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 "jvmtifiles/jvmtiEnv.hpp"
44 #include "logging/log.hpp"
45 #include "logging/logConfiguration.hpp"
46 #include "logging/logStream.hpp"
47 #include "memory/allocation.inline.hpp"
48 #include "memory/metaspaceShared.hpp"
49 #include "memory/oopFactory.hpp"
50 #include "memory/resourceArea.hpp"
51 #include "memory/universe.hpp"
52 #include "oops/access.inline.hpp"
53 #include "oops/instanceKlass.hpp"
54 #include "oops/objArrayOop.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "oops/symbol.hpp"
57 #include "oops/typeArrayOop.inline.hpp"
58 #include "oops/verifyOopClosure.hpp"
59 #include "prims/jvm_misc.hpp"
60 #include "prims/jvmtiExport.hpp"
61 #include "prims/jvmtiThreadState.hpp"
62 #include "prims/privilegedStack.hpp"
63 #include "runtime/arguments.hpp"
64 #include "runtime/atomic.hpp"
65 #include "runtime/biasedLocking.hpp"
66 #include "runtime/flags/jvmFlagConstraintList.hpp"
67 #include "runtime/flags/jvmFlagRangeList.hpp"
68 #include "runtime/flags/jvmFlagWriteableList.hpp"
69 #include "runtime/deoptimization.hpp"
70 #include "runtime/frame.inline.hpp"
71 #include "runtime/handshake.hpp"
72 #include "runtime/init.hpp"
73 #include "runtime/interfaceSupport.inline.hpp"
74 #include "runtime/java.hpp"
75 #include "runtime/javaCalls.hpp"
76 #include "runtime/jniHandles.inline.hpp"
77 #include "runtime/jniPeriodicChecker.hpp"
78 #include "runtime/memprofiler.hpp"
79 #include "runtime/mutexLocker.hpp"
80 #include "runtime/objectMonitor.hpp"
81 #include "runtime/orderAccess.inline.hpp"
82 #include "runtime/osThread.hpp"
83 #include "runtime/prefetch.inline.hpp"
84 #include "runtime/safepoint.hpp"
85 #include "runtime/safepointMechanism.inline.hpp"
86 #include "runtime/sharedRuntime.hpp"
87 #include "runtime/statSampler.hpp"
88 #include "runtime/stubRoutines.hpp"
89 #include "runtime/sweeper.hpp"
90 #include "runtime/task.hpp"
91 #include "runtime/thread.inline.hpp"
92 #include "runtime/threadCritical.hpp"
93 #include "runtime/threadSMR.inline.hpp"
94 #include "runtime/timer.hpp"
95 #include "runtime/timerTrace.hpp"
96 #include "runtime/vframe.inline.hpp"
97 #include "runtime/vframeArray.hpp"
98 #include "runtime/vframe_hp.hpp"
99 #include "runtime/vmThread.hpp"
100 #include "runtime/vm_operations.hpp"
101 #include "runtime/vm_version.hpp"
102 #include "services/attachListener.hpp"
103 #include "services/management.hpp"
104 #include "services/memTracker.hpp"
105 #include "services/threadService.hpp"
106 #include "trace/traceMacros.hpp"
107 #include "trace/tracing.hpp"
108 #include "trace/tracingExport.hpp"
109 #include "utilities/align.hpp"
110 #include "utilities/copy.hpp"
111 #include "utilities/defaultStream.hpp"
112 #include "utilities/dtrace.hpp"
113 #include "utilities/events.hpp"
114 #include "utilities/macros.hpp"
115 #include "utilities/preserveException.hpp"
116 #include "utilities/vmError.hpp"
117 #if INCLUDE_ALL_GCS
118 #include "gc/cms/concurrentMarkSweepThread.hpp"
119 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
120 #include "gc/parallel/pcTasks.hpp"
121 #endif // INCLUDE_ALL_GCS
122 #if INCLUDE_JVMCI
123 #include "jvmci/jvmciCompiler.hpp"
124 #include "jvmci/jvmciRuntime.hpp"
125 #include "logging/logHandle.hpp"
126 #endif
127 #ifdef COMPILER1
128 #include "c1/c1_Compiler.hpp"
129 #endif
130 #ifdef COMPILER2
131 #include "opto/c2compiler.hpp"
132 #include "opto/idealGraphPrinter.hpp"
133 #endif
134 #if INCLUDE_RTM_OPT
135 #include "runtime/rtmLocking.hpp"
136 #endif
137
138 // Initialization after module runtime initialization
139 void universe_post_module_init(); // must happen after call_initPhase2
140
141 #ifdef DTRACE_ENABLED
142
143 // Only bother with this argument setup if dtrace is available
144
145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
147
148 #define DTRACE_THREAD_PROBE(probe, javathread) \
149 { \
150 ResourceMark rm(this); \
151 int len = 0; \
152 const char* name = (javathread)->get_thread_name(); \
153 len = strlen(name); \
154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
155 (char *) name, len, \
156 java_lang_Thread::thread_id((javathread)->threadObj()), \
157 (uintptr_t) (javathread)->osthread()->thread_id(), \
158 java_lang_Thread::is_daemon((javathread)->threadObj())); \
159 }
160
161 #else // ndef DTRACE_ENABLED
162
163 #define DTRACE_THREAD_PROBE(probe, javathread)
164
165 #endif // ndef DTRACE_ENABLED
166
167 #ifndef USE_LIBRARY_BASED_TLS_ONLY
168 // Current thread is maintained as a thread-local variable
169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
170 #endif
171 // Class hierarchy
172 // - Thread
173 // - VMThread
174 // - WatcherThread
175 // - ConcurrentMarkSweepThread
176 // - JavaThread
177 // - CompilerThread
178
179 // ======= Thread ========
180 // Support for forcing alignment of thread objects for biased locking
181 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
182 if (UseBiasedLocking) {
183 const int alignment = markOopDesc::biased_lock_alignment;
184 size_t aligned_size = size + (alignment - sizeof(intptr_t));
185 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
186 : AllocateHeap(aligned_size, flags, CURRENT_PC,
187 AllocFailStrategy::RETURN_NULL);
188 void* aligned_addr = align_up(real_malloc_addr, alignment);
189 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
190 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
191 "JavaThread alignment code overflowed allocated storage");
192 if (aligned_addr != real_malloc_addr) {
193 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
194 p2i(real_malloc_addr),
195 p2i(aligned_addr));
196 }
197 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
198 return aligned_addr;
199 } else {
200 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
201 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
202 }
203 }
204
205 void Thread::operator delete(void* p) {
206 if (UseBiasedLocking) {
207 FreeHeap(((Thread*) p)->_real_malloc_address);
208 } else {
209 FreeHeap(p);
210 }
211 }
212
213 void JavaThread::smr_delete() {
214 if (_on_thread_list) {
215 ThreadsSMRSupport::smr_delete(this);
216 } else {
217 delete this;
218 }
219 }
220
221 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
222 // JavaThread
223
224
225 Thread::Thread() {
226 // stack and get_thread
227 set_stack_base(NULL);
228 set_stack_size(0);
229 set_self_raw_id(0);
230 set_lgrp_id(-1);
231 DEBUG_ONLY(clear_suspendible_thread();)
232
233 // allocated data structures
234 set_osthread(NULL);
235 set_resource_area(new (mtThread)ResourceArea());
236 DEBUG_ONLY(_current_resource_mark = NULL;)
237 set_handle_area(new (mtThread) HandleArea(NULL));
238 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
239 set_active_handles(NULL);
240 set_free_handle_block(NULL);
241 set_last_handle_mark(NULL);
242
243 // This initial value ==> never claimed.
244 _oops_do_parity = 0;
245 _threads_hazard_ptr = NULL;
246 _nested_threads_hazard_ptr = NULL;
247 _nested_threads_hazard_ptr_cnt = 0;
248 _rcu_counter = 0;
249
250 // the handle mark links itself to last_handle_mark
251 new HandleMark(this);
252
253 // plain initialization
254 debug_only(_owned_locks = NULL;)
255 debug_only(_allow_allocation_count = 0;)
256 NOT_PRODUCT(_allow_safepoint_count = 0;)
257 NOT_PRODUCT(_skip_gcalot = false;)
258 _jvmti_env_iteration_count = 0;
259 set_allocated_bytes(0);
260 _vm_operation_started_count = 0;
261 _vm_operation_completed_count = 0;
262 _current_pending_monitor = NULL;
263 _current_pending_monitor_is_from_java = true;
264 _current_waiting_monitor = NULL;
265 _num_nested_signal = 0;
266 omFreeList = NULL;
267 omFreeCount = 0;
268 omFreeProvision = 32;
269 omInUseList = NULL;
270 omInUseCount = 0;
271
272 #ifdef ASSERT
273 _visited_for_critical_count = false;
274 #endif
275
276 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
277 Monitor::_safepoint_check_sometimes);
278 _suspend_flags = 0;
279
280 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
281 _hashStateX = os::random();
282 _hashStateY = 842502087;
283 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
284 _hashStateW = 273326509;
285
286 _OnTrap = 0;
287 _schedctl = NULL;
288 _Stalled = 0;
289 _TypeTag = 0x2BAD;
290
291 // Many of the following fields are effectively final - immutable
292 // Note that nascent threads can't use the Native Monitor-Mutex
293 // construct until the _MutexEvent is initialized ...
294 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
295 // we might instead use a stack of ParkEvents that we could provision on-demand.
296 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
297 // and ::Release()
298 _ParkEvent = ParkEvent::Allocate(this);
299 _SleepEvent = ParkEvent::Allocate(this);
300 _MutexEvent = ParkEvent::Allocate(this);
301 _MuxEvent = ParkEvent::Allocate(this);
302
303 #ifdef CHECK_UNHANDLED_OOPS
304 if (CheckUnhandledOops) {
305 _unhandled_oops = new UnhandledOops(this);
306 }
307 #endif // CHECK_UNHANDLED_OOPS
308 #ifdef ASSERT
309 if (UseBiasedLocking) {
310 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
311 assert(this == _real_malloc_address ||
312 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
313 "bug in forced alignment of thread objects");
314 }
315 #endif // ASSERT
316
317 // Notify the barrier set that a thread is being created. Note that the
318 // main thread is created before a barrier set is available. The call to
319 // BarrierSet::on_thread_create() for the main thread is therefore deferred
320 // until it calls BarrierSet::set_barrier_set().
321 BarrierSet* const barrier_set = BarrierSet::barrier_set();
322 if (barrier_set != NULL) {
323 barrier_set->on_thread_create(this);
324 }
325 }
326
327 void Thread::initialize_thread_current() {
328 #ifndef USE_LIBRARY_BASED_TLS_ONLY
329 assert(_thr_current == NULL, "Thread::current already initialized");
330 _thr_current = this;
331 #endif
332 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
333 ThreadLocalStorage::set_thread(this);
334 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
335 }
336
337 void Thread::clear_thread_current() {
338 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
339 #ifndef USE_LIBRARY_BASED_TLS_ONLY
340 _thr_current = NULL;
341 #endif
342 ThreadLocalStorage::set_thread(NULL);
343 }
344
345 void Thread::record_stack_base_and_size() {
346 set_stack_base(os::current_stack_base());
347 set_stack_size(os::current_stack_size());
348 // CR 7190089: on Solaris, primordial thread's stack is adjusted
349 // in initialize_thread(). Without the adjustment, stack size is
350 // incorrect if stack is set to unlimited (ulimit -s unlimited).
351 // So far, only Solaris has real implementation of initialize_thread().
352 //
353 // set up any platform-specific state.
354 os::initialize_thread(this);
355
356 // Set stack limits after thread is initialized.
357 if (is_Java_thread()) {
358 ((JavaThread*) this)->set_stack_overflow_limit();
359 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
360 }
361 #if INCLUDE_NMT
362 // record thread's native stack, stack grows downward
363 MemTracker::record_thread_stack(stack_end(), stack_size());
364 #endif // INCLUDE_NMT
365 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
366 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
367 os::current_thread_id(), p2i(stack_base() - stack_size()),
368 p2i(stack_base()), stack_size()/1024);
369 }
370
371
372 Thread::~Thread() {
373 EVENT_THREAD_DESTRUCT(this);
374
375 // Notify the barrier set that a thread is being destroyed. Note that a barrier
376 // set might not be available if we encountered errors during bootstrapping.
377 BarrierSet* const barrier_set = BarrierSet::barrier_set();
378 if (barrier_set != NULL) {
379 barrier_set->on_thread_destroy(this);
380 }
381
382 // stack_base can be NULL if the thread is never started or exited before
383 // record_stack_base_and_size called. Although, we would like to ensure
384 // that all started threads do call record_stack_base_and_size(), there is
385 // not proper way to enforce that.
386 #if INCLUDE_NMT
387 if (_stack_base != NULL) {
388 MemTracker::release_thread_stack(stack_end(), stack_size());
389 #ifdef ASSERT
390 set_stack_base(NULL);
391 #endif
392 }
393 #endif // INCLUDE_NMT
394
395 // deallocate data structures
396 delete resource_area();
397 // since the handle marks are using the handle area, we have to deallocated the root
398 // handle mark before deallocating the thread's handle area,
399 assert(last_handle_mark() != NULL, "check we have an element");
400 delete last_handle_mark();
401 assert(last_handle_mark() == NULL, "check we have reached the end");
402
403 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
404 // We NULL out the fields for good hygiene.
405 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
406 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
407 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
408 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
409
410 delete handle_area();
411 delete metadata_handles();
412
413 // SR_handler uses this as a termination indicator -
414 // needs to happen before os::free_thread()
415 delete _SR_lock;
416 _SR_lock = NULL;
417
418 // osthread() can be NULL, if creation of thread failed.
419 if (osthread() != NULL) os::free_thread(osthread());
420
421 // clear Thread::current if thread is deleting itself.
422 // Needed to ensure JNI correctly detects non-attached threads.
423 if (this == Thread::current()) {
424 clear_thread_current();
425 }
426
427 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
428 }
429
430 // NOTE: dummy function for assertion purpose.
431 void Thread::run() {
432 ShouldNotReachHere();
433 }
434
435 #ifdef ASSERT
436 // A JavaThread is considered "dangling" if it is not the current
437 // thread, has been added the Threads list, the system is not at a
438 // safepoint and the Thread is not "protected".
439 //
440 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
441 assert(!thread->is_Java_thread() || Thread::current() == thread ||
442 !((JavaThread *) thread)->on_thread_list() ||
443 SafepointSynchronize::is_at_safepoint() ||
444 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
445 "possibility of dangling Thread pointer");
446 }
447 #endif
448
449 ThreadPriority Thread::get_priority(const Thread* const thread) {
450 ThreadPriority priority;
451 // Can return an error!
452 (void)os::get_priority(thread, priority);
453 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
454 return priority;
455 }
456
457 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
458 debug_only(check_for_dangling_thread_pointer(thread);)
459 // Can return an error!
460 (void)os::set_priority(thread, priority);
461 }
462
463
464 void Thread::start(Thread* thread) {
465 // Start is different from resume in that its safety is guaranteed by context or
466 // being called from a Java method synchronized on the Thread object.
467 if (!DisableStartThread) {
468 if (thread->is_Java_thread()) {
469 // Initialize the thread state to RUNNABLE before starting this thread.
470 // Can not set it after the thread started because we do not know the
471 // exact thread state at that time. It could be in MONITOR_WAIT or
472 // in SLEEPING or some other state.
473 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
474 java_lang_Thread::RUNNABLE);
475 }
476 os::start_thread(thread);
477 }
478 }
479
480 // Enqueue a VM_Operation to do the job for us - sometime later
481 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
482 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
483 VMThread::execute(vm_stop);
484 }
485
486
487 // Check if an external suspend request has completed (or has been
488 // cancelled). Returns true if the thread is externally suspended and
489 // false otherwise.
490 //
491 // The bits parameter returns information about the code path through
492 // the routine. Useful for debugging:
493 //
494 // set in is_ext_suspend_completed():
495 // 0x00000001 - routine was entered
496 // 0x00000010 - routine return false at end
497 // 0x00000100 - thread exited (return false)
498 // 0x00000200 - suspend request cancelled (return false)
499 // 0x00000400 - thread suspended (return true)
500 // 0x00001000 - thread is in a suspend equivalent state (return true)
501 // 0x00002000 - thread is native and walkable (return true)
502 // 0x00004000 - thread is native_trans and walkable (needed retry)
503 //
504 // set in wait_for_ext_suspend_completion():
505 // 0x00010000 - routine was entered
506 // 0x00020000 - suspend request cancelled before loop (return false)
507 // 0x00040000 - thread suspended before loop (return true)
508 // 0x00080000 - suspend request cancelled in loop (return false)
509 // 0x00100000 - thread suspended in loop (return true)
510 // 0x00200000 - suspend not completed during retry loop (return false)
511
512 // Helper class for tracing suspend wait debug bits.
513 //
514 // 0x00000100 indicates that the target thread exited before it could
515 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
516 // 0x00080000 each indicate a cancelled suspend request so they don't
517 // count as wait failures either.
518 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
519
520 class TraceSuspendDebugBits : public StackObj {
521 private:
522 JavaThread * jt;
523 bool is_wait;
524 bool called_by_wait; // meaningful when !is_wait
525 uint32_t * bits;
526
527 public:
528 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
529 uint32_t *_bits) {
530 jt = _jt;
531 is_wait = _is_wait;
532 called_by_wait = _called_by_wait;
533 bits = _bits;
534 }
535
536 ~TraceSuspendDebugBits() {
537 if (!is_wait) {
538 #if 1
539 // By default, don't trace bits for is_ext_suspend_completed() calls.
540 // That trace is very chatty.
541 return;
542 #else
543 if (!called_by_wait) {
544 // If tracing for is_ext_suspend_completed() is enabled, then only
545 // trace calls to it from wait_for_ext_suspend_completion()
546 return;
547 }
548 #endif
549 }
550
551 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
552 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
553 MutexLocker ml(Threads_lock); // needed for get_thread_name()
554 ResourceMark rm;
555
556 tty->print_cr(
557 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
558 jt->get_thread_name(), *bits);
559
560 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
561 }
562 }
563 }
564 };
565 #undef DEBUG_FALSE_BITS
566
567
568 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
569 uint32_t *bits) {
570 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
571
572 bool did_trans_retry = false; // only do thread_in_native_trans retry once
573 bool do_trans_retry; // flag to force the retry
574
575 *bits |= 0x00000001;
576
577 do {
578 do_trans_retry = false;
579
580 if (is_exiting()) {
581 // Thread is in the process of exiting. This is always checked
582 // first to reduce the risk of dereferencing a freed JavaThread.
583 *bits |= 0x00000100;
584 return false;
585 }
586
587 if (!is_external_suspend()) {
588 // Suspend request is cancelled. This is always checked before
589 // is_ext_suspended() to reduce the risk of a rogue resume
590 // confusing the thread that made the suspend request.
591 *bits |= 0x00000200;
592 return false;
593 }
594
595 if (is_ext_suspended()) {
596 // thread is suspended
597 *bits |= 0x00000400;
598 return true;
599 }
600
601 // Now that we no longer do hard suspends of threads running
602 // native code, the target thread can be changing thread state
603 // while we are in this routine:
604 //
605 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
606 //
607 // We save a copy of the thread state as observed at this moment
608 // and make our decision about suspend completeness based on the
609 // copy. This closes the race where the thread state is seen as
610 // _thread_in_native_trans in the if-thread_blocked check, but is
611 // seen as _thread_blocked in if-thread_in_native_trans check.
612 JavaThreadState save_state = thread_state();
613
614 if (save_state == _thread_blocked && is_suspend_equivalent()) {
615 // If the thread's state is _thread_blocked and this blocking
616 // condition is known to be equivalent to a suspend, then we can
617 // consider the thread to be externally suspended. This means that
618 // the code that sets _thread_blocked has been modified to do
619 // self-suspension if the blocking condition releases. We also
620 // used to check for CONDVAR_WAIT here, but that is now covered by
621 // the _thread_blocked with self-suspension check.
622 //
623 // Return true since we wouldn't be here unless there was still an
624 // external suspend request.
625 *bits |= 0x00001000;
626 return true;
627 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
628 // Threads running native code will self-suspend on native==>VM/Java
629 // transitions. If its stack is walkable (should always be the case
630 // unless this function is called before the actual java_suspend()
631 // call), then the wait is done.
632 *bits |= 0x00002000;
633 return true;
634 } else if (!called_by_wait && !did_trans_retry &&
635 save_state == _thread_in_native_trans &&
636 frame_anchor()->walkable()) {
637 // The thread is transitioning from thread_in_native to another
638 // thread state. check_safepoint_and_suspend_for_native_trans()
639 // will force the thread to self-suspend. If it hasn't gotten
640 // there yet we may have caught the thread in-between the native
641 // code check above and the self-suspend. Lucky us. If we were
642 // called by wait_for_ext_suspend_completion(), then it
643 // will be doing the retries so we don't have to.
644 //
645 // Since we use the saved thread state in the if-statement above,
646 // there is a chance that the thread has already transitioned to
647 // _thread_blocked by the time we get here. In that case, we will
648 // make a single unnecessary pass through the logic below. This
649 // doesn't hurt anything since we still do the trans retry.
650
651 *bits |= 0x00004000;
652
653 // Once the thread leaves thread_in_native_trans for another
654 // thread state, we break out of this retry loop. We shouldn't
655 // need this flag to prevent us from getting back here, but
656 // sometimes paranoia is good.
657 did_trans_retry = true;
658
659 // We wait for the thread to transition to a more usable state.
660 for (int i = 1; i <= SuspendRetryCount; i++) {
661 // We used to do an "os::yield_all(i)" call here with the intention
662 // that yielding would increase on each retry. However, the parameter
663 // is ignored on Linux which means the yield didn't scale up. Waiting
664 // on the SR_lock below provides a much more predictable scale up for
665 // the delay. It also provides a simple/direct point to check for any
666 // safepoint requests from the VMThread
667
668 // temporarily drops SR_lock while doing wait with safepoint check
669 // (if we're a JavaThread - the WatcherThread can also call this)
670 // and increase delay with each retry
671 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
672
673 // check the actual thread state instead of what we saved above
674 if (thread_state() != _thread_in_native_trans) {
675 // the thread has transitioned to another thread state so
676 // try all the checks (except this one) one more time.
677 do_trans_retry = true;
678 break;
679 }
680 } // end retry loop
681
682
683 }
684 } while (do_trans_retry);
685
686 *bits |= 0x00000010;
687 return false;
688 }
689
690 // Wait for an external suspend request to complete (or be cancelled).
691 // Returns true if the thread is externally suspended and false otherwise.
692 //
693 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
694 uint32_t *bits) {
695 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
696 false /* !called_by_wait */, bits);
697
698 // local flag copies to minimize SR_lock hold time
699 bool is_suspended;
700 bool pending;
701 uint32_t reset_bits;
702
703 // set a marker so is_ext_suspend_completed() knows we are the caller
704 *bits |= 0x00010000;
705
706 // We use reset_bits to reinitialize the bits value at the top of
707 // each retry loop. This allows the caller to make use of any
708 // unused bits for their own marking purposes.
709 reset_bits = *bits;
710
711 {
712 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
713 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
714 delay, bits);
715 pending = is_external_suspend();
716 }
717 // must release SR_lock to allow suspension to complete
718
719 if (!pending) {
720 // A cancelled suspend request is the only false return from
721 // is_ext_suspend_completed() that keeps us from entering the
722 // retry loop.
723 *bits |= 0x00020000;
724 return false;
725 }
726
727 if (is_suspended) {
728 *bits |= 0x00040000;
729 return true;
730 }
731
732 for (int i = 1; i <= retries; i++) {
733 *bits = reset_bits; // reinit to only track last retry
734
735 // We used to do an "os::yield_all(i)" call here with the intention
736 // that yielding would increase on each retry. However, the parameter
737 // is ignored on Linux which means the yield didn't scale up. Waiting
738 // on the SR_lock below provides a much more predictable scale up for
739 // the delay. It also provides a simple/direct point to check for any
740 // safepoint requests from the VMThread
741
742 {
743 MutexLocker ml(SR_lock());
744 // wait with safepoint check (if we're a JavaThread - the WatcherThread
745 // can also call this) and increase delay with each retry
746 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
747
748 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
749 delay, bits);
750
751 // It is possible for the external suspend request to be cancelled
752 // (by a resume) before the actual suspend operation is completed.
753 // Refresh our local copy to see if we still need to wait.
754 pending = is_external_suspend();
755 }
756
757 if (!pending) {
758 // A cancelled suspend request is the only false return from
759 // is_ext_suspend_completed() that keeps us from staying in the
760 // retry loop.
761 *bits |= 0x00080000;
762 return false;
763 }
764
765 if (is_suspended) {
766 *bits |= 0x00100000;
767 return true;
768 }
769 } // end retry loop
770
771 // thread did not suspend after all our retries
772 *bits |= 0x00200000;
773 return false;
774 }
775
776 // Called from API entry points which perform stack walking. If the
777 // associated JavaThread is the current thread, then wait_for_suspend
778 // is not used. Otherwise, it determines if we should wait for the
779 // "other" thread to complete external suspension. (NOTE: in future
780 // releases the suspension mechanism should be reimplemented so this
781 // is not necessary.)
782 //
783 bool
784 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
785 if (this != JavaThread::current()) {
786 // "other" threads require special handling.
787 if (wait_for_suspend) {
788 // We are allowed to wait for the external suspend to complete
789 // so give the other thread a chance to get suspended.
790 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
791 SuspendRetryDelay, bits)) {
792 // Didn't make it so let the caller know.
793 return false;
794 }
795 }
796 // We aren't allowed to wait for the external suspend to complete
797 // so if the other thread isn't externally suspended we need to
798 // let the caller know.
799 else if (!is_ext_suspend_completed_with_lock(bits)) {
800 return false;
801 }
802 }
803
804 return true;
805 }
806
807 #ifndef PRODUCT
808 void JavaThread::record_jump(address target, address instr, const char* file,
809 int line) {
810
811 // This should not need to be atomic as the only way for simultaneous
812 // updates is via interrupts. Even then this should be rare or non-existent
813 // and we don't care that much anyway.
814
815 int index = _jmp_ring_index;
816 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
817 _jmp_ring[index]._target = (intptr_t) target;
818 _jmp_ring[index]._instruction = (intptr_t) instr;
819 _jmp_ring[index]._file = file;
820 _jmp_ring[index]._line = line;
821 }
822 #endif // PRODUCT
823
824 void Thread::interrupt(Thread* thread) {
825 debug_only(check_for_dangling_thread_pointer(thread);)
826 os::interrupt(thread);
827 }
828
829 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
830 debug_only(check_for_dangling_thread_pointer(thread);)
831 // Note: If clear_interrupted==false, this simply fetches and
832 // returns the value of the field osthread()->interrupted().
833 return os::is_interrupted(thread, clear_interrupted);
834 }
835
836
837 // GC Support
838 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
839 int thread_parity = _oops_do_parity;
840 if (thread_parity != strong_roots_parity) {
841 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
842 if (res == thread_parity) {
843 return true;
844 } else {
845 guarantee(res == strong_roots_parity, "Or else what?");
846 return false;
847 }
848 }
849 return false;
850 }
851
852 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
853 active_handles()->oops_do(f);
854 // Do oop for ThreadShadow
855 f->do_oop((oop*)&_pending_exception);
856 handle_area()->oops_do(f);
857
858 if (MonitorInUseLists) {
859 // When using thread local monitor lists, we scan them here,
860 // and the remaining global monitors in ObjectSynchronizer::oops_do().
861 ObjectSynchronizer::thread_local_used_oops_do(this, f);
862 }
863 }
864
865 void Thread::metadata_handles_do(void f(Metadata*)) {
866 // Only walk the Handles in Thread.
867 if (metadata_handles() != NULL) {
868 for (int i = 0; i< metadata_handles()->length(); i++) {
869 f(metadata_handles()->at(i));
870 }
871 }
872 }
873
874 void Thread::print_on(outputStream* st) const {
875 // get_priority assumes osthread initialized
876 if (osthread() != NULL) {
877 int os_prio;
878 if (os::get_native_priority(this, &os_prio) == OS_OK) {
879 st->print("os_prio=%d ", os_prio);
880 }
881 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
882 osthread()->print_on(st);
883 }
884 if (_threads_hazard_ptr != NULL) {
885 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
886 }
887 if (_nested_threads_hazard_ptr != NULL) {
888 print_nested_threads_hazard_ptrs_on(st);
889 }
890 st->print(" ");
891 debug_only(if (WizardMode) print_owned_locks_on(st);)
892 }
893
894 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
895 assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
896
897 if (EnableThreadSMRStatistics) {
898 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
899 }
900 st->print(", _nested_threads_hazard_ptrs=");
901 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
902 node = node->next()) {
903 if (node != _nested_threads_hazard_ptr) {
904 // First node does not need a comma-space separator.
905 st->print(", ");
906 }
907 st->print(INTPTR_FORMAT, p2i(node->t_list()));
908 }
909 }
910
911 // Thread::print_on_error() is called by fatal error handler. Don't use
912 // any lock or allocate memory.
913 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
914 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
915
916 if (is_VM_thread()) { st->print("VMThread"); }
917 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
918 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
919 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
920 else { st->print("Thread"); }
921
922 if (is_Named_thread()) {
923 st->print(" \"%s\"", name());
924 }
925
926 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
927 p2i(stack_end()), p2i(stack_base()));
928
929 if (osthread()) {
930 st->print(" [id=%d]", osthread()->thread_id());
931 }
932
933 if (_threads_hazard_ptr != NULL) {
934 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
935 }
936 if (_nested_threads_hazard_ptr != NULL) {
937 print_nested_threads_hazard_ptrs_on(st);
938 }
939 }
940
941 void Thread::print_value_on(outputStream* st) const {
942 if (is_Named_thread()) {
943 st->print(" \"%s\" ", name());
944 }
945 st->print(INTPTR_FORMAT, p2i(this)); // print address
946 }
947
948 #ifdef ASSERT
949 void Thread::print_owned_locks_on(outputStream* st) const {
950 Monitor *cur = _owned_locks;
951 if (cur == NULL) {
952 st->print(" (no locks) ");
953 } else {
954 st->print_cr(" Locks owned:");
955 while (cur) {
956 cur->print_on(st);
957 cur = cur->next();
958 }
959 }
960 }
961
962 static int ref_use_count = 0;
963
964 bool Thread::owns_locks_but_compiled_lock() const {
965 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
966 if (cur != Compile_lock) return true;
967 }
968 return false;
969 }
970
971
972 #endif
973
974 #ifndef PRODUCT
975
976 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
977 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
978 // no threads which allow_vm_block's are held
979 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
980 // Check if current thread is allowed to block at a safepoint
981 if (!(_allow_safepoint_count == 0)) {
982 fatal("Possible safepoint reached by thread that does not allow it");
983 }
984 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
985 fatal("LEAF method calling lock?");
986 }
987
988 #ifdef ASSERT
989 if (potential_vm_operation && is_Java_thread()
990 && !Universe::is_bootstrapping()) {
991 // Make sure we do not hold any locks that the VM thread also uses.
992 // This could potentially lead to deadlocks
993 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
994 // Threads_lock is special, since the safepoint synchronization will not start before this is
995 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
996 // since it is used to transfer control between JavaThreads and the VMThread
997 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
998 if ((cur->allow_vm_block() &&
999 cur != Threads_lock &&
1000 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1001 cur != VMOperationRequest_lock &&
1002 cur != VMOperationQueue_lock) ||
1003 cur->rank() == Mutex::special) {
1004 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1005 }
1006 }
1007 }
1008
1009 if (GCALotAtAllSafepoints) {
1010 // We could enter a safepoint here and thus have a gc
1011 InterfaceSupport::check_gc_alot();
1012 }
1013 #endif
1014 }
1015 #endif
1016
1017 bool Thread::is_in_stack(address adr) const {
1018 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1019 address end = os::current_stack_pointer();
1020 // Allow non Java threads to call this without stack_base
1021 if (_stack_base == NULL) return true;
1022 if (stack_base() >= adr && adr >= end) return true;
1023
1024 return false;
1025 }
1026
1027 bool Thread::is_in_usable_stack(address adr) const {
1028 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1029 size_t usable_stack_size = _stack_size - stack_guard_size;
1030
1031 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1032 }
1033
1034
1035 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1036 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1037 // used for compilation in the future. If that change is made, the need for these methods
1038 // should be revisited, and they should be removed if possible.
1039
1040 bool Thread::is_lock_owned(address adr) const {
1041 return on_local_stack(adr);
1042 }
1043
1044 bool Thread::set_as_starting_thread() {
1045 // NOTE: this must be called inside the main thread.
1046 return os::create_main_thread((JavaThread*)this);
1047 }
1048
1049 static void initialize_class(Symbol* class_name, TRAPS) {
1050 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1051 InstanceKlass::cast(klass)->initialize(CHECK);
1052 }
1053
1054
1055 // Creates the initial ThreadGroup
1056 static Handle create_initial_thread_group(TRAPS) {
1057 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1058 InstanceKlass* ik = InstanceKlass::cast(k);
1059
1060 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1061 {
1062 JavaValue result(T_VOID);
1063 JavaCalls::call_special(&result,
1064 system_instance,
1065 ik,
1066 vmSymbols::object_initializer_name(),
1067 vmSymbols::void_method_signature(),
1068 CHECK_NH);
1069 }
1070 Universe::set_system_thread_group(system_instance());
1071
1072 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1073 {
1074 JavaValue result(T_VOID);
1075 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1076 JavaCalls::call_special(&result,
1077 main_instance,
1078 ik,
1079 vmSymbols::object_initializer_name(),
1080 vmSymbols::threadgroup_string_void_signature(),
1081 system_instance,
1082 string,
1083 CHECK_NH);
1084 }
1085 return main_instance;
1086 }
1087
1088 // Creates the initial Thread
1089 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1090 TRAPS) {
1091 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1092 InstanceKlass* ik = InstanceKlass::cast(k);
1093 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1094
1095 java_lang_Thread::set_thread(thread_oop(), thread);
1096 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1097 thread->set_threadObj(thread_oop());
1098
1099 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1100
1101 JavaValue result(T_VOID);
1102 JavaCalls::call_special(&result, thread_oop,
1103 ik,
1104 vmSymbols::object_initializer_name(),
1105 vmSymbols::threadgroup_string_void_signature(),
1106 thread_group,
1107 string,
1108 CHECK_NULL);
1109 return thread_oop();
1110 }
1111
1112 char java_runtime_name[128] = "";
1113 char java_runtime_version[128] = "";
1114
1115 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1116 static const char* get_java_runtime_name(TRAPS) {
1117 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1118 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1119 fieldDescriptor fd;
1120 bool found = k != NULL &&
1121 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1122 vmSymbols::string_signature(), &fd);
1123 if (found) {
1124 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1125 if (name_oop == NULL) {
1126 return NULL;
1127 }
1128 const char* name = java_lang_String::as_utf8_string(name_oop,
1129 java_runtime_name,
1130 sizeof(java_runtime_name));
1131 return name;
1132 } else {
1133 return NULL;
1134 }
1135 }
1136
1137 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1138 static const char* get_java_runtime_version(TRAPS) {
1139 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1140 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1141 fieldDescriptor fd;
1142 bool found = k != NULL &&
1143 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1144 vmSymbols::string_signature(), &fd);
1145 if (found) {
1146 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1147 if (name_oop == NULL) {
1148 return NULL;
1149 }
1150 const char* name = java_lang_String::as_utf8_string(name_oop,
1151 java_runtime_version,
1152 sizeof(java_runtime_version));
1153 return name;
1154 } else {
1155 return NULL;
1156 }
1157 }
1158
1159 // General purpose hook into Java code, run once when the VM is initialized.
1160 // The Java library method itself may be changed independently from the VM.
1161 static void call_postVMInitHook(TRAPS) {
1162 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1163 if (klass != NULL) {
1164 JavaValue result(T_VOID);
1165 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1166 vmSymbols::void_method_signature(),
1167 CHECK);
1168 }
1169 }
1170
1171 static void reset_vm_info_property(TRAPS) {
1172 // the vm info string
1173 ResourceMark rm(THREAD);
1174 const char *vm_info = VM_Version::vm_info_string();
1175
1176 // java.lang.System class
1177 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1178
1179 // setProperty arguments
1180 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1181 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1182
1183 // return value
1184 JavaValue r(T_OBJECT);
1185
1186 // public static String setProperty(String key, String value);
1187 JavaCalls::call_static(&r,
1188 klass,
1189 vmSymbols::setProperty_name(),
1190 vmSymbols::string_string_string_signature(),
1191 key_str,
1192 value_str,
1193 CHECK);
1194 }
1195
1196
1197 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1198 bool daemon, TRAPS) {
1199 assert(thread_group.not_null(), "thread group should be specified");
1200 assert(threadObj() == NULL, "should only create Java thread object once");
1201
1202 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1203 InstanceKlass* ik = InstanceKlass::cast(k);
1204 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1205
1206 java_lang_Thread::set_thread(thread_oop(), this);
1207 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1208 set_threadObj(thread_oop());
1209
1210 JavaValue result(T_VOID);
1211 if (thread_name != NULL) {
1212 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1213 // Thread gets assigned specified name and null target
1214 JavaCalls::call_special(&result,
1215 thread_oop,
1216 ik,
1217 vmSymbols::object_initializer_name(),
1218 vmSymbols::threadgroup_string_void_signature(),
1219 thread_group, // Argument 1
1220 name, // Argument 2
1221 THREAD);
1222 } else {
1223 // Thread gets assigned name "Thread-nnn" and null target
1224 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1225 JavaCalls::call_special(&result,
1226 thread_oop,
1227 ik,
1228 vmSymbols::object_initializer_name(),
1229 vmSymbols::threadgroup_runnable_void_signature(),
1230 thread_group, // Argument 1
1231 Handle(), // Argument 2
1232 THREAD);
1233 }
1234
1235
1236 if (daemon) {
1237 java_lang_Thread::set_daemon(thread_oop());
1238 }
1239
1240 if (HAS_PENDING_EXCEPTION) {
1241 return;
1242 }
1243
1244 Klass* group = SystemDictionary::ThreadGroup_klass();
1245 Handle threadObj(THREAD, this->threadObj());
1246
1247 JavaCalls::call_special(&result,
1248 thread_group,
1249 group,
1250 vmSymbols::add_method_name(),
1251 vmSymbols::thread_void_signature(),
1252 threadObj, // Arg 1
1253 THREAD);
1254 }
1255
1256 // NamedThread -- non-JavaThread subclasses with multiple
1257 // uniquely named instances should derive from this.
1258 NamedThread::NamedThread() : Thread() {
1259 _name = NULL;
1260 _processed_thread = NULL;
1261 _gc_id = GCId::undefined();
1262 }
1263
1264 NamedThread::~NamedThread() {
1265 if (_name != NULL) {
1266 FREE_C_HEAP_ARRAY(char, _name);
1267 _name = NULL;
1268 }
1269 }
1270
1271 void NamedThread::set_name(const char* format, ...) {
1272 guarantee(_name == NULL, "Only get to set name once.");
1273 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1274 guarantee(_name != NULL, "alloc failure");
1275 va_list ap;
1276 va_start(ap, format);
1277 jio_vsnprintf(_name, max_name_len, format, ap);
1278 va_end(ap);
1279 }
1280
1281 void NamedThread::initialize_named_thread() {
1282 set_native_thread_name(name());
1283 }
1284
1285 void NamedThread::print_on(outputStream* st) const {
1286 st->print("\"%s\" ", name());
1287 Thread::print_on(st);
1288 st->cr();
1289 }
1290
1291
1292 // ======= WatcherThread ========
1293
1294 // The watcher thread exists to simulate timer interrupts. It should
1295 // be replaced by an abstraction over whatever native support for
1296 // timer interrupts exists on the platform.
1297
1298 WatcherThread* WatcherThread::_watcher_thread = NULL;
1299 bool WatcherThread::_startable = false;
1300 volatile bool WatcherThread::_should_terminate = false;
1301
1302 WatcherThread::WatcherThread() : Thread() {
1303 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1304 if (os::create_thread(this, os::watcher_thread)) {
1305 _watcher_thread = this;
1306
1307 // Set the watcher thread to the highest OS priority which should not be
1308 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1309 // is created. The only normal thread using this priority is the reference
1310 // handler thread, which runs for very short intervals only.
1311 // If the VMThread's priority is not lower than the WatcherThread profiling
1312 // will be inaccurate.
1313 os::set_priority(this, MaxPriority);
1314 if (!DisableStartThread) {
1315 os::start_thread(this);
1316 }
1317 }
1318 }
1319
1320 int WatcherThread::sleep() const {
1321 // The WatcherThread does not participate in the safepoint protocol
1322 // for the PeriodicTask_lock because it is not a JavaThread.
1323 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1324
1325 if (_should_terminate) {
1326 // check for termination before we do any housekeeping or wait
1327 return 0; // we did not sleep.
1328 }
1329
1330 // remaining will be zero if there are no tasks,
1331 // causing the WatcherThread to sleep until a task is
1332 // enrolled
1333 int remaining = PeriodicTask::time_to_wait();
1334 int time_slept = 0;
1335
1336 // we expect this to timeout - we only ever get unparked when
1337 // we should terminate or when a new task has been enrolled
1338 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1339
1340 jlong time_before_loop = os::javaTimeNanos();
1341
1342 while (true) {
1343 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1344 remaining);
1345 jlong now = os::javaTimeNanos();
1346
1347 if (remaining == 0) {
1348 // if we didn't have any tasks we could have waited for a long time
1349 // consider the time_slept zero and reset time_before_loop
1350 time_slept = 0;
1351 time_before_loop = now;
1352 } else {
1353 // need to recalculate since we might have new tasks in _tasks
1354 time_slept = (int) ((now - time_before_loop) / 1000000);
1355 }
1356
1357 // Change to task list or spurious wakeup of some kind
1358 if (timedout || _should_terminate) {
1359 break;
1360 }
1361
1362 remaining = PeriodicTask::time_to_wait();
1363 if (remaining == 0) {
1364 // Last task was just disenrolled so loop around and wait until
1365 // another task gets enrolled
1366 continue;
1367 }
1368
1369 remaining -= time_slept;
1370 if (remaining <= 0) {
1371 break;
1372 }
1373 }
1374
1375 return time_slept;
1376 }
1377
1378 void WatcherThread::run() {
1379 assert(this == watcher_thread(), "just checking");
1380
1381 this->record_stack_base_and_size();
1382 this->set_native_thread_name(this->name());
1383 this->set_active_handles(JNIHandleBlock::allocate_block());
1384 while (true) {
1385 assert(watcher_thread() == Thread::current(), "thread consistency check");
1386 assert(watcher_thread() == this, "thread consistency check");
1387
1388 // Calculate how long it'll be until the next PeriodicTask work
1389 // should be done, and sleep that amount of time.
1390 int time_waited = sleep();
1391
1392 if (VMError::is_error_reported()) {
1393 // A fatal error has happened, the error handler(VMError::report_and_die)
1394 // should abort JVM after creating an error log file. However in some
1395 // rare cases, the error handler itself might deadlock. Here periodically
1396 // check for error reporting timeouts, and if it happens, just proceed to
1397 // abort the VM.
1398
1399 // This code is in WatcherThread because WatcherThread wakes up
1400 // periodically so the fatal error handler doesn't need to do anything;
1401 // also because the WatcherThread is less likely to crash than other
1402 // threads.
1403
1404 for (;;) {
1405 // Note: we use naked sleep in this loop because we want to avoid using
1406 // any kind of VM infrastructure which may be broken at this point.
1407 if (VMError::check_timeout()) {
1408 // We hit error reporting timeout. Error reporting was interrupted and
1409 // will be wrapping things up now (closing files etc). Give it some more
1410 // time, then quit the VM.
1411 os::naked_short_sleep(200);
1412 // Print a message to stderr.
1413 fdStream err(defaultStream::output_fd());
1414 err.print_raw_cr("# [ timer expired, abort... ]");
1415 // skip atexit/vm_exit/vm_abort hooks
1416 os::die();
1417 }
1418
1419 // Wait a second, then recheck for timeout.
1420 os::naked_short_sleep(999);
1421 }
1422 }
1423
1424 if (_should_terminate) {
1425 // check for termination before posting the next tick
1426 break;
1427 }
1428
1429 PeriodicTask::real_time_tick(time_waited);
1430 }
1431
1432 // Signal that it is terminated
1433 {
1434 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1435 _watcher_thread = NULL;
1436 Terminator_lock->notify();
1437 }
1438 }
1439
1440 void WatcherThread::start() {
1441 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1442
1443 if (watcher_thread() == NULL && _startable) {
1444 _should_terminate = false;
1445 // Create the single instance of WatcherThread
1446 new WatcherThread();
1447 }
1448 }
1449
1450 void WatcherThread::make_startable() {
1451 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1452 _startable = true;
1453 }
1454
1455 void WatcherThread::stop() {
1456 {
1457 // Follow normal safepoint aware lock enter protocol since the
1458 // WatcherThread is stopped by another JavaThread.
1459 MutexLocker ml(PeriodicTask_lock);
1460 _should_terminate = true;
1461
1462 WatcherThread* watcher = watcher_thread();
1463 if (watcher != NULL) {
1464 // unpark the WatcherThread so it can see that it should terminate
1465 watcher->unpark();
1466 }
1467 }
1468
1469 MutexLocker mu(Terminator_lock);
1470
1471 while (watcher_thread() != NULL) {
1472 // This wait should make safepoint checks, wait without a timeout,
1473 // and wait as a suspend-equivalent condition.
1474 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1475 Mutex::_as_suspend_equivalent_flag);
1476 }
1477 }
1478
1479 void WatcherThread::unpark() {
1480 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1481 PeriodicTask_lock->notify();
1482 }
1483
1484 void WatcherThread::print_on(outputStream* st) const {
1485 st->print("\"%s\" ", name());
1486 Thread::print_on(st);
1487 st->cr();
1488 }
1489
1490 // ======= JavaThread ========
1491
1492 #if INCLUDE_JVMCI
1493
1494 jlong* JavaThread::_jvmci_old_thread_counters;
1495
1496 bool jvmci_counters_include(JavaThread* thread) {
1497 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1498 }
1499
1500 void JavaThread::collect_counters(typeArrayOop array) {
1501 if (JVMCICounterSize > 0) {
1502 MutexLocker tl(Threads_lock);
1503 JavaThreadIteratorWithHandle jtiwh;
1504 for (int i = 0; i < array->length(); i++) {
1505 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1506 }
1507 for (; JavaThread *tp = jtiwh.next(); ) {
1508 if (jvmci_counters_include(tp)) {
1509 for (int i = 0; i < array->length(); i++) {
1510 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1511 }
1512 }
1513 }
1514 }
1515 }
1516
1517 #endif // INCLUDE_JVMCI
1518
1519 // A JavaThread is a normal Java thread
1520
1521 void JavaThread::initialize() {
1522 // Initialize fields
1523
1524 set_saved_exception_pc(NULL);
1525 set_threadObj(NULL);
1526 _anchor.clear();
1527 set_entry_point(NULL);
1528 set_jni_functions(jni_functions());
1529 set_callee_target(NULL);
1530 set_vm_result(NULL);
1531 set_vm_result_2(NULL);
1532 set_vframe_array_head(NULL);
1533 set_vframe_array_last(NULL);
1534 set_deferred_locals(NULL);
1535 set_deopt_mark(NULL);
1536 set_deopt_compiled_method(NULL);
1537 clear_must_deopt_id();
1538 set_monitor_chunks(NULL);
1539 set_next(NULL);
1540 _on_thread_list = false;
1541 set_thread_state(_thread_new);
1542 _terminated = _not_terminated;
1543 _privileged_stack_top = NULL;
1544 _array_for_gc = NULL;
1545 _suspend_equivalent = false;
1546 _in_deopt_handler = 0;
1547 _doing_unsafe_access = false;
1548 _stack_guard_state = stack_guard_unused;
1549 #if INCLUDE_JVMCI
1550 _pending_monitorenter = false;
1551 _pending_deoptimization = -1;
1552 _pending_failed_speculation = NULL;
1553 _pending_transfer_to_interpreter = false;
1554 _adjusting_comp_level = false;
1555 _jvmci._alternate_call_target = NULL;
1556 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1557 if (JVMCICounterSize > 0) {
1558 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1559 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1560 } else {
1561 _jvmci_counters = NULL;
1562 }
1563 #endif // INCLUDE_JVMCI
1564 _reserved_stack_activation = NULL; // stack base not known yet
1565 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1566 _exception_pc = 0;
1567 _exception_handler_pc = 0;
1568 _is_method_handle_return = 0;
1569 _jvmti_thread_state= NULL;
1570 _should_post_on_exceptions_flag = JNI_FALSE;
1571 _jvmti_get_loaded_classes_closure = NULL;
1572 _interp_only_mode = 0;
1573 _special_runtime_exit_condition = _no_async_condition;
1574 _pending_async_exception = NULL;
1575 _thread_stat = NULL;
1576 _thread_stat = new ThreadStatistics();
1577 _blocked_on_compilation = false;
1578 _jni_active_critical = 0;
1579 _pending_jni_exception_check_fn = NULL;
1580 _do_not_unlock_if_synchronized = false;
1581 _cached_monitor_info = NULL;
1582 _parker = Parker::Allocate(this);
1583
1584 #ifndef PRODUCT
1585 _jmp_ring_index = 0;
1586 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1587 record_jump(NULL, NULL, NULL, 0);
1588 }
1589 #endif // PRODUCT
1590
1591 // Setup safepoint state info for this thread
1592 ThreadSafepointState::create(this);
1593
1594 debug_only(_java_call_counter = 0);
1595
1596 // JVMTI PopFrame support
1597 _popframe_condition = popframe_inactive;
1598 _popframe_preserved_args = NULL;
1599 _popframe_preserved_args_size = 0;
1600 _frames_to_pop_failed_realloc = 0;
1601
1602 if (SafepointMechanism::uses_thread_local_poll()) {
1603 SafepointMechanism::initialize_header(this);
1604 }
1605
1606 pd_initialize();
1607 }
1608
1609 JavaThread::JavaThread(bool is_attaching_via_jni) :
1610 Thread() {
1611 initialize();
1612 if (is_attaching_via_jni) {
1613 _jni_attach_state = _attaching_via_jni;
1614 } else {
1615 _jni_attach_state = _not_attaching_via_jni;
1616 }
1617 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1618 }
1619
1620 bool JavaThread::reguard_stack(address cur_sp) {
1621 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1622 && _stack_guard_state != stack_guard_reserved_disabled) {
1623 return true; // Stack already guarded or guard pages not needed.
1624 }
1625
1626 if (register_stack_overflow()) {
1627 // For those architectures which have separate register and
1628 // memory stacks, we must check the register stack to see if
1629 // it has overflowed.
1630 return false;
1631 }
1632
1633 // Java code never executes within the yellow zone: the latter is only
1634 // there to provoke an exception during stack banging. If java code
1635 // is executing there, either StackShadowPages should be larger, or
1636 // some exception code in c1, c2 or the interpreter isn't unwinding
1637 // when it should.
1638 guarantee(cur_sp > stack_reserved_zone_base(),
1639 "not enough space to reguard - increase StackShadowPages");
1640 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1641 enable_stack_yellow_reserved_zone();
1642 if (reserved_stack_activation() != stack_base()) {
1643 set_reserved_stack_activation(stack_base());
1644 }
1645 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1646 set_reserved_stack_activation(stack_base());
1647 enable_stack_reserved_zone();
1648 }
1649 return true;
1650 }
1651
1652 bool JavaThread::reguard_stack(void) {
1653 return reguard_stack(os::current_stack_pointer());
1654 }
1655
1656
1657 void JavaThread::block_if_vm_exited() {
1658 if (_terminated == _vm_exited) {
1659 // _vm_exited is set at safepoint, and Threads_lock is never released
1660 // we will block here forever
1661 Threads_lock->lock_without_safepoint_check();
1662 ShouldNotReachHere();
1663 }
1664 }
1665
1666
1667 // Remove this ifdef when C1 is ported to the compiler interface.
1668 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1669 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1670
1671 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1672 Thread() {
1673 initialize();
1674 _jni_attach_state = _not_attaching_via_jni;
1675 set_entry_point(entry_point);
1676 // Create the native thread itself.
1677 // %note runtime_23
1678 os::ThreadType thr_type = os::java_thread;
1679 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1680 os::java_thread;
1681 os::create_thread(this, thr_type, stack_sz);
1682 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1683 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1684 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1685 // the exception consists of creating the exception object & initializing it, initialization
1686 // will leave the VM via a JavaCall and then all locks must be unlocked).
1687 //
1688 // The thread is still suspended when we reach here. Thread must be explicit started
1689 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1690 // by calling Threads:add. The reason why this is not done here, is because the thread
1691 // object must be fully initialized (take a look at JVM_Start)
1692 }
1693
1694 JavaThread::~JavaThread() {
1695
1696 // JSR166 -- return the parker to the free list
1697 Parker::Release(_parker);
1698 _parker = NULL;
1699
1700 // Free any remaining previous UnrollBlock
1701 vframeArray* old_array = vframe_array_last();
1702
1703 if (old_array != NULL) {
1704 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1705 old_array->set_unroll_block(NULL);
1706 delete old_info;
1707 delete old_array;
1708 }
1709
1710 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1711 if (deferred != NULL) {
1712 // This can only happen if thread is destroyed before deoptimization occurs.
1713 assert(deferred->length() != 0, "empty array!");
1714 do {
1715 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1716 deferred->remove_at(0);
1717 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1718 delete dlv;
1719 } while (deferred->length() != 0);
1720 delete deferred;
1721 }
1722
1723 // All Java related clean up happens in exit
1724 ThreadSafepointState::destroy(this);
1725 if (_thread_stat != NULL) delete _thread_stat;
1726
1727 #if INCLUDE_JVMCI
1728 if (JVMCICounterSize > 0) {
1729 if (jvmci_counters_include(this)) {
1730 for (int i = 0; i < JVMCICounterSize; i++) {
1731 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1732 }
1733 }
1734 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1735 }
1736 #endif // INCLUDE_JVMCI
1737 }
1738
1739
1740 // The first routine called by a new Java thread
1741 void JavaThread::run() {
1742 // initialize thread-local alloc buffer related fields
1743 this->initialize_tlab();
1744
1745 // used to test validity of stack trace backs
1746 this->record_base_of_stack_pointer();
1747
1748 // Record real stack base and size.
1749 this->record_stack_base_and_size();
1750
1751 this->create_stack_guard_pages();
1752
1753 this->cache_global_variables();
1754
1755 // Thread is now sufficient initialized to be handled by the safepoint code as being
1756 // in the VM. Change thread state from _thread_new to _thread_in_vm
1757 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1758
1759 assert(JavaThread::current() == this, "sanity check");
1760 assert(!Thread::current()->owns_locks(), "sanity check");
1761
1762 DTRACE_THREAD_PROBE(start, this);
1763
1764 // This operation might block. We call that after all safepoint checks for a new thread has
1765 // been completed.
1766 this->set_active_handles(JNIHandleBlock::allocate_block());
1767
1768 if (JvmtiExport::should_post_thread_life()) {
1769 JvmtiExport::post_thread_start(this);
1770 }
1771
1772 EventThreadStart event;
1773 if (event.should_commit()) {
1774 event.set_thread(THREAD_TRACE_ID(this));
1775 event.commit();
1776 }
1777
1778 // We call another function to do the rest so we are sure that the stack addresses used
1779 // from there will be lower than the stack base just computed
1780 thread_main_inner();
1781
1782 // Note, thread is no longer valid at this point!
1783 }
1784
1785
1786 void JavaThread::thread_main_inner() {
1787 assert(JavaThread::current() == this, "sanity check");
1788 assert(this->threadObj() != NULL, "just checking");
1789
1790 // Execute thread entry point unless this thread has a pending exception
1791 // or has been stopped before starting.
1792 // Note: Due to JVM_StopThread we can have pending exceptions already!
1793 if (!this->has_pending_exception() &&
1794 !java_lang_Thread::is_stillborn(this->threadObj())) {
1795 {
1796 ResourceMark rm(this);
1797 this->set_native_thread_name(this->get_thread_name());
1798 }
1799 HandleMark hm(this);
1800 this->entry_point()(this, this);
1801 }
1802
1803 DTRACE_THREAD_PROBE(stop, this);
1804
1805 this->exit(false);
1806 this->smr_delete();
1807 }
1808
1809
1810 static void ensure_join(JavaThread* thread) {
1811 // We do not need to grab the Threads_lock, since we are operating on ourself.
1812 Handle threadObj(thread, thread->threadObj());
1813 assert(threadObj.not_null(), "java thread object must exist");
1814 ObjectLocker lock(threadObj, thread);
1815 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1816 thread->clear_pending_exception();
1817 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1818 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1819 // Clear the native thread instance - this makes isAlive return false and allows the join()
1820 // to complete once we've done the notify_all below
1821 java_lang_Thread::set_thread(threadObj(), NULL);
1822 lock.notify_all(thread);
1823 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1824 thread->clear_pending_exception();
1825 }
1826
1827
1828 // For any new cleanup additions, please check to see if they need to be applied to
1829 // cleanup_failed_attach_current_thread as well.
1830 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1831 assert(this == JavaThread::current(), "thread consistency check");
1832
1833 elapsedTimer _timer_exit_phase1;
1834 elapsedTimer _timer_exit_phase2;
1835 elapsedTimer _timer_exit_phase3;
1836 elapsedTimer _timer_exit_phase4;
1837
1838 if (log_is_enabled(Debug, os, thread, timer)) {
1839 _timer_exit_phase1.start();
1840 }
1841
1842 HandleMark hm(this);
1843 Handle uncaught_exception(this, this->pending_exception());
1844 this->clear_pending_exception();
1845 Handle threadObj(this, this->threadObj());
1846 assert(threadObj.not_null(), "Java thread object should be created");
1847
1848 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1849 {
1850 EXCEPTION_MARK;
1851
1852 CLEAR_PENDING_EXCEPTION;
1853 }
1854 if (!destroy_vm) {
1855 if (uncaught_exception.not_null()) {
1856 EXCEPTION_MARK;
1857 // Call method Thread.dispatchUncaughtException().
1858 Klass* thread_klass = SystemDictionary::Thread_klass();
1859 JavaValue result(T_VOID);
1860 JavaCalls::call_virtual(&result,
1861 threadObj, thread_klass,
1862 vmSymbols::dispatchUncaughtException_name(),
1863 vmSymbols::throwable_void_signature(),
1864 uncaught_exception,
1865 THREAD);
1866 if (HAS_PENDING_EXCEPTION) {
1867 ResourceMark rm(this);
1868 jio_fprintf(defaultStream::error_stream(),
1869 "\nException: %s thrown from the UncaughtExceptionHandler"
1870 " in thread \"%s\"\n",
1871 pending_exception()->klass()->external_name(),
1872 get_thread_name());
1873 CLEAR_PENDING_EXCEPTION;
1874 }
1875 }
1876
1877 // Called before the java thread exit since we want to read info
1878 // from java_lang_Thread object
1879 EventThreadEnd event;
1880 if (event.should_commit()) {
1881 event.set_thread(THREAD_TRACE_ID(this));
1882 event.commit();
1883 }
1884
1885 // Call after last event on thread
1886 EVENT_THREAD_EXIT(this);
1887
1888 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1889 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1890 // is deprecated anyhow.
1891 if (!is_Compiler_thread()) {
1892 int count = 3;
1893 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1894 EXCEPTION_MARK;
1895 JavaValue result(T_VOID);
1896 Klass* thread_klass = SystemDictionary::Thread_klass();
1897 JavaCalls::call_virtual(&result,
1898 threadObj, thread_klass,
1899 vmSymbols::exit_method_name(),
1900 vmSymbols::void_method_signature(),
1901 THREAD);
1902 CLEAR_PENDING_EXCEPTION;
1903 }
1904 }
1905 // notify JVMTI
1906 if (JvmtiExport::should_post_thread_life()) {
1907 JvmtiExport::post_thread_end(this);
1908 }
1909
1910 // We have notified the agents that we are exiting, before we go on,
1911 // we must check for a pending external suspend request and honor it
1912 // in order to not surprise the thread that made the suspend request.
1913 while (true) {
1914 {
1915 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1916 if (!is_external_suspend()) {
1917 set_terminated(_thread_exiting);
1918 ThreadService::current_thread_exiting(this);
1919 break;
1920 }
1921 // Implied else:
1922 // Things get a little tricky here. We have a pending external
1923 // suspend request, but we are holding the SR_lock so we
1924 // can't just self-suspend. So we temporarily drop the lock
1925 // and then self-suspend.
1926 }
1927
1928 ThreadBlockInVM tbivm(this);
1929 java_suspend_self();
1930
1931 // We're done with this suspend request, but we have to loop around
1932 // and check again. Eventually we will get SR_lock without a pending
1933 // external suspend request and will be able to mark ourselves as
1934 // exiting.
1935 }
1936 // no more external suspends are allowed at this point
1937 } else {
1938 // before_exit() has already posted JVMTI THREAD_END events
1939 }
1940
1941 if (log_is_enabled(Debug, os, thread, timer)) {
1942 _timer_exit_phase1.stop();
1943 _timer_exit_phase2.start();
1944 }
1945 // Notify waiters on thread object. This has to be done after exit() is called
1946 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1947 // group should have the destroyed bit set before waiters are notified).
1948 ensure_join(this);
1949 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1950
1951 if (log_is_enabled(Debug, os, thread, timer)) {
1952 _timer_exit_phase2.stop();
1953 _timer_exit_phase3.start();
1954 }
1955 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1956 // held by this thread must be released. The spec does not distinguish
1957 // between JNI-acquired and regular Java monitors. We can only see
1958 // regular Java monitors here if monitor enter-exit matching is broken.
1959 //
1960 // Optionally release any monitors for regular JavaThread exits. This
1961 // is provided as a work around for any bugs in monitor enter-exit
1962 // matching. This can be expensive so it is not enabled by default.
1963 //
1964 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1965 // ObjectSynchronizer::release_monitors_owned_by_thread().
1966 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1967 // Sanity check even though JNI DetachCurrentThread() would have
1968 // returned JNI_ERR if there was a Java frame. JavaThread exit
1969 // should be done executing Java code by the time we get here.
1970 assert(!this->has_last_Java_frame(),
1971 "should not have a Java frame when detaching or exiting");
1972 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1973 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1974 }
1975
1976 // These things needs to be done while we are still a Java Thread. Make sure that thread
1977 // is in a consistent state, in case GC happens
1978 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1979
1980 if (active_handles() != NULL) {
1981 JNIHandleBlock* block = active_handles();
1982 set_active_handles(NULL);
1983 JNIHandleBlock::release_block(block);
1984 }
1985
1986 if (free_handle_block() != NULL) {
1987 JNIHandleBlock* block = free_handle_block();
1988 set_free_handle_block(NULL);
1989 JNIHandleBlock::release_block(block);
1990 }
1991
1992 // These have to be removed while this is still a valid thread.
1993 remove_stack_guard_pages();
1994
1995 if (UseTLAB) {
1996 tlab().make_parsable(true); // retire TLAB
1997 }
1998
1999 if (JvmtiEnv::environments_might_exist()) {
2000 JvmtiExport::cleanup_thread(this);
2001 }
2002
2003 // We must flush any deferred card marks and other various GC barrier
2004 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2005 // before removing a thread from the list of active threads.
2006 BarrierSet::barrier_set()->on_thread_detach(this);
2007
2008 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2009 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2010 os::current_thread_id());
2011
2012 if (log_is_enabled(Debug, os, thread, timer)) {
2013 _timer_exit_phase3.stop();
2014 _timer_exit_phase4.start();
2015 }
2016 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2017 Threads::remove(this);
2018
2019 if (log_is_enabled(Debug, os, thread, timer)) {
2020 _timer_exit_phase4.stop();
2021 ResourceMark rm(this);
2022 log_debug(os, thread, timer)("name='%s'"
2023 ", exit-phase1=" JLONG_FORMAT
2024 ", exit-phase2=" JLONG_FORMAT
2025 ", exit-phase3=" JLONG_FORMAT
2026 ", exit-phase4=" JLONG_FORMAT,
2027 get_thread_name(),
2028 _timer_exit_phase1.milliseconds(),
2029 _timer_exit_phase2.milliseconds(),
2030 _timer_exit_phase3.milliseconds(),
2031 _timer_exit_phase4.milliseconds());
2032 }
2033 }
2034
2035 void JavaThread::cleanup_failed_attach_current_thread() {
2036 if (active_handles() != NULL) {
2037 JNIHandleBlock* block = active_handles();
2038 set_active_handles(NULL);
2039 JNIHandleBlock::release_block(block);
2040 }
2041
2042 if (free_handle_block() != NULL) {
2043 JNIHandleBlock* block = free_handle_block();
2044 set_free_handle_block(NULL);
2045 JNIHandleBlock::release_block(block);
2046 }
2047
2048 // These have to be removed while this is still a valid thread.
2049 remove_stack_guard_pages();
2050
2051 if (UseTLAB) {
2052 tlab().make_parsable(true); // retire TLAB, if any
2053 }
2054
2055 BarrierSet::barrier_set()->on_thread_detach(this);
2056
2057 Threads::remove(this);
2058 this->smr_delete();
2059 }
2060
2061 JavaThread* JavaThread::active() {
2062 Thread* thread = Thread::current();
2063 if (thread->is_Java_thread()) {
2064 return (JavaThread*) thread;
2065 } else {
2066 assert(thread->is_VM_thread(), "this must be a vm thread");
2067 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2068 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2069 assert(ret->is_Java_thread(), "must be a Java thread");
2070 return ret;
2071 }
2072 }
2073
2074 bool JavaThread::is_lock_owned(address adr) const {
2075 if (Thread::is_lock_owned(adr)) return true;
2076
2077 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2078 if (chunk->contains(adr)) return true;
2079 }
2080
2081 return false;
2082 }
2083
2084
2085 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2086 chunk->set_next(monitor_chunks());
2087 set_monitor_chunks(chunk);
2088 }
2089
2090 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2091 guarantee(monitor_chunks() != NULL, "must be non empty");
2092 if (monitor_chunks() == chunk) {
2093 set_monitor_chunks(chunk->next());
2094 } else {
2095 MonitorChunk* prev = monitor_chunks();
2096 while (prev->next() != chunk) prev = prev->next();
2097 prev->set_next(chunk->next());
2098 }
2099 }
2100
2101 // JVM support.
2102
2103 // Note: this function shouldn't block if it's called in
2104 // _thread_in_native_trans state (such as from
2105 // check_special_condition_for_native_trans()).
2106 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2107
2108 if (has_last_Java_frame() && has_async_condition()) {
2109 // If we are at a polling page safepoint (not a poll return)
2110 // then we must defer async exception because live registers
2111 // will be clobbered by the exception path. Poll return is
2112 // ok because the call we a returning from already collides
2113 // with exception handling registers and so there is no issue.
2114 // (The exception handling path kills call result registers but
2115 // this is ok since the exception kills the result anyway).
2116
2117 if (is_at_poll_safepoint()) {
2118 // if the code we are returning to has deoptimized we must defer
2119 // the exception otherwise live registers get clobbered on the
2120 // exception path before deoptimization is able to retrieve them.
2121 //
2122 RegisterMap map(this, false);
2123 frame caller_fr = last_frame().sender(&map);
2124 assert(caller_fr.is_compiled_frame(), "what?");
2125 if (caller_fr.is_deoptimized_frame()) {
2126 log_info(exceptions)("deferred async exception at compiled safepoint");
2127 return;
2128 }
2129 }
2130 }
2131
2132 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2133 if (condition == _no_async_condition) {
2134 // Conditions have changed since has_special_runtime_exit_condition()
2135 // was called:
2136 // - if we were here only because of an external suspend request,
2137 // then that was taken care of above (or cancelled) so we are done
2138 // - if we were here because of another async request, then it has
2139 // been cleared between the has_special_runtime_exit_condition()
2140 // and now so again we are done
2141 return;
2142 }
2143
2144 // Check for pending async. exception
2145 if (_pending_async_exception != NULL) {
2146 // Only overwrite an already pending exception, if it is not a threadDeath.
2147 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2148
2149 // We cannot call Exceptions::_throw(...) here because we cannot block
2150 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2151
2152 LogTarget(Info, exceptions) lt;
2153 if (lt.is_enabled()) {
2154 ResourceMark rm;
2155 LogStream ls(lt);
2156 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2157 if (has_last_Java_frame()) {
2158 frame f = last_frame();
2159 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2160 }
2161 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2162 }
2163 _pending_async_exception = NULL;
2164 clear_has_async_exception();
2165 }
2166 }
2167
2168 if (check_unsafe_error &&
2169 condition == _async_unsafe_access_error && !has_pending_exception()) {
2170 condition = _no_async_condition; // done
2171 switch (thread_state()) {
2172 case _thread_in_vm: {
2173 JavaThread* THREAD = this;
2174 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2175 }
2176 case _thread_in_native: {
2177 ThreadInVMfromNative tiv(this);
2178 JavaThread* THREAD = this;
2179 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2180 }
2181 case _thread_in_Java: {
2182 ThreadInVMfromJava tiv(this);
2183 JavaThread* THREAD = this;
2184 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2185 }
2186 default:
2187 ShouldNotReachHere();
2188 }
2189 }
2190
2191 assert(condition == _no_async_condition || has_pending_exception() ||
2192 (!check_unsafe_error && condition == _async_unsafe_access_error),
2193 "must have handled the async condition, if no exception");
2194 }
2195
2196 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2197 //
2198 // Check for pending external suspend. Internal suspend requests do
2199 // not use handle_special_runtime_exit_condition().
2200 // If JNIEnv proxies are allowed, don't self-suspend if the target
2201 // thread is not the current thread. In older versions of jdbx, jdbx
2202 // threads could call into the VM with another thread's JNIEnv so we
2203 // can be here operating on behalf of a suspended thread (4432884).
2204 bool do_self_suspend = is_external_suspend_with_lock();
2205 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2206 //
2207 // Because thread is external suspended the safepoint code will count
2208 // thread as at a safepoint. This can be odd because we can be here
2209 // as _thread_in_Java which would normally transition to _thread_blocked
2210 // at a safepoint. We would like to mark the thread as _thread_blocked
2211 // before calling java_suspend_self like all other callers of it but
2212 // we must then observe proper safepoint protocol. (We can't leave
2213 // _thread_blocked with a safepoint in progress). However we can be
2214 // here as _thread_in_native_trans so we can't use a normal transition
2215 // constructor/destructor pair because they assert on that type of
2216 // transition. We could do something like:
2217 //
2218 // JavaThreadState state = thread_state();
2219 // set_thread_state(_thread_in_vm);
2220 // {
2221 // ThreadBlockInVM tbivm(this);
2222 // java_suspend_self()
2223 // }
2224 // set_thread_state(_thread_in_vm_trans);
2225 // if (safepoint) block;
2226 // set_thread_state(state);
2227 //
2228 // but that is pretty messy. Instead we just go with the way the
2229 // code has worked before and note that this is the only path to
2230 // java_suspend_self that doesn't put the thread in _thread_blocked
2231 // mode.
2232
2233 frame_anchor()->make_walkable(this);
2234 java_suspend_self();
2235
2236 // We might be here for reasons in addition to the self-suspend request
2237 // so check for other async requests.
2238 }
2239
2240 if (check_asyncs) {
2241 check_and_handle_async_exceptions();
2242 }
2243 #if INCLUDE_TRACE
2244 if (is_trace_suspend()) {
2245 TRACE_SUSPEND_THREAD(this);
2246 }
2247 #endif
2248 }
2249
2250 void JavaThread::send_thread_stop(oop java_throwable) {
2251 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2252 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2253 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2254
2255 // Do not throw asynchronous exceptions against the compiler thread
2256 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2257 if (!can_call_java()) return;
2258
2259 {
2260 // Actually throw the Throwable against the target Thread - however
2261 // only if there is no thread death exception installed already.
2262 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2263 // If the topmost frame is a runtime stub, then we are calling into
2264 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2265 // must deoptimize the caller before continuing, as the compiled exception handler table
2266 // may not be valid
2267 if (has_last_Java_frame()) {
2268 frame f = last_frame();
2269 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2270 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2271 RegisterMap reg_map(this, UseBiasedLocking);
2272 frame compiled_frame = f.sender(®_map);
2273 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2274 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2275 }
2276 }
2277 }
2278
2279 // Set async. pending exception in thread.
2280 set_pending_async_exception(java_throwable);
2281
2282 if (log_is_enabled(Info, exceptions)) {
2283 ResourceMark rm;
2284 log_info(exceptions)("Pending Async. exception installed of type: %s",
2285 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2286 }
2287 // for AbortVMOnException flag
2288 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2289 }
2290 }
2291
2292
2293 // Interrupt thread so it will wake up from a potential wait()
2294 Thread::interrupt(this);
2295 }
2296
2297 // External suspension mechanism.
2298 //
2299 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2300 // to any VM_locks and it is at a transition
2301 // Self-suspension will happen on the transition out of the vm.
2302 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2303 //
2304 // Guarantees on return:
2305 // + Target thread will not execute any new bytecode (that's why we need to
2306 // force a safepoint)
2307 // + Target thread will not enter any new monitors
2308 //
2309 void JavaThread::java_suspend() {
2310 ThreadsListHandle tlh;
2311 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2312 return;
2313 }
2314
2315 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2316 if (!is_external_suspend()) {
2317 // a racing resume has cancelled us; bail out now
2318 return;
2319 }
2320
2321 // suspend is done
2322 uint32_t debug_bits = 0;
2323 // Warning: is_ext_suspend_completed() may temporarily drop the
2324 // SR_lock to allow the thread to reach a stable thread state if
2325 // it is currently in a transient thread state.
2326 if (is_ext_suspend_completed(false /* !called_by_wait */,
2327 SuspendRetryDelay, &debug_bits)) {
2328 return;
2329 }
2330 }
2331
2332 VM_ThreadSuspend vm_suspend;
2333 VMThread::execute(&vm_suspend);
2334 }
2335
2336 // Part II of external suspension.
2337 // A JavaThread self suspends when it detects a pending external suspend
2338 // request. This is usually on transitions. It is also done in places
2339 // where continuing to the next transition would surprise the caller,
2340 // e.g., monitor entry.
2341 //
2342 // Returns the number of times that the thread self-suspended.
2343 //
2344 // Note: DO NOT call java_suspend_self() when you just want to block current
2345 // thread. java_suspend_self() is the second stage of cooperative
2346 // suspension for external suspend requests and should only be used
2347 // to complete an external suspend request.
2348 //
2349 int JavaThread::java_suspend_self() {
2350 int ret = 0;
2351
2352 // we are in the process of exiting so don't suspend
2353 if (is_exiting()) {
2354 clear_external_suspend();
2355 return ret;
2356 }
2357
2358 assert(_anchor.walkable() ||
2359 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2360 "must have walkable stack");
2361
2362 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2363
2364 assert(!this->is_ext_suspended(),
2365 "a thread trying to self-suspend should not already be suspended");
2366
2367 if (this->is_suspend_equivalent()) {
2368 // If we are self-suspending as a result of the lifting of a
2369 // suspend equivalent condition, then the suspend_equivalent
2370 // flag is not cleared until we set the ext_suspended flag so
2371 // that wait_for_ext_suspend_completion() returns consistent
2372 // results.
2373 this->clear_suspend_equivalent();
2374 }
2375
2376 // A racing resume may have cancelled us before we grabbed SR_lock
2377 // above. Or another external suspend request could be waiting for us
2378 // by the time we return from SR_lock()->wait(). The thread
2379 // that requested the suspension may already be trying to walk our
2380 // stack and if we return now, we can change the stack out from under
2381 // it. This would be a "bad thing (TM)" and cause the stack walker
2382 // to crash. We stay self-suspended until there are no more pending
2383 // external suspend requests.
2384 while (is_external_suspend()) {
2385 ret++;
2386 this->set_ext_suspended();
2387
2388 // _ext_suspended flag is cleared by java_resume()
2389 while (is_ext_suspended()) {
2390 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2391 }
2392 }
2393
2394 return ret;
2395 }
2396
2397 #ifdef ASSERT
2398 // Verify the JavaThread has not yet been published in the Threads::list, and
2399 // hence doesn't need protection from concurrent access at this stage.
2400 void JavaThread::verify_not_published() {
2401 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2402 // since an unpublished JavaThread doesn't participate in the
2403 // Thread-SMR protocol for keeping a ThreadsList alive.
2404 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2405 }
2406 #endif
2407
2408 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2409 // progress or when _suspend_flags is non-zero.
2410 // Current thread needs to self-suspend if there is a suspend request and/or
2411 // block if a safepoint is in progress.
2412 // Async exception ISN'T checked.
2413 // Note only the ThreadInVMfromNative transition can call this function
2414 // directly and when thread state is _thread_in_native_trans
2415 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2416 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2417
2418 JavaThread *curJT = JavaThread::current();
2419 bool do_self_suspend = thread->is_external_suspend();
2420
2421 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2422
2423 // If JNIEnv proxies are allowed, don't self-suspend if the target
2424 // thread is not the current thread. In older versions of jdbx, jdbx
2425 // threads could call into the VM with another thread's JNIEnv so we
2426 // can be here operating on behalf of a suspended thread (4432884).
2427 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2428 JavaThreadState state = thread->thread_state();
2429
2430 // We mark this thread_blocked state as a suspend-equivalent so
2431 // that a caller to is_ext_suspend_completed() won't be confused.
2432 // The suspend-equivalent state is cleared by java_suspend_self().
2433 thread->set_suspend_equivalent();
2434
2435 // If the safepoint code sees the _thread_in_native_trans state, it will
2436 // wait until the thread changes to other thread state. There is no
2437 // guarantee on how soon we can obtain the SR_lock and complete the
2438 // self-suspend request. It would be a bad idea to let safepoint wait for
2439 // too long. Temporarily change the state to _thread_blocked to
2440 // let the VM thread know that this thread is ready for GC. The problem
2441 // of changing thread state is that safepoint could happen just after
2442 // java_suspend_self() returns after being resumed, and VM thread will
2443 // see the _thread_blocked state. We must check for safepoint
2444 // after restoring the state and make sure we won't leave while a safepoint
2445 // is in progress.
2446 thread->set_thread_state(_thread_blocked);
2447 thread->java_suspend_self();
2448 thread->set_thread_state(state);
2449
2450 InterfaceSupport::serialize_thread_state_with_handler(thread);
2451 }
2452
2453 SafepointMechanism::block_if_requested(curJT);
2454
2455 if (thread->is_deopt_suspend()) {
2456 thread->clear_deopt_suspend();
2457 RegisterMap map(thread, false);
2458 frame f = thread->last_frame();
2459 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2460 f = f.sender(&map);
2461 }
2462 if (f.id() == thread->must_deopt_id()) {
2463 thread->clear_must_deopt_id();
2464 f.deoptimize(thread);
2465 } else {
2466 fatal("missed deoptimization!");
2467 }
2468 }
2469 #if INCLUDE_TRACE
2470 if (thread->is_trace_suspend()) {
2471 TRACE_SUSPEND_THREAD(thread);
2472 }
2473 #endif
2474 }
2475
2476 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2477 // progress or when _suspend_flags is non-zero.
2478 // Current thread needs to self-suspend if there is a suspend request and/or
2479 // block if a safepoint is in progress.
2480 // Also check for pending async exception (not including unsafe access error).
2481 // Note only the native==>VM/Java barriers can call this function and when
2482 // thread state is _thread_in_native_trans.
2483 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2484 check_safepoint_and_suspend_for_native_trans(thread);
2485
2486 if (thread->has_async_exception()) {
2487 // We are in _thread_in_native_trans state, don't handle unsafe
2488 // access error since that may block.
2489 thread->check_and_handle_async_exceptions(false);
2490 }
2491 }
2492
2493 // This is a variant of the normal
2494 // check_special_condition_for_native_trans with slightly different
2495 // semantics for use by critical native wrappers. It does all the
2496 // normal checks but also performs the transition back into
2497 // thread_in_Java state. This is required so that critical natives
2498 // can potentially block and perform a GC if they are the last thread
2499 // exiting the GCLocker.
2500 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2501 check_special_condition_for_native_trans(thread);
2502
2503 // Finish the transition
2504 thread->set_thread_state(_thread_in_Java);
2505
2506 if (thread->do_critical_native_unlock()) {
2507 ThreadInVMfromJavaNoAsyncException tiv(thread);
2508 GCLocker::unlock_critical(thread);
2509 thread->clear_critical_native_unlock();
2510 }
2511 }
2512
2513 // We need to guarantee the Threads_lock here, since resumes are not
2514 // allowed during safepoint synchronization
2515 // Can only resume from an external suspension
2516 void JavaThread::java_resume() {
2517 assert_locked_or_safepoint(Threads_lock);
2518
2519 // Sanity check: thread is gone, has started exiting or the thread
2520 // was not externally suspended.
2521 ThreadsListHandle tlh;
2522 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2523 return;
2524 }
2525
2526 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2527
2528 clear_external_suspend();
2529
2530 if (is_ext_suspended()) {
2531 clear_ext_suspended();
2532 SR_lock()->notify_all();
2533 }
2534 }
2535
2536 size_t JavaThread::_stack_red_zone_size = 0;
2537 size_t JavaThread::_stack_yellow_zone_size = 0;
2538 size_t JavaThread::_stack_reserved_zone_size = 0;
2539 size_t JavaThread::_stack_shadow_zone_size = 0;
2540
2541 void JavaThread::create_stack_guard_pages() {
2542 if (!os::uses_stack_guard_pages() ||
2543 _stack_guard_state != stack_guard_unused ||
2544 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2545 log_info(os, thread)("Stack guard page creation for thread "
2546 UINTX_FORMAT " disabled", os::current_thread_id());
2547 return;
2548 }
2549 address low_addr = stack_end();
2550 size_t len = stack_guard_zone_size();
2551
2552 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2553 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2554
2555 int must_commit = os::must_commit_stack_guard_pages();
2556 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2557
2558 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2559 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2560 return;
2561 }
2562
2563 if (os::guard_memory((char *) low_addr, len)) {
2564 _stack_guard_state = stack_guard_enabled;
2565 } else {
2566 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2567 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2568 if (os::uncommit_memory((char *) low_addr, len)) {
2569 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2570 }
2571 return;
2572 }
2573
2574 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2575 PTR_FORMAT "-" PTR_FORMAT ".",
2576 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2577 }
2578
2579 void JavaThread::remove_stack_guard_pages() {
2580 assert(Thread::current() == this, "from different thread");
2581 if (_stack_guard_state == stack_guard_unused) return;
2582 address low_addr = stack_end();
2583 size_t len = stack_guard_zone_size();
2584
2585 if (os::must_commit_stack_guard_pages()) {
2586 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2587 _stack_guard_state = stack_guard_unused;
2588 } else {
2589 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2590 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2591 return;
2592 }
2593 } else {
2594 if (_stack_guard_state == stack_guard_unused) return;
2595 if (os::unguard_memory((char *) low_addr, len)) {
2596 _stack_guard_state = stack_guard_unused;
2597 } else {
2598 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2599 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2600 return;
2601 }
2602 }
2603
2604 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2605 PTR_FORMAT "-" PTR_FORMAT ".",
2606 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2607 }
2608
2609 void JavaThread::enable_stack_reserved_zone() {
2610 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2611 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2612
2613 // The base notation is from the stack's point of view, growing downward.
2614 // We need to adjust it to work correctly with guard_memory()
2615 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2616
2617 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2618 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2619
2620 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2621 _stack_guard_state = stack_guard_enabled;
2622 } else {
2623 warning("Attempt to guard stack reserved zone failed.");
2624 }
2625 enable_register_stack_guard();
2626 }
2627
2628 void JavaThread::disable_stack_reserved_zone() {
2629 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2630 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2631
2632 // Simply return if called for a thread that does not use guard pages.
2633 if (_stack_guard_state == stack_guard_unused) return;
2634
2635 // The base notation is from the stack's point of view, growing downward.
2636 // We need to adjust it to work correctly with guard_memory()
2637 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2638
2639 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2640 _stack_guard_state = stack_guard_reserved_disabled;
2641 } else {
2642 warning("Attempt to unguard stack reserved zone failed.");
2643 }
2644 disable_register_stack_guard();
2645 }
2646
2647 void JavaThread::enable_stack_yellow_reserved_zone() {
2648 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2649 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2650
2651 // The base notation is from the stacks point of view, growing downward.
2652 // We need to adjust it to work correctly with guard_memory()
2653 address base = stack_red_zone_base();
2654
2655 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2656 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2657
2658 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2659 _stack_guard_state = stack_guard_enabled;
2660 } else {
2661 warning("Attempt to guard stack yellow zone failed.");
2662 }
2663 enable_register_stack_guard();
2664 }
2665
2666 void JavaThread::disable_stack_yellow_reserved_zone() {
2667 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2668 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2669
2670 // Simply return if called for a thread that does not use guard pages.
2671 if (_stack_guard_state == stack_guard_unused) return;
2672
2673 // The base notation is from the stacks point of view, growing downward.
2674 // We need to adjust it to work correctly with guard_memory()
2675 address base = stack_red_zone_base();
2676
2677 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2678 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2679 } else {
2680 warning("Attempt to unguard stack yellow zone failed.");
2681 }
2682 disable_register_stack_guard();
2683 }
2684
2685 void JavaThread::enable_stack_red_zone() {
2686 // The base notation is from the stacks point of view, growing downward.
2687 // We need to adjust it to work correctly with guard_memory()
2688 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2689 address base = stack_red_zone_base() - stack_red_zone_size();
2690
2691 guarantee(base < stack_base(), "Error calculating stack red zone");
2692 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2693
2694 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2695 warning("Attempt to guard stack red zone failed.");
2696 }
2697 }
2698
2699 void JavaThread::disable_stack_red_zone() {
2700 // The base notation is from the stacks point of view, growing downward.
2701 // We need to adjust it to work correctly with guard_memory()
2702 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2703 address base = stack_red_zone_base() - stack_red_zone_size();
2704 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2705 warning("Attempt to unguard stack red zone failed.");
2706 }
2707 }
2708
2709 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2710 // ignore is there is no stack
2711 if (!has_last_Java_frame()) return;
2712 // traverse the stack frames. Starts from top frame.
2713 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2714 frame* fr = fst.current();
2715 f(fr, fst.register_map());
2716 }
2717 }
2718
2719
2720 #ifndef PRODUCT
2721 // Deoptimization
2722 // Function for testing deoptimization
2723 void JavaThread::deoptimize() {
2724 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2725 StackFrameStream fst(this, UseBiasedLocking);
2726 bool deopt = false; // Dump stack only if a deopt actually happens.
2727 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2728 // Iterate over all frames in the thread and deoptimize
2729 for (; !fst.is_done(); fst.next()) {
2730 if (fst.current()->can_be_deoptimized()) {
2731
2732 if (only_at) {
2733 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2734 // consists of comma or carriage return separated numbers so
2735 // search for the current bci in that string.
2736 address pc = fst.current()->pc();
2737 nmethod* nm = (nmethod*) fst.current()->cb();
2738 ScopeDesc* sd = nm->scope_desc_at(pc);
2739 char buffer[8];
2740 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2741 size_t len = strlen(buffer);
2742 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2743 while (found != NULL) {
2744 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2745 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2746 // Check that the bci found is bracketed by terminators.
2747 break;
2748 }
2749 found = strstr(found + 1, buffer);
2750 }
2751 if (!found) {
2752 continue;
2753 }
2754 }
2755
2756 if (DebugDeoptimization && !deopt) {
2757 deopt = true; // One-time only print before deopt
2758 tty->print_cr("[BEFORE Deoptimization]");
2759 trace_frames();
2760 trace_stack();
2761 }
2762 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2763 }
2764 }
2765
2766 if (DebugDeoptimization && deopt) {
2767 tty->print_cr("[AFTER Deoptimization]");
2768 trace_frames();
2769 }
2770 }
2771
2772
2773 // Make zombies
2774 void JavaThread::make_zombies() {
2775 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2776 if (fst.current()->can_be_deoptimized()) {
2777 // it is a Java nmethod
2778 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2779 nm->make_not_entrant();
2780 }
2781 }
2782 }
2783 #endif // PRODUCT
2784
2785
2786 void JavaThread::deoptimized_wrt_marked_nmethods() {
2787 if (!has_last_Java_frame()) return;
2788 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2789 StackFrameStream fst(this, UseBiasedLocking);
2790 for (; !fst.is_done(); fst.next()) {
2791 if (fst.current()->should_be_deoptimized()) {
2792 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2793 }
2794 }
2795 }
2796
2797
2798 // If the caller is a NamedThread, then remember, in the current scope,
2799 // the given JavaThread in its _processed_thread field.
2800 class RememberProcessedThread: public StackObj {
2801 NamedThread* _cur_thr;
2802 public:
2803 RememberProcessedThread(JavaThread* jthr) {
2804 Thread* thread = Thread::current();
2805 if (thread->is_Named_thread()) {
2806 _cur_thr = (NamedThread *)thread;
2807 _cur_thr->set_processed_thread(jthr);
2808 } else {
2809 _cur_thr = NULL;
2810 }
2811 }
2812
2813 ~RememberProcessedThread() {
2814 if (_cur_thr) {
2815 _cur_thr->set_processed_thread(NULL);
2816 }
2817 }
2818 };
2819
2820 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2821 // Verify that the deferred card marks have been flushed.
2822 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2823
2824 // Traverse the GCHandles
2825 Thread::oops_do(f, cf);
2826
2827 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2828
2829 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2830 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2831
2832 if (has_last_Java_frame()) {
2833 // Record JavaThread to GC thread
2834 RememberProcessedThread rpt(this);
2835
2836 // Traverse the privileged stack
2837 if (_privileged_stack_top != NULL) {
2838 _privileged_stack_top->oops_do(f);
2839 }
2840
2841 // traverse the registered growable array
2842 if (_array_for_gc != NULL) {
2843 for (int index = 0; index < _array_for_gc->length(); index++) {
2844 f->do_oop(_array_for_gc->adr_at(index));
2845 }
2846 }
2847
2848 // Traverse the monitor chunks
2849 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2850 chunk->oops_do(f);
2851 }
2852
2853 // Traverse the execution stack
2854 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2855 fst.current()->oops_do(f, cf, fst.register_map());
2856 }
2857 }
2858
2859 // callee_target is never live across a gc point so NULL it here should
2860 // it still contain a methdOop.
2861
2862 set_callee_target(NULL);
2863
2864 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2865 // If we have deferred set_locals there might be oops waiting to be
2866 // written
2867 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2868 if (list != NULL) {
2869 for (int i = 0; i < list->length(); i++) {
2870 list->at(i)->oops_do(f);
2871 }
2872 }
2873
2874 // Traverse instance variables at the end since the GC may be moving things
2875 // around using this function
2876 f->do_oop((oop*) &_threadObj);
2877 f->do_oop((oop*) &_vm_result);
2878 f->do_oop((oop*) &_exception_oop);
2879 f->do_oop((oop*) &_pending_async_exception);
2880
2881 if (jvmti_thread_state() != NULL) {
2882 jvmti_thread_state()->oops_do(f);
2883 }
2884 }
2885
2886 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2887 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2888 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2889
2890 if (has_last_Java_frame()) {
2891 // Traverse the execution stack
2892 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2893 fst.current()->nmethods_do(cf);
2894 }
2895 }
2896 }
2897
2898 void JavaThread::metadata_do(void f(Metadata*)) {
2899 if (has_last_Java_frame()) {
2900 // Traverse the execution stack to call f() on the methods in the stack
2901 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2902 fst.current()->metadata_do(f);
2903 }
2904 } else if (is_Compiler_thread()) {
2905 // need to walk ciMetadata in current compile tasks to keep alive.
2906 CompilerThread* ct = (CompilerThread*)this;
2907 if (ct->env() != NULL) {
2908 ct->env()->metadata_do(f);
2909 }
2910 CompileTask* task = ct->task();
2911 if (task != NULL) {
2912 task->metadata_do(f);
2913 }
2914 }
2915 }
2916
2917 // Printing
2918 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2919 switch (_thread_state) {
2920 case _thread_uninitialized: return "_thread_uninitialized";
2921 case _thread_new: return "_thread_new";
2922 case _thread_new_trans: return "_thread_new_trans";
2923 case _thread_in_native: return "_thread_in_native";
2924 case _thread_in_native_trans: return "_thread_in_native_trans";
2925 case _thread_in_vm: return "_thread_in_vm";
2926 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2927 case _thread_in_Java: return "_thread_in_Java";
2928 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2929 case _thread_blocked: return "_thread_blocked";
2930 case _thread_blocked_trans: return "_thread_blocked_trans";
2931 default: return "unknown thread state";
2932 }
2933 }
2934
2935 #ifndef PRODUCT
2936 void JavaThread::print_thread_state_on(outputStream *st) const {
2937 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2938 };
2939 void JavaThread::print_thread_state() const {
2940 print_thread_state_on(tty);
2941 }
2942 #endif // PRODUCT
2943
2944 // Called by Threads::print() for VM_PrintThreads operation
2945 void JavaThread::print_on(outputStream *st) const {
2946 st->print_raw("\"");
2947 st->print_raw(get_thread_name());
2948 st->print_raw("\" ");
2949 oop thread_oop = threadObj();
2950 if (thread_oop != NULL) {
2951 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2952 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2953 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2954 }
2955 Thread::print_on(st);
2956 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2957 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2958 if (thread_oop != NULL) {
2959 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2960 }
2961 #ifndef PRODUCT
2962 print_thread_state_on(st);
2963 _safepoint_state->print_on(st);
2964 #endif // PRODUCT
2965 if (is_Compiler_thread()) {
2966 CompileTask *task = ((CompilerThread*)this)->task();
2967 if (task != NULL) {
2968 st->print(" Compiling: ");
2969 task->print(st, NULL, true, false);
2970 } else {
2971 st->print(" No compile task");
2972 }
2973 st->cr();
2974 }
2975 }
2976
2977 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2978 st->print("%s", get_thread_name_string(buf, buflen));
2979 }
2980
2981 // Called by fatal error handler. The difference between this and
2982 // JavaThread::print() is that we can't grab lock or allocate memory.
2983 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2984 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2985 oop thread_obj = threadObj();
2986 if (thread_obj != NULL) {
2987 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2988 }
2989 st->print(" [");
2990 st->print("%s", _get_thread_state_name(_thread_state));
2991 if (osthread()) {
2992 st->print(", id=%d", osthread()->thread_id());
2993 }
2994 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2995 p2i(stack_end()), p2i(stack_base()));
2996 st->print("]");
2997
2998 if (_threads_hazard_ptr != NULL) {
2999 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
3000 }
3001 if (_nested_threads_hazard_ptr != NULL) {
3002 print_nested_threads_hazard_ptrs_on(st);
3003 }
3004 return;
3005 }
3006
3007 // Verification
3008
3009 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3010
3011 void JavaThread::verify() {
3012 // Verify oops in the thread.
3013 oops_do(&VerifyOopClosure::verify_oop, NULL);
3014
3015 // Verify the stack frames.
3016 frames_do(frame_verify);
3017 }
3018
3019 // CR 6300358 (sub-CR 2137150)
3020 // Most callers of this method assume that it can't return NULL but a
3021 // thread may not have a name whilst it is in the process of attaching to
3022 // the VM - see CR 6412693, and there are places where a JavaThread can be
3023 // seen prior to having it's threadObj set (eg JNI attaching threads and
3024 // if vm exit occurs during initialization). These cases can all be accounted
3025 // for such that this method never returns NULL.
3026 const char* JavaThread::get_thread_name() const {
3027 #ifdef ASSERT
3028 // early safepoints can hit while current thread does not yet have TLS
3029 if (!SafepointSynchronize::is_at_safepoint()) {
3030 Thread *cur = Thread::current();
3031 if (!(cur->is_Java_thread() && cur == this)) {
3032 // Current JavaThreads are allowed to get their own name without
3033 // the Threads_lock.
3034 assert_locked_or_safepoint(Threads_lock);
3035 }
3036 }
3037 #endif // ASSERT
3038 return get_thread_name_string();
3039 }
3040
3041 // Returns a non-NULL representation of this thread's name, or a suitable
3042 // descriptive string if there is no set name
3043 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3044 const char* name_str;
3045 oop thread_obj = threadObj();
3046 if (thread_obj != NULL) {
3047 oop name = java_lang_Thread::name(thread_obj);
3048 if (name != NULL) {
3049 if (buf == NULL) {
3050 name_str = java_lang_String::as_utf8_string(name);
3051 } else {
3052 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3053 }
3054 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3055 name_str = "<no-name - thread is attaching>";
3056 } else {
3057 name_str = Thread::name();
3058 }
3059 } else {
3060 name_str = Thread::name();
3061 }
3062 assert(name_str != NULL, "unexpected NULL thread name");
3063 return name_str;
3064 }
3065
3066
3067 const char* JavaThread::get_threadgroup_name() const {
3068 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3069 oop thread_obj = threadObj();
3070 if (thread_obj != NULL) {
3071 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3072 if (thread_group != NULL) {
3073 // ThreadGroup.name can be null
3074 return java_lang_ThreadGroup::name(thread_group);
3075 }
3076 }
3077 return NULL;
3078 }
3079
3080 const char* JavaThread::get_parent_name() const {
3081 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3082 oop thread_obj = threadObj();
3083 if (thread_obj != NULL) {
3084 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3085 if (thread_group != NULL) {
3086 oop parent = java_lang_ThreadGroup::parent(thread_group);
3087 if (parent != NULL) {
3088 // ThreadGroup.name can be null
3089 return java_lang_ThreadGroup::name(parent);
3090 }
3091 }
3092 }
3093 return NULL;
3094 }
3095
3096 ThreadPriority JavaThread::java_priority() const {
3097 oop thr_oop = threadObj();
3098 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3099 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3100 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3101 return priority;
3102 }
3103
3104 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3105
3106 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3107 // Link Java Thread object <-> C++ Thread
3108
3109 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3110 // and put it into a new Handle. The Handle "thread_oop" can then
3111 // be used to pass the C++ thread object to other methods.
3112
3113 // Set the Java level thread object (jthread) field of the
3114 // new thread (a JavaThread *) to C++ thread object using the
3115 // "thread_oop" handle.
3116
3117 // Set the thread field (a JavaThread *) of the
3118 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3119
3120 Handle thread_oop(Thread::current(),
3121 JNIHandles::resolve_non_null(jni_thread));
3122 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3123 "must be initialized");
3124 set_threadObj(thread_oop());
3125 java_lang_Thread::set_thread(thread_oop(), this);
3126
3127 if (prio == NoPriority) {
3128 prio = java_lang_Thread::priority(thread_oop());
3129 assert(prio != NoPriority, "A valid priority should be present");
3130 }
3131
3132 // Push the Java priority down to the native thread; needs Threads_lock
3133 Thread::set_priority(this, prio);
3134
3135 // Add the new thread to the Threads list and set it in motion.
3136 // We must have threads lock in order to call Threads::add.
3137 // It is crucial that we do not block before the thread is
3138 // added to the Threads list for if a GC happens, then the java_thread oop
3139 // will not be visited by GC.
3140 Threads::add(this);
3141 }
3142
3143 oop JavaThread::current_park_blocker() {
3144 // Support for JSR-166 locks
3145 oop thread_oop = threadObj();
3146 if (thread_oop != NULL &&
3147 JDK_Version::current().supports_thread_park_blocker()) {
3148 return java_lang_Thread::park_blocker(thread_oop);
3149 }
3150 return NULL;
3151 }
3152
3153
3154 void JavaThread::print_stack_on(outputStream* st) {
3155 if (!has_last_Java_frame()) return;
3156 ResourceMark rm;
3157 HandleMark hm;
3158
3159 RegisterMap reg_map(this);
3160 vframe* start_vf = last_java_vframe(®_map);
3161 int count = 0;
3162 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3163 if (f->is_java_frame()) {
3164 javaVFrame* jvf = javaVFrame::cast(f);
3165 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3166
3167 // Print out lock information
3168 if (JavaMonitorsInStackTrace) {
3169 jvf->print_lock_info_on(st, count);
3170 }
3171 } else {
3172 // Ignore non-Java frames
3173 }
3174
3175 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3176 count++;
3177 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3178 }
3179 }
3180
3181
3182 // JVMTI PopFrame support
3183 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3184 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3185 if (in_bytes(size_in_bytes) != 0) {
3186 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3187 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3188 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3189 }
3190 }
3191
3192 void* JavaThread::popframe_preserved_args() {
3193 return _popframe_preserved_args;
3194 }
3195
3196 ByteSize JavaThread::popframe_preserved_args_size() {
3197 return in_ByteSize(_popframe_preserved_args_size);
3198 }
3199
3200 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3201 int sz = in_bytes(popframe_preserved_args_size());
3202 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3203 return in_WordSize(sz / wordSize);
3204 }
3205
3206 void JavaThread::popframe_free_preserved_args() {
3207 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3208 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3209 _popframe_preserved_args = NULL;
3210 _popframe_preserved_args_size = 0;
3211 }
3212
3213 #ifndef PRODUCT
3214
3215 void JavaThread::trace_frames() {
3216 tty->print_cr("[Describe stack]");
3217 int frame_no = 1;
3218 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3219 tty->print(" %d. ", frame_no++);
3220 fst.current()->print_value_on(tty, this);
3221 tty->cr();
3222 }
3223 }
3224
3225 class PrintAndVerifyOopClosure: public OopClosure {
3226 protected:
3227 template <class T> inline void do_oop_work(T* p) {
3228 oop obj = RawAccess<>::oop_load(p);
3229 if (obj == NULL) return;
3230 tty->print(INTPTR_FORMAT ": ", p2i(p));
3231 if (oopDesc::is_oop_or_null(obj)) {
3232 if (obj->is_objArray()) {
3233 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3234 } else {
3235 obj->print();
3236 }
3237 } else {
3238 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3239 }
3240 tty->cr();
3241 }
3242 public:
3243 virtual void do_oop(oop* p) { do_oop_work(p); }
3244 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3245 };
3246
3247
3248 static void oops_print(frame* f, const RegisterMap *map) {
3249 PrintAndVerifyOopClosure print;
3250 f->print_value();
3251 f->oops_do(&print, NULL, (RegisterMap*)map);
3252 }
3253
3254 // Print our all the locations that contain oops and whether they are
3255 // valid or not. This useful when trying to find the oldest frame
3256 // where an oop has gone bad since the frame walk is from youngest to
3257 // oldest.
3258 void JavaThread::trace_oops() {
3259 tty->print_cr("[Trace oops]");
3260 frames_do(oops_print);
3261 }
3262
3263
3264 #ifdef ASSERT
3265 // Print or validate the layout of stack frames
3266 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3267 ResourceMark rm;
3268 PRESERVE_EXCEPTION_MARK;
3269 FrameValues values;
3270 int frame_no = 0;
3271 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3272 fst.current()->describe(values, ++frame_no);
3273 if (depth == frame_no) break;
3274 }
3275 if (validate_only) {
3276 values.validate();
3277 } else {
3278 tty->print_cr("[Describe stack layout]");
3279 values.print(this);
3280 }
3281 }
3282 #endif
3283
3284 void JavaThread::trace_stack_from(vframe* start_vf) {
3285 ResourceMark rm;
3286 int vframe_no = 1;
3287 for (vframe* f = start_vf; f; f = f->sender()) {
3288 if (f->is_java_frame()) {
3289 javaVFrame::cast(f)->print_activation(vframe_no++);
3290 } else {
3291 f->print();
3292 }
3293 if (vframe_no > StackPrintLimit) {
3294 tty->print_cr("...<more frames>...");
3295 return;
3296 }
3297 }
3298 }
3299
3300
3301 void JavaThread::trace_stack() {
3302 if (!has_last_Java_frame()) return;
3303 ResourceMark rm;
3304 HandleMark hm;
3305 RegisterMap reg_map(this);
3306 trace_stack_from(last_java_vframe(®_map));
3307 }
3308
3309
3310 #endif // PRODUCT
3311
3312
3313 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3314 assert(reg_map != NULL, "a map must be given");
3315 frame f = last_frame();
3316 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3317 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3318 }
3319 return NULL;
3320 }
3321
3322
3323 Klass* JavaThread::security_get_caller_class(int depth) {
3324 vframeStream vfst(this);
3325 vfst.security_get_caller_frame(depth);
3326 if (!vfst.at_end()) {
3327 return vfst.method()->method_holder();
3328 }
3329 return NULL;
3330 }
3331
3332 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3333 assert(thread->is_Compiler_thread(), "must be compiler thread");
3334 CompileBroker::compiler_thread_loop();
3335 }
3336
3337 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3338 NMethodSweeper::sweeper_loop();
3339 }
3340
3341 // Create a CompilerThread
3342 CompilerThread::CompilerThread(CompileQueue* queue,
3343 CompilerCounters* counters)
3344 : JavaThread(&compiler_thread_entry) {
3345 _env = NULL;
3346 _log = NULL;
3347 _task = NULL;
3348 _queue = queue;
3349 _counters = counters;
3350 _buffer_blob = NULL;
3351 _compiler = NULL;
3352
3353 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3354 resource_area()->bias_to(mtCompiler);
3355
3356 #ifndef PRODUCT
3357 _ideal_graph_printer = NULL;
3358 #endif
3359 }
3360
3361 CompilerThread::~CompilerThread() {
3362 // Delete objects which were allocated on heap.
3363 delete _counters;
3364 }
3365
3366 bool CompilerThread::can_call_java() const {
3367 return _compiler != NULL && _compiler->is_jvmci();
3368 }
3369
3370 // Create sweeper thread
3371 CodeCacheSweeperThread::CodeCacheSweeperThread()
3372 : JavaThread(&sweeper_thread_entry) {
3373 _scanned_compiled_method = NULL;
3374 }
3375
3376 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3377 JavaThread::oops_do(f, cf);
3378 if (_scanned_compiled_method != NULL && cf != NULL) {
3379 // Safepoints can occur when the sweeper is scanning an nmethod so
3380 // process it here to make sure it isn't unloaded in the middle of
3381 // a scan.
3382 cf->do_code_blob(_scanned_compiled_method);
3383 }
3384 }
3385
3386 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3387 JavaThread::nmethods_do(cf);
3388 if (_scanned_compiled_method != NULL && cf != NULL) {
3389 // Safepoints can occur when the sweeper is scanning an nmethod so
3390 // process it here to make sure it isn't unloaded in the middle of
3391 // a scan.
3392 cf->do_code_blob(_scanned_compiled_method);
3393 }
3394 }
3395
3396
3397 // ======= Threads ========
3398
3399 // The Threads class links together all active threads, and provides
3400 // operations over all threads. It is protected by the Threads_lock,
3401 // which is also used in other global contexts like safepointing.
3402 // ThreadsListHandles are used to safely perform operations on one
3403 // or more threads without the risk of the thread exiting during the
3404 // operation.
3405 //
3406 // Note: The Threads_lock is currently more widely used than we
3407 // would like. We are actively migrating Threads_lock uses to other
3408 // mechanisms in order to reduce Threads_lock contention.
3409
3410 JavaThread* Threads::_thread_list = NULL;
3411 int Threads::_number_of_threads = 0;
3412 int Threads::_number_of_non_daemon_threads = 0;
3413 int Threads::_return_code = 0;
3414 int Threads::_thread_claim_parity = 0;
3415 size_t JavaThread::_stack_size_at_create = 0;
3416
3417 #ifdef ASSERT
3418 bool Threads::_vm_complete = false;
3419 #endif
3420
3421 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3422 Prefetch::read((void*)addr, prefetch_interval);
3423 return *addr;
3424 }
3425
3426 // Possibly the ugliest for loop the world has seen. C++ does not allow
3427 // multiple types in the declaration section of the for loop. In this case
3428 // we are only dealing with pointers and hence can cast them. It looks ugly
3429 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3430 #define DO_JAVA_THREADS(LIST, X) \
3431 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3432 *MACRO_list = (JavaThread*)(LIST), \
3433 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3434 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3435 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3436 MACRO_current_p != MACRO_end; \
3437 MACRO_current_p++, \
3438 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3439
3440 // All JavaThreads
3441 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3442
3443 // All non-JavaThreads (i.e., every non-JavaThread in the system).
3444 void Threads::non_java_threads_do(ThreadClosure* tc) {
3445 // Someday we could have a table or list of all non-JavaThreads.
3446 // For now, just manually iterate through them.
3447 tc->do_thread(VMThread::vm_thread());
3448 if (Universe::heap() != NULL) {
3449 Universe::heap()->gc_threads_do(tc);
3450 }
3451 WatcherThread *wt = WatcherThread::watcher_thread();
3452 // Strictly speaking, the following NULL check isn't sufficient to make sure
3453 // the data for WatcherThread is still valid upon being examined. However,
3454 // considering that WatchThread terminates when the VM is on the way to
3455 // exit at safepoint, the chance of the above is extremely small. The right
3456 // way to prevent termination of WatcherThread would be to acquire
3457 // Terminator_lock, but we can't do that without violating the lock rank
3458 // checking in some cases.
3459 if (wt != NULL) {
3460 tc->do_thread(wt);
3461 }
3462
3463 #if INCLUDE_TRACE
3464 Thread* sampler_thread = TracingExport::sampler_thread_acquire();
3465 if (sampler_thread != NULL) {
3466 tc->do_thread(sampler_thread);
3467 }
3468 #endif
3469
3470 // If CompilerThreads ever become non-JavaThreads, add them here
3471 }
3472
3473 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3474 void Threads::threads_do(ThreadClosure* tc) {
3475 assert_locked_or_safepoint(Threads_lock);
3476 // ALL_JAVA_THREADS iterates through all JavaThreads.
3477 ALL_JAVA_THREADS(p) {
3478 tc->do_thread(p);
3479 }
3480 non_java_threads_do(tc);
3481 }
3482
3483 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3484 int cp = Threads::thread_claim_parity();
3485 ALL_JAVA_THREADS(p) {
3486 if (p->claim_oops_do(is_par, cp)) {
3487 tc->do_thread(p);
3488 }
3489 }
3490 VMThread* vmt = VMThread::vm_thread();
3491 if (vmt->claim_oops_do(is_par, cp)) {
3492 tc->do_thread(vmt);
3493 }
3494 }
3495
3496 // The system initialization in the library has three phases.
3497 //
3498 // Phase 1: java.lang.System class initialization
3499 // java.lang.System is a primordial class loaded and initialized
3500 // by the VM early during startup. java.lang.System.<clinit>
3501 // only does registerNatives and keeps the rest of the class
3502 // initialization work later until thread initialization completes.
3503 //
3504 // System.initPhase1 initializes the system properties, the static
3505 // fields in, out, and err. Set up java signal handlers, OS-specific
3506 // system settings, and thread group of the main thread.
3507 static void call_initPhase1(TRAPS) {
3508 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3509 JavaValue result(T_VOID);
3510 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3511 vmSymbols::void_method_signature(), CHECK);
3512 }
3513
3514 // Phase 2. Module system initialization
3515 // This will initialize the module system. Only java.base classes
3516 // can be loaded until phase 2 completes.
3517 //
3518 // Call System.initPhase2 after the compiler initialization and jsr292
3519 // classes get initialized because module initialization runs a lot of java
3520 // code, that for performance reasons, should be compiled. Also, this will
3521 // enable the startup code to use lambda and other language features in this
3522 // phase and onward.
3523 //
3524 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3525 static void call_initPhase2(TRAPS) {
3526 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3527
3528 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3529
3530 JavaValue result(T_INT);
3531 JavaCallArguments args;
3532 args.push_int(DisplayVMOutputToStderr);
3533 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3534 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3535 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3536 if (result.get_jint() != JNI_OK) {
3537 vm_exit_during_initialization(); // no message or exception
3538 }
3539
3540 universe_post_module_init();
3541 }
3542
3543 // Phase 3. final setup - set security manager, system class loader and TCCL
3544 //
3545 // This will instantiate and set the security manager, set the system class
3546 // loader as well as the thread context class loader. The security manager
3547 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3548 // other modules or the application's classpath.
3549 static void call_initPhase3(TRAPS) {
3550 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3551 JavaValue result(T_VOID);
3552 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3553 vmSymbols::void_method_signature(), CHECK);
3554 }
3555
3556 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3557 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3558
3559 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3560 create_vm_init_libraries();
3561 }
3562
3563 initialize_class(vmSymbols::java_lang_String(), CHECK);
3564
3565 // Inject CompactStrings value after the static initializers for String ran.
3566 java_lang_String::set_compact_strings(CompactStrings);
3567
3568 // Initialize java_lang.System (needed before creating the thread)
3569 initialize_class(vmSymbols::java_lang_System(), CHECK);
3570 // The VM creates & returns objects of this class. Make sure it's initialized.
3571 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3572 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3573 Handle thread_group = create_initial_thread_group(CHECK);
3574 Universe::set_main_thread_group(thread_group());
3575 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3576 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3577 main_thread->set_threadObj(thread_object);
3578 // Set thread status to running since main thread has
3579 // been started and running.
3580 java_lang_Thread::set_thread_status(thread_object,
3581 java_lang_Thread::RUNNABLE);
3582
3583 // The VM creates objects of this class.
3584 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3585
3586 // The VM preresolves methods to these classes. Make sure that they get initialized
3587 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3588 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3589
3590 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3591 call_initPhase1(CHECK);
3592
3593 // get the Java runtime name after java.lang.System is initialized
3594 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3595 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3596
3597 // an instance of OutOfMemory exception has been allocated earlier
3598 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3599 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3600 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3601 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3602 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3603 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3604 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3605 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3606 }
3607
3608 void Threads::initialize_jsr292_core_classes(TRAPS) {
3609 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3610
3611 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3612 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3613 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3614 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3615 }
3616
3617 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3618 extern void JDK_Version_init();
3619
3620 // Preinitialize version info.
3621 VM_Version::early_initialize();
3622
3623 // Check version
3624 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3625
3626 // Initialize library-based TLS
3627 ThreadLocalStorage::init();
3628
3629 // Initialize the output stream module
3630 ostream_init();
3631
3632 // Process java launcher properties.
3633 Arguments::process_sun_java_launcher_properties(args);
3634
3635 // Initialize the os module
3636 os::init();
3637
3638 // Record VM creation timing statistics
3639 TraceVmCreationTime create_vm_timer;
3640 create_vm_timer.start();
3641
3642 // Initialize system properties.
3643 Arguments::init_system_properties();
3644
3645 // So that JDK version can be used as a discriminator when parsing arguments
3646 JDK_Version_init();
3647
3648 // Update/Initialize System properties after JDK version number is known
3649 Arguments::init_version_specific_system_properties();
3650
3651 // Make sure to initialize log configuration *before* parsing arguments
3652 LogConfiguration::initialize(create_vm_timer.begin_time());
3653
3654 // Parse arguments
3655 // Note: this internally calls os::init_container_support()
3656 jint parse_result = Arguments::parse(args);
3657 if (parse_result != JNI_OK) return parse_result;
3658
3659 os::init_before_ergo();
3660
3661 jint ergo_result = Arguments::apply_ergo();
3662 if (ergo_result != JNI_OK) return ergo_result;
3663
3664 // Final check of all ranges after ergonomics which may change values.
3665 if (!JVMFlagRangeList::check_ranges()) {
3666 return JNI_EINVAL;
3667 }
3668
3669 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3670 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3671 if (!constraint_result) {
3672 return JNI_EINVAL;
3673 }
3674
3675 JVMFlagWriteableList::mark_startup();
3676
3677 if (PauseAtStartup) {
3678 os::pause();
3679 }
3680
3681 HOTSPOT_VM_INIT_BEGIN();
3682
3683 // Timing (must come after argument parsing)
3684 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3685
3686 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3687 // Initialize assert poison page mechanism.
3688 if (ShowRegistersOnAssert) {
3689 initialize_assert_poison();
3690 }
3691 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3692
3693 // Initialize the os module after parsing the args
3694 jint os_init_2_result = os::init_2();
3695 if (os_init_2_result != JNI_OK) return os_init_2_result;
3696
3697 SafepointMechanism::initialize();
3698
3699 jint adjust_after_os_result = Arguments::adjust_after_os();
3700 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3701
3702 // Initialize output stream logging
3703 ostream_init_log();
3704
3705 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3706 // Must be before create_vm_init_agents()
3707 if (Arguments::init_libraries_at_startup()) {
3708 convert_vm_init_libraries_to_agents();
3709 }
3710
3711 // Launch -agentlib/-agentpath and converted -Xrun agents
3712 if (Arguments::init_agents_at_startup()) {
3713 create_vm_init_agents();
3714 }
3715
3716 // Initialize Threads state
3717 _thread_list = NULL;
3718 _number_of_threads = 0;
3719 _number_of_non_daemon_threads = 0;
3720
3721 // Initialize global data structures and create system classes in heap
3722 vm_init_globals();
3723
3724 #if INCLUDE_JVMCI
3725 if (JVMCICounterSize > 0) {
3726 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3727 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3728 } else {
3729 JavaThread::_jvmci_old_thread_counters = NULL;
3730 }
3731 #endif // INCLUDE_JVMCI
3732
3733 // Attach the main thread to this os thread
3734 JavaThread* main_thread = new JavaThread();
3735 main_thread->set_thread_state(_thread_in_vm);
3736 main_thread->initialize_thread_current();
3737 // must do this before set_active_handles
3738 main_thread->record_stack_base_and_size();
3739 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3740
3741 if (!main_thread->set_as_starting_thread()) {
3742 vm_shutdown_during_initialization(
3743 "Failed necessary internal allocation. Out of swap space");
3744 main_thread->smr_delete();
3745 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3746 return JNI_ENOMEM;
3747 }
3748
3749 // Enable guard page *after* os::create_main_thread(), otherwise it would
3750 // crash Linux VM, see notes in os_linux.cpp.
3751 main_thread->create_stack_guard_pages();
3752
3753 // Initialize Java-Level synchronization subsystem
3754 ObjectMonitor::Initialize();
3755
3756 // Initialize global modules
3757 jint status = init_globals();
3758 if (status != JNI_OK) {
3759 main_thread->smr_delete();
3760 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3761 return status;
3762 }
3763
3764 if (TRACE_INITIALIZE() != JNI_OK) {
3765 vm_exit_during_initialization("Failed to initialize tracing backend");
3766 }
3767
3768 // Should be done after the heap is fully created
3769 main_thread->cache_global_variables();
3770
3771 HandleMark hm;
3772
3773 { MutexLocker mu(Threads_lock);
3774 Threads::add(main_thread);
3775 }
3776
3777 // Any JVMTI raw monitors entered in onload will transition into
3778 // real raw monitor. VM is setup enough here for raw monitor enter.
3779 JvmtiExport::transition_pending_onload_raw_monitors();
3780
3781 // Create the VMThread
3782 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3783
3784 VMThread::create();
3785 Thread* vmthread = VMThread::vm_thread();
3786
3787 if (!os::create_thread(vmthread, os::vm_thread)) {
3788 vm_exit_during_initialization("Cannot create VM thread. "
3789 "Out of system resources.");
3790 }
3791
3792 // Wait for the VM thread to become ready, and VMThread::run to initialize
3793 // Monitors can have spurious returns, must always check another state flag
3794 {
3795 MutexLocker ml(Notify_lock);
3796 os::start_thread(vmthread);
3797 while (vmthread->active_handles() == NULL) {
3798 Notify_lock->wait();
3799 }
3800 }
3801 }
3802
3803 assert(Universe::is_fully_initialized(), "not initialized");
3804 if (VerifyDuringStartup) {
3805 // Make sure we're starting with a clean slate.
3806 VM_Verify verify_op;
3807 VMThread::execute(&verify_op);
3808 }
3809
3810 Thread* THREAD = Thread::current();
3811
3812 // Always call even when there are not JVMTI environments yet, since environments
3813 // may be attached late and JVMTI must track phases of VM execution
3814 JvmtiExport::enter_early_start_phase();
3815
3816 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3817 JvmtiExport::post_early_vm_start();
3818
3819 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3820
3821 // We need this for ClassDataSharing - the initial vm.info property is set
3822 // with the default value of CDS "sharing" which may be reset through
3823 // command line options.
3824 reset_vm_info_property(CHECK_JNI_ERR);
3825
3826 quicken_jni_functions();
3827
3828 // No more stub generation allowed after that point.
3829 StubCodeDesc::freeze();
3830
3831 // Set flag that basic initialization has completed. Used by exceptions and various
3832 // debug stuff, that does not work until all basic classes have been initialized.
3833 set_init_completed();
3834
3835 LogConfiguration::post_initialize();
3836 Metaspace::post_initialize();
3837
3838 HOTSPOT_VM_INIT_END();
3839
3840 // record VM initialization completion time
3841 #if INCLUDE_MANAGEMENT
3842 Management::record_vm_init_completed();
3843 #endif // INCLUDE_MANAGEMENT
3844
3845 // Signal Dispatcher needs to be started before VMInit event is posted
3846 os::signal_init(CHECK_JNI_ERR);
3847
3848 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3849 if (!DisableAttachMechanism) {
3850 AttachListener::vm_start();
3851 if (StartAttachListener || AttachListener::init_at_startup()) {
3852 AttachListener::init();
3853 }
3854 }
3855
3856 // Launch -Xrun agents
3857 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3858 // back-end can launch with -Xdebug -Xrunjdwp.
3859 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3860 create_vm_init_libraries();
3861 }
3862
3863 if (CleanChunkPoolAsync) {
3864 Chunk::start_chunk_pool_cleaner_task();
3865 }
3866
3867 // initialize compiler(s)
3868 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3869 #if INCLUDE_JVMCI
3870 bool force_JVMCI_intialization = false;
3871 if (EnableJVMCI) {
3872 // Initialize JVMCI eagerly when it is explicitly requested.
3873 // Or when JVMCIPrintProperties is enabled.
3874 // The JVMCI Java initialization code will read this flag and
3875 // do the printing if it's set.
3876 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3877
3878 if (!force_JVMCI_intialization) {
3879 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3880 // compilations via JVMCI will not actually block until JVMCI is initialized.
3881 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3882 }
3883 }
3884 #endif
3885 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3886 // Postpone completion of compiler initialization to after JVMCI
3887 // is initialized to avoid timeouts of blocking compilations.
3888 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3889 CompileBroker::compilation_init_phase2();
3890 }
3891 #endif
3892
3893 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3894 // It is done after compilers are initialized, because otherwise compilations of
3895 // signature polymorphic MH intrinsics can be missed
3896 // (see SystemDictionary::find_method_handle_intrinsic).
3897 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3898
3899 // This will initialize the module system. Only java.base classes can be
3900 // loaded until phase 2 completes
3901 call_initPhase2(CHECK_JNI_ERR);
3902
3903 // Always call even when there are not JVMTI environments yet, since environments
3904 // may be attached late and JVMTI must track phases of VM execution
3905 JvmtiExport::enter_start_phase();
3906
3907 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3908 JvmtiExport::post_vm_start();
3909
3910 // Final system initialization including security manager and system class loader
3911 call_initPhase3(CHECK_JNI_ERR);
3912
3913 // cache the system and platform class loaders
3914 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3915
3916 #if INCLUDE_CDS
3917 if (DumpSharedSpaces) {
3918 // capture the module path info from the ModuleEntryTable
3919 ClassLoader::initialize_module_path(THREAD);
3920 }
3921 #endif
3922
3923 #if INCLUDE_JVMCI
3924 if (force_JVMCI_intialization) {
3925 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3926 CompileBroker::compilation_init_phase2();
3927 }
3928 #endif
3929
3930 // Always call even when there are not JVMTI environments yet, since environments
3931 // may be attached late and JVMTI must track phases of VM execution
3932 JvmtiExport::enter_live_phase();
3933
3934 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3935 JvmtiExport::post_vm_initialized();
3936
3937 if (TRACE_START() != JNI_OK) {
3938 vm_exit_during_initialization("Failed to start tracing backend.");
3939 }
3940
3941 #if INCLUDE_MANAGEMENT
3942 Management::initialize(THREAD);
3943
3944 if (HAS_PENDING_EXCEPTION) {
3945 // management agent fails to start possibly due to
3946 // configuration problem and is responsible for printing
3947 // stack trace if appropriate. Simply exit VM.
3948 vm_exit(1);
3949 }
3950 #endif // INCLUDE_MANAGEMENT
3951
3952 if (MemProfiling) MemProfiler::engage();
3953 StatSampler::engage();
3954 if (CheckJNICalls) JniPeriodicChecker::engage();
3955
3956 BiasedLocking::init();
3957
3958 #if INCLUDE_RTM_OPT
3959 RTMLockingCounters::init();
3960 #endif
3961
3962 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3963 call_postVMInitHook(THREAD);
3964 // The Java side of PostVMInitHook.run must deal with all
3965 // exceptions and provide means of diagnosis.
3966 if (HAS_PENDING_EXCEPTION) {
3967 CLEAR_PENDING_EXCEPTION;
3968 }
3969 }
3970
3971 {
3972 MutexLocker ml(PeriodicTask_lock);
3973 // Make sure the WatcherThread can be started by WatcherThread::start()
3974 // or by dynamic enrollment.
3975 WatcherThread::make_startable();
3976 // Start up the WatcherThread if there are any periodic tasks
3977 // NOTE: All PeriodicTasks should be registered by now. If they
3978 // aren't, late joiners might appear to start slowly (we might
3979 // take a while to process their first tick).
3980 if (PeriodicTask::num_tasks() > 0) {
3981 WatcherThread::start();
3982 }
3983 }
3984
3985 create_vm_timer.end();
3986 #ifdef ASSERT
3987 _vm_complete = true;
3988 #endif
3989
3990 if (DumpSharedSpaces) {
3991 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3992 ShouldNotReachHere();
3993 }
3994
3995 return JNI_OK;
3996 }
3997
3998 // type for the Agent_OnLoad and JVM_OnLoad entry points
3999 extern "C" {
4000 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4001 }
4002 // Find a command line agent library and return its entry point for
4003 // -agentlib: -agentpath: -Xrun
4004 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4005 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4006 const char *on_load_symbols[],
4007 size_t num_symbol_entries) {
4008 OnLoadEntry_t on_load_entry = NULL;
4009 void *library = NULL;
4010
4011 if (!agent->valid()) {
4012 char buffer[JVM_MAXPATHLEN];
4013 char ebuf[1024] = "";
4014 const char *name = agent->name();
4015 const char *msg = "Could not find agent library ";
4016
4017 // First check to see if agent is statically linked into executable
4018 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4019 library = agent->os_lib();
4020 } else if (agent->is_absolute_path()) {
4021 library = os::dll_load(name, ebuf, sizeof ebuf);
4022 if (library == NULL) {
4023 const char *sub_msg = " in absolute path, with error: ";
4024 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4025 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4026 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4027 // If we can't find the agent, exit.
4028 vm_exit_during_initialization(buf, NULL);
4029 FREE_C_HEAP_ARRAY(char, buf);
4030 }
4031 } else {
4032 // Try to load the agent from the standard dll directory
4033 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4034 name)) {
4035 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4036 }
4037 if (library == NULL) { // Try the library path directory.
4038 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4039 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4040 }
4041 if (library == NULL) {
4042 const char *sub_msg = " on the library path, with error: ";
4043 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4044
4045 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4046 strlen(ebuf) + strlen(sub_msg2) + 1;
4047 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4048 if (!agent->is_instrument_lib()) {
4049 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4050 } else {
4051 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4052 }
4053 // If we can't find the agent, exit.
4054 vm_exit_during_initialization(buf, NULL);
4055 FREE_C_HEAP_ARRAY(char, buf);
4056 }
4057 }
4058 }
4059 agent->set_os_lib(library);
4060 agent->set_valid();
4061 }
4062
4063 // Find the OnLoad function.
4064 on_load_entry =
4065 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4066 false,
4067 on_load_symbols,
4068 num_symbol_entries));
4069 return on_load_entry;
4070 }
4071
4072 // Find the JVM_OnLoad entry point
4073 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4074 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4075 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4076 }
4077
4078 // Find the Agent_OnLoad entry point
4079 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4080 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4081 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4082 }
4083
4084 // For backwards compatibility with -Xrun
4085 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4086 // treated like -agentpath:
4087 // Must be called before agent libraries are created
4088 void Threads::convert_vm_init_libraries_to_agents() {
4089 AgentLibrary* agent;
4090 AgentLibrary* next;
4091
4092 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4093 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4094 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4095
4096 // If there is an JVM_OnLoad function it will get called later,
4097 // otherwise see if there is an Agent_OnLoad
4098 if (on_load_entry == NULL) {
4099 on_load_entry = lookup_agent_on_load(agent);
4100 if (on_load_entry != NULL) {
4101 // switch it to the agent list -- so that Agent_OnLoad will be called,
4102 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4103 Arguments::convert_library_to_agent(agent);
4104 } else {
4105 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4106 }
4107 }
4108 }
4109 }
4110
4111 // Create agents for -agentlib: -agentpath: and converted -Xrun
4112 // Invokes Agent_OnLoad
4113 // Called very early -- before JavaThreads exist
4114 void Threads::create_vm_init_agents() {
4115 extern struct JavaVM_ main_vm;
4116 AgentLibrary* agent;
4117
4118 JvmtiExport::enter_onload_phase();
4119
4120 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4121 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4122
4123 if (on_load_entry != NULL) {
4124 // Invoke the Agent_OnLoad function
4125 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4126 if (err != JNI_OK) {
4127 vm_exit_during_initialization("agent library failed to init", agent->name());
4128 }
4129 } else {
4130 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4131 }
4132 }
4133 JvmtiExport::enter_primordial_phase();
4134 }
4135
4136 extern "C" {
4137 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4138 }
4139
4140 void Threads::shutdown_vm_agents() {
4141 // Send any Agent_OnUnload notifications
4142 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4143 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4144 extern struct JavaVM_ main_vm;
4145 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4146
4147 // Find the Agent_OnUnload function.
4148 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4149 os::find_agent_function(agent,
4150 false,
4151 on_unload_symbols,
4152 num_symbol_entries));
4153
4154 // Invoke the Agent_OnUnload function
4155 if (unload_entry != NULL) {
4156 JavaThread* thread = JavaThread::current();
4157 ThreadToNativeFromVM ttn(thread);
4158 HandleMark hm(thread);
4159 (*unload_entry)(&main_vm);
4160 }
4161 }
4162 }
4163
4164 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4165 // Invokes JVM_OnLoad
4166 void Threads::create_vm_init_libraries() {
4167 extern struct JavaVM_ main_vm;
4168 AgentLibrary* agent;
4169
4170 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4171 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4172
4173 if (on_load_entry != NULL) {
4174 // Invoke the JVM_OnLoad function
4175 JavaThread* thread = JavaThread::current();
4176 ThreadToNativeFromVM ttn(thread);
4177 HandleMark hm(thread);
4178 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4179 if (err != JNI_OK) {
4180 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4181 }
4182 } else {
4183 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4184 }
4185 }
4186 }
4187
4188
4189 // Last thread running calls java.lang.Shutdown.shutdown()
4190 void JavaThread::invoke_shutdown_hooks() {
4191 HandleMark hm(this);
4192
4193 // We could get here with a pending exception, if so clear it now.
4194 if (this->has_pending_exception()) {
4195 this->clear_pending_exception();
4196 }
4197
4198 EXCEPTION_MARK;
4199 Klass* shutdown_klass =
4200 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4201 THREAD);
4202 if (shutdown_klass != NULL) {
4203 // SystemDictionary::resolve_or_null will return null if there was
4204 // an exception. If we cannot load the Shutdown class, just don't
4205 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4206 // won't be run. Note that if a shutdown hook was registered,
4207 // the Shutdown class would have already been loaded
4208 // (Runtime.addShutdownHook will load it).
4209 JavaValue result(T_VOID);
4210 JavaCalls::call_static(&result,
4211 shutdown_klass,
4212 vmSymbols::shutdown_method_name(),
4213 vmSymbols::void_method_signature(),
4214 THREAD);
4215 }
4216 CLEAR_PENDING_EXCEPTION;
4217 }
4218
4219 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4220 // the program falls off the end of main(). Another VM exit path is through
4221 // vm_exit() when the program calls System.exit() to return a value or when
4222 // there is a serious error in VM. The two shutdown paths are not exactly
4223 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4224 // and VM_Exit op at VM level.
4225 //
4226 // Shutdown sequence:
4227 // + Shutdown native memory tracking if it is on
4228 // + Wait until we are the last non-daemon thread to execute
4229 // <-- every thing is still working at this moment -->
4230 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4231 // shutdown hooks
4232 // + Call before_exit(), prepare for VM exit
4233 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4234 // currently the only user of this mechanism is File.deleteOnExit())
4235 // > stop StatSampler, watcher thread, CMS threads,
4236 // post thread end and vm death events to JVMTI,
4237 // stop signal thread
4238 // + Call JavaThread::exit(), it will:
4239 // > release JNI handle blocks, remove stack guard pages
4240 // > remove this thread from Threads list
4241 // <-- no more Java code from this thread after this point -->
4242 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4243 // the compiler threads at safepoint
4244 // <-- do not use anything that could get blocked by Safepoint -->
4245 // + Disable tracing at JNI/JVM barriers
4246 // + Set _vm_exited flag for threads that are still running native code
4247 // + Delete this thread
4248 // + Call exit_globals()
4249 // > deletes tty
4250 // > deletes PerfMemory resources
4251 // + Return to caller
4252
4253 bool Threads::destroy_vm() {
4254 JavaThread* thread = JavaThread::current();
4255
4256 #ifdef ASSERT
4257 _vm_complete = false;
4258 #endif
4259 // Wait until we are the last non-daemon thread to execute
4260 { MutexLocker nu(Threads_lock);
4261 while (Threads::number_of_non_daemon_threads() > 1)
4262 // This wait should make safepoint checks, wait without a timeout,
4263 // and wait as a suspend-equivalent condition.
4264 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4265 Mutex::_as_suspend_equivalent_flag);
4266 }
4267
4268 EventShutdown e;
4269 if (e.should_commit()) {
4270 e.set_reason("No remaining non-daemon Java threads");
4271 e.commit();
4272 }
4273
4274 // Hang forever on exit if we are reporting an error.
4275 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4276 os::infinite_sleep();
4277 }
4278 os::wait_for_keypress_at_exit();
4279
4280 // run Java level shutdown hooks
4281 thread->invoke_shutdown_hooks();
4282
4283 before_exit(thread);
4284
4285 thread->exit(true);
4286
4287 // Stop VM thread.
4288 {
4289 // 4945125 The vm thread comes to a safepoint during exit.
4290 // GC vm_operations can get caught at the safepoint, and the
4291 // heap is unparseable if they are caught. Grab the Heap_lock
4292 // to prevent this. The GC vm_operations will not be able to
4293 // queue until after the vm thread is dead. After this point,
4294 // we'll never emerge out of the safepoint before the VM exits.
4295
4296 MutexLocker ml(Heap_lock);
4297
4298 VMThread::wait_for_vm_thread_exit();
4299 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4300 VMThread::destroy();
4301 }
4302
4303 // Now, all Java threads are gone except daemon threads. Daemon threads
4304 // running Java code or in VM are stopped by the Safepoint. However,
4305 // daemon threads executing native code are still running. But they
4306 // will be stopped at native=>Java/VM barriers. Note that we can't
4307 // simply kill or suspend them, as it is inherently deadlock-prone.
4308
4309 VM_Exit::set_vm_exited();
4310
4311 // Clean up ideal graph printers after the VMThread has started
4312 // the final safepoint which will block all the Compiler threads.
4313 // Note that this Thread has already logically exited so the
4314 // clean_up() function's use of a JavaThreadIteratorWithHandle
4315 // would be a problem except set_vm_exited() has remembered the
4316 // shutdown thread which is granted a policy exception.
4317 #if defined(COMPILER2) && !defined(PRODUCT)
4318 IdealGraphPrinter::clean_up();
4319 #endif
4320
4321 notify_vm_shutdown();
4322
4323 // We are after VM_Exit::set_vm_exited() so we can't call
4324 // thread->smr_delete() or we will block on the Threads_lock.
4325 // Deleting the shutdown thread here is safe because another
4326 // JavaThread cannot have an active ThreadsListHandle for
4327 // this JavaThread.
4328 delete thread;
4329
4330 #if INCLUDE_JVMCI
4331 if (JVMCICounterSize > 0) {
4332 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4333 }
4334 #endif
4335
4336 // exit_globals() will delete tty
4337 exit_globals();
4338
4339 LogConfiguration::finalize();
4340
4341 return true;
4342 }
4343
4344
4345 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4346 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4347 return is_supported_jni_version(version);
4348 }
4349
4350
4351 jboolean Threads::is_supported_jni_version(jint version) {
4352 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4353 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4354 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4355 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4356 if (version == JNI_VERSION_9) return JNI_TRUE;
4357 if (version == JNI_VERSION_10) return JNI_TRUE;
4358 return JNI_FALSE;
4359 }
4360
4361
4362 void Threads::add(JavaThread* p, bool force_daemon) {
4363 // The threads lock must be owned at this point
4364 assert_locked_or_safepoint(Threads_lock);
4365
4366 BarrierSet::barrier_set()->on_thread_attach(p);
4367
4368 p->set_next(_thread_list);
4369 _thread_list = p;
4370
4371 // Once a JavaThread is added to the Threads list, smr_delete() has
4372 // to be used to delete it. Otherwise we can just delete it directly.
4373 p->set_on_thread_list();
4374
4375 _number_of_threads++;
4376 oop threadObj = p->threadObj();
4377 bool daemon = true;
4378 // Bootstrapping problem: threadObj can be null for initial
4379 // JavaThread (or for threads attached via JNI)
4380 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4381 _number_of_non_daemon_threads++;
4382 daemon = false;
4383 }
4384
4385 ThreadService::add_thread(p, daemon);
4386
4387 // Maintain fast thread list
4388 ThreadsSMRSupport::add_thread(p);
4389
4390 // Possible GC point.
4391 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4392 }
4393
4394 void Threads::remove(JavaThread* p) {
4395
4396 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4397 ObjectSynchronizer::omFlush(p);
4398
4399 // Extra scope needed for Thread_lock, so we can check
4400 // that we do not remove thread without safepoint code notice
4401 { MutexLocker ml(Threads_lock);
4402
4403 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4404
4405 // Maintain fast thread list
4406 ThreadsSMRSupport::remove_thread(p);
4407
4408 JavaThread* current = _thread_list;
4409 JavaThread* prev = NULL;
4410
4411 while (current != p) {
4412 prev = current;
4413 current = current->next();
4414 }
4415
4416 if (prev) {
4417 prev->set_next(current->next());
4418 } else {
4419 _thread_list = p->next();
4420 }
4421
4422 _number_of_threads--;
4423 oop threadObj = p->threadObj();
4424 bool daemon = true;
4425 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4426 _number_of_non_daemon_threads--;
4427 daemon = false;
4428
4429 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4430 // on destroy_vm will wake up.
4431 if (number_of_non_daemon_threads() == 1) {
4432 Threads_lock->notify_all();
4433 }
4434 }
4435 ThreadService::remove_thread(p, daemon);
4436
4437 // Make sure that safepoint code disregard this thread. This is needed since
4438 // the thread might mess around with locks after this point. This can cause it
4439 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4440 // of this thread since it is removed from the queue.
4441 p->set_terminated_value();
4442 } // unlock Threads_lock
4443
4444 // Since Events::log uses a lock, we grab it outside the Threads_lock
4445 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4446 }
4447
4448 // Operations on the Threads list for GC. These are not explicitly locked,
4449 // but the garbage collector must provide a safe context for them to run.
4450 // In particular, these things should never be called when the Threads_lock
4451 // is held by some other thread. (Note: the Safepoint abstraction also
4452 // uses the Threads_lock to guarantee this property. It also makes sure that
4453 // all threads gets blocked when exiting or starting).
4454
4455 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4456 ALL_JAVA_THREADS(p) {
4457 p->oops_do(f, cf);
4458 }
4459 VMThread::vm_thread()->oops_do(f, cf);
4460 }
4461
4462 void Threads::change_thread_claim_parity() {
4463 // Set the new claim parity.
4464 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4465 "Not in range.");
4466 _thread_claim_parity++;
4467 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4468 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4469 "Not in range.");
4470 }
4471
4472 #ifdef ASSERT
4473 void Threads::assert_all_threads_claimed() {
4474 ALL_JAVA_THREADS(p) {
4475 const int thread_parity = p->oops_do_parity();
4476 assert((thread_parity == _thread_claim_parity),
4477 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4478 }
4479 VMThread* vmt = VMThread::vm_thread();
4480 const int thread_parity = vmt->oops_do_parity();
4481 assert((thread_parity == _thread_claim_parity),
4482 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4483 }
4484 #endif // ASSERT
4485
4486 class ParallelOopsDoThreadClosure : public ThreadClosure {
4487 private:
4488 OopClosure* _f;
4489 CodeBlobClosure* _cf;
4490 public:
4491 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4492 void do_thread(Thread* t) {
4493 t->oops_do(_f, _cf);
4494 }
4495 };
4496
4497 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4498 ParallelOopsDoThreadClosure tc(f, cf);
4499 possibly_parallel_threads_do(is_par, &tc);
4500 }
4501
4502 #if INCLUDE_ALL_GCS
4503 // Used by ParallelScavenge
4504 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4505 ALL_JAVA_THREADS(p) {
4506 q->enqueue(new ThreadRootsTask(p));
4507 }
4508 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4509 }
4510
4511 // Used by Parallel Old
4512 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4513 ALL_JAVA_THREADS(p) {
4514 q->enqueue(new ThreadRootsMarkingTask(p));
4515 }
4516 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4517 }
4518 #endif // INCLUDE_ALL_GCS
4519
4520 void Threads::nmethods_do(CodeBlobClosure* cf) {
4521 ALL_JAVA_THREADS(p) {
4522 // This is used by the code cache sweeper to mark nmethods that are active
4523 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4524 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4525 if(!p->is_Code_cache_sweeper_thread()) {
4526 p->nmethods_do(cf);
4527 }
4528 }
4529 }
4530
4531 void Threads::metadata_do(void f(Metadata*)) {
4532 ALL_JAVA_THREADS(p) {
4533 p->metadata_do(f);
4534 }
4535 }
4536
4537 class ThreadHandlesClosure : public ThreadClosure {
4538 void (*_f)(Metadata*);
4539 public:
4540 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4541 virtual void do_thread(Thread* thread) {
4542 thread->metadata_handles_do(_f);
4543 }
4544 };
4545
4546 void Threads::metadata_handles_do(void f(Metadata*)) {
4547 // Only walk the Handles in Thread.
4548 ThreadHandlesClosure handles_closure(f);
4549 threads_do(&handles_closure);
4550 }
4551
4552 void Threads::deoptimized_wrt_marked_nmethods() {
4553 ALL_JAVA_THREADS(p) {
4554 p->deoptimized_wrt_marked_nmethods();
4555 }
4556 }
4557
4558
4559 // Get count Java threads that are waiting to enter the specified monitor.
4560 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4561 int count,
4562 address monitor) {
4563 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4564
4565 int i = 0;
4566 DO_JAVA_THREADS(t_list, p) {
4567 if (!p->can_call_java()) continue;
4568
4569 address pending = (address)p->current_pending_monitor();
4570 if (pending == monitor) { // found a match
4571 if (i < count) result->append(p); // save the first count matches
4572 i++;
4573 }
4574 }
4575
4576 return result;
4577 }
4578
4579
4580 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4581 address owner) {
4582 // NULL owner means not locked so we can skip the search
4583 if (owner == NULL) return NULL;
4584
4585 DO_JAVA_THREADS(t_list, p) {
4586 // first, see if owner is the address of a Java thread
4587 if (owner == (address)p) return p;
4588 }
4589
4590 // Cannot assert on lack of success here since this function may be
4591 // used by code that is trying to report useful problem information
4592 // like deadlock detection.
4593 if (UseHeavyMonitors) return NULL;
4594
4595 // If we didn't find a matching Java thread and we didn't force use of
4596 // heavyweight monitors, then the owner is the stack address of the
4597 // Lock Word in the owning Java thread's stack.
4598 //
4599 JavaThread* the_owner = NULL;
4600 DO_JAVA_THREADS(t_list, q) {
4601 if (q->is_lock_owned(owner)) {
4602 the_owner = q;
4603 break;
4604 }
4605 }
4606
4607 // cannot assert on lack of success here; see above comment
4608 return the_owner;
4609 }
4610
4611 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4612 void Threads::print_on(outputStream* st, bool print_stacks,
4613 bool internal_format, bool print_concurrent_locks) {
4614 char buf[32];
4615 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4616
4617 st->print_cr("Full thread dump %s (%s %s):",
4618 Abstract_VM_Version::vm_name(),
4619 Abstract_VM_Version::vm_release(),
4620 Abstract_VM_Version::vm_info_string());
4621 st->cr();
4622
4623 #if INCLUDE_SERVICES
4624 // Dump concurrent locks
4625 ConcurrentLocksDump concurrent_locks;
4626 if (print_concurrent_locks) {
4627 concurrent_locks.dump_at_safepoint();
4628 }
4629 #endif // INCLUDE_SERVICES
4630
4631 ThreadsSMRSupport::print_info_on(st);
4632 st->cr();
4633
4634 ALL_JAVA_THREADS(p) {
4635 ResourceMark rm;
4636 p->print_on(st);
4637 if (print_stacks) {
4638 if (internal_format) {
4639 p->trace_stack();
4640 } else {
4641 p->print_stack_on(st);
4642 }
4643 }
4644 st->cr();
4645 #if INCLUDE_SERVICES
4646 if (print_concurrent_locks) {
4647 concurrent_locks.print_locks_on(p, st);
4648 }
4649 #endif // INCLUDE_SERVICES
4650 }
4651
4652 VMThread::vm_thread()->print_on(st);
4653 st->cr();
4654 Universe::heap()->print_gc_threads_on(st);
4655 WatcherThread* wt = WatcherThread::watcher_thread();
4656 if (wt != NULL) {
4657 wt->print_on(st);
4658 st->cr();
4659 }
4660
4661 st->flush();
4662 }
4663
4664 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4665 int buflen, bool* found_current) {
4666 if (this_thread != NULL) {
4667 bool is_current = (current == this_thread);
4668 *found_current = *found_current || is_current;
4669 st->print("%s", is_current ? "=>" : " ");
4670
4671 st->print(PTR_FORMAT, p2i(this_thread));
4672 st->print(" ");
4673 this_thread->print_on_error(st, buf, buflen);
4674 st->cr();
4675 }
4676 }
4677
4678 class PrintOnErrorClosure : public ThreadClosure {
4679 outputStream* _st;
4680 Thread* _current;
4681 char* _buf;
4682 int _buflen;
4683 bool* _found_current;
4684 public:
4685 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4686 int buflen, bool* found_current) :
4687 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4688
4689 virtual void do_thread(Thread* thread) {
4690 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4691 }
4692 };
4693
4694 // Threads::print_on_error() is called by fatal error handler. It's possible
4695 // that VM is not at safepoint and/or current thread is inside signal handler.
4696 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4697 // memory (even in resource area), it might deadlock the error handler.
4698 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4699 int buflen) {
4700 ThreadsSMRSupport::print_info_on(st);
4701 st->cr();
4702
4703 bool found_current = false;
4704 st->print_cr("Java Threads: ( => current thread )");
4705 ALL_JAVA_THREADS(thread) {
4706 print_on_error(thread, st, current, buf, buflen, &found_current);
4707 }
4708 st->cr();
4709
4710 st->print_cr("Other Threads:");
4711 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4712 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4713
4714 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4715 Universe::heap()->gc_threads_do(&print_closure);
4716
4717 if (!found_current) {
4718 st->cr();
4719 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4720 current->print_on_error(st, buf, buflen);
4721 st->cr();
4722 }
4723 st->cr();
4724
4725 st->print_cr("Threads with active compile tasks:");
4726 print_threads_compiling(st, buf, buflen);
4727 }
4728
4729 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4730 ALL_JAVA_THREADS(thread) {
4731 if (thread->is_Compiler_thread()) {
4732 CompilerThread* ct = (CompilerThread*) thread;
4733
4734 // Keep task in local variable for NULL check.
4735 // ct->_task might be set to NULL by concurring compiler thread
4736 // because it completed the compilation. The task is never freed,
4737 // though, just returned to a free list.
4738 CompileTask* task = ct->task();
4739 if (task != NULL) {
4740 thread->print_name_on_error(st, buf, buflen);
4741 task->print(st, NULL, true, true);
4742 }
4743 }
4744 }
4745 }
4746
4747
4748 // Internal SpinLock and Mutex
4749 // Based on ParkEvent
4750
4751 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4752 //
4753 // We employ SpinLocks _only for low-contention, fixed-length
4754 // short-duration critical sections where we're concerned
4755 // about native mutex_t or HotSpot Mutex:: latency.
4756 // The mux construct provides a spin-then-block mutual exclusion
4757 // mechanism.
4758 //
4759 // Testing has shown that contention on the ListLock guarding gFreeList
4760 // is common. If we implement ListLock as a simple SpinLock it's common
4761 // for the JVM to devolve to yielding with little progress. This is true
4762 // despite the fact that the critical sections protected by ListLock are
4763 // extremely short.
4764 //
4765 // TODO-FIXME: ListLock should be of type SpinLock.
4766 // We should make this a 1st-class type, integrated into the lock
4767 // hierarchy as leaf-locks. Critically, the SpinLock structure
4768 // should have sufficient padding to avoid false-sharing and excessive
4769 // cache-coherency traffic.
4770
4771
4772 typedef volatile int SpinLockT;
4773
4774 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4775 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4776 return; // normal fast-path return
4777 }
4778
4779 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4780 TEVENT(SpinAcquire - ctx);
4781 int ctr = 0;
4782 int Yields = 0;
4783 for (;;) {
4784 while (*adr != 0) {
4785 ++ctr;
4786 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4787 if (Yields > 5) {
4788 os::naked_short_sleep(1);
4789 } else {
4790 os::naked_yield();
4791 ++Yields;
4792 }
4793 } else {
4794 SpinPause();
4795 }
4796 }
4797 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4798 }
4799 }
4800
4801 void Thread::SpinRelease(volatile int * adr) {
4802 assert(*adr != 0, "invariant");
4803 OrderAccess::fence(); // guarantee at least release consistency.
4804 // Roach-motel semantics.
4805 // It's safe if subsequent LDs and STs float "up" into the critical section,
4806 // but prior LDs and STs within the critical section can't be allowed
4807 // to reorder or float past the ST that releases the lock.
4808 // Loads and stores in the critical section - which appear in program
4809 // order before the store that releases the lock - must also appear
4810 // before the store that releases the lock in memory visibility order.
4811 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4812 // the ST of 0 into the lock-word which releases the lock, so fence
4813 // more than covers this on all platforms.
4814 *adr = 0;
4815 }
4816
4817 // muxAcquire and muxRelease:
4818 //
4819 // * muxAcquire and muxRelease support a single-word lock-word construct.
4820 // The LSB of the word is set IFF the lock is held.
4821 // The remainder of the word points to the head of a singly-linked list
4822 // of threads blocked on the lock.
4823 //
4824 // * The current implementation of muxAcquire-muxRelease uses its own
4825 // dedicated Thread._MuxEvent instance. If we're interested in
4826 // minimizing the peak number of extant ParkEvent instances then
4827 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4828 // as certain invariants were satisfied. Specifically, care would need
4829 // to be taken with regards to consuming unpark() "permits".
4830 // A safe rule of thumb is that a thread would never call muxAcquire()
4831 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4832 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4833 // consume an unpark() permit intended for monitorenter, for instance.
4834 // One way around this would be to widen the restricted-range semaphore
4835 // implemented in park(). Another alternative would be to provide
4836 // multiple instances of the PlatformEvent() for each thread. One
4837 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4838 //
4839 // * Usage:
4840 // -- Only as leaf locks
4841 // -- for short-term locking only as muxAcquire does not perform
4842 // thread state transitions.
4843 //
4844 // Alternatives:
4845 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4846 // but with parking or spin-then-park instead of pure spinning.
4847 // * Use Taura-Oyama-Yonenzawa locks.
4848 // * It's possible to construct a 1-0 lock if we encode the lockword as
4849 // (List,LockByte). Acquire will CAS the full lockword while Release
4850 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4851 // acquiring threads use timers (ParkTimed) to detect and recover from
4852 // the stranding window. Thread/Node structures must be aligned on 256-byte
4853 // boundaries by using placement-new.
4854 // * Augment MCS with advisory back-link fields maintained with CAS().
4855 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4856 // The validity of the backlinks must be ratified before we trust the value.
4857 // If the backlinks are invalid the exiting thread must back-track through the
4858 // the forward links, which are always trustworthy.
4859 // * Add a successor indication. The LockWord is currently encoded as
4860 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4861 // to provide the usual futile-wakeup optimization.
4862 // See RTStt for details.
4863 // * Consider schedctl.sc_nopreempt to cover the critical section.
4864 //
4865
4866
4867 const intptr_t LOCKBIT = 1;
4868
4869 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4870 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4871 if (w == 0) return;
4872 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4873 return;
4874 }
4875
4876 TEVENT(muxAcquire - Contention);
4877 ParkEvent * const Self = Thread::current()->_MuxEvent;
4878 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4879 for (;;) {
4880 int its = (os::is_MP() ? 100 : 0) + 1;
4881
4882 // Optional spin phase: spin-then-park strategy
4883 while (--its >= 0) {
4884 w = *Lock;
4885 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4886 return;
4887 }
4888 }
4889
4890 Self->reset();
4891 Self->OnList = intptr_t(Lock);
4892 // The following fence() isn't _strictly necessary as the subsequent
4893 // CAS() both serializes execution and ratifies the fetched *Lock value.
4894 OrderAccess::fence();
4895 for (;;) {
4896 w = *Lock;
4897 if ((w & LOCKBIT) == 0) {
4898 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4899 Self->OnList = 0; // hygiene - allows stronger asserts
4900 return;
4901 }
4902 continue; // Interference -- *Lock changed -- Just retry
4903 }
4904 assert(w & LOCKBIT, "invariant");
4905 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4906 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4907 }
4908
4909 while (Self->OnList != 0) {
4910 Self->park();
4911 }
4912 }
4913 }
4914
4915 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4916 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4917 if (w == 0) return;
4918 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4919 return;
4920 }
4921
4922 TEVENT(muxAcquire - Contention);
4923 ParkEvent * ReleaseAfter = NULL;
4924 if (ev == NULL) {
4925 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4926 }
4927 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4928 for (;;) {
4929 guarantee(ev->OnList == 0, "invariant");
4930 int its = (os::is_MP() ? 100 : 0) + 1;
4931
4932 // Optional spin phase: spin-then-park strategy
4933 while (--its >= 0) {
4934 w = *Lock;
4935 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4936 if (ReleaseAfter != NULL) {
4937 ParkEvent::Release(ReleaseAfter);
4938 }
4939 return;
4940 }
4941 }
4942
4943 ev->reset();
4944 ev->OnList = intptr_t(Lock);
4945 // The following fence() isn't _strictly necessary as the subsequent
4946 // CAS() both serializes execution and ratifies the fetched *Lock value.
4947 OrderAccess::fence();
4948 for (;;) {
4949 w = *Lock;
4950 if ((w & LOCKBIT) == 0) {
4951 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4952 ev->OnList = 0;
4953 // We call ::Release while holding the outer lock, thus
4954 // artificially lengthening the critical section.
4955 // Consider deferring the ::Release() until the subsequent unlock(),
4956 // after we've dropped the outer lock.
4957 if (ReleaseAfter != NULL) {
4958 ParkEvent::Release(ReleaseAfter);
4959 }
4960 return;
4961 }
4962 continue; // Interference -- *Lock changed -- Just retry
4963 }
4964 assert(w & LOCKBIT, "invariant");
4965 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4966 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4967 }
4968
4969 while (ev->OnList != 0) {
4970 ev->park();
4971 }
4972 }
4973 }
4974
4975 // Release() must extract a successor from the list and then wake that thread.
4976 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4977 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4978 // Release() would :
4979 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4980 // (B) Extract a successor from the private list "in-hand"
4981 // (C) attempt to CAS() the residual back into *Lock over null.
4982 // If there were any newly arrived threads and the CAS() would fail.
4983 // In that case Release() would detach the RATs, re-merge the list in-hand
4984 // with the RATs and repeat as needed. Alternately, Release() might
4985 // detach and extract a successor, but then pass the residual list to the wakee.
4986 // The wakee would be responsible for reattaching and remerging before it
4987 // competed for the lock.
4988 //
4989 // Both "pop" and DMR are immune from ABA corruption -- there can be
4990 // multiple concurrent pushers, but only one popper or detacher.
4991 // This implementation pops from the head of the list. This is unfair,
4992 // but tends to provide excellent throughput as hot threads remain hot.
4993 // (We wake recently run threads first).
4994 //
4995 // All paths through muxRelease() will execute a CAS.
4996 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4997 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4998 // executed within the critical section are complete and globally visible before the
4999 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5000 void Thread::muxRelease(volatile intptr_t * Lock) {
5001 for (;;) {
5002 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5003 assert(w & LOCKBIT, "invariant");
5004 if (w == LOCKBIT) return;
5005 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5006 assert(List != NULL, "invariant");
5007 assert(List->OnList == intptr_t(Lock), "invariant");
5008 ParkEvent * const nxt = List->ListNext;
5009 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5010
5011 // The following CAS() releases the lock and pops the head element.
5012 // The CAS() also ratifies the previously fetched lock-word value.
5013 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5014 continue;
5015 }
5016 List->OnList = 0;
5017 OrderAccess::fence();
5018 List->unpark();
5019 return;
5020 }
5021 }
5022
5023
5024 void Threads::verify() {
5025 ALL_JAVA_THREADS(p) {
5026 p->verify();
5027 }
5028 VMThread* thread = VMThread::vm_thread();
5029 if (thread != NULL) thread->verify();
5030 }