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 "runtime/arguments.hpp"
65 #include "runtime/atomic.hpp"
66 #include "runtime/biasedLocking.hpp"
67 #include "runtime/fieldDescriptor.inline.hpp"
68 #include "runtime/flags/jvmFlagConstraintList.hpp"
69 #include "runtime/flags/jvmFlagRangeList.hpp"
70 #include "runtime/flags/jvmFlagWriteableList.hpp"
71 #include "runtime/deoptimization.hpp"
72 #include "runtime/frame.inline.hpp"
73 #include "runtime/handshake.hpp"
74 #include "runtime/init.hpp"
75 #include "runtime/interfaceSupport.inline.hpp"
76 #include "runtime/java.hpp"
77 #include "runtime/javaCalls.hpp"
78 #include "runtime/jniHandles.inline.hpp"
79 #include "runtime/jniPeriodicChecker.hpp"
80 #include "runtime/memprofiler.hpp"
81 #include "runtime/mutexLocker.hpp"
82 #include "runtime/objectMonitor.hpp"
83 #include "runtime/orderAccess.hpp"
84 #include "runtime/osThread.hpp"
85 #include "runtime/prefetch.inline.hpp"
86 #include "runtime/safepoint.hpp"
87 #include "runtime/safepointMechanism.inline.hpp"
88 #include "runtime/safepointVerifiers.hpp"
89 #include "runtime/sharedRuntime.hpp"
90 #include "runtime/statSampler.hpp"
91 #include "runtime/stubRoutines.hpp"
92 #include "runtime/sweeper.hpp"
93 #include "runtime/task.hpp"
94 #include "runtime/thread.inline.hpp"
95 #include "runtime/threadCritical.hpp"
96 #include "runtime/threadSMR.inline.hpp"
97 #include "runtime/threadStatisticalInfo.hpp"
98 #include "runtime/timer.hpp"
99 #include "runtime/timerTrace.hpp"
100 #include "runtime/vframe.inline.hpp"
101 #include "runtime/vframeArray.hpp"
102 #include "runtime/vframe_hp.hpp"
103 #include "runtime/vmThread.hpp"
104 #include "runtime/vm_operations.hpp"
105 #include "runtime/vm_version.hpp"
106 #include "services/attachListener.hpp"
107 #include "services/management.hpp"
108 #include "services/memTracker.hpp"
109 #include "services/threadService.hpp"
110 #include "utilities/align.hpp"
111 #include "utilities/copy.hpp"
112 #include "utilities/defaultStream.hpp"
113 #include "utilities/dtrace.hpp"
114 #include "utilities/events.hpp"
115 #include "utilities/macros.hpp"
116 #include "utilities/preserveException.hpp"
117 #include "utilities/singleWriterSynchronizer.hpp"
118 #include "utilities/vmError.hpp"
119 #if INCLUDE_JVMCI
120 #include "jvmci/jvmciCompiler.hpp"
121 #include "jvmci/jvmciRuntime.hpp"
122 #include "logging/logHandle.hpp"
123 #endif
124 #ifdef COMPILER1
125 #include "c1/c1_Compiler.hpp"
126 #endif
127 #ifdef COMPILER2
128 #include "opto/c2compiler.hpp"
129 #include "opto/idealGraphPrinter.hpp"
130 #endif
131 #if INCLUDE_RTM_OPT
132 #include "runtime/rtmLocking.hpp"
133 #endif
134 #if INCLUDE_JFR
135 #include "jfr/jfr.hpp"
136 #endif
137
138 // Initialization after module runtime initialization
139 void universe_post_module_init(); // must happen after call_initPhase2
140
141 #ifdef DTRACE_ENABLED
142
143 // Only bother with this argument setup if dtrace is available
144
145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
147
148 #define DTRACE_THREAD_PROBE(probe, javathread) \
149 { \
150 ResourceMark rm(this); \
151 int len = 0; \
152 const char* name = (javathread)->get_thread_name(); \
153 len = strlen(name); \
154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
155 (char *) name, len, \
156 java_lang_Thread::thread_id((javathread)->threadObj()), \
157 (uintptr_t) (javathread)->osthread()->thread_id(), \
158 java_lang_Thread::is_daemon((javathread)->threadObj())); \
159 }
160
161 #else // ndef DTRACE_ENABLED
162
163 #define DTRACE_THREAD_PROBE(probe, javathread)
164
165 #endif // ndef DTRACE_ENABLED
166
167 #ifndef USE_LIBRARY_BASED_TLS_ONLY
168 // Current thread is maintained as a thread-local variable
169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
170 #endif
171
172 // ======= Thread ========
173 // Support for forcing alignment of thread objects for biased locking
174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
175 if (UseBiasedLocking) {
176 const int alignment = markOopDesc::biased_lock_alignment;
177 size_t aligned_size = size + (alignment - sizeof(intptr_t));
178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
179 : AllocateHeap(aligned_size, flags, CURRENT_PC,
180 AllocFailStrategy::RETURN_NULL);
181 void* aligned_addr = align_up(real_malloc_addr, alignment);
182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
184 "JavaThread alignment code overflowed allocated storage");
185 if (aligned_addr != real_malloc_addr) {
186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
187 p2i(real_malloc_addr),
188 p2i(aligned_addr));
189 }
190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
191 return aligned_addr;
192 } else {
193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
195 }
196 }
197
198 void Thread::operator delete(void* p) {
199 if (UseBiasedLocking) {
200 FreeHeap(((Thread*) p)->_real_malloc_address);
201 } else {
202 FreeHeap(p);
203 }
204 }
205
206 void JavaThread::smr_delete() {
207 if (_on_thread_list) {
208 ThreadsSMRSupport::smr_delete(this);
209 } else {
210 delete this;
211 }
212 }
213
214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
215 // JavaThread
216
217
218 Thread::Thread() {
219 // stack and get_thread
220 set_stack_base(NULL);
221 set_stack_size(0);
222 set_self_raw_id(0);
223 set_lgrp_id(-1);
224 DEBUG_ONLY(clear_suspendible_thread();)
225
226 // allocated data structures
227 set_osthread(NULL);
228 set_resource_area(new (mtThread)ResourceArea());
229 DEBUG_ONLY(_current_resource_mark = NULL;)
230 set_handle_area(new (mtThread) HandleArea(NULL));
231 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
232 set_active_handles(NULL);
233 set_free_handle_block(NULL);
234 set_last_handle_mark(NULL);
235
236 // This initial value ==> never claimed.
237 _oops_do_parity = 0;
238 _threads_hazard_ptr = NULL;
239 _threads_list_ptr = NULL;
240 _nested_threads_hazard_ptr_cnt = 0;
241 _rcu_counter = 0;
242
243 // the handle mark links itself to last_handle_mark
244 new HandleMark(this);
245
246 // plain initialization
247 debug_only(_owned_locks = NULL;)
248 debug_only(_allow_allocation_count = 0;)
249 NOT_PRODUCT(_allow_safepoint_count = 0;)
250 NOT_PRODUCT(_skip_gcalot = false;)
251 _jvmti_env_iteration_count = 0;
252 set_allocated_bytes(0);
253 _vm_operation_started_count = 0;
254 _vm_operation_completed_count = 0;
255 _current_pending_monitor = NULL;
256 _current_pending_monitor_is_from_java = true;
257 _current_waiting_monitor = NULL;
258 _num_nested_signal = 0;
259 omFreeList = NULL;
260 omFreeCount = 0;
261 omFreeProvision = 32;
262 omInUseList = NULL;
263 omInUseCount = 0;
264
265 #ifdef ASSERT
266 _visited_for_critical_count = false;
267 #endif
268
269 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
270 Monitor::_safepoint_check_sometimes);
271 _suspend_flags = 0;
272
273 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
274 _hashStateX = os::random();
275 _hashStateY = 842502087;
276 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
277 _hashStateW = 273326509;
278
279 _OnTrap = 0;
280 _Stalled = 0;
281 _TypeTag = 0x2BAD;
282
283 // Many of the following fields are effectively final - immutable
284 // Note that nascent threads can't use the Native Monitor-Mutex
285 // construct until the _MutexEvent is initialized ...
286 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
287 // we might instead use a stack of ParkEvents that we could provision on-demand.
288 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
289 // and ::Release()
290 _ParkEvent = ParkEvent::Allocate(this);
291 _SleepEvent = ParkEvent::Allocate(this);
292 _MutexEvent = ParkEvent::Allocate(this);
293 _MuxEvent = ParkEvent::Allocate(this);
294
295 #ifdef CHECK_UNHANDLED_OOPS
296 if (CheckUnhandledOops) {
297 _unhandled_oops = new UnhandledOops(this);
298 }
299 #endif // CHECK_UNHANDLED_OOPS
300 #ifdef ASSERT
301 if (UseBiasedLocking) {
302 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
303 assert(this == _real_malloc_address ||
304 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
305 "bug in forced alignment of thread objects");
306 }
307 #endif // ASSERT
308
309 // Notify the barrier set that a thread is being created. Note that some
310 // threads are created before a barrier set is available. The call to
311 // BarrierSet::on_thread_create() for these threads is therefore deferred
312 // to BarrierSet::set_barrier_set().
313 BarrierSet* const barrier_set = BarrierSet::barrier_set();
314 if (barrier_set != NULL) {
315 barrier_set->on_thread_create(this);
316 } else {
317 DEBUG_ONLY(Threads::inc_threads_before_barrier_set();)
318 }
319 }
320
321 void Thread::initialize_thread_current() {
322 #ifndef USE_LIBRARY_BASED_TLS_ONLY
323 assert(_thr_current == NULL, "Thread::current already initialized");
324 _thr_current = this;
325 #endif
326 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
327 ThreadLocalStorage::set_thread(this);
328 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
329 }
330
331 void Thread::clear_thread_current() {
332 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
333 #ifndef USE_LIBRARY_BASED_TLS_ONLY
334 _thr_current = NULL;
335 #endif
336 ThreadLocalStorage::set_thread(NULL);
337 }
338
339 void Thread::record_stack_base_and_size() {
340 // Note: at this point, Thread object is not yet initialized. Do not rely on
341 // any members being initialized. Do not rely on Thread::current() being set.
342 // If possible, refrain from doing anything which may crash or assert since
343 // quite probably those crash dumps will be useless.
344 set_stack_base(os::current_stack_base());
345 set_stack_size(os::current_stack_size());
346
347 #ifdef SOLARIS
348 if (os::is_primordial_thread()) {
349 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
350 }
351 #endif
352
353 // Set stack limits after thread is initialized.
354 if (is_Java_thread()) {
355 ((JavaThread*) this)->set_stack_overflow_limit();
356 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
357 }
358 }
359
360 #if INCLUDE_NMT
361 void Thread::register_thread_stack_with_NMT() {
362 MemTracker::record_thread_stack(stack_end(), stack_size());
363 }
364 #endif // INCLUDE_NMT
365
366 void Thread::call_run() {
367 // At this point, Thread object should be fully initialized and
368 // Thread::current() should be set.
369
370 register_thread_stack_with_NMT();
371
372 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
373 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
374 os::current_thread_id(), p2i(stack_base() - stack_size()),
375 p2i(stack_base()), stack_size()/1024);
376
377 // Invoke <ChildClass>::run()
378 this->run();
379 // Returned from <ChildClass>::run(). Thread finished.
380
381 // Note: at this point the thread object may already have deleted itself.
382 // So from here on do not dereference *this*.
383
384 // If a thread has not deleted itself ("delete this") as part of its
385 // termination sequence, we have to ensure thread-local-storage is
386 // cleared before we actually terminate. No threads should ever be
387 // deleted asynchronously with respect to their termination.
388 if (Thread::current_or_null_safe() != NULL) {
389 assert(Thread::current_or_null_safe() == this, "current thread is wrong");
390 Thread::clear_thread_current();
391 }
392
393 }
394
395 Thread::~Thread() {
396 JFR_ONLY(Jfr::on_thread_destruct(this);)
397
398 // Notify the barrier set that a thread is being destroyed. Note that a barrier
399 // set might not be available if we encountered errors during bootstrapping.
400 BarrierSet* const barrier_set = BarrierSet::barrier_set();
401 if (barrier_set != NULL) {
402 barrier_set->on_thread_destroy(this);
403 }
404
405
406 // stack_base can be NULL if the thread is never started or exited before
407 // record_stack_base_and_size called. Although, we would like to ensure
408 // that all started threads do call record_stack_base_and_size(), there is
409 // not proper way to enforce that.
410 #if INCLUDE_NMT
411 if (_stack_base != NULL) {
412 MemTracker::release_thread_stack(stack_end(), stack_size());
413 #ifdef ASSERT
414 set_stack_base(NULL);
415 #endif
416 }
417 #endif // INCLUDE_NMT
418
419 // deallocate data structures
420 delete resource_area();
421 // since the handle marks are using the handle area, we have to deallocated the root
422 // handle mark before deallocating the thread's handle area,
423 assert(last_handle_mark() != NULL, "check we have an element");
424 delete last_handle_mark();
425 assert(last_handle_mark() == NULL, "check we have reached the end");
426
427 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
428 // We NULL out the fields for good hygiene.
429 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
430 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
431 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
432 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
433
434 delete handle_area();
435 delete metadata_handles();
436
437 // SR_handler uses this as a termination indicator -
438 // needs to happen before os::free_thread()
439 delete _SR_lock;
440 _SR_lock = NULL;
441
442 // osthread() can be NULL, if creation of thread failed.
443 if (osthread() != NULL) os::free_thread(osthread());
444
445 // clear Thread::current if thread is deleting itself.
446 // Needed to ensure JNI correctly detects non-attached threads.
447 if (this == Thread::current()) {
448 Thread::clear_thread_current();
449 }
450
451 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
452 }
453
454 #ifdef ASSERT
455 // A JavaThread is considered "dangling" if it is not the current
456 // thread, has been added the Threads list, the system is not at a
457 // safepoint and the Thread is not "protected".
458 //
459 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
460 assert(!thread->is_Java_thread() || Thread::current() == thread ||
461 !((JavaThread *) thread)->on_thread_list() ||
462 SafepointSynchronize::is_at_safepoint() ||
463 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
464 "possibility of dangling Thread pointer");
465 }
466 #endif
467
468 ThreadPriority Thread::get_priority(const Thread* const thread) {
469 ThreadPriority priority;
470 // Can return an error!
471 (void)os::get_priority(thread, priority);
472 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
473 return priority;
474 }
475
476 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
477 debug_only(check_for_dangling_thread_pointer(thread);)
478 // Can return an error!
479 (void)os::set_priority(thread, priority);
480 }
481
482
483 void Thread::start(Thread* thread) {
484 // Start is different from resume in that its safety is guaranteed by context or
485 // being called from a Java method synchronized on the Thread object.
486 if (!DisableStartThread) {
487 if (thread->is_Java_thread()) {
488 // Initialize the thread state to RUNNABLE before starting this thread.
489 // Can not set it after the thread started because we do not know the
490 // exact thread state at that time. It could be in MONITOR_WAIT or
491 // in SLEEPING or some other state.
492 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
493 java_lang_Thread::RUNNABLE);
494 }
495 os::start_thread(thread);
496 }
497 }
498
499 // Enqueue a VM_Operation to do the job for us - sometime later
500 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
501 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
502 VMThread::execute(vm_stop);
503 }
504
505
506 // Check if an external suspend request has completed (or has been
507 // cancelled). Returns true if the thread is externally suspended and
508 // false otherwise.
509 //
510 // The bits parameter returns information about the code path through
511 // the routine. Useful for debugging:
512 //
513 // set in is_ext_suspend_completed():
514 // 0x00000001 - routine was entered
515 // 0x00000010 - routine return false at end
516 // 0x00000100 - thread exited (return false)
517 // 0x00000200 - suspend request cancelled (return false)
518 // 0x00000400 - thread suspended (return true)
519 // 0x00001000 - thread is in a suspend equivalent state (return true)
520 // 0x00002000 - thread is native and walkable (return true)
521 // 0x00004000 - thread is native_trans and walkable (needed retry)
522 //
523 // set in wait_for_ext_suspend_completion():
524 // 0x00010000 - routine was entered
525 // 0x00020000 - suspend request cancelled before loop (return false)
526 // 0x00040000 - thread suspended before loop (return true)
527 // 0x00080000 - suspend request cancelled in loop (return false)
528 // 0x00100000 - thread suspended in loop (return true)
529 // 0x00200000 - suspend not completed during retry loop (return false)
530
531 // Helper class for tracing suspend wait debug bits.
532 //
533 // 0x00000100 indicates that the target thread exited before it could
534 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
535 // 0x00080000 each indicate a cancelled suspend request so they don't
536 // count as wait failures either.
537 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
538
539 class TraceSuspendDebugBits : public StackObj {
540 private:
541 JavaThread * jt;
542 bool is_wait;
543 bool called_by_wait; // meaningful when !is_wait
544 uint32_t * bits;
545
546 public:
547 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
548 uint32_t *_bits) {
549 jt = _jt;
550 is_wait = _is_wait;
551 called_by_wait = _called_by_wait;
552 bits = _bits;
553 }
554
555 ~TraceSuspendDebugBits() {
556 if (!is_wait) {
557 #if 1
558 // By default, don't trace bits for is_ext_suspend_completed() calls.
559 // That trace is very chatty.
560 return;
561 #else
562 if (!called_by_wait) {
563 // If tracing for is_ext_suspend_completed() is enabled, then only
564 // trace calls to it from wait_for_ext_suspend_completion()
565 return;
566 }
567 #endif
568 }
569
570 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
571 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
572 MutexLocker ml(Threads_lock); // needed for get_thread_name()
573 ResourceMark rm;
574
575 tty->print_cr(
576 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
577 jt->get_thread_name(), *bits);
578
579 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
580 }
581 }
582 }
583 };
584 #undef DEBUG_FALSE_BITS
585
586
587 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
588 uint32_t *bits) {
589 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
590
591 bool did_trans_retry = false; // only do thread_in_native_trans retry once
592 bool do_trans_retry; // flag to force the retry
593
594 *bits |= 0x00000001;
595
596 do {
597 do_trans_retry = false;
598
599 if (is_exiting()) {
600 // Thread is in the process of exiting. This is always checked
601 // first to reduce the risk of dereferencing a freed JavaThread.
602 *bits |= 0x00000100;
603 return false;
604 }
605
606 if (!is_external_suspend()) {
607 // Suspend request is cancelled. This is always checked before
608 // is_ext_suspended() to reduce the risk of a rogue resume
609 // confusing the thread that made the suspend request.
610 *bits |= 0x00000200;
611 return false;
612 }
613
614 if (is_ext_suspended()) {
615 // thread is suspended
616 *bits |= 0x00000400;
617 return true;
618 }
619
620 // Now that we no longer do hard suspends of threads running
621 // native code, the target thread can be changing thread state
622 // while we are in this routine:
623 //
624 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
625 //
626 // We save a copy of the thread state as observed at this moment
627 // and make our decision about suspend completeness based on the
628 // copy. This closes the race where the thread state is seen as
629 // _thread_in_native_trans in the if-thread_blocked check, but is
630 // seen as _thread_blocked in if-thread_in_native_trans check.
631 JavaThreadState save_state = thread_state();
632
633 if (save_state == _thread_blocked && is_suspend_equivalent()) {
634 // If the thread's state is _thread_blocked and this blocking
635 // condition is known to be equivalent to a suspend, then we can
636 // consider the thread to be externally suspended. This means that
637 // the code that sets _thread_blocked has been modified to do
638 // self-suspension if the blocking condition releases. We also
639 // used to check for CONDVAR_WAIT here, but that is now covered by
640 // the _thread_blocked with self-suspension check.
641 //
642 // Return true since we wouldn't be here unless there was still an
643 // external suspend request.
644 *bits |= 0x00001000;
645 return true;
646 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
647 // Threads running native code will self-suspend on native==>VM/Java
648 // transitions. If its stack is walkable (should always be the case
649 // unless this function is called before the actual java_suspend()
650 // call), then the wait is done.
651 *bits |= 0x00002000;
652 return true;
653 } else if (!called_by_wait && !did_trans_retry &&
654 save_state == _thread_in_native_trans &&
655 frame_anchor()->walkable()) {
656 // The thread is transitioning from thread_in_native to another
657 // thread state. check_safepoint_and_suspend_for_native_trans()
658 // will force the thread to self-suspend. If it hasn't gotten
659 // there yet we may have caught the thread in-between the native
660 // code check above and the self-suspend. Lucky us. If we were
661 // called by wait_for_ext_suspend_completion(), then it
662 // will be doing the retries so we don't have to.
663 //
664 // Since we use the saved thread state in the if-statement above,
665 // there is a chance that the thread has already transitioned to
666 // _thread_blocked by the time we get here. In that case, we will
667 // make a single unnecessary pass through the logic below. This
668 // doesn't hurt anything since we still do the trans retry.
669
670 *bits |= 0x00004000;
671
672 // Once the thread leaves thread_in_native_trans for another
673 // thread state, we break out of this retry loop. We shouldn't
674 // need this flag to prevent us from getting back here, but
675 // sometimes paranoia is good.
676 did_trans_retry = true;
677
678 // We wait for the thread to transition to a more usable state.
679 for (int i = 1; i <= SuspendRetryCount; i++) {
680 // We used to do an "os::yield_all(i)" call here with the intention
681 // that yielding would increase on each retry. However, the parameter
682 // is ignored on Linux which means the yield didn't scale up. Waiting
683 // on the SR_lock below provides a much more predictable scale up for
684 // the delay. It also provides a simple/direct point to check for any
685 // safepoint requests from the VMThread
686
687 // temporarily drops SR_lock while doing wait with safepoint check
688 // (if we're a JavaThread - the WatcherThread can also call this)
689 // and increase delay with each retry
690 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
691
692 // check the actual thread state instead of what we saved above
693 if (thread_state() != _thread_in_native_trans) {
694 // the thread has transitioned to another thread state so
695 // try all the checks (except this one) one more time.
696 do_trans_retry = true;
697 break;
698 }
699 } // end retry loop
700
701
702 }
703 } while (do_trans_retry);
704
705 *bits |= 0x00000010;
706 return false;
707 }
708
709 // Wait for an external suspend request to complete (or be cancelled).
710 // Returns true if the thread is externally suspended and false otherwise.
711 //
712 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
713 uint32_t *bits) {
714 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
715 false /* !called_by_wait */, bits);
716
717 // local flag copies to minimize SR_lock hold time
718 bool is_suspended;
719 bool pending;
720 uint32_t reset_bits;
721
722 // set a marker so is_ext_suspend_completed() knows we are the caller
723 *bits |= 0x00010000;
724
725 // We use reset_bits to reinitialize the bits value at the top of
726 // each retry loop. This allows the caller to make use of any
727 // unused bits for their own marking purposes.
728 reset_bits = *bits;
729
730 {
731 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
732 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
733 delay, bits);
734 pending = is_external_suspend();
735 }
736 // must release SR_lock to allow suspension to complete
737
738 if (!pending) {
739 // A cancelled suspend request is the only false return from
740 // is_ext_suspend_completed() that keeps us from entering the
741 // retry loop.
742 *bits |= 0x00020000;
743 return false;
744 }
745
746 if (is_suspended) {
747 *bits |= 0x00040000;
748 return true;
749 }
750
751 for (int i = 1; i <= retries; i++) {
752 *bits = reset_bits; // reinit to only track last retry
753
754 // We used to do an "os::yield_all(i)" call here with the intention
755 // that yielding would increase on each retry. However, the parameter
756 // is ignored on Linux which means the yield didn't scale up. Waiting
757 // on the SR_lock below provides a much more predictable scale up for
758 // the delay. It also provides a simple/direct point to check for any
759 // safepoint requests from the VMThread
760
761 {
762 MutexLocker ml(SR_lock());
763 // wait with safepoint check (if we're a JavaThread - the WatcherThread
764 // can also call this) and increase delay with each retry
765 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
766
767 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
768 delay, bits);
769
770 // It is possible for the external suspend request to be cancelled
771 // (by a resume) before the actual suspend operation is completed.
772 // Refresh our local copy to see if we still need to wait.
773 pending = is_external_suspend();
774 }
775
776 if (!pending) {
777 // A cancelled suspend request is the only false return from
778 // is_ext_suspend_completed() that keeps us from staying in the
779 // retry loop.
780 *bits |= 0x00080000;
781 return false;
782 }
783
784 if (is_suspended) {
785 *bits |= 0x00100000;
786 return true;
787 }
788 } // end retry loop
789
790 // thread did not suspend after all our retries
791 *bits |= 0x00200000;
792 return false;
793 }
794
795 // Called from API entry points which perform stack walking. If the
796 // associated JavaThread is the current thread, then wait_for_suspend
797 // is not used. Otherwise, it determines if we should wait for the
798 // "other" thread to complete external suspension. (NOTE: in future
799 // releases the suspension mechanism should be reimplemented so this
800 // is not necessary.)
801 //
802 bool
803 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
804 if (this != JavaThread::current()) {
805 // "other" threads require special handling.
806 if (wait_for_suspend) {
807 // We are allowed to wait for the external suspend to complete
808 // so give the other thread a chance to get suspended.
809 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
810 SuspendRetryDelay, bits)) {
811 // Didn't make it so let the caller know.
812 return false;
813 }
814 }
815 // We aren't allowed to wait for the external suspend to complete
816 // so if the other thread isn't externally suspended we need to
817 // let the caller know.
818 else if (!is_ext_suspend_completed_with_lock(bits)) {
819 return false;
820 }
821 }
822
823 return true;
824 }
825
826 #ifndef PRODUCT
827 void JavaThread::record_jump(address target, address instr, const char* file,
828 int line) {
829
830 // This should not need to be atomic as the only way for simultaneous
831 // updates is via interrupts. Even then this should be rare or non-existent
832 // and we don't care that much anyway.
833
834 int index = _jmp_ring_index;
835 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
836 _jmp_ring[index]._target = (intptr_t) target;
837 _jmp_ring[index]._instruction = (intptr_t) instr;
838 _jmp_ring[index]._file = file;
839 _jmp_ring[index]._line = line;
840 }
841 #endif // PRODUCT
842
843 void Thread::interrupt(Thread* thread) {
844 debug_only(check_for_dangling_thread_pointer(thread);)
845 os::interrupt(thread);
846 }
847
848 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
849 debug_only(check_for_dangling_thread_pointer(thread);)
850 // Note: If clear_interrupted==false, this simply fetches and
851 // returns the value of the field osthread()->interrupted().
852 return os::is_interrupted(thread, clear_interrupted);
853 }
854
855
856 // GC Support
857 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
858 int thread_parity = _oops_do_parity;
859 if (thread_parity != strong_roots_parity) {
860 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
861 if (res == thread_parity) {
862 return true;
863 } else {
864 guarantee(res == strong_roots_parity, "Or else what?");
865 return false;
866 }
867 }
868 return false;
869 }
870
871 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
872 active_handles()->oops_do(f);
873 // Do oop for ThreadShadow
874 f->do_oop((oop*)&_pending_exception);
875 handle_area()->oops_do(f);
876
877 // We scan thread local monitor lists here, and the remaining global
878 // monitors in ObjectSynchronizer::oops_do().
879 ObjectSynchronizer::thread_local_used_oops_do(this, f);
880 }
881
882 void Thread::metadata_handles_do(void f(Metadata*)) {
883 // Only walk the Handles in Thread.
884 if (metadata_handles() != NULL) {
885 for (int i = 0; i< metadata_handles()->length(); i++) {
886 f(metadata_handles()->at(i));
887 }
888 }
889 }
890
891 void Thread::print_on(outputStream* st, bool print_extended_info) const {
892 // get_priority assumes osthread initialized
893 if (osthread() != NULL) {
894 int os_prio;
895 if (os::get_native_priority(this, &os_prio) == OS_OK) {
896 st->print("os_prio=%d ", os_prio);
897 }
898
899 st->print("cpu=%.2fms ",
900 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
901 );
902 st->print("elapsed=%.2fs ",
903 _statistical_info.getElapsedTime() / 1000.0
904 );
905 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
906 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
907 st->print("allocated=" SIZE_FORMAT "%s ",
908 byte_size_in_proper_unit(allocated_bytes),
909 proper_unit_for_byte_size(allocated_bytes)
910 );
911 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
912 }
913
914 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
915 osthread()->print_on(st);
916 }
917 ThreadsSMRSupport::print_info_on(this, st);
918 st->print(" ");
919 debug_only(if (WizardMode) print_owned_locks_on(st);)
920 }
921
922 // Thread::print_on_error() is called by fatal error handler. Don't use
923 // any lock or allocate memory.
924 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
925 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
926
927 if (is_VM_thread()) { st->print("VMThread"); }
928 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
929 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
930 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
931 else { st->print("Thread"); }
932
933 if (is_Named_thread()) {
934 st->print(" \"%s\"", name());
935 }
936
937 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
938 p2i(stack_end()), p2i(stack_base()));
939
940 if (osthread()) {
941 st->print(" [id=%d]", osthread()->thread_id());
942 }
943
944 ThreadsSMRSupport::print_info_on(this, st);
945 }
946
947 void Thread::print_value_on(outputStream* st) const {
948 if (is_Named_thread()) {
949 st->print(" \"%s\" ", name());
950 }
951 st->print(INTPTR_FORMAT, p2i(this)); // print address
952 }
953
954 #ifdef ASSERT
955 void Thread::print_owned_locks_on(outputStream* st) const {
956 Monitor *cur = _owned_locks;
957 if (cur == NULL) {
958 st->print(" (no locks) ");
959 } else {
960 st->print_cr(" Locks owned:");
961 while (cur) {
962 cur->print_on(st);
963 cur = cur->next();
964 }
965 }
966 }
967
968 static int ref_use_count = 0;
969
970 bool Thread::owns_locks_but_compiled_lock() const {
971 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
972 if (cur != Compile_lock) return true;
973 }
974 return false;
975 }
976
977
978 #endif
979
980 #ifndef PRODUCT
981
982 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
983 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
984 // no locks which allow_vm_block's are held
985 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
986 // Check if current thread is allowed to block at a safepoint
987 if (!(_allow_safepoint_count == 0)) {
988 fatal("Possible safepoint reached by thread that does not allow it");
989 }
990 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
991 fatal("LEAF method calling lock?");
992 }
993
994 #ifdef ASSERT
995 if (potential_vm_operation && is_Java_thread()
996 && !Universe::is_bootstrapping()) {
997 // Make sure we do not hold any locks that the VM thread also uses.
998 // This could potentially lead to deadlocks
999 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1000 // Threads_lock is special, since the safepoint synchronization will not start before this is
1001 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1002 // since it is used to transfer control between JavaThreads and the VMThread
1003 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1004 if ((cur->allow_vm_block() &&
1005 cur != Threads_lock &&
1006 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1007 cur != VMOperationRequest_lock &&
1008 cur != VMOperationQueue_lock) ||
1009 cur->rank() == Mutex::special) {
1010 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1011 }
1012 }
1013 }
1014
1015 if (GCALotAtAllSafepoints) {
1016 // We could enter a safepoint here and thus have a gc
1017 InterfaceSupport::check_gc_alot();
1018 }
1019 #endif
1020 }
1021 #endif
1022
1023 bool Thread::is_in_stack(address adr) const {
1024 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1025 address end = os::current_stack_pointer();
1026 // Allow non Java threads to call this without stack_base
1027 if (_stack_base == NULL) return true;
1028 if (stack_base() >= adr && adr >= end) return true;
1029
1030 return false;
1031 }
1032
1033 bool Thread::is_in_usable_stack(address adr) const {
1034 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1035 size_t usable_stack_size = _stack_size - stack_guard_size;
1036
1037 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1038 }
1039
1040
1041 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1042 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1043 // used for compilation in the future. If that change is made, the need for these methods
1044 // should be revisited, and they should be removed if possible.
1045
1046 bool Thread::is_lock_owned(address adr) const {
1047 return on_local_stack(adr);
1048 }
1049
1050 bool Thread::set_as_starting_thread() {
1051 // NOTE: this must be called inside the main thread.
1052 return os::create_main_thread((JavaThread*)this);
1053 }
1054
1055 static void initialize_class(Symbol* class_name, TRAPS) {
1056 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1057 InstanceKlass::cast(klass)->initialize(CHECK);
1058 }
1059
1060
1061 // Creates the initial ThreadGroup
1062 static Handle create_initial_thread_group(TRAPS) {
1063 Handle system_instance = JavaCalls::construct_new_instance(
1064 SystemDictionary::ThreadGroup_klass(),
1065 vmSymbols::void_method_signature(),
1066 CHECK_NH);
1067 Universe::set_system_thread_group(system_instance());
1068
1069 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1070 Handle main_instance = JavaCalls::construct_new_instance(
1071 SystemDictionary::ThreadGroup_klass(),
1072 vmSymbols::threadgroup_string_void_signature(),
1073 system_instance,
1074 string,
1075 CHECK_NH);
1076 return main_instance;
1077 }
1078
1079 // Creates the initial Thread
1080 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1081 TRAPS) {
1082 InstanceKlass* ik = SystemDictionary::Thread_klass();
1083 assert(ik->is_initialized(), "must be");
1084 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1085
1086 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1087 // constructor calls Thread.current(), which must be set here for the
1088 // initial thread.
1089 java_lang_Thread::set_thread(thread_oop(), thread);
1090 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1091 thread->set_threadObj(thread_oop());
1092
1093 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1094
1095 JavaValue result(T_VOID);
1096 JavaCalls::call_special(&result, thread_oop,
1097 ik,
1098 vmSymbols::object_initializer_name(),
1099 vmSymbols::threadgroup_string_void_signature(),
1100 thread_group,
1101 string,
1102 CHECK_NULL);
1103 return thread_oop();
1104 }
1105
1106 char java_runtime_name[128] = "";
1107 char java_runtime_version[128] = "";
1108
1109 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1110 static const char* get_java_runtime_name(TRAPS) {
1111 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1112 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1113 fieldDescriptor fd;
1114 bool found = k != NULL &&
1115 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1116 vmSymbols::string_signature(), &fd);
1117 if (found) {
1118 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1119 if (name_oop == NULL) {
1120 return NULL;
1121 }
1122 const char* name = java_lang_String::as_utf8_string(name_oop,
1123 java_runtime_name,
1124 sizeof(java_runtime_name));
1125 return name;
1126 } else {
1127 return NULL;
1128 }
1129 }
1130
1131 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1132 static const char* get_java_runtime_version(TRAPS) {
1133 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1134 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1135 fieldDescriptor fd;
1136 bool found = k != NULL &&
1137 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1138 vmSymbols::string_signature(), &fd);
1139 if (found) {
1140 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1141 if (name_oop == NULL) {
1142 return NULL;
1143 }
1144 const char* name = java_lang_String::as_utf8_string(name_oop,
1145 java_runtime_version,
1146 sizeof(java_runtime_version));
1147 return name;
1148 } else {
1149 return NULL;
1150 }
1151 }
1152
1153 // General purpose hook into Java code, run once when the VM is initialized.
1154 // The Java library method itself may be changed independently from the VM.
1155 static void call_postVMInitHook(TRAPS) {
1156 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1157 if (klass != NULL) {
1158 JavaValue result(T_VOID);
1159 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1160 vmSymbols::void_method_signature(),
1161 CHECK);
1162 }
1163 }
1164
1165 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1166 bool daemon, TRAPS) {
1167 assert(thread_group.not_null(), "thread group should be specified");
1168 assert(threadObj() == NULL, "should only create Java thread object once");
1169
1170 InstanceKlass* ik = SystemDictionary::Thread_klass();
1171 assert(ik->is_initialized(), "must be");
1172 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1173
1174 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1175 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1176 // constructor calls Thread.current(), which must be set here.
1177 java_lang_Thread::set_thread(thread_oop(), this);
1178 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1179 set_threadObj(thread_oop());
1180
1181 JavaValue result(T_VOID);
1182 if (thread_name != NULL) {
1183 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1184 // Thread gets assigned specified name and null target
1185 JavaCalls::call_special(&result,
1186 thread_oop,
1187 ik,
1188 vmSymbols::object_initializer_name(),
1189 vmSymbols::threadgroup_string_void_signature(),
1190 thread_group,
1191 name,
1192 THREAD);
1193 } else {
1194 // Thread gets assigned name "Thread-nnn" and null target
1195 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1196 JavaCalls::call_special(&result,
1197 thread_oop,
1198 ik,
1199 vmSymbols::object_initializer_name(),
1200 vmSymbols::threadgroup_runnable_void_signature(),
1201 thread_group,
1202 Handle(),
1203 THREAD);
1204 }
1205
1206
1207 if (daemon) {
1208 java_lang_Thread::set_daemon(thread_oop());
1209 }
1210
1211 if (HAS_PENDING_EXCEPTION) {
1212 return;
1213 }
1214
1215 Klass* group = SystemDictionary::ThreadGroup_klass();
1216 Handle threadObj(THREAD, this->threadObj());
1217
1218 JavaCalls::call_special(&result,
1219 thread_group,
1220 group,
1221 vmSymbols::add_method_name(),
1222 vmSymbols::thread_void_signature(),
1223 threadObj, // Arg 1
1224 THREAD);
1225 }
1226
1227 // List of all NonJavaThreads and safe iteration over that list.
1228
1229 class NonJavaThread::List {
1230 public:
1231 NonJavaThread* volatile _head;
1232 SingleWriterSynchronizer _protect;
1233
1234 List() : _head(NULL), _protect() {}
1235 };
1236
1237 NonJavaThread::List NonJavaThread::_the_list;
1238
1239 NonJavaThread::Iterator::Iterator() :
1240 _protect_enter(_the_list._protect.enter()),
1241 _current(OrderAccess::load_acquire(&_the_list._head))
1242 {}
1243
1244 NonJavaThread::Iterator::~Iterator() {
1245 _the_list._protect.exit(_protect_enter);
1246 }
1247
1248 void NonJavaThread::Iterator::step() {
1249 assert(!end(), "precondition");
1250 _current = OrderAccess::load_acquire(&_current->_next);
1251 }
1252
1253 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1254 // Add this thread to _the_list.
1255 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1256 _next = _the_list._head;
1257 OrderAccess::release_store(&_the_list._head, this);
1258 }
1259
1260 NonJavaThread::~NonJavaThread() {
1261 // Remove this thread from _the_list.
1262 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1263 NonJavaThread* volatile* p = &_the_list._head;
1264 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1265 if (t == this) {
1266 *p = this->_next;
1267 // Wait for any in-progress iterators.
1268 _the_list._protect.synchronize();
1269 break;
1270 }
1271 }
1272 }
1273
1274 // NamedThread -- non-JavaThread subclasses with multiple
1275 // uniquely named instances should derive from this.
1276 NamedThread::NamedThread() :
1277 NonJavaThread(),
1278 _name(NULL),
1279 _processed_thread(NULL),
1280 _gc_id(GCId::undefined())
1281 {}
1282
1283 NamedThread::~NamedThread() {
1284 if (_name != NULL) {
1285 FREE_C_HEAP_ARRAY(char, _name);
1286 _name = NULL;
1287 }
1288 }
1289
1290 void NamedThread::set_name(const char* format, ...) {
1291 guarantee(_name == NULL, "Only get to set name once.");
1292 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1293 guarantee(_name != NULL, "alloc failure");
1294 va_list ap;
1295 va_start(ap, format);
1296 jio_vsnprintf(_name, max_name_len, format, ap);
1297 va_end(ap);
1298 }
1299
1300 void NamedThread::initialize_named_thread() {
1301 set_native_thread_name(name());
1302 }
1303
1304 void NamedThread::print_on(outputStream* st) const {
1305 st->print("\"%s\" ", name());
1306 Thread::print_on(st);
1307 st->cr();
1308 }
1309
1310
1311 // ======= WatcherThread ========
1312
1313 // The watcher thread exists to simulate timer interrupts. It should
1314 // be replaced by an abstraction over whatever native support for
1315 // timer interrupts exists on the platform.
1316
1317 WatcherThread* WatcherThread::_watcher_thread = NULL;
1318 bool WatcherThread::_startable = false;
1319 volatile bool WatcherThread::_should_terminate = false;
1320
1321 WatcherThread::WatcherThread() : NonJavaThread() {
1322 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1323 if (os::create_thread(this, os::watcher_thread)) {
1324 _watcher_thread = this;
1325
1326 // Set the watcher thread to the highest OS priority which should not be
1327 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1328 // is created. The only normal thread using this priority is the reference
1329 // handler thread, which runs for very short intervals only.
1330 // If the VMThread's priority is not lower than the WatcherThread profiling
1331 // will be inaccurate.
1332 os::set_priority(this, MaxPriority);
1333 if (!DisableStartThread) {
1334 os::start_thread(this);
1335 }
1336 }
1337 }
1338
1339 int WatcherThread::sleep() const {
1340 // The WatcherThread does not participate in the safepoint protocol
1341 // for the PeriodicTask_lock because it is not a JavaThread.
1342 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1343
1344 if (_should_terminate) {
1345 // check for termination before we do any housekeeping or wait
1346 return 0; // we did not sleep.
1347 }
1348
1349 // remaining will be zero if there are no tasks,
1350 // causing the WatcherThread to sleep until a task is
1351 // enrolled
1352 int remaining = PeriodicTask::time_to_wait();
1353 int time_slept = 0;
1354
1355 // we expect this to timeout - we only ever get unparked when
1356 // we should terminate or when a new task has been enrolled
1357 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1358
1359 jlong time_before_loop = os::javaTimeNanos();
1360
1361 while (true) {
1362 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1363 remaining);
1364 jlong now = os::javaTimeNanos();
1365
1366 if (remaining == 0) {
1367 // if we didn't have any tasks we could have waited for a long time
1368 // consider the time_slept zero and reset time_before_loop
1369 time_slept = 0;
1370 time_before_loop = now;
1371 } else {
1372 // need to recalculate since we might have new tasks in _tasks
1373 time_slept = (int) ((now - time_before_loop) / 1000000);
1374 }
1375
1376 // Change to task list or spurious wakeup of some kind
1377 if (timedout || _should_terminate) {
1378 break;
1379 }
1380
1381 remaining = PeriodicTask::time_to_wait();
1382 if (remaining == 0) {
1383 // Last task was just disenrolled so loop around and wait until
1384 // another task gets enrolled
1385 continue;
1386 }
1387
1388 remaining -= time_slept;
1389 if (remaining <= 0) {
1390 break;
1391 }
1392 }
1393
1394 return time_slept;
1395 }
1396
1397 void WatcherThread::run() {
1398 assert(this == watcher_thread(), "just checking");
1399
1400 this->set_native_thread_name(this->name());
1401 this->set_active_handles(JNIHandleBlock::allocate_block());
1402 while (true) {
1403 assert(watcher_thread() == Thread::current(), "thread consistency check");
1404 assert(watcher_thread() == this, "thread consistency check");
1405
1406 // Calculate how long it'll be until the next PeriodicTask work
1407 // should be done, and sleep that amount of time.
1408 int time_waited = sleep();
1409
1410 if (VMError::is_error_reported()) {
1411 // A fatal error has happened, the error handler(VMError::report_and_die)
1412 // should abort JVM after creating an error log file. However in some
1413 // rare cases, the error handler itself might deadlock. Here periodically
1414 // check for error reporting timeouts, and if it happens, just proceed to
1415 // abort the VM.
1416
1417 // This code is in WatcherThread because WatcherThread wakes up
1418 // periodically so the fatal error handler doesn't need to do anything;
1419 // also because the WatcherThread is less likely to crash than other
1420 // threads.
1421
1422 for (;;) {
1423 // Note: we use naked sleep in this loop because we want to avoid using
1424 // any kind of VM infrastructure which may be broken at this point.
1425 if (VMError::check_timeout()) {
1426 // We hit error reporting timeout. Error reporting was interrupted and
1427 // will be wrapping things up now (closing files etc). Give it some more
1428 // time, then quit the VM.
1429 os::naked_short_sleep(200);
1430 // Print a message to stderr.
1431 fdStream err(defaultStream::output_fd());
1432 err.print_raw_cr("# [ timer expired, abort... ]");
1433 // skip atexit/vm_exit/vm_abort hooks
1434 os::die();
1435 }
1436
1437 // Wait a second, then recheck for timeout.
1438 os::naked_short_sleep(999);
1439 }
1440 }
1441
1442 if (_should_terminate) {
1443 // check for termination before posting the next tick
1444 break;
1445 }
1446
1447 PeriodicTask::real_time_tick(time_waited);
1448 }
1449
1450 // Signal that it is terminated
1451 {
1452 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1453 _watcher_thread = NULL;
1454 Terminator_lock->notify();
1455 }
1456 }
1457
1458 void WatcherThread::start() {
1459 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1460
1461 if (watcher_thread() == NULL && _startable) {
1462 _should_terminate = false;
1463 // Create the single instance of WatcherThread
1464 new WatcherThread();
1465 }
1466 }
1467
1468 void WatcherThread::make_startable() {
1469 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1470 _startable = true;
1471 }
1472
1473 void WatcherThread::stop() {
1474 {
1475 // Follow normal safepoint aware lock enter protocol since the
1476 // WatcherThread is stopped by another JavaThread.
1477 MutexLocker ml(PeriodicTask_lock);
1478 _should_terminate = true;
1479
1480 WatcherThread* watcher = watcher_thread();
1481 if (watcher != NULL) {
1482 // unpark the WatcherThread so it can see that it should terminate
1483 watcher->unpark();
1484 }
1485 }
1486
1487 MutexLocker mu(Terminator_lock);
1488
1489 while (watcher_thread() != NULL) {
1490 // This wait should make safepoint checks, wait without a timeout,
1491 // and wait as a suspend-equivalent condition.
1492 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1493 Mutex::_as_suspend_equivalent_flag);
1494 }
1495 }
1496
1497 void WatcherThread::unpark() {
1498 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1499 PeriodicTask_lock->notify();
1500 }
1501
1502 void WatcherThread::print_on(outputStream* st) const {
1503 st->print("\"%s\" ", name());
1504 Thread::print_on(st);
1505 st->cr();
1506 }
1507
1508 // ======= JavaThread ========
1509
1510 #if INCLUDE_JVMCI
1511
1512 jlong* JavaThread::_jvmci_old_thread_counters;
1513
1514 bool jvmci_counters_include(JavaThread* thread) {
1515 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1516 }
1517
1518 void JavaThread::collect_counters(typeArrayOop array) {
1519 if (JVMCICounterSize > 0) {
1520 JavaThreadIteratorWithHandle jtiwh;
1521 for (int i = 0; i < array->length(); i++) {
1522 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1523 }
1524 for (; JavaThread *tp = jtiwh.next(); ) {
1525 if (jvmci_counters_include(tp)) {
1526 for (int i = 0; i < array->length(); i++) {
1527 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1528 }
1529 }
1530 }
1531 }
1532 }
1533
1534 #endif // INCLUDE_JVMCI
1535
1536 // A JavaThread is a normal Java thread
1537
1538 void JavaThread::initialize() {
1539 // Initialize fields
1540
1541 set_saved_exception_pc(NULL);
1542 set_threadObj(NULL);
1543 _anchor.clear();
1544 set_entry_point(NULL);
1545 set_jni_functions(jni_functions());
1546 set_callee_target(NULL);
1547 set_vm_result(NULL);
1548 set_vm_result_2(NULL);
1549 set_vframe_array_head(NULL);
1550 set_vframe_array_last(NULL);
1551 set_deferred_locals(NULL);
1552 set_deopt_mark(NULL);
1553 set_deopt_compiled_method(NULL);
1554 clear_must_deopt_id();
1555 set_monitor_chunks(NULL);
1556 set_next(NULL);
1557 _on_thread_list = false;
1558 set_thread_state(_thread_new);
1559 _terminated = _not_terminated;
1560 _array_for_gc = NULL;
1561 _suspend_equivalent = false;
1562 _in_deopt_handler = 0;
1563 _doing_unsafe_access = false;
1564 _stack_guard_state = stack_guard_unused;
1565 #if INCLUDE_JVMCI
1566 _pending_monitorenter = false;
1567 _pending_deoptimization = -1;
1568 _pending_failed_speculation = 0;
1569 _pending_transfer_to_interpreter = false;
1570 _adjusting_comp_level = false;
1571 _in_retryable_allocation = false;
1572 _jvmci._alternate_call_target = NULL;
1573 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1574 if (JVMCICounterSize > 0) {
1575 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1576 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1577 } else {
1578 _jvmci_counters = NULL;
1579 }
1580 #endif // INCLUDE_JVMCI
1581 _reserved_stack_activation = NULL; // stack base not known yet
1582 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1583 _exception_pc = 0;
1584 _exception_handler_pc = 0;
1585 _is_method_handle_return = 0;
1586 _jvmti_thread_state= NULL;
1587 _should_post_on_exceptions_flag = JNI_FALSE;
1588 _interp_only_mode = 0;
1589 _special_runtime_exit_condition = _no_async_condition;
1590 _pending_async_exception = NULL;
1591 _thread_stat = NULL;
1592 _thread_stat = new ThreadStatistics();
1593 _blocked_on_compilation = false;
1594 _jni_active_critical = 0;
1595 _pending_jni_exception_check_fn = NULL;
1596 _do_not_unlock_if_synchronized = false;
1597 _cached_monitor_info = NULL;
1598 _parker = Parker::Allocate(this);
1599
1600 #ifndef PRODUCT
1601 _jmp_ring_index = 0;
1602 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1603 record_jump(NULL, NULL, NULL, 0);
1604 }
1605 #endif // PRODUCT
1606
1607 // Setup safepoint state info for this thread
1608 ThreadSafepointState::create(this);
1609
1610 debug_only(_java_call_counter = 0);
1611
1612 // JVMTI PopFrame support
1613 _popframe_condition = popframe_inactive;
1614 _popframe_preserved_args = NULL;
1615 _popframe_preserved_args_size = 0;
1616 _frames_to_pop_failed_realloc = 0;
1617
1618 if (SafepointMechanism::uses_thread_local_poll()) {
1619 SafepointMechanism::initialize_header(this);
1620 }
1621
1622 pd_initialize();
1623 }
1624
1625 JavaThread::JavaThread(bool is_attaching_via_jni) :
1626 Thread() {
1627 initialize();
1628 if (is_attaching_via_jni) {
1629 _jni_attach_state = _attaching_via_jni;
1630 } else {
1631 _jni_attach_state = _not_attaching_via_jni;
1632 }
1633 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1634 }
1635
1636 bool JavaThread::reguard_stack(address cur_sp) {
1637 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1638 && _stack_guard_state != stack_guard_reserved_disabled) {
1639 return true; // Stack already guarded or guard pages not needed.
1640 }
1641
1642 if (register_stack_overflow()) {
1643 // For those architectures which have separate register and
1644 // memory stacks, we must check the register stack to see if
1645 // it has overflowed.
1646 return false;
1647 }
1648
1649 // Java code never executes within the yellow zone: the latter is only
1650 // there to provoke an exception during stack banging. If java code
1651 // is executing there, either StackShadowPages should be larger, or
1652 // some exception code in c1, c2 or the interpreter isn't unwinding
1653 // when it should.
1654 guarantee(cur_sp > stack_reserved_zone_base(),
1655 "not enough space to reguard - increase StackShadowPages");
1656 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1657 enable_stack_yellow_reserved_zone();
1658 if (reserved_stack_activation() != stack_base()) {
1659 set_reserved_stack_activation(stack_base());
1660 }
1661 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1662 set_reserved_stack_activation(stack_base());
1663 enable_stack_reserved_zone();
1664 }
1665 return true;
1666 }
1667
1668 bool JavaThread::reguard_stack(void) {
1669 return reguard_stack(os::current_stack_pointer());
1670 }
1671
1672
1673 void JavaThread::block_if_vm_exited() {
1674 if (_terminated == _vm_exited) {
1675 // _vm_exited is set at safepoint, and Threads_lock is never released
1676 // we will block here forever
1677 Threads_lock->lock_without_safepoint_check();
1678 ShouldNotReachHere();
1679 }
1680 }
1681
1682
1683 // Remove this ifdef when C1 is ported to the compiler interface.
1684 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1685 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1686
1687 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1688 Thread() {
1689 initialize();
1690 _jni_attach_state = _not_attaching_via_jni;
1691 set_entry_point(entry_point);
1692 // Create the native thread itself.
1693 // %note runtime_23
1694 os::ThreadType thr_type = os::java_thread;
1695 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1696 os::java_thread;
1697 os::create_thread(this, thr_type, stack_sz);
1698 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1699 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1700 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1701 // the exception consists of creating the exception object & initializing it, initialization
1702 // will leave the VM via a JavaCall and then all locks must be unlocked).
1703 //
1704 // The thread is still suspended when we reach here. Thread must be explicit started
1705 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1706 // by calling Threads:add. The reason why this is not done here, is because the thread
1707 // object must be fully initialized (take a look at JVM_Start)
1708 }
1709
1710 JavaThread::~JavaThread() {
1711
1712 // JSR166 -- return the parker to the free list
1713 Parker::Release(_parker);
1714 _parker = NULL;
1715
1716 // Free any remaining previous UnrollBlock
1717 vframeArray* old_array = vframe_array_last();
1718
1719 if (old_array != NULL) {
1720 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1721 old_array->set_unroll_block(NULL);
1722 delete old_info;
1723 delete old_array;
1724 }
1725
1726 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1727 if (deferred != NULL) {
1728 // This can only happen if thread is destroyed before deoptimization occurs.
1729 assert(deferred->length() != 0, "empty array!");
1730 do {
1731 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1732 deferred->remove_at(0);
1733 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1734 delete dlv;
1735 } while (deferred->length() != 0);
1736 delete deferred;
1737 }
1738
1739 // All Java related clean up happens in exit
1740 ThreadSafepointState::destroy(this);
1741 if (_thread_stat != NULL) delete _thread_stat;
1742
1743 #if INCLUDE_JVMCI
1744 if (JVMCICounterSize > 0) {
1745 if (jvmci_counters_include(this)) {
1746 for (int i = 0; i < JVMCICounterSize; i++) {
1747 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1748 }
1749 }
1750 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1751 }
1752 #endif // INCLUDE_JVMCI
1753 }
1754
1755
1756 // The first routine called by a new Java thread
1757 void JavaThread::run() {
1758 // initialize thread-local alloc buffer related fields
1759 this->initialize_tlab();
1760
1761 // used to test validity of stack trace backs
1762 this->record_base_of_stack_pointer();
1763
1764 this->create_stack_guard_pages();
1765
1766 this->cache_global_variables();
1767
1768 // Thread is now sufficient initialized to be handled by the safepoint code as being
1769 // in the VM. Change thread state from _thread_new to _thread_in_vm
1770 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1771
1772 assert(JavaThread::current() == this, "sanity check");
1773 assert(!Thread::current()->owns_locks(), "sanity check");
1774
1775 DTRACE_THREAD_PROBE(start, this);
1776
1777 // This operation might block. We call that after all safepoint checks for a new thread has
1778 // been completed.
1779 this->set_active_handles(JNIHandleBlock::allocate_block());
1780
1781 if (JvmtiExport::should_post_thread_life()) {
1782 JvmtiExport::post_thread_start(this);
1783 }
1784
1785 EventThreadStart event;
1786 if (event.should_commit()) {
1787 event.set_thread(JFR_THREAD_ID(this));
1788 event.commit();
1789 }
1790
1791 // We call another function to do the rest so we are sure that the stack addresses used
1792 // from there will be lower than the stack base just computed
1793 thread_main_inner();
1794
1795 // Note, thread is no longer valid at this point!
1796 }
1797
1798
1799 void JavaThread::thread_main_inner() {
1800 assert(JavaThread::current() == this, "sanity check");
1801 assert(this->threadObj() != NULL, "just checking");
1802
1803 // Execute thread entry point unless this thread has a pending exception
1804 // or has been stopped before starting.
1805 // Note: Due to JVM_StopThread we can have pending exceptions already!
1806 if (!this->has_pending_exception() &&
1807 !java_lang_Thread::is_stillborn(this->threadObj())) {
1808 {
1809 ResourceMark rm(this);
1810 this->set_native_thread_name(this->get_thread_name());
1811 }
1812 HandleMark hm(this);
1813 this->entry_point()(this, this);
1814 }
1815
1816 DTRACE_THREAD_PROBE(stop, this);
1817
1818 this->exit(false);
1819 this->smr_delete();
1820 }
1821
1822
1823 static void ensure_join(JavaThread* thread) {
1824 // We do not need to grab the Threads_lock, since we are operating on ourself.
1825 Handle threadObj(thread, thread->threadObj());
1826 assert(threadObj.not_null(), "java thread object must exist");
1827 ObjectLocker lock(threadObj, thread);
1828 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1829 thread->clear_pending_exception();
1830 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1831 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1832 // Clear the native thread instance - this makes isAlive return false and allows the join()
1833 // to complete once we've done the notify_all below
1834 java_lang_Thread::set_thread(threadObj(), NULL);
1835 lock.notify_all(thread);
1836 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1837 thread->clear_pending_exception();
1838 }
1839
1840 static bool is_daemon(oop threadObj) {
1841 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1842 }
1843
1844 // For any new cleanup additions, please check to see if they need to be applied to
1845 // cleanup_failed_attach_current_thread as well.
1846 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1847 assert(this == JavaThread::current(), "thread consistency check");
1848
1849 elapsedTimer _timer_exit_phase1;
1850 elapsedTimer _timer_exit_phase2;
1851 elapsedTimer _timer_exit_phase3;
1852 elapsedTimer _timer_exit_phase4;
1853
1854 if (log_is_enabled(Debug, os, thread, timer)) {
1855 _timer_exit_phase1.start();
1856 }
1857
1858 HandleMark hm(this);
1859 Handle uncaught_exception(this, this->pending_exception());
1860 this->clear_pending_exception();
1861 Handle threadObj(this, this->threadObj());
1862 assert(threadObj.not_null(), "Java thread object should be created");
1863
1864 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1865 {
1866 EXCEPTION_MARK;
1867
1868 CLEAR_PENDING_EXCEPTION;
1869 }
1870 if (!destroy_vm) {
1871 if (uncaught_exception.not_null()) {
1872 EXCEPTION_MARK;
1873 // Call method Thread.dispatchUncaughtException().
1874 Klass* thread_klass = SystemDictionary::Thread_klass();
1875 JavaValue result(T_VOID);
1876 JavaCalls::call_virtual(&result,
1877 threadObj, thread_klass,
1878 vmSymbols::dispatchUncaughtException_name(),
1879 vmSymbols::throwable_void_signature(),
1880 uncaught_exception,
1881 THREAD);
1882 if (HAS_PENDING_EXCEPTION) {
1883 ResourceMark rm(this);
1884 jio_fprintf(defaultStream::error_stream(),
1885 "\nException: %s thrown from the UncaughtExceptionHandler"
1886 " in thread \"%s\"\n",
1887 pending_exception()->klass()->external_name(),
1888 get_thread_name());
1889 CLEAR_PENDING_EXCEPTION;
1890 }
1891 }
1892
1893 // Called before the java thread exit since we want to read info
1894 // from java_lang_Thread object
1895 EventThreadEnd event;
1896 if (event.should_commit()) {
1897 event.set_thread(JFR_THREAD_ID(this));
1898 event.commit();
1899 }
1900
1901 // Call after last event on thread
1902 JFR_ONLY(Jfr::on_thread_exit(this);)
1903
1904 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1905 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1906 // is deprecated anyhow.
1907 if (!is_Compiler_thread()) {
1908 int count = 3;
1909 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1910 EXCEPTION_MARK;
1911 JavaValue result(T_VOID);
1912 Klass* thread_klass = SystemDictionary::Thread_klass();
1913 JavaCalls::call_virtual(&result,
1914 threadObj, thread_klass,
1915 vmSymbols::exit_method_name(),
1916 vmSymbols::void_method_signature(),
1917 THREAD);
1918 CLEAR_PENDING_EXCEPTION;
1919 }
1920 }
1921 // notify JVMTI
1922 if (JvmtiExport::should_post_thread_life()) {
1923 JvmtiExport::post_thread_end(this);
1924 }
1925
1926 // We have notified the agents that we are exiting, before we go on,
1927 // we must check for a pending external suspend request and honor it
1928 // in order to not surprise the thread that made the suspend request.
1929 while (true) {
1930 {
1931 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1932 if (!is_external_suspend()) {
1933 set_terminated(_thread_exiting);
1934 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1935 break;
1936 }
1937 // Implied else:
1938 // Things get a little tricky here. We have a pending external
1939 // suspend request, but we are holding the SR_lock so we
1940 // can't just self-suspend. So we temporarily drop the lock
1941 // and then self-suspend.
1942 }
1943
1944 ThreadBlockInVM tbivm(this);
1945 java_suspend_self();
1946
1947 // We're done with this suspend request, but we have to loop around
1948 // and check again. Eventually we will get SR_lock without a pending
1949 // external suspend request and will be able to mark ourselves as
1950 // exiting.
1951 }
1952 // no more external suspends are allowed at this point
1953 } else {
1954 assert(!is_terminated() && !is_exiting(), "must not be exiting");
1955 // before_exit() has already posted JVMTI THREAD_END events
1956 }
1957
1958 if (log_is_enabled(Debug, os, thread, timer)) {
1959 _timer_exit_phase1.stop();
1960 _timer_exit_phase2.start();
1961 }
1962 // Notify waiters on thread object. This has to be done after exit() is called
1963 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1964 // group should have the destroyed bit set before waiters are notified).
1965 ensure_join(this);
1966 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1967
1968 if (log_is_enabled(Debug, os, thread, timer)) {
1969 _timer_exit_phase2.stop();
1970 _timer_exit_phase3.start();
1971 }
1972 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1973 // held by this thread must be released. The spec does not distinguish
1974 // between JNI-acquired and regular Java monitors. We can only see
1975 // regular Java monitors here if monitor enter-exit matching is broken.
1976 //
1977 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1978 // ObjectSynchronizer::release_monitors_owned_by_thread().
1979 if (exit_type == jni_detach) {
1980 // Sanity check even though JNI DetachCurrentThread() would have
1981 // returned JNI_ERR if there was a Java frame. JavaThread exit
1982 // should be done executing Java code by the time we get here.
1983 assert(!this->has_last_Java_frame(),
1984 "should not have a Java frame when detaching or exiting");
1985 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1986 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1987 }
1988
1989 // These things needs to be done while we are still a Java Thread. Make sure that thread
1990 // is in a consistent state, in case GC happens
1991
1992 if (active_handles() != NULL) {
1993 JNIHandleBlock* block = active_handles();
1994 set_active_handles(NULL);
1995 JNIHandleBlock::release_block(block);
1996 }
1997
1998 if (free_handle_block() != NULL) {
1999 JNIHandleBlock* block = free_handle_block();
2000 set_free_handle_block(NULL);
2001 JNIHandleBlock::release_block(block);
2002 }
2003
2004 // These have to be removed while this is still a valid thread.
2005 remove_stack_guard_pages();
2006
2007 if (UseTLAB) {
2008 tlab().retire();
2009 }
2010
2011 if (JvmtiEnv::environments_might_exist()) {
2012 JvmtiExport::cleanup_thread(this);
2013 }
2014
2015 // We must flush any deferred card marks and other various GC barrier
2016 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2017 // before removing a thread from the list of active threads.
2018 BarrierSet::barrier_set()->on_thread_detach(this);
2019
2020 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2021 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2022 os::current_thread_id());
2023
2024 if (log_is_enabled(Debug, os, thread, timer)) {
2025 _timer_exit_phase3.stop();
2026 _timer_exit_phase4.start();
2027 }
2028 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2029 Threads::remove(this);
2030
2031 if (log_is_enabled(Debug, os, thread, timer)) {
2032 _timer_exit_phase4.stop();
2033 ResourceMark rm(this);
2034 log_debug(os, thread, timer)("name='%s'"
2035 ", exit-phase1=" JLONG_FORMAT
2036 ", exit-phase2=" JLONG_FORMAT
2037 ", exit-phase3=" JLONG_FORMAT
2038 ", exit-phase4=" JLONG_FORMAT,
2039 get_thread_name(),
2040 _timer_exit_phase1.milliseconds(),
2041 _timer_exit_phase2.milliseconds(),
2042 _timer_exit_phase3.milliseconds(),
2043 _timer_exit_phase4.milliseconds());
2044 }
2045 }
2046
2047 void JavaThread::cleanup_failed_attach_current_thread() {
2048 if (active_handles() != NULL) {
2049 JNIHandleBlock* block = active_handles();
2050 set_active_handles(NULL);
2051 JNIHandleBlock::release_block(block);
2052 }
2053
2054 if (free_handle_block() != NULL) {
2055 JNIHandleBlock* block = free_handle_block();
2056 set_free_handle_block(NULL);
2057 JNIHandleBlock::release_block(block);
2058 }
2059
2060 // These have to be removed while this is still a valid thread.
2061 remove_stack_guard_pages();
2062
2063 if (UseTLAB) {
2064 tlab().retire();
2065 }
2066
2067 BarrierSet::barrier_set()->on_thread_detach(this);
2068
2069 Threads::remove(this);
2070 this->smr_delete();
2071 }
2072
2073 JavaThread* JavaThread::active() {
2074 Thread* thread = Thread::current();
2075 if (thread->is_Java_thread()) {
2076 return (JavaThread*) thread;
2077 } else {
2078 assert(thread->is_VM_thread(), "this must be a vm thread");
2079 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2080 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2081 assert(ret->is_Java_thread(), "must be a Java thread");
2082 return ret;
2083 }
2084 }
2085
2086 bool JavaThread::is_lock_owned(address adr) const {
2087 if (Thread::is_lock_owned(adr)) return true;
2088
2089 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2090 if (chunk->contains(adr)) return true;
2091 }
2092
2093 return false;
2094 }
2095
2096
2097 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2098 chunk->set_next(monitor_chunks());
2099 set_monitor_chunks(chunk);
2100 }
2101
2102 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2103 guarantee(monitor_chunks() != NULL, "must be non empty");
2104 if (monitor_chunks() == chunk) {
2105 set_monitor_chunks(chunk->next());
2106 } else {
2107 MonitorChunk* prev = monitor_chunks();
2108 while (prev->next() != chunk) prev = prev->next();
2109 prev->set_next(chunk->next());
2110 }
2111 }
2112
2113 // JVM support.
2114
2115 // Note: this function shouldn't block if it's called in
2116 // _thread_in_native_trans state (such as from
2117 // check_special_condition_for_native_trans()).
2118 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2119
2120 if (has_last_Java_frame() && has_async_condition()) {
2121 // If we are at a polling page safepoint (not a poll return)
2122 // then we must defer async exception because live registers
2123 // will be clobbered by the exception path. Poll return is
2124 // ok because the call we a returning from already collides
2125 // with exception handling registers and so there is no issue.
2126 // (The exception handling path kills call result registers but
2127 // this is ok since the exception kills the result anyway).
2128
2129 if (is_at_poll_safepoint()) {
2130 // if the code we are returning to has deoptimized we must defer
2131 // the exception otherwise live registers get clobbered on the
2132 // exception path before deoptimization is able to retrieve them.
2133 //
2134 RegisterMap map(this, false);
2135 frame caller_fr = last_frame().sender(&map);
2136 assert(caller_fr.is_compiled_frame(), "what?");
2137 if (caller_fr.is_deoptimized_frame()) {
2138 log_info(exceptions)("deferred async exception at compiled safepoint");
2139 return;
2140 }
2141 }
2142 }
2143
2144 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2145 if (condition == _no_async_condition) {
2146 // Conditions have changed since has_special_runtime_exit_condition()
2147 // was called:
2148 // - if we were here only because of an external suspend request,
2149 // then that was taken care of above (or cancelled) so we are done
2150 // - if we were here because of another async request, then it has
2151 // been cleared between the has_special_runtime_exit_condition()
2152 // and now so again we are done
2153 return;
2154 }
2155
2156 // Check for pending async. exception
2157 if (_pending_async_exception != NULL) {
2158 // Only overwrite an already pending exception, if it is not a threadDeath.
2159 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2160
2161 // We cannot call Exceptions::_throw(...) here because we cannot block
2162 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2163
2164 LogTarget(Info, exceptions) lt;
2165 if (lt.is_enabled()) {
2166 ResourceMark rm;
2167 LogStream ls(lt);
2168 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2169 if (has_last_Java_frame()) {
2170 frame f = last_frame();
2171 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2172 }
2173 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2174 }
2175 _pending_async_exception = NULL;
2176 clear_has_async_exception();
2177 }
2178 }
2179
2180 if (check_unsafe_error &&
2181 condition == _async_unsafe_access_error && !has_pending_exception()) {
2182 condition = _no_async_condition; // done
2183 switch (thread_state()) {
2184 case _thread_in_vm: {
2185 JavaThread* THREAD = this;
2186 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2187 }
2188 case _thread_in_native: {
2189 ThreadInVMfromNative tiv(this);
2190 JavaThread* THREAD = this;
2191 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2192 }
2193 case _thread_in_Java: {
2194 ThreadInVMfromJava tiv(this);
2195 JavaThread* THREAD = this;
2196 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2197 }
2198 default:
2199 ShouldNotReachHere();
2200 }
2201 }
2202
2203 assert(condition == _no_async_condition || has_pending_exception() ||
2204 (!check_unsafe_error && condition == _async_unsafe_access_error),
2205 "must have handled the async condition, if no exception");
2206 }
2207
2208 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2209 //
2210 // Check for pending external suspend. Internal suspend requests do
2211 // not use handle_special_runtime_exit_condition().
2212 // If JNIEnv proxies are allowed, don't self-suspend if the target
2213 // thread is not the current thread. In older versions of jdbx, jdbx
2214 // threads could call into the VM with another thread's JNIEnv so we
2215 // can be here operating on behalf of a suspended thread (4432884).
2216 bool do_self_suspend = is_external_suspend_with_lock();
2217 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2218 //
2219 // Because thread is external suspended the safepoint code will count
2220 // thread as at a safepoint. This can be odd because we can be here
2221 // as _thread_in_Java which would normally transition to _thread_blocked
2222 // at a safepoint. We would like to mark the thread as _thread_blocked
2223 // before calling java_suspend_self like all other callers of it but
2224 // we must then observe proper safepoint protocol. (We can't leave
2225 // _thread_blocked with a safepoint in progress). However we can be
2226 // here as _thread_in_native_trans so we can't use a normal transition
2227 // constructor/destructor pair because they assert on that type of
2228 // transition. We could do something like:
2229 //
2230 // JavaThreadState state = thread_state();
2231 // set_thread_state(_thread_in_vm);
2232 // {
2233 // ThreadBlockInVM tbivm(this);
2234 // java_suspend_self()
2235 // }
2236 // set_thread_state(_thread_in_vm_trans);
2237 // if (safepoint) block;
2238 // set_thread_state(state);
2239 //
2240 // but that is pretty messy. Instead we just go with the way the
2241 // code has worked before and note that this is the only path to
2242 // java_suspend_self that doesn't put the thread in _thread_blocked
2243 // mode.
2244
2245 frame_anchor()->make_walkable(this);
2246 java_suspend_self();
2247
2248 // We might be here for reasons in addition to the self-suspend request
2249 // so check for other async requests.
2250 }
2251
2252 if (check_asyncs) {
2253 check_and_handle_async_exceptions();
2254 }
2255
2256 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2257 }
2258
2259 void JavaThread::send_thread_stop(oop java_throwable) {
2260 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2261 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2262 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2263
2264 // Do not throw asynchronous exceptions against the compiler thread
2265 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2266 if (!can_call_java()) return;
2267
2268 {
2269 // Actually throw the Throwable against the target Thread - however
2270 // only if there is no thread death exception installed already.
2271 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2272 // If the topmost frame is a runtime stub, then we are calling into
2273 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2274 // must deoptimize the caller before continuing, as the compiled exception handler table
2275 // may not be valid
2276 if (has_last_Java_frame()) {
2277 frame f = last_frame();
2278 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2279 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2280 RegisterMap reg_map(this, UseBiasedLocking);
2281 frame compiled_frame = f.sender(®_map);
2282 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2283 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2284 }
2285 }
2286 }
2287
2288 // Set async. pending exception in thread.
2289 set_pending_async_exception(java_throwable);
2290
2291 if (log_is_enabled(Info, exceptions)) {
2292 ResourceMark rm;
2293 log_info(exceptions)("Pending Async. exception installed of type: %s",
2294 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2295 }
2296 // for AbortVMOnException flag
2297 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2298 }
2299 }
2300
2301
2302 // Interrupt thread so it will wake up from a potential wait()
2303 Thread::interrupt(this);
2304 }
2305
2306 // External suspension mechanism.
2307 //
2308 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2309 // to any VM_locks and it is at a transition
2310 // Self-suspension will happen on the transition out of the vm.
2311 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2312 //
2313 // Guarantees on return:
2314 // + Target thread will not execute any new bytecode (that's why we need to
2315 // force a safepoint)
2316 // + Target thread will not enter any new monitors
2317 //
2318 void JavaThread::java_suspend() {
2319 ThreadsListHandle tlh;
2320 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2321 return;
2322 }
2323
2324 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2325 if (!is_external_suspend()) {
2326 // a racing resume has cancelled us; bail out now
2327 return;
2328 }
2329
2330 // suspend is done
2331 uint32_t debug_bits = 0;
2332 // Warning: is_ext_suspend_completed() may temporarily drop the
2333 // SR_lock to allow the thread to reach a stable thread state if
2334 // it is currently in a transient thread state.
2335 if (is_ext_suspend_completed(false /* !called_by_wait */,
2336 SuspendRetryDelay, &debug_bits)) {
2337 return;
2338 }
2339 }
2340
2341 VM_ThreadSuspend vm_suspend;
2342 VMThread::execute(&vm_suspend);
2343 }
2344
2345 // Part II of external suspension.
2346 // A JavaThread self suspends when it detects a pending external suspend
2347 // request. This is usually on transitions. It is also done in places
2348 // where continuing to the next transition would surprise the caller,
2349 // e.g., monitor entry.
2350 //
2351 // Returns the number of times that the thread self-suspended.
2352 //
2353 // Note: DO NOT call java_suspend_self() when you just want to block current
2354 // thread. java_suspend_self() is the second stage of cooperative
2355 // suspension for external suspend requests and should only be used
2356 // to complete an external suspend request.
2357 //
2358 int JavaThread::java_suspend_self() {
2359 int ret = 0;
2360
2361 // we are in the process of exiting so don't suspend
2362 if (is_exiting()) {
2363 clear_external_suspend();
2364 return ret;
2365 }
2366
2367 assert(_anchor.walkable() ||
2368 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2369 "must have walkable stack");
2370
2371 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2372
2373 assert(!this->is_ext_suspended(),
2374 "a thread trying to self-suspend should not already be suspended");
2375
2376 if (this->is_suspend_equivalent()) {
2377 // If we are self-suspending as a result of the lifting of a
2378 // suspend equivalent condition, then the suspend_equivalent
2379 // flag is not cleared until we set the ext_suspended flag so
2380 // that wait_for_ext_suspend_completion() returns consistent
2381 // results.
2382 this->clear_suspend_equivalent();
2383 }
2384
2385 // A racing resume may have cancelled us before we grabbed SR_lock
2386 // above. Or another external suspend request could be waiting for us
2387 // by the time we return from SR_lock()->wait(). The thread
2388 // that requested the suspension may already be trying to walk our
2389 // stack and if we return now, we can change the stack out from under
2390 // it. This would be a "bad thing (TM)" and cause the stack walker
2391 // to crash. We stay self-suspended until there are no more pending
2392 // external suspend requests.
2393 while (is_external_suspend()) {
2394 ret++;
2395 this->set_ext_suspended();
2396
2397 // _ext_suspended flag is cleared by java_resume()
2398 while (is_ext_suspended()) {
2399 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2400 }
2401 }
2402
2403 return ret;
2404 }
2405
2406 #ifdef ASSERT
2407 // Verify the JavaThread has not yet been published in the Threads::list, and
2408 // hence doesn't need protection from concurrent access at this stage.
2409 void JavaThread::verify_not_published() {
2410 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2411 // since an unpublished JavaThread doesn't participate in the
2412 // Thread-SMR protocol for keeping a ThreadsList alive.
2413 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2414 }
2415 #endif
2416
2417 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2418 // progress or when _suspend_flags is non-zero.
2419 // Current thread needs to self-suspend if there is a suspend request and/or
2420 // block if a safepoint is in progress.
2421 // Async exception ISN'T checked.
2422 // Note only the ThreadInVMfromNative transition can call this function
2423 // directly and when thread state is _thread_in_native_trans
2424 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2425 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2426
2427 JavaThread *curJT = JavaThread::current();
2428 bool do_self_suspend = thread->is_external_suspend();
2429
2430 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2431
2432 // If JNIEnv proxies are allowed, don't self-suspend if the target
2433 // thread is not the current thread. In older versions of jdbx, jdbx
2434 // threads could call into the VM with another thread's JNIEnv so we
2435 // can be here operating on behalf of a suspended thread (4432884).
2436 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2437 JavaThreadState state = thread->thread_state();
2438
2439 // We mark this thread_blocked state as a suspend-equivalent so
2440 // that a caller to is_ext_suspend_completed() won't be confused.
2441 // The suspend-equivalent state is cleared by java_suspend_self().
2442 thread->set_suspend_equivalent();
2443
2444 // If the safepoint code sees the _thread_in_native_trans state, it will
2445 // wait until the thread changes to other thread state. There is no
2446 // guarantee on how soon we can obtain the SR_lock and complete the
2447 // self-suspend request. It would be a bad idea to let safepoint wait for
2448 // too long. Temporarily change the state to _thread_blocked to
2449 // let the VM thread know that this thread is ready for GC. The problem
2450 // of changing thread state is that safepoint could happen just after
2451 // java_suspend_self() returns after being resumed, and VM thread will
2452 // see the _thread_blocked state. We must check for safepoint
2453 // after restoring the state and make sure we won't leave while a safepoint
2454 // is in progress.
2455 thread->set_thread_state(_thread_blocked);
2456 thread->java_suspend_self();
2457 thread->set_thread_state(state);
2458
2459 InterfaceSupport::serialize_thread_state_with_handler(thread);
2460 }
2461
2462 SafepointMechanism::block_if_requested(curJT);
2463
2464 if (thread->is_deopt_suspend()) {
2465 thread->clear_deopt_suspend();
2466 RegisterMap map(thread, false);
2467 frame f = thread->last_frame();
2468 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2469 f = f.sender(&map);
2470 }
2471 if (f.id() == thread->must_deopt_id()) {
2472 thread->clear_must_deopt_id();
2473 f.deoptimize(thread);
2474 } else {
2475 fatal("missed deoptimization!");
2476 }
2477 }
2478
2479 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2480 }
2481
2482 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2483 // progress or when _suspend_flags is non-zero.
2484 // Current thread needs to self-suspend if there is a suspend request and/or
2485 // block if a safepoint is in progress.
2486 // Also check for pending async exception (not including unsafe access error).
2487 // Note only the native==>VM/Java barriers can call this function and when
2488 // thread state is _thread_in_native_trans.
2489 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2490 check_safepoint_and_suspend_for_native_trans(thread);
2491
2492 if (thread->has_async_exception()) {
2493 // We are in _thread_in_native_trans state, don't handle unsafe
2494 // access error since that may block.
2495 thread->check_and_handle_async_exceptions(false);
2496 }
2497 }
2498
2499 // This is a variant of the normal
2500 // check_special_condition_for_native_trans with slightly different
2501 // semantics for use by critical native wrappers. It does all the
2502 // normal checks but also performs the transition back into
2503 // thread_in_Java state. This is required so that critical natives
2504 // can potentially block and perform a GC if they are the last thread
2505 // exiting the GCLocker.
2506 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2507 check_special_condition_for_native_trans(thread);
2508
2509 // Finish the transition
2510 thread->set_thread_state(_thread_in_Java);
2511
2512 if (thread->do_critical_native_unlock()) {
2513 ThreadInVMfromJavaNoAsyncException tiv(thread);
2514 GCLocker::unlock_critical(thread);
2515 thread->clear_critical_native_unlock();
2516 }
2517 }
2518
2519 // We need to guarantee the Threads_lock here, since resumes are not
2520 // allowed during safepoint synchronization
2521 // Can only resume from an external suspension
2522 void JavaThread::java_resume() {
2523 assert_locked_or_safepoint(Threads_lock);
2524
2525 // Sanity check: thread is gone, has started exiting or the thread
2526 // was not externally suspended.
2527 ThreadsListHandle tlh;
2528 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2529 return;
2530 }
2531
2532 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2533
2534 clear_external_suspend();
2535
2536 if (is_ext_suspended()) {
2537 clear_ext_suspended();
2538 SR_lock()->notify_all();
2539 }
2540 }
2541
2542 size_t JavaThread::_stack_red_zone_size = 0;
2543 size_t JavaThread::_stack_yellow_zone_size = 0;
2544 size_t JavaThread::_stack_reserved_zone_size = 0;
2545 size_t JavaThread::_stack_shadow_zone_size = 0;
2546
2547 void JavaThread::create_stack_guard_pages() {
2548 if (!os::uses_stack_guard_pages() ||
2549 _stack_guard_state != stack_guard_unused ||
2550 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2551 log_info(os, thread)("Stack guard page creation for thread "
2552 UINTX_FORMAT " disabled", os::current_thread_id());
2553 return;
2554 }
2555 address low_addr = stack_end();
2556 size_t len = stack_guard_zone_size();
2557
2558 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2559 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2560
2561 int must_commit = os::must_commit_stack_guard_pages();
2562 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2563
2564 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2565 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2566 return;
2567 }
2568
2569 if (os::guard_memory((char *) low_addr, len)) {
2570 _stack_guard_state = stack_guard_enabled;
2571 } else {
2572 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2573 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2574 if (os::uncommit_memory((char *) low_addr, len)) {
2575 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2576 }
2577 return;
2578 }
2579
2580 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2581 PTR_FORMAT "-" PTR_FORMAT ".",
2582 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2583 }
2584
2585 void JavaThread::remove_stack_guard_pages() {
2586 assert(Thread::current() == this, "from different thread");
2587 if (_stack_guard_state == stack_guard_unused) return;
2588 address low_addr = stack_end();
2589 size_t len = stack_guard_zone_size();
2590
2591 if (os::must_commit_stack_guard_pages()) {
2592 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2593 _stack_guard_state = stack_guard_unused;
2594 } else {
2595 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2596 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2597 return;
2598 }
2599 } else {
2600 if (_stack_guard_state == stack_guard_unused) return;
2601 if (os::unguard_memory((char *) low_addr, len)) {
2602 _stack_guard_state = stack_guard_unused;
2603 } else {
2604 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2605 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2606 return;
2607 }
2608 }
2609
2610 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2611 PTR_FORMAT "-" PTR_FORMAT ".",
2612 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2613 }
2614
2615 void JavaThread::enable_stack_reserved_zone() {
2616 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2617 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
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 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2624 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2625
2626 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2627 _stack_guard_state = stack_guard_enabled;
2628 } else {
2629 warning("Attempt to guard stack reserved zone failed.");
2630 }
2631 enable_register_stack_guard();
2632 }
2633
2634 void JavaThread::disable_stack_reserved_zone() {
2635 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2636 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2637
2638 // Simply return if called for a thread that does not use guard pages.
2639 if (_stack_guard_state == stack_guard_unused) return;
2640
2641 // The base notation is from the stack's point of view, growing downward.
2642 // We need to adjust it to work correctly with guard_memory()
2643 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2644
2645 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2646 _stack_guard_state = stack_guard_reserved_disabled;
2647 } else {
2648 warning("Attempt to unguard stack reserved zone failed.");
2649 }
2650 disable_register_stack_guard();
2651 }
2652
2653 void JavaThread::enable_stack_yellow_reserved_zone() {
2654 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2655 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
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 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2662 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2663
2664 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2665 _stack_guard_state = stack_guard_enabled;
2666 } else {
2667 warning("Attempt to guard stack yellow zone failed.");
2668 }
2669 enable_register_stack_guard();
2670 }
2671
2672 void JavaThread::disable_stack_yellow_reserved_zone() {
2673 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2674 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2675
2676 // Simply return if called for a thread that does not use guard pages.
2677 if (_stack_guard_state == stack_guard_unused) return;
2678
2679 // The base notation is from the stacks point of view, growing downward.
2680 // We need to adjust it to work correctly with guard_memory()
2681 address base = stack_red_zone_base();
2682
2683 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2684 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2685 } else {
2686 warning("Attempt to unguard stack yellow zone failed.");
2687 }
2688 disable_register_stack_guard();
2689 }
2690
2691 void JavaThread::enable_stack_red_zone() {
2692 // The base notation is from the stacks point of view, growing downward.
2693 // We need to adjust it to work correctly with guard_memory()
2694 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2695 address base = stack_red_zone_base() - stack_red_zone_size();
2696
2697 guarantee(base < stack_base(), "Error calculating stack red zone");
2698 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2699
2700 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2701 warning("Attempt to guard stack red zone failed.");
2702 }
2703 }
2704
2705 void JavaThread::disable_stack_red_zone() {
2706 // The base notation is from the stacks point of view, growing downward.
2707 // We need to adjust it to work correctly with guard_memory()
2708 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2709 address base = stack_red_zone_base() - stack_red_zone_size();
2710 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2711 warning("Attempt to unguard stack red zone failed.");
2712 }
2713 }
2714
2715 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2716 // ignore is there is no stack
2717 if (!has_last_Java_frame()) return;
2718 // traverse the stack frames. Starts from top frame.
2719 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2720 frame* fr = fst.current();
2721 f(fr, fst.register_map());
2722 }
2723 }
2724
2725
2726 #ifndef PRODUCT
2727 // Deoptimization
2728 // Function for testing deoptimization
2729 void JavaThread::deoptimize() {
2730 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2731 StackFrameStream fst(this, UseBiasedLocking);
2732 bool deopt = false; // Dump stack only if a deopt actually happens.
2733 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2734 // Iterate over all frames in the thread and deoptimize
2735 for (; !fst.is_done(); fst.next()) {
2736 if (fst.current()->can_be_deoptimized()) {
2737
2738 if (only_at) {
2739 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2740 // consists of comma or carriage return separated numbers so
2741 // search for the current bci in that string.
2742 address pc = fst.current()->pc();
2743 nmethod* nm = (nmethod*) fst.current()->cb();
2744 ScopeDesc* sd = nm->scope_desc_at(pc);
2745 char buffer[8];
2746 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2747 size_t len = strlen(buffer);
2748 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2749 while (found != NULL) {
2750 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2751 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2752 // Check that the bci found is bracketed by terminators.
2753 break;
2754 }
2755 found = strstr(found + 1, buffer);
2756 }
2757 if (!found) {
2758 continue;
2759 }
2760 }
2761
2762 if (DebugDeoptimization && !deopt) {
2763 deopt = true; // One-time only print before deopt
2764 tty->print_cr("[BEFORE Deoptimization]");
2765 trace_frames();
2766 trace_stack();
2767 }
2768 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2769 }
2770 }
2771
2772 if (DebugDeoptimization && deopt) {
2773 tty->print_cr("[AFTER Deoptimization]");
2774 trace_frames();
2775 }
2776 }
2777
2778
2779 // Make zombies
2780 void JavaThread::make_zombies() {
2781 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2782 if (fst.current()->can_be_deoptimized()) {
2783 // it is a Java nmethod
2784 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2785 nm->make_not_entrant();
2786 }
2787 }
2788 }
2789 #endif // PRODUCT
2790
2791
2792 void JavaThread::deoptimized_wrt_marked_nmethods() {
2793 if (!has_last_Java_frame()) return;
2794 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2795 StackFrameStream fst(this, UseBiasedLocking);
2796 for (; !fst.is_done(); fst.next()) {
2797 if (fst.current()->should_be_deoptimized()) {
2798 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2799 }
2800 }
2801 }
2802
2803
2804 // If the caller is a NamedThread, then remember, in the current scope,
2805 // the given JavaThread in its _processed_thread field.
2806 class RememberProcessedThread: public StackObj {
2807 NamedThread* _cur_thr;
2808 public:
2809 RememberProcessedThread(JavaThread* jthr) {
2810 Thread* thread = Thread::current();
2811 if (thread->is_Named_thread()) {
2812 _cur_thr = (NamedThread *)thread;
2813 _cur_thr->set_processed_thread(jthr);
2814 } else {
2815 _cur_thr = NULL;
2816 }
2817 }
2818
2819 ~RememberProcessedThread() {
2820 if (_cur_thr) {
2821 _cur_thr->set_processed_thread(NULL);
2822 }
2823 }
2824 };
2825
2826 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2827 // Verify that the deferred card marks have been flushed.
2828 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2829
2830 // Traverse the GCHandles
2831 Thread::oops_do(f, cf);
2832
2833 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2834 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2835
2836 if (has_last_Java_frame()) {
2837 // Record JavaThread to GC thread
2838 RememberProcessedThread rpt(this);
2839
2840 // traverse the registered growable array
2841 if (_array_for_gc != NULL) {
2842 for (int index = 0; index < _array_for_gc->length(); index++) {
2843 f->do_oop(_array_for_gc->adr_at(index));
2844 }
2845 }
2846
2847 // Traverse the monitor chunks
2848 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2849 chunk->oops_do(f);
2850 }
2851
2852 // Traverse the execution stack
2853 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2854 fst.current()->oops_do(f, cf, fst.register_map());
2855 }
2856 }
2857
2858 // callee_target is never live across a gc point so NULL it here should
2859 // it still contain a methdOop.
2860
2861 set_callee_target(NULL);
2862
2863 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2864 // If we have deferred set_locals there might be oops waiting to be
2865 // written
2866 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2867 if (list != NULL) {
2868 for (int i = 0; i < list->length(); i++) {
2869 list->at(i)->oops_do(f);
2870 }
2871 }
2872
2873 // Traverse instance variables at the end since the GC may be moving things
2874 // around using this function
2875 f->do_oop((oop*) &_threadObj);
2876 f->do_oop((oop*) &_vm_result);
2877 f->do_oop((oop*) &_exception_oop);
2878 f->do_oop((oop*) &_pending_async_exception);
2879
2880 if (jvmti_thread_state() != NULL) {
2881 jvmti_thread_state()->oops_do(f);
2882 }
2883 }
2884
2885 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2886 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2887 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2888
2889 if (has_last_Java_frame()) {
2890 // Traverse the execution stack
2891 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2892 fst.current()->nmethods_do(cf);
2893 }
2894 }
2895 }
2896
2897 void JavaThread::metadata_do(void f(Metadata*)) {
2898 if (has_last_Java_frame()) {
2899 // Traverse the execution stack to call f() on the methods in the stack
2900 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2901 fst.current()->metadata_do(f);
2902 }
2903 } else if (is_Compiler_thread()) {
2904 // need to walk ciMetadata in current compile tasks to keep alive.
2905 CompilerThread* ct = (CompilerThread*)this;
2906 if (ct->env() != NULL) {
2907 ct->env()->metadata_do(f);
2908 }
2909 CompileTask* task = ct->task();
2910 if (task != NULL) {
2911 task->metadata_do(f);
2912 }
2913 }
2914 }
2915
2916 // Printing
2917 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2918 switch (_thread_state) {
2919 case _thread_uninitialized: return "_thread_uninitialized";
2920 case _thread_new: return "_thread_new";
2921 case _thread_new_trans: return "_thread_new_trans";
2922 case _thread_in_native: return "_thread_in_native";
2923 case _thread_in_native_trans: return "_thread_in_native_trans";
2924 case _thread_in_vm: return "_thread_in_vm";
2925 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2926 case _thread_in_Java: return "_thread_in_Java";
2927 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2928 case _thread_blocked: return "_thread_blocked";
2929 case _thread_blocked_trans: return "_thread_blocked_trans";
2930 default: return "unknown thread state";
2931 }
2932 }
2933
2934 #ifndef PRODUCT
2935 void JavaThread::print_thread_state_on(outputStream *st) const {
2936 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2937 };
2938 void JavaThread::print_thread_state() const {
2939 print_thread_state_on(tty);
2940 }
2941 #endif // PRODUCT
2942
2943 // Called by Threads::print() for VM_PrintThreads operation
2944 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2945 st->print_raw("\"");
2946 st->print_raw(get_thread_name());
2947 st->print_raw("\" ");
2948 oop thread_oop = threadObj();
2949 if (thread_oop != NULL) {
2950 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2951 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2952 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2953 }
2954 Thread::print_on(st, print_extended_info);
2955 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2956 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2957 if (thread_oop != NULL) {
2958 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2959 }
2960 #ifndef PRODUCT
2961 print_thread_state_on(st);
2962 _safepoint_state->print_on(st);
2963 #endif // PRODUCT
2964 if (is_Compiler_thread()) {
2965 CompileTask *task = ((CompilerThread*)this)->task();
2966 if (task != NULL) {
2967 st->print(" Compiling: ");
2968 task->print(st, NULL, true, false);
2969 } else {
2970 st->print(" No compile task");
2971 }
2972 st->cr();
2973 }
2974 }
2975
2976 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2977 st->print("%s", get_thread_name_string(buf, buflen));
2978 }
2979
2980 // Called by fatal error handler. The difference between this and
2981 // JavaThread::print() is that we can't grab lock or allocate memory.
2982 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2983 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2984 oop thread_obj = threadObj();
2985 if (thread_obj != NULL) {
2986 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2987 }
2988 st->print(" [");
2989 st->print("%s", _get_thread_state_name(_thread_state));
2990 if (osthread()) {
2991 st->print(", id=%d", osthread()->thread_id());
2992 }
2993 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2994 p2i(stack_end()), p2i(stack_base()));
2995 st->print("]");
2996
2997 ThreadsSMRSupport::print_info_on(this, st);
2998 return;
2999 }
3000
3001 // Verification
3002
3003 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3004
3005 void JavaThread::verify() {
3006 // Verify oops in the thread.
3007 oops_do(&VerifyOopClosure::verify_oop, NULL);
3008
3009 // Verify the stack frames.
3010 frames_do(frame_verify);
3011 }
3012
3013 // CR 6300358 (sub-CR 2137150)
3014 // Most callers of this method assume that it can't return NULL but a
3015 // thread may not have a name whilst it is in the process of attaching to
3016 // the VM - see CR 6412693, and there are places where a JavaThread can be
3017 // seen prior to having it's threadObj set (eg JNI attaching threads and
3018 // if vm exit occurs during initialization). These cases can all be accounted
3019 // for such that this method never returns NULL.
3020 const char* JavaThread::get_thread_name() const {
3021 #ifdef ASSERT
3022 // early safepoints can hit while current thread does not yet have TLS
3023 if (!SafepointSynchronize::is_at_safepoint()) {
3024 Thread *cur = Thread::current();
3025 if (!(cur->is_Java_thread() && cur == this)) {
3026 // Current JavaThreads are allowed to get their own name without
3027 // the Threads_lock.
3028 assert_locked_or_safepoint(Threads_lock);
3029 }
3030 }
3031 #endif // ASSERT
3032 return get_thread_name_string();
3033 }
3034
3035 // Returns a non-NULL representation of this thread's name, or a suitable
3036 // descriptive string if there is no set name
3037 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3038 const char* name_str;
3039 oop thread_obj = threadObj();
3040 if (thread_obj != NULL) {
3041 oop name = java_lang_Thread::name(thread_obj);
3042 if (name != NULL) {
3043 if (buf == NULL) {
3044 name_str = java_lang_String::as_utf8_string(name);
3045 } else {
3046 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3047 }
3048 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3049 name_str = "<no-name - thread is attaching>";
3050 } else {
3051 name_str = Thread::name();
3052 }
3053 } else {
3054 name_str = Thread::name();
3055 }
3056 assert(name_str != NULL, "unexpected NULL thread name");
3057 return name_str;
3058 }
3059
3060
3061 const char* JavaThread::get_threadgroup_name() const {
3062 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3063 oop thread_obj = threadObj();
3064 if (thread_obj != NULL) {
3065 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3066 if (thread_group != NULL) {
3067 // ThreadGroup.name can be null
3068 return java_lang_ThreadGroup::name(thread_group);
3069 }
3070 }
3071 return NULL;
3072 }
3073
3074 const char* JavaThread::get_parent_name() const {
3075 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3076 oop thread_obj = threadObj();
3077 if (thread_obj != NULL) {
3078 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3079 if (thread_group != NULL) {
3080 oop parent = java_lang_ThreadGroup::parent(thread_group);
3081 if (parent != NULL) {
3082 // ThreadGroup.name can be null
3083 return java_lang_ThreadGroup::name(parent);
3084 }
3085 }
3086 }
3087 return NULL;
3088 }
3089
3090 ThreadPriority JavaThread::java_priority() const {
3091 oop thr_oop = threadObj();
3092 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3093 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3094 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3095 return priority;
3096 }
3097
3098 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3099
3100 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3101 // Link Java Thread object <-> C++ Thread
3102
3103 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3104 // and put it into a new Handle. The Handle "thread_oop" can then
3105 // be used to pass the C++ thread object to other methods.
3106
3107 // Set the Java level thread object (jthread) field of the
3108 // new thread (a JavaThread *) to C++ thread object using the
3109 // "thread_oop" handle.
3110
3111 // Set the thread field (a JavaThread *) of the
3112 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3113
3114 Handle thread_oop(Thread::current(),
3115 JNIHandles::resolve_non_null(jni_thread));
3116 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3117 "must be initialized");
3118 set_threadObj(thread_oop());
3119 java_lang_Thread::set_thread(thread_oop(), this);
3120
3121 if (prio == NoPriority) {
3122 prio = java_lang_Thread::priority(thread_oop());
3123 assert(prio != NoPriority, "A valid priority should be present");
3124 }
3125
3126 // Push the Java priority down to the native thread; needs Threads_lock
3127 Thread::set_priority(this, prio);
3128
3129 // Add the new thread to the Threads list and set it in motion.
3130 // We must have threads lock in order to call Threads::add.
3131 // It is crucial that we do not block before the thread is
3132 // added to the Threads list for if a GC happens, then the java_thread oop
3133 // will not be visited by GC.
3134 Threads::add(this);
3135 }
3136
3137 oop JavaThread::current_park_blocker() {
3138 // Support for JSR-166 locks
3139 oop thread_oop = threadObj();
3140 if (thread_oop != NULL &&
3141 JDK_Version::current().supports_thread_park_blocker()) {
3142 return java_lang_Thread::park_blocker(thread_oop);
3143 }
3144 return NULL;
3145 }
3146
3147
3148 void JavaThread::print_stack_on(outputStream* st) {
3149 if (!has_last_Java_frame()) return;
3150 ResourceMark rm;
3151 HandleMark hm;
3152
3153 RegisterMap reg_map(this);
3154 vframe* start_vf = last_java_vframe(®_map);
3155 int count = 0;
3156 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3157 if (f->is_java_frame()) {
3158 javaVFrame* jvf = javaVFrame::cast(f);
3159 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3160
3161 // Print out lock information
3162 if (JavaMonitorsInStackTrace) {
3163 jvf->print_lock_info_on(st, count);
3164 }
3165 } else {
3166 // Ignore non-Java frames
3167 }
3168
3169 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3170 count++;
3171 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3172 }
3173 }
3174
3175
3176 // JVMTI PopFrame support
3177 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3178 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3179 if (in_bytes(size_in_bytes) != 0) {
3180 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3181 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3182 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3183 }
3184 }
3185
3186 void* JavaThread::popframe_preserved_args() {
3187 return _popframe_preserved_args;
3188 }
3189
3190 ByteSize JavaThread::popframe_preserved_args_size() {
3191 return in_ByteSize(_popframe_preserved_args_size);
3192 }
3193
3194 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3195 int sz = in_bytes(popframe_preserved_args_size());
3196 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3197 return in_WordSize(sz / wordSize);
3198 }
3199
3200 void JavaThread::popframe_free_preserved_args() {
3201 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3202 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3203 _popframe_preserved_args = NULL;
3204 _popframe_preserved_args_size = 0;
3205 }
3206
3207 #ifndef PRODUCT
3208
3209 void JavaThread::trace_frames() {
3210 tty->print_cr("[Describe stack]");
3211 int frame_no = 1;
3212 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3213 tty->print(" %d. ", frame_no++);
3214 fst.current()->print_value_on(tty, this);
3215 tty->cr();
3216 }
3217 }
3218
3219 class PrintAndVerifyOopClosure: public OopClosure {
3220 protected:
3221 template <class T> inline void do_oop_work(T* p) {
3222 oop obj = RawAccess<>::oop_load(p);
3223 if (obj == NULL) return;
3224 tty->print(INTPTR_FORMAT ": ", p2i(p));
3225 if (oopDesc::is_oop_or_null(obj)) {
3226 if (obj->is_objArray()) {
3227 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3228 } else {
3229 obj->print();
3230 }
3231 } else {
3232 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3233 }
3234 tty->cr();
3235 }
3236 public:
3237 virtual void do_oop(oop* p) { do_oop_work(p); }
3238 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3239 };
3240
3241
3242 static void oops_print(frame* f, const RegisterMap *map) {
3243 PrintAndVerifyOopClosure print;
3244 f->print_value();
3245 f->oops_do(&print, NULL, (RegisterMap*)map);
3246 }
3247
3248 // Print our all the locations that contain oops and whether they are
3249 // valid or not. This useful when trying to find the oldest frame
3250 // where an oop has gone bad since the frame walk is from youngest to
3251 // oldest.
3252 void JavaThread::trace_oops() {
3253 tty->print_cr("[Trace oops]");
3254 frames_do(oops_print);
3255 }
3256
3257
3258 #ifdef ASSERT
3259 // Print or validate the layout of stack frames
3260 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3261 ResourceMark rm;
3262 PRESERVE_EXCEPTION_MARK;
3263 FrameValues values;
3264 int frame_no = 0;
3265 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3266 fst.current()->describe(values, ++frame_no);
3267 if (depth == frame_no) break;
3268 }
3269 if (validate_only) {
3270 values.validate();
3271 } else {
3272 tty->print_cr("[Describe stack layout]");
3273 values.print(this);
3274 }
3275 }
3276 #endif
3277
3278 void JavaThread::trace_stack_from(vframe* start_vf) {
3279 ResourceMark rm;
3280 int vframe_no = 1;
3281 for (vframe* f = start_vf; f; f = f->sender()) {
3282 if (f->is_java_frame()) {
3283 javaVFrame::cast(f)->print_activation(vframe_no++);
3284 } else {
3285 f->print();
3286 }
3287 if (vframe_no > StackPrintLimit) {
3288 tty->print_cr("...<more frames>...");
3289 return;
3290 }
3291 }
3292 }
3293
3294
3295 void JavaThread::trace_stack() {
3296 if (!has_last_Java_frame()) return;
3297 ResourceMark rm;
3298 HandleMark hm;
3299 RegisterMap reg_map(this);
3300 trace_stack_from(last_java_vframe(®_map));
3301 }
3302
3303
3304 #endif // PRODUCT
3305
3306
3307 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3308 assert(reg_map != NULL, "a map must be given");
3309 frame f = last_frame();
3310 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3311 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3312 }
3313 return NULL;
3314 }
3315
3316
3317 Klass* JavaThread::security_get_caller_class(int depth) {
3318 vframeStream vfst(this);
3319 vfst.security_get_caller_frame(depth);
3320 if (!vfst.at_end()) {
3321 return vfst.method()->method_holder();
3322 }
3323 return NULL;
3324 }
3325
3326 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3327 assert(thread->is_Compiler_thread(), "must be compiler thread");
3328 CompileBroker::compiler_thread_loop();
3329 }
3330
3331 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3332 NMethodSweeper::sweeper_loop();
3333 }
3334
3335 // Create a CompilerThread
3336 CompilerThread::CompilerThread(CompileQueue* queue,
3337 CompilerCounters* counters)
3338 : JavaThread(&compiler_thread_entry) {
3339 _env = NULL;
3340 _log = NULL;
3341 _task = NULL;
3342 _queue = queue;
3343 _counters = counters;
3344 _buffer_blob = NULL;
3345 _compiler = NULL;
3346
3347 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3348 resource_area()->bias_to(mtCompiler);
3349
3350 #ifndef PRODUCT
3351 _ideal_graph_printer = NULL;
3352 #endif
3353 }
3354
3355 CompilerThread::~CompilerThread() {
3356 // Delete objects which were allocated on heap.
3357 delete _counters;
3358 }
3359
3360 bool CompilerThread::can_call_java() const {
3361 return _compiler != NULL && _compiler->is_jvmci();
3362 }
3363
3364 // Create sweeper thread
3365 CodeCacheSweeperThread::CodeCacheSweeperThread()
3366 : JavaThread(&sweeper_thread_entry) {
3367 _scanned_compiled_method = NULL;
3368 }
3369
3370 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3371 JavaThread::oops_do(f, cf);
3372 if (_scanned_compiled_method != NULL && cf != NULL) {
3373 // Safepoints can occur when the sweeper is scanning an nmethod so
3374 // process it here to make sure it isn't unloaded in the middle of
3375 // a scan.
3376 cf->do_code_blob(_scanned_compiled_method);
3377 }
3378 }
3379
3380 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3381 JavaThread::nmethods_do(cf);
3382 if (_scanned_compiled_method != NULL && cf != NULL) {
3383 // Safepoints can occur when the sweeper is scanning an nmethod so
3384 // process it here to make sure it isn't unloaded in the middle of
3385 // a scan.
3386 cf->do_code_blob(_scanned_compiled_method);
3387 }
3388 }
3389
3390
3391 // ======= Threads ========
3392
3393 // The Threads class links together all active threads, and provides
3394 // operations over all threads. It is protected by the Threads_lock,
3395 // which is also used in other global contexts like safepointing.
3396 // ThreadsListHandles are used to safely perform operations on one
3397 // or more threads without the risk of the thread exiting during the
3398 // operation.
3399 //
3400 // Note: The Threads_lock is currently more widely used than we
3401 // would like. We are actively migrating Threads_lock uses to other
3402 // mechanisms in order to reduce Threads_lock contention.
3403
3404 JavaThread* Threads::_thread_list = NULL;
3405 int Threads::_number_of_threads = 0;
3406 int Threads::_number_of_non_daemon_threads = 0;
3407 int Threads::_return_code = 0;
3408 int Threads::_thread_claim_parity = 0;
3409 size_t JavaThread::_stack_size_at_create = 0;
3410
3411 #ifdef ASSERT
3412 bool Threads::_vm_complete = false;
3413 size_t Threads::_threads_before_barrier_set = 0;
3414 #endif
3415
3416 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3417 Prefetch::read((void*)addr, prefetch_interval);
3418 return *addr;
3419 }
3420
3421 // Possibly the ugliest for loop the world has seen. C++ does not allow
3422 // multiple types in the declaration section of the for loop. In this case
3423 // we are only dealing with pointers and hence can cast them. It looks ugly
3424 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3425 #define DO_JAVA_THREADS(LIST, X) \
3426 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3427 *MACRO_list = (JavaThread*)(LIST), \
3428 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3429 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3430 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3431 MACRO_current_p != MACRO_end; \
3432 MACRO_current_p++, \
3433 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3434
3435 // All JavaThreads
3436 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3437
3438 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3439 void Threads::non_java_threads_do(ThreadClosure* tc) {
3440 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3441 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3442 tc->do_thread(njti.current());
3443 }
3444 }
3445
3446 // All JavaThreads
3447 void Threads::java_threads_do(ThreadClosure* tc) {
3448 assert_locked_or_safepoint(Threads_lock);
3449 // ALL_JAVA_THREADS iterates through all JavaThreads.
3450 ALL_JAVA_THREADS(p) {
3451 tc->do_thread(p);
3452 }
3453 }
3454
3455 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3456 assert_locked_or_safepoint(Threads_lock);
3457 java_threads_do(tc);
3458 tc->do_thread(VMThread::vm_thread());
3459 }
3460
3461 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3462 void Threads::threads_do(ThreadClosure* tc) {
3463 assert_locked_or_safepoint(Threads_lock);
3464 java_threads_do(tc);
3465 non_java_threads_do(tc);
3466 }
3467
3468 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3469 int cp = Threads::thread_claim_parity();
3470 ALL_JAVA_THREADS(p) {
3471 if (p->claim_oops_do(is_par, cp)) {
3472 tc->do_thread(p);
3473 }
3474 }
3475 VMThread* vmt = VMThread::vm_thread();
3476 if (vmt->claim_oops_do(is_par, cp)) {
3477 tc->do_thread(vmt);
3478 }
3479 }
3480
3481 // The system initialization in the library has three phases.
3482 //
3483 // Phase 1: java.lang.System class initialization
3484 // java.lang.System is a primordial class loaded and initialized
3485 // by the VM early during startup. java.lang.System.<clinit>
3486 // only does registerNatives and keeps the rest of the class
3487 // initialization work later until thread initialization completes.
3488 //
3489 // System.initPhase1 initializes the system properties, the static
3490 // fields in, out, and err. Set up java signal handlers, OS-specific
3491 // system settings, and thread group of the main thread.
3492 static void call_initPhase1(TRAPS) {
3493 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3494 JavaValue result(T_VOID);
3495 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3496 vmSymbols::void_method_signature(), CHECK);
3497 }
3498
3499 // Phase 2. Module system initialization
3500 // This will initialize the module system. Only java.base classes
3501 // can be loaded until phase 2 completes.
3502 //
3503 // Call System.initPhase2 after the compiler initialization and jsr292
3504 // classes get initialized because module initialization runs a lot of java
3505 // code, that for performance reasons, should be compiled. Also, this will
3506 // enable the startup code to use lambda and other language features in this
3507 // phase and onward.
3508 //
3509 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3510 static void call_initPhase2(TRAPS) {
3511 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3512
3513 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3514
3515 JavaValue result(T_INT);
3516 JavaCallArguments args;
3517 args.push_int(DisplayVMOutputToStderr);
3518 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3519 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3520 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3521 if (result.get_jint() != JNI_OK) {
3522 vm_exit_during_initialization(); // no message or exception
3523 }
3524
3525 universe_post_module_init();
3526 }
3527
3528 // Phase 3. final setup - set security manager, system class loader and TCCL
3529 //
3530 // This will instantiate and set the security manager, set the system class
3531 // loader as well as the thread context class loader. The security manager
3532 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3533 // other modules or the application's classpath.
3534 static void call_initPhase3(TRAPS) {
3535 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3536 JavaValue result(T_VOID);
3537 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3538 vmSymbols::void_method_signature(), CHECK);
3539 }
3540
3541 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3542 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3543
3544 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3545 create_vm_init_libraries();
3546 }
3547
3548 initialize_class(vmSymbols::java_lang_String(), CHECK);
3549
3550 // Inject CompactStrings value after the static initializers for String ran.
3551 java_lang_String::set_compact_strings(CompactStrings);
3552
3553 // Initialize java_lang.System (needed before creating the thread)
3554 initialize_class(vmSymbols::java_lang_System(), CHECK);
3555 // The VM creates & returns objects of this class. Make sure it's initialized.
3556 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3557 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3558 Handle thread_group = create_initial_thread_group(CHECK);
3559 Universe::set_main_thread_group(thread_group());
3560 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3561 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3562 main_thread->set_threadObj(thread_object);
3563 // Set thread status to running since main thread has
3564 // been started and running.
3565 java_lang_Thread::set_thread_status(thread_object,
3566 java_lang_Thread::RUNNABLE);
3567
3568 // The VM creates objects of this class.
3569 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3570
3571 // The VM preresolves methods to these classes. Make sure that they get initialized
3572 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3573 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3574
3575 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3576 call_initPhase1(CHECK);
3577
3578 // get the Java runtime name after java.lang.System is initialized
3579 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3580 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3581
3582 // an instance of OutOfMemory exception has been allocated earlier
3583 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3584 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3585 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3586 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3587 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3588 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3589 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3590 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3591 }
3592
3593 void Threads::initialize_jsr292_core_classes(TRAPS) {
3594 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3595
3596 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3597 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3598 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3599 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3600 }
3601
3602 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3603 extern void JDK_Version_init();
3604
3605 // Preinitialize version info.
3606 VM_Version::early_initialize();
3607
3608 // Check version
3609 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3610
3611 // Initialize library-based TLS
3612 ThreadLocalStorage::init();
3613
3614 // Initialize the output stream module
3615 ostream_init();
3616
3617 // Process java launcher properties.
3618 Arguments::process_sun_java_launcher_properties(args);
3619
3620 // Initialize the os module
3621 os::init();
3622
3623 // Record VM creation timing statistics
3624 TraceVmCreationTime create_vm_timer;
3625 create_vm_timer.start();
3626
3627 // Initialize system properties.
3628 Arguments::init_system_properties();
3629
3630 // So that JDK version can be used as a discriminator when parsing arguments
3631 JDK_Version_init();
3632
3633 // Update/Initialize System properties after JDK version number is known
3634 Arguments::init_version_specific_system_properties();
3635
3636 // Make sure to initialize log configuration *before* parsing arguments
3637 LogConfiguration::initialize(create_vm_timer.begin_time());
3638
3639 // Parse arguments
3640 // Note: this internally calls os::init_container_support()
3641 jint parse_result = Arguments::parse(args);
3642 if (parse_result != JNI_OK) return parse_result;
3643
3644 os::init_before_ergo();
3645
3646 jint ergo_result = Arguments::apply_ergo();
3647 if (ergo_result != JNI_OK) return ergo_result;
3648
3649 // Final check of all ranges after ergonomics which may change values.
3650 if (!JVMFlagRangeList::check_ranges()) {
3651 return JNI_EINVAL;
3652 }
3653
3654 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3655 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3656 if (!constraint_result) {
3657 return JNI_EINVAL;
3658 }
3659
3660 JVMFlagWriteableList::mark_startup();
3661
3662 if (PauseAtStartup) {
3663 os::pause();
3664 }
3665
3666 HOTSPOT_VM_INIT_BEGIN();
3667
3668 // Timing (must come after argument parsing)
3669 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3670
3671 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3672 // Initialize assert poison page mechanism.
3673 if (ShowRegistersOnAssert) {
3674 initialize_assert_poison();
3675 }
3676 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3677
3678 // Initialize the os module after parsing the args
3679 jint os_init_2_result = os::init_2();
3680 if (os_init_2_result != JNI_OK) return os_init_2_result;
3681
3682 SafepointMechanism::initialize();
3683
3684 jint adjust_after_os_result = Arguments::adjust_after_os();
3685 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3686
3687 // Initialize output stream logging
3688 ostream_init_log();
3689
3690 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3691 // Must be before create_vm_init_agents()
3692 if (Arguments::init_libraries_at_startup()) {
3693 convert_vm_init_libraries_to_agents();
3694 }
3695
3696 // Launch -agentlib/-agentpath and converted -Xrun agents
3697 if (Arguments::init_agents_at_startup()) {
3698 create_vm_init_agents();
3699 }
3700
3701 // Initialize Threads state
3702 _thread_list = NULL;
3703 _number_of_threads = 0;
3704 _number_of_non_daemon_threads = 0;
3705
3706 // Initialize global data structures and create system classes in heap
3707 vm_init_globals();
3708
3709 #if INCLUDE_JVMCI
3710 if (JVMCICounterSize > 0) {
3711 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3712 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3713 } else {
3714 JavaThread::_jvmci_old_thread_counters = NULL;
3715 }
3716 #endif // INCLUDE_JVMCI
3717
3718 // Attach the main thread to this os thread
3719 JavaThread* main_thread = new JavaThread();
3720 main_thread->set_thread_state(_thread_in_vm);
3721 main_thread->initialize_thread_current();
3722 // must do this before set_active_handles
3723 main_thread->record_stack_base_and_size();
3724 main_thread->register_thread_stack_with_NMT();
3725 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3726
3727 if (!main_thread->set_as_starting_thread()) {
3728 vm_shutdown_during_initialization(
3729 "Failed necessary internal allocation. Out of swap space");
3730 main_thread->smr_delete();
3731 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3732 return JNI_ENOMEM;
3733 }
3734
3735 // Enable guard page *after* os::create_main_thread(), otherwise it would
3736 // crash Linux VM, see notes in os_linux.cpp.
3737 main_thread->create_stack_guard_pages();
3738
3739 // Initialize Java-Level synchronization subsystem
3740 ObjectMonitor::Initialize();
3741
3742 // Initialize global modules
3743 jint status = init_globals();
3744 if (status != JNI_OK) {
3745 main_thread->smr_delete();
3746 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3747 return status;
3748 }
3749
3750 JFR_ONLY(Jfr::on_vm_init();)
3751
3752 // Should be done after the heap is fully created
3753 main_thread->cache_global_variables();
3754
3755 HandleMark hm;
3756
3757 { MutexLocker mu(Threads_lock);
3758 Threads::add(main_thread);
3759 }
3760
3761 // Any JVMTI raw monitors entered in onload will transition into
3762 // real raw monitor. VM is setup enough here for raw monitor enter.
3763 JvmtiExport::transition_pending_onload_raw_monitors();
3764
3765 // Create the VMThread
3766 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3767
3768 VMThread::create();
3769 Thread* vmthread = VMThread::vm_thread();
3770
3771 if (!os::create_thread(vmthread, os::vm_thread)) {
3772 vm_exit_during_initialization("Cannot create VM thread. "
3773 "Out of system resources.");
3774 }
3775
3776 // Wait for the VM thread to become ready, and VMThread::run to initialize
3777 // Monitors can have spurious returns, must always check another state flag
3778 {
3779 MutexLocker ml(Notify_lock);
3780 os::start_thread(vmthread);
3781 while (vmthread->active_handles() == NULL) {
3782 Notify_lock->wait();
3783 }
3784 }
3785 }
3786
3787 assert(Universe::is_fully_initialized(), "not initialized");
3788 if (VerifyDuringStartup) {
3789 // Make sure we're starting with a clean slate.
3790 VM_Verify verify_op;
3791 VMThread::execute(&verify_op);
3792 }
3793
3794 // We need this to update the java.vm.info property in case any flags used
3795 // to initially define it have been changed. This is needed for both CDS and
3796 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3797 // is initially computed. See Abstract_VM_Version::vm_info_string().
3798 // This update must happen before we initialize the java classes, but
3799 // after any initialization logic that might modify the flags.
3800 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3801
3802 Thread* THREAD = Thread::current();
3803
3804 // Always call even when there are not JVMTI environments yet, since environments
3805 // may be attached late and JVMTI must track phases of VM execution
3806 JvmtiExport::enter_early_start_phase();
3807
3808 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3809 JvmtiExport::post_early_vm_start();
3810
3811 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3812
3813 quicken_jni_functions();
3814
3815 // No more stub generation allowed after that point.
3816 StubCodeDesc::freeze();
3817
3818 // Set flag that basic initialization has completed. Used by exceptions and various
3819 // debug stuff, that does not work until all basic classes have been initialized.
3820 set_init_completed();
3821
3822 LogConfiguration::post_initialize();
3823 Metaspace::post_initialize();
3824
3825 HOTSPOT_VM_INIT_END();
3826
3827 // record VM initialization completion time
3828 #if INCLUDE_MANAGEMENT
3829 Management::record_vm_init_completed();
3830 #endif // INCLUDE_MANAGEMENT
3831
3832 // Signal Dispatcher needs to be started before VMInit event is posted
3833 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3834
3835 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3836 if (!DisableAttachMechanism) {
3837 AttachListener::vm_start();
3838 if (StartAttachListener || AttachListener::init_at_startup()) {
3839 AttachListener::init();
3840 }
3841 }
3842
3843 // Launch -Xrun agents
3844 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3845 // back-end can launch with -Xdebug -Xrunjdwp.
3846 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3847 create_vm_init_libraries();
3848 }
3849
3850 if (CleanChunkPoolAsync) {
3851 Chunk::start_chunk_pool_cleaner_task();
3852 }
3853
3854 // initialize compiler(s)
3855 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3856 #if INCLUDE_JVMCI
3857 bool force_JVMCI_intialization = false;
3858 if (EnableJVMCI) {
3859 // Initialize JVMCI eagerly when it is explicitly requested.
3860 // Or when JVMCIPrintProperties is enabled.
3861 // The JVMCI Java initialization code will read this flag and
3862 // do the printing if it's set.
3863 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3864
3865 if (!force_JVMCI_intialization) {
3866 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3867 // compilations via JVMCI will not actually block until JVMCI is initialized.
3868 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3869 }
3870 }
3871 #endif
3872 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3873 // Postpone completion of compiler initialization to after JVMCI
3874 // is initialized to avoid timeouts of blocking compilations.
3875 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3876 CompileBroker::compilation_init_phase2();
3877 }
3878 #endif
3879
3880 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3881 // It is done after compilers are initialized, because otherwise compilations of
3882 // signature polymorphic MH intrinsics can be missed
3883 // (see SystemDictionary::find_method_handle_intrinsic).
3884 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3885
3886 // This will initialize the module system. Only java.base classes can be
3887 // loaded until phase 2 completes
3888 call_initPhase2(CHECK_JNI_ERR);
3889
3890 // Always call even when there are not JVMTI environments yet, since environments
3891 // may be attached late and JVMTI must track phases of VM execution
3892 JvmtiExport::enter_start_phase();
3893
3894 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3895 JvmtiExport::post_vm_start();
3896
3897 // Final system initialization including security manager and system class loader
3898 call_initPhase3(CHECK_JNI_ERR);
3899
3900 // cache the system and platform class loaders
3901 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3902
3903 #if INCLUDE_CDS
3904 if (DumpSharedSpaces) {
3905 // capture the module path info from the ModuleEntryTable
3906 ClassLoader::initialize_module_path(THREAD);
3907 }
3908 #endif
3909
3910 #if INCLUDE_JVMCI
3911 if (force_JVMCI_intialization) {
3912 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3913 CompileBroker::compilation_init_phase2();
3914 }
3915 #endif
3916
3917 // Always call even when there are not JVMTI environments yet, since environments
3918 // may be attached late and JVMTI must track phases of VM execution
3919 JvmtiExport::enter_live_phase();
3920
3921 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3922 JvmtiExport::post_vm_initialized();
3923
3924 JFR_ONLY(Jfr::on_vm_start();)
3925
3926 #if INCLUDE_MANAGEMENT
3927 Management::initialize(THREAD);
3928
3929 if (HAS_PENDING_EXCEPTION) {
3930 // management agent fails to start possibly due to
3931 // configuration problem and is responsible for printing
3932 // stack trace if appropriate. Simply exit VM.
3933 vm_exit(1);
3934 }
3935 #endif // INCLUDE_MANAGEMENT
3936
3937 if (MemProfiling) MemProfiler::engage();
3938 StatSampler::engage();
3939 if (CheckJNICalls) JniPeriodicChecker::engage();
3940
3941 BiasedLocking::init();
3942
3943 #if INCLUDE_RTM_OPT
3944 RTMLockingCounters::init();
3945 #endif
3946
3947 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3948 call_postVMInitHook(THREAD);
3949 // The Java side of PostVMInitHook.run must deal with all
3950 // exceptions and provide means of diagnosis.
3951 if (HAS_PENDING_EXCEPTION) {
3952 CLEAR_PENDING_EXCEPTION;
3953 }
3954 }
3955
3956 {
3957 MutexLocker ml(PeriodicTask_lock);
3958 // Make sure the WatcherThread can be started by WatcherThread::start()
3959 // or by dynamic enrollment.
3960 WatcherThread::make_startable();
3961 // Start up the WatcherThread if there are any periodic tasks
3962 // NOTE: All PeriodicTasks should be registered by now. If they
3963 // aren't, late joiners might appear to start slowly (we might
3964 // take a while to process their first tick).
3965 if (PeriodicTask::num_tasks() > 0) {
3966 WatcherThread::start();
3967 }
3968 }
3969
3970 create_vm_timer.end();
3971 #ifdef ASSERT
3972 _vm_complete = true;
3973 #endif
3974
3975 if (DumpSharedSpaces) {
3976 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3977 ShouldNotReachHere();
3978 }
3979
3980 return JNI_OK;
3981 }
3982
3983 // type for the Agent_OnLoad and JVM_OnLoad entry points
3984 extern "C" {
3985 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3986 }
3987 // Find a command line agent library and return its entry point for
3988 // -agentlib: -agentpath: -Xrun
3989 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3990 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3991 const char *on_load_symbols[],
3992 size_t num_symbol_entries) {
3993 OnLoadEntry_t on_load_entry = NULL;
3994 void *library = NULL;
3995
3996 if (!agent->valid()) {
3997 char buffer[JVM_MAXPATHLEN];
3998 char ebuf[1024] = "";
3999 const char *name = agent->name();
4000 const char *msg = "Could not find agent library ";
4001
4002 // First check to see if agent is statically linked into executable
4003 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4004 library = agent->os_lib();
4005 } else if (agent->is_absolute_path()) {
4006 library = os::dll_load(name, ebuf, sizeof ebuf);
4007 if (library == NULL) {
4008 const char *sub_msg = " in absolute path, with error: ";
4009 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4010 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4011 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4012 // If we can't find the agent, exit.
4013 vm_exit_during_initialization(buf, NULL);
4014 FREE_C_HEAP_ARRAY(char, buf);
4015 }
4016 } else {
4017 // Try to load the agent from the standard dll directory
4018 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4019 name)) {
4020 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4021 }
4022 if (library == NULL) { // Try the library path directory.
4023 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4024 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4025 }
4026 if (library == NULL) {
4027 const char *sub_msg = " on the library path, with error: ";
4028 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4029
4030 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4031 strlen(ebuf) + strlen(sub_msg2) + 1;
4032 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4033 if (!agent->is_instrument_lib()) {
4034 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4035 } else {
4036 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4037 }
4038 // If we can't find the agent, exit.
4039 vm_exit_during_initialization(buf, NULL);
4040 FREE_C_HEAP_ARRAY(char, buf);
4041 }
4042 }
4043 }
4044 agent->set_os_lib(library);
4045 agent->set_valid();
4046 }
4047
4048 // Find the OnLoad function.
4049 on_load_entry =
4050 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4051 false,
4052 on_load_symbols,
4053 num_symbol_entries));
4054 return on_load_entry;
4055 }
4056
4057 // Find the JVM_OnLoad entry point
4058 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4059 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4060 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4061 }
4062
4063 // Find the Agent_OnLoad entry point
4064 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4065 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4066 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4067 }
4068
4069 // For backwards compatibility with -Xrun
4070 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4071 // treated like -agentpath:
4072 // Must be called before agent libraries are created
4073 void Threads::convert_vm_init_libraries_to_agents() {
4074 AgentLibrary* agent;
4075 AgentLibrary* next;
4076
4077 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4078 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4079 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4080
4081 // If there is an JVM_OnLoad function it will get called later,
4082 // otherwise see if there is an Agent_OnLoad
4083 if (on_load_entry == NULL) {
4084 on_load_entry = lookup_agent_on_load(agent);
4085 if (on_load_entry != NULL) {
4086 // switch it to the agent list -- so that Agent_OnLoad will be called,
4087 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4088 Arguments::convert_library_to_agent(agent);
4089 } else {
4090 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4091 }
4092 }
4093 }
4094 }
4095
4096 // Create agents for -agentlib: -agentpath: and converted -Xrun
4097 // Invokes Agent_OnLoad
4098 // Called very early -- before JavaThreads exist
4099 void Threads::create_vm_init_agents() {
4100 extern struct JavaVM_ main_vm;
4101 AgentLibrary* agent;
4102
4103 JvmtiExport::enter_onload_phase();
4104
4105 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4106 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4107
4108 if (on_load_entry != NULL) {
4109 // Invoke the Agent_OnLoad function
4110 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4111 if (err != JNI_OK) {
4112 vm_exit_during_initialization("agent library failed to init", agent->name());
4113 }
4114 } else {
4115 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4116 }
4117 }
4118 JvmtiExport::enter_primordial_phase();
4119 }
4120
4121 extern "C" {
4122 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4123 }
4124
4125 void Threads::shutdown_vm_agents() {
4126 // Send any Agent_OnUnload notifications
4127 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4128 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4129 extern struct JavaVM_ main_vm;
4130 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4131
4132 // Find the Agent_OnUnload function.
4133 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4134 os::find_agent_function(agent,
4135 false,
4136 on_unload_symbols,
4137 num_symbol_entries));
4138
4139 // Invoke the Agent_OnUnload function
4140 if (unload_entry != NULL) {
4141 JavaThread* thread = JavaThread::current();
4142 ThreadToNativeFromVM ttn(thread);
4143 HandleMark hm(thread);
4144 (*unload_entry)(&main_vm);
4145 }
4146 }
4147 }
4148
4149 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4150 // Invokes JVM_OnLoad
4151 void Threads::create_vm_init_libraries() {
4152 extern struct JavaVM_ main_vm;
4153 AgentLibrary* agent;
4154
4155 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4156 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4157
4158 if (on_load_entry != NULL) {
4159 // Invoke the JVM_OnLoad function
4160 JavaThread* thread = JavaThread::current();
4161 ThreadToNativeFromVM ttn(thread);
4162 HandleMark hm(thread);
4163 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4164 if (err != JNI_OK) {
4165 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4166 }
4167 } else {
4168 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4169 }
4170 }
4171 }
4172
4173
4174 // Last thread running calls java.lang.Shutdown.shutdown()
4175 void JavaThread::invoke_shutdown_hooks() {
4176 HandleMark hm(this);
4177
4178 // We could get here with a pending exception, if so clear it now.
4179 if (this->has_pending_exception()) {
4180 this->clear_pending_exception();
4181 }
4182
4183 EXCEPTION_MARK;
4184 Klass* shutdown_klass =
4185 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4186 THREAD);
4187 if (shutdown_klass != NULL) {
4188 // SystemDictionary::resolve_or_null will return null if there was
4189 // an exception. If we cannot load the Shutdown class, just don't
4190 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4191 // won't be run. Note that if a shutdown hook was registered,
4192 // the Shutdown class would have already been loaded
4193 // (Runtime.addShutdownHook will load it).
4194 JavaValue result(T_VOID);
4195 JavaCalls::call_static(&result,
4196 shutdown_klass,
4197 vmSymbols::shutdown_method_name(),
4198 vmSymbols::void_method_signature(),
4199 THREAD);
4200 }
4201 CLEAR_PENDING_EXCEPTION;
4202 }
4203
4204 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4205 // the program falls off the end of main(). Another VM exit path is through
4206 // vm_exit() when the program calls System.exit() to return a value or when
4207 // there is a serious error in VM. The two shutdown paths are not exactly
4208 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4209 // and VM_Exit op at VM level.
4210 //
4211 // Shutdown sequence:
4212 // + Shutdown native memory tracking if it is on
4213 // + Wait until we are the last non-daemon thread to execute
4214 // <-- every thing is still working at this moment -->
4215 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4216 // shutdown hooks
4217 // + Call before_exit(), prepare for VM exit
4218 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4219 // currently the only user of this mechanism is File.deleteOnExit())
4220 // > stop StatSampler, watcher thread, CMS threads,
4221 // post thread end and vm death events to JVMTI,
4222 // stop signal thread
4223 // + Call JavaThread::exit(), it will:
4224 // > release JNI handle blocks, remove stack guard pages
4225 // > remove this thread from Threads list
4226 // <-- no more Java code from this thread after this point -->
4227 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4228 // the compiler threads at safepoint
4229 // <-- do not use anything that could get blocked by Safepoint -->
4230 // + Disable tracing at JNI/JVM barriers
4231 // + Set _vm_exited flag for threads that are still running native code
4232 // + Call exit_globals()
4233 // > deletes tty
4234 // > deletes PerfMemory resources
4235 // + Delete this thread
4236 // + Return to caller
4237
4238 bool Threads::destroy_vm() {
4239 JavaThread* thread = JavaThread::current();
4240
4241 #ifdef ASSERT
4242 _vm_complete = false;
4243 #endif
4244 // Wait until we are the last non-daemon thread to execute
4245 { MutexLocker nu(Threads_lock);
4246 while (Threads::number_of_non_daemon_threads() > 1)
4247 // This wait should make safepoint checks, wait without a timeout,
4248 // and wait as a suspend-equivalent condition.
4249 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4250 Mutex::_as_suspend_equivalent_flag);
4251 }
4252
4253 EventShutdown e;
4254 if (e.should_commit()) {
4255 e.set_reason("No remaining non-daemon Java threads");
4256 e.commit();
4257 }
4258
4259 // Hang forever on exit if we are reporting an error.
4260 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4261 os::infinite_sleep();
4262 }
4263 os::wait_for_keypress_at_exit();
4264
4265 // run Java level shutdown hooks
4266 thread->invoke_shutdown_hooks();
4267
4268 before_exit(thread);
4269
4270 thread->exit(true);
4271
4272 // Stop VM thread.
4273 {
4274 // 4945125 The vm thread comes to a safepoint during exit.
4275 // GC vm_operations can get caught at the safepoint, and the
4276 // heap is unparseable if they are caught. Grab the Heap_lock
4277 // to prevent this. The GC vm_operations will not be able to
4278 // queue until after the vm thread is dead. After this point,
4279 // we'll never emerge out of the safepoint before the VM exits.
4280
4281 MutexLocker ml(Heap_lock);
4282
4283 VMThread::wait_for_vm_thread_exit();
4284 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4285 VMThread::destroy();
4286 }
4287
4288 // Now, all Java threads are gone except daemon threads. Daemon threads
4289 // running Java code or in VM are stopped by the Safepoint. However,
4290 // daemon threads executing native code are still running. But they
4291 // will be stopped at native=>Java/VM barriers. Note that we can't
4292 // simply kill or suspend them, as it is inherently deadlock-prone.
4293
4294 VM_Exit::set_vm_exited();
4295
4296 // Clean up ideal graph printers after the VMThread has started
4297 // the final safepoint which will block all the Compiler threads.
4298 // Note that this Thread has already logically exited so the
4299 // clean_up() function's use of a JavaThreadIteratorWithHandle
4300 // would be a problem except set_vm_exited() has remembered the
4301 // shutdown thread which is granted a policy exception.
4302 #if defined(COMPILER2) && !defined(PRODUCT)
4303 IdealGraphPrinter::clean_up();
4304 #endif
4305
4306 notify_vm_shutdown();
4307
4308 // exit_globals() will delete tty
4309 exit_globals();
4310
4311 // We are after VM_Exit::set_vm_exited() so we can't call
4312 // thread->smr_delete() or we will block on the Threads_lock.
4313 // Deleting the shutdown thread here is safe because another
4314 // JavaThread cannot have an active ThreadsListHandle for
4315 // this JavaThread.
4316 delete thread;
4317
4318 #if INCLUDE_JVMCI
4319 if (JVMCICounterSize > 0) {
4320 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4321 }
4322 #endif
4323
4324 LogConfiguration::finalize();
4325
4326 return true;
4327 }
4328
4329
4330 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4331 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4332 return is_supported_jni_version(version);
4333 }
4334
4335
4336 jboolean Threads::is_supported_jni_version(jint version) {
4337 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4338 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4339 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4340 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4341 if (version == JNI_VERSION_9) return JNI_TRUE;
4342 if (version == JNI_VERSION_10) return JNI_TRUE;
4343 return JNI_FALSE;
4344 }
4345
4346
4347 void Threads::add(JavaThread* p, bool force_daemon) {
4348 // The threads lock must be owned at this point
4349 assert(Threads_lock->owned_by_self(), "must have threads lock");
4350
4351 BarrierSet::barrier_set()->on_thread_attach(p);
4352
4353 p->set_next(_thread_list);
4354 _thread_list = p;
4355
4356 // Once a JavaThread is added to the Threads list, smr_delete() has
4357 // to be used to delete it. Otherwise we can just delete it directly.
4358 p->set_on_thread_list();
4359
4360 _number_of_threads++;
4361 oop threadObj = p->threadObj();
4362 bool daemon = true;
4363 // Bootstrapping problem: threadObj can be null for initial
4364 // JavaThread (or for threads attached via JNI)
4365 if ((!force_daemon) && !is_daemon((threadObj))) {
4366 _number_of_non_daemon_threads++;
4367 daemon = false;
4368 }
4369
4370 ThreadService::add_thread(p, daemon);
4371
4372 // Maintain fast thread list
4373 ThreadsSMRSupport::add_thread(p);
4374
4375 // Possible GC point.
4376 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4377 }
4378
4379 void Threads::remove(JavaThread* p) {
4380
4381 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4382 ObjectSynchronizer::omFlush(p);
4383
4384 // Extra scope needed for Thread_lock, so we can check
4385 // that we do not remove thread without safepoint code notice
4386 { MutexLocker ml(Threads_lock);
4387
4388 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4389
4390 // Maintain fast thread list
4391 ThreadsSMRSupport::remove_thread(p);
4392
4393 JavaThread* current = _thread_list;
4394 JavaThread* prev = NULL;
4395
4396 while (current != p) {
4397 prev = current;
4398 current = current->next();
4399 }
4400
4401 if (prev) {
4402 prev->set_next(current->next());
4403 } else {
4404 _thread_list = p->next();
4405 }
4406
4407 _number_of_threads--;
4408 oop threadObj = p->threadObj();
4409 bool daemon = true;
4410 if (!is_daemon(threadObj)) {
4411 _number_of_non_daemon_threads--;
4412 daemon = false;
4413
4414 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4415 // on destroy_vm will wake up.
4416 if (number_of_non_daemon_threads() == 1) {
4417 Threads_lock->notify_all();
4418 }
4419 }
4420 ThreadService::remove_thread(p, daemon);
4421
4422 // Make sure that safepoint code disregard this thread. This is needed since
4423 // the thread might mess around with locks after this point. This can cause it
4424 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4425 // of this thread since it is removed from the queue.
4426 p->set_terminated_value();
4427 } // unlock Threads_lock
4428
4429 // Since Events::log uses a lock, we grab it outside the Threads_lock
4430 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4431 }
4432
4433 // Operations on the Threads list for GC. These are not explicitly locked,
4434 // but the garbage collector must provide a safe context for them to run.
4435 // In particular, these things should never be called when the Threads_lock
4436 // is held by some other thread. (Note: the Safepoint abstraction also
4437 // uses the Threads_lock to guarantee this property. It also makes sure that
4438 // all threads gets blocked when exiting or starting).
4439
4440 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4441 ALL_JAVA_THREADS(p) {
4442 p->oops_do(f, cf);
4443 }
4444 VMThread::vm_thread()->oops_do(f, cf);
4445 }
4446
4447 void Threads::change_thread_claim_parity() {
4448 // Set the new claim parity.
4449 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4450 "Not in range.");
4451 _thread_claim_parity++;
4452 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4453 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4454 "Not in range.");
4455 }
4456
4457 #ifdef ASSERT
4458 void Threads::assert_all_threads_claimed() {
4459 ALL_JAVA_THREADS(p) {
4460 const int thread_parity = p->oops_do_parity();
4461 assert((thread_parity == _thread_claim_parity),
4462 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4463 }
4464 VMThread* vmt = VMThread::vm_thread();
4465 const int thread_parity = vmt->oops_do_parity();
4466 assert((thread_parity == _thread_claim_parity),
4467 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4468 }
4469 #endif // ASSERT
4470
4471 class ParallelOopsDoThreadClosure : public ThreadClosure {
4472 private:
4473 OopClosure* _f;
4474 CodeBlobClosure* _cf;
4475 public:
4476 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4477 void do_thread(Thread* t) {
4478 t->oops_do(_f, _cf);
4479 }
4480 };
4481
4482 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4483 ParallelOopsDoThreadClosure tc(f, cf);
4484 possibly_parallel_threads_do(is_par, &tc);
4485 }
4486
4487 void Threads::nmethods_do(CodeBlobClosure* cf) {
4488 ALL_JAVA_THREADS(p) {
4489 // This is used by the code cache sweeper to mark nmethods that are active
4490 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4491 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4492 if(!p->is_Code_cache_sweeper_thread()) {
4493 p->nmethods_do(cf);
4494 }
4495 }
4496 }
4497
4498 void Threads::metadata_do(void f(Metadata*)) {
4499 ALL_JAVA_THREADS(p) {
4500 p->metadata_do(f);
4501 }
4502 }
4503
4504 class ThreadHandlesClosure : public ThreadClosure {
4505 void (*_f)(Metadata*);
4506 public:
4507 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4508 virtual void do_thread(Thread* thread) {
4509 thread->metadata_handles_do(_f);
4510 }
4511 };
4512
4513 void Threads::metadata_handles_do(void f(Metadata*)) {
4514 // Only walk the Handles in Thread.
4515 ThreadHandlesClosure handles_closure(f);
4516 threads_do(&handles_closure);
4517 }
4518
4519 void Threads::deoptimized_wrt_marked_nmethods() {
4520 ALL_JAVA_THREADS(p) {
4521 p->deoptimized_wrt_marked_nmethods();
4522 }
4523 }
4524
4525
4526 // Get count Java threads that are waiting to enter the specified monitor.
4527 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4528 int count,
4529 address monitor) {
4530 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4531
4532 int i = 0;
4533 DO_JAVA_THREADS(t_list, p) {
4534 if (!p->can_call_java()) continue;
4535
4536 address pending = (address)p->current_pending_monitor();
4537 if (pending == monitor) { // found a match
4538 if (i < count) result->append(p); // save the first count matches
4539 i++;
4540 }
4541 }
4542
4543 return result;
4544 }
4545
4546
4547 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4548 address owner) {
4549 // NULL owner means not locked so we can skip the search
4550 if (owner == NULL) return NULL;
4551
4552 DO_JAVA_THREADS(t_list, p) {
4553 // first, see if owner is the address of a Java thread
4554 if (owner == (address)p) return p;
4555 }
4556
4557 // Cannot assert on lack of success here since this function may be
4558 // used by code that is trying to report useful problem information
4559 // like deadlock detection.
4560 if (UseHeavyMonitors) return NULL;
4561
4562 // If we didn't find a matching Java thread and we didn't force use of
4563 // heavyweight monitors, then the owner is the stack address of the
4564 // Lock Word in the owning Java thread's stack.
4565 //
4566 JavaThread* the_owner = NULL;
4567 DO_JAVA_THREADS(t_list, q) {
4568 if (q->is_lock_owned(owner)) {
4569 the_owner = q;
4570 break;
4571 }
4572 }
4573
4574 // cannot assert on lack of success here; see above comment
4575 return the_owner;
4576 }
4577
4578 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4579 void Threads::print_on(outputStream* st, bool print_stacks,
4580 bool internal_format, bool print_concurrent_locks,
4581 bool print_extended_info) {
4582 char buf[32];
4583 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4584
4585 st->print_cr("Full thread dump %s (%s %s):",
4586 VM_Version::vm_name(),
4587 VM_Version::vm_release(),
4588 VM_Version::vm_info_string());
4589 st->cr();
4590
4591 #if INCLUDE_SERVICES
4592 // Dump concurrent locks
4593 ConcurrentLocksDump concurrent_locks;
4594 if (print_concurrent_locks) {
4595 concurrent_locks.dump_at_safepoint();
4596 }
4597 #endif // INCLUDE_SERVICES
4598
4599 ThreadsSMRSupport::print_info_on(st);
4600 st->cr();
4601
4602 ALL_JAVA_THREADS(p) {
4603 ResourceMark rm;
4604 p->print_on(st, print_extended_info);
4605 if (print_stacks) {
4606 if (internal_format) {
4607 p->trace_stack();
4608 } else {
4609 p->print_stack_on(st);
4610 }
4611 }
4612 st->cr();
4613 #if INCLUDE_SERVICES
4614 if (print_concurrent_locks) {
4615 concurrent_locks.print_locks_on(p, st);
4616 }
4617 #endif // INCLUDE_SERVICES
4618 }
4619
4620 VMThread::vm_thread()->print_on(st);
4621 st->cr();
4622 Universe::heap()->print_gc_threads_on(st);
4623 WatcherThread* wt = WatcherThread::watcher_thread();
4624 if (wt != NULL) {
4625 wt->print_on(st);
4626 st->cr();
4627 }
4628
4629 st->flush();
4630 }
4631
4632 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4633 int buflen, bool* found_current) {
4634 if (this_thread != NULL) {
4635 bool is_current = (current == this_thread);
4636 *found_current = *found_current || is_current;
4637 st->print("%s", is_current ? "=>" : " ");
4638
4639 st->print(PTR_FORMAT, p2i(this_thread));
4640 st->print(" ");
4641 this_thread->print_on_error(st, buf, buflen);
4642 st->cr();
4643 }
4644 }
4645
4646 class PrintOnErrorClosure : public ThreadClosure {
4647 outputStream* _st;
4648 Thread* _current;
4649 char* _buf;
4650 int _buflen;
4651 bool* _found_current;
4652 public:
4653 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4654 int buflen, bool* found_current) :
4655 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4656
4657 virtual void do_thread(Thread* thread) {
4658 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4659 }
4660 };
4661
4662 // Threads::print_on_error() is called by fatal error handler. It's possible
4663 // that VM is not at safepoint and/or current thread is inside signal handler.
4664 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4665 // memory (even in resource area), it might deadlock the error handler.
4666 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4667 int buflen) {
4668 ThreadsSMRSupport::print_info_on(st);
4669 st->cr();
4670
4671 bool found_current = false;
4672 st->print_cr("Java Threads: ( => current thread )");
4673 ALL_JAVA_THREADS(thread) {
4674 print_on_error(thread, st, current, buf, buflen, &found_current);
4675 }
4676 st->cr();
4677
4678 st->print_cr("Other Threads:");
4679 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4680 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4681
4682 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4683 Universe::heap()->gc_threads_do(&print_closure);
4684
4685 if (!found_current) {
4686 st->cr();
4687 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4688 current->print_on_error(st, buf, buflen);
4689 st->cr();
4690 }
4691 st->cr();
4692
4693 st->print_cr("Threads with active compile tasks:");
4694 print_threads_compiling(st, buf, buflen);
4695 }
4696
4697 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4698 ALL_JAVA_THREADS(thread) {
4699 if (thread->is_Compiler_thread()) {
4700 CompilerThread* ct = (CompilerThread*) thread;
4701
4702 // Keep task in local variable for NULL check.
4703 // ct->_task might be set to NULL by concurring compiler thread
4704 // because it completed the compilation. The task is never freed,
4705 // though, just returned to a free list.
4706 CompileTask* task = ct->task();
4707 if (task != NULL) {
4708 thread->print_name_on_error(st, buf, buflen);
4709 task->print(st, NULL, true, true);
4710 }
4711 }
4712 }
4713 }
4714
4715
4716 // Internal SpinLock and Mutex
4717 // Based on ParkEvent
4718
4719 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4720 //
4721 // We employ SpinLocks _only for low-contention, fixed-length
4722 // short-duration critical sections where we're concerned
4723 // about native mutex_t or HotSpot Mutex:: latency.
4724 // The mux construct provides a spin-then-block mutual exclusion
4725 // mechanism.
4726 //
4727 // Testing has shown that contention on the ListLock guarding gFreeList
4728 // is common. If we implement ListLock as a simple SpinLock it's common
4729 // for the JVM to devolve to yielding with little progress. This is true
4730 // despite the fact that the critical sections protected by ListLock are
4731 // extremely short.
4732 //
4733 // TODO-FIXME: ListLock should be of type SpinLock.
4734 // We should make this a 1st-class type, integrated into the lock
4735 // hierarchy as leaf-locks. Critically, the SpinLock structure
4736 // should have sufficient padding to avoid false-sharing and excessive
4737 // cache-coherency traffic.
4738
4739
4740 typedef volatile int SpinLockT;
4741
4742 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4743 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4744 return; // normal fast-path return
4745 }
4746
4747 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4748 int ctr = 0;
4749 int Yields = 0;
4750 for (;;) {
4751 while (*adr != 0) {
4752 ++ctr;
4753 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4754 if (Yields > 5) {
4755 os::naked_short_sleep(1);
4756 } else {
4757 os::naked_yield();
4758 ++Yields;
4759 }
4760 } else {
4761 SpinPause();
4762 }
4763 }
4764 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4765 }
4766 }
4767
4768 void Thread::SpinRelease(volatile int * adr) {
4769 assert(*adr != 0, "invariant");
4770 OrderAccess::fence(); // guarantee at least release consistency.
4771 // Roach-motel semantics.
4772 // It's safe if subsequent LDs and STs float "up" into the critical section,
4773 // but prior LDs and STs within the critical section can't be allowed
4774 // to reorder or float past the ST that releases the lock.
4775 // Loads and stores in the critical section - which appear in program
4776 // order before the store that releases the lock - must also appear
4777 // before the store that releases the lock in memory visibility order.
4778 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4779 // the ST of 0 into the lock-word which releases the lock, so fence
4780 // more than covers this on all platforms.
4781 *adr = 0;
4782 }
4783
4784 // muxAcquire and muxRelease:
4785 //
4786 // * muxAcquire and muxRelease support a single-word lock-word construct.
4787 // The LSB of the word is set IFF the lock is held.
4788 // The remainder of the word points to the head of a singly-linked list
4789 // of threads blocked on the lock.
4790 //
4791 // * The current implementation of muxAcquire-muxRelease uses its own
4792 // dedicated Thread._MuxEvent instance. If we're interested in
4793 // minimizing the peak number of extant ParkEvent instances then
4794 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4795 // as certain invariants were satisfied. Specifically, care would need
4796 // to be taken with regards to consuming unpark() "permits".
4797 // A safe rule of thumb is that a thread would never call muxAcquire()
4798 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4799 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4800 // consume an unpark() permit intended for monitorenter, for instance.
4801 // One way around this would be to widen the restricted-range semaphore
4802 // implemented in park(). Another alternative would be to provide
4803 // multiple instances of the PlatformEvent() for each thread. One
4804 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4805 //
4806 // * Usage:
4807 // -- Only as leaf locks
4808 // -- for short-term locking only as muxAcquire does not perform
4809 // thread state transitions.
4810 //
4811 // Alternatives:
4812 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4813 // but with parking or spin-then-park instead of pure spinning.
4814 // * Use Taura-Oyama-Yonenzawa locks.
4815 // * It's possible to construct a 1-0 lock if we encode the lockword as
4816 // (List,LockByte). Acquire will CAS the full lockword while Release
4817 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4818 // acquiring threads use timers (ParkTimed) to detect and recover from
4819 // the stranding window. Thread/Node structures must be aligned on 256-byte
4820 // boundaries by using placement-new.
4821 // * Augment MCS with advisory back-link fields maintained with CAS().
4822 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4823 // The validity of the backlinks must be ratified before we trust the value.
4824 // If the backlinks are invalid the exiting thread must back-track through the
4825 // the forward links, which are always trustworthy.
4826 // * Add a successor indication. The LockWord is currently encoded as
4827 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4828 // to provide the usual futile-wakeup optimization.
4829 // See RTStt for details.
4830 //
4831
4832
4833 const intptr_t LOCKBIT = 1;
4834
4835 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4836 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4837 if (w == 0) return;
4838 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4839 return;
4840 }
4841
4842 ParkEvent * const Self = Thread::current()->_MuxEvent;
4843 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4844 for (;;) {
4845 int its = (os::is_MP() ? 100 : 0) + 1;
4846
4847 // Optional spin phase: spin-then-park strategy
4848 while (--its >= 0) {
4849 w = *Lock;
4850 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4851 return;
4852 }
4853 }
4854
4855 Self->reset();
4856 Self->OnList = intptr_t(Lock);
4857 // The following fence() isn't _strictly necessary as the subsequent
4858 // CAS() both serializes execution and ratifies the fetched *Lock value.
4859 OrderAccess::fence();
4860 for (;;) {
4861 w = *Lock;
4862 if ((w & LOCKBIT) == 0) {
4863 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4864 Self->OnList = 0; // hygiene - allows stronger asserts
4865 return;
4866 }
4867 continue; // Interference -- *Lock changed -- Just retry
4868 }
4869 assert(w & LOCKBIT, "invariant");
4870 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4871 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4872 }
4873
4874 while (Self->OnList != 0) {
4875 Self->park();
4876 }
4877 }
4878 }
4879
4880 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4881 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4882 if (w == 0) return;
4883 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4884 return;
4885 }
4886
4887 ParkEvent * ReleaseAfter = NULL;
4888 if (ev == NULL) {
4889 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4890 }
4891 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4892 for (;;) {
4893 guarantee(ev->OnList == 0, "invariant");
4894 int its = (os::is_MP() ? 100 : 0) + 1;
4895
4896 // Optional spin phase: spin-then-park strategy
4897 while (--its >= 0) {
4898 w = *Lock;
4899 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4900 if (ReleaseAfter != NULL) {
4901 ParkEvent::Release(ReleaseAfter);
4902 }
4903 return;
4904 }
4905 }
4906
4907 ev->reset();
4908 ev->OnList = intptr_t(Lock);
4909 // The following fence() isn't _strictly necessary as the subsequent
4910 // CAS() both serializes execution and ratifies the fetched *Lock value.
4911 OrderAccess::fence();
4912 for (;;) {
4913 w = *Lock;
4914 if ((w & LOCKBIT) == 0) {
4915 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4916 ev->OnList = 0;
4917 // We call ::Release while holding the outer lock, thus
4918 // artificially lengthening the critical section.
4919 // Consider deferring the ::Release() until the subsequent unlock(),
4920 // after we've dropped the outer lock.
4921 if (ReleaseAfter != NULL) {
4922 ParkEvent::Release(ReleaseAfter);
4923 }
4924 return;
4925 }
4926 continue; // Interference -- *Lock changed -- Just retry
4927 }
4928 assert(w & LOCKBIT, "invariant");
4929 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4930 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4931 }
4932
4933 while (ev->OnList != 0) {
4934 ev->park();
4935 }
4936 }
4937 }
4938
4939 // Release() must extract a successor from the list and then wake that thread.
4940 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4941 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4942 // Release() would :
4943 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4944 // (B) Extract a successor from the private list "in-hand"
4945 // (C) attempt to CAS() the residual back into *Lock over null.
4946 // If there were any newly arrived threads and the CAS() would fail.
4947 // In that case Release() would detach the RATs, re-merge the list in-hand
4948 // with the RATs and repeat as needed. Alternately, Release() might
4949 // detach and extract a successor, but then pass the residual list to the wakee.
4950 // The wakee would be responsible for reattaching and remerging before it
4951 // competed for the lock.
4952 //
4953 // Both "pop" and DMR are immune from ABA corruption -- there can be
4954 // multiple concurrent pushers, but only one popper or detacher.
4955 // This implementation pops from the head of the list. This is unfair,
4956 // but tends to provide excellent throughput as hot threads remain hot.
4957 // (We wake recently run threads first).
4958 //
4959 // All paths through muxRelease() will execute a CAS.
4960 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4961 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4962 // executed within the critical section are complete and globally visible before the
4963 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4964 void Thread::muxRelease(volatile intptr_t * Lock) {
4965 for (;;) {
4966 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4967 assert(w & LOCKBIT, "invariant");
4968 if (w == LOCKBIT) return;
4969 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4970 assert(List != NULL, "invariant");
4971 assert(List->OnList == intptr_t(Lock), "invariant");
4972 ParkEvent * const nxt = List->ListNext;
4973 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4974
4975 // The following CAS() releases the lock and pops the head element.
4976 // The CAS() also ratifies the previously fetched lock-word value.
4977 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4978 continue;
4979 }
4980 List->OnList = 0;
4981 OrderAccess::fence();
4982 List->unpark();
4983 return;
4984 }
4985 }
4986
4987
4988 void Threads::verify() {
4989 ALL_JAVA_THREADS(p) {
4990 p->verify();
4991 }
4992 VMThread* thread = VMThread::vm_thread();
4993 if (thread != NULL) thread->verify();
4994 }