1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/scopeDesc.hpp"
33 #include "compiler/compileBroker.hpp"
34 #include "compiler/compileTask.hpp"
35 #include "gc/shared/gcId.hpp"
36 #include "gc/shared/gcLocker.inline.hpp"
37 #include "gc/shared/workgroup.hpp"
38 #include "interpreter/interpreter.hpp"
39 #include "interpreter/linkResolver.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "jvmtifiles/jvmtiEnv.hpp"
42 #include "logging/log.hpp"
43 #include "logging/logConfiguration.hpp"
44 #include "logging/logStream.hpp"
45 #include "memory/metaspaceShared.hpp"
46 #include "memory/oopFactory.hpp"
47 #include "memory/resourceArea.hpp"
48 #include "memory/universe.inline.hpp"
49 #include "oops/instanceKlass.hpp"
50 #include "oops/objArrayOop.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/symbol.hpp"
53 #include "oops/verifyOopClosure.hpp"
54 #include "prims/jvm.h"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagWriteableList.hpp"
64 #include "runtime/commandLineFlagRangeList.hpp"
65 #include "runtime/deoptimization.hpp"
66 #include "runtime/fprofiler.hpp"
67 #include "runtime/frame.inline.hpp"
68 #include "runtime/globals.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/interfaceSupport.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/jniPeriodicChecker.hpp"
74 #include "runtime/timerTrace.hpp"
75 #include "runtime/memprofiler.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/objectMonitor.hpp"
78 #include "runtime/orderAccess.inline.hpp"
79 #include "runtime/osThread.hpp"
80 #include "runtime/safepoint.hpp"
81 #include "runtime/sharedRuntime.hpp"
82 #include "runtime/statSampler.hpp"
83 #include "runtime/stubRoutines.hpp"
84 #include "runtime/sweeper.hpp"
85 #include "runtime/task.hpp"
86 #include "runtime/thread.inline.hpp"
87 #include "runtime/threadCritical.hpp"
88 #include "runtime/vframe.hpp"
89 #include "runtime/vframeArray.hpp"
90 #include "runtime/vframe_hp.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "runtime/vm_operations.hpp"
93 #include "runtime/vm_version.hpp"
94 #include "services/attachListener.hpp"
95 #include "services/management.hpp"
96 #include "services/memTracker.hpp"
97 #include "services/threadService.hpp"
98 #include "trace/traceMacros.hpp"
99 #include "trace/tracing.hpp"
100 #include "utilities/align.hpp"
101 #include "utilities/defaultStream.hpp"
102 #include "utilities/dtrace.hpp"
103 #include "utilities/events.hpp"
104 #include "utilities/macros.hpp"
105 #include "utilities/preserveException.hpp"
106 #include "utilities/vmError.hpp"
107 #if INCLUDE_ALL_GCS
108 #include "gc/cms/concurrentMarkSweepThread.hpp"
109 #include "gc/g1/concurrentMarkThread.inline.hpp"
110 #include "gc/parallel/pcTasks.hpp"
111 #endif // INCLUDE_ALL_GCS
112 #if INCLUDE_JVMCI
113 #include "jvmci/jvmciCompiler.hpp"
114 #include "jvmci/jvmciRuntime.hpp"
115 #include "logging/logHandle.hpp"
116 #endif
117 #ifdef COMPILER1
118 #include "c1/c1_Compiler.hpp"
119 #endif
120 #ifdef COMPILER2
121 #include "opto/c2compiler.hpp"
122 #include "opto/idealGraphPrinter.hpp"
123 #endif
124 #if INCLUDE_RTM_OPT
125 #include "runtime/rtmLocking.hpp"
126 #endif
127
128 // Initialization after module runtime initialization
129 void universe_post_module_init(); // must happen after call_initPhase2
130
131 #ifdef DTRACE_ENABLED
132
133 // Only bother with this argument setup if dtrace is available
134
135 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
136 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
137
138 #define DTRACE_THREAD_PROBE(probe, javathread) \
139 { \
140 ResourceMark rm(this); \
141 int len = 0; \
142 const char* name = (javathread)->get_thread_name(); \
143 len = strlen(name); \
144 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
145 (char *) name, len, \
146 java_lang_Thread::thread_id((javathread)->threadObj()), \
147 (uintptr_t) (javathread)->osthread()->thread_id(), \
148 java_lang_Thread::is_daemon((javathread)->threadObj())); \
149 }
150
151 #else // ndef DTRACE_ENABLED
152
153 #define DTRACE_THREAD_PROBE(probe, javathread)
154
155 #endif // ndef DTRACE_ENABLED
156
157 #ifndef USE_LIBRARY_BASED_TLS_ONLY
158 // Current thread is maintained as a thread-local variable
159 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
160 #endif
161 // Class hierarchy
162 // - Thread
163 // - VMThread
164 // - WatcherThread
165 // - ConcurrentMarkSweepThread
166 // - JavaThread
167 // - CompilerThread
168
169 // ======= Thread ========
170 // Support for forcing alignment of thread objects for biased locking
171 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
172 if (UseBiasedLocking) {
173 const int alignment = markOopDesc::biased_lock_alignment;
174 size_t aligned_size = size + (alignment - sizeof(intptr_t));
175 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
176 : AllocateHeap(aligned_size, flags, CURRENT_PC,
177 AllocFailStrategy::RETURN_NULL);
178 void* aligned_addr = align_up(real_malloc_addr, alignment);
179 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
180 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
181 "JavaThread alignment code overflowed allocated storage");
182 if (aligned_addr != real_malloc_addr) {
183 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
184 p2i(real_malloc_addr),
185 p2i(aligned_addr));
186 }
187 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
188 return aligned_addr;
189 } else {
190 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
191 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
192 }
193 }
194
195 void Thread::operator delete(void* p) {
196 if (UseBiasedLocking) {
197 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
198 FreeHeap(real_malloc_addr);
199 } else {
200 FreeHeap(p);
201 }
202 }
203
204
205 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
206 // JavaThread
207
208
209 Thread::Thread() {
210 // stack and get_thread
211 set_stack_base(NULL);
212 set_stack_size(0);
213 set_self_raw_id(0);
214 set_lgrp_id(-1);
215 DEBUG_ONLY(clear_suspendible_thread();)
216
217 // allocated data structures
218 set_osthread(NULL);
219 set_resource_area(new (mtThread)ResourceArea());
220 DEBUG_ONLY(_current_resource_mark = NULL;)
221 set_handle_area(new (mtThread) HandleArea(NULL));
222 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
223 set_active_handles(NULL);
224 set_free_handle_block(NULL);
225 set_last_handle_mark(NULL);
226
227 // This initial value ==> never claimed.
228 _oops_do_parity = 0;
229
230 // the handle mark links itself to last_handle_mark
231 new HandleMark(this);
232
233 // plain initialization
234 debug_only(_owned_locks = NULL;)
235 debug_only(_allow_allocation_count = 0;)
236 NOT_PRODUCT(_allow_safepoint_count = 0;)
237 NOT_PRODUCT(_skip_gcalot = false;)
238 _jvmti_env_iteration_count = 0;
239 set_allocated_bytes(0);
240 _vm_operation_started_count = 0;
241 _vm_operation_completed_count = 0;
242 _current_pending_monitor = NULL;
243 _current_pending_monitor_is_from_java = true;
244 _current_waiting_monitor = NULL;
245 _num_nested_signal = 0;
246 omFreeList = NULL;
247 omFreeCount = 0;
248 omFreeProvision = 32;
249 omInUseList = NULL;
250 omInUseCount = 0;
251
252 #ifdef ASSERT
253 _visited_for_critical_count = false;
254 #endif
255
256 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
257 Monitor::_safepoint_check_sometimes);
258 _suspend_flags = 0;
259
260 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
261 _hashStateX = os::random();
262 _hashStateY = 842502087;
263 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
264 _hashStateW = 273326509;
265
266 _OnTrap = 0;
267 _schedctl = NULL;
268 _Stalled = 0;
269 _TypeTag = 0x2BAD;
270
271 // Many of the following fields are effectively final - immutable
272 // Note that nascent threads can't use the Native Monitor-Mutex
273 // construct until the _MutexEvent is initialized ...
274 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
275 // we might instead use a stack of ParkEvents that we could provision on-demand.
276 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
277 // and ::Release()
278 _ParkEvent = ParkEvent::Allocate(this);
279 _SleepEvent = ParkEvent::Allocate(this);
280 _MutexEvent = ParkEvent::Allocate(this);
281 _MuxEvent = ParkEvent::Allocate(this);
282
283 #ifdef CHECK_UNHANDLED_OOPS
284 if (CheckUnhandledOops) {
285 _unhandled_oops = new UnhandledOops(this);
286 }
287 #endif // CHECK_UNHANDLED_OOPS
288 #ifdef ASSERT
289 if (UseBiasedLocking) {
290 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
291 assert(this == _real_malloc_address ||
292 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
293 "bug in forced alignment of thread objects");
294 }
295 #endif // ASSERT
296 }
297
298 void Thread::initialize_thread_current() {
299 #ifndef USE_LIBRARY_BASED_TLS_ONLY
300 assert(_thr_current == NULL, "Thread::current already initialized");
301 _thr_current = this;
302 #endif
303 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
304 ThreadLocalStorage::set_thread(this);
305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
306 }
307
308 void Thread::clear_thread_current() {
309 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
310 #ifndef USE_LIBRARY_BASED_TLS_ONLY
311 _thr_current = NULL;
312 #endif
313 ThreadLocalStorage::set_thread(NULL);
314 }
315
316 void Thread::record_stack_base_and_size() {
317 set_stack_base(os::current_stack_base());
318 set_stack_size(os::current_stack_size());
319 // CR 7190089: on Solaris, primordial thread's stack is adjusted
320 // in initialize_thread(). Without the adjustment, stack size is
321 // incorrect if stack is set to unlimited (ulimit -s unlimited).
322 // So far, only Solaris has real implementation of initialize_thread().
323 //
324 // set up any platform-specific state.
325 os::initialize_thread(this);
326
327 // Set stack limits after thread is initialized.
328 if (is_Java_thread()) {
329 ((JavaThread*) this)->set_stack_overflow_limit();
330 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
331 }
332 #if INCLUDE_NMT
333 // record thread's native stack, stack grows downward
334 MemTracker::record_thread_stack(stack_end(), stack_size());
335 #endif // INCLUDE_NMT
336 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
337 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
338 os::current_thread_id(), p2i(stack_base() - stack_size()),
339 p2i(stack_base()), stack_size()/1024);
340 }
341
342
343 Thread::~Thread() {
344 EVENT_THREAD_DESTRUCT(this);
345
346 // stack_base can be NULL if the thread is never started or exited before
347 // record_stack_base_and_size called. Although, we would like to ensure
348 // that all started threads do call record_stack_base_and_size(), there is
349 // not proper way to enforce that.
350 #if INCLUDE_NMT
351 if (_stack_base != NULL) {
352 MemTracker::release_thread_stack(stack_end(), stack_size());
353 #ifdef ASSERT
354 set_stack_base(NULL);
355 #endif
356 }
357 #endif // INCLUDE_NMT
358
359 // deallocate data structures
360 delete resource_area();
361 // since the handle marks are using the handle area, we have to deallocated the root
362 // handle mark before deallocating the thread's handle area,
363 assert(last_handle_mark() != NULL, "check we have an element");
364 delete last_handle_mark();
365 assert(last_handle_mark() == NULL, "check we have reached the end");
366
367 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
368 // We NULL out the fields for good hygiene.
369 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
370 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
371 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
372 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
373
374 delete handle_area();
375 delete metadata_handles();
376
377 // SR_handler uses this as a termination indicator -
378 // needs to happen before os::free_thread()
379 delete _SR_lock;
380 _SR_lock = NULL;
381
382 // osthread() can be NULL, if creation of thread failed.
383 if (osthread() != NULL) os::free_thread(osthread());
384
385 // clear Thread::current if thread is deleting itself.
386 // Needed to ensure JNI correctly detects non-attached threads.
387 if (this == Thread::current()) {
388 clear_thread_current();
389 }
390
391 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
392 }
393
394 // NOTE: dummy function for assertion purpose.
395 void Thread::run() {
396 ShouldNotReachHere();
397 }
398
399 #ifdef ASSERT
400 // Private method to check for dangling thread pointer
401 void check_for_dangling_thread_pointer(Thread *thread) {
402 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
403 "possibility of dangling Thread pointer");
404 }
405 #endif
406
407 ThreadPriority Thread::get_priority(const Thread* const thread) {
408 ThreadPriority priority;
409 // Can return an error!
410 (void)os::get_priority(thread, priority);
411 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
412 return priority;
413 }
414
415 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
416 debug_only(check_for_dangling_thread_pointer(thread);)
417 // Can return an error!
418 (void)os::set_priority(thread, priority);
419 }
420
421
422 void Thread::start(Thread* thread) {
423 // Start is different from resume in that its safety is guaranteed by context or
424 // being called from a Java method synchronized on the Thread object.
425 if (!DisableStartThread) {
426 if (thread->is_Java_thread()) {
427 // Initialize the thread state to RUNNABLE before starting this thread.
428 // Can not set it after the thread started because we do not know the
429 // exact thread state at that time. It could be in MONITOR_WAIT or
430 // in SLEEPING or some other state.
431 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
432 java_lang_Thread::RUNNABLE);
433 }
434 os::start_thread(thread);
435 }
436 }
437
438 // Enqueue a VM_Operation to do the job for us - sometime later
439 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
440 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
441 VMThread::execute(vm_stop);
442 }
443
444
445 // Check if an external suspend request has completed (or has been
446 // cancelled). Returns true if the thread is externally suspended and
447 // false otherwise.
448 //
449 // The bits parameter returns information about the code path through
450 // the routine. Useful for debugging:
451 //
452 // set in is_ext_suspend_completed():
453 // 0x00000001 - routine was entered
454 // 0x00000010 - routine return false at end
455 // 0x00000100 - thread exited (return false)
456 // 0x00000200 - suspend request cancelled (return false)
457 // 0x00000400 - thread suspended (return true)
458 // 0x00001000 - thread is in a suspend equivalent state (return true)
459 // 0x00002000 - thread is native and walkable (return true)
460 // 0x00004000 - thread is native_trans and walkable (needed retry)
461 //
462 // set in wait_for_ext_suspend_completion():
463 // 0x00010000 - routine was entered
464 // 0x00020000 - suspend request cancelled before loop (return false)
465 // 0x00040000 - thread suspended before loop (return true)
466 // 0x00080000 - suspend request cancelled in loop (return false)
467 // 0x00100000 - thread suspended in loop (return true)
468 // 0x00200000 - suspend not completed during retry loop (return false)
469
470 // Helper class for tracing suspend wait debug bits.
471 //
472 // 0x00000100 indicates that the target thread exited before it could
473 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
474 // 0x00080000 each indicate a cancelled suspend request so they don't
475 // count as wait failures either.
476 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
477
478 class TraceSuspendDebugBits : public StackObj {
479 private:
480 JavaThread * jt;
481 bool is_wait;
482 bool called_by_wait; // meaningful when !is_wait
483 uint32_t * bits;
484
485 public:
486 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
487 uint32_t *_bits) {
488 jt = _jt;
489 is_wait = _is_wait;
490 called_by_wait = _called_by_wait;
491 bits = _bits;
492 }
493
494 ~TraceSuspendDebugBits() {
495 if (!is_wait) {
496 #if 1
497 // By default, don't trace bits for is_ext_suspend_completed() calls.
498 // That trace is very chatty.
499 return;
500 #else
501 if (!called_by_wait) {
502 // If tracing for is_ext_suspend_completed() is enabled, then only
503 // trace calls to it from wait_for_ext_suspend_completion()
504 return;
505 }
506 #endif
507 }
508
509 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
510 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
511 MutexLocker ml(Threads_lock); // needed for get_thread_name()
512 ResourceMark rm;
513
514 tty->print_cr(
515 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
516 jt->get_thread_name(), *bits);
517
518 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
519 }
520 }
521 }
522 };
523 #undef DEBUG_FALSE_BITS
524
525
526 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
527 uint32_t *bits) {
528 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
529
530 bool did_trans_retry = false; // only do thread_in_native_trans retry once
531 bool do_trans_retry; // flag to force the retry
532
533 *bits |= 0x00000001;
534
535 do {
536 do_trans_retry = false;
537
538 if (is_exiting()) {
539 // Thread is in the process of exiting. This is always checked
540 // first to reduce the risk of dereferencing a freed JavaThread.
541 *bits |= 0x00000100;
542 return false;
543 }
544
545 if (!is_external_suspend()) {
546 // Suspend request is cancelled. This is always checked before
547 // is_ext_suspended() to reduce the risk of a rogue resume
548 // confusing the thread that made the suspend request.
549 *bits |= 0x00000200;
550 return false;
551 }
552
553 if (is_ext_suspended()) {
554 // thread is suspended
555 *bits |= 0x00000400;
556 return true;
557 }
558
559 // Now that we no longer do hard suspends of threads running
560 // native code, the target thread can be changing thread state
561 // while we are in this routine:
562 //
563 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
564 //
565 // We save a copy of the thread state as observed at this moment
566 // and make our decision about suspend completeness based on the
567 // copy. This closes the race where the thread state is seen as
568 // _thread_in_native_trans in the if-thread_blocked check, but is
569 // seen as _thread_blocked in if-thread_in_native_trans check.
570 JavaThreadState save_state = thread_state();
571
572 if (save_state == _thread_blocked && is_suspend_equivalent()) {
573 // If the thread's state is _thread_blocked and this blocking
574 // condition is known to be equivalent to a suspend, then we can
575 // consider the thread to be externally suspended. This means that
576 // the code that sets _thread_blocked has been modified to do
577 // self-suspension if the blocking condition releases. We also
578 // used to check for CONDVAR_WAIT here, but that is now covered by
579 // the _thread_blocked with self-suspension check.
580 //
581 // Return true since we wouldn't be here unless there was still an
582 // external suspend request.
583 *bits |= 0x00001000;
584 return true;
585 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
586 // Threads running native code will self-suspend on native==>VM/Java
587 // transitions. If its stack is walkable (should always be the case
588 // unless this function is called before the actual java_suspend()
589 // call), then the wait is done.
590 *bits |= 0x00002000;
591 return true;
592 } else if (!called_by_wait && !did_trans_retry &&
593 save_state == _thread_in_native_trans &&
594 frame_anchor()->walkable()) {
595 // The thread is transitioning from thread_in_native to another
596 // thread state. check_safepoint_and_suspend_for_native_trans()
597 // will force the thread to self-suspend. If it hasn't gotten
598 // there yet we may have caught the thread in-between the native
599 // code check above and the self-suspend. Lucky us. If we were
600 // called by wait_for_ext_suspend_completion(), then it
601 // will be doing the retries so we don't have to.
602 //
603 // Since we use the saved thread state in the if-statement above,
604 // there is a chance that the thread has already transitioned to
605 // _thread_blocked by the time we get here. In that case, we will
606 // make a single unnecessary pass through the logic below. This
607 // doesn't hurt anything since we still do the trans retry.
608
609 *bits |= 0x00004000;
610
611 // Once the thread leaves thread_in_native_trans for another
612 // thread state, we break out of this retry loop. We shouldn't
613 // need this flag to prevent us from getting back here, but
614 // sometimes paranoia is good.
615 did_trans_retry = true;
616
617 // We wait for the thread to transition to a more usable state.
618 for (int i = 1; i <= SuspendRetryCount; i++) {
619 // We used to do an "os::yield_all(i)" call here with the intention
620 // that yielding would increase on each retry. However, the parameter
621 // is ignored on Linux which means the yield didn't scale up. Waiting
622 // on the SR_lock below provides a much more predictable scale up for
623 // the delay. It also provides a simple/direct point to check for any
624 // safepoint requests from the VMThread
625
626 // temporarily drops SR_lock while doing wait with safepoint check
627 // (if we're a JavaThread - the WatcherThread can also call this)
628 // and increase delay with each retry
629 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
630
631 // check the actual thread state instead of what we saved above
632 if (thread_state() != _thread_in_native_trans) {
633 // the thread has transitioned to another thread state so
634 // try all the checks (except this one) one more time.
635 do_trans_retry = true;
636 break;
637 }
638 } // end retry loop
639
640
641 }
642 } while (do_trans_retry);
643
644 *bits |= 0x00000010;
645 return false;
646 }
647
648 // Wait for an external suspend request to complete (or be cancelled).
649 // Returns true if the thread is externally suspended and false otherwise.
650 //
651 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
652 uint32_t *bits) {
653 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
654 false /* !called_by_wait */, bits);
655
656 // local flag copies to minimize SR_lock hold time
657 bool is_suspended;
658 bool pending;
659 uint32_t reset_bits;
660
661 // set a marker so is_ext_suspend_completed() knows we are the caller
662 *bits |= 0x00010000;
663
664 // We use reset_bits to reinitialize the bits value at the top of
665 // each retry loop. This allows the caller to make use of any
666 // unused bits for their own marking purposes.
667 reset_bits = *bits;
668
669 {
670 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
671 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
672 delay, bits);
673 pending = is_external_suspend();
674 }
675 // must release SR_lock to allow suspension to complete
676
677 if (!pending) {
678 // A cancelled suspend request is the only false return from
679 // is_ext_suspend_completed() that keeps us from entering the
680 // retry loop.
681 *bits |= 0x00020000;
682 return false;
683 }
684
685 if (is_suspended) {
686 *bits |= 0x00040000;
687 return true;
688 }
689
690 for (int i = 1; i <= retries; i++) {
691 *bits = reset_bits; // reinit to only track last retry
692
693 // We used to do an "os::yield_all(i)" call here with the intention
694 // that yielding would increase on each retry. However, the parameter
695 // is ignored on Linux which means the yield didn't scale up. Waiting
696 // on the SR_lock below provides a much more predictable scale up for
697 // the delay. It also provides a simple/direct point to check for any
698 // safepoint requests from the VMThread
699
700 {
701 MutexLocker ml(SR_lock());
702 // wait with safepoint check (if we're a JavaThread - the WatcherThread
703 // can also call this) and increase delay with each retry
704 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
705
706 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
707 delay, bits);
708
709 // It is possible for the external suspend request to be cancelled
710 // (by a resume) before the actual suspend operation is completed.
711 // Refresh our local copy to see if we still need to wait.
712 pending = is_external_suspend();
713 }
714
715 if (!pending) {
716 // A cancelled suspend request is the only false return from
717 // is_ext_suspend_completed() that keeps us from staying in the
718 // retry loop.
719 *bits |= 0x00080000;
720 return false;
721 }
722
723 if (is_suspended) {
724 *bits |= 0x00100000;
725 return true;
726 }
727 } // end retry loop
728
729 // thread did not suspend after all our retries
730 *bits |= 0x00200000;
731 return false;
732 }
733
734 #ifndef PRODUCT
735 void JavaThread::record_jump(address target, address instr, const char* file,
736 int line) {
737
738 // This should not need to be atomic as the only way for simultaneous
739 // updates is via interrupts. Even then this should be rare or non-existent
740 // and we don't care that much anyway.
741
742 int index = _jmp_ring_index;
743 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
744 _jmp_ring[index]._target = (intptr_t) target;
745 _jmp_ring[index]._instruction = (intptr_t) instr;
746 _jmp_ring[index]._file = file;
747 _jmp_ring[index]._line = line;
748 }
749 #endif // PRODUCT
750
751 // Called by flat profiler
752 // Callers have already called wait_for_ext_suspend_completion
753 // The assertion for that is currently too complex to put here:
754 bool JavaThread::profile_last_Java_frame(frame* _fr) {
755 bool gotframe = false;
756 // self suspension saves needed state.
757 if (has_last_Java_frame() && _anchor.walkable()) {
758 *_fr = pd_last_frame();
759 gotframe = true;
760 }
761 return gotframe;
762 }
763
764 void Thread::interrupt(Thread* thread) {
765 debug_only(check_for_dangling_thread_pointer(thread);)
766 os::interrupt(thread);
767 }
768
769 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
770 debug_only(check_for_dangling_thread_pointer(thread);)
771 // Note: If clear_interrupted==false, this simply fetches and
772 // returns the value of the field osthread()->interrupted().
773 return os::is_interrupted(thread, clear_interrupted);
774 }
775
776
777 // GC Support
778 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
779 jint thread_parity = _oops_do_parity;
780 if (thread_parity != strong_roots_parity) {
781 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
782 if (res == thread_parity) {
783 return true;
784 } else {
785 guarantee(res == strong_roots_parity, "Or else what?");
786 return false;
787 }
788 }
789 return false;
790 }
791
792 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
793 active_handles()->oops_do(f);
794 // Do oop for ThreadShadow
795 f->do_oop((oop*)&_pending_exception);
796 handle_area()->oops_do(f);
797
798 if (MonitorInUseLists) {
799 // When using thread local monitor lists, we scan them here,
800 // and the remaining global monitors in ObjectSynchronizer::oops_do().
801 ObjectSynchronizer::thread_local_used_oops_do(this, f);
802 }
803 }
804
805 void Thread::metadata_handles_do(void f(Metadata*)) {
806 // Only walk the Handles in Thread.
807 if (metadata_handles() != NULL) {
808 for (int i = 0; i< metadata_handles()->length(); i++) {
809 f(metadata_handles()->at(i));
810 }
811 }
812 }
813
814 void Thread::print_on(outputStream* st) const {
815 // get_priority assumes osthread initialized
816 if (osthread() != NULL) {
817 int os_prio;
818 if (os::get_native_priority(this, &os_prio) == OS_OK) {
819 st->print("os_prio=%d ", os_prio);
820 }
821 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
822 ext().print_on(st);
823 osthread()->print_on(st);
824 }
825 debug_only(if (WizardMode) print_owned_locks_on(st);)
826 }
827
828 // Thread::print_on_error() is called by fatal error handler. Don't use
829 // any lock or allocate memory.
830 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
831 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
832
833 if (is_VM_thread()) { st->print("VMThread"); }
834 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
835 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
836 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
837 else { st->print("Thread"); }
838
839 if (is_Named_thread()) {
840 st->print(" \"%s\"", name());
841 }
842
843 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
844 p2i(stack_end()), p2i(stack_base()));
845
846 if (osthread()) {
847 st->print(" [id=%d]", osthread()->thread_id());
848 }
849 }
850
851 void Thread::print_value_on(outputStream* st) const {
852 if (is_Named_thread()) {
853 st->print(" \"%s\" ", name());
854 }
855 st->print(INTPTR_FORMAT, p2i(this)); // print address
856 }
857
858 #ifdef ASSERT
859 void Thread::print_owned_locks_on(outputStream* st) const {
860 Monitor *cur = _owned_locks;
861 if (cur == NULL) {
862 st->print(" (no locks) ");
863 } else {
864 st->print_cr(" Locks owned:");
865 while (cur) {
866 cur->print_on(st);
867 cur = cur->next();
868 }
869 }
870 }
871
872 static int ref_use_count = 0;
873
874 bool Thread::owns_locks_but_compiled_lock() const {
875 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
876 if (cur != Compile_lock) return true;
877 }
878 return false;
879 }
880
881
882 #endif
883
884 #ifndef PRODUCT
885
886 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
887 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
888 // no threads which allow_vm_block's are held
889 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
890 // Check if current thread is allowed to block at a safepoint
891 if (!(_allow_safepoint_count == 0)) {
892 fatal("Possible safepoint reached by thread that does not allow it");
893 }
894 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
895 fatal("LEAF method calling lock?");
896 }
897
898 #ifdef ASSERT
899 if (potential_vm_operation && is_Java_thread()
900 && !Universe::is_bootstrapping()) {
901 // Make sure we do not hold any locks that the VM thread also uses.
902 // This could potentially lead to deadlocks
903 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
904 // Threads_lock is special, since the safepoint synchronization will not start before this is
905 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
906 // since it is used to transfer control between JavaThreads and the VMThread
907 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
908 if ((cur->allow_vm_block() &&
909 cur != Threads_lock &&
910 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
911 cur != VMOperationRequest_lock &&
912 cur != VMOperationQueue_lock) ||
913 cur->rank() == Mutex::special) {
914 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
915 }
916 }
917 }
918
919 if (GCALotAtAllSafepoints) {
920 // We could enter a safepoint here and thus have a gc
921 InterfaceSupport::check_gc_alot();
922 }
923 #endif
924 }
925 #endif
926
927 bool Thread::is_in_stack(address adr) const {
928 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
929 address end = os::current_stack_pointer();
930 // Allow non Java threads to call this without stack_base
931 if (_stack_base == NULL) return true;
932 if (stack_base() >= adr && adr >= end) return true;
933
934 return false;
935 }
936
937 bool Thread::is_in_usable_stack(address adr) const {
938 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
939 size_t usable_stack_size = _stack_size - stack_guard_size;
940
941 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
942 }
943
944
945 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
946 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
947 // used for compilation in the future. If that change is made, the need for these methods
948 // should be revisited, and they should be removed if possible.
949
950 bool Thread::is_lock_owned(address adr) const {
951 return on_local_stack(adr);
952 }
953
954 bool Thread::set_as_starting_thread() {
955 // NOTE: this must be called inside the main thread.
956 return os::create_main_thread((JavaThread*)this);
957 }
958
959 static void initialize_class(Symbol* class_name, TRAPS) {
960 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
961 InstanceKlass::cast(klass)->initialize(CHECK);
962 }
963
964
965 // Creates the initial ThreadGroup
966 static Handle create_initial_thread_group(TRAPS) {
967 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
968 InstanceKlass* ik = InstanceKlass::cast(k);
969
970 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
971 {
972 JavaValue result(T_VOID);
973 JavaCalls::call_special(&result,
974 system_instance,
975 ik,
976 vmSymbols::object_initializer_name(),
977 vmSymbols::void_method_signature(),
978 CHECK_NH);
979 }
980 Universe::set_system_thread_group(system_instance());
981
982 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
983 {
984 JavaValue result(T_VOID);
985 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
986 JavaCalls::call_special(&result,
987 main_instance,
988 ik,
989 vmSymbols::object_initializer_name(),
990 vmSymbols::threadgroup_string_void_signature(),
991 system_instance,
992 string,
993 CHECK_NH);
994 }
995 return main_instance;
996 }
997
998 // Creates the initial Thread
999 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1000 TRAPS) {
1001 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1002 InstanceKlass* ik = InstanceKlass::cast(k);
1003 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1004
1005 java_lang_Thread::set_thread(thread_oop(), thread);
1006 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1007 thread->set_threadObj(thread_oop());
1008
1009 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1010
1011 JavaValue result(T_VOID);
1012 JavaCalls::call_special(&result, thread_oop,
1013 ik,
1014 vmSymbols::object_initializer_name(),
1015 vmSymbols::threadgroup_string_void_signature(),
1016 thread_group,
1017 string,
1018 CHECK_NULL);
1019 return thread_oop();
1020 }
1021
1022 char java_runtime_name[128] = "";
1023 char java_runtime_version[128] = "";
1024
1025 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1026 static const char* get_java_runtime_name(TRAPS) {
1027 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1028 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1029 fieldDescriptor fd;
1030 bool found = k != NULL &&
1031 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1032 vmSymbols::string_signature(), &fd);
1033 if (found) {
1034 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1035 if (name_oop == NULL) {
1036 return NULL;
1037 }
1038 const char* name = java_lang_String::as_utf8_string(name_oop,
1039 java_runtime_name,
1040 sizeof(java_runtime_name));
1041 return name;
1042 } else {
1043 return NULL;
1044 }
1045 }
1046
1047 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1048 static const char* get_java_runtime_version(TRAPS) {
1049 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1050 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1051 fieldDescriptor fd;
1052 bool found = k != NULL &&
1053 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1054 vmSymbols::string_signature(), &fd);
1055 if (found) {
1056 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1057 if (name_oop == NULL) {
1058 return NULL;
1059 }
1060 const char* name = java_lang_String::as_utf8_string(name_oop,
1061 java_runtime_version,
1062 sizeof(java_runtime_version));
1063 return name;
1064 } else {
1065 return NULL;
1066 }
1067 }
1068
1069 // General purpose hook into Java code, run once when the VM is initialized.
1070 // The Java library method itself may be changed independently from the VM.
1071 static void call_postVMInitHook(TRAPS) {
1072 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1073 if (klass != NULL) {
1074 JavaValue result(T_VOID);
1075 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1076 vmSymbols::void_method_signature(),
1077 CHECK);
1078 }
1079 }
1080
1081 static void reset_vm_info_property(TRAPS) {
1082 // the vm info string
1083 ResourceMark rm(THREAD);
1084 const char *vm_info = VM_Version::vm_info_string();
1085
1086 // java.lang.System class
1087 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1088
1089 // setProperty arguments
1090 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1091 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1092
1093 // return value
1094 JavaValue r(T_OBJECT);
1095
1096 // public static String setProperty(String key, String value);
1097 JavaCalls::call_static(&r,
1098 klass,
1099 vmSymbols::setProperty_name(),
1100 vmSymbols::string_string_string_signature(),
1101 key_str,
1102 value_str,
1103 CHECK);
1104 }
1105
1106
1107 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1108 bool daemon, TRAPS) {
1109 assert(thread_group.not_null(), "thread group should be specified");
1110 assert(threadObj() == NULL, "should only create Java thread object once");
1111
1112 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1113 InstanceKlass* ik = InstanceKlass::cast(k);
1114 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1115
1116 java_lang_Thread::set_thread(thread_oop(), this);
1117 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1118 set_threadObj(thread_oop());
1119
1120 JavaValue result(T_VOID);
1121 if (thread_name != NULL) {
1122 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1123 // Thread gets assigned specified name and null target
1124 JavaCalls::call_special(&result,
1125 thread_oop,
1126 ik,
1127 vmSymbols::object_initializer_name(),
1128 vmSymbols::threadgroup_string_void_signature(),
1129 thread_group, // Argument 1
1130 name, // Argument 2
1131 THREAD);
1132 } else {
1133 // Thread gets assigned name "Thread-nnn" and null target
1134 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1135 JavaCalls::call_special(&result,
1136 thread_oop,
1137 ik,
1138 vmSymbols::object_initializer_name(),
1139 vmSymbols::threadgroup_runnable_void_signature(),
1140 thread_group, // Argument 1
1141 Handle(), // Argument 2
1142 THREAD);
1143 }
1144
1145
1146 if (daemon) {
1147 java_lang_Thread::set_daemon(thread_oop());
1148 }
1149
1150 if (HAS_PENDING_EXCEPTION) {
1151 return;
1152 }
1153
1154 Klass* group = SystemDictionary::ThreadGroup_klass();
1155 Handle threadObj(THREAD, this->threadObj());
1156
1157 JavaCalls::call_special(&result,
1158 thread_group,
1159 group,
1160 vmSymbols::add_method_name(),
1161 vmSymbols::thread_void_signature(),
1162 threadObj, // Arg 1
1163 THREAD);
1164 }
1165
1166 // NamedThread -- non-JavaThread subclasses with multiple
1167 // uniquely named instances should derive from this.
1168 NamedThread::NamedThread() : Thread() {
1169 _name = NULL;
1170 _processed_thread = NULL;
1171 _gc_id = GCId::undefined();
1172 }
1173
1174 NamedThread::~NamedThread() {
1175 if (_name != NULL) {
1176 FREE_C_HEAP_ARRAY(char, _name);
1177 _name = NULL;
1178 }
1179 }
1180
1181 void NamedThread::set_name(const char* format, ...) {
1182 guarantee(_name == NULL, "Only get to set name once.");
1183 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1184 guarantee(_name != NULL, "alloc failure");
1185 va_list ap;
1186 va_start(ap, format);
1187 jio_vsnprintf(_name, max_name_len, format, ap);
1188 va_end(ap);
1189 }
1190
1191 void NamedThread::initialize_named_thread() {
1192 set_native_thread_name(name());
1193 }
1194
1195 void NamedThread::print_on(outputStream* st) const {
1196 st->print("\"%s\" ", name());
1197 Thread::print_on(st);
1198 st->cr();
1199 }
1200
1201
1202 // ======= WatcherThread ========
1203
1204 // The watcher thread exists to simulate timer interrupts. It should
1205 // be replaced by an abstraction over whatever native support for
1206 // timer interrupts exists on the platform.
1207
1208 WatcherThread* WatcherThread::_watcher_thread = NULL;
1209 bool WatcherThread::_startable = false;
1210 volatile bool WatcherThread::_should_terminate = false;
1211
1212 WatcherThread::WatcherThread() : Thread() {
1213 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1214 if (os::create_thread(this, os::watcher_thread)) {
1215 _watcher_thread = this;
1216
1217 // Set the watcher thread to the highest OS priority which should not be
1218 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1219 // is created. The only normal thread using this priority is the reference
1220 // handler thread, which runs for very short intervals only.
1221 // If the VMThread's priority is not lower than the WatcherThread profiling
1222 // will be inaccurate.
1223 os::set_priority(this, MaxPriority);
1224 if (!DisableStartThread) {
1225 os::start_thread(this);
1226 }
1227 }
1228 }
1229
1230 int WatcherThread::sleep() const {
1231 // The WatcherThread does not participate in the safepoint protocol
1232 // for the PeriodicTask_lock because it is not a JavaThread.
1233 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1234
1235 if (_should_terminate) {
1236 // check for termination before we do any housekeeping or wait
1237 return 0; // we did not sleep.
1238 }
1239
1240 // remaining will be zero if there are no tasks,
1241 // causing the WatcherThread to sleep until a task is
1242 // enrolled
1243 int remaining = PeriodicTask::time_to_wait();
1244 int time_slept = 0;
1245
1246 // we expect this to timeout - we only ever get unparked when
1247 // we should terminate or when a new task has been enrolled
1248 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1249
1250 jlong time_before_loop = os::javaTimeNanos();
1251
1252 while (true) {
1253 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1254 remaining);
1255 jlong now = os::javaTimeNanos();
1256
1257 if (remaining == 0) {
1258 // if we didn't have any tasks we could have waited for a long time
1259 // consider the time_slept zero and reset time_before_loop
1260 time_slept = 0;
1261 time_before_loop = now;
1262 } else {
1263 // need to recalculate since we might have new tasks in _tasks
1264 time_slept = (int) ((now - time_before_loop) / 1000000);
1265 }
1266
1267 // Change to task list or spurious wakeup of some kind
1268 if (timedout || _should_terminate) {
1269 break;
1270 }
1271
1272 remaining = PeriodicTask::time_to_wait();
1273 if (remaining == 0) {
1274 // Last task was just disenrolled so loop around and wait until
1275 // another task gets enrolled
1276 continue;
1277 }
1278
1279 remaining -= time_slept;
1280 if (remaining <= 0) {
1281 break;
1282 }
1283 }
1284
1285 return time_slept;
1286 }
1287
1288 void WatcherThread::run() {
1289 assert(this == watcher_thread(), "just checking");
1290
1291 this->record_stack_base_and_size();
1292 this->set_native_thread_name(this->name());
1293 this->set_active_handles(JNIHandleBlock::allocate_block());
1294 while (true) {
1295 assert(watcher_thread() == Thread::current(), "thread consistency check");
1296 assert(watcher_thread() == this, "thread consistency check");
1297
1298 // Calculate how long it'll be until the next PeriodicTask work
1299 // should be done, and sleep that amount of time.
1300 int time_waited = sleep();
1301
1302 if (VMError::is_error_reported()) {
1303 // A fatal error has happened, the error handler(VMError::report_and_die)
1304 // should abort JVM after creating an error log file. However in some
1305 // rare cases, the error handler itself might deadlock. Here periodically
1306 // check for error reporting timeouts, and if it happens, just proceed to
1307 // abort the VM.
1308
1309 // This code is in WatcherThread because WatcherThread wakes up
1310 // periodically so the fatal error handler doesn't need to do anything;
1311 // also because the WatcherThread is less likely to crash than other
1312 // threads.
1313
1314 for (;;) {
1315 // Note: we use naked sleep in this loop because we want to avoid using
1316 // any kind of VM infrastructure which may be broken at this point.
1317 if (VMError::check_timeout()) {
1318 // We hit error reporting timeout. Error reporting was interrupted and
1319 // will be wrapping things up now (closing files etc). Give it some more
1320 // time, then quit the VM.
1321 os::naked_short_sleep(200);
1322 // Print a message to stderr.
1323 fdStream err(defaultStream::output_fd());
1324 err.print_raw_cr("# [ timer expired, abort... ]");
1325 // skip atexit/vm_exit/vm_abort hooks
1326 os::die();
1327 }
1328
1329 // Wait a second, then recheck for timeout.
1330 os::naked_short_sleep(999);
1331 }
1332 }
1333
1334 if (_should_terminate) {
1335 // check for termination before posting the next tick
1336 break;
1337 }
1338
1339 PeriodicTask::real_time_tick(time_waited);
1340 }
1341
1342 // Signal that it is terminated
1343 {
1344 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1345 _watcher_thread = NULL;
1346 Terminator_lock->notify();
1347 }
1348 }
1349
1350 void WatcherThread::start() {
1351 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1352
1353 if (watcher_thread() == NULL && _startable) {
1354 _should_terminate = false;
1355 // Create the single instance of WatcherThread
1356 new WatcherThread();
1357 }
1358 }
1359
1360 void WatcherThread::make_startable() {
1361 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1362 _startable = true;
1363 }
1364
1365 void WatcherThread::stop() {
1366 {
1367 // Follow normal safepoint aware lock enter protocol since the
1368 // WatcherThread is stopped by another JavaThread.
1369 MutexLocker ml(PeriodicTask_lock);
1370 _should_terminate = true;
1371
1372 WatcherThread* watcher = watcher_thread();
1373 if (watcher != NULL) {
1374 // unpark the WatcherThread so it can see that it should terminate
1375 watcher->unpark();
1376 }
1377 }
1378
1379 MutexLocker mu(Terminator_lock);
1380
1381 while (watcher_thread() != NULL) {
1382 // This wait should make safepoint checks, wait without a timeout,
1383 // and wait as a suspend-equivalent condition.
1384 //
1385 // Note: If the FlatProfiler is running, then this thread is waiting
1386 // for the WatcherThread to terminate and the WatcherThread, via the
1387 // FlatProfiler task, is waiting for the external suspend request on
1388 // this thread to complete. wait_for_ext_suspend_completion() will
1389 // eventually timeout, but that takes time. Making this wait a
1390 // suspend-equivalent condition solves that timeout problem.
1391 //
1392 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1393 Mutex::_as_suspend_equivalent_flag);
1394 }
1395 }
1396
1397 void WatcherThread::unpark() {
1398 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1399 PeriodicTask_lock->notify();
1400 }
1401
1402 void WatcherThread::print_on(outputStream* st) const {
1403 st->print("\"%s\" ", name());
1404 Thread::print_on(st);
1405 st->cr();
1406 }
1407
1408 // ======= JavaThread ========
1409
1410 #if INCLUDE_JVMCI
1411
1412 jlong* JavaThread::_jvmci_old_thread_counters;
1413
1414 bool jvmci_counters_include(JavaThread* thread) {
1415 oop threadObj = thread->threadObj();
1416 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1417 }
1418
1419 void JavaThread::collect_counters(typeArrayOop array) {
1420 if (JVMCICounterSize > 0) {
1421 MutexLocker tl(Threads_lock);
1422 for (int i = 0; i < array->length(); i++) {
1423 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1424 }
1425 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1426 if (jvmci_counters_include(tp)) {
1427 for (int i = 0; i < array->length(); i++) {
1428 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1429 }
1430 }
1431 }
1432 }
1433 }
1434
1435 #endif // INCLUDE_JVMCI
1436
1437 // A JavaThread is a normal Java thread
1438
1439 void JavaThread::initialize() {
1440 // Initialize fields
1441
1442 set_saved_exception_pc(NULL);
1443 set_threadObj(NULL);
1444 _anchor.clear();
1445 set_entry_point(NULL);
1446 set_jni_functions(jni_functions());
1447 set_callee_target(NULL);
1448 set_vm_result(NULL);
1449 set_vm_result_2(NULL);
1450 set_vframe_array_head(NULL);
1451 set_vframe_array_last(NULL);
1452 set_deferred_locals(NULL);
1453 set_deopt_mark(NULL);
1454 set_deopt_compiled_method(NULL);
1455 clear_must_deopt_id();
1456 set_monitor_chunks(NULL);
1457 set_next(NULL);
1458 set_thread_state(_thread_new);
1459 _terminated = _not_terminated;
1460 _privileged_stack_top = NULL;
1461 _array_for_gc = NULL;
1462 _suspend_equivalent = false;
1463 _in_deopt_handler = 0;
1464 _doing_unsafe_access = false;
1465 _stack_guard_state = stack_guard_unused;
1466 #if INCLUDE_JVMCI
1467 _pending_monitorenter = false;
1468 _pending_deoptimization = -1;
1469 _pending_failed_speculation = NULL;
1470 _pending_transfer_to_interpreter = false;
1471 _adjusting_comp_level = false;
1472 _jvmci._alternate_call_target = NULL;
1473 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1474 if (JVMCICounterSize > 0) {
1475 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1476 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1477 } else {
1478 _jvmci_counters = NULL;
1479 }
1480 #endif // INCLUDE_JVMCI
1481 _reserved_stack_activation = NULL; // stack base not known yet
1482 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1483 _exception_pc = 0;
1484 _exception_handler_pc = 0;
1485 _is_method_handle_return = 0;
1486 _jvmti_thread_state= NULL;
1487 _should_post_on_exceptions_flag = JNI_FALSE;
1488 _jvmti_get_loaded_classes_closure = NULL;
1489 _interp_only_mode = 0;
1490 _special_runtime_exit_condition = _no_async_condition;
1491 _pending_async_exception = NULL;
1492 _thread_stat = NULL;
1493 _thread_stat = new ThreadStatistics();
1494 _blocked_on_compilation = false;
1495 _jni_active_critical = 0;
1496 _pending_jni_exception_check_fn = NULL;
1497 _do_not_unlock_if_synchronized = false;
1498 _cached_monitor_info = NULL;
1499 _parker = Parker::Allocate(this);
1500
1501 #ifndef PRODUCT
1502 _jmp_ring_index = 0;
1503 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1504 record_jump(NULL, NULL, NULL, 0);
1505 }
1506 #endif // PRODUCT
1507
1508 set_thread_profiler(NULL);
1509 if (FlatProfiler::is_active()) {
1510 // This is where we would decide to either give each thread it's own profiler
1511 // or use one global one from FlatProfiler,
1512 // or up to some count of the number of profiled threads, etc.
1513 ThreadProfiler* pp = new ThreadProfiler();
1514 pp->engage();
1515 set_thread_profiler(pp);
1516 }
1517
1518 // Setup safepoint state info for this thread
1519 ThreadSafepointState::create(this);
1520
1521 debug_only(_java_call_counter = 0);
1522
1523 // JVMTI PopFrame support
1524 _popframe_condition = popframe_inactive;
1525 _popframe_preserved_args = NULL;
1526 _popframe_preserved_args_size = 0;
1527 _frames_to_pop_failed_realloc = 0;
1528
1529 pd_initialize();
1530 }
1531
1532 #if INCLUDE_ALL_GCS
1533 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1534 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1535 #endif // INCLUDE_ALL_GCS
1536
1537 JavaThread::JavaThread(bool is_attaching_via_jni) :
1538 Thread()
1539 #if INCLUDE_ALL_GCS
1540 , _satb_mark_queue(&_satb_mark_queue_set),
1541 _dirty_card_queue(&_dirty_card_queue_set)
1542 #endif // INCLUDE_ALL_GCS
1543 {
1544 initialize();
1545 if (is_attaching_via_jni) {
1546 _jni_attach_state = _attaching_via_jni;
1547 } else {
1548 _jni_attach_state = _not_attaching_via_jni;
1549 }
1550 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1551 }
1552
1553 bool JavaThread::reguard_stack(address cur_sp) {
1554 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1555 && _stack_guard_state != stack_guard_reserved_disabled) {
1556 return true; // Stack already guarded or guard pages not needed.
1557 }
1558
1559 if (register_stack_overflow()) {
1560 // For those architectures which have separate register and
1561 // memory stacks, we must check the register stack to see if
1562 // it has overflowed.
1563 return false;
1564 }
1565
1566 // Java code never executes within the yellow zone: the latter is only
1567 // there to provoke an exception during stack banging. If java code
1568 // is executing there, either StackShadowPages should be larger, or
1569 // some exception code in c1, c2 or the interpreter isn't unwinding
1570 // when it should.
1571 guarantee(cur_sp > stack_reserved_zone_base(),
1572 "not enough space to reguard - increase StackShadowPages");
1573 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1574 enable_stack_yellow_reserved_zone();
1575 if (reserved_stack_activation() != stack_base()) {
1576 set_reserved_stack_activation(stack_base());
1577 }
1578 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1579 set_reserved_stack_activation(stack_base());
1580 enable_stack_reserved_zone();
1581 }
1582 return true;
1583 }
1584
1585 bool JavaThread::reguard_stack(void) {
1586 return reguard_stack(os::current_stack_pointer());
1587 }
1588
1589
1590 void JavaThread::block_if_vm_exited() {
1591 if (_terminated == _vm_exited) {
1592 // _vm_exited is set at safepoint, and Threads_lock is never released
1593 // we will block here forever
1594 Threads_lock->lock_without_safepoint_check();
1595 ShouldNotReachHere();
1596 }
1597 }
1598
1599
1600 // Remove this ifdef when C1 is ported to the compiler interface.
1601 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1602 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1603
1604 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1605 Thread()
1606 #if INCLUDE_ALL_GCS
1607 , _satb_mark_queue(&_satb_mark_queue_set),
1608 _dirty_card_queue(&_dirty_card_queue_set)
1609 #endif // INCLUDE_ALL_GCS
1610 {
1611 initialize();
1612 _jni_attach_state = _not_attaching_via_jni;
1613 set_entry_point(entry_point);
1614 // Create the native thread itself.
1615 // %note runtime_23
1616 os::ThreadType thr_type = os::java_thread;
1617 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1618 os::java_thread;
1619 os::create_thread(this, thr_type, stack_sz);
1620 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1621 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1622 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1623 // the exception consists of creating the exception object & initializing it, initialization
1624 // will leave the VM via a JavaCall and then all locks must be unlocked).
1625 //
1626 // The thread is still suspended when we reach here. Thread must be explicit started
1627 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1628 // by calling Threads:add. The reason why this is not done here, is because the thread
1629 // object must be fully initialized (take a look at JVM_Start)
1630 }
1631
1632 JavaThread::~JavaThread() {
1633
1634 // JSR166 -- return the parker to the free list
1635 Parker::Release(_parker);
1636 _parker = NULL;
1637
1638 // Free any remaining previous UnrollBlock
1639 vframeArray* old_array = vframe_array_last();
1640
1641 if (old_array != NULL) {
1642 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1643 old_array->set_unroll_block(NULL);
1644 delete old_info;
1645 delete old_array;
1646 }
1647
1648 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1649 if (deferred != NULL) {
1650 // This can only happen if thread is destroyed before deoptimization occurs.
1651 assert(deferred->length() != 0, "empty array!");
1652 do {
1653 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1654 deferred->remove_at(0);
1655 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1656 delete dlv;
1657 } while (deferred->length() != 0);
1658 delete deferred;
1659 }
1660
1661 // All Java related clean up happens in exit
1662 ThreadSafepointState::destroy(this);
1663 if (_thread_profiler != NULL) delete _thread_profiler;
1664 if (_thread_stat != NULL) delete _thread_stat;
1665
1666 #if INCLUDE_JVMCI
1667 if (JVMCICounterSize > 0) {
1668 if (jvmci_counters_include(this)) {
1669 for (int i = 0; i < JVMCICounterSize; i++) {
1670 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1671 }
1672 }
1673 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1674 }
1675 #endif // INCLUDE_JVMCI
1676 }
1677
1678
1679 // The first routine called by a new Java thread
1680 void JavaThread::run() {
1681 // initialize thread-local alloc buffer related fields
1682 this->initialize_tlab();
1683
1684 // used to test validity of stack trace backs
1685 this->record_base_of_stack_pointer();
1686
1687 // Record real stack base and size.
1688 this->record_stack_base_and_size();
1689
1690 this->create_stack_guard_pages();
1691
1692 this->cache_global_variables();
1693
1694 // Thread is now sufficient initialized to be handled by the safepoint code as being
1695 // in the VM. Change thread state from _thread_new to _thread_in_vm
1696 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1697
1698 assert(JavaThread::current() == this, "sanity check");
1699 assert(!Thread::current()->owns_locks(), "sanity check");
1700
1701 DTRACE_THREAD_PROBE(start, this);
1702
1703 // This operation might block. We call that after all safepoint checks for a new thread has
1704 // been completed.
1705 this->set_active_handles(JNIHandleBlock::allocate_block());
1706
1707 if (JvmtiExport::should_post_thread_life()) {
1708 JvmtiExport::post_thread_start(this);
1709 }
1710
1711 EventThreadStart event;
1712 if (event.should_commit()) {
1713 event.set_thread(THREAD_TRACE_ID(this));
1714 event.commit();
1715 }
1716
1717 // We call another function to do the rest so we are sure that the stack addresses used
1718 // from there will be lower than the stack base just computed
1719 thread_main_inner();
1720
1721 // Note, thread is no longer valid at this point!
1722 }
1723
1724
1725 void JavaThread::thread_main_inner() {
1726 assert(JavaThread::current() == this, "sanity check");
1727 assert(this->threadObj() != NULL, "just checking");
1728
1729 // Execute thread entry point unless this thread has a pending exception
1730 // or has been stopped before starting.
1731 // Note: Due to JVM_StopThread we can have pending exceptions already!
1732 if (!this->has_pending_exception() &&
1733 !java_lang_Thread::is_stillborn(this->threadObj())) {
1734 {
1735 ResourceMark rm(this);
1736 this->set_native_thread_name(this->get_thread_name());
1737 }
1738 HandleMark hm(this);
1739 this->entry_point()(this, this);
1740 }
1741
1742 DTRACE_THREAD_PROBE(stop, this);
1743
1744 this->exit(false);
1745 delete this;
1746 }
1747
1748
1749 static void ensure_join(JavaThread* thread) {
1750 // We do not need to grap the Threads_lock, since we are operating on ourself.
1751 Handle threadObj(thread, thread->threadObj());
1752 assert(threadObj.not_null(), "java thread object must exist");
1753 ObjectLocker lock(threadObj, thread);
1754 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1755 thread->clear_pending_exception();
1756 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1757 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1758 // Clear the native thread instance - this makes isAlive return false and allows the join()
1759 // to complete once we've done the notify_all below
1760 java_lang_Thread::set_thread(threadObj(), NULL);
1761 lock.notify_all(thread);
1762 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1763 thread->clear_pending_exception();
1764 }
1765
1766
1767 // For any new cleanup additions, please check to see if they need to be applied to
1768 // cleanup_failed_attach_current_thread as well.
1769 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1770 assert(this == JavaThread::current(), "thread consistency check");
1771
1772 HandleMark hm(this);
1773 Handle uncaught_exception(this, this->pending_exception());
1774 this->clear_pending_exception();
1775 Handle threadObj(this, this->threadObj());
1776 assert(threadObj.not_null(), "Java thread object should be created");
1777
1778 if (get_thread_profiler() != NULL) {
1779 get_thread_profiler()->disengage();
1780 ResourceMark rm;
1781 get_thread_profiler()->print(get_thread_name());
1782 }
1783
1784
1785 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1786 {
1787 EXCEPTION_MARK;
1788
1789 CLEAR_PENDING_EXCEPTION;
1790 }
1791 if (!destroy_vm) {
1792 if (uncaught_exception.not_null()) {
1793 EXCEPTION_MARK;
1794 // Call method Thread.dispatchUncaughtException().
1795 Klass* thread_klass = SystemDictionary::Thread_klass();
1796 JavaValue result(T_VOID);
1797 JavaCalls::call_virtual(&result,
1798 threadObj, thread_klass,
1799 vmSymbols::dispatchUncaughtException_name(),
1800 vmSymbols::throwable_void_signature(),
1801 uncaught_exception,
1802 THREAD);
1803 if (HAS_PENDING_EXCEPTION) {
1804 ResourceMark rm(this);
1805 jio_fprintf(defaultStream::error_stream(),
1806 "\nException: %s thrown from the UncaughtExceptionHandler"
1807 " in thread \"%s\"\n",
1808 pending_exception()->klass()->external_name(),
1809 get_thread_name());
1810 CLEAR_PENDING_EXCEPTION;
1811 }
1812 }
1813
1814 // Called before the java thread exit since we want to read info
1815 // from java_lang_Thread object
1816 EventThreadEnd event;
1817 if (event.should_commit()) {
1818 event.set_thread(THREAD_TRACE_ID(this));
1819 event.commit();
1820 }
1821
1822 // Call after last event on thread
1823 EVENT_THREAD_EXIT(this);
1824
1825 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1826 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1827 // is deprecated anyhow.
1828 if (!is_Compiler_thread()) {
1829 int count = 3;
1830 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1831 EXCEPTION_MARK;
1832 JavaValue result(T_VOID);
1833 Klass* thread_klass = SystemDictionary::Thread_klass();
1834 JavaCalls::call_virtual(&result,
1835 threadObj, thread_klass,
1836 vmSymbols::exit_method_name(),
1837 vmSymbols::void_method_signature(),
1838 THREAD);
1839 CLEAR_PENDING_EXCEPTION;
1840 }
1841 }
1842 // notify JVMTI
1843 if (JvmtiExport::should_post_thread_life()) {
1844 JvmtiExport::post_thread_end(this);
1845 }
1846
1847 // We have notified the agents that we are exiting, before we go on,
1848 // we must check for a pending external suspend request and honor it
1849 // in order to not surprise the thread that made the suspend request.
1850 while (true) {
1851 {
1852 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1853 if (!is_external_suspend()) {
1854 set_terminated(_thread_exiting);
1855 ThreadService::current_thread_exiting(this);
1856 break;
1857 }
1858 // Implied else:
1859 // Things get a little tricky here. We have a pending external
1860 // suspend request, but we are holding the SR_lock so we
1861 // can't just self-suspend. So we temporarily drop the lock
1862 // and then self-suspend.
1863 }
1864
1865 ThreadBlockInVM tbivm(this);
1866 java_suspend_self();
1867
1868 // We're done with this suspend request, but we have to loop around
1869 // and check again. Eventually we will get SR_lock without a pending
1870 // external suspend request and will be able to mark ourselves as
1871 // exiting.
1872 }
1873 // no more external suspends are allowed at this point
1874 } else {
1875 // before_exit() has already posted JVMTI THREAD_END events
1876 }
1877
1878 // Notify waiters on thread object. This has to be done after exit() is called
1879 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1880 // group should have the destroyed bit set before waiters are notified).
1881 ensure_join(this);
1882 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1883
1884 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1885 // held by this thread must be released. The spec does not distinguish
1886 // between JNI-acquired and regular Java monitors. We can only see
1887 // regular Java monitors here if monitor enter-exit matching is broken.
1888 //
1889 // Optionally release any monitors for regular JavaThread exits. This
1890 // is provided as a work around for any bugs in monitor enter-exit
1891 // matching. This can be expensive so it is not enabled by default.
1892 //
1893 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1894 // ObjectSynchronizer::release_monitors_owned_by_thread().
1895 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1896 // Sanity check even though JNI DetachCurrentThread() would have
1897 // returned JNI_ERR if there was a Java frame. JavaThread exit
1898 // should be done executing Java code by the time we get here.
1899 assert(!this->has_last_Java_frame(),
1900 "should not have a Java frame when detaching or exiting");
1901 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1902 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1903 }
1904
1905 // These things needs to be done while we are still a Java Thread. Make sure that thread
1906 // is in a consistent state, in case GC happens
1907 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1908
1909 if (active_handles() != NULL) {
1910 JNIHandleBlock* block = active_handles();
1911 set_active_handles(NULL);
1912 JNIHandleBlock::release_block(block);
1913 }
1914
1915 if (free_handle_block() != NULL) {
1916 JNIHandleBlock* block = free_handle_block();
1917 set_free_handle_block(NULL);
1918 JNIHandleBlock::release_block(block);
1919 }
1920
1921 // These have to be removed while this is still a valid thread.
1922 remove_stack_guard_pages();
1923
1924 if (UseTLAB) {
1925 tlab().make_parsable(true); // retire TLAB
1926 }
1927
1928 if (JvmtiEnv::environments_might_exist()) {
1929 JvmtiExport::cleanup_thread(this);
1930 }
1931
1932 // We must flush any deferred card marks before removing a thread from
1933 // the list of active threads.
1934 Universe::heap()->flush_deferred_store_barrier(this);
1935 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1936
1937 #if INCLUDE_ALL_GCS
1938 // We must flush the G1-related buffers before removing a thread
1939 // from the list of active threads. We must do this after any deferred
1940 // card marks have been flushed (above) so that any entries that are
1941 // added to the thread's dirty card queue as a result are not lost.
1942 if (UseG1GC) {
1943 flush_barrier_queues();
1944 }
1945 #endif // INCLUDE_ALL_GCS
1946
1947 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1948 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1949 os::current_thread_id());
1950
1951 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1952 Threads::remove(this);
1953 }
1954
1955 #if INCLUDE_ALL_GCS
1956 // Flush G1-related queues.
1957 void JavaThread::flush_barrier_queues() {
1958 satb_mark_queue().flush();
1959 dirty_card_queue().flush();
1960 }
1961
1962 void JavaThread::initialize_queues() {
1963 assert(!SafepointSynchronize::is_at_safepoint(),
1964 "we should not be at a safepoint");
1965
1966 SATBMarkQueue& satb_queue = satb_mark_queue();
1967 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1968 // The SATB queue should have been constructed with its active
1969 // field set to false.
1970 assert(!satb_queue.is_active(), "SATB queue should not be active");
1971 assert(satb_queue.is_empty(), "SATB queue should be empty");
1972 // If we are creating the thread during a marking cycle, we should
1973 // set the active field of the SATB queue to true.
1974 if (satb_queue_set.is_active()) {
1975 satb_queue.set_active(true);
1976 }
1977
1978 DirtyCardQueue& dirty_queue = dirty_card_queue();
1979 // The dirty card queue should have been constructed with its
1980 // active field set to true.
1981 assert(dirty_queue.is_active(), "dirty card queue should be active");
1982 }
1983 #endif // INCLUDE_ALL_GCS
1984
1985 void JavaThread::cleanup_failed_attach_current_thread() {
1986 if (get_thread_profiler() != NULL) {
1987 get_thread_profiler()->disengage();
1988 ResourceMark rm;
1989 get_thread_profiler()->print(get_thread_name());
1990 }
1991
1992 if (active_handles() != NULL) {
1993 JNIHandleBlock* block = active_handles();
1994 set_active_handles(NULL);
1995 JNIHandleBlock::release_block(block);
1996 }
1997
1998 if (free_handle_block() != NULL) {
1999 JNIHandleBlock* block = free_handle_block();
2000 set_free_handle_block(NULL);
2001 JNIHandleBlock::release_block(block);
2002 }
2003
2004 // These have to be removed while this is still a valid thread.
2005 remove_stack_guard_pages();
2006
2007 if (UseTLAB) {
2008 tlab().make_parsable(true); // retire TLAB, if any
2009 }
2010
2011 #if INCLUDE_ALL_GCS
2012 if (UseG1GC) {
2013 flush_barrier_queues();
2014 }
2015 #endif // INCLUDE_ALL_GCS
2016
2017 Threads::remove(this);
2018 delete this;
2019 }
2020
2021
2022
2023
2024 JavaThread* JavaThread::active() {
2025 Thread* thread = Thread::current();
2026 if (thread->is_Java_thread()) {
2027 return (JavaThread*) thread;
2028 } else {
2029 assert(thread->is_VM_thread(), "this must be a vm thread");
2030 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2031 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2032 assert(ret->is_Java_thread(), "must be a Java thread");
2033 return ret;
2034 }
2035 }
2036
2037 bool JavaThread::is_lock_owned(address adr) const {
2038 if (Thread::is_lock_owned(adr)) return true;
2039
2040 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2041 if (chunk->contains(adr)) return true;
2042 }
2043
2044 return false;
2045 }
2046
2047
2048 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2049 chunk->set_next(monitor_chunks());
2050 set_monitor_chunks(chunk);
2051 }
2052
2053 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2054 guarantee(monitor_chunks() != NULL, "must be non empty");
2055 if (monitor_chunks() == chunk) {
2056 set_monitor_chunks(chunk->next());
2057 } else {
2058 MonitorChunk* prev = monitor_chunks();
2059 while (prev->next() != chunk) prev = prev->next();
2060 prev->set_next(chunk->next());
2061 }
2062 }
2063
2064 // JVM support.
2065
2066 // Note: this function shouldn't block if it's called in
2067 // _thread_in_native_trans state (such as from
2068 // check_special_condition_for_native_trans()).
2069 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2070
2071 if (has_last_Java_frame() && has_async_condition()) {
2072 // If we are at a polling page safepoint (not a poll return)
2073 // then we must defer async exception because live registers
2074 // will be clobbered by the exception path. Poll return is
2075 // ok because the call we a returning from already collides
2076 // with exception handling registers and so there is no issue.
2077 // (The exception handling path kills call result registers but
2078 // this is ok since the exception kills the result anyway).
2079
2080 if (is_at_poll_safepoint()) {
2081 // if the code we are returning to has deoptimized we must defer
2082 // the exception otherwise live registers get clobbered on the
2083 // exception path before deoptimization is able to retrieve them.
2084 //
2085 RegisterMap map(this, false);
2086 frame caller_fr = last_frame().sender(&map);
2087 assert(caller_fr.is_compiled_frame(), "what?");
2088 if (caller_fr.is_deoptimized_frame()) {
2089 log_info(exceptions)("deferred async exception at compiled safepoint");
2090 return;
2091 }
2092 }
2093 }
2094
2095 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2096 if (condition == _no_async_condition) {
2097 // Conditions have changed since has_special_runtime_exit_condition()
2098 // was called:
2099 // - if we were here only because of an external suspend request,
2100 // then that was taken care of above (or cancelled) so we are done
2101 // - if we were here because of another async request, then it has
2102 // been cleared between the has_special_runtime_exit_condition()
2103 // and now so again we are done
2104 return;
2105 }
2106
2107 // Check for pending async. exception
2108 if (_pending_async_exception != NULL) {
2109 // Only overwrite an already pending exception, if it is not a threadDeath.
2110 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2111
2112 // We cannot call Exceptions::_throw(...) here because we cannot block
2113 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2114
2115 LogTarget(Info, exceptions) lt;
2116 if (lt.is_enabled()) {
2117 ResourceMark rm;
2118 LogStream ls(lt);
2119 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2120 if (has_last_Java_frame()) {
2121 frame f = last_frame();
2122 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2123 }
2124 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2125 }
2126 _pending_async_exception = NULL;
2127 clear_has_async_exception();
2128 }
2129 }
2130
2131 if (check_unsafe_error &&
2132 condition == _async_unsafe_access_error && !has_pending_exception()) {
2133 condition = _no_async_condition; // done
2134 switch (thread_state()) {
2135 case _thread_in_vm: {
2136 JavaThread* THREAD = this;
2137 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2138 }
2139 case _thread_in_native: {
2140 ThreadInVMfromNative tiv(this);
2141 JavaThread* THREAD = this;
2142 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2143 }
2144 case _thread_in_Java: {
2145 ThreadInVMfromJava tiv(this);
2146 JavaThread* THREAD = this;
2147 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2148 }
2149 default:
2150 ShouldNotReachHere();
2151 }
2152 }
2153
2154 assert(condition == _no_async_condition || has_pending_exception() ||
2155 (!check_unsafe_error && condition == _async_unsafe_access_error),
2156 "must have handled the async condition, if no exception");
2157 }
2158
2159 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2160 //
2161 // Check for pending external suspend. Internal suspend requests do
2162 // not use handle_special_runtime_exit_condition().
2163 // If JNIEnv proxies are allowed, don't self-suspend if the target
2164 // thread is not the current thread. In older versions of jdbx, jdbx
2165 // threads could call into the VM with another thread's JNIEnv so we
2166 // can be here operating on behalf of a suspended thread (4432884).
2167 bool do_self_suspend = is_external_suspend_with_lock();
2168 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2169 //
2170 // Because thread is external suspended the safepoint code will count
2171 // thread as at a safepoint. This can be odd because we can be here
2172 // as _thread_in_Java which would normally transition to _thread_blocked
2173 // at a safepoint. We would like to mark the thread as _thread_blocked
2174 // before calling java_suspend_self like all other callers of it but
2175 // we must then observe proper safepoint protocol. (We can't leave
2176 // _thread_blocked with a safepoint in progress). However we can be
2177 // here as _thread_in_native_trans so we can't use a normal transition
2178 // constructor/destructor pair because they assert on that type of
2179 // transition. We could do something like:
2180 //
2181 // JavaThreadState state = thread_state();
2182 // set_thread_state(_thread_in_vm);
2183 // {
2184 // ThreadBlockInVM tbivm(this);
2185 // java_suspend_self()
2186 // }
2187 // set_thread_state(_thread_in_vm_trans);
2188 // if (safepoint) block;
2189 // set_thread_state(state);
2190 //
2191 // but that is pretty messy. Instead we just go with the way the
2192 // code has worked before and note that this is the only path to
2193 // java_suspend_self that doesn't put the thread in _thread_blocked
2194 // mode.
2195
2196 frame_anchor()->make_walkable(this);
2197 java_suspend_self();
2198
2199 // We might be here for reasons in addition to the self-suspend request
2200 // so check for other async requests.
2201 }
2202
2203 if (check_asyncs) {
2204 check_and_handle_async_exceptions();
2205 }
2206 #if INCLUDE_TRACE
2207 if (is_trace_suspend()) {
2208 TRACE_SUSPEND_THREAD(this);
2209 }
2210 #endif
2211 }
2212
2213 void JavaThread::send_thread_stop(oop java_throwable) {
2214 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2215 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2216 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2217
2218 // Do not throw asynchronous exceptions against the compiler thread
2219 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2220 if (!can_call_java()) return;
2221
2222 {
2223 // Actually throw the Throwable against the target Thread - however
2224 // only if there is no thread death exception installed already.
2225 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2226 // If the topmost frame is a runtime stub, then we are calling into
2227 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2228 // must deoptimize the caller before continuing, as the compiled exception handler table
2229 // may not be valid
2230 if (has_last_Java_frame()) {
2231 frame f = last_frame();
2232 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2233 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2234 RegisterMap reg_map(this, UseBiasedLocking);
2235 frame compiled_frame = f.sender(®_map);
2236 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2237 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2238 }
2239 }
2240 }
2241
2242 // Set async. pending exception in thread.
2243 set_pending_async_exception(java_throwable);
2244
2245 if (log_is_enabled(Info, exceptions)) {
2246 ResourceMark rm;
2247 log_info(exceptions)("Pending Async. exception installed of type: %s",
2248 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2249 }
2250 // for AbortVMOnException flag
2251 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2252 }
2253 }
2254
2255
2256 // Interrupt thread so it will wake up from a potential wait()
2257 Thread::interrupt(this);
2258 }
2259
2260 // External suspension mechanism.
2261 //
2262 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2263 // to any VM_locks and it is at a transition
2264 // Self-suspension will happen on the transition out of the vm.
2265 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2266 //
2267 // Guarantees on return:
2268 // + Target thread will not execute any new bytecode (that's why we need to
2269 // force a safepoint)
2270 // + Target thread will not enter any new monitors
2271 //
2272 void JavaThread::java_suspend() {
2273 { MutexLocker mu(Threads_lock);
2274 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2275 return;
2276 }
2277 }
2278
2279 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2280 if (!is_external_suspend()) {
2281 // a racing resume has cancelled us; bail out now
2282 return;
2283 }
2284
2285 // suspend is done
2286 uint32_t debug_bits = 0;
2287 // Warning: is_ext_suspend_completed() may temporarily drop the
2288 // SR_lock to allow the thread to reach a stable thread state if
2289 // it is currently in a transient thread state.
2290 if (is_ext_suspend_completed(false /* !called_by_wait */,
2291 SuspendRetryDelay, &debug_bits)) {
2292 return;
2293 }
2294 }
2295
2296 VM_ThreadSuspend vm_suspend;
2297 VMThread::execute(&vm_suspend);
2298 }
2299
2300 // Part II of external suspension.
2301 // A JavaThread self suspends when it detects a pending external suspend
2302 // request. This is usually on transitions. It is also done in places
2303 // where continuing to the next transition would surprise the caller,
2304 // e.g., monitor entry.
2305 //
2306 // Returns the number of times that the thread self-suspended.
2307 //
2308 // Note: DO NOT call java_suspend_self() when you just want to block current
2309 // thread. java_suspend_self() is the second stage of cooperative
2310 // suspension for external suspend requests and should only be used
2311 // to complete an external suspend request.
2312 //
2313 int JavaThread::java_suspend_self() {
2314 int ret = 0;
2315
2316 // we are in the process of exiting so don't suspend
2317 if (is_exiting()) {
2318 clear_external_suspend();
2319 return ret;
2320 }
2321
2322 assert(_anchor.walkable() ||
2323 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2324 "must have walkable stack");
2325
2326 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2327
2328 assert(!this->is_ext_suspended(),
2329 "a thread trying to self-suspend should not already be suspended");
2330
2331 if (this->is_suspend_equivalent()) {
2332 // If we are self-suspending as a result of the lifting of a
2333 // suspend equivalent condition, then the suspend_equivalent
2334 // flag is not cleared until we set the ext_suspended flag so
2335 // that wait_for_ext_suspend_completion() returns consistent
2336 // results.
2337 this->clear_suspend_equivalent();
2338 }
2339
2340 // A racing resume may have cancelled us before we grabbed SR_lock
2341 // above. Or another external suspend request could be waiting for us
2342 // by the time we return from SR_lock()->wait(). The thread
2343 // that requested the suspension may already be trying to walk our
2344 // stack and if we return now, we can change the stack out from under
2345 // it. This would be a "bad thing (TM)" and cause the stack walker
2346 // to crash. We stay self-suspended until there are no more pending
2347 // external suspend requests.
2348 while (is_external_suspend()) {
2349 ret++;
2350 this->set_ext_suspended();
2351
2352 // _ext_suspended flag is cleared by java_resume()
2353 while (is_ext_suspended()) {
2354 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2355 }
2356 }
2357
2358 return ret;
2359 }
2360
2361 #ifdef ASSERT
2362 // verify the JavaThread has not yet been published in the Threads::list, and
2363 // hence doesn't need protection from concurrent access at this stage
2364 void JavaThread::verify_not_published() {
2365 if (!Threads_lock->owned_by_self()) {
2366 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2367 assert(!Threads::includes(this),
2368 "java thread shouldn't have been published yet!");
2369 } else {
2370 assert(!Threads::includes(this),
2371 "java thread shouldn't have been published yet!");
2372 }
2373 }
2374 #endif
2375
2376 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2377 // progress or when _suspend_flags is non-zero.
2378 // Current thread needs to self-suspend if there is a suspend request and/or
2379 // block if a safepoint is in progress.
2380 // Async exception ISN'T checked.
2381 // Note only the ThreadInVMfromNative transition can call this function
2382 // directly and when thread state is _thread_in_native_trans
2383 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2384 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2385
2386 JavaThread *curJT = JavaThread::current();
2387 bool do_self_suspend = thread->is_external_suspend();
2388
2389 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2390
2391 // If JNIEnv proxies are allowed, don't self-suspend if the target
2392 // thread is not the current thread. In older versions of jdbx, jdbx
2393 // threads could call into the VM with another thread's JNIEnv so we
2394 // can be here operating on behalf of a suspended thread (4432884).
2395 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2396 JavaThreadState state = thread->thread_state();
2397
2398 // We mark this thread_blocked state as a suspend-equivalent so
2399 // that a caller to is_ext_suspend_completed() won't be confused.
2400 // The suspend-equivalent state is cleared by java_suspend_self().
2401 thread->set_suspend_equivalent();
2402
2403 // If the safepoint code sees the _thread_in_native_trans state, it will
2404 // wait until the thread changes to other thread state. There is no
2405 // guarantee on how soon we can obtain the SR_lock and complete the
2406 // self-suspend request. It would be a bad idea to let safepoint wait for
2407 // too long. Temporarily change the state to _thread_blocked to
2408 // let the VM thread know that this thread is ready for GC. The problem
2409 // of changing thread state is that safepoint could happen just after
2410 // java_suspend_self() returns after being resumed, and VM thread will
2411 // see the _thread_blocked state. We must check for safepoint
2412 // after restoring the state and make sure we won't leave while a safepoint
2413 // is in progress.
2414 thread->set_thread_state(_thread_blocked);
2415 thread->java_suspend_self();
2416 thread->set_thread_state(state);
2417
2418 InterfaceSupport::serialize_thread_state_with_handler(thread);
2419 }
2420
2421 if (SafepointSynchronize::do_call_back()) {
2422 // If we are safepointing, then block the caller which may not be
2423 // the same as the target thread (see above).
2424 SafepointSynchronize::block(curJT);
2425 }
2426
2427 if (thread->is_deopt_suspend()) {
2428 thread->clear_deopt_suspend();
2429 RegisterMap map(thread, false);
2430 frame f = thread->last_frame();
2431 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2432 f = f.sender(&map);
2433 }
2434 if (f.id() == thread->must_deopt_id()) {
2435 thread->clear_must_deopt_id();
2436 f.deoptimize(thread);
2437 } else {
2438 fatal("missed deoptimization!");
2439 }
2440 }
2441 #if INCLUDE_TRACE
2442 if (thread->is_trace_suspend()) {
2443 TRACE_SUSPEND_THREAD(thread);
2444 }
2445 #endif
2446 }
2447
2448 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2449 // progress or when _suspend_flags is non-zero.
2450 // Current thread needs to self-suspend if there is a suspend request and/or
2451 // block if a safepoint is in progress.
2452 // Also check for pending async exception (not including unsafe access error).
2453 // Note only the native==>VM/Java barriers can call this function and when
2454 // thread state is _thread_in_native_trans.
2455 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2456 check_safepoint_and_suspend_for_native_trans(thread);
2457
2458 if (thread->has_async_exception()) {
2459 // We are in _thread_in_native_trans state, don't handle unsafe
2460 // access error since that may block.
2461 thread->check_and_handle_async_exceptions(false);
2462 }
2463 }
2464
2465 // This is a variant of the normal
2466 // check_special_condition_for_native_trans with slightly different
2467 // semantics for use by critical native wrappers. It does all the
2468 // normal checks but also performs the transition back into
2469 // thread_in_Java state. This is required so that critical natives
2470 // can potentially block and perform a GC if they are the last thread
2471 // exiting the GCLocker.
2472 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2473 check_special_condition_for_native_trans(thread);
2474
2475 // Finish the transition
2476 thread->set_thread_state(_thread_in_Java);
2477
2478 if (thread->do_critical_native_unlock()) {
2479 ThreadInVMfromJavaNoAsyncException tiv(thread);
2480 GCLocker::unlock_critical(thread);
2481 thread->clear_critical_native_unlock();
2482 }
2483 }
2484
2485 // We need to guarantee the Threads_lock here, since resumes are not
2486 // allowed during safepoint synchronization
2487 // Can only resume from an external suspension
2488 void JavaThread::java_resume() {
2489 assert_locked_or_safepoint(Threads_lock);
2490
2491 // Sanity check: thread is gone, has started exiting or the thread
2492 // was not externally suspended.
2493 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2494 return;
2495 }
2496
2497 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2498
2499 clear_external_suspend();
2500
2501 if (is_ext_suspended()) {
2502 clear_ext_suspended();
2503 SR_lock()->notify_all();
2504 }
2505 }
2506
2507 size_t JavaThread::_stack_red_zone_size = 0;
2508 size_t JavaThread::_stack_yellow_zone_size = 0;
2509 size_t JavaThread::_stack_reserved_zone_size = 0;
2510 size_t JavaThread::_stack_shadow_zone_size = 0;
2511
2512 void JavaThread::create_stack_guard_pages() {
2513 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2514 address low_addr = stack_end();
2515 size_t len = stack_guard_zone_size();
2516
2517 int must_commit = os::must_commit_stack_guard_pages();
2518 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2519
2520 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2521 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2522 return;
2523 }
2524
2525 if (os::guard_memory((char *) low_addr, len)) {
2526 _stack_guard_state = stack_guard_enabled;
2527 } else {
2528 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2529 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2530 if (os::uncommit_memory((char *) low_addr, len)) {
2531 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2532 }
2533 return;
2534 }
2535
2536 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2537 PTR_FORMAT "-" PTR_FORMAT ".",
2538 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2539 }
2540
2541 void JavaThread::remove_stack_guard_pages() {
2542 assert(Thread::current() == this, "from different thread");
2543 if (_stack_guard_state == stack_guard_unused) return;
2544 address low_addr = stack_end();
2545 size_t len = stack_guard_zone_size();
2546
2547 if (os::must_commit_stack_guard_pages()) {
2548 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2549 _stack_guard_state = stack_guard_unused;
2550 } else {
2551 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2552 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2553 return;
2554 }
2555 } else {
2556 if (_stack_guard_state == stack_guard_unused) return;
2557 if (os::unguard_memory((char *) low_addr, len)) {
2558 _stack_guard_state = stack_guard_unused;
2559 } else {
2560 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2561 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2562 return;
2563 }
2564 }
2565
2566 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2567 PTR_FORMAT "-" PTR_FORMAT ".",
2568 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2569 }
2570
2571 void JavaThread::enable_stack_reserved_zone() {
2572 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2573 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2574
2575 // The base notation is from the stack's point of view, growing downward.
2576 // We need to adjust it to work correctly with guard_memory()
2577 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2578
2579 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2580 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2581
2582 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2583 _stack_guard_state = stack_guard_enabled;
2584 } else {
2585 warning("Attempt to guard stack reserved zone failed.");
2586 }
2587 enable_register_stack_guard();
2588 }
2589
2590 void JavaThread::disable_stack_reserved_zone() {
2591 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2592 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2593
2594 // Simply return if called for a thread that does not use guard pages.
2595 if (_stack_guard_state == stack_guard_unused) return;
2596
2597 // The base notation is from the stack's point of view, growing downward.
2598 // We need to adjust it to work correctly with guard_memory()
2599 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2600
2601 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2602 _stack_guard_state = stack_guard_reserved_disabled;
2603 } else {
2604 warning("Attempt to unguard stack reserved zone failed.");
2605 }
2606 disable_register_stack_guard();
2607 }
2608
2609 void JavaThread::enable_stack_yellow_reserved_zone() {
2610 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2611 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2612
2613 // The base notation is from the stacks point of view, growing downward.
2614 // We need to adjust it to work correctly with guard_memory()
2615 address base = stack_red_zone_base();
2616
2617 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2618 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2619
2620 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2621 _stack_guard_state = stack_guard_enabled;
2622 } else {
2623 warning("Attempt to guard stack yellow zone failed.");
2624 }
2625 enable_register_stack_guard();
2626 }
2627
2628 void JavaThread::disable_stack_yellow_reserved_zone() {
2629 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2630 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2631
2632 // Simply return if called for a thread that does not use guard pages.
2633 if (_stack_guard_state == stack_guard_unused) return;
2634
2635 // The base notation is from the stacks point of view, growing downward.
2636 // We need to adjust it to work correctly with guard_memory()
2637 address base = stack_red_zone_base();
2638
2639 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2640 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2641 } else {
2642 warning("Attempt to unguard stack yellow zone failed.");
2643 }
2644 disable_register_stack_guard();
2645 }
2646
2647 void JavaThread::enable_stack_red_zone() {
2648 // The base notation is from the stacks point of view, growing downward.
2649 // We need to adjust it to work correctly with guard_memory()
2650 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2651 address base = stack_red_zone_base() - stack_red_zone_size();
2652
2653 guarantee(base < stack_base(), "Error calculating stack red zone");
2654 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2655
2656 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2657 warning("Attempt to guard stack red zone failed.");
2658 }
2659 }
2660
2661 void JavaThread::disable_stack_red_zone() {
2662 // The base notation is from the stacks point of view, growing downward.
2663 // We need to adjust it to work correctly with guard_memory()
2664 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2665 address base = stack_red_zone_base() - stack_red_zone_size();
2666 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2667 warning("Attempt to unguard stack red zone failed.");
2668 }
2669 }
2670
2671 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2672 // ignore is there is no stack
2673 if (!has_last_Java_frame()) return;
2674 // traverse the stack frames. Starts from top frame.
2675 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2676 frame* fr = fst.current();
2677 f(fr, fst.register_map());
2678 }
2679 }
2680
2681
2682 #ifndef PRODUCT
2683 // Deoptimization
2684 // Function for testing deoptimization
2685 void JavaThread::deoptimize() {
2686 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2687 StackFrameStream fst(this, UseBiasedLocking);
2688 bool deopt = false; // Dump stack only if a deopt actually happens.
2689 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2690 // Iterate over all frames in the thread and deoptimize
2691 for (; !fst.is_done(); fst.next()) {
2692 if (fst.current()->can_be_deoptimized()) {
2693
2694 if (only_at) {
2695 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2696 // consists of comma or carriage return separated numbers so
2697 // search for the current bci in that string.
2698 address pc = fst.current()->pc();
2699 nmethod* nm = (nmethod*) fst.current()->cb();
2700 ScopeDesc* sd = nm->scope_desc_at(pc);
2701 char buffer[8];
2702 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2703 size_t len = strlen(buffer);
2704 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2705 while (found != NULL) {
2706 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2707 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2708 // Check that the bci found is bracketed by terminators.
2709 break;
2710 }
2711 found = strstr(found + 1, buffer);
2712 }
2713 if (!found) {
2714 continue;
2715 }
2716 }
2717
2718 if (DebugDeoptimization && !deopt) {
2719 deopt = true; // One-time only print before deopt
2720 tty->print_cr("[BEFORE Deoptimization]");
2721 trace_frames();
2722 trace_stack();
2723 }
2724 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2725 }
2726 }
2727
2728 if (DebugDeoptimization && deopt) {
2729 tty->print_cr("[AFTER Deoptimization]");
2730 trace_frames();
2731 }
2732 }
2733
2734
2735 // Make zombies
2736 void JavaThread::make_zombies() {
2737 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2738 if (fst.current()->can_be_deoptimized()) {
2739 // it is a Java nmethod
2740 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2741 nm->make_not_entrant();
2742 }
2743 }
2744 }
2745 #endif // PRODUCT
2746
2747
2748 void JavaThread::deoptimized_wrt_marked_nmethods() {
2749 if (!has_last_Java_frame()) return;
2750 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2751 StackFrameStream fst(this, UseBiasedLocking);
2752 for (; !fst.is_done(); fst.next()) {
2753 if (fst.current()->should_be_deoptimized()) {
2754 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2755 }
2756 }
2757 }
2758
2759
2760 // If the caller is a NamedThread, then remember, in the current scope,
2761 // the given JavaThread in its _processed_thread field.
2762 class RememberProcessedThread: public StackObj {
2763 NamedThread* _cur_thr;
2764 public:
2765 RememberProcessedThread(JavaThread* jthr) {
2766 Thread* thread = Thread::current();
2767 if (thread->is_Named_thread()) {
2768 _cur_thr = (NamedThread *)thread;
2769 _cur_thr->set_processed_thread(jthr);
2770 } else {
2771 _cur_thr = NULL;
2772 }
2773 }
2774
2775 ~RememberProcessedThread() {
2776 if (_cur_thr) {
2777 _cur_thr->set_processed_thread(NULL);
2778 }
2779 }
2780 };
2781
2782 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2783 // Verify that the deferred card marks have been flushed.
2784 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2785
2786 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2787 // since there may be more than one thread using each ThreadProfiler.
2788
2789 // Traverse the GCHandles
2790 Thread::oops_do(f, cf);
2791
2792 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2793
2794 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2795 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2796
2797 if (has_last_Java_frame()) {
2798 // Record JavaThread to GC thread
2799 RememberProcessedThread rpt(this);
2800
2801 // Traverse the privileged stack
2802 if (_privileged_stack_top != NULL) {
2803 _privileged_stack_top->oops_do(f);
2804 }
2805
2806 // traverse the registered growable array
2807 if (_array_for_gc != NULL) {
2808 for (int index = 0; index < _array_for_gc->length(); index++) {
2809 f->do_oop(_array_for_gc->adr_at(index));
2810 }
2811 }
2812
2813 // Traverse the monitor chunks
2814 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2815 chunk->oops_do(f);
2816 }
2817
2818 // Traverse the execution stack
2819 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2820 fst.current()->oops_do(f, cf, fst.register_map());
2821 }
2822 }
2823
2824 // callee_target is never live across a gc point so NULL it here should
2825 // it still contain a methdOop.
2826
2827 set_callee_target(NULL);
2828
2829 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2830 // If we have deferred set_locals there might be oops waiting to be
2831 // written
2832 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2833 if (list != NULL) {
2834 for (int i = 0; i < list->length(); i++) {
2835 list->at(i)->oops_do(f);
2836 }
2837 }
2838
2839 // Traverse instance variables at the end since the GC may be moving things
2840 // around using this function
2841 f->do_oop((oop*) &_threadObj);
2842 f->do_oop((oop*) &_vm_result);
2843 f->do_oop((oop*) &_exception_oop);
2844 f->do_oop((oop*) &_pending_async_exception);
2845
2846 if (jvmti_thread_state() != NULL) {
2847 jvmti_thread_state()->oops_do(f);
2848 }
2849 }
2850
2851 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2852 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2853 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2854
2855 if (has_last_Java_frame()) {
2856 // Traverse the execution stack
2857 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2858 fst.current()->nmethods_do(cf);
2859 }
2860 }
2861 }
2862
2863 void JavaThread::metadata_do(void f(Metadata*)) {
2864 if (has_last_Java_frame()) {
2865 // Traverse the execution stack to call f() on the methods in the stack
2866 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2867 fst.current()->metadata_do(f);
2868 }
2869 } else if (is_Compiler_thread()) {
2870 // need to walk ciMetadata in current compile tasks to keep alive.
2871 CompilerThread* ct = (CompilerThread*)this;
2872 if (ct->env() != NULL) {
2873 ct->env()->metadata_do(f);
2874 }
2875 if (ct->task() != NULL) {
2876 ct->task()->metadata_do(f);
2877 }
2878 }
2879 }
2880
2881 // Printing
2882 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2883 switch (_thread_state) {
2884 case _thread_uninitialized: return "_thread_uninitialized";
2885 case _thread_new: return "_thread_new";
2886 case _thread_new_trans: return "_thread_new_trans";
2887 case _thread_in_native: return "_thread_in_native";
2888 case _thread_in_native_trans: return "_thread_in_native_trans";
2889 case _thread_in_vm: return "_thread_in_vm";
2890 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2891 case _thread_in_Java: return "_thread_in_Java";
2892 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2893 case _thread_blocked: return "_thread_blocked";
2894 case _thread_blocked_trans: return "_thread_blocked_trans";
2895 default: return "unknown thread state";
2896 }
2897 }
2898
2899 #ifndef PRODUCT
2900 void JavaThread::print_thread_state_on(outputStream *st) const {
2901 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2902 };
2903 void JavaThread::print_thread_state() const {
2904 print_thread_state_on(tty);
2905 }
2906 #endif // PRODUCT
2907
2908 // Called by Threads::print() for VM_PrintThreads operation
2909 void JavaThread::print_on(outputStream *st) const {
2910 st->print_raw("\"");
2911 st->print_raw(get_thread_name());
2912 st->print_raw("\" ");
2913 oop thread_oop = threadObj();
2914 if (thread_oop != NULL) {
2915 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2916 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2917 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2918 }
2919 Thread::print_on(st);
2920 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2921 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2922 if (thread_oop != NULL) {
2923 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2924 }
2925 #ifndef PRODUCT
2926 print_thread_state_on(st);
2927 _safepoint_state->print_on(st);
2928 #endif // PRODUCT
2929 if (is_Compiler_thread()) {
2930 CompilerThread* ct = (CompilerThread*)this;
2931 if (ct->task() != NULL) {
2932 st->print(" Compiling: ");
2933 ct->task()->print(st, NULL, true, false);
2934 } else {
2935 st->print(" No compile task");
2936 }
2937 st->cr();
2938 }
2939 }
2940
2941 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2942 st->print("%s", get_thread_name_string(buf, buflen));
2943 }
2944
2945 // Called by fatal error handler. The difference between this and
2946 // JavaThread::print() is that we can't grab lock or allocate memory.
2947 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2948 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2949 oop thread_obj = threadObj();
2950 if (thread_obj != NULL) {
2951 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2952 }
2953 st->print(" [");
2954 st->print("%s", _get_thread_state_name(_thread_state));
2955 if (osthread()) {
2956 st->print(", id=%d", osthread()->thread_id());
2957 }
2958 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2959 p2i(stack_end()), p2i(stack_base()));
2960 st->print("]");
2961 return;
2962 }
2963
2964 // Verification
2965
2966 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2967
2968 void JavaThread::verify() {
2969 // Verify oops in the thread.
2970 oops_do(&VerifyOopClosure::verify_oop, NULL);
2971
2972 // Verify the stack frames.
2973 frames_do(frame_verify);
2974 }
2975
2976 // CR 6300358 (sub-CR 2137150)
2977 // Most callers of this method assume that it can't return NULL but a
2978 // thread may not have a name whilst it is in the process of attaching to
2979 // the VM - see CR 6412693, and there are places where a JavaThread can be
2980 // seen prior to having it's threadObj set (eg JNI attaching threads and
2981 // if vm exit occurs during initialization). These cases can all be accounted
2982 // for such that this method never returns NULL.
2983 const char* JavaThread::get_thread_name() const {
2984 #ifdef ASSERT
2985 // early safepoints can hit while current thread does not yet have TLS
2986 if (!SafepointSynchronize::is_at_safepoint()) {
2987 Thread *cur = Thread::current();
2988 if (!(cur->is_Java_thread() && cur == this)) {
2989 // Current JavaThreads are allowed to get their own name without
2990 // the Threads_lock.
2991 assert_locked_or_safepoint(Threads_lock);
2992 }
2993 }
2994 #endif // ASSERT
2995 return get_thread_name_string();
2996 }
2997
2998 // Returns a non-NULL representation of this thread's name, or a suitable
2999 // descriptive string if there is no set name
3000 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3001 const char* name_str;
3002 oop thread_obj = threadObj();
3003 if (thread_obj != NULL) {
3004 oop name = java_lang_Thread::name(thread_obj);
3005 if (name != NULL) {
3006 if (buf == NULL) {
3007 name_str = java_lang_String::as_utf8_string(name);
3008 } else {
3009 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3010 }
3011 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3012 name_str = "<no-name - thread is attaching>";
3013 } else {
3014 name_str = Thread::name();
3015 }
3016 } else {
3017 name_str = Thread::name();
3018 }
3019 assert(name_str != NULL, "unexpected NULL thread name");
3020 return name_str;
3021 }
3022
3023
3024 const char* JavaThread::get_threadgroup_name() const {
3025 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3026 oop thread_obj = threadObj();
3027 if (thread_obj != NULL) {
3028 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3029 if (thread_group != NULL) {
3030 // ThreadGroup.name can be null
3031 return java_lang_ThreadGroup::name(thread_group);
3032 }
3033 }
3034 return NULL;
3035 }
3036
3037 const char* JavaThread::get_parent_name() const {
3038 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3039 oop thread_obj = threadObj();
3040 if (thread_obj != NULL) {
3041 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3042 if (thread_group != NULL) {
3043 oop parent = java_lang_ThreadGroup::parent(thread_group);
3044 if (parent != NULL) {
3045 // ThreadGroup.name can be null
3046 return java_lang_ThreadGroup::name(parent);
3047 }
3048 }
3049 }
3050 return NULL;
3051 }
3052
3053 ThreadPriority JavaThread::java_priority() const {
3054 oop thr_oop = threadObj();
3055 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3056 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3057 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3058 return priority;
3059 }
3060
3061 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3062
3063 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3064 // Link Java Thread object <-> C++ Thread
3065
3066 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3067 // and put it into a new Handle. The Handle "thread_oop" can then
3068 // be used to pass the C++ thread object to other methods.
3069
3070 // Set the Java level thread object (jthread) field of the
3071 // new thread (a JavaThread *) to C++ thread object using the
3072 // "thread_oop" handle.
3073
3074 // Set the thread field (a JavaThread *) of the
3075 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3076
3077 Handle thread_oop(Thread::current(),
3078 JNIHandles::resolve_non_null(jni_thread));
3079 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3080 "must be initialized");
3081 set_threadObj(thread_oop());
3082 java_lang_Thread::set_thread(thread_oop(), this);
3083
3084 if (prio == NoPriority) {
3085 prio = java_lang_Thread::priority(thread_oop());
3086 assert(prio != NoPriority, "A valid priority should be present");
3087 }
3088
3089 // Push the Java priority down to the native thread; needs Threads_lock
3090 Thread::set_priority(this, prio);
3091
3092 prepare_ext();
3093
3094 // Add the new thread to the Threads list and set it in motion.
3095 // We must have threads lock in order to call Threads::add.
3096 // It is crucial that we do not block before the thread is
3097 // added to the Threads list for if a GC happens, then the java_thread oop
3098 // will not be visited by GC.
3099 Threads::add(this);
3100 }
3101
3102 oop JavaThread::current_park_blocker() {
3103 // Support for JSR-166 locks
3104 oop thread_oop = threadObj();
3105 if (thread_oop != NULL &&
3106 JDK_Version::current().supports_thread_park_blocker()) {
3107 return java_lang_Thread::park_blocker(thread_oop);
3108 }
3109 return NULL;
3110 }
3111
3112
3113 void JavaThread::print_stack_on(outputStream* st) {
3114 if (!has_last_Java_frame()) return;
3115 ResourceMark rm;
3116 HandleMark hm;
3117
3118 RegisterMap reg_map(this);
3119 vframe* start_vf = last_java_vframe(®_map);
3120 int count = 0;
3121 for (vframe* f = start_vf; f; f = f->sender()) {
3122 if (f->is_java_frame()) {
3123 javaVFrame* jvf = javaVFrame::cast(f);
3124 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3125
3126 // Print out lock information
3127 if (JavaMonitorsInStackTrace) {
3128 jvf->print_lock_info_on(st, count);
3129 }
3130 } else {
3131 // Ignore non-Java frames
3132 }
3133
3134 // Bail-out case for too deep stacks
3135 count++;
3136 if (MaxJavaStackTraceDepth == count) return;
3137 }
3138 }
3139
3140
3141 // JVMTI PopFrame support
3142 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3143 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3144 if (in_bytes(size_in_bytes) != 0) {
3145 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3146 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3147 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3148 }
3149 }
3150
3151 void* JavaThread::popframe_preserved_args() {
3152 return _popframe_preserved_args;
3153 }
3154
3155 ByteSize JavaThread::popframe_preserved_args_size() {
3156 return in_ByteSize(_popframe_preserved_args_size);
3157 }
3158
3159 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3160 int sz = in_bytes(popframe_preserved_args_size());
3161 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3162 return in_WordSize(sz / wordSize);
3163 }
3164
3165 void JavaThread::popframe_free_preserved_args() {
3166 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3167 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3168 _popframe_preserved_args = NULL;
3169 _popframe_preserved_args_size = 0;
3170 }
3171
3172 #ifndef PRODUCT
3173
3174 void JavaThread::trace_frames() {
3175 tty->print_cr("[Describe stack]");
3176 int frame_no = 1;
3177 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3178 tty->print(" %d. ", frame_no++);
3179 fst.current()->print_value_on(tty, this);
3180 tty->cr();
3181 }
3182 }
3183
3184 class PrintAndVerifyOopClosure: public OopClosure {
3185 protected:
3186 template <class T> inline void do_oop_work(T* p) {
3187 oop obj = oopDesc::load_decode_heap_oop(p);
3188 if (obj == NULL) return;
3189 tty->print(INTPTR_FORMAT ": ", p2i(p));
3190 if (obj->is_oop_or_null()) {
3191 if (obj->is_objArray()) {
3192 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3193 } else {
3194 obj->print();
3195 }
3196 } else {
3197 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3198 }
3199 tty->cr();
3200 }
3201 public:
3202 virtual void do_oop(oop* p) { do_oop_work(p); }
3203 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3204 };
3205
3206
3207 static void oops_print(frame* f, const RegisterMap *map) {
3208 PrintAndVerifyOopClosure print;
3209 f->print_value();
3210 f->oops_do(&print, NULL, (RegisterMap*)map);
3211 }
3212
3213 // Print our all the locations that contain oops and whether they are
3214 // valid or not. This useful when trying to find the oldest frame
3215 // where an oop has gone bad since the frame walk is from youngest to
3216 // oldest.
3217 void JavaThread::trace_oops() {
3218 tty->print_cr("[Trace oops]");
3219 frames_do(oops_print);
3220 }
3221
3222
3223 #ifdef ASSERT
3224 // Print or validate the layout of stack frames
3225 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3226 ResourceMark rm;
3227 PRESERVE_EXCEPTION_MARK;
3228 FrameValues values;
3229 int frame_no = 0;
3230 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3231 fst.current()->describe(values, ++frame_no);
3232 if (depth == frame_no) break;
3233 }
3234 if (validate_only) {
3235 values.validate();
3236 } else {
3237 tty->print_cr("[Describe stack layout]");
3238 values.print(this);
3239 }
3240 }
3241 #endif
3242
3243 void JavaThread::trace_stack_from(vframe* start_vf) {
3244 ResourceMark rm;
3245 int vframe_no = 1;
3246 for (vframe* f = start_vf; f; f = f->sender()) {
3247 if (f->is_java_frame()) {
3248 javaVFrame::cast(f)->print_activation(vframe_no++);
3249 } else {
3250 f->print();
3251 }
3252 if (vframe_no > StackPrintLimit) {
3253 tty->print_cr("...<more frames>...");
3254 return;
3255 }
3256 }
3257 }
3258
3259
3260 void JavaThread::trace_stack() {
3261 if (!has_last_Java_frame()) return;
3262 ResourceMark rm;
3263 HandleMark hm;
3264 RegisterMap reg_map(this);
3265 trace_stack_from(last_java_vframe(®_map));
3266 }
3267
3268
3269 #endif // PRODUCT
3270
3271
3272 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3273 assert(reg_map != NULL, "a map must be given");
3274 frame f = last_frame();
3275 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3276 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3277 }
3278 return NULL;
3279 }
3280
3281
3282 Klass* JavaThread::security_get_caller_class(int depth) {
3283 vframeStream vfst(this);
3284 vfst.security_get_caller_frame(depth);
3285 if (!vfst.at_end()) {
3286 return vfst.method()->method_holder();
3287 }
3288 return NULL;
3289 }
3290
3291 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3292 assert(thread->is_Compiler_thread(), "must be compiler thread");
3293 CompileBroker::compiler_thread_loop();
3294 }
3295
3296 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3297 NMethodSweeper::sweeper_loop();
3298 }
3299
3300 // Create a CompilerThread
3301 CompilerThread::CompilerThread(CompileQueue* queue,
3302 CompilerCounters* counters)
3303 : JavaThread(&compiler_thread_entry) {
3304 _env = NULL;
3305 _log = NULL;
3306 _task = NULL;
3307 _queue = queue;
3308 _counters = counters;
3309 _buffer_blob = NULL;
3310 _compiler = NULL;
3311
3312 #ifndef PRODUCT
3313 _ideal_graph_printer = NULL;
3314 #endif
3315 }
3316
3317 bool CompilerThread::can_call_java() const {
3318 return _compiler != NULL && _compiler->is_jvmci();
3319 }
3320
3321 // Create sweeper thread
3322 CodeCacheSweeperThread::CodeCacheSweeperThread()
3323 : JavaThread(&sweeper_thread_entry) {
3324 _scanned_compiled_method = NULL;
3325 }
3326
3327 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3328 JavaThread::oops_do(f, cf);
3329 if (_scanned_compiled_method != NULL && cf != NULL) {
3330 // Safepoints can occur when the sweeper is scanning an nmethod so
3331 // process it here to make sure it isn't unloaded in the middle of
3332 // a scan.
3333 cf->do_code_blob(_scanned_compiled_method);
3334 }
3335 }
3336
3337 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3338 JavaThread::nmethods_do(cf);
3339 if (_scanned_compiled_method != NULL && cf != NULL) {
3340 // Safepoints can occur when the sweeper is scanning an nmethod so
3341 // process it here to make sure it isn't unloaded in the middle of
3342 // a scan.
3343 cf->do_code_blob(_scanned_compiled_method);
3344 }
3345 }
3346
3347
3348 // ======= Threads ========
3349
3350 // The Threads class links together all active threads, and provides
3351 // operations over all threads. It is protected by its own Mutex
3352 // lock, which is also used in other contexts to protect thread
3353 // operations from having the thread being operated on from exiting
3354 // and going away unexpectedly (e.g., safepoint synchronization)
3355
3356 JavaThread* Threads::_thread_list = NULL;
3357 int Threads::_number_of_threads = 0;
3358 int Threads::_number_of_non_daemon_threads = 0;
3359 int Threads::_return_code = 0;
3360 int Threads::_thread_claim_parity = 0;
3361 size_t JavaThread::_stack_size_at_create = 0;
3362 #ifdef ASSERT
3363 bool Threads::_vm_complete = false;
3364 #endif
3365
3366 // All JavaThreads
3367 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3368
3369 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3370 void Threads::threads_do(ThreadClosure* tc) {
3371 assert_locked_or_safepoint(Threads_lock);
3372 // ALL_JAVA_THREADS iterates through all JavaThreads
3373 ALL_JAVA_THREADS(p) {
3374 tc->do_thread(p);
3375 }
3376 // Someday we could have a table or list of all non-JavaThreads.
3377 // For now, just manually iterate through them.
3378 tc->do_thread(VMThread::vm_thread());
3379 Universe::heap()->gc_threads_do(tc);
3380 WatcherThread *wt = WatcherThread::watcher_thread();
3381 // Strictly speaking, the following NULL check isn't sufficient to make sure
3382 // the data for WatcherThread is still valid upon being examined. However,
3383 // considering that WatchThread terminates when the VM is on the way to
3384 // exit at safepoint, the chance of the above is extremely small. The right
3385 // way to prevent termination of WatcherThread would be to acquire
3386 // Terminator_lock, but we can't do that without violating the lock rank
3387 // checking in some cases.
3388 if (wt != NULL) {
3389 tc->do_thread(wt);
3390 }
3391
3392 // If CompilerThreads ever become non-JavaThreads, add them here
3393 }
3394
3395 void Threads::parallel_java_threads_do(ThreadClosure* tc) {
3396 int cp = Threads::thread_claim_parity();
3397 ALL_JAVA_THREADS(p) {
3398 if (p->claim_oops_do(true, cp)) {
3399 tc->do_thread(p);
3400 }
3401 }
3402 // Thread claiming protocol requires us to claim the same interesting
3403 // threads on all paths. Notably, Threads::possibly_parallel_threads_do
3404 // claims all Java threads *and* the VMThread. To avoid breaking the
3405 // claiming protocol, we have to claim VMThread on this path too, even
3406 // if we do not apply the closure to the VMThread.
3407 VMThread* vmt = VMThread::vm_thread();
3408 (void)vmt->claim_oops_do(true, cp);
3409 }
3410
3411 // The system initialization in the library has three phases.
3412 //
3413 // Phase 1: java.lang.System class initialization
3414 // java.lang.System is a primordial class loaded and initialized
3415 // by the VM early during startup. java.lang.System.<clinit>
3416 // only does registerNatives and keeps the rest of the class
3417 // initialization work later until thread initialization completes.
3418 //
3419 // System.initPhase1 initializes the system properties, the static
3420 // fields in, out, and err. Set up java signal handlers, OS-specific
3421 // system settings, and thread group of the main thread.
3422 static void call_initPhase1(TRAPS) {
3423 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3424 JavaValue result(T_VOID);
3425 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3426 vmSymbols::void_method_signature(), CHECK);
3427 }
3428
3429 // Phase 2. Module system initialization
3430 // This will initialize the module system. Only java.base classes
3431 // can be loaded until phase 2 completes.
3432 //
3433 // Call System.initPhase2 after the compiler initialization and jsr292
3434 // classes get initialized because module initialization runs a lot of java
3435 // code, that for performance reasons, should be compiled. Also, this will
3436 // enable the startup code to use lambda and other language features in this
3437 // phase and onward.
3438 //
3439 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3440 static void call_initPhase2(TRAPS) {
3441 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3442
3443 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3444
3445 JavaValue result(T_INT);
3446 JavaCallArguments args;
3447 args.push_int(DisplayVMOutputToStderr);
3448 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3449 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3450 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3451 if (result.get_jint() != JNI_OK) {
3452 vm_exit_during_initialization(); // no message or exception
3453 }
3454
3455 universe_post_module_init();
3456 }
3457
3458 // Phase 3. final setup - set security manager, system class loader and TCCL
3459 //
3460 // This will instantiate and set the security manager, set the system class
3461 // loader as well as the thread context class loader. The security manager
3462 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3463 // other modules or the application's classpath.
3464 static void call_initPhase3(TRAPS) {
3465 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3466 JavaValue result(T_VOID);
3467 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3468 vmSymbols::void_method_signature(), CHECK);
3469 }
3470
3471 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3472 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3473
3474 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3475 create_vm_init_libraries();
3476 }
3477
3478 initialize_class(vmSymbols::java_lang_String(), CHECK);
3479
3480 // Inject CompactStrings value after the static initializers for String ran.
3481 java_lang_String::set_compact_strings(CompactStrings);
3482
3483 // Initialize java_lang.System (needed before creating the thread)
3484 initialize_class(vmSymbols::java_lang_System(), CHECK);
3485 // The VM creates & returns objects of this class. Make sure it's initialized.
3486 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3487 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3488 Handle thread_group = create_initial_thread_group(CHECK);
3489 Universe::set_main_thread_group(thread_group());
3490 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3491 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3492 main_thread->set_threadObj(thread_object);
3493 // Set thread status to running since main thread has
3494 // been started and running.
3495 java_lang_Thread::set_thread_status(thread_object,
3496 java_lang_Thread::RUNNABLE);
3497
3498 // The VM creates objects of this class.
3499 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3500
3501 // The VM preresolves methods to these classes. Make sure that they get initialized
3502 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3503 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3504
3505 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3506 call_initPhase1(CHECK);
3507
3508 // get the Java runtime name after java.lang.System is initialized
3509 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3510 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3511
3512 // an instance of OutOfMemory exception has been allocated earlier
3513 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3514 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3515 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3516 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3517 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3518 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3519 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3520 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3521 }
3522
3523 void Threads::initialize_jsr292_core_classes(TRAPS) {
3524 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3525
3526 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3527 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3528 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3529 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3530 }
3531
3532 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3533 extern void JDK_Version_init();
3534
3535 // Preinitialize version info.
3536 VM_Version::early_initialize();
3537
3538 // Check version
3539 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3540
3541 // Initialize library-based TLS
3542 ThreadLocalStorage::init();
3543
3544 // Initialize the output stream module
3545 ostream_init();
3546
3547 // Process java launcher properties.
3548 Arguments::process_sun_java_launcher_properties(args);
3549
3550 // Initialize the os module
3551 os::init();
3552
3553 // Record VM creation timing statistics
3554 TraceVmCreationTime create_vm_timer;
3555 create_vm_timer.start();
3556
3557 // Initialize system properties.
3558 Arguments::init_system_properties();
3559
3560 // So that JDK version can be used as a discriminator when parsing arguments
3561 JDK_Version_init();
3562
3563 // Update/Initialize System properties after JDK version number is known
3564 Arguments::init_version_specific_system_properties();
3565
3566 // Make sure to initialize log configuration *before* parsing arguments
3567 LogConfiguration::initialize(create_vm_timer.begin_time());
3568
3569 // Parse arguments
3570 jint parse_result = Arguments::parse(args);
3571 if (parse_result != JNI_OK) return parse_result;
3572
3573 os::init_before_ergo();
3574
3575 jint ergo_result = Arguments::apply_ergo();
3576 if (ergo_result != JNI_OK) return ergo_result;
3577
3578 // Final check of all ranges after ergonomics which may change values.
3579 if (!CommandLineFlagRangeList::check_ranges()) {
3580 return JNI_EINVAL;
3581 }
3582
3583 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3584 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3585 if (!constraint_result) {
3586 return JNI_EINVAL;
3587 }
3588
3589 CommandLineFlagWriteableList::mark_startup();
3590
3591 if (PauseAtStartup) {
3592 os::pause();
3593 }
3594
3595 HOTSPOT_VM_INIT_BEGIN();
3596
3597 // Timing (must come after argument parsing)
3598 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3599
3600 // Initialize the os module after parsing the args
3601 jint os_init_2_result = os::init_2();
3602 if (os_init_2_result != JNI_OK) return os_init_2_result;
3603
3604 jint adjust_after_os_result = Arguments::adjust_after_os();
3605 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3606
3607 // Initialize output stream logging
3608 ostream_init_log();
3609
3610 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3611 // Must be before create_vm_init_agents()
3612 if (Arguments::init_libraries_at_startup()) {
3613 convert_vm_init_libraries_to_agents();
3614 }
3615
3616 // Launch -agentlib/-agentpath and converted -Xrun agents
3617 if (Arguments::init_agents_at_startup()) {
3618 create_vm_init_agents();
3619 }
3620
3621 // Initialize Threads state
3622 _thread_list = NULL;
3623 _number_of_threads = 0;
3624 _number_of_non_daemon_threads = 0;
3625
3626 // Initialize global data structures and create system classes in heap
3627 vm_init_globals();
3628
3629 #if INCLUDE_JVMCI
3630 if (JVMCICounterSize > 0) {
3631 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3632 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3633 } else {
3634 JavaThread::_jvmci_old_thread_counters = NULL;
3635 }
3636 #endif // INCLUDE_JVMCI
3637
3638 // Attach the main thread to this os thread
3639 JavaThread* main_thread = new JavaThread();
3640 main_thread->set_thread_state(_thread_in_vm);
3641 main_thread->initialize_thread_current();
3642 // must do this before set_active_handles
3643 main_thread->record_stack_base_and_size();
3644 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3645
3646 if (!main_thread->set_as_starting_thread()) {
3647 vm_shutdown_during_initialization(
3648 "Failed necessary internal allocation. Out of swap space");
3649 delete main_thread;
3650 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3651 return JNI_ENOMEM;
3652 }
3653
3654 // Enable guard page *after* os::create_main_thread(), otherwise it would
3655 // crash Linux VM, see notes in os_linux.cpp.
3656 main_thread->create_stack_guard_pages();
3657
3658 // Initialize Java-Level synchronization subsystem
3659 ObjectMonitor::Initialize();
3660
3661 // Initialize global modules
3662 jint status = init_globals();
3663 if (status != JNI_OK) {
3664 delete main_thread;
3665 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3666 return status;
3667 }
3668
3669 if (TRACE_INITIALIZE() != JNI_OK) {
3670 vm_exit_during_initialization("Failed to initialize tracing backend");
3671 }
3672
3673 // Should be done after the heap is fully created
3674 main_thread->cache_global_variables();
3675
3676 HandleMark hm;
3677
3678 { MutexLocker mu(Threads_lock);
3679 Threads::add(main_thread);
3680 }
3681
3682 // Any JVMTI raw monitors entered in onload will transition into
3683 // real raw monitor. VM is setup enough here for raw monitor enter.
3684 JvmtiExport::transition_pending_onload_raw_monitors();
3685
3686 // Create the VMThread
3687 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3688
3689 VMThread::create();
3690 Thread* vmthread = VMThread::vm_thread();
3691
3692 if (!os::create_thread(vmthread, os::vm_thread)) {
3693 vm_exit_during_initialization("Cannot create VM thread. "
3694 "Out of system resources.");
3695 }
3696
3697 // Wait for the VM thread to become ready, and VMThread::run to initialize
3698 // Monitors can have spurious returns, must always check another state flag
3699 {
3700 MutexLocker ml(Notify_lock);
3701 os::start_thread(vmthread);
3702 while (vmthread->active_handles() == NULL) {
3703 Notify_lock->wait();
3704 }
3705 }
3706 }
3707
3708 assert(Universe::is_fully_initialized(), "not initialized");
3709 if (VerifyDuringStartup) {
3710 // Make sure we're starting with a clean slate.
3711 VM_Verify verify_op;
3712 VMThread::execute(&verify_op);
3713 }
3714
3715 Thread* THREAD = Thread::current();
3716
3717 // At this point, the Universe is initialized, but we have not executed
3718 // any byte code. Now is a good time (the only time) to dump out the
3719 // internal state of the JVM for sharing.
3720 if (DumpSharedSpaces) {
3721 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3722 ShouldNotReachHere();
3723 }
3724
3725 // Always call even when there are not JVMTI environments yet, since environments
3726 // may be attached late and JVMTI must track phases of VM execution
3727 JvmtiExport::enter_early_start_phase();
3728
3729 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3730 JvmtiExport::post_early_vm_start();
3731
3732 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3733
3734 // We need this for ClassDataSharing - the initial vm.info property is set
3735 // with the default value of CDS "sharing" which may be reset through
3736 // command line options.
3737 reset_vm_info_property(CHECK_JNI_ERR);
3738
3739 quicken_jni_functions();
3740
3741 // No more stub generation allowed after that point.
3742 StubCodeDesc::freeze();
3743
3744 // Set flag that basic initialization has completed. Used by exceptions and various
3745 // debug stuff, that does not work until all basic classes have been initialized.
3746 set_init_completed();
3747
3748 LogConfiguration::post_initialize();
3749 Metaspace::post_initialize();
3750
3751 HOTSPOT_VM_INIT_END();
3752
3753 // record VM initialization completion time
3754 #if INCLUDE_MANAGEMENT
3755 Management::record_vm_init_completed();
3756 #endif // INCLUDE_MANAGEMENT
3757
3758 // Signal Dispatcher needs to be started before VMInit event is posted
3759 os::signal_init(CHECK_JNI_ERR);
3760
3761 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3762 if (!DisableAttachMechanism) {
3763 AttachListener::vm_start();
3764 if (StartAttachListener || AttachListener::init_at_startup()) {
3765 AttachListener::init();
3766 }
3767 }
3768
3769 // Launch -Xrun agents
3770 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3771 // back-end can launch with -Xdebug -Xrunjdwp.
3772 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3773 create_vm_init_libraries();
3774 }
3775
3776 if (CleanChunkPoolAsync) {
3777 Chunk::start_chunk_pool_cleaner_task();
3778 }
3779
3780 // initialize compiler(s)
3781 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3782 CompileBroker::compilation_init(CHECK_JNI_ERR);
3783 #endif
3784
3785 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3786 // It is done after compilers are initialized, because otherwise compilations of
3787 // signature polymorphic MH intrinsics can be missed
3788 // (see SystemDictionary::find_method_handle_intrinsic).
3789 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3790
3791 // This will initialize the module system. Only java.base classes can be
3792 // loaded until phase 2 completes
3793 call_initPhase2(CHECK_JNI_ERR);
3794
3795 // Always call even when there are not JVMTI environments yet, since environments
3796 // may be attached late and JVMTI must track phases of VM execution
3797 JvmtiExport::enter_start_phase();
3798
3799 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3800 JvmtiExport::post_vm_start();
3801
3802 // Final system initialization including security manager and system class loader
3803 call_initPhase3(CHECK_JNI_ERR);
3804
3805 // cache the system class loader
3806 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3807
3808 #if INCLUDE_JVMCI
3809 if (EnableJVMCI) {
3810 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3811 // The JVMCI Java initialization code will read this flag and
3812 // do the printing if it's set.
3813 bool init = JVMCIPrintProperties;
3814
3815 if (!init) {
3816 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3817 // compilations via JVMCI will not actually block until JVMCI is initialized.
3818 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3819 }
3820
3821 if (init) {
3822 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3823 }
3824 }
3825 #endif
3826
3827 // Always call even when there are not JVMTI environments yet, since environments
3828 // may be attached late and JVMTI must track phases of VM execution
3829 JvmtiExport::enter_live_phase();
3830
3831 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3832 JvmtiExport::post_vm_initialized();
3833
3834 if (TRACE_START() != JNI_OK) {
3835 vm_exit_during_initialization("Failed to start tracing backend.");
3836 }
3837
3838 #if INCLUDE_MANAGEMENT
3839 Management::initialize(THREAD);
3840
3841 if (HAS_PENDING_EXCEPTION) {
3842 // management agent fails to start possibly due to
3843 // configuration problem and is responsible for printing
3844 // stack trace if appropriate. Simply exit VM.
3845 vm_exit(1);
3846 }
3847 #endif // INCLUDE_MANAGEMENT
3848
3849 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3850 if (MemProfiling) MemProfiler::engage();
3851 StatSampler::engage();
3852 if (CheckJNICalls) JniPeriodicChecker::engage();
3853
3854 BiasedLocking::init();
3855
3856 #if INCLUDE_RTM_OPT
3857 RTMLockingCounters::init();
3858 #endif
3859
3860 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3861 call_postVMInitHook(THREAD);
3862 // The Java side of PostVMInitHook.run must deal with all
3863 // exceptions and provide means of diagnosis.
3864 if (HAS_PENDING_EXCEPTION) {
3865 CLEAR_PENDING_EXCEPTION;
3866 }
3867 }
3868
3869 {
3870 MutexLocker ml(PeriodicTask_lock);
3871 // Make sure the WatcherThread can be started by WatcherThread::start()
3872 // or by dynamic enrollment.
3873 WatcherThread::make_startable();
3874 // Start up the WatcherThread if there are any periodic tasks
3875 // NOTE: All PeriodicTasks should be registered by now. If they
3876 // aren't, late joiners might appear to start slowly (we might
3877 // take a while to process their first tick).
3878 if (PeriodicTask::num_tasks() > 0) {
3879 WatcherThread::start();
3880 }
3881 }
3882
3883 create_vm_timer.end();
3884 #ifdef ASSERT
3885 _vm_complete = true;
3886 #endif
3887 return JNI_OK;
3888 }
3889
3890 // type for the Agent_OnLoad and JVM_OnLoad entry points
3891 extern "C" {
3892 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3893 }
3894 // Find a command line agent library and return its entry point for
3895 // -agentlib: -agentpath: -Xrun
3896 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3897 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3898 const char *on_load_symbols[],
3899 size_t num_symbol_entries) {
3900 OnLoadEntry_t on_load_entry = NULL;
3901 void *library = NULL;
3902
3903 if (!agent->valid()) {
3904 char buffer[JVM_MAXPATHLEN];
3905 char ebuf[1024] = "";
3906 const char *name = agent->name();
3907 const char *msg = "Could not find agent library ";
3908
3909 // First check to see if agent is statically linked into executable
3910 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3911 library = agent->os_lib();
3912 } else if (agent->is_absolute_path()) {
3913 library = os::dll_load(name, ebuf, sizeof ebuf);
3914 if (library == NULL) {
3915 const char *sub_msg = " in absolute path, with error: ";
3916 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3917 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3918 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3919 // If we can't find the agent, exit.
3920 vm_exit_during_initialization(buf, NULL);
3921 FREE_C_HEAP_ARRAY(char, buf);
3922 }
3923 } else {
3924 // Try to load the agent from the standard dll directory
3925 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3926 name)) {
3927 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3928 }
3929 if (library == NULL) { // Try the local directory
3930 char ns[1] = {0};
3931 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3932 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3933 }
3934 if (library == NULL) {
3935 const char *sub_msg = " on the library path, with error: ";
3936 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3937 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3938 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3939 // If we can't find the agent, exit.
3940 vm_exit_during_initialization(buf, NULL);
3941 FREE_C_HEAP_ARRAY(char, buf);
3942 }
3943 }
3944 }
3945 agent->set_os_lib(library);
3946 agent->set_valid();
3947 }
3948
3949 // Find the OnLoad function.
3950 on_load_entry =
3951 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3952 false,
3953 on_load_symbols,
3954 num_symbol_entries));
3955 return on_load_entry;
3956 }
3957
3958 // Find the JVM_OnLoad entry point
3959 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3960 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3961 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3962 }
3963
3964 // Find the Agent_OnLoad entry point
3965 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3966 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3967 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3968 }
3969
3970 // For backwards compatibility with -Xrun
3971 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3972 // treated like -agentpath:
3973 // Must be called before agent libraries are created
3974 void Threads::convert_vm_init_libraries_to_agents() {
3975 AgentLibrary* agent;
3976 AgentLibrary* next;
3977
3978 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3979 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3980 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3981
3982 // If there is an JVM_OnLoad function it will get called later,
3983 // otherwise see if there is an Agent_OnLoad
3984 if (on_load_entry == NULL) {
3985 on_load_entry = lookup_agent_on_load(agent);
3986 if (on_load_entry != NULL) {
3987 // switch it to the agent list -- so that Agent_OnLoad will be called,
3988 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3989 Arguments::convert_library_to_agent(agent);
3990 } else {
3991 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3992 }
3993 }
3994 }
3995 }
3996
3997 // Create agents for -agentlib: -agentpath: and converted -Xrun
3998 // Invokes Agent_OnLoad
3999 // Called very early -- before JavaThreads exist
4000 void Threads::create_vm_init_agents() {
4001 extern struct JavaVM_ main_vm;
4002 AgentLibrary* agent;
4003
4004 JvmtiExport::enter_onload_phase();
4005
4006 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4007 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4008
4009 if (on_load_entry != NULL) {
4010 // Invoke the Agent_OnLoad function
4011 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4012 if (err != JNI_OK) {
4013 vm_exit_during_initialization("agent library failed to init", agent->name());
4014 }
4015 } else {
4016 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4017 }
4018 }
4019 JvmtiExport::enter_primordial_phase();
4020 }
4021
4022 extern "C" {
4023 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4024 }
4025
4026 void Threads::shutdown_vm_agents() {
4027 // Send any Agent_OnUnload notifications
4028 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4029 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4030 extern struct JavaVM_ main_vm;
4031 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4032
4033 // Find the Agent_OnUnload function.
4034 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4035 os::find_agent_function(agent,
4036 false,
4037 on_unload_symbols,
4038 num_symbol_entries));
4039
4040 // Invoke the Agent_OnUnload function
4041 if (unload_entry != NULL) {
4042 JavaThread* thread = JavaThread::current();
4043 ThreadToNativeFromVM ttn(thread);
4044 HandleMark hm(thread);
4045 (*unload_entry)(&main_vm);
4046 }
4047 }
4048 }
4049
4050 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4051 // Invokes JVM_OnLoad
4052 void Threads::create_vm_init_libraries() {
4053 extern struct JavaVM_ main_vm;
4054 AgentLibrary* agent;
4055
4056 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4057 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4058
4059 if (on_load_entry != NULL) {
4060 // Invoke the JVM_OnLoad function
4061 JavaThread* thread = JavaThread::current();
4062 ThreadToNativeFromVM ttn(thread);
4063 HandleMark hm(thread);
4064 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4065 if (err != JNI_OK) {
4066 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4067 }
4068 } else {
4069 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4070 }
4071 }
4072 }
4073
4074 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4075 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4076
4077 JavaThread* java_thread = NULL;
4078 // Sequential search for now. Need to do better optimization later.
4079 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4080 oop tobj = thread->threadObj();
4081 if (!thread->is_exiting() &&
4082 tobj != NULL &&
4083 java_tid == java_lang_Thread::thread_id(tobj)) {
4084 java_thread = thread;
4085 break;
4086 }
4087 }
4088 return java_thread;
4089 }
4090
4091
4092 // Last thread running calls java.lang.Shutdown.shutdown()
4093 void JavaThread::invoke_shutdown_hooks() {
4094 HandleMark hm(this);
4095
4096 // We could get here with a pending exception, if so clear it now.
4097 if (this->has_pending_exception()) {
4098 this->clear_pending_exception();
4099 }
4100
4101 EXCEPTION_MARK;
4102 Klass* shutdown_klass =
4103 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4104 THREAD);
4105 if (shutdown_klass != NULL) {
4106 // SystemDictionary::resolve_or_null will return null if there was
4107 // an exception. If we cannot load the Shutdown class, just don't
4108 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4109 // and finalizers (if runFinalizersOnExit is set) won't be run.
4110 // Note that if a shutdown hook was registered or runFinalizersOnExit
4111 // was called, the Shutdown class would have already been loaded
4112 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4113 JavaValue result(T_VOID);
4114 JavaCalls::call_static(&result,
4115 shutdown_klass,
4116 vmSymbols::shutdown_method_name(),
4117 vmSymbols::void_method_signature(),
4118 THREAD);
4119 }
4120 CLEAR_PENDING_EXCEPTION;
4121 }
4122
4123 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4124 // the program falls off the end of main(). Another VM exit path is through
4125 // vm_exit() when the program calls System.exit() to return a value or when
4126 // there is a serious error in VM. The two shutdown paths are not exactly
4127 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4128 // and VM_Exit op at VM level.
4129 //
4130 // Shutdown sequence:
4131 // + Shutdown native memory tracking if it is on
4132 // + Wait until we are the last non-daemon thread to execute
4133 // <-- every thing is still working at this moment -->
4134 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4135 // shutdown hooks, run finalizers if finalization-on-exit
4136 // + Call before_exit(), prepare for VM exit
4137 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4138 // currently the only user of this mechanism is File.deleteOnExit())
4139 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4140 // post thread end and vm death events to JVMTI,
4141 // stop signal thread
4142 // + Call JavaThread::exit(), it will:
4143 // > release JNI handle blocks, remove stack guard pages
4144 // > remove this thread from Threads list
4145 // <-- no more Java code from this thread after this point -->
4146 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4147 // the compiler threads at safepoint
4148 // <-- do not use anything that could get blocked by Safepoint -->
4149 // + Disable tracing at JNI/JVM barriers
4150 // + Set _vm_exited flag for threads that are still running native code
4151 // + Delete this thread
4152 // + Call exit_globals()
4153 // > deletes tty
4154 // > deletes PerfMemory resources
4155 // + Return to caller
4156
4157 bool Threads::destroy_vm() {
4158 JavaThread* thread = JavaThread::current();
4159
4160 #ifdef ASSERT
4161 _vm_complete = false;
4162 #endif
4163 // Wait until we are the last non-daemon thread to execute
4164 { MutexLocker nu(Threads_lock);
4165 while (Threads::number_of_non_daemon_threads() > 1)
4166 // This wait should make safepoint checks, wait without a timeout,
4167 // and wait as a suspend-equivalent condition.
4168 //
4169 // Note: If the FlatProfiler is running and this thread is waiting
4170 // for another non-daemon thread to finish, then the FlatProfiler
4171 // is waiting for the external suspend request on this thread to
4172 // complete. wait_for_ext_suspend_completion() will eventually
4173 // timeout, but that takes time. Making this wait a suspend-
4174 // equivalent condition solves that timeout problem.
4175 //
4176 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4177 Mutex::_as_suspend_equivalent_flag);
4178 }
4179
4180 // Hang forever on exit if we are reporting an error.
4181 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4182 os::infinite_sleep();
4183 }
4184 os::wait_for_keypress_at_exit();
4185
4186 // run Java level shutdown hooks
4187 thread->invoke_shutdown_hooks();
4188
4189 before_exit(thread);
4190
4191 thread->exit(true);
4192
4193 // Stop VM thread.
4194 {
4195 // 4945125 The vm thread comes to a safepoint during exit.
4196 // GC vm_operations can get caught at the safepoint, and the
4197 // heap is unparseable if they are caught. Grab the Heap_lock
4198 // to prevent this. The GC vm_operations will not be able to
4199 // queue until after the vm thread is dead. After this point,
4200 // we'll never emerge out of the safepoint before the VM exits.
4201
4202 MutexLocker ml(Heap_lock);
4203
4204 VMThread::wait_for_vm_thread_exit();
4205 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4206 VMThread::destroy();
4207 }
4208
4209 // clean up ideal graph printers
4210 #if defined(COMPILER2) && !defined(PRODUCT)
4211 IdealGraphPrinter::clean_up();
4212 #endif
4213
4214 // Now, all Java threads are gone except daemon threads. Daemon threads
4215 // running Java code or in VM are stopped by the Safepoint. However,
4216 // daemon threads executing native code are still running. But they
4217 // will be stopped at native=>Java/VM barriers. Note that we can't
4218 // simply kill or suspend them, as it is inherently deadlock-prone.
4219
4220 VM_Exit::set_vm_exited();
4221
4222 notify_vm_shutdown();
4223
4224 delete thread;
4225
4226 #if INCLUDE_JVMCI
4227 if (JVMCICounterSize > 0) {
4228 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4229 }
4230 #endif
4231
4232 // exit_globals() will delete tty
4233 exit_globals();
4234
4235 LogConfiguration::finalize();
4236
4237 return true;
4238 }
4239
4240
4241 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4242 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4243 return is_supported_jni_version(version);
4244 }
4245
4246
4247 jboolean Threads::is_supported_jni_version(jint version) {
4248 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4249 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4250 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4251 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4252 if (version == JNI_VERSION_9) return JNI_TRUE;
4253 return JNI_FALSE;
4254 }
4255
4256
4257 void Threads::add(JavaThread* p, bool force_daemon) {
4258 // The threads lock must be owned at this point
4259 assert_locked_or_safepoint(Threads_lock);
4260
4261 // See the comment for this method in thread.hpp for its purpose and
4262 // why it is called here.
4263 p->initialize_queues();
4264 p->set_next(_thread_list);
4265 _thread_list = p;
4266 _number_of_threads++;
4267 oop threadObj = p->threadObj();
4268 bool daemon = true;
4269 // Bootstrapping problem: threadObj can be null for initial
4270 // JavaThread (or for threads attached via JNI)
4271 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4272 _number_of_non_daemon_threads++;
4273 daemon = false;
4274 }
4275
4276 ThreadService::add_thread(p, daemon);
4277
4278 // Possible GC point.
4279 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4280 }
4281
4282 void Threads::remove(JavaThread* p) {
4283
4284 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4285 ObjectSynchronizer::omFlush(p);
4286
4287 // Extra scope needed for Thread_lock, so we can check
4288 // that we do not remove thread without safepoint code notice
4289 { MutexLocker ml(Threads_lock);
4290
4291 assert(includes(p), "p must be present");
4292
4293 JavaThread* current = _thread_list;
4294 JavaThread* prev = NULL;
4295
4296 while (current != p) {
4297 prev = current;
4298 current = current->next();
4299 }
4300
4301 if (prev) {
4302 prev->set_next(current->next());
4303 } else {
4304 _thread_list = p->next();
4305 }
4306 _number_of_threads--;
4307 oop threadObj = p->threadObj();
4308 bool daemon = true;
4309 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4310 _number_of_non_daemon_threads--;
4311 daemon = false;
4312
4313 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4314 // on destroy_vm will wake up.
4315 if (number_of_non_daemon_threads() == 1) {
4316 Threads_lock->notify_all();
4317 }
4318 }
4319 ThreadService::remove_thread(p, daemon);
4320
4321 // Make sure that safepoint code disregard this thread. This is needed since
4322 // the thread might mess around with locks after this point. This can cause it
4323 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4324 // of this thread since it is removed from the queue.
4325 p->set_terminated_value();
4326 } // unlock Threads_lock
4327
4328 // Since Events::log uses a lock, we grab it outside the Threads_lock
4329 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4330 }
4331
4332 // Threads_lock must be held when this is called (or must be called during a safepoint)
4333 bool Threads::includes(JavaThread* p) {
4334 assert(Threads_lock->is_locked(), "sanity check");
4335 ALL_JAVA_THREADS(q) {
4336 if (q == p) {
4337 return true;
4338 }
4339 }
4340 return false;
4341 }
4342
4343 // Operations on the Threads list for GC. These are not explicitly locked,
4344 // but the garbage collector must provide a safe context for them to run.
4345 // In particular, these things should never be called when the Threads_lock
4346 // is held by some other thread. (Note: the Safepoint abstraction also
4347 // uses the Threads_lock to guarantee this property. It also makes sure that
4348 // all threads gets blocked when exiting or starting).
4349
4350 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4351 ALL_JAVA_THREADS(p) {
4352 p->oops_do(f, cf);
4353 }
4354 VMThread::vm_thread()->oops_do(f, cf);
4355 }
4356
4357 void Threads::change_thread_claim_parity() {
4358 // Set the new claim parity.
4359 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4360 "Not in range.");
4361 _thread_claim_parity++;
4362 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4363 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4364 "Not in range.");
4365 }
4366
4367 #ifdef ASSERT
4368 void Threads::assert_all_threads_claimed() {
4369 ALL_JAVA_THREADS(p) {
4370 const int thread_parity = p->oops_do_parity();
4371 assert((thread_parity == _thread_claim_parity),
4372 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4373 }
4374 VMThread* vmt = VMThread::vm_thread();
4375 const int thread_parity = vmt->oops_do_parity();
4376 assert((thread_parity == _thread_claim_parity),
4377 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4378 }
4379 #endif // ASSERT
4380
4381 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4382 int cp = Threads::thread_claim_parity();
4383 ALL_JAVA_THREADS(p) {
4384 if (p->claim_oops_do(is_par, cp)) {
4385 p->oops_do(f, cf);
4386 }
4387 }
4388 VMThread* vmt = VMThread::vm_thread();
4389 if (vmt->claim_oops_do(is_par, cp)) {
4390 vmt->oops_do(f, cf);
4391 }
4392 }
4393
4394 #if INCLUDE_ALL_GCS
4395 // Used by ParallelScavenge
4396 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4397 ALL_JAVA_THREADS(p) {
4398 q->enqueue(new ThreadRootsTask(p));
4399 }
4400 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4401 }
4402
4403 // Used by Parallel Old
4404 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4405 ALL_JAVA_THREADS(p) {
4406 q->enqueue(new ThreadRootsMarkingTask(p));
4407 }
4408 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4409 }
4410 #endif // INCLUDE_ALL_GCS
4411
4412 void Threads::nmethods_do(CodeBlobClosure* cf) {
4413 ALL_JAVA_THREADS(p) {
4414 // This is used by the code cache sweeper to mark nmethods that are active
4415 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4416 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4417 if(!p->is_Code_cache_sweeper_thread()) {
4418 p->nmethods_do(cf);
4419 }
4420 }
4421 }
4422
4423 void Threads::metadata_do(void f(Metadata*)) {
4424 ALL_JAVA_THREADS(p) {
4425 p->metadata_do(f);
4426 }
4427 }
4428
4429 class ThreadHandlesClosure : public ThreadClosure {
4430 void (*_f)(Metadata*);
4431 public:
4432 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4433 virtual void do_thread(Thread* thread) {
4434 thread->metadata_handles_do(_f);
4435 }
4436 };
4437
4438 void Threads::metadata_handles_do(void f(Metadata*)) {
4439 // Only walk the Handles in Thread.
4440 ThreadHandlesClosure handles_closure(f);
4441 threads_do(&handles_closure);
4442 }
4443
4444 void Threads::deoptimized_wrt_marked_nmethods() {
4445 ALL_JAVA_THREADS(p) {
4446 p->deoptimized_wrt_marked_nmethods();
4447 }
4448 }
4449
4450
4451 // Get count Java threads that are waiting to enter the specified monitor.
4452 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4453 address monitor,
4454 bool doLock) {
4455 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4456 "must grab Threads_lock or be at safepoint");
4457 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4458
4459 int i = 0;
4460 {
4461 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4462 ALL_JAVA_THREADS(p) {
4463 if (!p->can_call_java()) continue;
4464
4465 address pending = (address)p->current_pending_monitor();
4466 if (pending == monitor) { // found a match
4467 if (i < count) result->append(p); // save the first count matches
4468 i++;
4469 }
4470 }
4471 }
4472 return result;
4473 }
4474
4475
4476 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4477 bool doLock) {
4478 assert(doLock ||
4479 Threads_lock->owned_by_self() ||
4480 SafepointSynchronize::is_at_safepoint(),
4481 "must grab Threads_lock or be at safepoint");
4482
4483 // NULL owner means not locked so we can skip the search
4484 if (owner == NULL) return NULL;
4485
4486 {
4487 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4488 ALL_JAVA_THREADS(p) {
4489 // first, see if owner is the address of a Java thread
4490 if (owner == (address)p) return p;
4491 }
4492 }
4493 // Cannot assert on lack of success here since this function may be
4494 // used by code that is trying to report useful problem information
4495 // like deadlock detection.
4496 if (UseHeavyMonitors) return NULL;
4497
4498 // If we didn't find a matching Java thread and we didn't force use of
4499 // heavyweight monitors, then the owner is the stack address of the
4500 // Lock Word in the owning Java thread's stack.
4501 //
4502 JavaThread* the_owner = NULL;
4503 {
4504 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4505 ALL_JAVA_THREADS(q) {
4506 if (q->is_lock_owned(owner)) {
4507 the_owner = q;
4508 break;
4509 }
4510 }
4511 }
4512 // cannot assert on lack of success here; see above comment
4513 return the_owner;
4514 }
4515
4516 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4517 void Threads::print_on(outputStream* st, bool print_stacks,
4518 bool internal_format, bool print_concurrent_locks) {
4519 char buf[32];
4520 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4521
4522 st->print_cr("Full thread dump %s (%s %s):",
4523 Abstract_VM_Version::vm_name(),
4524 Abstract_VM_Version::vm_release(),
4525 Abstract_VM_Version::vm_info_string());
4526 st->cr();
4527
4528 #if INCLUDE_SERVICES
4529 // Dump concurrent locks
4530 ConcurrentLocksDump concurrent_locks;
4531 if (print_concurrent_locks) {
4532 concurrent_locks.dump_at_safepoint();
4533 }
4534 #endif // INCLUDE_SERVICES
4535
4536 ALL_JAVA_THREADS(p) {
4537 ResourceMark rm;
4538 p->print_on(st);
4539 if (print_stacks) {
4540 if (internal_format) {
4541 p->trace_stack();
4542 } else {
4543 p->print_stack_on(st);
4544 }
4545 }
4546 st->cr();
4547 #if INCLUDE_SERVICES
4548 if (print_concurrent_locks) {
4549 concurrent_locks.print_locks_on(p, st);
4550 }
4551 #endif // INCLUDE_SERVICES
4552 }
4553
4554 VMThread::vm_thread()->print_on(st);
4555 st->cr();
4556 Universe::heap()->print_gc_threads_on(st);
4557 WatcherThread* wt = WatcherThread::watcher_thread();
4558 if (wt != NULL) {
4559 wt->print_on(st);
4560 st->cr();
4561 }
4562 st->flush();
4563 }
4564
4565 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4566 int buflen, bool* found_current) {
4567 if (this_thread != NULL) {
4568 bool is_current = (current == this_thread);
4569 *found_current = *found_current || is_current;
4570 st->print("%s", is_current ? "=>" : " ");
4571
4572 st->print(PTR_FORMAT, p2i(this_thread));
4573 st->print(" ");
4574 this_thread->print_on_error(st, buf, buflen);
4575 st->cr();
4576 }
4577 }
4578
4579 class PrintOnErrorClosure : public ThreadClosure {
4580 outputStream* _st;
4581 Thread* _current;
4582 char* _buf;
4583 int _buflen;
4584 bool* _found_current;
4585 public:
4586 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4587 int buflen, bool* found_current) :
4588 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4589
4590 virtual void do_thread(Thread* thread) {
4591 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4592 }
4593 };
4594
4595 // Threads::print_on_error() is called by fatal error handler. It's possible
4596 // that VM is not at safepoint and/or current thread is inside signal handler.
4597 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4598 // memory (even in resource area), it might deadlock the error handler.
4599 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4600 int buflen) {
4601 bool found_current = false;
4602 st->print_cr("Java Threads: ( => current thread )");
4603 ALL_JAVA_THREADS(thread) {
4604 print_on_error(thread, st, current, buf, buflen, &found_current);
4605 }
4606 st->cr();
4607
4608 st->print_cr("Other Threads:");
4609 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4610 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4611
4612 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4613 Universe::heap()->gc_threads_do(&print_closure);
4614
4615 if (!found_current) {
4616 st->cr();
4617 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4618 current->print_on_error(st, buf, buflen);
4619 st->cr();
4620 }
4621 st->cr();
4622 st->print_cr("Threads with active compile tasks:");
4623 print_threads_compiling(st, buf, buflen);
4624 }
4625
4626 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4627 ALL_JAVA_THREADS(thread) {
4628 if (thread->is_Compiler_thread()) {
4629 CompilerThread* ct = (CompilerThread*) thread;
4630 if (ct->task() != NULL) {
4631 thread->print_name_on_error(st, buf, buflen);
4632 ct->task()->print(st, NULL, true, true);
4633 }
4634 }
4635 }
4636 }
4637
4638
4639 // Internal SpinLock and Mutex
4640 // Based on ParkEvent
4641
4642 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4643 //
4644 // We employ SpinLocks _only for low-contention, fixed-length
4645 // short-duration critical sections where we're concerned
4646 // about native mutex_t or HotSpot Mutex:: latency.
4647 // The mux construct provides a spin-then-block mutual exclusion
4648 // mechanism.
4649 //
4650 // Testing has shown that contention on the ListLock guarding gFreeList
4651 // is common. If we implement ListLock as a simple SpinLock it's common
4652 // for the JVM to devolve to yielding with little progress. This is true
4653 // despite the fact that the critical sections protected by ListLock are
4654 // extremely short.
4655 //
4656 // TODO-FIXME: ListLock should be of type SpinLock.
4657 // We should make this a 1st-class type, integrated into the lock
4658 // hierarchy as leaf-locks. Critically, the SpinLock structure
4659 // should have sufficient padding to avoid false-sharing and excessive
4660 // cache-coherency traffic.
4661
4662
4663 typedef volatile int SpinLockT;
4664
4665 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4666 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4667 return; // normal fast-path return
4668 }
4669
4670 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4671 TEVENT(SpinAcquire - ctx);
4672 int ctr = 0;
4673 int Yields = 0;
4674 for (;;) {
4675 while (*adr != 0) {
4676 ++ctr;
4677 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4678 if (Yields > 5) {
4679 os::naked_short_sleep(1);
4680 } else {
4681 os::naked_yield();
4682 ++Yields;
4683 }
4684 } else {
4685 SpinPause();
4686 }
4687 }
4688 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4689 }
4690 }
4691
4692 void Thread::SpinRelease(volatile int * adr) {
4693 assert(*adr != 0, "invariant");
4694 OrderAccess::fence(); // guarantee at least release consistency.
4695 // Roach-motel semantics.
4696 // It's safe if subsequent LDs and STs float "up" into the critical section,
4697 // but prior LDs and STs within the critical section can't be allowed
4698 // to reorder or float past the ST that releases the lock.
4699 // Loads and stores in the critical section - which appear in program
4700 // order before the store that releases the lock - must also appear
4701 // before the store that releases the lock in memory visibility order.
4702 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4703 // the ST of 0 into the lock-word which releases the lock, so fence
4704 // more than covers this on all platforms.
4705 *adr = 0;
4706 }
4707
4708 // muxAcquire and muxRelease:
4709 //
4710 // * muxAcquire and muxRelease support a single-word lock-word construct.
4711 // The LSB of the word is set IFF the lock is held.
4712 // The remainder of the word points to the head of a singly-linked list
4713 // of threads blocked on the lock.
4714 //
4715 // * The current implementation of muxAcquire-muxRelease uses its own
4716 // dedicated Thread._MuxEvent instance. If we're interested in
4717 // minimizing the peak number of extant ParkEvent instances then
4718 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4719 // as certain invariants were satisfied. Specifically, care would need
4720 // to be taken with regards to consuming unpark() "permits".
4721 // A safe rule of thumb is that a thread would never call muxAcquire()
4722 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4723 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4724 // consume an unpark() permit intended for monitorenter, for instance.
4725 // One way around this would be to widen the restricted-range semaphore
4726 // implemented in park(). Another alternative would be to provide
4727 // multiple instances of the PlatformEvent() for each thread. One
4728 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4729 //
4730 // * Usage:
4731 // -- Only as leaf locks
4732 // -- for short-term locking only as muxAcquire does not perform
4733 // thread state transitions.
4734 //
4735 // Alternatives:
4736 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4737 // but with parking or spin-then-park instead of pure spinning.
4738 // * Use Taura-Oyama-Yonenzawa locks.
4739 // * It's possible to construct a 1-0 lock if we encode the lockword as
4740 // (List,LockByte). Acquire will CAS the full lockword while Release
4741 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4742 // acquiring threads use timers (ParkTimed) to detect and recover from
4743 // the stranding window. Thread/Node structures must be aligned on 256-byte
4744 // boundaries by using placement-new.
4745 // * Augment MCS with advisory back-link fields maintained with CAS().
4746 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4747 // The validity of the backlinks must be ratified before we trust the value.
4748 // If the backlinks are invalid the exiting thread must back-track through the
4749 // the forward links, which are always trustworthy.
4750 // * Add a successor indication. The LockWord is currently encoded as
4751 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4752 // to provide the usual futile-wakeup optimization.
4753 // See RTStt for details.
4754 // * Consider schedctl.sc_nopreempt to cover the critical section.
4755 //
4756
4757
4758 typedef volatile intptr_t MutexT; // Mux Lock-word
4759 enum MuxBits { LOCKBIT = 1 };
4760
4761 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4762 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4763 if (w == 0) return;
4764 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4765 return;
4766 }
4767
4768 TEVENT(muxAcquire - Contention);
4769 ParkEvent * const Self = Thread::current()->_MuxEvent;
4770 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4771 for (;;) {
4772 int its = (os::is_MP() ? 100 : 0) + 1;
4773
4774 // Optional spin phase: spin-then-park strategy
4775 while (--its >= 0) {
4776 w = *Lock;
4777 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4778 return;
4779 }
4780 }
4781
4782 Self->reset();
4783 Self->OnList = intptr_t(Lock);
4784 // The following fence() isn't _strictly necessary as the subsequent
4785 // CAS() both serializes execution and ratifies the fetched *Lock value.
4786 OrderAccess::fence();
4787 for (;;) {
4788 w = *Lock;
4789 if ((w & LOCKBIT) == 0) {
4790 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4791 Self->OnList = 0; // hygiene - allows stronger asserts
4792 return;
4793 }
4794 continue; // Interference -- *Lock changed -- Just retry
4795 }
4796 assert(w & LOCKBIT, "invariant");
4797 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4798 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4799 }
4800
4801 while (Self->OnList != 0) {
4802 Self->park();
4803 }
4804 }
4805 }
4806
4807 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4808 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4809 if (w == 0) return;
4810 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4811 return;
4812 }
4813
4814 TEVENT(muxAcquire - Contention);
4815 ParkEvent * ReleaseAfter = NULL;
4816 if (ev == NULL) {
4817 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4818 }
4819 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4820 for (;;) {
4821 guarantee(ev->OnList == 0, "invariant");
4822 int its = (os::is_MP() ? 100 : 0) + 1;
4823
4824 // Optional spin phase: spin-then-park strategy
4825 while (--its >= 0) {
4826 w = *Lock;
4827 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4828 if (ReleaseAfter != NULL) {
4829 ParkEvent::Release(ReleaseAfter);
4830 }
4831 return;
4832 }
4833 }
4834
4835 ev->reset();
4836 ev->OnList = intptr_t(Lock);
4837 // The following fence() isn't _strictly necessary as the subsequent
4838 // CAS() both serializes execution and ratifies the fetched *Lock value.
4839 OrderAccess::fence();
4840 for (;;) {
4841 w = *Lock;
4842 if ((w & LOCKBIT) == 0) {
4843 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4844 ev->OnList = 0;
4845 // We call ::Release while holding the outer lock, thus
4846 // artificially lengthening the critical section.
4847 // Consider deferring the ::Release() until the subsequent unlock(),
4848 // after we've dropped the outer lock.
4849 if (ReleaseAfter != NULL) {
4850 ParkEvent::Release(ReleaseAfter);
4851 }
4852 return;
4853 }
4854 continue; // Interference -- *Lock changed -- Just retry
4855 }
4856 assert(w & LOCKBIT, "invariant");
4857 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4858 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4859 }
4860
4861 while (ev->OnList != 0) {
4862 ev->park();
4863 }
4864 }
4865 }
4866
4867 // Release() must extract a successor from the list and then wake that thread.
4868 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4869 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4870 // Release() would :
4871 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4872 // (B) Extract a successor from the private list "in-hand"
4873 // (C) attempt to CAS() the residual back into *Lock over null.
4874 // If there were any newly arrived threads and the CAS() would fail.
4875 // In that case Release() would detach the RATs, re-merge the list in-hand
4876 // with the RATs and repeat as needed. Alternately, Release() might
4877 // detach and extract a successor, but then pass the residual list to the wakee.
4878 // The wakee would be responsible for reattaching and remerging before it
4879 // competed for the lock.
4880 //
4881 // Both "pop" and DMR are immune from ABA corruption -- there can be
4882 // multiple concurrent pushers, but only one popper or detacher.
4883 // This implementation pops from the head of the list. This is unfair,
4884 // but tends to provide excellent throughput as hot threads remain hot.
4885 // (We wake recently run threads first).
4886 //
4887 // All paths through muxRelease() will execute a CAS.
4888 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4889 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4890 // executed within the critical section are complete and globally visible before the
4891 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4892 void Thread::muxRelease(volatile intptr_t * Lock) {
4893 for (;;) {
4894 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4895 assert(w & LOCKBIT, "invariant");
4896 if (w == LOCKBIT) return;
4897 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4898 assert(List != NULL, "invariant");
4899 assert(List->OnList == intptr_t(Lock), "invariant");
4900 ParkEvent * const nxt = List->ListNext;
4901 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4902
4903 // The following CAS() releases the lock and pops the head element.
4904 // The CAS() also ratifies the previously fetched lock-word value.
4905 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4906 continue;
4907 }
4908 List->OnList = 0;
4909 OrderAccess::fence();
4910 List->unpark();
4911 return;
4912 }
4913 }
4914
4915
4916 void Threads::verify() {
4917 ALL_JAVA_THREADS(p) {
4918 p->verify();
4919 }
4920 VMThread* thread = VMThread::vm_thread();
4921 if (thread != NULL) thread->verify();
4922 }