1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/scopeDesc.hpp"
33 #include "compiler/compileBroker.hpp"
34 #include "compiler/compileTask.hpp"
35 #include "gc/shared/gcId.hpp"
36 #include "gc/shared/gcLocker.inline.hpp"
37 #include "gc/shared/workgroup.hpp"
38 #include "interpreter/interpreter.hpp"
39 #include "interpreter/linkResolver.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "jvmtifiles/jvmtiEnv.hpp"
42 #include "logging/log.hpp"
43 #include "logging/logConfiguration.hpp"
44 #include "memory/metaspaceShared.hpp"
45 #include "memory/oopFactory.hpp"
46 #include "memory/resourceArea.hpp"
47 #include "memory/universe.inline.hpp"
48 #include "oops/instanceKlass.hpp"
49 #include "oops/objArrayOop.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/symbol.hpp"
52 #include "oops/verifyOopClosure.hpp"
53 #include "prims/jvm.h"
54 #include "prims/jvm_misc.hpp"
55 #include "prims/jvmtiExport.hpp"
56 #include "prims/jvmtiThreadState.hpp"
57 #include "prims/privilegedStack.hpp"
58 #include "runtime/arguments.hpp"
59 #include "runtime/atomic.hpp"
60 #include "runtime/biasedLocking.hpp"
61 #include "runtime/commandLineFlagConstraintList.hpp"
62 #include "runtime/commandLineFlagWriteableList.hpp"
63 #include "runtime/commandLineFlagRangeList.hpp"
64 #include "runtime/deoptimization.hpp"
65 #include "runtime/fprofiler.hpp"
66 #include "runtime/frame.inline.hpp"
67 #include "runtime/globals.hpp"
68 #include "runtime/init.hpp"
69 #include "runtime/interfaceSupport.hpp"
70 #include "runtime/java.hpp"
71 #include "runtime/javaCalls.hpp"
72 #include "runtime/jniPeriodicChecker.hpp"
73 #include "runtime/timerTrace.hpp"
74 #include "runtime/memprofiler.hpp"
75 #include "runtime/mutexLocker.hpp"
76 #include "runtime/objectMonitor.hpp"
77 #include "runtime/orderAccess.inline.hpp"
78 #include "runtime/osThread.hpp"
79 #include "runtime/safepoint.hpp"
80 #include "runtime/sharedRuntime.hpp"
81 #include "runtime/statSampler.hpp"
82 #include "runtime/stubRoutines.hpp"
83 #include "runtime/sweeper.hpp"
84 #include "runtime/task.hpp"
85 #include "runtime/thread.inline.hpp"
86 #include "runtime/threadCritical.hpp"
87 #include "runtime/vframe.hpp"
88 #include "runtime/vframeArray.hpp"
89 #include "runtime/vframe_hp.hpp"
90 #include "runtime/vmThread.hpp"
91 #include "runtime/vm_operations.hpp"
92 #include "runtime/vm_version.hpp"
93 #include "services/attachListener.hpp"
94 #include "services/management.hpp"
95 #include "services/memTracker.hpp"
96 #include "services/threadService.hpp"
97 #include "trace/traceMacros.hpp"
98 #include "trace/tracing.hpp"
99 #include "utilities/align.hpp"
100 #include "utilities/defaultStream.hpp"
101 #include "utilities/dtrace.hpp"
102 #include "utilities/events.hpp"
103 #include "utilities/macros.hpp"
104 #include "utilities/preserveException.hpp"
105 #include "utilities/vmError.hpp"
106 #if INCLUDE_ALL_GCS
107 #include "gc/cms/concurrentMarkSweepThread.hpp"
108 #include "gc/g1/concurrentMarkThread.inline.hpp"
109 #include "gc/parallel/pcTasks.hpp"
110 #endif // INCLUDE_ALL_GCS
111 #if INCLUDE_JVMCI
112 #include "jvmci/jvmciCompiler.hpp"
113 #include "jvmci/jvmciRuntime.hpp"
114 #endif
115 #ifdef COMPILER1
116 #include "c1/c1_Compiler.hpp"
117 #endif
118 #ifdef COMPILER2
119 #include "opto/c2compiler.hpp"
120 #include "opto/idealGraphPrinter.hpp"
121 #endif
122 #if INCLUDE_RTM_OPT
123 #include "runtime/rtmLocking.hpp"
124 #endif
125
126 // Initialization after module runtime initialization
127 void universe_post_module_init(); // must happen after call_initPhase2
128
129 #ifdef DTRACE_ENABLED
130
131 // Only bother with this argument setup if dtrace is available
132
133 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
134 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
135
136 #define DTRACE_THREAD_PROBE(probe, javathread) \
137 { \
138 ResourceMark rm(this); \
139 int len = 0; \
140 const char* name = (javathread)->get_thread_name(); \
141 len = strlen(name); \
142 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
143 (char *) name, len, \
144 java_lang_Thread::thread_id((javathread)->threadObj()), \
145 (uintptr_t) (javathread)->osthread()->thread_id(), \
146 java_lang_Thread::is_daemon((javathread)->threadObj())); \
147 }
148
149 #else // ndef DTRACE_ENABLED
150
151 #define DTRACE_THREAD_PROBE(probe, javathread)
152
153 #endif // ndef DTRACE_ENABLED
154
155 #ifndef USE_LIBRARY_BASED_TLS_ONLY
156 // Current thread is maintained as a thread-local variable
157 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
158 #endif
159 // Class hierarchy
160 // - Thread
161 // - VMThread
162 // - WatcherThread
163 // - ConcurrentMarkSweepThread
164 // - JavaThread
165 // - CompilerThread
166
167 // ======= Thread ========
168 // Support for forcing alignment of thread objects for biased locking
169 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
170 if (UseBiasedLocking) {
171 const int alignment = markOopDesc::biased_lock_alignment;
172 size_t aligned_size = size + (alignment - sizeof(intptr_t));
173 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
174 : AllocateHeap(aligned_size, flags, CURRENT_PC,
175 AllocFailStrategy::RETURN_NULL);
176 void* aligned_addr = align_up(real_malloc_addr, alignment);
177 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
178 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
179 "JavaThread alignment code overflowed allocated storage");
180 if (aligned_addr != real_malloc_addr) {
181 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
182 p2i(real_malloc_addr),
183 p2i(aligned_addr));
184 }
185 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
186 return aligned_addr;
187 } else {
188 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
189 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
190 }
191 }
192
193 void Thread::operator delete(void* p) {
194 if (UseBiasedLocking) {
195 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
196 FreeHeap(real_malloc_addr);
197 } else {
198 FreeHeap(p);
199 }
200 }
201
202
203 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
204 // JavaThread
205
206
207 Thread::Thread() {
208 // stack and get_thread
209 set_stack_base(NULL);
210 set_stack_size(0);
211 set_self_raw_id(0);
212 set_lgrp_id(-1);
213 DEBUG_ONLY(clear_suspendible_thread();)
214
215 // allocated data structures
216 set_osthread(NULL);
217 set_resource_area(new (mtThread)ResourceArea());
218 DEBUG_ONLY(_current_resource_mark = NULL;)
219 set_handle_area(new (mtThread) HandleArea(NULL));
220 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
221 set_active_handles(NULL);
222 set_free_handle_block(NULL);
223 set_last_handle_mark(NULL);
224
225 // This initial value ==> never claimed.
226 _oops_do_parity = 0;
227
228 // the handle mark links itself to last_handle_mark
229 new HandleMark(this);
230
231 // plain initialization
232 debug_only(_owned_locks = NULL;)
233 debug_only(_allow_allocation_count = 0;)
234 NOT_PRODUCT(_allow_safepoint_count = 0;)
235 NOT_PRODUCT(_skip_gcalot = false;)
236 _jvmti_env_iteration_count = 0;
237 set_allocated_bytes(0);
238 _vm_operation_started_count = 0;
239 _vm_operation_completed_count = 0;
240 _current_pending_monitor = NULL;
241 _current_pending_monitor_is_from_java = true;
242 _current_waiting_monitor = NULL;
243 _num_nested_signal = 0;
244 omFreeList = NULL;
245 omFreeCount = 0;
246 omFreeProvision = 32;
247 omInUseList = NULL;
248 omInUseCount = 0;
249
250 #ifdef ASSERT
251 _visited_for_critical_count = false;
252 #endif
253
254 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
255 Monitor::_safepoint_check_sometimes);
256 _suspend_flags = 0;
257
258 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
259 _hashStateX = os::random();
260 _hashStateY = 842502087;
261 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
262 _hashStateW = 273326509;
263
264 _OnTrap = 0;
265 _schedctl = NULL;
266 _Stalled = 0;
267 _TypeTag = 0x2BAD;
268
269 // Many of the following fields are effectively final - immutable
270 // Note that nascent threads can't use the Native Monitor-Mutex
271 // construct until the _MutexEvent is initialized ...
272 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
273 // we might instead use a stack of ParkEvents that we could provision on-demand.
274 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
275 // and ::Release()
276 _ParkEvent = ParkEvent::Allocate(this);
277 _SleepEvent = ParkEvent::Allocate(this);
278 _MutexEvent = ParkEvent::Allocate(this);
279 _MuxEvent = ParkEvent::Allocate(this);
280
281 #ifdef CHECK_UNHANDLED_OOPS
282 if (CheckUnhandledOops) {
283 _unhandled_oops = new UnhandledOops(this);
284 }
285 #endif // CHECK_UNHANDLED_OOPS
286 #ifdef ASSERT
287 if (UseBiasedLocking) {
288 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
289 assert(this == _real_malloc_address ||
290 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
291 "bug in forced alignment of thread objects");
292 }
293 #endif // ASSERT
294 }
295
296 void Thread::initialize_thread_current() {
297 #ifndef USE_LIBRARY_BASED_TLS_ONLY
298 assert(_thr_current == NULL, "Thread::current already initialized");
299 _thr_current = this;
300 #endif
301 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
302 ThreadLocalStorage::set_thread(this);
303 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
304 }
305
306 void Thread::clear_thread_current() {
307 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
308 #ifndef USE_LIBRARY_BASED_TLS_ONLY
309 _thr_current = NULL;
310 #endif
311 ThreadLocalStorage::set_thread(NULL);
312 }
313
314 void Thread::record_stack_base_and_size() {
315 set_stack_base(os::current_stack_base());
316 set_stack_size(os::current_stack_size());
317 // CR 7190089: on Solaris, primordial thread's stack is adjusted
318 // in initialize_thread(). Without the adjustment, stack size is
319 // incorrect if stack is set to unlimited (ulimit -s unlimited).
320 // So far, only Solaris has real implementation of initialize_thread().
321 //
322 // set up any platform-specific state.
323 os::initialize_thread(this);
324
325 // Set stack limits after thread is initialized.
326 if (is_Java_thread()) {
327 ((JavaThread*) this)->set_stack_overflow_limit();
328 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
329 }
330 #if INCLUDE_NMT
331 // record thread's native stack, stack grows downward
332 MemTracker::record_thread_stack(stack_end(), stack_size());
333 #endif // INCLUDE_NMT
334 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
335 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
336 os::current_thread_id(), p2i(stack_base() - stack_size()),
337 p2i(stack_base()), stack_size()/1024);
338 }
339
340
341 Thread::~Thread() {
342 EVENT_THREAD_DESTRUCT(this);
343
344 // stack_base can be NULL if the thread is never started or exited before
345 // record_stack_base_and_size called. Although, we would like to ensure
346 // that all started threads do call record_stack_base_and_size(), there is
347 // not proper way to enforce that.
348 #if INCLUDE_NMT
349 if (_stack_base != NULL) {
350 MemTracker::release_thread_stack(stack_end(), stack_size());
351 #ifdef ASSERT
352 set_stack_base(NULL);
353 #endif
354 }
355 #endif // INCLUDE_NMT
356
357 // deallocate data structures
358 delete resource_area();
359 // since the handle marks are using the handle area, we have to deallocated the root
360 // handle mark before deallocating the thread's handle area,
361 assert(last_handle_mark() != NULL, "check we have an element");
362 delete last_handle_mark();
363 assert(last_handle_mark() == NULL, "check we have reached the end");
364
365 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
366 // We NULL out the fields for good hygiene.
367 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
368 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
369 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
370 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
371
372 delete handle_area();
373 delete metadata_handles();
374
375 // SR_handler uses this as a termination indicator -
376 // needs to happen before os::free_thread()
377 delete _SR_lock;
378 _SR_lock = NULL;
379
380 // osthread() can be NULL, if creation of thread failed.
381 if (osthread() != NULL) os::free_thread(osthread());
382
383 // clear Thread::current if thread is deleting itself.
384 // Needed to ensure JNI correctly detects non-attached threads.
385 if (this == Thread::current()) {
386 clear_thread_current();
387 }
388
389 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
390 }
391
392 // NOTE: dummy function for assertion purpose.
393 void Thread::run() {
394 ShouldNotReachHere();
395 }
396
397 #ifdef ASSERT
398 // Private method to check for dangling thread pointer
399 void check_for_dangling_thread_pointer(Thread *thread) {
400 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
401 "possibility of dangling Thread pointer");
402 }
403 #endif
404
405 ThreadPriority Thread::get_priority(const Thread* const thread) {
406 ThreadPriority priority;
407 // Can return an error!
408 (void)os::get_priority(thread, priority);
409 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
410 return priority;
411 }
412
413 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
414 debug_only(check_for_dangling_thread_pointer(thread);)
415 // Can return an error!
416 (void)os::set_priority(thread, priority);
417 }
418
419
420 void Thread::start(Thread* thread) {
421 // Start is different from resume in that its safety is guaranteed by context or
422 // being called from a Java method synchronized on the Thread object.
423 if (!DisableStartThread) {
424 if (thread->is_Java_thread()) {
425 // Initialize the thread state to RUNNABLE before starting this thread.
426 // Can not set it after the thread started because we do not know the
427 // exact thread state at that time. It could be in MONITOR_WAIT or
428 // in SLEEPING or some other state.
429 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
430 java_lang_Thread::RUNNABLE);
431 }
432 os::start_thread(thread);
433 }
434 }
435
436 // Enqueue a VM_Operation to do the job for us - sometime later
437 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
438 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
439 VMThread::execute(vm_stop);
440 }
441
442
443 // Check if an external suspend request has completed (or has been
444 // cancelled). Returns true if the thread is externally suspended and
445 // false otherwise.
446 //
447 // The bits parameter returns information about the code path through
448 // the routine. Useful for debugging:
449 //
450 // set in is_ext_suspend_completed():
451 // 0x00000001 - routine was entered
452 // 0x00000010 - routine return false at end
453 // 0x00000100 - thread exited (return false)
454 // 0x00000200 - suspend request cancelled (return false)
455 // 0x00000400 - thread suspended (return true)
456 // 0x00001000 - thread is in a suspend equivalent state (return true)
457 // 0x00002000 - thread is native and walkable (return true)
458 // 0x00004000 - thread is native_trans and walkable (needed retry)
459 //
460 // set in wait_for_ext_suspend_completion():
461 // 0x00010000 - routine was entered
462 // 0x00020000 - suspend request cancelled before loop (return false)
463 // 0x00040000 - thread suspended before loop (return true)
464 // 0x00080000 - suspend request cancelled in loop (return false)
465 // 0x00100000 - thread suspended in loop (return true)
466 // 0x00200000 - suspend not completed during retry loop (return false)
467
468 // Helper class for tracing suspend wait debug bits.
469 //
470 // 0x00000100 indicates that the target thread exited before it could
471 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
472 // 0x00080000 each indicate a cancelled suspend request so they don't
473 // count as wait failures either.
474 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
475
476 class TraceSuspendDebugBits : public StackObj {
477 private:
478 JavaThread * jt;
479 bool is_wait;
480 bool called_by_wait; // meaningful when !is_wait
481 uint32_t * bits;
482
483 public:
484 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
485 uint32_t *_bits) {
486 jt = _jt;
487 is_wait = _is_wait;
488 called_by_wait = _called_by_wait;
489 bits = _bits;
490 }
491
492 ~TraceSuspendDebugBits() {
493 if (!is_wait) {
494 #if 1
495 // By default, don't trace bits for is_ext_suspend_completed() calls.
496 // That trace is very chatty.
497 return;
498 #else
499 if (!called_by_wait) {
500 // If tracing for is_ext_suspend_completed() is enabled, then only
501 // trace calls to it from wait_for_ext_suspend_completion()
502 return;
503 }
504 #endif
505 }
506
507 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
508 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
509 MutexLocker ml(Threads_lock); // needed for get_thread_name()
510 ResourceMark rm;
511
512 tty->print_cr(
513 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
514 jt->get_thread_name(), *bits);
515
516 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
517 }
518 }
519 }
520 };
521 #undef DEBUG_FALSE_BITS
522
523
524 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
525 uint32_t *bits) {
526 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
527
528 bool did_trans_retry = false; // only do thread_in_native_trans retry once
529 bool do_trans_retry; // flag to force the retry
530
531 *bits |= 0x00000001;
532
533 do {
534 do_trans_retry = false;
535
536 if (is_exiting()) {
537 // Thread is in the process of exiting. This is always checked
538 // first to reduce the risk of dereferencing a freed JavaThread.
539 *bits |= 0x00000100;
540 return false;
541 }
542
543 if (!is_external_suspend()) {
544 // Suspend request is cancelled. This is always checked before
545 // is_ext_suspended() to reduce the risk of a rogue resume
546 // confusing the thread that made the suspend request.
547 *bits |= 0x00000200;
548 return false;
549 }
550
551 if (is_ext_suspended()) {
552 // thread is suspended
553 *bits |= 0x00000400;
554 return true;
555 }
556
557 // Now that we no longer do hard suspends of threads running
558 // native code, the target thread can be changing thread state
559 // while we are in this routine:
560 //
561 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
562 //
563 // We save a copy of the thread state as observed at this moment
564 // and make our decision about suspend completeness based on the
565 // copy. This closes the race where the thread state is seen as
566 // _thread_in_native_trans in the if-thread_blocked check, but is
567 // seen as _thread_blocked in if-thread_in_native_trans check.
568 JavaThreadState save_state = thread_state();
569
570 if (save_state == _thread_blocked && is_suspend_equivalent()) {
571 // If the thread's state is _thread_blocked and this blocking
572 // condition is known to be equivalent to a suspend, then we can
573 // consider the thread to be externally suspended. This means that
574 // the code that sets _thread_blocked has been modified to do
575 // self-suspension if the blocking condition releases. We also
576 // used to check for CONDVAR_WAIT here, but that is now covered by
577 // the _thread_blocked with self-suspension check.
578 //
579 // Return true since we wouldn't be here unless there was still an
580 // external suspend request.
581 *bits |= 0x00001000;
582 return true;
583 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
584 // Threads running native code will self-suspend on native==>VM/Java
585 // transitions. If its stack is walkable (should always be the case
586 // unless this function is called before the actual java_suspend()
587 // call), then the wait is done.
588 *bits |= 0x00002000;
589 return true;
590 } else if (!called_by_wait && !did_trans_retry &&
591 save_state == _thread_in_native_trans &&
592 frame_anchor()->walkable()) {
593 // The thread is transitioning from thread_in_native to another
594 // thread state. check_safepoint_and_suspend_for_native_trans()
595 // will force the thread to self-suspend. If it hasn't gotten
596 // there yet we may have caught the thread in-between the native
597 // code check above and the self-suspend. Lucky us. If we were
598 // called by wait_for_ext_suspend_completion(), then it
599 // will be doing the retries so we don't have to.
600 //
601 // Since we use the saved thread state in the if-statement above,
602 // there is a chance that the thread has already transitioned to
603 // _thread_blocked by the time we get here. In that case, we will
604 // make a single unnecessary pass through the logic below. This
605 // doesn't hurt anything since we still do the trans retry.
606
607 *bits |= 0x00004000;
608
609 // Once the thread leaves thread_in_native_trans for another
610 // thread state, we break out of this retry loop. We shouldn't
611 // need this flag to prevent us from getting back here, but
612 // sometimes paranoia is good.
613 did_trans_retry = true;
614
615 // We wait for the thread to transition to a more usable state.
616 for (int i = 1; i <= SuspendRetryCount; i++) {
617 // We used to do an "os::yield_all(i)" call here with the intention
618 // that yielding would increase on each retry. However, the parameter
619 // is ignored on Linux which means the yield didn't scale up. Waiting
620 // on the SR_lock below provides a much more predictable scale up for
621 // the delay. It also provides a simple/direct point to check for any
622 // safepoint requests from the VMThread
623
624 // temporarily drops SR_lock while doing wait with safepoint check
625 // (if we're a JavaThread - the WatcherThread can also call this)
626 // and increase delay with each retry
627 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
628
629 // check the actual thread state instead of what we saved above
630 if (thread_state() != _thread_in_native_trans) {
631 // the thread has transitioned to another thread state so
632 // try all the checks (except this one) one more time.
633 do_trans_retry = true;
634 break;
635 }
636 } // end retry loop
637
638
639 }
640 } while (do_trans_retry);
641
642 *bits |= 0x00000010;
643 return false;
644 }
645
646 // Wait for an external suspend request to complete (or be cancelled).
647 // Returns true if the thread is externally suspended and false otherwise.
648 //
649 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
650 uint32_t *bits) {
651 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
652 false /* !called_by_wait */, bits);
653
654 // local flag copies to minimize SR_lock hold time
655 bool is_suspended;
656 bool pending;
657 uint32_t reset_bits;
658
659 // set a marker so is_ext_suspend_completed() knows we are the caller
660 *bits |= 0x00010000;
661
662 // We use reset_bits to reinitialize the bits value at the top of
663 // each retry loop. This allows the caller to make use of any
664 // unused bits for their own marking purposes.
665 reset_bits = *bits;
666
667 {
668 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
669 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
670 delay, bits);
671 pending = is_external_suspend();
672 }
673 // must release SR_lock to allow suspension to complete
674
675 if (!pending) {
676 // A cancelled suspend request is the only false return from
677 // is_ext_suspend_completed() that keeps us from entering the
678 // retry loop.
679 *bits |= 0x00020000;
680 return false;
681 }
682
683 if (is_suspended) {
684 *bits |= 0x00040000;
685 return true;
686 }
687
688 for (int i = 1; i <= retries; i++) {
689 *bits = reset_bits; // reinit to only track last retry
690
691 // We used to do an "os::yield_all(i)" call here with the intention
692 // that yielding would increase on each retry. However, the parameter
693 // is ignored on Linux which means the yield didn't scale up. Waiting
694 // on the SR_lock below provides a much more predictable scale up for
695 // the delay. It also provides a simple/direct point to check for any
696 // safepoint requests from the VMThread
697
698 {
699 MutexLocker ml(SR_lock());
700 // wait with safepoint check (if we're a JavaThread - the WatcherThread
701 // can also call this) and increase delay with each retry
702 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
703
704 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
705 delay, bits);
706
707 // It is possible for the external suspend request to be cancelled
708 // (by a resume) before the actual suspend operation is completed.
709 // Refresh our local copy to see if we still need to wait.
710 pending = is_external_suspend();
711 }
712
713 if (!pending) {
714 // A cancelled suspend request is the only false return from
715 // is_ext_suspend_completed() that keeps us from staying in the
716 // retry loop.
717 *bits |= 0x00080000;
718 return false;
719 }
720
721 if (is_suspended) {
722 *bits |= 0x00100000;
723 return true;
724 }
725 } // end retry loop
726
727 // thread did not suspend after all our retries
728 *bits |= 0x00200000;
729 return false;
730 }
731
732 #ifndef PRODUCT
733 void JavaThread::record_jump(address target, address instr, const char* file,
734 int line) {
735
736 // This should not need to be atomic as the only way for simultaneous
737 // updates is via interrupts. Even then this should be rare or non-existent
738 // and we don't care that much anyway.
739
740 int index = _jmp_ring_index;
741 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
742 _jmp_ring[index]._target = (intptr_t) target;
743 _jmp_ring[index]._instruction = (intptr_t) instr;
744 _jmp_ring[index]._file = file;
745 _jmp_ring[index]._line = line;
746 }
747 #endif // PRODUCT
748
749 // Called by flat profiler
750 // Callers have already called wait_for_ext_suspend_completion
751 // The assertion for that is currently too complex to put here:
752 bool JavaThread::profile_last_Java_frame(frame* _fr) {
753 bool gotframe = false;
754 // self suspension saves needed state.
755 if (has_last_Java_frame() && _anchor.walkable()) {
756 *_fr = pd_last_frame();
757 gotframe = true;
758 }
759 return gotframe;
760 }
761
762 void Thread::interrupt(Thread* thread) {
763 debug_only(check_for_dangling_thread_pointer(thread);)
764 os::interrupt(thread);
765 }
766
767 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
768 debug_only(check_for_dangling_thread_pointer(thread);)
769 // Note: If clear_interrupted==false, this simply fetches and
770 // returns the value of the field osthread()->interrupted().
771 return os::is_interrupted(thread, clear_interrupted);
772 }
773
774
775 // GC Support
776 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
777 jint thread_parity = _oops_do_parity;
778 if (thread_parity != strong_roots_parity) {
779 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
780 if (res == thread_parity) {
781 return true;
782 } else {
783 guarantee(res == strong_roots_parity, "Or else what?");
784 return false;
785 }
786 }
787 return false;
788 }
789
790 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
791 active_handles()->oops_do(f);
792 // Do oop for ThreadShadow
793 f->do_oop((oop*)&_pending_exception);
794 handle_area()->oops_do(f);
795
796 if (MonitorInUseLists) {
797 // When using thread local monitor lists, we scan them here,
798 // and the remaining global monitors in ObjectSynchronizer::oops_do().
799 ObjectSynchronizer::thread_local_used_oops_do(this, f);
800 }
801 }
802
803 void Thread::metadata_handles_do(void f(Metadata*)) {
804 // Only walk the Handles in Thread.
805 if (metadata_handles() != NULL) {
806 for (int i = 0; i< metadata_handles()->length(); i++) {
807 f(metadata_handles()->at(i));
808 }
809 }
810 }
811
812 void Thread::print_on(outputStream* st) const {
813 // get_priority assumes osthread initialized
814 if (osthread() != NULL) {
815 int os_prio;
816 if (os::get_native_priority(this, &os_prio) == OS_OK) {
817 st->print("os_prio=%d ", os_prio);
818 }
819 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
820 ext().print_on(st);
821 osthread()->print_on(st);
822 }
823 debug_only(if (WizardMode) print_owned_locks_on(st);)
824 }
825
826 // Thread::print_on_error() is called by fatal error handler. Don't use
827 // any lock or allocate memory.
828 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
829 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
830
831 if (is_VM_thread()) { st->print("VMThread"); }
832 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
833 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
834 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
835 else { st->print("Thread"); }
836
837 if (is_Named_thread()) {
838 st->print(" \"%s\"", name());
839 }
840
841 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
842 p2i(stack_end()), p2i(stack_base()));
843
844 if (osthread()) {
845 st->print(" [id=%d]", osthread()->thread_id());
846 }
847 }
848
849 #ifdef ASSERT
850 void Thread::print_owned_locks_on(outputStream* st) const {
851 Monitor *cur = _owned_locks;
852 if (cur == NULL) {
853 st->print(" (no locks) ");
854 } else {
855 st->print_cr(" Locks owned:");
856 while (cur) {
857 cur->print_on(st);
858 cur = cur->next();
859 }
860 }
861 }
862
863 static int ref_use_count = 0;
864
865 bool Thread::owns_locks_but_compiled_lock() const {
866 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
867 if (cur != Compile_lock) return true;
868 }
869 return false;
870 }
871
872
873 #endif
874
875 #ifndef PRODUCT
876
877 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
878 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
879 // no threads which allow_vm_block's are held
880 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
881 // Check if current thread is allowed to block at a safepoint
882 if (!(_allow_safepoint_count == 0)) {
883 fatal("Possible safepoint reached by thread that does not allow it");
884 }
885 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
886 fatal("LEAF method calling lock?");
887 }
888
889 #ifdef ASSERT
890 if (potential_vm_operation && is_Java_thread()
891 && !Universe::is_bootstrapping()) {
892 // Make sure we do not hold any locks that the VM thread also uses.
893 // This could potentially lead to deadlocks
894 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
895 // Threads_lock is special, since the safepoint synchronization will not start before this is
896 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
897 // since it is used to transfer control between JavaThreads and the VMThread
898 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
899 if ((cur->allow_vm_block() &&
900 cur != Threads_lock &&
901 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
902 cur != VMOperationRequest_lock &&
903 cur != VMOperationQueue_lock) ||
904 cur->rank() == Mutex::special) {
905 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
906 }
907 }
908 }
909
910 if (GCALotAtAllSafepoints) {
911 // We could enter a safepoint here and thus have a gc
912 InterfaceSupport::check_gc_alot();
913 }
914 #endif
915 }
916 #endif
917
918 bool Thread::is_in_stack(address adr) const {
919 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
920 address end = os::current_stack_pointer();
921 // Allow non Java threads to call this without stack_base
922 if (_stack_base == NULL) return true;
923 if (stack_base() >= adr && adr >= end) return true;
924
925 return false;
926 }
927
928 bool Thread::is_in_usable_stack(address adr) const {
929 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
930 size_t usable_stack_size = _stack_size - stack_guard_size;
931
932 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
933 }
934
935
936 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
937 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
938 // used for compilation in the future. If that change is made, the need for these methods
939 // should be revisited, and they should be removed if possible.
940
941 bool Thread::is_lock_owned(address adr) const {
942 return on_local_stack(adr);
943 }
944
945 bool Thread::set_as_starting_thread() {
946 // NOTE: this must be called inside the main thread.
947 return os::create_main_thread((JavaThread*)this);
948 }
949
950 static void initialize_class(Symbol* class_name, TRAPS) {
951 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
952 InstanceKlass::cast(klass)->initialize(CHECK);
953 }
954
955
956 // Creates the initial ThreadGroup
957 static Handle create_initial_thread_group(TRAPS) {
958 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
959 InstanceKlass* ik = InstanceKlass::cast(k);
960
961 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
962 {
963 JavaValue result(T_VOID);
964 JavaCalls::call_special(&result,
965 system_instance,
966 ik,
967 vmSymbols::object_initializer_name(),
968 vmSymbols::void_method_signature(),
969 CHECK_NH);
970 }
971 Universe::set_system_thread_group(system_instance());
972
973 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
974 {
975 JavaValue result(T_VOID);
976 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
977 JavaCalls::call_special(&result,
978 main_instance,
979 ik,
980 vmSymbols::object_initializer_name(),
981 vmSymbols::threadgroup_string_void_signature(),
982 system_instance,
983 string,
984 CHECK_NH);
985 }
986 return main_instance;
987 }
988
989 // Creates the initial Thread
990 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
991 TRAPS) {
992 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
993 InstanceKlass* ik = InstanceKlass::cast(k);
994 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
995
996 java_lang_Thread::set_thread(thread_oop(), thread);
997 java_lang_Thread::set_priority(thread_oop(), NormPriority);
998 thread->set_threadObj(thread_oop());
999
1000 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1001
1002 JavaValue result(T_VOID);
1003 JavaCalls::call_special(&result, thread_oop,
1004 ik,
1005 vmSymbols::object_initializer_name(),
1006 vmSymbols::threadgroup_string_void_signature(),
1007 thread_group,
1008 string,
1009 CHECK_NULL);
1010 return thread_oop();
1011 }
1012
1013 char java_runtime_name[128] = "";
1014 char java_runtime_version[128] = "";
1015
1016 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1017 static const char* get_java_runtime_name(TRAPS) {
1018 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1019 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1020 fieldDescriptor fd;
1021 bool found = k != NULL &&
1022 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1023 vmSymbols::string_signature(), &fd);
1024 if (found) {
1025 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1026 if (name_oop == NULL) {
1027 return NULL;
1028 }
1029 const char* name = java_lang_String::as_utf8_string(name_oop,
1030 java_runtime_name,
1031 sizeof(java_runtime_name));
1032 return name;
1033 } else {
1034 return NULL;
1035 }
1036 }
1037
1038 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1039 static const char* get_java_runtime_version(TRAPS) {
1040 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1041 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1042 fieldDescriptor fd;
1043 bool found = k != NULL &&
1044 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1045 vmSymbols::string_signature(), &fd);
1046 if (found) {
1047 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1048 if (name_oop == NULL) {
1049 return NULL;
1050 }
1051 const char* name = java_lang_String::as_utf8_string(name_oop,
1052 java_runtime_version,
1053 sizeof(java_runtime_version));
1054 return name;
1055 } else {
1056 return NULL;
1057 }
1058 }
1059
1060 // General purpose hook into Java code, run once when the VM is initialized.
1061 // The Java library method itself may be changed independently from the VM.
1062 static void call_postVMInitHook(TRAPS) {
1063 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1064 if (klass != NULL) {
1065 JavaValue result(T_VOID);
1066 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1067 vmSymbols::void_method_signature(),
1068 CHECK);
1069 }
1070 }
1071
1072 static void reset_vm_info_property(TRAPS) {
1073 // the vm info string
1074 ResourceMark rm(THREAD);
1075 const char *vm_info = VM_Version::vm_info_string();
1076
1077 // java.lang.System class
1078 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1079
1080 // setProperty arguments
1081 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1082 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1083
1084 // return value
1085 JavaValue r(T_OBJECT);
1086
1087 // public static String setProperty(String key, String value);
1088 JavaCalls::call_static(&r,
1089 klass,
1090 vmSymbols::setProperty_name(),
1091 vmSymbols::string_string_string_signature(),
1092 key_str,
1093 value_str,
1094 CHECK);
1095 }
1096
1097
1098 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1099 bool daemon, TRAPS) {
1100 assert(thread_group.not_null(), "thread group should be specified");
1101 assert(threadObj() == NULL, "should only create Java thread object once");
1102
1103 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1104 InstanceKlass* ik = InstanceKlass::cast(k);
1105 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1106
1107 java_lang_Thread::set_thread(thread_oop(), this);
1108 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1109 set_threadObj(thread_oop());
1110
1111 JavaValue result(T_VOID);
1112 if (thread_name != NULL) {
1113 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1114 // Thread gets assigned specified name and null target
1115 JavaCalls::call_special(&result,
1116 thread_oop,
1117 ik,
1118 vmSymbols::object_initializer_name(),
1119 vmSymbols::threadgroup_string_void_signature(),
1120 thread_group, // Argument 1
1121 name, // Argument 2
1122 THREAD);
1123 } else {
1124 // Thread gets assigned name "Thread-nnn" and null target
1125 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1126 JavaCalls::call_special(&result,
1127 thread_oop,
1128 ik,
1129 vmSymbols::object_initializer_name(),
1130 vmSymbols::threadgroup_runnable_void_signature(),
1131 thread_group, // Argument 1
1132 Handle(), // Argument 2
1133 THREAD);
1134 }
1135
1136
1137 if (daemon) {
1138 java_lang_Thread::set_daemon(thread_oop());
1139 }
1140
1141 if (HAS_PENDING_EXCEPTION) {
1142 return;
1143 }
1144
1145 Klass* group = SystemDictionary::ThreadGroup_klass();
1146 Handle threadObj(THREAD, this->threadObj());
1147
1148 JavaCalls::call_special(&result,
1149 thread_group,
1150 group,
1151 vmSymbols::add_method_name(),
1152 vmSymbols::thread_void_signature(),
1153 threadObj, // Arg 1
1154 THREAD);
1155 }
1156
1157 // NamedThread -- non-JavaThread subclasses with multiple
1158 // uniquely named instances should derive from this.
1159 NamedThread::NamedThread() : Thread() {
1160 _name = NULL;
1161 _processed_thread = NULL;
1162 _gc_id = GCId::undefined();
1163 }
1164
1165 NamedThread::~NamedThread() {
1166 if (_name != NULL) {
1167 FREE_C_HEAP_ARRAY(char, _name);
1168 _name = NULL;
1169 }
1170 }
1171
1172 void NamedThread::set_name(const char* format, ...) {
1173 guarantee(_name == NULL, "Only get to set name once.");
1174 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1175 guarantee(_name != NULL, "alloc failure");
1176 va_list ap;
1177 va_start(ap, format);
1178 jio_vsnprintf(_name, max_name_len, format, ap);
1179 va_end(ap);
1180 }
1181
1182 void NamedThread::initialize_named_thread() {
1183 set_native_thread_name(name());
1184 }
1185
1186 void NamedThread::print_on(outputStream* st) const {
1187 st->print("\"%s\" ", name());
1188 Thread::print_on(st);
1189 st->cr();
1190 }
1191
1192
1193 // ======= WatcherThread ========
1194
1195 // The watcher thread exists to simulate timer interrupts. It should
1196 // be replaced by an abstraction over whatever native support for
1197 // timer interrupts exists on the platform.
1198
1199 WatcherThread* WatcherThread::_watcher_thread = NULL;
1200 bool WatcherThread::_startable = false;
1201 volatile bool WatcherThread::_should_terminate = false;
1202
1203 WatcherThread::WatcherThread() : Thread() {
1204 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1205 if (os::create_thread(this, os::watcher_thread)) {
1206 _watcher_thread = this;
1207
1208 // Set the watcher thread to the highest OS priority which should not be
1209 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1210 // is created. The only normal thread using this priority is the reference
1211 // handler thread, which runs for very short intervals only.
1212 // If the VMThread's priority is not lower than the WatcherThread profiling
1213 // will be inaccurate.
1214 os::set_priority(this, MaxPriority);
1215 if (!DisableStartThread) {
1216 os::start_thread(this);
1217 }
1218 }
1219 }
1220
1221 int WatcherThread::sleep() const {
1222 // The WatcherThread does not participate in the safepoint protocol
1223 // for the PeriodicTask_lock because it is not a JavaThread.
1224 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1225
1226 if (_should_terminate) {
1227 // check for termination before we do any housekeeping or wait
1228 return 0; // we did not sleep.
1229 }
1230
1231 // remaining will be zero if there are no tasks,
1232 // causing the WatcherThread to sleep until a task is
1233 // enrolled
1234 int remaining = PeriodicTask::time_to_wait();
1235 int time_slept = 0;
1236
1237 // we expect this to timeout - we only ever get unparked when
1238 // we should terminate or when a new task has been enrolled
1239 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1240
1241 jlong time_before_loop = os::javaTimeNanos();
1242
1243 while (true) {
1244 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1245 remaining);
1246 jlong now = os::javaTimeNanos();
1247
1248 if (remaining == 0) {
1249 // if we didn't have any tasks we could have waited for a long time
1250 // consider the time_slept zero and reset time_before_loop
1251 time_slept = 0;
1252 time_before_loop = now;
1253 } else {
1254 // need to recalculate since we might have new tasks in _tasks
1255 time_slept = (int) ((now - time_before_loop) / 1000000);
1256 }
1257
1258 // Change to task list or spurious wakeup of some kind
1259 if (timedout || _should_terminate) {
1260 break;
1261 }
1262
1263 remaining = PeriodicTask::time_to_wait();
1264 if (remaining == 0) {
1265 // Last task was just disenrolled so loop around and wait until
1266 // another task gets enrolled
1267 continue;
1268 }
1269
1270 remaining -= time_slept;
1271 if (remaining <= 0) {
1272 break;
1273 }
1274 }
1275
1276 return time_slept;
1277 }
1278
1279 void WatcherThread::run() {
1280 assert(this == watcher_thread(), "just checking");
1281
1282 this->record_stack_base_and_size();
1283 this->set_native_thread_name(this->name());
1284 this->set_active_handles(JNIHandleBlock::allocate_block());
1285 while (true) {
1286 assert(watcher_thread() == Thread::current(), "thread consistency check");
1287 assert(watcher_thread() == this, "thread consistency check");
1288
1289 // Calculate how long it'll be until the next PeriodicTask work
1290 // should be done, and sleep that amount of time.
1291 int time_waited = sleep();
1292
1293 if (VMError::is_error_reported()) {
1294 // A fatal error has happened, the error handler(VMError::report_and_die)
1295 // should abort JVM after creating an error log file. However in some
1296 // rare cases, the error handler itself might deadlock. Here periodically
1297 // check for error reporting timeouts, and if it happens, just proceed to
1298 // abort the VM.
1299
1300 // This code is in WatcherThread because WatcherThread wakes up
1301 // periodically so the fatal error handler doesn't need to do anything;
1302 // also because the WatcherThread is less likely to crash than other
1303 // threads.
1304
1305 for (;;) {
1306 // Note: we use naked sleep in this loop because we want to avoid using
1307 // any kind of VM infrastructure which may be broken at this point.
1308 if (VMError::check_timeout()) {
1309 // We hit error reporting timeout. Error reporting was interrupted and
1310 // will be wrapping things up now (closing files etc). Give it some more
1311 // time, then quit the VM.
1312 os::naked_short_sleep(200);
1313 // Print a message to stderr.
1314 fdStream err(defaultStream::output_fd());
1315 err.print_raw_cr("# [ timer expired, abort... ]");
1316 // skip atexit/vm_exit/vm_abort hooks
1317 os::die();
1318 }
1319
1320 // Wait a second, then recheck for timeout.
1321 os::naked_short_sleep(999);
1322 }
1323 }
1324
1325 if (_should_terminate) {
1326 // check for termination before posting the next tick
1327 break;
1328 }
1329
1330 PeriodicTask::real_time_tick(time_waited);
1331 }
1332
1333 // Signal that it is terminated
1334 {
1335 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1336 _watcher_thread = NULL;
1337 Terminator_lock->notify();
1338 }
1339 }
1340
1341 void WatcherThread::start() {
1342 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1343
1344 if (watcher_thread() == NULL && _startable) {
1345 _should_terminate = false;
1346 // Create the single instance of WatcherThread
1347 new WatcherThread();
1348 }
1349 }
1350
1351 void WatcherThread::make_startable() {
1352 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1353 _startable = true;
1354 }
1355
1356 void WatcherThread::stop() {
1357 {
1358 // Follow normal safepoint aware lock enter protocol since the
1359 // WatcherThread is stopped by another JavaThread.
1360 MutexLocker ml(PeriodicTask_lock);
1361 _should_terminate = true;
1362
1363 WatcherThread* watcher = watcher_thread();
1364 if (watcher != NULL) {
1365 // unpark the WatcherThread so it can see that it should terminate
1366 watcher->unpark();
1367 }
1368 }
1369
1370 MutexLocker mu(Terminator_lock);
1371
1372 while (watcher_thread() != NULL) {
1373 // This wait should make safepoint checks, wait without a timeout,
1374 // and wait as a suspend-equivalent condition.
1375 //
1376 // Note: If the FlatProfiler is running, then this thread is waiting
1377 // for the WatcherThread to terminate and the WatcherThread, via the
1378 // FlatProfiler task, is waiting for the external suspend request on
1379 // this thread to complete. wait_for_ext_suspend_completion() will
1380 // eventually timeout, but that takes time. Making this wait a
1381 // suspend-equivalent condition solves that timeout problem.
1382 //
1383 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1384 Mutex::_as_suspend_equivalent_flag);
1385 }
1386 }
1387
1388 void WatcherThread::unpark() {
1389 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1390 PeriodicTask_lock->notify();
1391 }
1392
1393 void WatcherThread::print_on(outputStream* st) const {
1394 st->print("\"%s\" ", name());
1395 Thread::print_on(st);
1396 st->cr();
1397 }
1398
1399 // ======= JavaThread ========
1400
1401 #if INCLUDE_JVMCI
1402
1403 jlong* JavaThread::_jvmci_old_thread_counters;
1404
1405 bool jvmci_counters_include(JavaThread* thread) {
1406 oop threadObj = thread->threadObj();
1407 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1408 }
1409
1410 void JavaThread::collect_counters(typeArrayOop array) {
1411 if (JVMCICounterSize > 0) {
1412 MutexLocker tl(Threads_lock);
1413 for (int i = 0; i < array->length(); i++) {
1414 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1415 }
1416 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1417 if (jvmci_counters_include(tp)) {
1418 for (int i = 0; i < array->length(); i++) {
1419 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1420 }
1421 }
1422 }
1423 }
1424 }
1425
1426 #endif // INCLUDE_JVMCI
1427
1428 // A JavaThread is a normal Java thread
1429
1430 void JavaThread::initialize() {
1431 // Initialize fields
1432
1433 set_saved_exception_pc(NULL);
1434 set_threadObj(NULL);
1435 _anchor.clear();
1436 set_entry_point(NULL);
1437 set_jni_functions(jni_functions());
1438 set_callee_target(NULL);
1439 set_vm_result(NULL);
1440 set_vm_result_2(NULL);
1441 set_vframe_array_head(NULL);
1442 set_vframe_array_last(NULL);
1443 set_deferred_locals(NULL);
1444 set_deopt_mark(NULL);
1445 set_deopt_compiled_method(NULL);
1446 clear_must_deopt_id();
1447 set_monitor_chunks(NULL);
1448 set_next(NULL);
1449 set_thread_state(_thread_new);
1450 _terminated = _not_terminated;
1451 _privileged_stack_top = NULL;
1452 _array_for_gc = NULL;
1453 _suspend_equivalent = false;
1454 _in_deopt_handler = 0;
1455 _doing_unsafe_access = false;
1456 _stack_guard_state = stack_guard_unused;
1457 #if INCLUDE_JVMCI
1458 _pending_monitorenter = false;
1459 _pending_deoptimization = -1;
1460 _pending_failed_speculation = NULL;
1461 _pending_transfer_to_interpreter = false;
1462 _adjusting_comp_level = false;
1463 _jvmci._alternate_call_target = NULL;
1464 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1465 if (JVMCICounterSize > 0) {
1466 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1467 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1468 } else {
1469 _jvmci_counters = NULL;
1470 }
1471 #endif // INCLUDE_JVMCI
1472 _reserved_stack_activation = NULL; // stack base not known yet
1473 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1474 _exception_pc = 0;
1475 _exception_handler_pc = 0;
1476 _is_method_handle_return = 0;
1477 _jvmti_thread_state= NULL;
1478 _should_post_on_exceptions_flag = JNI_FALSE;
1479 _jvmti_get_loaded_classes_closure = NULL;
1480 _interp_only_mode = 0;
1481 _special_runtime_exit_condition = _no_async_condition;
1482 _pending_async_exception = NULL;
1483 _thread_stat = NULL;
1484 _thread_stat = new ThreadStatistics();
1485 _blocked_on_compilation = false;
1486 _jni_active_critical = 0;
1487 _pending_jni_exception_check_fn = NULL;
1488 _do_not_unlock_if_synchronized = false;
1489 _cached_monitor_info = NULL;
1490 _parker = Parker::Allocate(this);
1491
1492 #ifndef PRODUCT
1493 _jmp_ring_index = 0;
1494 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1495 record_jump(NULL, NULL, NULL, 0);
1496 }
1497 #endif // PRODUCT
1498
1499 set_thread_profiler(NULL);
1500 if (FlatProfiler::is_active()) {
1501 // This is where we would decide to either give each thread it's own profiler
1502 // or use one global one from FlatProfiler,
1503 // or up to some count of the number of profiled threads, etc.
1504 ThreadProfiler* pp = new ThreadProfiler();
1505 pp->engage();
1506 set_thread_profiler(pp);
1507 }
1508
1509 // Setup safepoint state info for this thread
1510 ThreadSafepointState::create(this);
1511
1512 debug_only(_java_call_counter = 0);
1513
1514 // JVMTI PopFrame support
1515 _popframe_condition = popframe_inactive;
1516 _popframe_preserved_args = NULL;
1517 _popframe_preserved_args_size = 0;
1518 _frames_to_pop_failed_realloc = 0;
1519
1520 pd_initialize();
1521 }
1522
1523 #if INCLUDE_ALL_GCS
1524 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1525 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1526 #endif // INCLUDE_ALL_GCS
1527
1528 JavaThread::JavaThread(bool is_attaching_via_jni) :
1529 Thread()
1530 #if INCLUDE_ALL_GCS
1531 , _satb_mark_queue(&_satb_mark_queue_set),
1532 _dirty_card_queue(&_dirty_card_queue_set)
1533 #endif // INCLUDE_ALL_GCS
1534 {
1535 initialize();
1536 if (is_attaching_via_jni) {
1537 _jni_attach_state = _attaching_via_jni;
1538 } else {
1539 _jni_attach_state = _not_attaching_via_jni;
1540 }
1541 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1542 }
1543
1544 bool JavaThread::reguard_stack(address cur_sp) {
1545 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1546 && _stack_guard_state != stack_guard_reserved_disabled) {
1547 return true; // Stack already guarded or guard pages not needed.
1548 }
1549
1550 if (register_stack_overflow()) {
1551 // For those architectures which have separate register and
1552 // memory stacks, we must check the register stack to see if
1553 // it has overflowed.
1554 return false;
1555 }
1556
1557 // Java code never executes within the yellow zone: the latter is only
1558 // there to provoke an exception during stack banging. If java code
1559 // is executing there, either StackShadowPages should be larger, or
1560 // some exception code in c1, c2 or the interpreter isn't unwinding
1561 // when it should.
1562 guarantee(cur_sp > stack_reserved_zone_base(),
1563 "not enough space to reguard - increase StackShadowPages");
1564 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1565 enable_stack_yellow_reserved_zone();
1566 if (reserved_stack_activation() != stack_base()) {
1567 set_reserved_stack_activation(stack_base());
1568 }
1569 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1570 set_reserved_stack_activation(stack_base());
1571 enable_stack_reserved_zone();
1572 }
1573 return true;
1574 }
1575
1576 bool JavaThread::reguard_stack(void) {
1577 return reguard_stack(os::current_stack_pointer());
1578 }
1579
1580
1581 void JavaThread::block_if_vm_exited() {
1582 if (_terminated == _vm_exited) {
1583 // _vm_exited is set at safepoint, and Threads_lock is never released
1584 // we will block here forever
1585 Threads_lock->lock_without_safepoint_check();
1586 ShouldNotReachHere();
1587 }
1588 }
1589
1590
1591 // Remove this ifdef when C1 is ported to the compiler interface.
1592 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1593 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1594
1595 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1596 Thread()
1597 #if INCLUDE_ALL_GCS
1598 , _satb_mark_queue(&_satb_mark_queue_set),
1599 _dirty_card_queue(&_dirty_card_queue_set)
1600 #endif // INCLUDE_ALL_GCS
1601 {
1602 initialize();
1603 _jni_attach_state = _not_attaching_via_jni;
1604 set_entry_point(entry_point);
1605 // Create the native thread itself.
1606 // %note runtime_23
1607 os::ThreadType thr_type = os::java_thread;
1608 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1609 os::java_thread;
1610 os::create_thread(this, thr_type, stack_sz);
1611 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1612 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1613 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1614 // the exception consists of creating the exception object & initializing it, initialization
1615 // will leave the VM via a JavaCall and then all locks must be unlocked).
1616 //
1617 // The thread is still suspended when we reach here. Thread must be explicit started
1618 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1619 // by calling Threads:add. The reason why this is not done here, is because the thread
1620 // object must be fully initialized (take a look at JVM_Start)
1621 }
1622
1623 JavaThread::~JavaThread() {
1624
1625 // JSR166 -- return the parker to the free list
1626 Parker::Release(_parker);
1627 _parker = NULL;
1628
1629 // Free any remaining previous UnrollBlock
1630 vframeArray* old_array = vframe_array_last();
1631
1632 if (old_array != NULL) {
1633 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1634 old_array->set_unroll_block(NULL);
1635 delete old_info;
1636 delete old_array;
1637 }
1638
1639 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1640 if (deferred != NULL) {
1641 // This can only happen if thread is destroyed before deoptimization occurs.
1642 assert(deferred->length() != 0, "empty array!");
1643 do {
1644 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1645 deferred->remove_at(0);
1646 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1647 delete dlv;
1648 } while (deferred->length() != 0);
1649 delete deferred;
1650 }
1651
1652 // All Java related clean up happens in exit
1653 ThreadSafepointState::destroy(this);
1654 if (_thread_profiler != NULL) delete _thread_profiler;
1655 if (_thread_stat != NULL) delete _thread_stat;
1656
1657 #if INCLUDE_JVMCI
1658 if (JVMCICounterSize > 0) {
1659 if (jvmci_counters_include(this)) {
1660 for (int i = 0; i < JVMCICounterSize; i++) {
1661 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1662 }
1663 }
1664 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1665 }
1666 #endif // INCLUDE_JVMCI
1667 }
1668
1669
1670 // The first routine called by a new Java thread
1671 void JavaThread::run() {
1672 // initialize thread-local alloc buffer related fields
1673 this->initialize_tlab();
1674
1675 // used to test validity of stack trace backs
1676 this->record_base_of_stack_pointer();
1677
1678 // Record real stack base and size.
1679 this->record_stack_base_and_size();
1680
1681 this->create_stack_guard_pages();
1682
1683 this->cache_global_variables();
1684
1685 // Thread is now sufficient initialized to be handled by the safepoint code as being
1686 // in the VM. Change thread state from _thread_new to _thread_in_vm
1687 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1688
1689 assert(JavaThread::current() == this, "sanity check");
1690 assert(!Thread::current()->owns_locks(), "sanity check");
1691
1692 DTRACE_THREAD_PROBE(start, this);
1693
1694 // This operation might block. We call that after all safepoint checks for a new thread has
1695 // been completed.
1696 this->set_active_handles(JNIHandleBlock::allocate_block());
1697
1698 if (JvmtiExport::should_post_thread_life()) {
1699 JvmtiExport::post_thread_start(this);
1700 }
1701
1702 EventThreadStart event;
1703 if (event.should_commit()) {
1704 event.set_thread(THREAD_TRACE_ID(this));
1705 event.commit();
1706 }
1707
1708 // We call another function to do the rest so we are sure that the stack addresses used
1709 // from there will be lower than the stack base just computed
1710 thread_main_inner();
1711
1712 // Note, thread is no longer valid at this point!
1713 }
1714
1715
1716 void JavaThread::thread_main_inner() {
1717 assert(JavaThread::current() == this, "sanity check");
1718 assert(this->threadObj() != NULL, "just checking");
1719
1720 // Execute thread entry point unless this thread has a pending exception
1721 // or has been stopped before starting.
1722 // Note: Due to JVM_StopThread we can have pending exceptions already!
1723 if (!this->has_pending_exception() &&
1724 !java_lang_Thread::is_stillborn(this->threadObj())) {
1725 {
1726 ResourceMark rm(this);
1727 this->set_native_thread_name(this->get_thread_name());
1728 }
1729 HandleMark hm(this);
1730 this->entry_point()(this, this);
1731 }
1732
1733 DTRACE_THREAD_PROBE(stop, this);
1734
1735 this->exit(false);
1736 delete this;
1737 }
1738
1739
1740 static void ensure_join(JavaThread* thread) {
1741 // We do not need to grap the Threads_lock, since we are operating on ourself.
1742 Handle threadObj(thread, thread->threadObj());
1743 assert(threadObj.not_null(), "java thread object must exist");
1744 ObjectLocker lock(threadObj, thread);
1745 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1746 thread->clear_pending_exception();
1747 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1748 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1749 // Clear the native thread instance - this makes isAlive return false and allows the join()
1750 // to complete once we've done the notify_all below
1751 java_lang_Thread::set_thread(threadObj(), NULL);
1752 lock.notify_all(thread);
1753 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1754 thread->clear_pending_exception();
1755 }
1756
1757
1758 // For any new cleanup additions, please check to see if they need to be applied to
1759 // cleanup_failed_attach_current_thread as well.
1760 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1761 assert(this == JavaThread::current(), "thread consistency check");
1762
1763 HandleMark hm(this);
1764 Handle uncaught_exception(this, this->pending_exception());
1765 this->clear_pending_exception();
1766 Handle threadObj(this, this->threadObj());
1767 assert(threadObj.not_null(), "Java thread object should be created");
1768
1769 if (get_thread_profiler() != NULL) {
1770 get_thread_profiler()->disengage();
1771 ResourceMark rm;
1772 get_thread_profiler()->print(get_thread_name());
1773 }
1774
1775
1776 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1777 {
1778 EXCEPTION_MARK;
1779
1780 CLEAR_PENDING_EXCEPTION;
1781 }
1782 if (!destroy_vm) {
1783 if (uncaught_exception.not_null()) {
1784 EXCEPTION_MARK;
1785 // Call method Thread.dispatchUncaughtException().
1786 Klass* thread_klass = SystemDictionary::Thread_klass();
1787 JavaValue result(T_VOID);
1788 JavaCalls::call_virtual(&result,
1789 threadObj, thread_klass,
1790 vmSymbols::dispatchUncaughtException_name(),
1791 vmSymbols::throwable_void_signature(),
1792 uncaught_exception,
1793 THREAD);
1794 if (HAS_PENDING_EXCEPTION) {
1795 ResourceMark rm(this);
1796 jio_fprintf(defaultStream::error_stream(),
1797 "\nException: %s thrown from the UncaughtExceptionHandler"
1798 " in thread \"%s\"\n",
1799 pending_exception()->klass()->external_name(),
1800 get_thread_name());
1801 CLEAR_PENDING_EXCEPTION;
1802 }
1803 }
1804
1805 // Called before the java thread exit since we want to read info
1806 // from java_lang_Thread object
1807 EventThreadEnd event;
1808 if (event.should_commit()) {
1809 event.set_thread(THREAD_TRACE_ID(this));
1810 event.commit();
1811 }
1812
1813 // Call after last event on thread
1814 EVENT_THREAD_EXIT(this);
1815
1816 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1817 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1818 // is deprecated anyhow.
1819 if (!is_Compiler_thread()) {
1820 int count = 3;
1821 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1822 EXCEPTION_MARK;
1823 JavaValue result(T_VOID);
1824 Klass* thread_klass = SystemDictionary::Thread_klass();
1825 JavaCalls::call_virtual(&result,
1826 threadObj, thread_klass,
1827 vmSymbols::exit_method_name(),
1828 vmSymbols::void_method_signature(),
1829 THREAD);
1830 CLEAR_PENDING_EXCEPTION;
1831 }
1832 }
1833 // notify JVMTI
1834 if (JvmtiExport::should_post_thread_life()) {
1835 JvmtiExport::post_thread_end(this);
1836 }
1837
1838 // We have notified the agents that we are exiting, before we go on,
1839 // we must check for a pending external suspend request and honor it
1840 // in order to not surprise the thread that made the suspend request.
1841 while (true) {
1842 {
1843 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1844 if (!is_external_suspend()) {
1845 set_terminated(_thread_exiting);
1846 ThreadService::current_thread_exiting(this);
1847 break;
1848 }
1849 // Implied else:
1850 // Things get a little tricky here. We have a pending external
1851 // suspend request, but we are holding the SR_lock so we
1852 // can't just self-suspend. So we temporarily drop the lock
1853 // and then self-suspend.
1854 }
1855
1856 ThreadBlockInVM tbivm(this);
1857 java_suspend_self();
1858
1859 // We're done with this suspend request, but we have to loop around
1860 // and check again. Eventually we will get SR_lock without a pending
1861 // external suspend request and will be able to mark ourselves as
1862 // exiting.
1863 }
1864 // no more external suspends are allowed at this point
1865 } else {
1866 // before_exit() has already posted JVMTI THREAD_END events
1867 }
1868
1869 // Notify waiters on thread object. This has to be done after exit() is called
1870 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1871 // group should have the destroyed bit set before waiters are notified).
1872 ensure_join(this);
1873 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1874
1875 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1876 // held by this thread must be released. The spec does not distinguish
1877 // between JNI-acquired and regular Java monitors. We can only see
1878 // regular Java monitors here if monitor enter-exit matching is broken.
1879 //
1880 // Optionally release any monitors for regular JavaThread exits. This
1881 // is provided as a work around for any bugs in monitor enter-exit
1882 // matching. This can be expensive so it is not enabled by default.
1883 //
1884 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1885 // ObjectSynchronizer::release_monitors_owned_by_thread().
1886 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1887 // Sanity check even though JNI DetachCurrentThread() would have
1888 // returned JNI_ERR if there was a Java frame. JavaThread exit
1889 // should be done executing Java code by the time we get here.
1890 assert(!this->has_last_Java_frame(),
1891 "should not have a Java frame when detaching or exiting");
1892 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1893 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1894 }
1895
1896 // These things needs to be done while we are still a Java Thread. Make sure that thread
1897 // is in a consistent state, in case GC happens
1898 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1899
1900 if (active_handles() != NULL) {
1901 JNIHandleBlock* block = active_handles();
1902 set_active_handles(NULL);
1903 JNIHandleBlock::release_block(block);
1904 }
1905
1906 if (free_handle_block() != NULL) {
1907 JNIHandleBlock* block = free_handle_block();
1908 set_free_handle_block(NULL);
1909 JNIHandleBlock::release_block(block);
1910 }
1911
1912 // These have to be removed while this is still a valid thread.
1913 remove_stack_guard_pages();
1914
1915 if (UseTLAB) {
1916 tlab().make_parsable(true); // retire TLAB
1917 }
1918
1919 if (JvmtiEnv::environments_might_exist()) {
1920 JvmtiExport::cleanup_thread(this);
1921 }
1922
1923 // We must flush any deferred card marks before removing a thread from
1924 // the list of active threads.
1925 Universe::heap()->flush_deferred_store_barrier(this);
1926 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1927
1928 #if INCLUDE_ALL_GCS
1929 // We must flush the G1-related buffers before removing a thread
1930 // from the list of active threads. We must do this after any deferred
1931 // card marks have been flushed (above) so that any entries that are
1932 // added to the thread's dirty card queue as a result are not lost.
1933 if (UseG1GC) {
1934 flush_barrier_queues();
1935 }
1936 #endif // INCLUDE_ALL_GCS
1937
1938 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1939 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1940 os::current_thread_id());
1941
1942 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1943 Threads::remove(this);
1944 }
1945
1946 #if INCLUDE_ALL_GCS
1947 // Flush G1-related queues.
1948 void JavaThread::flush_barrier_queues() {
1949 satb_mark_queue().flush();
1950 dirty_card_queue().flush();
1951 }
1952
1953 void JavaThread::initialize_queues() {
1954 assert(!SafepointSynchronize::is_at_safepoint(),
1955 "we should not be at a safepoint");
1956
1957 SATBMarkQueue& satb_queue = satb_mark_queue();
1958 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1959 // The SATB queue should have been constructed with its active
1960 // field set to false.
1961 assert(!satb_queue.is_active(), "SATB queue should not be active");
1962 assert(satb_queue.is_empty(), "SATB queue should be empty");
1963 // If we are creating the thread during a marking cycle, we should
1964 // set the active field of the SATB queue to true.
1965 if (satb_queue_set.is_active()) {
1966 satb_queue.set_active(true);
1967 }
1968
1969 DirtyCardQueue& dirty_queue = dirty_card_queue();
1970 // The dirty card queue should have been constructed with its
1971 // active field set to true.
1972 assert(dirty_queue.is_active(), "dirty card queue should be active");
1973 }
1974 #endif // INCLUDE_ALL_GCS
1975
1976 void JavaThread::cleanup_failed_attach_current_thread() {
1977 if (get_thread_profiler() != NULL) {
1978 get_thread_profiler()->disengage();
1979 ResourceMark rm;
1980 get_thread_profiler()->print(get_thread_name());
1981 }
1982
1983 if (active_handles() != NULL) {
1984 JNIHandleBlock* block = active_handles();
1985 set_active_handles(NULL);
1986 JNIHandleBlock::release_block(block);
1987 }
1988
1989 if (free_handle_block() != NULL) {
1990 JNIHandleBlock* block = free_handle_block();
1991 set_free_handle_block(NULL);
1992 JNIHandleBlock::release_block(block);
1993 }
1994
1995 // These have to be removed while this is still a valid thread.
1996 remove_stack_guard_pages();
1997
1998 if (UseTLAB) {
1999 tlab().make_parsable(true); // retire TLAB, if any
2000 }
2001
2002 #if INCLUDE_ALL_GCS
2003 if (UseG1GC) {
2004 flush_barrier_queues();
2005 }
2006 #endif // INCLUDE_ALL_GCS
2007
2008 Threads::remove(this);
2009 delete this;
2010 }
2011
2012
2013
2014
2015 JavaThread* JavaThread::active() {
2016 Thread* thread = Thread::current();
2017 if (thread->is_Java_thread()) {
2018 return (JavaThread*) thread;
2019 } else {
2020 assert(thread->is_VM_thread(), "this must be a vm thread");
2021 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2022 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2023 assert(ret->is_Java_thread(), "must be a Java thread");
2024 return ret;
2025 }
2026 }
2027
2028 bool JavaThread::is_lock_owned(address adr) const {
2029 if (Thread::is_lock_owned(adr)) return true;
2030
2031 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2032 if (chunk->contains(adr)) return true;
2033 }
2034
2035 return false;
2036 }
2037
2038
2039 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2040 chunk->set_next(monitor_chunks());
2041 set_monitor_chunks(chunk);
2042 }
2043
2044 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2045 guarantee(monitor_chunks() != NULL, "must be non empty");
2046 if (monitor_chunks() == chunk) {
2047 set_monitor_chunks(chunk->next());
2048 } else {
2049 MonitorChunk* prev = monitor_chunks();
2050 while (prev->next() != chunk) prev = prev->next();
2051 prev->set_next(chunk->next());
2052 }
2053 }
2054
2055 // JVM support.
2056
2057 // Note: this function shouldn't block if it's called in
2058 // _thread_in_native_trans state (such as from
2059 // check_special_condition_for_native_trans()).
2060 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2061
2062 if (has_last_Java_frame() && has_async_condition()) {
2063 // If we are at a polling page safepoint (not a poll return)
2064 // then we must defer async exception because live registers
2065 // will be clobbered by the exception path. Poll return is
2066 // ok because the call we a returning from already collides
2067 // with exception handling registers and so there is no issue.
2068 // (The exception handling path kills call result registers but
2069 // this is ok since the exception kills the result anyway).
2070
2071 if (is_at_poll_safepoint()) {
2072 // if the code we are returning to has deoptimized we must defer
2073 // the exception otherwise live registers get clobbered on the
2074 // exception path before deoptimization is able to retrieve them.
2075 //
2076 RegisterMap map(this, false);
2077 frame caller_fr = last_frame().sender(&map);
2078 assert(caller_fr.is_compiled_frame(), "what?");
2079 if (caller_fr.is_deoptimized_frame()) {
2080 log_info(exceptions)("deferred async exception at compiled safepoint");
2081 return;
2082 }
2083 }
2084 }
2085
2086 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2087 if (condition == _no_async_condition) {
2088 // Conditions have changed since has_special_runtime_exit_condition()
2089 // was called:
2090 // - if we were here only because of an external suspend request,
2091 // then that was taken care of above (or cancelled) so we are done
2092 // - if we were here because of another async request, then it has
2093 // been cleared between the has_special_runtime_exit_condition()
2094 // and now so again we are done
2095 return;
2096 }
2097
2098 // Check for pending async. exception
2099 if (_pending_async_exception != NULL) {
2100 // Only overwrite an already pending exception, if it is not a threadDeath.
2101 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2102
2103 // We cannot call Exceptions::_throw(...) here because we cannot block
2104 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2105
2106 if (log_is_enabled(Info, exceptions)) {
2107 ResourceMark rm;
2108 outputStream* logstream = Log(exceptions)::info_stream();
2109 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2110 if (has_last_Java_frame()) {
2111 frame f = last_frame();
2112 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2113 }
2114 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2115 }
2116 _pending_async_exception = NULL;
2117 clear_has_async_exception();
2118 }
2119 }
2120
2121 if (check_unsafe_error &&
2122 condition == _async_unsafe_access_error && !has_pending_exception()) {
2123 condition = _no_async_condition; // done
2124 switch (thread_state()) {
2125 case _thread_in_vm: {
2126 JavaThread* THREAD = this;
2127 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2128 }
2129 case _thread_in_native: {
2130 ThreadInVMfromNative tiv(this);
2131 JavaThread* THREAD = this;
2132 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2133 }
2134 case _thread_in_Java: {
2135 ThreadInVMfromJava tiv(this);
2136 JavaThread* THREAD = this;
2137 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2138 }
2139 default:
2140 ShouldNotReachHere();
2141 }
2142 }
2143
2144 assert(condition == _no_async_condition || has_pending_exception() ||
2145 (!check_unsafe_error && condition == _async_unsafe_access_error),
2146 "must have handled the async condition, if no exception");
2147 }
2148
2149 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2150 //
2151 // Check for pending external suspend. Internal suspend requests do
2152 // not use handle_special_runtime_exit_condition().
2153 // If JNIEnv proxies are allowed, don't self-suspend if the target
2154 // thread is not the current thread. In older versions of jdbx, jdbx
2155 // threads could call into the VM with another thread's JNIEnv so we
2156 // can be here operating on behalf of a suspended thread (4432884).
2157 bool do_self_suspend = is_external_suspend_with_lock();
2158 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2159 //
2160 // Because thread is external suspended the safepoint code will count
2161 // thread as at a safepoint. This can be odd because we can be here
2162 // as _thread_in_Java which would normally transition to _thread_blocked
2163 // at a safepoint. We would like to mark the thread as _thread_blocked
2164 // before calling java_suspend_self like all other callers of it but
2165 // we must then observe proper safepoint protocol. (We can't leave
2166 // _thread_blocked with a safepoint in progress). However we can be
2167 // here as _thread_in_native_trans so we can't use a normal transition
2168 // constructor/destructor pair because they assert on that type of
2169 // transition. We could do something like:
2170 //
2171 // JavaThreadState state = thread_state();
2172 // set_thread_state(_thread_in_vm);
2173 // {
2174 // ThreadBlockInVM tbivm(this);
2175 // java_suspend_self()
2176 // }
2177 // set_thread_state(_thread_in_vm_trans);
2178 // if (safepoint) block;
2179 // set_thread_state(state);
2180 //
2181 // but that is pretty messy. Instead we just go with the way the
2182 // code has worked before and note that this is the only path to
2183 // java_suspend_self that doesn't put the thread in _thread_blocked
2184 // mode.
2185
2186 frame_anchor()->make_walkable(this);
2187 java_suspend_self();
2188
2189 // We might be here for reasons in addition to the self-suspend request
2190 // so check for other async requests.
2191 }
2192
2193 if (check_asyncs) {
2194 check_and_handle_async_exceptions();
2195 }
2196 #if INCLUDE_TRACE
2197 if (is_trace_suspend()) {
2198 TRACE_SUSPEND_THREAD(this);
2199 }
2200 #endif
2201 }
2202
2203 void JavaThread::send_thread_stop(oop java_throwable) {
2204 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2205 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2206 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2207
2208 // Do not throw asynchronous exceptions against the compiler thread
2209 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2210 if (!can_call_java()) return;
2211
2212 {
2213 // Actually throw the Throwable against the target Thread - however
2214 // only if there is no thread death exception installed already.
2215 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2216 // If the topmost frame is a runtime stub, then we are calling into
2217 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2218 // must deoptimize the caller before continuing, as the compiled exception handler table
2219 // may not be valid
2220 if (has_last_Java_frame()) {
2221 frame f = last_frame();
2222 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2223 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2224 RegisterMap reg_map(this, UseBiasedLocking);
2225 frame compiled_frame = f.sender(®_map);
2226 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2227 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2228 }
2229 }
2230 }
2231
2232 // Set async. pending exception in thread.
2233 set_pending_async_exception(java_throwable);
2234
2235 if (log_is_enabled(Info, exceptions)) {
2236 ResourceMark rm;
2237 log_info(exceptions)("Pending Async. exception installed of type: %s",
2238 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2239 }
2240 // for AbortVMOnException flag
2241 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2242 }
2243 }
2244
2245
2246 // Interrupt thread so it will wake up from a potential wait()
2247 Thread::interrupt(this);
2248 }
2249
2250 // External suspension mechanism.
2251 //
2252 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2253 // to any VM_locks and it is at a transition
2254 // Self-suspension will happen on the transition out of the vm.
2255 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2256 //
2257 // Guarantees on return:
2258 // + Target thread will not execute any new bytecode (that's why we need to
2259 // force a safepoint)
2260 // + Target thread will not enter any new monitors
2261 //
2262 void JavaThread::java_suspend() {
2263 { MutexLocker mu(Threads_lock);
2264 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2265 return;
2266 }
2267 }
2268
2269 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2270 if (!is_external_suspend()) {
2271 // a racing resume has cancelled us; bail out now
2272 return;
2273 }
2274
2275 // suspend is done
2276 uint32_t debug_bits = 0;
2277 // Warning: is_ext_suspend_completed() may temporarily drop the
2278 // SR_lock to allow the thread to reach a stable thread state if
2279 // it is currently in a transient thread state.
2280 if (is_ext_suspend_completed(false /* !called_by_wait */,
2281 SuspendRetryDelay, &debug_bits)) {
2282 return;
2283 }
2284 }
2285
2286 VM_ThreadSuspend vm_suspend;
2287 VMThread::execute(&vm_suspend);
2288 }
2289
2290 // Part II of external suspension.
2291 // A JavaThread self suspends when it detects a pending external suspend
2292 // request. This is usually on transitions. It is also done in places
2293 // where continuing to the next transition would surprise the caller,
2294 // e.g., monitor entry.
2295 //
2296 // Returns the number of times that the thread self-suspended.
2297 //
2298 // Note: DO NOT call java_suspend_self() when you just want to block current
2299 // thread. java_suspend_self() is the second stage of cooperative
2300 // suspension for external suspend requests and should only be used
2301 // to complete an external suspend request.
2302 //
2303 int JavaThread::java_suspend_self() {
2304 int ret = 0;
2305
2306 // we are in the process of exiting so don't suspend
2307 if (is_exiting()) {
2308 clear_external_suspend();
2309 return ret;
2310 }
2311
2312 assert(_anchor.walkable() ||
2313 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2314 "must have walkable stack");
2315
2316 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2317
2318 assert(!this->is_ext_suspended(),
2319 "a thread trying to self-suspend should not already be suspended");
2320
2321 if (this->is_suspend_equivalent()) {
2322 // If we are self-suspending as a result of the lifting of a
2323 // suspend equivalent condition, then the suspend_equivalent
2324 // flag is not cleared until we set the ext_suspended flag so
2325 // that wait_for_ext_suspend_completion() returns consistent
2326 // results.
2327 this->clear_suspend_equivalent();
2328 }
2329
2330 // A racing resume may have cancelled us before we grabbed SR_lock
2331 // above. Or another external suspend request could be waiting for us
2332 // by the time we return from SR_lock()->wait(). The thread
2333 // that requested the suspension may already be trying to walk our
2334 // stack and if we return now, we can change the stack out from under
2335 // it. This would be a "bad thing (TM)" and cause the stack walker
2336 // to crash. We stay self-suspended until there are no more pending
2337 // external suspend requests.
2338 while (is_external_suspend()) {
2339 ret++;
2340 this->set_ext_suspended();
2341
2342 // _ext_suspended flag is cleared by java_resume()
2343 while (is_ext_suspended()) {
2344 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2345 }
2346 }
2347
2348 return ret;
2349 }
2350
2351 #ifdef ASSERT
2352 // verify the JavaThread has not yet been published in the Threads::list, and
2353 // hence doesn't need protection from concurrent access at this stage
2354 void JavaThread::verify_not_published() {
2355 if (!Threads_lock->owned_by_self()) {
2356 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2357 assert(!Threads::includes(this),
2358 "java thread shouldn't have been published yet!");
2359 } else {
2360 assert(!Threads::includes(this),
2361 "java thread shouldn't have been published yet!");
2362 }
2363 }
2364 #endif
2365
2366 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2367 // progress or when _suspend_flags is non-zero.
2368 // Current thread needs to self-suspend if there is a suspend request and/or
2369 // block if a safepoint is in progress.
2370 // Async exception ISN'T checked.
2371 // Note only the ThreadInVMfromNative transition can call this function
2372 // directly and when thread state is _thread_in_native_trans
2373 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2374 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2375
2376 JavaThread *curJT = JavaThread::current();
2377 bool do_self_suspend = thread->is_external_suspend();
2378
2379 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2380
2381 // If JNIEnv proxies are allowed, don't self-suspend if the target
2382 // thread is not the current thread. In older versions of jdbx, jdbx
2383 // threads could call into the VM with another thread's JNIEnv so we
2384 // can be here operating on behalf of a suspended thread (4432884).
2385 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2386 JavaThreadState state = thread->thread_state();
2387
2388 // We mark this thread_blocked state as a suspend-equivalent so
2389 // that a caller to is_ext_suspend_completed() won't be confused.
2390 // The suspend-equivalent state is cleared by java_suspend_self().
2391 thread->set_suspend_equivalent();
2392
2393 // If the safepoint code sees the _thread_in_native_trans state, it will
2394 // wait until the thread changes to other thread state. There is no
2395 // guarantee on how soon we can obtain the SR_lock and complete the
2396 // self-suspend request. It would be a bad idea to let safepoint wait for
2397 // too long. Temporarily change the state to _thread_blocked to
2398 // let the VM thread know that this thread is ready for GC. The problem
2399 // of changing thread state is that safepoint could happen just after
2400 // java_suspend_self() returns after being resumed, and VM thread will
2401 // see the _thread_blocked state. We must check for safepoint
2402 // after restoring the state and make sure we won't leave while a safepoint
2403 // is in progress.
2404 thread->set_thread_state(_thread_blocked);
2405 thread->java_suspend_self();
2406 thread->set_thread_state(state);
2407
2408 InterfaceSupport::serialize_thread_state_with_handler(thread);
2409 }
2410
2411 if (SafepointSynchronize::do_call_back()) {
2412 // If we are safepointing, then block the caller which may not be
2413 // the same as the target thread (see above).
2414 SafepointSynchronize::block(curJT);
2415 }
2416
2417 if (thread->is_deopt_suspend()) {
2418 thread->clear_deopt_suspend();
2419 RegisterMap map(thread, false);
2420 frame f = thread->last_frame();
2421 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2422 f = f.sender(&map);
2423 }
2424 if (f.id() == thread->must_deopt_id()) {
2425 thread->clear_must_deopt_id();
2426 f.deoptimize(thread);
2427 } else {
2428 fatal("missed deoptimization!");
2429 }
2430 }
2431 #if INCLUDE_TRACE
2432 if (thread->is_trace_suspend()) {
2433 TRACE_SUSPEND_THREAD(thread);
2434 }
2435 #endif
2436 }
2437
2438 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2439 // progress or when _suspend_flags is non-zero.
2440 // Current thread needs to self-suspend if there is a suspend request and/or
2441 // block if a safepoint is in progress.
2442 // Also check for pending async exception (not including unsafe access error).
2443 // Note only the native==>VM/Java barriers can call this function and when
2444 // thread state is _thread_in_native_trans.
2445 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2446 check_safepoint_and_suspend_for_native_trans(thread);
2447
2448 if (thread->has_async_exception()) {
2449 // We are in _thread_in_native_trans state, don't handle unsafe
2450 // access error since that may block.
2451 thread->check_and_handle_async_exceptions(false);
2452 }
2453 }
2454
2455 // This is a variant of the normal
2456 // check_special_condition_for_native_trans with slightly different
2457 // semantics for use by critical native wrappers. It does all the
2458 // normal checks but also performs the transition back into
2459 // thread_in_Java state. This is required so that critical natives
2460 // can potentially block and perform a GC if they are the last thread
2461 // exiting the GCLocker.
2462 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2463 check_special_condition_for_native_trans(thread);
2464
2465 // Finish the transition
2466 thread->set_thread_state(_thread_in_Java);
2467
2468 if (thread->do_critical_native_unlock()) {
2469 ThreadInVMfromJavaNoAsyncException tiv(thread);
2470 GCLocker::unlock_critical(thread);
2471 thread->clear_critical_native_unlock();
2472 }
2473 }
2474
2475 // We need to guarantee the Threads_lock here, since resumes are not
2476 // allowed during safepoint synchronization
2477 // Can only resume from an external suspension
2478 void JavaThread::java_resume() {
2479 assert_locked_or_safepoint(Threads_lock);
2480
2481 // Sanity check: thread is gone, has started exiting or the thread
2482 // was not externally suspended.
2483 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2484 return;
2485 }
2486
2487 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2488
2489 clear_external_suspend();
2490
2491 if (is_ext_suspended()) {
2492 clear_ext_suspended();
2493 SR_lock()->notify_all();
2494 }
2495 }
2496
2497 size_t JavaThread::_stack_red_zone_size = 0;
2498 size_t JavaThread::_stack_yellow_zone_size = 0;
2499 size_t JavaThread::_stack_reserved_zone_size = 0;
2500 size_t JavaThread::_stack_shadow_zone_size = 0;
2501
2502 void JavaThread::create_stack_guard_pages() {
2503 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2504 address low_addr = stack_end();
2505 size_t len = stack_guard_zone_size();
2506
2507 int must_commit = os::must_commit_stack_guard_pages();
2508 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2509
2510 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2511 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2512 return;
2513 }
2514
2515 if (os::guard_memory((char *) low_addr, len)) {
2516 _stack_guard_state = stack_guard_enabled;
2517 } else {
2518 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2519 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2520 if (os::uncommit_memory((char *) low_addr, len)) {
2521 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2522 }
2523 return;
2524 }
2525
2526 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2527 PTR_FORMAT "-" PTR_FORMAT ".",
2528 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2529 }
2530
2531 void JavaThread::remove_stack_guard_pages() {
2532 assert(Thread::current() == this, "from different thread");
2533 if (_stack_guard_state == stack_guard_unused) return;
2534 address low_addr = stack_end();
2535 size_t len = stack_guard_zone_size();
2536
2537 if (os::must_commit_stack_guard_pages()) {
2538 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2539 _stack_guard_state = stack_guard_unused;
2540 } else {
2541 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2542 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2543 return;
2544 }
2545 } else {
2546 if (_stack_guard_state == stack_guard_unused) return;
2547 if (os::unguard_memory((char *) low_addr, len)) {
2548 _stack_guard_state = stack_guard_unused;
2549 } else {
2550 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2551 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2552 return;
2553 }
2554 }
2555
2556 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2557 PTR_FORMAT "-" PTR_FORMAT ".",
2558 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2559 }
2560
2561 void JavaThread::enable_stack_reserved_zone() {
2562 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2563 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2564
2565 // The base notation is from the stack's point of view, growing downward.
2566 // We need to adjust it to work correctly with guard_memory()
2567 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2568
2569 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2570 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2571
2572 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2573 _stack_guard_state = stack_guard_enabled;
2574 } else {
2575 warning("Attempt to guard stack reserved zone failed.");
2576 }
2577 enable_register_stack_guard();
2578 }
2579
2580 void JavaThread::disable_stack_reserved_zone() {
2581 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2582 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2583
2584 // Simply return if called for a thread that does not use guard pages.
2585 if (_stack_guard_state == stack_guard_unused) return;
2586
2587 // The base notation is from the stack's point of view, growing downward.
2588 // We need to adjust it to work correctly with guard_memory()
2589 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2590
2591 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2592 _stack_guard_state = stack_guard_reserved_disabled;
2593 } else {
2594 warning("Attempt to unguard stack reserved zone failed.");
2595 }
2596 disable_register_stack_guard();
2597 }
2598
2599 void JavaThread::enable_stack_yellow_reserved_zone() {
2600 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2601 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2602
2603 // The base notation is from the stacks point of view, growing downward.
2604 // We need to adjust it to work correctly with guard_memory()
2605 address base = stack_red_zone_base();
2606
2607 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2608 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2609
2610 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2611 _stack_guard_state = stack_guard_enabled;
2612 } else {
2613 warning("Attempt to guard stack yellow zone failed.");
2614 }
2615 enable_register_stack_guard();
2616 }
2617
2618 void JavaThread::disable_stack_yellow_reserved_zone() {
2619 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2620 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2621
2622 // Simply return if called for a thread that does not use guard pages.
2623 if (_stack_guard_state == stack_guard_unused) return;
2624
2625 // The base notation is from the stacks point of view, growing downward.
2626 // We need to adjust it to work correctly with guard_memory()
2627 address base = stack_red_zone_base();
2628
2629 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2630 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2631 } else {
2632 warning("Attempt to unguard stack yellow zone failed.");
2633 }
2634 disable_register_stack_guard();
2635 }
2636
2637 void JavaThread::enable_stack_red_zone() {
2638 // The base notation is from the stacks point of view, growing downward.
2639 // We need to adjust it to work correctly with guard_memory()
2640 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2641 address base = stack_red_zone_base() - stack_red_zone_size();
2642
2643 guarantee(base < stack_base(), "Error calculating stack red zone");
2644 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2645
2646 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2647 warning("Attempt to guard stack red zone failed.");
2648 }
2649 }
2650
2651 void JavaThread::disable_stack_red_zone() {
2652 // The base notation is from the stacks point of view, growing downward.
2653 // We need to adjust it to work correctly with guard_memory()
2654 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2655 address base = stack_red_zone_base() - stack_red_zone_size();
2656 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2657 warning("Attempt to unguard stack red zone failed.");
2658 }
2659 }
2660
2661 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2662 // ignore is there is no stack
2663 if (!has_last_Java_frame()) return;
2664 // traverse the stack frames. Starts from top frame.
2665 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2666 frame* fr = fst.current();
2667 f(fr, fst.register_map());
2668 }
2669 }
2670
2671
2672 #ifndef PRODUCT
2673 // Deoptimization
2674 // Function for testing deoptimization
2675 void JavaThread::deoptimize() {
2676 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2677 StackFrameStream fst(this, UseBiasedLocking);
2678 bool deopt = false; // Dump stack only if a deopt actually happens.
2679 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2680 // Iterate over all frames in the thread and deoptimize
2681 for (; !fst.is_done(); fst.next()) {
2682 if (fst.current()->can_be_deoptimized()) {
2683
2684 if (only_at) {
2685 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2686 // consists of comma or carriage return separated numbers so
2687 // search for the current bci in that string.
2688 address pc = fst.current()->pc();
2689 nmethod* nm = (nmethod*) fst.current()->cb();
2690 ScopeDesc* sd = nm->scope_desc_at(pc);
2691 char buffer[8];
2692 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2693 size_t len = strlen(buffer);
2694 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2695 while (found != NULL) {
2696 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2697 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2698 // Check that the bci found is bracketed by terminators.
2699 break;
2700 }
2701 found = strstr(found + 1, buffer);
2702 }
2703 if (!found) {
2704 continue;
2705 }
2706 }
2707
2708 if (DebugDeoptimization && !deopt) {
2709 deopt = true; // One-time only print before deopt
2710 tty->print_cr("[BEFORE Deoptimization]");
2711 trace_frames();
2712 trace_stack();
2713 }
2714 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2715 }
2716 }
2717
2718 if (DebugDeoptimization && deopt) {
2719 tty->print_cr("[AFTER Deoptimization]");
2720 trace_frames();
2721 }
2722 }
2723
2724
2725 // Make zombies
2726 void JavaThread::make_zombies() {
2727 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2728 if (fst.current()->can_be_deoptimized()) {
2729 // it is a Java nmethod
2730 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2731 nm->make_not_entrant();
2732 }
2733 }
2734 }
2735 #endif // PRODUCT
2736
2737
2738 void JavaThread::deoptimized_wrt_marked_nmethods() {
2739 if (!has_last_Java_frame()) return;
2740 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2741 StackFrameStream fst(this, UseBiasedLocking);
2742 for (; !fst.is_done(); fst.next()) {
2743 if (fst.current()->should_be_deoptimized()) {
2744 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2745 }
2746 }
2747 }
2748
2749
2750 // If the caller is a NamedThread, then remember, in the current scope,
2751 // the given JavaThread in its _processed_thread field.
2752 class RememberProcessedThread: public StackObj {
2753 NamedThread* _cur_thr;
2754 public:
2755 RememberProcessedThread(JavaThread* jthr) {
2756 Thread* thread = Thread::current();
2757 if (thread->is_Named_thread()) {
2758 _cur_thr = (NamedThread *)thread;
2759 _cur_thr->set_processed_thread(jthr);
2760 } else {
2761 _cur_thr = NULL;
2762 }
2763 }
2764
2765 ~RememberProcessedThread() {
2766 if (_cur_thr) {
2767 _cur_thr->set_processed_thread(NULL);
2768 }
2769 }
2770 };
2771
2772 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2773 // Verify that the deferred card marks have been flushed.
2774 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2775
2776 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2777 // since there may be more than one thread using each ThreadProfiler.
2778
2779 // Traverse the GCHandles
2780 Thread::oops_do(f, cf);
2781
2782 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2783
2784 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2785 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2786
2787 if (has_last_Java_frame()) {
2788 // Record JavaThread to GC thread
2789 RememberProcessedThread rpt(this);
2790
2791 // Traverse the privileged stack
2792 if (_privileged_stack_top != NULL) {
2793 _privileged_stack_top->oops_do(f);
2794 }
2795
2796 // traverse the registered growable array
2797 if (_array_for_gc != NULL) {
2798 for (int index = 0; index < _array_for_gc->length(); index++) {
2799 f->do_oop(_array_for_gc->adr_at(index));
2800 }
2801 }
2802
2803 // Traverse the monitor chunks
2804 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2805 chunk->oops_do(f);
2806 }
2807
2808 // Traverse the execution stack
2809 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2810 fst.current()->oops_do(f, cf, fst.register_map());
2811 }
2812 }
2813
2814 // callee_target is never live across a gc point so NULL it here should
2815 // it still contain a methdOop.
2816
2817 set_callee_target(NULL);
2818
2819 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2820 // If we have deferred set_locals there might be oops waiting to be
2821 // written
2822 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2823 if (list != NULL) {
2824 for (int i = 0; i < list->length(); i++) {
2825 list->at(i)->oops_do(f);
2826 }
2827 }
2828
2829 // Traverse instance variables at the end since the GC may be moving things
2830 // around using this function
2831 f->do_oop((oop*) &_threadObj);
2832 f->do_oop((oop*) &_vm_result);
2833 f->do_oop((oop*) &_exception_oop);
2834 f->do_oop((oop*) &_pending_async_exception);
2835
2836 if (jvmti_thread_state() != NULL) {
2837 jvmti_thread_state()->oops_do(f);
2838 }
2839 }
2840
2841 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2842 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2843 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2844
2845 if (has_last_Java_frame()) {
2846 // Traverse the execution stack
2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2848 fst.current()->nmethods_do(cf);
2849 }
2850 }
2851 }
2852
2853 void JavaThread::metadata_do(void f(Metadata*)) {
2854 if (has_last_Java_frame()) {
2855 // Traverse the execution stack to call f() on the methods in the stack
2856 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2857 fst.current()->metadata_do(f);
2858 }
2859 } else if (is_Compiler_thread()) {
2860 // need to walk ciMetadata in current compile tasks to keep alive.
2861 CompilerThread* ct = (CompilerThread*)this;
2862 if (ct->env() != NULL) {
2863 ct->env()->metadata_do(f);
2864 }
2865 if (ct->task() != NULL) {
2866 ct->task()->metadata_do(f);
2867 }
2868 }
2869 }
2870
2871 // Printing
2872 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2873 switch (_thread_state) {
2874 case _thread_uninitialized: return "_thread_uninitialized";
2875 case _thread_new: return "_thread_new";
2876 case _thread_new_trans: return "_thread_new_trans";
2877 case _thread_in_native: return "_thread_in_native";
2878 case _thread_in_native_trans: return "_thread_in_native_trans";
2879 case _thread_in_vm: return "_thread_in_vm";
2880 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2881 case _thread_in_Java: return "_thread_in_Java";
2882 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2883 case _thread_blocked: return "_thread_blocked";
2884 case _thread_blocked_trans: return "_thread_blocked_trans";
2885 default: return "unknown thread state";
2886 }
2887 }
2888
2889 #ifndef PRODUCT
2890 void JavaThread::print_thread_state_on(outputStream *st) const {
2891 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2892 };
2893 void JavaThread::print_thread_state() const {
2894 print_thread_state_on(tty);
2895 }
2896 #endif // PRODUCT
2897
2898 // Called by Threads::print() for VM_PrintThreads operation
2899 void JavaThread::print_on(outputStream *st) const {
2900 st->print_raw("\"");
2901 st->print_raw(get_thread_name());
2902 st->print_raw("\" ");
2903 oop thread_oop = threadObj();
2904 if (thread_oop != NULL) {
2905 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2906 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2907 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2908 }
2909 Thread::print_on(st);
2910 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2911 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2912 if (thread_oop != NULL) {
2913 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2914 }
2915 #ifndef PRODUCT
2916 print_thread_state_on(st);
2917 _safepoint_state->print_on(st);
2918 #endif // PRODUCT
2919 if (is_Compiler_thread()) {
2920 CompilerThread* ct = (CompilerThread*)this;
2921 if (ct->task() != NULL) {
2922 st->print(" Compiling: ");
2923 ct->task()->print(st, NULL, true, false);
2924 } else {
2925 st->print(" No compile task");
2926 }
2927 st->cr();
2928 }
2929 }
2930
2931 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2932 st->print("%s", get_thread_name_string(buf, buflen));
2933 }
2934
2935 // Called by fatal error handler. The difference between this and
2936 // JavaThread::print() is that we can't grab lock or allocate memory.
2937 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2938 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2939 oop thread_obj = threadObj();
2940 if (thread_obj != NULL) {
2941 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2942 }
2943 st->print(" [");
2944 st->print("%s", _get_thread_state_name(_thread_state));
2945 if (osthread()) {
2946 st->print(", id=%d", osthread()->thread_id());
2947 }
2948 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2949 p2i(stack_end()), p2i(stack_base()));
2950 st->print("]");
2951 return;
2952 }
2953
2954 // Verification
2955
2956 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2957
2958 void JavaThread::verify() {
2959 // Verify oops in the thread.
2960 oops_do(&VerifyOopClosure::verify_oop, NULL);
2961
2962 // Verify the stack frames.
2963 frames_do(frame_verify);
2964 }
2965
2966 // CR 6300358 (sub-CR 2137150)
2967 // Most callers of this method assume that it can't return NULL but a
2968 // thread may not have a name whilst it is in the process of attaching to
2969 // the VM - see CR 6412693, and there are places where a JavaThread can be
2970 // seen prior to having it's threadObj set (eg JNI attaching threads and
2971 // if vm exit occurs during initialization). These cases can all be accounted
2972 // for such that this method never returns NULL.
2973 const char* JavaThread::get_thread_name() const {
2974 #ifdef ASSERT
2975 // early safepoints can hit while current thread does not yet have TLS
2976 if (!SafepointSynchronize::is_at_safepoint()) {
2977 Thread *cur = Thread::current();
2978 if (!(cur->is_Java_thread() && cur == this)) {
2979 // Current JavaThreads are allowed to get their own name without
2980 // the Threads_lock.
2981 assert_locked_or_safepoint(Threads_lock);
2982 }
2983 }
2984 #endif // ASSERT
2985 return get_thread_name_string();
2986 }
2987
2988 // Returns a non-NULL representation of this thread's name, or a suitable
2989 // descriptive string if there is no set name
2990 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2991 const char* name_str;
2992 oop thread_obj = threadObj();
2993 if (thread_obj != NULL) {
2994 oop name = java_lang_Thread::name(thread_obj);
2995 if (name != NULL) {
2996 if (buf == NULL) {
2997 name_str = java_lang_String::as_utf8_string(name);
2998 } else {
2999 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3000 }
3001 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3002 name_str = "<no-name - thread is attaching>";
3003 } else {
3004 name_str = Thread::name();
3005 }
3006 } else {
3007 name_str = Thread::name();
3008 }
3009 assert(name_str != NULL, "unexpected NULL thread name");
3010 return name_str;
3011 }
3012
3013
3014 const char* JavaThread::get_threadgroup_name() const {
3015 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3016 oop thread_obj = threadObj();
3017 if (thread_obj != NULL) {
3018 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3019 if (thread_group != NULL) {
3020 // ThreadGroup.name can be null
3021 return java_lang_ThreadGroup::name(thread_group);
3022 }
3023 }
3024 return NULL;
3025 }
3026
3027 const char* JavaThread::get_parent_name() const {
3028 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3029 oop thread_obj = threadObj();
3030 if (thread_obj != NULL) {
3031 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3032 if (thread_group != NULL) {
3033 oop parent = java_lang_ThreadGroup::parent(thread_group);
3034 if (parent != NULL) {
3035 // ThreadGroup.name can be null
3036 return java_lang_ThreadGroup::name(parent);
3037 }
3038 }
3039 }
3040 return NULL;
3041 }
3042
3043 ThreadPriority JavaThread::java_priority() const {
3044 oop thr_oop = threadObj();
3045 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3046 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3047 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3048 return priority;
3049 }
3050
3051 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3052
3053 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3054 // Link Java Thread object <-> C++ Thread
3055
3056 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3057 // and put it into a new Handle. The Handle "thread_oop" can then
3058 // be used to pass the C++ thread object to other methods.
3059
3060 // Set the Java level thread object (jthread) field of the
3061 // new thread (a JavaThread *) to C++ thread object using the
3062 // "thread_oop" handle.
3063
3064 // Set the thread field (a JavaThread *) of the
3065 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3066
3067 Handle thread_oop(Thread::current(),
3068 JNIHandles::resolve_non_null(jni_thread));
3069 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3070 "must be initialized");
3071 set_threadObj(thread_oop());
3072 java_lang_Thread::set_thread(thread_oop(), this);
3073
3074 if (prio == NoPriority) {
3075 prio = java_lang_Thread::priority(thread_oop());
3076 assert(prio != NoPriority, "A valid priority should be present");
3077 }
3078
3079 // Push the Java priority down to the native thread; needs Threads_lock
3080 Thread::set_priority(this, prio);
3081
3082 prepare_ext();
3083
3084 // Add the new thread to the Threads list and set it in motion.
3085 // We must have threads lock in order to call Threads::add.
3086 // It is crucial that we do not block before the thread is
3087 // added to the Threads list for if a GC happens, then the java_thread oop
3088 // will not be visited by GC.
3089 Threads::add(this);
3090 }
3091
3092 oop JavaThread::current_park_blocker() {
3093 // Support for JSR-166 locks
3094 oop thread_oop = threadObj();
3095 if (thread_oop != NULL &&
3096 JDK_Version::current().supports_thread_park_blocker()) {
3097 return java_lang_Thread::park_blocker(thread_oop);
3098 }
3099 return NULL;
3100 }
3101
3102
3103 void JavaThread::print_stack_on(outputStream* st) {
3104 if (!has_last_Java_frame()) return;
3105 ResourceMark rm;
3106 HandleMark hm;
3107
3108 RegisterMap reg_map(this);
3109 vframe* start_vf = last_java_vframe(®_map);
3110 int count = 0;
3111 for (vframe* f = start_vf; f; f = f->sender()) {
3112 if (f->is_java_frame()) {
3113 javaVFrame* jvf = javaVFrame::cast(f);
3114 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3115
3116 // Print out lock information
3117 if (JavaMonitorsInStackTrace) {
3118 jvf->print_lock_info_on(st, count);
3119 }
3120 } else {
3121 // Ignore non-Java frames
3122 }
3123
3124 // Bail-out case for too deep stacks
3125 count++;
3126 if (MaxJavaStackTraceDepth == count) return;
3127 }
3128 }
3129
3130
3131 // JVMTI PopFrame support
3132 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3133 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3134 if (in_bytes(size_in_bytes) != 0) {
3135 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3136 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3137 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3138 }
3139 }
3140
3141 void* JavaThread::popframe_preserved_args() {
3142 return _popframe_preserved_args;
3143 }
3144
3145 ByteSize JavaThread::popframe_preserved_args_size() {
3146 return in_ByteSize(_popframe_preserved_args_size);
3147 }
3148
3149 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3150 int sz = in_bytes(popframe_preserved_args_size());
3151 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3152 return in_WordSize(sz / wordSize);
3153 }
3154
3155 void JavaThread::popframe_free_preserved_args() {
3156 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3157 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3158 _popframe_preserved_args = NULL;
3159 _popframe_preserved_args_size = 0;
3160 }
3161
3162 #ifndef PRODUCT
3163
3164 void JavaThread::trace_frames() {
3165 tty->print_cr("[Describe stack]");
3166 int frame_no = 1;
3167 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3168 tty->print(" %d. ", frame_no++);
3169 fst.current()->print_value_on(tty, this);
3170 tty->cr();
3171 }
3172 }
3173
3174 class PrintAndVerifyOopClosure: public OopClosure {
3175 protected:
3176 template <class T> inline void do_oop_work(T* p) {
3177 oop obj = oopDesc::load_decode_heap_oop(p);
3178 if (obj == NULL) return;
3179 tty->print(INTPTR_FORMAT ": ", p2i(p));
3180 if (obj->is_oop_or_null()) {
3181 if (obj->is_objArray()) {
3182 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3183 } else {
3184 obj->print();
3185 }
3186 } else {
3187 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3188 }
3189 tty->cr();
3190 }
3191 public:
3192 virtual void do_oop(oop* p) { do_oop_work(p); }
3193 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3194 };
3195
3196
3197 static void oops_print(frame* f, const RegisterMap *map) {
3198 PrintAndVerifyOopClosure print;
3199 f->print_value();
3200 f->oops_do(&print, NULL, (RegisterMap*)map);
3201 }
3202
3203 // Print our all the locations that contain oops and whether they are
3204 // valid or not. This useful when trying to find the oldest frame
3205 // where an oop has gone bad since the frame walk is from youngest to
3206 // oldest.
3207 void JavaThread::trace_oops() {
3208 tty->print_cr("[Trace oops]");
3209 frames_do(oops_print);
3210 }
3211
3212
3213 #ifdef ASSERT
3214 // Print or validate the layout of stack frames
3215 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3216 ResourceMark rm;
3217 PRESERVE_EXCEPTION_MARK;
3218 FrameValues values;
3219 int frame_no = 0;
3220 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3221 fst.current()->describe(values, ++frame_no);
3222 if (depth == frame_no) break;
3223 }
3224 if (validate_only) {
3225 values.validate();
3226 } else {
3227 tty->print_cr("[Describe stack layout]");
3228 values.print(this);
3229 }
3230 }
3231 #endif
3232
3233 void JavaThread::trace_stack_from(vframe* start_vf) {
3234 ResourceMark rm;
3235 int vframe_no = 1;
3236 for (vframe* f = start_vf; f; f = f->sender()) {
3237 if (f->is_java_frame()) {
3238 javaVFrame::cast(f)->print_activation(vframe_no++);
3239 } else {
3240 f->print();
3241 }
3242 if (vframe_no > StackPrintLimit) {
3243 tty->print_cr("...<more frames>...");
3244 return;
3245 }
3246 }
3247 }
3248
3249
3250 void JavaThread::trace_stack() {
3251 if (!has_last_Java_frame()) return;
3252 ResourceMark rm;
3253 HandleMark hm;
3254 RegisterMap reg_map(this);
3255 trace_stack_from(last_java_vframe(®_map));
3256 }
3257
3258
3259 #endif // PRODUCT
3260
3261
3262 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3263 assert(reg_map != NULL, "a map must be given");
3264 frame f = last_frame();
3265 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3266 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3267 }
3268 return NULL;
3269 }
3270
3271
3272 Klass* JavaThread::security_get_caller_class(int depth) {
3273 vframeStream vfst(this);
3274 vfst.security_get_caller_frame(depth);
3275 if (!vfst.at_end()) {
3276 return vfst.method()->method_holder();
3277 }
3278 return NULL;
3279 }
3280
3281 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3282 assert(thread->is_Compiler_thread(), "must be compiler thread");
3283 CompileBroker::compiler_thread_loop();
3284 }
3285
3286 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3287 NMethodSweeper::sweeper_loop();
3288 }
3289
3290 // Create a CompilerThread
3291 CompilerThread::CompilerThread(CompileQueue* queue,
3292 CompilerCounters* counters)
3293 : JavaThread(&compiler_thread_entry) {
3294 _env = NULL;
3295 _log = NULL;
3296 _task = NULL;
3297 _queue = queue;
3298 _counters = counters;
3299 _buffer_blob = NULL;
3300 _compiler = NULL;
3301
3302 #ifndef PRODUCT
3303 _ideal_graph_printer = NULL;
3304 #endif
3305 }
3306
3307 bool CompilerThread::can_call_java() const {
3308 return _compiler != NULL && _compiler->is_jvmci();
3309 }
3310
3311 // Create sweeper thread
3312 CodeCacheSweeperThread::CodeCacheSweeperThread()
3313 : JavaThread(&sweeper_thread_entry) {
3314 _scanned_compiled_method = NULL;
3315 }
3316
3317 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3318 JavaThread::oops_do(f, cf);
3319 if (_scanned_compiled_method != NULL && cf != NULL) {
3320 // Safepoints can occur when the sweeper is scanning an nmethod so
3321 // process it here to make sure it isn't unloaded in the middle of
3322 // a scan.
3323 cf->do_code_blob(_scanned_compiled_method);
3324 }
3325 }
3326
3327 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3328 JavaThread::nmethods_do(cf);
3329 if (_scanned_compiled_method != NULL && cf != NULL) {
3330 // Safepoints can occur when the sweeper is scanning an nmethod so
3331 // process it here to make sure it isn't unloaded in the middle of
3332 // a scan.
3333 cf->do_code_blob(_scanned_compiled_method);
3334 }
3335 }
3336
3337
3338 // ======= Threads ========
3339
3340 // The Threads class links together all active threads, and provides
3341 // operations over all threads. It is protected by its own Mutex
3342 // lock, which is also used in other contexts to protect thread
3343 // operations from having the thread being operated on from exiting
3344 // and going away unexpectedly (e.g., safepoint synchronization)
3345
3346 JavaThread* Threads::_thread_list = NULL;
3347 int Threads::_number_of_threads = 0;
3348 int Threads::_number_of_non_daemon_threads = 0;
3349 int Threads::_return_code = 0;
3350 int Threads::_thread_claim_parity = 0;
3351 size_t JavaThread::_stack_size_at_create = 0;
3352 #ifdef ASSERT
3353 bool Threads::_vm_complete = false;
3354 #endif
3355
3356 // All JavaThreads
3357 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3358
3359 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3360 void Threads::threads_do(ThreadClosure* tc) {
3361 assert_locked_or_safepoint(Threads_lock);
3362 // ALL_JAVA_THREADS iterates through all JavaThreads
3363 ALL_JAVA_THREADS(p) {
3364 tc->do_thread(p);
3365 }
3366 // Someday we could have a table or list of all non-JavaThreads.
3367 // For now, just manually iterate through them.
3368 tc->do_thread(VMThread::vm_thread());
3369 Universe::heap()->gc_threads_do(tc);
3370 WatcherThread *wt = WatcherThread::watcher_thread();
3371 // Strictly speaking, the following NULL check isn't sufficient to make sure
3372 // the data for WatcherThread is still valid upon being examined. However,
3373 // considering that WatchThread terminates when the VM is on the way to
3374 // exit at safepoint, the chance of the above is extremely small. The right
3375 // way to prevent termination of WatcherThread would be to acquire
3376 // Terminator_lock, but we can't do that without violating the lock rank
3377 // checking in some cases.
3378 if (wt != NULL) {
3379 tc->do_thread(wt);
3380 }
3381
3382 // If CompilerThreads ever become non-JavaThreads, add them here
3383 }
3384
3385 // The system initialization in the library has three phases.
3386 //
3387 // Phase 1: java.lang.System class initialization
3388 // java.lang.System is a primordial class loaded and initialized
3389 // by the VM early during startup. java.lang.System.<clinit>
3390 // only does registerNatives and keeps the rest of the class
3391 // initialization work later until thread initialization completes.
3392 //
3393 // System.initPhase1 initializes the system properties, the static
3394 // fields in, out, and err. Set up java signal handlers, OS-specific
3395 // system settings, and thread group of the main thread.
3396 static void call_initPhase1(TRAPS) {
3397 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3398 JavaValue result(T_VOID);
3399 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3400 vmSymbols::void_method_signature(), CHECK);
3401 }
3402
3403 // Phase 2. Module system initialization
3404 // This will initialize the module system. Only java.base classes
3405 // can be loaded until phase 2 completes.
3406 //
3407 // Call System.initPhase2 after the compiler initialization and jsr292
3408 // classes get initialized because module initialization runs a lot of java
3409 // code, that for performance reasons, should be compiled. Also, this will
3410 // enable the startup code to use lambda and other language features in this
3411 // phase and onward.
3412 //
3413 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3414 static void call_initPhase2(TRAPS) {
3415 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3416
3417 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3418
3419 JavaValue result(T_INT);
3420 JavaCallArguments args;
3421 args.push_int(DisplayVMOutputToStderr);
3422 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3423 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3424 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3425 if (result.get_jint() != JNI_OK) {
3426 vm_exit_during_initialization(); // no message or exception
3427 }
3428
3429 universe_post_module_init();
3430 }
3431
3432 // Phase 3. final setup - set security manager, system class loader and TCCL
3433 //
3434 // This will instantiate and set the security manager, set the system class
3435 // loader as well as the thread context class loader. The security manager
3436 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3437 // other modules or the application's classpath.
3438 static void call_initPhase3(TRAPS) {
3439 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3440 JavaValue result(T_VOID);
3441 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3442 vmSymbols::void_method_signature(), CHECK);
3443 }
3444
3445 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3446 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3447
3448 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3449 create_vm_init_libraries();
3450 }
3451
3452 initialize_class(vmSymbols::java_lang_String(), CHECK);
3453
3454 // Inject CompactStrings value after the static initializers for String ran.
3455 java_lang_String::set_compact_strings(CompactStrings);
3456
3457 // Initialize java_lang.System (needed before creating the thread)
3458 initialize_class(vmSymbols::java_lang_System(), CHECK);
3459 // The VM creates & returns objects of this class. Make sure it's initialized.
3460 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3461 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3462 Handle thread_group = create_initial_thread_group(CHECK);
3463 Universe::set_main_thread_group(thread_group());
3464 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3465 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3466 main_thread->set_threadObj(thread_object);
3467 // Set thread status to running since main thread has
3468 // been started and running.
3469 java_lang_Thread::set_thread_status(thread_object,
3470 java_lang_Thread::RUNNABLE);
3471
3472 // The VM creates objects of this class.
3473 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3474
3475 // The VM preresolves methods to these classes. Make sure that they get initialized
3476 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3477 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3478
3479 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3480 call_initPhase1(CHECK);
3481
3482 // get the Java runtime name after java.lang.System is initialized
3483 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3484 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3485
3486 // an instance of OutOfMemory exception has been allocated earlier
3487 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3488 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3489 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3490 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3491 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3492 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3493 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3494 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3495 }
3496
3497 void Threads::initialize_jsr292_core_classes(TRAPS) {
3498 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3499
3500 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3501 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3502 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3503 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3504 }
3505
3506 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3507 extern void JDK_Version_init();
3508
3509 // Preinitialize version info.
3510 VM_Version::early_initialize();
3511
3512 // Check version
3513 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3514
3515 // Initialize library-based TLS
3516 ThreadLocalStorage::init();
3517
3518 // Initialize the output stream module
3519 ostream_init();
3520
3521 // Process java launcher properties.
3522 Arguments::process_sun_java_launcher_properties(args);
3523
3524 // Initialize the os module
3525 os::init();
3526
3527 // Record VM creation timing statistics
3528 TraceVmCreationTime create_vm_timer;
3529 create_vm_timer.start();
3530
3531 // Initialize system properties.
3532 Arguments::init_system_properties();
3533
3534 // So that JDK version can be used as a discriminator when parsing arguments
3535 JDK_Version_init();
3536
3537 // Update/Initialize System properties after JDK version number is known
3538 Arguments::init_version_specific_system_properties();
3539
3540 // Make sure to initialize log configuration *before* parsing arguments
3541 LogConfiguration::initialize(create_vm_timer.begin_time());
3542
3543 // Parse arguments
3544 jint parse_result = Arguments::parse(args);
3545 if (parse_result != JNI_OK) return parse_result;
3546
3547 os::init_before_ergo();
3548
3549 jint ergo_result = Arguments::apply_ergo();
3550 if (ergo_result != JNI_OK) return ergo_result;
3551
3552 // Final check of all ranges after ergonomics which may change values.
3553 if (!CommandLineFlagRangeList::check_ranges()) {
3554 return JNI_EINVAL;
3555 }
3556
3557 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3558 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3559 if (!constraint_result) {
3560 return JNI_EINVAL;
3561 }
3562
3563 CommandLineFlagWriteableList::mark_startup();
3564
3565 if (PauseAtStartup) {
3566 os::pause();
3567 }
3568
3569 HOTSPOT_VM_INIT_BEGIN();
3570
3571 // Timing (must come after argument parsing)
3572 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3573
3574 // Initialize the os module after parsing the args
3575 jint os_init_2_result = os::init_2();
3576 if (os_init_2_result != JNI_OK) return os_init_2_result;
3577
3578 jint adjust_after_os_result = Arguments::adjust_after_os();
3579 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3580
3581 // Initialize output stream logging
3582 ostream_init_log();
3583
3584 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3585 // Must be before create_vm_init_agents()
3586 if (Arguments::init_libraries_at_startup()) {
3587 convert_vm_init_libraries_to_agents();
3588 }
3589
3590 // Launch -agentlib/-agentpath and converted -Xrun agents
3591 if (Arguments::init_agents_at_startup()) {
3592 create_vm_init_agents();
3593 }
3594
3595 // Initialize Threads state
3596 _thread_list = NULL;
3597 _number_of_threads = 0;
3598 _number_of_non_daemon_threads = 0;
3599
3600 // Initialize global data structures and create system classes in heap
3601 vm_init_globals();
3602
3603 #if INCLUDE_JVMCI
3604 if (JVMCICounterSize > 0) {
3605 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3606 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3607 } else {
3608 JavaThread::_jvmci_old_thread_counters = NULL;
3609 }
3610 #endif // INCLUDE_JVMCI
3611
3612 // Attach the main thread to this os thread
3613 JavaThread* main_thread = new JavaThread();
3614 main_thread->set_thread_state(_thread_in_vm);
3615 main_thread->initialize_thread_current();
3616 // must do this before set_active_handles
3617 main_thread->record_stack_base_and_size();
3618 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3619
3620 if (!main_thread->set_as_starting_thread()) {
3621 vm_shutdown_during_initialization(
3622 "Failed necessary internal allocation. Out of swap space");
3623 delete main_thread;
3624 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3625 return JNI_ENOMEM;
3626 }
3627
3628 // Enable guard page *after* os::create_main_thread(), otherwise it would
3629 // crash Linux VM, see notes in os_linux.cpp.
3630 main_thread->create_stack_guard_pages();
3631
3632 // Initialize Java-Level synchronization subsystem
3633 ObjectMonitor::Initialize();
3634
3635 // Initialize global modules
3636 jint status = init_globals();
3637 if (status != JNI_OK) {
3638 delete main_thread;
3639 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3640 return status;
3641 }
3642
3643 if (TRACE_INITIALIZE() != JNI_OK) {
3644 vm_exit_during_initialization("Failed to initialize tracing backend");
3645 }
3646
3647 // Should be done after the heap is fully created
3648 main_thread->cache_global_variables();
3649
3650 HandleMark hm;
3651
3652 { MutexLocker mu(Threads_lock);
3653 Threads::add(main_thread);
3654 }
3655
3656 // Any JVMTI raw monitors entered in onload will transition into
3657 // real raw monitor. VM is setup enough here for raw monitor enter.
3658 JvmtiExport::transition_pending_onload_raw_monitors();
3659
3660 // Create the VMThread
3661 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3662
3663 VMThread::create();
3664 Thread* vmthread = VMThread::vm_thread();
3665
3666 if (!os::create_thread(vmthread, os::vm_thread)) {
3667 vm_exit_during_initialization("Cannot create VM thread. "
3668 "Out of system resources.");
3669 }
3670
3671 // Wait for the VM thread to become ready, and VMThread::run to initialize
3672 // Monitors can have spurious returns, must always check another state flag
3673 {
3674 MutexLocker ml(Notify_lock);
3675 os::start_thread(vmthread);
3676 while (vmthread->active_handles() == NULL) {
3677 Notify_lock->wait();
3678 }
3679 }
3680 }
3681
3682 assert(Universe::is_fully_initialized(), "not initialized");
3683 if (VerifyDuringStartup) {
3684 // Make sure we're starting with a clean slate.
3685 VM_Verify verify_op;
3686 VMThread::execute(&verify_op);
3687 }
3688
3689 Thread* THREAD = Thread::current();
3690
3691 // At this point, the Universe is initialized, but we have not executed
3692 // any byte code. Now is a good time (the only time) to dump out the
3693 // internal state of the JVM for sharing.
3694 if (DumpSharedSpaces) {
3695 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3696 ShouldNotReachHere();
3697 }
3698
3699 // Always call even when there are not JVMTI environments yet, since environments
3700 // may be attached late and JVMTI must track phases of VM execution
3701 JvmtiExport::enter_early_start_phase();
3702
3703 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3704 JvmtiExport::post_early_vm_start();
3705
3706 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3707
3708 // We need this for ClassDataSharing - the initial vm.info property is set
3709 // with the default value of CDS "sharing" which may be reset through
3710 // command line options.
3711 reset_vm_info_property(CHECK_JNI_ERR);
3712
3713 quicken_jni_functions();
3714
3715 // No more stub generation allowed after that point.
3716 StubCodeDesc::freeze();
3717
3718 // Set flag that basic initialization has completed. Used by exceptions and various
3719 // debug stuff, that does not work until all basic classes have been initialized.
3720 set_init_completed();
3721
3722 LogConfiguration::post_initialize();
3723 Metaspace::post_initialize();
3724
3725 HOTSPOT_VM_INIT_END();
3726
3727 // record VM initialization completion time
3728 #if INCLUDE_MANAGEMENT
3729 Management::record_vm_init_completed();
3730 #endif // INCLUDE_MANAGEMENT
3731
3732 // Signal Dispatcher needs to be started before VMInit event is posted
3733 os::signal_init(CHECK_JNI_ERR);
3734
3735 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3736 if (!DisableAttachMechanism) {
3737 AttachListener::vm_start();
3738 if (StartAttachListener || AttachListener::init_at_startup()) {
3739 AttachListener::init();
3740 }
3741 }
3742
3743 // Launch -Xrun agents
3744 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3745 // back-end can launch with -Xdebug -Xrunjdwp.
3746 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3747 create_vm_init_libraries();
3748 }
3749
3750 if (CleanChunkPoolAsync) {
3751 Chunk::start_chunk_pool_cleaner_task();
3752 }
3753
3754 // initialize compiler(s)
3755 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3756 CompileBroker::compilation_init(CHECK_JNI_ERR);
3757 #endif
3758
3759 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3760 // It is done after compilers are initialized, because otherwise compilations of
3761 // signature polymorphic MH intrinsics can be missed
3762 // (see SystemDictionary::find_method_handle_intrinsic).
3763 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3764
3765 // This will initialize the module system. Only java.base classes can be
3766 // loaded until phase 2 completes
3767 call_initPhase2(CHECK_JNI_ERR);
3768
3769 // Always call even when there are not JVMTI environments yet, since environments
3770 // may be attached late and JVMTI must track phases of VM execution
3771 JvmtiExport::enter_start_phase();
3772
3773 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3774 JvmtiExport::post_vm_start();
3775
3776 // Final system initialization including security manager and system class loader
3777 call_initPhase3(CHECK_JNI_ERR);
3778
3779 // cache the system class loader
3780 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3781
3782 #if INCLUDE_JVMCI
3783 if (EnableJVMCI) {
3784 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3785 // The JVMCI Java initialization code will read this flag and
3786 // do the printing if it's set.
3787 bool init = JVMCIPrintProperties;
3788
3789 if (!init) {
3790 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3791 // compilations via JVMCI will not actually block until JVMCI is initialized.
3792 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3793 }
3794
3795 if (init) {
3796 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3797 }
3798 }
3799 #endif
3800
3801 // Always call even when there are not JVMTI environments yet, since environments
3802 // may be attached late and JVMTI must track phases of VM execution
3803 JvmtiExport::enter_live_phase();
3804
3805 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3806 JvmtiExport::post_vm_initialized();
3807
3808 if (TRACE_START() != JNI_OK) {
3809 vm_exit_during_initialization("Failed to start tracing backend.");
3810 }
3811
3812 #if INCLUDE_MANAGEMENT
3813 Management::initialize(THREAD);
3814
3815 if (HAS_PENDING_EXCEPTION) {
3816 // management agent fails to start possibly due to
3817 // configuration problem and is responsible for printing
3818 // stack trace if appropriate. Simply exit VM.
3819 vm_exit(1);
3820 }
3821 #endif // INCLUDE_MANAGEMENT
3822
3823 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3824 if (MemProfiling) MemProfiler::engage();
3825 StatSampler::engage();
3826 if (CheckJNICalls) JniPeriodicChecker::engage();
3827
3828 BiasedLocking::init();
3829
3830 #if INCLUDE_RTM_OPT
3831 RTMLockingCounters::init();
3832 #endif
3833
3834 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3835 call_postVMInitHook(THREAD);
3836 // The Java side of PostVMInitHook.run must deal with all
3837 // exceptions and provide means of diagnosis.
3838 if (HAS_PENDING_EXCEPTION) {
3839 CLEAR_PENDING_EXCEPTION;
3840 }
3841 }
3842
3843 {
3844 MutexLocker ml(PeriodicTask_lock);
3845 // Make sure the WatcherThread can be started by WatcherThread::start()
3846 // or by dynamic enrollment.
3847 WatcherThread::make_startable();
3848 // Start up the WatcherThread if there are any periodic tasks
3849 // NOTE: All PeriodicTasks should be registered by now. If they
3850 // aren't, late joiners might appear to start slowly (we might
3851 // take a while to process their first tick).
3852 if (PeriodicTask::num_tasks() > 0) {
3853 WatcherThread::start();
3854 }
3855 }
3856
3857 create_vm_timer.end();
3858 #ifdef ASSERT
3859 _vm_complete = true;
3860 #endif
3861 return JNI_OK;
3862 }
3863
3864 // type for the Agent_OnLoad and JVM_OnLoad entry points
3865 extern "C" {
3866 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3867 }
3868 // Find a command line agent library and return its entry point for
3869 // -agentlib: -agentpath: -Xrun
3870 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3871 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3872 const char *on_load_symbols[],
3873 size_t num_symbol_entries) {
3874 OnLoadEntry_t on_load_entry = NULL;
3875 void *library = NULL;
3876
3877 if (!agent->valid()) {
3878 char buffer[JVM_MAXPATHLEN];
3879 char ebuf[1024] = "";
3880 const char *name = agent->name();
3881 const char *msg = "Could not find agent library ";
3882
3883 // First check to see if agent is statically linked into executable
3884 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3885 library = agent->os_lib();
3886 } else if (agent->is_absolute_path()) {
3887 library = os::dll_load(name, ebuf, sizeof ebuf);
3888 if (library == NULL) {
3889 const char *sub_msg = " in absolute path, with error: ";
3890 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3891 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3892 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3893 // If we can't find the agent, exit.
3894 vm_exit_during_initialization(buf, NULL);
3895 FREE_C_HEAP_ARRAY(char, buf);
3896 }
3897 } else {
3898 // Try to load the agent from the standard dll directory
3899 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3900 name)) {
3901 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3902 }
3903 if (library == NULL) { // Try the local directory
3904 char ns[1] = {0};
3905 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3906 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3907 }
3908 if (library == NULL) {
3909 const char *sub_msg = " on the library path, with error: ";
3910 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3911 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3912 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3913 // If we can't find the agent, exit.
3914 vm_exit_during_initialization(buf, NULL);
3915 FREE_C_HEAP_ARRAY(char, buf);
3916 }
3917 }
3918 }
3919 agent->set_os_lib(library);
3920 agent->set_valid();
3921 }
3922
3923 // Find the OnLoad function.
3924 on_load_entry =
3925 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3926 false,
3927 on_load_symbols,
3928 num_symbol_entries));
3929 return on_load_entry;
3930 }
3931
3932 // Find the JVM_OnLoad entry point
3933 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3934 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3935 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3936 }
3937
3938 // Find the Agent_OnLoad entry point
3939 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3940 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3941 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3942 }
3943
3944 // For backwards compatibility with -Xrun
3945 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3946 // treated like -agentpath:
3947 // Must be called before agent libraries are created
3948 void Threads::convert_vm_init_libraries_to_agents() {
3949 AgentLibrary* agent;
3950 AgentLibrary* next;
3951
3952 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3953 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3954 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3955
3956 // If there is an JVM_OnLoad function it will get called later,
3957 // otherwise see if there is an Agent_OnLoad
3958 if (on_load_entry == NULL) {
3959 on_load_entry = lookup_agent_on_load(agent);
3960 if (on_load_entry != NULL) {
3961 // switch it to the agent list -- so that Agent_OnLoad will be called,
3962 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3963 Arguments::convert_library_to_agent(agent);
3964 } else {
3965 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3966 }
3967 }
3968 }
3969 }
3970
3971 // Create agents for -agentlib: -agentpath: and converted -Xrun
3972 // Invokes Agent_OnLoad
3973 // Called very early -- before JavaThreads exist
3974 void Threads::create_vm_init_agents() {
3975 extern struct JavaVM_ main_vm;
3976 AgentLibrary* agent;
3977
3978 JvmtiExport::enter_onload_phase();
3979
3980 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3981 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3982
3983 if (on_load_entry != NULL) {
3984 // Invoke the Agent_OnLoad function
3985 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3986 if (err != JNI_OK) {
3987 vm_exit_during_initialization("agent library failed to init", agent->name());
3988 }
3989 } else {
3990 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3991 }
3992 }
3993 JvmtiExport::enter_primordial_phase();
3994 }
3995
3996 extern "C" {
3997 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3998 }
3999
4000 void Threads::shutdown_vm_agents() {
4001 // Send any Agent_OnUnload notifications
4002 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4003 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4004 extern struct JavaVM_ main_vm;
4005 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4006
4007 // Find the Agent_OnUnload function.
4008 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4009 os::find_agent_function(agent,
4010 false,
4011 on_unload_symbols,
4012 num_symbol_entries));
4013
4014 // Invoke the Agent_OnUnload function
4015 if (unload_entry != NULL) {
4016 JavaThread* thread = JavaThread::current();
4017 ThreadToNativeFromVM ttn(thread);
4018 HandleMark hm(thread);
4019 (*unload_entry)(&main_vm);
4020 }
4021 }
4022 }
4023
4024 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4025 // Invokes JVM_OnLoad
4026 void Threads::create_vm_init_libraries() {
4027 extern struct JavaVM_ main_vm;
4028 AgentLibrary* agent;
4029
4030 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4031 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4032
4033 if (on_load_entry != NULL) {
4034 // Invoke the JVM_OnLoad function
4035 JavaThread* thread = JavaThread::current();
4036 ThreadToNativeFromVM ttn(thread);
4037 HandleMark hm(thread);
4038 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4039 if (err != JNI_OK) {
4040 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4041 }
4042 } else {
4043 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4044 }
4045 }
4046 }
4047
4048 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4049 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4050
4051 JavaThread* java_thread = NULL;
4052 // Sequential search for now. Need to do better optimization later.
4053 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4054 oop tobj = thread->threadObj();
4055 if (!thread->is_exiting() &&
4056 tobj != NULL &&
4057 java_tid == java_lang_Thread::thread_id(tobj)) {
4058 java_thread = thread;
4059 break;
4060 }
4061 }
4062 return java_thread;
4063 }
4064
4065
4066 // Last thread running calls java.lang.Shutdown.shutdown()
4067 void JavaThread::invoke_shutdown_hooks() {
4068 HandleMark hm(this);
4069
4070 // We could get here with a pending exception, if so clear it now.
4071 if (this->has_pending_exception()) {
4072 this->clear_pending_exception();
4073 }
4074
4075 EXCEPTION_MARK;
4076 Klass* shutdown_klass =
4077 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4078 THREAD);
4079 if (shutdown_klass != NULL) {
4080 // SystemDictionary::resolve_or_null will return null if there was
4081 // an exception. If we cannot load the Shutdown class, just don't
4082 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4083 // and finalizers (if runFinalizersOnExit is set) won't be run.
4084 // Note that if a shutdown hook was registered or runFinalizersOnExit
4085 // was called, the Shutdown class would have already been loaded
4086 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4087 JavaValue result(T_VOID);
4088 JavaCalls::call_static(&result,
4089 shutdown_klass,
4090 vmSymbols::shutdown_method_name(),
4091 vmSymbols::void_method_signature(),
4092 THREAD);
4093 }
4094 CLEAR_PENDING_EXCEPTION;
4095 }
4096
4097 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4098 // the program falls off the end of main(). Another VM exit path is through
4099 // vm_exit() when the program calls System.exit() to return a value or when
4100 // there is a serious error in VM. The two shutdown paths are not exactly
4101 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4102 // and VM_Exit op at VM level.
4103 //
4104 // Shutdown sequence:
4105 // + Shutdown native memory tracking if it is on
4106 // + Wait until we are the last non-daemon thread to execute
4107 // <-- every thing is still working at this moment -->
4108 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4109 // shutdown hooks, run finalizers if finalization-on-exit
4110 // + Call before_exit(), prepare for VM exit
4111 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4112 // currently the only user of this mechanism is File.deleteOnExit())
4113 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4114 // post thread end and vm death events to JVMTI,
4115 // stop signal thread
4116 // + Call JavaThread::exit(), it will:
4117 // > release JNI handle blocks, remove stack guard pages
4118 // > remove this thread from Threads list
4119 // <-- no more Java code from this thread after this point -->
4120 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4121 // the compiler threads at safepoint
4122 // <-- do not use anything that could get blocked by Safepoint -->
4123 // + Disable tracing at JNI/JVM barriers
4124 // + Set _vm_exited flag for threads that are still running native code
4125 // + Delete this thread
4126 // + Call exit_globals()
4127 // > deletes tty
4128 // > deletes PerfMemory resources
4129 // + Return to caller
4130
4131 bool Threads::destroy_vm() {
4132 JavaThread* thread = JavaThread::current();
4133
4134 #ifdef ASSERT
4135 _vm_complete = false;
4136 #endif
4137 // Wait until we are the last non-daemon thread to execute
4138 { MutexLocker nu(Threads_lock);
4139 while (Threads::number_of_non_daemon_threads() > 1)
4140 // This wait should make safepoint checks, wait without a timeout,
4141 // and wait as a suspend-equivalent condition.
4142 //
4143 // Note: If the FlatProfiler is running and this thread is waiting
4144 // for another non-daemon thread to finish, then the FlatProfiler
4145 // is waiting for the external suspend request on this thread to
4146 // complete. wait_for_ext_suspend_completion() will eventually
4147 // timeout, but that takes time. Making this wait a suspend-
4148 // equivalent condition solves that timeout problem.
4149 //
4150 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4151 Mutex::_as_suspend_equivalent_flag);
4152 }
4153
4154 // Hang forever on exit if we are reporting an error.
4155 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4156 os::infinite_sleep();
4157 }
4158 os::wait_for_keypress_at_exit();
4159
4160 // run Java level shutdown hooks
4161 thread->invoke_shutdown_hooks();
4162
4163 before_exit(thread);
4164
4165 thread->exit(true);
4166
4167 // Stop VM thread.
4168 {
4169 // 4945125 The vm thread comes to a safepoint during exit.
4170 // GC vm_operations can get caught at the safepoint, and the
4171 // heap is unparseable if they are caught. Grab the Heap_lock
4172 // to prevent this. The GC vm_operations will not be able to
4173 // queue until after the vm thread is dead. After this point,
4174 // we'll never emerge out of the safepoint before the VM exits.
4175
4176 MutexLocker ml(Heap_lock);
4177
4178 VMThread::wait_for_vm_thread_exit();
4179 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4180 VMThread::destroy();
4181 }
4182
4183 // clean up ideal graph printers
4184 #if defined(COMPILER2) && !defined(PRODUCT)
4185 IdealGraphPrinter::clean_up();
4186 #endif
4187
4188 // Now, all Java threads are gone except daemon threads. Daemon threads
4189 // running Java code or in VM are stopped by the Safepoint. However,
4190 // daemon threads executing native code are still running. But they
4191 // will be stopped at native=>Java/VM barriers. Note that we can't
4192 // simply kill or suspend them, as it is inherently deadlock-prone.
4193
4194 VM_Exit::set_vm_exited();
4195
4196 notify_vm_shutdown();
4197
4198 delete thread;
4199
4200 #if INCLUDE_JVMCI
4201 if (JVMCICounterSize > 0) {
4202 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4203 }
4204 #endif
4205
4206 // exit_globals() will delete tty
4207 exit_globals();
4208
4209 LogConfiguration::finalize();
4210
4211 return true;
4212 }
4213
4214
4215 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4216 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4217 return is_supported_jni_version(version);
4218 }
4219
4220
4221 jboolean Threads::is_supported_jni_version(jint version) {
4222 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4223 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4224 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4225 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4226 if (version == JNI_VERSION_9) return JNI_TRUE;
4227 return JNI_FALSE;
4228 }
4229
4230
4231 void Threads::add(JavaThread* p, bool force_daemon) {
4232 // The threads lock must be owned at this point
4233 assert_locked_or_safepoint(Threads_lock);
4234
4235 // See the comment for this method in thread.hpp for its purpose and
4236 // why it is called here.
4237 p->initialize_queues();
4238 p->set_next(_thread_list);
4239 _thread_list = p;
4240 _number_of_threads++;
4241 oop threadObj = p->threadObj();
4242 bool daemon = true;
4243 // Bootstrapping problem: threadObj can be null for initial
4244 // JavaThread (or for threads attached via JNI)
4245 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4246 _number_of_non_daemon_threads++;
4247 daemon = false;
4248 }
4249
4250 ThreadService::add_thread(p, daemon);
4251
4252 // Possible GC point.
4253 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4254 }
4255
4256 void Threads::remove(JavaThread* p) {
4257
4258 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4259 ObjectSynchronizer::omFlush(p);
4260
4261 // Extra scope needed for Thread_lock, so we can check
4262 // that we do not remove thread without safepoint code notice
4263 { MutexLocker ml(Threads_lock);
4264
4265 assert(includes(p), "p must be present");
4266
4267 JavaThread* current = _thread_list;
4268 JavaThread* prev = NULL;
4269
4270 while (current != p) {
4271 prev = current;
4272 current = current->next();
4273 }
4274
4275 if (prev) {
4276 prev->set_next(current->next());
4277 } else {
4278 _thread_list = p->next();
4279 }
4280 _number_of_threads--;
4281 oop threadObj = p->threadObj();
4282 bool daemon = true;
4283 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4284 _number_of_non_daemon_threads--;
4285 daemon = false;
4286
4287 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4288 // on destroy_vm will wake up.
4289 if (number_of_non_daemon_threads() == 1) {
4290 Threads_lock->notify_all();
4291 }
4292 }
4293 ThreadService::remove_thread(p, daemon);
4294
4295 // Make sure that safepoint code disregard this thread. This is needed since
4296 // the thread might mess around with locks after this point. This can cause it
4297 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4298 // of this thread since it is removed from the queue.
4299 p->set_terminated_value();
4300 } // unlock Threads_lock
4301
4302 // Since Events::log uses a lock, we grab it outside the Threads_lock
4303 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4304 }
4305
4306 // Threads_lock must be held when this is called (or must be called during a safepoint)
4307 bool Threads::includes(JavaThread* p) {
4308 assert(Threads_lock->is_locked(), "sanity check");
4309 ALL_JAVA_THREADS(q) {
4310 if (q == p) {
4311 return true;
4312 }
4313 }
4314 return false;
4315 }
4316
4317 // Operations on the Threads list for GC. These are not explicitly locked,
4318 // but the garbage collector must provide a safe context for them to run.
4319 // In particular, these things should never be called when the Threads_lock
4320 // is held by some other thread. (Note: the Safepoint abstraction also
4321 // uses the Threads_lock to guarantee this property. It also makes sure that
4322 // all threads gets blocked when exiting or starting).
4323
4324 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4325 ALL_JAVA_THREADS(p) {
4326 p->oops_do(f, cf);
4327 }
4328 VMThread::vm_thread()->oops_do(f, cf);
4329 }
4330
4331 void Threads::change_thread_claim_parity() {
4332 // Set the new claim parity.
4333 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4334 "Not in range.");
4335 _thread_claim_parity++;
4336 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4337 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4338 "Not in range.");
4339 }
4340
4341 #ifdef ASSERT
4342 void Threads::assert_all_threads_claimed() {
4343 ALL_JAVA_THREADS(p) {
4344 const int thread_parity = p->oops_do_parity();
4345 assert((thread_parity == _thread_claim_parity),
4346 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4347 }
4348 }
4349 #endif // ASSERT
4350
4351 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4352 int cp = Threads::thread_claim_parity();
4353 ALL_JAVA_THREADS(p) {
4354 if (p->claim_oops_do(is_par, cp)) {
4355 p->oops_do(f, cf);
4356 }
4357 }
4358 VMThread* vmt = VMThread::vm_thread();
4359 if (vmt->claim_oops_do(is_par, cp)) {
4360 vmt->oops_do(f, cf);
4361 }
4362 }
4363
4364 #if INCLUDE_ALL_GCS
4365 // Used by ParallelScavenge
4366 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4367 ALL_JAVA_THREADS(p) {
4368 q->enqueue(new ThreadRootsTask(p));
4369 }
4370 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4371 }
4372
4373 // Used by Parallel Old
4374 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4375 ALL_JAVA_THREADS(p) {
4376 q->enqueue(new ThreadRootsMarkingTask(p));
4377 }
4378 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4379 }
4380 #endif // INCLUDE_ALL_GCS
4381
4382 void Threads::nmethods_do(CodeBlobClosure* cf) {
4383 ALL_JAVA_THREADS(p) {
4384 // This is used by the code cache sweeper to mark nmethods that are active
4385 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4386 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4387 if(!p->is_Code_cache_sweeper_thread()) {
4388 p->nmethods_do(cf);
4389 }
4390 }
4391 }
4392
4393 void Threads::metadata_do(void f(Metadata*)) {
4394 ALL_JAVA_THREADS(p) {
4395 p->metadata_do(f);
4396 }
4397 }
4398
4399 class ThreadHandlesClosure : public ThreadClosure {
4400 void (*_f)(Metadata*);
4401 public:
4402 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4403 virtual void do_thread(Thread* thread) {
4404 thread->metadata_handles_do(_f);
4405 }
4406 };
4407
4408 void Threads::metadata_handles_do(void f(Metadata*)) {
4409 // Only walk the Handles in Thread.
4410 ThreadHandlesClosure handles_closure(f);
4411 threads_do(&handles_closure);
4412 }
4413
4414 void Threads::deoptimized_wrt_marked_nmethods() {
4415 ALL_JAVA_THREADS(p) {
4416 p->deoptimized_wrt_marked_nmethods();
4417 }
4418 }
4419
4420
4421 // Get count Java threads that are waiting to enter the specified monitor.
4422 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4423 address monitor,
4424 bool doLock) {
4425 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4426 "must grab Threads_lock or be at safepoint");
4427 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4428
4429 int i = 0;
4430 {
4431 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4432 ALL_JAVA_THREADS(p) {
4433 if (!p->can_call_java()) continue;
4434
4435 address pending = (address)p->current_pending_monitor();
4436 if (pending == monitor) { // found a match
4437 if (i < count) result->append(p); // save the first count matches
4438 i++;
4439 }
4440 }
4441 }
4442 return result;
4443 }
4444
4445
4446 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4447 bool doLock) {
4448 assert(doLock ||
4449 Threads_lock->owned_by_self() ||
4450 SafepointSynchronize::is_at_safepoint(),
4451 "must grab Threads_lock or be at safepoint");
4452
4453 // NULL owner means not locked so we can skip the search
4454 if (owner == NULL) return NULL;
4455
4456 {
4457 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4458 ALL_JAVA_THREADS(p) {
4459 // first, see if owner is the address of a Java thread
4460 if (owner == (address)p) return p;
4461 }
4462 }
4463 // Cannot assert on lack of success here since this function may be
4464 // used by code that is trying to report useful problem information
4465 // like deadlock detection.
4466 if (UseHeavyMonitors) return NULL;
4467
4468 // If we didn't find a matching Java thread and we didn't force use of
4469 // heavyweight monitors, then the owner is the stack address of the
4470 // Lock Word in the owning Java thread's stack.
4471 //
4472 JavaThread* the_owner = NULL;
4473 {
4474 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4475 ALL_JAVA_THREADS(q) {
4476 if (q->is_lock_owned(owner)) {
4477 the_owner = q;
4478 break;
4479 }
4480 }
4481 }
4482 // cannot assert on lack of success here; see above comment
4483 return the_owner;
4484 }
4485
4486 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4487 void Threads::print_on(outputStream* st, bool print_stacks,
4488 bool internal_format, bool print_concurrent_locks) {
4489 char buf[32];
4490 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4491
4492 st->print_cr("Full thread dump %s (%s %s):",
4493 Abstract_VM_Version::vm_name(),
4494 Abstract_VM_Version::vm_release(),
4495 Abstract_VM_Version::vm_info_string());
4496 st->cr();
4497
4498 #if INCLUDE_SERVICES
4499 // Dump concurrent locks
4500 ConcurrentLocksDump concurrent_locks;
4501 if (print_concurrent_locks) {
4502 concurrent_locks.dump_at_safepoint();
4503 }
4504 #endif // INCLUDE_SERVICES
4505
4506 ALL_JAVA_THREADS(p) {
4507 ResourceMark rm;
4508 p->print_on(st);
4509 if (print_stacks) {
4510 if (internal_format) {
4511 p->trace_stack();
4512 } else {
4513 p->print_stack_on(st);
4514 }
4515 }
4516 st->cr();
4517 #if INCLUDE_SERVICES
4518 if (print_concurrent_locks) {
4519 concurrent_locks.print_locks_on(p, st);
4520 }
4521 #endif // INCLUDE_SERVICES
4522 }
4523
4524 VMThread::vm_thread()->print_on(st);
4525 st->cr();
4526 Universe::heap()->print_gc_threads_on(st);
4527 WatcherThread* wt = WatcherThread::watcher_thread();
4528 if (wt != NULL) {
4529 wt->print_on(st);
4530 st->cr();
4531 }
4532 st->flush();
4533 }
4534
4535 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4536 int buflen, bool* found_current) {
4537 if (this_thread != NULL) {
4538 bool is_current = (current == this_thread);
4539 *found_current = *found_current || is_current;
4540 st->print("%s", is_current ? "=>" : " ");
4541
4542 st->print(PTR_FORMAT, p2i(this_thread));
4543 st->print(" ");
4544 this_thread->print_on_error(st, buf, buflen);
4545 st->cr();
4546 }
4547 }
4548
4549 class PrintOnErrorClosure : public ThreadClosure {
4550 outputStream* _st;
4551 Thread* _current;
4552 char* _buf;
4553 int _buflen;
4554 bool* _found_current;
4555 public:
4556 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4557 int buflen, bool* found_current) :
4558 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4559
4560 virtual void do_thread(Thread* thread) {
4561 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4562 }
4563 };
4564
4565 // Threads::print_on_error() is called by fatal error handler. It's possible
4566 // that VM is not at safepoint and/or current thread is inside signal handler.
4567 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4568 // memory (even in resource area), it might deadlock the error handler.
4569 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4570 int buflen) {
4571 bool found_current = false;
4572 st->print_cr("Java Threads: ( => current thread )");
4573 ALL_JAVA_THREADS(thread) {
4574 print_on_error(thread, st, current, buf, buflen, &found_current);
4575 }
4576 st->cr();
4577
4578 st->print_cr("Other Threads:");
4579 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4580 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4581
4582 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4583 Universe::heap()->gc_threads_do(&print_closure);
4584
4585 if (!found_current) {
4586 st->cr();
4587 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4588 current->print_on_error(st, buf, buflen);
4589 st->cr();
4590 }
4591 st->cr();
4592 st->print_cr("Threads with active compile tasks:");
4593 print_threads_compiling(st, buf, buflen);
4594 }
4595
4596 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4597 ALL_JAVA_THREADS(thread) {
4598 if (thread->is_Compiler_thread()) {
4599 CompilerThread* ct = (CompilerThread*) thread;
4600 if (ct->task() != NULL) {
4601 thread->print_name_on_error(st, buf, buflen);
4602 ct->task()->print(st, NULL, true, true);
4603 }
4604 }
4605 }
4606 }
4607
4608
4609 // Internal SpinLock and Mutex
4610 // Based on ParkEvent
4611
4612 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4613 //
4614 // We employ SpinLocks _only for low-contention, fixed-length
4615 // short-duration critical sections where we're concerned
4616 // about native mutex_t or HotSpot Mutex:: latency.
4617 // The mux construct provides a spin-then-block mutual exclusion
4618 // mechanism.
4619 //
4620 // Testing has shown that contention on the ListLock guarding gFreeList
4621 // is common. If we implement ListLock as a simple SpinLock it's common
4622 // for the JVM to devolve to yielding with little progress. This is true
4623 // despite the fact that the critical sections protected by ListLock are
4624 // extremely short.
4625 //
4626 // TODO-FIXME: ListLock should be of type SpinLock.
4627 // We should make this a 1st-class type, integrated into the lock
4628 // hierarchy as leaf-locks. Critically, the SpinLock structure
4629 // should have sufficient padding to avoid false-sharing and excessive
4630 // cache-coherency traffic.
4631
4632
4633 typedef volatile int SpinLockT;
4634
4635 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4636 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4637 return; // normal fast-path return
4638 }
4639
4640 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4641 TEVENT(SpinAcquire - ctx);
4642 int ctr = 0;
4643 int Yields = 0;
4644 for (;;) {
4645 while (*adr != 0) {
4646 ++ctr;
4647 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4648 if (Yields > 5) {
4649 os::naked_short_sleep(1);
4650 } else {
4651 os::naked_yield();
4652 ++Yields;
4653 }
4654 } else {
4655 SpinPause();
4656 }
4657 }
4658 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4659 }
4660 }
4661
4662 void Thread::SpinRelease(volatile int * adr) {
4663 assert(*adr != 0, "invariant");
4664 OrderAccess::fence(); // guarantee at least release consistency.
4665 // Roach-motel semantics.
4666 // It's safe if subsequent LDs and STs float "up" into the critical section,
4667 // but prior LDs and STs within the critical section can't be allowed
4668 // to reorder or float past the ST that releases the lock.
4669 // Loads and stores in the critical section - which appear in program
4670 // order before the store that releases the lock - must also appear
4671 // before the store that releases the lock in memory visibility order.
4672 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4673 // the ST of 0 into the lock-word which releases the lock, so fence
4674 // more than covers this on all platforms.
4675 *adr = 0;
4676 }
4677
4678 // muxAcquire and muxRelease:
4679 //
4680 // * muxAcquire and muxRelease support a single-word lock-word construct.
4681 // The LSB of the word is set IFF the lock is held.
4682 // The remainder of the word points to the head of a singly-linked list
4683 // of threads blocked on the lock.
4684 //
4685 // * The current implementation of muxAcquire-muxRelease uses its own
4686 // dedicated Thread._MuxEvent instance. If we're interested in
4687 // minimizing the peak number of extant ParkEvent instances then
4688 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4689 // as certain invariants were satisfied. Specifically, care would need
4690 // to be taken with regards to consuming unpark() "permits".
4691 // A safe rule of thumb is that a thread would never call muxAcquire()
4692 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4693 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4694 // consume an unpark() permit intended for monitorenter, for instance.
4695 // One way around this would be to widen the restricted-range semaphore
4696 // implemented in park(). Another alternative would be to provide
4697 // multiple instances of the PlatformEvent() for each thread. One
4698 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4699 //
4700 // * Usage:
4701 // -- Only as leaf locks
4702 // -- for short-term locking only as muxAcquire does not perform
4703 // thread state transitions.
4704 //
4705 // Alternatives:
4706 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4707 // but with parking or spin-then-park instead of pure spinning.
4708 // * Use Taura-Oyama-Yonenzawa locks.
4709 // * It's possible to construct a 1-0 lock if we encode the lockword as
4710 // (List,LockByte). Acquire will CAS the full lockword while Release
4711 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4712 // acquiring threads use timers (ParkTimed) to detect and recover from
4713 // the stranding window. Thread/Node structures must be aligned on 256-byte
4714 // boundaries by using placement-new.
4715 // * Augment MCS with advisory back-link fields maintained with CAS().
4716 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4717 // The validity of the backlinks must be ratified before we trust the value.
4718 // If the backlinks are invalid the exiting thread must back-track through the
4719 // the forward links, which are always trustworthy.
4720 // * Add a successor indication. The LockWord is currently encoded as
4721 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4722 // to provide the usual futile-wakeup optimization.
4723 // See RTStt for details.
4724 // * Consider schedctl.sc_nopreempt to cover the critical section.
4725 //
4726
4727
4728 typedef volatile intptr_t MutexT; // Mux Lock-word
4729 enum MuxBits { LOCKBIT = 1 };
4730
4731 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4732 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4733 if (w == 0) return;
4734 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4735 return;
4736 }
4737
4738 TEVENT(muxAcquire - Contention);
4739 ParkEvent * const Self = Thread::current()->_MuxEvent;
4740 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4741 for (;;) {
4742 int its = (os::is_MP() ? 100 : 0) + 1;
4743
4744 // Optional spin phase: spin-then-park strategy
4745 while (--its >= 0) {
4746 w = *Lock;
4747 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4748 return;
4749 }
4750 }
4751
4752 Self->reset();
4753 Self->OnList = intptr_t(Lock);
4754 // The following fence() isn't _strictly necessary as the subsequent
4755 // CAS() both serializes execution and ratifies the fetched *Lock value.
4756 OrderAccess::fence();
4757 for (;;) {
4758 w = *Lock;
4759 if ((w & LOCKBIT) == 0) {
4760 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4761 Self->OnList = 0; // hygiene - allows stronger asserts
4762 return;
4763 }
4764 continue; // Interference -- *Lock changed -- Just retry
4765 }
4766 assert(w & LOCKBIT, "invariant");
4767 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4768 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4769 }
4770
4771 while (Self->OnList != 0) {
4772 Self->park();
4773 }
4774 }
4775 }
4776
4777 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4778 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4779 if (w == 0) return;
4780 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4781 return;
4782 }
4783
4784 TEVENT(muxAcquire - Contention);
4785 ParkEvent * ReleaseAfter = NULL;
4786 if (ev == NULL) {
4787 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4788 }
4789 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4790 for (;;) {
4791 guarantee(ev->OnList == 0, "invariant");
4792 int its = (os::is_MP() ? 100 : 0) + 1;
4793
4794 // Optional spin phase: spin-then-park strategy
4795 while (--its >= 0) {
4796 w = *Lock;
4797 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4798 if (ReleaseAfter != NULL) {
4799 ParkEvent::Release(ReleaseAfter);
4800 }
4801 return;
4802 }
4803 }
4804
4805 ev->reset();
4806 ev->OnList = intptr_t(Lock);
4807 // The following fence() isn't _strictly necessary as the subsequent
4808 // CAS() both serializes execution and ratifies the fetched *Lock value.
4809 OrderAccess::fence();
4810 for (;;) {
4811 w = *Lock;
4812 if ((w & LOCKBIT) == 0) {
4813 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4814 ev->OnList = 0;
4815 // We call ::Release while holding the outer lock, thus
4816 // artificially lengthening the critical section.
4817 // Consider deferring the ::Release() until the subsequent unlock(),
4818 // after we've dropped the outer lock.
4819 if (ReleaseAfter != NULL) {
4820 ParkEvent::Release(ReleaseAfter);
4821 }
4822 return;
4823 }
4824 continue; // Interference -- *Lock changed -- Just retry
4825 }
4826 assert(w & LOCKBIT, "invariant");
4827 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4828 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4829 }
4830
4831 while (ev->OnList != 0) {
4832 ev->park();
4833 }
4834 }
4835 }
4836
4837 // Release() must extract a successor from the list and then wake that thread.
4838 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4839 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4840 // Release() would :
4841 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4842 // (B) Extract a successor from the private list "in-hand"
4843 // (C) attempt to CAS() the residual back into *Lock over null.
4844 // If there were any newly arrived threads and the CAS() would fail.
4845 // In that case Release() would detach the RATs, re-merge the list in-hand
4846 // with the RATs and repeat as needed. Alternately, Release() might
4847 // detach and extract a successor, but then pass the residual list to the wakee.
4848 // The wakee would be responsible for reattaching and remerging before it
4849 // competed for the lock.
4850 //
4851 // Both "pop" and DMR are immune from ABA corruption -- there can be
4852 // multiple concurrent pushers, but only one popper or detacher.
4853 // This implementation pops from the head of the list. This is unfair,
4854 // but tends to provide excellent throughput as hot threads remain hot.
4855 // (We wake recently run threads first).
4856 //
4857 // All paths through muxRelease() will execute a CAS.
4858 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4859 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4860 // executed within the critical section are complete and globally visible before the
4861 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4862 void Thread::muxRelease(volatile intptr_t * Lock) {
4863 for (;;) {
4864 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4865 assert(w & LOCKBIT, "invariant");
4866 if (w == LOCKBIT) return;
4867 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4868 assert(List != NULL, "invariant");
4869 assert(List->OnList == intptr_t(Lock), "invariant");
4870 ParkEvent * const nxt = List->ListNext;
4871 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4872
4873 // The following CAS() releases the lock and pops the head element.
4874 // The CAS() also ratifies the previously fetched lock-word value.
4875 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4876 continue;
4877 }
4878 List->OnList = 0;
4879 OrderAccess::fence();
4880 List->unpark();
4881 return;
4882 }
4883 }
4884
4885
4886 void Threads::verify() {
4887 ALL_JAVA_THREADS(p) {
4888 p->verify();
4889 }
4890 VMThread* thread = VMThread::vm_thread();
4891 if (thread != NULL) thread->verify();
4892 }