 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
308 }
309
310 void Thread::clear_thread_current() {
311 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
312 #ifndef USE_LIBRARY_BASED_TLS_ONLY
313 _thr_current = NULL;
314 #endif
315 ThreadLocalStorage::set_thread(NULL);
316 }
317
318 void Thread::record_stack_base_and_size() {
319 set_stack_base(os::current_stack_base());
320 set_stack_size(os::current_stack_size());
321 // CR 7190089: on Solaris, primordial thread's stack is adjusted
322 // in initialize_thread(). Without the adjustment, stack size is
323 // incorrect if stack is set to unlimited (ulimit -s unlimited).
324 // So far, only Solaris has real implementation of initialize_thread().
325 //
326 // set up any platform-specific state.
327 os::initialize_thread(this);
328
329 // Set stack limits after thread is initialized.
330 if (is_Java_thread()) {
331 ((JavaThread*) this)->set_stack_overflow_limit();
332 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
333 }
334 #if INCLUDE_NMT
335 // record thread's native stack, stack grows downward
336 MemTracker::record_thread_stack(stack_end(), stack_size());
337 #endif // INCLUDE_NMT
338 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
339 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
340 os::current_thread_id(), p2i(stack_base() - stack_size()),
341 p2i(stack_base()), stack_size()/1024);
342 }
343
344
345 Thread::~Thread() {
346 EVENT_THREAD_DESTRUCT(this);
347
348 // stack_base can be NULL if the thread is never started or exited before
349 // record_stack_base_and_size called. Although, we would like to ensure
350 // that all started threads do call record_stack_base_and_size(), there is
351 // not proper way to enforce that.
352 #if INCLUDE_NMT
353 if (_stack_base != NULL) {
354 MemTracker::release_thread_stack(stack_end(), stack_size());
355 #ifdef ASSERT
356 set_stack_base(NULL);
357 #endif
358 }
359 #endif // INCLUDE_NMT
360
361 // deallocate data structures
362 delete resource_area();
363 // since the handle marks are using the handle area, we have to deallocated the root
364 // handle mark before deallocating the thread's handle area,
365 assert(last_handle_mark() != NULL, "check we have an element");
366 delete last_handle_mark();
367 assert(last_handle_mark() == NULL, "check we have reached the end");
368
369 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
370 // We NULL out the fields for good hygiene.
371 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
372 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
373 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
374 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
375
376 delete handle_area();
377 delete metadata_handles();
378
379 // SR_handler uses this as a termination indicator -
380 // needs to happen before os::free_thread()
381 delete _SR_lock;
382 _SR_lock = NULL;
383
384 // osthread() can be NULL, if creation of thread failed.
385 if (osthread() != NULL) os::free_thread(osthread());
386
387 // clear Thread::current if thread is deleting itself.
388 // Needed to ensure JNI correctly detects non-attached threads.
389 if (this == Thread::current()) {
390 clear_thread_current();
391 }
392
393 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
394 }
395
396 // NOTE: dummy function for assertion purpose.
397 void Thread::run() {
398 ShouldNotReachHere();
399 }
400
401 #ifdef ASSERT
402 // Private method to check for dangling thread pointer
403 void check_for_dangling_thread_pointer(Thread *thread) {
404 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
405 "possibility of dangling Thread pointer");
406 }
407 #endif
408
409 ThreadPriority Thread::get_priority(const Thread* const thread) {
410 ThreadPriority priority;
411 // Can return an error!
412 (void)os::get_priority(thread, priority);
413 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
414 return priority;
415 }
416
417 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
418 debug_only(check_for_dangling_thread_pointer(thread);)
419 // Can return an error!
420 (void)os::set_priority(thread, priority);
421 }
422
423
424 void Thread::start(Thread* thread) {
425 // Start is different from resume in that its safety is guaranteed by context or
426 // being called from a Java method synchronized on the Thread object.
427 if (!DisableStartThread) {
428 if (thread->is_Java_thread()) {
429 // Initialize the thread state to RUNNABLE before starting this thread.
430 // Can not set it after the thread started because we do not know the
431 // exact thread state at that time. It could be in MONITOR_WAIT or
432 // in SLEEPING or some other state.
433 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
434 java_lang_Thread::RUNNABLE);
435 }
436 os::start_thread(thread);
437 }
438 }
439
440 // Enqueue a VM_Operation to do the job for us - sometime later
441 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
442 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
443 VMThread::execute(vm_stop);
444 }
445
446
447 // Check if an external suspend request has completed (or has been
448 // cancelled). Returns true if the thread is externally suspended and
449 // false otherwise.
450 //
451 // The bits parameter returns information about the code path through
452 // the routine. Useful for debugging:
453 //
454 // set in is_ext_suspend_completed():
455 // 0x00000001 - routine was entered
456 // 0x00000010 - routine return false at end
457 // 0x00000100 - thread exited (return false)
458 // 0x00000200 - suspend request cancelled (return false)
459 // 0x00000400 - thread suspended (return true)
460 // 0x00001000 - thread is in a suspend equivalent state (return true)
461 // 0x00002000 - thread is native and walkable (return true)
462 // 0x00004000 - thread is native_trans and walkable (needed retry)
463 //
464 // set in wait_for_ext_suspend_completion():
465 // 0x00010000 - routine was entered
466 // 0x00020000 - suspend request cancelled before loop (return false)
467 // 0x00040000 - thread suspended before loop (return true)
468 // 0x00080000 - suspend request cancelled in loop (return false)
469 // 0x00100000 - thread suspended in loop (return true)
470 // 0x00200000 - suspend not completed during retry loop (return false)
471
472 // Helper class for tracing suspend wait debug bits.
473 //
474 // 0x00000100 indicates that the target thread exited before it could
475 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
476 // 0x00080000 each indicate a cancelled suspend request so they don't
477 // count as wait failures either.
478 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
479
480 class TraceSuspendDebugBits : public StackObj {
481 private:
482 JavaThread * jt;
483 bool is_wait;
484 bool called_by_wait; // meaningful when !is_wait
485 uint32_t * bits;
486
487 public:
488 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
489 uint32_t *_bits) {
490 jt = _jt;
491 is_wait = _is_wait;
492 called_by_wait = _called_by_wait;
493 bits = _bits;
494 }
495
496 ~TraceSuspendDebugBits() {
497 if (!is_wait) {
498 #if 1
499 // By default, don't trace bits for is_ext_suspend_completed() calls.
500 // That trace is very chatty.
501 return;
502 #else
503 if (!called_by_wait) {
504 // If tracing for is_ext_suspend_completed() is enabled, then only
505 // trace calls to it from wait_for_ext_suspend_completion()
506 return;
507 }
508 #endif
509 }
510
511 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
512 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
513 MutexLocker ml(Threads_lock); // needed for get_thread_name()
514 ResourceMark rm;
515
516 tty->print_cr(
517 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
518 jt->get_thread_name(), *bits);
519
520 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
521 }
522 }
523 }
524 };
525 #undef DEBUG_FALSE_BITS
526
527
528 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
529 uint32_t *bits) {
530 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
531
532 bool did_trans_retry = false; // only do thread_in_native_trans retry once
533 bool do_trans_retry; // flag to force the retry
534
535 *bits |= 0x00000001;
536
537 do {
538 do_trans_retry = false;
539
540 if (is_exiting()) {
541 // Thread is in the process of exiting. This is always checked
542 // first to reduce the risk of dereferencing a freed JavaThread.
543 *bits |= 0x00000100;
544 return false;
545 }
546
547 if (!is_external_suspend()) {
548 // Suspend request is cancelled. This is always checked before
549 // is_ext_suspended() to reduce the risk of a rogue resume
550 // confusing the thread that made the suspend request.
551 *bits |= 0x00000200;
552 return false;
553 }
554
555 if (is_ext_suspended()) {
556 // thread is suspended
557 *bits |= 0x00000400;
558 return true;
559 }
560
561 // Now that we no longer do hard suspends of threads running
562 // native code, the target thread can be changing thread state
563 // while we are in this routine:
564 //
565 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
566 //
567 // We save a copy of the thread state as observed at this moment
568 // and make our decision about suspend completeness based on the
569 // copy. This closes the race where the thread state is seen as
570 // _thread_in_native_trans in the if-thread_blocked check, but is
571 // seen as _thread_blocked in if-thread_in_native_trans check.
572 JavaThreadState save_state = thread_state();
573
574 if (save_state == _thread_blocked && is_suspend_equivalent()) {
575 // If the thread's state is _thread_blocked and this blocking
576 // condition is known to be equivalent to a suspend, then we can
577 // consider the thread to be externally suspended. This means that
578 // the code that sets _thread_blocked has been modified to do
579 // self-suspension if the blocking condition releases. We also
580 // used to check for CONDVAR_WAIT here, but that is now covered by
581 // the _thread_blocked with self-suspension check.
582 //
583 // Return true since we wouldn't be here unless there was still an
584 // external suspend request.
585 *bits |= 0x00001000;
586 return true;
587 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
588 // Threads running native code will self-suspend on native==>VM/Java
589 // transitions. If its stack is walkable (should always be the case
590 // unless this function is called before the actual java_suspend()
591 // call), then the wait is done.
592 *bits |= 0x00002000;
593 return true;
594 } else if (!called_by_wait && !did_trans_retry &&
595 save_state == _thread_in_native_trans &&
596 frame_anchor()->walkable()) {
597 // The thread is transitioning from thread_in_native to another
598 // thread state. check_safepoint_and_suspend_for_native_trans()
599 // will force the thread to self-suspend. If it hasn't gotten
600 // there yet we may have caught the thread in-between the native
601 // code check above and the self-suspend. Lucky us. If we were
602 // called by wait_for_ext_suspend_completion(), then it
603 // will be doing the retries so we don't have to.
604 //
605 // Since we use the saved thread state in the if-statement above,
606 // there is a chance that the thread has already transitioned to
607 // _thread_blocked by the time we get here. In that case, we will
608 // make a single unnecessary pass through the logic below. This
609 // doesn't hurt anything since we still do the trans retry.
610
611 *bits |= 0x00004000;
612
613 // Once the thread leaves thread_in_native_trans for another
614 // thread state, we break out of this retry loop. We shouldn't
615 // need this flag to prevent us from getting back here, but
616 // sometimes paranoia is good.
617 did_trans_retry = true;
618
619 // We wait for the thread to transition to a more usable state.
620 for (int i = 1; i <= SuspendRetryCount; i++) {
621 // We used to do an "os::yield_all(i)" call here with the intention
622 // that yielding would increase on each retry. However, the parameter
623 // is ignored on Linux which means the yield didn't scale up. Waiting
624 // on the SR_lock below provides a much more predictable scale up for
625 // the delay. It also provides a simple/direct point to check for any
626 // safepoint requests from the VMThread
627
628 // temporarily drops SR_lock while doing wait with safepoint check
629 // (if we're a JavaThread - the WatcherThread can also call this)
630 // and increase delay with each retry
631 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
632
633 // check the actual thread state instead of what we saved above
634 if (thread_state() != _thread_in_native_trans) {
635 // the thread has transitioned to another thread state so
636 // try all the checks (except this one) one more time.
637 do_trans_retry = true;
638 break;
639 }
640 } // end retry loop
641
642
643 }
644 } while (do_trans_retry);
645
646 *bits |= 0x00000010;
647 return false;
648 }
649
650 // Wait for an external suspend request to complete (or be cancelled).
651 // Returns true if the thread is externally suspended and false otherwise.
652 //
653 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
654 uint32_t *bits) {
655 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
656 false /* !called_by_wait */, bits);
657
658 // local flag copies to minimize SR_lock hold time
659 bool is_suspended;
660 bool pending;
661 uint32_t reset_bits;
662
663 // set a marker so is_ext_suspend_completed() knows we are the caller
664 *bits |= 0x00010000;
665
666 // We use reset_bits to reinitialize the bits value at the top of
667 // each retry loop. This allows the caller to make use of any
668 // unused bits for their own marking purposes.
669 reset_bits = *bits;
670
671 {
672 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
673 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
674 delay, bits);
675 pending = is_external_suspend();
676 }
677 // must release SR_lock to allow suspension to complete
678
679 if (!pending) {
680 // A cancelled suspend request is the only false return from
681 // is_ext_suspend_completed() that keeps us from entering the
682 // retry loop.
683 *bits |= 0x00020000;
684 return false;
685 }
686
687 if (is_suspended) {
688 *bits |= 0x00040000;
689 return true;
690 }
691
692 for (int i = 1; i <= retries; i++) {
693 *bits = reset_bits; // reinit to only track last retry
694
695 // We used to do an "os::yield_all(i)" call here with the intention
696 // that yielding would increase on each retry. However, the parameter
697 // is ignored on Linux which means the yield didn't scale up. Waiting
698 // on the SR_lock below provides a much more predictable scale up for
699 // the delay. It also provides a simple/direct point to check for any
700 // safepoint requests from the VMThread
701
702 {
703 MutexLocker ml(SR_lock());
704 // wait with safepoint check (if we're a JavaThread - the WatcherThread
705 // can also call this) and increase delay with each retry
706 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
707
708 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
709 delay, bits);
710
711 // It is possible for the external suspend request to be cancelled
712 // (by a resume) before the actual suspend operation is completed.
713 // Refresh our local copy to see if we still need to wait.
714 pending = is_external_suspend();
715 }
716
717 if (!pending) {
718 // A cancelled suspend request is the only false return from
719 // is_ext_suspend_completed() that keeps us from staying in the
720 // retry loop.
721 *bits |= 0x00080000;
722 return false;
723 }
724
725 if (is_suspended) {
726 *bits |= 0x00100000;
727 return true;
728 }
729 } // end retry loop
730
731 // thread did not suspend after all our retries
732 *bits |= 0x00200000;
733 return false;
734 }
735
736 #ifndef PRODUCT
737 void JavaThread::record_jump(address target, address instr, const char* file,
738 int line) {
739
740 // This should not need to be atomic as the only way for simultaneous
741 // updates is via interrupts. Even then this should be rare or non-existent
742 // and we don't care that much anyway.
743
744 int index = _jmp_ring_index;
745 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
746 _jmp_ring[index]._target = (intptr_t) target;
747 _jmp_ring[index]._instruction = (intptr_t) instr;
748 _jmp_ring[index]._file = file;
749 _jmp_ring[index]._line = line;
750 }
751 #endif // PRODUCT
752
753 void Thread::interrupt(Thread* thread) {
754 debug_only(check_for_dangling_thread_pointer(thread);)
755 os::interrupt(thread);
756 }
757
758 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
759 debug_only(check_for_dangling_thread_pointer(thread);)
760 // Note: If clear_interrupted==false, this simply fetches and
761 // returns the value of the field osthread()->interrupted().
762 return os::is_interrupted(thread, clear_interrupted);
763 }
764
765
766 // GC Support
767 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
768 jint thread_parity = _oops_do_parity;
769 if (thread_parity != strong_roots_parity) {
770 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
771 if (res == thread_parity) {
772 return true;
773 } else {
774 guarantee(res == strong_roots_parity, "Or else what?");
775 return false;
776 }
777 }
778 return false;
779 }
780
781 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
782 active_handles()->oops_do(f);
783 // Do oop for ThreadShadow
784 f->do_oop((oop*)&_pending_exception);
785 handle_area()->oops_do(f);
786
787 if (MonitorInUseLists) {
788 // When using thread local monitor lists, we scan them here,
789 // and the remaining global monitors in ObjectSynchronizer::oops_do().
790 ObjectSynchronizer::thread_local_used_oops_do(this, f);
791 }
792 }
793
794 void Thread::metadata_handles_do(void f(Metadata*)) {
795 // Only walk the Handles in Thread.
796 if (metadata_handles() != NULL) {
797 for (int i = 0; i< metadata_handles()->length(); i++) {
798 f(metadata_handles()->at(i));
799 }
800 }
801 }
802
803 void Thread::print_on(outputStream* st) const {
804 // get_priority assumes osthread initialized
805 if (osthread() != NULL) {
806 int os_prio;
807 if (os::get_native_priority(this, &os_prio) == OS_OK) {
808 st->print("os_prio=%d ", os_prio);
809 }
810 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
811 ext().print_on(st);
812 osthread()->print_on(st);
813 }
814 debug_only(if (WizardMode) print_owned_locks_on(st);)
815 }
816
817 // Thread::print_on_error() is called by fatal error handler. Don't use
818 // any lock or allocate memory.
819 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
820 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
821
822 if (is_VM_thread()) { st->print("VMThread"); }
823 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
824 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
825 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
826 else { st->print("Thread"); }
827
828 if (is_Named_thread()) {
829 st->print(" \"%s\"", name());
830 }
831
832 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
833 p2i(stack_end()), p2i(stack_base()));
834
835 if (osthread()) {
836 st->print(" [id=%d]", osthread()->thread_id());
837 }
838 }
839
840 void Thread::print_value_on(outputStream* st) const {
841 if (is_Named_thread()) {
842 st->print(" \"%s\" ", name());
843 }
844 st->print(INTPTR_FORMAT, p2i(this)); // print address
845 }
846
847 void JavaThread::print_vt_buffer_stats_on(outputStream* st) const {
848 st->print_cr("%s:", this->name());
849 st->print_cr("\tChunks in use : %d", vtchunk_in_use());
850 st->print_cr("\tCached chunk : %d", local_free_chunk() == NULL ? 0 : 1);
851 st->print_cr("\tMax chunks : %d", vtchunk_max());
852 st->print_cr("\tReturned chunks : %d", vtchunk_total_returned());
853 st->print_cr("\tFailed chunk allocs : %d", vtchunk_total_failed());
854 st->print_cr("\tMemory buffered : " JLONG_FORMAT, vtchunk_total_memory_buffered());
855 st->print_cr("");
856 }
857
858 #ifdef ASSERT
859 void Thread::print_owned_locks_on(outputStream* st) const {
860 Monitor *cur = _owned_locks;
861 if (cur == NULL) {
862 st->print(" (no locks) ");
863 } else {
864 st->print_cr(" Locks owned:");
865 while (cur) {
866 cur->print_on(st);
867 cur = cur->next();
868 }
869 }
870 }
871
872 static int ref_use_count = 0;
873
874 bool Thread::owns_locks_but_compiled_lock() const {
875 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
876 if (cur != Compile_lock) return true;
877 }
878 return false;
879 }
880
881
882 #endif
883
884 #ifndef PRODUCT
885
886 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
887 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
888 // no threads which allow_vm_block's are held
889 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
890 // Check if current thread is allowed to block at a safepoint
891 if (!(_allow_safepoint_count == 0)) {
892 fatal("Possible safepoint reached by thread that does not allow it");
893 }
894 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
895 fatal("LEAF method calling lock?");
896 }
897
898 #ifdef ASSERT
899 if (potential_vm_operation && is_Java_thread()
900 && !Universe::is_bootstrapping()) {
901 // Make sure we do not hold any locks that the VM thread also uses.
902 // This could potentially lead to deadlocks
903 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
904 // Threads_lock is special, since the safepoint synchronization will not start before this is
905 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
906 // since it is used to transfer control between JavaThreads and the VMThread
907 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
908 if ((cur->allow_vm_block() &&
909 cur != Threads_lock &&
910 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
911 cur != VMOperationRequest_lock &&
912 cur != VMOperationQueue_lock) ||
913 cur->rank() == Mutex::special) {
914 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
915 }
916 }
917 }
918
919 if (GCALotAtAllSafepoints) {
920 // We could enter a safepoint here and thus have a gc
921 InterfaceSupport::check_gc_alot();
922 }
923 #endif
924 }
925 #endif
926
927 bool Thread::is_in_stack(address adr) const {
928 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
929 address end = os::current_stack_pointer();
930 // Allow non Java threads to call this without stack_base
931 if (_stack_base == NULL) return true;
932 if (stack_base() >= adr && adr >= end) return true;
933
934 return false;
935 }
936
937 bool Thread::is_in_usable_stack(address adr) const {
938 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
939 size_t usable_stack_size = _stack_size - stack_guard_size;
940
941 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
942 }
943
944
945 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
946 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
947 // used for compilation in the future. If that change is made, the need for these methods
948 // should be revisited, and they should be removed if possible.
949
950 bool Thread::is_lock_owned(address adr) const {
951 return on_local_stack(adr);
952 }
953
954 bool Thread::set_as_starting_thread() {
955 // NOTE: this must be called inside the main thread.
956 return os::create_main_thread((JavaThread*)this);
957 }
958
959 static void initialize_class(Symbol* class_name, TRAPS) {
960 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
961 InstanceKlass::cast(klass)->initialize(CHECK);
962 }
963
964
965 // Creates the initial ThreadGroup
966 static Handle create_initial_thread_group(TRAPS) {
967 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
968 InstanceKlass* ik = InstanceKlass::cast(k);
969
970 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
971 {
972 JavaValue result(T_VOID);
973 JavaCalls::call_special(&result,
974 system_instance,
975 ik,
976 vmSymbols::object_initializer_name(),
977 vmSymbols::void_method_signature(),
978 CHECK_NH);
979 }
980 Universe::set_system_thread_group(system_instance());
981
982 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
983 {
984 JavaValue result(T_VOID);
985 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
986 JavaCalls::call_special(&result,
987 main_instance,
988 ik,
989 vmSymbols::object_initializer_name(),
990 vmSymbols::threadgroup_string_void_signature(),
991 system_instance,
992 string,
993 CHECK_NH);
994 }
995 return main_instance;
996 }
997
998 // Creates the initial Thread
999 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1000 TRAPS) {
1001 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1002 InstanceKlass* ik = InstanceKlass::cast(k);
1003 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1004
1005 java_lang_Thread::set_thread(thread_oop(), thread);
1006 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1007 thread->set_threadObj(thread_oop());
1008
1009 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1010
1011 JavaValue result(T_VOID);
1012 JavaCalls::call_special(&result, thread_oop,
1013 ik,
1014 vmSymbols::object_initializer_name(),
1015 vmSymbols::threadgroup_string_void_signature(),
1016 thread_group,
1017 string,
1018 CHECK_NULL);
1019 return thread_oop();
1020 }
1021
1022 char java_runtime_name[128] = "";
1023 char java_runtime_version[128] = "";
1024
1025 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1026 static const char* get_java_runtime_name(TRAPS) {
1027 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1028 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1029 fieldDescriptor fd;
1030 bool found = k != NULL &&
1031 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1032 vmSymbols::string_signature(), &fd);
1033 if (found) {
1034 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1035 if (name_oop == NULL) {
1036 return NULL;
1037 }
1038 const char* name = java_lang_String::as_utf8_string(name_oop,
1039 java_runtime_name,
1040 sizeof(java_runtime_name));
1041 return name;
1042 } else {
1043 return NULL;
1044 }
1045 }
1046
1047 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1048 static const char* get_java_runtime_version(TRAPS) {
1049 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1050 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1051 fieldDescriptor fd;
1052 bool found = k != NULL &&
1053 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1054 vmSymbols::string_signature(), &fd);
1055 if (found) {
1056 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1057 if (name_oop == NULL) {
1058 return NULL;
1059 }
1060 const char* name = java_lang_String::as_utf8_string(name_oop,
1061 java_runtime_version,
1062 sizeof(java_runtime_version));
1063 return name;
1064 } else {
1065 return NULL;
1066 }
1067 }
1068
1069 // General purpose hook into Java code, run once when the VM is initialized.
1070 // The Java library method itself may be changed independently from the VM.
1071 static void call_postVMInitHook(TRAPS) {
1072 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1073 if (klass != NULL) {
1074 JavaValue result(T_VOID);
1075 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1076 vmSymbols::void_method_signature(),
1077 CHECK);
1078 }
1079 }
1080
1081 static void reset_vm_info_property(TRAPS) {
1082 // the vm info string
1083 ResourceMark rm(THREAD);
1084 const char *vm_info = VM_Version::vm_info_string();
1085
1086 // java.lang.System class
1087 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1088
1089 // setProperty arguments
1090 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1091 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1092
1093 // return value
1094 JavaValue r(T_OBJECT);
1095
1096 // public static String setProperty(String key, String value);
1097 JavaCalls::call_static(&r,
1098 klass,
1099 vmSymbols::setProperty_name(),
1100 vmSymbols::string_string_string_signature(),
1101 key_str,
1102 value_str,
1103 CHECK);
1104 }
1105
1106
1107 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1108 bool daemon, TRAPS) {
1109 assert(thread_group.not_null(), "thread group should be specified");
1110 assert(threadObj() == NULL, "should only create Java thread object once");
1111
1112 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1113 InstanceKlass* ik = InstanceKlass::cast(k);
1114 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1115
1116 java_lang_Thread::set_thread(thread_oop(), this);
1117 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1118 set_threadObj(thread_oop());
1119
1120 JavaValue result(T_VOID);
1121 if (thread_name != NULL) {
1122 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1123 // Thread gets assigned specified name and null target
1124 JavaCalls::call_special(&result,
1125 thread_oop,
1126 ik,
1127 vmSymbols::object_initializer_name(),
1128 vmSymbols::threadgroup_string_void_signature(),
1129 thread_group, // Argument 1
1130 name, // Argument 2
1131 THREAD);
1132 } else {
1133 // Thread gets assigned name "Thread-nnn" and null target
1134 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1135 JavaCalls::call_special(&result,
1136 thread_oop,
1137 ik,
1138 vmSymbols::object_initializer_name(),
1139 vmSymbols::threadgroup_runnable_void_signature(),
1140 thread_group, // Argument 1
1141 Handle(), // Argument 2
1142 THREAD);
1143 }
1144
1145
1146 if (daemon) {
1147 java_lang_Thread::set_daemon(thread_oop());
1148 }
1149
1150 if (HAS_PENDING_EXCEPTION) {
1151 return;
1152 }
1153
1154 Klass* group = SystemDictionary::ThreadGroup_klass();
1155 Handle threadObj(THREAD, this->threadObj());
1156
1157 JavaCalls::call_special(&result,
1158 thread_group,
1159 group,
1160 vmSymbols::add_method_name(),
1161 vmSymbols::thread_void_signature(),
1162 threadObj, // Arg 1
1163 THREAD);
1164 }
1165
1166 // NamedThread -- non-JavaThread subclasses with multiple
1167 // uniquely named instances should derive from this.
1168 NamedThread::NamedThread() : Thread() {
1169 _name = NULL;
1170 _processed_thread = NULL;
1171 _gc_id = GCId::undefined();
1172 }
1173
1174 NamedThread::~NamedThread() {
1175 if (_name != NULL) {
1176 FREE_C_HEAP_ARRAY(char, _name);
1177 _name = NULL;
1178 }
1179 }
1180
1181 void NamedThread::set_name(const char* format, ...) {
1182 guarantee(_name == NULL, "Only get to set name once.");
1183 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1184 guarantee(_name != NULL, "alloc failure");
1185 va_list ap;
1186 va_start(ap, format);
1187 jio_vsnprintf(_name, max_name_len, format, ap);
1188 va_end(ap);
1189 }
1190
1191 void NamedThread::initialize_named_thread() {
1192 set_native_thread_name(name());
1193 }
1194
1195 void NamedThread::print_on(outputStream* st) const {
1196 st->print("\"%s\" ", name());
1197 Thread::print_on(st);
1198 st->cr();
1199 }
1200
1201
1202 // ======= WatcherThread ========
1203
1204 // The watcher thread exists to simulate timer interrupts. It should
1205 // be replaced by an abstraction over whatever native support for
1206 // timer interrupts exists on the platform.
1207
1208 WatcherThread* WatcherThread::_watcher_thread = NULL;
1209 bool WatcherThread::_startable = false;
1210 volatile bool WatcherThread::_should_terminate = false;
1211
1212 WatcherThread::WatcherThread() : Thread() {
1213 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1214 if (os::create_thread(this, os::watcher_thread)) {
1215 _watcher_thread = this;
1216
1217 // Set the watcher thread to the highest OS priority which should not be
1218 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1219 // is created. The only normal thread using this priority is the reference
1220 // handler thread, which runs for very short intervals only.
1221 // If the VMThread's priority is not lower than the WatcherThread profiling
1222 // will be inaccurate.
1223 os::set_priority(this, MaxPriority);
1224 if (!DisableStartThread) {
1225 os::start_thread(this);
1226 }
1227 }
1228 }
1229
1230 int WatcherThread::sleep() const {
1231 // The WatcherThread does not participate in the safepoint protocol
1232 // for the PeriodicTask_lock because it is not a JavaThread.
1233 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1234
1235 if (_should_terminate) {
1236 // check for termination before we do any housekeeping or wait
1237 return 0; // we did not sleep.
1238 }
1239
1240 // remaining will be zero if there are no tasks,
1241 // causing the WatcherThread to sleep until a task is
1242 // enrolled
1243 int remaining = PeriodicTask::time_to_wait();
1244 int time_slept = 0;
1245
1246 // we expect this to timeout - we only ever get unparked when
1247 // we should terminate or when a new task has been enrolled
1248 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1249
1250 jlong time_before_loop = os::javaTimeNanos();
1251
1252 while (true) {
1253 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1254 remaining);
1255 jlong now = os::javaTimeNanos();
1256
1257 if (remaining == 0) {
1258 // if we didn't have any tasks we could have waited for a long time
1259 // consider the time_slept zero and reset time_before_loop
1260 time_slept = 0;
1261 time_before_loop = now;
1262 } else {
1263 // need to recalculate since we might have new tasks in _tasks
1264 time_slept = (int) ((now - time_before_loop) / 1000000);
1265 }
1266
1267 // Change to task list or spurious wakeup of some kind
1268 if (timedout || _should_terminate) {
1269 break;
1270 }
1271
1272 remaining = PeriodicTask::time_to_wait();
1273 if (remaining == 0) {
1274 // Last task was just disenrolled so loop around and wait until
1275 // another task gets enrolled
1276 continue;
1277 }
1278
1279 remaining -= time_slept;
1280 if (remaining <= 0) {
1281 break;
1282 }
1283 }
1284
1285 return time_slept;
1286 }
1287
1288 void WatcherThread::run() {
1289 assert(this == watcher_thread(), "just checking");
1290
1291 this->record_stack_base_and_size();
1292 this->set_native_thread_name(this->name());
1293 this->set_active_handles(JNIHandleBlock::allocate_block());
1294 while (true) {
1295 assert(watcher_thread() == Thread::current(), "thread consistency check");
1296 assert(watcher_thread() == this, "thread consistency check");
1297
1298 // Calculate how long it'll be until the next PeriodicTask work
1299 // should be done, and sleep that amount of time.
1300 int time_waited = sleep();
1301
1302 if (VMError::is_error_reported()) {
1303 // A fatal error has happened, the error handler(VMError::report_and_die)
1304 // should abort JVM after creating an error log file. However in some
1305 // rare cases, the error handler itself might deadlock. Here periodically
1306 // check for error reporting timeouts, and if it happens, just proceed to
1307 // abort the VM.
1308
1309 // This code is in WatcherThread because WatcherThread wakes up
1310 // periodically so the fatal error handler doesn't need to do anything;
1311 // also because the WatcherThread is less likely to crash than other
1312 // threads.
1313
1314 for (;;) {
1315 // Note: we use naked sleep in this loop because we want to avoid using
1316 // any kind of VM infrastructure which may be broken at this point.
1317 if (VMError::check_timeout()) {
1318 // We hit error reporting timeout. Error reporting was interrupted and
1319 // will be wrapping things up now (closing files etc). Give it some more
1320 // time, then quit the VM.
1321 os::naked_short_sleep(200);
1322 // Print a message to stderr.
1323 fdStream err(defaultStream::output_fd());
1324 err.print_raw_cr("# [ timer expired, abort... ]");
1325 // skip atexit/vm_exit/vm_abort hooks
1326 os::die();
1327 }
1328
1329 // Wait a second, then recheck for timeout.
1330 os::naked_short_sleep(999);
1331 }
1332 }
1333
1334 if (_should_terminate) {
1335 // check for termination before posting the next tick
1336 break;
1337 }
1338
1339 PeriodicTask::real_time_tick(time_waited);
1340 }
1341
1342 // Signal that it is terminated
1343 {
1344 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1345 _watcher_thread = NULL;
1346 Terminator_lock->notify();
1347 }
1348 }
1349
1350 void WatcherThread::start() {
1351 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1352
1353 if (watcher_thread() == NULL && _startable) {
1354 _should_terminate = false;
1355 // Create the single instance of WatcherThread
1356 new WatcherThread();
1357 }
1358 }
1359
1360 void WatcherThread::make_startable() {
1361 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1362 _startable = true;
1363 }
1364
1365 void WatcherThread::stop() {
1366 {
1367 // Follow normal safepoint aware lock enter protocol since the
1368 // WatcherThread is stopped by another JavaThread.
1369 MutexLocker ml(PeriodicTask_lock);
1370 _should_terminate = true;
1371
1372 WatcherThread* watcher = watcher_thread();
1373 if (watcher != NULL) {
1374 // unpark the WatcherThread so it can see that it should terminate
1375 watcher->unpark();
1376 }
1377 }
1378
1379 MutexLocker mu(Terminator_lock);
1380
1381 while (watcher_thread() != NULL) {
1382 // This wait should make safepoint checks, wait without a timeout,
1383 // and wait as a suspend-equivalent condition.
1384 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1385 Mutex::_as_suspend_equivalent_flag);
1386 }
1387 }
1388
1389 void WatcherThread::unpark() {
1390 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1391 PeriodicTask_lock->notify();
1392 }
1393
1394 void WatcherThread::print_on(outputStream* st) const {
1395 st->print("\"%s\" ", name());
1396 Thread::print_on(st);
1397 st->cr();
1398 }
1399
1400 // ======= JavaThread ========
1401
1402 #if INCLUDE_JVMCI
1403
1404 jlong* JavaThread::_jvmci_old_thread_counters;
1405
1406 bool jvmci_counters_include(JavaThread* thread) {
1407 oop threadObj = thread->threadObj();
1408 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1409 }
1410
1411 void JavaThread::collect_counters(typeArrayOop array) {
1412 if (JVMCICounterSize > 0) {
1413 MutexLocker tl(Threads_lock);
1414 for (int i = 0; i < array->length(); i++) {
1415 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1416 }
1417 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1418 if (jvmci_counters_include(tp)) {
1419 for (int i = 0; i < array->length(); i++) {
1420 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1421 }
1422 }
1423 }
1424 }
1425 }
1426
1427 #endif // INCLUDE_JVMCI
1428
1429 // A JavaThread is a normal Java thread
1430
1431 void JavaThread::initialize() {
1432 // Initialize fields
1433
1434 set_saved_exception_pc(NULL);
1435 set_threadObj(NULL);
1436 _anchor.clear();
1437 set_entry_point(NULL);
1438 set_jni_functions(jni_functions());
1439 set_callee_target(NULL);
1440 set_vm_result(NULL);
1441 set_vm_result_2(NULL);
1442 set_return_buffered_value(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 // Setup safepoint state info for this thread
1502 ThreadSafepointState::create(this);
1503
1504 debug_only(_java_call_counter = 0);
1505
1506 // JVMTI PopFrame support
1507 _popframe_condition = popframe_inactive;
1508 _popframe_preserved_args = NULL;
1509 _popframe_preserved_args_size = 0;
1510 _frames_to_pop_failed_realloc = 0;
1511
1512 // Buffered value types support
1513 _vt_alloc_ptr = NULL;
1514 _vt_alloc_limit = NULL;
1515 _local_free_chunk = NULL;
1516 _current_vtbuffer_mark = VTBuffer::mark_A;
1517 // Buffered value types instrumentation support
1518 _vtchunk_in_use = 0;
1519 _vtchunk_max = 0;
1520 _vtchunk_total_returned = 0;
1521 _vtchunk_total_failed = 0;
1522 _vtchunk_total_memory_buffered = 0;
1523
1524 pd_initialize();
1525 }
1526
1527 #if INCLUDE_ALL_GCS
1528 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1529 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1530 #endif // INCLUDE_ALL_GCS
1531
1532 JavaThread::JavaThread(bool is_attaching_via_jni) :
1533 Thread()
1534 #if INCLUDE_ALL_GCS
1535 , _satb_mark_queue(&_satb_mark_queue_set),
1536 _dirty_card_queue(&_dirty_card_queue_set)
1537 #endif // INCLUDE_ALL_GCS
1538 {
1539 initialize();
1540 if (is_attaching_via_jni) {
1541 _jni_attach_state = _attaching_via_jni;
1542 } else {
1543 _jni_attach_state = _not_attaching_via_jni;
1544 }
1545 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1546 }
1547
1548 bool JavaThread::reguard_stack(address cur_sp) {
1549 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1550 && _stack_guard_state != stack_guard_reserved_disabled) {
1551 return true; // Stack already guarded or guard pages not needed.
1552 }
1553
1554 if (register_stack_overflow()) {
1555 // For those architectures which have separate register and
1556 // memory stacks, we must check the register stack to see if
1557 // it has overflowed.
1558 return false;
1559 }
1560
1561 // Java code never executes within the yellow zone: the latter is only
1562 // there to provoke an exception during stack banging. If java code
1563 // is executing there, either StackShadowPages should be larger, or
1564 // some exception code in c1, c2 or the interpreter isn't unwinding
1565 // when it should.
1566 guarantee(cur_sp > stack_reserved_zone_base(),
1567 "not enough space to reguard - increase StackShadowPages");
1568 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1569 enable_stack_yellow_reserved_zone();
1570 if (reserved_stack_activation() != stack_base()) {
1571 set_reserved_stack_activation(stack_base());
1572 }
1573 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1574 set_reserved_stack_activation(stack_base());
1575 enable_stack_reserved_zone();
1576 }
1577 return true;
1578 }
1579
1580 bool JavaThread::reguard_stack(void) {
1581 return reguard_stack(os::current_stack_pointer());
1582 }
1583
1584
1585 void JavaThread::block_if_vm_exited() {
1586 if (_terminated == _vm_exited) {
1587 // _vm_exited is set at safepoint, and Threads_lock is never released
1588 // we will block here forever
1589 Threads_lock->lock_without_safepoint_check();
1590 ShouldNotReachHere();
1591 }
1592 }
1593
1594
1595 // Remove this ifdef when C1 is ported to the compiler interface.
1596 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1597 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1598
1599 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1600 Thread()
1601 #if INCLUDE_ALL_GCS
1602 , _satb_mark_queue(&_satb_mark_queue_set),
1603 _dirty_card_queue(&_dirty_card_queue_set)
1604 #endif // INCLUDE_ALL_GCS
1605 {
1606 initialize();
1607 _jni_attach_state = _not_attaching_via_jni;
1608 set_entry_point(entry_point);
1609 // Create the native thread itself.
1610 // %note runtime_23
1611 os::ThreadType thr_type = os::java_thread;
1612 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1613 os::java_thread;
1614 os::create_thread(this, thr_type, stack_sz);
1615 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1616 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1617 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1618 // the exception consists of creating the exception object & initializing it, initialization
1619 // will leave the VM via a JavaCall and then all locks must be unlocked).
1620 //
1621 // The thread is still suspended when we reach here. Thread must be explicit started
1622 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1623 // by calling Threads:add. The reason why this is not done here, is because the thread
1624 // object must be fully initialized (take a look at JVM_Start)
1625 }
1626
1627 JavaThread::~JavaThread() {
1628
1629 // JSR166 -- return the parker to the free list
1630 Parker::Release(_parker);
1631 _parker = NULL;
1632
1633 // Free any remaining previous UnrollBlock
1634 vframeArray* old_array = vframe_array_last();
1635
1636 if (old_array != NULL) {
1637 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1638 old_array->set_unroll_block(NULL);
1639 delete old_info;
1640 delete old_array;
1641 }
1642
1643 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1644 if (deferred != NULL) {
1645 // This can only happen if thread is destroyed before deoptimization occurs.
1646 assert(deferred->length() != 0, "empty array!");
1647 do {
1648 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1649 deferred->remove_at(0);
1650 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1651 delete dlv;
1652 } while (deferred->length() != 0);
1653 delete deferred;
1654 }
1655
1656 // All Java related clean up happens in exit
1657 ThreadSafepointState::destroy(this);
1658 if (_thread_stat != NULL) delete _thread_stat;
1659
1660 if (_vt_alloc_ptr != NULL) {
1661 VTBufferChunk* chunk = VTBufferChunk::chunk(_vt_alloc_ptr);
1662 while (chunk != NULL) {
1663 VTBufferChunk* temp = chunk->prev();
1664 VTBuffer::recycle_chunk(this, chunk);
1665 chunk = temp;
1666 }
1667 _vt_alloc_ptr = NULL;
1668 _vt_alloc_limit = NULL;
1669 }
1670
1671 #if INCLUDE_JVMCI
1672 if (JVMCICounterSize > 0) {
1673 if (jvmci_counters_include(this)) {
1674 for (int i = 0; i < JVMCICounterSize; i++) {
1675 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1676 }
1677 }
1678 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1679 }
1680 #endif // INCLUDE_JVMCI
1681 }
1682
1683
1684 // The first routine called by a new Java thread
1685 void JavaThread::run() {
1686 // initialize thread-local alloc buffer related fields
1687 this->initialize_tlab();
1688
1689 // used to test validity of stack trace backs
1690 this->record_base_of_stack_pointer();
1691
1692 // Record real stack base and size.
1693 this->record_stack_base_and_size();
1694
1695 this->create_stack_guard_pages();
1696
1697 this->cache_global_variables();
1698
1699 // Thread is now sufficient initialized to be handled by the safepoint code as being
1700 // in the VM. Change thread state from _thread_new to _thread_in_vm
1701 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1702
1703 assert(JavaThread::current() == this, "sanity check");
1704 assert(!Thread::current()->owns_locks(), "sanity check");
1705
1706 DTRACE_THREAD_PROBE(start, this);
1707
1708 // This operation might block. We call that after all safepoint checks for a new thread has
1709 // been completed.
1710 this->set_active_handles(JNIHandleBlock::allocate_block());
1711
1712 if (JvmtiExport::should_post_thread_life()) {
1713 JvmtiExport::post_thread_start(this);
1714 }
1715
1716 EventThreadStart event;
1717 if (event.should_commit()) {
1718 event.set_thread(THREAD_TRACE_ID(this));
1719 event.commit();
1720 }
1721
1722 // We call another function to do the rest so we are sure that the stack addresses used
1723 // from there will be lower than the stack base just computed
1724 thread_main_inner();
1725
1726 // Note, thread is no longer valid at this point!
1727 }
1728
1729
1730 void JavaThread::thread_main_inner() {
1731 assert(JavaThread::current() == this, "sanity check");
1732 assert(this->threadObj() != NULL, "just checking");
1733
1734 // Execute thread entry point unless this thread has a pending exception
1735 // or has been stopped before starting.
1736 // Note: Due to JVM_StopThread we can have pending exceptions already!
1737 if (!this->has_pending_exception() &&
1738 !java_lang_Thread::is_stillborn(this->threadObj())) {
1739 {
1740 ResourceMark rm(this);
1741 this->set_native_thread_name(this->get_thread_name());
1742 }
1743 HandleMark hm(this);
1744 this->entry_point()(this, this);
1745 }
1746
1747 DTRACE_THREAD_PROBE(stop, this);
1748
1749 this->exit(false);
1750 delete this;
1751 }
1752
1753
1754 static void ensure_join(JavaThread* thread) {
1755 // We do not need to grap the Threads_lock, since we are operating on ourself.
1756 Handle threadObj(thread, thread->threadObj());
1757 assert(threadObj.not_null(), "java thread object must exist");
1758 ObjectLocker lock(threadObj, thread);
1759 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1760 thread->clear_pending_exception();
1761 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1762 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1763 // Clear the native thread instance - this makes isAlive return false and allows the join()
1764 // to complete once we've done the notify_all below
1765 java_lang_Thread::set_thread(threadObj(), NULL);
1766 lock.notify_all(thread);
1767 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1768 thread->clear_pending_exception();
1769 }
1770
1771
1772 // For any new cleanup additions, please check to see if they need to be applied to
1773 // cleanup_failed_attach_current_thread as well.
1774 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1775 assert(this == JavaThread::current(), "thread consistency check");
1776
1777 HandleMark hm(this);
1778 Handle uncaught_exception(this, this->pending_exception());
1779 this->clear_pending_exception();
1780 Handle threadObj(this, this->threadObj());
1781 assert(threadObj.not_null(), "Java thread object should be created");
1782
1783 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1784 {
1785 EXCEPTION_MARK;
1786
1787 CLEAR_PENDING_EXCEPTION;
1788 }
1789 if (!destroy_vm) {
1790 if (uncaught_exception.not_null()) {
1791 EXCEPTION_MARK;
1792 // Call method Thread.dispatchUncaughtException().
1793 Klass* thread_klass = SystemDictionary::Thread_klass();
1794 JavaValue result(T_VOID);
1795 JavaCalls::call_virtual(&result,
1796 threadObj, thread_klass,
1797 vmSymbols::dispatchUncaughtException_name(),
1798 vmSymbols::throwable_void_signature(),
1799 uncaught_exception,
1800 THREAD);
1801 if (HAS_PENDING_EXCEPTION) {
1802 ResourceMark rm(this);
1803 jio_fprintf(defaultStream::error_stream(),
1804 "\nException: %s thrown from the UncaughtExceptionHandler"
1805 " in thread \"%s\"\n",
1806 pending_exception()->klass()->external_name(),
1807 get_thread_name());
1808 CLEAR_PENDING_EXCEPTION;
1809 }
1810 }
1811
1812 // Called before the java thread exit since we want to read info
1813 // from java_lang_Thread object
1814 EventThreadEnd event;
1815 if (event.should_commit()) {
1816 event.set_thread(THREAD_TRACE_ID(this));
1817 event.commit();
1818 }
1819
1820 // Call after last event on thread
1821 EVENT_THREAD_EXIT(this);
1822
1823 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1824 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1825 // is deprecated anyhow.
1826 if (!is_Compiler_thread()) {
1827 int count = 3;
1828 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1829 EXCEPTION_MARK;
1830 JavaValue result(T_VOID);
1831 Klass* thread_klass = SystemDictionary::Thread_klass();
1832 JavaCalls::call_virtual(&result,
1833 threadObj, thread_klass,
1834 vmSymbols::exit_method_name(),
1835 vmSymbols::void_method_signature(),
1836 THREAD);
1837 CLEAR_PENDING_EXCEPTION;
1838 }
1839 }
1840 // notify JVMTI
1841 if (JvmtiExport::should_post_thread_life()) {
1842 JvmtiExport::post_thread_end(this);
1843 }
1844
1845 // We have notified the agents that we are exiting, before we go on,
1846 // we must check for a pending external suspend request and honor it
1847 // in order to not surprise the thread that made the suspend request.
1848 while (true) {
1849 {
1850 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1851 if (!is_external_suspend()) {
1852 set_terminated(_thread_exiting);
1853 ThreadService::current_thread_exiting(this);
1854 break;
1855 }
1856 // Implied else:
1857 // Things get a little tricky here. We have a pending external
1858 // suspend request, but we are holding the SR_lock so we
1859 // can't just self-suspend. So we temporarily drop the lock
1860 // and then self-suspend.
1861 }
1862
1863 ThreadBlockInVM tbivm(this);
1864 java_suspend_self();
1865
1866 // We're done with this suspend request, but we have to loop around
1867 // and check again. Eventually we will get SR_lock without a pending
1868 // external suspend request and will be able to mark ourselves as
1869 // exiting.
1870 }
1871 // no more external suspends are allowed at this point
1872 } else {
1873 // before_exit() has already posted JVMTI THREAD_END events
1874 }
1875
1876 // Notify waiters on thread object. This has to be done after exit() is called
1877 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1878 // group should have the destroyed bit set before waiters are notified).
1879 ensure_join(this);
1880 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1881
1882 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1883 // held by this thread must be released. The spec does not distinguish
1884 // between JNI-acquired and regular Java monitors. We can only see
1885 // regular Java monitors here if monitor enter-exit matching is broken.
1886 //
1887 // Optionally release any monitors for regular JavaThread exits. This
1888 // is provided as a work around for any bugs in monitor enter-exit
1889 // matching. This can be expensive so it is not enabled by default.
1890 //
1891 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1892 // ObjectSynchronizer::release_monitors_owned_by_thread().
1893 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1894 // Sanity check even though JNI DetachCurrentThread() would have
1895 // returned JNI_ERR if there was a Java frame. JavaThread exit
1896 // should be done executing Java code by the time we get here.
1897 assert(!this->has_last_Java_frame(),
1898 "should not have a Java frame when detaching or exiting");
1899 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1900 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1901 }
1902
1903 // These things needs to be done while we are still a Java Thread. Make sure that thread
1904 // is in a consistent state, in case GC happens
1905 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1906
1907 if (active_handles() != NULL) {
1908 JNIHandleBlock* block = active_handles();
1909 set_active_handles(NULL);
1910 JNIHandleBlock::release_block(block);
1911 }
1912
1913 if (free_handle_block() != NULL) {
1914 JNIHandleBlock* block = free_handle_block();
1915 set_free_handle_block(NULL);
1916 JNIHandleBlock::release_block(block);
1917 }
1918
1919 // These have to be removed while this is still a valid thread.
1920 remove_stack_guard_pages();
1921
1922 if (UseTLAB) {
1923 tlab().make_parsable(true); // retire TLAB
1924 }
1925
1926 if (JvmtiEnv::environments_might_exist()) {
1927 JvmtiExport::cleanup_thread(this);
1928 }
1929
1930 // We must flush any deferred card marks before removing a thread from
1931 // the list of active threads.
1932 Universe::heap()->flush_deferred_store_barrier(this);
1933 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1934
1935 #if INCLUDE_ALL_GCS
1936 // We must flush the G1-related buffers before removing a thread
1937 // from the list of active threads. We must do this after any deferred
1938 // card marks have been flushed (above) so that any entries that are
1939 // added to the thread's dirty card queue as a result are not lost.
1940 if (UseG1GC) {
1941 flush_barrier_queues();
1942 }
1943 #endif // INCLUDE_ALL_GCS
1944
1945 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1946 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1947 os::current_thread_id());
1948
1949 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1950 Threads::remove(this);
1951 }
1952
1953 #if INCLUDE_ALL_GCS
1954 // Flush G1-related queues.
1955 void JavaThread::flush_barrier_queues() {
1956 satb_mark_queue().flush();
1957 dirty_card_queue().flush();
1958 }
1959
1960 void JavaThread::initialize_queues() {
1961 assert(!SafepointSynchronize::is_at_safepoint(),
1962 "we should not be at a safepoint");
1963
1964 SATBMarkQueue& satb_queue = satb_mark_queue();
1965 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1966 // The SATB queue should have been constructed with its active
1967 // field set to false.
1968 assert(!satb_queue.is_active(), "SATB queue should not be active");
1969 assert(satb_queue.is_empty(), "SATB queue should be empty");
1970 // If we are creating the thread during a marking cycle, we should
1971 // set the active field of the SATB queue to true.
1972 if (satb_queue_set.is_active()) {
1973 satb_queue.set_active(true);
1974 }
1975
1976 DirtyCardQueue& dirty_queue = dirty_card_queue();
1977 // The dirty card queue should have been constructed with its
1978 // active field set to true.
1979 assert(dirty_queue.is_active(), "dirty card queue should be active");
1980 }
1981 #endif // INCLUDE_ALL_GCS
1982
1983 void JavaThread::cleanup_failed_attach_current_thread() {
1984 if (active_handles() != NULL) {
1985 JNIHandleBlock* block = active_handles();
1986 set_active_handles(NULL);
1987 JNIHandleBlock::release_block(block);
1988 }
1989
1990 if (free_handle_block() != NULL) {
1991 JNIHandleBlock* block = free_handle_block();
1992 set_free_handle_block(NULL);
1993 JNIHandleBlock::release_block(block);
1994 }
1995
1996 // These have to be removed while this is still a valid thread.
1997 remove_stack_guard_pages();
1998
1999 if (UseTLAB) {
2000 tlab().make_parsable(true); // retire TLAB, if any
2001 }
2002
2003 #if INCLUDE_ALL_GCS
2004 if (UseG1GC) {
2005 flush_barrier_queues();
2006 }
2007 #endif // INCLUDE_ALL_GCS
2008
2009 Threads::remove(this);
2010 delete this;
2011 }
2012
2013
2014
2015
2016 JavaThread* JavaThread::active() {
2017 Thread* thread = Thread::current();
2018 if (thread->is_Java_thread()) {
2019 return (JavaThread*) thread;
2020 } else {
2021 assert(thread->is_VM_thread(), "this must be a vm thread");
2022 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2023 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2024 assert(ret->is_Java_thread(), "must be a Java thread");
2025 return ret;
2026 }
2027 }
2028
2029 bool JavaThread::is_lock_owned(address adr) const {
2030 if (Thread::is_lock_owned(adr)) return true;
2031
2032 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2033 if (chunk->contains(adr)) return true;
2034 }
2035
2036 return false;
2037 }
2038
2039
2040 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2041 chunk->set_next(monitor_chunks());
2042 set_monitor_chunks(chunk);
2043 }
2044
2045 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2046 guarantee(monitor_chunks() != NULL, "must be non empty");
2047 if (monitor_chunks() == chunk) {
2048 set_monitor_chunks(chunk->next());
2049 } else {
2050 MonitorChunk* prev = monitor_chunks();
2051 while (prev->next() != chunk) prev = prev->next();
2052 prev->set_next(chunk->next());
2053 }
2054 }
2055
2056 // JVM support.
2057
2058 // Note: this function shouldn't block if it's called in
2059 // _thread_in_native_trans state (such as from
2060 // check_special_condition_for_native_trans()).
2061 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2062
2063 if (has_last_Java_frame() && has_async_condition()) {
2064 // If we are at a polling page safepoint (not a poll return)
2065 // then we must defer async exception because live registers
2066 // will be clobbered by the exception path. Poll return is
2067 // ok because the call we a returning from already collides
2068 // with exception handling registers and so there is no issue.
2069 // (The exception handling path kills call result registers but
2070 // this is ok since the exception kills the result anyway).
2071
2072 if (is_at_poll_safepoint()) {
2073 // if the code we are returning to has deoptimized we must defer
2074 // the exception otherwise live registers get clobbered on the
2075 // exception path before deoptimization is able to retrieve them.
2076 //
2077 RegisterMap map(this, false);
2078 frame caller_fr = last_frame().sender(&map);
2079 assert(caller_fr.is_compiled_frame(), "what?");
2080 if (caller_fr.is_deoptimized_frame()) {
2081 log_info(exceptions)("deferred async exception at compiled safepoint");
2082 return;
2083 }
2084 }
2085 }
2086
2087 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2088 if (condition == _no_async_condition) {
2089 // Conditions have changed since has_special_runtime_exit_condition()
2090 // was called:
2091 // - if we were here only because of an external suspend request,
2092 // then that was taken care of above (or cancelled) so we are done
2093 // - if we were here because of another async request, then it has
2094 // been cleared between the has_special_runtime_exit_condition()
2095 // and now so again we are done
2096 return;
2097 }
2098
2099 // Check for pending async. exception
2100 if (_pending_async_exception != NULL) {
2101 // Only overwrite an already pending exception, if it is not a threadDeath.
2102 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2103
2104 // We cannot call Exceptions::_throw(...) here because we cannot block
2105 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2106
2107 LogTarget(Info, exceptions) lt;
2108 if (lt.is_enabled()) {
2109 ResourceMark rm;
2110 LogStream ls(lt);
2111 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2112 if (has_last_Java_frame()) {
2113 frame f = last_frame();
2114 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2115 }
2116 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2117 }
2118 _pending_async_exception = NULL;
2119 clear_has_async_exception();
2120 }
2121 }
2122
2123 if (check_unsafe_error &&
2124 condition == _async_unsafe_access_error && !has_pending_exception()) {
2125 condition = _no_async_condition; // done
2126 switch (thread_state()) {
2127 case _thread_in_vm: {
2128 JavaThread* THREAD = this;
2129 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2130 }
2131 case _thread_in_native: {
2132 ThreadInVMfromNative tiv(this);
2133 JavaThread* THREAD = this;
2134 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2135 }
2136 case _thread_in_Java: {
2137 ThreadInVMfromJava tiv(this);
2138 JavaThread* THREAD = this;
2139 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2140 }
2141 default:
2142 ShouldNotReachHere();
2143 }
2144 }
2145
2146 assert(condition == _no_async_condition || has_pending_exception() ||
2147 (!check_unsafe_error && condition == _async_unsafe_access_error),
2148 "must have handled the async condition, if no exception");
2149 }
2150
2151 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2152 //
2153 // Check for pending external suspend. Internal suspend requests do
2154 // not use handle_special_runtime_exit_condition().
2155 // If JNIEnv proxies are allowed, don't self-suspend if the target
2156 // thread is not the current thread. In older versions of jdbx, jdbx
2157 // threads could call into the VM with another thread's JNIEnv so we
2158 // can be here operating on behalf of a suspended thread (4432884).
2159 bool do_self_suspend = is_external_suspend_with_lock();
2160 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2161 //
2162 // Because thread is external suspended the safepoint code will count
2163 // thread as at a safepoint. This can be odd because we can be here
2164 // as _thread_in_Java which would normally transition to _thread_blocked
2165 // at a safepoint. We would like to mark the thread as _thread_blocked
2166 // before calling java_suspend_self like all other callers of it but
2167 // we must then observe proper safepoint protocol. (We can't leave
2168 // _thread_blocked with a safepoint in progress). However we can be
2169 // here as _thread_in_native_trans so we can't use a normal transition
2170 // constructor/destructor pair because they assert on that type of
2171 // transition. We could do something like:
2172 //
2173 // JavaThreadState state = thread_state();
2174 // set_thread_state(_thread_in_vm);
2175 // {
2176 // ThreadBlockInVM tbivm(this);
2177 // java_suspend_self()
2178 // }
2179 // set_thread_state(_thread_in_vm_trans);
2180 // if (safepoint) block;
2181 // set_thread_state(state);
2182 //
2183 // but that is pretty messy. Instead we just go with the way the
2184 // code has worked before and note that this is the only path to
2185 // java_suspend_self that doesn't put the thread in _thread_blocked
2186 // mode.
2187
2188 frame_anchor()->make_walkable(this);
2189 java_suspend_self();
2190
2191 // We might be here for reasons in addition to the self-suspend request
2192 // so check for other async requests.
2193 }
2194
2195 if (check_asyncs) {
2196 check_and_handle_async_exceptions();
2197 }
2198 #if INCLUDE_TRACE
2199 if (is_trace_suspend()) {
2200 TRACE_SUSPEND_THREAD(this);
2201 }
2202 #endif
2203 }
2204
2205 void JavaThread::send_thread_stop(oop java_throwable) {
2206 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2207 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2208 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2209
2210 // Do not throw asynchronous exceptions against the compiler thread
2211 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2212 if (!can_call_java()) return;
2213
2214 {
2215 // Actually throw the Throwable against the target Thread - however
2216 // only if there is no thread death exception installed already.
2217 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2218 // If the topmost frame is a runtime stub, then we are calling into
2219 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2220 // must deoptimize the caller before continuing, as the compiled exception handler table
2221 // may not be valid
2222 if (has_last_Java_frame()) {
2223 frame f = last_frame();
2224 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2225 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2226 RegisterMap reg_map(this, UseBiasedLocking);
2227 frame compiled_frame = f.sender(®_map);
2228 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2229 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2230 }
2231 }
2232 }
2233
2234 // Set async. pending exception in thread.
2235 set_pending_async_exception(java_throwable);
2236
2237 if (log_is_enabled(Info, exceptions)) {
2238 ResourceMark rm;
2239 log_info(exceptions)("Pending Async. exception installed of type: %s",
2240 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2241 }
2242 // for AbortVMOnException flag
2243 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2244 }
2245 }
2246
2247
2248 // Interrupt thread so it will wake up from a potential wait()
2249 Thread::interrupt(this);
2250 }
2251
2252 // External suspension mechanism.
2253 //
2254 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2255 // to any VM_locks and it is at a transition
2256 // Self-suspension will happen on the transition out of the vm.
2257 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2258 //
2259 // Guarantees on return:
2260 // + Target thread will not execute any new bytecode (that's why we need to
2261 // force a safepoint)
2262 // + Target thread will not enter any new monitors
2263 //
2264 void JavaThread::java_suspend() {
2265 { MutexLocker mu(Threads_lock);
2266 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2267 return;
2268 }
2269 }
2270
2271 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2272 if (!is_external_suspend()) {
2273 // a racing resume has cancelled us; bail out now
2274 return;
2275 }
2276
2277 // suspend is done
2278 uint32_t debug_bits = 0;
2279 // Warning: is_ext_suspend_completed() may temporarily drop the
2280 // SR_lock to allow the thread to reach a stable thread state if
2281 // it is currently in a transient thread state.
2282 if (is_ext_suspend_completed(false /* !called_by_wait */,
2283 SuspendRetryDelay, &debug_bits)) {
2284 return;
2285 }
2286 }
2287
2288 VM_ThreadSuspend vm_suspend;
2289 VMThread::execute(&vm_suspend);
2290 }
2291
2292 // Part II of external suspension.
2293 // A JavaThread self suspends when it detects a pending external suspend
2294 // request. This is usually on transitions. It is also done in places
2295 // where continuing to the next transition would surprise the caller,
2296 // e.g., monitor entry.
2297 //
2298 // Returns the number of times that the thread self-suspended.
2299 //
2300 // Note: DO NOT call java_suspend_self() when you just want to block current
2301 // thread. java_suspend_self() is the second stage of cooperative
2302 // suspension for external suspend requests and should only be used
2303 // to complete an external suspend request.
2304 //
2305 int JavaThread::java_suspend_self() {
2306 int ret = 0;
2307
2308 // we are in the process of exiting so don't suspend
2309 if (is_exiting()) {
2310 clear_external_suspend();
2311 return ret;
2312 }
2313
2314 assert(_anchor.walkable() ||
2315 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2316 "must have walkable stack");
2317
2318 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2319
2320 assert(!this->is_ext_suspended(),
2321 "a thread trying to self-suspend should not already be suspended");
2322
2323 if (this->is_suspend_equivalent()) {
2324 // If we are self-suspending as a result of the lifting of a
2325 // suspend equivalent condition, then the suspend_equivalent
2326 // flag is not cleared until we set the ext_suspended flag so
2327 // that wait_for_ext_suspend_completion() returns consistent
2328 // results.
2329 this->clear_suspend_equivalent();
2330 }
2331
2332 // A racing resume may have cancelled us before we grabbed SR_lock
2333 // above. Or another external suspend request could be waiting for us
2334 // by the time we return from SR_lock()->wait(). The thread
2335 // that requested the suspension may already be trying to walk our
2336 // stack and if we return now, we can change the stack out from under
2337 // it. This would be a "bad thing (TM)" and cause the stack walker
2338 // to crash. We stay self-suspended until there are no more pending
2339 // external suspend requests.
2340 while (is_external_suspend()) {
2341 ret++;
2342 this->set_ext_suspended();
2343
2344 // _ext_suspended flag is cleared by java_resume()
2345 while (is_ext_suspended()) {
2346 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2347 }
2348 }
2349
2350 return ret;
2351 }
2352
2353 #ifdef ASSERT
2354 // verify the JavaThread has not yet been published in the Threads::list, and
2355 // hence doesn't need protection from concurrent access at this stage
2356 void JavaThread::verify_not_published() {
2357 if (!Threads_lock->owned_by_self()) {
2358 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2359 assert(!Threads::includes(this),
2360 "java thread shouldn't have been published yet!");
2361 } else {
2362 assert(!Threads::includes(this),
2363 "java thread shouldn't have been published yet!");
2364 }
2365 }
2366 #endif
2367
2368 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2369 // progress or when _suspend_flags is non-zero.
2370 // Current thread needs to self-suspend if there is a suspend request and/or
2371 // block if a safepoint is in progress.
2372 // Async exception ISN'T checked.
2373 // Note only the ThreadInVMfromNative transition can call this function
2374 // directly and when thread state is _thread_in_native_trans
2375 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2376 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2377
2378 JavaThread *curJT = JavaThread::current();
2379 bool do_self_suspend = thread->is_external_suspend();
2380
2381 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2382
2383 // If JNIEnv proxies are allowed, don't self-suspend if the target
2384 // thread is not the current thread. In older versions of jdbx, jdbx
2385 // threads could call into the VM with another thread's JNIEnv so we
2386 // can be here operating on behalf of a suspended thread (4432884).
2387 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2388 JavaThreadState state = thread->thread_state();
2389
2390 // We mark this thread_blocked state as a suspend-equivalent so
2391 // that a caller to is_ext_suspend_completed() won't be confused.
2392 // The suspend-equivalent state is cleared by java_suspend_self().
2393 thread->set_suspend_equivalent();
2394
2395 // If the safepoint code sees the _thread_in_native_trans state, it will
2396 // wait until the thread changes to other thread state. There is no
2397 // guarantee on how soon we can obtain the SR_lock and complete the
2398 // self-suspend request. It would be a bad idea to let safepoint wait for
2399 // too long. Temporarily change the state to _thread_blocked to
2400 // let the VM thread know that this thread is ready for GC. The problem
2401 // of changing thread state is that safepoint could happen just after
2402 // java_suspend_self() returns after being resumed, and VM thread will
2403 // see the _thread_blocked state. We must check for safepoint
2404 // after restoring the state and make sure we won't leave while a safepoint
2405 // is in progress.
2406 thread->set_thread_state(_thread_blocked);
2407 thread->java_suspend_self();
2408 thread->set_thread_state(state);
2409
2410 InterfaceSupport::serialize_thread_state_with_handler(thread);
2411 }
2412
2413 if (SafepointSynchronize::do_call_back()) {
2414 // If we are safepointing, then block the caller which may not be
2415 // the same as the target thread (see above).
2416 SafepointSynchronize::block(curJT);
2417 }
2418
2419 if (thread->is_deopt_suspend()) {
2420 thread->clear_deopt_suspend();
2421 RegisterMap map(thread, false);
2422 frame f = thread->last_frame();
2423 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2424 f = f.sender(&map);
2425 }
2426 if (f.id() == thread->must_deopt_id()) {
2427 thread->clear_must_deopt_id();
2428 f.deoptimize(thread);
2429 } else {
2430 fatal("missed deoptimization!");
2431 }
2432 }
2433 #if INCLUDE_TRACE
2434 if (thread->is_trace_suspend()) {
2435 TRACE_SUSPEND_THREAD(thread);
2436 }
2437 #endif
2438 }
2439
2440 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2441 // progress or when _suspend_flags is non-zero.
2442 // Current thread needs to self-suspend if there is a suspend request and/or
2443 // block if a safepoint is in progress.
2444 // Also check for pending async exception (not including unsafe access error).
2445 // Note only the native==>VM/Java barriers can call this function and when
2446 // thread state is _thread_in_native_trans.
2447 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2448 check_safepoint_and_suspend_for_native_trans(thread);
2449
2450 if (thread->has_async_exception()) {
2451 // We are in _thread_in_native_trans state, don't handle unsafe
2452 // access error since that may block.
2453 thread->check_and_handle_async_exceptions(false);
2454 }
2455 }
2456
2457 // This is a variant of the normal
2458 // check_special_condition_for_native_trans with slightly different
2459 // semantics for use by critical native wrappers. It does all the
2460 // normal checks but also performs the transition back into
2461 // thread_in_Java state. This is required so that critical natives
2462 // can potentially block and perform a GC if they are the last thread
2463 // exiting the GCLocker.
2464 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2465 check_special_condition_for_native_trans(thread);
2466
2467 // Finish the transition
2468 thread->set_thread_state(_thread_in_Java);
2469
2470 if (thread->do_critical_native_unlock()) {
2471 ThreadInVMfromJavaNoAsyncException tiv(thread);
2472 GCLocker::unlock_critical(thread);
2473 thread->clear_critical_native_unlock();
2474 }
2475 }
2476
2477 // We need to guarantee the Threads_lock here, since resumes are not
2478 // allowed during safepoint synchronization
2479 // Can only resume from an external suspension
2480 void JavaThread::java_resume() {
2481 assert_locked_or_safepoint(Threads_lock);
2482
2483 // Sanity check: thread is gone, has started exiting or the thread
2484 // was not externally suspended.
2485 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2486 return;
2487 }
2488
2489 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2490
2491 clear_external_suspend();
2492
2493 if (is_ext_suspended()) {
2494 clear_ext_suspended();
2495 SR_lock()->notify_all();
2496 }
2497 }
2498
2499 size_t JavaThread::_stack_red_zone_size = 0;
2500 size_t JavaThread::_stack_yellow_zone_size = 0;
2501 size_t JavaThread::_stack_reserved_zone_size = 0;
2502 size_t JavaThread::_stack_shadow_zone_size = 0;
2503
2504 void JavaThread::create_stack_guard_pages() {
2505 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2506 address low_addr = stack_end();
2507 size_t len = stack_guard_zone_size();
2508
2509 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2510 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2511
2512 int must_commit = os::must_commit_stack_guard_pages();
2513 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2514
2515 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2516 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2517 return;
2518 }
2519
2520 if (os::guard_memory((char *) low_addr, len)) {
2521 _stack_guard_state = stack_guard_enabled;
2522 } else {
2523 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2524 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2525 if (os::uncommit_memory((char *) low_addr, len)) {
2526 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2527 }
2528 return;
2529 }
2530
2531 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2532 PTR_FORMAT "-" PTR_FORMAT ".",
2533 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2534 }
2535
2536 void JavaThread::remove_stack_guard_pages() {
2537 assert(Thread::current() == this, "from different thread");
2538 if (_stack_guard_state == stack_guard_unused) return;
2539 address low_addr = stack_end();
2540 size_t len = stack_guard_zone_size();
2541
2542 if (os::must_commit_stack_guard_pages()) {
2543 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2544 _stack_guard_state = stack_guard_unused;
2545 } else {
2546 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2547 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2548 return;
2549 }
2550 } else {
2551 if (_stack_guard_state == stack_guard_unused) return;
2552 if (os::unguard_memory((char *) low_addr, len)) {
2553 _stack_guard_state = stack_guard_unused;
2554 } else {
2555 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2556 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2557 return;
2558 }
2559 }
2560
2561 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2562 PTR_FORMAT "-" PTR_FORMAT ".",
2563 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2564 }
2565
2566 void JavaThread::enable_stack_reserved_zone() {
2567 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2568 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2569
2570 // The base notation is from the stack's point of view, growing downward.
2571 // We need to adjust it to work correctly with guard_memory()
2572 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2573
2574 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2575 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2576
2577 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2578 _stack_guard_state = stack_guard_enabled;
2579 } else {
2580 warning("Attempt to guard stack reserved zone failed.");
2581 }
2582 enable_register_stack_guard();
2583 }
2584
2585 void JavaThread::disable_stack_reserved_zone() {
2586 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2587 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2588
2589 // Simply return if called for a thread that does not use guard pages.
2590 if (_stack_guard_state == stack_guard_unused) return;
2591
2592 // The base notation is from the stack's point of view, growing downward.
2593 // We need to adjust it to work correctly with guard_memory()
2594 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2595
2596 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2597 _stack_guard_state = stack_guard_reserved_disabled;
2598 } else {
2599 warning("Attempt to unguard stack reserved zone failed.");
2600 }
2601 disable_register_stack_guard();
2602 }
2603
2604 void JavaThread::enable_stack_yellow_reserved_zone() {
2605 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2606 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2607
2608 // The base notation is from the stacks point of view, growing downward.
2609 // We need to adjust it to work correctly with guard_memory()
2610 address base = stack_red_zone_base();
2611
2612 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2613 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2614
2615 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2616 _stack_guard_state = stack_guard_enabled;
2617 } else {
2618 warning("Attempt to guard stack yellow zone failed.");
2619 }
2620 enable_register_stack_guard();
2621 }
2622
2623 void JavaThread::disable_stack_yellow_reserved_zone() {
2624 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2625 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2626
2627 // Simply return if called for a thread that does not use guard pages.
2628 if (_stack_guard_state == stack_guard_unused) return;
2629
2630 // The base notation is from the stacks point of view, growing downward.
2631 // We need to adjust it to work correctly with guard_memory()
2632 address base = stack_red_zone_base();
2633
2634 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2635 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2636 } else {
2637 warning("Attempt to unguard stack yellow zone failed.");
2638 }
2639 disable_register_stack_guard();
2640 }
2641
2642 void JavaThread::enable_stack_red_zone() {
2643 // The base notation is from the stacks point of view, growing downward.
2644 // We need to adjust it to work correctly with guard_memory()
2645 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2646 address base = stack_red_zone_base() - stack_red_zone_size();
2647
2648 guarantee(base < stack_base(), "Error calculating stack red zone");
2649 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2650
2651 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2652 warning("Attempt to guard stack red zone failed.");
2653 }
2654 }
2655
2656 void JavaThread::disable_stack_red_zone() {
2657 // The base notation is from the stacks point of view, growing downward.
2658 // We need to adjust it to work correctly with guard_memory()
2659 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2660 address base = stack_red_zone_base() - stack_red_zone_size();
2661 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2662 warning("Attempt to unguard stack red zone failed.");
2663 }
2664 }
2665
2666 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2667 // ignore is there is no stack
2668 if (!has_last_Java_frame()) return;
2669 // Because this method is used to verify oops, it must support
2670 // oops in buffered values
2671 BufferedValuesDealiaser dealiaser(this);
2672
2673 // traverse the stack frames. Starts from top frame.
2674 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2675 frame* fr = fst.current();
2676 f(fr, fst.register_map());
2677 }
2678 }
2679
2680
2681 #ifndef PRODUCT
2682 // Deoptimization
2683 // Function for testing deoptimization
2684 void JavaThread::deoptimize() {
2685 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2686 StackFrameStream fst(this, UseBiasedLocking);
2687 bool deopt = false; // Dump stack only if a deopt actually happens.
2688 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2689 // Iterate over all frames in the thread and deoptimize
2690 for (; !fst.is_done(); fst.next()) {
2691 if (fst.current()->can_be_deoptimized()) {
2692
2693 if (only_at) {
2694 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2695 // consists of comma or carriage return separated numbers so
2696 // search for the current bci in that string.
2697 address pc = fst.current()->pc();
2698 nmethod* nm = (nmethod*) fst.current()->cb();
2699 ScopeDesc* sd = nm->scope_desc_at(pc);
2700 char buffer[8];
2701 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2702 size_t len = strlen(buffer);
2703 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2704 while (found != NULL) {
2705 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2706 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2707 // Check that the bci found is bracketed by terminators.
2708 break;
2709 }
2710 found = strstr(found + 1, buffer);
2711 }
2712 if (!found) {
2713 continue;
2714 }
2715 }
2716
2717 if (DebugDeoptimization && !deopt) {
2718 deopt = true; // One-time only print before deopt
2719 tty->print_cr("[BEFORE Deoptimization]");
2720 trace_frames();
2721 trace_stack();
2722 }
2723 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2724 }
2725 }
2726
2727 if (DebugDeoptimization && deopt) {
2728 tty->print_cr("[AFTER Deoptimization]");
2729 trace_frames();
2730 }
2731 }
2732
2733
2734 // Make zombies
2735 void JavaThread::make_zombies() {
2736 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2737 if (fst.current()->can_be_deoptimized()) {
2738 // it is a Java nmethod
2739 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2740 nm->make_not_entrant();
2741 }
2742 }
2743 }
2744 #endif // PRODUCT
2745
2746
2747 void JavaThread::deoptimized_wrt_marked_nmethods() {
2748 if (!has_last_Java_frame()) return;
2749 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2750 StackFrameStream fst(this, UseBiasedLocking);
2751 for (; !fst.is_done(); fst.next()) {
2752 if (fst.current()->should_be_deoptimized()) {
2753 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2754 }
2755 }
2756 }
2757
2758
2759 // If the caller is a NamedThread, then remember, in the current scope,
2760 // the given JavaThread in its _processed_thread field.
2761 class RememberProcessedThread: public StackObj {
2762 NamedThread* _cur_thr;
2763 public:
2764 RememberProcessedThread(JavaThread* jthr) {
2765 Thread* thread = Thread::current();
2766 if (thread->is_Named_thread()) {
2767 _cur_thr = (NamedThread *)thread;
2768 _cur_thr->set_processed_thread(jthr);
2769 } else {
2770 _cur_thr = NULL;
2771 }
2772 }
2773
2774 ~RememberProcessedThread() {
2775 if (_cur_thr) {
2776 _cur_thr->set_processed_thread(NULL);
2777 }
2778 }
2779 };
2780
2781 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2782 // Verify that the deferred card marks have been flushed.
2783 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2784
2785 BufferedValuesDealiaser dealiaser(this);
2786
2787 // Traverse the GCHandles
2788 Thread::oops_do(f, cf);
2789
2790 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2791
2792 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2793 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2794
2795 if (has_last_Java_frame()) {
2796 // Record JavaThread to GC thread
2797 RememberProcessedThread rpt(this);
2798
2799 // Traverse the privileged stack
2800 if (_privileged_stack_top != NULL) {
2801 _privileged_stack_top->oops_do(f);
2802 }
2803
2804 // traverse the registered growable array
2805 if (_array_for_gc != NULL) {
2806 for (int index = 0; index < _array_for_gc->length(); index++) {
2807 if (!VTBuffer::is_in_vt_buffer(_array_for_gc->at(index))) {
2808 f->do_oop(_array_for_gc->adr_at(index));
2809 } else {
2810 oop value = _array_for_gc->at(index);
2811 assert(value->is_value(), "Sanity check");
2812 dealiaser.oops_do(f, value);
2813 }
2814 }
2815 }
2816
2817 // Traverse the monitor chunks
2818 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2819 chunk->oops_do(f);
2820 }
2821
2822 // Traverse the execution stack
2823 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2824 fst.current()->oops_do(f, cf, fst.register_map());
2825 }
2826 }
2827
2828 // callee_target is never live across a gc point so NULL it here should
2829 // it still contain a methdOop.
2830
2831 set_callee_target(NULL);
2832
2833 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2834 // If we have deferred set_locals there might be oops waiting to be
2835 // written
2836 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2837 if (list != NULL) {
2838 for (int i = 0; i < list->length(); i++) {
2839 list->at(i)->oops_do(f);
2840 }
2841 }
2842
2843 // Traverse instance variables at the end since the GC may be moving things
2844 // around using this function
2845 f->do_oop((oop*) &_threadObj);
2846 if (!VTBuffer::is_in_vt_buffer(_vm_result)) {
2847 f->do_oop((oop*) &_vm_result);
2848 } else {
2849 assert(_vm_result->is_value(), "Must be a value");
2850 dealiaser.oops_do(f, _vm_result);
2851 }
2852 f->do_oop((oop*) &_exception_oop);
2853 f->do_oop((oop*) &_pending_async_exception);
2854
2855 if (jvmti_thread_state() != NULL) {
2856 jvmti_thread_state()->oops_do(f);
2857 }
2858 }
2859
2860 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2861 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2862 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2863
2864 if (has_last_Java_frame()) {
2865 // Traverse the execution stack
2866 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2867 fst.current()->nmethods_do(cf);
2868 }
2869 }
2870 }
2871
2872 void JavaThread::metadata_do(void f(Metadata*)) {
2873 if (has_last_Java_frame()) {
2874 // Traverse the execution stack to call f() on the methods in the stack
2875 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2876 fst.current()->metadata_do(f);
2877 }
2878 } else if (is_Compiler_thread()) {
2879 // need to walk ciMetadata in current compile tasks to keep alive.
2880 CompilerThread* ct = (CompilerThread*)this;
2881 if (ct->env() != NULL) {
2882 ct->env()->metadata_do(f);
2883 }
2884 if (ct->task() != NULL) {
2885 ct->task()->metadata_do(f);
2886 }
2887 }
2888 }
2889
2890 // Printing
2891 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2892 switch (_thread_state) {
2893 case _thread_uninitialized: return "_thread_uninitialized";
2894 case _thread_new: return "_thread_new";
2895 case _thread_new_trans: return "_thread_new_trans";
2896 case _thread_in_native: return "_thread_in_native";
2897 case _thread_in_native_trans: return "_thread_in_native_trans";
2898 case _thread_in_vm: return "_thread_in_vm";
2899 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2900 case _thread_in_Java: return "_thread_in_Java";
2901 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2902 case _thread_blocked: return "_thread_blocked";
2903 case _thread_blocked_trans: return "_thread_blocked_trans";
2904 default: return "unknown thread state";
2905 }
2906 }
2907
2908 #ifndef PRODUCT
2909 void JavaThread::print_thread_state_on(outputStream *st) const {
2910 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2911 };
2912 void JavaThread::print_thread_state() const {
2913 print_thread_state_on(tty);
2914 }
2915 #endif // PRODUCT
2916
2917 // Called by Threads::print() for VM_PrintThreads operation
2918 void JavaThread::print_on(outputStream *st) const {
2919 st->print_raw("\"");
2920 st->print_raw(get_thread_name());
2921 st->print_raw("\" ");
2922 oop thread_oop = threadObj();
2923 if (thread_oop != NULL) {
2924 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2925 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2926 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2927 }
2928 Thread::print_on(st);
2929 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2930 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2931 if (thread_oop != NULL) {
2932 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2933 }
2934 #ifndef PRODUCT
2935 print_thread_state_on(st);
2936 _safepoint_state->print_on(st);
2937 #endif // PRODUCT
2938 if (is_Compiler_thread()) {
2939 CompilerThread* ct = (CompilerThread*)this;
2940 if (ct->task() != NULL) {
2941 st->print(" Compiling: ");
2942 ct->task()->print(st, NULL, true, false);
2943 } else {
2944 st->print(" No compile task");
2945 }
2946 st->cr();
2947 }
2948 }
2949
2950 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2951 st->print("%s", get_thread_name_string(buf, buflen));
2952 }
2953
2954 // Called by fatal error handler. The difference between this and
2955 // JavaThread::print() is that we can't grab lock or allocate memory.
2956 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2957 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2958 oop thread_obj = threadObj();
2959 if (thread_obj != NULL) {
2960 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2961 }
2962 st->print(" [");
2963 st->print("%s", _get_thread_state_name(_thread_state));
2964 if (osthread()) {
2965 st->print(", id=%d", osthread()->thread_id());
2966 }
2967 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2968 p2i(stack_end()), p2i(stack_base()));
2969 st->print("]");
2970 return;
2971 }
2972
2973 // Verification
2974
2975 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2976
2977 void JavaThread::verify() {
2978 // Verify oops in the thread.
2979 oops_do(&VerifyOopClosure::verify_oop, NULL);
2980
2981 // Verify the stack frames.
2982 frames_do(frame_verify);
2983 }
2984
2985 // CR 6300358 (sub-CR 2137150)
2986 // Most callers of this method assume that it can't return NULL but a
2987 // thread may not have a name whilst it is in the process of attaching to
2988 // the VM - see CR 6412693, and there are places where a JavaThread can be
2989 // seen prior to having it's threadObj set (eg JNI attaching threads and
2990 // if vm exit occurs during initialization). These cases can all be accounted
2991 // for such that this method never returns NULL.
2992 const char* JavaThread::get_thread_name() const {
2993 #ifdef ASSERT
2994 // early safepoints can hit while current thread does not yet have TLS
2995 if (!SafepointSynchronize::is_at_safepoint()) {
2996 Thread *cur = Thread::current();
2997 if (!(cur->is_Java_thread() && cur == this)) {
2998 // Current JavaThreads are allowed to get their own name without
2999 // the Threads_lock.
3000 assert_locked_or_safepoint(Threads_lock);
3001 }
3002 }
3003 #endif // ASSERT
3004 return get_thread_name_string();
3005 }
3006
3007 // Returns a non-NULL representation of this thread's name, or a suitable
3008 // descriptive string if there is no set name
3009 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3010 const char* name_str;
3011 oop thread_obj = threadObj();
3012 if (thread_obj != NULL) {
3013 oop name = java_lang_Thread::name(thread_obj);
3014 if (name != NULL) {
3015 if (buf == NULL) {
3016 name_str = java_lang_String::as_utf8_string(name);
3017 } else {
3018 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3019 }
3020 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3021 name_str = "<no-name - thread is attaching>";
3022 } else {
3023 name_str = Thread::name();
3024 }
3025 } else {
3026 name_str = Thread::name();
3027 }
3028 assert(name_str != NULL, "unexpected NULL thread name");
3029 return name_str;
3030 }
3031
3032
3033 const char* JavaThread::get_threadgroup_name() const {
3034 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3035 oop thread_obj = threadObj();
3036 if (thread_obj != NULL) {
3037 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3038 if (thread_group != NULL) {
3039 // ThreadGroup.name can be null
3040 return java_lang_ThreadGroup::name(thread_group);
3041 }
3042 }
3043 return NULL;
3044 }
3045
3046 const char* JavaThread::get_parent_name() const {
3047 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3048 oop thread_obj = threadObj();
3049 if (thread_obj != NULL) {
3050 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3051 if (thread_group != NULL) {
3052 oop parent = java_lang_ThreadGroup::parent(thread_group);
3053 if (parent != NULL) {
3054 // ThreadGroup.name can be null
3055 return java_lang_ThreadGroup::name(parent);
3056 }
3057 }
3058 }
3059 return NULL;
3060 }
3061
3062 ThreadPriority JavaThread::java_priority() const {
3063 oop thr_oop = threadObj();
3064 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3065 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3066 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3067 return priority;
3068 }
3069
3070 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3071
3072 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3073 // Link Java Thread object <-> C++ Thread
3074
3075 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3076 // and put it into a new Handle. The Handle "thread_oop" can then
3077 // be used to pass the C++ thread object to other methods.
3078
3079 // Set the Java level thread object (jthread) field of the
3080 // new thread (a JavaThread *) to C++ thread object using the
3081 // "thread_oop" handle.
3082
3083 // Set the thread field (a JavaThread *) of the
3084 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3085
3086 Handle thread_oop(Thread::current(),
3087 JNIHandles::resolve_non_null(jni_thread));
3088 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3089 "must be initialized");
3090 set_threadObj(thread_oop());
3091 java_lang_Thread::set_thread(thread_oop(), this);
3092
3093 if (prio == NoPriority) {
3094 prio = java_lang_Thread::priority(thread_oop());
3095 assert(prio != NoPriority, "A valid priority should be present");
3096 }
3097
3098 // Push the Java priority down to the native thread; needs Threads_lock
3099 Thread::set_priority(this, prio);
3100
3101 prepare_ext();
3102
3103 // Add the new thread to the Threads list and set it in motion.
3104 // We must have threads lock in order to call Threads::add.
3105 // It is crucial that we do not block before the thread is
3106 // added to the Threads list for if a GC happens, then the java_thread oop
3107 // will not be visited by GC.
3108 Threads::add(this);
3109 }
3110
3111 oop JavaThread::current_park_blocker() {
3112 // Support for JSR-166 locks
3113 oop thread_oop = threadObj();
3114 if (thread_oop != NULL &&
3115 JDK_Version::current().supports_thread_park_blocker()) {
3116 return java_lang_Thread::park_blocker(thread_oop);
3117 }
3118 return NULL;
3119 }
3120
3121
3122 void JavaThread::print_stack_on(outputStream* st) {
3123 if (!has_last_Java_frame()) return;
3124 ResourceMark rm;
3125 HandleMark hm;
3126
3127 RegisterMap reg_map(this);
3128 vframe* start_vf = last_java_vframe(®_map);
3129 int count = 0;
3130 for (vframe* f = start_vf; f; f = f->sender()) {
3131 if (f->is_java_frame()) {
3132 javaVFrame* jvf = javaVFrame::cast(f);
3133 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3134
3135 // Print out lock information
3136 if (JavaMonitorsInStackTrace) {
3137 jvf->print_lock_info_on(st, count);
3138 }
3139 } else {
3140 // Ignore non-Java frames
3141 }
3142
3143 // Bail-out case for too deep stacks
3144 count++;
3145 if (MaxJavaStackTraceDepth == count) return;
3146 }
3147 }
3148
3149
3150 // JVMTI PopFrame support
3151 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3152 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3153 if (in_bytes(size_in_bytes) != 0) {
3154 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3155 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3156 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3157 }
3158 }
3159
3160 void* JavaThread::popframe_preserved_args() {
3161 return _popframe_preserved_args;
3162 }
3163
3164 ByteSize JavaThread::popframe_preserved_args_size() {
3165 return in_ByteSize(_popframe_preserved_args_size);
3166 }
3167
3168 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3169 int sz = in_bytes(popframe_preserved_args_size());
3170 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3171 return in_WordSize(sz / wordSize);
3172 }
3173
3174 void JavaThread::popframe_free_preserved_args() {
3175 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3176 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3177 _popframe_preserved_args = NULL;
3178 _popframe_preserved_args_size = 0;
3179 }
3180
3181 #ifndef PRODUCT
3182
3183 void JavaThread::trace_frames() {
3184 tty->print_cr("[Describe stack]");
3185 int frame_no = 1;
3186 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3187 tty->print(" %d. ", frame_no++);
3188 fst.current()->print_value_on(tty, this);
3189 tty->cr();
3190 }
3191 }
3192
3193 class PrintAndVerifyOopClosure: public OopClosure {
3194 protected:
3195 template <class T> inline void do_oop_work(T* p) {
3196 oop obj = oopDesc::load_decode_heap_oop(p);
3197 if (obj == NULL) return;
3198 tty->print(INTPTR_FORMAT ": ", p2i(p));
3199 if (oopDesc::is_oop_or_null(obj)) {
3200 if (obj->is_objArray()) {
3201 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3202 } else {
3203 obj->print();
3204 }
3205 } else {
3206 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3207 }
3208 tty->cr();
3209 }
3210 public:
3211 virtual void do_oop(oop* p) { do_oop_work(p); }
3212 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3213 };
3214
3215
3216 static void oops_print(frame* f, const RegisterMap *map) {
3217 PrintAndVerifyOopClosure print;
3218 f->print_value();
3219 f->oops_do(&print, NULL, (RegisterMap*)map);
3220 }
3221
3222 // Print our all the locations that contain oops and whether they are
3223 // valid or not. This useful when trying to find the oldest frame
3224 // where an oop has gone bad since the frame walk is from youngest to
3225 // oldest.
3226 void JavaThread::trace_oops() {
3227 tty->print_cr("[Trace oops]");
3228 frames_do(oops_print);
3229 }
3230
3231
3232 #ifdef ASSERT
3233 // Print or validate the layout of stack frames
3234 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3235 ResourceMark rm;
3236 PRESERVE_EXCEPTION_MARK;
3237 FrameValues values;
3238 int frame_no = 0;
3239 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3240 fst.current()->describe(values, ++frame_no);
3241 if (depth == frame_no) break;
3242 }
3243 if (validate_only) {
3244 values.validate();
3245 } else {
3246 tty->print_cr("[Describe stack layout]");
3247 values.print(this);
3248 }
3249 }
3250 #endif
3251
3252 void JavaThread::trace_stack_from(vframe* start_vf) {
3253 ResourceMark rm;
3254 int vframe_no = 1;
3255 for (vframe* f = start_vf; f; f = f->sender()) {
3256 if (f->is_java_frame()) {
3257 javaVFrame::cast(f)->print_activation(vframe_no++);
3258 } else {
3259 f->print();
3260 }
3261 if (vframe_no > StackPrintLimit) {
3262 tty->print_cr("...<more frames>...");
3263 return;
3264 }
3265 }
3266 }
3267
3268
3269 void JavaThread::trace_stack() {
3270 if (!has_last_Java_frame()) return;
3271 ResourceMark rm;
3272 HandleMark hm;
3273 RegisterMap reg_map(this);
3274 trace_stack_from(last_java_vframe(®_map));
3275 }
3276
3277
3278 #endif // PRODUCT
3279
3280
3281 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3282 assert(reg_map != NULL, "a map must be given");
3283 frame f = last_frame();
3284 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3285 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3286 }
3287 return NULL;
3288 }
3289
3290
3291 Klass* JavaThread::security_get_caller_class(int depth) {
3292 vframeStream vfst(this);
3293 vfst.security_get_caller_frame(depth);
3294 if (!vfst.at_end()) {
3295 return vfst.method()->method_holder();
3296 }
3297 return NULL;
3298 }
3299
3300 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3301 assert(thread->is_Compiler_thread(), "must be compiler thread");
3302 CompileBroker::compiler_thread_loop();
3303 }
3304
3305 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3306 NMethodSweeper::sweeper_loop();
3307 }
3308
3309 // Create a CompilerThread
3310 CompilerThread::CompilerThread(CompileQueue* queue,
3311 CompilerCounters* counters)
3312 : JavaThread(&compiler_thread_entry) {
3313 _env = NULL;
3314 _log = NULL;
3315 _task = NULL;
3316 _queue = queue;
3317 _counters = counters;
3318 _buffer_blob = NULL;
3319 _compiler = NULL;
3320
3321 #ifndef PRODUCT
3322 _ideal_graph_printer = NULL;
3323 #endif
3324 }
3325
3326 bool CompilerThread::can_call_java() const {
3327 return _compiler != NULL && _compiler->is_jvmci();
3328 }
3329
3330 // Create sweeper thread
3331 CodeCacheSweeperThread::CodeCacheSweeperThread()
3332 : JavaThread(&sweeper_thread_entry) {
3333 _scanned_compiled_method = NULL;
3334 }
3335
3336 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3337 JavaThread::oops_do(f, cf);
3338 if (_scanned_compiled_method != NULL && cf != NULL) {
3339 // Safepoints can occur when the sweeper is scanning an nmethod so
3340 // process it here to make sure it isn't unloaded in the middle of
3341 // a scan.
3342 cf->do_code_blob(_scanned_compiled_method);
3343 }
3344 }
3345
3346 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3347 JavaThread::nmethods_do(cf);
3348 if (_scanned_compiled_method != NULL && cf != NULL) {
3349 // Safepoints can occur when the sweeper is scanning an nmethod so
3350 // process it here to make sure it isn't unloaded in the middle of
3351 // a scan.
3352 cf->do_code_blob(_scanned_compiled_method);
3353 }
3354 }
3355
3356
3357 // ======= Threads ========
3358
3359 // The Threads class links together all active threads, and provides
3360 // operations over all threads. It is protected by its own Mutex
3361 // lock, which is also used in other contexts to protect thread
3362 // operations from having the thread being operated on from exiting
3363 // and going away unexpectedly (e.g., safepoint synchronization)
3364
3365 JavaThread* Threads::_thread_list = NULL;
3366 int Threads::_number_of_threads = 0;
3367 int Threads::_number_of_non_daemon_threads = 0;
3368 int Threads::_return_code = 0;
3369 int Threads::_thread_claim_parity = 0;
3370 size_t JavaThread::_stack_size_at_create = 0;
3371 #ifdef ASSERT
3372 bool Threads::_vm_complete = false;
3373 #endif
3374
3375 // All JavaThreads
3376 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3377
3378 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3379 void Threads::threads_do(ThreadClosure* tc) {
3380 assert_locked_or_safepoint(Threads_lock);
3381 // ALL_JAVA_THREADS iterates through all JavaThreads
3382 ALL_JAVA_THREADS(p) {
3383 tc->do_thread(p);
3384 }
3385 // Someday we could have a table or list of all non-JavaThreads.
3386 // For now, just manually iterate through them.
3387 tc->do_thread(VMThread::vm_thread());
3388 Universe::heap()->gc_threads_do(tc);
3389 WatcherThread *wt = WatcherThread::watcher_thread();
3390 // Strictly speaking, the following NULL check isn't sufficient to make sure
3391 // the data for WatcherThread is still valid upon being examined. However,
3392 // considering that WatchThread terminates when the VM is on the way to
3393 // exit at safepoint, the chance of the above is extremely small. The right
3394 // way to prevent termination of WatcherThread would be to acquire
3395 // Terminator_lock, but we can't do that without violating the lock rank
3396 // checking in some cases.
3397 if (wt != NULL) {
3398 tc->do_thread(wt);
3399 }
3400
3401 // If CompilerThreads ever become non-JavaThreads, add them here
3402 }
3403
3404 void Threads::parallel_java_threads_do(ThreadClosure* tc) {
3405 int cp = Threads::thread_claim_parity();
3406 ALL_JAVA_THREADS(p) {
3407 if (p->claim_oops_do(true, cp)) {
3408 tc->do_thread(p);
3409 }
3410 }
3411 // Thread claiming protocol requires us to claim the same interesting
3412 // threads on all paths. Notably, Threads::possibly_parallel_threads_do
3413 // claims all Java threads *and* the VMThread. To avoid breaking the
3414 // claiming protocol, we have to claim VMThread on this path too, even
3415 // if we do not apply the closure to the VMThread.
3416 VMThread* vmt = VMThread::vm_thread();
3417 (void)vmt->claim_oops_do(true, cp);
3418 }
3419
3420 // The system initialization in the library has three phases.
3421 //
3422 // Phase 1: java.lang.System class initialization
3423 // java.lang.System is a primordial class loaded and initialized
3424 // by the VM early during startup. java.lang.System.<clinit>
3425 // only does registerNatives and keeps the rest of the class
3426 // initialization work later until thread initialization completes.
3427 //
3428 // System.initPhase1 initializes the system properties, the static
3429 // fields in, out, and err. Set up java signal handlers, OS-specific
3430 // system settings, and thread group of the main thread.
3431 static void call_initPhase1(TRAPS) {
3432 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3433 JavaValue result(T_VOID);
3434 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3435 vmSymbols::void_method_signature(), CHECK);
3436 }
3437
3438 // Phase 2. Module system initialization
3439 // This will initialize the module system. Only java.base classes
3440 // can be loaded until phase 2 completes.
3441 //
3442 // Call System.initPhase2 after the compiler initialization and jsr292
3443 // classes get initialized because module initialization runs a lot of java
3444 // code, that for performance reasons, should be compiled. Also, this will
3445 // enable the startup code to use lambda and other language features in this
3446 // phase and onward.
3447 //
3448 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3449 static void call_initPhase2(TRAPS) {
3450 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3451
3452 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3453
3454 JavaValue result(T_INT);
3455 JavaCallArguments args;
3456 args.push_int(DisplayVMOutputToStderr);
3457 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3458 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3459 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3460 if (result.get_jint() != JNI_OK) {
3461 vm_exit_during_initialization(); // no message or exception
3462 }
3463
3464 universe_post_module_init();
3465 }
3466
3467 // Phase 3. final setup - set security manager, system class loader and TCCL
3468 //
3469 // This will instantiate and set the security manager, set the system class
3470 // loader as well as the thread context class loader. The security manager
3471 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3472 // other modules or the application's classpath.
3473 static void call_initPhase3(TRAPS) {
3474 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3475 JavaValue result(T_VOID);
3476 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3477 vmSymbols::void_method_signature(), CHECK);
3478 }
3479
3480 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3481 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3482
3483 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3484 create_vm_init_libraries();
3485 }
3486
3487 initialize_class(vmSymbols::java_lang_String(), CHECK);
3488
3489 // Inject CompactStrings value after the static initializers for String ran.
3490 java_lang_String::set_compact_strings(CompactStrings);
3491
3492 // Initialize java_lang.System (needed before creating the thread)
3493 initialize_class(vmSymbols::java_lang_System(), CHECK);
3494 // The VM creates & returns objects of this class. Make sure it's initialized.
3495 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3496 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3497 Handle thread_group = create_initial_thread_group(CHECK);
3498 Universe::set_main_thread_group(thread_group());
3499 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3500 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3501 main_thread->set_threadObj(thread_object);
3502 // Set thread status to running since main thread has
3503 // been started and running.
3504 java_lang_Thread::set_thread_status(thread_object,
3505 java_lang_Thread::RUNNABLE);
3506
3507 // The VM creates objects of this class.
3508 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3509
3510 // The VM preresolves methods to these classes. Make sure that they get initialized
3511 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3512 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3513
3514 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3515 call_initPhase1(CHECK);
3516
3517 // get the Java runtime name after java.lang.System is initialized
3518 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3519 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3520
3521 // an instance of OutOfMemory exception has been allocated earlier
3522 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3523 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3524 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3525 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3526 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3527 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3528 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3529 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3530 }
3531
3532 void Threads::initialize_jsr292_core_classes(TRAPS) {
3533 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3534
3535 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3536 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3537 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3538 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3539 }
3540
3541 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3542 extern void JDK_Version_init();
3543
3544 // Preinitialize version info.
3545 VM_Version::early_initialize();
3546
3547 // Check version
3548 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3549
3550 // Initialize library-based TLS
3551 ThreadLocalStorage::init();
3552
3553 // Initialize the output stream module
3554 ostream_init();
3555
3556 // Process java launcher properties.
3557 Arguments::process_sun_java_launcher_properties(args);
3558
3559 // Initialize the os module
3560 os::init();
3561
3562 // Record VM creation timing statistics
3563 TraceVmCreationTime create_vm_timer;
3564 create_vm_timer.start();
3565
3566 // Initialize system properties.
3567 Arguments::init_system_properties();
3568
3569 // So that JDK version can be used as a discriminator when parsing arguments
3570 JDK_Version_init();
3571
3572 // Update/Initialize System properties after JDK version number is known
3573 Arguments::init_version_specific_system_properties();
3574
3575 // Make sure to initialize log configuration *before* parsing arguments
3576 LogConfiguration::initialize(create_vm_timer.begin_time());
3577
3578 // Parse arguments
3579 jint parse_result = Arguments::parse(args);
3580 if (parse_result != JNI_OK) return parse_result;
3581
3582 os::init_before_ergo();
3583
3584 jint ergo_result = Arguments::apply_ergo();
3585 if (ergo_result != JNI_OK) return ergo_result;
3586
3587 // Final check of all ranges after ergonomics which may change values.
3588 if (!CommandLineFlagRangeList::check_ranges()) {
3589 return JNI_EINVAL;
3590 }
3591
3592 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3593 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3594 if (!constraint_result) {
3595 return JNI_EINVAL;
3596 }
3597
3598 CommandLineFlagWriteableList::mark_startup();
3599
3600 if (PauseAtStartup) {
3601 os::pause();
3602 }
3603
3604 HOTSPOT_VM_INIT_BEGIN();
3605
3606 // Timing (must come after argument parsing)
3607 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3608
3609 // Initialize the os module after parsing the args
3610 jint os_init_2_result = os::init_2();
3611 if (os_init_2_result != JNI_OK) return os_init_2_result;
3612
3613 jint adjust_after_os_result = Arguments::adjust_after_os();
3614 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3615
3616 // Initialize output stream logging
3617 ostream_init_log();
3618
3619 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3620 // Must be before create_vm_init_agents()
3621 if (Arguments::init_libraries_at_startup()) {
3622 convert_vm_init_libraries_to_agents();
3623 }
3624
3625 // Launch -agentlib/-agentpath and converted -Xrun agents
3626 if (Arguments::init_agents_at_startup()) {
3627 create_vm_init_agents();
3628 }
3629
3630 // Initialize Threads state
3631 _thread_list = NULL;
3632 _number_of_threads = 0;
3633 _number_of_non_daemon_threads = 0;
3634
3635 // Initialize global data structures and create system classes in heap
3636 vm_init_globals();
3637
3638 #if INCLUDE_JVMCI
3639 if (JVMCICounterSize > 0) {
3640 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3641 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3642 } else {
3643 JavaThread::_jvmci_old_thread_counters = NULL;
3644 }
3645 #endif // INCLUDE_JVMCI
3646
3647 // Attach the main thread to this os thread
3648 JavaThread* main_thread = new JavaThread();
3649 main_thread->set_thread_state(_thread_in_vm);
3650 main_thread->initialize_thread_current();
3651 // must do this before set_active_handles
3652 main_thread->record_stack_base_and_size();
3653 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3654
3655 if (!main_thread->set_as_starting_thread()) {
3656 vm_shutdown_during_initialization(
3657 "Failed necessary internal allocation. Out of swap space");
3658 delete main_thread;
3659 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3660 return JNI_ENOMEM;
3661 }
3662
3663 // Enable guard page *after* os::create_main_thread(), otherwise it would
3664 // crash Linux VM, see notes in os_linux.cpp.
3665 main_thread->create_stack_guard_pages();
3666
3667 // Initialize Java-Level synchronization subsystem
3668 ObjectMonitor::Initialize();
3669
3670 // Initialize global modules
3671 jint status = init_globals();
3672 if (status != JNI_OK) {
3673 delete main_thread;
3674 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3675 return status;
3676 }
3677
3678 if (TRACE_INITIALIZE() != JNI_OK) {
3679 vm_exit_during_initialization("Failed to initialize tracing backend");
3680 }
3681
3682 // Should be done after the heap is fully created
3683 main_thread->cache_global_variables();
3684
3685 HandleMark hm;
3686
3687 { MutexLocker mu(Threads_lock);
3688 Threads::add(main_thread);
3689 }
3690
3691 // Any JVMTI raw monitors entered in onload will transition into
3692 // real raw monitor. VM is setup enough here for raw monitor enter.
3693 JvmtiExport::transition_pending_onload_raw_monitors();
3694
3695 // Create the VMThread
3696 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3697
3698 VMThread::create();
3699 Thread* vmthread = VMThread::vm_thread();
3700
3701 if (!os::create_thread(vmthread, os::vm_thread)) {
3702 vm_exit_during_initialization("Cannot create VM thread. "
3703 "Out of system resources.");
3704 }
3705
3706 // Wait for the VM thread to become ready, and VMThread::run to initialize
3707 // Monitors can have spurious returns, must always check another state flag
3708 {
3709 MutexLocker ml(Notify_lock);
3710 os::start_thread(vmthread);
3711 while (vmthread->active_handles() == NULL) {
3712 Notify_lock->wait();
3713 }
3714 }
3715 }
3716
3717 assert(Universe::is_fully_initialized(), "not initialized");
3718 if (VerifyDuringStartup) {
3719 // Make sure we're starting with a clean slate.
3720 VM_Verify verify_op;
3721 VMThread::execute(&verify_op);
3722 }
3723
3724 Thread* THREAD = Thread::current();
3725
3726 // Always call even when there are not JVMTI environments yet, since environments
3727 // may be attached late and JVMTI must track phases of VM execution
3728 JvmtiExport::enter_early_start_phase();
3729
3730 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3731 JvmtiExport::post_early_vm_start();
3732
3733 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3734
3735 // We need this for ClassDataSharing - the initial vm.info property is set
3736 // with the default value of CDS "sharing" which may be reset through
3737 // command line options.
3738 reset_vm_info_property(CHECK_JNI_ERR);
3739
3740 quicken_jni_functions();
3741
3742 // No more stub generation allowed after that point.
3743 StubCodeDesc::freeze();
3744
3745 // Set flag that basic initialization has completed. Used by exceptions and various
3746 // debug stuff, that does not work until all basic classes have been initialized.
3747 set_init_completed();
3748
3749 LogConfiguration::post_initialize();
3750 Metaspace::post_initialize();
3751
3752 HOTSPOT_VM_INIT_END();
3753
3754 // record VM initialization completion time
3755 #if INCLUDE_MANAGEMENT
3756 Management::record_vm_init_completed();
3757 #endif // INCLUDE_MANAGEMENT
3758
3759 // Signal Dispatcher needs to be started before VMInit event is posted
3760 os::signal_init(CHECK_JNI_ERR);
3761
3762 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3763 if (!DisableAttachMechanism) {
3764 AttachListener::vm_start();
3765 if (StartAttachListener || AttachListener::init_at_startup()) {
3766 AttachListener::init();
3767 }
3768 }
3769
3770 // Launch -Xrun agents
3771 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3772 // back-end can launch with -Xdebug -Xrunjdwp.
3773 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3774 create_vm_init_libraries();
3775 }
3776
3777 if (CleanChunkPoolAsync) {
3778 Chunk::start_chunk_pool_cleaner_task();
3779 }
3780
3781 // initialize compiler(s)
3782 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3783 CompileBroker::compilation_init(CHECK_JNI_ERR);
3784 #endif
3785
3786 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3787 // It is done after compilers are initialized, because otherwise compilations of
3788 // signature polymorphic MH intrinsics can be missed
3789 // (see SystemDictionary::find_method_handle_intrinsic).
3790 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3791
3792 // This will initialize the module system. Only java.base classes can be
3793 // loaded until phase 2 completes
3794 call_initPhase2(CHECK_JNI_ERR);
3795
3796 // Always call even when there are not JVMTI environments yet, since environments
3797 // may be attached late and JVMTI must track phases of VM execution
3798 JvmtiExport::enter_start_phase();
3799
3800 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3801 JvmtiExport::post_vm_start();
3802
3803 // Final system initialization including security manager and system class loader
3804 call_initPhase3(CHECK_JNI_ERR);
3805
3806 // cache the system class loader
3807 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3808
3809 #if INCLUDE_JVMCI
3810 if (EnableJVMCI) {
3811 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3812 // The JVMCI Java initialization code will read this flag and
3813 // do the printing if it's set.
3814 bool init = JVMCIPrintProperties;
3815
3816 if (!init) {
3817 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3818 // compilations via JVMCI will not actually block until JVMCI is initialized.
3819 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3820 }
3821
3822 if (init) {
3823 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3824 }
3825 }
3826 #endif
3827
3828 // Always call even when there are not JVMTI environments yet, since environments
3829 // may be attached late and JVMTI must track phases of VM execution
3830 JvmtiExport::enter_live_phase();
3831
3832 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3833 JvmtiExport::post_vm_initialized();
3834
3835 if (TRACE_START() != JNI_OK) {
3836 vm_exit_during_initialization("Failed to start tracing backend.");
3837 }
3838
3839 #if INCLUDE_MANAGEMENT
3840 Management::initialize(THREAD);
3841
3842 if (HAS_PENDING_EXCEPTION) {
3843 // management agent fails to start possibly due to
3844 // configuration problem and is responsible for printing
3845 // stack trace if appropriate. Simply exit VM.
3846 vm_exit(1);
3847 }
3848 #endif // INCLUDE_MANAGEMENT
3849
3850 if (MemProfiling) MemProfiler::engage();
3851 StatSampler::engage();
3852 if (CheckJNICalls) JniPeriodicChecker::engage();
3853
3854 BiasedLocking::init();
3855
3856 #if INCLUDE_RTM_OPT
3857 RTMLockingCounters::init();
3858 #endif
3859
3860 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3861 call_postVMInitHook(THREAD);
3862 // The Java side of PostVMInitHook.run must deal with all
3863 // exceptions and provide means of diagnosis.
3864 if (HAS_PENDING_EXCEPTION) {
3865 CLEAR_PENDING_EXCEPTION;
3866 }
3867 }
3868
3869 {
3870 MutexLocker ml(PeriodicTask_lock);
3871 // Make sure the WatcherThread can be started by WatcherThread::start()
3872 // or by dynamic enrollment.
3873 WatcherThread::make_startable();
3874 // Start up the WatcherThread if there are any periodic tasks
3875 // NOTE: All PeriodicTasks should be registered by now. If they
3876 // aren't, late joiners might appear to start slowly (we might
3877 // take a while to process their first tick).
3878 if (PeriodicTask::num_tasks() > 0) {
3879 WatcherThread::start();
3880 }
3881 }
3882
3883 create_vm_timer.end();
3884 #ifdef ASSERT
3885 _vm_complete = true;
3886 #endif
3887
3888 if (DumpSharedSpaces) {
3889 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3890 ShouldNotReachHere();
3891 }
3892
3893 return JNI_OK;
3894 }
3895
3896 // type for the Agent_OnLoad and JVM_OnLoad entry points
3897 extern "C" {
3898 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3899 }
3900 // Find a command line agent library and return its entry point for
3901 // -agentlib: -agentpath: -Xrun
3902 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3903 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3904 const char *on_load_symbols[],
3905 size_t num_symbol_entries) {
3906 OnLoadEntry_t on_load_entry = NULL;
3907 void *library = NULL;
3908
3909 if (!agent->valid()) {
3910 char buffer[JVM_MAXPATHLEN];
3911 char ebuf[1024] = "";
3912 const char *name = agent->name();
3913 const char *msg = "Could not find agent library ";
3914
3915 // First check to see if agent is statically linked into executable
3916 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3917 library = agent->os_lib();
3918 } else if (agent->is_absolute_path()) {
3919 library = os::dll_load(name, ebuf, sizeof ebuf);
3920 if (library == NULL) {
3921 const char *sub_msg = " in absolute path, with error: ";
3922 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3923 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3924 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3925 // If we can't find the agent, exit.
3926 vm_exit_during_initialization(buf, NULL);
3927 FREE_C_HEAP_ARRAY(char, buf);
3928 }
3929 } else {
3930 // Try to load the agent from the standard dll directory
3931 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3932 name)) {
3933 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3934 }
3935 if (library == NULL) { // Try the library path directory.
3936 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3937 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3938 }
3939 if (library == NULL) {
3940 const char *sub_msg = " on the library path, with error: ";
3941 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3942 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3943 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3944 // If we can't find the agent, exit.
3945 vm_exit_during_initialization(buf, NULL);
3946 FREE_C_HEAP_ARRAY(char, buf);
3947 }
3948 }
3949 }
3950 agent->set_os_lib(library);
3951 agent->set_valid();
3952 }
3953
3954 // Find the OnLoad function.
3955 on_load_entry =
3956 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3957 false,
3958 on_load_symbols,
3959 num_symbol_entries));
3960 return on_load_entry;
3961 }
3962
3963 // Find the JVM_OnLoad entry point
3964 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3965 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3966 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3967 }
3968
3969 // Find the Agent_OnLoad entry point
3970 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3971 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3972 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3973 }
3974
3975 // For backwards compatibility with -Xrun
3976 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3977 // treated like -agentpath:
3978 // Must be called before agent libraries are created
3979 void Threads::convert_vm_init_libraries_to_agents() {
3980 AgentLibrary* agent;
3981 AgentLibrary* next;
3982
3983 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3984 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3985 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3986
3987 // If there is an JVM_OnLoad function it will get called later,
3988 // otherwise see if there is an Agent_OnLoad
3989 if (on_load_entry == NULL) {
3990 on_load_entry = lookup_agent_on_load(agent);
3991 if (on_load_entry != NULL) {
3992 // switch it to the agent list -- so that Agent_OnLoad will be called,
3993 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3994 Arguments::convert_library_to_agent(agent);
3995 } else {
3996 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3997 }
3998 }
3999 }
4000 }
4001
4002 // Create agents for -agentlib: -agentpath: and converted -Xrun
4003 // Invokes Agent_OnLoad
4004 // Called very early -- before JavaThreads exist
4005 void Threads::create_vm_init_agents() {
4006 extern struct JavaVM_ main_vm;
4007 AgentLibrary* agent;
4008
4009 JvmtiExport::enter_onload_phase();
4010
4011 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4012 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4013
4014 if (on_load_entry != NULL) {
4015 // Invoke the Agent_OnLoad function
4016 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4017 if (err != JNI_OK) {
4018 vm_exit_during_initialization("agent library failed to init", agent->name());
4019 }
4020 } else {
4021 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4022 }
4023 }
4024 JvmtiExport::enter_primordial_phase();
4025 }
4026
4027 extern "C" {
4028 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4029 }
4030
4031 void Threads::shutdown_vm_agents() {
4032 // Send any Agent_OnUnload notifications
4033 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4034 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4035 extern struct JavaVM_ main_vm;
4036 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4037
4038 // Find the Agent_OnUnload function.
4039 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4040 os::find_agent_function(agent,
4041 false,
4042 on_unload_symbols,
4043 num_symbol_entries));
4044
4045 // Invoke the Agent_OnUnload function
4046 if (unload_entry != NULL) {
4047 JavaThread* thread = JavaThread::current();
4048 ThreadToNativeFromVM ttn(thread);
4049 HandleMark hm(thread);
4050 (*unload_entry)(&main_vm);
4051 }
4052 }
4053 }
4054
4055 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4056 // Invokes JVM_OnLoad
4057 void Threads::create_vm_init_libraries() {
4058 extern struct JavaVM_ main_vm;
4059 AgentLibrary* agent;
4060
4061 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4062 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4063
4064 if (on_load_entry != NULL) {
4065 // Invoke the JVM_OnLoad function
4066 JavaThread* thread = JavaThread::current();
4067 ThreadToNativeFromVM ttn(thread);
4068 HandleMark hm(thread);
4069 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4070 if (err != JNI_OK) {
4071 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4072 }
4073 } else {
4074 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4075 }
4076 }
4077 }
4078
4079 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4080 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4081
4082 JavaThread* java_thread = NULL;
4083 // Sequential search for now. Need to do better optimization later.
4084 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4085 oop tobj = thread->threadObj();
4086 if (!thread->is_exiting() &&
4087 tobj != NULL &&
4088 java_tid == java_lang_Thread::thread_id(tobj)) {
4089 java_thread = thread;
4090 break;
4091 }
4092 }
4093 return java_thread;
4094 }
4095
4096
4097 // Last thread running calls java.lang.Shutdown.shutdown()
4098 void JavaThread::invoke_shutdown_hooks() {
4099 HandleMark hm(this);
4100
4101 // We could get here with a pending exception, if so clear it now.
4102 if (this->has_pending_exception()) {
4103 this->clear_pending_exception();
4104 }
4105
4106 EXCEPTION_MARK;
4107 Klass* shutdown_klass =
4108 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4109 THREAD);
4110 if (shutdown_klass != NULL) {
4111 // SystemDictionary::resolve_or_null will return null if there was
4112 // an exception. If we cannot load the Shutdown class, just don't
4113 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4114 // and finalizers (if runFinalizersOnExit is set) won't be run.
4115 // Note that if a shutdown hook was registered or runFinalizersOnExit
4116 // was called, the Shutdown class would have already been loaded
4117 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4118 JavaValue result(T_VOID);
4119 JavaCalls::call_static(&result,
4120 shutdown_klass,
4121 vmSymbols::shutdown_method_name(),
4122 vmSymbols::void_method_signature(),
4123 THREAD);
4124 }
4125 CLEAR_PENDING_EXCEPTION;
4126 }
4127
4128 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4129 // the program falls off the end of main(). Another VM exit path is through
4130 // vm_exit() when the program calls System.exit() to return a value or when
4131 // there is a serious error in VM. The two shutdown paths are not exactly
4132 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4133 // and VM_Exit op at VM level.
4134 //
4135 // Shutdown sequence:
4136 // + Shutdown native memory tracking if it is on
4137 // + Wait until we are the last non-daemon thread to execute
4138 // <-- every thing is still working at this moment -->
4139 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4140 // shutdown hooks, run finalizers if finalization-on-exit
4141 // + Call before_exit(), prepare for VM exit
4142 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4143 // currently the only user of this mechanism is File.deleteOnExit())
4144 // > stop StatSampler, watcher thread, CMS threads,
4145 // post thread end and vm death events to JVMTI,
4146 // stop signal thread
4147 // + Call JavaThread::exit(), it will:
4148 // > release JNI handle blocks, remove stack guard pages
4149 // > remove this thread from Threads list
4150 // <-- no more Java code from this thread after this point -->
4151 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4152 // the compiler threads at safepoint
4153 // <-- do not use anything that could get blocked by Safepoint -->
4154 // + Disable tracing at JNI/JVM barriers
4155 // + Set _vm_exited flag for threads that are still running native code
4156 // + Delete this thread
4157 // + Call exit_globals()
4158 // > deletes tty
4159 // > deletes PerfMemory resources
4160 // + Return to caller
4161
4162 bool Threads::destroy_vm() {
4163 JavaThread* thread = JavaThread::current();
4164
4165 #ifdef ASSERT
4166 _vm_complete = false;
4167 #endif
4168 // Wait until we are the last non-daemon thread to execute
4169 { MutexLocker nu(Threads_lock);
4170 while (Threads::number_of_non_daemon_threads() > 1)
4171 // This wait should make safepoint checks, wait without a timeout,
4172 // and wait as a suspend-equivalent condition.
4173 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4174 Mutex::_as_suspend_equivalent_flag);
4175 }
4176
4177 // Hang forever on exit if we are reporting an error.
4178 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4179 os::infinite_sleep();
4180 }
4181 os::wait_for_keypress_at_exit();
4182
4183 // run Java level shutdown hooks
4184 thread->invoke_shutdown_hooks();
4185
4186 before_exit(thread);
4187
4188 thread->exit(true);
4189
4190 // Stop VM thread.
4191 {
4192 // 4945125 The vm thread comes to a safepoint during exit.
4193 // GC vm_operations can get caught at the safepoint, and the
4194 // heap is unparseable if they are caught. Grab the Heap_lock
4195 // to prevent this. The GC vm_operations will not be able to
4196 // queue until after the vm thread is dead. After this point,
4197 // we'll never emerge out of the safepoint before the VM exits.
4198
4199 MutexLocker ml(Heap_lock);
4200
4201 VMThread::wait_for_vm_thread_exit();
4202 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4203 VMThread::destroy();
4204 }
4205
4206 // clean up ideal graph printers
4207 #if defined(COMPILER2) && !defined(PRODUCT)
4208 IdealGraphPrinter::clean_up();
4209 #endif
4210
4211 // Now, all Java threads are gone except daemon threads. Daemon threads
4212 // running Java code or in VM are stopped by the Safepoint. However,
4213 // daemon threads executing native code are still running. But they
4214 // will be stopped at native=>Java/VM barriers. Note that we can't
4215 // simply kill or suspend them, as it is inherently deadlock-prone.
4216
4217 VM_Exit::set_vm_exited();
4218
4219 notify_vm_shutdown();
4220
4221 delete thread;
4222
4223 #if INCLUDE_JVMCI
4224 if (JVMCICounterSize > 0) {
4225 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4226 }
4227 #endif
4228
4229 // exit_globals() will delete tty
4230 exit_globals();
4231
4232 LogConfiguration::finalize();
4233
4234 return true;
4235 }
4236
4237
4238 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4239 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4240 return is_supported_jni_version(version);
4241 }
4242
4243
4244 jboolean Threads::is_supported_jni_version(jint version) {
4245 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4246 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4247 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4248 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4249 if (version == JNI_VERSION_9) return JNI_TRUE;
4250 return JNI_FALSE;
4251 }
4252
4253
4254 void Threads::add(JavaThread* p, bool force_daemon) {
4255 // The threads lock must be owned at this point
4256 assert_locked_or_safepoint(Threads_lock);
4257
4258 // See the comment for this method in thread.hpp for its purpose and
4259 // why it is called here.
4260 p->initialize_queues();
4261 p->set_next(_thread_list);
4262 _thread_list = p;
4263 _number_of_threads++;
4264 oop threadObj = p->threadObj();
4265 bool daemon = true;
4266 // Bootstrapping problem: threadObj can be null for initial
4267 // JavaThread (or for threads attached via JNI)
4268 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4269 _number_of_non_daemon_threads++;
4270 daemon = false;
4271 }
4272
4273 ThreadService::add_thread(p, daemon);
4274
4275 // Possible GC point.
4276 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4277 }
4278
4279 void Threads::remove(JavaThread* p) {
4280
4281 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4282 ObjectSynchronizer::omFlush(p);
4283
4284 // Extra scope needed for Thread_lock, so we can check
4285 // that we do not remove thread without safepoint code notice
4286 { MutexLocker ml(Threads_lock);
4287
4288 assert(includes(p), "p must be present");
4289
4290 JavaThread* current = _thread_list;
4291 JavaThread* prev = NULL;
4292
4293 while (current != p) {
4294 prev = current;
4295 current = current->next();
4296 }
4297
4298 if (prev) {
4299 prev->set_next(current->next());
4300 } else {
4301 _thread_list = p->next();
4302 }
4303 _number_of_threads--;
4304 oop threadObj = p->threadObj();
4305 bool daemon = true;
4306 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4307 _number_of_non_daemon_threads--;
4308 daemon = false;
4309
4310 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4311 // on destroy_vm will wake up.
4312 if (number_of_non_daemon_threads() == 1) {
4313 Threads_lock->notify_all();
4314 }
4315 }
4316 ThreadService::remove_thread(p, daemon);
4317
4318 // Make sure that safepoint code disregard this thread. This is needed since
4319 // the thread might mess around with locks after this point. This can cause it
4320 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4321 // of this thread since it is removed from the queue.
4322 p->set_terminated_value();
4323 } // unlock Threads_lock
4324
4325 // Since Events::log uses a lock, we grab it outside the Threads_lock
4326 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4327 }
4328
4329 // Threads_lock must be held when this is called (or must be called during a safepoint)
4330 bool Threads::includes(JavaThread* p) {
4331 assert(Threads_lock->is_locked(), "sanity check");
4332 ALL_JAVA_THREADS(q) {
4333 if (q == p) {
4334 return true;
4335 }
4336 }
4337 return false;
4338 }
4339
4340 // Operations on the Threads list for GC. These are not explicitly locked,
4341 // but the garbage collector must provide a safe context for them to run.
4342 // In particular, these things should never be called when the Threads_lock
4343 // is held by some other thread. (Note: the Safepoint abstraction also
4344 // uses the Threads_lock to guarantee this property. It also makes sure that
4345 // all threads gets blocked when exiting or starting).
4346
4347 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4348 ALL_JAVA_THREADS(p) {
4349 p->oops_do(f, cf);
4350 }
4351 VMThread::vm_thread()->oops_do(f, cf);
4352 }
4353
4354 void Threads::change_thread_claim_parity() {
4355 // Set the new claim parity.
4356 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4357 "Not in range.");
4358 _thread_claim_parity++;
4359 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4360 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4361 "Not in range.");
4362 }
4363
4364 #ifdef ASSERT
4365 void Threads::assert_all_threads_claimed() {
4366 ALL_JAVA_THREADS(p) {
4367 const int thread_parity = p->oops_do_parity();
4368 assert((thread_parity == _thread_claim_parity),
4369 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4370 }
4371 VMThread* vmt = VMThread::vm_thread();
4372 const int thread_parity = vmt->oops_do_parity();
4373 assert((thread_parity == _thread_claim_parity),
4374 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4375 }
4376 #endif // ASSERT
4377
4378 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4379 int cp = Threads::thread_claim_parity();
4380 ALL_JAVA_THREADS(p) {
4381 if (p->claim_oops_do(is_par, cp)) {
4382 p->oops_do(f, cf);
4383 }
4384 }
4385 VMThread* vmt = VMThread::vm_thread();
4386 if (vmt->claim_oops_do(is_par, cp)) {
4387 vmt->oops_do(f, cf);
4388 }
4389 }
4390
4391 #if INCLUDE_ALL_GCS
4392 // Used by ParallelScavenge
4393 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4394 ALL_JAVA_THREADS(p) {
4395 q->enqueue(new ThreadRootsTask(p));
4396 }
4397 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4398 }
4399
4400 // Used by Parallel Old
4401 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4402 ALL_JAVA_THREADS(p) {
4403 q->enqueue(new ThreadRootsMarkingTask(p));
4404 }
4405 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4406 }
4407 #endif // INCLUDE_ALL_GCS
4408
4409 void Threads::nmethods_do(CodeBlobClosure* cf) {
4410 ALL_JAVA_THREADS(p) {
4411 // This is used by the code cache sweeper to mark nmethods that are active
4412 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4413 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4414 if(!p->is_Code_cache_sweeper_thread()) {
4415 p->nmethods_do(cf);
4416 }
4417 }
4418 }
4419
4420 void Threads::metadata_do(void f(Metadata*)) {
4421 ALL_JAVA_THREADS(p) {
4422 p->metadata_do(f);
4423 }
4424 }
4425
4426 class ThreadHandlesClosure : public ThreadClosure {
4427 void (*_f)(Metadata*);
4428 public:
4429 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4430 virtual void do_thread(Thread* thread) {
4431 thread->metadata_handles_do(_f);
4432 }
4433 };
4434
4435 void Threads::metadata_handles_do(void f(Metadata*)) {
4436 // Only walk the Handles in Thread.
4437 ThreadHandlesClosure handles_closure(f);
4438 threads_do(&handles_closure);
4439 }
4440
4441 void Threads::deoptimized_wrt_marked_nmethods() {
4442 ALL_JAVA_THREADS(p) {
4443 p->deoptimized_wrt_marked_nmethods();
4444 }
4445 }
4446
4447
4448 // Get count Java threads that are waiting to enter the specified monitor.
4449 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4450 address monitor,
4451 bool doLock) {
4452 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4453 "must grab Threads_lock or be at safepoint");
4454 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4455
4456 int i = 0;
4457 {
4458 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4459 ALL_JAVA_THREADS(p) {
4460 if (!p->can_call_java()) continue;
4461
4462 address pending = (address)p->current_pending_monitor();
4463 if (pending == monitor) { // found a match
4464 if (i < count) result->append(p); // save the first count matches
4465 i++;
4466 }
4467 }
4468 }
4469 return result;
4470 }
4471
4472
4473 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4474 bool doLock) {
4475 assert(doLock ||
4476 Threads_lock->owned_by_self() ||
4477 SafepointSynchronize::is_at_safepoint(),
4478 "must grab Threads_lock or be at safepoint");
4479
4480 // NULL owner means not locked so we can skip the search
4481 if (owner == NULL) return NULL;
4482
4483 {
4484 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4485 ALL_JAVA_THREADS(p) {
4486 // first, see if owner is the address of a Java thread
4487 if (owner == (address)p) return p;
4488 }
4489 }
4490 // Cannot assert on lack of success here since this function may be
4491 // used by code that is trying to report useful problem information
4492 // like deadlock detection.
4493 if (UseHeavyMonitors) return NULL;
4494
4495 // If we didn't find a matching Java thread and we didn't force use of
4496 // heavyweight monitors, then the owner is the stack address of the
4497 // Lock Word in the owning Java thread's stack.
4498 //
4499 JavaThread* the_owner = NULL;
4500 {
4501 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4502 ALL_JAVA_THREADS(q) {
4503 if (q->is_lock_owned(owner)) {
4504 the_owner = q;
4505 break;
4506 }
4507 }
4508 }
4509 // cannot assert on lack of success here; see above comment
4510 return the_owner;
4511 }
4512
4513 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4514 void Threads::print_on(outputStream* st, bool print_stacks,
4515 bool internal_format, bool print_concurrent_locks) {
4516 char buf[32];
4517 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4518
4519 st->print_cr("Full thread dump %s (%s %s):",
4520 Abstract_VM_Version::vm_name(),
4521 Abstract_VM_Version::vm_release(),
4522 Abstract_VM_Version::vm_info_string());
4523 st->cr();
4524
4525 #if INCLUDE_SERVICES
4526 // Dump concurrent locks
4527 ConcurrentLocksDump concurrent_locks;
4528 if (print_concurrent_locks) {
4529 concurrent_locks.dump_at_safepoint();
4530 }
4531 #endif // INCLUDE_SERVICES
4532
4533 ALL_JAVA_THREADS(p) {
4534 ResourceMark rm;
4535 p->print_on(st);
4536 if (print_stacks) {
4537 if (internal_format) {
4538 p->trace_stack();
4539 } else {
4540 p->print_stack_on(st);
4541 }
4542 }
4543 st->cr();
4544 #if INCLUDE_SERVICES
4545 if (print_concurrent_locks) {
4546 concurrent_locks.print_locks_on(p, st);
4547 }
4548 #endif // INCLUDE_SERVICES
4549 }
4550
4551 VMThread::vm_thread()->print_on(st);
4552 st->cr();
4553 Universe::heap()->print_gc_threads_on(st);
4554 WatcherThread* wt = WatcherThread::watcher_thread();
4555 if (wt != NULL) {
4556 wt->print_on(st);
4557 st->cr();
4558 }
4559 st->flush();
4560 }
4561
4562 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4563 int buflen, bool* found_current) {
4564 if (this_thread != NULL) {
4565 bool is_current = (current == this_thread);
4566 *found_current = *found_current || is_current;
4567 st->print("%s", is_current ? "=>" : " ");
4568
4569 st->print(PTR_FORMAT, p2i(this_thread));
4570 st->print(" ");
4571 this_thread->print_on_error(st, buf, buflen);
4572 st->cr();
4573 }
4574 }
4575
4576 class PrintOnErrorClosure : public ThreadClosure {
4577 outputStream* _st;
4578 Thread* _current;
4579 char* _buf;
4580 int _buflen;
4581 bool* _found_current;
4582 public:
4583 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4584 int buflen, bool* found_current) :
4585 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4586
4587 virtual void do_thread(Thread* thread) {
4588 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4589 }
4590 };
4591
4592 // Threads::print_on_error() is called by fatal error handler. It's possible
4593 // that VM is not at safepoint and/or current thread is inside signal handler.
4594 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4595 // memory (even in resource area), it might deadlock the error handler.
4596 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4597 int buflen) {
4598 bool found_current = false;
4599 st->print_cr("Java Threads: ( => current thread )");
4600 ALL_JAVA_THREADS(thread) {
4601 print_on_error(thread, st, current, buf, buflen, &found_current);
4602 }
4603 st->cr();
4604
4605 st->print_cr("Other Threads:");
4606 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4607 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4608
4609 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4610 Universe::heap()->gc_threads_do(&print_closure);
4611
4612 if (!found_current) {
4613 st->cr();
4614 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4615 current->print_on_error(st, buf, buflen);
4616 st->cr();
4617 }
4618 st->cr();
4619 st->print_cr("Threads with active compile tasks:");
4620 print_threads_compiling(st, buf, buflen);
4621 }
4622
4623 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4624 ALL_JAVA_THREADS(thread) {
4625 if (thread->is_Compiler_thread()) {
4626 CompilerThread* ct = (CompilerThread*) thread;
4627 if (ct->task() != NULL) {
4628 thread->print_name_on_error(st, buf, buflen);
4629 ct->task()->print(st, NULL, true, true);
4630 }
4631 }
4632 }
4633 }
4634
4635
4636 // Internal SpinLock and Mutex
4637 // Based on ParkEvent
4638
4639 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4640 //
4641 // We employ SpinLocks _only for low-contention, fixed-length
4642 // short-duration critical sections where we're concerned
4643 // about native mutex_t or HotSpot Mutex:: latency.
4644 // The mux construct provides a spin-then-block mutual exclusion
4645 // mechanism.
4646 //
4647 // Testing has shown that contention on the ListLock guarding gFreeList
4648 // is common. If we implement ListLock as a simple SpinLock it's common
4649 // for the JVM to devolve to yielding with little progress. This is true
4650 // despite the fact that the critical sections protected by ListLock are
4651 // extremely short.
4652 //
4653 // TODO-FIXME: ListLock should be of type SpinLock.
4654 // We should make this a 1st-class type, integrated into the lock
4655 // hierarchy as leaf-locks. Critically, the SpinLock structure
4656 // should have sufficient padding to avoid false-sharing and excessive
4657 // cache-coherency traffic.
4658
4659
4660 typedef volatile int SpinLockT;
4661
4662 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4663 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4664 return; // normal fast-path return
4665 }
4666
4667 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4668 TEVENT(SpinAcquire - ctx);
4669 int ctr = 0;
4670 int Yields = 0;
4671 for (;;) {
4672 while (*adr != 0) {
4673 ++ctr;
4674 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4675 if (Yields > 5) {
4676 os::naked_short_sleep(1);
4677 } else {
4678 os::naked_yield();
4679 ++Yields;
4680 }
4681 } else {
4682 SpinPause();
4683 }
4684 }
4685 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4686 }
4687 }
4688
4689 void Thread::SpinRelease(volatile int * adr) {
4690 assert(*adr != 0, "invariant");
4691 OrderAccess::fence(); // guarantee at least release consistency.
4692 // Roach-motel semantics.
4693 // It's safe if subsequent LDs and STs float "up" into the critical section,
4694 // but prior LDs and STs within the critical section can't be allowed
4695 // to reorder or float past the ST that releases the lock.
4696 // Loads and stores in the critical section - which appear in program
4697 // order before the store that releases the lock - must also appear
4698 // before the store that releases the lock in memory visibility order.
4699 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4700 // the ST of 0 into the lock-word which releases the lock, so fence
4701 // more than covers this on all platforms.
4702 *adr = 0;
4703 }
4704
4705 // muxAcquire and muxRelease:
4706 //
4707 // * muxAcquire and muxRelease support a single-word lock-word construct.
4708 // The LSB of the word is set IFF the lock is held.
4709 // The remainder of the word points to the head of a singly-linked list
4710 // of threads blocked on the lock.
4711 //
4712 // * The current implementation of muxAcquire-muxRelease uses its own
4713 // dedicated Thread._MuxEvent instance. If we're interested in
4714 // minimizing the peak number of extant ParkEvent instances then
4715 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4716 // as certain invariants were satisfied. Specifically, care would need
4717 // to be taken with regards to consuming unpark() "permits".
4718 // A safe rule of thumb is that a thread would never call muxAcquire()
4719 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4720 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4721 // consume an unpark() permit intended for monitorenter, for instance.
4722 // One way around this would be to widen the restricted-range semaphore
4723 // implemented in park(). Another alternative would be to provide
4724 // multiple instances of the PlatformEvent() for each thread. One
4725 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4726 //
4727 // * Usage:
4728 // -- Only as leaf locks
4729 // -- for short-term locking only as muxAcquire does not perform
4730 // thread state transitions.
4731 //
4732 // Alternatives:
4733 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4734 // but with parking or spin-then-park instead of pure spinning.
4735 // * Use Taura-Oyama-Yonenzawa locks.
4736 // * It's possible to construct a 1-0 lock if we encode the lockword as
4737 // (List,LockByte). Acquire will CAS the full lockword while Release
4738 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4739 // acquiring threads use timers (ParkTimed) to detect and recover from
4740 // the stranding window. Thread/Node structures must be aligned on 256-byte
4741 // boundaries by using placement-new.
4742 // * Augment MCS with advisory back-link fields maintained with CAS().
4743 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4744 // The validity of the backlinks must be ratified before we trust the value.
4745 // If the backlinks are invalid the exiting thread must back-track through the
4746 // the forward links, which are always trustworthy.
4747 // * Add a successor indication. The LockWord is currently encoded as
4748 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4749 // to provide the usual futile-wakeup optimization.
4750 // See RTStt for details.
4751 // * Consider schedctl.sc_nopreempt to cover the critical section.
4752 //
4753
4754
4755 typedef volatile intptr_t MutexT; // Mux Lock-word
4756 enum MuxBits { LOCKBIT = 1 };
4757
4758 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4759 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4760 if (w == 0) return;
4761 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4762 return;
4763 }
4764
4765 TEVENT(muxAcquire - Contention);
4766 ParkEvent * const Self = Thread::current()->_MuxEvent;
4767 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4768 for (;;) {
4769 int its = (os::is_MP() ? 100 : 0) + 1;
4770
4771 // Optional spin phase: spin-then-park strategy
4772 while (--its >= 0) {
4773 w = *Lock;
4774 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4775 return;
4776 }
4777 }
4778
4779 Self->reset();
4780 Self->OnList = intptr_t(Lock);
4781 // The following fence() isn't _strictly necessary as the subsequent
4782 // CAS() both serializes execution and ratifies the fetched *Lock value.
4783 OrderAccess::fence();
4784 for (;;) {
4785 w = *Lock;
4786 if ((w & LOCKBIT) == 0) {
4787 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4788 Self->OnList = 0; // hygiene - allows stronger asserts
4789 return;
4790 }
4791 continue; // Interference -- *Lock changed -- Just retry
4792 }
4793 assert(w & LOCKBIT, "invariant");
4794 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4795 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4796 }
4797
4798 while (Self->OnList != 0) {
4799 Self->park();
4800 }
4801 }
4802 }
4803
4804 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4805 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4806 if (w == 0) return;
4807 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4808 return;
4809 }
4810
4811 TEVENT(muxAcquire - Contention);
4812 ParkEvent * ReleaseAfter = NULL;
4813 if (ev == NULL) {
4814 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4815 }
4816 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4817 for (;;) {
4818 guarantee(ev->OnList == 0, "invariant");
4819 int its = (os::is_MP() ? 100 : 0) + 1;
4820
4821 // Optional spin phase: spin-then-park strategy
4822 while (--its >= 0) {
4823 w = *Lock;
4824 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4825 if (ReleaseAfter != NULL) {
4826 ParkEvent::Release(ReleaseAfter);
4827 }
4828 return;
4829 }
4830 }
4831
4832 ev->reset();
4833 ev->OnList = intptr_t(Lock);
4834 // The following fence() isn't _strictly necessary as the subsequent
4835 // CAS() both serializes execution and ratifies the fetched *Lock value.
4836 OrderAccess::fence();
4837 for (;;) {
4838 w = *Lock;
4839 if ((w & LOCKBIT) == 0) {
4840 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4841 ev->OnList = 0;
4842 // We call ::Release while holding the outer lock, thus
4843 // artificially lengthening the critical section.
4844 // Consider deferring the ::Release() until the subsequent unlock(),
4845 // after we've dropped the outer lock.
4846 if (ReleaseAfter != NULL) {
4847 ParkEvent::Release(ReleaseAfter);
4848 }
4849 return;
4850 }
4851 continue; // Interference -- *Lock changed -- Just retry
4852 }
4853 assert(w & LOCKBIT, "invariant");
4854 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4855 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4856 }
4857
4858 while (ev->OnList != 0) {
4859 ev->park();
4860 }
4861 }
4862 }
4863
4864 // Release() must extract a successor from the list and then wake that thread.
4865 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4866 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4867 // Release() would :
4868 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4869 // (B) Extract a successor from the private list "in-hand"
4870 // (C) attempt to CAS() the residual back into *Lock over null.
4871 // If there were any newly arrived threads and the CAS() would fail.
4872 // In that case Release() would detach the RATs, re-merge the list in-hand
4873 // with the RATs and repeat as needed. Alternately, Release() might
4874 // detach and extract a successor, but then pass the residual list to the wakee.
4875 // The wakee would be responsible for reattaching and remerging before it
4876 // competed for the lock.
4877 //
4878 // Both "pop" and DMR are immune from ABA corruption -- there can be
4879 // multiple concurrent pushers, but only one popper or detacher.
4880 // This implementation pops from the head of the list. This is unfair,
4881 // but tends to provide excellent throughput as hot threads remain hot.
4882 // (We wake recently run threads first).
4883 //
4884 // All paths through muxRelease() will execute a CAS.
4885 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4886 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4887 // executed within the critical section are complete and globally visible before the
4888 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4889 void Thread::muxRelease(volatile intptr_t * Lock) {
4890 for (;;) {
4891 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4892 assert(w & LOCKBIT, "invariant");
4893 if (w == LOCKBIT) return;
4894 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4895 assert(List != NULL, "invariant");
4896 assert(List->OnList == intptr_t(Lock), "invariant");
4897 ParkEvent * const nxt = List->ListNext;
4898 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4899
4900 // The following CAS() releases the lock and pops the head element.
4901 // The CAS() also ratifies the previously fetched lock-word value.
4902 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4903 continue;
4904 }
4905 List->OnList = 0;
4906 OrderAccess::fence();
4907 List->unpark();
4908 return;
4909 }
4910 }
4911
4912
4913 void Threads::verify() {
4914 ALL_JAVA_THREADS(p) {
4915 p->verify();
4916 }
4917 VMThread* thread = VMThread::vm_thread();
4918 if (thread != NULL) thread->verify();
4919 }
4920
4921 void Threads::print_vt_buffer_stats_on(outputStream* st) {
4922 ALL_JAVA_THREADS(p) {
4923 p->print_vt_buffer_stats_on(st);
4924 }
4925 }