1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/barrierSet.hpp"
37 #include "gc/shared/gcId.hpp"
38 #include "gc/shared/gcLocker.inline.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "jfr/support/jfrThreadId.hpp"
45 #include "jvmtifiles/jvmtiEnv.hpp"
46 #include "logging/log.hpp"
47 #include "logging/logConfiguration.hpp"
48 #include "logging/logStream.hpp"
49 #include "memory/allocation.inline.hpp"
50 #include "memory/metaspaceShared.hpp"
51 #include "memory/oopFactory.hpp"
52 #include "memory/resourceArea.hpp"
53 #include "memory/universe.hpp"
54 #include "oops/access.inline.hpp"
55 #include "oops/instanceKlass.hpp"
56 #include "oops/objArrayOop.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/symbol.hpp"
59 #include "oops/typeArrayOop.inline.hpp"
60 #include "oops/verifyOopClosure.hpp"
61 #include "prims/jvm_misc.hpp"
62 #include "prims/jvmtiExport.hpp"
63 #include "prims/jvmtiThreadState.hpp"
64 #include "prims/privilegedStack.hpp"
65 #include "runtime/arguments.hpp"
66 #include "runtime/atomic.hpp"
67 #include "runtime/biasedLocking.hpp"
68 #include "runtime/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.inline.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/sharedRuntime.hpp"
89 #include "runtime/statSampler.hpp"
90 #include "runtime/stubRoutines.hpp"
91 #include "runtime/sweeper.hpp"
92 #include "runtime/task.hpp"
93 #include "runtime/thread.inline.hpp"
94 #include "runtime/threadCritical.hpp"
95 #include "runtime/threadSMR.inline.hpp"
96 #include "runtime/timer.hpp"
97 #include "runtime/timerTrace.hpp"
98 #include "runtime/vframe.inline.hpp"
99 #include "runtime/vframeArray.hpp"
100 #include "runtime/vframe_hp.hpp"
101 #include "runtime/vmThread.hpp"
102 #include "runtime/vm_operations.hpp"
103 #include "runtime/vm_version.hpp"
104 #include "services/attachListener.hpp"
105 #include "services/management.hpp"
106 #include "services/memTracker.hpp"
107 #include "services/threadService.hpp"
108 #include "utilities/align.hpp"
109 #include "utilities/copy.hpp"
110 #include "utilities/defaultStream.hpp"
111 #include "utilities/dtrace.hpp"
112 #include "utilities/events.hpp"
113 #include "utilities/macros.hpp"
114 #include "utilities/preserveException.hpp"
115 #include "utilities/vmError.hpp"
116 #if INCLUDE_JVMCI
117 #include "jvmci/jvmciCompiler.hpp"
118 #include "jvmci/jvmciRuntime.hpp"
119 #include "logging/logHandle.hpp"
120 #endif
121 #ifdef COMPILER1
122 #include "c1/c1_Compiler.hpp"
123 #endif
124 #ifdef COMPILER2
125 #include "opto/c2compiler.hpp"
126 #include "opto/idealGraphPrinter.hpp"
127 #endif
128 #if INCLUDE_RTM_OPT
129 #include "runtime/rtmLocking.hpp"
130 #endif
131 #if INCLUDE_JFR
132 #include "jfr/jfr.hpp"
133 #endif
134
135 // Initialization after module runtime initialization
136 void universe_post_module_init(); // must happen after call_initPhase2
137
138 #ifdef DTRACE_ENABLED
139
140 // Only bother with this argument setup if dtrace is available
141
142 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
143 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
144
145 #define DTRACE_THREAD_PROBE(probe, javathread) \
146 { \
147 ResourceMark rm(this); \
148 int len = 0; \
149 const char* name = (javathread)->get_thread_name(); \
150 len = strlen(name); \
151 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
152 (char *) name, len, \
153 java_lang_Thread::thread_id((javathread)->threadObj()), \
154 (uintptr_t) (javathread)->osthread()->thread_id(), \
155 java_lang_Thread::is_daemon((javathread)->threadObj())); \
156 }
157
158 #else // ndef DTRACE_ENABLED
159
160 #define DTRACE_THREAD_PROBE(probe, javathread)
161
162 #endif // ndef DTRACE_ENABLED
163
164 #ifndef USE_LIBRARY_BASED_TLS_ONLY
165 // Current thread is maintained as a thread-local variable
166 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
167 #endif
168 // Class hierarchy
169 // - Thread
170 // - VMThread
171 // - WatcherThread
172 // - ConcurrentMarkSweepThread
173 // - JavaThread
174 // - CompilerThread
175
176 // ======= Thread ========
177 // Support for forcing alignment of thread objects for biased locking
178 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
179 if (UseBiasedLocking) {
180 const int alignment = markOopDesc::biased_lock_alignment;
181 size_t aligned_size = size + (alignment - sizeof(intptr_t));
182 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
183 : AllocateHeap(aligned_size, flags, CURRENT_PC,
184 AllocFailStrategy::RETURN_NULL);
185 void* aligned_addr = align_up(real_malloc_addr, alignment);
186 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
187 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
188 "JavaThread alignment code overflowed allocated storage");
189 if (aligned_addr != real_malloc_addr) {
190 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
191 p2i(real_malloc_addr),
192 p2i(aligned_addr));
193 }
194 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
195 return aligned_addr;
196 } else {
197 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
198 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
199 }
200 }
201
202 void Thread::operator delete(void* p) {
203 if (UseBiasedLocking) {
204 FreeHeap(((Thread*) p)->_real_malloc_address);
205 } else {
206 FreeHeap(p);
207 }
208 }
209
210 void JavaThread::smr_delete() {
211 if (_on_thread_list) {
212 ThreadsSMRSupport::smr_delete(this);
213 } else {
214 delete this;
215 }
216 }
217
218 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
219 // JavaThread
220
221
222 Thread::Thread() {
223 // stack and get_thread
224 set_stack_base(NULL);
225 set_stack_size(0);
226 set_self_raw_id(0);
227 set_lgrp_id(-1);
228 DEBUG_ONLY(clear_suspendible_thread();)
229
230 // allocated data structures
231 set_osthread(NULL);
232 set_resource_area(new (mtThread)ResourceArea());
233 DEBUG_ONLY(_current_resource_mark = NULL;)
234 set_handle_area(new (mtThread) HandleArea(NULL));
235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
236 set_active_handles(NULL);
237 set_free_handle_block(NULL);
238 set_last_handle_mark(NULL);
239
240 _statistic_info.setStartTime(os::javaTimeMillis());
241 _statistic_info.setDefineClassCount(0);
242
243 // This initial value ==> never claimed.
244 _oops_do_parity = 0;
245 _threads_hazard_ptr = NULL;
246 _threads_list_ptr = NULL;
247 _nested_threads_hazard_ptr_cnt = 0;
248 _rcu_counter = 0;
249
250 // the handle mark links itself to last_handle_mark
251 new HandleMark(this);
252
253 // plain initialization
254 debug_only(_owned_locks = NULL;)
255 debug_only(_allow_allocation_count = 0;)
256 NOT_PRODUCT(_allow_safepoint_count = 0;)
257 NOT_PRODUCT(_skip_gcalot = false;)
258 _jvmti_env_iteration_count = 0;
259 set_allocated_bytes(0);
260 _vm_operation_started_count = 0;
261 _vm_operation_completed_count = 0;
262 _current_pending_monitor = NULL;
263 _current_pending_monitor_is_from_java = true;
264 _current_waiting_monitor = NULL;
265 _num_nested_signal = 0;
266 omFreeList = NULL;
267 omFreeCount = 0;
268 omFreeProvision = 32;
269 omInUseList = NULL;
270 omInUseCount = 0;
271
272 #ifdef ASSERT
273 _visited_for_critical_count = false;
274 #endif
275
276 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
277 Monitor::_safepoint_check_sometimes);
278 _suspend_flags = 0;
279
280 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
281 _hashStateX = os::random();
282 _hashStateY = 842502087;
283 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
284 _hashStateW = 273326509;
285
286 _OnTrap = 0;
287 _schedctl = NULL;
288 _Stalled = 0;
289 _TypeTag = 0x2BAD;
290
291 // Many of the following fields are effectively final - immutable
292 // Note that nascent threads can't use the Native Monitor-Mutex
293 // construct until the _MutexEvent is initialized ...
294 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
295 // we might instead use a stack of ParkEvents that we could provision on-demand.
296 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
297 // and ::Release()
298 _ParkEvent = ParkEvent::Allocate(this);
299 _SleepEvent = ParkEvent::Allocate(this);
300 _MutexEvent = ParkEvent::Allocate(this);
301 _MuxEvent = ParkEvent::Allocate(this);
302
303 #ifdef CHECK_UNHANDLED_OOPS
304 if (CheckUnhandledOops) {
305 _unhandled_oops = new UnhandledOops(this);
306 }
307 #endif // CHECK_UNHANDLED_OOPS
308 #ifdef ASSERT
309 if (UseBiasedLocking) {
310 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
311 assert(this == _real_malloc_address ||
312 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
313 "bug in forced alignment of thread objects");
314 }
315 #endif // ASSERT
316
317 // Notify the barrier set that a thread is being created. Note that the
318 // main thread is created before a barrier set is available. The call to
319 // BarrierSet::on_thread_create() for the main thread is therefore deferred
320 // until it calls BarrierSet::set_barrier_set().
321 BarrierSet* const barrier_set = BarrierSet::barrier_set();
322 if (barrier_set != NULL) {
323 barrier_set->on_thread_create(this);
324 }
325 }
326
327 void Thread::initialize_thread_current() {
328 #ifndef USE_LIBRARY_BASED_TLS_ONLY
329 assert(_thr_current == NULL, "Thread::current already initialized");
330 _thr_current = this;
331 #endif
332 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
333 ThreadLocalStorage::set_thread(this);
334 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
335 }
336
337 void Thread::clear_thread_current() {
338 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
339 #ifndef USE_LIBRARY_BASED_TLS_ONLY
340 _thr_current = NULL;
341 #endif
342 ThreadLocalStorage::set_thread(NULL);
343 }
344
345 void Thread::record_stack_base_and_size() {
346 set_stack_base(os::current_stack_base());
347 set_stack_size(os::current_stack_size());
348 // CR 7190089: on Solaris, primordial thread's stack is adjusted
349 // in initialize_thread(). Without the adjustment, stack size is
350 // incorrect if stack is set to unlimited (ulimit -s unlimited).
351 // So far, only Solaris has real implementation of initialize_thread().
352 //
353 // set up any platform-specific state.
354 os::initialize_thread(this);
355
356 // Set stack limits after thread is initialized.
357 if (is_Java_thread()) {
358 ((JavaThread*) this)->set_stack_overflow_limit();
359 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
360 }
361 #if INCLUDE_NMT
362 // record thread's native stack, stack grows downward
363 MemTracker::record_thread_stack(stack_end(), stack_size());
364 #endif // INCLUDE_NMT
365 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
366 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
367 os::current_thread_id(), p2i(stack_base() - stack_size()),
368 p2i(stack_base()), stack_size()/1024);
369 }
370
371
372 Thread::~Thread() {
373 JFR_ONLY(Jfr::on_thread_destruct(this);)
374
375 // Notify the barrier set that a thread is being destroyed. Note that a barrier
376 // set might not be available if we encountered errors during bootstrapping.
377 BarrierSet* const barrier_set = BarrierSet::barrier_set();
378 if (barrier_set != NULL) {
379 barrier_set->on_thread_destroy(this);
380 }
381
382
383 // stack_base can be NULL if the thread is never started or exited before
384 // record_stack_base_and_size called. Although, we would like to ensure
385 // that all started threads do call record_stack_base_and_size(), there is
386 // not proper way to enforce that.
387 #if INCLUDE_NMT
388 if (_stack_base != NULL) {
389 MemTracker::release_thread_stack(stack_end(), stack_size());
390 #ifdef ASSERT
391 set_stack_base(NULL);
392 #endif
393 }
394 #endif // INCLUDE_NMT
395
396 // deallocate data structures
397 delete resource_area();
398 // since the handle marks are using the handle area, we have to deallocated the root
399 // handle mark before deallocating the thread's handle area,
400 assert(last_handle_mark() != NULL, "check we have an element");
401 delete last_handle_mark();
402 assert(last_handle_mark() == NULL, "check we have reached the end");
403
404 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
405 // We NULL out the fields for good hygiene.
406 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
407 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
408 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
409 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
410
411 delete handle_area();
412 delete metadata_handles();
413
414 // SR_handler uses this as a termination indicator -
415 // needs to happen before os::free_thread()
416 delete _SR_lock;
417 _SR_lock = NULL;
418
419 // osthread() can be NULL, if creation of thread failed.
420 if (osthread() != NULL) os::free_thread(osthread());
421
422 // clear Thread::current if thread is deleting itself.
423 // Needed to ensure JNI correctly detects non-attached threads.
424 if (this == Thread::current()) {
425 clear_thread_current();
426 }
427
428 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
429 }
430
431 // NOTE: dummy function for assertion purpose.
432 void Thread::run() {
433 ShouldNotReachHere();
434 }
435
436 #ifdef ASSERT
437 // A JavaThread is considered "dangling" if it is not the current
438 // thread, has been added the Threads list, the system is not at a
439 // safepoint and the Thread is not "protected".
440 //
441 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
442 assert(!thread->is_Java_thread() || Thread::current() == thread ||
443 !((JavaThread *) thread)->on_thread_list() ||
444 SafepointSynchronize::is_at_safepoint() ||
445 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
446 "possibility of dangling Thread pointer");
447 }
448 #endif
449
450 ThreadPriority Thread::get_priority(const Thread* const thread) {
451 ThreadPriority priority;
452 // Can return an error!
453 (void)os::get_priority(thread, priority);
454 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
455 return priority;
456 }
457
458 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
459 debug_only(check_for_dangling_thread_pointer(thread);)
460 // Can return an error!
461 (void)os::set_priority(thread, priority);
462 }
463
464
465 void Thread::start(Thread* thread) {
466 // Start is different from resume in that its safety is guaranteed by context or
467 // being called from a Java method synchronized on the Thread object.
468 if (!DisableStartThread) {
469 if (thread->is_Java_thread()) {
470 // Initialize the thread state to RUNNABLE before starting this thread.
471 // Can not set it after the thread started because we do not know the
472 // exact thread state at that time. It could be in MONITOR_WAIT or
473 // in SLEEPING or some other state.
474 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
475 java_lang_Thread::RUNNABLE);
476 }
477 os::start_thread(thread);
478 }
479 }
480
481 // Enqueue a VM_Operation to do the job for us - sometime later
482 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
483 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
484 VMThread::execute(vm_stop);
485 }
486
487
488 // Check if an external suspend request has completed (or has been
489 // cancelled). Returns true if the thread is externally suspended and
490 // false otherwise.
491 //
492 // The bits parameter returns information about the code path through
493 // the routine. Useful for debugging:
494 //
495 // set in is_ext_suspend_completed():
496 // 0x00000001 - routine was entered
497 // 0x00000010 - routine return false at end
498 // 0x00000100 - thread exited (return false)
499 // 0x00000200 - suspend request cancelled (return false)
500 // 0x00000400 - thread suspended (return true)
501 // 0x00001000 - thread is in a suspend equivalent state (return true)
502 // 0x00002000 - thread is native and walkable (return true)
503 // 0x00004000 - thread is native_trans and walkable (needed retry)
504 //
505 // set in wait_for_ext_suspend_completion():
506 // 0x00010000 - routine was entered
507 // 0x00020000 - suspend request cancelled before loop (return false)
508 // 0x00040000 - thread suspended before loop (return true)
509 // 0x00080000 - suspend request cancelled in loop (return false)
510 // 0x00100000 - thread suspended in loop (return true)
511 // 0x00200000 - suspend not completed during retry loop (return false)
512
513 // Helper class for tracing suspend wait debug bits.
514 //
515 // 0x00000100 indicates that the target thread exited before it could
516 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
517 // 0x00080000 each indicate a cancelled suspend request so they don't
518 // count as wait failures either.
519 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
520
521 class TraceSuspendDebugBits : public StackObj {
522 private:
523 JavaThread * jt;
524 bool is_wait;
525 bool called_by_wait; // meaningful when !is_wait
526 uint32_t * bits;
527
528 public:
529 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
530 uint32_t *_bits) {
531 jt = _jt;
532 is_wait = _is_wait;
533 called_by_wait = _called_by_wait;
534 bits = _bits;
535 }
536
537 ~TraceSuspendDebugBits() {
538 if (!is_wait) {
539 #if 1
540 // By default, don't trace bits for is_ext_suspend_completed() calls.
541 // That trace is very chatty.
542 return;
543 #else
544 if (!called_by_wait) {
545 // If tracing for is_ext_suspend_completed() is enabled, then only
546 // trace calls to it from wait_for_ext_suspend_completion()
547 return;
548 }
549 #endif
550 }
551
552 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
553 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
554 MutexLocker ml(Threads_lock); // needed for get_thread_name()
555 ResourceMark rm;
556
557 tty->print_cr(
558 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
559 jt->get_thread_name(), *bits);
560
561 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
562 }
563 }
564 }
565 };
566 #undef DEBUG_FALSE_BITS
567
568
569 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
570 uint32_t *bits) {
571 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
572
573 bool did_trans_retry = false; // only do thread_in_native_trans retry once
574 bool do_trans_retry; // flag to force the retry
575
576 *bits |= 0x00000001;
577
578 do {
579 do_trans_retry = false;
580
581 if (is_exiting()) {
582 // Thread is in the process of exiting. This is always checked
583 // first to reduce the risk of dereferencing a freed JavaThread.
584 *bits |= 0x00000100;
585 return false;
586 }
587
588 if (!is_external_suspend()) {
589 // Suspend request is cancelled. This is always checked before
590 // is_ext_suspended() to reduce the risk of a rogue resume
591 // confusing the thread that made the suspend request.
592 *bits |= 0x00000200;
593 return false;
594 }
595
596 if (is_ext_suspended()) {
597 // thread is suspended
598 *bits |= 0x00000400;
599 return true;
600 }
601
602 // Now that we no longer do hard suspends of threads running
603 // native code, the target thread can be changing thread state
604 // while we are in this routine:
605 //
606 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
607 //
608 // We save a copy of the thread state as observed at this moment
609 // and make our decision about suspend completeness based on the
610 // copy. This closes the race where the thread state is seen as
611 // _thread_in_native_trans in the if-thread_blocked check, but is
612 // seen as _thread_blocked in if-thread_in_native_trans check.
613 JavaThreadState save_state = thread_state();
614
615 if (save_state == _thread_blocked && is_suspend_equivalent()) {
616 // If the thread's state is _thread_blocked and this blocking
617 // condition is known to be equivalent to a suspend, then we can
618 // consider the thread to be externally suspended. This means that
619 // the code that sets _thread_blocked has been modified to do
620 // self-suspension if the blocking condition releases. We also
621 // used to check for CONDVAR_WAIT here, but that is now covered by
622 // the _thread_blocked with self-suspension check.
623 //
624 // Return true since we wouldn't be here unless there was still an
625 // external suspend request.
626 *bits |= 0x00001000;
627 return true;
628 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
629 // Threads running native code will self-suspend on native==>VM/Java
630 // transitions. If its stack is walkable (should always be the case
631 // unless this function is called before the actual java_suspend()
632 // call), then the wait is done.
633 *bits |= 0x00002000;
634 return true;
635 } else if (!called_by_wait && !did_trans_retry &&
636 save_state == _thread_in_native_trans &&
637 frame_anchor()->walkable()) {
638 // The thread is transitioning from thread_in_native to another
639 // thread state. check_safepoint_and_suspend_for_native_trans()
640 // will force the thread to self-suspend. If it hasn't gotten
641 // there yet we may have caught the thread in-between the native
642 // code check above and the self-suspend. Lucky us. If we were
643 // called by wait_for_ext_suspend_completion(), then it
644 // will be doing the retries so we don't have to.
645 //
646 // Since we use the saved thread state in the if-statement above,
647 // there is a chance that the thread has already transitioned to
648 // _thread_blocked by the time we get here. In that case, we will
649 // make a single unnecessary pass through the logic below. This
650 // doesn't hurt anything since we still do the trans retry.
651
652 *bits |= 0x00004000;
653
654 // Once the thread leaves thread_in_native_trans for another
655 // thread state, we break out of this retry loop. We shouldn't
656 // need this flag to prevent us from getting back here, but
657 // sometimes paranoia is good.
658 did_trans_retry = true;
659
660 // We wait for the thread to transition to a more usable state.
661 for (int i = 1; i <= SuspendRetryCount; i++) {
662 // We used to do an "os::yield_all(i)" call here with the intention
663 // that yielding would increase on each retry. However, the parameter
664 // is ignored on Linux which means the yield didn't scale up. Waiting
665 // on the SR_lock below provides a much more predictable scale up for
666 // the delay. It also provides a simple/direct point to check for any
667 // safepoint requests from the VMThread
668
669 // temporarily drops SR_lock while doing wait with safepoint check
670 // (if we're a JavaThread - the WatcherThread can also call this)
671 // and increase delay with each retry
672 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
673
674 // check the actual thread state instead of what we saved above
675 if (thread_state() != _thread_in_native_trans) {
676 // the thread has transitioned to another thread state so
677 // try all the checks (except this one) one more time.
678 do_trans_retry = true;
679 break;
680 }
681 } // end retry loop
682
683
684 }
685 } while (do_trans_retry);
686
687 *bits |= 0x00000010;
688 return false;
689 }
690
691 // Wait for an external suspend request to complete (or be cancelled).
692 // Returns true if the thread is externally suspended and false otherwise.
693 //
694 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
695 uint32_t *bits) {
696 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
697 false /* !called_by_wait */, bits);
698
699 // local flag copies to minimize SR_lock hold time
700 bool is_suspended;
701 bool pending;
702 uint32_t reset_bits;
703
704 // set a marker so is_ext_suspend_completed() knows we are the caller
705 *bits |= 0x00010000;
706
707 // We use reset_bits to reinitialize the bits value at the top of
708 // each retry loop. This allows the caller to make use of any
709 // unused bits for their own marking purposes.
710 reset_bits = *bits;
711
712 {
713 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
714 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
715 delay, bits);
716 pending = is_external_suspend();
717 }
718 // must release SR_lock to allow suspension to complete
719
720 if (!pending) {
721 // A cancelled suspend request is the only false return from
722 // is_ext_suspend_completed() that keeps us from entering the
723 // retry loop.
724 *bits |= 0x00020000;
725 return false;
726 }
727
728 if (is_suspended) {
729 *bits |= 0x00040000;
730 return true;
731 }
732
733 for (int i = 1; i <= retries; i++) {
734 *bits = reset_bits; // reinit to only track last retry
735
736 // We used to do an "os::yield_all(i)" call here with the intention
737 // that yielding would increase on each retry. However, the parameter
738 // is ignored on Linux which means the yield didn't scale up. Waiting
739 // on the SR_lock below provides a much more predictable scale up for
740 // the delay. It also provides a simple/direct point to check for any
741 // safepoint requests from the VMThread
742
743 {
744 MutexLocker ml(SR_lock());
745 // wait with safepoint check (if we're a JavaThread - the WatcherThread
746 // can also call this) and increase delay with each retry
747 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
748
749 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
750 delay, bits);
751
752 // It is possible for the external suspend request to be cancelled
753 // (by a resume) before the actual suspend operation is completed.
754 // Refresh our local copy to see if we still need to wait.
755 pending = is_external_suspend();
756 }
757
758 if (!pending) {
759 // A cancelled suspend request is the only false return from
760 // is_ext_suspend_completed() that keeps us from staying in the
761 // retry loop.
762 *bits |= 0x00080000;
763 return false;
764 }
765
766 if (is_suspended) {
767 *bits |= 0x00100000;
768 return true;
769 }
770 } // end retry loop
771
772 // thread did not suspend after all our retries
773 *bits |= 0x00200000;
774 return false;
775 }
776
777 // Called from API entry points which perform stack walking. If the
778 // associated JavaThread is the current thread, then wait_for_suspend
779 // is not used. Otherwise, it determines if we should wait for the
780 // "other" thread to complete external suspension. (NOTE: in future
781 // releases the suspension mechanism should be reimplemented so this
782 // is not necessary.)
783 //
784 bool
785 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
786 if (this != JavaThread::current()) {
787 // "other" threads require special handling.
788 if (wait_for_suspend) {
789 // We are allowed to wait for the external suspend to complete
790 // so give the other thread a chance to get suspended.
791 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
792 SuspendRetryDelay, bits)) {
793 // Didn't make it so let the caller know.
794 return false;
795 }
796 }
797 // We aren't allowed to wait for the external suspend to complete
798 // so if the other thread isn't externally suspended we need to
799 // let the caller know.
800 else if (!is_ext_suspend_completed_with_lock(bits)) {
801 return false;
802 }
803 }
804
805 return true;
806 }
807
808 #ifndef PRODUCT
809 void JavaThread::record_jump(address target, address instr, const char* file,
810 int line) {
811
812 // This should not need to be atomic as the only way for simultaneous
813 // updates is via interrupts. Even then this should be rare or non-existent
814 // and we don't care that much anyway.
815
816 int index = _jmp_ring_index;
817 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
818 _jmp_ring[index]._target = (intptr_t) target;
819 _jmp_ring[index]._instruction = (intptr_t) instr;
820 _jmp_ring[index]._file = file;
821 _jmp_ring[index]._line = line;
822 }
823 #endif // PRODUCT
824
825 void Thread::interrupt(Thread* thread) {
826 debug_only(check_for_dangling_thread_pointer(thread);)
827 os::interrupt(thread);
828 }
829
830 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
831 debug_only(check_for_dangling_thread_pointer(thread);)
832 // Note: If clear_interrupted==false, this simply fetches and
833 // returns the value of the field osthread()->interrupted().
834 return os::is_interrupted(thread, clear_interrupted);
835 }
836
837
838 // GC Support
839 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
840 int thread_parity = _oops_do_parity;
841 if (thread_parity != strong_roots_parity) {
842 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
843 if (res == thread_parity) {
844 return true;
845 } else {
846 guarantee(res == strong_roots_parity, "Or else what?");
847 return false;
848 }
849 }
850 return false;
851 }
852
853 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
854 active_handles()->oops_do(f);
855 // Do oop for ThreadShadow
856 f->do_oop((oop*)&_pending_exception);
857 handle_area()->oops_do(f);
858
859 if (MonitorInUseLists) {
860 // When using thread local monitor lists, we scan them here,
861 // and the remaining global monitors in ObjectSynchronizer::oops_do().
862 ObjectSynchronizer::thread_local_used_oops_do(this, f);
863 }
864 }
865
866 void Thread::metadata_handles_do(void f(Metadata*)) {
867 // Only walk the Handles in Thread.
868 if (metadata_handles() != NULL) {
869 for (int i = 0; i< metadata_handles()->length(); i++) {
870 f(metadata_handles()->at(i));
871 }
872 }
873 }
874
875 void Thread::print_on(outputStream* st) const {
876 // get_priority assumes osthread initialized
877 if (osthread() != NULL) {
878 int os_prio;
879 if (os::get_native_priority(this, &os_prio) == OS_OK) {
880 st->print("os_prio=%d ", os_prio);
881 }
882
883 if (PrintExtendedThreadInfo && os::is_thread_cpu_time_supported()) {
884 st->print("cpu=%.2fms ",
885 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
886 );
887 st->print("elapsed=%.2fs ",
888 _statistic_info.getElepsedTime() / 1000.0);
889 }
890
891 if (PrintExtendedThreadInfo && is_Java_thread()) {
892 jlong allocated_bytes = const_cast<Thread*>(this)->cooked_allocated_bytes();
893 st->print("allocated=" JLONG_FORMAT "B ", allocated_bytes);
894 st->print("defined_classes=" INT64_FORMAT " ", _statistic_info.getDefineClassCount());
895 }
896
897 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
898 osthread()->print_on(st);
899 }
900 ThreadsSMRSupport::print_info_on(this, st);
901 st->print(" ");
902 debug_only(if (WizardMode) print_owned_locks_on(st);)
903 }
904
905 // Thread::print_on_error() is called by fatal error handler. Don't use
906 // any lock or allocate memory.
907 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
908 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
909
910 if (is_VM_thread()) { st->print("VMThread"); }
911 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
912 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
913 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
914 else { st->print("Thread"); }
915
916 if (is_Named_thread()) {
917 st->print(" \"%s\"", name());
918 }
919
920 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
921 p2i(stack_end()), p2i(stack_base()));
922
923 if (osthread()) {
924 st->print(" [id=%d]", osthread()->thread_id());
925 }
926
927 ThreadsSMRSupport::print_info_on(this, st);
928 }
929
930 void Thread::print_value_on(outputStream* st) const {
931 if (is_Named_thread()) {
932 st->print(" \"%s\" ", name());
933 }
934 st->print(INTPTR_FORMAT, p2i(this)); // print address
935 }
936
937 #ifdef ASSERT
938 void Thread::print_owned_locks_on(outputStream* st) const {
939 Monitor *cur = _owned_locks;
940 if (cur == NULL) {
941 st->print(" (no locks) ");
942 } else {
943 st->print_cr(" Locks owned:");
944 while (cur) {
945 cur->print_on(st);
946 cur = cur->next();
947 }
948 }
949 }
950
951 static int ref_use_count = 0;
952
953 bool Thread::owns_locks_but_compiled_lock() const {
954 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
955 if (cur != Compile_lock) return true;
956 }
957 return false;
958 }
959
960
961 #endif
962
963 #ifndef PRODUCT
964
965 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
966 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
967 // no threads which allow_vm_block's are held
968 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
969 // Check if current thread is allowed to block at a safepoint
970 if (!(_allow_safepoint_count == 0)) {
971 fatal("Possible safepoint reached by thread that does not allow it");
972 }
973 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
974 fatal("LEAF method calling lock?");
975 }
976
977 #ifdef ASSERT
978 if (potential_vm_operation && is_Java_thread()
979 && !Universe::is_bootstrapping()) {
980 // Make sure we do not hold any locks that the VM thread also uses.
981 // This could potentially lead to deadlocks
982 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
983 // Threads_lock is special, since the safepoint synchronization will not start before this is
984 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
985 // since it is used to transfer control between JavaThreads and the VMThread
986 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
987 if ((cur->allow_vm_block() &&
988 cur != Threads_lock &&
989 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
990 cur != VMOperationRequest_lock &&
991 cur != VMOperationQueue_lock) ||
992 cur->rank() == Mutex::special) {
993 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
994 }
995 }
996 }
997
998 if (GCALotAtAllSafepoints) {
999 // We could enter a safepoint here and thus have a gc
1000 InterfaceSupport::check_gc_alot();
1001 }
1002 #endif
1003 }
1004 #endif
1005
1006 bool Thread::is_in_stack(address adr) const {
1007 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1008 address end = os::current_stack_pointer();
1009 // Allow non Java threads to call this without stack_base
1010 if (_stack_base == NULL) return true;
1011 if (stack_base() >= adr && adr >= end) return true;
1012
1013 return false;
1014 }
1015
1016 bool Thread::is_in_usable_stack(address adr) const {
1017 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1018 size_t usable_stack_size = _stack_size - stack_guard_size;
1019
1020 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1021 }
1022
1023
1024 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1025 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1026 // used for compilation in the future. If that change is made, the need for these methods
1027 // should be revisited, and they should be removed if possible.
1028
1029 bool Thread::is_lock_owned(address adr) const {
1030 return on_local_stack(adr);
1031 }
1032
1033 bool Thread::set_as_starting_thread() {
1034 // NOTE: this must be called inside the main thread.
1035 return os::create_main_thread((JavaThread*)this);
1036 }
1037
1038 static void initialize_class(Symbol* class_name, TRAPS) {
1039 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1040 InstanceKlass::cast(klass)->initialize(CHECK);
1041 }
1042
1043
1044 // Creates the initial ThreadGroup
1045 static Handle create_initial_thread_group(TRAPS) {
1046 Handle system_instance = JavaCalls::construct_new_instance(
1047 SystemDictionary::ThreadGroup_klass(),
1048 vmSymbols::void_method_signature(),
1049 CHECK_NH);
1050 Universe::set_system_thread_group(system_instance());
1051
1052 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1053 Handle main_instance = JavaCalls::construct_new_instance(
1054 SystemDictionary::ThreadGroup_klass(),
1055 vmSymbols::threadgroup_string_void_signature(),
1056 system_instance,
1057 string,
1058 CHECK_NH);
1059 return main_instance;
1060 }
1061
1062 // Creates the initial Thread
1063 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1064 TRAPS) {
1065 InstanceKlass* ik = SystemDictionary::Thread_klass();
1066 assert(ik->is_initialized(), "must be");
1067 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1068
1069 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1070 // constructor calls Thread.current(), which must be set here for the
1071 // initial thread.
1072 java_lang_Thread::set_thread(thread_oop(), thread);
1073 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1074 thread->set_threadObj(thread_oop());
1075
1076 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1077
1078 JavaValue result(T_VOID);
1079 JavaCalls::call_special(&result, thread_oop,
1080 ik,
1081 vmSymbols::object_initializer_name(),
1082 vmSymbols::threadgroup_string_void_signature(),
1083 thread_group,
1084 string,
1085 CHECK_NULL);
1086 return thread_oop();
1087 }
1088
1089 char java_runtime_name[128] = "";
1090 char java_runtime_version[128] = "";
1091
1092 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1093 static const char* get_java_runtime_name(TRAPS) {
1094 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1095 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1096 fieldDescriptor fd;
1097 bool found = k != NULL &&
1098 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1099 vmSymbols::string_signature(), &fd);
1100 if (found) {
1101 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1102 if (name_oop == NULL) {
1103 return NULL;
1104 }
1105 const char* name = java_lang_String::as_utf8_string(name_oop,
1106 java_runtime_name,
1107 sizeof(java_runtime_name));
1108 return name;
1109 } else {
1110 return NULL;
1111 }
1112 }
1113
1114 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1115 static const char* get_java_runtime_version(TRAPS) {
1116 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1117 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1118 fieldDescriptor fd;
1119 bool found = k != NULL &&
1120 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1121 vmSymbols::string_signature(), &fd);
1122 if (found) {
1123 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1124 if (name_oop == NULL) {
1125 return NULL;
1126 }
1127 const char* name = java_lang_String::as_utf8_string(name_oop,
1128 java_runtime_version,
1129 sizeof(java_runtime_version));
1130 return name;
1131 } else {
1132 return NULL;
1133 }
1134 }
1135
1136 // General purpose hook into Java code, run once when the VM is initialized.
1137 // The Java library method itself may be changed independently from the VM.
1138 static void call_postVMInitHook(TRAPS) {
1139 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1140 if (klass != NULL) {
1141 JavaValue result(T_VOID);
1142 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1143 vmSymbols::void_method_signature(),
1144 CHECK);
1145 }
1146 }
1147
1148 static void reset_vm_info_property(TRAPS) {
1149 // the vm info string
1150 ResourceMark rm(THREAD);
1151 const char *vm_info = VM_Version::vm_info_string();
1152
1153 // java.lang.System class
1154 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1155
1156 // setProperty arguments
1157 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1158 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1159
1160 // return value
1161 JavaValue r(T_OBJECT);
1162
1163 // public static String setProperty(String key, String value);
1164 JavaCalls::call_static(&r,
1165 klass,
1166 vmSymbols::setProperty_name(),
1167 vmSymbols::string_string_string_signature(),
1168 key_str,
1169 value_str,
1170 CHECK);
1171 }
1172
1173
1174 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1175 bool daemon, TRAPS) {
1176 assert(thread_group.not_null(), "thread group should be specified");
1177 assert(threadObj() == NULL, "should only create Java thread object once");
1178
1179 InstanceKlass* ik = SystemDictionary::Thread_klass();
1180 assert(ik->is_initialized(), "must be");
1181 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1182
1183 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1184 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1185 // constructor calls Thread.current(), which must be set here.
1186 java_lang_Thread::set_thread(thread_oop(), this);
1187 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1188 set_threadObj(thread_oop());
1189
1190 JavaValue result(T_VOID);
1191 if (thread_name != NULL) {
1192 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1193 // Thread gets assigned specified name and null target
1194 JavaCalls::call_special(&result,
1195 thread_oop,
1196 ik,
1197 vmSymbols::object_initializer_name(),
1198 vmSymbols::threadgroup_string_void_signature(),
1199 thread_group,
1200 name,
1201 THREAD);
1202 } else {
1203 // Thread gets assigned name "Thread-nnn" and null target
1204 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1205 JavaCalls::call_special(&result,
1206 thread_oop,
1207 ik,
1208 vmSymbols::object_initializer_name(),
1209 vmSymbols::threadgroup_runnable_void_signature(),
1210 thread_group,
1211 Handle(),
1212 THREAD);
1213 }
1214
1215
1216 if (daemon) {
1217 java_lang_Thread::set_daemon(thread_oop());
1218 }
1219
1220 if (HAS_PENDING_EXCEPTION) {
1221 return;
1222 }
1223
1224 Klass* group = SystemDictionary::ThreadGroup_klass();
1225 Handle threadObj(THREAD, this->threadObj());
1226
1227 JavaCalls::call_special(&result,
1228 thread_group,
1229 group,
1230 vmSymbols::add_method_name(),
1231 vmSymbols::thread_void_signature(),
1232 threadObj, // Arg 1
1233 THREAD);
1234 }
1235
1236 // NamedThread -- non-JavaThread subclasses with multiple
1237 // uniquely named instances should derive from this.
1238 NamedThread::NamedThread() : Thread() {
1239 _name = NULL;
1240 _processed_thread = NULL;
1241 _gc_id = GCId::undefined();
1242 }
1243
1244 NamedThread::~NamedThread() {
1245 if (_name != NULL) {
1246 FREE_C_HEAP_ARRAY(char, _name);
1247 _name = NULL;
1248 }
1249 }
1250
1251 void NamedThread::set_name(const char* format, ...) {
1252 guarantee(_name == NULL, "Only get to set name once.");
1253 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1254 guarantee(_name != NULL, "alloc failure");
1255 va_list ap;
1256 va_start(ap, format);
1257 jio_vsnprintf(_name, max_name_len, format, ap);
1258 va_end(ap);
1259 }
1260
1261 void NamedThread::initialize_named_thread() {
1262 set_native_thread_name(name());
1263 }
1264
1265 void NamedThread::print_on(outputStream* st) const {
1266 st->print("\"%s\" ", name());
1267 Thread::print_on(st);
1268 st->cr();
1269 }
1270
1271
1272 // ======= WatcherThread ========
1273
1274 // The watcher thread exists to simulate timer interrupts. It should
1275 // be replaced by an abstraction over whatever native support for
1276 // timer interrupts exists on the platform.
1277
1278 WatcherThread* WatcherThread::_watcher_thread = NULL;
1279 bool WatcherThread::_startable = false;
1280 volatile bool WatcherThread::_should_terminate = false;
1281
1282 WatcherThread::WatcherThread() : Thread() {
1283 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1284 if (os::create_thread(this, os::watcher_thread)) {
1285 _watcher_thread = this;
1286
1287 // Set the watcher thread to the highest OS priority which should not be
1288 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1289 // is created. The only normal thread using this priority is the reference
1290 // handler thread, which runs for very short intervals only.
1291 // If the VMThread's priority is not lower than the WatcherThread profiling
1292 // will be inaccurate.
1293 os::set_priority(this, MaxPriority);
1294 if (!DisableStartThread) {
1295 os::start_thread(this);
1296 }
1297 }
1298 }
1299
1300 int WatcherThread::sleep() const {
1301 // The WatcherThread does not participate in the safepoint protocol
1302 // for the PeriodicTask_lock because it is not a JavaThread.
1303 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1304
1305 if (_should_terminate) {
1306 // check for termination before we do any housekeeping or wait
1307 return 0; // we did not sleep.
1308 }
1309
1310 // remaining will be zero if there are no tasks,
1311 // causing the WatcherThread to sleep until a task is
1312 // enrolled
1313 int remaining = PeriodicTask::time_to_wait();
1314 int time_slept = 0;
1315
1316 // we expect this to timeout - we only ever get unparked when
1317 // we should terminate or when a new task has been enrolled
1318 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1319
1320 jlong time_before_loop = os::javaTimeNanos();
1321
1322 while (true) {
1323 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1324 remaining);
1325 jlong now = os::javaTimeNanos();
1326
1327 if (remaining == 0) {
1328 // if we didn't have any tasks we could have waited for a long time
1329 // consider the time_slept zero and reset time_before_loop
1330 time_slept = 0;
1331 time_before_loop = now;
1332 } else {
1333 // need to recalculate since we might have new tasks in _tasks
1334 time_slept = (int) ((now - time_before_loop) / 1000000);
1335 }
1336
1337 // Change to task list or spurious wakeup of some kind
1338 if (timedout || _should_terminate) {
1339 break;
1340 }
1341
1342 remaining = PeriodicTask::time_to_wait();
1343 if (remaining == 0) {
1344 // Last task was just disenrolled so loop around and wait until
1345 // another task gets enrolled
1346 continue;
1347 }
1348
1349 remaining -= time_slept;
1350 if (remaining <= 0) {
1351 break;
1352 }
1353 }
1354
1355 return time_slept;
1356 }
1357
1358 void WatcherThread::run() {
1359 assert(this == watcher_thread(), "just checking");
1360
1361 this->record_stack_base_and_size();
1362 this->set_native_thread_name(this->name());
1363 this->set_active_handles(JNIHandleBlock::allocate_block());
1364 while (true) {
1365 assert(watcher_thread() == Thread::current(), "thread consistency check");
1366 assert(watcher_thread() == this, "thread consistency check");
1367
1368 // Calculate how long it'll be until the next PeriodicTask work
1369 // should be done, and sleep that amount of time.
1370 int time_waited = sleep();
1371
1372 if (VMError::is_error_reported()) {
1373 // A fatal error has happened, the error handler(VMError::report_and_die)
1374 // should abort JVM after creating an error log file. However in some
1375 // rare cases, the error handler itself might deadlock. Here periodically
1376 // check for error reporting timeouts, and if it happens, just proceed to
1377 // abort the VM.
1378
1379 // This code is in WatcherThread because WatcherThread wakes up
1380 // periodically so the fatal error handler doesn't need to do anything;
1381 // also because the WatcherThread is less likely to crash than other
1382 // threads.
1383
1384 for (;;) {
1385 // Note: we use naked sleep in this loop because we want to avoid using
1386 // any kind of VM infrastructure which may be broken at this point.
1387 if (VMError::check_timeout()) {
1388 // We hit error reporting timeout. Error reporting was interrupted and
1389 // will be wrapping things up now (closing files etc). Give it some more
1390 // time, then quit the VM.
1391 os::naked_short_sleep(200);
1392 // Print a message to stderr.
1393 fdStream err(defaultStream::output_fd());
1394 err.print_raw_cr("# [ timer expired, abort... ]");
1395 // skip atexit/vm_exit/vm_abort hooks
1396 os::die();
1397 }
1398
1399 // Wait a second, then recheck for timeout.
1400 os::naked_short_sleep(999);
1401 }
1402 }
1403
1404 if (_should_terminate) {
1405 // check for termination before posting the next tick
1406 break;
1407 }
1408
1409 PeriodicTask::real_time_tick(time_waited);
1410 }
1411
1412 // Signal that it is terminated
1413 {
1414 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1415 _watcher_thread = NULL;
1416 Terminator_lock->notify();
1417 }
1418 }
1419
1420 void WatcherThread::start() {
1421 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1422
1423 if (watcher_thread() == NULL && _startable) {
1424 _should_terminate = false;
1425 // Create the single instance of WatcherThread
1426 new WatcherThread();
1427 }
1428 }
1429
1430 void WatcherThread::make_startable() {
1431 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1432 _startable = true;
1433 }
1434
1435 void WatcherThread::stop() {
1436 {
1437 // Follow normal safepoint aware lock enter protocol since the
1438 // WatcherThread is stopped by another JavaThread.
1439 MutexLocker ml(PeriodicTask_lock);
1440 _should_terminate = true;
1441
1442 WatcherThread* watcher = watcher_thread();
1443 if (watcher != NULL) {
1444 // unpark the WatcherThread so it can see that it should terminate
1445 watcher->unpark();
1446 }
1447 }
1448
1449 MutexLocker mu(Terminator_lock);
1450
1451 while (watcher_thread() != NULL) {
1452 // This wait should make safepoint checks, wait without a timeout,
1453 // and wait as a suspend-equivalent condition.
1454 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1455 Mutex::_as_suspend_equivalent_flag);
1456 }
1457 }
1458
1459 void WatcherThread::unpark() {
1460 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1461 PeriodicTask_lock->notify();
1462 }
1463
1464 void WatcherThread::print_on(outputStream* st) const {
1465 st->print("\"%s\" ", name());
1466 Thread::print_on(st);
1467 st->cr();
1468 }
1469
1470 // ======= JavaThread ========
1471
1472 #if INCLUDE_JVMCI
1473
1474 jlong* JavaThread::_jvmci_old_thread_counters;
1475
1476 bool jvmci_counters_include(JavaThread* thread) {
1477 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1478 }
1479
1480 void JavaThread::collect_counters(typeArrayOop array) {
1481 if (JVMCICounterSize > 0) {
1482 JavaThreadIteratorWithHandle jtiwh;
1483 for (int i = 0; i < array->length(); i++) {
1484 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1485 }
1486 for (; JavaThread *tp = jtiwh.next(); ) {
1487 if (jvmci_counters_include(tp)) {
1488 for (int i = 0; i < array->length(); i++) {
1489 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1490 }
1491 }
1492 }
1493 }
1494 }
1495
1496 #endif // INCLUDE_JVMCI
1497
1498 // A JavaThread is a normal Java thread
1499
1500 void JavaThread::initialize() {
1501 // Initialize fields
1502
1503 set_saved_exception_pc(NULL);
1504 set_threadObj(NULL);
1505 _anchor.clear();
1506 set_entry_point(NULL);
1507 set_jni_functions(jni_functions());
1508 set_callee_target(NULL);
1509 set_vm_result(NULL);
1510 set_vm_result_2(NULL);
1511 set_vframe_array_head(NULL);
1512 set_vframe_array_last(NULL);
1513 set_deferred_locals(NULL);
1514 set_deopt_mark(NULL);
1515 set_deopt_compiled_method(NULL);
1516 clear_must_deopt_id();
1517 set_monitor_chunks(NULL);
1518 set_next(NULL);
1519 _on_thread_list = false;
1520 set_thread_state(_thread_new);
1521 _terminated = _not_terminated;
1522 _privileged_stack_top = NULL;
1523 _array_for_gc = NULL;
1524 _suspend_equivalent = false;
1525 _in_deopt_handler = 0;
1526 _doing_unsafe_access = false;
1527 _stack_guard_state = stack_guard_unused;
1528 #if INCLUDE_JVMCI
1529 _pending_monitorenter = false;
1530 _pending_deoptimization = -1;
1531 _pending_failed_speculation = NULL;
1532 _pending_transfer_to_interpreter = false;
1533 _adjusting_comp_level = false;
1534 _jvmci._alternate_call_target = NULL;
1535 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1536 if (JVMCICounterSize > 0) {
1537 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1538 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1539 } else {
1540 _jvmci_counters = NULL;
1541 }
1542 #endif // INCLUDE_JVMCI
1543 _reserved_stack_activation = NULL; // stack base not known yet
1544 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1545 _exception_pc = 0;
1546 _exception_handler_pc = 0;
1547 _is_method_handle_return = 0;
1548 _jvmti_thread_state= NULL;
1549 _should_post_on_exceptions_flag = JNI_FALSE;
1550 _jvmti_get_loaded_classes_closure = NULL;
1551 _interp_only_mode = 0;
1552 _special_runtime_exit_condition = _no_async_condition;
1553 _pending_async_exception = NULL;
1554 _thread_stat = NULL;
1555 _thread_stat = new ThreadStatistics();
1556 _blocked_on_compilation = false;
1557 _jni_active_critical = 0;
1558 _pending_jni_exception_check_fn = NULL;
1559 _do_not_unlock_if_synchronized = false;
1560 _cached_monitor_info = NULL;
1561 _parker = Parker::Allocate(this);
1562
1563 #ifndef PRODUCT
1564 _jmp_ring_index = 0;
1565 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1566 record_jump(NULL, NULL, NULL, 0);
1567 }
1568 #endif // PRODUCT
1569
1570 // Setup safepoint state info for this thread
1571 ThreadSafepointState::create(this);
1572
1573 debug_only(_java_call_counter = 0);
1574
1575 // JVMTI PopFrame support
1576 _popframe_condition = popframe_inactive;
1577 _popframe_preserved_args = NULL;
1578 _popframe_preserved_args_size = 0;
1579 _frames_to_pop_failed_realloc = 0;
1580
1581 if (SafepointMechanism::uses_thread_local_poll()) {
1582 SafepointMechanism::initialize_header(this);
1583 }
1584
1585 pd_initialize();
1586 }
1587
1588 JavaThread::JavaThread(bool is_attaching_via_jni) :
1589 Thread() {
1590 initialize();
1591 if (is_attaching_via_jni) {
1592 _jni_attach_state = _attaching_via_jni;
1593 } else {
1594 _jni_attach_state = _not_attaching_via_jni;
1595 }
1596 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1597 }
1598
1599 bool JavaThread::reguard_stack(address cur_sp) {
1600 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1601 && _stack_guard_state != stack_guard_reserved_disabled) {
1602 return true; // Stack already guarded or guard pages not needed.
1603 }
1604
1605 if (register_stack_overflow()) {
1606 // For those architectures which have separate register and
1607 // memory stacks, we must check the register stack to see if
1608 // it has overflowed.
1609 return false;
1610 }
1611
1612 // Java code never executes within the yellow zone: the latter is only
1613 // there to provoke an exception during stack banging. If java code
1614 // is executing there, either StackShadowPages should be larger, or
1615 // some exception code in c1, c2 or the interpreter isn't unwinding
1616 // when it should.
1617 guarantee(cur_sp > stack_reserved_zone_base(),
1618 "not enough space to reguard - increase StackShadowPages");
1619 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1620 enable_stack_yellow_reserved_zone();
1621 if (reserved_stack_activation() != stack_base()) {
1622 set_reserved_stack_activation(stack_base());
1623 }
1624 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1625 set_reserved_stack_activation(stack_base());
1626 enable_stack_reserved_zone();
1627 }
1628 return true;
1629 }
1630
1631 bool JavaThread::reguard_stack(void) {
1632 return reguard_stack(os::current_stack_pointer());
1633 }
1634
1635
1636 void JavaThread::block_if_vm_exited() {
1637 if (_terminated == _vm_exited) {
1638 // _vm_exited is set at safepoint, and Threads_lock is never released
1639 // we will block here forever
1640 Threads_lock->lock_without_safepoint_check();
1641 ShouldNotReachHere();
1642 }
1643 }
1644
1645
1646 // Remove this ifdef when C1 is ported to the compiler interface.
1647 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1648 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1649
1650 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1651 Thread() {
1652 initialize();
1653 _jni_attach_state = _not_attaching_via_jni;
1654 set_entry_point(entry_point);
1655 // Create the native thread itself.
1656 // %note runtime_23
1657 os::ThreadType thr_type = os::java_thread;
1658 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1659 os::java_thread;
1660 os::create_thread(this, thr_type, stack_sz);
1661 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1662 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1663 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1664 // the exception consists of creating the exception object & initializing it, initialization
1665 // will leave the VM via a JavaCall and then all locks must be unlocked).
1666 //
1667 // The thread is still suspended when we reach here. Thread must be explicit started
1668 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1669 // by calling Threads:add. The reason why this is not done here, is because the thread
1670 // object must be fully initialized (take a look at JVM_Start)
1671 }
1672
1673 JavaThread::~JavaThread() {
1674
1675 // JSR166 -- return the parker to the free list
1676 Parker::Release(_parker);
1677 _parker = NULL;
1678
1679 // Free any remaining previous UnrollBlock
1680 vframeArray* old_array = vframe_array_last();
1681
1682 if (old_array != NULL) {
1683 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1684 old_array->set_unroll_block(NULL);
1685 delete old_info;
1686 delete old_array;
1687 }
1688
1689 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1690 if (deferred != NULL) {
1691 // This can only happen if thread is destroyed before deoptimization occurs.
1692 assert(deferred->length() != 0, "empty array!");
1693 do {
1694 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1695 deferred->remove_at(0);
1696 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1697 delete dlv;
1698 } while (deferred->length() != 0);
1699 delete deferred;
1700 }
1701
1702 // All Java related clean up happens in exit
1703 ThreadSafepointState::destroy(this);
1704 if (_thread_stat != NULL) delete _thread_stat;
1705
1706 #if INCLUDE_JVMCI
1707 if (JVMCICounterSize > 0) {
1708 if (jvmci_counters_include(this)) {
1709 for (int i = 0; i < JVMCICounterSize; i++) {
1710 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1711 }
1712 }
1713 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1714 }
1715 #endif // INCLUDE_JVMCI
1716 }
1717
1718
1719 // The first routine called by a new Java thread
1720 void JavaThread::run() {
1721 // initialize thread-local alloc buffer related fields
1722 this->initialize_tlab();
1723
1724 // used to test validity of stack trace backs
1725 this->record_base_of_stack_pointer();
1726
1727 // Record real stack base and size.
1728 this->record_stack_base_and_size();
1729
1730 this->create_stack_guard_pages();
1731
1732 this->cache_global_variables();
1733
1734 // Thread is now sufficient initialized to be handled by the safepoint code as being
1735 // in the VM. Change thread state from _thread_new to _thread_in_vm
1736 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1737
1738 assert(JavaThread::current() == this, "sanity check");
1739 assert(!Thread::current()->owns_locks(), "sanity check");
1740
1741 DTRACE_THREAD_PROBE(start, this);
1742
1743 // This operation might block. We call that after all safepoint checks for a new thread has
1744 // been completed.
1745 this->set_active_handles(JNIHandleBlock::allocate_block());
1746
1747 if (JvmtiExport::should_post_thread_life()) {
1748 JvmtiExport::post_thread_start(this);
1749 }
1750
1751 EventThreadStart event;
1752 if (event.should_commit()) {
1753 event.set_thread(JFR_THREAD_ID(this));
1754 event.commit();
1755 }
1756
1757 // We call another function to do the rest so we are sure that the stack addresses used
1758 // from there will be lower than the stack base just computed
1759 thread_main_inner();
1760
1761 // Note, thread is no longer valid at this point!
1762 }
1763
1764
1765 void JavaThread::thread_main_inner() {
1766 assert(JavaThread::current() == this, "sanity check");
1767 assert(this->threadObj() != NULL, "just checking");
1768
1769 // Execute thread entry point unless this thread has a pending exception
1770 // or has been stopped before starting.
1771 // Note: Due to JVM_StopThread we can have pending exceptions already!
1772 if (!this->has_pending_exception() &&
1773 !java_lang_Thread::is_stillborn(this->threadObj())) {
1774 {
1775 ResourceMark rm(this);
1776 this->set_native_thread_name(this->get_thread_name());
1777 }
1778 HandleMark hm(this);
1779 this->entry_point()(this, this);
1780 }
1781
1782 DTRACE_THREAD_PROBE(stop, this);
1783
1784 this->exit(false);
1785 this->smr_delete();
1786 }
1787
1788
1789 static void ensure_join(JavaThread* thread) {
1790 // We do not need to grab the Threads_lock, since we are operating on ourself.
1791 Handle threadObj(thread, thread->threadObj());
1792 assert(threadObj.not_null(), "java thread object must exist");
1793 ObjectLocker lock(threadObj, thread);
1794 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1795 thread->clear_pending_exception();
1796 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1797 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1798 // Clear the native thread instance - this makes isAlive return false and allows the join()
1799 // to complete once we've done the notify_all below
1800 java_lang_Thread::set_thread(threadObj(), NULL);
1801 lock.notify_all(thread);
1802 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1803 thread->clear_pending_exception();
1804 }
1805
1806
1807 // For any new cleanup additions, please check to see if they need to be applied to
1808 // cleanup_failed_attach_current_thread as well.
1809 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1810 assert(this == JavaThread::current(), "thread consistency check");
1811
1812 elapsedTimer _timer_exit_phase1;
1813 elapsedTimer _timer_exit_phase2;
1814 elapsedTimer _timer_exit_phase3;
1815 elapsedTimer _timer_exit_phase4;
1816
1817 if (log_is_enabled(Debug, os, thread, timer)) {
1818 _timer_exit_phase1.start();
1819 }
1820
1821 HandleMark hm(this);
1822 Handle uncaught_exception(this, this->pending_exception());
1823 this->clear_pending_exception();
1824 Handle threadObj(this, this->threadObj());
1825 assert(threadObj.not_null(), "Java thread object should be created");
1826
1827 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1828 {
1829 EXCEPTION_MARK;
1830
1831 CLEAR_PENDING_EXCEPTION;
1832 }
1833 if (!destroy_vm) {
1834 if (uncaught_exception.not_null()) {
1835 EXCEPTION_MARK;
1836 // Call method Thread.dispatchUncaughtException().
1837 Klass* thread_klass = SystemDictionary::Thread_klass();
1838 JavaValue result(T_VOID);
1839 JavaCalls::call_virtual(&result,
1840 threadObj, thread_klass,
1841 vmSymbols::dispatchUncaughtException_name(),
1842 vmSymbols::throwable_void_signature(),
1843 uncaught_exception,
1844 THREAD);
1845 if (HAS_PENDING_EXCEPTION) {
1846 ResourceMark rm(this);
1847 jio_fprintf(defaultStream::error_stream(),
1848 "\nException: %s thrown from the UncaughtExceptionHandler"
1849 " in thread \"%s\"\n",
1850 pending_exception()->klass()->external_name(),
1851 get_thread_name());
1852 CLEAR_PENDING_EXCEPTION;
1853 }
1854 }
1855
1856 // Called before the java thread exit since we want to read info
1857 // from java_lang_Thread object
1858 EventThreadEnd event;
1859 if (event.should_commit()) {
1860 event.set_thread(JFR_THREAD_ID(this));
1861 event.commit();
1862 }
1863
1864 // Call after last event on thread
1865 JFR_ONLY(Jfr::on_thread_exit(this);)
1866
1867 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1868 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1869 // is deprecated anyhow.
1870 if (!is_Compiler_thread()) {
1871 int count = 3;
1872 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1873 EXCEPTION_MARK;
1874 JavaValue result(T_VOID);
1875 Klass* thread_klass = SystemDictionary::Thread_klass();
1876 JavaCalls::call_virtual(&result,
1877 threadObj, thread_klass,
1878 vmSymbols::exit_method_name(),
1879 vmSymbols::void_method_signature(),
1880 THREAD);
1881 CLEAR_PENDING_EXCEPTION;
1882 }
1883 }
1884 // notify JVMTI
1885 if (JvmtiExport::should_post_thread_life()) {
1886 JvmtiExport::post_thread_end(this);
1887 }
1888
1889 // We have notified the agents that we are exiting, before we go on,
1890 // we must check for a pending external suspend request and honor it
1891 // in order to not surprise the thread that made the suspend request.
1892 while (true) {
1893 {
1894 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1895 if (!is_external_suspend()) {
1896 set_terminated(_thread_exiting);
1897 ThreadService::current_thread_exiting(this);
1898 break;
1899 }
1900 // Implied else:
1901 // Things get a little tricky here. We have a pending external
1902 // suspend request, but we are holding the SR_lock so we
1903 // can't just self-suspend. So we temporarily drop the lock
1904 // and then self-suspend.
1905 }
1906
1907 ThreadBlockInVM tbivm(this);
1908 java_suspend_self();
1909
1910 // We're done with this suspend request, but we have to loop around
1911 // and check again. Eventually we will get SR_lock without a pending
1912 // external suspend request and will be able to mark ourselves as
1913 // exiting.
1914 }
1915 // no more external suspends are allowed at this point
1916 } else {
1917 // before_exit() has already posted JVMTI THREAD_END events
1918 }
1919
1920 if (log_is_enabled(Debug, os, thread, timer)) {
1921 _timer_exit_phase1.stop();
1922 _timer_exit_phase2.start();
1923 }
1924 // Notify waiters on thread object. This has to be done after exit() is called
1925 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1926 // group should have the destroyed bit set before waiters are notified).
1927 ensure_join(this);
1928 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1929
1930 if (log_is_enabled(Debug, os, thread, timer)) {
1931 _timer_exit_phase2.stop();
1932 _timer_exit_phase3.start();
1933 }
1934 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1935 // held by this thread must be released. The spec does not distinguish
1936 // between JNI-acquired and regular Java monitors. We can only see
1937 // regular Java monitors here if monitor enter-exit matching is broken.
1938 //
1939 // Optionally release any monitors for regular JavaThread exits. This
1940 // is provided as a work around for any bugs in monitor enter-exit
1941 // matching. This can be expensive so it is not enabled by default.
1942 //
1943 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1944 // ObjectSynchronizer::release_monitors_owned_by_thread().
1945 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1946 // Sanity check even though JNI DetachCurrentThread() would have
1947 // returned JNI_ERR if there was a Java frame. JavaThread exit
1948 // should be done executing Java code by the time we get here.
1949 assert(!this->has_last_Java_frame(),
1950 "should not have a Java frame when detaching or exiting");
1951 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1952 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1953 }
1954
1955 // These things needs to be done while we are still a Java Thread. Make sure that thread
1956 // is in a consistent state, in case GC happens
1957 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1958
1959 if (active_handles() != NULL) {
1960 JNIHandleBlock* block = active_handles();
1961 set_active_handles(NULL);
1962 JNIHandleBlock::release_block(block);
1963 }
1964
1965 if (free_handle_block() != NULL) {
1966 JNIHandleBlock* block = free_handle_block();
1967 set_free_handle_block(NULL);
1968 JNIHandleBlock::release_block(block);
1969 }
1970
1971 // These have to be removed while this is still a valid thread.
1972 remove_stack_guard_pages();
1973
1974 if (UseTLAB) {
1975 tlab().make_parsable(true); // retire TLAB
1976 }
1977
1978 if (JvmtiEnv::environments_might_exist()) {
1979 JvmtiExport::cleanup_thread(this);
1980 }
1981
1982 // We must flush any deferred card marks and other various GC barrier
1983 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
1984 // before removing a thread from the list of active threads.
1985 BarrierSet::barrier_set()->on_thread_detach(this);
1986
1987 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1988 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1989 os::current_thread_id());
1990
1991 if (log_is_enabled(Debug, os, thread, timer)) {
1992 _timer_exit_phase3.stop();
1993 _timer_exit_phase4.start();
1994 }
1995 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1996 Threads::remove(this);
1997
1998 if (log_is_enabled(Debug, os, thread, timer)) {
1999 _timer_exit_phase4.stop();
2000 ResourceMark rm(this);
2001 log_debug(os, thread, timer)("name='%s'"
2002 ", exit-phase1=" JLONG_FORMAT
2003 ", exit-phase2=" JLONG_FORMAT
2004 ", exit-phase3=" JLONG_FORMAT
2005 ", exit-phase4=" JLONG_FORMAT,
2006 get_thread_name(),
2007 _timer_exit_phase1.milliseconds(),
2008 _timer_exit_phase2.milliseconds(),
2009 _timer_exit_phase3.milliseconds(),
2010 _timer_exit_phase4.milliseconds());
2011 }
2012 }
2013
2014 void JavaThread::cleanup_failed_attach_current_thread() {
2015 if (active_handles() != NULL) {
2016 JNIHandleBlock* block = active_handles();
2017 set_active_handles(NULL);
2018 JNIHandleBlock::release_block(block);
2019 }
2020
2021 if (free_handle_block() != NULL) {
2022 JNIHandleBlock* block = free_handle_block();
2023 set_free_handle_block(NULL);
2024 JNIHandleBlock::release_block(block);
2025 }
2026
2027 // These have to be removed while this is still a valid thread.
2028 remove_stack_guard_pages();
2029
2030 if (UseTLAB) {
2031 tlab().make_parsable(true); // retire TLAB, if any
2032 }
2033
2034 BarrierSet::barrier_set()->on_thread_detach(this);
2035
2036 Threads::remove(this);
2037 this->smr_delete();
2038 }
2039
2040 JavaThread* JavaThread::active() {
2041 Thread* thread = Thread::current();
2042 if (thread->is_Java_thread()) {
2043 return (JavaThread*) thread;
2044 } else {
2045 assert(thread->is_VM_thread(), "this must be a vm thread");
2046 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2047 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2048 assert(ret->is_Java_thread(), "must be a Java thread");
2049 return ret;
2050 }
2051 }
2052
2053 bool JavaThread::is_lock_owned(address adr) const {
2054 if (Thread::is_lock_owned(adr)) return true;
2055
2056 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2057 if (chunk->contains(adr)) return true;
2058 }
2059
2060 return false;
2061 }
2062
2063
2064 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2065 chunk->set_next(monitor_chunks());
2066 set_monitor_chunks(chunk);
2067 }
2068
2069 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2070 guarantee(monitor_chunks() != NULL, "must be non empty");
2071 if (monitor_chunks() == chunk) {
2072 set_monitor_chunks(chunk->next());
2073 } else {
2074 MonitorChunk* prev = monitor_chunks();
2075 while (prev->next() != chunk) prev = prev->next();
2076 prev->set_next(chunk->next());
2077 }
2078 }
2079
2080 // JVM support.
2081
2082 // Note: this function shouldn't block if it's called in
2083 // _thread_in_native_trans state (such as from
2084 // check_special_condition_for_native_trans()).
2085 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2086
2087 if (has_last_Java_frame() && has_async_condition()) {
2088 // If we are at a polling page safepoint (not a poll return)
2089 // then we must defer async exception because live registers
2090 // will be clobbered by the exception path. Poll return is
2091 // ok because the call we a returning from already collides
2092 // with exception handling registers and so there is no issue.
2093 // (The exception handling path kills call result registers but
2094 // this is ok since the exception kills the result anyway).
2095
2096 if (is_at_poll_safepoint()) {
2097 // if the code we are returning to has deoptimized we must defer
2098 // the exception otherwise live registers get clobbered on the
2099 // exception path before deoptimization is able to retrieve them.
2100 //
2101 RegisterMap map(this, false);
2102 frame caller_fr = last_frame().sender(&map);
2103 assert(caller_fr.is_compiled_frame(), "what?");
2104 if (caller_fr.is_deoptimized_frame()) {
2105 log_info(exceptions)("deferred async exception at compiled safepoint");
2106 return;
2107 }
2108 }
2109 }
2110
2111 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2112 if (condition == _no_async_condition) {
2113 // Conditions have changed since has_special_runtime_exit_condition()
2114 // was called:
2115 // - if we were here only because of an external suspend request,
2116 // then that was taken care of above (or cancelled) so we are done
2117 // - if we were here because of another async request, then it has
2118 // been cleared between the has_special_runtime_exit_condition()
2119 // and now so again we are done
2120 return;
2121 }
2122
2123 // Check for pending async. exception
2124 if (_pending_async_exception != NULL) {
2125 // Only overwrite an already pending exception, if it is not a threadDeath.
2126 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2127
2128 // We cannot call Exceptions::_throw(...) here because we cannot block
2129 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2130
2131 LogTarget(Info, exceptions) lt;
2132 if (lt.is_enabled()) {
2133 ResourceMark rm;
2134 LogStream ls(lt);
2135 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2136 if (has_last_Java_frame()) {
2137 frame f = last_frame();
2138 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2139 }
2140 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2141 }
2142 _pending_async_exception = NULL;
2143 clear_has_async_exception();
2144 }
2145 }
2146
2147 if (check_unsafe_error &&
2148 condition == _async_unsafe_access_error && !has_pending_exception()) {
2149 condition = _no_async_condition; // done
2150 switch (thread_state()) {
2151 case _thread_in_vm: {
2152 JavaThread* THREAD = this;
2153 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2154 }
2155 case _thread_in_native: {
2156 ThreadInVMfromNative tiv(this);
2157 JavaThread* THREAD = this;
2158 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2159 }
2160 case _thread_in_Java: {
2161 ThreadInVMfromJava tiv(this);
2162 JavaThread* THREAD = this;
2163 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2164 }
2165 default:
2166 ShouldNotReachHere();
2167 }
2168 }
2169
2170 assert(condition == _no_async_condition || has_pending_exception() ||
2171 (!check_unsafe_error && condition == _async_unsafe_access_error),
2172 "must have handled the async condition, if no exception");
2173 }
2174
2175 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2176 //
2177 // Check for pending external suspend. Internal suspend requests do
2178 // not use handle_special_runtime_exit_condition().
2179 // If JNIEnv proxies are allowed, don't self-suspend if the target
2180 // thread is not the current thread. In older versions of jdbx, jdbx
2181 // threads could call into the VM with another thread's JNIEnv so we
2182 // can be here operating on behalf of a suspended thread (4432884).
2183 bool do_self_suspend = is_external_suspend_with_lock();
2184 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2185 //
2186 // Because thread is external suspended the safepoint code will count
2187 // thread as at a safepoint. This can be odd because we can be here
2188 // as _thread_in_Java which would normally transition to _thread_blocked
2189 // at a safepoint. We would like to mark the thread as _thread_blocked
2190 // before calling java_suspend_self like all other callers of it but
2191 // we must then observe proper safepoint protocol. (We can't leave
2192 // _thread_blocked with a safepoint in progress). However we can be
2193 // here as _thread_in_native_trans so we can't use a normal transition
2194 // constructor/destructor pair because they assert on that type of
2195 // transition. We could do something like:
2196 //
2197 // JavaThreadState state = thread_state();
2198 // set_thread_state(_thread_in_vm);
2199 // {
2200 // ThreadBlockInVM tbivm(this);
2201 // java_suspend_self()
2202 // }
2203 // set_thread_state(_thread_in_vm_trans);
2204 // if (safepoint) block;
2205 // set_thread_state(state);
2206 //
2207 // but that is pretty messy. Instead we just go with the way the
2208 // code has worked before and note that this is the only path to
2209 // java_suspend_self that doesn't put the thread in _thread_blocked
2210 // mode.
2211
2212 frame_anchor()->make_walkable(this);
2213 java_suspend_self();
2214
2215 // We might be here for reasons in addition to the self-suspend request
2216 // so check for other async requests.
2217 }
2218
2219 if (check_asyncs) {
2220 check_and_handle_async_exceptions();
2221 }
2222
2223 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2224 }
2225
2226 void JavaThread::send_thread_stop(oop java_throwable) {
2227 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2228 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2229 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2230
2231 // Do not throw asynchronous exceptions against the compiler thread
2232 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2233 if (!can_call_java()) return;
2234
2235 {
2236 // Actually throw the Throwable against the target Thread - however
2237 // only if there is no thread death exception installed already.
2238 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2239 // If the topmost frame is a runtime stub, then we are calling into
2240 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2241 // must deoptimize the caller before continuing, as the compiled exception handler table
2242 // may not be valid
2243 if (has_last_Java_frame()) {
2244 frame f = last_frame();
2245 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2246 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2247 RegisterMap reg_map(this, UseBiasedLocking);
2248 frame compiled_frame = f.sender(®_map);
2249 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2250 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2251 }
2252 }
2253 }
2254
2255 // Set async. pending exception in thread.
2256 set_pending_async_exception(java_throwable);
2257
2258 if (log_is_enabled(Info, exceptions)) {
2259 ResourceMark rm;
2260 log_info(exceptions)("Pending Async. exception installed of type: %s",
2261 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2262 }
2263 // for AbortVMOnException flag
2264 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2265 }
2266 }
2267
2268
2269 // Interrupt thread so it will wake up from a potential wait()
2270 Thread::interrupt(this);
2271 }
2272
2273 // External suspension mechanism.
2274 //
2275 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2276 // to any VM_locks and it is at a transition
2277 // Self-suspension will happen on the transition out of the vm.
2278 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2279 //
2280 // Guarantees on return:
2281 // + Target thread will not execute any new bytecode (that's why we need to
2282 // force a safepoint)
2283 // + Target thread will not enter any new monitors
2284 //
2285 void JavaThread::java_suspend() {
2286 ThreadsListHandle tlh;
2287 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2288 return;
2289 }
2290
2291 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2292 if (!is_external_suspend()) {
2293 // a racing resume has cancelled us; bail out now
2294 return;
2295 }
2296
2297 // suspend is done
2298 uint32_t debug_bits = 0;
2299 // Warning: is_ext_suspend_completed() may temporarily drop the
2300 // SR_lock to allow the thread to reach a stable thread state if
2301 // it is currently in a transient thread state.
2302 if (is_ext_suspend_completed(false /* !called_by_wait */,
2303 SuspendRetryDelay, &debug_bits)) {
2304 return;
2305 }
2306 }
2307
2308 VM_ThreadSuspend vm_suspend;
2309 VMThread::execute(&vm_suspend);
2310 }
2311
2312 // Part II of external suspension.
2313 // A JavaThread self suspends when it detects a pending external suspend
2314 // request. This is usually on transitions. It is also done in places
2315 // where continuing to the next transition would surprise the caller,
2316 // e.g., monitor entry.
2317 //
2318 // Returns the number of times that the thread self-suspended.
2319 //
2320 // Note: DO NOT call java_suspend_self() when you just want to block current
2321 // thread. java_suspend_self() is the second stage of cooperative
2322 // suspension for external suspend requests and should only be used
2323 // to complete an external suspend request.
2324 //
2325 int JavaThread::java_suspend_self() {
2326 int ret = 0;
2327
2328 // we are in the process of exiting so don't suspend
2329 if (is_exiting()) {
2330 clear_external_suspend();
2331 return ret;
2332 }
2333
2334 assert(_anchor.walkable() ||
2335 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2336 "must have walkable stack");
2337
2338 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2339
2340 assert(!this->is_ext_suspended(),
2341 "a thread trying to self-suspend should not already be suspended");
2342
2343 if (this->is_suspend_equivalent()) {
2344 // If we are self-suspending as a result of the lifting of a
2345 // suspend equivalent condition, then the suspend_equivalent
2346 // flag is not cleared until we set the ext_suspended flag so
2347 // that wait_for_ext_suspend_completion() returns consistent
2348 // results.
2349 this->clear_suspend_equivalent();
2350 }
2351
2352 // A racing resume may have cancelled us before we grabbed SR_lock
2353 // above. Or another external suspend request could be waiting for us
2354 // by the time we return from SR_lock()->wait(). The thread
2355 // that requested the suspension may already be trying to walk our
2356 // stack and if we return now, we can change the stack out from under
2357 // it. This would be a "bad thing (TM)" and cause the stack walker
2358 // to crash. We stay self-suspended until there are no more pending
2359 // external suspend requests.
2360 while (is_external_suspend()) {
2361 ret++;
2362 this->set_ext_suspended();
2363
2364 // _ext_suspended flag is cleared by java_resume()
2365 while (is_ext_suspended()) {
2366 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2367 }
2368 }
2369
2370 return ret;
2371 }
2372
2373 #ifdef ASSERT
2374 // Verify the JavaThread has not yet been published in the Threads::list, and
2375 // hence doesn't need protection from concurrent access at this stage.
2376 void JavaThread::verify_not_published() {
2377 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2378 // since an unpublished JavaThread doesn't participate in the
2379 // Thread-SMR protocol for keeping a ThreadsList alive.
2380 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2381 }
2382 #endif
2383
2384 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2385 // progress or when _suspend_flags is non-zero.
2386 // Current thread needs to self-suspend if there is a suspend request and/or
2387 // block if a safepoint is in progress.
2388 // Async exception ISN'T checked.
2389 // Note only the ThreadInVMfromNative transition can call this function
2390 // directly and when thread state is _thread_in_native_trans
2391 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2392 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2393
2394 JavaThread *curJT = JavaThread::current();
2395 bool do_self_suspend = thread->is_external_suspend();
2396
2397 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2398
2399 // If JNIEnv proxies are allowed, don't self-suspend if the target
2400 // thread is not the current thread. In older versions of jdbx, jdbx
2401 // threads could call into the VM with another thread's JNIEnv so we
2402 // can be here operating on behalf of a suspended thread (4432884).
2403 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2404 JavaThreadState state = thread->thread_state();
2405
2406 // We mark this thread_blocked state as a suspend-equivalent so
2407 // that a caller to is_ext_suspend_completed() won't be confused.
2408 // The suspend-equivalent state is cleared by java_suspend_self().
2409 thread->set_suspend_equivalent();
2410
2411 // If the safepoint code sees the _thread_in_native_trans state, it will
2412 // wait until the thread changes to other thread state. There is no
2413 // guarantee on how soon we can obtain the SR_lock and complete the
2414 // self-suspend request. It would be a bad idea to let safepoint wait for
2415 // too long. Temporarily change the state to _thread_blocked to
2416 // let the VM thread know that this thread is ready for GC. The problem
2417 // of changing thread state is that safepoint could happen just after
2418 // java_suspend_self() returns after being resumed, and VM thread will
2419 // see the _thread_blocked state. We must check for safepoint
2420 // after restoring the state and make sure we won't leave while a safepoint
2421 // is in progress.
2422 thread->set_thread_state(_thread_blocked);
2423 thread->java_suspend_self();
2424 thread->set_thread_state(state);
2425
2426 InterfaceSupport::serialize_thread_state_with_handler(thread);
2427 }
2428
2429 SafepointMechanism::block_if_requested(curJT);
2430
2431 if (thread->is_deopt_suspend()) {
2432 thread->clear_deopt_suspend();
2433 RegisterMap map(thread, false);
2434 frame f = thread->last_frame();
2435 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2436 f = f.sender(&map);
2437 }
2438 if (f.id() == thread->must_deopt_id()) {
2439 thread->clear_must_deopt_id();
2440 f.deoptimize(thread);
2441 } else {
2442 fatal("missed deoptimization!");
2443 }
2444 }
2445
2446 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2447 }
2448
2449 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2450 // progress or when _suspend_flags is non-zero.
2451 // Current thread needs to self-suspend if there is a suspend request and/or
2452 // block if a safepoint is in progress.
2453 // Also check for pending async exception (not including unsafe access error).
2454 // Note only the native==>VM/Java barriers can call this function and when
2455 // thread state is _thread_in_native_trans.
2456 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2457 check_safepoint_and_suspend_for_native_trans(thread);
2458
2459 if (thread->has_async_exception()) {
2460 // We are in _thread_in_native_trans state, don't handle unsafe
2461 // access error since that may block.
2462 thread->check_and_handle_async_exceptions(false);
2463 }
2464 }
2465
2466 // This is a variant of the normal
2467 // check_special_condition_for_native_trans with slightly different
2468 // semantics for use by critical native wrappers. It does all the
2469 // normal checks but also performs the transition back into
2470 // thread_in_Java state. This is required so that critical natives
2471 // can potentially block and perform a GC if they are the last thread
2472 // exiting the GCLocker.
2473 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2474 check_special_condition_for_native_trans(thread);
2475
2476 // Finish the transition
2477 thread->set_thread_state(_thread_in_Java);
2478
2479 if (thread->do_critical_native_unlock()) {
2480 ThreadInVMfromJavaNoAsyncException tiv(thread);
2481 GCLocker::unlock_critical(thread);
2482 thread->clear_critical_native_unlock();
2483 }
2484 }
2485
2486 // We need to guarantee the Threads_lock here, since resumes are not
2487 // allowed during safepoint synchronization
2488 // Can only resume from an external suspension
2489 void JavaThread::java_resume() {
2490 assert_locked_or_safepoint(Threads_lock);
2491
2492 // Sanity check: thread is gone, has started exiting or the thread
2493 // was not externally suspended.
2494 ThreadsListHandle tlh;
2495 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2496 return;
2497 }
2498
2499 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2500
2501 clear_external_suspend();
2502
2503 if (is_ext_suspended()) {
2504 clear_ext_suspended();
2505 SR_lock()->notify_all();
2506 }
2507 }
2508
2509 size_t JavaThread::_stack_red_zone_size = 0;
2510 size_t JavaThread::_stack_yellow_zone_size = 0;
2511 size_t JavaThread::_stack_reserved_zone_size = 0;
2512 size_t JavaThread::_stack_shadow_zone_size = 0;
2513
2514 void JavaThread::create_stack_guard_pages() {
2515 if (!os::uses_stack_guard_pages() ||
2516 _stack_guard_state != stack_guard_unused ||
2517 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2518 log_info(os, thread)("Stack guard page creation for thread "
2519 UINTX_FORMAT " disabled", os::current_thread_id());
2520 return;
2521 }
2522 address low_addr = stack_end();
2523 size_t len = stack_guard_zone_size();
2524
2525 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2526 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2527
2528 int must_commit = os::must_commit_stack_guard_pages();
2529 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2530
2531 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2532 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2533 return;
2534 }
2535
2536 if (os::guard_memory((char *) low_addr, len)) {
2537 _stack_guard_state = stack_guard_enabled;
2538 } else {
2539 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2540 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2541 if (os::uncommit_memory((char *) low_addr, len)) {
2542 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2543 }
2544 return;
2545 }
2546
2547 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2548 PTR_FORMAT "-" PTR_FORMAT ".",
2549 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2550 }
2551
2552 void JavaThread::remove_stack_guard_pages() {
2553 assert(Thread::current() == this, "from different thread");
2554 if (_stack_guard_state == stack_guard_unused) return;
2555 address low_addr = stack_end();
2556 size_t len = stack_guard_zone_size();
2557
2558 if (os::must_commit_stack_guard_pages()) {
2559 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2560 _stack_guard_state = stack_guard_unused;
2561 } else {
2562 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2563 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2564 return;
2565 }
2566 } else {
2567 if (_stack_guard_state == stack_guard_unused) return;
2568 if (os::unguard_memory((char *) low_addr, len)) {
2569 _stack_guard_state = stack_guard_unused;
2570 } else {
2571 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2572 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2573 return;
2574 }
2575 }
2576
2577 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2578 PTR_FORMAT "-" PTR_FORMAT ".",
2579 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2580 }
2581
2582 void JavaThread::enable_stack_reserved_zone() {
2583 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2584 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2585
2586 // The base notation is from the stack's point of view, growing downward.
2587 // We need to adjust it to work correctly with guard_memory()
2588 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2589
2590 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2591 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2592
2593 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2594 _stack_guard_state = stack_guard_enabled;
2595 } else {
2596 warning("Attempt to guard stack reserved zone failed.");
2597 }
2598 enable_register_stack_guard();
2599 }
2600
2601 void JavaThread::disable_stack_reserved_zone() {
2602 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2603 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2604
2605 // Simply return if called for a thread that does not use guard pages.
2606 if (_stack_guard_state == stack_guard_unused) return;
2607
2608 // The base notation is from the stack's point of view, growing downward.
2609 // We need to adjust it to work correctly with guard_memory()
2610 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2611
2612 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2613 _stack_guard_state = stack_guard_reserved_disabled;
2614 } else {
2615 warning("Attempt to unguard stack reserved zone failed.");
2616 }
2617 disable_register_stack_guard();
2618 }
2619
2620 void JavaThread::enable_stack_yellow_reserved_zone() {
2621 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2622 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2623
2624 // The base notation is from the stacks point of view, growing downward.
2625 // We need to adjust it to work correctly with guard_memory()
2626 address base = stack_red_zone_base();
2627
2628 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2629 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2630
2631 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2632 _stack_guard_state = stack_guard_enabled;
2633 } else {
2634 warning("Attempt to guard stack yellow zone failed.");
2635 }
2636 enable_register_stack_guard();
2637 }
2638
2639 void JavaThread::disable_stack_yellow_reserved_zone() {
2640 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2641 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2642
2643 // Simply return if called for a thread that does not use guard pages.
2644 if (_stack_guard_state == stack_guard_unused) return;
2645
2646 // The base notation is from the stacks point of view, growing downward.
2647 // We need to adjust it to work correctly with guard_memory()
2648 address base = stack_red_zone_base();
2649
2650 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2651 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2652 } else {
2653 warning("Attempt to unguard stack yellow zone failed.");
2654 }
2655 disable_register_stack_guard();
2656 }
2657
2658 void JavaThread::enable_stack_red_zone() {
2659 // The base notation is from the stacks point of view, growing downward.
2660 // We need to adjust it to work correctly with guard_memory()
2661 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2662 address base = stack_red_zone_base() - stack_red_zone_size();
2663
2664 guarantee(base < stack_base(), "Error calculating stack red zone");
2665 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2666
2667 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2668 warning("Attempt to guard stack red zone failed.");
2669 }
2670 }
2671
2672 void JavaThread::disable_stack_red_zone() {
2673 // The base notation is from the stacks point of view, growing downward.
2674 // We need to adjust it to work correctly with guard_memory()
2675 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2676 address base = stack_red_zone_base() - stack_red_zone_size();
2677 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2678 warning("Attempt to unguard stack red zone failed.");
2679 }
2680 }
2681
2682 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2683 // ignore is there is no stack
2684 if (!has_last_Java_frame()) return;
2685 // traverse the stack frames. Starts from top frame.
2686 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2687 frame* fr = fst.current();
2688 f(fr, fst.register_map());
2689 }
2690 }
2691
2692
2693 #ifndef PRODUCT
2694 // Deoptimization
2695 // Function for testing deoptimization
2696 void JavaThread::deoptimize() {
2697 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2698 StackFrameStream fst(this, UseBiasedLocking);
2699 bool deopt = false; // Dump stack only if a deopt actually happens.
2700 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2701 // Iterate over all frames in the thread and deoptimize
2702 for (; !fst.is_done(); fst.next()) {
2703 if (fst.current()->can_be_deoptimized()) {
2704
2705 if (only_at) {
2706 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2707 // consists of comma or carriage return separated numbers so
2708 // search for the current bci in that string.
2709 address pc = fst.current()->pc();
2710 nmethod* nm = (nmethod*) fst.current()->cb();
2711 ScopeDesc* sd = nm->scope_desc_at(pc);
2712 char buffer[8];
2713 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2714 size_t len = strlen(buffer);
2715 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2716 while (found != NULL) {
2717 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2718 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2719 // Check that the bci found is bracketed by terminators.
2720 break;
2721 }
2722 found = strstr(found + 1, buffer);
2723 }
2724 if (!found) {
2725 continue;
2726 }
2727 }
2728
2729 if (DebugDeoptimization && !deopt) {
2730 deopt = true; // One-time only print before deopt
2731 tty->print_cr("[BEFORE Deoptimization]");
2732 trace_frames();
2733 trace_stack();
2734 }
2735 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2736 }
2737 }
2738
2739 if (DebugDeoptimization && deopt) {
2740 tty->print_cr("[AFTER Deoptimization]");
2741 trace_frames();
2742 }
2743 }
2744
2745
2746 // Make zombies
2747 void JavaThread::make_zombies() {
2748 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2749 if (fst.current()->can_be_deoptimized()) {
2750 // it is a Java nmethod
2751 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2752 nm->make_not_entrant();
2753 }
2754 }
2755 }
2756 #endif // PRODUCT
2757
2758
2759 void JavaThread::deoptimized_wrt_marked_nmethods() {
2760 if (!has_last_Java_frame()) return;
2761 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2762 StackFrameStream fst(this, UseBiasedLocking);
2763 for (; !fst.is_done(); fst.next()) {
2764 if (fst.current()->should_be_deoptimized()) {
2765 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2766 }
2767 }
2768 }
2769
2770
2771 // If the caller is a NamedThread, then remember, in the current scope,
2772 // the given JavaThread in its _processed_thread field.
2773 class RememberProcessedThread: public StackObj {
2774 NamedThread* _cur_thr;
2775 public:
2776 RememberProcessedThread(JavaThread* jthr) {
2777 Thread* thread = Thread::current();
2778 if (thread->is_Named_thread()) {
2779 _cur_thr = (NamedThread *)thread;
2780 _cur_thr->set_processed_thread(jthr);
2781 } else {
2782 _cur_thr = NULL;
2783 }
2784 }
2785
2786 ~RememberProcessedThread() {
2787 if (_cur_thr) {
2788 _cur_thr->set_processed_thread(NULL);
2789 }
2790 }
2791 };
2792
2793 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2794 // Verify that the deferred card marks have been flushed.
2795 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2796
2797 // Traverse the GCHandles
2798 Thread::oops_do(f, cf);
2799
2800 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2801
2802 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2803 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2804
2805 if (has_last_Java_frame()) {
2806 // Record JavaThread to GC thread
2807 RememberProcessedThread rpt(this);
2808
2809 // Traverse the privileged stack
2810 if (_privileged_stack_top != NULL) {
2811 _privileged_stack_top->oops_do(f);
2812 }
2813
2814 // traverse the registered growable array
2815 if (_array_for_gc != NULL) {
2816 for (int index = 0; index < _array_for_gc->length(); index++) {
2817 f->do_oop(_array_for_gc->adr_at(index));
2818 }
2819 }
2820
2821 // Traverse the monitor chunks
2822 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2823 chunk->oops_do(f);
2824 }
2825
2826 // Traverse the execution stack
2827 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2828 fst.current()->oops_do(f, cf, fst.register_map());
2829 }
2830 }
2831
2832 // callee_target is never live across a gc point so NULL it here should
2833 // it still contain a methdOop.
2834
2835 set_callee_target(NULL);
2836
2837 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2838 // If we have deferred set_locals there might be oops waiting to be
2839 // written
2840 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2841 if (list != NULL) {
2842 for (int i = 0; i < list->length(); i++) {
2843 list->at(i)->oops_do(f);
2844 }
2845 }
2846
2847 // Traverse instance variables at the end since the GC may be moving things
2848 // around using this function
2849 f->do_oop((oop*) &_threadObj);
2850 f->do_oop((oop*) &_vm_result);
2851 f->do_oop((oop*) &_exception_oop);
2852 f->do_oop((oop*) &_pending_async_exception);
2853
2854 if (jvmti_thread_state() != NULL) {
2855 jvmti_thread_state()->oops_do(f);
2856 }
2857 }
2858
2859 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2860 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2861 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2862
2863 if (has_last_Java_frame()) {
2864 // Traverse the execution stack
2865 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2866 fst.current()->nmethods_do(cf);
2867 }
2868 }
2869 }
2870
2871 void JavaThread::metadata_do(void f(Metadata*)) {
2872 if (has_last_Java_frame()) {
2873 // Traverse the execution stack to call f() on the methods in the stack
2874 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2875 fst.current()->metadata_do(f);
2876 }
2877 } else if (is_Compiler_thread()) {
2878 // need to walk ciMetadata in current compile tasks to keep alive.
2879 CompilerThread* ct = (CompilerThread*)this;
2880 if (ct->env() != NULL) {
2881 ct->env()->metadata_do(f);
2882 }
2883 CompileTask* task = ct->task();
2884 if (task != NULL) {
2885 task->metadata_do(f);
2886 }
2887 }
2888 }
2889
2890 // Printing
2891 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2892 switch (_thread_state) {
2893 case _thread_uninitialized: return "_thread_uninitialized";
2894 case _thread_new: return "_thread_new";
2895 case _thread_new_trans: return "_thread_new_trans";
2896 case _thread_in_native: return "_thread_in_native";
2897 case _thread_in_native_trans: return "_thread_in_native_trans";
2898 case _thread_in_vm: return "_thread_in_vm";
2899 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2900 case _thread_in_Java: return "_thread_in_Java";
2901 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2902 case _thread_blocked: return "_thread_blocked";
2903 case _thread_blocked_trans: return "_thread_blocked_trans";
2904 default: return "unknown thread state";
2905 }
2906 }
2907
2908 #ifndef PRODUCT
2909 void JavaThread::print_thread_state_on(outputStream *st) const {
2910 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2911 };
2912 void JavaThread::print_thread_state() const {
2913 print_thread_state_on(tty);
2914 }
2915 #endif // PRODUCT
2916
2917 // Called by Threads::print() for VM_PrintThreads operation
2918 void JavaThread::print_on(outputStream *st) const {
2919 st->print_raw("\"");
2920 st->print_raw(get_thread_name());
2921 st->print_raw("\" ");
2922 oop thread_oop = threadObj();
2923 if (thread_oop != NULL) {
2924 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2925 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2926 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2927 }
2928 Thread::print_on(st);
2929 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2930 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2931 if (thread_oop != NULL) {
2932 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2933 }
2934 #ifndef PRODUCT
2935 print_thread_state_on(st);
2936 _safepoint_state->print_on(st);
2937 #endif // PRODUCT
2938 if (is_Compiler_thread()) {
2939 CompileTask *task = ((CompilerThread*)this)->task();
2940 if (task != NULL) {
2941 st->print(" Compiling: ");
2942 task->print(st, NULL, true, false);
2943 } else {
2944 st->print(" No compile task");
2945 }
2946 st->cr();
2947 }
2948 }
2949
2950 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2951 st->print("%s", get_thread_name_string(buf, buflen));
2952 }
2953
2954 // Called by fatal error handler. The difference between this and
2955 // JavaThread::print() is that we can't grab lock or allocate memory.
2956 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2957 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2958 oop thread_obj = threadObj();
2959 if (thread_obj != NULL) {
2960 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2961 }
2962 st->print(" [");
2963 st->print("%s", _get_thread_state_name(_thread_state));
2964 if (osthread()) {
2965 st->print(", id=%d", osthread()->thread_id());
2966 }
2967 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2968 p2i(stack_end()), p2i(stack_base()));
2969 st->print("]");
2970
2971 ThreadsSMRSupport::print_info_on(this, st);
2972 return;
2973 }
2974
2975 // Verification
2976
2977 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2978
2979 void JavaThread::verify() {
2980 // Verify oops in the thread.
2981 oops_do(&VerifyOopClosure::verify_oop, NULL);
2982
2983 // Verify the stack frames.
2984 frames_do(frame_verify);
2985 }
2986
2987 // CR 6300358 (sub-CR 2137150)
2988 // Most callers of this method assume that it can't return NULL but a
2989 // thread may not have a name whilst it is in the process of attaching to
2990 // the VM - see CR 6412693, and there are places where a JavaThread can be
2991 // seen prior to having it's threadObj set (eg JNI attaching threads and
2992 // if vm exit occurs during initialization). These cases can all be accounted
2993 // for such that this method never returns NULL.
2994 const char* JavaThread::get_thread_name() const {
2995 #ifdef ASSERT
2996 // early safepoints can hit while current thread does not yet have TLS
2997 if (!SafepointSynchronize::is_at_safepoint()) {
2998 Thread *cur = Thread::current();
2999 if (!(cur->is_Java_thread() && cur == this)) {
3000 // Current JavaThreads are allowed to get their own name without
3001 // the Threads_lock.
3002 assert_locked_or_safepoint(Threads_lock);
3003 }
3004 }
3005 #endif // ASSERT
3006 return get_thread_name_string();
3007 }
3008
3009 // Returns a non-NULL representation of this thread's name, or a suitable
3010 // descriptive string if there is no set name
3011 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3012 const char* name_str;
3013 oop thread_obj = threadObj();
3014 if (thread_obj != NULL) {
3015 oop name = java_lang_Thread::name(thread_obj);
3016 if (name != NULL) {
3017 if (buf == NULL) {
3018 name_str = java_lang_String::as_utf8_string(name);
3019 } else {
3020 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3021 }
3022 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3023 name_str = "<no-name - thread is attaching>";
3024 } else {
3025 name_str = Thread::name();
3026 }
3027 } else {
3028 name_str = Thread::name();
3029 }
3030 assert(name_str != NULL, "unexpected NULL thread name");
3031 return name_str;
3032 }
3033
3034
3035 const char* JavaThread::get_threadgroup_name() const {
3036 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3037 oop thread_obj = threadObj();
3038 if (thread_obj != NULL) {
3039 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3040 if (thread_group != NULL) {
3041 // ThreadGroup.name can be null
3042 return java_lang_ThreadGroup::name(thread_group);
3043 }
3044 }
3045 return NULL;
3046 }
3047
3048 const char* JavaThread::get_parent_name() const {
3049 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3050 oop thread_obj = threadObj();
3051 if (thread_obj != NULL) {
3052 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3053 if (thread_group != NULL) {
3054 oop parent = java_lang_ThreadGroup::parent(thread_group);
3055 if (parent != NULL) {
3056 // ThreadGroup.name can be null
3057 return java_lang_ThreadGroup::name(parent);
3058 }
3059 }
3060 }
3061 return NULL;
3062 }
3063
3064 ThreadPriority JavaThread::java_priority() const {
3065 oop thr_oop = threadObj();
3066 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3067 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3068 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3069 return priority;
3070 }
3071
3072 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3073
3074 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3075 // Link Java Thread object <-> C++ Thread
3076
3077 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3078 // and put it into a new Handle. The Handle "thread_oop" can then
3079 // be used to pass the C++ thread object to other methods.
3080
3081 // Set the Java level thread object (jthread) field of the
3082 // new thread (a JavaThread *) to C++ thread object using the
3083 // "thread_oop" handle.
3084
3085 // Set the thread field (a JavaThread *) of the
3086 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3087
3088 Handle thread_oop(Thread::current(),
3089 JNIHandles::resolve_non_null(jni_thread));
3090 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3091 "must be initialized");
3092 set_threadObj(thread_oop());
3093 java_lang_Thread::set_thread(thread_oop(), this);
3094
3095 if (prio == NoPriority) {
3096 prio = java_lang_Thread::priority(thread_oop());
3097 assert(prio != NoPriority, "A valid priority should be present");
3098 }
3099
3100 // Push the Java priority down to the native thread; needs Threads_lock
3101 Thread::set_priority(this, prio);
3102
3103 // Add the new thread to the Threads list and set it in motion.
3104 // We must have threads lock in order to call Threads::add.
3105 // It is crucial that we do not block before the thread is
3106 // added to the Threads list for if a GC happens, then the java_thread oop
3107 // will not be visited by GC.
3108 Threads::add(this);
3109 }
3110
3111 oop JavaThread::current_park_blocker() {
3112 // Support for JSR-166 locks
3113 oop thread_oop = threadObj();
3114 if (thread_oop != NULL &&
3115 JDK_Version::current().supports_thread_park_blocker()) {
3116 return java_lang_Thread::park_blocker(thread_oop);
3117 }
3118 return NULL;
3119 }
3120
3121
3122 void JavaThread::print_stack_on(outputStream* st) {
3123 if (!has_last_Java_frame()) return;
3124 ResourceMark rm;
3125 HandleMark hm;
3126
3127 RegisterMap reg_map(this);
3128 vframe* start_vf = last_java_vframe(®_map);
3129 int count = 0;
3130 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3131 if (f->is_java_frame()) {
3132 javaVFrame* jvf = javaVFrame::cast(f);
3133 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3134
3135 // Print out lock information
3136 if (JavaMonitorsInStackTrace) {
3137 jvf->print_lock_info_on(st, count);
3138 }
3139 } else {
3140 // Ignore non-Java frames
3141 }
3142
3143 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3144 count++;
3145 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3146 }
3147 }
3148
3149
3150 // JVMTI PopFrame support
3151 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3152 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3153 if (in_bytes(size_in_bytes) != 0) {
3154 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3155 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3156 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3157 }
3158 }
3159
3160 void* JavaThread::popframe_preserved_args() {
3161 return _popframe_preserved_args;
3162 }
3163
3164 ByteSize JavaThread::popframe_preserved_args_size() {
3165 return in_ByteSize(_popframe_preserved_args_size);
3166 }
3167
3168 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3169 int sz = in_bytes(popframe_preserved_args_size());
3170 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3171 return in_WordSize(sz / wordSize);
3172 }
3173
3174 void JavaThread::popframe_free_preserved_args() {
3175 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3176 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3177 _popframe_preserved_args = NULL;
3178 _popframe_preserved_args_size = 0;
3179 }
3180
3181 #ifndef PRODUCT
3182
3183 void JavaThread::trace_frames() {
3184 tty->print_cr("[Describe stack]");
3185 int frame_no = 1;
3186 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3187 tty->print(" %d. ", frame_no++);
3188 fst.current()->print_value_on(tty, this);
3189 tty->cr();
3190 }
3191 }
3192
3193 class PrintAndVerifyOopClosure: public OopClosure {
3194 protected:
3195 template <class T> inline void do_oop_work(T* p) {
3196 oop obj = RawAccess<>::oop_load(p);
3197 if (obj == NULL) return;
3198 tty->print(INTPTR_FORMAT ": ", p2i(p));
3199 if (oopDesc::is_oop_or_null(obj)) {
3200 if (obj->is_objArray()) {
3201 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3202 } else {
3203 obj->print();
3204 }
3205 } else {
3206 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3207 }
3208 tty->cr();
3209 }
3210 public:
3211 virtual void do_oop(oop* p) { do_oop_work(p); }
3212 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3213 };
3214
3215
3216 static void oops_print(frame* f, const RegisterMap *map) {
3217 PrintAndVerifyOopClosure print;
3218 f->print_value();
3219 f->oops_do(&print, NULL, (RegisterMap*)map);
3220 }
3221
3222 // Print our all the locations that contain oops and whether they are
3223 // valid or not. This useful when trying to find the oldest frame
3224 // where an oop has gone bad since the frame walk is from youngest to
3225 // oldest.
3226 void JavaThread::trace_oops() {
3227 tty->print_cr("[Trace oops]");
3228 frames_do(oops_print);
3229 }
3230
3231
3232 #ifdef ASSERT
3233 // Print or validate the layout of stack frames
3234 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3235 ResourceMark rm;
3236 PRESERVE_EXCEPTION_MARK;
3237 FrameValues values;
3238 int frame_no = 0;
3239 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3240 fst.current()->describe(values, ++frame_no);
3241 if (depth == frame_no) break;
3242 }
3243 if (validate_only) {
3244 values.validate();
3245 } else {
3246 tty->print_cr("[Describe stack layout]");
3247 values.print(this);
3248 }
3249 }
3250 #endif
3251
3252 void JavaThread::trace_stack_from(vframe* start_vf) {
3253 ResourceMark rm;
3254 int vframe_no = 1;
3255 for (vframe* f = start_vf; f; f = f->sender()) {
3256 if (f->is_java_frame()) {
3257 javaVFrame::cast(f)->print_activation(vframe_no++);
3258 } else {
3259 f->print();
3260 }
3261 if (vframe_no > StackPrintLimit) {
3262 tty->print_cr("...<more frames>...");
3263 return;
3264 }
3265 }
3266 }
3267
3268
3269 void JavaThread::trace_stack() {
3270 if (!has_last_Java_frame()) return;
3271 ResourceMark rm;
3272 HandleMark hm;
3273 RegisterMap reg_map(this);
3274 trace_stack_from(last_java_vframe(®_map));
3275 }
3276
3277
3278 #endif // PRODUCT
3279
3280
3281 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3282 assert(reg_map != NULL, "a map must be given");
3283 frame f = last_frame();
3284 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3285 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3286 }
3287 return NULL;
3288 }
3289
3290
3291 Klass* JavaThread::security_get_caller_class(int depth) {
3292 vframeStream vfst(this);
3293 vfst.security_get_caller_frame(depth);
3294 if (!vfst.at_end()) {
3295 return vfst.method()->method_holder();
3296 }
3297 return NULL;
3298 }
3299
3300 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3301 assert(thread->is_Compiler_thread(), "must be compiler thread");
3302 CompileBroker::compiler_thread_loop();
3303 }
3304
3305 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3306 NMethodSweeper::sweeper_loop();
3307 }
3308
3309 // Create a CompilerThread
3310 CompilerThread::CompilerThread(CompileQueue* queue,
3311 CompilerCounters* counters)
3312 : JavaThread(&compiler_thread_entry) {
3313 _env = NULL;
3314 _log = NULL;
3315 _task = NULL;
3316 _queue = queue;
3317 _counters = counters;
3318 _buffer_blob = NULL;
3319 _compiler = NULL;
3320
3321 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3322 resource_area()->bias_to(mtCompiler);
3323
3324 #ifndef PRODUCT
3325 _ideal_graph_printer = NULL;
3326 #endif
3327 }
3328
3329 CompilerThread::~CompilerThread() {
3330 // Delete objects which were allocated on heap.
3331 delete _counters;
3332 }
3333
3334 bool CompilerThread::can_call_java() const {
3335 return _compiler != NULL && _compiler->is_jvmci();
3336 }
3337
3338 // Create sweeper thread
3339 CodeCacheSweeperThread::CodeCacheSweeperThread()
3340 : JavaThread(&sweeper_thread_entry) {
3341 _scanned_compiled_method = NULL;
3342 }
3343
3344 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3345 JavaThread::oops_do(f, cf);
3346 if (_scanned_compiled_method != NULL && cf != NULL) {
3347 // Safepoints can occur when the sweeper is scanning an nmethod so
3348 // process it here to make sure it isn't unloaded in the middle of
3349 // a scan.
3350 cf->do_code_blob(_scanned_compiled_method);
3351 }
3352 }
3353
3354 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3355 JavaThread::nmethods_do(cf);
3356 if (_scanned_compiled_method != NULL && cf != NULL) {
3357 // Safepoints can occur when the sweeper is scanning an nmethod so
3358 // process it here to make sure it isn't unloaded in the middle of
3359 // a scan.
3360 cf->do_code_blob(_scanned_compiled_method);
3361 }
3362 }
3363
3364
3365 // ======= Threads ========
3366
3367 // The Threads class links together all active threads, and provides
3368 // operations over all threads. It is protected by the Threads_lock,
3369 // which is also used in other global contexts like safepointing.
3370 // ThreadsListHandles are used to safely perform operations on one
3371 // or more threads without the risk of the thread exiting during the
3372 // operation.
3373 //
3374 // Note: The Threads_lock is currently more widely used than we
3375 // would like. We are actively migrating Threads_lock uses to other
3376 // mechanisms in order to reduce Threads_lock contention.
3377
3378 JavaThread* Threads::_thread_list = NULL;
3379 int Threads::_number_of_threads = 0;
3380 int Threads::_number_of_non_daemon_threads = 0;
3381 int Threads::_return_code = 0;
3382 int Threads::_thread_claim_parity = 0;
3383 size_t JavaThread::_stack_size_at_create = 0;
3384
3385 #ifdef ASSERT
3386 bool Threads::_vm_complete = false;
3387 #endif
3388
3389 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3390 Prefetch::read((void*)addr, prefetch_interval);
3391 return *addr;
3392 }
3393
3394 // Possibly the ugliest for loop the world has seen. C++ does not allow
3395 // multiple types in the declaration section of the for loop. In this case
3396 // we are only dealing with pointers and hence can cast them. It looks ugly
3397 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3398 #define DO_JAVA_THREADS(LIST, X) \
3399 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3400 *MACRO_list = (JavaThread*)(LIST), \
3401 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3402 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3403 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3404 MACRO_current_p != MACRO_end; \
3405 MACRO_current_p++, \
3406 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3407
3408 // All JavaThreads
3409 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3410
3411 // All non-JavaThreads (i.e., every non-JavaThread in the system).
3412 void Threads::non_java_threads_do(ThreadClosure* tc) {
3413 // Someday we could have a table or list of all non-JavaThreads.
3414 // For now, just manually iterate through them.
3415 tc->do_thread(VMThread::vm_thread());
3416 if (Universe::heap() != NULL) {
3417 Universe::heap()->gc_threads_do(tc);
3418 }
3419 WatcherThread *wt = WatcherThread::watcher_thread();
3420 // Strictly speaking, the following NULL check isn't sufficient to make sure
3421 // the data for WatcherThread is still valid upon being examined. However,
3422 // considering that WatchThread terminates when the VM is on the way to
3423 // exit at safepoint, the chance of the above is extremely small. The right
3424 // way to prevent termination of WatcherThread would be to acquire
3425 // Terminator_lock, but we can't do that without violating the lock rank
3426 // checking in some cases.
3427 if (wt != NULL) {
3428 tc->do_thread(wt);
3429 }
3430
3431 #if INCLUDE_JFR
3432 Thread* sampler_thread = Jfr::sampler_thread();
3433 if (sampler_thread != NULL) {
3434 tc->do_thread(sampler_thread);
3435 }
3436
3437 #endif
3438
3439 // If CompilerThreads ever become non-JavaThreads, add them here
3440 }
3441
3442 // All JavaThreads
3443 void Threads::java_threads_do(ThreadClosure* tc) {
3444 assert_locked_or_safepoint(Threads_lock);
3445 // ALL_JAVA_THREADS iterates through all JavaThreads.
3446 ALL_JAVA_THREADS(p) {
3447 tc->do_thread(p);
3448 }
3449 }
3450
3451 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3452 assert_locked_or_safepoint(Threads_lock);
3453 java_threads_do(tc);
3454 tc->do_thread(VMThread::vm_thread());
3455 }
3456
3457 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3458 void Threads::threads_do(ThreadClosure* tc) {
3459 assert_locked_or_safepoint(Threads_lock);
3460 java_threads_do(tc);
3461 non_java_threads_do(tc);
3462 }
3463
3464 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3465 int cp = Threads::thread_claim_parity();
3466 ALL_JAVA_THREADS(p) {
3467 if (p->claim_oops_do(is_par, cp)) {
3468 tc->do_thread(p);
3469 }
3470 }
3471 VMThread* vmt = VMThread::vm_thread();
3472 if (vmt->claim_oops_do(is_par, cp)) {
3473 tc->do_thread(vmt);
3474 }
3475 }
3476
3477 // The system initialization in the library has three phases.
3478 //
3479 // Phase 1: java.lang.System class initialization
3480 // java.lang.System is a primordial class loaded and initialized
3481 // by the VM early during startup. java.lang.System.<clinit>
3482 // only does registerNatives and keeps the rest of the class
3483 // initialization work later until thread initialization completes.
3484 //
3485 // System.initPhase1 initializes the system properties, the static
3486 // fields in, out, and err. Set up java signal handlers, OS-specific
3487 // system settings, and thread group of the main thread.
3488 static void call_initPhase1(TRAPS) {
3489 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3490 JavaValue result(T_VOID);
3491 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3492 vmSymbols::void_method_signature(), CHECK);
3493 }
3494
3495 // Phase 2. Module system initialization
3496 // This will initialize the module system. Only java.base classes
3497 // can be loaded until phase 2 completes.
3498 //
3499 // Call System.initPhase2 after the compiler initialization and jsr292
3500 // classes get initialized because module initialization runs a lot of java
3501 // code, that for performance reasons, should be compiled. Also, this will
3502 // enable the startup code to use lambda and other language features in this
3503 // phase and onward.
3504 //
3505 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3506 static void call_initPhase2(TRAPS) {
3507 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3508
3509 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3510
3511 JavaValue result(T_INT);
3512 JavaCallArguments args;
3513 args.push_int(DisplayVMOutputToStderr);
3514 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3515 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3516 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3517 if (result.get_jint() != JNI_OK) {
3518 vm_exit_during_initialization(); // no message or exception
3519 }
3520
3521 universe_post_module_init();
3522 }
3523
3524 // Phase 3. final setup - set security manager, system class loader and TCCL
3525 //
3526 // This will instantiate and set the security manager, set the system class
3527 // loader as well as the thread context class loader. The security manager
3528 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3529 // other modules or the application's classpath.
3530 static void call_initPhase3(TRAPS) {
3531 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3532 JavaValue result(T_VOID);
3533 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3534 vmSymbols::void_method_signature(), CHECK);
3535 }
3536
3537 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3538 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3539
3540 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3541 create_vm_init_libraries();
3542 }
3543
3544 initialize_class(vmSymbols::java_lang_String(), CHECK);
3545
3546 // Inject CompactStrings value after the static initializers for String ran.
3547 java_lang_String::set_compact_strings(CompactStrings);
3548
3549 // Initialize java_lang.System (needed before creating the thread)
3550 initialize_class(vmSymbols::java_lang_System(), CHECK);
3551 // The VM creates & returns objects of this class. Make sure it's initialized.
3552 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3553 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3554 Handle thread_group = create_initial_thread_group(CHECK);
3555 Universe::set_main_thread_group(thread_group());
3556 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3557 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3558 main_thread->set_threadObj(thread_object);
3559 // Set thread status to running since main thread has
3560 // been started and running.
3561 java_lang_Thread::set_thread_status(thread_object,
3562 java_lang_Thread::RUNNABLE);
3563
3564 // The VM creates objects of this class.
3565 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3566
3567 // The VM preresolves methods to these classes. Make sure that they get initialized
3568 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3569 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3570
3571 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3572 call_initPhase1(CHECK);
3573
3574 // get the Java runtime name after java.lang.System is initialized
3575 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3576 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3577
3578 // an instance of OutOfMemory exception has been allocated earlier
3579 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3580 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3581 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3582 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3583 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3584 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3585 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3586 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3587 }
3588
3589 void Threads::initialize_jsr292_core_classes(TRAPS) {
3590 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3591
3592 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3593 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3594 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3595 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3596 }
3597
3598 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3599 extern void JDK_Version_init();
3600
3601 // Preinitialize version info.
3602 VM_Version::early_initialize();
3603
3604 // Check version
3605 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3606
3607 // Initialize library-based TLS
3608 ThreadLocalStorage::init();
3609
3610 // Initialize the output stream module
3611 ostream_init();
3612
3613 // Process java launcher properties.
3614 Arguments::process_sun_java_launcher_properties(args);
3615
3616 // Initialize the os module
3617 os::init();
3618
3619 // Record VM creation timing statistics
3620 TraceVmCreationTime create_vm_timer;
3621 create_vm_timer.start();
3622
3623 // Initialize system properties.
3624 Arguments::init_system_properties();
3625
3626 // So that JDK version can be used as a discriminator when parsing arguments
3627 JDK_Version_init();
3628
3629 // Update/Initialize System properties after JDK version number is known
3630 Arguments::init_version_specific_system_properties();
3631
3632 // Make sure to initialize log configuration *before* parsing arguments
3633 LogConfiguration::initialize(create_vm_timer.begin_time());
3634
3635 // Parse arguments
3636 // Note: this internally calls os::init_container_support()
3637 jint parse_result = Arguments::parse(args);
3638 if (parse_result != JNI_OK) return parse_result;
3639
3640 os::init_before_ergo();
3641
3642 jint ergo_result = Arguments::apply_ergo();
3643 if (ergo_result != JNI_OK) return ergo_result;
3644
3645 // Final check of all ranges after ergonomics which may change values.
3646 if (!JVMFlagRangeList::check_ranges()) {
3647 return JNI_EINVAL;
3648 }
3649
3650 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3651 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3652 if (!constraint_result) {
3653 return JNI_EINVAL;
3654 }
3655
3656 JVMFlagWriteableList::mark_startup();
3657
3658 if (PauseAtStartup) {
3659 os::pause();
3660 }
3661
3662 HOTSPOT_VM_INIT_BEGIN();
3663
3664 // Timing (must come after argument parsing)
3665 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3666
3667 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3668 // Initialize assert poison page mechanism.
3669 if (ShowRegistersOnAssert) {
3670 initialize_assert_poison();
3671 }
3672 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3673
3674 // Initialize the os module after parsing the args
3675 jint os_init_2_result = os::init_2();
3676 if (os_init_2_result != JNI_OK) return os_init_2_result;
3677
3678 SafepointMechanism::initialize();
3679
3680 jint adjust_after_os_result = Arguments::adjust_after_os();
3681 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3682
3683 // Initialize output stream logging
3684 ostream_init_log();
3685
3686 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3687 // Must be before create_vm_init_agents()
3688 if (Arguments::init_libraries_at_startup()) {
3689 convert_vm_init_libraries_to_agents();
3690 }
3691
3692 // Launch -agentlib/-agentpath and converted -Xrun agents
3693 if (Arguments::init_agents_at_startup()) {
3694 create_vm_init_agents();
3695 }
3696
3697 // Initialize Threads state
3698 _thread_list = NULL;
3699 _number_of_threads = 0;
3700 _number_of_non_daemon_threads = 0;
3701
3702 // Initialize global data structures and create system classes in heap
3703 vm_init_globals();
3704
3705 #if INCLUDE_JVMCI
3706 if (JVMCICounterSize > 0) {
3707 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3708 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3709 } else {
3710 JavaThread::_jvmci_old_thread_counters = NULL;
3711 }
3712 #endif // INCLUDE_JVMCI
3713
3714 // Attach the main thread to this os thread
3715 JavaThread* main_thread = new JavaThread();
3716 main_thread->set_thread_state(_thread_in_vm);
3717 main_thread->initialize_thread_current();
3718 // must do this before set_active_handles
3719 main_thread->record_stack_base_and_size();
3720 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3721
3722 if (!main_thread->set_as_starting_thread()) {
3723 vm_shutdown_during_initialization(
3724 "Failed necessary internal allocation. Out of swap space");
3725 main_thread->smr_delete();
3726 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3727 return JNI_ENOMEM;
3728 }
3729
3730 // Enable guard page *after* os::create_main_thread(), otherwise it would
3731 // crash Linux VM, see notes in os_linux.cpp.
3732 main_thread->create_stack_guard_pages();
3733
3734 // Initialize Java-Level synchronization subsystem
3735 ObjectMonitor::Initialize();
3736
3737 // Initialize global modules
3738 jint status = init_globals();
3739 if (status != JNI_OK) {
3740 main_thread->smr_delete();
3741 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3742 return status;
3743 }
3744
3745 JFR_ONLY(Jfr::on_vm_init();)
3746
3747 // Should be done after the heap is fully created
3748 main_thread->cache_global_variables();
3749
3750 HandleMark hm;
3751
3752 { MutexLocker mu(Threads_lock);
3753 Threads::add(main_thread);
3754 }
3755
3756 // Any JVMTI raw monitors entered in onload will transition into
3757 // real raw monitor. VM is setup enough here for raw monitor enter.
3758 JvmtiExport::transition_pending_onload_raw_monitors();
3759
3760 // Create the VMThread
3761 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3762
3763 VMThread::create();
3764 Thread* vmthread = VMThread::vm_thread();
3765
3766 if (!os::create_thread(vmthread, os::vm_thread)) {
3767 vm_exit_during_initialization("Cannot create VM thread. "
3768 "Out of system resources.");
3769 }
3770
3771 // Wait for the VM thread to become ready, and VMThread::run to initialize
3772 // Monitors can have spurious returns, must always check another state flag
3773 {
3774 MutexLocker ml(Notify_lock);
3775 os::start_thread(vmthread);
3776 while (vmthread->active_handles() == NULL) {
3777 Notify_lock->wait();
3778 }
3779 }
3780 }
3781
3782 assert(Universe::is_fully_initialized(), "not initialized");
3783 if (VerifyDuringStartup) {
3784 // Make sure we're starting with a clean slate.
3785 VM_Verify verify_op;
3786 VMThread::execute(&verify_op);
3787 }
3788
3789 Thread* THREAD = Thread::current();
3790
3791 // Always call even when there are not JVMTI environments yet, since environments
3792 // may be attached late and JVMTI must track phases of VM execution
3793 JvmtiExport::enter_early_start_phase();
3794
3795 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3796 JvmtiExport::post_early_vm_start();
3797
3798 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3799
3800 // We need this for ClassDataSharing - the initial vm.info property is set
3801 // with the default value of CDS "sharing" which may be reset through
3802 // command line options.
3803 reset_vm_info_property(CHECK_JNI_ERR);
3804
3805 quicken_jni_functions();
3806
3807 // No more stub generation allowed after that point.
3808 StubCodeDesc::freeze();
3809
3810 // Set flag that basic initialization has completed. Used by exceptions and various
3811 // debug stuff, that does not work until all basic classes have been initialized.
3812 set_init_completed();
3813
3814 LogConfiguration::post_initialize();
3815 Metaspace::post_initialize();
3816
3817 HOTSPOT_VM_INIT_END();
3818
3819 // record VM initialization completion time
3820 #if INCLUDE_MANAGEMENT
3821 Management::record_vm_init_completed();
3822 #endif // INCLUDE_MANAGEMENT
3823
3824 // Signal Dispatcher needs to be started before VMInit event is posted
3825 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3826
3827 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3828 if (!DisableAttachMechanism) {
3829 AttachListener::vm_start();
3830 if (StartAttachListener || AttachListener::init_at_startup()) {
3831 AttachListener::init();
3832 }
3833 }
3834
3835 // Launch -Xrun agents
3836 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3837 // back-end can launch with -Xdebug -Xrunjdwp.
3838 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3839 create_vm_init_libraries();
3840 }
3841
3842 if (CleanChunkPoolAsync) {
3843 Chunk::start_chunk_pool_cleaner_task();
3844 }
3845
3846 // initialize compiler(s)
3847 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3848 #if INCLUDE_JVMCI
3849 bool force_JVMCI_intialization = false;
3850 if (EnableJVMCI) {
3851 // Initialize JVMCI eagerly when it is explicitly requested.
3852 // Or when JVMCIPrintProperties is enabled.
3853 // The JVMCI Java initialization code will read this flag and
3854 // do the printing if it's set.
3855 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3856
3857 if (!force_JVMCI_intialization) {
3858 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3859 // compilations via JVMCI will not actually block until JVMCI is initialized.
3860 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3861 }
3862 }
3863 #endif
3864 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3865 // Postpone completion of compiler initialization to after JVMCI
3866 // is initialized to avoid timeouts of blocking compilations.
3867 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3868 CompileBroker::compilation_init_phase2();
3869 }
3870 #endif
3871
3872 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3873 // It is done after compilers are initialized, because otherwise compilations of
3874 // signature polymorphic MH intrinsics can be missed
3875 // (see SystemDictionary::find_method_handle_intrinsic).
3876 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3877
3878 // This will initialize the module system. Only java.base classes can be
3879 // loaded until phase 2 completes
3880 call_initPhase2(CHECK_JNI_ERR);
3881
3882 // Always call even when there are not JVMTI environments yet, since environments
3883 // may be attached late and JVMTI must track phases of VM execution
3884 JvmtiExport::enter_start_phase();
3885
3886 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3887 JvmtiExport::post_vm_start();
3888
3889 // Final system initialization including security manager and system class loader
3890 call_initPhase3(CHECK_JNI_ERR);
3891
3892 // cache the system and platform class loaders
3893 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3894
3895 #if INCLUDE_CDS
3896 if (DumpSharedSpaces) {
3897 // capture the module path info from the ModuleEntryTable
3898 ClassLoader::initialize_module_path(THREAD);
3899 }
3900 #endif
3901
3902 #if INCLUDE_JVMCI
3903 if (force_JVMCI_intialization) {
3904 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3905 CompileBroker::compilation_init_phase2();
3906 }
3907 #endif
3908
3909 // Always call even when there are not JVMTI environments yet, since environments
3910 // may be attached late and JVMTI must track phases of VM execution
3911 JvmtiExport::enter_live_phase();
3912
3913 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3914 JvmtiExport::post_vm_initialized();
3915
3916 JFR_ONLY(Jfr::on_vm_start();)
3917
3918 #if INCLUDE_MANAGEMENT
3919 Management::initialize(THREAD);
3920
3921 if (HAS_PENDING_EXCEPTION) {
3922 // management agent fails to start possibly due to
3923 // configuration problem and is responsible for printing
3924 // stack trace if appropriate. Simply exit VM.
3925 vm_exit(1);
3926 }
3927 #endif // INCLUDE_MANAGEMENT
3928
3929 if (MemProfiling) MemProfiler::engage();
3930 StatSampler::engage();
3931 if (CheckJNICalls) JniPeriodicChecker::engage();
3932
3933 BiasedLocking::init();
3934
3935 #if INCLUDE_RTM_OPT
3936 RTMLockingCounters::init();
3937 #endif
3938
3939 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3940 call_postVMInitHook(THREAD);
3941 // The Java side of PostVMInitHook.run must deal with all
3942 // exceptions and provide means of diagnosis.
3943 if (HAS_PENDING_EXCEPTION) {
3944 CLEAR_PENDING_EXCEPTION;
3945 }
3946 }
3947
3948 {
3949 MutexLocker ml(PeriodicTask_lock);
3950 // Make sure the WatcherThread can be started by WatcherThread::start()
3951 // or by dynamic enrollment.
3952 WatcherThread::make_startable();
3953 // Start up the WatcherThread if there are any periodic tasks
3954 // NOTE: All PeriodicTasks should be registered by now. If they
3955 // aren't, late joiners might appear to start slowly (we might
3956 // take a while to process their first tick).
3957 if (PeriodicTask::num_tasks() > 0) {
3958 WatcherThread::start();
3959 }
3960 }
3961
3962 create_vm_timer.end();
3963 #ifdef ASSERT
3964 _vm_complete = true;
3965 #endif
3966
3967 if (DumpSharedSpaces) {
3968 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3969 ShouldNotReachHere();
3970 }
3971
3972 return JNI_OK;
3973 }
3974
3975 // type for the Agent_OnLoad and JVM_OnLoad entry points
3976 extern "C" {
3977 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3978 }
3979 // Find a command line agent library and return its entry point for
3980 // -agentlib: -agentpath: -Xrun
3981 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3982 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3983 const char *on_load_symbols[],
3984 size_t num_symbol_entries) {
3985 OnLoadEntry_t on_load_entry = NULL;
3986 void *library = NULL;
3987
3988 if (!agent->valid()) {
3989 char buffer[JVM_MAXPATHLEN];
3990 char ebuf[1024] = "";
3991 const char *name = agent->name();
3992 const char *msg = "Could not find agent library ";
3993
3994 // First check to see if agent is statically linked into executable
3995 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3996 library = agent->os_lib();
3997 } else if (agent->is_absolute_path()) {
3998 library = os::dll_load(name, ebuf, sizeof ebuf);
3999 if (library == NULL) {
4000 const char *sub_msg = " in absolute path, with error: ";
4001 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4002 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4003 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4004 // If we can't find the agent, exit.
4005 vm_exit_during_initialization(buf, NULL);
4006 FREE_C_HEAP_ARRAY(char, buf);
4007 }
4008 } else {
4009 // Try to load the agent from the standard dll directory
4010 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4011 name)) {
4012 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4013 }
4014 if (library == NULL) { // Try the library path directory.
4015 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4016 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4017 }
4018 if (library == NULL) {
4019 const char *sub_msg = " on the library path, with error: ";
4020 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4021
4022 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4023 strlen(ebuf) + strlen(sub_msg2) + 1;
4024 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4025 if (!agent->is_instrument_lib()) {
4026 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4027 } else {
4028 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4029 }
4030 // If we can't find the agent, exit.
4031 vm_exit_during_initialization(buf, NULL);
4032 FREE_C_HEAP_ARRAY(char, buf);
4033 }
4034 }
4035 }
4036 agent->set_os_lib(library);
4037 agent->set_valid();
4038 }
4039
4040 // Find the OnLoad function.
4041 on_load_entry =
4042 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4043 false,
4044 on_load_symbols,
4045 num_symbol_entries));
4046 return on_load_entry;
4047 }
4048
4049 // Find the JVM_OnLoad entry point
4050 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4051 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4052 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4053 }
4054
4055 // Find the Agent_OnLoad entry point
4056 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4057 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4058 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4059 }
4060
4061 // For backwards compatibility with -Xrun
4062 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4063 // treated like -agentpath:
4064 // Must be called before agent libraries are created
4065 void Threads::convert_vm_init_libraries_to_agents() {
4066 AgentLibrary* agent;
4067 AgentLibrary* next;
4068
4069 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4070 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4071 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4072
4073 // If there is an JVM_OnLoad function it will get called later,
4074 // otherwise see if there is an Agent_OnLoad
4075 if (on_load_entry == NULL) {
4076 on_load_entry = lookup_agent_on_load(agent);
4077 if (on_load_entry != NULL) {
4078 // switch it to the agent list -- so that Agent_OnLoad will be called,
4079 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4080 Arguments::convert_library_to_agent(agent);
4081 } else {
4082 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4083 }
4084 }
4085 }
4086 }
4087
4088 // Create agents for -agentlib: -agentpath: and converted -Xrun
4089 // Invokes Agent_OnLoad
4090 // Called very early -- before JavaThreads exist
4091 void Threads::create_vm_init_agents() {
4092 extern struct JavaVM_ main_vm;
4093 AgentLibrary* agent;
4094
4095 JvmtiExport::enter_onload_phase();
4096
4097 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4098 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4099
4100 if (on_load_entry != NULL) {
4101 // Invoke the Agent_OnLoad function
4102 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4103 if (err != JNI_OK) {
4104 vm_exit_during_initialization("agent library failed to init", agent->name());
4105 }
4106 } else {
4107 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4108 }
4109 }
4110 JvmtiExport::enter_primordial_phase();
4111 }
4112
4113 extern "C" {
4114 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4115 }
4116
4117 void Threads::shutdown_vm_agents() {
4118 // Send any Agent_OnUnload notifications
4119 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4120 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4121 extern struct JavaVM_ main_vm;
4122 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4123
4124 // Find the Agent_OnUnload function.
4125 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4126 os::find_agent_function(agent,
4127 false,
4128 on_unload_symbols,
4129 num_symbol_entries));
4130
4131 // Invoke the Agent_OnUnload function
4132 if (unload_entry != NULL) {
4133 JavaThread* thread = JavaThread::current();
4134 ThreadToNativeFromVM ttn(thread);
4135 HandleMark hm(thread);
4136 (*unload_entry)(&main_vm);
4137 }
4138 }
4139 }
4140
4141 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4142 // Invokes JVM_OnLoad
4143 void Threads::create_vm_init_libraries() {
4144 extern struct JavaVM_ main_vm;
4145 AgentLibrary* agent;
4146
4147 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4148 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4149
4150 if (on_load_entry != NULL) {
4151 // Invoke the JVM_OnLoad function
4152 JavaThread* thread = JavaThread::current();
4153 ThreadToNativeFromVM ttn(thread);
4154 HandleMark hm(thread);
4155 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4156 if (err != JNI_OK) {
4157 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4158 }
4159 } else {
4160 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4161 }
4162 }
4163 }
4164
4165
4166 // Last thread running calls java.lang.Shutdown.shutdown()
4167 void JavaThread::invoke_shutdown_hooks() {
4168 HandleMark hm(this);
4169
4170 // We could get here with a pending exception, if so clear it now.
4171 if (this->has_pending_exception()) {
4172 this->clear_pending_exception();
4173 }
4174
4175 EXCEPTION_MARK;
4176 Klass* shutdown_klass =
4177 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4178 THREAD);
4179 if (shutdown_klass != NULL) {
4180 // SystemDictionary::resolve_or_null will return null if there was
4181 // an exception. If we cannot load the Shutdown class, just don't
4182 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4183 // won't be run. Note that if a shutdown hook was registered,
4184 // the Shutdown class would have already been loaded
4185 // (Runtime.addShutdownHook will load it).
4186 JavaValue result(T_VOID);
4187 JavaCalls::call_static(&result,
4188 shutdown_klass,
4189 vmSymbols::shutdown_method_name(),
4190 vmSymbols::void_method_signature(),
4191 THREAD);
4192 }
4193 CLEAR_PENDING_EXCEPTION;
4194 }
4195
4196 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4197 // the program falls off the end of main(). Another VM exit path is through
4198 // vm_exit() when the program calls System.exit() to return a value or when
4199 // there is a serious error in VM. The two shutdown paths are not exactly
4200 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4201 // and VM_Exit op at VM level.
4202 //
4203 // Shutdown sequence:
4204 // + Shutdown native memory tracking if it is on
4205 // + Wait until we are the last non-daemon thread to execute
4206 // <-- every thing is still working at this moment -->
4207 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4208 // shutdown hooks
4209 // + Call before_exit(), prepare for VM exit
4210 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4211 // currently the only user of this mechanism is File.deleteOnExit())
4212 // > stop StatSampler, watcher thread, CMS threads,
4213 // post thread end and vm death events to JVMTI,
4214 // stop signal thread
4215 // + Call JavaThread::exit(), it will:
4216 // > release JNI handle blocks, remove stack guard pages
4217 // > remove this thread from Threads list
4218 // <-- no more Java code from this thread after this point -->
4219 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4220 // the compiler threads at safepoint
4221 // <-- do not use anything that could get blocked by Safepoint -->
4222 // + Disable tracing at JNI/JVM barriers
4223 // + Set _vm_exited flag for threads that are still running native code
4224 // + Delete this thread
4225 // + Call exit_globals()
4226 // > deletes tty
4227 // > deletes PerfMemory resources
4228 // + Return to caller
4229
4230 bool Threads::destroy_vm() {
4231 JavaThread* thread = JavaThread::current();
4232
4233 #ifdef ASSERT
4234 _vm_complete = false;
4235 #endif
4236 // Wait until we are the last non-daemon thread to execute
4237 { MutexLocker nu(Threads_lock);
4238 while (Threads::number_of_non_daemon_threads() > 1)
4239 // This wait should make safepoint checks, wait without a timeout,
4240 // and wait as a suspend-equivalent condition.
4241 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4242 Mutex::_as_suspend_equivalent_flag);
4243 }
4244
4245 EventShutdown e;
4246 if (e.should_commit()) {
4247 e.set_reason("No remaining non-daemon Java threads");
4248 e.commit();
4249 }
4250
4251 // Hang forever on exit if we are reporting an error.
4252 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4253 os::infinite_sleep();
4254 }
4255 os::wait_for_keypress_at_exit();
4256
4257 // run Java level shutdown hooks
4258 thread->invoke_shutdown_hooks();
4259
4260 before_exit(thread);
4261
4262 thread->exit(true);
4263
4264 // Stop VM thread.
4265 {
4266 // 4945125 The vm thread comes to a safepoint during exit.
4267 // GC vm_operations can get caught at the safepoint, and the
4268 // heap is unparseable if they are caught. Grab the Heap_lock
4269 // to prevent this. The GC vm_operations will not be able to
4270 // queue until after the vm thread is dead. After this point,
4271 // we'll never emerge out of the safepoint before the VM exits.
4272
4273 MutexLocker ml(Heap_lock);
4274
4275 VMThread::wait_for_vm_thread_exit();
4276 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4277 VMThread::destroy();
4278 }
4279
4280 // Now, all Java threads are gone except daemon threads. Daemon threads
4281 // running Java code or in VM are stopped by the Safepoint. However,
4282 // daemon threads executing native code are still running. But they
4283 // will be stopped at native=>Java/VM barriers. Note that we can't
4284 // simply kill or suspend them, as it is inherently deadlock-prone.
4285
4286 VM_Exit::set_vm_exited();
4287
4288 // Clean up ideal graph printers after the VMThread has started
4289 // the final safepoint which will block all the Compiler threads.
4290 // Note that this Thread has already logically exited so the
4291 // clean_up() function's use of a JavaThreadIteratorWithHandle
4292 // would be a problem except set_vm_exited() has remembered the
4293 // shutdown thread which is granted a policy exception.
4294 #if defined(COMPILER2) && !defined(PRODUCT)
4295 IdealGraphPrinter::clean_up();
4296 #endif
4297
4298 notify_vm_shutdown();
4299
4300 // We are after VM_Exit::set_vm_exited() so we can't call
4301 // thread->smr_delete() or we will block on the Threads_lock.
4302 // Deleting the shutdown thread here is safe because another
4303 // JavaThread cannot have an active ThreadsListHandle for
4304 // this JavaThread.
4305 delete thread;
4306
4307 #if INCLUDE_JVMCI
4308 if (JVMCICounterSize > 0) {
4309 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4310 }
4311 #endif
4312
4313 // exit_globals() will delete tty
4314 exit_globals();
4315
4316 LogConfiguration::finalize();
4317
4318 return true;
4319 }
4320
4321
4322 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4323 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4324 return is_supported_jni_version(version);
4325 }
4326
4327
4328 jboolean Threads::is_supported_jni_version(jint version) {
4329 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4330 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4331 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4332 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4333 if (version == JNI_VERSION_9) return JNI_TRUE;
4334 if (version == JNI_VERSION_10) return JNI_TRUE;
4335 return JNI_FALSE;
4336 }
4337
4338
4339 void Threads::add(JavaThread* p, bool force_daemon) {
4340 // The threads lock must be owned at this point
4341 assert_locked_or_safepoint(Threads_lock);
4342
4343 BarrierSet::barrier_set()->on_thread_attach(p);
4344
4345 p->set_next(_thread_list);
4346 _thread_list = p;
4347
4348 // Once a JavaThread is added to the Threads list, smr_delete() has
4349 // to be used to delete it. Otherwise we can just delete it directly.
4350 p->set_on_thread_list();
4351
4352 _number_of_threads++;
4353 oop threadObj = p->threadObj();
4354 bool daemon = true;
4355 // Bootstrapping problem: threadObj can be null for initial
4356 // JavaThread (or for threads attached via JNI)
4357 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4358 _number_of_non_daemon_threads++;
4359 daemon = false;
4360 }
4361
4362 ThreadService::add_thread(p, daemon);
4363
4364 // Maintain fast thread list
4365 ThreadsSMRSupport::add_thread(p);
4366
4367 // Possible GC point.
4368 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4369 }
4370
4371 void Threads::remove(JavaThread* p) {
4372
4373 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4374 ObjectSynchronizer::omFlush(p);
4375
4376 // Extra scope needed for Thread_lock, so we can check
4377 // that we do not remove thread without safepoint code notice
4378 { MutexLocker ml(Threads_lock);
4379
4380 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4381
4382 // Maintain fast thread list
4383 ThreadsSMRSupport::remove_thread(p);
4384
4385 JavaThread* current = _thread_list;
4386 JavaThread* prev = NULL;
4387
4388 while (current != p) {
4389 prev = current;
4390 current = current->next();
4391 }
4392
4393 if (prev) {
4394 prev->set_next(current->next());
4395 } else {
4396 _thread_list = p->next();
4397 }
4398
4399 _number_of_threads--;
4400 oop threadObj = p->threadObj();
4401 bool daemon = true;
4402 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4403 _number_of_non_daemon_threads--;
4404 daemon = false;
4405
4406 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4407 // on destroy_vm will wake up.
4408 if (number_of_non_daemon_threads() == 1) {
4409 Threads_lock->notify_all();
4410 }
4411 }
4412 ThreadService::remove_thread(p, daemon);
4413
4414 // Make sure that safepoint code disregard this thread. This is needed since
4415 // the thread might mess around with locks after this point. This can cause it
4416 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4417 // of this thread since it is removed from the queue.
4418 p->set_terminated_value();
4419 } // unlock Threads_lock
4420
4421 // Since Events::log uses a lock, we grab it outside the Threads_lock
4422 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4423 }
4424
4425 // Operations on the Threads list for GC. These are not explicitly locked,
4426 // but the garbage collector must provide a safe context for them to run.
4427 // In particular, these things should never be called when the Threads_lock
4428 // is held by some other thread. (Note: the Safepoint abstraction also
4429 // uses the Threads_lock to guarantee this property. It also makes sure that
4430 // all threads gets blocked when exiting or starting).
4431
4432 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4433 ALL_JAVA_THREADS(p) {
4434 p->oops_do(f, cf);
4435 }
4436 VMThread::vm_thread()->oops_do(f, cf);
4437 }
4438
4439 void Threads::change_thread_claim_parity() {
4440 // Set the new claim parity.
4441 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4442 "Not in range.");
4443 _thread_claim_parity++;
4444 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4445 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4446 "Not in range.");
4447 }
4448
4449 #ifdef ASSERT
4450 void Threads::assert_all_threads_claimed() {
4451 ALL_JAVA_THREADS(p) {
4452 const int thread_parity = p->oops_do_parity();
4453 assert((thread_parity == _thread_claim_parity),
4454 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4455 }
4456 VMThread* vmt = VMThread::vm_thread();
4457 const int thread_parity = vmt->oops_do_parity();
4458 assert((thread_parity == _thread_claim_parity),
4459 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4460 }
4461 #endif // ASSERT
4462
4463 class ParallelOopsDoThreadClosure : public ThreadClosure {
4464 private:
4465 OopClosure* _f;
4466 CodeBlobClosure* _cf;
4467 public:
4468 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4469 void do_thread(Thread* t) {
4470 t->oops_do(_f, _cf);
4471 }
4472 };
4473
4474 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4475 ParallelOopsDoThreadClosure tc(f, cf);
4476 possibly_parallel_threads_do(is_par, &tc);
4477 }
4478
4479 void Threads::nmethods_do(CodeBlobClosure* cf) {
4480 ALL_JAVA_THREADS(p) {
4481 // This is used by the code cache sweeper to mark nmethods that are active
4482 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4483 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4484 if(!p->is_Code_cache_sweeper_thread()) {
4485 p->nmethods_do(cf);
4486 }
4487 }
4488 }
4489
4490 void Threads::metadata_do(void f(Metadata*)) {
4491 ALL_JAVA_THREADS(p) {
4492 p->metadata_do(f);
4493 }
4494 }
4495
4496 class ThreadHandlesClosure : public ThreadClosure {
4497 void (*_f)(Metadata*);
4498 public:
4499 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4500 virtual void do_thread(Thread* thread) {
4501 thread->metadata_handles_do(_f);
4502 }
4503 };
4504
4505 void Threads::metadata_handles_do(void f(Metadata*)) {
4506 // Only walk the Handles in Thread.
4507 ThreadHandlesClosure handles_closure(f);
4508 threads_do(&handles_closure);
4509 }
4510
4511 void Threads::deoptimized_wrt_marked_nmethods() {
4512 ALL_JAVA_THREADS(p) {
4513 p->deoptimized_wrt_marked_nmethods();
4514 }
4515 }
4516
4517
4518 // Get count Java threads that are waiting to enter the specified monitor.
4519 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4520 int count,
4521 address monitor) {
4522 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4523
4524 int i = 0;
4525 DO_JAVA_THREADS(t_list, p) {
4526 if (!p->can_call_java()) continue;
4527
4528 address pending = (address)p->current_pending_monitor();
4529 if (pending == monitor) { // found a match
4530 if (i < count) result->append(p); // save the first count matches
4531 i++;
4532 }
4533 }
4534
4535 return result;
4536 }
4537
4538
4539 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4540 address owner) {
4541 // NULL owner means not locked so we can skip the search
4542 if (owner == NULL) return NULL;
4543
4544 DO_JAVA_THREADS(t_list, p) {
4545 // first, see if owner is the address of a Java thread
4546 if (owner == (address)p) return p;
4547 }
4548
4549 // Cannot assert on lack of success here since this function may be
4550 // used by code that is trying to report useful problem information
4551 // like deadlock detection.
4552 if (UseHeavyMonitors) return NULL;
4553
4554 // If we didn't find a matching Java thread and we didn't force use of
4555 // heavyweight monitors, then the owner is the stack address of the
4556 // Lock Word in the owning Java thread's stack.
4557 //
4558 JavaThread* the_owner = NULL;
4559 DO_JAVA_THREADS(t_list, q) {
4560 if (q->is_lock_owned(owner)) {
4561 the_owner = q;
4562 break;
4563 }
4564 }
4565
4566 // cannot assert on lack of success here; see above comment
4567 return the_owner;
4568 }
4569
4570 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4571 void Threads::print_on(outputStream* st, bool print_stacks,
4572 bool internal_format, bool print_concurrent_locks) {
4573 char buf[32];
4574 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4575
4576 st->print_cr("Full thread dump %s (%s %s):",
4577 Abstract_VM_Version::vm_name(),
4578 Abstract_VM_Version::vm_release(),
4579 Abstract_VM_Version::vm_info_string());
4580 st->cr();
4581
4582 #if INCLUDE_SERVICES
4583 // Dump concurrent locks
4584 ConcurrentLocksDump concurrent_locks;
4585 if (print_concurrent_locks) {
4586 concurrent_locks.dump_at_safepoint();
4587 }
4588 #endif // INCLUDE_SERVICES
4589
4590 ThreadsSMRSupport::print_info_on(st);
4591 st->cr();
4592
4593 ALL_JAVA_THREADS(p) {
4594 ResourceMark rm;
4595 p->print_on(st);
4596 if (print_stacks) {
4597 if (internal_format) {
4598 p->trace_stack();
4599 } else {
4600 p->print_stack_on(st);
4601 }
4602 }
4603 st->cr();
4604 #if INCLUDE_SERVICES
4605 if (print_concurrent_locks) {
4606 concurrent_locks.print_locks_on(p, st);
4607 }
4608 #endif // INCLUDE_SERVICES
4609 }
4610
4611 VMThread::vm_thread()->print_on(st);
4612 st->cr();
4613 Universe::heap()->print_gc_threads_on(st);
4614 WatcherThread* wt = WatcherThread::watcher_thread();
4615 if (wt != NULL) {
4616 wt->print_on(st);
4617 st->cr();
4618 }
4619
4620 st->flush();
4621 }
4622
4623 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4624 int buflen, bool* found_current) {
4625 if (this_thread != NULL) {
4626 bool is_current = (current == this_thread);
4627 *found_current = *found_current || is_current;
4628 st->print("%s", is_current ? "=>" : " ");
4629
4630 st->print(PTR_FORMAT, p2i(this_thread));
4631 st->print(" ");
4632 this_thread->print_on_error(st, buf, buflen);
4633 st->cr();
4634 }
4635 }
4636
4637 class PrintOnErrorClosure : public ThreadClosure {
4638 outputStream* _st;
4639 Thread* _current;
4640 char* _buf;
4641 int _buflen;
4642 bool* _found_current;
4643 public:
4644 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4645 int buflen, bool* found_current) :
4646 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4647
4648 virtual void do_thread(Thread* thread) {
4649 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4650 }
4651 };
4652
4653 // Threads::print_on_error() is called by fatal error handler. It's possible
4654 // that VM is not at safepoint and/or current thread is inside signal handler.
4655 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4656 // memory (even in resource area), it might deadlock the error handler.
4657 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4658 int buflen) {
4659 ThreadsSMRSupport::print_info_on(st);
4660 st->cr();
4661
4662 bool found_current = false;
4663 st->print_cr("Java Threads: ( => current thread )");
4664 ALL_JAVA_THREADS(thread) {
4665 print_on_error(thread, st, current, buf, buflen, &found_current);
4666 }
4667 st->cr();
4668
4669 st->print_cr("Other Threads:");
4670 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4671 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4672
4673 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4674 Universe::heap()->gc_threads_do(&print_closure);
4675
4676 if (!found_current) {
4677 st->cr();
4678 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4679 current->print_on_error(st, buf, buflen);
4680 st->cr();
4681 }
4682 st->cr();
4683
4684 st->print_cr("Threads with active compile tasks:");
4685 print_threads_compiling(st, buf, buflen);
4686 }
4687
4688 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4689 ALL_JAVA_THREADS(thread) {
4690 if (thread->is_Compiler_thread()) {
4691 CompilerThread* ct = (CompilerThread*) thread;
4692
4693 // Keep task in local variable for NULL check.
4694 // ct->_task might be set to NULL by concurring compiler thread
4695 // because it completed the compilation. The task is never freed,
4696 // though, just returned to a free list.
4697 CompileTask* task = ct->task();
4698 if (task != NULL) {
4699 thread->print_name_on_error(st, buf, buflen);
4700 task->print(st, NULL, true, true);
4701 }
4702 }
4703 }
4704 }
4705
4706
4707 // Internal SpinLock and Mutex
4708 // Based on ParkEvent
4709
4710 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4711 //
4712 // We employ SpinLocks _only for low-contention, fixed-length
4713 // short-duration critical sections where we're concerned
4714 // about native mutex_t or HotSpot Mutex:: latency.
4715 // The mux construct provides a spin-then-block mutual exclusion
4716 // mechanism.
4717 //
4718 // Testing has shown that contention on the ListLock guarding gFreeList
4719 // is common. If we implement ListLock as a simple SpinLock it's common
4720 // for the JVM to devolve to yielding with little progress. This is true
4721 // despite the fact that the critical sections protected by ListLock are
4722 // extremely short.
4723 //
4724 // TODO-FIXME: ListLock should be of type SpinLock.
4725 // We should make this a 1st-class type, integrated into the lock
4726 // hierarchy as leaf-locks. Critically, the SpinLock structure
4727 // should have sufficient padding to avoid false-sharing and excessive
4728 // cache-coherency traffic.
4729
4730
4731 typedef volatile int SpinLockT;
4732
4733 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4734 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4735 return; // normal fast-path return
4736 }
4737
4738 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4739 TEVENT(SpinAcquire - ctx);
4740 int ctr = 0;
4741 int Yields = 0;
4742 for (;;) {
4743 while (*adr != 0) {
4744 ++ctr;
4745 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4746 if (Yields > 5) {
4747 os::naked_short_sleep(1);
4748 } else {
4749 os::naked_yield();
4750 ++Yields;
4751 }
4752 } else {
4753 SpinPause();
4754 }
4755 }
4756 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4757 }
4758 }
4759
4760 void Thread::SpinRelease(volatile int * adr) {
4761 assert(*adr != 0, "invariant");
4762 OrderAccess::fence(); // guarantee at least release consistency.
4763 // Roach-motel semantics.
4764 // It's safe if subsequent LDs and STs float "up" into the critical section,
4765 // but prior LDs and STs within the critical section can't be allowed
4766 // to reorder or float past the ST that releases the lock.
4767 // Loads and stores in the critical section - which appear in program
4768 // order before the store that releases the lock - must also appear
4769 // before the store that releases the lock in memory visibility order.
4770 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4771 // the ST of 0 into the lock-word which releases the lock, so fence
4772 // more than covers this on all platforms.
4773 *adr = 0;
4774 }
4775
4776 // muxAcquire and muxRelease:
4777 //
4778 // * muxAcquire and muxRelease support a single-word lock-word construct.
4779 // The LSB of the word is set IFF the lock is held.
4780 // The remainder of the word points to the head of a singly-linked list
4781 // of threads blocked on the lock.
4782 //
4783 // * The current implementation of muxAcquire-muxRelease uses its own
4784 // dedicated Thread._MuxEvent instance. If we're interested in
4785 // minimizing the peak number of extant ParkEvent instances then
4786 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4787 // as certain invariants were satisfied. Specifically, care would need
4788 // to be taken with regards to consuming unpark() "permits".
4789 // A safe rule of thumb is that a thread would never call muxAcquire()
4790 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4791 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4792 // consume an unpark() permit intended for monitorenter, for instance.
4793 // One way around this would be to widen the restricted-range semaphore
4794 // implemented in park(). Another alternative would be to provide
4795 // multiple instances of the PlatformEvent() for each thread. One
4796 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4797 //
4798 // * Usage:
4799 // -- Only as leaf locks
4800 // -- for short-term locking only as muxAcquire does not perform
4801 // thread state transitions.
4802 //
4803 // Alternatives:
4804 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4805 // but with parking or spin-then-park instead of pure spinning.
4806 // * Use Taura-Oyama-Yonenzawa locks.
4807 // * It's possible to construct a 1-0 lock if we encode the lockword as
4808 // (List,LockByte). Acquire will CAS the full lockword while Release
4809 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4810 // acquiring threads use timers (ParkTimed) to detect and recover from
4811 // the stranding window. Thread/Node structures must be aligned on 256-byte
4812 // boundaries by using placement-new.
4813 // * Augment MCS with advisory back-link fields maintained with CAS().
4814 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4815 // The validity of the backlinks must be ratified before we trust the value.
4816 // If the backlinks are invalid the exiting thread must back-track through the
4817 // the forward links, which are always trustworthy.
4818 // * Add a successor indication. The LockWord is currently encoded as
4819 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4820 // to provide the usual futile-wakeup optimization.
4821 // See RTStt for details.
4822 // * Consider schedctl.sc_nopreempt to cover the critical section.
4823 //
4824
4825
4826 const intptr_t LOCKBIT = 1;
4827
4828 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4829 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4830 if (w == 0) return;
4831 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4832 return;
4833 }
4834
4835 TEVENT(muxAcquire - Contention);
4836 ParkEvent * const Self = Thread::current()->_MuxEvent;
4837 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4838 for (;;) {
4839 int its = (os::is_MP() ? 100 : 0) + 1;
4840
4841 // Optional spin phase: spin-then-park strategy
4842 while (--its >= 0) {
4843 w = *Lock;
4844 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4845 return;
4846 }
4847 }
4848
4849 Self->reset();
4850 Self->OnList = intptr_t(Lock);
4851 // The following fence() isn't _strictly necessary as the subsequent
4852 // CAS() both serializes execution and ratifies the fetched *Lock value.
4853 OrderAccess::fence();
4854 for (;;) {
4855 w = *Lock;
4856 if ((w & LOCKBIT) == 0) {
4857 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4858 Self->OnList = 0; // hygiene - allows stronger asserts
4859 return;
4860 }
4861 continue; // Interference -- *Lock changed -- Just retry
4862 }
4863 assert(w & LOCKBIT, "invariant");
4864 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4865 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4866 }
4867
4868 while (Self->OnList != 0) {
4869 Self->park();
4870 }
4871 }
4872 }
4873
4874 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4875 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4876 if (w == 0) return;
4877 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4878 return;
4879 }
4880
4881 TEVENT(muxAcquire - Contention);
4882 ParkEvent * ReleaseAfter = NULL;
4883 if (ev == NULL) {
4884 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4885 }
4886 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4887 for (;;) {
4888 guarantee(ev->OnList == 0, "invariant");
4889 int its = (os::is_MP() ? 100 : 0) + 1;
4890
4891 // Optional spin phase: spin-then-park strategy
4892 while (--its >= 0) {
4893 w = *Lock;
4894 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4895 if (ReleaseAfter != NULL) {
4896 ParkEvent::Release(ReleaseAfter);
4897 }
4898 return;
4899 }
4900 }
4901
4902 ev->reset();
4903 ev->OnList = intptr_t(Lock);
4904 // The following fence() isn't _strictly necessary as the subsequent
4905 // CAS() both serializes execution and ratifies the fetched *Lock value.
4906 OrderAccess::fence();
4907 for (;;) {
4908 w = *Lock;
4909 if ((w & LOCKBIT) == 0) {
4910 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4911 ev->OnList = 0;
4912 // We call ::Release while holding the outer lock, thus
4913 // artificially lengthening the critical section.
4914 // Consider deferring the ::Release() until the subsequent unlock(),
4915 // after we've dropped the outer lock.
4916 if (ReleaseAfter != NULL) {
4917 ParkEvent::Release(ReleaseAfter);
4918 }
4919 return;
4920 }
4921 continue; // Interference -- *Lock changed -- Just retry
4922 }
4923 assert(w & LOCKBIT, "invariant");
4924 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4925 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4926 }
4927
4928 while (ev->OnList != 0) {
4929 ev->park();
4930 }
4931 }
4932 }
4933
4934 // Release() must extract a successor from the list and then wake that thread.
4935 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4936 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4937 // Release() would :
4938 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4939 // (B) Extract a successor from the private list "in-hand"
4940 // (C) attempt to CAS() the residual back into *Lock over null.
4941 // If there were any newly arrived threads and the CAS() would fail.
4942 // In that case Release() would detach the RATs, re-merge the list in-hand
4943 // with the RATs and repeat as needed. Alternately, Release() might
4944 // detach and extract a successor, but then pass the residual list to the wakee.
4945 // The wakee would be responsible for reattaching and remerging before it
4946 // competed for the lock.
4947 //
4948 // Both "pop" and DMR are immune from ABA corruption -- there can be
4949 // multiple concurrent pushers, but only one popper or detacher.
4950 // This implementation pops from the head of the list. This is unfair,
4951 // but tends to provide excellent throughput as hot threads remain hot.
4952 // (We wake recently run threads first).
4953 //
4954 // All paths through muxRelease() will execute a CAS.
4955 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4956 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4957 // executed within the critical section are complete and globally visible before the
4958 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4959 void Thread::muxRelease(volatile intptr_t * Lock) {
4960 for (;;) {
4961 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4962 assert(w & LOCKBIT, "invariant");
4963 if (w == LOCKBIT) return;
4964 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4965 assert(List != NULL, "invariant");
4966 assert(List->OnList == intptr_t(Lock), "invariant");
4967 ParkEvent * const nxt = List->ListNext;
4968 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4969
4970 // The following CAS() releases the lock and pops the head element.
4971 // The CAS() also ratifies the previously fetched lock-word value.
4972 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4973 continue;
4974 }
4975 List->OnList = 0;
4976 OrderAccess::fence();
4977 List->unpark();
4978 return;
4979 }
4980 }
4981
4982
4983 void Threads::verify() {
4984 ALL_JAVA_THREADS(p) {
4985 p->verify();
4986 }
4987 VMThread* thread = VMThread::vm_thread();
4988 if (thread != NULL) thread->verify();
4989 }