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