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