1 /*
2 * Copyright (c) 1997, 2018, 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 "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/barrierSet.hpp"
37 #include "gc/shared/gcId.hpp"
38 #include "gc/shared/gcLocker.inline.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "jfr/support/jfrThreadId.hpp"
45 #include "jvmtifiles/jvmtiEnv.hpp"
46 #include "logging/log.hpp"
47 #include "logging/logConfiguration.hpp"
48 #include "logging/logStream.hpp"
49 #include "memory/allocation.inline.hpp"
50 #include "memory/metaspaceShared.hpp"
51 #include "memory/oopFactory.hpp"
52 #include "memory/resourceArea.hpp"
53 #include "memory/universe.hpp"
54 #include "oops/access.inline.hpp"
55 #include "oops/instanceKlass.hpp"
56 #include "oops/objArrayOop.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/symbol.hpp"
59 #include "oops/typeArrayOop.inline.hpp"
60 #include "oops/valueKlass.hpp"
61 #include "oops/verifyOopClosure.hpp"
62 #include "prims/jvm_misc.hpp"
63 #include "prims/jvmtiExport.hpp"
64 #include "prims/jvmtiThreadState.hpp"
65 #include "prims/privilegedStack.hpp"
66 #include "runtime/arguments.hpp"
67 #include "runtime/atomic.hpp"
68 #include "runtime/biasedLocking.hpp"
69 #include "runtime/fieldDescriptor.inline.hpp"
70 #include "runtime/flags/jvmFlagConstraintList.hpp"
71 #include "runtime/flags/jvmFlagRangeList.hpp"
72 #include "runtime/flags/jvmFlagWriteableList.hpp"
73 #include "runtime/deoptimization.hpp"
74 #include "runtime/frame.inline.hpp"
75 #include "runtime/handshake.hpp"
76 #include "runtime/init.hpp"
77 #include "runtime/interfaceSupport.inline.hpp"
78 #include "runtime/java.hpp"
79 #include "runtime/javaCalls.hpp"
80 #include "runtime/jniHandles.inline.hpp"
81 #include "runtime/jniPeriodicChecker.hpp"
82 #include "runtime/memprofiler.hpp"
83 #include "runtime/mutexLocker.hpp"
84 #include "runtime/objectMonitor.hpp"
85 #include "runtime/orderAccess.hpp"
86 #include "runtime/osThread.hpp"
87 #include "runtime/prefetch.inline.hpp"
88 #include "runtime/safepoint.hpp"
89 #include "runtime/safepointMechanism.inline.hpp"
90 #include "runtime/safepointVerifiers.hpp"
91 #include "runtime/sharedRuntime.hpp"
92 #include "runtime/statSampler.hpp"
93 #include "runtime/stubRoutines.hpp"
94 #include "runtime/sweeper.hpp"
95 #include "runtime/task.hpp"
96 #include "runtime/thread.inline.hpp"
97 #include "runtime/threadCritical.hpp"
98 #include "runtime/threadSMR.inline.hpp"
99 #include "runtime/threadStatisticalInfo.hpp"
100 #include "runtime/timer.hpp"
101 #include "runtime/timerTrace.hpp"
102 #include "runtime/vframe.inline.hpp"
103 #include "runtime/vframeArray.hpp"
104 #include "runtime/vframe_hp.hpp"
105 #include "runtime/vmThread.hpp"
106 #include "runtime/vm_operations.hpp"
107 #include "runtime/vm_version.hpp"
108 #include "services/attachListener.hpp"
109 #include "services/management.hpp"
110 #include "services/memTracker.hpp"
111 #include "services/threadService.hpp"
112 #include "utilities/align.hpp"
113 #include "utilities/copy.hpp"
114 #include "utilities/defaultStream.hpp"
115 #include "utilities/dtrace.hpp"
116 #include "utilities/events.hpp"
117 #include "utilities/macros.hpp"
118 #include "utilities/preserveException.hpp"
119 #include "utilities/singleWriterSynchronizer.hpp"
120 #include "utilities/vmError.hpp"
121 #if INCLUDE_JVMCI
122 #include "jvmci/jvmciCompiler.hpp"
123 #include "jvmci/jvmciRuntime.hpp"
124 #include "logging/logHandle.hpp"
125 #endif
126 #ifdef COMPILER1
127 #include "c1/c1_Compiler.hpp"
128 #endif
129 #ifdef COMPILER2
130 #include "opto/c2compiler.hpp"
131 #include "opto/idealGraphPrinter.hpp"
132 #endif
133 #if INCLUDE_RTM_OPT
134 #include "runtime/rtmLocking.hpp"
135 #endif
136 #if INCLUDE_JFR
137 #include "jfr/jfr.hpp"
138 #endif
139
140 // Initialization after module runtime initialization
141 void universe_post_module_init(); // must happen after call_initPhase2
142
143 #ifdef DTRACE_ENABLED
144
145 // Only bother with this argument setup if dtrace is available
146
147 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
148 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
149
150 #define DTRACE_THREAD_PROBE(probe, javathread) \
151 { \
152 ResourceMark rm(this); \
153 int len = 0; \
154 const char* name = (javathread)->get_thread_name(); \
155 len = strlen(name); \
156 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
157 (char *) name, len, \
158 java_lang_Thread::thread_id((javathread)->threadObj()), \
159 (uintptr_t) (javathread)->osthread()->thread_id(), \
160 java_lang_Thread::is_daemon((javathread)->threadObj())); \
161 }
162
163 #else // ndef DTRACE_ENABLED
164
165 #define DTRACE_THREAD_PROBE(probe, javathread)
166
167 #endif // ndef DTRACE_ENABLED
168
169 #ifndef USE_LIBRARY_BASED_TLS_ONLY
170 // Current thread is maintained as a thread-local variable
171 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
172 #endif
173
174 // ======= Thread ========
175 // Support for forcing alignment of thread objects for biased locking
176 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
177 if (UseBiasedLocking) {
178 const int alignment = markOopDesc::biased_lock_alignment;
179 size_t aligned_size = size + (alignment - sizeof(intptr_t));
180 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
181 : AllocateHeap(aligned_size, flags, CURRENT_PC,
182 AllocFailStrategy::RETURN_NULL);
183 void* aligned_addr = align_up(real_malloc_addr, alignment);
184 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
185 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
186 "JavaThread alignment code overflowed allocated storage");
187 if (aligned_addr != real_malloc_addr) {
188 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
189 p2i(real_malloc_addr),
190 p2i(aligned_addr));
191 }
192 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
193 return aligned_addr;
194 } else {
195 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
196 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
197 }
198 }
199
200 void Thread::operator delete(void* p) {
201 if (UseBiasedLocking) {
202 FreeHeap(((Thread*) p)->_real_malloc_address);
203 } else {
204 FreeHeap(p);
205 }
206 }
207
208 void JavaThread::smr_delete() {
209 if (_on_thread_list) {
210 ThreadsSMRSupport::smr_delete(this);
211 } else {
212 delete this;
213 }
214 }
215
216 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
217 // JavaThread
218
219
220 Thread::Thread() {
221 // stack and get_thread
222 set_stack_base(NULL);
223 set_stack_size(0);
224 set_self_raw_id(0);
225 set_lgrp_id(-1);
226 DEBUG_ONLY(clear_suspendible_thread();)
227
228 // allocated data structures
229 set_osthread(NULL);
230 set_resource_area(new (mtThread)ResourceArea());
231 DEBUG_ONLY(_current_resource_mark = NULL;)
232 set_handle_area(new (mtThread) HandleArea(NULL));
233 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
234 set_active_handles(NULL);
235 set_free_handle_block(NULL);
236 set_last_handle_mark(NULL);
237
238 // This initial value ==> never claimed.
239 _oops_do_parity = 0;
240 _threads_hazard_ptr = NULL;
241 _threads_list_ptr = NULL;
242 _nested_threads_hazard_ptr_cnt = 0;
243 _rcu_counter = 0;
244
245 // the handle mark links itself to last_handle_mark
246 new HandleMark(this);
247
248 // plain initialization
249 debug_only(_owned_locks = NULL;)
250 debug_only(_allow_allocation_count = 0;)
251 NOT_PRODUCT(_allow_safepoint_count = 0;)
252 NOT_PRODUCT(_skip_gcalot = false;)
253 _jvmti_env_iteration_count = 0;
254 set_allocated_bytes(0);
255 _vm_operation_started_count = 0;
256 _vm_operation_completed_count = 0;
257 _current_pending_monitor = NULL;
258 _current_pending_monitor_is_from_java = true;
259 _current_waiting_monitor = NULL;
260 _num_nested_signal = 0;
261 omFreeList = NULL;
262 omFreeCount = 0;
263 omFreeProvision = 32;
264 omInUseList = NULL;
265 omInUseCount = 0;
266
267 #ifdef ASSERT
268 _visited_for_critical_count = false;
269 #endif
270
271 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
272 Monitor::_safepoint_check_sometimes);
273 _suspend_flags = 0;
274
275 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
276 _hashStateX = os::random();
277 _hashStateY = 842502087;
278 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
279 _hashStateW = 273326509;
280
281 _OnTrap = 0;
282 _Stalled = 0;
283 _TypeTag = 0x2BAD;
284
285 // Many of the following fields are effectively final - immutable
286 // Note that nascent threads can't use the Native Monitor-Mutex
287 // construct until the _MutexEvent is initialized ...
288 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
289 // we might instead use a stack of ParkEvents that we could provision on-demand.
290 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
291 // and ::Release()
292 _ParkEvent = ParkEvent::Allocate(this);
293 _SleepEvent = ParkEvent::Allocate(this);
294 _MutexEvent = ParkEvent::Allocate(this);
295 _MuxEvent = ParkEvent::Allocate(this);
296
297 #ifdef CHECK_UNHANDLED_OOPS
298 if (CheckUnhandledOops) {
299 _unhandled_oops = new UnhandledOops(this);
300 }
301 #endif // CHECK_UNHANDLED_OOPS
302 #ifdef ASSERT
303 if (UseBiasedLocking) {
304 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
305 assert(this == _real_malloc_address ||
306 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
307 "bug in forced alignment of thread objects");
308 }
309 #endif // ASSERT
310
311 // Notify the barrier set that a thread is being created. Note that some
312 // threads are created before a barrier set is available. The call to
313 // BarrierSet::on_thread_create() for these threads is therefore deferred
314 // to BarrierSet::set_barrier_set().
315 BarrierSet* const barrier_set = BarrierSet::barrier_set();
316 if (barrier_set != NULL) {
317 barrier_set->on_thread_create(this);
318 } else {
319 DEBUG_ONLY(Threads::inc_threads_before_barrier_set();)
320 }
321 }
322
323 void Thread::initialize_thread_current() {
324 #ifndef USE_LIBRARY_BASED_TLS_ONLY
325 assert(_thr_current == NULL, "Thread::current already initialized");
326 _thr_current = this;
327 #endif
328 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
329 ThreadLocalStorage::set_thread(this);
330 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
331 }
332
333 void Thread::clear_thread_current() {
334 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
335 #ifndef USE_LIBRARY_BASED_TLS_ONLY
336 _thr_current = NULL;
337 #endif
338 ThreadLocalStorage::set_thread(NULL);
339 }
340
341 void Thread::record_stack_base_and_size() {
342 set_stack_base(os::current_stack_base());
343 set_stack_size(os::current_stack_size());
344 // CR 7190089: on Solaris, primordial thread's stack is adjusted
345 // in initialize_thread(). Without the adjustment, stack size is
346 // incorrect if stack is set to unlimited (ulimit -s unlimited).
347 // So far, only Solaris has real implementation of initialize_thread().
348 //
349 // set up any platform-specific state.
350 os::initialize_thread(this);
351
352 // Set stack limits after thread is initialized.
353 if (is_Java_thread()) {
354 ((JavaThread*) this)->set_stack_overflow_limit();
355 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
356 }
357 #if INCLUDE_NMT
358 // record thread's native stack, stack grows downward
359 MemTracker::record_thread_stack(stack_end(), stack_size());
360 #endif // INCLUDE_NMT
361 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
362 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
363 os::current_thread_id(), p2i(stack_base() - stack_size()),
364 p2i(stack_base()), stack_size()/1024);
365 }
366
367
368 Thread::~Thread() {
369 JFR_ONLY(Jfr::on_thread_destruct(this);)
370
371 // Notify the barrier set that a thread is being destroyed. Note that a barrier
372 // set might not be available if we encountered errors during bootstrapping.
373 BarrierSet* const barrier_set = BarrierSet::barrier_set();
374 if (barrier_set != NULL) {
375 barrier_set->on_thread_destroy(this);
376 }
377
378
379 // stack_base can be NULL if the thread is never started or exited before
380 // record_stack_base_and_size called. Although, we would like to ensure
381 // that all started threads do call record_stack_base_and_size(), there is
382 // not proper way to enforce that.
383 #if INCLUDE_NMT
384 if (_stack_base != NULL) {
385 MemTracker::release_thread_stack(stack_end(), stack_size());
386 #ifdef ASSERT
387 set_stack_base(NULL);
388 #endif
389 }
390 #endif // INCLUDE_NMT
391
392 // deallocate data structures
393 delete resource_area();
394 // since the handle marks are using the handle area, we have to deallocated the root
395 // handle mark before deallocating the thread's handle area,
396 assert(last_handle_mark() != NULL, "check we have an element");
397 delete last_handle_mark();
398 assert(last_handle_mark() == NULL, "check we have reached the end");
399
400 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
401 // We NULL out the fields for good hygiene.
402 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
403 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
404 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
405 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
406
407 delete handle_area();
408 delete metadata_handles();
409
410 // SR_handler uses this as a termination indicator -
411 // needs to happen before os::free_thread()
412 delete _SR_lock;
413 _SR_lock = NULL;
414
415 // osthread() can be NULL, if creation of thread failed.
416 if (osthread() != NULL) os::free_thread(osthread());
417
418 // clear Thread::current if thread is deleting itself.
419 // Needed to ensure JNI correctly detects non-attached threads.
420 if (this == Thread::current()) {
421 clear_thread_current();
422 }
423
424 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
425 }
426
427 // NOTE: dummy function for assertion purpose.
428 void Thread::run() {
429 ShouldNotReachHere();
430 }
431
432 #ifdef ASSERT
433 // A JavaThread is considered "dangling" if it is not the current
434 // thread, has been added the Threads list, the system is not at a
435 // safepoint and the Thread is not "protected".
436 //
437 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
438 assert(!thread->is_Java_thread() || Thread::current() == thread ||
439 !((JavaThread *) thread)->on_thread_list() ||
440 SafepointSynchronize::is_at_safepoint() ||
441 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
442 "possibility of dangling Thread pointer");
443 }
444 #endif
445
446 ThreadPriority Thread::get_priority(const Thread* const thread) {
447 ThreadPriority priority;
448 // Can return an error!
449 (void)os::get_priority(thread, priority);
450 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
451 return priority;
452 }
453
454 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
455 debug_only(check_for_dangling_thread_pointer(thread);)
456 // Can return an error!
457 (void)os::set_priority(thread, priority);
458 }
459
460
461 void Thread::start(Thread* thread) {
462 // Start is different from resume in that its safety is guaranteed by context or
463 // being called from a Java method synchronized on the Thread object.
464 if (!DisableStartThread) {
465 if (thread->is_Java_thread()) {
466 // Initialize the thread state to RUNNABLE before starting this thread.
467 // Can not set it after the thread started because we do not know the
468 // exact thread state at that time. It could be in MONITOR_WAIT or
469 // in SLEEPING or some other state.
470 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
471 java_lang_Thread::RUNNABLE);
472 }
473 os::start_thread(thread);
474 }
475 }
476
477 // Enqueue a VM_Operation to do the job for us - sometime later
478 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
479 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
480 VMThread::execute(vm_stop);
481 }
482
483
484 // Check if an external suspend request has completed (or has been
485 // cancelled). Returns true if the thread is externally suspended and
486 // false otherwise.
487 //
488 // The bits parameter returns information about the code path through
489 // the routine. Useful for debugging:
490 //
491 // set in is_ext_suspend_completed():
492 // 0x00000001 - routine was entered
493 // 0x00000010 - routine return false at end
494 // 0x00000100 - thread exited (return false)
495 // 0x00000200 - suspend request cancelled (return false)
496 // 0x00000400 - thread suspended (return true)
497 // 0x00001000 - thread is in a suspend equivalent state (return true)
498 // 0x00002000 - thread is native and walkable (return true)
499 // 0x00004000 - thread is native_trans and walkable (needed retry)
500 //
501 // set in wait_for_ext_suspend_completion():
502 // 0x00010000 - routine was entered
503 // 0x00020000 - suspend request cancelled before loop (return false)
504 // 0x00040000 - thread suspended before loop (return true)
505 // 0x00080000 - suspend request cancelled in loop (return false)
506 // 0x00100000 - thread suspended in loop (return true)
507 // 0x00200000 - suspend not completed during retry loop (return false)
508
509 // Helper class for tracing suspend wait debug bits.
510 //
511 // 0x00000100 indicates that the target thread exited before it could
512 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
513 // 0x00080000 each indicate a cancelled suspend request so they don't
514 // count as wait failures either.
515 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
516
517 class TraceSuspendDebugBits : public StackObj {
518 private:
519 JavaThread * jt;
520 bool is_wait;
521 bool called_by_wait; // meaningful when !is_wait
522 uint32_t * bits;
523
524 public:
525 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
526 uint32_t *_bits) {
527 jt = _jt;
528 is_wait = _is_wait;
529 called_by_wait = _called_by_wait;
530 bits = _bits;
531 }
532
533 ~TraceSuspendDebugBits() {
534 if (!is_wait) {
535 #if 1
536 // By default, don't trace bits for is_ext_suspend_completed() calls.
537 // That trace is very chatty.
538 return;
539 #else
540 if (!called_by_wait) {
541 // If tracing for is_ext_suspend_completed() is enabled, then only
542 // trace calls to it from wait_for_ext_suspend_completion()
543 return;
544 }
545 #endif
546 }
547
548 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
549 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
550 MutexLocker ml(Threads_lock); // needed for get_thread_name()
551 ResourceMark rm;
552
553 tty->print_cr(
554 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
555 jt->get_thread_name(), *bits);
556
557 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
558 }
559 }
560 }
561 };
562 #undef DEBUG_FALSE_BITS
563
564
565 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
566 uint32_t *bits) {
567 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
568
569 bool did_trans_retry = false; // only do thread_in_native_trans retry once
570 bool do_trans_retry; // flag to force the retry
571
572 *bits |= 0x00000001;
573
574 do {
575 do_trans_retry = false;
576
577 if (is_exiting()) {
578 // Thread is in the process of exiting. This is always checked
579 // first to reduce the risk of dereferencing a freed JavaThread.
580 *bits |= 0x00000100;
581 return false;
582 }
583
584 if (!is_external_suspend()) {
585 // Suspend request is cancelled. This is always checked before
586 // is_ext_suspended() to reduce the risk of a rogue resume
587 // confusing the thread that made the suspend request.
588 *bits |= 0x00000200;
589 return false;
590 }
591
592 if (is_ext_suspended()) {
593 // thread is suspended
594 *bits |= 0x00000400;
595 return true;
596 }
597
598 // Now that we no longer do hard suspends of threads running
599 // native code, the target thread can be changing thread state
600 // while we are in this routine:
601 //
602 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
603 //
604 // We save a copy of the thread state as observed at this moment
605 // and make our decision about suspend completeness based on the
606 // copy. This closes the race where the thread state is seen as
607 // _thread_in_native_trans in the if-thread_blocked check, but is
608 // seen as _thread_blocked in if-thread_in_native_trans check.
609 JavaThreadState save_state = thread_state();
610
611 if (save_state == _thread_blocked && is_suspend_equivalent()) {
612 // If the thread's state is _thread_blocked and this blocking
613 // condition is known to be equivalent to a suspend, then we can
614 // consider the thread to be externally suspended. This means that
615 // the code that sets _thread_blocked has been modified to do
616 // self-suspension if the blocking condition releases. We also
617 // used to check for CONDVAR_WAIT here, but that is now covered by
618 // the _thread_blocked with self-suspension check.
619 //
620 // Return true since we wouldn't be here unless there was still an
621 // external suspend request.
622 *bits |= 0x00001000;
623 return true;
624 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
625 // Threads running native code will self-suspend on native==>VM/Java
626 // transitions. If its stack is walkable (should always be the case
627 // unless this function is called before the actual java_suspend()
628 // call), then the wait is done.
629 *bits |= 0x00002000;
630 return true;
631 } else if (!called_by_wait && !did_trans_retry &&
632 save_state == _thread_in_native_trans &&
633 frame_anchor()->walkable()) {
634 // The thread is transitioning from thread_in_native to another
635 // thread state. check_safepoint_and_suspend_for_native_trans()
636 // will force the thread to self-suspend. If it hasn't gotten
637 // there yet we may have caught the thread in-between the native
638 // code check above and the self-suspend. Lucky us. If we were
639 // called by wait_for_ext_suspend_completion(), then it
640 // will be doing the retries so we don't have to.
641 //
642 // Since we use the saved thread state in the if-statement above,
643 // there is a chance that the thread has already transitioned to
644 // _thread_blocked by the time we get here. In that case, we will
645 // make a single unnecessary pass through the logic below. This
646 // doesn't hurt anything since we still do the trans retry.
647
648 *bits |= 0x00004000;
649
650 // Once the thread leaves thread_in_native_trans for another
651 // thread state, we break out of this retry loop. We shouldn't
652 // need this flag to prevent us from getting back here, but
653 // sometimes paranoia is good.
654 did_trans_retry = true;
655
656 // We wait for the thread to transition to a more usable state.
657 for (int i = 1; i <= SuspendRetryCount; i++) {
658 // We used to do an "os::yield_all(i)" call here with the intention
659 // that yielding would increase on each retry. However, the parameter
660 // is ignored on Linux which means the yield didn't scale up. Waiting
661 // on the SR_lock below provides a much more predictable scale up for
662 // the delay. It also provides a simple/direct point to check for any
663 // safepoint requests from the VMThread
664
665 // temporarily drops SR_lock while doing wait with safepoint check
666 // (if we're a JavaThread - the WatcherThread can also call this)
667 // and increase delay with each retry
668 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
669
670 // check the actual thread state instead of what we saved above
671 if (thread_state() != _thread_in_native_trans) {
672 // the thread has transitioned to another thread state so
673 // try all the checks (except this one) one more time.
674 do_trans_retry = true;
675 break;
676 }
677 } // end retry loop
678
679
680 }
681 } while (do_trans_retry);
682
683 *bits |= 0x00000010;
684 return false;
685 }
686
687 // Wait for an external suspend request to complete (or be cancelled).
688 // Returns true if the thread is externally suspended and false otherwise.
689 //
690 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
691 uint32_t *bits) {
692 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
693 false /* !called_by_wait */, bits);
694
695 // local flag copies to minimize SR_lock hold time
696 bool is_suspended;
697 bool pending;
698 uint32_t reset_bits;
699
700 // set a marker so is_ext_suspend_completed() knows we are the caller
701 *bits |= 0x00010000;
702
703 // We use reset_bits to reinitialize the bits value at the top of
704 // each retry loop. This allows the caller to make use of any
705 // unused bits for their own marking purposes.
706 reset_bits = *bits;
707
708 {
709 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
710 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
711 delay, bits);
712 pending = is_external_suspend();
713 }
714 // must release SR_lock to allow suspension to complete
715
716 if (!pending) {
717 // A cancelled suspend request is the only false return from
718 // is_ext_suspend_completed() that keeps us from entering the
719 // retry loop.
720 *bits |= 0x00020000;
721 return false;
722 }
723
724 if (is_suspended) {
725 *bits |= 0x00040000;
726 return true;
727 }
728
729 for (int i = 1; i <= retries; i++) {
730 *bits = reset_bits; // reinit to only track last retry
731
732 // We used to do an "os::yield_all(i)" call here with the intention
733 // that yielding would increase on each retry. However, the parameter
734 // is ignored on Linux which means the yield didn't scale up. Waiting
735 // on the SR_lock below provides a much more predictable scale up for
736 // the delay. It also provides a simple/direct point to check for any
737 // safepoint requests from the VMThread
738
739 {
740 MutexLocker ml(SR_lock());
741 // wait with safepoint check (if we're a JavaThread - the WatcherThread
742 // can also call this) and increase delay with each retry
743 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
744
745 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
746 delay, bits);
747
748 // It is possible for the external suspend request to be cancelled
749 // (by a resume) before the actual suspend operation is completed.
750 // Refresh our local copy to see if we still need to wait.
751 pending = is_external_suspend();
752 }
753
754 if (!pending) {
755 // A cancelled suspend request is the only false return from
756 // is_ext_suspend_completed() that keeps us from staying in the
757 // retry loop.
758 *bits |= 0x00080000;
759 return false;
760 }
761
762 if (is_suspended) {
763 *bits |= 0x00100000;
764 return true;
765 }
766 } // end retry loop
767
768 // thread did not suspend after all our retries
769 *bits |= 0x00200000;
770 return false;
771 }
772
773 // Called from API entry points which perform stack walking. If the
774 // associated JavaThread is the current thread, then wait_for_suspend
775 // is not used. Otherwise, it determines if we should wait for the
776 // "other" thread to complete external suspension. (NOTE: in future
777 // releases the suspension mechanism should be reimplemented so this
778 // is not necessary.)
779 //
780 bool
781 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
782 if (this != JavaThread::current()) {
783 // "other" threads require special handling.
784 if (wait_for_suspend) {
785 // We are allowed to wait for the external suspend to complete
786 // so give the other thread a chance to get suspended.
787 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
788 SuspendRetryDelay, bits)) {
789 // Didn't make it so let the caller know.
790 return false;
791 }
792 }
793 // We aren't allowed to wait for the external suspend to complete
794 // so if the other thread isn't externally suspended we need to
795 // let the caller know.
796 else if (!is_ext_suspend_completed_with_lock(bits)) {
797 return false;
798 }
799 }
800
801 return true;
802 }
803
804 #ifndef PRODUCT
805 void JavaThread::record_jump(address target, address instr, const char* file,
806 int line) {
807
808 // This should not need to be atomic as the only way for simultaneous
809 // updates is via interrupts. Even then this should be rare or non-existent
810 // and we don't care that much anyway.
811
812 int index = _jmp_ring_index;
813 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
814 _jmp_ring[index]._target = (intptr_t) target;
815 _jmp_ring[index]._instruction = (intptr_t) instr;
816 _jmp_ring[index]._file = file;
817 _jmp_ring[index]._line = line;
818 }
819 #endif // PRODUCT
820
821 void Thread::interrupt(Thread* thread) {
822 debug_only(check_for_dangling_thread_pointer(thread);)
823 os::interrupt(thread);
824 }
825
826 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
827 debug_only(check_for_dangling_thread_pointer(thread);)
828 // Note: If clear_interrupted==false, this simply fetches and
829 // returns the value of the field osthread()->interrupted().
830 return os::is_interrupted(thread, clear_interrupted);
831 }
832
833
834 // GC Support
835 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
836 int thread_parity = _oops_do_parity;
837 if (thread_parity != strong_roots_parity) {
838 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
839 if (res == thread_parity) {
840 return true;
841 } else {
842 guarantee(res == strong_roots_parity, "Or else what?");
843 return false;
844 }
845 }
846 return false;
847 }
848
849 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
850 active_handles()->oops_do(f);
851 // Do oop for ThreadShadow
852 f->do_oop((oop*)&_pending_exception);
853 handle_area()->oops_do(f);
854
855 if (MonitorInUseLists) {
856 // When using thread local monitor lists, we scan them here,
857 // and the remaining global monitors in ObjectSynchronizer::oops_do().
858 ObjectSynchronizer::thread_local_used_oops_do(this, f);
859 }
860 }
861
862 void Thread::metadata_handles_do(void f(Metadata*)) {
863 // Only walk the Handles in Thread.
864 if (metadata_handles() != NULL) {
865 for (int i = 0; i< metadata_handles()->length(); i++) {
866 f(metadata_handles()->at(i));
867 }
868 }
869 }
870
871 void Thread::print_on(outputStream* st, bool print_extended_info) const {
872 // get_priority assumes osthread initialized
873 if (osthread() != NULL) {
874 int os_prio;
875 if (os::get_native_priority(this, &os_prio) == OS_OK) {
876 st->print("os_prio=%d ", os_prio);
877 }
878
879 st->print("cpu=%.2fms ",
880 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
881 );
882 st->print("elapsed=%.2fs ",
883 _statistical_info.getElapsedTime() / 1000.0
884 );
885 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
886 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
887 st->print("allocated=" SIZE_FORMAT "%s ",
888 byte_size_in_proper_unit(allocated_bytes),
889 proper_unit_for_byte_size(allocated_bytes)
890 );
891 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
892 }
893
894 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
895 osthread()->print_on(st);
896 }
897 ThreadsSMRSupport::print_info_on(this, st);
898 st->print(" ");
899 debug_only(if (WizardMode) print_owned_locks_on(st);)
900 }
901
902 // Thread::print_on_error() is called by fatal error handler. Don't use
903 // any lock or allocate memory.
904 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
905 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
906
907 if (is_VM_thread()) { st->print("VMThread"); }
908 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
909 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
910 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
911 else { st->print("Thread"); }
912
913 if (is_Named_thread()) {
914 st->print(" \"%s\"", name());
915 }
916
917 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
918 p2i(stack_end()), p2i(stack_base()));
919
920 if (osthread()) {
921 st->print(" [id=%d]", osthread()->thread_id());
922 }
923
924 ThreadsSMRSupport::print_info_on(this, st);
925 }
926
927 void Thread::print_value_on(outputStream* st) const {
928 if (is_Named_thread()) {
929 st->print(" \"%s\" ", name());
930 }
931 st->print(INTPTR_FORMAT, p2i(this)); // print address
932 }
933
934 #ifdef ASSERT
935 void Thread::print_owned_locks_on(outputStream* st) const {
936 Monitor *cur = _owned_locks;
937 if (cur == NULL) {
938 st->print(" (no locks) ");
939 } else {
940 st->print_cr(" Locks owned:");
941 while (cur) {
942 cur->print_on(st);
943 cur = cur->next();
944 }
945 }
946 }
947
948 static int ref_use_count = 0;
949
950 bool Thread::owns_locks_but_compiled_lock() const {
951 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
952 if (cur != Compile_lock) return true;
953 }
954 return false;
955 }
956
957
958 #endif
959
960 #ifndef PRODUCT
961
962 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
963 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
964 // no locks which allow_vm_block's are held
965 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
966 // Check if current thread is allowed to block at a safepoint
967 if (!(_allow_safepoint_count == 0)) {
968 fatal("Possible safepoint reached by thread that does not allow it");
969 }
970 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
971 fatal("LEAF method calling lock?");
972 }
973
974 #ifdef ASSERT
975 if (potential_vm_operation && is_Java_thread()
976 && !Universe::is_bootstrapping()) {
977 // Make sure we do not hold any locks that the VM thread also uses.
978 // This could potentially lead to deadlocks
979 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
980 // Threads_lock is special, since the safepoint synchronization will not start before this is
981 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
982 // since it is used to transfer control between JavaThreads and the VMThread
983 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
984 if ((cur->allow_vm_block() &&
985 cur != Threads_lock &&
986 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
987 cur != VMOperationRequest_lock &&
988 cur != VMOperationQueue_lock) ||
989 cur->rank() == Mutex::special) {
990 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
991 }
992 }
993 }
994
995 if (GCALotAtAllSafepoints) {
996 // We could enter a safepoint here and thus have a gc
997 InterfaceSupport::check_gc_alot();
998 }
999 #endif
1000 }
1001 #endif
1002
1003 bool Thread::is_in_stack(address adr) const {
1004 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1005 address end = os::current_stack_pointer();
1006 // Allow non Java threads to call this without stack_base
1007 if (_stack_base == NULL) return true;
1008 if (stack_base() >= adr && adr >= end) return true;
1009
1010 return false;
1011 }
1012
1013 bool Thread::is_in_usable_stack(address adr) const {
1014 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1015 size_t usable_stack_size = _stack_size - stack_guard_size;
1016
1017 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1018 }
1019
1020
1021 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1022 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1023 // used for compilation in the future. If that change is made, the need for these methods
1024 // should be revisited, and they should be removed if possible.
1025
1026 bool Thread::is_lock_owned(address adr) const {
1027 return on_local_stack(adr);
1028 }
1029
1030 bool Thread::set_as_starting_thread() {
1031 // NOTE: this must be called inside the main thread.
1032 return os::create_main_thread((JavaThread*)this);
1033 }
1034
1035 static void initialize_class(Symbol* class_name, TRAPS) {
1036 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1037 InstanceKlass::cast(klass)->initialize(CHECK);
1038 }
1039
1040
1041 // Creates the initial ThreadGroup
1042 static Handle create_initial_thread_group(TRAPS) {
1043 Handle system_instance = JavaCalls::construct_new_instance(
1044 SystemDictionary::ThreadGroup_klass(),
1045 vmSymbols::void_method_signature(),
1046 CHECK_NH);
1047 Universe::set_system_thread_group(system_instance());
1048
1049 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1050 Handle main_instance = JavaCalls::construct_new_instance(
1051 SystemDictionary::ThreadGroup_klass(),
1052 vmSymbols::threadgroup_string_void_signature(),
1053 system_instance,
1054 string,
1055 CHECK_NH);
1056 return main_instance;
1057 }
1058
1059 // Creates the initial Thread
1060 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1061 TRAPS) {
1062 InstanceKlass* ik = SystemDictionary::Thread_klass();
1063 assert(ik->is_initialized(), "must be");
1064 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1065
1066 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1067 // constructor calls Thread.current(), which must be set here for the
1068 // initial thread.
1069 java_lang_Thread::set_thread(thread_oop(), thread);
1070 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1071 thread->set_threadObj(thread_oop());
1072
1073 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1074
1075 JavaValue result(T_VOID);
1076 JavaCalls::call_special(&result, thread_oop,
1077 ik,
1078 vmSymbols::object_initializer_name(),
1079 vmSymbols::threadgroup_string_void_signature(),
1080 thread_group,
1081 string,
1082 CHECK_NULL);
1083 return thread_oop();
1084 }
1085
1086 char java_runtime_name[128] = "";
1087 char java_runtime_version[128] = "";
1088
1089 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1090 static const char* get_java_runtime_name(TRAPS) {
1091 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1092 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1093 fieldDescriptor fd;
1094 bool found = k != NULL &&
1095 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1096 vmSymbols::string_signature(), &fd);
1097 if (found) {
1098 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1099 if (name_oop == NULL) {
1100 return NULL;
1101 }
1102 const char* name = java_lang_String::as_utf8_string(name_oop,
1103 java_runtime_name,
1104 sizeof(java_runtime_name));
1105 return name;
1106 } else {
1107 return NULL;
1108 }
1109 }
1110
1111 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1112 static const char* get_java_runtime_version(TRAPS) {
1113 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1114 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1115 fieldDescriptor fd;
1116 bool found = k != NULL &&
1117 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1118 vmSymbols::string_signature(), &fd);
1119 if (found) {
1120 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1121 if (name_oop == NULL) {
1122 return NULL;
1123 }
1124 const char* name = java_lang_String::as_utf8_string(name_oop,
1125 java_runtime_version,
1126 sizeof(java_runtime_version));
1127 return name;
1128 } else {
1129 return NULL;
1130 }
1131 }
1132
1133 // General purpose hook into Java code, run once when the VM is initialized.
1134 // The Java library method itself may be changed independently from the VM.
1135 static void call_postVMInitHook(TRAPS) {
1136 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1137 if (klass != NULL) {
1138 JavaValue result(T_VOID);
1139 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1140 vmSymbols::void_method_signature(),
1141 CHECK);
1142 }
1143 }
1144
1145 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1146 bool daemon, TRAPS) {
1147 assert(thread_group.not_null(), "thread group should be specified");
1148 assert(threadObj() == NULL, "should only create Java thread object once");
1149
1150 InstanceKlass* ik = SystemDictionary::Thread_klass();
1151 assert(ik->is_initialized(), "must be");
1152 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1153
1154 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1155 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1156 // constructor calls Thread.current(), which must be set here.
1157 java_lang_Thread::set_thread(thread_oop(), this);
1158 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1159 set_threadObj(thread_oop());
1160
1161 JavaValue result(T_VOID);
1162 if (thread_name != NULL) {
1163 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1164 // Thread gets assigned specified name and null target
1165 JavaCalls::call_special(&result,
1166 thread_oop,
1167 ik,
1168 vmSymbols::object_initializer_name(),
1169 vmSymbols::threadgroup_string_void_signature(),
1170 thread_group,
1171 name,
1172 THREAD);
1173 } else {
1174 // Thread gets assigned name "Thread-nnn" and null target
1175 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1176 JavaCalls::call_special(&result,
1177 thread_oop,
1178 ik,
1179 vmSymbols::object_initializer_name(),
1180 vmSymbols::threadgroup_runnable_void_signature(),
1181 thread_group,
1182 Handle(),
1183 THREAD);
1184 }
1185
1186
1187 if (daemon) {
1188 java_lang_Thread::set_daemon(thread_oop());
1189 }
1190
1191 if (HAS_PENDING_EXCEPTION) {
1192 return;
1193 }
1194
1195 Klass* group = SystemDictionary::ThreadGroup_klass();
1196 Handle threadObj(THREAD, this->threadObj());
1197
1198 JavaCalls::call_special(&result,
1199 thread_group,
1200 group,
1201 vmSymbols::add_method_name(),
1202 vmSymbols::thread_void_signature(),
1203 threadObj, // Arg 1
1204 THREAD);
1205 }
1206
1207 // List of all NonJavaThreads and safe iteration over that list.
1208
1209 class NonJavaThread::List {
1210 public:
1211 NonJavaThread* volatile _head;
1212 SingleWriterSynchronizer _protect;
1213
1214 List() : _head(NULL), _protect() {}
1215 };
1216
1217 NonJavaThread::List NonJavaThread::_the_list;
1218
1219 NonJavaThread::Iterator::Iterator() :
1220 _protect_enter(_the_list._protect.enter()),
1221 _current(OrderAccess::load_acquire(&_the_list._head))
1222 {}
1223
1224 NonJavaThread::Iterator::~Iterator() {
1225 _the_list._protect.exit(_protect_enter);
1226 }
1227
1228 void NonJavaThread::Iterator::step() {
1229 assert(!end(), "precondition");
1230 _current = OrderAccess::load_acquire(&_current->_next);
1231 }
1232
1233 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1234 // Add this thread to _the_list.
1235 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1236 _next = _the_list._head;
1237 OrderAccess::release_store(&_the_list._head, this);
1238 }
1239
1240 NonJavaThread::~NonJavaThread() {
1241 // Remove this thread from _the_list.
1242 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1243 NonJavaThread* volatile* p = &_the_list._head;
1244 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1245 if (t == this) {
1246 *p = this->_next;
1247 // Wait for any in-progress iterators.
1248 _the_list._protect.synchronize();
1249 break;
1250 }
1251 }
1252 }
1253
1254 // NamedThread -- non-JavaThread subclasses with multiple
1255 // uniquely named instances should derive from this.
1256 NamedThread::NamedThread() :
1257 NonJavaThread(),
1258 _name(NULL),
1259 _processed_thread(NULL),
1260 _gc_id(GCId::undefined())
1261 {}
1262
1263 NamedThread::~NamedThread() {
1264 if (_name != NULL) {
1265 FREE_C_HEAP_ARRAY(char, _name);
1266 _name = NULL;
1267 }
1268 }
1269
1270 void NamedThread::set_name(const char* format, ...) {
1271 guarantee(_name == NULL, "Only get to set name once.");
1272 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1273 guarantee(_name != NULL, "alloc failure");
1274 va_list ap;
1275 va_start(ap, format);
1276 jio_vsnprintf(_name, max_name_len, format, ap);
1277 va_end(ap);
1278 }
1279
1280 void NamedThread::initialize_named_thread() {
1281 set_native_thread_name(name());
1282 }
1283
1284 void NamedThread::print_on(outputStream* st) const {
1285 st->print("\"%s\" ", name());
1286 Thread::print_on(st);
1287 st->cr();
1288 }
1289
1290
1291 // ======= WatcherThread ========
1292
1293 // The watcher thread exists to simulate timer interrupts. It should
1294 // be replaced by an abstraction over whatever native support for
1295 // timer interrupts exists on the platform.
1296
1297 WatcherThread* WatcherThread::_watcher_thread = NULL;
1298 bool WatcherThread::_startable = false;
1299 volatile bool WatcherThread::_should_terminate = false;
1300
1301 WatcherThread::WatcherThread() : NonJavaThread() {
1302 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1303 if (os::create_thread(this, os::watcher_thread)) {
1304 _watcher_thread = this;
1305
1306 // Set the watcher thread to the highest OS priority which should not be
1307 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1308 // is created. The only normal thread using this priority is the reference
1309 // handler thread, which runs for very short intervals only.
1310 // If the VMThread's priority is not lower than the WatcherThread profiling
1311 // will be inaccurate.
1312 os::set_priority(this, MaxPriority);
1313 if (!DisableStartThread) {
1314 os::start_thread(this);
1315 }
1316 }
1317 }
1318
1319 int WatcherThread::sleep() const {
1320 // The WatcherThread does not participate in the safepoint protocol
1321 // for the PeriodicTask_lock because it is not a JavaThread.
1322 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1323
1324 if (_should_terminate) {
1325 // check for termination before we do any housekeeping or wait
1326 return 0; // we did not sleep.
1327 }
1328
1329 // remaining will be zero if there are no tasks,
1330 // causing the WatcherThread to sleep until a task is
1331 // enrolled
1332 int remaining = PeriodicTask::time_to_wait();
1333 int time_slept = 0;
1334
1335 // we expect this to timeout - we only ever get unparked when
1336 // we should terminate or when a new task has been enrolled
1337 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1338
1339 jlong time_before_loop = os::javaTimeNanos();
1340
1341 while (true) {
1342 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1343 remaining);
1344 jlong now = os::javaTimeNanos();
1345
1346 if (remaining == 0) {
1347 // if we didn't have any tasks we could have waited for a long time
1348 // consider the time_slept zero and reset time_before_loop
1349 time_slept = 0;
1350 time_before_loop = now;
1351 } else {
1352 // need to recalculate since we might have new tasks in _tasks
1353 time_slept = (int) ((now - time_before_loop) / 1000000);
1354 }
1355
1356 // Change to task list or spurious wakeup of some kind
1357 if (timedout || _should_terminate) {
1358 break;
1359 }
1360
1361 remaining = PeriodicTask::time_to_wait();
1362 if (remaining == 0) {
1363 // Last task was just disenrolled so loop around and wait until
1364 // another task gets enrolled
1365 continue;
1366 }
1367
1368 remaining -= time_slept;
1369 if (remaining <= 0) {
1370 break;
1371 }
1372 }
1373
1374 return time_slept;
1375 }
1376
1377 void WatcherThread::run() {
1378 assert(this == watcher_thread(), "just checking");
1379
1380 this->record_stack_base_and_size();
1381 this->set_native_thread_name(this->name());
1382 this->set_active_handles(JNIHandleBlock::allocate_block());
1383 while (true) {
1384 assert(watcher_thread() == Thread::current(), "thread consistency check");
1385 assert(watcher_thread() == this, "thread consistency check");
1386
1387 // Calculate how long it'll be until the next PeriodicTask work
1388 // should be done, and sleep that amount of time.
1389 int time_waited = sleep();
1390
1391 if (VMError::is_error_reported()) {
1392 // A fatal error has happened, the error handler(VMError::report_and_die)
1393 // should abort JVM after creating an error log file. However in some
1394 // rare cases, the error handler itself might deadlock. Here periodically
1395 // check for error reporting timeouts, and if it happens, just proceed to
1396 // abort the VM.
1397
1398 // This code is in WatcherThread because WatcherThread wakes up
1399 // periodically so the fatal error handler doesn't need to do anything;
1400 // also because the WatcherThread is less likely to crash than other
1401 // threads.
1402
1403 for (;;) {
1404 // Note: we use naked sleep in this loop because we want to avoid using
1405 // any kind of VM infrastructure which may be broken at this point.
1406 if (VMError::check_timeout()) {
1407 // We hit error reporting timeout. Error reporting was interrupted and
1408 // will be wrapping things up now (closing files etc). Give it some more
1409 // time, then quit the VM.
1410 os::naked_short_sleep(200);
1411 // Print a message to stderr.
1412 fdStream err(defaultStream::output_fd());
1413 err.print_raw_cr("# [ timer expired, abort... ]");
1414 // skip atexit/vm_exit/vm_abort hooks
1415 os::die();
1416 }
1417
1418 // Wait a second, then recheck for timeout.
1419 os::naked_short_sleep(999);
1420 }
1421 }
1422
1423 if (_should_terminate) {
1424 // check for termination before posting the next tick
1425 break;
1426 }
1427
1428 PeriodicTask::real_time_tick(time_waited);
1429 }
1430
1431 // Signal that it is terminated
1432 {
1433 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1434 _watcher_thread = NULL;
1435 Terminator_lock->notify();
1436 }
1437 }
1438
1439 void WatcherThread::start() {
1440 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1441
1442 if (watcher_thread() == NULL && _startable) {
1443 _should_terminate = false;
1444 // Create the single instance of WatcherThread
1445 new WatcherThread();
1446 }
1447 }
1448
1449 void WatcherThread::make_startable() {
1450 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1451 _startable = true;
1452 }
1453
1454 void WatcherThread::stop() {
1455 {
1456 // Follow normal safepoint aware lock enter protocol since the
1457 // WatcherThread is stopped by another JavaThread.
1458 MutexLocker ml(PeriodicTask_lock);
1459 _should_terminate = true;
1460
1461 WatcherThread* watcher = watcher_thread();
1462 if (watcher != NULL) {
1463 // unpark the WatcherThread so it can see that it should terminate
1464 watcher->unpark();
1465 }
1466 }
1467
1468 MutexLocker mu(Terminator_lock);
1469
1470 while (watcher_thread() != NULL) {
1471 // This wait should make safepoint checks, wait without a timeout,
1472 // and wait as a suspend-equivalent condition.
1473 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1474 Mutex::_as_suspend_equivalent_flag);
1475 }
1476 }
1477
1478 void WatcherThread::unpark() {
1479 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1480 PeriodicTask_lock->notify();
1481 }
1482
1483 void WatcherThread::print_on(outputStream* st) const {
1484 st->print("\"%s\" ", name());
1485 Thread::print_on(st);
1486 st->cr();
1487 }
1488
1489 // ======= JavaThread ========
1490
1491 #if INCLUDE_JVMCI
1492
1493 jlong* JavaThread::_jvmci_old_thread_counters;
1494
1495 bool jvmci_counters_include(JavaThread* thread) {
1496 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1497 }
1498
1499 void JavaThread::collect_counters(typeArrayOop array) {
1500 if (JVMCICounterSize > 0) {
1501 JavaThreadIteratorWithHandle jtiwh;
1502 for (int i = 0; i < array->length(); i++) {
1503 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1504 }
1505 for (; JavaThread *tp = jtiwh.next(); ) {
1506 if (jvmci_counters_include(tp)) {
1507 for (int i = 0; i < array->length(); i++) {
1508 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1509 }
1510 }
1511 }
1512 }
1513 }
1514
1515 #endif // INCLUDE_JVMCI
1516
1517 // A JavaThread is a normal Java thread
1518
1519 void JavaThread::initialize() {
1520 // Initialize fields
1521
1522 set_saved_exception_pc(NULL);
1523 set_threadObj(NULL);
1524 _anchor.clear();
1525 set_entry_point(NULL);
1526 set_jni_functions(jni_functions());
1527 set_callee_target(NULL);
1528 set_vm_result(NULL);
1529 set_vm_result_2(NULL);
1530 set_return_buffered_value(NULL);
1531 set_vframe_array_head(NULL);
1532 set_vframe_array_last(NULL);
1533 set_deferred_locals(NULL);
1534 set_deopt_mark(NULL);
1535 set_deopt_compiled_method(NULL);
1536 clear_must_deopt_id();
1537 set_monitor_chunks(NULL);
1538 set_next(NULL);
1539 _on_thread_list = false;
1540 set_thread_state(_thread_new);
1541 _terminated = _not_terminated;
1542 _privileged_stack_top = NULL;
1543 _array_for_gc = NULL;
1544 _suspend_equivalent = false;
1545 _in_deopt_handler = 0;
1546 _doing_unsafe_access = false;
1547 _stack_guard_state = stack_guard_unused;
1548 #if INCLUDE_JVMCI
1549 _pending_monitorenter = false;
1550 _pending_deoptimization = -1;
1551 _pending_failed_speculation = 0;
1552 _pending_transfer_to_interpreter = false;
1553 _adjusting_comp_level = false;
1554 _jvmci._alternate_call_target = NULL;
1555 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1556 if (JVMCICounterSize > 0) {
1557 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1558 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1559 } else {
1560 _jvmci_counters = NULL;
1561 }
1562 #endif // INCLUDE_JVMCI
1563 _reserved_stack_activation = NULL; // stack base not known yet
1564 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1565 _exception_pc = 0;
1566 _exception_handler_pc = 0;
1567 _is_method_handle_return = 0;
1568 _jvmti_thread_state= NULL;
1569 _should_post_on_exceptions_flag = JNI_FALSE;
1570 _interp_only_mode = 0;
1571 _special_runtime_exit_condition = _no_async_condition;
1572 _pending_async_exception = NULL;
1573 _thread_stat = NULL;
1574 _thread_stat = new ThreadStatistics();
1575 _blocked_on_compilation = false;
1576 _jni_active_critical = 0;
1577 _pending_jni_exception_check_fn = NULL;
1578 _do_not_unlock_if_synchronized = false;
1579 _cached_monitor_info = NULL;
1580 _parker = Parker::Allocate(this);
1581
1582 #ifndef PRODUCT
1583 _jmp_ring_index = 0;
1584 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1585 record_jump(NULL, NULL, NULL, 0);
1586 }
1587 #endif // PRODUCT
1588
1589 // Setup safepoint state info for this thread
1590 ThreadSafepointState::create(this);
1591
1592 debug_only(_java_call_counter = 0);
1593
1594 // JVMTI PopFrame support
1595 _popframe_condition = popframe_inactive;
1596 _popframe_preserved_args = NULL;
1597 _popframe_preserved_args_size = 0;
1598 _frames_to_pop_failed_realloc = 0;
1599
1600 if (SafepointMechanism::uses_thread_local_poll()) {
1601 SafepointMechanism::initialize_header(this);
1602 }
1603
1604 pd_initialize();
1605 }
1606
1607 JavaThread::JavaThread(bool is_attaching_via_jni) :
1608 Thread() {
1609 initialize();
1610 if (is_attaching_via_jni) {
1611 _jni_attach_state = _attaching_via_jni;
1612 } else {
1613 _jni_attach_state = _not_attaching_via_jni;
1614 }
1615 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1616 }
1617
1618 bool JavaThread::reguard_stack(address cur_sp) {
1619 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1620 && _stack_guard_state != stack_guard_reserved_disabled) {
1621 return true; // Stack already guarded or guard pages not needed.
1622 }
1623
1624 if (register_stack_overflow()) {
1625 // For those architectures which have separate register and
1626 // memory stacks, we must check the register stack to see if
1627 // it has overflowed.
1628 return false;
1629 }
1630
1631 // Java code never executes within the yellow zone: the latter is only
1632 // there to provoke an exception during stack banging. If java code
1633 // is executing there, either StackShadowPages should be larger, or
1634 // some exception code in c1, c2 or the interpreter isn't unwinding
1635 // when it should.
1636 guarantee(cur_sp > stack_reserved_zone_base(),
1637 "not enough space to reguard - increase StackShadowPages");
1638 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1639 enable_stack_yellow_reserved_zone();
1640 if (reserved_stack_activation() != stack_base()) {
1641 set_reserved_stack_activation(stack_base());
1642 }
1643 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1644 set_reserved_stack_activation(stack_base());
1645 enable_stack_reserved_zone();
1646 }
1647 return true;
1648 }
1649
1650 bool JavaThread::reguard_stack(void) {
1651 return reguard_stack(os::current_stack_pointer());
1652 }
1653
1654
1655 void JavaThread::block_if_vm_exited() {
1656 if (_terminated == _vm_exited) {
1657 // _vm_exited is set at safepoint, and Threads_lock is never released
1658 // we will block here forever
1659 Threads_lock->lock_without_safepoint_check();
1660 ShouldNotReachHere();
1661 }
1662 }
1663
1664
1665 // Remove this ifdef when C1 is ported to the compiler interface.
1666 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1667 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1668
1669 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1670 Thread() {
1671 initialize();
1672 _jni_attach_state = _not_attaching_via_jni;
1673 set_entry_point(entry_point);
1674 // Create the native thread itself.
1675 // %note runtime_23
1676 os::ThreadType thr_type = os::java_thread;
1677 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1678 os::java_thread;
1679 os::create_thread(this, thr_type, stack_sz);
1680 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1681 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1682 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1683 // the exception consists of creating the exception object & initializing it, initialization
1684 // will leave the VM via a JavaCall and then all locks must be unlocked).
1685 //
1686 // The thread is still suspended when we reach here. Thread must be explicit started
1687 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1688 // by calling Threads:add. The reason why this is not done here, is because the thread
1689 // object must be fully initialized (take a look at JVM_Start)
1690 }
1691
1692 JavaThread::~JavaThread() {
1693
1694 // JSR166 -- return the parker to the free list
1695 Parker::Release(_parker);
1696 _parker = NULL;
1697
1698 // Free any remaining previous UnrollBlock
1699 vframeArray* old_array = vframe_array_last();
1700
1701 if (old_array != NULL) {
1702 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1703 old_array->set_unroll_block(NULL);
1704 delete old_info;
1705 delete old_array;
1706 }
1707
1708 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1709 if (deferred != NULL) {
1710 // This can only happen if thread is destroyed before deoptimization occurs.
1711 assert(deferred->length() != 0, "empty array!");
1712 do {
1713 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1714 deferred->remove_at(0);
1715 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1716 delete dlv;
1717 } while (deferred->length() != 0);
1718 delete deferred;
1719 }
1720
1721 // All Java related clean up happens in exit
1722 ThreadSafepointState::destroy(this);
1723 if (_thread_stat != NULL) delete _thread_stat;
1724
1725 #if INCLUDE_JVMCI
1726 if (JVMCICounterSize > 0) {
1727 if (jvmci_counters_include(this)) {
1728 for (int i = 0; i < JVMCICounterSize; i++) {
1729 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1730 }
1731 }
1732 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1733 }
1734 #endif // INCLUDE_JVMCI
1735 }
1736
1737
1738 // The first routine called by a new Java thread
1739 void JavaThread::run() {
1740 // initialize thread-local alloc buffer related fields
1741 this->initialize_tlab();
1742
1743 // used to test validity of stack trace backs
1744 this->record_base_of_stack_pointer();
1745
1746 // Record real stack base and size.
1747 this->record_stack_base_and_size();
1748
1749 this->create_stack_guard_pages();
1750
1751 this->cache_global_variables();
1752
1753 // Thread is now sufficient initialized to be handled by the safepoint code as being
1754 // in the VM. Change thread state from _thread_new to _thread_in_vm
1755 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1756
1757 assert(JavaThread::current() == this, "sanity check");
1758 assert(!Thread::current()->owns_locks(), "sanity check");
1759
1760 DTRACE_THREAD_PROBE(start, this);
1761
1762 // This operation might block. We call that after all safepoint checks for a new thread has
1763 // been completed.
1764 this->set_active_handles(JNIHandleBlock::allocate_block());
1765
1766 if (JvmtiExport::should_post_thread_life()) {
1767 JvmtiExport::post_thread_start(this);
1768 }
1769
1770 EventThreadStart event;
1771 if (event.should_commit()) {
1772 event.set_thread(JFR_THREAD_ID(this));
1773 event.commit();
1774 }
1775
1776 // We call another function to do the rest so we are sure that the stack addresses used
1777 // from there will be lower than the stack base just computed
1778 thread_main_inner();
1779
1780 // Note, thread is no longer valid at this point!
1781 }
1782
1783
1784 void JavaThread::thread_main_inner() {
1785 assert(JavaThread::current() == this, "sanity check");
1786 assert(this->threadObj() != NULL, "just checking");
1787
1788 // Execute thread entry point unless this thread has a pending exception
1789 // or has been stopped before starting.
1790 // Note: Due to JVM_StopThread we can have pending exceptions already!
1791 if (!this->has_pending_exception() &&
1792 !java_lang_Thread::is_stillborn(this->threadObj())) {
1793 {
1794 ResourceMark rm(this);
1795 this->set_native_thread_name(this->get_thread_name());
1796 }
1797 HandleMark hm(this);
1798 this->entry_point()(this, this);
1799 }
1800
1801 DTRACE_THREAD_PROBE(stop, this);
1802
1803 this->exit(false);
1804 this->smr_delete();
1805 }
1806
1807
1808 static void ensure_join(JavaThread* thread) {
1809 // We do not need to grab the Threads_lock, since we are operating on ourself.
1810 Handle threadObj(thread, thread->threadObj());
1811 assert(threadObj.not_null(), "java thread object must exist");
1812 ObjectLocker lock(threadObj, thread);
1813 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1814 thread->clear_pending_exception();
1815 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1816 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1817 // Clear the native thread instance - this makes isAlive return false and allows the join()
1818 // to complete once we've done the notify_all below
1819 java_lang_Thread::set_thread(threadObj(), NULL);
1820 lock.notify_all(thread);
1821 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1822 thread->clear_pending_exception();
1823 }
1824
1825
1826 // For any new cleanup additions, please check to see if they need to be applied to
1827 // cleanup_failed_attach_current_thread as well.
1828 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1829 assert(this == JavaThread::current(), "thread consistency check");
1830
1831 elapsedTimer _timer_exit_phase1;
1832 elapsedTimer _timer_exit_phase2;
1833 elapsedTimer _timer_exit_phase3;
1834 elapsedTimer _timer_exit_phase4;
1835
1836 if (log_is_enabled(Debug, os, thread, timer)) {
1837 _timer_exit_phase1.start();
1838 }
1839
1840 HandleMark hm(this);
1841 Handle uncaught_exception(this, this->pending_exception());
1842 this->clear_pending_exception();
1843 Handle threadObj(this, this->threadObj());
1844 assert(threadObj.not_null(), "Java thread object should be created");
1845
1846 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1847 {
1848 EXCEPTION_MARK;
1849
1850 CLEAR_PENDING_EXCEPTION;
1851 }
1852 if (!destroy_vm) {
1853 if (uncaught_exception.not_null()) {
1854 EXCEPTION_MARK;
1855 // Call method Thread.dispatchUncaughtException().
1856 Klass* thread_klass = SystemDictionary::Thread_klass();
1857 JavaValue result(T_VOID);
1858 JavaCalls::call_virtual(&result,
1859 threadObj, thread_klass,
1860 vmSymbols::dispatchUncaughtException_name(),
1861 vmSymbols::throwable_void_signature(),
1862 uncaught_exception,
1863 THREAD);
1864 if (HAS_PENDING_EXCEPTION) {
1865 ResourceMark rm(this);
1866 jio_fprintf(defaultStream::error_stream(),
1867 "\nException: %s thrown from the UncaughtExceptionHandler"
1868 " in thread \"%s\"\n",
1869 pending_exception()->klass()->external_name(),
1870 get_thread_name());
1871 CLEAR_PENDING_EXCEPTION;
1872 }
1873 }
1874
1875 // Called before the java thread exit since we want to read info
1876 // from java_lang_Thread object
1877 EventThreadEnd event;
1878 if (event.should_commit()) {
1879 event.set_thread(JFR_THREAD_ID(this));
1880 event.commit();
1881 }
1882
1883 // Call after last event on thread
1884 JFR_ONLY(Jfr::on_thread_exit(this);)
1885
1886 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1887 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1888 // is deprecated anyhow.
1889 if (!is_Compiler_thread()) {
1890 int count = 3;
1891 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1892 EXCEPTION_MARK;
1893 JavaValue result(T_VOID);
1894 Klass* thread_klass = SystemDictionary::Thread_klass();
1895 JavaCalls::call_virtual(&result,
1896 threadObj, thread_klass,
1897 vmSymbols::exit_method_name(),
1898 vmSymbols::void_method_signature(),
1899 THREAD);
1900 CLEAR_PENDING_EXCEPTION;
1901 }
1902 }
1903 // notify JVMTI
1904 if (JvmtiExport::should_post_thread_life()) {
1905 JvmtiExport::post_thread_end(this);
1906 }
1907
1908 // We have notified the agents that we are exiting, before we go on,
1909 // we must check for a pending external suspend request and honor it
1910 // in order to not surprise the thread that made the suspend request.
1911 while (true) {
1912 {
1913 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1914 if (!is_external_suspend()) {
1915 set_terminated(_thread_exiting);
1916 ThreadService::current_thread_exiting(this);
1917 break;
1918 }
1919 // Implied else:
1920 // Things get a little tricky here. We have a pending external
1921 // suspend request, but we are holding the SR_lock so we
1922 // can't just self-suspend. So we temporarily drop the lock
1923 // and then self-suspend.
1924 }
1925
1926 ThreadBlockInVM tbivm(this);
1927 java_suspend_self();
1928
1929 // We're done with this suspend request, but we have to loop around
1930 // and check again. Eventually we will get SR_lock without a pending
1931 // external suspend request and will be able to mark ourselves as
1932 // exiting.
1933 }
1934 // no more external suspends are allowed at this point
1935 } else {
1936 // before_exit() has already posted JVMTI THREAD_END events
1937 }
1938
1939 if (log_is_enabled(Debug, os, thread, timer)) {
1940 _timer_exit_phase1.stop();
1941 _timer_exit_phase2.start();
1942 }
1943 // Notify waiters on thread object. This has to be done after exit() is called
1944 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1945 // group should have the destroyed bit set before waiters are notified).
1946 ensure_join(this);
1947 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1948
1949 if (log_is_enabled(Debug, os, thread, timer)) {
1950 _timer_exit_phase2.stop();
1951 _timer_exit_phase3.start();
1952 }
1953 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1954 // held by this thread must be released. The spec does not distinguish
1955 // between JNI-acquired and regular Java monitors. We can only see
1956 // regular Java monitors here if monitor enter-exit matching is broken.
1957 //
1958 // Optionally release any monitors for regular JavaThread exits. This
1959 // is provided as a work around for any bugs in monitor enter-exit
1960 // matching. This can be expensive so it is not enabled by default.
1961 //
1962 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1963 // ObjectSynchronizer::release_monitors_owned_by_thread().
1964 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1965 // Sanity check even though JNI DetachCurrentThread() would have
1966 // returned JNI_ERR if there was a Java frame. JavaThread exit
1967 // should be done executing Java code by the time we get here.
1968 assert(!this->has_last_Java_frame(),
1969 "should not have a Java frame when detaching or exiting");
1970 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1971 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1972 }
1973
1974 // These things needs to be done while we are still a Java Thread. Make sure that thread
1975 // is in a consistent state, in case GC happens
1976 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1977
1978 if (active_handles() != NULL) {
1979 JNIHandleBlock* block = active_handles();
1980 set_active_handles(NULL);
1981 JNIHandleBlock::release_block(block);
1982 }
1983
1984 if (free_handle_block() != NULL) {
1985 JNIHandleBlock* block = free_handle_block();
1986 set_free_handle_block(NULL);
1987 JNIHandleBlock::release_block(block);
1988 }
1989
1990 // These have to be removed while this is still a valid thread.
1991 remove_stack_guard_pages();
1992
1993 if (UseTLAB) {
1994 tlab().make_parsable(true); // retire TLAB
1995 }
1996
1997 if (JvmtiEnv::environments_might_exist()) {
1998 JvmtiExport::cleanup_thread(this);
1999 }
2000
2001 // We must flush any deferred card marks and other various GC barrier
2002 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2003 // before removing a thread from the list of active threads.
2004 BarrierSet::barrier_set()->on_thread_detach(this);
2005
2006 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2007 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2008 os::current_thread_id());
2009
2010 if (log_is_enabled(Debug, os, thread, timer)) {
2011 _timer_exit_phase3.stop();
2012 _timer_exit_phase4.start();
2013 }
2014 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2015 Threads::remove(this);
2016
2017 if (log_is_enabled(Debug, os, thread, timer)) {
2018 _timer_exit_phase4.stop();
2019 ResourceMark rm(this);
2020 log_debug(os, thread, timer)("name='%s'"
2021 ", exit-phase1=" JLONG_FORMAT
2022 ", exit-phase2=" JLONG_FORMAT
2023 ", exit-phase3=" JLONG_FORMAT
2024 ", exit-phase4=" JLONG_FORMAT,
2025 get_thread_name(),
2026 _timer_exit_phase1.milliseconds(),
2027 _timer_exit_phase2.milliseconds(),
2028 _timer_exit_phase3.milliseconds(),
2029 _timer_exit_phase4.milliseconds());
2030 }
2031 }
2032
2033 void JavaThread::cleanup_failed_attach_current_thread() {
2034 if (active_handles() != NULL) {
2035 JNIHandleBlock* block = active_handles();
2036 set_active_handles(NULL);
2037 JNIHandleBlock::release_block(block);
2038 }
2039
2040 if (free_handle_block() != NULL) {
2041 JNIHandleBlock* block = free_handle_block();
2042 set_free_handle_block(NULL);
2043 JNIHandleBlock::release_block(block);
2044 }
2045
2046 // These have to be removed while this is still a valid thread.
2047 remove_stack_guard_pages();
2048
2049 if (UseTLAB) {
2050 tlab().make_parsable(true); // retire TLAB, if any
2051 }
2052
2053 BarrierSet::barrier_set()->on_thread_detach(this);
2054
2055 Threads::remove(this);
2056 this->smr_delete();
2057 }
2058
2059 JavaThread* JavaThread::active() {
2060 Thread* thread = Thread::current();
2061 if (thread->is_Java_thread()) {
2062 return (JavaThread*) thread;
2063 } else {
2064 assert(thread->is_VM_thread(), "this must be a vm thread");
2065 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2066 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2067 assert(ret->is_Java_thread(), "must be a Java thread");
2068 return ret;
2069 }
2070 }
2071
2072 bool JavaThread::is_lock_owned(address adr) const {
2073 if (Thread::is_lock_owned(adr)) return true;
2074
2075 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2076 if (chunk->contains(adr)) return true;
2077 }
2078
2079 return false;
2080 }
2081
2082
2083 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2084 chunk->set_next(monitor_chunks());
2085 set_monitor_chunks(chunk);
2086 }
2087
2088 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2089 guarantee(monitor_chunks() != NULL, "must be non empty");
2090 if (monitor_chunks() == chunk) {
2091 set_monitor_chunks(chunk->next());
2092 } else {
2093 MonitorChunk* prev = monitor_chunks();
2094 while (prev->next() != chunk) prev = prev->next();
2095 prev->set_next(chunk->next());
2096 }
2097 }
2098
2099 // JVM support.
2100
2101 // Note: this function shouldn't block if it's called in
2102 // _thread_in_native_trans state (such as from
2103 // check_special_condition_for_native_trans()).
2104 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2105
2106 if (has_last_Java_frame() && has_async_condition()) {
2107 // If we are at a polling page safepoint (not a poll return)
2108 // then we must defer async exception because live registers
2109 // will be clobbered by the exception path. Poll return is
2110 // ok because the call we a returning from already collides
2111 // with exception handling registers and so there is no issue.
2112 // (The exception handling path kills call result registers but
2113 // this is ok since the exception kills the result anyway).
2114
2115 if (is_at_poll_safepoint()) {
2116 // if the code we are returning to has deoptimized we must defer
2117 // the exception otherwise live registers get clobbered on the
2118 // exception path before deoptimization is able to retrieve them.
2119 //
2120 RegisterMap map(this, false);
2121 frame caller_fr = last_frame().sender(&map);
2122 assert(caller_fr.is_compiled_frame(), "what?");
2123 if (caller_fr.is_deoptimized_frame()) {
2124 log_info(exceptions)("deferred async exception at compiled safepoint");
2125 return;
2126 }
2127 }
2128 }
2129
2130 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2131 if (condition == _no_async_condition) {
2132 // Conditions have changed since has_special_runtime_exit_condition()
2133 // was called:
2134 // - if we were here only because of an external suspend request,
2135 // then that was taken care of above (or cancelled) so we are done
2136 // - if we were here because of another async request, then it has
2137 // been cleared between the has_special_runtime_exit_condition()
2138 // and now so again we are done
2139 return;
2140 }
2141
2142 // Check for pending async. exception
2143 if (_pending_async_exception != NULL) {
2144 // Only overwrite an already pending exception, if it is not a threadDeath.
2145 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2146
2147 // We cannot call Exceptions::_throw(...) here because we cannot block
2148 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2149
2150 LogTarget(Info, exceptions) lt;
2151 if (lt.is_enabled()) {
2152 ResourceMark rm;
2153 LogStream ls(lt);
2154 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2155 if (has_last_Java_frame()) {
2156 frame f = last_frame();
2157 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2158 }
2159 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2160 }
2161 _pending_async_exception = NULL;
2162 clear_has_async_exception();
2163 }
2164 }
2165
2166 if (check_unsafe_error &&
2167 condition == _async_unsafe_access_error && !has_pending_exception()) {
2168 condition = _no_async_condition; // done
2169 switch (thread_state()) {
2170 case _thread_in_vm: {
2171 JavaThread* THREAD = this;
2172 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2173 }
2174 case _thread_in_native: {
2175 ThreadInVMfromNative tiv(this);
2176 JavaThread* THREAD = this;
2177 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2178 }
2179 case _thread_in_Java: {
2180 ThreadInVMfromJava tiv(this);
2181 JavaThread* THREAD = this;
2182 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2183 }
2184 default:
2185 ShouldNotReachHere();
2186 }
2187 }
2188
2189 assert(condition == _no_async_condition || has_pending_exception() ||
2190 (!check_unsafe_error && condition == _async_unsafe_access_error),
2191 "must have handled the async condition, if no exception");
2192 }
2193
2194 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2195 //
2196 // Check for pending external suspend. Internal suspend requests do
2197 // not use handle_special_runtime_exit_condition().
2198 // If JNIEnv proxies are allowed, don't self-suspend if the target
2199 // thread is not the current thread. In older versions of jdbx, jdbx
2200 // threads could call into the VM with another thread's JNIEnv so we
2201 // can be here operating on behalf of a suspended thread (4432884).
2202 bool do_self_suspend = is_external_suspend_with_lock();
2203 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2204 //
2205 // Because thread is external suspended the safepoint code will count
2206 // thread as at a safepoint. This can be odd because we can be here
2207 // as _thread_in_Java which would normally transition to _thread_blocked
2208 // at a safepoint. We would like to mark the thread as _thread_blocked
2209 // before calling java_suspend_self like all other callers of it but
2210 // we must then observe proper safepoint protocol. (We can't leave
2211 // _thread_blocked with a safepoint in progress). However we can be
2212 // here as _thread_in_native_trans so we can't use a normal transition
2213 // constructor/destructor pair because they assert on that type of
2214 // transition. We could do something like:
2215 //
2216 // JavaThreadState state = thread_state();
2217 // set_thread_state(_thread_in_vm);
2218 // {
2219 // ThreadBlockInVM tbivm(this);
2220 // java_suspend_self()
2221 // }
2222 // set_thread_state(_thread_in_vm_trans);
2223 // if (safepoint) block;
2224 // set_thread_state(state);
2225 //
2226 // but that is pretty messy. Instead we just go with the way the
2227 // code has worked before and note that this is the only path to
2228 // java_suspend_self that doesn't put the thread in _thread_blocked
2229 // mode.
2230
2231 frame_anchor()->make_walkable(this);
2232 java_suspend_self();
2233
2234 // We might be here for reasons in addition to the self-suspend request
2235 // so check for other async requests.
2236 }
2237
2238 if (check_asyncs) {
2239 check_and_handle_async_exceptions();
2240 }
2241
2242 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2243 }
2244
2245 void JavaThread::send_thread_stop(oop java_throwable) {
2246 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2247 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2248 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2249
2250 // Do not throw asynchronous exceptions against the compiler thread
2251 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2252 if (!can_call_java()) return;
2253
2254 {
2255 // Actually throw the Throwable against the target Thread - however
2256 // only if there is no thread death exception installed already.
2257 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2258 // If the topmost frame is a runtime stub, then we are calling into
2259 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2260 // must deoptimize the caller before continuing, as the compiled exception handler table
2261 // may not be valid
2262 if (has_last_Java_frame()) {
2263 frame f = last_frame();
2264 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2265 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2266 RegisterMap reg_map(this, UseBiasedLocking);
2267 frame compiled_frame = f.sender(®_map);
2268 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2269 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2270 }
2271 }
2272 }
2273
2274 // Set async. pending exception in thread.
2275 set_pending_async_exception(java_throwable);
2276
2277 if (log_is_enabled(Info, exceptions)) {
2278 ResourceMark rm;
2279 log_info(exceptions)("Pending Async. exception installed of type: %s",
2280 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2281 }
2282 // for AbortVMOnException flag
2283 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2284 }
2285 }
2286
2287
2288 // Interrupt thread so it will wake up from a potential wait()
2289 Thread::interrupt(this);
2290 }
2291
2292 // External suspension mechanism.
2293 //
2294 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2295 // to any VM_locks and it is at a transition
2296 // Self-suspension will happen on the transition out of the vm.
2297 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2298 //
2299 // Guarantees on return:
2300 // + Target thread will not execute any new bytecode (that's why we need to
2301 // force a safepoint)
2302 // + Target thread will not enter any new monitors
2303 //
2304 void JavaThread::java_suspend() {
2305 ThreadsListHandle tlh;
2306 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2307 return;
2308 }
2309
2310 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2311 if (!is_external_suspend()) {
2312 // a racing resume has cancelled us; bail out now
2313 return;
2314 }
2315
2316 // suspend is done
2317 uint32_t debug_bits = 0;
2318 // Warning: is_ext_suspend_completed() may temporarily drop the
2319 // SR_lock to allow the thread to reach a stable thread state if
2320 // it is currently in a transient thread state.
2321 if (is_ext_suspend_completed(false /* !called_by_wait */,
2322 SuspendRetryDelay, &debug_bits)) {
2323 return;
2324 }
2325 }
2326
2327 VM_ThreadSuspend vm_suspend;
2328 VMThread::execute(&vm_suspend);
2329 }
2330
2331 // Part II of external suspension.
2332 // A JavaThread self suspends when it detects a pending external suspend
2333 // request. This is usually on transitions. It is also done in places
2334 // where continuing to the next transition would surprise the caller,
2335 // e.g., monitor entry.
2336 //
2337 // Returns the number of times that the thread self-suspended.
2338 //
2339 // Note: DO NOT call java_suspend_self() when you just want to block current
2340 // thread. java_suspend_self() is the second stage of cooperative
2341 // suspension for external suspend requests and should only be used
2342 // to complete an external suspend request.
2343 //
2344 int JavaThread::java_suspend_self() {
2345 int ret = 0;
2346
2347 // we are in the process of exiting so don't suspend
2348 if (is_exiting()) {
2349 clear_external_suspend();
2350 return ret;
2351 }
2352
2353 assert(_anchor.walkable() ||
2354 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2355 "must have walkable stack");
2356
2357 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2358
2359 assert(!this->is_ext_suspended(),
2360 "a thread trying to self-suspend should not already be suspended");
2361
2362 if (this->is_suspend_equivalent()) {
2363 // If we are self-suspending as a result of the lifting of a
2364 // suspend equivalent condition, then the suspend_equivalent
2365 // flag is not cleared until we set the ext_suspended flag so
2366 // that wait_for_ext_suspend_completion() returns consistent
2367 // results.
2368 this->clear_suspend_equivalent();
2369 }
2370
2371 // A racing resume may have cancelled us before we grabbed SR_lock
2372 // above. Or another external suspend request could be waiting for us
2373 // by the time we return from SR_lock()->wait(). The thread
2374 // that requested the suspension may already be trying to walk our
2375 // stack and if we return now, we can change the stack out from under
2376 // it. This would be a "bad thing (TM)" and cause the stack walker
2377 // to crash. We stay self-suspended until there are no more pending
2378 // external suspend requests.
2379 while (is_external_suspend()) {
2380 ret++;
2381 this->set_ext_suspended();
2382
2383 // _ext_suspended flag is cleared by java_resume()
2384 while (is_ext_suspended()) {
2385 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2386 }
2387 }
2388
2389 return ret;
2390 }
2391
2392 #ifdef ASSERT
2393 // Verify the JavaThread has not yet been published in the Threads::list, and
2394 // hence doesn't need protection from concurrent access at this stage.
2395 void JavaThread::verify_not_published() {
2396 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2397 // since an unpublished JavaThread doesn't participate in the
2398 // Thread-SMR protocol for keeping a ThreadsList alive.
2399 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2400 }
2401 #endif
2402
2403 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2404 // progress or when _suspend_flags is non-zero.
2405 // Current thread needs to self-suspend if there is a suspend request and/or
2406 // block if a safepoint is in progress.
2407 // Async exception ISN'T checked.
2408 // Note only the ThreadInVMfromNative transition can call this function
2409 // directly and when thread state is _thread_in_native_trans
2410 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2411 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2412
2413 JavaThread *curJT = JavaThread::current();
2414 bool do_self_suspend = thread->is_external_suspend();
2415
2416 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2417
2418 // If JNIEnv proxies are allowed, don't self-suspend if the target
2419 // thread is not the current thread. In older versions of jdbx, jdbx
2420 // threads could call into the VM with another thread's JNIEnv so we
2421 // can be here operating on behalf of a suspended thread (4432884).
2422 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2423 JavaThreadState state = thread->thread_state();
2424
2425 // We mark this thread_blocked state as a suspend-equivalent so
2426 // that a caller to is_ext_suspend_completed() won't be confused.
2427 // The suspend-equivalent state is cleared by java_suspend_self().
2428 thread->set_suspend_equivalent();
2429
2430 // If the safepoint code sees the _thread_in_native_trans state, it will
2431 // wait until the thread changes to other thread state. There is no
2432 // guarantee on how soon we can obtain the SR_lock and complete the
2433 // self-suspend request. It would be a bad idea to let safepoint wait for
2434 // too long. Temporarily change the state to _thread_blocked to
2435 // let the VM thread know that this thread is ready for GC. The problem
2436 // of changing thread state is that safepoint could happen just after
2437 // java_suspend_self() returns after being resumed, and VM thread will
2438 // see the _thread_blocked state. We must check for safepoint
2439 // after restoring the state and make sure we won't leave while a safepoint
2440 // is in progress.
2441 thread->set_thread_state(_thread_blocked);
2442 thread->java_suspend_self();
2443 thread->set_thread_state(state);
2444
2445 InterfaceSupport::serialize_thread_state_with_handler(thread);
2446 }
2447
2448 SafepointMechanism::block_if_requested(curJT);
2449
2450 if (thread->is_deopt_suspend()) {
2451 thread->clear_deopt_suspend();
2452 RegisterMap map(thread, false);
2453 frame f = thread->last_frame();
2454 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2455 f = f.sender(&map);
2456 }
2457 if (f.id() == thread->must_deopt_id()) {
2458 thread->clear_must_deopt_id();
2459 f.deoptimize(thread);
2460 } else {
2461 fatal("missed deoptimization!");
2462 }
2463 }
2464
2465 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2466 }
2467
2468 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2469 // progress or when _suspend_flags is non-zero.
2470 // Current thread needs to self-suspend if there is a suspend request and/or
2471 // block if a safepoint is in progress.
2472 // Also check for pending async exception (not including unsafe access error).
2473 // Note only the native==>VM/Java barriers can call this function and when
2474 // thread state is _thread_in_native_trans.
2475 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2476 check_safepoint_and_suspend_for_native_trans(thread);
2477
2478 if (thread->has_async_exception()) {
2479 // We are in _thread_in_native_trans state, don't handle unsafe
2480 // access error since that may block.
2481 thread->check_and_handle_async_exceptions(false);
2482 }
2483 }
2484
2485 // This is a variant of the normal
2486 // check_special_condition_for_native_trans with slightly different
2487 // semantics for use by critical native wrappers. It does all the
2488 // normal checks but also performs the transition back into
2489 // thread_in_Java state. This is required so that critical natives
2490 // can potentially block and perform a GC if they are the last thread
2491 // exiting the GCLocker.
2492 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2493 check_special_condition_for_native_trans(thread);
2494
2495 // Finish the transition
2496 thread->set_thread_state(_thread_in_Java);
2497
2498 if (thread->do_critical_native_unlock()) {
2499 ThreadInVMfromJavaNoAsyncException tiv(thread);
2500 GCLocker::unlock_critical(thread);
2501 thread->clear_critical_native_unlock();
2502 }
2503 }
2504
2505 // We need to guarantee the Threads_lock here, since resumes are not
2506 // allowed during safepoint synchronization
2507 // Can only resume from an external suspension
2508 void JavaThread::java_resume() {
2509 assert_locked_or_safepoint(Threads_lock);
2510
2511 // Sanity check: thread is gone, has started exiting or the thread
2512 // was not externally suspended.
2513 ThreadsListHandle tlh;
2514 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2515 return;
2516 }
2517
2518 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2519
2520 clear_external_suspend();
2521
2522 if (is_ext_suspended()) {
2523 clear_ext_suspended();
2524 SR_lock()->notify_all();
2525 }
2526 }
2527
2528 size_t JavaThread::_stack_red_zone_size = 0;
2529 size_t JavaThread::_stack_yellow_zone_size = 0;
2530 size_t JavaThread::_stack_reserved_zone_size = 0;
2531 size_t JavaThread::_stack_shadow_zone_size = 0;
2532
2533 void JavaThread::create_stack_guard_pages() {
2534 if (!os::uses_stack_guard_pages() ||
2535 _stack_guard_state != stack_guard_unused ||
2536 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2537 log_info(os, thread)("Stack guard page creation for thread "
2538 UINTX_FORMAT " disabled", os::current_thread_id());
2539 return;
2540 }
2541 address low_addr = stack_end();
2542 size_t len = stack_guard_zone_size();
2543
2544 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2545 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2546
2547 int must_commit = os::must_commit_stack_guard_pages();
2548 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2549
2550 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2551 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2552 return;
2553 }
2554
2555 if (os::guard_memory((char *) low_addr, len)) {
2556 _stack_guard_state = stack_guard_enabled;
2557 } else {
2558 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2559 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2560 if (os::uncommit_memory((char *) low_addr, len)) {
2561 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2562 }
2563 return;
2564 }
2565
2566 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2567 PTR_FORMAT "-" PTR_FORMAT ".",
2568 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2569 }
2570
2571 void JavaThread::remove_stack_guard_pages() {
2572 assert(Thread::current() == this, "from different thread");
2573 if (_stack_guard_state == stack_guard_unused) return;
2574 address low_addr = stack_end();
2575 size_t len = stack_guard_zone_size();
2576
2577 if (os::must_commit_stack_guard_pages()) {
2578 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2579 _stack_guard_state = stack_guard_unused;
2580 } else {
2581 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2582 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2583 return;
2584 }
2585 } else {
2586 if (_stack_guard_state == stack_guard_unused) return;
2587 if (os::unguard_memory((char *) low_addr, len)) {
2588 _stack_guard_state = stack_guard_unused;
2589 } else {
2590 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2591 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2592 return;
2593 }
2594 }
2595
2596 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2597 PTR_FORMAT "-" PTR_FORMAT ".",
2598 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2599 }
2600
2601 void JavaThread::enable_stack_reserved_zone() {
2602 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2603 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2604
2605 // The base notation is from the stack's point of view, growing downward.
2606 // We need to adjust it to work correctly with guard_memory()
2607 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2608
2609 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2610 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2611
2612 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2613 _stack_guard_state = stack_guard_enabled;
2614 } else {
2615 warning("Attempt to guard stack reserved zone failed.");
2616 }
2617 enable_register_stack_guard();
2618 }
2619
2620 void JavaThread::disable_stack_reserved_zone() {
2621 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2622 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2623
2624 // Simply return if called for a thread that does not use guard pages.
2625 if (_stack_guard_state == stack_guard_unused) return;
2626
2627 // The base notation is from the stack's point of view, growing downward.
2628 // We need to adjust it to work correctly with guard_memory()
2629 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2630
2631 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2632 _stack_guard_state = stack_guard_reserved_disabled;
2633 } else {
2634 warning("Attempt to unguard stack reserved zone failed.");
2635 }
2636 disable_register_stack_guard();
2637 }
2638
2639 void JavaThread::enable_stack_yellow_reserved_zone() {
2640 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2641 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2642
2643 // The base notation is from the stacks point of view, growing downward.
2644 // We need to adjust it to work correctly with guard_memory()
2645 address base = stack_red_zone_base();
2646
2647 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2648 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2649
2650 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2651 _stack_guard_state = stack_guard_enabled;
2652 } else {
2653 warning("Attempt to guard stack yellow zone failed.");
2654 }
2655 enable_register_stack_guard();
2656 }
2657
2658 void JavaThread::disable_stack_yellow_reserved_zone() {
2659 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2660 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2661
2662 // Simply return if called for a thread that does not use guard pages.
2663 if (_stack_guard_state == stack_guard_unused) return;
2664
2665 // The base notation is from the stacks point of view, growing downward.
2666 // We need to adjust it to work correctly with guard_memory()
2667 address base = stack_red_zone_base();
2668
2669 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2670 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2671 } else {
2672 warning("Attempt to unguard stack yellow zone failed.");
2673 }
2674 disable_register_stack_guard();
2675 }
2676
2677 void JavaThread::enable_stack_red_zone() {
2678 // The base notation is from the stacks point of view, growing downward.
2679 // We need to adjust it to work correctly with guard_memory()
2680 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2681 address base = stack_red_zone_base() - stack_red_zone_size();
2682
2683 guarantee(base < stack_base(), "Error calculating stack red zone");
2684 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2685
2686 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2687 warning("Attempt to guard stack red zone failed.");
2688 }
2689 }
2690
2691 void JavaThread::disable_stack_red_zone() {
2692 // The base notation is from the stacks point of view, growing downward.
2693 // We need to adjust it to work correctly with guard_memory()
2694 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2695 address base = stack_red_zone_base() - stack_red_zone_size();
2696 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2697 warning("Attempt to unguard stack red zone failed.");
2698 }
2699 }
2700
2701 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2702 // ignore is there is no stack
2703 if (!has_last_Java_frame()) return;
2704 // Because this method is used to verify oops, it must support
2705 // oops in buffered values
2706
2707 // traverse the stack frames. Starts from top frame.
2708 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2709 frame* fr = fst.current();
2710 f(fr, fst.register_map());
2711 }
2712 }
2713
2714
2715 #ifndef PRODUCT
2716 // Deoptimization
2717 // Function for testing deoptimization
2718 void JavaThread::deoptimize() {
2719 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2720 StackFrameStream fst(this, UseBiasedLocking);
2721 bool deopt = false; // Dump stack only if a deopt actually happens.
2722 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2723 // Iterate over all frames in the thread and deoptimize
2724 for (; !fst.is_done(); fst.next()) {
2725 if (fst.current()->can_be_deoptimized()) {
2726
2727 if (only_at) {
2728 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2729 // consists of comma or carriage return separated numbers so
2730 // search for the current bci in that string.
2731 address pc = fst.current()->pc();
2732 nmethod* nm = (nmethod*) fst.current()->cb();
2733 ScopeDesc* sd = nm->scope_desc_at(pc);
2734 char buffer[8];
2735 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2736 size_t len = strlen(buffer);
2737 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2738 while (found != NULL) {
2739 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2740 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2741 // Check that the bci found is bracketed by terminators.
2742 break;
2743 }
2744 found = strstr(found + 1, buffer);
2745 }
2746 if (!found) {
2747 continue;
2748 }
2749 }
2750
2751 if (DebugDeoptimization && !deopt) {
2752 deopt = true; // One-time only print before deopt
2753 tty->print_cr("[BEFORE Deoptimization]");
2754 trace_frames();
2755 trace_stack();
2756 }
2757 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2758 }
2759 }
2760
2761 if (DebugDeoptimization && deopt) {
2762 tty->print_cr("[AFTER Deoptimization]");
2763 trace_frames();
2764 }
2765 }
2766
2767
2768 // Make zombies
2769 void JavaThread::make_zombies() {
2770 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2771 if (fst.current()->can_be_deoptimized()) {
2772 // it is a Java nmethod
2773 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2774 nm->make_not_entrant();
2775 }
2776 }
2777 }
2778 #endif // PRODUCT
2779
2780
2781 void JavaThread::deoptimized_wrt_marked_nmethods() {
2782 if (!has_last_Java_frame()) return;
2783 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2784 StackFrameStream fst(this, UseBiasedLocking);
2785 for (; !fst.is_done(); fst.next()) {
2786 if (fst.current()->should_be_deoptimized()) {
2787 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2788 }
2789 }
2790 }
2791
2792
2793 // If the caller is a NamedThread, then remember, in the current scope,
2794 // the given JavaThread in its _processed_thread field.
2795 class RememberProcessedThread: public StackObj {
2796 NamedThread* _cur_thr;
2797 public:
2798 RememberProcessedThread(JavaThread* jthr) {
2799 Thread* thread = Thread::current();
2800 if (thread->is_Named_thread()) {
2801 _cur_thr = (NamedThread *)thread;
2802 _cur_thr->set_processed_thread(jthr);
2803 } else {
2804 _cur_thr = NULL;
2805 }
2806 }
2807
2808 ~RememberProcessedThread() {
2809 if (_cur_thr) {
2810 _cur_thr->set_processed_thread(NULL);
2811 }
2812 }
2813 };
2814
2815 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2816 // Verify that the deferred card marks have been flushed.
2817 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2818
2819 // Traverse the GCHandles
2820 Thread::oops_do(f, cf);
2821
2822 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2823 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2824
2825 if (has_last_Java_frame()) {
2826 // Record JavaThread to GC thread
2827 RememberProcessedThread rpt(this);
2828
2829 // Traverse the privileged stack
2830 if (_privileged_stack_top != NULL) {
2831 _privileged_stack_top->oops_do(f);
2832 }
2833
2834 // traverse the registered growable array
2835 if (_array_for_gc != NULL) {
2836 for (int index = 0; index < _array_for_gc->length(); index++) {
2837 f->do_oop(_array_for_gc->adr_at(index));
2838 }
2839 }
2840
2841 // Traverse the monitor chunks
2842 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2843 chunk->oops_do(f);
2844 }
2845
2846 // Traverse the execution stack
2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2848 fst.current()->oops_do(f, cf, fst.register_map());
2849 }
2850 }
2851
2852 // callee_target is never live across a gc point so NULL it here should
2853 // it still contain a methdOop.
2854
2855 set_callee_target(NULL);
2856
2857 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2858 // If we have deferred set_locals there might be oops waiting to be
2859 // written
2860 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2861 if (list != NULL) {
2862 for (int i = 0; i < list->length(); i++) {
2863 list->at(i)->oops_do(f);
2864 }
2865 }
2866
2867 // Traverse instance variables at the end since the GC may be moving things
2868 // around using this function
2869 f->do_oop((oop*) &_threadObj);
2870 f->do_oop((oop*) &_vm_result);
2871 f->do_oop((oop*) &_exception_oop);
2872 f->do_oop((oop*) &_pending_async_exception);
2873
2874 if (jvmti_thread_state() != NULL) {
2875 jvmti_thread_state()->oops_do(f);
2876 }
2877 }
2878
2879 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2880 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2881 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2882
2883 if (has_last_Java_frame()) {
2884 // Traverse the execution stack
2885 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2886 fst.current()->nmethods_do(cf);
2887 }
2888 }
2889 }
2890
2891 void JavaThread::metadata_do(void f(Metadata*)) {
2892 if (has_last_Java_frame()) {
2893 // Traverse the execution stack to call f() on the methods in the stack
2894 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2895 fst.current()->metadata_do(f);
2896 }
2897 } else if (is_Compiler_thread()) {
2898 // need to walk ciMetadata in current compile tasks to keep alive.
2899 CompilerThread* ct = (CompilerThread*)this;
2900 if (ct->env() != NULL) {
2901 ct->env()->metadata_do(f);
2902 }
2903 CompileTask* task = ct->task();
2904 if (task != NULL) {
2905 task->metadata_do(f);
2906 }
2907 }
2908 }
2909
2910 // Printing
2911 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2912 switch (_thread_state) {
2913 case _thread_uninitialized: return "_thread_uninitialized";
2914 case _thread_new: return "_thread_new";
2915 case _thread_new_trans: return "_thread_new_trans";
2916 case _thread_in_native: return "_thread_in_native";
2917 case _thread_in_native_trans: return "_thread_in_native_trans";
2918 case _thread_in_vm: return "_thread_in_vm";
2919 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2920 case _thread_in_Java: return "_thread_in_Java";
2921 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2922 case _thread_blocked: return "_thread_blocked";
2923 case _thread_blocked_trans: return "_thread_blocked_trans";
2924 default: return "unknown thread state";
2925 }
2926 }
2927
2928 #ifndef PRODUCT
2929 void JavaThread::print_thread_state_on(outputStream *st) const {
2930 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2931 };
2932 void JavaThread::print_thread_state() const {
2933 print_thread_state_on(tty);
2934 }
2935 #endif // PRODUCT
2936
2937 // Called by Threads::print() for VM_PrintThreads operation
2938 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2939 st->print_raw("\"");
2940 st->print_raw(get_thread_name());
2941 st->print_raw("\" ");
2942 oop thread_oop = threadObj();
2943 if (thread_oop != NULL) {
2944 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2945 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2946 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2947 }
2948 Thread::print_on(st, print_extended_info);
2949 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2950 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2951 if (thread_oop != NULL) {
2952 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2953 }
2954 #ifndef PRODUCT
2955 print_thread_state_on(st);
2956 _safepoint_state->print_on(st);
2957 #endif // PRODUCT
2958 if (is_Compiler_thread()) {
2959 CompileTask *task = ((CompilerThread*)this)->task();
2960 if (task != NULL) {
2961 st->print(" Compiling: ");
2962 task->print(st, NULL, true, false);
2963 } else {
2964 st->print(" No compile task");
2965 }
2966 st->cr();
2967 }
2968 }
2969
2970 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2971 st->print("%s", get_thread_name_string(buf, buflen));
2972 }
2973
2974 // Called by fatal error handler. The difference between this and
2975 // JavaThread::print() is that we can't grab lock or allocate memory.
2976 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2977 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2978 oop thread_obj = threadObj();
2979 if (thread_obj != NULL) {
2980 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2981 }
2982 st->print(" [");
2983 st->print("%s", _get_thread_state_name(_thread_state));
2984 if (osthread()) {
2985 st->print(", id=%d", osthread()->thread_id());
2986 }
2987 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2988 p2i(stack_end()), p2i(stack_base()));
2989 st->print("]");
2990
2991 ThreadsSMRSupport::print_info_on(this, st);
2992 return;
2993 }
2994
2995 // Verification
2996
2997 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2998
2999 void JavaThread::verify() {
3000 // Verify oops in the thread.
3001 oops_do(&VerifyOopClosure::verify_oop, NULL);
3002
3003 // Verify the stack frames.
3004 frames_do(frame_verify);
3005 }
3006
3007 // CR 6300358 (sub-CR 2137150)
3008 // Most callers of this method assume that it can't return NULL but a
3009 // thread may not have a name whilst it is in the process of attaching to
3010 // the VM - see CR 6412693, and there are places where a JavaThread can be
3011 // seen prior to having it's threadObj set (eg JNI attaching threads and
3012 // if vm exit occurs during initialization). These cases can all be accounted
3013 // for such that this method never returns NULL.
3014 const char* JavaThread::get_thread_name() const {
3015 #ifdef ASSERT
3016 // early safepoints can hit while current thread does not yet have TLS
3017 if (!SafepointSynchronize::is_at_safepoint()) {
3018 Thread *cur = Thread::current();
3019 if (!(cur->is_Java_thread() && cur == this)) {
3020 // Current JavaThreads are allowed to get their own name without
3021 // the Threads_lock.
3022 assert_locked_or_safepoint(Threads_lock);
3023 }
3024 }
3025 #endif // ASSERT
3026 return get_thread_name_string();
3027 }
3028
3029 // Returns a non-NULL representation of this thread's name, or a suitable
3030 // descriptive string if there is no set name
3031 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3032 const char* name_str;
3033 oop thread_obj = threadObj();
3034 if (thread_obj != NULL) {
3035 oop name = java_lang_Thread::name(thread_obj);
3036 if (name != NULL) {
3037 if (buf == NULL) {
3038 name_str = java_lang_String::as_utf8_string(name);
3039 } else {
3040 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3041 }
3042 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3043 name_str = "<no-name - thread is attaching>";
3044 } else {
3045 name_str = Thread::name();
3046 }
3047 } else {
3048 name_str = Thread::name();
3049 }
3050 assert(name_str != NULL, "unexpected NULL thread name");
3051 return name_str;
3052 }
3053
3054
3055 const char* JavaThread::get_threadgroup_name() const {
3056 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3057 oop thread_obj = threadObj();
3058 if (thread_obj != NULL) {
3059 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3060 if (thread_group != NULL) {
3061 // ThreadGroup.name can be null
3062 return java_lang_ThreadGroup::name(thread_group);
3063 }
3064 }
3065 return NULL;
3066 }
3067
3068 const char* JavaThread::get_parent_name() const {
3069 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3070 oop thread_obj = threadObj();
3071 if (thread_obj != NULL) {
3072 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3073 if (thread_group != NULL) {
3074 oop parent = java_lang_ThreadGroup::parent(thread_group);
3075 if (parent != NULL) {
3076 // ThreadGroup.name can be null
3077 return java_lang_ThreadGroup::name(parent);
3078 }
3079 }
3080 }
3081 return NULL;
3082 }
3083
3084 ThreadPriority JavaThread::java_priority() const {
3085 oop thr_oop = threadObj();
3086 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3087 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3088 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3089 return priority;
3090 }
3091
3092 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3093
3094 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3095 // Link Java Thread object <-> C++ Thread
3096
3097 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3098 // and put it into a new Handle. The Handle "thread_oop" can then
3099 // be used to pass the C++ thread object to other methods.
3100
3101 // Set the Java level thread object (jthread) field of the
3102 // new thread (a JavaThread *) to C++ thread object using the
3103 // "thread_oop" handle.
3104
3105 // Set the thread field (a JavaThread *) of the
3106 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3107
3108 Handle thread_oop(Thread::current(),
3109 JNIHandles::resolve_non_null(jni_thread));
3110 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3111 "must be initialized");
3112 set_threadObj(thread_oop());
3113 java_lang_Thread::set_thread(thread_oop(), this);
3114
3115 if (prio == NoPriority) {
3116 prio = java_lang_Thread::priority(thread_oop());
3117 assert(prio != NoPriority, "A valid priority should be present");
3118 }
3119
3120 // Push the Java priority down to the native thread; needs Threads_lock
3121 Thread::set_priority(this, prio);
3122
3123 // Add the new thread to the Threads list and set it in motion.
3124 // We must have threads lock in order to call Threads::add.
3125 // It is crucial that we do not block before the thread is
3126 // added to the Threads list for if a GC happens, then the java_thread oop
3127 // will not be visited by GC.
3128 Threads::add(this);
3129 }
3130
3131 oop JavaThread::current_park_blocker() {
3132 // Support for JSR-166 locks
3133 oop thread_oop = threadObj();
3134 if (thread_oop != NULL &&
3135 JDK_Version::current().supports_thread_park_blocker()) {
3136 return java_lang_Thread::park_blocker(thread_oop);
3137 }
3138 return NULL;
3139 }
3140
3141
3142 void JavaThread::print_stack_on(outputStream* st) {
3143 if (!has_last_Java_frame()) return;
3144 ResourceMark rm;
3145 HandleMark hm;
3146
3147 RegisterMap reg_map(this);
3148 vframe* start_vf = last_java_vframe(®_map);
3149 int count = 0;
3150 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3151 if (f->is_java_frame()) {
3152 javaVFrame* jvf = javaVFrame::cast(f);
3153 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3154
3155 // Print out lock information
3156 if (JavaMonitorsInStackTrace) {
3157 jvf->print_lock_info_on(st, count);
3158 }
3159 } else {
3160 // Ignore non-Java frames
3161 }
3162
3163 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3164 count++;
3165 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3166 }
3167 }
3168
3169
3170 // JVMTI PopFrame support
3171 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3172 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3173 if (in_bytes(size_in_bytes) != 0) {
3174 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3175 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3176 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3177 }
3178 }
3179
3180 void* JavaThread::popframe_preserved_args() {
3181 return _popframe_preserved_args;
3182 }
3183
3184 ByteSize JavaThread::popframe_preserved_args_size() {
3185 return in_ByteSize(_popframe_preserved_args_size);
3186 }
3187
3188 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3189 int sz = in_bytes(popframe_preserved_args_size());
3190 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3191 return in_WordSize(sz / wordSize);
3192 }
3193
3194 void JavaThread::popframe_free_preserved_args() {
3195 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3196 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3197 _popframe_preserved_args = NULL;
3198 _popframe_preserved_args_size = 0;
3199 }
3200
3201 #ifndef PRODUCT
3202
3203 void JavaThread::trace_frames() {
3204 tty->print_cr("[Describe stack]");
3205 int frame_no = 1;
3206 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3207 tty->print(" %d. ", frame_no++);
3208 fst.current()->print_value_on(tty, this);
3209 tty->cr();
3210 }
3211 }
3212
3213 class PrintAndVerifyOopClosure: public OopClosure {
3214 protected:
3215 template <class T> inline void do_oop_work(T* p) {
3216 oop obj = RawAccess<>::oop_load(p);
3217 if (obj == NULL) return;
3218 tty->print(INTPTR_FORMAT ": ", p2i(p));
3219 if (oopDesc::is_oop_or_null(obj)) {
3220 if (obj->is_objArray()) {
3221 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3222 } else {
3223 obj->print();
3224 }
3225 } else {
3226 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3227 }
3228 tty->cr();
3229 }
3230 public:
3231 virtual void do_oop(oop* p) { do_oop_work(p); }
3232 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3233 };
3234
3235
3236 static void oops_print(frame* f, const RegisterMap *map) {
3237 PrintAndVerifyOopClosure print;
3238 f->print_value();
3239 f->oops_do(&print, NULL, (RegisterMap*)map);
3240 }
3241
3242 // Print our all the locations that contain oops and whether they are
3243 // valid or not. This useful when trying to find the oldest frame
3244 // where an oop has gone bad since the frame walk is from youngest to
3245 // oldest.
3246 void JavaThread::trace_oops() {
3247 tty->print_cr("[Trace oops]");
3248 frames_do(oops_print);
3249 }
3250
3251
3252 #ifdef ASSERT
3253 // Print or validate the layout of stack frames
3254 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3255 ResourceMark rm;
3256 PRESERVE_EXCEPTION_MARK;
3257 FrameValues values;
3258 int frame_no = 0;
3259 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3260 fst.current()->describe(values, ++frame_no);
3261 if (depth == frame_no) break;
3262 }
3263 if (validate_only) {
3264 values.validate();
3265 } else {
3266 tty->print_cr("[Describe stack layout]");
3267 values.print(this);
3268 }
3269 }
3270 #endif
3271
3272 void JavaThread::trace_stack_from(vframe* start_vf) {
3273 ResourceMark rm;
3274 int vframe_no = 1;
3275 for (vframe* f = start_vf; f; f = f->sender()) {
3276 if (f->is_java_frame()) {
3277 javaVFrame::cast(f)->print_activation(vframe_no++);
3278 } else {
3279 f->print();
3280 }
3281 if (vframe_no > StackPrintLimit) {
3282 tty->print_cr("...<more frames>...");
3283 return;
3284 }
3285 }
3286 }
3287
3288
3289 void JavaThread::trace_stack() {
3290 if (!has_last_Java_frame()) return;
3291 ResourceMark rm;
3292 HandleMark hm;
3293 RegisterMap reg_map(this);
3294 trace_stack_from(last_java_vframe(®_map));
3295 }
3296
3297
3298 #endif // PRODUCT
3299
3300
3301 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3302 assert(reg_map != NULL, "a map must be given");
3303 frame f = last_frame();
3304 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3305 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3306 }
3307 return NULL;
3308 }
3309
3310
3311 Klass* JavaThread::security_get_caller_class(int depth) {
3312 vframeStream vfst(this);
3313 vfst.security_get_caller_frame(depth);
3314 if (!vfst.at_end()) {
3315 return vfst.method()->method_holder();
3316 }
3317 return NULL;
3318 }
3319
3320 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3321 assert(thread->is_Compiler_thread(), "must be compiler thread");
3322 CompileBroker::compiler_thread_loop();
3323 }
3324
3325 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3326 NMethodSweeper::sweeper_loop();
3327 }
3328
3329 // Create a CompilerThread
3330 CompilerThread::CompilerThread(CompileQueue* queue,
3331 CompilerCounters* counters)
3332 : JavaThread(&compiler_thread_entry) {
3333 _env = NULL;
3334 _log = NULL;
3335 _task = NULL;
3336 _queue = queue;
3337 _counters = counters;
3338 _buffer_blob = NULL;
3339 _compiler = NULL;
3340
3341 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3342 resource_area()->bias_to(mtCompiler);
3343
3344 #ifndef PRODUCT
3345 _ideal_graph_printer = NULL;
3346 #endif
3347 }
3348
3349 CompilerThread::~CompilerThread() {
3350 // Delete objects which were allocated on heap.
3351 delete _counters;
3352 }
3353
3354 bool CompilerThread::can_call_java() const {
3355 return _compiler != NULL && _compiler->is_jvmci();
3356 }
3357
3358 // Create sweeper thread
3359 CodeCacheSweeperThread::CodeCacheSweeperThread()
3360 : JavaThread(&sweeper_thread_entry) {
3361 _scanned_compiled_method = NULL;
3362 }
3363
3364 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3365 JavaThread::oops_do(f, cf);
3366 if (_scanned_compiled_method != NULL && cf != NULL) {
3367 // Safepoints can occur when the sweeper is scanning an nmethod so
3368 // process it here to make sure it isn't unloaded in the middle of
3369 // a scan.
3370 cf->do_code_blob(_scanned_compiled_method);
3371 }
3372 }
3373
3374 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3375 JavaThread::nmethods_do(cf);
3376 if (_scanned_compiled_method != NULL && cf != NULL) {
3377 // Safepoints can occur when the sweeper is scanning an nmethod so
3378 // process it here to make sure it isn't unloaded in the middle of
3379 // a scan.
3380 cf->do_code_blob(_scanned_compiled_method);
3381 }
3382 }
3383
3384
3385 // ======= Threads ========
3386
3387 // The Threads class links together all active threads, and provides
3388 // operations over all threads. It is protected by the Threads_lock,
3389 // which is also used in other global contexts like safepointing.
3390 // ThreadsListHandles are used to safely perform operations on one
3391 // or more threads without the risk of the thread exiting during the
3392 // operation.
3393 //
3394 // Note: The Threads_lock is currently more widely used than we
3395 // would like. We are actively migrating Threads_lock uses to other
3396 // mechanisms in order to reduce Threads_lock contention.
3397
3398 JavaThread* Threads::_thread_list = NULL;
3399 int Threads::_number_of_threads = 0;
3400 int Threads::_number_of_non_daemon_threads = 0;
3401 int Threads::_return_code = 0;
3402 int Threads::_thread_claim_parity = 0;
3403 size_t JavaThread::_stack_size_at_create = 0;
3404
3405 #ifdef ASSERT
3406 bool Threads::_vm_complete = false;
3407 size_t Threads::_threads_before_barrier_set = 0;
3408 #endif
3409
3410 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3411 Prefetch::read((void*)addr, prefetch_interval);
3412 return *addr;
3413 }
3414
3415 // Possibly the ugliest for loop the world has seen. C++ does not allow
3416 // multiple types in the declaration section of the for loop. In this case
3417 // we are only dealing with pointers and hence can cast them. It looks ugly
3418 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3419 #define DO_JAVA_THREADS(LIST, X) \
3420 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3421 *MACRO_list = (JavaThread*)(LIST), \
3422 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3423 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3424 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3425 MACRO_current_p != MACRO_end; \
3426 MACRO_current_p++, \
3427 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3428
3429 // All JavaThreads
3430 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3431
3432 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3433 void Threads::non_java_threads_do(ThreadClosure* tc) {
3434 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3435 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3436 tc->do_thread(njti.current());
3437 }
3438 }
3439
3440 // All JavaThreads
3441 void Threads::java_threads_do(ThreadClosure* tc) {
3442 assert_locked_or_safepoint(Threads_lock);
3443 // ALL_JAVA_THREADS iterates through all JavaThreads.
3444 ALL_JAVA_THREADS(p) {
3445 tc->do_thread(p);
3446 }
3447 }
3448
3449 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3450 assert_locked_or_safepoint(Threads_lock);
3451 java_threads_do(tc);
3452 tc->do_thread(VMThread::vm_thread());
3453 }
3454
3455 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3456 void Threads::threads_do(ThreadClosure* tc) {
3457 assert_locked_or_safepoint(Threads_lock);
3458 java_threads_do(tc);
3459 non_java_threads_do(tc);
3460 }
3461
3462 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3463 int cp = Threads::thread_claim_parity();
3464 ALL_JAVA_THREADS(p) {
3465 if (p->claim_oops_do(is_par, cp)) {
3466 tc->do_thread(p);
3467 }
3468 }
3469 VMThread* vmt = VMThread::vm_thread();
3470 if (vmt->claim_oops_do(is_par, cp)) {
3471 tc->do_thread(vmt);
3472 }
3473 }
3474
3475 // The system initialization in the library has three phases.
3476 //
3477 // Phase 1: java.lang.System class initialization
3478 // java.lang.System is a primordial class loaded and initialized
3479 // by the VM early during startup. java.lang.System.<clinit>
3480 // only does registerNatives and keeps the rest of the class
3481 // initialization work later until thread initialization completes.
3482 //
3483 // System.initPhase1 initializes the system properties, the static
3484 // fields in, out, and err. Set up java signal handlers, OS-specific
3485 // system settings, and thread group of the main thread.
3486 static void call_initPhase1(TRAPS) {
3487 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3488 JavaValue result(T_VOID);
3489 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3490 vmSymbols::void_method_signature(), CHECK);
3491 }
3492
3493 // Phase 2. Module system initialization
3494 // This will initialize the module system. Only java.base classes
3495 // can be loaded until phase 2 completes.
3496 //
3497 // Call System.initPhase2 after the compiler initialization and jsr292
3498 // classes get initialized because module initialization runs a lot of java
3499 // code, that for performance reasons, should be compiled. Also, this will
3500 // enable the startup code to use lambda and other language features in this
3501 // phase and onward.
3502 //
3503 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3504 static void call_initPhase2(TRAPS) {
3505 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3506
3507 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3508
3509 JavaValue result(T_INT);
3510 JavaCallArguments args;
3511 args.push_int(DisplayVMOutputToStderr);
3512 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3513 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3514 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3515 if (result.get_jint() != JNI_OK) {
3516 vm_exit_during_initialization(); // no message or exception
3517 }
3518
3519 universe_post_module_init();
3520 }
3521
3522 // Phase 3. final setup - set security manager, system class loader and TCCL
3523 //
3524 // This will instantiate and set the security manager, set the system class
3525 // loader as well as the thread context class loader. The security manager
3526 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3527 // other modules or the application's classpath.
3528 static void call_initPhase3(TRAPS) {
3529 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3530 JavaValue result(T_VOID);
3531 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3532 vmSymbols::void_method_signature(), CHECK);
3533 }
3534
3535 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3536 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3537
3538 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3539 create_vm_init_libraries();
3540 }
3541
3542 initialize_class(vmSymbols::java_lang_String(), CHECK);
3543
3544 // Inject CompactStrings value after the static initializers for String ran.
3545 java_lang_String::set_compact_strings(CompactStrings);
3546
3547 // Initialize java_lang.System (needed before creating the thread)
3548 initialize_class(vmSymbols::java_lang_System(), CHECK);
3549 // The VM creates & returns objects of this class. Make sure it's initialized.
3550 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3551 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3552 Handle thread_group = create_initial_thread_group(CHECK);
3553 Universe::set_main_thread_group(thread_group());
3554 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3555 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3556 main_thread->set_threadObj(thread_object);
3557 // Set thread status to running since main thread has
3558 // been started and running.
3559 java_lang_Thread::set_thread_status(thread_object,
3560 java_lang_Thread::RUNNABLE);
3561
3562 // The VM creates objects of this class.
3563 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3564
3565 // The VM preresolves methods to these classes. Make sure that they get initialized
3566 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3567 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3568
3569 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3570 call_initPhase1(CHECK);
3571
3572 // get the Java runtime name after java.lang.System is initialized
3573 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3574 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3575
3576 // an instance of OutOfMemory exception has been allocated earlier
3577 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3578 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3579 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3580 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3581 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3582 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3583 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3584 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3585 }
3586
3587 void Threads::initialize_jsr292_core_classes(TRAPS) {
3588 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3589
3590 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3591 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3592 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3593 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3594 }
3595
3596 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3597 extern void JDK_Version_init();
3598
3599 // Preinitialize version info.
3600 VM_Version::early_initialize();
3601
3602 // Check version
3603 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3604
3605 // Initialize library-based TLS
3606 ThreadLocalStorage::init();
3607
3608 // Initialize the output stream module
3609 ostream_init();
3610
3611 // Process java launcher properties.
3612 Arguments::process_sun_java_launcher_properties(args);
3613
3614 // Initialize the os module
3615 os::init();
3616
3617 // Record VM creation timing statistics
3618 TraceVmCreationTime create_vm_timer;
3619 create_vm_timer.start();
3620
3621 // Initialize system properties.
3622 Arguments::init_system_properties();
3623
3624 // So that JDK version can be used as a discriminator when parsing arguments
3625 JDK_Version_init();
3626
3627 // Update/Initialize System properties after JDK version number is known
3628 Arguments::init_version_specific_system_properties();
3629
3630 // Make sure to initialize log configuration *before* parsing arguments
3631 LogConfiguration::initialize(create_vm_timer.begin_time());
3632
3633 // Parse arguments
3634 // Note: this internally calls os::init_container_support()
3635 jint parse_result = Arguments::parse(args);
3636 if (parse_result != JNI_OK) return parse_result;
3637
3638 os::init_before_ergo();
3639
3640 jint ergo_result = Arguments::apply_ergo();
3641 if (ergo_result != JNI_OK) return ergo_result;
3642
3643 // Final check of all ranges after ergonomics which may change values.
3644 if (!JVMFlagRangeList::check_ranges()) {
3645 return JNI_EINVAL;
3646 }
3647
3648 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3649 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3650 if (!constraint_result) {
3651 return JNI_EINVAL;
3652 }
3653
3654 JVMFlagWriteableList::mark_startup();
3655
3656 if (PauseAtStartup) {
3657 os::pause();
3658 }
3659
3660 HOTSPOT_VM_INIT_BEGIN();
3661
3662 // Timing (must come after argument parsing)
3663 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3664
3665 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3666 // Initialize assert poison page mechanism.
3667 if (ShowRegistersOnAssert) {
3668 initialize_assert_poison();
3669 }
3670 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3671
3672 // Initialize the os module after parsing the args
3673 jint os_init_2_result = os::init_2();
3674 if (os_init_2_result != JNI_OK) return os_init_2_result;
3675
3676 SafepointMechanism::initialize();
3677
3678 jint adjust_after_os_result = Arguments::adjust_after_os();
3679 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3680
3681 // Initialize output stream logging
3682 ostream_init_log();
3683
3684 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3685 // Must be before create_vm_init_agents()
3686 if (Arguments::init_libraries_at_startup()) {
3687 convert_vm_init_libraries_to_agents();
3688 }
3689
3690 // Launch -agentlib/-agentpath and converted -Xrun agents
3691 if (Arguments::init_agents_at_startup()) {
3692 create_vm_init_agents();
3693 }
3694
3695 // Initialize Threads state
3696 _thread_list = NULL;
3697 _number_of_threads = 0;
3698 _number_of_non_daemon_threads = 0;
3699
3700 // Initialize global data structures and create system classes in heap
3701 vm_init_globals();
3702
3703 #if INCLUDE_JVMCI
3704 if (JVMCICounterSize > 0) {
3705 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3706 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3707 } else {
3708 JavaThread::_jvmci_old_thread_counters = NULL;
3709 }
3710 #endif // INCLUDE_JVMCI
3711
3712 // Attach the main thread to this os thread
3713 JavaThread* main_thread = new JavaThread();
3714 main_thread->set_thread_state(_thread_in_vm);
3715 main_thread->initialize_thread_current();
3716 // must do this before set_active_handles
3717 main_thread->record_stack_base_and_size();
3718 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3719
3720 if (!main_thread->set_as_starting_thread()) {
3721 vm_shutdown_during_initialization(
3722 "Failed necessary internal allocation. Out of swap space");
3723 main_thread->smr_delete();
3724 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3725 return JNI_ENOMEM;
3726 }
3727
3728 // Enable guard page *after* os::create_main_thread(), otherwise it would
3729 // crash Linux VM, see notes in os_linux.cpp.
3730 main_thread->create_stack_guard_pages();
3731
3732 // Initialize Java-Level synchronization subsystem
3733 ObjectMonitor::Initialize();
3734
3735 // Initialize global modules
3736 jint status = init_globals();
3737 if (status != JNI_OK) {
3738 main_thread->smr_delete();
3739 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3740 return status;
3741 }
3742
3743 JFR_ONLY(Jfr::on_vm_init();)
3744
3745 // Should be done after the heap is fully created
3746 main_thread->cache_global_variables();
3747
3748 HandleMark hm;
3749
3750 { MutexLocker mu(Threads_lock);
3751 Threads::add(main_thread);
3752 }
3753
3754 // Any JVMTI raw monitors entered in onload will transition into
3755 // real raw monitor. VM is setup enough here for raw monitor enter.
3756 JvmtiExport::transition_pending_onload_raw_monitors();
3757
3758 // Create the VMThread
3759 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3760
3761 VMThread::create();
3762 Thread* vmthread = VMThread::vm_thread();
3763
3764 if (!os::create_thread(vmthread, os::vm_thread)) {
3765 vm_exit_during_initialization("Cannot create VM thread. "
3766 "Out of system resources.");
3767 }
3768
3769 // Wait for the VM thread to become ready, and VMThread::run to initialize
3770 // Monitors can have spurious returns, must always check another state flag
3771 {
3772 MutexLocker ml(Notify_lock);
3773 os::start_thread(vmthread);
3774 while (vmthread->active_handles() == NULL) {
3775 Notify_lock->wait();
3776 }
3777 }
3778 }
3779
3780 assert(Universe::is_fully_initialized(), "not initialized");
3781 if (VerifyDuringStartup) {
3782 // Make sure we're starting with a clean slate.
3783 VM_Verify verify_op;
3784 VMThread::execute(&verify_op);
3785 }
3786
3787 // We need this to update the java.vm.info property in case any flags used
3788 // to initially define it have been changed. This is needed for both CDS and
3789 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3790 // is initially computed. See Abstract_VM_Version::vm_info_string().
3791 // This update must happen before we initialize the java classes, but
3792 // after any initialization logic that might modify the flags.
3793 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3794
3795 Thread* THREAD = Thread::current();
3796
3797 // Always call even when there are not JVMTI environments yet, since environments
3798 // may be attached late and JVMTI must track phases of VM execution
3799 JvmtiExport::enter_early_start_phase();
3800
3801 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3802 JvmtiExport::post_early_vm_start();
3803
3804 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3805
3806 quicken_jni_functions();
3807
3808 // No more stub generation allowed after that point.
3809 StubCodeDesc::freeze();
3810
3811 // Set flag that basic initialization has completed. Used by exceptions and various
3812 // debug stuff, that does not work until all basic classes have been initialized.
3813 set_init_completed();
3814
3815 LogConfiguration::post_initialize();
3816 Metaspace::post_initialize();
3817
3818 HOTSPOT_VM_INIT_END();
3819
3820 // record VM initialization completion time
3821 #if INCLUDE_MANAGEMENT
3822 Management::record_vm_init_completed();
3823 #endif // INCLUDE_MANAGEMENT
3824
3825 // Signal Dispatcher needs to be started before VMInit event is posted
3826 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3827
3828 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3829 if (!DisableAttachMechanism) {
3830 AttachListener::vm_start();
3831 if (StartAttachListener || AttachListener::init_at_startup()) {
3832 AttachListener::init();
3833 }
3834 }
3835
3836 // Launch -Xrun agents
3837 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3838 // back-end can launch with -Xdebug -Xrunjdwp.
3839 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3840 create_vm_init_libraries();
3841 }
3842
3843 if (CleanChunkPoolAsync) {
3844 Chunk::start_chunk_pool_cleaner_task();
3845 }
3846
3847 // initialize compiler(s)
3848 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3849 #if INCLUDE_JVMCI
3850 bool force_JVMCI_intialization = false;
3851 if (EnableJVMCI) {
3852 // Initialize JVMCI eagerly when it is explicitly requested.
3853 // Or when JVMCIPrintProperties is enabled.
3854 // The JVMCI Java initialization code will read this flag and
3855 // do the printing if it's set.
3856 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3857
3858 if (!force_JVMCI_intialization) {
3859 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3860 // compilations via JVMCI will not actually block until JVMCI is initialized.
3861 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3862 }
3863 }
3864 #endif
3865 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3866 // Postpone completion of compiler initialization to after JVMCI
3867 // is initialized to avoid timeouts of blocking compilations.
3868 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3869 CompileBroker::compilation_init_phase2();
3870 }
3871 #endif
3872
3873 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3874 // It is done after compilers are initialized, because otherwise compilations of
3875 // signature polymorphic MH intrinsics can be missed
3876 // (see SystemDictionary::find_method_handle_intrinsic).
3877 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3878
3879 // This will initialize the module system. Only java.base classes can be
3880 // loaded until phase 2 completes
3881 call_initPhase2(CHECK_JNI_ERR);
3882
3883 // Always call even when there are not JVMTI environments yet, since environments
3884 // may be attached late and JVMTI must track phases of VM execution
3885 JvmtiExport::enter_start_phase();
3886
3887 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3888 JvmtiExport::post_vm_start();
3889
3890 // Final system initialization including security manager and system class loader
3891 call_initPhase3(CHECK_JNI_ERR);
3892
3893 // cache the system and platform class loaders
3894 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3895
3896 #if INCLUDE_CDS
3897 if (DumpSharedSpaces) {
3898 // capture the module path info from the ModuleEntryTable
3899 ClassLoader::initialize_module_path(THREAD);
3900 }
3901 #endif
3902
3903 #if INCLUDE_JVMCI
3904 if (force_JVMCI_intialization) {
3905 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3906 CompileBroker::compilation_init_phase2();
3907 }
3908 #endif
3909
3910 // Always call even when there are not JVMTI environments yet, since environments
3911 // may be attached late and JVMTI must track phases of VM execution
3912 JvmtiExport::enter_live_phase();
3913
3914 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3915 JvmtiExport::post_vm_initialized();
3916
3917 JFR_ONLY(Jfr::on_vm_start();)
3918
3919 #if INCLUDE_MANAGEMENT
3920 Management::initialize(THREAD);
3921
3922 if (HAS_PENDING_EXCEPTION) {
3923 // management agent fails to start possibly due to
3924 // configuration problem and is responsible for printing
3925 // stack trace if appropriate. Simply exit VM.
3926 vm_exit(1);
3927 }
3928 #endif // INCLUDE_MANAGEMENT
3929
3930 if (MemProfiling) MemProfiler::engage();
3931 StatSampler::engage();
3932 if (CheckJNICalls) JniPeriodicChecker::engage();
3933
3934 BiasedLocking::init();
3935
3936 #if INCLUDE_RTM_OPT
3937 RTMLockingCounters::init();
3938 #endif
3939
3940 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3941 call_postVMInitHook(THREAD);
3942 // The Java side of PostVMInitHook.run must deal with all
3943 // exceptions and provide means of diagnosis.
3944 if (HAS_PENDING_EXCEPTION) {
3945 CLEAR_PENDING_EXCEPTION;
3946 }
3947 }
3948
3949 {
3950 MutexLocker ml(PeriodicTask_lock);
3951 // Make sure the WatcherThread can be started by WatcherThread::start()
3952 // or by dynamic enrollment.
3953 WatcherThread::make_startable();
3954 // Start up the WatcherThread if there are any periodic tasks
3955 // NOTE: All PeriodicTasks should be registered by now. If they
3956 // aren't, late joiners might appear to start slowly (we might
3957 // take a while to process their first tick).
3958 if (PeriodicTask::num_tasks() > 0) {
3959 WatcherThread::start();
3960 }
3961 }
3962
3963 create_vm_timer.end();
3964 #ifdef ASSERT
3965 _vm_complete = true;
3966 #endif
3967
3968 if (DumpSharedSpaces) {
3969 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3970 ShouldNotReachHere();
3971 }
3972
3973 return JNI_OK;
3974 }
3975
3976 // type for the Agent_OnLoad and JVM_OnLoad entry points
3977 extern "C" {
3978 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3979 }
3980 // Find a command line agent library and return its entry point for
3981 // -agentlib: -agentpath: -Xrun
3982 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3983 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3984 const char *on_load_symbols[],
3985 size_t num_symbol_entries) {
3986 OnLoadEntry_t on_load_entry = NULL;
3987 void *library = NULL;
3988
3989 if (!agent->valid()) {
3990 char buffer[JVM_MAXPATHLEN];
3991 char ebuf[1024] = "";
3992 const char *name = agent->name();
3993 const char *msg = "Could not find agent library ";
3994
3995 // First check to see if agent is statically linked into executable
3996 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3997 library = agent->os_lib();
3998 } else if (agent->is_absolute_path()) {
3999 library = os::dll_load(name, ebuf, sizeof ebuf);
4000 if (library == NULL) {
4001 const char *sub_msg = " in absolute path, with error: ";
4002 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4003 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4004 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4005 // If we can't find the agent, exit.
4006 vm_exit_during_initialization(buf, NULL);
4007 FREE_C_HEAP_ARRAY(char, buf);
4008 }
4009 } else {
4010 // Try to load the agent from the standard dll directory
4011 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4012 name)) {
4013 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4014 }
4015 if (library == NULL) { // Try the library path directory.
4016 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4017 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4018 }
4019 if (library == NULL) {
4020 const char *sub_msg = " on the library path, with error: ";
4021 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4022
4023 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4024 strlen(ebuf) + strlen(sub_msg2) + 1;
4025 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4026 if (!agent->is_instrument_lib()) {
4027 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4028 } else {
4029 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4030 }
4031 // If we can't find the agent, exit.
4032 vm_exit_during_initialization(buf, NULL);
4033 FREE_C_HEAP_ARRAY(char, buf);
4034 }
4035 }
4036 }
4037 agent->set_os_lib(library);
4038 agent->set_valid();
4039 }
4040
4041 // Find the OnLoad function.
4042 on_load_entry =
4043 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4044 false,
4045 on_load_symbols,
4046 num_symbol_entries));
4047 return on_load_entry;
4048 }
4049
4050 // Find the JVM_OnLoad entry point
4051 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4052 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4053 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4054 }
4055
4056 // Find the Agent_OnLoad entry point
4057 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4058 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4059 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4060 }
4061
4062 // For backwards compatibility with -Xrun
4063 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4064 // treated like -agentpath:
4065 // Must be called before agent libraries are created
4066 void Threads::convert_vm_init_libraries_to_agents() {
4067 AgentLibrary* agent;
4068 AgentLibrary* next;
4069
4070 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4071 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4072 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4073
4074 // If there is an JVM_OnLoad function it will get called later,
4075 // otherwise see if there is an Agent_OnLoad
4076 if (on_load_entry == NULL) {
4077 on_load_entry = lookup_agent_on_load(agent);
4078 if (on_load_entry != NULL) {
4079 // switch it to the agent list -- so that Agent_OnLoad will be called,
4080 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4081 Arguments::convert_library_to_agent(agent);
4082 } else {
4083 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4084 }
4085 }
4086 }
4087 }
4088
4089 // Create agents for -agentlib: -agentpath: and converted -Xrun
4090 // Invokes Agent_OnLoad
4091 // Called very early -- before JavaThreads exist
4092 void Threads::create_vm_init_agents() {
4093 extern struct JavaVM_ main_vm;
4094 AgentLibrary* agent;
4095
4096 JvmtiExport::enter_onload_phase();
4097
4098 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4099 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4100
4101 if (on_load_entry != NULL) {
4102 // Invoke the Agent_OnLoad function
4103 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4104 if (err != JNI_OK) {
4105 vm_exit_during_initialization("agent library failed to init", agent->name());
4106 }
4107 } else {
4108 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4109 }
4110 }
4111 JvmtiExport::enter_primordial_phase();
4112 }
4113
4114 extern "C" {
4115 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4116 }
4117
4118 void Threads::shutdown_vm_agents() {
4119 // Send any Agent_OnUnload notifications
4120 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4121 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4122 extern struct JavaVM_ main_vm;
4123 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4124
4125 // Find the Agent_OnUnload function.
4126 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4127 os::find_agent_function(agent,
4128 false,
4129 on_unload_symbols,
4130 num_symbol_entries));
4131
4132 // Invoke the Agent_OnUnload function
4133 if (unload_entry != NULL) {
4134 JavaThread* thread = JavaThread::current();
4135 ThreadToNativeFromVM ttn(thread);
4136 HandleMark hm(thread);
4137 (*unload_entry)(&main_vm);
4138 }
4139 }
4140 }
4141
4142 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4143 // Invokes JVM_OnLoad
4144 void Threads::create_vm_init_libraries() {
4145 extern struct JavaVM_ main_vm;
4146 AgentLibrary* agent;
4147
4148 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4149 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4150
4151 if (on_load_entry != NULL) {
4152 // Invoke the JVM_OnLoad function
4153 JavaThread* thread = JavaThread::current();
4154 ThreadToNativeFromVM ttn(thread);
4155 HandleMark hm(thread);
4156 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4157 if (err != JNI_OK) {
4158 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4159 }
4160 } else {
4161 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4162 }
4163 }
4164 }
4165
4166
4167 // Last thread running calls java.lang.Shutdown.shutdown()
4168 void JavaThread::invoke_shutdown_hooks() {
4169 HandleMark hm(this);
4170
4171 // We could get here with a pending exception, if so clear it now.
4172 if (this->has_pending_exception()) {
4173 this->clear_pending_exception();
4174 }
4175
4176 EXCEPTION_MARK;
4177 Klass* shutdown_klass =
4178 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4179 THREAD);
4180 if (shutdown_klass != NULL) {
4181 // SystemDictionary::resolve_or_null will return null if there was
4182 // an exception. If we cannot load the Shutdown class, just don't
4183 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4184 // won't be run. Note that if a shutdown hook was registered,
4185 // the Shutdown class would have already been loaded
4186 // (Runtime.addShutdownHook will load it).
4187 JavaValue result(T_VOID);
4188 JavaCalls::call_static(&result,
4189 shutdown_klass,
4190 vmSymbols::shutdown_method_name(),
4191 vmSymbols::void_method_signature(),
4192 THREAD);
4193 }
4194 CLEAR_PENDING_EXCEPTION;
4195 }
4196
4197 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4198 // the program falls off the end of main(). Another VM exit path is through
4199 // vm_exit() when the program calls System.exit() to return a value or when
4200 // there is a serious error in VM. The two shutdown paths are not exactly
4201 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4202 // and VM_Exit op at VM level.
4203 //
4204 // Shutdown sequence:
4205 // + Shutdown native memory tracking if it is on
4206 // + Wait until we are the last non-daemon thread to execute
4207 // <-- every thing is still working at this moment -->
4208 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4209 // shutdown hooks
4210 // + Call before_exit(), prepare for VM exit
4211 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4212 // currently the only user of this mechanism is File.deleteOnExit())
4213 // > stop StatSampler, watcher thread, CMS threads,
4214 // post thread end and vm death events to JVMTI,
4215 // stop signal thread
4216 // + Call JavaThread::exit(), it will:
4217 // > release JNI handle blocks, remove stack guard pages
4218 // > remove this thread from Threads list
4219 // <-- no more Java code from this thread after this point -->
4220 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4221 // the compiler threads at safepoint
4222 // <-- do not use anything that could get blocked by Safepoint -->
4223 // + Disable tracing at JNI/JVM barriers
4224 // + Set _vm_exited flag for threads that are still running native code
4225 // + Delete this thread
4226 // + Call exit_globals()
4227 // > deletes tty
4228 // > deletes PerfMemory resources
4229 // + Return to caller
4230
4231 bool Threads::destroy_vm() {
4232 JavaThread* thread = JavaThread::current();
4233
4234 #ifdef ASSERT
4235 _vm_complete = false;
4236 #endif
4237 // Wait until we are the last non-daemon thread to execute
4238 { MutexLocker nu(Threads_lock);
4239 while (Threads::number_of_non_daemon_threads() > 1)
4240 // This wait should make safepoint checks, wait without a timeout,
4241 // and wait as a suspend-equivalent condition.
4242 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4243 Mutex::_as_suspend_equivalent_flag);
4244 }
4245
4246 EventShutdown e;
4247 if (e.should_commit()) {
4248 e.set_reason("No remaining non-daemon Java threads");
4249 e.commit();
4250 }
4251
4252 // Hang forever on exit if we are reporting an error.
4253 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4254 os::infinite_sleep();
4255 }
4256 os::wait_for_keypress_at_exit();
4257
4258 // run Java level shutdown hooks
4259 thread->invoke_shutdown_hooks();
4260
4261 before_exit(thread);
4262
4263 thread->exit(true);
4264 // thread will never call smr_delete, instead of implicit cancel
4265 // in wait_for_vm_thread_exit we do it explicit.
4266 thread->cancel_handshake();
4267
4268 // Stop VM thread.
4269 {
4270 // 4945125 The vm thread comes to a safepoint during exit.
4271 // GC vm_operations can get caught at the safepoint, and the
4272 // heap is unparseable if they are caught. Grab the Heap_lock
4273 // to prevent this. The GC vm_operations will not be able to
4274 // queue until after the vm thread is dead. After this point,
4275 // we'll never emerge out of the safepoint before the VM exits.
4276
4277 MutexLocker ml(Heap_lock);
4278
4279 VMThread::wait_for_vm_thread_exit();
4280 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4281 VMThread::destroy();
4282 }
4283
4284 // Now, all Java threads are gone except daemon threads. Daemon threads
4285 // running Java code or in VM are stopped by the Safepoint. However,
4286 // daemon threads executing native code are still running. But they
4287 // will be stopped at native=>Java/VM barriers. Note that we can't
4288 // simply kill or suspend them, as it is inherently deadlock-prone.
4289
4290 VM_Exit::set_vm_exited();
4291
4292 // Clean up ideal graph printers after the VMThread has started
4293 // the final safepoint which will block all the Compiler threads.
4294 // Note that this Thread has already logically exited so the
4295 // clean_up() function's use of a JavaThreadIteratorWithHandle
4296 // would be a problem except set_vm_exited() has remembered the
4297 // shutdown thread which is granted a policy exception.
4298 #if defined(COMPILER2) && !defined(PRODUCT)
4299 IdealGraphPrinter::clean_up();
4300 #endif
4301
4302 notify_vm_shutdown();
4303
4304 // We are after VM_Exit::set_vm_exited() so we can't call
4305 // thread->smr_delete() or we will block on the Threads_lock.
4306 // Deleting the shutdown thread here is safe because another
4307 // JavaThread cannot have an active ThreadsListHandle for
4308 // this JavaThread.
4309 delete thread;
4310
4311 #if INCLUDE_JVMCI
4312 if (JVMCICounterSize > 0) {
4313 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4314 }
4315 #endif
4316
4317 // exit_globals() will delete tty
4318 exit_globals();
4319
4320 LogConfiguration::finalize();
4321
4322 return true;
4323 }
4324
4325
4326 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4327 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4328 return is_supported_jni_version(version);
4329 }
4330
4331
4332 jboolean Threads::is_supported_jni_version(jint version) {
4333 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4334 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4335 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4336 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4337 if (version == JNI_VERSION_9) return JNI_TRUE;
4338 if (version == JNI_VERSION_10) return JNI_TRUE;
4339 return JNI_FALSE;
4340 }
4341
4342
4343 void Threads::add(JavaThread* p, bool force_daemon) {
4344 // The threads lock must be owned at this point
4345 assert_locked_or_safepoint(Threads_lock);
4346
4347 BarrierSet::barrier_set()->on_thread_attach(p);
4348
4349 p->set_next(_thread_list);
4350 _thread_list = p;
4351
4352 // Once a JavaThread is added to the Threads list, smr_delete() has
4353 // to be used to delete it. Otherwise we can just delete it directly.
4354 p->set_on_thread_list();
4355
4356 _number_of_threads++;
4357 oop threadObj = p->threadObj();
4358 bool daemon = true;
4359 // Bootstrapping problem: threadObj can be null for initial
4360 // JavaThread (or for threads attached via JNI)
4361 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4362 _number_of_non_daemon_threads++;
4363 daemon = false;
4364 }
4365
4366 ThreadService::add_thread(p, daemon);
4367
4368 // Maintain fast thread list
4369 ThreadsSMRSupport::add_thread(p);
4370
4371 // Possible GC point.
4372 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4373 }
4374
4375 void Threads::remove(JavaThread* p) {
4376
4377 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4378 ObjectSynchronizer::omFlush(p);
4379
4380 // Extra scope needed for Thread_lock, so we can check
4381 // that we do not remove thread without safepoint code notice
4382 { MutexLocker ml(Threads_lock);
4383
4384 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4385
4386 // Maintain fast thread list
4387 ThreadsSMRSupport::remove_thread(p);
4388
4389 JavaThread* current = _thread_list;
4390 JavaThread* prev = NULL;
4391
4392 while (current != p) {
4393 prev = current;
4394 current = current->next();
4395 }
4396
4397 if (prev) {
4398 prev->set_next(current->next());
4399 } else {
4400 _thread_list = p->next();
4401 }
4402
4403 _number_of_threads--;
4404 oop threadObj = p->threadObj();
4405 bool daemon = true;
4406 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4407 _number_of_non_daemon_threads--;
4408 daemon = false;
4409
4410 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4411 // on destroy_vm will wake up.
4412 if (number_of_non_daemon_threads() == 1) {
4413 Threads_lock->notify_all();
4414 }
4415 }
4416 ThreadService::remove_thread(p, daemon);
4417
4418 // Make sure that safepoint code disregard this thread. This is needed since
4419 // the thread might mess around with locks after this point. This can cause it
4420 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4421 // of this thread since it is removed from the queue.
4422 p->set_terminated_value();
4423 } // unlock Threads_lock
4424
4425 // Since Events::log uses a lock, we grab it outside the Threads_lock
4426 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4427 }
4428
4429 // Operations on the Threads list for GC. These are not explicitly locked,
4430 // but the garbage collector must provide a safe context for them to run.
4431 // In particular, these things should never be called when the Threads_lock
4432 // is held by some other thread. (Note: the Safepoint abstraction also
4433 // uses the Threads_lock to guarantee this property. It also makes sure that
4434 // all threads gets blocked when exiting or starting).
4435
4436 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4437 ALL_JAVA_THREADS(p) {
4438 p->oops_do(f, cf);
4439 }
4440 VMThread::vm_thread()->oops_do(f, cf);
4441 }
4442
4443 void Threads::change_thread_claim_parity() {
4444 // Set the new claim parity.
4445 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4446 "Not in range.");
4447 _thread_claim_parity++;
4448 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4449 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4450 "Not in range.");
4451 }
4452
4453 #ifdef ASSERT
4454 void Threads::assert_all_threads_claimed() {
4455 ALL_JAVA_THREADS(p) {
4456 const int thread_parity = p->oops_do_parity();
4457 assert((thread_parity == _thread_claim_parity),
4458 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4459 }
4460 VMThread* vmt = VMThread::vm_thread();
4461 const int thread_parity = vmt->oops_do_parity();
4462 assert((thread_parity == _thread_claim_parity),
4463 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4464 }
4465 #endif // ASSERT
4466
4467 class ParallelOopsDoThreadClosure : public ThreadClosure {
4468 private:
4469 OopClosure* _f;
4470 CodeBlobClosure* _cf;
4471 public:
4472 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4473 void do_thread(Thread* t) {
4474 t->oops_do(_f, _cf);
4475 }
4476 };
4477
4478 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4479 ParallelOopsDoThreadClosure tc(f, cf);
4480 possibly_parallel_threads_do(is_par, &tc);
4481 }
4482
4483 void Threads::nmethods_do(CodeBlobClosure* cf) {
4484 ALL_JAVA_THREADS(p) {
4485 // This is used by the code cache sweeper to mark nmethods that are active
4486 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4487 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4488 if(!p->is_Code_cache_sweeper_thread()) {
4489 p->nmethods_do(cf);
4490 }
4491 }
4492 }
4493
4494 void Threads::metadata_do(void f(Metadata*)) {
4495 ALL_JAVA_THREADS(p) {
4496 p->metadata_do(f);
4497 }
4498 }
4499
4500 class ThreadHandlesClosure : public ThreadClosure {
4501 void (*_f)(Metadata*);
4502 public:
4503 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4504 virtual void do_thread(Thread* thread) {
4505 thread->metadata_handles_do(_f);
4506 }
4507 };
4508
4509 void Threads::metadata_handles_do(void f(Metadata*)) {
4510 // Only walk the Handles in Thread.
4511 ThreadHandlesClosure handles_closure(f);
4512 threads_do(&handles_closure);
4513 }
4514
4515 void Threads::deoptimized_wrt_marked_nmethods() {
4516 ALL_JAVA_THREADS(p) {
4517 p->deoptimized_wrt_marked_nmethods();
4518 }
4519 }
4520
4521
4522 // Get count Java threads that are waiting to enter the specified monitor.
4523 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4524 int count,
4525 address monitor) {
4526 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4527
4528 int i = 0;
4529 DO_JAVA_THREADS(t_list, p) {
4530 if (!p->can_call_java()) continue;
4531
4532 address pending = (address)p->current_pending_monitor();
4533 if (pending == monitor) { // found a match
4534 if (i < count) result->append(p); // save the first count matches
4535 i++;
4536 }
4537 }
4538
4539 return result;
4540 }
4541
4542
4543 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4544 address owner) {
4545 // NULL owner means not locked so we can skip the search
4546 if (owner == NULL) return NULL;
4547
4548 DO_JAVA_THREADS(t_list, p) {
4549 // first, see if owner is the address of a Java thread
4550 if (owner == (address)p) return p;
4551 }
4552
4553 // Cannot assert on lack of success here since this function may be
4554 // used by code that is trying to report useful problem information
4555 // like deadlock detection.
4556 if (UseHeavyMonitors) return NULL;
4557
4558 // If we didn't find a matching Java thread and we didn't force use of
4559 // heavyweight monitors, then the owner is the stack address of the
4560 // Lock Word in the owning Java thread's stack.
4561 //
4562 JavaThread* the_owner = NULL;
4563 DO_JAVA_THREADS(t_list, q) {
4564 if (q->is_lock_owned(owner)) {
4565 the_owner = q;
4566 break;
4567 }
4568 }
4569
4570 // cannot assert on lack of success here; see above comment
4571 return the_owner;
4572 }
4573
4574 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4575 void Threads::print_on(outputStream* st, bool print_stacks,
4576 bool internal_format, bool print_concurrent_locks,
4577 bool print_extended_info) {
4578 char buf[32];
4579 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4580
4581 st->print_cr("Full thread dump %s (%s %s):",
4582 Abstract_VM_Version::vm_name(),
4583 Abstract_VM_Version::vm_release(),
4584 Abstract_VM_Version::vm_info_string());
4585 st->cr();
4586
4587 #if INCLUDE_SERVICES
4588 // Dump concurrent locks
4589 ConcurrentLocksDump concurrent_locks;
4590 if (print_concurrent_locks) {
4591 concurrent_locks.dump_at_safepoint();
4592 }
4593 #endif // INCLUDE_SERVICES
4594
4595 ThreadsSMRSupport::print_info_on(st);
4596 st->cr();
4597
4598 ALL_JAVA_THREADS(p) {
4599 ResourceMark rm;
4600 p->print_on(st, print_extended_info);
4601 if (print_stacks) {
4602 if (internal_format) {
4603 p->trace_stack();
4604 } else {
4605 p->print_stack_on(st);
4606 }
4607 }
4608 st->cr();
4609 #if INCLUDE_SERVICES
4610 if (print_concurrent_locks) {
4611 concurrent_locks.print_locks_on(p, st);
4612 }
4613 #endif // INCLUDE_SERVICES
4614 }
4615
4616 VMThread::vm_thread()->print_on(st);
4617 st->cr();
4618 Universe::heap()->print_gc_threads_on(st);
4619 WatcherThread* wt = WatcherThread::watcher_thread();
4620 if (wt != NULL) {
4621 wt->print_on(st);
4622 st->cr();
4623 }
4624
4625 st->flush();
4626 }
4627
4628 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4629 int buflen, bool* found_current) {
4630 if (this_thread != NULL) {
4631 bool is_current = (current == this_thread);
4632 *found_current = *found_current || is_current;
4633 st->print("%s", is_current ? "=>" : " ");
4634
4635 st->print(PTR_FORMAT, p2i(this_thread));
4636 st->print(" ");
4637 this_thread->print_on_error(st, buf, buflen);
4638 st->cr();
4639 }
4640 }
4641
4642 class PrintOnErrorClosure : public ThreadClosure {
4643 outputStream* _st;
4644 Thread* _current;
4645 char* _buf;
4646 int _buflen;
4647 bool* _found_current;
4648 public:
4649 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4650 int buflen, bool* found_current) :
4651 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4652
4653 virtual void do_thread(Thread* thread) {
4654 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4655 }
4656 };
4657
4658 // Threads::print_on_error() is called by fatal error handler. It's possible
4659 // that VM is not at safepoint and/or current thread is inside signal handler.
4660 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4661 // memory (even in resource area), it might deadlock the error handler.
4662 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4663 int buflen) {
4664 ThreadsSMRSupport::print_info_on(st);
4665 st->cr();
4666
4667 bool found_current = false;
4668 st->print_cr("Java Threads: ( => current thread )");
4669 ALL_JAVA_THREADS(thread) {
4670 print_on_error(thread, st, current, buf, buflen, &found_current);
4671 }
4672 st->cr();
4673
4674 st->print_cr("Other Threads:");
4675 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4676 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4677
4678 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4679 Universe::heap()->gc_threads_do(&print_closure);
4680
4681 if (!found_current) {
4682 st->cr();
4683 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4684 current->print_on_error(st, buf, buflen);
4685 st->cr();
4686 }
4687 st->cr();
4688
4689 st->print_cr("Threads with active compile tasks:");
4690 print_threads_compiling(st, buf, buflen);
4691 }
4692
4693 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4694 ALL_JAVA_THREADS(thread) {
4695 if (thread->is_Compiler_thread()) {
4696 CompilerThread* ct = (CompilerThread*) thread;
4697
4698 // Keep task in local variable for NULL check.
4699 // ct->_task might be set to NULL by concurring compiler thread
4700 // because it completed the compilation. The task is never freed,
4701 // though, just returned to a free list.
4702 CompileTask* task = ct->task();
4703 if (task != NULL) {
4704 thread->print_name_on_error(st, buf, buflen);
4705 task->print(st, NULL, true, true);
4706 }
4707 }
4708 }
4709 }
4710
4711
4712 // Internal SpinLock and Mutex
4713 // Based on ParkEvent
4714
4715 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4716 //
4717 // We employ SpinLocks _only for low-contention, fixed-length
4718 // short-duration critical sections where we're concerned
4719 // about native mutex_t or HotSpot Mutex:: latency.
4720 // The mux construct provides a spin-then-block mutual exclusion
4721 // mechanism.
4722 //
4723 // Testing has shown that contention on the ListLock guarding gFreeList
4724 // is common. If we implement ListLock as a simple SpinLock it's common
4725 // for the JVM to devolve to yielding with little progress. This is true
4726 // despite the fact that the critical sections protected by ListLock are
4727 // extremely short.
4728 //
4729 // TODO-FIXME: ListLock should be of type SpinLock.
4730 // We should make this a 1st-class type, integrated into the lock
4731 // hierarchy as leaf-locks. Critically, the SpinLock structure
4732 // should have sufficient padding to avoid false-sharing and excessive
4733 // cache-coherency traffic.
4734
4735
4736 typedef volatile int SpinLockT;
4737
4738 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4739 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4740 return; // normal fast-path return
4741 }
4742
4743 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4744 TEVENT(SpinAcquire - ctx);
4745 int ctr = 0;
4746 int Yields = 0;
4747 for (;;) {
4748 while (*adr != 0) {
4749 ++ctr;
4750 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4751 if (Yields > 5) {
4752 os::naked_short_sleep(1);
4753 } else {
4754 os::naked_yield();
4755 ++Yields;
4756 }
4757 } else {
4758 SpinPause();
4759 }
4760 }
4761 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4762 }
4763 }
4764
4765 void Thread::SpinRelease(volatile int * adr) {
4766 assert(*adr != 0, "invariant");
4767 OrderAccess::fence(); // guarantee at least release consistency.
4768 // Roach-motel semantics.
4769 // It's safe if subsequent LDs and STs float "up" into the critical section,
4770 // but prior LDs and STs within the critical section can't be allowed
4771 // to reorder or float past the ST that releases the lock.
4772 // Loads and stores in the critical section - which appear in program
4773 // order before the store that releases the lock - must also appear
4774 // before the store that releases the lock in memory visibility order.
4775 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4776 // the ST of 0 into the lock-word which releases the lock, so fence
4777 // more than covers this on all platforms.
4778 *adr = 0;
4779 }
4780
4781 // muxAcquire and muxRelease:
4782 //
4783 // * muxAcquire and muxRelease support a single-word lock-word construct.
4784 // The LSB of the word is set IFF the lock is held.
4785 // The remainder of the word points to the head of a singly-linked list
4786 // of threads blocked on the lock.
4787 //
4788 // * The current implementation of muxAcquire-muxRelease uses its own
4789 // dedicated Thread._MuxEvent instance. If we're interested in
4790 // minimizing the peak number of extant ParkEvent instances then
4791 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4792 // as certain invariants were satisfied. Specifically, care would need
4793 // to be taken with regards to consuming unpark() "permits".
4794 // A safe rule of thumb is that a thread would never call muxAcquire()
4795 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4796 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4797 // consume an unpark() permit intended for monitorenter, for instance.
4798 // One way around this would be to widen the restricted-range semaphore
4799 // implemented in park(). Another alternative would be to provide
4800 // multiple instances of the PlatformEvent() for each thread. One
4801 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4802 //
4803 // * Usage:
4804 // -- Only as leaf locks
4805 // -- for short-term locking only as muxAcquire does not perform
4806 // thread state transitions.
4807 //
4808 // Alternatives:
4809 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4810 // but with parking or spin-then-park instead of pure spinning.
4811 // * Use Taura-Oyama-Yonenzawa locks.
4812 // * It's possible to construct a 1-0 lock if we encode the lockword as
4813 // (List,LockByte). Acquire will CAS the full lockword while Release
4814 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4815 // acquiring threads use timers (ParkTimed) to detect and recover from
4816 // the stranding window. Thread/Node structures must be aligned on 256-byte
4817 // boundaries by using placement-new.
4818 // * Augment MCS with advisory back-link fields maintained with CAS().
4819 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4820 // The validity of the backlinks must be ratified before we trust the value.
4821 // If the backlinks are invalid the exiting thread must back-track through the
4822 // the forward links, which are always trustworthy.
4823 // * Add a successor indication. The LockWord is currently encoded as
4824 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4825 // to provide the usual futile-wakeup optimization.
4826 // See RTStt for details.
4827 //
4828
4829
4830 const intptr_t LOCKBIT = 1;
4831
4832 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4833 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4834 if (w == 0) return;
4835 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4836 return;
4837 }
4838
4839 TEVENT(muxAcquire - Contention);
4840 ParkEvent * const Self = Thread::current()->_MuxEvent;
4841 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4842 for (;;) {
4843 int its = (os::is_MP() ? 100 : 0) + 1;
4844
4845 // Optional spin phase: spin-then-park strategy
4846 while (--its >= 0) {
4847 w = *Lock;
4848 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4849 return;
4850 }
4851 }
4852
4853 Self->reset();
4854 Self->OnList = intptr_t(Lock);
4855 // The following fence() isn't _strictly necessary as the subsequent
4856 // CAS() both serializes execution and ratifies the fetched *Lock value.
4857 OrderAccess::fence();
4858 for (;;) {
4859 w = *Lock;
4860 if ((w & LOCKBIT) == 0) {
4861 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4862 Self->OnList = 0; // hygiene - allows stronger asserts
4863 return;
4864 }
4865 continue; // Interference -- *Lock changed -- Just retry
4866 }
4867 assert(w & LOCKBIT, "invariant");
4868 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4869 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4870 }
4871
4872 while (Self->OnList != 0) {
4873 Self->park();
4874 }
4875 }
4876 }
4877
4878 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4879 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4880 if (w == 0) return;
4881 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4882 return;
4883 }
4884
4885 TEVENT(muxAcquire - Contention);
4886 ParkEvent * ReleaseAfter = NULL;
4887 if (ev == NULL) {
4888 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4889 }
4890 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4891 for (;;) {
4892 guarantee(ev->OnList == 0, "invariant");
4893 int its = (os::is_MP() ? 100 : 0) + 1;
4894
4895 // Optional spin phase: spin-then-park strategy
4896 while (--its >= 0) {
4897 w = *Lock;
4898 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4899 if (ReleaseAfter != NULL) {
4900 ParkEvent::Release(ReleaseAfter);
4901 }
4902 return;
4903 }
4904 }
4905
4906 ev->reset();
4907 ev->OnList = intptr_t(Lock);
4908 // The following fence() isn't _strictly necessary as the subsequent
4909 // CAS() both serializes execution and ratifies the fetched *Lock value.
4910 OrderAccess::fence();
4911 for (;;) {
4912 w = *Lock;
4913 if ((w & LOCKBIT) == 0) {
4914 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4915 ev->OnList = 0;
4916 // We call ::Release while holding the outer lock, thus
4917 // artificially lengthening the critical section.
4918 // Consider deferring the ::Release() until the subsequent unlock(),
4919 // after we've dropped the outer lock.
4920 if (ReleaseAfter != NULL) {
4921 ParkEvent::Release(ReleaseAfter);
4922 }
4923 return;
4924 }
4925 continue; // Interference -- *Lock changed -- Just retry
4926 }
4927 assert(w & LOCKBIT, "invariant");
4928 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4929 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4930 }
4931
4932 while (ev->OnList != 0) {
4933 ev->park();
4934 }
4935 }
4936 }
4937
4938 // Release() must extract a successor from the list and then wake that thread.
4939 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4940 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4941 // Release() would :
4942 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4943 // (B) Extract a successor from the private list "in-hand"
4944 // (C) attempt to CAS() the residual back into *Lock over null.
4945 // If there were any newly arrived threads and the CAS() would fail.
4946 // In that case Release() would detach the RATs, re-merge the list in-hand
4947 // with the RATs and repeat as needed. Alternately, Release() might
4948 // detach and extract a successor, but then pass the residual list to the wakee.
4949 // The wakee would be responsible for reattaching and remerging before it
4950 // competed for the lock.
4951 //
4952 // Both "pop" and DMR are immune from ABA corruption -- there can be
4953 // multiple concurrent pushers, but only one popper or detacher.
4954 // This implementation pops from the head of the list. This is unfair,
4955 // but tends to provide excellent throughput as hot threads remain hot.
4956 // (We wake recently run threads first).
4957 //
4958 // All paths through muxRelease() will execute a CAS.
4959 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4960 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4961 // executed within the critical section are complete and globally visible before the
4962 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4963 void Thread::muxRelease(volatile intptr_t * Lock) {
4964 for (;;) {
4965 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4966 assert(w & LOCKBIT, "invariant");
4967 if (w == LOCKBIT) return;
4968 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4969 assert(List != NULL, "invariant");
4970 assert(List->OnList == intptr_t(Lock), "invariant");
4971 ParkEvent * const nxt = List->ListNext;
4972 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4973
4974 // The following CAS() releases the lock and pops the head element.
4975 // The CAS() also ratifies the previously fetched lock-word value.
4976 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4977 continue;
4978 }
4979 List->OnList = 0;
4980 OrderAccess::fence();
4981 List->unpark();
4982 return;
4983 }
4984 }
4985
4986
4987 void Threads::verify() {
4988 ALL_JAVA_THREADS(p) {
4989 p->verify();
4990 }
4991 VMThread* thread = VMThread::vm_thread();
4992 if (thread != NULL) thread->verify();
4993 }