1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/scopeDesc.hpp"
33 #include "compiler/compileBroker.hpp"
34 #include "compiler/compileTask.hpp"
35 #include "gc/shared/gcId.hpp"
36 #include "gc/shared/gcLocker.inline.hpp"
37 #include "gc/shared/workgroup.hpp"
38 #include "interpreter/interpreter.hpp"
39 #include "interpreter/linkResolver.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "jvmtifiles/jvmtiEnv.hpp"
42 #include "logging/log.hpp"
43 #include "logging/logConfiguration.hpp"
44 #include "logging/logStream.hpp"
45 #include "memory/metaspaceShared.hpp"
46 #include "memory/oopFactory.hpp"
47 #include "memory/resourceArea.hpp"
48 #include "memory/universe.inline.hpp"
49 #include "oops/instanceKlass.hpp"
50 #include "oops/objArrayOop.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/symbol.hpp"
53 #include "oops/verifyOopClosure.hpp"
54 #include "prims/jvm.h"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagWriteableList.hpp"
64 #include "runtime/commandLineFlagRangeList.hpp"
65 #include "runtime/deoptimization.hpp"
66 #include "runtime/frame.inline.hpp"
67 #include "runtime/globals.hpp"
68 #include "runtime/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/shenandoah/shenandoahConcurrentThread.hpp"
108 #include "gc/cms/concurrentMarkSweepThread.hpp"
109 #include "gc/g1/concurrentMarkThread.inline.hpp"
110 #include "gc/parallel/pcTasks.hpp"
111 #endif // INCLUDE_ALL_GCS
112 #if INCLUDE_JVMCI
113 #include "jvmci/jvmciCompiler.hpp"
114 #include "jvmci/jvmciRuntime.hpp"
115 #include "logging/logHandle.hpp"
116 #endif
117 #ifdef COMPILER1
118 #include "c1/c1_Compiler.hpp"
119 #endif
120 #ifdef COMPILER2
121 #include "opto/c2compiler.hpp"
122 #include "opto/idealGraphPrinter.hpp"
123 #endif
124 #if INCLUDE_RTM_OPT
125 #include "runtime/rtmLocking.hpp"
126 #endif
127
128 // Initialization after module runtime initialization
129 void universe_post_module_init(); // must happen after call_initPhase2
130
131 #ifdef DTRACE_ENABLED
132
133 // Only bother with this argument setup if dtrace is available
134
135 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
136 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
137
138 #define DTRACE_THREAD_PROBE(probe, javathread) \
139 { \
140 ResourceMark rm(this); \
141 int len = 0; \
142 const char* name = (javathread)->get_thread_name(); \
143 len = strlen(name); \
144 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
145 (char *) name, len, \
146 java_lang_Thread::thread_id((javathread)->threadObj()), \
147 (uintptr_t) (javathread)->osthread()->thread_id(), \
148 java_lang_Thread::is_daemon((javathread)->threadObj())); \
149 }
150
151 #else // ndef DTRACE_ENABLED
152
153 #define DTRACE_THREAD_PROBE(probe, javathread)
154
155 #endif // ndef DTRACE_ENABLED
156
157 #ifndef USE_LIBRARY_BASED_TLS_ONLY
158 // Current thread is maintained as a thread-local variable
159 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
160 #endif
161 // Class hierarchy
162 // - Thread
163 // - VMThread
164 // - WatcherThread
165 // - ConcurrentMarkSweepThread
166 // - JavaThread
167 // - CompilerThread
168
169 // ======= Thread ========
170 // Support for forcing alignment of thread objects for biased locking
171 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
172 if (UseBiasedLocking) {
173 const int alignment = markOopDesc::biased_lock_alignment;
174 size_t aligned_size = size + (alignment - sizeof(intptr_t));
175 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
176 : AllocateHeap(aligned_size, flags, CURRENT_PC,
177 AllocFailStrategy::RETURN_NULL);
178 void* aligned_addr = align_up(real_malloc_addr, alignment);
179 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
180 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
181 "JavaThread alignment code overflowed allocated storage");
182 if (aligned_addr != real_malloc_addr) {
183 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
184 p2i(real_malloc_addr),
185 p2i(aligned_addr));
186 }
187 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
188 return aligned_addr;
189 } else {
190 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
191 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
192 }
193 }
194
195 void Thread::operator delete(void* p) {
196 if (UseBiasedLocking) {
197 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
198 FreeHeap(real_malloc_addr);
199 } else {
200 FreeHeap(p);
201 }
202 }
203
204
205 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
206 // JavaThread
207
208
209 Thread::Thread() {
210 // stack and get_thread
211 set_stack_base(NULL);
212 set_stack_size(0);
213 set_self_raw_id(0);
214 set_lgrp_id(-1);
215 DEBUG_ONLY(clear_suspendible_thread();)
216
217 // allocated data structures
218 set_osthread(NULL);
219 set_resource_area(new (mtThread)ResourceArea());
220 DEBUG_ONLY(_current_resource_mark = NULL;)
221 set_handle_area(new (mtThread) HandleArea(NULL));
222 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
223 set_active_handles(NULL);
224 set_free_handle_block(NULL);
225 set_last_handle_mark(NULL);
226
227 // This initial value ==> never claimed.
228 _oops_do_parity = 0;
229
230 // the handle mark links itself to last_handle_mark
231 new HandleMark(this);
232
233 // plain initialization
234 debug_only(_owned_locks = NULL;)
235 debug_only(_allow_allocation_count = 0;)
236 NOT_PRODUCT(_allow_safepoint_count = 0;)
237 NOT_PRODUCT(_skip_gcalot = false;)
238 _jvmti_env_iteration_count = 0;
239 set_allocated_bytes(0);
240 _vm_operation_started_count = 0;
241 _vm_operation_completed_count = 0;
242 _current_pending_monitor = NULL;
243 _current_pending_monitor_is_from_java = true;
244 _current_waiting_monitor = NULL;
245 _num_nested_signal = 0;
246 omFreeList = NULL;
247 omFreeCount = 0;
248 omFreeProvision = 32;
249 omInUseList = NULL;
250 omInUseCount = 0;
251
252 #ifdef ASSERT
253 _visited_for_critical_count = false;
254 #endif
255
256 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
257 Monitor::_safepoint_check_sometimes);
258 _suspend_flags = 0;
259
260 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
261 _hashStateX = os::random();
262 _hashStateY = 842502087;
263 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
264 _hashStateW = 273326509;
265
266 _OnTrap = 0;
267 _schedctl = NULL;
268 _Stalled = 0;
269 _TypeTag = 0x2BAD;
270
271 // Many of the following fields are effectively final - immutable
272 // Note that nascent threads can't use the Native Monitor-Mutex
273 // construct until the _MutexEvent is initialized ...
274 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
275 // we might instead use a stack of ParkEvents that we could provision on-demand.
276 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
277 // and ::Release()
278 _ParkEvent = ParkEvent::Allocate(this);
279 _SleepEvent = ParkEvent::Allocate(this);
280 _MutexEvent = ParkEvent::Allocate(this);
281 _MuxEvent = ParkEvent::Allocate(this);
282
283 #ifdef CHECK_UNHANDLED_OOPS
284 if (CheckUnhandledOops) {
285 _unhandled_oops = new UnhandledOops(this);
286 }
287 #endif // CHECK_UNHANDLED_OOPS
288 #ifdef ASSERT
289 if (UseBiasedLocking) {
290 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
291 assert(this == _real_malloc_address ||
292 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
293 "bug in forced alignment of thread objects");
294 }
295 #endif // ASSERT
296 }
297
298 void Thread::initialize_thread_current() {
299 #ifndef USE_LIBRARY_BASED_TLS_ONLY
300 assert(_thr_current == NULL, "Thread::current already initialized");
301 _thr_current = this;
302 #endif
303 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
304 ThreadLocalStorage::set_thread(this);
305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
306 }
307
308 void Thread::clear_thread_current() {
309 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
310 #ifndef USE_LIBRARY_BASED_TLS_ONLY
311 _thr_current = NULL;
312 #endif
313 ThreadLocalStorage::set_thread(NULL);
314 }
315
316 void Thread::record_stack_base_and_size() {
317 set_stack_base(os::current_stack_base());
318 set_stack_size(os::current_stack_size());
319 // CR 7190089: on Solaris, primordial thread's stack is adjusted
320 // in initialize_thread(). Without the adjustment, stack size is
321 // incorrect if stack is set to unlimited (ulimit -s unlimited).
322 // So far, only Solaris has real implementation of initialize_thread().
323 //
324 // set up any platform-specific state.
325 os::initialize_thread(this);
326
327 // Set stack limits after thread is initialized.
328 if (is_Java_thread()) {
329 ((JavaThread*) this)->set_stack_overflow_limit();
330 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
331 }
332 #if INCLUDE_NMT
333 // record thread's native stack, stack grows downward
334 MemTracker::record_thread_stack(stack_end(), stack_size());
335 #endif // INCLUDE_NMT
336 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
337 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
338 os::current_thread_id(), p2i(stack_base() - stack_size()),
339 p2i(stack_base()), stack_size()/1024);
340 }
341
342
343 Thread::~Thread() {
344 EVENT_THREAD_DESTRUCT(this);
345
346 // stack_base can be NULL if the thread is never started or exited before
347 // record_stack_base_and_size called. Although, we would like to ensure
348 // that all started threads do call record_stack_base_and_size(), there is
349 // not proper way to enforce that.
350 #if INCLUDE_NMT
351 if (_stack_base != NULL) {
352 MemTracker::release_thread_stack(stack_end(), stack_size());
353 #ifdef ASSERT
354 set_stack_base(NULL);
355 #endif
356 }
357 #endif // INCLUDE_NMT
358
359 // deallocate data structures
360 delete resource_area();
361 // since the handle marks are using the handle area, we have to deallocated the root
362 // handle mark before deallocating the thread's handle area,
363 assert(last_handle_mark() != NULL, "check we have an element");
364 delete last_handle_mark();
365 assert(last_handle_mark() == NULL, "check we have reached the end");
366
367 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
368 // We NULL out the fields for good hygiene.
369 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
370 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
371 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
372 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
373
374 delete handle_area();
375 delete metadata_handles();
376
377 // SR_handler uses this as a termination indicator -
378 // needs to happen before os::free_thread()
379 delete _SR_lock;
380 _SR_lock = NULL;
381
382 // osthread() can be NULL, if creation of thread failed.
383 if (osthread() != NULL) os::free_thread(osthread());
384
385 // clear Thread::current if thread is deleting itself.
386 // Needed to ensure JNI correctly detects non-attached threads.
387 if (this == Thread::current()) {
388 clear_thread_current();
389 }
390
391 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
392 }
393
394 // NOTE: dummy function for assertion purpose.
395 void Thread::run() {
396 ShouldNotReachHere();
397 }
398
399 #ifdef ASSERT
400 // Private method to check for dangling thread pointer
401 void check_for_dangling_thread_pointer(Thread *thread) {
402 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
403 "possibility of dangling Thread pointer");
404 }
405 #endif
406
407 ThreadPriority Thread::get_priority(const Thread* const thread) {
408 ThreadPriority priority;
409 // Can return an error!
410 (void)os::get_priority(thread, priority);
411 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
412 return priority;
413 }
414
415 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
416 debug_only(check_for_dangling_thread_pointer(thread);)
417 // Can return an error!
418 (void)os::set_priority(thread, priority);
419 }
420
421
422 void Thread::start(Thread* thread) {
423 // Start is different from resume in that its safety is guaranteed by context or
424 // being called from a Java method synchronized on the Thread object.
425 if (!DisableStartThread) {
426 if (thread->is_Java_thread()) {
427 // Initialize the thread state to RUNNABLE before starting this thread.
428 // Can not set it after the thread started because we do not know the
429 // exact thread state at that time. It could be in MONITOR_WAIT or
430 // in SLEEPING or some other state.
431 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
432 java_lang_Thread::RUNNABLE);
433 }
434 os::start_thread(thread);
435 }
436 }
437
438 // Enqueue a VM_Operation to do the job for us - sometime later
439 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
440 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
441 VMThread::execute(vm_stop);
442 }
443
444
445 // Check if an external suspend request has completed (or has been
446 // cancelled). Returns true if the thread is externally suspended and
447 // false otherwise.
448 //
449 // The bits parameter returns information about the code path through
450 // the routine. Useful for debugging:
451 //
452 // set in is_ext_suspend_completed():
453 // 0x00000001 - routine was entered
454 // 0x00000010 - routine return false at end
455 // 0x00000100 - thread exited (return false)
456 // 0x00000200 - suspend request cancelled (return false)
457 // 0x00000400 - thread suspended (return true)
458 // 0x00001000 - thread is in a suspend equivalent state (return true)
459 // 0x00002000 - thread is native and walkable (return true)
460 // 0x00004000 - thread is native_trans and walkable (needed retry)
461 //
462 // set in wait_for_ext_suspend_completion():
463 // 0x00010000 - routine was entered
464 // 0x00020000 - suspend request cancelled before loop (return false)
465 // 0x00040000 - thread suspended before loop (return true)
466 // 0x00080000 - suspend request cancelled in loop (return false)
467 // 0x00100000 - thread suspended in loop (return true)
468 // 0x00200000 - suspend not completed during retry loop (return false)
469
470 // Helper class for tracing suspend wait debug bits.
471 //
472 // 0x00000100 indicates that the target thread exited before it could
473 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
474 // 0x00080000 each indicate a cancelled suspend request so they don't
475 // count as wait failures either.
476 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
477
478 class TraceSuspendDebugBits : public StackObj {
479 private:
480 JavaThread * jt;
481 bool is_wait;
482 bool called_by_wait; // meaningful when !is_wait
483 uint32_t * bits;
484
485 public:
486 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
487 uint32_t *_bits) {
488 jt = _jt;
489 is_wait = _is_wait;
490 called_by_wait = _called_by_wait;
491 bits = _bits;
492 }
493
494 ~TraceSuspendDebugBits() {
495 if (!is_wait) {
496 #if 1
497 // By default, don't trace bits for is_ext_suspend_completed() calls.
498 // That trace is very chatty.
499 return;
500 #else
501 if (!called_by_wait) {
502 // If tracing for is_ext_suspend_completed() is enabled, then only
503 // trace calls to it from wait_for_ext_suspend_completion()
504 return;
505 }
506 #endif
507 }
508
509 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
510 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
511 MutexLocker ml(Threads_lock); // needed for get_thread_name()
512 ResourceMark rm;
513
514 tty->print_cr(
515 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
516 jt->get_thread_name(), *bits);
517
518 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
519 }
520 }
521 }
522 };
523 #undef DEBUG_FALSE_BITS
524
525
526 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
527 uint32_t *bits) {
528 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
529
530 bool did_trans_retry = false; // only do thread_in_native_trans retry once
531 bool do_trans_retry; // flag to force the retry
532
533 *bits |= 0x00000001;
534
535 do {
536 do_trans_retry = false;
537
538 if (is_exiting()) {
539 // Thread is in the process of exiting. This is always checked
540 // first to reduce the risk of dereferencing a freed JavaThread.
541 *bits |= 0x00000100;
542 return false;
543 }
544
545 if (!is_external_suspend()) {
546 // Suspend request is cancelled. This is always checked before
547 // is_ext_suspended() to reduce the risk of a rogue resume
548 // confusing the thread that made the suspend request.
549 *bits |= 0x00000200;
550 return false;
551 }
552
553 if (is_ext_suspended()) {
554 // thread is suspended
555 *bits |= 0x00000400;
556 return true;
557 }
558
559 // Now that we no longer do hard suspends of threads running
560 // native code, the target thread can be changing thread state
561 // while we are in this routine:
562 //
563 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
564 //
565 // We save a copy of the thread state as observed at this moment
566 // and make our decision about suspend completeness based on the
567 // copy. This closes the race where the thread state is seen as
568 // _thread_in_native_trans in the if-thread_blocked check, but is
569 // seen as _thread_blocked in if-thread_in_native_trans check.
570 JavaThreadState save_state = thread_state();
571
572 if (save_state == _thread_blocked && is_suspend_equivalent()) {
573 // If the thread's state is _thread_blocked and this blocking
574 // condition is known to be equivalent to a suspend, then we can
575 // consider the thread to be externally suspended. This means that
576 // the code that sets _thread_blocked has been modified to do
577 // self-suspension if the blocking condition releases. We also
578 // used to check for CONDVAR_WAIT here, but that is now covered by
579 // the _thread_blocked with self-suspension check.
580 //
581 // Return true since we wouldn't be here unless there was still an
582 // external suspend request.
583 *bits |= 0x00001000;
584 return true;
585 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
586 // Threads running native code will self-suspend on native==>VM/Java
587 // transitions. If its stack is walkable (should always be the case
588 // unless this function is called before the actual java_suspend()
589 // call), then the wait is done.
590 *bits |= 0x00002000;
591 return true;
592 } else if (!called_by_wait && !did_trans_retry &&
593 save_state == _thread_in_native_trans &&
594 frame_anchor()->walkable()) {
595 // The thread is transitioning from thread_in_native to another
596 // thread state. check_safepoint_and_suspend_for_native_trans()
597 // will force the thread to self-suspend. If it hasn't gotten
598 // there yet we may have caught the thread in-between the native
599 // code check above and the self-suspend. Lucky us. If we were
600 // called by wait_for_ext_suspend_completion(), then it
601 // will be doing the retries so we don't have to.
602 //
603 // Since we use the saved thread state in the if-statement above,
604 // there is a chance that the thread has already transitioned to
605 // _thread_blocked by the time we get here. In that case, we will
606 // make a single unnecessary pass through the logic below. This
607 // doesn't hurt anything since we still do the trans retry.
608
609 *bits |= 0x00004000;
610
611 // Once the thread leaves thread_in_native_trans for another
612 // thread state, we break out of this retry loop. We shouldn't
613 // need this flag to prevent us from getting back here, but
614 // sometimes paranoia is good.
615 did_trans_retry = true;
616
617 // We wait for the thread to transition to a more usable state.
618 for (int i = 1; i <= SuspendRetryCount; i++) {
619 // We used to do an "os::yield_all(i)" call here with the intention
620 // that yielding would increase on each retry. However, the parameter
621 // is ignored on Linux which means the yield didn't scale up. Waiting
622 // on the SR_lock below provides a much more predictable scale up for
623 // the delay. It also provides a simple/direct point to check for any
624 // safepoint requests from the VMThread
625
626 // temporarily drops SR_lock while doing wait with safepoint check
627 // (if we're a JavaThread - the WatcherThread can also call this)
628 // and increase delay with each retry
629 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
630
631 // check the actual thread state instead of what we saved above
632 if (thread_state() != _thread_in_native_trans) {
633 // the thread has transitioned to another thread state so
634 // try all the checks (except this one) one more time.
635 do_trans_retry = true;
636 break;
637 }
638 } // end retry loop
639
640
641 }
642 } while (do_trans_retry);
643
644 *bits |= 0x00000010;
645 return false;
646 }
647
648 // Wait for an external suspend request to complete (or be cancelled).
649 // Returns true if the thread is externally suspended and false otherwise.
650 //
651 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
652 uint32_t *bits) {
653 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
654 false /* !called_by_wait */, bits);
655
656 // local flag copies to minimize SR_lock hold time
657 bool is_suspended;
658 bool pending;
659 uint32_t reset_bits;
660
661 // set a marker so is_ext_suspend_completed() knows we are the caller
662 *bits |= 0x00010000;
663
664 // We use reset_bits to reinitialize the bits value at the top of
665 // each retry loop. This allows the caller to make use of any
666 // unused bits for their own marking purposes.
667 reset_bits = *bits;
668
669 {
670 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
671 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
672 delay, bits);
673 pending = is_external_suspend();
674 }
675 // must release SR_lock to allow suspension to complete
676
677 if (!pending) {
678 // A cancelled suspend request is the only false return from
679 // is_ext_suspend_completed() that keeps us from entering the
680 // retry loop.
681 *bits |= 0x00020000;
682 return false;
683 }
684
685 if (is_suspended) {
686 *bits |= 0x00040000;
687 return true;
688 }
689
690 for (int i = 1; i <= retries; i++) {
691 *bits = reset_bits; // reinit to only track last retry
692
693 // We used to do an "os::yield_all(i)" call here with the intention
694 // that yielding would increase on each retry. However, the parameter
695 // is ignored on Linux which means the yield didn't scale up. Waiting
696 // on the SR_lock below provides a much more predictable scale up for
697 // the delay. It also provides a simple/direct point to check for any
698 // safepoint requests from the VMThread
699
700 {
701 MutexLocker ml(SR_lock());
702 // wait with safepoint check (if we're a JavaThread - the WatcherThread
703 // can also call this) and increase delay with each retry
704 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
705
706 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
707 delay, bits);
708
709 // It is possible for the external suspend request to be cancelled
710 // (by a resume) before the actual suspend operation is completed.
711 // Refresh our local copy to see if we still need to wait.
712 pending = is_external_suspend();
713 }
714
715 if (!pending) {
716 // A cancelled suspend request is the only false return from
717 // is_ext_suspend_completed() that keeps us from staying in the
718 // retry loop.
719 *bits |= 0x00080000;
720 return false;
721 }
722
723 if (is_suspended) {
724 *bits |= 0x00100000;
725 return true;
726 }
727 } // end retry loop
728
729 // thread did not suspend after all our retries
730 *bits |= 0x00200000;
731 return false;
732 }
733
734 #ifndef PRODUCT
735 void JavaThread::record_jump(address target, address instr, const char* file,
736 int line) {
737
738 // This should not need to be atomic as the only way for simultaneous
739 // updates is via interrupts. Even then this should be rare or non-existent
740 // and we don't care that much anyway.
741
742 int index = _jmp_ring_index;
743 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
744 _jmp_ring[index]._target = (intptr_t) target;
745 _jmp_ring[index]._instruction = (intptr_t) instr;
746 _jmp_ring[index]._file = file;
747 _jmp_ring[index]._line = line;
748 }
749 #endif // PRODUCT
750
751 void Thread::interrupt(Thread* thread) {
752 debug_only(check_for_dangling_thread_pointer(thread);)
753 os::interrupt(thread);
754 }
755
756 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
757 debug_only(check_for_dangling_thread_pointer(thread);)
758 // Note: If clear_interrupted==false, this simply fetches and
759 // returns the value of the field osthread()->interrupted().
760 return os::is_interrupted(thread, clear_interrupted);
761 }
762
763
764 // GC Support
765 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
766 jint thread_parity = _oops_do_parity;
767 if (thread_parity != strong_roots_parity) {
768 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
769 if (res == thread_parity) {
770 return true;
771 } else {
772 guarantee(res == strong_roots_parity, "Or else what?");
773 return false;
774 }
775 }
776 return false;
777 }
778
779 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
780 active_handles()->oops_do(f);
781 // Do oop for ThreadShadow
782 f->do_oop((oop*)&_pending_exception);
783 handle_area()->oops_do(f);
784
785 if (MonitorInUseLists) {
786 // When using thread local monitor lists, we scan them here,
787 // and the remaining global monitors in ObjectSynchronizer::oops_do().
788 VM_Operation* op = VMThread::vm_operation();
789 if (op != NULL && op->deflates_idle_monitors()) {
790 DeflateMonitorCounters counters; // Dummy for now.
791 ObjectSynchronizer::deflate_thread_local_monitors(this, &counters, f);
792 } else {
793 ObjectSynchronizer::thread_local_used_oops_do(this, f);
794 }
795 }
796 }
797
798 void Thread::metadata_handles_do(void f(Metadata*)) {
799 // Only walk the Handles in Thread.
800 if (metadata_handles() != NULL) {
801 for (int i = 0; i< metadata_handles()->length(); i++) {
802 f(metadata_handles()->at(i));
803 }
804 }
805 }
806
807 void Thread::print_on(outputStream* st) const {
808 // get_priority assumes osthread initialized
809 if (osthread() != NULL) {
810 int os_prio;
811 if (os::get_native_priority(this, &os_prio) == OS_OK) {
812 st->print("os_prio=%d ", os_prio);
813 }
814 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
815 ext().print_on(st);
816 osthread()->print_on(st);
817 }
818 debug_only(if (WizardMode) print_owned_locks_on(st);)
819 }
820
821 // Thread::print_on_error() is called by fatal error handler. Don't use
822 // any lock or allocate memory.
823 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
824 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
825
826 if (is_VM_thread()) { st->print("VMThread"); }
827 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
828 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
829 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
830 else { st->print("Thread"); }
831
832 if (is_Named_thread()) {
833 st->print(" \"%s\"", name());
834 }
835
836 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
837 p2i(stack_end()), p2i(stack_base()));
838
839 if (osthread()) {
840 st->print(" [id=%d]", osthread()->thread_id());
841 }
842 }
843
844 void Thread::print_value_on(outputStream* st) const {
845 if (is_Named_thread()) {
846 st->print(" \"%s\" ", name());
847 }
848 st->print(INTPTR_FORMAT, p2i(this)); // print address
849 }
850
851 #ifdef ASSERT
852 void Thread::print_owned_locks_on(outputStream* st) const {
853 Monitor *cur = _owned_locks;
854 if (cur == NULL) {
855 st->print(" (no locks) ");
856 } else {
857 st->print_cr(" Locks owned:");
858 while (cur) {
859 cur->print_on(st);
860 cur = cur->next();
861 }
862 }
863 }
864
865 static int ref_use_count = 0;
866
867 bool Thread::owns_locks_but_compiled_lock() const {
868 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
869 if (cur != Compile_lock) return true;
870 }
871 return false;
872 }
873
874
875 #endif
876
877 #ifndef PRODUCT
878
879 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
880 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
881 // no threads which allow_vm_block's are held
882 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
883 // Check if current thread is allowed to block at a safepoint
884 if (!(_allow_safepoint_count == 0)) {
885 fatal("Possible safepoint reached by thread that does not allow it");
886 }
887 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
888 fatal("LEAF method calling lock?");
889 }
890
891 #ifdef ASSERT
892 if (potential_vm_operation && is_Java_thread()
893 && !Universe::is_bootstrapping()) {
894 // Make sure we do not hold any locks that the VM thread also uses.
895 // This could potentially lead to deadlocks
896 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
897 // Threads_lock is special, since the safepoint synchronization will not start before this is
898 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
899 // since it is used to transfer control between JavaThreads and the VMThread
900 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
901 if ((cur->allow_vm_block() &&
902 cur != Threads_lock &&
903 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
904 cur != VMOperationRequest_lock &&
905 cur != VMOperationQueue_lock) ||
906 cur->rank() == Mutex::special) {
907 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
908 }
909 }
910 }
911
912 if (GCALotAtAllSafepoints) {
913 // We could enter a safepoint here and thus have a gc
914 InterfaceSupport::check_gc_alot();
915 }
916 #endif
917 }
918 #endif
919
920 bool Thread::is_in_stack(address adr) const {
921 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
922 address end = os::current_stack_pointer();
923 // Allow non Java threads to call this without stack_base
924 if (_stack_base == NULL) return true;
925 if (stack_base() >= adr && adr >= end) return true;
926
927 return false;
928 }
929
930 bool Thread::is_in_usable_stack(address adr) const {
931 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
932 size_t usable_stack_size = _stack_size - stack_guard_size;
933
934 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
935 }
936
937
938 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
939 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
940 // used for compilation in the future. If that change is made, the need for these methods
941 // should be revisited, and they should be removed if possible.
942
943 bool Thread::is_lock_owned(address adr) const {
944 return on_local_stack(adr);
945 }
946
947 bool Thread::set_as_starting_thread() {
948 // NOTE: this must be called inside the main thread.
949 return os::create_main_thread((JavaThread*)this);
950 }
951
952 static void initialize_class(Symbol* class_name, TRAPS) {
953 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
954 InstanceKlass::cast(klass)->initialize(CHECK);
955 }
956
957
958 // Creates the initial ThreadGroup
959 static Handle create_initial_thread_group(TRAPS) {
960 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
961 InstanceKlass* ik = InstanceKlass::cast(k);
962
963 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
964 {
965 JavaValue result(T_VOID);
966 JavaCalls::call_special(&result,
967 system_instance,
968 ik,
969 vmSymbols::object_initializer_name(),
970 vmSymbols::void_method_signature(),
971 CHECK_NH);
972 }
973 Universe::set_system_thread_group(system_instance());
974
975 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
976 {
977 JavaValue result(T_VOID);
978 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
979 JavaCalls::call_special(&result,
980 main_instance,
981 ik,
982 vmSymbols::object_initializer_name(),
983 vmSymbols::threadgroup_string_void_signature(),
984 system_instance,
985 string,
986 CHECK_NH);
987 }
988 return main_instance;
989 }
990
991 // Creates the initial Thread
992 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
993 TRAPS) {
994 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
995 InstanceKlass* ik = InstanceKlass::cast(k);
996 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
997
998 java_lang_Thread::set_thread(thread_oop(), thread);
999 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1000 thread->set_threadObj(thread_oop());
1001
1002 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1003
1004 JavaValue result(T_VOID);
1005 JavaCalls::call_special(&result, thread_oop,
1006 ik,
1007 vmSymbols::object_initializer_name(),
1008 vmSymbols::threadgroup_string_void_signature(),
1009 thread_group,
1010 string,
1011 CHECK_NULL);
1012 return thread_oop();
1013 }
1014
1015 char java_runtime_name[128] = "";
1016 char java_runtime_version[128] = "";
1017
1018 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1019 static const char* get_java_runtime_name(TRAPS) {
1020 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1021 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1022 fieldDescriptor fd;
1023 bool found = k != NULL &&
1024 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1025 vmSymbols::string_signature(), &fd);
1026 if (found) {
1027 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1028 if (name_oop == NULL) {
1029 return NULL;
1030 }
1031 const char* name = java_lang_String::as_utf8_string(name_oop,
1032 java_runtime_name,
1033 sizeof(java_runtime_name));
1034 return name;
1035 } else {
1036 return NULL;
1037 }
1038 }
1039
1040 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1041 static const char* get_java_runtime_version(TRAPS) {
1042 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1043 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1044 fieldDescriptor fd;
1045 bool found = k != NULL &&
1046 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1047 vmSymbols::string_signature(), &fd);
1048 if (found) {
1049 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1050 if (name_oop == NULL) {
1051 return NULL;
1052 }
1053 const char* name = java_lang_String::as_utf8_string(name_oop,
1054 java_runtime_version,
1055 sizeof(java_runtime_version));
1056 return name;
1057 } else {
1058 return NULL;
1059 }
1060 }
1061
1062 // General purpose hook into Java code, run once when the VM is initialized.
1063 // The Java library method itself may be changed independently from the VM.
1064 static void call_postVMInitHook(TRAPS) {
1065 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1066 if (klass != NULL) {
1067 JavaValue result(T_VOID);
1068 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1069 vmSymbols::void_method_signature(),
1070 CHECK);
1071 }
1072 }
1073
1074 static void reset_vm_info_property(TRAPS) {
1075 // the vm info string
1076 ResourceMark rm(THREAD);
1077 const char *vm_info = VM_Version::vm_info_string();
1078
1079 // java.lang.System class
1080 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1081
1082 // setProperty arguments
1083 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1084 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1085
1086 // return value
1087 JavaValue r(T_OBJECT);
1088
1089 // public static String setProperty(String key, String value);
1090 JavaCalls::call_static(&r,
1091 klass,
1092 vmSymbols::setProperty_name(),
1093 vmSymbols::string_string_string_signature(),
1094 key_str,
1095 value_str,
1096 CHECK);
1097 }
1098
1099
1100 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1101 bool daemon, TRAPS) {
1102 assert(thread_group.not_null(), "thread group should be specified");
1103 assert(threadObj() == NULL, "should only create Java thread object once");
1104
1105 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1106 InstanceKlass* ik = InstanceKlass::cast(k);
1107 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1108
1109 java_lang_Thread::set_thread(thread_oop(), this);
1110 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1111 set_threadObj(thread_oop());
1112
1113 JavaValue result(T_VOID);
1114 if (thread_name != NULL) {
1115 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1116 // Thread gets assigned specified name and null target
1117 JavaCalls::call_special(&result,
1118 thread_oop,
1119 ik,
1120 vmSymbols::object_initializer_name(),
1121 vmSymbols::threadgroup_string_void_signature(),
1122 thread_group, // Argument 1
1123 name, // Argument 2
1124 THREAD);
1125 } else {
1126 // Thread gets assigned name "Thread-nnn" and null target
1127 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1128 JavaCalls::call_special(&result,
1129 thread_oop,
1130 ik,
1131 vmSymbols::object_initializer_name(),
1132 vmSymbols::threadgroup_runnable_void_signature(),
1133 thread_group, // Argument 1
1134 Handle(), // Argument 2
1135 THREAD);
1136 }
1137
1138
1139 if (daemon) {
1140 java_lang_Thread::set_daemon(thread_oop());
1141 }
1142
1143 if (HAS_PENDING_EXCEPTION) {
1144 return;
1145 }
1146
1147 Klass* group = SystemDictionary::ThreadGroup_klass();
1148 Handle threadObj(THREAD, this->threadObj());
1149
1150 JavaCalls::call_special(&result,
1151 thread_group,
1152 group,
1153 vmSymbols::add_method_name(),
1154 vmSymbols::thread_void_signature(),
1155 threadObj, // Arg 1
1156 THREAD);
1157 }
1158
1159 // NamedThread -- non-JavaThread subclasses with multiple
1160 // uniquely named instances should derive from this.
1161 NamedThread::NamedThread() : Thread() {
1162 _name = NULL;
1163 _processed_thread = NULL;
1164 _gc_id = GCId::undefined();
1165 }
1166
1167 NamedThread::~NamedThread() {
1168 if (_name != NULL) {
1169 FREE_C_HEAP_ARRAY(char, _name);
1170 _name = NULL;
1171 }
1172 }
1173
1174 void NamedThread::set_name(const char* format, ...) {
1175 guarantee(_name == NULL, "Only get to set name once.");
1176 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1177 guarantee(_name != NULL, "alloc failure");
1178 va_list ap;
1179 va_start(ap, format);
1180 jio_vsnprintf(_name, max_name_len, format, ap);
1181 va_end(ap);
1182 }
1183
1184 void NamedThread::initialize_named_thread() {
1185 set_native_thread_name(name());
1186 }
1187
1188 void NamedThread::print_on(outputStream* st) const {
1189 st->print("\"%s\" ", name());
1190 Thread::print_on(st);
1191 st->cr();
1192 }
1193
1194
1195 // ======= WatcherThread ========
1196
1197 // The watcher thread exists to simulate timer interrupts. It should
1198 // be replaced by an abstraction over whatever native support for
1199 // timer interrupts exists on the platform.
1200
1201 WatcherThread* WatcherThread::_watcher_thread = NULL;
1202 bool WatcherThread::_startable = false;
1203 volatile bool WatcherThread::_should_terminate = false;
1204
1205 WatcherThread::WatcherThread() : Thread() {
1206 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1207 if (os::create_thread(this, os::watcher_thread)) {
1208 _watcher_thread = this;
1209
1210 // Set the watcher thread to the highest OS priority which should not be
1211 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1212 // is created. The only normal thread using this priority is the reference
1213 // handler thread, which runs for very short intervals only.
1214 // If the VMThread's priority is not lower than the WatcherThread profiling
1215 // will be inaccurate.
1216 os::set_priority(this, MaxPriority);
1217 if (!DisableStartThread) {
1218 os::start_thread(this);
1219 }
1220 }
1221 }
1222
1223 int WatcherThread::sleep() const {
1224 // The WatcherThread does not participate in the safepoint protocol
1225 // for the PeriodicTask_lock because it is not a JavaThread.
1226 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1227
1228 if (_should_terminate) {
1229 // check for termination before we do any housekeeping or wait
1230 return 0; // we did not sleep.
1231 }
1232
1233 // remaining will be zero if there are no tasks,
1234 // causing the WatcherThread to sleep until a task is
1235 // enrolled
1236 int remaining = PeriodicTask::time_to_wait();
1237 int time_slept = 0;
1238
1239 // we expect this to timeout - we only ever get unparked when
1240 // we should terminate or when a new task has been enrolled
1241 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1242
1243 jlong time_before_loop = os::javaTimeNanos();
1244
1245 while (true) {
1246 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1247 remaining);
1248 jlong now = os::javaTimeNanos();
1249
1250 if (remaining == 0) {
1251 // if we didn't have any tasks we could have waited for a long time
1252 // consider the time_slept zero and reset time_before_loop
1253 time_slept = 0;
1254 time_before_loop = now;
1255 } else {
1256 // need to recalculate since we might have new tasks in _tasks
1257 time_slept = (int) ((now - time_before_loop) / 1000000);
1258 }
1259
1260 // Change to task list or spurious wakeup of some kind
1261 if (timedout || _should_terminate) {
1262 break;
1263 }
1264
1265 remaining = PeriodicTask::time_to_wait();
1266 if (remaining == 0) {
1267 // Last task was just disenrolled so loop around and wait until
1268 // another task gets enrolled
1269 continue;
1270 }
1271
1272 remaining -= time_slept;
1273 if (remaining <= 0) {
1274 break;
1275 }
1276 }
1277
1278 return time_slept;
1279 }
1280
1281 void WatcherThread::run() {
1282 assert(this == watcher_thread(), "just checking");
1283
1284 this->record_stack_base_and_size();
1285 this->set_native_thread_name(this->name());
1286 this->set_active_handles(JNIHandleBlock::allocate_block());
1287 while (true) {
1288 assert(watcher_thread() == Thread::current(), "thread consistency check");
1289 assert(watcher_thread() == this, "thread consistency check");
1290
1291 // Calculate how long it'll be until the next PeriodicTask work
1292 // should be done, and sleep that amount of time.
1293 int time_waited = sleep();
1294
1295 if (VMError::is_error_reported()) {
1296 // A fatal error has happened, the error handler(VMError::report_and_die)
1297 // should abort JVM after creating an error log file. However in some
1298 // rare cases, the error handler itself might deadlock. Here periodically
1299 // check for error reporting timeouts, and if it happens, just proceed to
1300 // abort the VM.
1301
1302 // This code is in WatcherThread because WatcherThread wakes up
1303 // periodically so the fatal error handler doesn't need to do anything;
1304 // also because the WatcherThread is less likely to crash than other
1305 // threads.
1306
1307 for (;;) {
1308 // Note: we use naked sleep in this loop because we want to avoid using
1309 // any kind of VM infrastructure which may be broken at this point.
1310 if (VMError::check_timeout()) {
1311 // We hit error reporting timeout. Error reporting was interrupted and
1312 // will be wrapping things up now (closing files etc). Give it some more
1313 // time, then quit the VM.
1314 os::naked_short_sleep(200);
1315 // Print a message to stderr.
1316 fdStream err(defaultStream::output_fd());
1317 err.print_raw_cr("# [ timer expired, abort... ]");
1318 // skip atexit/vm_exit/vm_abort hooks
1319 os::die();
1320 }
1321
1322 // Wait a second, then recheck for timeout.
1323 os::naked_short_sleep(999);
1324 }
1325 }
1326
1327 if (_should_terminate) {
1328 // check for termination before posting the next tick
1329 break;
1330 }
1331
1332 PeriodicTask::real_time_tick(time_waited);
1333 }
1334
1335 // Signal that it is terminated
1336 {
1337 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1338 _watcher_thread = NULL;
1339 Terminator_lock->notify();
1340 }
1341 }
1342
1343 void WatcherThread::start() {
1344 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1345
1346 if (watcher_thread() == NULL && _startable) {
1347 _should_terminate = false;
1348 // Create the single instance of WatcherThread
1349 new WatcherThread();
1350 }
1351 }
1352
1353 void WatcherThread::make_startable() {
1354 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1355 _startable = true;
1356 }
1357
1358 void WatcherThread::stop() {
1359 {
1360 // Follow normal safepoint aware lock enter protocol since the
1361 // WatcherThread is stopped by another JavaThread.
1362 MutexLocker ml(PeriodicTask_lock);
1363 _should_terminate = true;
1364
1365 WatcherThread* watcher = watcher_thread();
1366 if (watcher != NULL) {
1367 // unpark the WatcherThread so it can see that it should terminate
1368 watcher->unpark();
1369 }
1370 }
1371
1372 MutexLocker mu(Terminator_lock);
1373
1374 while (watcher_thread() != NULL) {
1375 // This wait should make safepoint checks, wait without a timeout,
1376 // and wait as a suspend-equivalent condition.
1377 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1378 Mutex::_as_suspend_equivalent_flag);
1379 }
1380 }
1381
1382 void WatcherThread::unpark() {
1383 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1384 PeriodicTask_lock->notify();
1385 }
1386
1387 void WatcherThread::print_on(outputStream* st) const {
1388 st->print("\"%s\" ", name());
1389 Thread::print_on(st);
1390 st->cr();
1391 }
1392
1393 // ======= JavaThread ========
1394
1395 #if INCLUDE_JVMCI
1396
1397 jlong* JavaThread::_jvmci_old_thread_counters;
1398
1399 bool jvmci_counters_include(JavaThread* thread) {
1400 oop threadObj = thread->threadObj();
1401 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1402 }
1403
1404 void JavaThread::collect_counters(typeArrayOop array) {
1405 if (JVMCICounterSize > 0) {
1406 MutexLocker tl(Threads_lock);
1407 for (int i = 0; i < array->length(); i++) {
1408 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1409 }
1410 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1411 if (jvmci_counters_include(tp)) {
1412 for (int i = 0; i < array->length(); i++) {
1413 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1414 }
1415 }
1416 }
1417 }
1418 }
1419
1420 #endif // INCLUDE_JVMCI
1421
1422 // A JavaThread is a normal Java thread
1423
1424 void JavaThread::initialize() {
1425 // Initialize fields
1426
1427 set_saved_exception_pc(NULL);
1428 set_threadObj(NULL);
1429 _anchor.clear();
1430 set_entry_point(NULL);
1431 set_jni_functions(jni_functions());
1432 set_callee_target(NULL);
1433 set_vm_result(NULL);
1434 set_vm_result_2(NULL);
1435 set_vframe_array_head(NULL);
1436 set_vframe_array_last(NULL);
1437 set_deferred_locals(NULL);
1438 set_deopt_mark(NULL);
1439 set_deopt_compiled_method(NULL);
1440 clear_must_deopt_id();
1441 set_monitor_chunks(NULL);
1442 set_next(NULL);
1443 set_thread_state(_thread_new);
1444 _terminated = _not_terminated;
1445 _privileged_stack_top = NULL;
1446 _array_for_gc = NULL;
1447 _suspend_equivalent = false;
1448 _in_deopt_handler = 0;
1449 _doing_unsafe_access = false;
1450 _stack_guard_state = stack_guard_unused;
1451 #if INCLUDE_JVMCI
1452 _pending_monitorenter = false;
1453 _pending_deoptimization = -1;
1454 _pending_failed_speculation = NULL;
1455 _pending_transfer_to_interpreter = false;
1456 _adjusting_comp_level = false;
1457 _jvmci._alternate_call_target = NULL;
1458 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1459 if (JVMCICounterSize > 0) {
1460 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1461 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1462 } else {
1463 _jvmci_counters = NULL;
1464 }
1465 #endif // INCLUDE_JVMCI
1466 _reserved_stack_activation = NULL; // stack base not known yet
1467 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1468 _exception_pc = 0;
1469 _exception_handler_pc = 0;
1470 _is_method_handle_return = 0;
1471 _jvmti_thread_state= NULL;
1472 _should_post_on_exceptions_flag = JNI_FALSE;
1473 _jvmti_get_loaded_classes_closure = NULL;
1474 _interp_only_mode = 0;
1475 _special_runtime_exit_condition = _no_async_condition;
1476 _pending_async_exception = NULL;
1477 _thread_stat = NULL;
1478 _thread_stat = new ThreadStatistics();
1479 _blocked_on_compilation = false;
1480 _jni_active_critical = 0;
1481 _pending_jni_exception_check_fn = NULL;
1482 _do_not_unlock_if_synchronized = false;
1483 _cached_monitor_info = NULL;
1484 _parker = Parker::Allocate(this);
1485
1486 #ifndef PRODUCT
1487 _jmp_ring_index = 0;
1488 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1489 record_jump(NULL, NULL, NULL, 0);
1490 }
1491 #endif // PRODUCT
1492
1493 // Setup safepoint state info for this thread
1494 ThreadSafepointState::create(this);
1495
1496 debug_only(_java_call_counter = 0);
1497
1498 // JVMTI PopFrame support
1499 _popframe_condition = popframe_inactive;
1500 _popframe_preserved_args = NULL;
1501 _popframe_preserved_args_size = 0;
1502 _frames_to_pop_failed_realloc = 0;
1503
1504 pd_initialize();
1505 }
1506
1507 #if INCLUDE_ALL_GCS
1508 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1509 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1510 bool JavaThread::_evacuation_in_progress_global = false;
1511 #endif // INCLUDE_ALL_GCS
1512
1513 JavaThread::JavaThread(bool is_attaching_via_jni) :
1514 Thread()
1515 #if INCLUDE_ALL_GCS
1516 , _satb_mark_queue(&_satb_mark_queue_set),
1517 _dirty_card_queue(&_dirty_card_queue_set),
1518 _evacuation_in_progress(_evacuation_in_progress_global)
1519 #endif // INCLUDE_ALL_GCS
1520 {
1521 initialize();
1522 if (is_attaching_via_jni) {
1523 _jni_attach_state = _attaching_via_jni;
1524 } else {
1525 _jni_attach_state = _not_attaching_via_jni;
1526 }
1527 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1528 }
1529
1530 bool JavaThread::reguard_stack(address cur_sp) {
1531 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1532 && _stack_guard_state != stack_guard_reserved_disabled) {
1533 return true; // Stack already guarded or guard pages not needed.
1534 }
1535
1536 if (register_stack_overflow()) {
1537 // For those architectures which have separate register and
1538 // memory stacks, we must check the register stack to see if
1539 // it has overflowed.
1540 return false;
1541 }
1542
1543 // Java code never executes within the yellow zone: the latter is only
1544 // there to provoke an exception during stack banging. If java code
1545 // is executing there, either StackShadowPages should be larger, or
1546 // some exception code in c1, c2 or the interpreter isn't unwinding
1547 // when it should.
1548 guarantee(cur_sp > stack_reserved_zone_base(),
1549 "not enough space to reguard - increase StackShadowPages");
1550 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1551 enable_stack_yellow_reserved_zone();
1552 if (reserved_stack_activation() != stack_base()) {
1553 set_reserved_stack_activation(stack_base());
1554 }
1555 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1556 set_reserved_stack_activation(stack_base());
1557 enable_stack_reserved_zone();
1558 }
1559 return true;
1560 }
1561
1562 bool JavaThread::reguard_stack(void) {
1563 return reguard_stack(os::current_stack_pointer());
1564 }
1565
1566
1567 void JavaThread::block_if_vm_exited() {
1568 if (_terminated == _vm_exited) {
1569 // _vm_exited is set at safepoint, and Threads_lock is never released
1570 // we will block here forever
1571 Threads_lock->lock_without_safepoint_check();
1572 ShouldNotReachHere();
1573 }
1574 }
1575
1576
1577 // Remove this ifdef when C1 is ported to the compiler interface.
1578 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1579 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1580
1581 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1582 Thread()
1583 #if INCLUDE_ALL_GCS
1584 , _satb_mark_queue(&_satb_mark_queue_set),
1585 _dirty_card_queue(&_dirty_card_queue_set),
1586 _evacuation_in_progress(_evacuation_in_progress_global)
1587 #endif // INCLUDE_ALL_GCS
1588 {
1589 initialize();
1590 _jni_attach_state = _not_attaching_via_jni;
1591 set_entry_point(entry_point);
1592 // Create the native thread itself.
1593 // %note runtime_23
1594 os::ThreadType thr_type = os::java_thread;
1595 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1596 os::java_thread;
1597 os::create_thread(this, thr_type, stack_sz);
1598 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1599 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1600 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1601 // the exception consists of creating the exception object & initializing it, initialization
1602 // will leave the VM via a JavaCall and then all locks must be unlocked).
1603 //
1604 // The thread is still suspended when we reach here. Thread must be explicit started
1605 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1606 // by calling Threads:add. The reason why this is not done here, is because the thread
1607 // object must be fully initialized (take a look at JVM_Start)
1608 }
1609
1610 JavaThread::~JavaThread() {
1611
1612 // JSR166 -- return the parker to the free list
1613 Parker::Release(_parker);
1614 _parker = NULL;
1615
1616 // Free any remaining previous UnrollBlock
1617 vframeArray* old_array = vframe_array_last();
1618
1619 if (old_array != NULL) {
1620 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1621 old_array->set_unroll_block(NULL);
1622 delete old_info;
1623 delete old_array;
1624 }
1625
1626 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1627 if (deferred != NULL) {
1628 // This can only happen if thread is destroyed before deoptimization occurs.
1629 assert(deferred->length() != 0, "empty array!");
1630 do {
1631 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1632 deferred->remove_at(0);
1633 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1634 delete dlv;
1635 } while (deferred->length() != 0);
1636 delete deferred;
1637 }
1638
1639 // All Java related clean up happens in exit
1640 ThreadSafepointState::destroy(this);
1641 if (_thread_stat != NULL) delete _thread_stat;
1642
1643 #if INCLUDE_JVMCI
1644 if (JVMCICounterSize > 0) {
1645 if (jvmci_counters_include(this)) {
1646 for (int i = 0; i < JVMCICounterSize; i++) {
1647 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1648 }
1649 }
1650 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1651 }
1652 #endif // INCLUDE_JVMCI
1653 }
1654
1655
1656 // The first routine called by a new Java thread
1657 void JavaThread::run() {
1658 // initialize thread-local alloc buffer related fields
1659 this->initialize_tlab();
1660
1661 // used to test validity of stack trace backs
1662 this->record_base_of_stack_pointer();
1663
1664 // Record real stack base and size.
1665 this->record_stack_base_and_size();
1666
1667 this->create_stack_guard_pages();
1668
1669 this->cache_global_variables();
1670
1671 // Thread is now sufficient initialized to be handled by the safepoint code as being
1672 // in the VM. Change thread state from _thread_new to _thread_in_vm
1673 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1674
1675 assert(JavaThread::current() == this, "sanity check");
1676 assert(!Thread::current()->owns_locks(), "sanity check");
1677
1678 DTRACE_THREAD_PROBE(start, this);
1679
1680 // This operation might block. We call that after all safepoint checks for a new thread has
1681 // been completed.
1682 this->set_active_handles(JNIHandleBlock::allocate_block());
1683
1684 if (JvmtiExport::should_post_thread_life()) {
1685 JvmtiExport::post_thread_start(this);
1686 }
1687
1688 EventThreadStart event;
1689 if (event.should_commit()) {
1690 event.set_thread(THREAD_TRACE_ID(this));
1691 event.commit();
1692 }
1693
1694 // We call another function to do the rest so we are sure that the stack addresses used
1695 // from there will be lower than the stack base just computed
1696 thread_main_inner();
1697
1698 // Note, thread is no longer valid at this point!
1699 }
1700
1701
1702 void JavaThread::thread_main_inner() {
1703 assert(JavaThread::current() == this, "sanity check");
1704 assert(this->threadObj() != NULL, "just checking");
1705
1706 // Execute thread entry point unless this thread has a pending exception
1707 // or has been stopped before starting.
1708 // Note: Due to JVM_StopThread we can have pending exceptions already!
1709 if (!this->has_pending_exception() &&
1710 !java_lang_Thread::is_stillborn(this->threadObj())) {
1711 {
1712 ResourceMark rm(this);
1713 this->set_native_thread_name(this->get_thread_name());
1714 }
1715 HandleMark hm(this);
1716 this->entry_point()(this, this);
1717 }
1718
1719 DTRACE_THREAD_PROBE(stop, this);
1720
1721 this->exit(false);
1722 delete this;
1723 }
1724
1725
1726 static void ensure_join(JavaThread* thread) {
1727 // We do not need to grap the Threads_lock, since we are operating on ourself.
1728 Handle threadObj(thread, thread->threadObj());
1729 assert(threadObj.not_null(), "java thread object must exist");
1730 ObjectLocker lock(threadObj, thread);
1731 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1732 thread->clear_pending_exception();
1733 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1734 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1735 // Clear the native thread instance - this makes isAlive return false and allows the join()
1736 // to complete once we've done the notify_all below
1737 java_lang_Thread::set_thread(threadObj(), NULL);
1738 lock.notify_all(thread);
1739 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1740 thread->clear_pending_exception();
1741 }
1742
1743
1744 // For any new cleanup additions, please check to see if they need to be applied to
1745 // cleanup_failed_attach_current_thread as well.
1746 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1747 assert(this == JavaThread::current(), "thread consistency check");
1748
1749 HandleMark hm(this);
1750 Handle uncaught_exception(this, this->pending_exception());
1751 this->clear_pending_exception();
1752 Handle threadObj(this, this->threadObj());
1753 assert(threadObj.not_null(), "Java thread object should be created");
1754
1755 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1756 {
1757 EXCEPTION_MARK;
1758
1759 CLEAR_PENDING_EXCEPTION;
1760 }
1761 if (!destroy_vm) {
1762 if (uncaught_exception.not_null()) {
1763 EXCEPTION_MARK;
1764 // Call method Thread.dispatchUncaughtException().
1765 Klass* thread_klass = SystemDictionary::Thread_klass();
1766 JavaValue result(T_VOID);
1767 JavaCalls::call_virtual(&result,
1768 threadObj, thread_klass,
1769 vmSymbols::dispatchUncaughtException_name(),
1770 vmSymbols::throwable_void_signature(),
1771 uncaught_exception,
1772 THREAD);
1773 if (HAS_PENDING_EXCEPTION) {
1774 ResourceMark rm(this);
1775 jio_fprintf(defaultStream::error_stream(),
1776 "\nException: %s thrown from the UncaughtExceptionHandler"
1777 " in thread \"%s\"\n",
1778 pending_exception()->klass()->external_name(),
1779 get_thread_name());
1780 CLEAR_PENDING_EXCEPTION;
1781 }
1782 }
1783
1784 // Called before the java thread exit since we want to read info
1785 // from java_lang_Thread object
1786 EventThreadEnd event;
1787 if (event.should_commit()) {
1788 event.set_thread(THREAD_TRACE_ID(this));
1789 event.commit();
1790 }
1791
1792 // Call after last event on thread
1793 EVENT_THREAD_EXIT(this);
1794
1795 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1796 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1797 // is deprecated anyhow.
1798 if (!is_Compiler_thread()) {
1799 int count = 3;
1800 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1801 EXCEPTION_MARK;
1802 JavaValue result(T_VOID);
1803 Klass* thread_klass = SystemDictionary::Thread_klass();
1804 JavaCalls::call_virtual(&result,
1805 threadObj, thread_klass,
1806 vmSymbols::exit_method_name(),
1807 vmSymbols::void_method_signature(),
1808 THREAD);
1809 CLEAR_PENDING_EXCEPTION;
1810 }
1811 }
1812 // notify JVMTI
1813 if (JvmtiExport::should_post_thread_life()) {
1814 JvmtiExport::post_thread_end(this);
1815 }
1816
1817 // We have notified the agents that we are exiting, before we go on,
1818 // we must check for a pending external suspend request and honor it
1819 // in order to not surprise the thread that made the suspend request.
1820 while (true) {
1821 {
1822 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1823 if (!is_external_suspend()) {
1824 set_terminated(_thread_exiting);
1825 ThreadService::current_thread_exiting(this);
1826 break;
1827 }
1828 // Implied else:
1829 // Things get a little tricky here. We have a pending external
1830 // suspend request, but we are holding the SR_lock so we
1831 // can't just self-suspend. So we temporarily drop the lock
1832 // and then self-suspend.
1833 }
1834
1835 ThreadBlockInVM tbivm(this);
1836 java_suspend_self();
1837
1838 // We're done with this suspend request, but we have to loop around
1839 // and check again. Eventually we will get SR_lock without a pending
1840 // external suspend request and will be able to mark ourselves as
1841 // exiting.
1842 }
1843 // no more external suspends are allowed at this point
1844 } else {
1845 // before_exit() has already posted JVMTI THREAD_END events
1846 }
1847
1848 // Notify waiters on thread object. This has to be done after exit() is called
1849 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1850 // group should have the destroyed bit set before waiters are notified).
1851 ensure_join(this);
1852 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1853
1854 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1855 // held by this thread must be released. The spec does not distinguish
1856 // between JNI-acquired and regular Java monitors. We can only see
1857 // regular Java monitors here if monitor enter-exit matching is broken.
1858 //
1859 // Optionally release any monitors for regular JavaThread exits. This
1860 // is provided as a work around for any bugs in monitor enter-exit
1861 // matching. This can be expensive so it is not enabled by default.
1862 //
1863 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1864 // ObjectSynchronizer::release_monitors_owned_by_thread().
1865 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1866 // Sanity check even though JNI DetachCurrentThread() would have
1867 // returned JNI_ERR if there was a Java frame. JavaThread exit
1868 // should be done executing Java code by the time we get here.
1869 assert(!this->has_last_Java_frame(),
1870 "should not have a Java frame when detaching or exiting");
1871 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1872 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1873 }
1874
1875 // These things needs to be done while we are still a Java Thread. Make sure that thread
1876 // is in a consistent state, in case GC happens
1877 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1878
1879 if (active_handles() != NULL) {
1880 JNIHandleBlock* block = active_handles();
1881 set_active_handles(NULL);
1882 JNIHandleBlock::release_block(block);
1883 }
1884
1885 if (free_handle_block() != NULL) {
1886 JNIHandleBlock* block = free_handle_block();
1887 set_free_handle_block(NULL);
1888 JNIHandleBlock::release_block(block);
1889 }
1890
1891 // These have to be removed while this is still a valid thread.
1892 remove_stack_guard_pages();
1893
1894 if (UseTLAB) {
1895 tlab().make_parsable(true); // retire TLAB
1896 }
1897
1898 if (JvmtiEnv::environments_might_exist()) {
1899 JvmtiExport::cleanup_thread(this);
1900 }
1901
1902 // We must flush any deferred card marks before removing a thread from
1903 // the list of active threads.
1904 Universe::heap()->flush_deferred_store_barrier(this);
1905 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1906
1907 #if INCLUDE_ALL_GCS
1908 // We must flush the G1-related buffers before removing a thread
1909 // from the list of active threads. We must do this after any deferred
1910 // card marks have been flushed (above) so that any entries that are
1911 // added to the thread's dirty card queue as a result are not lost.
1912 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
1913 flush_barrier_queues();
1914 }
1915 if (UseShenandoahGC && UseTLAB && gclab().is_initialized()) {
1916 gclab().make_parsable(true);
1917 }
1918 #endif // INCLUDE_ALL_GCS
1919
1920 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1921 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1922 os::current_thread_id());
1923
1924 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1925 Threads::remove(this);
1926 }
1927
1928 #if INCLUDE_ALL_GCS
1929 // Flush G1-related queues.
1930 void JavaThread::flush_barrier_queues() {
1931 satb_mark_queue().flush();
1932 dirty_card_queue().flush();
1933 }
1934
1935 void JavaThread::initialize_queues() {
1936 assert(!SafepointSynchronize::is_at_safepoint(),
1937 "we should not be at a safepoint");
1938
1939 SATBMarkQueue& satb_queue = satb_mark_queue();
1940 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1941 // The SATB queue should have been constructed with its active
1942 // field set to false.
1943 assert(!satb_queue.is_active(), "SATB queue should not be active");
1944 assert(satb_queue.is_empty(), "SATB queue should be empty");
1945 // If we are creating the thread during a marking cycle, we should
1946 // set the active field of the SATB queue to true.
1947 if (satb_queue_set.is_active()) {
1948 satb_queue.set_active(true);
1949 }
1950
1951 DirtyCardQueue& dirty_queue = dirty_card_queue();
1952 // The dirty card queue should have been constructed with its
1953 // active field set to true.
1954 assert(dirty_queue.is_active(), "dirty card queue should be active");
1955
1956 _evacuation_in_progress = _evacuation_in_progress_global;
1957 }
1958
1959 bool JavaThread::evacuation_in_progress() const {
1960 return _evacuation_in_progress;
1961 }
1962
1963 void JavaThread::set_evacuation_in_progress(bool in_prog) {
1964 _evacuation_in_progress = in_prog;
1965 }
1966
1967 void JavaThread::set_evacuation_in_progress_all_threads(bool in_prog) {
1968 assert_locked_or_safepoint(Threads_lock);
1969 _evacuation_in_progress_global = in_prog;
1970 for (JavaThread* t = Threads::first(); t != NULL; t = t->next()) {
1971 t->set_evacuation_in_progress(in_prog);
1972 }
1973 }
1974 #endif // INCLUDE_ALL_GCS
1975
1976 void JavaThread::cleanup_failed_attach_current_thread() {
1977 if (active_handles() != NULL) {
1978 JNIHandleBlock* block = active_handles();
1979 set_active_handles(NULL);
1980 JNIHandleBlock::release_block(block);
1981 }
1982
1983 if (free_handle_block() != NULL) {
1984 JNIHandleBlock* block = free_handle_block();
1985 set_free_handle_block(NULL);
1986 JNIHandleBlock::release_block(block);
1987 }
1988
1989 // These have to be removed while this is still a valid thread.
1990 remove_stack_guard_pages();
1991
1992 if (UseTLAB) {
1993 tlab().make_parsable(true); // retire TLAB, if any
1994 }
1995
1996 #if INCLUDE_ALL_GCS
1997 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
1998 flush_barrier_queues();
1999 }
2000 if (UseShenandoahGC && UseTLAB && gclab().is_initialized()) {
2001 gclab().make_parsable(true);
2002 }
2003 #endif // INCLUDE_ALL_GCS
2004
2005 Threads::remove(this);
2006 delete this;
2007 }
2008
2009
2010
2011
2012 JavaThread* JavaThread::active() {
2013 Thread* thread = Thread::current();
2014 if (thread->is_Java_thread()) {
2015 return (JavaThread*) thread;
2016 } else {
2017 assert(thread->is_VM_thread(), "this must be a vm thread");
2018 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2019 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2020 assert(ret->is_Java_thread(), "must be a Java thread");
2021 return ret;
2022 }
2023 }
2024
2025 bool JavaThread::is_lock_owned(address adr) const {
2026 if (Thread::is_lock_owned(adr)) return true;
2027
2028 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2029 if (chunk->contains(adr)) return true;
2030 }
2031
2032 return false;
2033 }
2034
2035
2036 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2037 chunk->set_next(monitor_chunks());
2038 set_monitor_chunks(chunk);
2039 }
2040
2041 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2042 guarantee(monitor_chunks() != NULL, "must be non empty");
2043 if (monitor_chunks() == chunk) {
2044 set_monitor_chunks(chunk->next());
2045 } else {
2046 MonitorChunk* prev = monitor_chunks();
2047 while (prev->next() != chunk) prev = prev->next();
2048 prev->set_next(chunk->next());
2049 }
2050 }
2051
2052 // JVM support.
2053
2054 // Note: this function shouldn't block if it's called in
2055 // _thread_in_native_trans state (such as from
2056 // check_special_condition_for_native_trans()).
2057 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2058
2059 if (has_last_Java_frame() && has_async_condition()) {
2060 // If we are at a polling page safepoint (not a poll return)
2061 // then we must defer async exception because live registers
2062 // will be clobbered by the exception path. Poll return is
2063 // ok because the call we a returning from already collides
2064 // with exception handling registers and so there is no issue.
2065 // (The exception handling path kills call result registers but
2066 // this is ok since the exception kills the result anyway).
2067
2068 if (is_at_poll_safepoint()) {
2069 // if the code we are returning to has deoptimized we must defer
2070 // the exception otherwise live registers get clobbered on the
2071 // exception path before deoptimization is able to retrieve them.
2072 //
2073 RegisterMap map(this, false);
2074 frame caller_fr = last_frame().sender(&map);
2075 assert(caller_fr.is_compiled_frame(), "what?");
2076 if (caller_fr.is_deoptimized_frame()) {
2077 log_info(exceptions)("deferred async exception at compiled safepoint");
2078 return;
2079 }
2080 }
2081 }
2082
2083 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2084 if (condition == _no_async_condition) {
2085 // Conditions have changed since has_special_runtime_exit_condition()
2086 // was called:
2087 // - if we were here only because of an external suspend request,
2088 // then that was taken care of above (or cancelled) so we are done
2089 // - if we were here because of another async request, then it has
2090 // been cleared between the has_special_runtime_exit_condition()
2091 // and now so again we are done
2092 return;
2093 }
2094
2095 // Check for pending async. exception
2096 if (_pending_async_exception != NULL) {
2097 // Only overwrite an already pending exception, if it is not a threadDeath.
2098 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2099
2100 // We cannot call Exceptions::_throw(...) here because we cannot block
2101 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2102
2103 LogTarget(Info, exceptions) lt;
2104 if (lt.is_enabled()) {
2105 ResourceMark rm;
2106 LogStream ls(lt);
2107 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2108 if (has_last_Java_frame()) {
2109 frame f = last_frame();
2110 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2111 }
2112 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2113 }
2114 _pending_async_exception = NULL;
2115 clear_has_async_exception();
2116 }
2117 }
2118
2119 if (check_unsafe_error &&
2120 condition == _async_unsafe_access_error && !has_pending_exception()) {
2121 condition = _no_async_condition; // done
2122 switch (thread_state()) {
2123 case _thread_in_vm: {
2124 JavaThread* THREAD = this;
2125 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2126 }
2127 case _thread_in_native: {
2128 ThreadInVMfromNative tiv(this);
2129 JavaThread* THREAD = this;
2130 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2131 }
2132 case _thread_in_Java: {
2133 ThreadInVMfromJava tiv(this);
2134 JavaThread* THREAD = this;
2135 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2136 }
2137 default:
2138 ShouldNotReachHere();
2139 }
2140 }
2141
2142 assert(condition == _no_async_condition || has_pending_exception() ||
2143 (!check_unsafe_error && condition == _async_unsafe_access_error),
2144 "must have handled the async condition, if no exception");
2145 }
2146
2147 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2148 //
2149 // Check for pending external suspend. Internal suspend requests do
2150 // not use handle_special_runtime_exit_condition().
2151 // If JNIEnv proxies are allowed, don't self-suspend if the target
2152 // thread is not the current thread. In older versions of jdbx, jdbx
2153 // threads could call into the VM with another thread's JNIEnv so we
2154 // can be here operating on behalf of a suspended thread (4432884).
2155 bool do_self_suspend = is_external_suspend_with_lock();
2156 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2157 //
2158 // Because thread is external suspended the safepoint code will count
2159 // thread as at a safepoint. This can be odd because we can be here
2160 // as _thread_in_Java which would normally transition to _thread_blocked
2161 // at a safepoint. We would like to mark the thread as _thread_blocked
2162 // before calling java_suspend_self like all other callers of it but
2163 // we must then observe proper safepoint protocol. (We can't leave
2164 // _thread_blocked with a safepoint in progress). However we can be
2165 // here as _thread_in_native_trans so we can't use a normal transition
2166 // constructor/destructor pair because they assert on that type of
2167 // transition. We could do something like:
2168 //
2169 // JavaThreadState state = thread_state();
2170 // set_thread_state(_thread_in_vm);
2171 // {
2172 // ThreadBlockInVM tbivm(this);
2173 // java_suspend_self()
2174 // }
2175 // set_thread_state(_thread_in_vm_trans);
2176 // if (safepoint) block;
2177 // set_thread_state(state);
2178 //
2179 // but that is pretty messy. Instead we just go with the way the
2180 // code has worked before and note that this is the only path to
2181 // java_suspend_self that doesn't put the thread in _thread_blocked
2182 // mode.
2183
2184 frame_anchor()->make_walkable(this);
2185 java_suspend_self();
2186
2187 // We might be here for reasons in addition to the self-suspend request
2188 // so check for other async requests.
2189 }
2190
2191 if (check_asyncs) {
2192 check_and_handle_async_exceptions();
2193 }
2194 #if INCLUDE_TRACE
2195 if (is_trace_suspend()) {
2196 TRACE_SUSPEND_THREAD(this);
2197 }
2198 #endif
2199 }
2200
2201 void JavaThread::send_thread_stop(oop java_throwable) {
2202 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2203 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2204 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2205
2206 // Do not throw asynchronous exceptions against the compiler thread
2207 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2208 if (!can_call_java()) return;
2209
2210 {
2211 // Actually throw the Throwable against the target Thread - however
2212 // only if there is no thread death exception installed already.
2213 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2214 // If the topmost frame is a runtime stub, then we are calling into
2215 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2216 // must deoptimize the caller before continuing, as the compiled exception handler table
2217 // may not be valid
2218 if (has_last_Java_frame()) {
2219 frame f = last_frame();
2220 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2221 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2222 RegisterMap reg_map(this, UseBiasedLocking);
2223 frame compiled_frame = f.sender(®_map);
2224 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2225 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2226 }
2227 }
2228 }
2229
2230 // Set async. pending exception in thread.
2231 set_pending_async_exception(java_throwable);
2232
2233 if (log_is_enabled(Info, exceptions)) {
2234 ResourceMark rm;
2235 log_info(exceptions)("Pending Async. exception installed of type: %s",
2236 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2237 }
2238 // for AbortVMOnException flag
2239 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2240 }
2241 }
2242
2243
2244 // Interrupt thread so it will wake up from a potential wait()
2245 Thread::interrupt(this);
2246 }
2247
2248 // External suspension mechanism.
2249 //
2250 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2251 // to any VM_locks and it is at a transition
2252 // Self-suspension will happen on the transition out of the vm.
2253 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2254 //
2255 // Guarantees on return:
2256 // + Target thread will not execute any new bytecode (that's why we need to
2257 // force a safepoint)
2258 // + Target thread will not enter any new monitors
2259 //
2260 void JavaThread::java_suspend() {
2261 { MutexLocker mu(Threads_lock);
2262 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2263 return;
2264 }
2265 }
2266
2267 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2268 if (!is_external_suspend()) {
2269 // a racing resume has cancelled us; bail out now
2270 return;
2271 }
2272
2273 // suspend is done
2274 uint32_t debug_bits = 0;
2275 // Warning: is_ext_suspend_completed() may temporarily drop the
2276 // SR_lock to allow the thread to reach a stable thread state if
2277 // it is currently in a transient thread state.
2278 if (is_ext_suspend_completed(false /* !called_by_wait */,
2279 SuspendRetryDelay, &debug_bits)) {
2280 return;
2281 }
2282 }
2283
2284 VM_ThreadSuspend vm_suspend;
2285 VMThread::execute(&vm_suspend);
2286 }
2287
2288 // Part II of external suspension.
2289 // A JavaThread self suspends when it detects a pending external suspend
2290 // request. This is usually on transitions. It is also done in places
2291 // where continuing to the next transition would surprise the caller,
2292 // e.g., monitor entry.
2293 //
2294 // Returns the number of times that the thread self-suspended.
2295 //
2296 // Note: DO NOT call java_suspend_self() when you just want to block current
2297 // thread. java_suspend_self() is the second stage of cooperative
2298 // suspension for external suspend requests and should only be used
2299 // to complete an external suspend request.
2300 //
2301 int JavaThread::java_suspend_self() {
2302 int ret = 0;
2303
2304 // we are in the process of exiting so don't suspend
2305 if (is_exiting()) {
2306 clear_external_suspend();
2307 return ret;
2308 }
2309
2310 assert(_anchor.walkable() ||
2311 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2312 "must have walkable stack");
2313
2314 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2315
2316 assert(!this->is_ext_suspended(),
2317 "a thread trying to self-suspend should not already be suspended");
2318
2319 if (this->is_suspend_equivalent()) {
2320 // If we are self-suspending as a result of the lifting of a
2321 // suspend equivalent condition, then the suspend_equivalent
2322 // flag is not cleared until we set the ext_suspended flag so
2323 // that wait_for_ext_suspend_completion() returns consistent
2324 // results.
2325 this->clear_suspend_equivalent();
2326 }
2327
2328 // A racing resume may have cancelled us before we grabbed SR_lock
2329 // above. Or another external suspend request could be waiting for us
2330 // by the time we return from SR_lock()->wait(). The thread
2331 // that requested the suspension may already be trying to walk our
2332 // stack and if we return now, we can change the stack out from under
2333 // it. This would be a "bad thing (TM)" and cause the stack walker
2334 // to crash. We stay self-suspended until there are no more pending
2335 // external suspend requests.
2336 while (is_external_suspend()) {
2337 ret++;
2338 this->set_ext_suspended();
2339
2340 // _ext_suspended flag is cleared by java_resume()
2341 while (is_ext_suspended()) {
2342 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2343 }
2344 }
2345
2346 return ret;
2347 }
2348
2349 #ifdef ASSERT
2350 // verify the JavaThread has not yet been published in the Threads::list, and
2351 // hence doesn't need protection from concurrent access at this stage
2352 void JavaThread::verify_not_published() {
2353 if (!Threads_lock->owned_by_self()) {
2354 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2355 assert(!Threads::includes(this),
2356 "java thread shouldn't have been published yet!");
2357 } else {
2358 assert(!Threads::includes(this),
2359 "java thread shouldn't have been published yet!");
2360 }
2361 }
2362 #endif
2363
2364 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2365 // progress or when _suspend_flags is non-zero.
2366 // Current thread needs to self-suspend if there is a suspend request and/or
2367 // block if a safepoint is in progress.
2368 // Async exception ISN'T checked.
2369 // Note only the ThreadInVMfromNative transition can call this function
2370 // directly and when thread state is _thread_in_native_trans
2371 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2372 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2373
2374 JavaThread *curJT = JavaThread::current();
2375 bool do_self_suspend = thread->is_external_suspend();
2376
2377 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2378
2379 // If JNIEnv proxies are allowed, don't self-suspend if the target
2380 // thread is not the current thread. In older versions of jdbx, jdbx
2381 // threads could call into the VM with another thread's JNIEnv so we
2382 // can be here operating on behalf of a suspended thread (4432884).
2383 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2384 JavaThreadState state = thread->thread_state();
2385
2386 // We mark this thread_blocked state as a suspend-equivalent so
2387 // that a caller to is_ext_suspend_completed() won't be confused.
2388 // The suspend-equivalent state is cleared by java_suspend_self().
2389 thread->set_suspend_equivalent();
2390
2391 // If the safepoint code sees the _thread_in_native_trans state, it will
2392 // wait until the thread changes to other thread state. There is no
2393 // guarantee on how soon we can obtain the SR_lock and complete the
2394 // self-suspend request. It would be a bad idea to let safepoint wait for
2395 // too long. Temporarily change the state to _thread_blocked to
2396 // let the VM thread know that this thread is ready for GC. The problem
2397 // of changing thread state is that safepoint could happen just after
2398 // java_suspend_self() returns after being resumed, and VM thread will
2399 // see the _thread_blocked state. We must check for safepoint
2400 // after restoring the state and make sure we won't leave while a safepoint
2401 // is in progress.
2402 thread->set_thread_state(_thread_blocked);
2403 thread->java_suspend_self();
2404 thread->set_thread_state(state);
2405
2406 InterfaceSupport::serialize_thread_state_with_handler(thread);
2407 }
2408
2409 if (SafepointSynchronize::do_call_back()) {
2410 // If we are safepointing, then block the caller which may not be
2411 // the same as the target thread (see above).
2412 SafepointSynchronize::block(curJT);
2413 }
2414
2415 if (thread->is_deopt_suspend()) {
2416 thread->clear_deopt_suspend();
2417 RegisterMap map(thread, false);
2418 frame f = thread->last_frame();
2419 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2420 f = f.sender(&map);
2421 }
2422 if (f.id() == thread->must_deopt_id()) {
2423 thread->clear_must_deopt_id();
2424 f.deoptimize(thread);
2425 } else {
2426 fatal("missed deoptimization!");
2427 }
2428 }
2429 #if INCLUDE_TRACE
2430 if (thread->is_trace_suspend()) {
2431 TRACE_SUSPEND_THREAD(thread);
2432 }
2433 #endif
2434 }
2435
2436 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2437 // progress or when _suspend_flags is non-zero.
2438 // Current thread needs to self-suspend if there is a suspend request and/or
2439 // block if a safepoint is in progress.
2440 // Also check for pending async exception (not including unsafe access error).
2441 // Note only the native==>VM/Java barriers can call this function and when
2442 // thread state is _thread_in_native_trans.
2443 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2444 check_safepoint_and_suspend_for_native_trans(thread);
2445
2446 if (thread->has_async_exception()) {
2447 // We are in _thread_in_native_trans state, don't handle unsafe
2448 // access error since that may block.
2449 thread->check_and_handle_async_exceptions(false);
2450 }
2451 }
2452
2453 // This is a variant of the normal
2454 // check_special_condition_for_native_trans with slightly different
2455 // semantics for use by critical native wrappers. It does all the
2456 // normal checks but also performs the transition back into
2457 // thread_in_Java state. This is required so that critical natives
2458 // can potentially block and perform a GC if they are the last thread
2459 // exiting the GCLocker.
2460 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2461 check_special_condition_for_native_trans(thread);
2462
2463 // Finish the transition
2464 thread->set_thread_state(_thread_in_Java);
2465
2466 if (thread->do_critical_native_unlock()) {
2467 ThreadInVMfromJavaNoAsyncException tiv(thread);
2468 GCLocker::unlock_critical(thread);
2469 thread->clear_critical_native_unlock();
2470 }
2471 }
2472
2473 // We need to guarantee the Threads_lock here, since resumes are not
2474 // allowed during safepoint synchronization
2475 // Can only resume from an external suspension
2476 void JavaThread::java_resume() {
2477 assert_locked_or_safepoint(Threads_lock);
2478
2479 // Sanity check: thread is gone, has started exiting or the thread
2480 // was not externally suspended.
2481 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2482 return;
2483 }
2484
2485 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2486
2487 clear_external_suspend();
2488
2489 if (is_ext_suspended()) {
2490 clear_ext_suspended();
2491 SR_lock()->notify_all();
2492 }
2493 }
2494
2495 size_t JavaThread::_stack_red_zone_size = 0;
2496 size_t JavaThread::_stack_yellow_zone_size = 0;
2497 size_t JavaThread::_stack_reserved_zone_size = 0;
2498 size_t JavaThread::_stack_shadow_zone_size = 0;
2499
2500 void JavaThread::create_stack_guard_pages() {
2501 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2502 address low_addr = stack_end();
2503 size_t len = stack_guard_zone_size();
2504
2505 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2506 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2507
2508 int must_commit = os::must_commit_stack_guard_pages();
2509 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2510
2511 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2512 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2513 return;
2514 }
2515
2516 if (os::guard_memory((char *) low_addr, len)) {
2517 _stack_guard_state = stack_guard_enabled;
2518 } else {
2519 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2520 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2521 if (os::uncommit_memory((char *) low_addr, len)) {
2522 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2523 }
2524 return;
2525 }
2526
2527 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2528 PTR_FORMAT "-" PTR_FORMAT ".",
2529 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2530 }
2531
2532 void JavaThread::remove_stack_guard_pages() {
2533 assert(Thread::current() == this, "from different thread");
2534 if (_stack_guard_state == stack_guard_unused) return;
2535 address low_addr = stack_end();
2536 size_t len = stack_guard_zone_size();
2537
2538 if (os::must_commit_stack_guard_pages()) {
2539 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2540 _stack_guard_state = stack_guard_unused;
2541 } else {
2542 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2543 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2544 return;
2545 }
2546 } else {
2547 if (_stack_guard_state == stack_guard_unused) return;
2548 if (os::unguard_memory((char *) low_addr, len)) {
2549 _stack_guard_state = stack_guard_unused;
2550 } else {
2551 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2552 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2553 return;
2554 }
2555 }
2556
2557 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2558 PTR_FORMAT "-" PTR_FORMAT ".",
2559 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2560 }
2561
2562 void JavaThread::enable_stack_reserved_zone() {
2563 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2564 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2565
2566 // The base notation is from the stack's point of view, growing downward.
2567 // We need to adjust it to work correctly with guard_memory()
2568 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2569
2570 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2571 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2572
2573 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2574 _stack_guard_state = stack_guard_enabled;
2575 } else {
2576 warning("Attempt to guard stack reserved zone failed.");
2577 }
2578 enable_register_stack_guard();
2579 }
2580
2581 void JavaThread::disable_stack_reserved_zone() {
2582 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2583 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2584
2585 // Simply return if called for a thread that does not use guard pages.
2586 if (_stack_guard_state == stack_guard_unused) return;
2587
2588 // The base notation is from the stack's point of view, growing downward.
2589 // We need to adjust it to work correctly with guard_memory()
2590 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2591
2592 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2593 _stack_guard_state = stack_guard_reserved_disabled;
2594 } else {
2595 warning("Attempt to unguard stack reserved zone failed.");
2596 }
2597 disable_register_stack_guard();
2598 }
2599
2600 void JavaThread::enable_stack_yellow_reserved_zone() {
2601 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2602 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2603
2604 // The base notation is from the stacks point of view, growing downward.
2605 // We need to adjust it to work correctly with guard_memory()
2606 address base = stack_red_zone_base();
2607
2608 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2609 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2610
2611 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2612 _stack_guard_state = stack_guard_enabled;
2613 } else {
2614 warning("Attempt to guard stack yellow zone failed.");
2615 }
2616 enable_register_stack_guard();
2617 }
2618
2619 void JavaThread::disable_stack_yellow_reserved_zone() {
2620 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2621 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2622
2623 // Simply return if called for a thread that does not use guard pages.
2624 if (_stack_guard_state == stack_guard_unused) return;
2625
2626 // The base notation is from the stacks point of view, growing downward.
2627 // We need to adjust it to work correctly with guard_memory()
2628 address base = stack_red_zone_base();
2629
2630 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2631 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2632 } else {
2633 warning("Attempt to unguard stack yellow zone failed.");
2634 }
2635 disable_register_stack_guard();
2636 }
2637
2638 void JavaThread::enable_stack_red_zone() {
2639 // The base notation is from the stacks point of view, growing downward.
2640 // We need to adjust it to work correctly with guard_memory()
2641 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2642 address base = stack_red_zone_base() - stack_red_zone_size();
2643
2644 guarantee(base < stack_base(), "Error calculating stack red zone");
2645 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2646
2647 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2648 warning("Attempt to guard stack red zone failed.");
2649 }
2650 }
2651
2652 void JavaThread::disable_stack_red_zone() {
2653 // The base notation is from the stacks point of view, growing downward.
2654 // We need to adjust it to work correctly with guard_memory()
2655 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2656 address base = stack_red_zone_base() - stack_red_zone_size();
2657 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2658 warning("Attempt to unguard stack red zone failed.");
2659 }
2660 }
2661
2662 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2663 // ignore is there is no stack
2664 if (!has_last_Java_frame()) return;
2665 // traverse the stack frames. Starts from top frame.
2666 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2667 frame* fr = fst.current();
2668 f(fr, fst.register_map());
2669 }
2670 }
2671
2672
2673 #ifndef PRODUCT
2674 // Deoptimization
2675 // Function for testing deoptimization
2676 void JavaThread::deoptimize() {
2677 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2678 StackFrameStream fst(this, UseBiasedLocking);
2679 bool deopt = false; // Dump stack only if a deopt actually happens.
2680 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2681 // Iterate over all frames in the thread and deoptimize
2682 for (; !fst.is_done(); fst.next()) {
2683 if (fst.current()->can_be_deoptimized()) {
2684
2685 if (only_at) {
2686 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2687 // consists of comma or carriage return separated numbers so
2688 // search for the current bci in that string.
2689 address pc = fst.current()->pc();
2690 nmethod* nm = (nmethod*) fst.current()->cb();
2691 ScopeDesc* sd = nm->scope_desc_at(pc);
2692 char buffer[8];
2693 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2694 size_t len = strlen(buffer);
2695 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2696 while (found != NULL) {
2697 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2698 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2699 // Check that the bci found is bracketed by terminators.
2700 break;
2701 }
2702 found = strstr(found + 1, buffer);
2703 }
2704 if (!found) {
2705 continue;
2706 }
2707 }
2708
2709 if (DebugDeoptimization && !deopt) {
2710 deopt = true; // One-time only print before deopt
2711 tty->print_cr("[BEFORE Deoptimization]");
2712 trace_frames();
2713 trace_stack();
2714 }
2715 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2716 }
2717 }
2718
2719 if (DebugDeoptimization && deopt) {
2720 tty->print_cr("[AFTER Deoptimization]");
2721 trace_frames();
2722 }
2723 }
2724
2725
2726 // Make zombies
2727 void JavaThread::make_zombies() {
2728 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2729 if (fst.current()->can_be_deoptimized()) {
2730 // it is a Java nmethod
2731 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2732 nm->make_not_entrant();
2733 }
2734 }
2735 }
2736 #endif // PRODUCT
2737
2738
2739 void JavaThread::deoptimized_wrt_marked_nmethods() {
2740 if (!has_last_Java_frame()) return;
2741 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2742 StackFrameStream fst(this, UseBiasedLocking);
2743 for (; !fst.is_done(); fst.next()) {
2744 if (fst.current()->should_be_deoptimized()) {
2745 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2746 }
2747 }
2748 }
2749
2750
2751 // If the caller is a NamedThread, then remember, in the current scope,
2752 // the given JavaThread in its _processed_thread field.
2753 class RememberProcessedThread: public StackObj {
2754 NamedThread* _cur_thr;
2755 public:
2756 RememberProcessedThread(JavaThread* jthr) {
2757 Thread* thread = Thread::current();
2758 if (thread->is_Named_thread()) {
2759 _cur_thr = (NamedThread *)thread;
2760 _cur_thr->set_processed_thread(jthr);
2761 } else {
2762 _cur_thr = NULL;
2763 }
2764 }
2765
2766 ~RememberProcessedThread() {
2767 if (_cur_thr) {
2768 _cur_thr->set_processed_thread(NULL);
2769 }
2770 }
2771 };
2772
2773 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2774 // Verify that the deferred card marks have been flushed.
2775 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2776
2777 // Traverse the GCHandles
2778 Thread::oops_do(f, cf);
2779
2780 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2781
2782 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2783 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2784
2785 if (has_last_Java_frame()) {
2786 // Record JavaThread to GC thread
2787 RememberProcessedThread rpt(this);
2788
2789 // Traverse the privileged stack
2790 if (_privileged_stack_top != NULL) {
2791 _privileged_stack_top->oops_do(f);
2792 }
2793
2794 // traverse the registered growable array
2795 if (_array_for_gc != NULL) {
2796 for (int index = 0; index < _array_for_gc->length(); index++) {
2797 f->do_oop(_array_for_gc->adr_at(index));
2798 }
2799 }
2800
2801 // Traverse the monitor chunks
2802 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2803 chunk->oops_do(f);
2804 }
2805
2806 // Traverse the execution stack
2807 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2808 fst.current()->oops_do(f, cf, fst.register_map());
2809 }
2810 }
2811
2812 // callee_target is never live across a gc point so NULL it here should
2813 // it still contain a methdOop.
2814
2815 set_callee_target(NULL);
2816
2817 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2818 // If we have deferred set_locals there might be oops waiting to be
2819 // written
2820 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2821 if (list != NULL) {
2822 for (int i = 0; i < list->length(); i++) {
2823 list->at(i)->oops_do(f);
2824 }
2825 }
2826
2827 // Traverse instance variables at the end since the GC may be moving things
2828 // around using this function
2829 f->do_oop((oop*) &_threadObj);
2830 f->do_oop((oop*) &_vm_result);
2831 f->do_oop((oop*) &_exception_oop);
2832 f->do_oop((oop*) &_pending_async_exception);
2833
2834 if (jvmti_thread_state() != NULL) {
2835 jvmti_thread_state()->oops_do(f);
2836 }
2837 }
2838
2839 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2840 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2841 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2842
2843 if (has_last_Java_frame()) {
2844 // Traverse the execution stack
2845 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2846 fst.current()->nmethods_do(cf);
2847 }
2848 }
2849 }
2850
2851 void JavaThread::metadata_do(void f(Metadata*)) {
2852 if (has_last_Java_frame()) {
2853 // Traverse the execution stack to call f() on the methods in the stack
2854 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2855 fst.current()->metadata_do(f);
2856 }
2857 } else if (is_Compiler_thread()) {
2858 // need to walk ciMetadata in current compile tasks to keep alive.
2859 CompilerThread* ct = (CompilerThread*)this;
2860 if (ct->env() != NULL) {
2861 ct->env()->metadata_do(f);
2862 }
2863 if (ct->task() != NULL) {
2864 ct->task()->metadata_do(f);
2865 }
2866 }
2867 }
2868
2869 // Printing
2870 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2871 switch (_thread_state) {
2872 case _thread_uninitialized: return "_thread_uninitialized";
2873 case _thread_new: return "_thread_new";
2874 case _thread_new_trans: return "_thread_new_trans";
2875 case _thread_in_native: return "_thread_in_native";
2876 case _thread_in_native_trans: return "_thread_in_native_trans";
2877 case _thread_in_vm: return "_thread_in_vm";
2878 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2879 case _thread_in_Java: return "_thread_in_Java";
2880 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2881 case _thread_blocked: return "_thread_blocked";
2882 case _thread_blocked_trans: return "_thread_blocked_trans";
2883 default: return "unknown thread state";
2884 }
2885 }
2886
2887 #ifndef PRODUCT
2888 void JavaThread::print_thread_state_on(outputStream *st) const {
2889 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2890 };
2891 void JavaThread::print_thread_state() const {
2892 print_thread_state_on(tty);
2893 }
2894 #endif // PRODUCT
2895
2896 // Called by Threads::print() for VM_PrintThreads operation
2897 void JavaThread::print_on(outputStream *st) const {
2898 st->print_raw("\"");
2899 st->print_raw(get_thread_name());
2900 st->print_raw("\" ");
2901 oop thread_oop = threadObj();
2902 if (thread_oop != NULL) {
2903 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2904 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2905 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2906 }
2907 Thread::print_on(st);
2908 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2909 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2910 if (thread_oop != NULL) {
2911 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2912 }
2913 #ifndef PRODUCT
2914 print_thread_state_on(st);
2915 _safepoint_state->print_on(st);
2916 #endif // PRODUCT
2917 if (is_Compiler_thread()) {
2918 CompilerThread* ct = (CompilerThread*)this;
2919 if (ct->task() != NULL) {
2920 st->print(" Compiling: ");
2921 ct->task()->print(st, NULL, true, false);
2922 } else {
2923 st->print(" No compile task");
2924 }
2925 st->cr();
2926 }
2927 }
2928
2929 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2930 st->print("%s", get_thread_name_string(buf, buflen));
2931 }
2932
2933 // Called by fatal error handler. The difference between this and
2934 // JavaThread::print() is that we can't grab lock or allocate memory.
2935 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2936 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2937 oop thread_obj = threadObj();
2938 if (thread_obj != NULL) {
2939 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2940 }
2941 st->print(" [");
2942 st->print("%s", _get_thread_state_name(_thread_state));
2943 if (osthread()) {
2944 st->print(", id=%d", osthread()->thread_id());
2945 }
2946 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2947 p2i(stack_end()), p2i(stack_base()));
2948 st->print("]");
2949 return;
2950 }
2951
2952 // Verification
2953
2954 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2955
2956 void JavaThread::verify() {
2957 // Verify oops in the thread.
2958 oops_do(&VerifyOopClosure::verify_oop, NULL);
2959
2960 // Verify the stack frames.
2961 frames_do(frame_verify);
2962 }
2963
2964 // CR 6300358 (sub-CR 2137150)
2965 // Most callers of this method assume that it can't return NULL but a
2966 // thread may not have a name whilst it is in the process of attaching to
2967 // the VM - see CR 6412693, and there are places where a JavaThread can be
2968 // seen prior to having it's threadObj set (eg JNI attaching threads and
2969 // if vm exit occurs during initialization). These cases can all be accounted
2970 // for such that this method never returns NULL.
2971 const char* JavaThread::get_thread_name() const {
2972 #ifdef ASSERT
2973 // early safepoints can hit while current thread does not yet have TLS
2974 if (!SafepointSynchronize::is_at_safepoint()) {
2975 Thread *cur = Thread::current();
2976 if (!(cur->is_Java_thread() && cur == this)) {
2977 // Current JavaThreads are allowed to get their own name without
2978 // the Threads_lock.
2979 assert_locked_or_safepoint(Threads_lock);
2980 }
2981 }
2982 #endif // ASSERT
2983 return get_thread_name_string();
2984 }
2985
2986 // Returns a non-NULL representation of this thread's name, or a suitable
2987 // descriptive string if there is no set name
2988 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2989 const char* name_str;
2990 oop thread_obj = threadObj();
2991 if (thread_obj != NULL) {
2992 oop name = java_lang_Thread::name(thread_obj);
2993 if (name != NULL) {
2994 if (buf == NULL) {
2995 name_str = java_lang_String::as_utf8_string(name);
2996 } else {
2997 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2998 }
2999 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3000 name_str = "<no-name - thread is attaching>";
3001 } else {
3002 name_str = Thread::name();
3003 }
3004 } else {
3005 name_str = Thread::name();
3006 }
3007 assert(name_str != NULL, "unexpected NULL thread name");
3008 return name_str;
3009 }
3010
3011
3012 const char* JavaThread::get_threadgroup_name() const {
3013 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3014 oop thread_obj = threadObj();
3015 if (thread_obj != NULL) {
3016 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3017 if (thread_group != NULL) {
3018 // ThreadGroup.name can be null
3019 return java_lang_ThreadGroup::name(thread_group);
3020 }
3021 }
3022 return NULL;
3023 }
3024
3025 const char* JavaThread::get_parent_name() const {
3026 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3027 oop thread_obj = threadObj();
3028 if (thread_obj != NULL) {
3029 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3030 if (thread_group != NULL) {
3031 oop parent = java_lang_ThreadGroup::parent(thread_group);
3032 if (parent != NULL) {
3033 // ThreadGroup.name can be null
3034 return java_lang_ThreadGroup::name(parent);
3035 }
3036 }
3037 }
3038 return NULL;
3039 }
3040
3041 ThreadPriority JavaThread::java_priority() const {
3042 oop thr_oop = threadObj();
3043 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3044 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3045 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3046 return priority;
3047 }
3048
3049 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3050
3051 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3052 // Link Java Thread object <-> C++ Thread
3053
3054 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3055 // and put it into a new Handle. The Handle "thread_oop" can then
3056 // be used to pass the C++ thread object to other methods.
3057
3058 // Set the Java level thread object (jthread) field of the
3059 // new thread (a JavaThread *) to C++ thread object using the
3060 // "thread_oop" handle.
3061
3062 // Set the thread field (a JavaThread *) of the
3063 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3064
3065 Handle thread_oop(Thread::current(),
3066 JNIHandles::resolve_non_null(jni_thread));
3067 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3068 "must be initialized");
3069 set_threadObj(thread_oop());
3070 java_lang_Thread::set_thread(thread_oop(), this);
3071
3072 if (prio == NoPriority) {
3073 prio = java_lang_Thread::priority(thread_oop());
3074 assert(prio != NoPriority, "A valid priority should be present");
3075 }
3076
3077 // Push the Java priority down to the native thread; needs Threads_lock
3078 Thread::set_priority(this, prio);
3079
3080 prepare_ext();
3081
3082 // Add the new thread to the Threads list and set it in motion.
3083 // We must have threads lock in order to call Threads::add.
3084 // It is crucial that we do not block before the thread is
3085 // added to the Threads list for if a GC happens, then the java_thread oop
3086 // will not be visited by GC.
3087 Threads::add(this);
3088 }
3089
3090 oop JavaThread::current_park_blocker() {
3091 // Support for JSR-166 locks
3092 oop thread_oop = threadObj();
3093 if (thread_oop != NULL &&
3094 JDK_Version::current().supports_thread_park_blocker()) {
3095 return java_lang_Thread::park_blocker(thread_oop);
3096 }
3097 return NULL;
3098 }
3099
3100
3101 void JavaThread::print_stack_on(outputStream* st) {
3102 if (!has_last_Java_frame()) return;
3103 ResourceMark rm;
3104 HandleMark hm;
3105
3106 RegisterMap reg_map(this);
3107 vframe* start_vf = last_java_vframe(®_map);
3108 int count = 0;
3109 for (vframe* f = start_vf; f; f = f->sender()) {
3110 if (f->is_java_frame()) {
3111 javaVFrame* jvf = javaVFrame::cast(f);
3112 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3113
3114 // Print out lock information
3115 if (JavaMonitorsInStackTrace) {
3116 jvf->print_lock_info_on(st, count);
3117 }
3118 } else {
3119 // Ignore non-Java frames
3120 }
3121
3122 // Bail-out case for too deep stacks
3123 count++;
3124 if (MaxJavaStackTraceDepth == count) return;
3125 }
3126 }
3127
3128
3129 // JVMTI PopFrame support
3130 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3131 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3132 if (in_bytes(size_in_bytes) != 0) {
3133 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3134 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3135 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3136 }
3137 }
3138
3139 void* JavaThread::popframe_preserved_args() {
3140 return _popframe_preserved_args;
3141 }
3142
3143 ByteSize JavaThread::popframe_preserved_args_size() {
3144 return in_ByteSize(_popframe_preserved_args_size);
3145 }
3146
3147 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3148 int sz = in_bytes(popframe_preserved_args_size());
3149 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3150 return in_WordSize(sz / wordSize);
3151 }
3152
3153 void JavaThread::popframe_free_preserved_args() {
3154 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3155 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3156 _popframe_preserved_args = NULL;
3157 _popframe_preserved_args_size = 0;
3158 }
3159
3160 #ifndef PRODUCT
3161
3162 void JavaThread::trace_frames() {
3163 tty->print_cr("[Describe stack]");
3164 int frame_no = 1;
3165 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3166 tty->print(" %d. ", frame_no++);
3167 fst.current()->print_value_on(tty, this);
3168 tty->cr();
3169 }
3170 }
3171
3172 class PrintAndVerifyOopClosure: public OopClosure {
3173 protected:
3174 template <class T> inline void do_oop_work(T* p) {
3175 oop obj = oopDesc::load_decode_heap_oop(p);
3176 if (obj == NULL) return;
3177 tty->print(INTPTR_FORMAT ": ", p2i(p));
3178 if (oopDesc::is_oop_or_null(obj)) {
3179 if (obj->is_objArray()) {
3180 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3181 } else {
3182 obj->print();
3183 }
3184 } else {
3185 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3186 }
3187 tty->cr();
3188 }
3189 public:
3190 virtual void do_oop(oop* p) { do_oop_work(p); }
3191 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3192 };
3193
3194
3195 static void oops_print(frame* f, const RegisterMap *map) {
3196 PrintAndVerifyOopClosure print;
3197 f->print_value();
3198 f->oops_do(&print, NULL, (RegisterMap*)map);
3199 }
3200
3201 // Print our all the locations that contain oops and whether they are
3202 // valid or not. This useful when trying to find the oldest frame
3203 // where an oop has gone bad since the frame walk is from youngest to
3204 // oldest.
3205 void JavaThread::trace_oops() {
3206 tty->print_cr("[Trace oops]");
3207 frames_do(oops_print);
3208 }
3209
3210
3211 #ifdef ASSERT
3212 // Print or validate the layout of stack frames
3213 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3214 ResourceMark rm;
3215 PRESERVE_EXCEPTION_MARK;
3216 FrameValues values;
3217 int frame_no = 0;
3218 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3219 fst.current()->describe(values, ++frame_no);
3220 if (depth == frame_no) break;
3221 }
3222 if (validate_only) {
3223 values.validate();
3224 } else {
3225 tty->print_cr("[Describe stack layout]");
3226 values.print(this);
3227 }
3228 }
3229 #endif
3230
3231 void JavaThread::trace_stack_from(vframe* start_vf) {
3232 ResourceMark rm;
3233 int vframe_no = 1;
3234 for (vframe* f = start_vf; f; f = f->sender()) {
3235 if (f->is_java_frame()) {
3236 javaVFrame::cast(f)->print_activation(vframe_no++);
3237 } else {
3238 f->print();
3239 }
3240 if (vframe_no > StackPrintLimit) {
3241 tty->print_cr("...<more frames>...");
3242 return;
3243 }
3244 }
3245 }
3246
3247
3248 void JavaThread::trace_stack() {
3249 if (!has_last_Java_frame()) return;
3250 ResourceMark rm;
3251 HandleMark hm;
3252 RegisterMap reg_map(this);
3253 trace_stack_from(last_java_vframe(®_map));
3254 }
3255
3256
3257 #endif // PRODUCT
3258
3259
3260 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3261 assert(reg_map != NULL, "a map must be given");
3262 frame f = last_frame();
3263 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3264 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3265 }
3266 return NULL;
3267 }
3268
3269
3270 Klass* JavaThread::security_get_caller_class(int depth) {
3271 vframeStream vfst(this);
3272 vfst.security_get_caller_frame(depth);
3273 if (!vfst.at_end()) {
3274 return vfst.method()->method_holder();
3275 }
3276 return NULL;
3277 }
3278
3279 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3280 assert(thread->is_Compiler_thread(), "must be compiler thread");
3281 CompileBroker::compiler_thread_loop();
3282 }
3283
3284 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3285 NMethodSweeper::sweeper_loop();
3286 }
3287
3288 // Create a CompilerThread
3289 CompilerThread::CompilerThread(CompileQueue* queue,
3290 CompilerCounters* counters)
3291 : JavaThread(&compiler_thread_entry) {
3292 _env = NULL;
3293 _log = NULL;
3294 _task = NULL;
3295 _queue = queue;
3296 _counters = counters;
3297 _buffer_blob = NULL;
3298 _compiler = NULL;
3299
3300 #ifndef PRODUCT
3301 _ideal_graph_printer = NULL;
3302 #endif
3303 }
3304
3305 bool CompilerThread::can_call_java() const {
3306 return _compiler != NULL && _compiler->is_jvmci();
3307 }
3308
3309 // Create sweeper thread
3310 CodeCacheSweeperThread::CodeCacheSweeperThread()
3311 : JavaThread(&sweeper_thread_entry) {
3312 _scanned_compiled_method = NULL;
3313 }
3314
3315 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3316 JavaThread::oops_do(f, cf);
3317 if (_scanned_compiled_method != NULL && cf != NULL) {
3318 // Safepoints can occur when the sweeper is scanning an nmethod so
3319 // process it here to make sure it isn't unloaded in the middle of
3320 // a scan.
3321 cf->do_code_blob(_scanned_compiled_method);
3322 }
3323 }
3324
3325 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3326 JavaThread::nmethods_do(cf);
3327 if (_scanned_compiled_method != NULL && cf != NULL) {
3328 // Safepoints can occur when the sweeper is scanning an nmethod so
3329 // process it here to make sure it isn't unloaded in the middle of
3330 // a scan.
3331 cf->do_code_blob(_scanned_compiled_method);
3332 }
3333 }
3334
3335
3336 // ======= Threads ========
3337
3338 // The Threads class links together all active threads, and provides
3339 // operations over all threads. It is protected by its own Mutex
3340 // lock, which is also used in other contexts to protect thread
3341 // operations from having the thread being operated on from exiting
3342 // and going away unexpectedly (e.g., safepoint synchronization)
3343
3344 JavaThread* Threads::_thread_list = NULL;
3345 int Threads::_number_of_threads = 0;
3346 int Threads::_number_of_non_daemon_threads = 0;
3347 int Threads::_return_code = 0;
3348 int Threads::_thread_claim_parity = 0;
3349 size_t JavaThread::_stack_size_at_create = 0;
3350 #ifdef ASSERT
3351 bool Threads::_vm_complete = false;
3352 #endif
3353
3354 // All JavaThreads
3355 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3356
3357 void Threads::java_threads_do(ThreadClosure* tc) {
3358 assert_locked_or_safepoint(Threads_lock);
3359 ALL_JAVA_THREADS(p) {
3360 tc->do_thread(p);
3361 }
3362 }
3363
3364 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3365 void Threads::threads_do(ThreadClosure* tc) {
3366 assert_locked_or_safepoint(Threads_lock);
3367 // ALL_JAVA_THREADS iterates through all JavaThreads
3368 ALL_JAVA_THREADS(p) {
3369 tc->do_thread(p);
3370 }
3371 // Someday we could have a table or list of all non-JavaThreads.
3372 // For now, just manually iterate through them.
3373 tc->do_thread(VMThread::vm_thread());
3374 Universe::heap()->gc_threads_do(tc);
3375 WatcherThread *wt = WatcherThread::watcher_thread();
3376 // Strictly speaking, the following NULL check isn't sufficient to make sure
3377 // the data for WatcherThread is still valid upon being examined. However,
3378 // considering that WatchThread terminates when the VM is on the way to
3379 // exit at safepoint, the chance of the above is extremely small. The right
3380 // way to prevent termination of WatcherThread would be to acquire
3381 // Terminator_lock, but we can't do that without violating the lock rank
3382 // checking in some cases.
3383 if (wt != NULL) {
3384 tc->do_thread(wt);
3385 }
3386
3387 // If CompilerThreads ever become non-JavaThreads, add them here
3388 }
3389
3390 void Threads::parallel_java_threads_do(ThreadClosure* tc) {
3391 int cp = Threads::thread_claim_parity();
3392 ALL_JAVA_THREADS(p) {
3393 if (p->claim_oops_do(true, cp)) {
3394 tc->do_thread(p);
3395 }
3396 }
3397 // Thread claiming protocol requires us to claim the same interesting
3398 // threads on all paths. Notably, Threads::possibly_parallel_threads_do
3399 // claims all Java threads *and* the VMThread. To avoid breaking the
3400 // claiming protocol, we have to claim VMThread on this path too, even
3401 // if we do not apply the closure to the VMThread.
3402 VMThread* vmt = VMThread::vm_thread();
3403 (void)vmt->claim_oops_do(true, cp);
3404 }
3405
3406 // The system initialization in the library has three phases.
3407 //
3408 // Phase 1: java.lang.System class initialization
3409 // java.lang.System is a primordial class loaded and initialized
3410 // by the VM early during startup. java.lang.System.<clinit>
3411 // only does registerNatives and keeps the rest of the class
3412 // initialization work later until thread initialization completes.
3413 //
3414 // System.initPhase1 initializes the system properties, the static
3415 // fields in, out, and err. Set up java signal handlers, OS-specific
3416 // system settings, and thread group of the main thread.
3417 static void call_initPhase1(TRAPS) {
3418 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3419 JavaValue result(T_VOID);
3420 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3421 vmSymbols::void_method_signature(), CHECK);
3422 }
3423
3424 // Phase 2. Module system initialization
3425 // This will initialize the module system. Only java.base classes
3426 // can be loaded until phase 2 completes.
3427 //
3428 // Call System.initPhase2 after the compiler initialization and jsr292
3429 // classes get initialized because module initialization runs a lot of java
3430 // code, that for performance reasons, should be compiled. Also, this will
3431 // enable the startup code to use lambda and other language features in this
3432 // phase and onward.
3433 //
3434 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3435 static void call_initPhase2(TRAPS) {
3436 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3437
3438 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3439
3440 JavaValue result(T_INT);
3441 JavaCallArguments args;
3442 args.push_int(DisplayVMOutputToStderr);
3443 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3444 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3445 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3446 if (result.get_jint() != JNI_OK) {
3447 vm_exit_during_initialization(); // no message or exception
3448 }
3449
3450 universe_post_module_init();
3451 }
3452
3453 // Phase 3. final setup - set security manager, system class loader and TCCL
3454 //
3455 // This will instantiate and set the security manager, set the system class
3456 // loader as well as the thread context class loader. The security manager
3457 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3458 // other modules or the application's classpath.
3459 static void call_initPhase3(TRAPS) {
3460 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3461 JavaValue result(T_VOID);
3462 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3463 vmSymbols::void_method_signature(), CHECK);
3464 }
3465
3466 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3467 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3468
3469 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3470 create_vm_init_libraries();
3471 }
3472
3473 initialize_class(vmSymbols::java_lang_String(), CHECK);
3474
3475 // Inject CompactStrings value after the static initializers for String ran.
3476 java_lang_String::set_compact_strings(CompactStrings);
3477
3478 // Initialize java_lang.System (needed before creating the thread)
3479 initialize_class(vmSymbols::java_lang_System(), CHECK);
3480 // The VM creates & returns objects of this class. Make sure it's initialized.
3481 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3482 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3483 Handle thread_group = create_initial_thread_group(CHECK);
3484 Universe::set_main_thread_group(thread_group());
3485 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3486 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3487 main_thread->set_threadObj(thread_object);
3488 // Set thread status to running since main thread has
3489 // been started and running.
3490 java_lang_Thread::set_thread_status(thread_object,
3491 java_lang_Thread::RUNNABLE);
3492
3493 // The VM creates objects of this class.
3494 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3495
3496 // The VM preresolves methods to these classes. Make sure that they get initialized
3497 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3498 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3499
3500 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3501 call_initPhase1(CHECK);
3502
3503 // get the Java runtime name after java.lang.System is initialized
3504 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3505 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3506
3507 // an instance of OutOfMemory exception has been allocated earlier
3508 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3509 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3510 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3511 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3512 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3513 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3514 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3515 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3516 }
3517
3518 void Threads::initialize_jsr292_core_classes(TRAPS) {
3519 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3520
3521 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3522 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3523 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3524 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3525 }
3526
3527 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3528 extern void JDK_Version_init();
3529
3530 // Preinitialize version info.
3531 VM_Version::early_initialize();
3532
3533 // Check version
3534 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3535
3536 // Initialize library-based TLS
3537 ThreadLocalStorage::init();
3538
3539 // Initialize the output stream module
3540 ostream_init();
3541
3542 // Process java launcher properties.
3543 Arguments::process_sun_java_launcher_properties(args);
3544
3545 // Initialize the os module
3546 os::init();
3547
3548 // Record VM creation timing statistics
3549 TraceVmCreationTime create_vm_timer;
3550 create_vm_timer.start();
3551
3552 // Initialize system properties.
3553 Arguments::init_system_properties();
3554
3555 // So that JDK version can be used as a discriminator when parsing arguments
3556 JDK_Version_init();
3557
3558 // Update/Initialize System properties after JDK version number is known
3559 Arguments::init_version_specific_system_properties();
3560
3561 // Make sure to initialize log configuration *before* parsing arguments
3562 LogConfiguration::initialize(create_vm_timer.begin_time());
3563
3564 // Parse arguments
3565 jint parse_result = Arguments::parse(args);
3566 if (parse_result != JNI_OK) return parse_result;
3567
3568 os::init_before_ergo();
3569
3570 jint ergo_result = Arguments::apply_ergo();
3571 if (ergo_result != JNI_OK) return ergo_result;
3572
3573 // Final check of all ranges after ergonomics which may change values.
3574 if (!CommandLineFlagRangeList::check_ranges()) {
3575 return JNI_EINVAL;
3576 }
3577
3578 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3579 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3580 if (!constraint_result) {
3581 return JNI_EINVAL;
3582 }
3583
3584 CommandLineFlagWriteableList::mark_startup();
3585
3586 if (PauseAtStartup) {
3587 os::pause();
3588 }
3589
3590 HOTSPOT_VM_INIT_BEGIN();
3591
3592 // Timing (must come after argument parsing)
3593 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3594
3595 // Initialize the os module after parsing the args
3596 jint os_init_2_result = os::init_2();
3597 if (os_init_2_result != JNI_OK) return os_init_2_result;
3598
3599 jint adjust_after_os_result = Arguments::adjust_after_os();
3600 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3601
3602 // Initialize output stream logging
3603 ostream_init_log();
3604
3605 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3606 // Must be before create_vm_init_agents()
3607 if (Arguments::init_libraries_at_startup()) {
3608 convert_vm_init_libraries_to_agents();
3609 }
3610
3611 // Launch -agentlib/-agentpath and converted -Xrun agents
3612 if (Arguments::init_agents_at_startup()) {
3613 create_vm_init_agents();
3614 }
3615
3616 // Initialize Threads state
3617 _thread_list = NULL;
3618 _number_of_threads = 0;
3619 _number_of_non_daemon_threads = 0;
3620
3621 // Initialize global data structures and create system classes in heap
3622 vm_init_globals();
3623
3624 #if INCLUDE_JVMCI
3625 if (JVMCICounterSize > 0) {
3626 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3627 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3628 } else {
3629 JavaThread::_jvmci_old_thread_counters = NULL;
3630 }
3631 #endif // INCLUDE_JVMCI
3632
3633 // Attach the main thread to this os thread
3634 JavaThread* main_thread = new JavaThread();
3635 main_thread->set_thread_state(_thread_in_vm);
3636 main_thread->initialize_thread_current();
3637 // must do this before set_active_handles
3638 main_thread->record_stack_base_and_size();
3639 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3640
3641 if (!main_thread->set_as_starting_thread()) {
3642 vm_shutdown_during_initialization(
3643 "Failed necessary internal allocation. Out of swap space");
3644 delete main_thread;
3645 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3646 return JNI_ENOMEM;
3647 }
3648
3649 // Enable guard page *after* os::create_main_thread(), otherwise it would
3650 // crash Linux VM, see notes in os_linux.cpp.
3651 main_thread->create_stack_guard_pages();
3652
3653 // Initialize Java-Level synchronization subsystem
3654 ObjectMonitor::Initialize();
3655
3656 // Initialize global modules
3657 jint status = init_globals();
3658 if (status != JNI_OK) {
3659 delete main_thread;
3660 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3661 return status;
3662 }
3663
3664 if (TRACE_INITIALIZE() != JNI_OK) {
3665 vm_exit_during_initialization("Failed to initialize tracing backend");
3666 }
3667
3668 // Should be done after the heap is fully created
3669 main_thread->cache_global_variables();
3670
3671 HandleMark hm;
3672
3673 { MutexLocker mu(Threads_lock);
3674 Threads::add(main_thread);
3675 }
3676
3677 // Any JVMTI raw monitors entered in onload will transition into
3678 // real raw monitor. VM is setup enough here for raw monitor enter.
3679 JvmtiExport::transition_pending_onload_raw_monitors();
3680
3681 // Create the VMThread
3682 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3683
3684 VMThread::create();
3685 Thread* vmthread = VMThread::vm_thread();
3686
3687 if (!os::create_thread(vmthread, os::vm_thread)) {
3688 vm_exit_during_initialization("Cannot create VM thread. "
3689 "Out of system resources.");
3690 }
3691
3692 // Wait for the VM thread to become ready, and VMThread::run to initialize
3693 // Monitors can have spurious returns, must always check another state flag
3694 {
3695 MutexLocker ml(Notify_lock);
3696 os::start_thread(vmthread);
3697 while (vmthread->active_handles() == NULL) {
3698 Notify_lock->wait();
3699 }
3700 }
3701 }
3702
3703 assert(Universe::is_fully_initialized(), "not initialized");
3704 if (VerifyDuringStartup) {
3705 // Make sure we're starting with a clean slate.
3706 VM_Verify verify_op;
3707 VMThread::execute(&verify_op);
3708 }
3709
3710 Thread* THREAD = Thread::current();
3711
3712 // Always call even when there are not JVMTI environments yet, since environments
3713 // may be attached late and JVMTI must track phases of VM execution
3714 JvmtiExport::enter_early_start_phase();
3715
3716 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3717 JvmtiExport::post_early_vm_start();
3718
3719 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3720
3721 // We need this for ClassDataSharing - the initial vm.info property is set
3722 // with the default value of CDS "sharing" which may be reset through
3723 // command line options.
3724 reset_vm_info_property(CHECK_JNI_ERR);
3725
3726 quicken_jni_functions();
3727
3728 // No more stub generation allowed after that point.
3729 StubCodeDesc::freeze();
3730
3731 // Set flag that basic initialization has completed. Used by exceptions and various
3732 // debug stuff, that does not work until all basic classes have been initialized.
3733 set_init_completed();
3734
3735 LogConfiguration::post_initialize();
3736 Metaspace::post_initialize();
3737
3738 HOTSPOT_VM_INIT_END();
3739
3740 // record VM initialization completion time
3741 #if INCLUDE_MANAGEMENT
3742 Management::record_vm_init_completed();
3743 #endif // INCLUDE_MANAGEMENT
3744
3745 // Signal Dispatcher needs to be started before VMInit event is posted
3746 os::signal_init(CHECK_JNI_ERR);
3747
3748 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3749 if (!DisableAttachMechanism) {
3750 AttachListener::vm_start();
3751 if (StartAttachListener || AttachListener::init_at_startup()) {
3752 AttachListener::init();
3753 }
3754 }
3755
3756 // Launch -Xrun agents
3757 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3758 // back-end can launch with -Xdebug -Xrunjdwp.
3759 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3760 create_vm_init_libraries();
3761 }
3762
3763 if (CleanChunkPoolAsync) {
3764 Chunk::start_chunk_pool_cleaner_task();
3765 }
3766
3767 // initialize compiler(s)
3768 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3769 CompileBroker::compilation_init(CHECK_JNI_ERR);
3770 #endif
3771
3772 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3773 // It is done after compilers are initialized, because otherwise compilations of
3774 // signature polymorphic MH intrinsics can be missed
3775 // (see SystemDictionary::find_method_handle_intrinsic).
3776 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3777
3778 // This will initialize the module system. Only java.base classes can be
3779 // loaded until phase 2 completes
3780 call_initPhase2(CHECK_JNI_ERR);
3781
3782 // Always call even when there are not JVMTI environments yet, since environments
3783 // may be attached late and JVMTI must track phases of VM execution
3784 JvmtiExport::enter_start_phase();
3785
3786 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3787 JvmtiExport::post_vm_start();
3788
3789 // Final system initialization including security manager and system class loader
3790 call_initPhase3(CHECK_JNI_ERR);
3791
3792 // cache the system class loader
3793 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3794
3795 #if INCLUDE_JVMCI
3796 if (EnableJVMCI) {
3797 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3798 // The JVMCI Java initialization code will read this flag and
3799 // do the printing if it's set.
3800 bool init = JVMCIPrintProperties;
3801
3802 if (!init) {
3803 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3804 // compilations via JVMCI will not actually block until JVMCI is initialized.
3805 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3806 }
3807
3808 if (init) {
3809 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3810 }
3811 }
3812 #endif
3813
3814 // Always call even when there are not JVMTI environments yet, since environments
3815 // may be attached late and JVMTI must track phases of VM execution
3816 JvmtiExport::enter_live_phase();
3817
3818 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3819 JvmtiExport::post_vm_initialized();
3820
3821 if (TRACE_START() != JNI_OK) {
3822 vm_exit_during_initialization("Failed to start tracing backend.");
3823 }
3824
3825 #if INCLUDE_MANAGEMENT
3826 Management::initialize(THREAD);
3827
3828 if (HAS_PENDING_EXCEPTION) {
3829 // management agent fails to start possibly due to
3830 // configuration problem and is responsible for printing
3831 // stack trace if appropriate. Simply exit VM.
3832 vm_exit(1);
3833 }
3834 #endif // INCLUDE_MANAGEMENT
3835
3836 if (MemProfiling) MemProfiler::engage();
3837 StatSampler::engage();
3838 if (CheckJNICalls) JniPeriodicChecker::engage();
3839
3840 BiasedLocking::init();
3841
3842 #if INCLUDE_RTM_OPT
3843 RTMLockingCounters::init();
3844 #endif
3845
3846 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3847 call_postVMInitHook(THREAD);
3848 // The Java side of PostVMInitHook.run must deal with all
3849 // exceptions and provide means of diagnosis.
3850 if (HAS_PENDING_EXCEPTION) {
3851 CLEAR_PENDING_EXCEPTION;
3852 }
3853 }
3854
3855 {
3856 MutexLocker ml(PeriodicTask_lock);
3857 // Make sure the WatcherThread can be started by WatcherThread::start()
3858 // or by dynamic enrollment.
3859 WatcherThread::make_startable();
3860 // Start up the WatcherThread if there are any periodic tasks
3861 // NOTE: All PeriodicTasks should be registered by now. If they
3862 // aren't, late joiners might appear to start slowly (we might
3863 // take a while to process their first tick).
3864 if (PeriodicTask::num_tasks() > 0) {
3865 WatcherThread::start();
3866 }
3867 }
3868
3869 create_vm_timer.end();
3870 #ifdef ASSERT
3871 _vm_complete = true;
3872 #endif
3873
3874 if (DumpSharedSpaces) {
3875 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3876 ShouldNotReachHere();
3877 }
3878
3879 return JNI_OK;
3880 }
3881
3882 // type for the Agent_OnLoad and JVM_OnLoad entry points
3883 extern "C" {
3884 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3885 }
3886 // Find a command line agent library and return its entry point for
3887 // -agentlib: -agentpath: -Xrun
3888 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3889 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3890 const char *on_load_symbols[],
3891 size_t num_symbol_entries) {
3892 OnLoadEntry_t on_load_entry = NULL;
3893 void *library = NULL;
3894
3895 if (!agent->valid()) {
3896 char buffer[JVM_MAXPATHLEN];
3897 char ebuf[1024] = "";
3898 const char *name = agent->name();
3899 const char *msg = "Could not find agent library ";
3900
3901 // First check to see if agent is statically linked into executable
3902 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3903 library = agent->os_lib();
3904 } else if (agent->is_absolute_path()) {
3905 library = os::dll_load(name, ebuf, sizeof ebuf);
3906 if (library == NULL) {
3907 const char *sub_msg = " in absolute path, with error: ";
3908 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3909 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3910 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3911 // If we can't find the agent, exit.
3912 vm_exit_during_initialization(buf, NULL);
3913 FREE_C_HEAP_ARRAY(char, buf);
3914 }
3915 } else {
3916 // Try to load the agent from the standard dll directory
3917 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3918 name)) {
3919 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3920 }
3921 if (library == NULL) { // Try the library path directory.
3922 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3923 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3924 }
3925 if (library == NULL) {
3926 const char *sub_msg = " on the library path, with error: ";
3927 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3928 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3929 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3930 // If we can't find the agent, exit.
3931 vm_exit_during_initialization(buf, NULL);
3932 FREE_C_HEAP_ARRAY(char, buf);
3933 }
3934 }
3935 }
3936 agent->set_os_lib(library);
3937 agent->set_valid();
3938 }
3939
3940 // Find the OnLoad function.
3941 on_load_entry =
3942 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3943 false,
3944 on_load_symbols,
3945 num_symbol_entries));
3946 return on_load_entry;
3947 }
3948
3949 // Find the JVM_OnLoad entry point
3950 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3951 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3952 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3953 }
3954
3955 // Find the Agent_OnLoad entry point
3956 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3957 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3958 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3959 }
3960
3961 // For backwards compatibility with -Xrun
3962 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3963 // treated like -agentpath:
3964 // Must be called before agent libraries are created
3965 void Threads::convert_vm_init_libraries_to_agents() {
3966 AgentLibrary* agent;
3967 AgentLibrary* next;
3968
3969 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3970 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3971 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3972
3973 // If there is an JVM_OnLoad function it will get called later,
3974 // otherwise see if there is an Agent_OnLoad
3975 if (on_load_entry == NULL) {
3976 on_load_entry = lookup_agent_on_load(agent);
3977 if (on_load_entry != NULL) {
3978 // switch it to the agent list -- so that Agent_OnLoad will be called,
3979 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3980 Arguments::convert_library_to_agent(agent);
3981 } else {
3982 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3983 }
3984 }
3985 }
3986 }
3987
3988 // Create agents for -agentlib: -agentpath: and converted -Xrun
3989 // Invokes Agent_OnLoad
3990 // Called very early -- before JavaThreads exist
3991 void Threads::create_vm_init_agents() {
3992 extern struct JavaVM_ main_vm;
3993 AgentLibrary* agent;
3994
3995 JvmtiExport::enter_onload_phase();
3996
3997 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3998 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3999
4000 if (on_load_entry != NULL) {
4001 // Invoke the Agent_OnLoad function
4002 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4003 if (err != JNI_OK) {
4004 vm_exit_during_initialization("agent library failed to init", agent->name());
4005 }
4006 } else {
4007 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4008 }
4009 }
4010 JvmtiExport::enter_primordial_phase();
4011 }
4012
4013 extern "C" {
4014 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4015 }
4016
4017 void Threads::shutdown_vm_agents() {
4018 // Send any Agent_OnUnload notifications
4019 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4020 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4021 extern struct JavaVM_ main_vm;
4022 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4023
4024 // Find the Agent_OnUnload function.
4025 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4026 os::find_agent_function(agent,
4027 false,
4028 on_unload_symbols,
4029 num_symbol_entries));
4030
4031 // Invoke the Agent_OnUnload function
4032 if (unload_entry != NULL) {
4033 JavaThread* thread = JavaThread::current();
4034 ThreadToNativeFromVM ttn(thread);
4035 HandleMark hm(thread);
4036 (*unload_entry)(&main_vm);
4037 }
4038 }
4039 }
4040
4041 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4042 // Invokes JVM_OnLoad
4043 void Threads::create_vm_init_libraries() {
4044 extern struct JavaVM_ main_vm;
4045 AgentLibrary* agent;
4046
4047 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4048 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4049
4050 if (on_load_entry != NULL) {
4051 // Invoke the JVM_OnLoad function
4052 JavaThread* thread = JavaThread::current();
4053 ThreadToNativeFromVM ttn(thread);
4054 HandleMark hm(thread);
4055 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4056 if (err != JNI_OK) {
4057 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4058 }
4059 } else {
4060 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4061 }
4062 }
4063 }
4064
4065 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4066 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4067
4068 JavaThread* java_thread = NULL;
4069 // Sequential search for now. Need to do better optimization later.
4070 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4071 oop tobj = thread->threadObj();
4072 if (!thread->is_exiting() &&
4073 tobj != NULL &&
4074 java_tid == java_lang_Thread::thread_id(tobj)) {
4075 java_thread = thread;
4076 break;
4077 }
4078 }
4079 return java_thread;
4080 }
4081
4082
4083 // Last thread running calls java.lang.Shutdown.shutdown()
4084 void JavaThread::invoke_shutdown_hooks() {
4085 HandleMark hm(this);
4086
4087 // We could get here with a pending exception, if so clear it now.
4088 if (this->has_pending_exception()) {
4089 this->clear_pending_exception();
4090 }
4091
4092 EXCEPTION_MARK;
4093 Klass* shutdown_klass =
4094 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4095 THREAD);
4096 if (shutdown_klass != NULL) {
4097 // SystemDictionary::resolve_or_null will return null if there was
4098 // an exception. If we cannot load the Shutdown class, just don't
4099 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4100 // and finalizers (if runFinalizersOnExit is set) won't be run.
4101 // Note that if a shutdown hook was registered or runFinalizersOnExit
4102 // was called, the Shutdown class would have already been loaded
4103 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4104 JavaValue result(T_VOID);
4105 JavaCalls::call_static(&result,
4106 shutdown_klass,
4107 vmSymbols::shutdown_method_name(),
4108 vmSymbols::void_method_signature(),
4109 THREAD);
4110 }
4111 CLEAR_PENDING_EXCEPTION;
4112 }
4113
4114 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4115 // the program falls off the end of main(). Another VM exit path is through
4116 // vm_exit() when the program calls System.exit() to return a value or when
4117 // there is a serious error in VM. The two shutdown paths are not exactly
4118 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4119 // and VM_Exit op at VM level.
4120 //
4121 // Shutdown sequence:
4122 // + Shutdown native memory tracking if it is on
4123 // + Wait until we are the last non-daemon thread to execute
4124 // <-- every thing is still working at this moment -->
4125 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4126 // shutdown hooks, run finalizers if finalization-on-exit
4127 // + Call before_exit(), prepare for VM exit
4128 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4129 // currently the only user of this mechanism is File.deleteOnExit())
4130 // > stop StatSampler, watcher thread, CMS threads,
4131 // post thread end and vm death events to JVMTI,
4132 // stop signal thread
4133 // + Call JavaThread::exit(), it will:
4134 // > release JNI handle blocks, remove stack guard pages
4135 // > remove this thread from Threads list
4136 // <-- no more Java code from this thread after this point -->
4137 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4138 // the compiler threads at safepoint
4139 // <-- do not use anything that could get blocked by Safepoint -->
4140 // + Disable tracing at JNI/JVM barriers
4141 // + Set _vm_exited flag for threads that are still running native code
4142 // + Delete this thread
4143 // + Call exit_globals()
4144 // > deletes tty
4145 // > deletes PerfMemory resources
4146 // + Return to caller
4147
4148 bool Threads::destroy_vm() {
4149 JavaThread* thread = JavaThread::current();
4150
4151 #ifdef ASSERT
4152 _vm_complete = false;
4153 #endif
4154 // Wait until we are the last non-daemon thread to execute
4155 { MutexLocker nu(Threads_lock);
4156 while (Threads::number_of_non_daemon_threads() > 1)
4157 // This wait should make safepoint checks, wait without a timeout,
4158 // and wait as a suspend-equivalent condition.
4159 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4160 Mutex::_as_suspend_equivalent_flag);
4161 }
4162
4163 // Hang forever on exit if we are reporting an error.
4164 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4165 os::infinite_sleep();
4166 }
4167 os::wait_for_keypress_at_exit();
4168
4169 // run Java level shutdown hooks
4170 thread->invoke_shutdown_hooks();
4171
4172 before_exit(thread);
4173
4174 thread->exit(true);
4175
4176 // Stop VM thread.
4177 {
4178 // 4945125 The vm thread comes to a safepoint during exit.
4179 // GC vm_operations can get caught at the safepoint, and the
4180 // heap is unparseable if they are caught. Grab the Heap_lock
4181 // to prevent this. The GC vm_operations will not be able to
4182 // queue until after the vm thread is dead. After this point,
4183 // we'll never emerge out of the safepoint before the VM exits.
4184
4185 MutexLocker ml(Heap_lock);
4186
4187 VMThread::wait_for_vm_thread_exit();
4188 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4189 VMThread::destroy();
4190 }
4191
4192 // clean up ideal graph printers
4193 #if defined(COMPILER2) && !defined(PRODUCT)
4194 IdealGraphPrinter::clean_up();
4195 #endif
4196
4197 // Now, all Java threads are gone except daemon threads. Daemon threads
4198 // running Java code or in VM are stopped by the Safepoint. However,
4199 // daemon threads executing native code are still running. But they
4200 // will be stopped at native=>Java/VM barriers. Note that we can't
4201 // simply kill or suspend them, as it is inherently deadlock-prone.
4202
4203 VM_Exit::set_vm_exited();
4204
4205 notify_vm_shutdown();
4206
4207 delete thread;
4208
4209 #if INCLUDE_JVMCI
4210 if (JVMCICounterSize > 0) {
4211 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4212 }
4213 #endif
4214
4215 // exit_globals() will delete tty
4216 exit_globals();
4217
4218 LogConfiguration::finalize();
4219
4220 return true;
4221 }
4222
4223
4224 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4225 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4226 return is_supported_jni_version(version);
4227 }
4228
4229
4230 jboolean Threads::is_supported_jni_version(jint version) {
4231 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4232 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4233 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4234 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4235 if (version == JNI_VERSION_9) return JNI_TRUE;
4236 return JNI_FALSE;
4237 }
4238
4239
4240 void Threads::add(JavaThread* p, bool force_daemon) {
4241 // The threads lock must be owned at this point
4242 assert_locked_or_safepoint(Threads_lock);
4243
4244 // See the comment for this method in thread.hpp for its purpose and
4245 // why it is called here.
4246 p->initialize_queues();
4247 p->set_next(_thread_list);
4248 _thread_list = p;
4249 _number_of_threads++;
4250 oop threadObj = p->threadObj();
4251 bool daemon = true;
4252 // Bootstrapping problem: threadObj can be null for initial
4253 // JavaThread (or for threads attached via JNI)
4254 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4255 _number_of_non_daemon_threads++;
4256 daemon = false;
4257 }
4258
4259 ThreadService::add_thread(p, daemon);
4260
4261 // Possible GC point.
4262 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4263 }
4264
4265 void Threads::remove(JavaThread* p) {
4266
4267 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4268 ObjectSynchronizer::omFlush(p);
4269
4270 // Extra scope needed for Thread_lock, so we can check
4271 // that we do not remove thread without safepoint code notice
4272 { MutexLocker ml(Threads_lock);
4273
4274 assert(includes(p), "p must be present");
4275
4276 JavaThread* current = _thread_list;
4277 JavaThread* prev = NULL;
4278
4279 while (current != p) {
4280 prev = current;
4281 current = current->next();
4282 }
4283
4284 if (prev) {
4285 prev->set_next(current->next());
4286 } else {
4287 _thread_list = p->next();
4288 }
4289 _number_of_threads--;
4290 oop threadObj = p->threadObj();
4291 bool daemon = true;
4292 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4293 _number_of_non_daemon_threads--;
4294 daemon = false;
4295
4296 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4297 // on destroy_vm will wake up.
4298 if (number_of_non_daemon_threads() == 1) {
4299 Threads_lock->notify_all();
4300 }
4301 }
4302 ThreadService::remove_thread(p, daemon);
4303
4304 // Make sure that safepoint code disregard this thread. This is needed since
4305 // the thread might mess around with locks after this point. This can cause it
4306 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4307 // of this thread since it is removed from the queue.
4308 p->set_terminated_value();
4309 } // unlock Threads_lock
4310
4311 // Since Events::log uses a lock, we grab it outside the Threads_lock
4312 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4313 }
4314
4315 // Threads_lock must be held when this is called (or must be called during a safepoint)
4316 bool Threads::includes(JavaThread* p) {
4317 assert(Threads_lock->is_locked(), "sanity check");
4318 ALL_JAVA_THREADS(q) {
4319 if (q == p) {
4320 return true;
4321 }
4322 }
4323 return false;
4324 }
4325
4326 // Operations on the Threads list for GC. These are not explicitly locked,
4327 // but the garbage collector must provide a safe context for them to run.
4328 // In particular, these things should never be called when the Threads_lock
4329 // is held by some other thread. (Note: the Safepoint abstraction also
4330 // uses the Threads_lock to guarantee this property. It also makes sure that
4331 // all threads gets blocked when exiting or starting).
4332
4333 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4334 ALL_JAVA_THREADS(p) {
4335 p->oops_do(f, cf);
4336 }
4337 VMThread::vm_thread()->oops_do(f, cf);
4338 }
4339
4340 void Threads::change_thread_claim_parity() {
4341 // Set the new claim parity.
4342 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4343 "Not in range.");
4344 _thread_claim_parity++;
4345 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4346 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4347 "Not in range.");
4348 }
4349
4350 #ifdef ASSERT
4351 void Threads::assert_all_threads_claimed() {
4352 ALL_JAVA_THREADS(p) {
4353 const int thread_parity = p->oops_do_parity();
4354 assert((thread_parity == _thread_claim_parity),
4355 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4356 }
4357 VMThread* vmt = VMThread::vm_thread();
4358 const int thread_parity = vmt->oops_do_parity();
4359 assert((thread_parity == _thread_claim_parity),
4360 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4361 }
4362 #endif // ASSERT
4363
4364 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf, CodeBlobClosure* nmethods_cl) {
4365 int cp = Threads::thread_claim_parity();
4366 ALL_JAVA_THREADS(p) {
4367 if (p->claim_oops_do(is_par, cp)) {
4368 p->oops_do(f, cf);
4369 if (nmethods_cl != NULL && ! p->is_Code_cache_sweeper_thread()) {
4370 p->nmethods_do(nmethods_cl);
4371 }
4372 }
4373 }
4374 VMThread* vmt = VMThread::vm_thread();
4375 if (vmt->claim_oops_do(is_par, cp)) {
4376 vmt->oops_do(f, cf);
4377 }
4378 }
4379
4380 #if INCLUDE_ALL_GCS
4381 // Used by ParallelScavenge
4382 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4383 ALL_JAVA_THREADS(p) {
4384 q->enqueue(new ThreadRootsTask(p));
4385 }
4386 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4387 }
4388
4389 // Used by Parallel Old
4390 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4391 ALL_JAVA_THREADS(p) {
4392 q->enqueue(new ThreadRootsMarkingTask(p));
4393 }
4394 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4395 }
4396 #endif // INCLUDE_ALL_GCS
4397
4398 void Threads::nmethods_do(CodeBlobClosure* cf) {
4399 ALL_JAVA_THREADS(p) {
4400 // This is used by the code cache sweeper to mark nmethods that are active
4401 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4402 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4403 if(!p->is_Code_cache_sweeper_thread()) {
4404 p->nmethods_do(cf);
4405 }
4406 }
4407 }
4408
4409 void Threads::metadata_do(void f(Metadata*)) {
4410 ALL_JAVA_THREADS(p) {
4411 p->metadata_do(f);
4412 }
4413 }
4414
4415 class ThreadHandlesClosure : public ThreadClosure {
4416 void (*_f)(Metadata*);
4417 public:
4418 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4419 virtual void do_thread(Thread* thread) {
4420 thread->metadata_handles_do(_f);
4421 }
4422 };
4423
4424 void Threads::metadata_handles_do(void f(Metadata*)) {
4425 // Only walk the Handles in Thread.
4426 ThreadHandlesClosure handles_closure(f);
4427 threads_do(&handles_closure);
4428 }
4429
4430 void Threads::deoptimized_wrt_marked_nmethods() {
4431 ALL_JAVA_THREADS(p) {
4432 p->deoptimized_wrt_marked_nmethods();
4433 }
4434 }
4435
4436
4437 // Get count Java threads that are waiting to enter the specified monitor.
4438 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4439 address monitor,
4440 bool doLock) {
4441 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4442 "must grab Threads_lock or be at safepoint");
4443 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4444
4445 int i = 0;
4446 {
4447 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4448 ALL_JAVA_THREADS(p) {
4449 if (!p->can_call_java()) continue;
4450
4451 address pending = (address)p->current_pending_monitor();
4452 if (pending == monitor) { // found a match
4453 if (i < count) result->append(p); // save the first count matches
4454 i++;
4455 }
4456 }
4457 }
4458 return result;
4459 }
4460
4461
4462 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4463 bool doLock) {
4464 assert(doLock ||
4465 Threads_lock->owned_by_self() ||
4466 SafepointSynchronize::is_at_safepoint(),
4467 "must grab Threads_lock or be at safepoint");
4468
4469 // NULL owner means not locked so we can skip the search
4470 if (owner == NULL) return NULL;
4471
4472 {
4473 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4474 ALL_JAVA_THREADS(p) {
4475 // first, see if owner is the address of a Java thread
4476 if (owner == (address)p) return p;
4477 }
4478 }
4479 // Cannot assert on lack of success here since this function may be
4480 // used by code that is trying to report useful problem information
4481 // like deadlock detection.
4482 if (UseHeavyMonitors) return NULL;
4483
4484 // If we didn't find a matching Java thread and we didn't force use of
4485 // heavyweight monitors, then the owner is the stack address of the
4486 // Lock Word in the owning Java thread's stack.
4487 //
4488 JavaThread* the_owner = NULL;
4489 {
4490 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4491 ALL_JAVA_THREADS(q) {
4492 if (q->is_lock_owned(owner)) {
4493 the_owner = q;
4494 break;
4495 }
4496 }
4497 }
4498 // cannot assert on lack of success here; see above comment
4499 return the_owner;
4500 }
4501
4502 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4503 void Threads::print_on(outputStream* st, bool print_stacks,
4504 bool internal_format, bool print_concurrent_locks) {
4505 char buf[32];
4506 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4507
4508 st->print_cr("Full thread dump %s (%s %s):",
4509 Abstract_VM_Version::vm_name(),
4510 Abstract_VM_Version::vm_release(),
4511 Abstract_VM_Version::vm_info_string());
4512 st->cr();
4513
4514 #if INCLUDE_SERVICES
4515 // Dump concurrent locks
4516 ConcurrentLocksDump concurrent_locks;
4517 if (print_concurrent_locks) {
4518 concurrent_locks.dump_at_safepoint();
4519 }
4520 #endif // INCLUDE_SERVICES
4521
4522 ALL_JAVA_THREADS(p) {
4523 ResourceMark rm;
4524 p->print_on(st);
4525 if (print_stacks) {
4526 if (internal_format) {
4527 p->trace_stack();
4528 } else {
4529 p->print_stack_on(st);
4530 }
4531 }
4532 st->cr();
4533 #if INCLUDE_SERVICES
4534 if (print_concurrent_locks) {
4535 concurrent_locks.print_locks_on(p, st);
4536 }
4537 #endif // INCLUDE_SERVICES
4538 }
4539
4540 VMThread::vm_thread()->print_on(st);
4541 st->cr();
4542 Universe::heap()->print_gc_threads_on(st);
4543 WatcherThread* wt = WatcherThread::watcher_thread();
4544 if (wt != NULL) {
4545 wt->print_on(st);
4546 st->cr();
4547 }
4548 st->flush();
4549 }
4550
4551 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4552 int buflen, bool* found_current) {
4553 if (this_thread != NULL) {
4554 bool is_current = (current == this_thread);
4555 *found_current = *found_current || is_current;
4556 st->print("%s", is_current ? "=>" : " ");
4557
4558 st->print(PTR_FORMAT, p2i(this_thread));
4559 st->print(" ");
4560 this_thread->print_on_error(st, buf, buflen);
4561 st->cr();
4562 }
4563 }
4564
4565 class PrintOnErrorClosure : public ThreadClosure {
4566 outputStream* _st;
4567 Thread* _current;
4568 char* _buf;
4569 int _buflen;
4570 bool* _found_current;
4571 public:
4572 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4573 int buflen, bool* found_current) :
4574 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4575
4576 virtual void do_thread(Thread* thread) {
4577 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4578 }
4579 };
4580
4581 // Threads::print_on_error() is called by fatal error handler. It's possible
4582 // that VM is not at safepoint and/or current thread is inside signal handler.
4583 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4584 // memory (even in resource area), it might deadlock the error handler.
4585 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4586 int buflen) {
4587 bool found_current = false;
4588 st->print_cr("Java Threads: ( => current thread )");
4589 ALL_JAVA_THREADS(thread) {
4590 print_on_error(thread, st, current, buf, buflen, &found_current);
4591 }
4592 st->cr();
4593
4594 st->print_cr("Other Threads:");
4595 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4596 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4597
4598 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4599 Universe::heap()->gc_threads_do(&print_closure);
4600
4601 if (!found_current) {
4602 st->cr();
4603 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4604 current->print_on_error(st, buf, buflen);
4605 st->cr();
4606 }
4607 st->cr();
4608 st->print_cr("Threads with active compile tasks:");
4609 print_threads_compiling(st, buf, buflen);
4610 }
4611
4612 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4613 ALL_JAVA_THREADS(thread) {
4614 if (thread->is_Compiler_thread()) {
4615 CompilerThread* ct = (CompilerThread*) thread;
4616 if (ct->task() != NULL) {
4617 thread->print_name_on_error(st, buf, buflen);
4618 ct->task()->print(st, NULL, true, true);
4619 }
4620 }
4621 }
4622 }
4623
4624
4625 // Internal SpinLock and Mutex
4626 // Based on ParkEvent
4627
4628 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4629 //
4630 // We employ SpinLocks _only for low-contention, fixed-length
4631 // short-duration critical sections where we're concerned
4632 // about native mutex_t or HotSpot Mutex:: latency.
4633 // The mux construct provides a spin-then-block mutual exclusion
4634 // mechanism.
4635 //
4636 // Testing has shown that contention on the ListLock guarding gFreeList
4637 // is common. If we implement ListLock as a simple SpinLock it's common
4638 // for the JVM to devolve to yielding with little progress. This is true
4639 // despite the fact that the critical sections protected by ListLock are
4640 // extremely short.
4641 //
4642 // TODO-FIXME: ListLock should be of type SpinLock.
4643 // We should make this a 1st-class type, integrated into the lock
4644 // hierarchy as leaf-locks. Critically, the SpinLock structure
4645 // should have sufficient padding to avoid false-sharing and excessive
4646 // cache-coherency traffic.
4647
4648
4649 typedef volatile int SpinLockT;
4650
4651 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4652 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4653 return; // normal fast-path return
4654 }
4655
4656 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4657 TEVENT(SpinAcquire - ctx);
4658 int ctr = 0;
4659 int Yields = 0;
4660 for (;;) {
4661 while (*adr != 0) {
4662 ++ctr;
4663 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4664 if (Yields > 5) {
4665 os::naked_short_sleep(1);
4666 } else {
4667 os::naked_yield();
4668 ++Yields;
4669 }
4670 } else {
4671 SpinPause();
4672 }
4673 }
4674 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4675 }
4676 }
4677
4678 void Thread::SpinRelease(volatile int * adr) {
4679 assert(*adr != 0, "invariant");
4680 OrderAccess::fence(); // guarantee at least release consistency.
4681 // Roach-motel semantics.
4682 // It's safe if subsequent LDs and STs float "up" into the critical section,
4683 // but prior LDs and STs within the critical section can't be allowed
4684 // to reorder or float past the ST that releases the lock.
4685 // Loads and stores in the critical section - which appear in program
4686 // order before the store that releases the lock - must also appear
4687 // before the store that releases the lock in memory visibility order.
4688 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4689 // the ST of 0 into the lock-word which releases the lock, so fence
4690 // more than covers this on all platforms.
4691 *adr = 0;
4692 }
4693
4694 // muxAcquire and muxRelease:
4695 //
4696 // * muxAcquire and muxRelease support a single-word lock-word construct.
4697 // The LSB of the word is set IFF the lock is held.
4698 // The remainder of the word points to the head of a singly-linked list
4699 // of threads blocked on the lock.
4700 //
4701 // * The current implementation of muxAcquire-muxRelease uses its own
4702 // dedicated Thread._MuxEvent instance. If we're interested in
4703 // minimizing the peak number of extant ParkEvent instances then
4704 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4705 // as certain invariants were satisfied. Specifically, care would need
4706 // to be taken with regards to consuming unpark() "permits".
4707 // A safe rule of thumb is that a thread would never call muxAcquire()
4708 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4709 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4710 // consume an unpark() permit intended for monitorenter, for instance.
4711 // One way around this would be to widen the restricted-range semaphore
4712 // implemented in park(). Another alternative would be to provide
4713 // multiple instances of the PlatformEvent() for each thread. One
4714 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4715 //
4716 // * Usage:
4717 // -- Only as leaf locks
4718 // -- for short-term locking only as muxAcquire does not perform
4719 // thread state transitions.
4720 //
4721 // Alternatives:
4722 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4723 // but with parking or spin-then-park instead of pure spinning.
4724 // * Use Taura-Oyama-Yonenzawa locks.
4725 // * It's possible to construct a 1-0 lock if we encode the lockword as
4726 // (List,LockByte). Acquire will CAS the full lockword while Release
4727 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4728 // acquiring threads use timers (ParkTimed) to detect and recover from
4729 // the stranding window. Thread/Node structures must be aligned on 256-byte
4730 // boundaries by using placement-new.
4731 // * Augment MCS with advisory back-link fields maintained with CAS().
4732 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4733 // The validity of the backlinks must be ratified before we trust the value.
4734 // If the backlinks are invalid the exiting thread must back-track through the
4735 // the forward links, which are always trustworthy.
4736 // * Add a successor indication. The LockWord is currently encoded as
4737 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4738 // to provide the usual futile-wakeup optimization.
4739 // See RTStt for details.
4740 // * Consider schedctl.sc_nopreempt to cover the critical section.
4741 //
4742
4743
4744 typedef volatile intptr_t MutexT; // Mux Lock-word
4745 enum MuxBits { LOCKBIT = 1 };
4746
4747 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4748 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4749 if (w == 0) return;
4750 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4751 return;
4752 }
4753
4754 TEVENT(muxAcquire - Contention);
4755 ParkEvent * const Self = Thread::current()->_MuxEvent;
4756 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4757 for (;;) {
4758 int its = (os::is_MP() ? 100 : 0) + 1;
4759
4760 // Optional spin phase: spin-then-park strategy
4761 while (--its >= 0) {
4762 w = *Lock;
4763 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4764 return;
4765 }
4766 }
4767
4768 Self->reset();
4769 Self->OnList = intptr_t(Lock);
4770 // The following fence() isn't _strictly necessary as the subsequent
4771 // CAS() both serializes execution and ratifies the fetched *Lock value.
4772 OrderAccess::fence();
4773 for (;;) {
4774 w = *Lock;
4775 if ((w & LOCKBIT) == 0) {
4776 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4777 Self->OnList = 0; // hygiene - allows stronger asserts
4778 return;
4779 }
4780 continue; // Interference -- *Lock changed -- Just retry
4781 }
4782 assert(w & LOCKBIT, "invariant");
4783 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4784 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4785 }
4786
4787 while (Self->OnList != 0) {
4788 Self->park();
4789 }
4790 }
4791 }
4792
4793 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4794 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4795 if (w == 0) return;
4796 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4797 return;
4798 }
4799
4800 TEVENT(muxAcquire - Contention);
4801 ParkEvent * ReleaseAfter = NULL;
4802 if (ev == NULL) {
4803 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4804 }
4805 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4806 for (;;) {
4807 guarantee(ev->OnList == 0, "invariant");
4808 int its = (os::is_MP() ? 100 : 0) + 1;
4809
4810 // Optional spin phase: spin-then-park strategy
4811 while (--its >= 0) {
4812 w = *Lock;
4813 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4814 if (ReleaseAfter != NULL) {
4815 ParkEvent::Release(ReleaseAfter);
4816 }
4817 return;
4818 }
4819 }
4820
4821 ev->reset();
4822 ev->OnList = intptr_t(Lock);
4823 // The following fence() isn't _strictly necessary as the subsequent
4824 // CAS() both serializes execution and ratifies the fetched *Lock value.
4825 OrderAccess::fence();
4826 for (;;) {
4827 w = *Lock;
4828 if ((w & LOCKBIT) == 0) {
4829 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4830 ev->OnList = 0;
4831 // We call ::Release while holding the outer lock, thus
4832 // artificially lengthening the critical section.
4833 // Consider deferring the ::Release() until the subsequent unlock(),
4834 // after we've dropped the outer lock.
4835 if (ReleaseAfter != NULL) {
4836 ParkEvent::Release(ReleaseAfter);
4837 }
4838 return;
4839 }
4840 continue; // Interference -- *Lock changed -- Just retry
4841 }
4842 assert(w & LOCKBIT, "invariant");
4843 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4844 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4845 }
4846
4847 while (ev->OnList != 0) {
4848 ev->park();
4849 }
4850 }
4851 }
4852
4853 // Release() must extract a successor from the list and then wake that thread.
4854 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4855 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4856 // Release() would :
4857 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4858 // (B) Extract a successor from the private list "in-hand"
4859 // (C) attempt to CAS() the residual back into *Lock over null.
4860 // If there were any newly arrived threads and the CAS() would fail.
4861 // In that case Release() would detach the RATs, re-merge the list in-hand
4862 // with the RATs and repeat as needed. Alternately, Release() might
4863 // detach and extract a successor, but then pass the residual list to the wakee.
4864 // The wakee would be responsible for reattaching and remerging before it
4865 // competed for the lock.
4866 //
4867 // Both "pop" and DMR are immune from ABA corruption -- there can be
4868 // multiple concurrent pushers, but only one popper or detacher.
4869 // This implementation pops from the head of the list. This is unfair,
4870 // but tends to provide excellent throughput as hot threads remain hot.
4871 // (We wake recently run threads first).
4872 //
4873 // All paths through muxRelease() will execute a CAS.
4874 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4875 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4876 // executed within the critical section are complete and globally visible before the
4877 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4878 void Thread::muxRelease(volatile intptr_t * Lock) {
4879 for (;;) {
4880 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4881 assert(w & LOCKBIT, "invariant");
4882 if (w == LOCKBIT) return;
4883 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4884 assert(List != NULL, "invariant");
4885 assert(List->OnList == intptr_t(Lock), "invariant");
4886 ParkEvent * const nxt = List->ListNext;
4887 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4888
4889 // The following CAS() releases the lock and pops the head element.
4890 // The CAS() also ratifies the previously fetched lock-word value.
4891 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4892 continue;
4893 }
4894 List->OnList = 0;
4895 OrderAccess::fence();
4896 List->unpark();
4897 return;
4898 }
4899 }
4900
4901
4902 void Threads::verify() {
4903 ALL_JAVA_THREADS(p) {
4904 p->verify();
4905 }
4906 VMThread* thread = VMThread::vm_thread();
4907 if (thread != NULL) thread->verify();
4908 }