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/gcId.hpp"
37 #include "gc/shared/gcLocker.inline.hpp"
38 #include "gc/shared/workgroup.hpp"
39 #include "interpreter/interpreter.hpp"
40 #include "interpreter/linkResolver.hpp"
41 #include "interpreter/oopMapCache.hpp"
42 #include "jvmtifiles/jvmtiEnv.hpp"
43 #include "logging/log.hpp"
44 #include "logging/logConfiguration.hpp"
45 #include "logging/logStream.hpp"
46 #include "memory/allocation.inline.hpp"
47 #include "memory/metaspaceShared.hpp"
48 #include "memory/oopFactory.hpp"
49 #include "memory/resourceArea.hpp"
50 #include "memory/universe.hpp"
51 #include "oops/access.inline.hpp"
52 #include "oops/instanceKlass.hpp"
53 #include "oops/objArrayOop.hpp"
54 #include "oops/oop.inline.hpp"
55 #include "oops/symbol.hpp"
56 #include "oops/typeArrayOop.inline.hpp"
57 #include "oops/verifyOopClosure.hpp"
58 #include "prims/jvm_misc.hpp"
59 #include "prims/jvmtiExport.hpp"
60 #include "prims/jvmtiThreadState.hpp"
61 #include "prims/privilegedStack.hpp"
62 #include "runtime/arguments.hpp"
63 #include "runtime/atomic.hpp"
64 #include "runtime/biasedLocking.hpp"
65 #include "runtime/commandLineFlagConstraintList.hpp"
66 #include "runtime/commandLineFlagWriteableList.hpp"
67 #include "runtime/commandLineFlagRangeList.hpp"
68 #include "runtime/deoptimization.hpp"
69 #include "runtime/frame.inline.hpp"
70 #include "runtime/globals.hpp"
71 #include "runtime/handshake.hpp"
72 #include "runtime/init.hpp"
73 #include "runtime/interfaceSupport.inline.hpp"
74 #include "runtime/java.hpp"
75 #include "runtime/javaCalls.hpp"
76 #include "runtime/jniHandles.inline.hpp"
77 #include "runtime/jniPeriodicChecker.hpp"
78 #include "runtime/memprofiler.hpp"
79 #include "runtime/mutexLocker.hpp"
80 #include "runtime/objectMonitor.hpp"
81 #include "runtime/orderAccess.inline.hpp"
82 #include "runtime/osThread.hpp"
83 #include "runtime/prefetch.inline.hpp"
84 #include "runtime/safepoint.hpp"
85 #include "runtime/safepointMechanism.inline.hpp"
86 #include "runtime/sharedRuntime.hpp"
87 #include "runtime/statSampler.hpp"
88 #include "runtime/stubRoutines.hpp"
89 #include "runtime/sweeper.hpp"
90 #include "runtime/task.hpp"
91 #include "runtime/thread.inline.hpp"
92 #include "runtime/threadCritical.hpp"
93 #include "runtime/threadSMR.inline.hpp"
94 #include "runtime/timer.hpp"
95 #include "runtime/timerTrace.hpp"
96 #include "runtime/vframe.inline.hpp"
97 #include "runtime/vframeArray.hpp"
98 #include "runtime/vframe_hp.hpp"
99 #include "runtime/vmThread.hpp"
100 #include "runtime/vm_operations.hpp"
101 #include "runtime/vm_version.hpp"
102 #include "services/attachListener.hpp"
103 #include "services/management.hpp"
104 #include "services/memTracker.hpp"
105 #include "services/threadService.hpp"
106 #include "trace/traceMacros.hpp"
107 #include "trace/tracing.hpp"
108 #include "utilities/align.hpp"
109 #include "utilities/defaultStream.hpp"
110 #include "utilities/dtrace.hpp"
111 #include "utilities/events.hpp"
112 #include "utilities/macros.hpp"
113 #include "utilities/preserveException.hpp"
114 #include "utilities/vmError.hpp"
115 #if INCLUDE_ALL_GCS
116 #include "gc/cms/concurrentMarkSweepThread.hpp"
117 #include "gc/g1/concurrentMarkThread.inline.hpp"
118 #include "gc/parallel/pcTasks.hpp"
119 #endif // INCLUDE_ALL_GCS
120 #if INCLUDE_JVMCI
121 #include "jvmci/jvmciCompiler.hpp"
122 #include "jvmci/jvmciRuntime.hpp"
123 #include "logging/logHandle.hpp"
124 #endif
125 #ifdef COMPILER1
126 #include "c1/c1_Compiler.hpp"
127 #endif
128 #ifdef COMPILER2
129 #include "opto/c2compiler.hpp"
130 #include "opto/idealGraphPrinter.hpp"
131 #endif
132 #if INCLUDE_RTM_OPT
133 #include "runtime/rtmLocking.hpp"
134 #endif
135
136 // Initialization after module runtime initialization
137 void universe_post_module_init(); // must happen after call_initPhase2
138
139 #ifdef DTRACE_ENABLED
140
141 // Only bother with this argument setup if dtrace is available
142
143 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
144 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
145
146 #define DTRACE_THREAD_PROBE(probe, javathread) \
147 { \
148 ResourceMark rm(this); \
149 int len = 0; \
150 const char* name = (javathread)->get_thread_name(); \
151 len = strlen(name); \
152 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
153 (char *) name, len, \
154 java_lang_Thread::thread_id((javathread)->threadObj()), \
155 (uintptr_t) (javathread)->osthread()->thread_id(), \
156 java_lang_Thread::is_daemon((javathread)->threadObj())); \
157 }
158
159 #else // ndef DTRACE_ENABLED
160
161 #define DTRACE_THREAD_PROBE(probe, javathread)
162
163 #endif // ndef DTRACE_ENABLED
164
165 #ifndef USE_LIBRARY_BASED_TLS_ONLY
166 // Current thread is maintained as a thread-local variable
167 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
168 #endif
169 // Class hierarchy
170 // - Thread
171 // - VMThread
172 // - WatcherThread
173 // - ConcurrentMarkSweepThread
174 // - JavaThread
175 // - CompilerThread
176
177 // ======= Thread ========
178 // Support for forcing alignment of thread objects for biased locking
179 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
180 if (UseBiasedLocking) {
181 const int alignment = markOopDesc::biased_lock_alignment;
182 size_t aligned_size = size + (alignment - sizeof(intptr_t));
183 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
184 : AllocateHeap(aligned_size, flags, CURRENT_PC,
185 AllocFailStrategy::RETURN_NULL);
186 void* aligned_addr = align_up(real_malloc_addr, alignment);
187 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
188 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
189 "JavaThread alignment code overflowed allocated storage");
190 if (aligned_addr != real_malloc_addr) {
191 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
192 p2i(real_malloc_addr),
193 p2i(aligned_addr));
194 }
195 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
196 return aligned_addr;
197 } else {
198 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
199 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
200 }
201 }
202
203 void Thread::operator delete(void* p) {
204 if (UseBiasedLocking) {
205 FreeHeap(((Thread*) p)->_real_malloc_address);
206 } else {
207 FreeHeap(p);
208 }
209 }
210
211 void JavaThread::smr_delete() {
212 if (_on_thread_list) {
213 ThreadsSMRSupport::smr_delete(this);
214 } else {
215 delete this;
216 }
217 }
218
219 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
220 // JavaThread
221
222
223 Thread::Thread() {
224 // stack and get_thread
225 set_stack_base(NULL);
226 set_stack_size(0);
227 set_self_raw_id(0);
228 set_lgrp_id(-1);
229 DEBUG_ONLY(clear_suspendible_thread();)
230
231 // allocated data structures
232 set_osthread(NULL);
233 set_resource_area(new (mtThread)ResourceArea());
234 DEBUG_ONLY(_current_resource_mark = NULL;)
235 set_handle_area(new (mtThread) HandleArea(NULL));
236 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
237 set_active_handles(NULL);
238 set_free_handle_block(NULL);
239 set_last_handle_mark(NULL);
240
241 // This initial value ==> never claimed.
242 _oops_do_parity = 0;
243 _threads_hazard_ptr = NULL;
244 _nested_threads_hazard_ptr = NULL;
245 _nested_threads_hazard_ptr_cnt = 0;
246
247 // the handle mark links itself to last_handle_mark
248 new HandleMark(this);
249
250 // plain initialization
251 debug_only(_owned_locks = NULL;)
252 debug_only(_allow_allocation_count = 0;)
253 NOT_PRODUCT(_allow_safepoint_count = 0;)
254 NOT_PRODUCT(_skip_gcalot = false;)
255 _jvmti_env_iteration_count = 0;
256 set_allocated_bytes(0);
257 _vm_operation_started_count = 0;
258 _vm_operation_completed_count = 0;
259 _current_pending_monitor = NULL;
260 _current_pending_monitor_is_from_java = true;
261 _current_waiting_monitor = NULL;
262 _num_nested_signal = 0;
263 omFreeList = NULL;
264 omFreeCount = 0;
265 omFreeProvision = 32;
266 omInUseList = NULL;
267 omInUseCount = 0;
268
269 #ifdef ASSERT
270 _visited_for_critical_count = false;
271 #endif
272
273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
274 Monitor::_safepoint_check_sometimes);
275 _suspend_flags = 0;
276
277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
278 _hashStateX = os::random();
279 _hashStateY = 842502087;
280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
281 _hashStateW = 273326509;
282
283 _OnTrap = 0;
284 _schedctl = NULL;
285 _Stalled = 0;
286 _TypeTag = 0x2BAD;
287
288 // Many of the following fields are effectively final - immutable
289 // Note that nascent threads can't use the Native Monitor-Mutex
290 // construct until the _MutexEvent is initialized ...
291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
292 // we might instead use a stack of ParkEvents that we could provision on-demand.
293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
294 // and ::Release()
295 _ParkEvent = ParkEvent::Allocate(this);
296 _SleepEvent = ParkEvent::Allocate(this);
297 _MutexEvent = ParkEvent::Allocate(this);
298 _MuxEvent = ParkEvent::Allocate(this);
299
300 #ifdef CHECK_UNHANDLED_OOPS
301 if (CheckUnhandledOops) {
302 _unhandled_oops = new UnhandledOops(this);
303 }
304 #endif // CHECK_UNHANDLED_OOPS
305 #ifdef ASSERT
306 if (UseBiasedLocking) {
307 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
308 assert(this == _real_malloc_address ||
309 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
310 "bug in forced alignment of thread objects");
311 }
312 #endif // ASSERT
313 }
314
315 void Thread::initialize_thread_current() {
316 #ifndef USE_LIBRARY_BASED_TLS_ONLY
317 assert(_thr_current == NULL, "Thread::current already initialized");
318 _thr_current = this;
319 #endif
320 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
321 ThreadLocalStorage::set_thread(this);
322 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
323 }
324
325 void Thread::clear_thread_current() {
326 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
327 #ifndef USE_LIBRARY_BASED_TLS_ONLY
328 _thr_current = NULL;
329 #endif
330 ThreadLocalStorage::set_thread(NULL);
331 }
332
333 void Thread::record_stack_base_and_size() {
334 set_stack_base(os::current_stack_base());
335 set_stack_size(os::current_stack_size());
336 // CR 7190089: on Solaris, primordial thread's stack is adjusted
337 // in initialize_thread(). Without the adjustment, stack size is
338 // incorrect if stack is set to unlimited (ulimit -s unlimited).
339 // So far, only Solaris has real implementation of initialize_thread().
340 //
341 // set up any platform-specific state.
342 os::initialize_thread(this);
343
344 // Set stack limits after thread is initialized.
345 if (is_Java_thread()) {
346 ((JavaThread*) this)->set_stack_overflow_limit();
347 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
348 }
349 #if INCLUDE_NMT
350 // record thread's native stack, stack grows downward
351 MemTracker::record_thread_stack(stack_end(), stack_size());
352 #endif // INCLUDE_NMT
353 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
354 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
355 os::current_thread_id(), p2i(stack_base() - stack_size()),
356 p2i(stack_base()), stack_size()/1024);
357 }
358
359
360 Thread::~Thread() {
361 EVENT_THREAD_DESTRUCT(this);
362
363 // stack_base can be NULL if the thread is never started or exited before
364 // record_stack_base_and_size called. Although, we would like to ensure
365 // that all started threads do call record_stack_base_and_size(), there is
366 // not proper way to enforce that.
367 #if INCLUDE_NMT
368 if (_stack_base != NULL) {
369 MemTracker::release_thread_stack(stack_end(), stack_size());
370 #ifdef ASSERT
371 set_stack_base(NULL);
372 #endif
373 }
374 #endif // INCLUDE_NMT
375
376 // deallocate data structures
377 delete resource_area();
378 // since the handle marks are using the handle area, we have to deallocated the root
379 // handle mark before deallocating the thread's handle area,
380 assert(last_handle_mark() != NULL, "check we have an element");
381 delete last_handle_mark();
382 assert(last_handle_mark() == NULL, "check we have reached the end");
383
384 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
385 // We NULL out the fields for good hygiene.
386 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
387 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
388 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
389 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
390
391 delete handle_area();
392 delete metadata_handles();
393
394 // SR_handler uses this as a termination indicator -
395 // needs to happen before os::free_thread()
396 delete _SR_lock;
397 _SR_lock = NULL;
398
399 // osthread() can be NULL, if creation of thread failed.
400 if (osthread() != NULL) os::free_thread(osthread());
401
402 // clear Thread::current if thread is deleting itself.
403 // Needed to ensure JNI correctly detects non-attached threads.
404 if (this == Thread::current()) {
405 clear_thread_current();
406 }
407
408 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
409 }
410
411 // NOTE: dummy function for assertion purpose.
412 void Thread::run() {
413 ShouldNotReachHere();
414 }
415
416 #ifdef ASSERT
417 // A JavaThread is considered "dangling" if it is not the current
418 // thread, has been added the Threads list, the system is not at a
419 // safepoint and the Thread is not "protected".
420 //
421 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
422 assert(!thread->is_Java_thread() || Thread::current() == thread ||
423 !((JavaThread *) thread)->on_thread_list() ||
424 SafepointSynchronize::is_at_safepoint() ||
425 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
426 "possibility of dangling Thread pointer");
427 }
428 #endif
429
430 ThreadPriority Thread::get_priority(const Thread* const thread) {
431 ThreadPriority priority;
432 // Can return an error!
433 (void)os::get_priority(thread, priority);
434 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
435 return priority;
436 }
437
438 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
439 debug_only(check_for_dangling_thread_pointer(thread);)
440 // Can return an error!
441 (void)os::set_priority(thread, priority);
442 }
443
444
445 void Thread::start(Thread* thread) {
446 // Start is different from resume in that its safety is guaranteed by context or
447 // being called from a Java method synchronized on the Thread object.
448 if (!DisableStartThread) {
449 if (thread->is_Java_thread()) {
450 // Initialize the thread state to RUNNABLE before starting this thread.
451 // Can not set it after the thread started because we do not know the
452 // exact thread state at that time. It could be in MONITOR_WAIT or
453 // in SLEEPING or some other state.
454 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
455 java_lang_Thread::RUNNABLE);
456 }
457 os::start_thread(thread);
458 }
459 }
460
461 // Enqueue a VM_Operation to do the job for us - sometime later
462 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
463 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
464 VMThread::execute(vm_stop);
465 }
466
467
468 // Check if an external suspend request has completed (or has been
469 // cancelled). Returns true if the thread is externally suspended and
470 // false otherwise.
471 //
472 // The bits parameter returns information about the code path through
473 // the routine. Useful for debugging:
474 //
475 // set in is_ext_suspend_completed():
476 // 0x00000001 - routine was entered
477 // 0x00000010 - routine return false at end
478 // 0x00000100 - thread exited (return false)
479 // 0x00000200 - suspend request cancelled (return false)
480 // 0x00000400 - thread suspended (return true)
481 // 0x00001000 - thread is in a suspend equivalent state (return true)
482 // 0x00002000 - thread is native and walkable (return true)
483 // 0x00004000 - thread is native_trans and walkable (needed retry)
484 //
485 // set in wait_for_ext_suspend_completion():
486 // 0x00010000 - routine was entered
487 // 0x00020000 - suspend request cancelled before loop (return false)
488 // 0x00040000 - thread suspended before loop (return true)
489 // 0x00080000 - suspend request cancelled in loop (return false)
490 // 0x00100000 - thread suspended in loop (return true)
491 // 0x00200000 - suspend not completed during retry loop (return false)
492
493 // Helper class for tracing suspend wait debug bits.
494 //
495 // 0x00000100 indicates that the target thread exited before it could
496 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
497 // 0x00080000 each indicate a cancelled suspend request so they don't
498 // count as wait failures either.
499 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
500
501 class TraceSuspendDebugBits : public StackObj {
502 private:
503 JavaThread * jt;
504 bool is_wait;
505 bool called_by_wait; // meaningful when !is_wait
506 uint32_t * bits;
507
508 public:
509 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
510 uint32_t *_bits) {
511 jt = _jt;
512 is_wait = _is_wait;
513 called_by_wait = _called_by_wait;
514 bits = _bits;
515 }
516
517 ~TraceSuspendDebugBits() {
518 if (!is_wait) {
519 #if 1
520 // By default, don't trace bits for is_ext_suspend_completed() calls.
521 // That trace is very chatty.
522 return;
523 #else
524 if (!called_by_wait) {
525 // If tracing for is_ext_suspend_completed() is enabled, then only
526 // trace calls to it from wait_for_ext_suspend_completion()
527 return;
528 }
529 #endif
530 }
531
532 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
533 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
534 MutexLocker ml(Threads_lock); // needed for get_thread_name()
535 ResourceMark rm;
536
537 tty->print_cr(
538 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
539 jt->get_thread_name(), *bits);
540
541 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
542 }
543 }
544 }
545 };
546 #undef DEBUG_FALSE_BITS
547
548
549 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
550 uint32_t *bits) {
551 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
552
553 bool did_trans_retry = false; // only do thread_in_native_trans retry once
554 bool do_trans_retry; // flag to force the retry
555
556 *bits |= 0x00000001;
557
558 do {
559 do_trans_retry = false;
560
561 if (is_exiting()) {
562 // Thread is in the process of exiting. This is always checked
563 // first to reduce the risk of dereferencing a freed JavaThread.
564 *bits |= 0x00000100;
565 return false;
566 }
567
568 if (!is_external_suspend()) {
569 // Suspend request is cancelled. This is always checked before
570 // is_ext_suspended() to reduce the risk of a rogue resume
571 // confusing the thread that made the suspend request.
572 *bits |= 0x00000200;
573 return false;
574 }
575
576 if (is_ext_suspended()) {
577 // thread is suspended
578 *bits |= 0x00000400;
579 return true;
580 }
581
582 // Now that we no longer do hard suspends of threads running
583 // native code, the target thread can be changing thread state
584 // while we are in this routine:
585 //
586 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
587 //
588 // We save a copy of the thread state as observed at this moment
589 // and make our decision about suspend completeness based on the
590 // copy. This closes the race where the thread state is seen as
591 // _thread_in_native_trans in the if-thread_blocked check, but is
592 // seen as _thread_blocked in if-thread_in_native_trans check.
593 JavaThreadState save_state = thread_state();
594
595 if (save_state == _thread_blocked && is_suspend_equivalent()) {
596 // If the thread's state is _thread_blocked and this blocking
597 // condition is known to be equivalent to a suspend, then we can
598 // consider the thread to be externally suspended. This means that
599 // the code that sets _thread_blocked has been modified to do
600 // self-suspension if the blocking condition releases. We also
601 // used to check for CONDVAR_WAIT here, but that is now covered by
602 // the _thread_blocked with self-suspension check.
603 //
604 // Return true since we wouldn't be here unless there was still an
605 // external suspend request.
606 *bits |= 0x00001000;
607 return true;
608 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
609 // Threads running native code will self-suspend on native==>VM/Java
610 // transitions. If its stack is walkable (should always be the case
611 // unless this function is called before the actual java_suspend()
612 // call), then the wait is done.
613 *bits |= 0x00002000;
614 return true;
615 } else if (!called_by_wait && !did_trans_retry &&
616 save_state == _thread_in_native_trans &&
617 frame_anchor()->walkable()) {
618 // The thread is transitioning from thread_in_native to another
619 // thread state. check_safepoint_and_suspend_for_native_trans()
620 // will force the thread to self-suspend. If it hasn't gotten
621 // there yet we may have caught the thread in-between the native
622 // code check above and the self-suspend. Lucky us. If we were
623 // called by wait_for_ext_suspend_completion(), then it
624 // will be doing the retries so we don't have to.
625 //
626 // Since we use the saved thread state in the if-statement above,
627 // there is a chance that the thread has already transitioned to
628 // _thread_blocked by the time we get here. In that case, we will
629 // make a single unnecessary pass through the logic below. This
630 // doesn't hurt anything since we still do the trans retry.
631
632 *bits |= 0x00004000;
633
634 // Once the thread leaves thread_in_native_trans for another
635 // thread state, we break out of this retry loop. We shouldn't
636 // need this flag to prevent us from getting back here, but
637 // sometimes paranoia is good.
638 did_trans_retry = true;
639
640 // We wait for the thread to transition to a more usable state.
641 for (int i = 1; i <= SuspendRetryCount; i++) {
642 // We used to do an "os::yield_all(i)" call here with the intention
643 // that yielding would increase on each retry. However, the parameter
644 // is ignored on Linux which means the yield didn't scale up. Waiting
645 // on the SR_lock below provides a much more predictable scale up for
646 // the delay. It also provides a simple/direct point to check for any
647 // safepoint requests from the VMThread
648
649 // temporarily drops SR_lock while doing wait with safepoint check
650 // (if we're a JavaThread - the WatcherThread can also call this)
651 // and increase delay with each retry
652 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
653
654 // check the actual thread state instead of what we saved above
655 if (thread_state() != _thread_in_native_trans) {
656 // the thread has transitioned to another thread state so
657 // try all the checks (except this one) one more time.
658 do_trans_retry = true;
659 break;
660 }
661 } // end retry loop
662
663
664 }
665 } while (do_trans_retry);
666
667 *bits |= 0x00000010;
668 return false;
669 }
670
671 // Wait for an external suspend request to complete (or be cancelled).
672 // Returns true if the thread is externally suspended and false otherwise.
673 //
674 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
675 uint32_t *bits) {
676 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
677 false /* !called_by_wait */, bits);
678
679 // local flag copies to minimize SR_lock hold time
680 bool is_suspended;
681 bool pending;
682 uint32_t reset_bits;
683
684 // set a marker so is_ext_suspend_completed() knows we are the caller
685 *bits |= 0x00010000;
686
687 // We use reset_bits to reinitialize the bits value at the top of
688 // each retry loop. This allows the caller to make use of any
689 // unused bits for their own marking purposes.
690 reset_bits = *bits;
691
692 {
693 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
694 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
695 delay, bits);
696 pending = is_external_suspend();
697 }
698 // must release SR_lock to allow suspension to complete
699
700 if (!pending) {
701 // A cancelled suspend request is the only false return from
702 // is_ext_suspend_completed() that keeps us from entering the
703 // retry loop.
704 *bits |= 0x00020000;
705 return false;
706 }
707
708 if (is_suspended) {
709 *bits |= 0x00040000;
710 return true;
711 }
712
713 for (int i = 1; i <= retries; i++) {
714 *bits = reset_bits; // reinit to only track last retry
715
716 // We used to do an "os::yield_all(i)" call here with the intention
717 // that yielding would increase on each retry. However, the parameter
718 // is ignored on Linux which means the yield didn't scale up. Waiting
719 // on the SR_lock below provides a much more predictable scale up for
720 // the delay. It also provides a simple/direct point to check for any
721 // safepoint requests from the VMThread
722
723 {
724 MutexLocker ml(SR_lock());
725 // wait with safepoint check (if we're a JavaThread - the WatcherThread
726 // can also call this) and increase delay with each retry
727 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
728
729 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
730 delay, bits);
731
732 // It is possible for the external suspend request to be cancelled
733 // (by a resume) before the actual suspend operation is completed.
734 // Refresh our local copy to see if we still need to wait.
735 pending = is_external_suspend();
736 }
737
738 if (!pending) {
739 // A cancelled suspend request is the only false return from
740 // is_ext_suspend_completed() that keeps us from staying in the
741 // retry loop.
742 *bits |= 0x00080000;
743 return false;
744 }
745
746 if (is_suspended) {
747 *bits |= 0x00100000;
748 return true;
749 }
750 } // end retry loop
751
752 // thread did not suspend after all our retries
753 *bits |= 0x00200000;
754 return false;
755 }
756
757 // Called from API entry points which perform stack walking. If the
758 // associated JavaThread is the current thread, then wait_for_suspend
759 // is not used. Otherwise, it determines if we should wait for the
760 // "other" thread to complete external suspension. (NOTE: in future
761 // releases the suspension mechanism should be reimplemented so this
762 // is not necessary.)
763 //
764 bool
765 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
766 if (this != JavaThread::current()) {
767 // "other" threads require special handling.
768 if (wait_for_suspend) {
769 // We are allowed to wait for the external suspend to complete
770 // so give the other thread a chance to get suspended.
771 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
772 SuspendRetryDelay, bits)) {
773 // Didn't make it so let the caller know.
774 return false;
775 }
776 }
777 // We aren't allowed to wait for the external suspend to complete
778 // so if the other thread isn't externally suspended we need to
779 // let the caller know.
780 else if (!is_ext_suspend_completed_with_lock(bits)) {
781 return false;
782 }
783 }
784
785 return true;
786 }
787
788 #ifndef PRODUCT
789 void JavaThread::record_jump(address target, address instr, const char* file,
790 int line) {
791
792 // This should not need to be atomic as the only way for simultaneous
793 // updates is via interrupts. Even then this should be rare or non-existent
794 // and we don't care that much anyway.
795
796 int index = _jmp_ring_index;
797 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
798 _jmp_ring[index]._target = (intptr_t) target;
799 _jmp_ring[index]._instruction = (intptr_t) instr;
800 _jmp_ring[index]._file = file;
801 _jmp_ring[index]._line = line;
802 }
803 #endif // PRODUCT
804
805 void Thread::interrupt(Thread* thread) {
806 debug_only(check_for_dangling_thread_pointer(thread);)
807 os::interrupt(thread);
808 }
809
810 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
811 debug_only(check_for_dangling_thread_pointer(thread);)
812 // Note: If clear_interrupted==false, this simply fetches and
813 // returns the value of the field osthread()->interrupted().
814 return os::is_interrupted(thread, clear_interrupted);
815 }
816
817
818 // GC Support
819 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
820 int thread_parity = _oops_do_parity;
821 if (thread_parity != strong_roots_parity) {
822 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
823 if (res == thread_parity) {
824 return true;
825 } else {
826 guarantee(res == strong_roots_parity, "Or else what?");
827 return false;
828 }
829 }
830 return false;
831 }
832
833 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
834 active_handles()->oops_do(f);
835 // Do oop for ThreadShadow
836 f->do_oop((oop*)&_pending_exception);
837 handle_area()->oops_do(f);
838
839 if (MonitorInUseLists) {
840 // When using thread local monitor lists, we scan them here,
841 // and the remaining global monitors in ObjectSynchronizer::oops_do().
842 ObjectSynchronizer::thread_local_used_oops_do(this, f);
843 }
844 }
845
846 void Thread::metadata_handles_do(void f(Metadata*)) {
847 // Only walk the Handles in Thread.
848 if (metadata_handles() != NULL) {
849 for (int i = 0; i< metadata_handles()->length(); i++) {
850 f(metadata_handles()->at(i));
851 }
852 }
853 }
854
855 void Thread::print_on(outputStream* st) const {
856 // get_priority assumes osthread initialized
857 if (osthread() != NULL) {
858 int os_prio;
859 if (os::get_native_priority(this, &os_prio) == OS_OK) {
860 st->print("os_prio=%d ", os_prio);
861 }
862 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
863 osthread()->print_on(st);
864 }
865 if (_threads_hazard_ptr != NULL) {
866 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
867 }
868 if (_nested_threads_hazard_ptr != NULL) {
869 print_nested_threads_hazard_ptrs_on(st);
870 }
871 st->print(" ");
872 debug_only(if (WizardMode) print_owned_locks_on(st);)
873 }
874
875 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
876 assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
877
878 if (EnableThreadSMRStatistics) {
879 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
880 }
881 st->print(", _nested_threads_hazard_ptrs=");
882 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
883 node = node->next()) {
884 if (node != _nested_threads_hazard_ptr) {
885 // First node does not need a comma-space separator.
886 st->print(", ");
887 }
888 st->print(INTPTR_FORMAT, p2i(node->t_list()));
889 }
890 }
891
892 // Thread::print_on_error() is called by fatal error handler. Don't use
893 // any lock or allocate memory.
894 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
895 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
896
897 if (is_VM_thread()) { st->print("VMThread"); }
898 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
899 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
900 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
901 else { st->print("Thread"); }
902
903 if (is_Named_thread()) {
904 st->print(" \"%s\"", name());
905 }
906
907 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
908 p2i(stack_end()), p2i(stack_base()));
909
910 if (osthread()) {
911 st->print(" [id=%d]", osthread()->thread_id());
912 }
913
914 if (_threads_hazard_ptr != NULL) {
915 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
916 }
917 if (_nested_threads_hazard_ptr != NULL) {
918 print_nested_threads_hazard_ptrs_on(st);
919 }
920 }
921
922 void Thread::print_value_on(outputStream* st) const {
923 if (is_Named_thread()) {
924 st->print(" \"%s\" ", name());
925 }
926 st->print(INTPTR_FORMAT, p2i(this)); // print address
927 }
928
929 #ifdef ASSERT
930 void Thread::print_owned_locks_on(outputStream* st) const {
931 Monitor *cur = _owned_locks;
932 if (cur == NULL) {
933 st->print(" (no locks) ");
934 } else {
935 st->print_cr(" Locks owned:");
936 while (cur) {
937 cur->print_on(st);
938 cur = cur->next();
939 }
940 }
941 }
942
943 static int ref_use_count = 0;
944
945 bool Thread::owns_locks_but_compiled_lock() const {
946 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
947 if (cur != Compile_lock) return true;
948 }
949 return false;
950 }
951
952
953 #endif
954
955 #ifndef PRODUCT
956
957 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
958 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
959 // no threads which allow_vm_block's are held
960 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
961 // Check if current thread is allowed to block at a safepoint
962 if (!(_allow_safepoint_count == 0)) {
963 fatal("Possible safepoint reached by thread that does not allow it");
964 }
965 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
966 fatal("LEAF method calling lock?");
967 }
968
969 #ifdef ASSERT
970 if (potential_vm_operation && is_Java_thread()
971 && !Universe::is_bootstrapping()) {
972 // Make sure we do not hold any locks that the VM thread also uses.
973 // This could potentially lead to deadlocks
974 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
975 // Threads_lock is special, since the safepoint synchronization will not start before this is
976 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
977 // since it is used to transfer control between JavaThreads and the VMThread
978 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
979 if ((cur->allow_vm_block() &&
980 cur != Threads_lock &&
981 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
982 cur != VMOperationRequest_lock &&
983 cur != VMOperationQueue_lock) ||
984 cur->rank() == Mutex::special) {
985 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
986 }
987 }
988 }
989
990 if (GCALotAtAllSafepoints) {
991 // We could enter a safepoint here and thus have a gc
992 InterfaceSupport::check_gc_alot();
993 }
994 #endif
995 }
996 #endif
997
998 bool Thread::is_in_stack(address adr) const {
999 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1000 address end = os::current_stack_pointer();
1001 // Allow non Java threads to call this without stack_base
1002 if (_stack_base == NULL) return true;
1003 if (stack_base() >= adr && adr >= end) return true;
1004
1005 return false;
1006 }
1007
1008 bool Thread::is_in_usable_stack(address adr) const {
1009 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1010 size_t usable_stack_size = _stack_size - stack_guard_size;
1011
1012 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1013 }
1014
1015
1016 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1017 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1018 // used for compilation in the future. If that change is made, the need for these methods
1019 // should be revisited, and they should be removed if possible.
1020
1021 bool Thread::is_lock_owned(address adr) const {
1022 return on_local_stack(adr);
1023 }
1024
1025 bool Thread::set_as_starting_thread() {
1026 // NOTE: this must be called inside the main thread.
1027 return os::create_main_thread((JavaThread*)this);
1028 }
1029
1030 static void initialize_class(Symbol* class_name, TRAPS) {
1031 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1032 InstanceKlass::cast(klass)->initialize(CHECK);
1033 }
1034
1035
1036 // Creates the initial ThreadGroup
1037 static Handle create_initial_thread_group(TRAPS) {
1038 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1039 InstanceKlass* ik = InstanceKlass::cast(k);
1040
1041 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1042 {
1043 JavaValue result(T_VOID);
1044 JavaCalls::call_special(&result,
1045 system_instance,
1046 ik,
1047 vmSymbols::object_initializer_name(),
1048 vmSymbols::void_method_signature(),
1049 CHECK_NH);
1050 }
1051 Universe::set_system_thread_group(system_instance());
1052
1053 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1054 {
1055 JavaValue result(T_VOID);
1056 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1057 JavaCalls::call_special(&result,
1058 main_instance,
1059 ik,
1060 vmSymbols::object_initializer_name(),
1061 vmSymbols::threadgroup_string_void_signature(),
1062 system_instance,
1063 string,
1064 CHECK_NH);
1065 }
1066 return main_instance;
1067 }
1068
1069 // Creates the initial Thread
1070 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1071 TRAPS) {
1072 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1073 InstanceKlass* ik = InstanceKlass::cast(k);
1074 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1075
1076 java_lang_Thread::set_thread(thread_oop(), thread);
1077 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1078 thread->set_threadObj(thread_oop());
1079
1080 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1081
1082 JavaValue result(T_VOID);
1083 JavaCalls::call_special(&result, thread_oop,
1084 ik,
1085 vmSymbols::object_initializer_name(),
1086 vmSymbols::threadgroup_string_void_signature(),
1087 thread_group,
1088 string,
1089 CHECK_NULL);
1090 return thread_oop();
1091 }
1092
1093 char java_runtime_name[128] = "";
1094 char java_runtime_version[128] = "";
1095
1096 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1097 static const char* get_java_runtime_name(TRAPS) {
1098 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1099 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1100 fieldDescriptor fd;
1101 bool found = k != NULL &&
1102 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1103 vmSymbols::string_signature(), &fd);
1104 if (found) {
1105 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1106 if (name_oop == NULL) {
1107 return NULL;
1108 }
1109 const char* name = java_lang_String::as_utf8_string(name_oop,
1110 java_runtime_name,
1111 sizeof(java_runtime_name));
1112 return name;
1113 } else {
1114 return NULL;
1115 }
1116 }
1117
1118 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1119 static const char* get_java_runtime_version(TRAPS) {
1120 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1121 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1122 fieldDescriptor fd;
1123 bool found = k != NULL &&
1124 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1125 vmSymbols::string_signature(), &fd);
1126 if (found) {
1127 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1128 if (name_oop == NULL) {
1129 return NULL;
1130 }
1131 const char* name = java_lang_String::as_utf8_string(name_oop,
1132 java_runtime_version,
1133 sizeof(java_runtime_version));
1134 return name;
1135 } else {
1136 return NULL;
1137 }
1138 }
1139
1140 // General purpose hook into Java code, run once when the VM is initialized.
1141 // The Java library method itself may be changed independently from the VM.
1142 static void call_postVMInitHook(TRAPS) {
1143 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1144 if (klass != NULL) {
1145 JavaValue result(T_VOID);
1146 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1147 vmSymbols::void_method_signature(),
1148 CHECK);
1149 }
1150 }
1151
1152 static void reset_vm_info_property(TRAPS) {
1153 // the vm info string
1154 ResourceMark rm(THREAD);
1155 const char *vm_info = VM_Version::vm_info_string();
1156
1157 // java.lang.System class
1158 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1159
1160 // setProperty arguments
1161 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1162 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1163
1164 // return value
1165 JavaValue r(T_OBJECT);
1166
1167 // public static String setProperty(String key, String value);
1168 JavaCalls::call_static(&r,
1169 klass,
1170 vmSymbols::setProperty_name(),
1171 vmSymbols::string_string_string_signature(),
1172 key_str,
1173 value_str,
1174 CHECK);
1175 }
1176
1177
1178 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1179 bool daemon, TRAPS) {
1180 assert(thread_group.not_null(), "thread group should be specified");
1181 assert(threadObj() == NULL, "should only create Java thread object once");
1182
1183 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1184 InstanceKlass* ik = InstanceKlass::cast(k);
1185 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1186
1187 java_lang_Thread::set_thread(thread_oop(), this);
1188 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1189 set_threadObj(thread_oop());
1190
1191 JavaValue result(T_VOID);
1192 if (thread_name != NULL) {
1193 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1194 // Thread gets assigned specified name and null target
1195 JavaCalls::call_special(&result,
1196 thread_oop,
1197 ik,
1198 vmSymbols::object_initializer_name(),
1199 vmSymbols::threadgroup_string_void_signature(),
1200 thread_group, // Argument 1
1201 name, // Argument 2
1202 THREAD);
1203 } else {
1204 // Thread gets assigned name "Thread-nnn" and null target
1205 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1206 JavaCalls::call_special(&result,
1207 thread_oop,
1208 ik,
1209 vmSymbols::object_initializer_name(),
1210 vmSymbols::threadgroup_runnable_void_signature(),
1211 thread_group, // Argument 1
1212 Handle(), // Argument 2
1213 THREAD);
1214 }
1215
1216
1217 if (daemon) {
1218 java_lang_Thread::set_daemon(thread_oop());
1219 }
1220
1221 if (HAS_PENDING_EXCEPTION) {
1222 return;
1223 }
1224
1225 Klass* group = SystemDictionary::ThreadGroup_klass();
1226 Handle threadObj(THREAD, this->threadObj());
1227
1228 JavaCalls::call_special(&result,
1229 thread_group,
1230 group,
1231 vmSymbols::add_method_name(),
1232 vmSymbols::thread_void_signature(),
1233 threadObj, // Arg 1
1234 THREAD);
1235 }
1236
1237 // NamedThread -- non-JavaThread subclasses with multiple
1238 // uniquely named instances should derive from this.
1239 NamedThread::NamedThread() : Thread() {
1240 _name = NULL;
1241 _processed_thread = NULL;
1242 _gc_id = GCId::undefined();
1243 }
1244
1245 NamedThread::~NamedThread() {
1246 if (_name != NULL) {
1247 FREE_C_HEAP_ARRAY(char, _name);
1248 _name = NULL;
1249 }
1250 }
1251
1252 void NamedThread::set_name(const char* format, ...) {
1253 guarantee(_name == NULL, "Only get to set name once.");
1254 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1255 guarantee(_name != NULL, "alloc failure");
1256 va_list ap;
1257 va_start(ap, format);
1258 jio_vsnprintf(_name, max_name_len, format, ap);
1259 va_end(ap);
1260 }
1261
1262 void NamedThread::initialize_named_thread() {
1263 set_native_thread_name(name());
1264 }
1265
1266 void NamedThread::print_on(outputStream* st) const {
1267 st->print("\"%s\" ", name());
1268 Thread::print_on(st);
1269 st->cr();
1270 }
1271
1272
1273 // ======= WatcherThread ========
1274
1275 // The watcher thread exists to simulate timer interrupts. It should
1276 // be replaced by an abstraction over whatever native support for
1277 // timer interrupts exists on the platform.
1278
1279 WatcherThread* WatcherThread::_watcher_thread = NULL;
1280 bool WatcherThread::_startable = false;
1281 volatile bool WatcherThread::_should_terminate = false;
1282
1283 WatcherThread::WatcherThread() : Thread() {
1284 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1285 if (os::create_thread(this, os::watcher_thread)) {
1286 _watcher_thread = this;
1287
1288 // Set the watcher thread to the highest OS priority which should not be
1289 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1290 // is created. The only normal thread using this priority is the reference
1291 // handler thread, which runs for very short intervals only.
1292 // If the VMThread's priority is not lower than the WatcherThread profiling
1293 // will be inaccurate.
1294 os::set_priority(this, MaxPriority);
1295 if (!DisableStartThread) {
1296 os::start_thread(this);
1297 }
1298 }
1299 }
1300
1301 int WatcherThread::sleep() const {
1302 // The WatcherThread does not participate in the safepoint protocol
1303 // for the PeriodicTask_lock because it is not a JavaThread.
1304 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1305
1306 if (_should_terminate) {
1307 // check for termination before we do any housekeeping or wait
1308 return 0; // we did not sleep.
1309 }
1310
1311 // remaining will be zero if there are no tasks,
1312 // causing the WatcherThread to sleep until a task is
1313 // enrolled
1314 int remaining = PeriodicTask::time_to_wait();
1315 int time_slept = 0;
1316
1317 // we expect this to timeout - we only ever get unparked when
1318 // we should terminate or when a new task has been enrolled
1319 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1320
1321 jlong time_before_loop = os::javaTimeNanos();
1322
1323 while (true) {
1324 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1325 remaining);
1326 jlong now = os::javaTimeNanos();
1327
1328 if (remaining == 0) {
1329 // if we didn't have any tasks we could have waited for a long time
1330 // consider the time_slept zero and reset time_before_loop
1331 time_slept = 0;
1332 time_before_loop = now;
1333 } else {
1334 // need to recalculate since we might have new tasks in _tasks
1335 time_slept = (int) ((now - time_before_loop) / 1000000);
1336 }
1337
1338 // Change to task list or spurious wakeup of some kind
1339 if (timedout || _should_terminate) {
1340 break;
1341 }
1342
1343 remaining = PeriodicTask::time_to_wait();
1344 if (remaining == 0) {
1345 // Last task was just disenrolled so loop around and wait until
1346 // another task gets enrolled
1347 continue;
1348 }
1349
1350 remaining -= time_slept;
1351 if (remaining <= 0) {
1352 break;
1353 }
1354 }
1355
1356 return time_slept;
1357 }
1358
1359 void WatcherThread::run() {
1360 assert(this == watcher_thread(), "just checking");
1361
1362 this->record_stack_base_and_size();
1363 this->set_native_thread_name(this->name());
1364 this->set_active_handles(JNIHandleBlock::allocate_block());
1365 while (true) {
1366 assert(watcher_thread() == Thread::current(), "thread consistency check");
1367 assert(watcher_thread() == this, "thread consistency check");
1368
1369 // Calculate how long it'll be until the next PeriodicTask work
1370 // should be done, and sleep that amount of time.
1371 int time_waited = sleep();
1372
1373 if (VMError::is_error_reported()) {
1374 // A fatal error has happened, the error handler(VMError::report_and_die)
1375 // should abort JVM after creating an error log file. However in some
1376 // rare cases, the error handler itself might deadlock. Here periodically
1377 // check for error reporting timeouts, and if it happens, just proceed to
1378 // abort the VM.
1379
1380 // This code is in WatcherThread because WatcherThread wakes up
1381 // periodically so the fatal error handler doesn't need to do anything;
1382 // also because the WatcherThread is less likely to crash than other
1383 // threads.
1384
1385 for (;;) {
1386 // Note: we use naked sleep in this loop because we want to avoid using
1387 // any kind of VM infrastructure which may be broken at this point.
1388 if (VMError::check_timeout()) {
1389 // We hit error reporting timeout. Error reporting was interrupted and
1390 // will be wrapping things up now (closing files etc). Give it some more
1391 // time, then quit the VM.
1392 os::naked_short_sleep(200);
1393 // Print a message to stderr.
1394 fdStream err(defaultStream::output_fd());
1395 err.print_raw_cr("# [ timer expired, abort... ]");
1396 // skip atexit/vm_exit/vm_abort hooks
1397 os::die();
1398 }
1399
1400 // Wait a second, then recheck for timeout.
1401 os::naked_short_sleep(999);
1402 }
1403 }
1404
1405 if (_should_terminate) {
1406 // check for termination before posting the next tick
1407 break;
1408 }
1409
1410 PeriodicTask::real_time_tick(time_waited);
1411 }
1412
1413 // Signal that it is terminated
1414 {
1415 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1416 _watcher_thread = NULL;
1417 Terminator_lock->notify();
1418 }
1419 }
1420
1421 void WatcherThread::start() {
1422 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1423
1424 if (watcher_thread() == NULL && _startable) {
1425 _should_terminate = false;
1426 // Create the single instance of WatcherThread
1427 new WatcherThread();
1428 }
1429 }
1430
1431 void WatcherThread::make_startable() {
1432 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1433 _startable = true;
1434 }
1435
1436 void WatcherThread::stop() {
1437 {
1438 // Follow normal safepoint aware lock enter protocol since the
1439 // WatcherThread is stopped by another JavaThread.
1440 MutexLocker ml(PeriodicTask_lock);
1441 _should_terminate = true;
1442
1443 WatcherThread* watcher = watcher_thread();
1444 if (watcher != NULL) {
1445 // unpark the WatcherThread so it can see that it should terminate
1446 watcher->unpark();
1447 }
1448 }
1449
1450 MutexLocker mu(Terminator_lock);
1451
1452 while (watcher_thread() != NULL) {
1453 // This wait should make safepoint checks, wait without a timeout,
1454 // and wait as a suspend-equivalent condition.
1455 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1456 Mutex::_as_suspend_equivalent_flag);
1457 }
1458 }
1459
1460 void WatcherThread::unpark() {
1461 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1462 PeriodicTask_lock->notify();
1463 }
1464
1465 void WatcherThread::print_on(outputStream* st) const {
1466 st->print("\"%s\" ", name());
1467 Thread::print_on(st);
1468 st->cr();
1469 }
1470
1471 // ======= JavaThread ========
1472
1473 #if INCLUDE_JVMCI
1474
1475 jlong* JavaThread::_jvmci_old_thread_counters;
1476
1477 bool jvmci_counters_include(JavaThread* thread) {
1478 oop threadObj = thread->threadObj();
1479 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1480 }
1481
1482 void JavaThread::collect_counters(typeArrayOop array) {
1483 if (JVMCICounterSize > 0) {
1484 MutexLocker tl(Threads_lock);
1485 JavaThreadIteratorWithHandle jtiwh;
1486 for (int i = 0; i < array->length(); i++) {
1487 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1488 }
1489 for (; JavaThread *tp = jtiwh.next(); ) {
1490 if (jvmci_counters_include(tp)) {
1491 for (int i = 0; i < array->length(); i++) {
1492 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1493 }
1494 }
1495 }
1496 }
1497 }
1498
1499 #endif // INCLUDE_JVMCI
1500
1501 // A JavaThread is a normal Java thread
1502
1503 void JavaThread::initialize() {
1504 // Initialize fields
1505
1506 set_saved_exception_pc(NULL);
1507 set_threadObj(NULL);
1508 _anchor.clear();
1509 set_entry_point(NULL);
1510 set_jni_functions(jni_functions());
1511 set_callee_target(NULL);
1512 set_vm_result(NULL);
1513 set_vm_result_2(NULL);
1514 set_vframe_array_head(NULL);
1515 set_vframe_array_last(NULL);
1516 set_deferred_locals(NULL);
1517 set_deopt_mark(NULL);
1518 set_deopt_compiled_method(NULL);
1519 clear_must_deopt_id();
1520 set_monitor_chunks(NULL);
1521 set_next(NULL);
1522 _on_thread_list = false;
1523 set_thread_state(_thread_new);
1524 _terminated = _not_terminated;
1525 _privileged_stack_top = NULL;
1526 _array_for_gc = NULL;
1527 _suspend_equivalent = false;
1528 _in_deopt_handler = 0;
1529 _doing_unsafe_access = false;
1530 _stack_guard_state = stack_guard_unused;
1531 #if INCLUDE_JVMCI
1532 _pending_monitorenter = false;
1533 _pending_deoptimization = -1;
1534 _pending_failed_speculation = NULL;
1535 _pending_transfer_to_interpreter = false;
1536 _adjusting_comp_level = false;
1537 _jvmci._alternate_call_target = NULL;
1538 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1539 if (JVMCICounterSize > 0) {
1540 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1541 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1542 } else {
1543 _jvmci_counters = NULL;
1544 }
1545 #endif // INCLUDE_JVMCI
1546 _reserved_stack_activation = NULL; // stack base not known yet
1547 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1548 _exception_pc = 0;
1549 _exception_handler_pc = 0;
1550 _is_method_handle_return = 0;
1551 _jvmti_thread_state= NULL;
1552 _should_post_on_exceptions_flag = JNI_FALSE;
1553 _jvmti_get_loaded_classes_closure = NULL;
1554 _interp_only_mode = 0;
1555 _special_runtime_exit_condition = _no_async_condition;
1556 _pending_async_exception = NULL;
1557 _thread_stat = NULL;
1558 _thread_stat = new ThreadStatistics();
1559 _blocked_on_compilation = false;
1560 _jni_active_critical = 0;
1561 _pending_jni_exception_check_fn = NULL;
1562 _do_not_unlock_if_synchronized = false;
1563 _cached_monitor_info = NULL;
1564 _parker = Parker::Allocate(this);
1565
1566 #ifndef PRODUCT
1567 _jmp_ring_index = 0;
1568 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1569 record_jump(NULL, NULL, NULL, 0);
1570 }
1571 #endif // PRODUCT
1572
1573 // Setup safepoint state info for this thread
1574 ThreadSafepointState::create(this);
1575
1576 debug_only(_java_call_counter = 0);
1577
1578 // JVMTI PopFrame support
1579 _popframe_condition = popframe_inactive;
1580 _popframe_preserved_args = NULL;
1581 _popframe_preserved_args_size = 0;
1582 _frames_to_pop_failed_realloc = 0;
1583
1584 if (SafepointMechanism::uses_thread_local_poll()) {
1585 SafepointMechanism::initialize_header(this);
1586 }
1587
1588 pd_initialize();
1589 }
1590
1591 #if INCLUDE_ALL_GCS
1592 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1593 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1594 #endif // INCLUDE_ALL_GCS
1595
1596 JavaThread::JavaThread(bool is_attaching_via_jni) :
1597 Thread()
1598 #if INCLUDE_ALL_GCS
1599 , _satb_mark_queue(&_satb_mark_queue_set),
1600 _dirty_card_queue(&_dirty_card_queue_set)
1601 #endif // INCLUDE_ALL_GCS
1602 {
1603 initialize();
1604 if (is_attaching_via_jni) {
1605 _jni_attach_state = _attaching_via_jni;
1606 } else {
1607 _jni_attach_state = _not_attaching_via_jni;
1608 }
1609 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1610 }
1611
1612 bool JavaThread::reguard_stack(address cur_sp) {
1613 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1614 && _stack_guard_state != stack_guard_reserved_disabled) {
1615 return true; // Stack already guarded or guard pages not needed.
1616 }
1617
1618 if (register_stack_overflow()) {
1619 // For those architectures which have separate register and
1620 // memory stacks, we must check the register stack to see if
1621 // it has overflowed.
1622 return false;
1623 }
1624
1625 // Java code never executes within the yellow zone: the latter is only
1626 // there to provoke an exception during stack banging. If java code
1627 // is executing there, either StackShadowPages should be larger, or
1628 // some exception code in c1, c2 or the interpreter isn't unwinding
1629 // when it should.
1630 guarantee(cur_sp > stack_reserved_zone_base(),
1631 "not enough space to reguard - increase StackShadowPages");
1632 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1633 enable_stack_yellow_reserved_zone();
1634 if (reserved_stack_activation() != stack_base()) {
1635 set_reserved_stack_activation(stack_base());
1636 }
1637 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1638 set_reserved_stack_activation(stack_base());
1639 enable_stack_reserved_zone();
1640 }
1641 return true;
1642 }
1643
1644 bool JavaThread::reguard_stack(void) {
1645 return reguard_stack(os::current_stack_pointer());
1646 }
1647
1648
1649 void JavaThread::block_if_vm_exited() {
1650 if (_terminated == _vm_exited) {
1651 // _vm_exited is set at safepoint, and Threads_lock is never released
1652 // we will block here forever
1653 Threads_lock->lock_without_safepoint_check();
1654 ShouldNotReachHere();
1655 }
1656 }
1657
1658
1659 // Remove this ifdef when C1 is ported to the compiler interface.
1660 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1661 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1662
1663 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1664 Thread()
1665 #if INCLUDE_ALL_GCS
1666 , _satb_mark_queue(&_satb_mark_queue_set),
1667 _dirty_card_queue(&_dirty_card_queue_set)
1668 #endif // INCLUDE_ALL_GCS
1669 {
1670 initialize();
1671 _jni_attach_state = _not_attaching_via_jni;
1672 set_entry_point(entry_point);
1673 // Create the native thread itself.
1674 // %note runtime_23
1675 os::ThreadType thr_type = os::java_thread;
1676 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1677 os::java_thread;
1678 os::create_thread(this, thr_type, stack_sz);
1679 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1680 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1681 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1682 // the exception consists of creating the exception object & initializing it, initialization
1683 // will leave the VM via a JavaCall and then all locks must be unlocked).
1684 //
1685 // The thread is still suspended when we reach here. Thread must be explicit started
1686 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1687 // by calling Threads:add. The reason why this is not done here, is because the thread
1688 // object must be fully initialized (take a look at JVM_Start)
1689 }
1690
1691 JavaThread::~JavaThread() {
1692
1693 // JSR166 -- return the parker to the free list
1694 Parker::Release(_parker);
1695 _parker = NULL;
1696
1697 // Free any remaining previous UnrollBlock
1698 vframeArray* old_array = vframe_array_last();
1699
1700 if (old_array != NULL) {
1701 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1702 old_array->set_unroll_block(NULL);
1703 delete old_info;
1704 delete old_array;
1705 }
1706
1707 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1708 if (deferred != NULL) {
1709 // This can only happen if thread is destroyed before deoptimization occurs.
1710 assert(deferred->length() != 0, "empty array!");
1711 do {
1712 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1713 deferred->remove_at(0);
1714 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1715 delete dlv;
1716 } while (deferred->length() != 0);
1717 delete deferred;
1718 }
1719
1720 // All Java related clean up happens in exit
1721 ThreadSafepointState::destroy(this);
1722 if (_thread_stat != NULL) delete _thread_stat;
1723
1724 #if INCLUDE_JVMCI
1725 if (JVMCICounterSize > 0) {
1726 if (jvmci_counters_include(this)) {
1727 for (int i = 0; i < JVMCICounterSize; i++) {
1728 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1729 }
1730 }
1731 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1732 }
1733 #endif // INCLUDE_JVMCI
1734 }
1735
1736
1737 // The first routine called by a new Java thread
1738 void JavaThread::run() {
1739 // initialize thread-local alloc buffer related fields
1740 this->initialize_tlab();
1741
1742 // used to test validity of stack trace backs
1743 this->record_base_of_stack_pointer();
1744
1745 // Record real stack base and size.
1746 this->record_stack_base_and_size();
1747
1748 this->create_stack_guard_pages();
1749
1750 this->cache_global_variables();
1751
1752 // Thread is now sufficient initialized to be handled by the safepoint code as being
1753 // in the VM. Change thread state from _thread_new to _thread_in_vm
1754 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1755
1756 assert(JavaThread::current() == this, "sanity check");
1757 assert(!Thread::current()->owns_locks(), "sanity check");
1758
1759 DTRACE_THREAD_PROBE(start, this);
1760
1761 // This operation might block. We call that after all safepoint checks for a new thread has
1762 // been completed.
1763 this->set_active_handles(JNIHandleBlock::allocate_block());
1764
1765 if (JvmtiExport::should_post_thread_life()) {
1766 JvmtiExport::post_thread_start(this);
1767 }
1768
1769 EventThreadStart event;
1770 if (event.should_commit()) {
1771 event.set_thread(THREAD_TRACE_ID(this));
1772 event.commit();
1773 }
1774
1775 // We call another function to do the rest so we are sure that the stack addresses used
1776 // from there will be lower than the stack base just computed
1777 thread_main_inner();
1778
1779 // Note, thread is no longer valid at this point!
1780 }
1781
1782
1783 void JavaThread::thread_main_inner() {
1784 assert(JavaThread::current() == this, "sanity check");
1785 assert(this->threadObj() != NULL, "just checking");
1786
1787 // Execute thread entry point unless this thread has a pending exception
1788 // or has been stopped before starting.
1789 // Note: Due to JVM_StopThread we can have pending exceptions already!
1790 if (!this->has_pending_exception() &&
1791 !java_lang_Thread::is_stillborn(this->threadObj())) {
1792 {
1793 ResourceMark rm(this);
1794 this->set_native_thread_name(this->get_thread_name());
1795 }
1796 HandleMark hm(this);
1797 this->entry_point()(this, this);
1798 }
1799
1800 DTRACE_THREAD_PROBE(stop, this);
1801
1802 this->exit(false);
1803 this->smr_delete();
1804 }
1805
1806
1807 static void ensure_join(JavaThread* thread) {
1808 // We do not need to grab the Threads_lock, since we are operating on ourself.
1809 Handle threadObj(thread, thread->threadObj());
1810 assert(threadObj.not_null(), "java thread object must exist");
1811 ObjectLocker lock(threadObj, thread);
1812 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1813 thread->clear_pending_exception();
1814 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1815 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1816 // Clear the native thread instance - this makes isAlive return false and allows the join()
1817 // to complete once we've done the notify_all below
1818 java_lang_Thread::set_thread(threadObj(), NULL);
1819 lock.notify_all(thread);
1820 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1821 thread->clear_pending_exception();
1822 }
1823
1824
1825 // For any new cleanup additions, please check to see if they need to be applied to
1826 // cleanup_failed_attach_current_thread as well.
1827 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1828 assert(this == JavaThread::current(), "thread consistency check");
1829
1830 elapsedTimer _timer_exit_phase1;
1831 elapsedTimer _timer_exit_phase2;
1832 elapsedTimer _timer_exit_phase3;
1833 elapsedTimer _timer_exit_phase4;
1834
1835 if (log_is_enabled(Debug, os, thread, timer)) {
1836 _timer_exit_phase1.start();
1837 }
1838
1839 HandleMark hm(this);
1840 Handle uncaught_exception(this, this->pending_exception());
1841 this->clear_pending_exception();
1842 Handle threadObj(this, this->threadObj());
1843 assert(threadObj.not_null(), "Java thread object should be created");
1844
1845 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1846 {
1847 EXCEPTION_MARK;
1848
1849 CLEAR_PENDING_EXCEPTION;
1850 }
1851 if (!destroy_vm) {
1852 if (uncaught_exception.not_null()) {
1853 EXCEPTION_MARK;
1854 // Call method Thread.dispatchUncaughtException().
1855 Klass* thread_klass = SystemDictionary::Thread_klass();
1856 JavaValue result(T_VOID);
1857 JavaCalls::call_virtual(&result,
1858 threadObj, thread_klass,
1859 vmSymbols::dispatchUncaughtException_name(),
1860 vmSymbols::throwable_void_signature(),
1861 uncaught_exception,
1862 THREAD);
1863 if (HAS_PENDING_EXCEPTION) {
1864 ResourceMark rm(this);
1865 jio_fprintf(defaultStream::error_stream(),
1866 "\nException: %s thrown from the UncaughtExceptionHandler"
1867 " in thread \"%s\"\n",
1868 pending_exception()->klass()->external_name(),
1869 get_thread_name());
1870 CLEAR_PENDING_EXCEPTION;
1871 }
1872 }
1873
1874 // Called before the java thread exit since we want to read info
1875 // from java_lang_Thread object
1876 EventThreadEnd event;
1877 if (event.should_commit()) {
1878 event.set_thread(THREAD_TRACE_ID(this));
1879 event.commit();
1880 }
1881
1882 // Call after last event on thread
1883 EVENT_THREAD_EXIT(this);
1884
1885 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1886 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1887 // is deprecated anyhow.
1888 if (!is_Compiler_thread()) {
1889 int count = 3;
1890 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1891 EXCEPTION_MARK;
1892 JavaValue result(T_VOID);
1893 Klass* thread_klass = SystemDictionary::Thread_klass();
1894 JavaCalls::call_virtual(&result,
1895 threadObj, thread_klass,
1896 vmSymbols::exit_method_name(),
1897 vmSymbols::void_method_signature(),
1898 THREAD);
1899 CLEAR_PENDING_EXCEPTION;
1900 }
1901 }
1902 // notify JVMTI
1903 if (JvmtiExport::should_post_thread_life()) {
1904 JvmtiExport::post_thread_end(this);
1905 }
1906
1907 // We have notified the agents that we are exiting, before we go on,
1908 // we must check for a pending external suspend request and honor it
1909 // in order to not surprise the thread that made the suspend request.
1910 while (true) {
1911 {
1912 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1913 if (!is_external_suspend()) {
1914 set_terminated(_thread_exiting);
1915 ThreadService::current_thread_exiting(this);
1916 break;
1917 }
1918 // Implied else:
1919 // Things get a little tricky here. We have a pending external
1920 // suspend request, but we are holding the SR_lock so we
1921 // can't just self-suspend. So we temporarily drop the lock
1922 // and then self-suspend.
1923 }
1924
1925 ThreadBlockInVM tbivm(this);
1926 java_suspend_self();
1927
1928 // We're done with this suspend request, but we have to loop around
1929 // and check again. Eventually we will get SR_lock without a pending
1930 // external suspend request and will be able to mark ourselves as
1931 // exiting.
1932 }
1933 // no more external suspends are allowed at this point
1934 } else {
1935 // before_exit() has already posted JVMTI THREAD_END events
1936 }
1937
1938 if (log_is_enabled(Debug, os, thread, timer)) {
1939 _timer_exit_phase1.stop();
1940 _timer_exit_phase2.start();
1941 }
1942 // Notify waiters on thread object. This has to be done after exit() is called
1943 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1944 // group should have the destroyed bit set before waiters are notified).
1945 ensure_join(this);
1946 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1947
1948 if (log_is_enabled(Debug, os, thread, timer)) {
1949 _timer_exit_phase2.stop();
1950 _timer_exit_phase3.start();
1951 }
1952 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1953 // held by this thread must be released. The spec does not distinguish
1954 // between JNI-acquired and regular Java monitors. We can only see
1955 // regular Java monitors here if monitor enter-exit matching is broken.
1956 //
1957 // Optionally release any monitors for regular JavaThread exits. This
1958 // is provided as a work around for any bugs in monitor enter-exit
1959 // matching. This can be expensive so it is not enabled by default.
1960 //
1961 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1962 // ObjectSynchronizer::release_monitors_owned_by_thread().
1963 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1964 // Sanity check even though JNI DetachCurrentThread() would have
1965 // returned JNI_ERR if there was a Java frame. JavaThread exit
1966 // should be done executing Java code by the time we get here.
1967 assert(!this->has_last_Java_frame(),
1968 "should not have a Java frame when detaching or exiting");
1969 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1970 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1971 }
1972
1973 // These things needs to be done while we are still a Java Thread. Make sure that thread
1974 // is in a consistent state, in case GC happens
1975 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1976
1977 if (active_handles() != NULL) {
1978 JNIHandleBlock* block = active_handles();
1979 set_active_handles(NULL);
1980 JNIHandleBlock::release_block(block);
1981 }
1982
1983 if (free_handle_block() != NULL) {
1984 JNIHandleBlock* block = free_handle_block();
1985 set_free_handle_block(NULL);
1986 JNIHandleBlock::release_block(block);
1987 }
1988
1989 // These have to be removed while this is still a valid thread.
1990 remove_stack_guard_pages();
1991
1992 if (UseTLAB) {
1993 tlab().make_parsable(true); // retire TLAB
1994 }
1995
1996 if (JvmtiEnv::environments_might_exist()) {
1997 JvmtiExport::cleanup_thread(this);
1998 }
1999
2000 // We must flush any deferred card marks and other various GC barrier
2001 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2002 // before removing a thread from the list of active threads.
2003 BarrierSet::barrier_set()->on_thread_detach(this);
2004
2005 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2006 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2007 os::current_thread_id());
2008
2009 if (log_is_enabled(Debug, os, thread, timer)) {
2010 _timer_exit_phase3.stop();
2011 _timer_exit_phase4.start();
2012 }
2013 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2014 Threads::remove(this);
2015
2016 if (log_is_enabled(Debug, os, thread, timer)) {
2017 _timer_exit_phase4.stop();
2018 ResourceMark rm(this);
2019 log_debug(os, thread, timer)("name='%s'"
2020 ", exit-phase1=" JLONG_FORMAT
2021 ", exit-phase2=" JLONG_FORMAT
2022 ", exit-phase3=" JLONG_FORMAT
2023 ", exit-phase4=" JLONG_FORMAT,
2024 get_thread_name(),
2025 _timer_exit_phase1.milliseconds(),
2026 _timer_exit_phase2.milliseconds(),
2027 _timer_exit_phase3.milliseconds(),
2028 _timer_exit_phase4.milliseconds());
2029 }
2030 }
2031
2032 void JavaThread::cleanup_failed_attach_current_thread() {
2033 if (active_handles() != NULL) {
2034 JNIHandleBlock* block = active_handles();
2035 set_active_handles(NULL);
2036 JNIHandleBlock::release_block(block);
2037 }
2038
2039 if (free_handle_block() != NULL) {
2040 JNIHandleBlock* block = free_handle_block();
2041 set_free_handle_block(NULL);
2042 JNIHandleBlock::release_block(block);
2043 }
2044
2045 // These have to be removed while this is still a valid thread.
2046 remove_stack_guard_pages();
2047
2048 if (UseTLAB) {
2049 tlab().make_parsable(true); // retire TLAB, if any
2050 }
2051
2052 BarrierSet::barrier_set()->on_thread_detach(this);
2053
2054 Threads::remove(this);
2055 this->smr_delete();
2056 }
2057
2058 JavaThread* JavaThread::active() {
2059 Thread* thread = Thread::current();
2060 if (thread->is_Java_thread()) {
2061 return (JavaThread*) thread;
2062 } else {
2063 assert(thread->is_VM_thread(), "this must be a vm thread");
2064 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2065 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2066 assert(ret->is_Java_thread(), "must be a Java thread");
2067 return ret;
2068 }
2069 }
2070
2071 bool JavaThread::is_lock_owned(address adr) const {
2072 if (Thread::is_lock_owned(adr)) return true;
2073
2074 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2075 if (chunk->contains(adr)) return true;
2076 }
2077
2078 return false;
2079 }
2080
2081
2082 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2083 chunk->set_next(monitor_chunks());
2084 set_monitor_chunks(chunk);
2085 }
2086
2087 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2088 guarantee(monitor_chunks() != NULL, "must be non empty");
2089 if (monitor_chunks() == chunk) {
2090 set_monitor_chunks(chunk->next());
2091 } else {
2092 MonitorChunk* prev = monitor_chunks();
2093 while (prev->next() != chunk) prev = prev->next();
2094 prev->set_next(chunk->next());
2095 }
2096 }
2097
2098 // JVM support.
2099
2100 // Note: this function shouldn't block if it's called in
2101 // _thread_in_native_trans state (such as from
2102 // check_special_condition_for_native_trans()).
2103 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2104
2105 if (has_last_Java_frame() && has_async_condition()) {
2106 // If we are at a polling page safepoint (not a poll return)
2107 // then we must defer async exception because live registers
2108 // will be clobbered by the exception path. Poll return is
2109 // ok because the call we a returning from already collides
2110 // with exception handling registers and so there is no issue.
2111 // (The exception handling path kills call result registers but
2112 // this is ok since the exception kills the result anyway).
2113
2114 if (is_at_poll_safepoint()) {
2115 // if the code we are returning to has deoptimized we must defer
2116 // the exception otherwise live registers get clobbered on the
2117 // exception path before deoptimization is able to retrieve them.
2118 //
2119 RegisterMap map(this, false);
2120 frame caller_fr = last_frame().sender(&map);
2121 assert(caller_fr.is_compiled_frame(), "what?");
2122 if (caller_fr.is_deoptimized_frame()) {
2123 log_info(exceptions)("deferred async exception at compiled safepoint");
2124 return;
2125 }
2126 }
2127 }
2128
2129 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2130 if (condition == _no_async_condition) {
2131 // Conditions have changed since has_special_runtime_exit_condition()
2132 // was called:
2133 // - if we were here only because of an external suspend request,
2134 // then that was taken care of above (or cancelled) so we are done
2135 // - if we were here because of another async request, then it has
2136 // been cleared between the has_special_runtime_exit_condition()
2137 // and now so again we are done
2138 return;
2139 }
2140
2141 // Check for pending async. exception
2142 if (_pending_async_exception != NULL) {
2143 // Only overwrite an already pending exception, if it is not a threadDeath.
2144 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2145
2146 // We cannot call Exceptions::_throw(...) here because we cannot block
2147 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2148
2149 LogTarget(Info, exceptions) lt;
2150 if (lt.is_enabled()) {
2151 ResourceMark rm;
2152 LogStream ls(lt);
2153 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2154 if (has_last_Java_frame()) {
2155 frame f = last_frame();
2156 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2157 }
2158 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2159 }
2160 _pending_async_exception = NULL;
2161 clear_has_async_exception();
2162 }
2163 }
2164
2165 if (check_unsafe_error &&
2166 condition == _async_unsafe_access_error && !has_pending_exception()) {
2167 condition = _no_async_condition; // done
2168 switch (thread_state()) {
2169 case _thread_in_vm: {
2170 JavaThread* THREAD = this;
2171 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2172 }
2173 case _thread_in_native: {
2174 ThreadInVMfromNative tiv(this);
2175 JavaThread* THREAD = this;
2176 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2177 }
2178 case _thread_in_Java: {
2179 ThreadInVMfromJava tiv(this);
2180 JavaThread* THREAD = this;
2181 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2182 }
2183 default:
2184 ShouldNotReachHere();
2185 }
2186 }
2187
2188 assert(condition == _no_async_condition || has_pending_exception() ||
2189 (!check_unsafe_error && condition == _async_unsafe_access_error),
2190 "must have handled the async condition, if no exception");
2191 }
2192
2193 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2194 //
2195 // Check for pending external suspend. Internal suspend requests do
2196 // not use handle_special_runtime_exit_condition().
2197 // If JNIEnv proxies are allowed, don't self-suspend if the target
2198 // thread is not the current thread. In older versions of jdbx, jdbx
2199 // threads could call into the VM with another thread's JNIEnv so we
2200 // can be here operating on behalf of a suspended thread (4432884).
2201 bool do_self_suspend = is_external_suspend_with_lock();
2202 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2203 //
2204 // Because thread is external suspended the safepoint code will count
2205 // thread as at a safepoint. This can be odd because we can be here
2206 // as _thread_in_Java which would normally transition to _thread_blocked
2207 // at a safepoint. We would like to mark the thread as _thread_blocked
2208 // before calling java_suspend_self like all other callers of it but
2209 // we must then observe proper safepoint protocol. (We can't leave
2210 // _thread_blocked with a safepoint in progress). However we can be
2211 // here as _thread_in_native_trans so we can't use a normal transition
2212 // constructor/destructor pair because they assert on that type of
2213 // transition. We could do something like:
2214 //
2215 // JavaThreadState state = thread_state();
2216 // set_thread_state(_thread_in_vm);
2217 // {
2218 // ThreadBlockInVM tbivm(this);
2219 // java_suspend_self()
2220 // }
2221 // set_thread_state(_thread_in_vm_trans);
2222 // if (safepoint) block;
2223 // set_thread_state(state);
2224 //
2225 // but that is pretty messy. Instead we just go with the way the
2226 // code has worked before and note that this is the only path to
2227 // java_suspend_self that doesn't put the thread in _thread_blocked
2228 // mode.
2229
2230 frame_anchor()->make_walkable(this);
2231 java_suspend_self();
2232
2233 // We might be here for reasons in addition to the self-suspend request
2234 // so check for other async requests.
2235 }
2236
2237 if (check_asyncs) {
2238 check_and_handle_async_exceptions();
2239 }
2240 #if INCLUDE_TRACE
2241 if (is_trace_suspend()) {
2242 TRACE_SUSPEND_THREAD(this);
2243 }
2244 #endif
2245 }
2246
2247 void JavaThread::send_thread_stop(oop java_throwable) {
2248 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2249 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2250 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2251
2252 // Do not throw asynchronous exceptions against the compiler thread
2253 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2254 if (!can_call_java()) return;
2255
2256 {
2257 // Actually throw the Throwable against the target Thread - however
2258 // only if there is no thread death exception installed already.
2259 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2260 // If the topmost frame is a runtime stub, then we are calling into
2261 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2262 // must deoptimize the caller before continuing, as the compiled exception handler table
2263 // may not be valid
2264 if (has_last_Java_frame()) {
2265 frame f = last_frame();
2266 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2267 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2268 RegisterMap reg_map(this, UseBiasedLocking);
2269 frame compiled_frame = f.sender(®_map);
2270 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2271 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2272 }
2273 }
2274 }
2275
2276 // Set async. pending exception in thread.
2277 set_pending_async_exception(java_throwable);
2278
2279 if (log_is_enabled(Info, exceptions)) {
2280 ResourceMark rm;
2281 log_info(exceptions)("Pending Async. exception installed of type: %s",
2282 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2283 }
2284 // for AbortVMOnException flag
2285 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2286 }
2287 }
2288
2289
2290 // Interrupt thread so it will wake up from a potential wait()
2291 Thread::interrupt(this);
2292 }
2293
2294 // External suspension mechanism.
2295 //
2296 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2297 // to any VM_locks and it is at a transition
2298 // Self-suspension will happen on the transition out of the vm.
2299 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2300 //
2301 // Guarantees on return:
2302 // + Target thread will not execute any new bytecode (that's why we need to
2303 // force a safepoint)
2304 // + Target thread will not enter any new monitors
2305 //
2306 void JavaThread::java_suspend() {
2307 ThreadsListHandle tlh;
2308 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2309 return;
2310 }
2311
2312 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2313 if (!is_external_suspend()) {
2314 // a racing resume has cancelled us; bail out now
2315 return;
2316 }
2317
2318 // suspend is done
2319 uint32_t debug_bits = 0;
2320 // Warning: is_ext_suspend_completed() may temporarily drop the
2321 // SR_lock to allow the thread to reach a stable thread state if
2322 // it is currently in a transient thread state.
2323 if (is_ext_suspend_completed(false /* !called_by_wait */,
2324 SuspendRetryDelay, &debug_bits)) {
2325 return;
2326 }
2327 }
2328
2329 VM_ThreadSuspend vm_suspend;
2330 VMThread::execute(&vm_suspend);
2331 }
2332
2333 // Part II of external suspension.
2334 // A JavaThread self suspends when it detects a pending external suspend
2335 // request. This is usually on transitions. It is also done in places
2336 // where continuing to the next transition would surprise the caller,
2337 // e.g., monitor entry.
2338 //
2339 // Returns the number of times that the thread self-suspended.
2340 //
2341 // Note: DO NOT call java_suspend_self() when you just want to block current
2342 // thread. java_suspend_self() is the second stage of cooperative
2343 // suspension for external suspend requests and should only be used
2344 // to complete an external suspend request.
2345 //
2346 int JavaThread::java_suspend_self() {
2347 int ret = 0;
2348
2349 // we are in the process of exiting so don't suspend
2350 if (is_exiting()) {
2351 clear_external_suspend();
2352 return ret;
2353 }
2354
2355 assert(_anchor.walkable() ||
2356 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2357 "must have walkable stack");
2358
2359 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2360
2361 assert(!this->is_ext_suspended(),
2362 "a thread trying to self-suspend should not already be suspended");
2363
2364 if (this->is_suspend_equivalent()) {
2365 // If we are self-suspending as a result of the lifting of a
2366 // suspend equivalent condition, then the suspend_equivalent
2367 // flag is not cleared until we set the ext_suspended flag so
2368 // that wait_for_ext_suspend_completion() returns consistent
2369 // results.
2370 this->clear_suspend_equivalent();
2371 }
2372
2373 // A racing resume may have cancelled us before we grabbed SR_lock
2374 // above. Or another external suspend request could be waiting for us
2375 // by the time we return from SR_lock()->wait(). The thread
2376 // that requested the suspension may already be trying to walk our
2377 // stack and if we return now, we can change the stack out from under
2378 // it. This would be a "bad thing (TM)" and cause the stack walker
2379 // to crash. We stay self-suspended until there are no more pending
2380 // external suspend requests.
2381 while (is_external_suspend()) {
2382 ret++;
2383 this->set_ext_suspended();
2384
2385 // _ext_suspended flag is cleared by java_resume()
2386 while (is_ext_suspended()) {
2387 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2388 }
2389 }
2390
2391 return ret;
2392 }
2393
2394 #ifdef ASSERT
2395 // Verify the JavaThread has not yet been published in the Threads::list, and
2396 // hence doesn't need protection from concurrent access at this stage.
2397 void JavaThread::verify_not_published() {
2398 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2399 // since an unpublished JavaThread doesn't participate in the
2400 // Thread-SMR protocol for keeping a ThreadsList alive.
2401 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2402 }
2403 #endif
2404
2405 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2406 // progress or when _suspend_flags is non-zero.
2407 // Current thread needs to self-suspend if there is a suspend request and/or
2408 // block if a safepoint is in progress.
2409 // Async exception ISN'T checked.
2410 // Note only the ThreadInVMfromNative transition can call this function
2411 // directly and when thread state is _thread_in_native_trans
2412 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2413 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2414
2415 JavaThread *curJT = JavaThread::current();
2416 bool do_self_suspend = thread->is_external_suspend();
2417
2418 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2419
2420 // If JNIEnv proxies are allowed, don't self-suspend if the target
2421 // thread is not the current thread. In older versions of jdbx, jdbx
2422 // threads could call into the VM with another thread's JNIEnv so we
2423 // can be here operating on behalf of a suspended thread (4432884).
2424 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2425 JavaThreadState state = thread->thread_state();
2426
2427 // We mark this thread_blocked state as a suspend-equivalent so
2428 // that a caller to is_ext_suspend_completed() won't be confused.
2429 // The suspend-equivalent state is cleared by java_suspend_self().
2430 thread->set_suspend_equivalent();
2431
2432 // If the safepoint code sees the _thread_in_native_trans state, it will
2433 // wait until the thread changes to other thread state. There is no
2434 // guarantee on how soon we can obtain the SR_lock and complete the
2435 // self-suspend request. It would be a bad idea to let safepoint wait for
2436 // too long. Temporarily change the state to _thread_blocked to
2437 // let the VM thread know that this thread is ready for GC. The problem
2438 // of changing thread state is that safepoint could happen just after
2439 // java_suspend_self() returns after being resumed, and VM thread will
2440 // see the _thread_blocked state. We must check for safepoint
2441 // after restoring the state and make sure we won't leave while a safepoint
2442 // is in progress.
2443 thread->set_thread_state(_thread_blocked);
2444 thread->java_suspend_self();
2445 thread->set_thread_state(state);
2446
2447 InterfaceSupport::serialize_thread_state_with_handler(thread);
2448 }
2449
2450 SafepointMechanism::block_if_requested(curJT);
2451
2452 if (thread->is_deopt_suspend()) {
2453 thread->clear_deopt_suspend();
2454 RegisterMap map(thread, false);
2455 frame f = thread->last_frame();
2456 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2457 f = f.sender(&map);
2458 }
2459 if (f.id() == thread->must_deopt_id()) {
2460 thread->clear_must_deopt_id();
2461 f.deoptimize(thread);
2462 } else {
2463 fatal("missed deoptimization!");
2464 }
2465 }
2466 #if INCLUDE_TRACE
2467 if (thread->is_trace_suspend()) {
2468 TRACE_SUSPEND_THREAD(thread);
2469 }
2470 #endif
2471 }
2472
2473 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2474 // progress or when _suspend_flags is non-zero.
2475 // Current thread needs to self-suspend if there is a suspend request and/or
2476 // block if a safepoint is in progress.
2477 // Also check for pending async exception (not including unsafe access error).
2478 // Note only the native==>VM/Java barriers can call this function and when
2479 // thread state is _thread_in_native_trans.
2480 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2481 check_safepoint_and_suspend_for_native_trans(thread);
2482
2483 if (thread->has_async_exception()) {
2484 // We are in _thread_in_native_trans state, don't handle unsafe
2485 // access error since that may block.
2486 thread->check_and_handle_async_exceptions(false);
2487 }
2488 }
2489
2490 // This is a variant of the normal
2491 // check_special_condition_for_native_trans with slightly different
2492 // semantics for use by critical native wrappers. It does all the
2493 // normal checks but also performs the transition back into
2494 // thread_in_Java state. This is required so that critical natives
2495 // can potentially block and perform a GC if they are the last thread
2496 // exiting the GCLocker.
2497 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2498 check_special_condition_for_native_trans(thread);
2499
2500 // Finish the transition
2501 thread->set_thread_state(_thread_in_Java);
2502
2503 if (thread->do_critical_native_unlock()) {
2504 ThreadInVMfromJavaNoAsyncException tiv(thread);
2505 GCLocker::unlock_critical(thread);
2506 thread->clear_critical_native_unlock();
2507 }
2508 }
2509
2510 // We need to guarantee the Threads_lock here, since resumes are not
2511 // allowed during safepoint synchronization
2512 // Can only resume from an external suspension
2513 void JavaThread::java_resume() {
2514 assert_locked_or_safepoint(Threads_lock);
2515
2516 // Sanity check: thread is gone, has started exiting or the thread
2517 // was not externally suspended.
2518 ThreadsListHandle tlh;
2519 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2520 return;
2521 }
2522
2523 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2524
2525 clear_external_suspend();
2526
2527 if (is_ext_suspended()) {
2528 clear_ext_suspended();
2529 SR_lock()->notify_all();
2530 }
2531 }
2532
2533 size_t JavaThread::_stack_red_zone_size = 0;
2534 size_t JavaThread::_stack_yellow_zone_size = 0;
2535 size_t JavaThread::_stack_reserved_zone_size = 0;
2536 size_t JavaThread::_stack_shadow_zone_size = 0;
2537
2538 void JavaThread::create_stack_guard_pages() {
2539 if (!os::uses_stack_guard_pages() ||
2540 _stack_guard_state != stack_guard_unused ||
2541 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2542 log_info(os, thread)("Stack guard page creation for thread "
2543 UINTX_FORMAT " disabled", os::current_thread_id());
2544 return;
2545 }
2546 address low_addr = stack_end();
2547 size_t len = stack_guard_zone_size();
2548
2549 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2550 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2551
2552 int must_commit = os::must_commit_stack_guard_pages();
2553 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2554
2555 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2556 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2557 return;
2558 }
2559
2560 if (os::guard_memory((char *) low_addr, len)) {
2561 _stack_guard_state = stack_guard_enabled;
2562 } else {
2563 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2564 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2565 if (os::uncommit_memory((char *) low_addr, len)) {
2566 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2567 }
2568 return;
2569 }
2570
2571 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2572 PTR_FORMAT "-" PTR_FORMAT ".",
2573 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2574 }
2575
2576 void JavaThread::remove_stack_guard_pages() {
2577 assert(Thread::current() == this, "from different thread");
2578 if (_stack_guard_state == stack_guard_unused) return;
2579 address low_addr = stack_end();
2580 size_t len = stack_guard_zone_size();
2581
2582 if (os::must_commit_stack_guard_pages()) {
2583 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2584 _stack_guard_state = stack_guard_unused;
2585 } else {
2586 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2587 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2588 return;
2589 }
2590 } else {
2591 if (_stack_guard_state == stack_guard_unused) return;
2592 if (os::unguard_memory((char *) low_addr, len)) {
2593 _stack_guard_state = stack_guard_unused;
2594 } else {
2595 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2596 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2597 return;
2598 }
2599 }
2600
2601 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2602 PTR_FORMAT "-" PTR_FORMAT ".",
2603 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2604 }
2605
2606 void JavaThread::enable_stack_reserved_zone() {
2607 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2608 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2609
2610 // The base notation is from the stack's point of view, growing downward.
2611 // We need to adjust it to work correctly with guard_memory()
2612 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2613
2614 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2615 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2616
2617 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2618 _stack_guard_state = stack_guard_enabled;
2619 } else {
2620 warning("Attempt to guard stack reserved zone failed.");
2621 }
2622 enable_register_stack_guard();
2623 }
2624
2625 void JavaThread::disable_stack_reserved_zone() {
2626 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2627 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2628
2629 // Simply return if called for a thread that does not use guard pages.
2630 if (_stack_guard_state == stack_guard_unused) return;
2631
2632 // The base notation is from the stack's point of view, growing downward.
2633 // We need to adjust it to work correctly with guard_memory()
2634 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2635
2636 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2637 _stack_guard_state = stack_guard_reserved_disabled;
2638 } else {
2639 warning("Attempt to unguard stack reserved zone failed.");
2640 }
2641 disable_register_stack_guard();
2642 }
2643
2644 void JavaThread::enable_stack_yellow_reserved_zone() {
2645 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2646 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2647
2648 // The base notation is from the stacks point of view, growing downward.
2649 // We need to adjust it to work correctly with guard_memory()
2650 address base = stack_red_zone_base();
2651
2652 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2653 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2654
2655 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2656 _stack_guard_state = stack_guard_enabled;
2657 } else {
2658 warning("Attempt to guard stack yellow zone failed.");
2659 }
2660 enable_register_stack_guard();
2661 }
2662
2663 void JavaThread::disable_stack_yellow_reserved_zone() {
2664 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2665 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2666
2667 // Simply return if called for a thread that does not use guard pages.
2668 if (_stack_guard_state == stack_guard_unused) return;
2669
2670 // The base notation is from the stacks point of view, growing downward.
2671 // We need to adjust it to work correctly with guard_memory()
2672 address base = stack_red_zone_base();
2673
2674 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2675 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2676 } else {
2677 warning("Attempt to unguard stack yellow zone failed.");
2678 }
2679 disable_register_stack_guard();
2680 }
2681
2682 void JavaThread::enable_stack_red_zone() {
2683 // The base notation is from the stacks point of view, growing downward.
2684 // We need to adjust it to work correctly with guard_memory()
2685 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2686 address base = stack_red_zone_base() - stack_red_zone_size();
2687
2688 guarantee(base < stack_base(), "Error calculating stack red zone");
2689 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2690
2691 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2692 warning("Attempt to guard stack red zone failed.");
2693 }
2694 }
2695
2696 void JavaThread::disable_stack_red_zone() {
2697 // The base notation is from the stacks point of view, growing downward.
2698 // We need to adjust it to work correctly with guard_memory()
2699 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2700 address base = stack_red_zone_base() - stack_red_zone_size();
2701 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2702 warning("Attempt to unguard stack red zone failed.");
2703 }
2704 }
2705
2706 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2707 // ignore is there is no stack
2708 if (!has_last_Java_frame()) return;
2709 // traverse the stack frames. Starts from top frame.
2710 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2711 frame* fr = fst.current();
2712 f(fr, fst.register_map());
2713 }
2714 }
2715
2716
2717 #ifndef PRODUCT
2718 // Deoptimization
2719 // Function for testing deoptimization
2720 void JavaThread::deoptimize() {
2721 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2722 StackFrameStream fst(this, UseBiasedLocking);
2723 bool deopt = false; // Dump stack only if a deopt actually happens.
2724 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2725 // Iterate over all frames in the thread and deoptimize
2726 for (; !fst.is_done(); fst.next()) {
2727 if (fst.current()->can_be_deoptimized()) {
2728
2729 if (only_at) {
2730 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2731 // consists of comma or carriage return separated numbers so
2732 // search for the current bci in that string.
2733 address pc = fst.current()->pc();
2734 nmethod* nm = (nmethod*) fst.current()->cb();
2735 ScopeDesc* sd = nm->scope_desc_at(pc);
2736 char buffer[8];
2737 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2738 size_t len = strlen(buffer);
2739 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2740 while (found != NULL) {
2741 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2742 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2743 // Check that the bci found is bracketed by terminators.
2744 break;
2745 }
2746 found = strstr(found + 1, buffer);
2747 }
2748 if (!found) {
2749 continue;
2750 }
2751 }
2752
2753 if (DebugDeoptimization && !deopt) {
2754 deopt = true; // One-time only print before deopt
2755 tty->print_cr("[BEFORE Deoptimization]");
2756 trace_frames();
2757 trace_stack();
2758 }
2759 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2760 }
2761 }
2762
2763 if (DebugDeoptimization && deopt) {
2764 tty->print_cr("[AFTER Deoptimization]");
2765 trace_frames();
2766 }
2767 }
2768
2769
2770 // Make zombies
2771 void JavaThread::make_zombies() {
2772 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2773 if (fst.current()->can_be_deoptimized()) {
2774 // it is a Java nmethod
2775 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2776 nm->make_not_entrant();
2777 }
2778 }
2779 }
2780 #endif // PRODUCT
2781
2782
2783 void JavaThread::deoptimized_wrt_marked_nmethods() {
2784 if (!has_last_Java_frame()) return;
2785 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2786 StackFrameStream fst(this, UseBiasedLocking);
2787 for (; !fst.is_done(); fst.next()) {
2788 if (fst.current()->should_be_deoptimized()) {
2789 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2790 }
2791 }
2792 }
2793
2794
2795 // If the caller is a NamedThread, then remember, in the current scope,
2796 // the given JavaThread in its _processed_thread field.
2797 class RememberProcessedThread: public StackObj {
2798 NamedThread* _cur_thr;
2799 public:
2800 RememberProcessedThread(JavaThread* jthr) {
2801 Thread* thread = Thread::current();
2802 if (thread->is_Named_thread()) {
2803 _cur_thr = (NamedThread *)thread;
2804 _cur_thr->set_processed_thread(jthr);
2805 } else {
2806 _cur_thr = NULL;
2807 }
2808 }
2809
2810 ~RememberProcessedThread() {
2811 if (_cur_thr) {
2812 _cur_thr->set_processed_thread(NULL);
2813 }
2814 }
2815 };
2816
2817 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2818 // Verify that the deferred card marks have been flushed.
2819 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2820
2821 // Traverse the GCHandles
2822 Thread::oops_do(f, cf);
2823
2824 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2825
2826 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2827 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2828
2829 if (has_last_Java_frame()) {
2830 // Record JavaThread to GC thread
2831 RememberProcessedThread rpt(this);
2832
2833 // Traverse the privileged stack
2834 if (_privileged_stack_top != NULL) {
2835 _privileged_stack_top->oops_do(f);
2836 }
2837
2838 // traverse the registered growable array
2839 if (_array_for_gc != NULL) {
2840 for (int index = 0; index < _array_for_gc->length(); index++) {
2841 f->do_oop(_array_for_gc->adr_at(index));
2842 }
2843 }
2844
2845 // Traverse the monitor chunks
2846 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2847 chunk->oops_do(f);
2848 }
2849
2850 // Traverse the execution stack
2851 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2852 fst.current()->oops_do(f, cf, fst.register_map());
2853 }
2854 }
2855
2856 // callee_target is never live across a gc point so NULL it here should
2857 // it still contain a methdOop.
2858
2859 set_callee_target(NULL);
2860
2861 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2862 // If we have deferred set_locals there might be oops waiting to be
2863 // written
2864 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2865 if (list != NULL) {
2866 for (int i = 0; i < list->length(); i++) {
2867 list->at(i)->oops_do(f);
2868 }
2869 }
2870
2871 // Traverse instance variables at the end since the GC may be moving things
2872 // around using this function
2873 f->do_oop((oop*) &_threadObj);
2874 f->do_oop((oop*) &_vm_result);
2875 f->do_oop((oop*) &_exception_oop);
2876 f->do_oop((oop*) &_pending_async_exception);
2877
2878 if (jvmti_thread_state() != NULL) {
2879 jvmti_thread_state()->oops_do(f);
2880 }
2881 }
2882
2883 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2884 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2885 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2886
2887 if (has_last_Java_frame()) {
2888 // Traverse the execution stack
2889 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2890 fst.current()->nmethods_do(cf);
2891 }
2892 }
2893 }
2894
2895 void JavaThread::metadata_do(void f(Metadata*)) {
2896 if (has_last_Java_frame()) {
2897 // Traverse the execution stack to call f() on the methods in the stack
2898 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2899 fst.current()->metadata_do(f);
2900 }
2901 } else if (is_Compiler_thread()) {
2902 // need to walk ciMetadata in current compile tasks to keep alive.
2903 CompilerThread* ct = (CompilerThread*)this;
2904 if (ct->env() != NULL) {
2905 ct->env()->metadata_do(f);
2906 }
2907 CompileTask* task = ct->task();
2908 if (task != NULL) {
2909 task->metadata_do(f);
2910 }
2911 }
2912 }
2913
2914 // Printing
2915 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2916 switch (_thread_state) {
2917 case _thread_uninitialized: return "_thread_uninitialized";
2918 case _thread_new: return "_thread_new";
2919 case _thread_new_trans: return "_thread_new_trans";
2920 case _thread_in_native: return "_thread_in_native";
2921 case _thread_in_native_trans: return "_thread_in_native_trans";
2922 case _thread_in_vm: return "_thread_in_vm";
2923 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2924 case _thread_in_Java: return "_thread_in_Java";
2925 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2926 case _thread_blocked: return "_thread_blocked";
2927 case _thread_blocked_trans: return "_thread_blocked_trans";
2928 default: return "unknown thread state";
2929 }
2930 }
2931
2932 #ifndef PRODUCT
2933 void JavaThread::print_thread_state_on(outputStream *st) const {
2934 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2935 };
2936 void JavaThread::print_thread_state() const {
2937 print_thread_state_on(tty);
2938 }
2939 #endif // PRODUCT
2940
2941 // Called by Threads::print() for VM_PrintThreads operation
2942 void JavaThread::print_on(outputStream *st) const {
2943 st->print_raw("\"");
2944 st->print_raw(get_thread_name());
2945 st->print_raw("\" ");
2946 oop thread_oop = threadObj();
2947 if (thread_oop != NULL) {
2948 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2949 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2950 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2951 }
2952 Thread::print_on(st);
2953 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2954 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2955 if (thread_oop != NULL) {
2956 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2957 }
2958 #ifndef PRODUCT
2959 print_thread_state_on(st);
2960 _safepoint_state->print_on(st);
2961 #endif // PRODUCT
2962 if (is_Compiler_thread()) {
2963 CompileTask *task = ((CompilerThread*)this)->task();
2964 if (task != NULL) {
2965 st->print(" Compiling: ");
2966 task->print(st, NULL, true, false);
2967 } else {
2968 st->print(" No compile task");
2969 }
2970 st->cr();
2971 }
2972 }
2973
2974 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2975 st->print("%s", get_thread_name_string(buf, buflen));
2976 }
2977
2978 // Called by fatal error handler. The difference between this and
2979 // JavaThread::print() is that we can't grab lock or allocate memory.
2980 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2981 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2982 oop thread_obj = threadObj();
2983 if (thread_obj != NULL) {
2984 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2985 }
2986 st->print(" [");
2987 st->print("%s", _get_thread_state_name(_thread_state));
2988 if (osthread()) {
2989 st->print(", id=%d", osthread()->thread_id());
2990 }
2991 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2992 p2i(stack_end()), p2i(stack_base()));
2993 st->print("]");
2994
2995 if (_threads_hazard_ptr != NULL) {
2996 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
2997 }
2998 if (_nested_threads_hazard_ptr != NULL) {
2999 print_nested_threads_hazard_ptrs_on(st);
3000 }
3001 return;
3002 }
3003
3004 // Verification
3005
3006 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3007
3008 void JavaThread::verify() {
3009 // Verify oops in the thread.
3010 oops_do(&VerifyOopClosure::verify_oop, NULL);
3011
3012 // Verify the stack frames.
3013 frames_do(frame_verify);
3014 }
3015
3016 // CR 6300358 (sub-CR 2137150)
3017 // Most callers of this method assume that it can't return NULL but a
3018 // thread may not have a name whilst it is in the process of attaching to
3019 // the VM - see CR 6412693, and there are places where a JavaThread can be
3020 // seen prior to having it's threadObj set (eg JNI attaching threads and
3021 // if vm exit occurs during initialization). These cases can all be accounted
3022 // for such that this method never returns NULL.
3023 const char* JavaThread::get_thread_name() const {
3024 #ifdef ASSERT
3025 // early safepoints can hit while current thread does not yet have TLS
3026 if (!SafepointSynchronize::is_at_safepoint()) {
3027 Thread *cur = Thread::current();
3028 if (!(cur->is_Java_thread() && cur == this)) {
3029 // Current JavaThreads are allowed to get their own name without
3030 // the Threads_lock.
3031 assert_locked_or_safepoint(Threads_lock);
3032 }
3033 }
3034 #endif // ASSERT
3035 return get_thread_name_string();
3036 }
3037
3038 // Returns a non-NULL representation of this thread's name, or a suitable
3039 // descriptive string if there is no set name
3040 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3041 const char* name_str;
3042 oop thread_obj = threadObj();
3043 if (thread_obj != NULL) {
3044 oop name = java_lang_Thread::name(thread_obj);
3045 if (name != NULL) {
3046 if (buf == NULL) {
3047 name_str = java_lang_String::as_utf8_string(name);
3048 } else {
3049 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3050 }
3051 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3052 name_str = "<no-name - thread is attaching>";
3053 } else {
3054 name_str = Thread::name();
3055 }
3056 } else {
3057 name_str = Thread::name();
3058 }
3059 assert(name_str != NULL, "unexpected NULL thread name");
3060 return name_str;
3061 }
3062
3063
3064 const char* JavaThread::get_threadgroup_name() const {
3065 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3066 oop thread_obj = threadObj();
3067 if (thread_obj != NULL) {
3068 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3069 if (thread_group != NULL) {
3070 // ThreadGroup.name can be null
3071 return java_lang_ThreadGroup::name(thread_group);
3072 }
3073 }
3074 return NULL;
3075 }
3076
3077 const char* JavaThread::get_parent_name() const {
3078 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3079 oop thread_obj = threadObj();
3080 if (thread_obj != NULL) {
3081 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3082 if (thread_group != NULL) {
3083 oop parent = java_lang_ThreadGroup::parent(thread_group);
3084 if (parent != NULL) {
3085 // ThreadGroup.name can be null
3086 return java_lang_ThreadGroup::name(parent);
3087 }
3088 }
3089 }
3090 return NULL;
3091 }
3092
3093 ThreadPriority JavaThread::java_priority() const {
3094 oop thr_oop = threadObj();
3095 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3096 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3097 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3098 return priority;
3099 }
3100
3101 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3102
3103 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3104 // Link Java Thread object <-> C++ Thread
3105
3106 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3107 // and put it into a new Handle. The Handle "thread_oop" can then
3108 // be used to pass the C++ thread object to other methods.
3109
3110 // Set the Java level thread object (jthread) field of the
3111 // new thread (a JavaThread *) to C++ thread object using the
3112 // "thread_oop" handle.
3113
3114 // Set the thread field (a JavaThread *) of the
3115 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3116
3117 Handle thread_oop(Thread::current(),
3118 JNIHandles::resolve_non_null(jni_thread));
3119 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3120 "must be initialized");
3121 set_threadObj(thread_oop());
3122 java_lang_Thread::set_thread(thread_oop(), this);
3123
3124 if (prio == NoPriority) {
3125 prio = java_lang_Thread::priority(thread_oop());
3126 assert(prio != NoPriority, "A valid priority should be present");
3127 }
3128
3129 // Push the Java priority down to the native thread; needs Threads_lock
3130 Thread::set_priority(this, prio);
3131
3132 // Add the new thread to the Threads list and set it in motion.
3133 // We must have threads lock in order to call Threads::add.
3134 // It is crucial that we do not block before the thread is
3135 // added to the Threads list for if a GC happens, then the java_thread oop
3136 // will not be visited by GC.
3137 Threads::add(this);
3138 }
3139
3140 oop JavaThread::current_park_blocker() {
3141 // Support for JSR-166 locks
3142 oop thread_oop = threadObj();
3143 if (thread_oop != NULL &&
3144 JDK_Version::current().supports_thread_park_blocker()) {
3145 return java_lang_Thread::park_blocker(thread_oop);
3146 }
3147 return NULL;
3148 }
3149
3150
3151 void JavaThread::print_stack_on(outputStream* st) {
3152 if (!has_last_Java_frame()) return;
3153 ResourceMark rm;
3154 HandleMark hm;
3155
3156 RegisterMap reg_map(this);
3157 vframe* start_vf = last_java_vframe(®_map);
3158 int count = 0;
3159 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3160 if (f->is_java_frame()) {
3161 javaVFrame* jvf = javaVFrame::cast(f);
3162 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3163
3164 // Print out lock information
3165 if (JavaMonitorsInStackTrace) {
3166 jvf->print_lock_info_on(st, count);
3167 }
3168 } else {
3169 // Ignore non-Java frames
3170 }
3171
3172 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3173 count++;
3174 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3175 }
3176 }
3177
3178
3179 // JVMTI PopFrame support
3180 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3181 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3182 if (in_bytes(size_in_bytes) != 0) {
3183 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3184 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3185 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3186 }
3187 }
3188
3189 void* JavaThread::popframe_preserved_args() {
3190 return _popframe_preserved_args;
3191 }
3192
3193 ByteSize JavaThread::popframe_preserved_args_size() {
3194 return in_ByteSize(_popframe_preserved_args_size);
3195 }
3196
3197 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3198 int sz = in_bytes(popframe_preserved_args_size());
3199 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3200 return in_WordSize(sz / wordSize);
3201 }
3202
3203 void JavaThread::popframe_free_preserved_args() {
3204 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3205 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3206 _popframe_preserved_args = NULL;
3207 _popframe_preserved_args_size = 0;
3208 }
3209
3210 #ifndef PRODUCT
3211
3212 void JavaThread::trace_frames() {
3213 tty->print_cr("[Describe stack]");
3214 int frame_no = 1;
3215 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3216 tty->print(" %d. ", frame_no++);
3217 fst.current()->print_value_on(tty, this);
3218 tty->cr();
3219 }
3220 }
3221
3222 class PrintAndVerifyOopClosure: public OopClosure {
3223 protected:
3224 template <class T> inline void do_oop_work(T* p) {
3225 oop obj = RawAccess<>::oop_load(p);
3226 if (obj == NULL) return;
3227 tty->print(INTPTR_FORMAT ": ", p2i(p));
3228 if (oopDesc::is_oop_or_null(obj)) {
3229 if (obj->is_objArray()) {
3230 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3231 } else {
3232 obj->print();
3233 }
3234 } else {
3235 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3236 }
3237 tty->cr();
3238 }
3239 public:
3240 virtual void do_oop(oop* p) { do_oop_work(p); }
3241 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3242 };
3243
3244
3245 static void oops_print(frame* f, const RegisterMap *map) {
3246 PrintAndVerifyOopClosure print;
3247 f->print_value();
3248 f->oops_do(&print, NULL, (RegisterMap*)map);
3249 }
3250
3251 // Print our all the locations that contain oops and whether they are
3252 // valid or not. This useful when trying to find the oldest frame
3253 // where an oop has gone bad since the frame walk is from youngest to
3254 // oldest.
3255 void JavaThread::trace_oops() {
3256 tty->print_cr("[Trace oops]");
3257 frames_do(oops_print);
3258 }
3259
3260
3261 #ifdef ASSERT
3262 // Print or validate the layout of stack frames
3263 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3264 ResourceMark rm;
3265 PRESERVE_EXCEPTION_MARK;
3266 FrameValues values;
3267 int frame_no = 0;
3268 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3269 fst.current()->describe(values, ++frame_no);
3270 if (depth == frame_no) break;
3271 }
3272 if (validate_only) {
3273 values.validate();
3274 } else {
3275 tty->print_cr("[Describe stack layout]");
3276 values.print(this);
3277 }
3278 }
3279 #endif
3280
3281 void JavaThread::trace_stack_from(vframe* start_vf) {
3282 ResourceMark rm;
3283 int vframe_no = 1;
3284 for (vframe* f = start_vf; f; f = f->sender()) {
3285 if (f->is_java_frame()) {
3286 javaVFrame::cast(f)->print_activation(vframe_no++);
3287 } else {
3288 f->print();
3289 }
3290 if (vframe_no > StackPrintLimit) {
3291 tty->print_cr("...<more frames>...");
3292 return;
3293 }
3294 }
3295 }
3296
3297
3298 void JavaThread::trace_stack() {
3299 if (!has_last_Java_frame()) return;
3300 ResourceMark rm;
3301 HandleMark hm;
3302 RegisterMap reg_map(this);
3303 trace_stack_from(last_java_vframe(®_map));
3304 }
3305
3306
3307 #endif // PRODUCT
3308
3309
3310 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3311 assert(reg_map != NULL, "a map must be given");
3312 frame f = last_frame();
3313 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3314 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3315 }
3316 return NULL;
3317 }
3318
3319
3320 Klass* JavaThread::security_get_caller_class(int depth) {
3321 vframeStream vfst(this);
3322 vfst.security_get_caller_frame(depth);
3323 if (!vfst.at_end()) {
3324 return vfst.method()->method_holder();
3325 }
3326 return NULL;
3327 }
3328
3329 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3330 assert(thread->is_Compiler_thread(), "must be compiler thread");
3331 CompileBroker::compiler_thread_loop();
3332 }
3333
3334 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3335 NMethodSweeper::sweeper_loop();
3336 }
3337
3338 // Create a CompilerThread
3339 CompilerThread::CompilerThread(CompileQueue* queue,
3340 CompilerCounters* counters)
3341 : JavaThread(&compiler_thread_entry) {
3342 _env = NULL;
3343 _log = NULL;
3344 _task = NULL;
3345 _queue = queue;
3346 _counters = counters;
3347 _buffer_blob = NULL;
3348 _compiler = NULL;
3349
3350 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3351 resource_area()->bias_to(mtCompiler);
3352
3353 #ifndef PRODUCT
3354 _ideal_graph_printer = NULL;
3355 #endif
3356 }
3357
3358 bool CompilerThread::can_call_java() const {
3359 return _compiler != NULL && _compiler->is_jvmci();
3360 }
3361
3362 // Create sweeper thread
3363 CodeCacheSweeperThread::CodeCacheSweeperThread()
3364 : JavaThread(&sweeper_thread_entry) {
3365 _scanned_compiled_method = NULL;
3366 }
3367
3368 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3369 JavaThread::oops_do(f, cf);
3370 if (_scanned_compiled_method != NULL && cf != NULL) {
3371 // Safepoints can occur when the sweeper is scanning an nmethod so
3372 // process it here to make sure it isn't unloaded in the middle of
3373 // a scan.
3374 cf->do_code_blob(_scanned_compiled_method);
3375 }
3376 }
3377
3378 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3379 JavaThread::nmethods_do(cf);
3380 if (_scanned_compiled_method != NULL && cf != NULL) {
3381 // Safepoints can occur when the sweeper is scanning an nmethod so
3382 // process it here to make sure it isn't unloaded in the middle of
3383 // a scan.
3384 cf->do_code_blob(_scanned_compiled_method);
3385 }
3386 }
3387
3388
3389 // ======= Threads ========
3390
3391 // The Threads class links together all active threads, and provides
3392 // operations over all threads. It is protected by the Threads_lock,
3393 // which is also used in other global contexts like safepointing.
3394 // ThreadsListHandles are used to safely perform operations on one
3395 // or more threads without the risk of the thread exiting during the
3396 // operation.
3397 //
3398 // Note: The Threads_lock is currently more widely used than we
3399 // would like. We are actively migrating Threads_lock uses to other
3400 // mechanisms in order to reduce Threads_lock contention.
3401
3402 JavaThread* Threads::_thread_list = NULL;
3403 int Threads::_number_of_threads = 0;
3404 int Threads::_number_of_non_daemon_threads = 0;
3405 int Threads::_return_code = 0;
3406 int Threads::_thread_claim_parity = 0;
3407 size_t JavaThread::_stack_size_at_create = 0;
3408
3409 #ifdef ASSERT
3410 bool Threads::_vm_complete = false;
3411 #endif
3412
3413 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3414 Prefetch::read((void*)addr, prefetch_interval);
3415 return *addr;
3416 }
3417
3418 // Possibly the ugliest for loop the world has seen. C++ does not allow
3419 // multiple types in the declaration section of the for loop. In this case
3420 // we are only dealing with pointers and hence can cast them. It looks ugly
3421 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3422 #define DO_JAVA_THREADS(LIST, X) \
3423 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3424 *MACRO_list = (JavaThread*)(LIST), \
3425 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3426 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3427 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3428 MACRO_current_p != MACRO_end; \
3429 MACRO_current_p++, \
3430 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3431
3432 // All JavaThreads
3433 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3434
3435 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3436 void Threads::threads_do(ThreadClosure* tc) {
3437 assert_locked_or_safepoint(Threads_lock);
3438 // ALL_JAVA_THREADS iterates through all JavaThreads
3439 ALL_JAVA_THREADS(p) {
3440 tc->do_thread(p);
3441 }
3442 // Someday we could have a table or list of all non-JavaThreads.
3443 // For now, just manually iterate through them.
3444 tc->do_thread(VMThread::vm_thread());
3445 Universe::heap()->gc_threads_do(tc);
3446 WatcherThread *wt = WatcherThread::watcher_thread();
3447 // Strictly speaking, the following NULL check isn't sufficient to make sure
3448 // the data for WatcherThread is still valid upon being examined. However,
3449 // considering that WatchThread terminates when the VM is on the way to
3450 // exit at safepoint, the chance of the above is extremely small. The right
3451 // way to prevent termination of WatcherThread would be to acquire
3452 // Terminator_lock, but we can't do that without violating the lock rank
3453 // checking in some cases.
3454 if (wt != NULL) {
3455 tc->do_thread(wt);
3456 }
3457
3458 // If CompilerThreads ever become non-JavaThreads, add them here
3459 }
3460
3461 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3462 int cp = Threads::thread_claim_parity();
3463 ALL_JAVA_THREADS(p) {
3464 if (p->claim_oops_do(is_par, cp)) {
3465 tc->do_thread(p);
3466 }
3467 }
3468 VMThread* vmt = VMThread::vm_thread();
3469 if (vmt->claim_oops_do(is_par, cp)) {
3470 tc->do_thread(vmt);
3471 }
3472 }
3473
3474 // The system initialization in the library has three phases.
3475 //
3476 // Phase 1: java.lang.System class initialization
3477 // java.lang.System is a primordial class loaded and initialized
3478 // by the VM early during startup. java.lang.System.<clinit>
3479 // only does registerNatives and keeps the rest of the class
3480 // initialization work later until thread initialization completes.
3481 //
3482 // System.initPhase1 initializes the system properties, the static
3483 // fields in, out, and err. Set up java signal handlers, OS-specific
3484 // system settings, and thread group of the main thread.
3485 static void call_initPhase1(TRAPS) {
3486 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3487 JavaValue result(T_VOID);
3488 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3489 vmSymbols::void_method_signature(), CHECK);
3490 }
3491
3492 // Phase 2. Module system initialization
3493 // This will initialize the module system. Only java.base classes
3494 // can be loaded until phase 2 completes.
3495 //
3496 // Call System.initPhase2 after the compiler initialization and jsr292
3497 // classes get initialized because module initialization runs a lot of java
3498 // code, that for performance reasons, should be compiled. Also, this will
3499 // enable the startup code to use lambda and other language features in this
3500 // phase and onward.
3501 //
3502 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3503 static void call_initPhase2(TRAPS) {
3504 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3505
3506 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3507
3508 JavaValue result(T_INT);
3509 JavaCallArguments args;
3510 args.push_int(DisplayVMOutputToStderr);
3511 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3512 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3513 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3514 if (result.get_jint() != JNI_OK) {
3515 vm_exit_during_initialization(); // no message or exception
3516 }
3517
3518 universe_post_module_init();
3519 }
3520
3521 // Phase 3. final setup - set security manager, system class loader and TCCL
3522 //
3523 // This will instantiate and set the security manager, set the system class
3524 // loader as well as the thread context class loader. The security manager
3525 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3526 // other modules or the application's classpath.
3527 static void call_initPhase3(TRAPS) {
3528 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3529 JavaValue result(T_VOID);
3530 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3531 vmSymbols::void_method_signature(), CHECK);
3532 }
3533
3534 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3535 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3536
3537 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3538 create_vm_init_libraries();
3539 }
3540
3541 initialize_class(vmSymbols::java_lang_String(), CHECK);
3542
3543 // Inject CompactStrings value after the static initializers for String ran.
3544 java_lang_String::set_compact_strings(CompactStrings);
3545
3546 // Initialize java_lang.System (needed before creating the thread)
3547 initialize_class(vmSymbols::java_lang_System(), CHECK);
3548 // The VM creates & returns objects of this class. Make sure it's initialized.
3549 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3550 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3551 Handle thread_group = create_initial_thread_group(CHECK);
3552 Universe::set_main_thread_group(thread_group());
3553 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3554 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3555 main_thread->set_threadObj(thread_object);
3556 // Set thread status to running since main thread has
3557 // been started and running.
3558 java_lang_Thread::set_thread_status(thread_object,
3559 java_lang_Thread::RUNNABLE);
3560
3561 // The VM creates objects of this class.
3562 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3563
3564 // The VM preresolves methods to these classes. Make sure that they get initialized
3565 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3566 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3567
3568 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3569 call_initPhase1(CHECK);
3570
3571 // get the Java runtime name after java.lang.System is initialized
3572 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3573 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3574
3575 // an instance of OutOfMemory exception has been allocated earlier
3576 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3577 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3578 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3579 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3580 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3581 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3582 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3583 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3584 }
3585
3586 void Threads::initialize_jsr292_core_classes(TRAPS) {
3587 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3588
3589 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3590 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3591 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3592 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3593 }
3594
3595 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3596 extern void JDK_Version_init();
3597
3598 // Preinitialize version info.
3599 VM_Version::early_initialize();
3600
3601 // Check version
3602 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3603
3604 // Initialize library-based TLS
3605 ThreadLocalStorage::init();
3606
3607 // Initialize the output stream module
3608 ostream_init();
3609
3610 // Process java launcher properties.
3611 Arguments::process_sun_java_launcher_properties(args);
3612
3613 // Initialize the os module
3614 os::init();
3615
3616 // Record VM creation timing statistics
3617 TraceVmCreationTime create_vm_timer;
3618 create_vm_timer.start();
3619
3620 // Initialize system properties.
3621 Arguments::init_system_properties();
3622
3623 // So that JDK version can be used as a discriminator when parsing arguments
3624 JDK_Version_init();
3625
3626 // Update/Initialize System properties after JDK version number is known
3627 Arguments::init_version_specific_system_properties();
3628
3629 // Make sure to initialize log configuration *before* parsing arguments
3630 LogConfiguration::initialize(create_vm_timer.begin_time());
3631
3632 // Parse arguments
3633 // Note: this internally calls os::init_container_support()
3634 jint parse_result = Arguments::parse(args);
3635 if (parse_result != JNI_OK) return parse_result;
3636
3637 os::init_before_ergo();
3638
3639 jint ergo_result = Arguments::apply_ergo();
3640 if (ergo_result != JNI_OK) return ergo_result;
3641
3642 // Final check of all ranges after ergonomics which may change values.
3643 if (!CommandLineFlagRangeList::check_ranges()) {
3644 return JNI_EINVAL;
3645 }
3646
3647 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3648 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3649 if (!constraint_result) {
3650 return JNI_EINVAL;
3651 }
3652
3653 CommandLineFlagWriteableList::mark_startup();
3654
3655 if (PauseAtStartup) {
3656 os::pause();
3657 }
3658
3659 HOTSPOT_VM_INIT_BEGIN();
3660
3661 // Timing (must come after argument parsing)
3662 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3663
3664 // Initialize the os module after parsing the args
3665 jint os_init_2_result = os::init_2();
3666 if (os_init_2_result != JNI_OK) return os_init_2_result;
3667
3668 SafepointMechanism::initialize();
3669
3670 jint adjust_after_os_result = Arguments::adjust_after_os();
3671 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3672
3673 // Initialize output stream logging
3674 ostream_init_log();
3675
3676 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3677 // Must be before create_vm_init_agents()
3678 if (Arguments::init_libraries_at_startup()) {
3679 convert_vm_init_libraries_to_agents();
3680 }
3681
3682 // Launch -agentlib/-agentpath and converted -Xrun agents
3683 if (Arguments::init_agents_at_startup()) {
3684 create_vm_init_agents();
3685 }
3686
3687 // Initialize Threads state
3688 _thread_list = NULL;
3689 _number_of_threads = 0;
3690 _number_of_non_daemon_threads = 0;
3691
3692 // Initialize global data structures and create system classes in heap
3693 vm_init_globals();
3694
3695 #if INCLUDE_JVMCI
3696 if (JVMCICounterSize > 0) {
3697 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3698 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3699 } else {
3700 JavaThread::_jvmci_old_thread_counters = NULL;
3701 }
3702 #endif // INCLUDE_JVMCI
3703
3704 // Attach the main thread to this os thread
3705 JavaThread* main_thread = new JavaThread();
3706 main_thread->set_thread_state(_thread_in_vm);
3707 main_thread->initialize_thread_current();
3708 // must do this before set_active_handles
3709 main_thread->record_stack_base_and_size();
3710 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3711
3712 if (!main_thread->set_as_starting_thread()) {
3713 vm_shutdown_during_initialization(
3714 "Failed necessary internal allocation. Out of swap space");
3715 main_thread->smr_delete();
3716 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3717 return JNI_ENOMEM;
3718 }
3719
3720 // Enable guard page *after* os::create_main_thread(), otherwise it would
3721 // crash Linux VM, see notes in os_linux.cpp.
3722 main_thread->create_stack_guard_pages();
3723
3724 // Initialize Java-Level synchronization subsystem
3725 ObjectMonitor::Initialize();
3726
3727 // Initialize global modules
3728 jint status = init_globals();
3729 if (status != JNI_OK) {
3730 main_thread->smr_delete();
3731 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3732 return status;
3733 }
3734
3735 if (TRACE_INITIALIZE() != JNI_OK) {
3736 vm_exit_during_initialization("Failed to initialize tracing backend");
3737 }
3738
3739 // Should be done after the heap is fully created
3740 main_thread->cache_global_variables();
3741
3742 HandleMark hm;
3743
3744 { MutexLocker mu(Threads_lock);
3745 Threads::add(main_thread);
3746 }
3747
3748 // Any JVMTI raw monitors entered in onload will transition into
3749 // real raw monitor. VM is setup enough here for raw monitor enter.
3750 JvmtiExport::transition_pending_onload_raw_monitors();
3751
3752 // Create the VMThread
3753 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3754
3755 VMThread::create();
3756 Thread* vmthread = VMThread::vm_thread();
3757
3758 if (!os::create_thread(vmthread, os::vm_thread)) {
3759 vm_exit_during_initialization("Cannot create VM thread. "
3760 "Out of system resources.");
3761 }
3762
3763 // Wait for the VM thread to become ready, and VMThread::run to initialize
3764 // Monitors can have spurious returns, must always check another state flag
3765 {
3766 MutexLocker ml(Notify_lock);
3767 os::start_thread(vmthread);
3768 while (vmthread->active_handles() == NULL) {
3769 Notify_lock->wait();
3770 }
3771 }
3772 }
3773
3774 assert(Universe::is_fully_initialized(), "not initialized");
3775 if (VerifyDuringStartup) {
3776 // Make sure we're starting with a clean slate.
3777 VM_Verify verify_op;
3778 VMThread::execute(&verify_op);
3779 }
3780
3781 Thread* THREAD = Thread::current();
3782
3783 // Always call even when there are not JVMTI environments yet, since environments
3784 // may be attached late and JVMTI must track phases of VM execution
3785 JvmtiExport::enter_early_start_phase();
3786
3787 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3788 JvmtiExport::post_early_vm_start();
3789
3790 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3791
3792 // We need this for ClassDataSharing - the initial vm.info property is set
3793 // with the default value of CDS "sharing" which may be reset through
3794 // command line options.
3795 reset_vm_info_property(CHECK_JNI_ERR);
3796
3797 quicken_jni_functions();
3798
3799 // No more stub generation allowed after that point.
3800 StubCodeDesc::freeze();
3801
3802 // Set flag that basic initialization has completed. Used by exceptions and various
3803 // debug stuff, that does not work until all basic classes have been initialized.
3804 set_init_completed();
3805
3806 LogConfiguration::post_initialize();
3807 Metaspace::post_initialize();
3808
3809 HOTSPOT_VM_INIT_END();
3810
3811 // record VM initialization completion time
3812 #if INCLUDE_MANAGEMENT
3813 Management::record_vm_init_completed();
3814 #endif // INCLUDE_MANAGEMENT
3815
3816 // Signal Dispatcher needs to be started before VMInit event is posted
3817 os::signal_init(CHECK_JNI_ERR);
3818
3819 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3820 if (!DisableAttachMechanism) {
3821 AttachListener::vm_start();
3822 if (StartAttachListener || AttachListener::init_at_startup()) {
3823 AttachListener::init();
3824 }
3825 }
3826
3827 // Launch -Xrun agents
3828 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3829 // back-end can launch with -Xdebug -Xrunjdwp.
3830 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3831 create_vm_init_libraries();
3832 }
3833
3834 if (CleanChunkPoolAsync) {
3835 Chunk::start_chunk_pool_cleaner_task();
3836 }
3837
3838 // initialize compiler(s)
3839 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3840 CompileBroker::compilation_init(CHECK_JNI_ERR);
3841 #endif
3842
3843 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3844 // It is done after compilers are initialized, because otherwise compilations of
3845 // signature polymorphic MH intrinsics can be missed
3846 // (see SystemDictionary::find_method_handle_intrinsic).
3847 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3848
3849 // This will initialize the module system. Only java.base classes can be
3850 // loaded until phase 2 completes
3851 call_initPhase2(CHECK_JNI_ERR);
3852
3853 // Always call even when there are not JVMTI environments yet, since environments
3854 // may be attached late and JVMTI must track phases of VM execution
3855 JvmtiExport::enter_start_phase();
3856
3857 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3858 JvmtiExport::post_vm_start();
3859
3860 // Final system initialization including security manager and system class loader
3861 call_initPhase3(CHECK_JNI_ERR);
3862
3863 // cache the system and platform class loaders
3864 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3865
3866 #if INCLUDE_JVMCI
3867 if (EnableJVMCI) {
3868 // Initialize JVMCI eagerly when it is explicitly requested.
3869 // Or when JVMCIPrintProperties is enabled.
3870 // The JVMCI Java initialization code will read this flag and
3871 // do the printing if it's set.
3872 bool init = EagerJVMCI || JVMCIPrintProperties;
3873
3874 if (!init) {
3875 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3876 // compilations via JVMCI will not actually block until JVMCI is initialized.
3877 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3878 }
3879
3880 if (init) {
3881 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3882 }
3883 }
3884 #endif
3885
3886 // Always call even when there are not JVMTI environments yet, since environments
3887 // may be attached late and JVMTI must track phases of VM execution
3888 JvmtiExport::enter_live_phase();
3889
3890 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3891 JvmtiExport::post_vm_initialized();
3892
3893 if (TRACE_START() != JNI_OK) {
3894 vm_exit_during_initialization("Failed to start tracing backend.");
3895 }
3896
3897 #if INCLUDE_MANAGEMENT
3898 Management::initialize(THREAD);
3899
3900 if (HAS_PENDING_EXCEPTION) {
3901 // management agent fails to start possibly due to
3902 // configuration problem and is responsible for printing
3903 // stack trace if appropriate. Simply exit VM.
3904 vm_exit(1);
3905 }
3906 #endif // INCLUDE_MANAGEMENT
3907
3908 if (MemProfiling) MemProfiler::engage();
3909 StatSampler::engage();
3910 if (CheckJNICalls) JniPeriodicChecker::engage();
3911
3912 BiasedLocking::init();
3913
3914 #if INCLUDE_RTM_OPT
3915 RTMLockingCounters::init();
3916 #endif
3917
3918 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3919 call_postVMInitHook(THREAD);
3920 // The Java side of PostVMInitHook.run must deal with all
3921 // exceptions and provide means of diagnosis.
3922 if (HAS_PENDING_EXCEPTION) {
3923 CLEAR_PENDING_EXCEPTION;
3924 }
3925 }
3926
3927 {
3928 MutexLocker ml(PeriodicTask_lock);
3929 // Make sure the WatcherThread can be started by WatcherThread::start()
3930 // or by dynamic enrollment.
3931 WatcherThread::make_startable();
3932 // Start up the WatcherThread if there are any periodic tasks
3933 // NOTE: All PeriodicTasks should be registered by now. If they
3934 // aren't, late joiners might appear to start slowly (we might
3935 // take a while to process their first tick).
3936 if (PeriodicTask::num_tasks() > 0) {
3937 WatcherThread::start();
3938 }
3939 }
3940
3941 create_vm_timer.end();
3942 #ifdef ASSERT
3943 _vm_complete = true;
3944 #endif
3945
3946 if (DumpSharedSpaces) {
3947 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3948 ShouldNotReachHere();
3949 }
3950
3951 return JNI_OK;
3952 }
3953
3954 // type for the Agent_OnLoad and JVM_OnLoad entry points
3955 extern "C" {
3956 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3957 }
3958 // Find a command line agent library and return its entry point for
3959 // -agentlib: -agentpath: -Xrun
3960 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3961 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3962 const char *on_load_symbols[],
3963 size_t num_symbol_entries) {
3964 OnLoadEntry_t on_load_entry = NULL;
3965 void *library = NULL;
3966
3967 if (!agent->valid()) {
3968 char buffer[JVM_MAXPATHLEN];
3969 char ebuf[1024] = "";
3970 const char *name = agent->name();
3971 const char *msg = "Could not find agent library ";
3972
3973 // First check to see if agent is statically linked into executable
3974 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3975 library = agent->os_lib();
3976 } else if (agent->is_absolute_path()) {
3977 library = os::dll_load(name, ebuf, sizeof ebuf);
3978 if (library == NULL) {
3979 const char *sub_msg = " in absolute path, with error: ";
3980 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3981 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3982 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3983 // If we can't find the agent, exit.
3984 vm_exit_during_initialization(buf, NULL);
3985 FREE_C_HEAP_ARRAY(char, buf);
3986 }
3987 } else {
3988 // Try to load the agent from the standard dll directory
3989 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3990 name)) {
3991 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3992 }
3993 if (library == NULL) { // Try the library path directory.
3994 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3995 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3996 }
3997 if (library == NULL) {
3998 const char *sub_msg = " on the library path, with error: ";
3999 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4000
4001 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4002 strlen(ebuf) + strlen(sub_msg2) + 1;
4003 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4004 if (!agent->is_instrument_lib()) {
4005 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4006 } else {
4007 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4008 }
4009 // If we can't find the agent, exit.
4010 vm_exit_during_initialization(buf, NULL);
4011 FREE_C_HEAP_ARRAY(char, buf);
4012 }
4013 }
4014 }
4015 agent->set_os_lib(library);
4016 agent->set_valid();
4017 }
4018
4019 // Find the OnLoad function.
4020 on_load_entry =
4021 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4022 false,
4023 on_load_symbols,
4024 num_symbol_entries));
4025 return on_load_entry;
4026 }
4027
4028 // Find the JVM_OnLoad entry point
4029 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4030 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4031 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4032 }
4033
4034 // Find the Agent_OnLoad entry point
4035 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4036 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4037 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4038 }
4039
4040 // For backwards compatibility with -Xrun
4041 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4042 // treated like -agentpath:
4043 // Must be called before agent libraries are created
4044 void Threads::convert_vm_init_libraries_to_agents() {
4045 AgentLibrary* agent;
4046 AgentLibrary* next;
4047
4048 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4049 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4050 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4051
4052 // If there is an JVM_OnLoad function it will get called later,
4053 // otherwise see if there is an Agent_OnLoad
4054 if (on_load_entry == NULL) {
4055 on_load_entry = lookup_agent_on_load(agent);
4056 if (on_load_entry != NULL) {
4057 // switch it to the agent list -- so that Agent_OnLoad will be called,
4058 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4059 Arguments::convert_library_to_agent(agent);
4060 } else {
4061 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4062 }
4063 }
4064 }
4065 }
4066
4067 // Create agents for -agentlib: -agentpath: and converted -Xrun
4068 // Invokes Agent_OnLoad
4069 // Called very early -- before JavaThreads exist
4070 void Threads::create_vm_init_agents() {
4071 extern struct JavaVM_ main_vm;
4072 AgentLibrary* agent;
4073
4074 JvmtiExport::enter_onload_phase();
4075
4076 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4077 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4078
4079 if (on_load_entry != NULL) {
4080 // Invoke the Agent_OnLoad function
4081 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4082 if (err != JNI_OK) {
4083 vm_exit_during_initialization("agent library failed to init", agent->name());
4084 }
4085 } else {
4086 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4087 }
4088 }
4089 JvmtiExport::enter_primordial_phase();
4090 }
4091
4092 extern "C" {
4093 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4094 }
4095
4096 void Threads::shutdown_vm_agents() {
4097 // Send any Agent_OnUnload notifications
4098 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4099 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4100 extern struct JavaVM_ main_vm;
4101 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4102
4103 // Find the Agent_OnUnload function.
4104 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4105 os::find_agent_function(agent,
4106 false,
4107 on_unload_symbols,
4108 num_symbol_entries));
4109
4110 // Invoke the Agent_OnUnload function
4111 if (unload_entry != NULL) {
4112 JavaThread* thread = JavaThread::current();
4113 ThreadToNativeFromVM ttn(thread);
4114 HandleMark hm(thread);
4115 (*unload_entry)(&main_vm);
4116 }
4117 }
4118 }
4119
4120 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4121 // Invokes JVM_OnLoad
4122 void Threads::create_vm_init_libraries() {
4123 extern struct JavaVM_ main_vm;
4124 AgentLibrary* agent;
4125
4126 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4127 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4128
4129 if (on_load_entry != NULL) {
4130 // Invoke the JVM_OnLoad function
4131 JavaThread* thread = JavaThread::current();
4132 ThreadToNativeFromVM ttn(thread);
4133 HandleMark hm(thread);
4134 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4135 if (err != JNI_OK) {
4136 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4137 }
4138 } else {
4139 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4140 }
4141 }
4142 }
4143
4144
4145 // Last thread running calls java.lang.Shutdown.shutdown()
4146 void JavaThread::invoke_shutdown_hooks() {
4147 HandleMark hm(this);
4148
4149 // We could get here with a pending exception, if so clear it now.
4150 if (this->has_pending_exception()) {
4151 this->clear_pending_exception();
4152 }
4153
4154 EXCEPTION_MARK;
4155 Klass* shutdown_klass =
4156 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4157 THREAD);
4158 if (shutdown_klass != NULL) {
4159 // SystemDictionary::resolve_or_null will return null if there was
4160 // an exception. If we cannot load the Shutdown class, just don't
4161 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4162 // won't be run. Note that if a shutdown hook was registered,
4163 // the Shutdown class would have already been loaded
4164 // (Runtime.addShutdownHook will load it).
4165 JavaValue result(T_VOID);
4166 JavaCalls::call_static(&result,
4167 shutdown_klass,
4168 vmSymbols::shutdown_method_name(),
4169 vmSymbols::void_method_signature(),
4170 THREAD);
4171 }
4172 CLEAR_PENDING_EXCEPTION;
4173 }
4174
4175 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4176 // the program falls off the end of main(). Another VM exit path is through
4177 // vm_exit() when the program calls System.exit() to return a value or when
4178 // there is a serious error in VM. The two shutdown paths are not exactly
4179 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4180 // and VM_Exit op at VM level.
4181 //
4182 // Shutdown sequence:
4183 // + Shutdown native memory tracking if it is on
4184 // + Wait until we are the last non-daemon thread to execute
4185 // <-- every thing is still working at this moment -->
4186 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4187 // shutdown hooks
4188 // + Call before_exit(), prepare for VM exit
4189 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4190 // currently the only user of this mechanism is File.deleteOnExit())
4191 // > stop StatSampler, watcher thread, CMS threads,
4192 // post thread end and vm death events to JVMTI,
4193 // stop signal thread
4194 // + Call JavaThread::exit(), it will:
4195 // > release JNI handle blocks, remove stack guard pages
4196 // > remove this thread from Threads list
4197 // <-- no more Java code from this thread after this point -->
4198 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4199 // the compiler threads at safepoint
4200 // <-- do not use anything that could get blocked by Safepoint -->
4201 // + Disable tracing at JNI/JVM barriers
4202 // + Set _vm_exited flag for threads that are still running native code
4203 // + Delete this thread
4204 // + Call exit_globals()
4205 // > deletes tty
4206 // > deletes PerfMemory resources
4207 // + Return to caller
4208
4209 bool Threads::destroy_vm() {
4210 JavaThread* thread = JavaThread::current();
4211
4212 #ifdef ASSERT
4213 _vm_complete = false;
4214 #endif
4215 // Wait until we are the last non-daemon thread to execute
4216 { MutexLocker nu(Threads_lock);
4217 while (Threads::number_of_non_daemon_threads() > 1)
4218 // This wait should make safepoint checks, wait without a timeout,
4219 // and wait as a suspend-equivalent condition.
4220 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4221 Mutex::_as_suspend_equivalent_flag);
4222 }
4223
4224 EventShutdown e;
4225 if (e.should_commit()) {
4226 e.set_reason("No remaining non-daemon Java threads");
4227 e.commit();
4228 }
4229
4230 // Hang forever on exit if we are reporting an error.
4231 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4232 os::infinite_sleep();
4233 }
4234 os::wait_for_keypress_at_exit();
4235
4236 // run Java level shutdown hooks
4237 thread->invoke_shutdown_hooks();
4238
4239 before_exit(thread);
4240
4241 thread->exit(true);
4242
4243 // Stop VM thread.
4244 {
4245 // 4945125 The vm thread comes to a safepoint during exit.
4246 // GC vm_operations can get caught at the safepoint, and the
4247 // heap is unparseable if they are caught. Grab the Heap_lock
4248 // to prevent this. The GC vm_operations will not be able to
4249 // queue until after the vm thread is dead. After this point,
4250 // we'll never emerge out of the safepoint before the VM exits.
4251
4252 MutexLocker ml(Heap_lock);
4253
4254 VMThread::wait_for_vm_thread_exit();
4255 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4256 VMThread::destroy();
4257 }
4258
4259 // Now, all Java threads are gone except daemon threads. Daemon threads
4260 // running Java code or in VM are stopped by the Safepoint. However,
4261 // daemon threads executing native code are still running. But they
4262 // will be stopped at native=>Java/VM barriers. Note that we can't
4263 // simply kill or suspend them, as it is inherently deadlock-prone.
4264
4265 VM_Exit::set_vm_exited();
4266
4267 // Clean up ideal graph printers after the VMThread has started
4268 // the final safepoint which will block all the Compiler threads.
4269 // Note that this Thread has already logically exited so the
4270 // clean_up() function's use of a JavaThreadIteratorWithHandle
4271 // would be a problem except set_vm_exited() has remembered the
4272 // shutdown thread which is granted a policy exception.
4273 #if defined(COMPILER2) && !defined(PRODUCT)
4274 IdealGraphPrinter::clean_up();
4275 #endif
4276
4277 notify_vm_shutdown();
4278
4279 // We are after VM_Exit::set_vm_exited() so we can't call
4280 // thread->smr_delete() or we will block on the Threads_lock.
4281 // Deleting the shutdown thread here is safe because another
4282 // JavaThread cannot have an active ThreadsListHandle for
4283 // this JavaThread.
4284 delete thread;
4285
4286 #if INCLUDE_JVMCI
4287 if (JVMCICounterSize > 0) {
4288 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4289 }
4290 #endif
4291
4292 // exit_globals() will delete tty
4293 exit_globals();
4294
4295 LogConfiguration::finalize();
4296
4297 return true;
4298 }
4299
4300
4301 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4302 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4303 return is_supported_jni_version(version);
4304 }
4305
4306
4307 jboolean Threads::is_supported_jni_version(jint version) {
4308 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4309 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4310 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4311 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4312 if (version == JNI_VERSION_9) return JNI_TRUE;
4313 if (version == JNI_VERSION_10) return JNI_TRUE;
4314 return JNI_FALSE;
4315 }
4316
4317
4318 void Threads::add(JavaThread* p, bool force_daemon) {
4319 // The threads lock must be owned at this point
4320 assert_locked_or_safepoint(Threads_lock);
4321
4322 BarrierSet::barrier_set()->on_thread_attach(p);
4323
4324 p->set_next(_thread_list);
4325 _thread_list = p;
4326
4327 // Once a JavaThread is added to the Threads list, smr_delete() has
4328 // to be used to delete it. Otherwise we can just delete it directly.
4329 p->set_on_thread_list();
4330
4331 _number_of_threads++;
4332 oop threadObj = p->threadObj();
4333 bool daemon = true;
4334 // Bootstrapping problem: threadObj can be null for initial
4335 // JavaThread (or for threads attached via JNI)
4336 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4337 _number_of_non_daemon_threads++;
4338 daemon = false;
4339 }
4340
4341 ThreadService::add_thread(p, daemon);
4342
4343 // Maintain fast thread list
4344 ThreadsSMRSupport::add_thread(p);
4345
4346 // Possible GC point.
4347 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4348 }
4349
4350 void Threads::remove(JavaThread* p) {
4351
4352 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4353 ObjectSynchronizer::omFlush(p);
4354
4355 // Extra scope needed for Thread_lock, so we can check
4356 // that we do not remove thread without safepoint code notice
4357 { MutexLocker ml(Threads_lock);
4358
4359 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4360
4361 // Maintain fast thread list
4362 ThreadsSMRSupport::remove_thread(p);
4363
4364 JavaThread* current = _thread_list;
4365 JavaThread* prev = NULL;
4366
4367 while (current != p) {
4368 prev = current;
4369 current = current->next();
4370 }
4371
4372 if (prev) {
4373 prev->set_next(current->next());
4374 } else {
4375 _thread_list = p->next();
4376 }
4377
4378 _number_of_threads--;
4379 oop threadObj = p->threadObj();
4380 bool daemon = true;
4381 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4382 _number_of_non_daemon_threads--;
4383 daemon = false;
4384
4385 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4386 // on destroy_vm will wake up.
4387 if (number_of_non_daemon_threads() == 1) {
4388 Threads_lock->notify_all();
4389 }
4390 }
4391 ThreadService::remove_thread(p, daemon);
4392
4393 // Make sure that safepoint code disregard this thread. This is needed since
4394 // the thread might mess around with locks after this point. This can cause it
4395 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4396 // of this thread since it is removed from the queue.
4397 p->set_terminated_value();
4398 } // unlock Threads_lock
4399
4400 // Since Events::log uses a lock, we grab it outside the Threads_lock
4401 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4402 }
4403
4404 // Operations on the Threads list for GC. These are not explicitly locked,
4405 // but the garbage collector must provide a safe context for them to run.
4406 // In particular, these things should never be called when the Threads_lock
4407 // is held by some other thread. (Note: the Safepoint abstraction also
4408 // uses the Threads_lock to guarantee this property. It also makes sure that
4409 // all threads gets blocked when exiting or starting).
4410
4411 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4412 ALL_JAVA_THREADS(p) {
4413 p->oops_do(f, cf);
4414 }
4415 VMThread::vm_thread()->oops_do(f, cf);
4416 }
4417
4418 void Threads::change_thread_claim_parity() {
4419 // Set the new claim parity.
4420 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4421 "Not in range.");
4422 _thread_claim_parity++;
4423 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4424 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4425 "Not in range.");
4426 }
4427
4428 #ifdef ASSERT
4429 void Threads::assert_all_threads_claimed() {
4430 ALL_JAVA_THREADS(p) {
4431 const int thread_parity = p->oops_do_parity();
4432 assert((thread_parity == _thread_claim_parity),
4433 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4434 }
4435 VMThread* vmt = VMThread::vm_thread();
4436 const int thread_parity = vmt->oops_do_parity();
4437 assert((thread_parity == _thread_claim_parity),
4438 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4439 }
4440 #endif // ASSERT
4441
4442 class ParallelOopsDoThreadClosure : public ThreadClosure {
4443 private:
4444 OopClosure* _f;
4445 CodeBlobClosure* _cf;
4446 public:
4447 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4448 void do_thread(Thread* t) {
4449 t->oops_do(_f, _cf);
4450 }
4451 };
4452
4453 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4454 ParallelOopsDoThreadClosure tc(f, cf);
4455 possibly_parallel_threads_do(is_par, &tc);
4456 }
4457
4458 #if INCLUDE_ALL_GCS
4459 // Used by ParallelScavenge
4460 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4461 ALL_JAVA_THREADS(p) {
4462 q->enqueue(new ThreadRootsTask(p));
4463 }
4464 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4465 }
4466
4467 // Used by Parallel Old
4468 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4469 ALL_JAVA_THREADS(p) {
4470 q->enqueue(new ThreadRootsMarkingTask(p));
4471 }
4472 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4473 }
4474 #endif // INCLUDE_ALL_GCS
4475
4476 void Threads::nmethods_do(CodeBlobClosure* cf) {
4477 ALL_JAVA_THREADS(p) {
4478 // This is used by the code cache sweeper to mark nmethods that are active
4479 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4480 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4481 if(!p->is_Code_cache_sweeper_thread()) {
4482 p->nmethods_do(cf);
4483 }
4484 }
4485 }
4486
4487 void Threads::metadata_do(void f(Metadata*)) {
4488 ALL_JAVA_THREADS(p) {
4489 p->metadata_do(f);
4490 }
4491 }
4492
4493 class ThreadHandlesClosure : public ThreadClosure {
4494 void (*_f)(Metadata*);
4495 public:
4496 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4497 virtual void do_thread(Thread* thread) {
4498 thread->metadata_handles_do(_f);
4499 }
4500 };
4501
4502 void Threads::metadata_handles_do(void f(Metadata*)) {
4503 // Only walk the Handles in Thread.
4504 ThreadHandlesClosure handles_closure(f);
4505 threads_do(&handles_closure);
4506 }
4507
4508 void Threads::deoptimized_wrt_marked_nmethods() {
4509 ALL_JAVA_THREADS(p) {
4510 p->deoptimized_wrt_marked_nmethods();
4511 }
4512 }
4513
4514
4515 // Get count Java threads that are waiting to enter the specified monitor.
4516 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4517 int count,
4518 address monitor) {
4519 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4520
4521 int i = 0;
4522 DO_JAVA_THREADS(t_list, p) {
4523 if (!p->can_call_java()) continue;
4524
4525 address pending = (address)p->current_pending_monitor();
4526 if (pending == monitor) { // found a match
4527 if (i < count) result->append(p); // save the first count matches
4528 i++;
4529 }
4530 }
4531
4532 return result;
4533 }
4534
4535
4536 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4537 address owner) {
4538 // NULL owner means not locked so we can skip the search
4539 if (owner == NULL) return NULL;
4540
4541 DO_JAVA_THREADS(t_list, p) {
4542 // first, see if owner is the address of a Java thread
4543 if (owner == (address)p) return p;
4544 }
4545
4546 // Cannot assert on lack of success here since this function may be
4547 // used by code that is trying to report useful problem information
4548 // like deadlock detection.
4549 if (UseHeavyMonitors) return NULL;
4550
4551 // If we didn't find a matching Java thread and we didn't force use of
4552 // heavyweight monitors, then the owner is the stack address of the
4553 // Lock Word in the owning Java thread's stack.
4554 //
4555 JavaThread* the_owner = NULL;
4556 DO_JAVA_THREADS(t_list, q) {
4557 if (q->is_lock_owned(owner)) {
4558 the_owner = q;
4559 break;
4560 }
4561 }
4562
4563 // cannot assert on lack of success here; see above comment
4564 return the_owner;
4565 }
4566
4567 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4568 void Threads::print_on(outputStream* st, bool print_stacks,
4569 bool internal_format, bool print_concurrent_locks) {
4570 char buf[32];
4571 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4572
4573 st->print_cr("Full thread dump %s (%s %s):",
4574 Abstract_VM_Version::vm_name(),
4575 Abstract_VM_Version::vm_release(),
4576 Abstract_VM_Version::vm_info_string());
4577 st->cr();
4578
4579 #if INCLUDE_SERVICES
4580 // Dump concurrent locks
4581 ConcurrentLocksDump concurrent_locks;
4582 if (print_concurrent_locks) {
4583 concurrent_locks.dump_at_safepoint();
4584 }
4585 #endif // INCLUDE_SERVICES
4586
4587 ThreadsSMRSupport::print_info_on(st);
4588 st->cr();
4589
4590 ALL_JAVA_THREADS(p) {
4591 ResourceMark rm;
4592 p->print_on(st);
4593 if (print_stacks) {
4594 if (internal_format) {
4595 p->trace_stack();
4596 } else {
4597 p->print_stack_on(st);
4598 }
4599 }
4600 st->cr();
4601 #if INCLUDE_SERVICES
4602 if (print_concurrent_locks) {
4603 concurrent_locks.print_locks_on(p, st);
4604 }
4605 #endif // INCLUDE_SERVICES
4606 }
4607
4608 VMThread::vm_thread()->print_on(st);
4609 st->cr();
4610 Universe::heap()->print_gc_threads_on(st);
4611 WatcherThread* wt = WatcherThread::watcher_thread();
4612 if (wt != NULL) {
4613 wt->print_on(st);
4614 st->cr();
4615 }
4616
4617 st->flush();
4618 }
4619
4620 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4621 int buflen, bool* found_current) {
4622 if (this_thread != NULL) {
4623 bool is_current = (current == this_thread);
4624 *found_current = *found_current || is_current;
4625 st->print("%s", is_current ? "=>" : " ");
4626
4627 st->print(PTR_FORMAT, p2i(this_thread));
4628 st->print(" ");
4629 this_thread->print_on_error(st, buf, buflen);
4630 st->cr();
4631 }
4632 }
4633
4634 class PrintOnErrorClosure : public ThreadClosure {
4635 outputStream* _st;
4636 Thread* _current;
4637 char* _buf;
4638 int _buflen;
4639 bool* _found_current;
4640 public:
4641 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4642 int buflen, bool* found_current) :
4643 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4644
4645 virtual void do_thread(Thread* thread) {
4646 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4647 }
4648 };
4649
4650 // Threads::print_on_error() is called by fatal error handler. It's possible
4651 // that VM is not at safepoint and/or current thread is inside signal handler.
4652 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4653 // memory (even in resource area), it might deadlock the error handler.
4654 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4655 int buflen) {
4656 ThreadsSMRSupport::print_info_on(st);
4657 st->cr();
4658
4659 bool found_current = false;
4660 st->print_cr("Java Threads: ( => current thread )");
4661 ALL_JAVA_THREADS(thread) {
4662 print_on_error(thread, st, current, buf, buflen, &found_current);
4663 }
4664 st->cr();
4665
4666 st->print_cr("Other Threads:");
4667 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4668 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4669
4670 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4671 Universe::heap()->gc_threads_do(&print_closure);
4672
4673 if (!found_current) {
4674 st->cr();
4675 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4676 current->print_on_error(st, buf, buflen);
4677 st->cr();
4678 }
4679 st->cr();
4680
4681 st->print_cr("Threads with active compile tasks:");
4682 print_threads_compiling(st, buf, buflen);
4683 }
4684
4685 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4686 ALL_JAVA_THREADS(thread) {
4687 if (thread->is_Compiler_thread()) {
4688 CompilerThread* ct = (CompilerThread*) thread;
4689
4690 // Keep task in local variable for NULL check.
4691 // ct->_task might be set to NULL by concurring compiler thread
4692 // because it completed the compilation. The task is never freed,
4693 // though, just returned to a free list.
4694 CompileTask* task = ct->task();
4695 if (task != NULL) {
4696 thread->print_name_on_error(st, buf, buflen);
4697 task->print(st, NULL, true, true);
4698 }
4699 }
4700 }
4701 }
4702
4703
4704 // Internal SpinLock and Mutex
4705 // Based on ParkEvent
4706
4707 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4708 //
4709 // We employ SpinLocks _only for low-contention, fixed-length
4710 // short-duration critical sections where we're concerned
4711 // about native mutex_t or HotSpot Mutex:: latency.
4712 // The mux construct provides a spin-then-block mutual exclusion
4713 // mechanism.
4714 //
4715 // Testing has shown that contention on the ListLock guarding gFreeList
4716 // is common. If we implement ListLock as a simple SpinLock it's common
4717 // for the JVM to devolve to yielding with little progress. This is true
4718 // despite the fact that the critical sections protected by ListLock are
4719 // extremely short.
4720 //
4721 // TODO-FIXME: ListLock should be of type SpinLock.
4722 // We should make this a 1st-class type, integrated into the lock
4723 // hierarchy as leaf-locks. Critically, the SpinLock structure
4724 // should have sufficient padding to avoid false-sharing and excessive
4725 // cache-coherency traffic.
4726
4727
4728 typedef volatile int SpinLockT;
4729
4730 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4731 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4732 return; // normal fast-path return
4733 }
4734
4735 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4736 TEVENT(SpinAcquire - ctx);
4737 int ctr = 0;
4738 int Yields = 0;
4739 for (;;) {
4740 while (*adr != 0) {
4741 ++ctr;
4742 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4743 if (Yields > 5) {
4744 os::naked_short_sleep(1);
4745 } else {
4746 os::naked_yield();
4747 ++Yields;
4748 }
4749 } else {
4750 SpinPause();
4751 }
4752 }
4753 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4754 }
4755 }
4756
4757 void Thread::SpinRelease(volatile int * adr) {
4758 assert(*adr != 0, "invariant");
4759 OrderAccess::fence(); // guarantee at least release consistency.
4760 // Roach-motel semantics.
4761 // It's safe if subsequent LDs and STs float "up" into the critical section,
4762 // but prior LDs and STs within the critical section can't be allowed
4763 // to reorder or float past the ST that releases the lock.
4764 // Loads and stores in the critical section - which appear in program
4765 // order before the store that releases the lock - must also appear
4766 // before the store that releases the lock in memory visibility order.
4767 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4768 // the ST of 0 into the lock-word which releases the lock, so fence
4769 // more than covers this on all platforms.
4770 *adr = 0;
4771 }
4772
4773 // muxAcquire and muxRelease:
4774 //
4775 // * muxAcquire and muxRelease support a single-word lock-word construct.
4776 // The LSB of the word is set IFF the lock is held.
4777 // The remainder of the word points to the head of a singly-linked list
4778 // of threads blocked on the lock.
4779 //
4780 // * The current implementation of muxAcquire-muxRelease uses its own
4781 // dedicated Thread._MuxEvent instance. If we're interested in
4782 // minimizing the peak number of extant ParkEvent instances then
4783 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4784 // as certain invariants were satisfied. Specifically, care would need
4785 // to be taken with regards to consuming unpark() "permits".
4786 // A safe rule of thumb is that a thread would never call muxAcquire()
4787 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4788 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4789 // consume an unpark() permit intended for monitorenter, for instance.
4790 // One way around this would be to widen the restricted-range semaphore
4791 // implemented in park(). Another alternative would be to provide
4792 // multiple instances of the PlatformEvent() for each thread. One
4793 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4794 //
4795 // * Usage:
4796 // -- Only as leaf locks
4797 // -- for short-term locking only as muxAcquire does not perform
4798 // thread state transitions.
4799 //
4800 // Alternatives:
4801 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4802 // but with parking or spin-then-park instead of pure spinning.
4803 // * Use Taura-Oyama-Yonenzawa locks.
4804 // * It's possible to construct a 1-0 lock if we encode the lockword as
4805 // (List,LockByte). Acquire will CAS the full lockword while Release
4806 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4807 // acquiring threads use timers (ParkTimed) to detect and recover from
4808 // the stranding window. Thread/Node structures must be aligned on 256-byte
4809 // boundaries by using placement-new.
4810 // * Augment MCS with advisory back-link fields maintained with CAS().
4811 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4812 // The validity of the backlinks must be ratified before we trust the value.
4813 // If the backlinks are invalid the exiting thread must back-track through the
4814 // the forward links, which are always trustworthy.
4815 // * Add a successor indication. The LockWord is currently encoded as
4816 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4817 // to provide the usual futile-wakeup optimization.
4818 // See RTStt for details.
4819 // * Consider schedctl.sc_nopreempt to cover the critical section.
4820 //
4821
4822
4823 const intptr_t LOCKBIT = 1;
4824
4825 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4826 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4827 if (w == 0) return;
4828 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4829 return;
4830 }
4831
4832 TEVENT(muxAcquire - Contention);
4833 ParkEvent * const Self = Thread::current()->_MuxEvent;
4834 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4835 for (;;) {
4836 int its = (os::is_MP() ? 100 : 0) + 1;
4837
4838 // Optional spin phase: spin-then-park strategy
4839 while (--its >= 0) {
4840 w = *Lock;
4841 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4842 return;
4843 }
4844 }
4845
4846 Self->reset();
4847 Self->OnList = intptr_t(Lock);
4848 // The following fence() isn't _strictly necessary as the subsequent
4849 // CAS() both serializes execution and ratifies the fetched *Lock value.
4850 OrderAccess::fence();
4851 for (;;) {
4852 w = *Lock;
4853 if ((w & LOCKBIT) == 0) {
4854 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4855 Self->OnList = 0; // hygiene - allows stronger asserts
4856 return;
4857 }
4858 continue; // Interference -- *Lock changed -- Just retry
4859 }
4860 assert(w & LOCKBIT, "invariant");
4861 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4862 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4863 }
4864
4865 while (Self->OnList != 0) {
4866 Self->park();
4867 }
4868 }
4869 }
4870
4871 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4872 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4873 if (w == 0) return;
4874 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4875 return;
4876 }
4877
4878 TEVENT(muxAcquire - Contention);
4879 ParkEvent * ReleaseAfter = NULL;
4880 if (ev == NULL) {
4881 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4882 }
4883 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4884 for (;;) {
4885 guarantee(ev->OnList == 0, "invariant");
4886 int its = (os::is_MP() ? 100 : 0) + 1;
4887
4888 // Optional spin phase: spin-then-park strategy
4889 while (--its >= 0) {
4890 w = *Lock;
4891 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4892 if (ReleaseAfter != NULL) {
4893 ParkEvent::Release(ReleaseAfter);
4894 }
4895 return;
4896 }
4897 }
4898
4899 ev->reset();
4900 ev->OnList = intptr_t(Lock);
4901 // The following fence() isn't _strictly necessary as the subsequent
4902 // CAS() both serializes execution and ratifies the fetched *Lock value.
4903 OrderAccess::fence();
4904 for (;;) {
4905 w = *Lock;
4906 if ((w & LOCKBIT) == 0) {
4907 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4908 ev->OnList = 0;
4909 // We call ::Release while holding the outer lock, thus
4910 // artificially lengthening the critical section.
4911 // Consider deferring the ::Release() until the subsequent unlock(),
4912 // after we've dropped the outer lock.
4913 if (ReleaseAfter != NULL) {
4914 ParkEvent::Release(ReleaseAfter);
4915 }
4916 return;
4917 }
4918 continue; // Interference -- *Lock changed -- Just retry
4919 }
4920 assert(w & LOCKBIT, "invariant");
4921 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4922 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4923 }
4924
4925 while (ev->OnList != 0) {
4926 ev->park();
4927 }
4928 }
4929 }
4930
4931 // Release() must extract a successor from the list and then wake that thread.
4932 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4933 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4934 // Release() would :
4935 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4936 // (B) Extract a successor from the private list "in-hand"
4937 // (C) attempt to CAS() the residual back into *Lock over null.
4938 // If there were any newly arrived threads and the CAS() would fail.
4939 // In that case Release() would detach the RATs, re-merge the list in-hand
4940 // with the RATs and repeat as needed. Alternately, Release() might
4941 // detach and extract a successor, but then pass the residual list to the wakee.
4942 // The wakee would be responsible for reattaching and remerging before it
4943 // competed for the lock.
4944 //
4945 // Both "pop" and DMR are immune from ABA corruption -- there can be
4946 // multiple concurrent pushers, but only one popper or detacher.
4947 // This implementation pops from the head of the list. This is unfair,
4948 // but tends to provide excellent throughput as hot threads remain hot.
4949 // (We wake recently run threads first).
4950 //
4951 // All paths through muxRelease() will execute a CAS.
4952 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4953 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4954 // executed within the critical section are complete and globally visible before the
4955 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4956 void Thread::muxRelease(volatile intptr_t * Lock) {
4957 for (;;) {
4958 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4959 assert(w & LOCKBIT, "invariant");
4960 if (w == LOCKBIT) return;
4961 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4962 assert(List != NULL, "invariant");
4963 assert(List->OnList == intptr_t(Lock), "invariant");
4964 ParkEvent * const nxt = List->ListNext;
4965 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4966
4967 // The following CAS() releases the lock and pops the head element.
4968 // The CAS() also ratifies the previously fetched lock-word value.
4969 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4970 continue;
4971 }
4972 List->OnList = 0;
4973 OrderAccess::fence();
4974 List->unpark();
4975 return;
4976 }
4977 }
4978
4979
4980 void Threads::verify() {
4981 ALL_JAVA_THREADS(p) {
4982 p->verify();
4983 }
4984 VMThread* thread = VMThread::vm_thread();
4985 if (thread != NULL) thread->verify();
4986 }