1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/barrierSet.hpp"
37 #include "gc/shared/gcId.hpp"
38 #include "gc/shared/gcLocker.inline.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "jfr/support/jfrThreadId.hpp"
45 #include "jvmtifiles/jvmtiEnv.hpp"
46 #include "logging/log.hpp"
47 #include "logging/logConfiguration.hpp"
48 #include "logging/logStream.hpp"
49 #include "memory/allocation.inline.hpp"
50 #include "memory/metaspaceShared.hpp"
51 #include "memory/oopFactory.hpp"
52 #include "memory/resourceArea.hpp"
53 #include "memory/universe.hpp"
54 #include "oops/access.inline.hpp"
55 #include "oops/instanceKlass.hpp"
56 #include "oops/objArrayOop.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/symbol.hpp"
59 #include "oops/typeArrayOop.inline.hpp"
60 #include "oops/verifyOopClosure.hpp"
61 #include "prims/jvm_misc.hpp"
62 #include "prims/jvmtiExport.hpp"
63 #include "prims/jvmtiThreadState.hpp"
64 #include "prims/privilegedStack.hpp"
65 #include "runtime/arguments.hpp"
66 #include "runtime/atomic.hpp"
67 #include "runtime/biasedLocking.hpp"
68 #include "runtime/flags/jvmFlagConstraintList.hpp"
69 #include "runtime/flags/jvmFlagRangeList.hpp"
70 #include "runtime/flags/jvmFlagWriteableList.hpp"
71 #include "runtime/deoptimization.hpp"
72 #include "runtime/frame.inline.hpp"
73 #include "runtime/handshake.hpp"
74 #include "runtime/init.hpp"
75 #include "runtime/interfaceSupport.inline.hpp"
76 #include "runtime/java.hpp"
77 #include "runtime/javaCalls.hpp"
78 #include "runtime/jniHandles.inline.hpp"
79 #include "runtime/jniPeriodicChecker.hpp"
80 #include "runtime/memprofiler.hpp"
81 #include "runtime/mutexLocker.hpp"
82 #include "runtime/objectMonitor.hpp"
83 #include "runtime/orderAccess.hpp"
84 #include "runtime/osThread.hpp"
85 #include "runtime/prefetch.inline.hpp"
86 #include "runtime/safepoint.hpp"
87 #include "runtime/safepointMechanism.inline.hpp"
88 #include "runtime/sharedRuntime.hpp"
89 #include "runtime/statSampler.hpp"
90 #include "runtime/stubRoutines.hpp"
91 #include "runtime/sweeper.hpp"
92 #include "runtime/task.hpp"
93 #include "runtime/thread.inline.hpp"
94 #include "runtime/threadCritical.hpp"
95 #include "runtime/threadSMR.inline.hpp"
96 #include "runtime/timer.hpp"
97 #include "runtime/timerTrace.hpp"
98 #include "runtime/vframe.inline.hpp"
99 #include "runtime/vframeArray.hpp"
100 #include "runtime/vframe_hp.hpp"
101 #include "runtime/vmThread.hpp"
102 #include "runtime/vm_operations.hpp"
103 #include "runtime/vm_version.hpp"
104 #include "services/attachListener.hpp"
105 #include "services/management.hpp"
106 #include "services/memTracker.hpp"
107 #include "services/threadService.hpp"
108 #include "utilities/align.hpp"
109 #include "utilities/copy.hpp"
110 #include "utilities/defaultStream.hpp"
111 #include "utilities/dtrace.hpp"
112 #include "utilities/events.hpp"
113 #include "utilities/macros.hpp"
114 #include "utilities/preserveException.hpp"
115 #include "utilities/vmError.hpp"
116 #if INCLUDE_JVMCI
117 #include "jvmci/jvmciCompiler.hpp"
118 #include "jvmci/jvmciRuntime.hpp"
119 #include "logging/logHandle.hpp"
120 #endif
121 #ifdef COMPILER1
122 #include "c1/c1_Compiler.hpp"
123 #endif
124 #ifdef COMPILER2
125 #include "opto/c2compiler.hpp"
126 #include "opto/idealGraphPrinter.hpp"
127 #endif
128 #if INCLUDE_RTM_OPT
129 #include "runtime/rtmLocking.hpp"
130 #endif
131 #if INCLUDE_JFR
132 #include "jfr/jfr.hpp"
133 #endif
134
135 // Initialization after module runtime initialization
136 void universe_post_module_init(); // must happen after call_initPhase2
137
138 #ifdef DTRACE_ENABLED
139
140 // Only bother with this argument setup if dtrace is available
141
142 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
143 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
144
145 #define DTRACE_THREAD_PROBE(probe, javathread) \
146 { \
147 ResourceMark rm(this); \
148 int len = 0; \
149 const char* name = (javathread)->get_thread_name(); \
150 len = strlen(name); \
151 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
152 (char *) name, len, \
153 java_lang_Thread::thread_id((javathread)->threadObj()), \
154 (uintptr_t) (javathread)->osthread()->thread_id(), \
155 java_lang_Thread::is_daemon((javathread)->threadObj())); \
156 }
157
158 #else // ndef DTRACE_ENABLED
159
160 #define DTRACE_THREAD_PROBE(probe, javathread)
161
162 #endif // ndef DTRACE_ENABLED
163
164 #ifndef USE_LIBRARY_BASED_TLS_ONLY
165 // Current thread is maintained as a thread-local variable
166 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
167 #endif
168 // Class hierarchy
169 // - Thread
170 // - VMThread
171 // - WatcherThread
172 // - ConcurrentMarkSweepThread
173 // - JavaThread
174 // - CompilerThread
175
176 // ======= Thread ========
177 // Support for forcing alignment of thread objects for biased locking
178 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
179 if (UseBiasedLocking) {
180 const int alignment = markOopDesc::biased_lock_alignment;
181 size_t aligned_size = size + (alignment - sizeof(intptr_t));
182 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
183 : AllocateHeap(aligned_size, flags, CURRENT_PC,
184 AllocFailStrategy::RETURN_NULL);
185 void* aligned_addr = align_up(real_malloc_addr, alignment);
186 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
187 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
188 "JavaThread alignment code overflowed allocated storage");
189 if (aligned_addr != real_malloc_addr) {
190 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
191 p2i(real_malloc_addr),
192 p2i(aligned_addr));
193 }
194 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
195 return aligned_addr;
196 } else {
197 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
198 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
199 }
200 }
201
202 void Thread::operator delete(void* p) {
203 if (UseBiasedLocking) {
204 FreeHeap(((Thread*) p)->_real_malloc_address);
205 } else {
206 FreeHeap(p);
207 }
208 }
209
210 void JavaThread::smr_delete() {
211 if (_on_thread_list) {
212 ThreadsSMRSupport::smr_delete(this);
213 } else {
214 delete this;
215 }
216 }
217
218 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
219 // JavaThread
220
221
222 Thread::Thread() {
223 // stack and get_thread
224 set_stack_base(NULL);
225 set_stack_size(0);
226 set_self_raw_id(0);
227 set_lgrp_id(-1);
228 DEBUG_ONLY(clear_suspendible_thread();)
229
230 // allocated data structures
231 set_osthread(NULL);
232 set_resource_area(new (mtThread)ResourceArea());
233 DEBUG_ONLY(_current_resource_mark = NULL;)
234 set_handle_area(new (mtThread) HandleArea(NULL));
235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
236 set_active_handles(NULL);
237 set_free_handle_block(NULL);
238 set_last_handle_mark(NULL);
239
240 _statistic_info.setStartTime(os::javaTimeMillis());
241 _statistic_info.setDefineClassCount(0);
242
243 // This initial value ==> never claimed.
244 _oops_do_parity = 0;
245 _threads_hazard_ptr = NULL;
246 _threads_list_ptr = NULL;
247 _nested_threads_hazard_ptr_cnt = 0;
248 _rcu_counter = 0;
249
250 // the handle mark links itself to last_handle_mark
251 new HandleMark(this);
252
253 // plain initialization
254 debug_only(_owned_locks = NULL;)
255 debug_only(_allow_allocation_count = 0;)
256 NOT_PRODUCT(_allow_safepoint_count = 0;)
257 NOT_PRODUCT(_skip_gcalot = false;)
258 _jvmti_env_iteration_count = 0;
259 set_allocated_bytes(0);
260 _vm_operation_started_count = 0;
261 _vm_operation_completed_count = 0;
262 _current_pending_monitor = NULL;
263 _current_pending_monitor_is_from_java = true;
264 _current_waiting_monitor = NULL;
265 _num_nested_signal = 0;
266 omFreeList = NULL;
267 omFreeCount = 0;
268 omFreeProvision = 32;
269 omInUseList = NULL;
270 omInUseCount = 0;
271
272 #ifdef ASSERT
273 _visited_for_critical_count = false;
274 #endif
275
276 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
277 Monitor::_safepoint_check_sometimes);
278 _suspend_flags = 0;
279
280 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
281 _hashStateX = os::random();
282 _hashStateY = 842502087;
283 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
284 _hashStateW = 273326509;
285
286 _OnTrap = 0;
287 _schedctl = NULL;
288 _Stalled = 0;
289 _TypeTag = 0x2BAD;
290
291 // Many of the following fields are effectively final - immutable
292 // Note that nascent threads can't use the Native Monitor-Mutex
293 // construct until the _MutexEvent is initialized ...
294 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
295 // we might instead use a stack of ParkEvents that we could provision on-demand.
296 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
297 // and ::Release()
298 _ParkEvent = ParkEvent::Allocate(this);
299 _SleepEvent = ParkEvent::Allocate(this);
300 _MutexEvent = ParkEvent::Allocate(this);
301 _MuxEvent = ParkEvent::Allocate(this);
302
303 #ifdef CHECK_UNHANDLED_OOPS
304 if (CheckUnhandledOops) {
305 _unhandled_oops = new UnhandledOops(this);
306 }
307 #endif // CHECK_UNHANDLED_OOPS
308 #ifdef ASSERT
309 if (UseBiasedLocking) {
310 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
311 assert(this == _real_malloc_address ||
312 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
313 "bug in forced alignment of thread objects");
314 }
315 #endif // ASSERT
316
317 // Notify the barrier set that a thread is being created. Note that the
318 // main thread is created before a barrier set is available. The call to
319 // BarrierSet::on_thread_create() for the main thread is therefore deferred
320 // until it calls BarrierSet::set_barrier_set().
321 BarrierSet* const barrier_set = BarrierSet::barrier_set();
322 if (barrier_set != NULL) {
323 barrier_set->on_thread_create(this);
324 }
325 }
326
327 void Thread::initialize_thread_current() {
328 #ifndef USE_LIBRARY_BASED_TLS_ONLY
329 assert(_thr_current == NULL, "Thread::current already initialized");
330 _thr_current = this;
331 #endif
332 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
333 ThreadLocalStorage::set_thread(this);
334 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
335 }
336
337 void Thread::clear_thread_current() {
338 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
339 #ifndef USE_LIBRARY_BASED_TLS_ONLY
340 _thr_current = NULL;
341 #endif
342 ThreadLocalStorage::set_thread(NULL);
343 }
344
345 void Thread::record_stack_base_and_size() {
346 set_stack_base(os::current_stack_base());
347 set_stack_size(os::current_stack_size());
348 // CR 7190089: on Solaris, primordial thread's stack is adjusted
349 // in initialize_thread(). Without the adjustment, stack size is
350 // incorrect if stack is set to unlimited (ulimit -s unlimited).
351 // So far, only Solaris has real implementation of initialize_thread().
352 //
353 // set up any platform-specific state.
354 os::initialize_thread(this);
355
356 // Set stack limits after thread is initialized.
357 if (is_Java_thread()) {
358 ((JavaThread*) this)->set_stack_overflow_limit();
359 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
360 }
361 #if INCLUDE_NMT
362 // record thread's native stack, stack grows downward
363 MemTracker::record_thread_stack(stack_end(), stack_size());
364 #endif // INCLUDE_NMT
365 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
366 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
367 os::current_thread_id(), p2i(stack_base() - stack_size()),
368 p2i(stack_base()), stack_size()/1024);
369 }
370
371
372 Thread::~Thread() {
373 JFR_ONLY(Jfr::on_thread_destruct(this);)
374
375 // Notify the barrier set that a thread is being destroyed. Note that a barrier
376 // set might not be available if we encountered errors during bootstrapping.
377 BarrierSet* const barrier_set = BarrierSet::barrier_set();
378 if (barrier_set != NULL) {
379 barrier_set->on_thread_destroy(this);
380 }
381
382
383 // stack_base can be NULL if the thread is never started or exited before
384 // record_stack_base_and_size called. Although, we would like to ensure
385 // that all started threads do call record_stack_base_and_size(), there is
386 // not proper way to enforce that.
387 #if INCLUDE_NMT
388 if (_stack_base != NULL) {
389 MemTracker::release_thread_stack(stack_end(), stack_size());
390 #ifdef ASSERT
391 set_stack_base(NULL);
392 #endif
393 }
394 #endif // INCLUDE_NMT
395
396 // deallocate data structures
397 delete resource_area();
398 // since the handle marks are using the handle area, we have to deallocated the root
399 // handle mark before deallocating the thread's handle area,
400 assert(last_handle_mark() != NULL, "check we have an element");
401 delete last_handle_mark();
402 assert(last_handle_mark() == NULL, "check we have reached the end");
403
404 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
405 // We NULL out the fields for good hygiene.
406 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
407 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
408 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
409 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
410
411 delete handle_area();
412 delete metadata_handles();
413
414 // SR_handler uses this as a termination indicator -
415 // needs to happen before os::free_thread()
416 delete _SR_lock;
417 _SR_lock = NULL;
418
419 // osthread() can be NULL, if creation of thread failed.
420 if (osthread() != NULL) os::free_thread(osthread());
421
422 // clear Thread::current if thread is deleting itself.
423 // Needed to ensure JNI correctly detects non-attached threads.
424 if (this == Thread::current()) {
425 clear_thread_current();
426 }
427
428 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
429 }
430
431 // NOTE: dummy function for assertion purpose.
432 void Thread::run() {
433 ShouldNotReachHere();
434 }
435
436 #ifdef ASSERT
437 // A JavaThread is considered "dangling" if it is not the current
438 // thread, has been added the Threads list, the system is not at a
439 // safepoint and the Thread is not "protected".
440 //
441 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
442 assert(!thread->is_Java_thread() || Thread::current() == thread ||
443 !((JavaThread *) thread)->on_thread_list() ||
444 SafepointSynchronize::is_at_safepoint() ||
445 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
446 "possibility of dangling Thread pointer");
447 }
448 #endif
449
450 ThreadPriority Thread::get_priority(const Thread* const thread) {
451 ThreadPriority priority;
452 // Can return an error!
453 (void)os::get_priority(thread, priority);
454 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
455 return priority;
456 }
457
458 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
459 debug_only(check_for_dangling_thread_pointer(thread);)
460 // Can return an error!
461 (void)os::set_priority(thread, priority);
462 }
463
464
465 void Thread::start(Thread* thread) {
466 // Start is different from resume in that its safety is guaranteed by context or
467 // being called from a Java method synchronized on the Thread object.
468 if (!DisableStartThread) {
469 if (thread->is_Java_thread()) {
470 // Initialize the thread state to RUNNABLE before starting this thread.
471 // Can not set it after the thread started because we do not know the
472 // exact thread state at that time. It could be in MONITOR_WAIT or
473 // in SLEEPING or some other state.
474 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
475 java_lang_Thread::RUNNABLE);
476 }
477 os::start_thread(thread);
478 }
479 }
480
481 // Enqueue a VM_Operation to do the job for us - sometime later
482 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
483 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
484 VMThread::execute(vm_stop);
485 }
486
487
488 // Check if an external suspend request has completed (or has been
489 // cancelled). Returns true if the thread is externally suspended and
490 // false otherwise.
491 //
492 // The bits parameter returns information about the code path through
493 // the routine. Useful for debugging:
494 //
495 // set in is_ext_suspend_completed():
496 // 0x00000001 - routine was entered
497 // 0x00000010 - routine return false at end
498 // 0x00000100 - thread exited (return false)
499 // 0x00000200 - suspend request cancelled (return false)
500 // 0x00000400 - thread suspended (return true)
501 // 0x00001000 - thread is in a suspend equivalent state (return true)
502 // 0x00002000 - thread is native and walkable (return true)
503 // 0x00004000 - thread is native_trans and walkable (needed retry)
504 //
505 // set in wait_for_ext_suspend_completion():
506 // 0x00010000 - routine was entered
507 // 0x00020000 - suspend request cancelled before loop (return false)
508 // 0x00040000 - thread suspended before loop (return true)
509 // 0x00080000 - suspend request cancelled in loop (return false)
510 // 0x00100000 - thread suspended in loop (return true)
511 // 0x00200000 - suspend not completed during retry loop (return false)
512
513 // Helper class for tracing suspend wait debug bits.
514 //
515 // 0x00000100 indicates that the target thread exited before it could
516 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
517 // 0x00080000 each indicate a cancelled suspend request so they don't
518 // count as wait failures either.
519 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
520
521 class TraceSuspendDebugBits : public StackObj {
522 private:
523 JavaThread * jt;
524 bool is_wait;
525 bool called_by_wait; // meaningful when !is_wait
526 uint32_t * bits;
527
528 public:
529 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
530 uint32_t *_bits) {
531 jt = _jt;
532 is_wait = _is_wait;
533 called_by_wait = _called_by_wait;
534 bits = _bits;
535 }
536
537 ~TraceSuspendDebugBits() {
538 if (!is_wait) {
539 #if 1
540 // By default, don't trace bits for is_ext_suspend_completed() calls.
541 // That trace is very chatty.
542 return;
543 #else
544 if (!called_by_wait) {
545 // If tracing for is_ext_suspend_completed() is enabled, then only
546 // trace calls to it from wait_for_ext_suspend_completion()
547 return;
548 }
549 #endif
550 }
551
552 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
553 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
554 MutexLocker ml(Threads_lock); // needed for get_thread_name()
555 ResourceMark rm;
556
557 tty->print_cr(
558 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
559 jt->get_thread_name(), *bits);
560
561 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
562 }
563 }
564 }
565 };
566 #undef DEBUG_FALSE_BITS
567
568
569 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
570 uint32_t *bits) {
571 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
572
573 bool did_trans_retry = false; // only do thread_in_native_trans retry once
574 bool do_trans_retry; // flag to force the retry
575
576 *bits |= 0x00000001;
577
578 do {
579 do_trans_retry = false;
580
581 if (is_exiting()) {
582 // Thread is in the process of exiting. This is always checked
583 // first to reduce the risk of dereferencing a freed JavaThread.
584 *bits |= 0x00000100;
585 return false;
586 }
587
588 if (!is_external_suspend()) {
589 // Suspend request is cancelled. This is always checked before
590 // is_ext_suspended() to reduce the risk of a rogue resume
591 // confusing the thread that made the suspend request.
592 *bits |= 0x00000200;
593 return false;
594 }
595
596 if (is_ext_suspended()) {
597 // thread is suspended
598 *bits |= 0x00000400;
599 return true;
600 }
601
602 // Now that we no longer do hard suspends of threads running
603 // native code, the target thread can be changing thread state
604 // while we are in this routine:
605 //
606 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
607 //
608 // We save a copy of the thread state as observed at this moment
609 // and make our decision about suspend completeness based on the
610 // copy. This closes the race where the thread state is seen as
611 // _thread_in_native_trans in the if-thread_blocked check, but is
612 // seen as _thread_blocked in if-thread_in_native_trans check.
613 JavaThreadState save_state = thread_state();
614
615 if (save_state == _thread_blocked && is_suspend_equivalent()) {
616 // If the thread's state is _thread_blocked and this blocking
617 // condition is known to be equivalent to a suspend, then we can
618 // consider the thread to be externally suspended. This means that
619 // the code that sets _thread_blocked has been modified to do
620 // self-suspension if the blocking condition releases. We also
621 // used to check for CONDVAR_WAIT here, but that is now covered by
622 // the _thread_blocked with self-suspension check.
623 //
624 // Return true since we wouldn't be here unless there was still an
625 // external suspend request.
626 *bits |= 0x00001000;
627 return true;
628 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
629 // Threads running native code will self-suspend on native==>VM/Java
630 // transitions. If its stack is walkable (should always be the case
631 // unless this function is called before the actual java_suspend()
632 // call), then the wait is done.
633 *bits |= 0x00002000;
634 return true;
635 } else if (!called_by_wait && !did_trans_retry &&
636 save_state == _thread_in_native_trans &&
637 frame_anchor()->walkable()) {
638 // The thread is transitioning from thread_in_native to another
639 // thread state. check_safepoint_and_suspend_for_native_trans()
640 // will force the thread to self-suspend. If it hasn't gotten
641 // there yet we may have caught the thread in-between the native
642 // code check above and the self-suspend. Lucky us. If we were
643 // called by wait_for_ext_suspend_completion(), then it
644 // will be doing the retries so we don't have to.
645 //
646 // Since we use the saved thread state in the if-statement above,
647 // there is a chance that the thread has already transitioned to
648 // _thread_blocked by the time we get here. In that case, we will
649 // make a single unnecessary pass through the logic below. This
650 // doesn't hurt anything since we still do the trans retry.
651
652 *bits |= 0x00004000;
653
654 // Once the thread leaves thread_in_native_trans for another
655 // thread state, we break out of this retry loop. We shouldn't
656 // need this flag to prevent us from getting back here, but
657 // sometimes paranoia is good.
658 did_trans_retry = true;
659
660 // We wait for the thread to transition to a more usable state.
661 for (int i = 1; i <= SuspendRetryCount; i++) {
662 // We used to do an "os::yield_all(i)" call here with the intention
663 // that yielding would increase on each retry. However, the parameter
664 // is ignored on Linux which means the yield didn't scale up. Waiting
665 // on the SR_lock below provides a much more predictable scale up for
666 // the delay. It also provides a simple/direct point to check for any
667 // safepoint requests from the VMThread
668
669 // temporarily drops SR_lock while doing wait with safepoint check
670 // (if we're a JavaThread - the WatcherThread can also call this)
671 // and increase delay with each retry
672 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
673
674 // check the actual thread state instead of what we saved above
675 if (thread_state() != _thread_in_native_trans) {
676 // the thread has transitioned to another thread state so
677 // try all the checks (except this one) one more time.
678 do_trans_retry = true;
679 break;
680 }
681 } // end retry loop
682
683
684 }
685 } while (do_trans_retry);
686
687 *bits |= 0x00000010;
688 return false;
689 }
690
691 // Wait for an external suspend request to complete (or be cancelled).
692 // Returns true if the thread is externally suspended and false otherwise.
693 //
694 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
695 uint32_t *bits) {
696 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
697 false /* !called_by_wait */, bits);
698
699 // local flag copies to minimize SR_lock hold time
700 bool is_suspended;
701 bool pending;
702 uint32_t reset_bits;
703
704 // set a marker so is_ext_suspend_completed() knows we are the caller
705 *bits |= 0x00010000;
706
707 // We use reset_bits to reinitialize the bits value at the top of
708 // each retry loop. This allows the caller to make use of any
709 // unused bits for their own marking purposes.
710 reset_bits = *bits;
711
712 {
713 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
714 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
715 delay, bits);
716 pending = is_external_suspend();
717 }
718 // must release SR_lock to allow suspension to complete
719
720 if (!pending) {
721 // A cancelled suspend request is the only false return from
722 // is_ext_suspend_completed() that keeps us from entering the
723 // retry loop.
724 *bits |= 0x00020000;
725 return false;
726 }
727
728 if (is_suspended) {
729 *bits |= 0x00040000;
730 return true;
731 }
732
733 for (int i = 1; i <= retries; i++) {
734 *bits = reset_bits; // reinit to only track last retry
735
736 // We used to do an "os::yield_all(i)" call here with the intention
737 // that yielding would increase on each retry. However, the parameter
738 // is ignored on Linux which means the yield didn't scale up. Waiting
739 // on the SR_lock below provides a much more predictable scale up for
740 // the delay. It also provides a simple/direct point to check for any
741 // safepoint requests from the VMThread
742
743 {
744 MutexLocker ml(SR_lock());
745 // wait with safepoint check (if we're a JavaThread - the WatcherThread
746 // can also call this) and increase delay with each retry
747 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
748
749 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
750 delay, bits);
751
752 // It is possible for the external suspend request to be cancelled
753 // (by a resume) before the actual suspend operation is completed.
754 // Refresh our local copy to see if we still need to wait.
755 pending = is_external_suspend();
756 }
757
758 if (!pending) {
759 // A cancelled suspend request is the only false return from
760 // is_ext_suspend_completed() that keeps us from staying in the
761 // retry loop.
762 *bits |= 0x00080000;
763 return false;
764 }
765
766 if (is_suspended) {
767 *bits |= 0x00100000;
768 return true;
769 }
770 } // end retry loop
771
772 // thread did not suspend after all our retries
773 *bits |= 0x00200000;
774 return false;
775 }
776
777 // Called from API entry points which perform stack walking. If the
778 // associated JavaThread is the current thread, then wait_for_suspend
779 // is not used. Otherwise, it determines if we should wait for the
780 // "other" thread to complete external suspension. (NOTE: in future
781 // releases the suspension mechanism should be reimplemented so this
782 // is not necessary.)
783 //
784 bool
785 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
786 if (this != JavaThread::current()) {
787 // "other" threads require special handling.
788 if (wait_for_suspend) {
789 // We are allowed to wait for the external suspend to complete
790 // so give the other thread a chance to get suspended.
791 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
792 SuspendRetryDelay, bits)) {
793 // Didn't make it so let the caller know.
794 return false;
795 }
796 }
797 // We aren't allowed to wait for the external suspend to complete
798 // so if the other thread isn't externally suspended we need to
799 // let the caller know.
800 else if (!is_ext_suspend_completed_with_lock(bits)) {
801 return false;
802 }
803 }
804
805 return true;
806 }
807
808 #ifndef PRODUCT
809 void JavaThread::record_jump(address target, address instr, const char* file,
810 int line) {
811
812 // This should not need to be atomic as the only way for simultaneous
813 // updates is via interrupts. Even then this should be rare or non-existent
814 // and we don't care that much anyway.
815
816 int index = _jmp_ring_index;
817 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
818 _jmp_ring[index]._target = (intptr_t) target;
819 _jmp_ring[index]._instruction = (intptr_t) instr;
820 _jmp_ring[index]._file = file;
821 _jmp_ring[index]._line = line;
822 }
823 #endif // PRODUCT
824
825 void Thread::interrupt(Thread* thread) {
826 debug_only(check_for_dangling_thread_pointer(thread);)
827 os::interrupt(thread);
828 }
829
830 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
831 debug_only(check_for_dangling_thread_pointer(thread);)
832 // Note: If clear_interrupted==false, this simply fetches and
833 // returns the value of the field osthread()->interrupted().
834 return os::is_interrupted(thread, clear_interrupted);
835 }
836
837
838 // GC Support
839 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
840 int thread_parity = _oops_do_parity;
841 if (thread_parity != strong_roots_parity) {
842 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
843 if (res == thread_parity) {
844 return true;
845 } else {
846 guarantee(res == strong_roots_parity, "Or else what?");
847 return false;
848 }
849 }
850 return false;
851 }
852
853 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
854 active_handles()->oops_do(f);
855 // Do oop for ThreadShadow
856 f->do_oop((oop*)&_pending_exception);
857 handle_area()->oops_do(f);
858
859 if (MonitorInUseLists) {
860 // When using thread local monitor lists, we scan them here,
861 // and the remaining global monitors in ObjectSynchronizer::oops_do().
862 ObjectSynchronizer::thread_local_used_oops_do(this, f);
863 }
864 }
865
866 void Thread::metadata_handles_do(void f(Metadata*)) {
867 // Only walk the Handles in Thread.
868 if (metadata_handles() != NULL) {
869 for (int i = 0; i< metadata_handles()->length(); i++) {
870 f(metadata_handles()->at(i));
871 }
872 }
873 }
874
875 void Thread::print_on(outputStream* st, bool extended_thread_info) const {
876 // get_priority assumes osthread initialized
877 if (osthread() != NULL) {
878 int os_prio;
879 if (os::get_native_priority(this, &os_prio) == OS_OK) {
880 st->print("os_prio=%d ", os_prio);
881 }
882
883 st->print("cpu=%.2fms ",
884 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
885 );
886 st->print("elapsed=%.2fs ",
887 _statistic_info.getElapsedTime() / 1000.0);
888
889 if (is_Java_thread() && (PrintExtendedThreadInfo || extended_thread_info)) {
890 jlong allocated_bytes = const_cast<Thread*>(this)->cooked_allocated_bytes();
891 st->print("allocated=" JLONG_FORMAT "B ", allocated_bytes);
892 st->print("defined_classes=" INT64_FORMAT " ", _statistic_info.getDefineClassCount());
893 }
894
895 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
896 osthread()->print_on(st);
897 }
898 ThreadsSMRSupport::print_info_on(this, st);
899 st->print(" ");
900 debug_only(if (WizardMode) print_owned_locks_on(st);)
901 }
902
903 // Thread::print_on_error() is called by fatal error handler. Don't use
904 // any lock or allocate memory.
905 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
906 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
907
908 if (is_VM_thread()) { st->print("VMThread"); }
909 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
910 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
911 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
912 else { st->print("Thread"); }
913
914 if (is_Named_thread()) {
915 st->print(" \"%s\"", name());
916 }
917
918 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
919 p2i(stack_end()), p2i(stack_base()));
920
921 if (osthread()) {
922 st->print(" [id=%d]", osthread()->thread_id());
923 }
924
925 ThreadsSMRSupport::print_info_on(this, st);
926 }
927
928 void Thread::print_value_on(outputStream* st) const {
929 if (is_Named_thread()) {
930 st->print(" \"%s\" ", name());
931 }
932 st->print(INTPTR_FORMAT, p2i(this)); // print address
933 }
934
935 #ifdef ASSERT
936 void Thread::print_owned_locks_on(outputStream* st) const {
937 Monitor *cur = _owned_locks;
938 if (cur == NULL) {
939 st->print(" (no locks) ");
940 } else {
941 st->print_cr(" Locks owned:");
942 while (cur) {
943 cur->print_on(st);
944 cur = cur->next();
945 }
946 }
947 }
948
949 static int ref_use_count = 0;
950
951 bool Thread::owns_locks_but_compiled_lock() const {
952 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
953 if (cur != Compile_lock) return true;
954 }
955 return false;
956 }
957
958
959 #endif
960
961 #ifndef PRODUCT
962
963 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
964 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
965 // no threads which allow_vm_block's are held
966 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
967 // Check if current thread is allowed to block at a safepoint
968 if (!(_allow_safepoint_count == 0)) {
969 fatal("Possible safepoint reached by thread that does not allow it");
970 }
971 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
972 fatal("LEAF method calling lock?");
973 }
974
975 #ifdef ASSERT
976 if (potential_vm_operation && is_Java_thread()
977 && !Universe::is_bootstrapping()) {
978 // Make sure we do not hold any locks that the VM thread also uses.
979 // This could potentially lead to deadlocks
980 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
981 // Threads_lock is special, since the safepoint synchronization will not start before this is
982 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
983 // since it is used to transfer control between JavaThreads and the VMThread
984 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
985 if ((cur->allow_vm_block() &&
986 cur != Threads_lock &&
987 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
988 cur != VMOperationRequest_lock &&
989 cur != VMOperationQueue_lock) ||
990 cur->rank() == Mutex::special) {
991 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
992 }
993 }
994 }
995
996 if (GCALotAtAllSafepoints) {
997 // We could enter a safepoint here and thus have a gc
998 InterfaceSupport::check_gc_alot();
999 }
1000 #endif
1001 }
1002 #endif
1003
1004 bool Thread::is_in_stack(address adr) const {
1005 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1006 address end = os::current_stack_pointer();
1007 // Allow non Java threads to call this without stack_base
1008 if (_stack_base == NULL) return true;
1009 if (stack_base() >= adr && adr >= end) return true;
1010
1011 return false;
1012 }
1013
1014 bool Thread::is_in_usable_stack(address adr) const {
1015 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1016 size_t usable_stack_size = _stack_size - stack_guard_size;
1017
1018 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1019 }
1020
1021
1022 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1023 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1024 // used for compilation in the future. If that change is made, the need for these methods
1025 // should be revisited, and they should be removed if possible.
1026
1027 bool Thread::is_lock_owned(address adr) const {
1028 return on_local_stack(adr);
1029 }
1030
1031 bool Thread::set_as_starting_thread() {
1032 // NOTE: this must be called inside the main thread.
1033 return os::create_main_thread((JavaThread*)this);
1034 }
1035
1036 static void initialize_class(Symbol* class_name, TRAPS) {
1037 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1038 InstanceKlass::cast(klass)->initialize(CHECK);
1039 }
1040
1041
1042 // Creates the initial ThreadGroup
1043 static Handle create_initial_thread_group(TRAPS) {
1044 Handle system_instance = JavaCalls::construct_new_instance(
1045 SystemDictionary::ThreadGroup_klass(),
1046 vmSymbols::void_method_signature(),
1047 CHECK_NH);
1048 Universe::set_system_thread_group(system_instance());
1049
1050 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1051 Handle main_instance = JavaCalls::construct_new_instance(
1052 SystemDictionary::ThreadGroup_klass(),
1053 vmSymbols::threadgroup_string_void_signature(),
1054 system_instance,
1055 string,
1056 CHECK_NH);
1057 return main_instance;
1058 }
1059
1060 // Creates the initial Thread
1061 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1062 TRAPS) {
1063 InstanceKlass* ik = SystemDictionary::Thread_klass();
1064 assert(ik->is_initialized(), "must be");
1065 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1066
1067 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1068 // constructor calls Thread.current(), which must be set here for the
1069 // initial thread.
1070 java_lang_Thread::set_thread(thread_oop(), thread);
1071 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1072 thread->set_threadObj(thread_oop());
1073
1074 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1075
1076 JavaValue result(T_VOID);
1077 JavaCalls::call_special(&result, thread_oop,
1078 ik,
1079 vmSymbols::object_initializer_name(),
1080 vmSymbols::threadgroup_string_void_signature(),
1081 thread_group,
1082 string,
1083 CHECK_NULL);
1084 return thread_oop();
1085 }
1086
1087 char java_runtime_name[128] = "";
1088 char java_runtime_version[128] = "";
1089
1090 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1091 static const char* get_java_runtime_name(TRAPS) {
1092 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1093 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1094 fieldDescriptor fd;
1095 bool found = k != NULL &&
1096 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1097 vmSymbols::string_signature(), &fd);
1098 if (found) {
1099 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1100 if (name_oop == NULL) {
1101 return NULL;
1102 }
1103 const char* name = java_lang_String::as_utf8_string(name_oop,
1104 java_runtime_name,
1105 sizeof(java_runtime_name));
1106 return name;
1107 } else {
1108 return NULL;
1109 }
1110 }
1111
1112 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1113 static const char* get_java_runtime_version(TRAPS) {
1114 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1115 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1116 fieldDescriptor fd;
1117 bool found = k != NULL &&
1118 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1119 vmSymbols::string_signature(), &fd);
1120 if (found) {
1121 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1122 if (name_oop == NULL) {
1123 return NULL;
1124 }
1125 const char* name = java_lang_String::as_utf8_string(name_oop,
1126 java_runtime_version,
1127 sizeof(java_runtime_version));
1128 return name;
1129 } else {
1130 return NULL;
1131 }
1132 }
1133
1134 // General purpose hook into Java code, run once when the VM is initialized.
1135 // The Java library method itself may be changed independently from the VM.
1136 static void call_postVMInitHook(TRAPS) {
1137 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1138 if (klass != NULL) {
1139 JavaValue result(T_VOID);
1140 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1141 vmSymbols::void_method_signature(),
1142 CHECK);
1143 }
1144 }
1145
1146 static void reset_vm_info_property(TRAPS) {
1147 // the vm info string
1148 ResourceMark rm(THREAD);
1149 const char *vm_info = VM_Version::vm_info_string();
1150
1151 // update the native system property first
1152 Arguments::PropertyList_update_value(Arguments::system_properties(), "java.vm.info", vm_info);
1153
1154 // java.lang.System class
1155 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1156
1157 // setProperty arguments
1158 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1159 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1160
1161 // return value
1162 JavaValue r(T_OBJECT);
1163
1164 // public static String setProperty(String key, String value);
1165 JavaCalls::call_static(&r,
1166 klass,
1167 vmSymbols::setProperty_name(),
1168 vmSymbols::string_string_string_signature(),
1169 key_str,
1170 value_str,
1171 CHECK);
1172 }
1173
1174
1175 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1176 bool daemon, TRAPS) {
1177 assert(thread_group.not_null(), "thread group should be specified");
1178 assert(threadObj() == NULL, "should only create Java thread object once");
1179
1180 InstanceKlass* ik = SystemDictionary::Thread_klass();
1181 assert(ik->is_initialized(), "must be");
1182 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1183
1184 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1185 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1186 // constructor calls Thread.current(), which must be set here.
1187 java_lang_Thread::set_thread(thread_oop(), this);
1188 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1189 set_threadObj(thread_oop());
1190
1191 JavaValue result(T_VOID);
1192 if (thread_name != NULL) {
1193 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1194 // Thread gets assigned specified name and null target
1195 JavaCalls::call_special(&result,
1196 thread_oop,
1197 ik,
1198 vmSymbols::object_initializer_name(),
1199 vmSymbols::threadgroup_string_void_signature(),
1200 thread_group,
1201 name,
1202 THREAD);
1203 } else {
1204 // Thread gets assigned name "Thread-nnn" and null target
1205 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1206 JavaCalls::call_special(&result,
1207 thread_oop,
1208 ik,
1209 vmSymbols::object_initializer_name(),
1210 vmSymbols::threadgroup_runnable_void_signature(),
1211 thread_group,
1212 Handle(),
1213 THREAD);
1214 }
1215
1216
1217 if (daemon) {
1218 java_lang_Thread::set_daemon(thread_oop());
1219 }
1220
1221 if (HAS_PENDING_EXCEPTION) {
1222 return;
1223 }
1224
1225 Klass* group = SystemDictionary::ThreadGroup_klass();
1226 Handle threadObj(THREAD, this->threadObj());
1227
1228 JavaCalls::call_special(&result,
1229 thread_group,
1230 group,
1231 vmSymbols::add_method_name(),
1232 vmSymbols::thread_void_signature(),
1233 threadObj, // Arg 1
1234 THREAD);
1235 }
1236
1237 // NamedThread -- non-JavaThread subclasses with multiple
1238 // uniquely named instances should derive from this.
1239 NamedThread::NamedThread() : Thread() {
1240 _name = NULL;
1241 _processed_thread = NULL;
1242 _gc_id = GCId::undefined();
1243 }
1244
1245 NamedThread::~NamedThread() {
1246 if (_name != NULL) {
1247 FREE_C_HEAP_ARRAY(char, _name);
1248 _name = NULL;
1249 }
1250 }
1251
1252 void NamedThread::set_name(const char* format, ...) {
1253 guarantee(_name == NULL, "Only get to set name once.");
1254 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1255 guarantee(_name != NULL, "alloc failure");
1256 va_list ap;
1257 va_start(ap, format);
1258 jio_vsnprintf(_name, max_name_len, format, ap);
1259 va_end(ap);
1260 }
1261
1262 void NamedThread::initialize_named_thread() {
1263 set_native_thread_name(name());
1264 }
1265
1266 void NamedThread::print_on(outputStream* st) const {
1267 st->print("\"%s\" ", name());
1268 Thread::print_on(st);
1269 st->cr();
1270 }
1271
1272
1273 // ======= WatcherThread ========
1274
1275 // The watcher thread exists to simulate timer interrupts. It should
1276 // be replaced by an abstraction over whatever native support for
1277 // timer interrupts exists on the platform.
1278
1279 WatcherThread* WatcherThread::_watcher_thread = NULL;
1280 bool WatcherThread::_startable = false;
1281 volatile bool WatcherThread::_should_terminate = false;
1282
1283 WatcherThread::WatcherThread() : Thread() {
1284 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1285 if (os::create_thread(this, os::watcher_thread)) {
1286 _watcher_thread = this;
1287
1288 // Set the watcher thread to the highest OS priority which should not be
1289 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1290 // is created. The only normal thread using this priority is the reference
1291 // handler thread, which runs for very short intervals only.
1292 // If the VMThread's priority is not lower than the WatcherThread profiling
1293 // will be inaccurate.
1294 os::set_priority(this, MaxPriority);
1295 if (!DisableStartThread) {
1296 os::start_thread(this);
1297 }
1298 }
1299 }
1300
1301 int WatcherThread::sleep() const {
1302 // The WatcherThread does not participate in the safepoint protocol
1303 // for the PeriodicTask_lock because it is not a JavaThread.
1304 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1305
1306 if (_should_terminate) {
1307 // check for termination before we do any housekeeping or wait
1308 return 0; // we did not sleep.
1309 }
1310
1311 // remaining will be zero if there are no tasks,
1312 // causing the WatcherThread to sleep until a task is
1313 // enrolled
1314 int remaining = PeriodicTask::time_to_wait();
1315 int time_slept = 0;
1316
1317 // we expect this to timeout - we only ever get unparked when
1318 // we should terminate or when a new task has been enrolled
1319 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1320
1321 jlong time_before_loop = os::javaTimeNanos();
1322
1323 while (true) {
1324 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1325 remaining);
1326 jlong now = os::javaTimeNanos();
1327
1328 if (remaining == 0) {
1329 // if we didn't have any tasks we could have waited for a long time
1330 // consider the time_slept zero and reset time_before_loop
1331 time_slept = 0;
1332 time_before_loop = now;
1333 } else {
1334 // need to recalculate since we might have new tasks in _tasks
1335 time_slept = (int) ((now - time_before_loop) / 1000000);
1336 }
1337
1338 // Change to task list or spurious wakeup of some kind
1339 if (timedout || _should_terminate) {
1340 break;
1341 }
1342
1343 remaining = PeriodicTask::time_to_wait();
1344 if (remaining == 0) {
1345 // Last task was just disenrolled so loop around and wait until
1346 // another task gets enrolled
1347 continue;
1348 }
1349
1350 remaining -= time_slept;
1351 if (remaining <= 0) {
1352 break;
1353 }
1354 }
1355
1356 return time_slept;
1357 }
1358
1359 void WatcherThread::run() {
1360 assert(this == watcher_thread(), "just checking");
1361
1362 this->record_stack_base_and_size();
1363 this->set_native_thread_name(this->name());
1364 this->set_active_handles(JNIHandleBlock::allocate_block());
1365 while (true) {
1366 assert(watcher_thread() == Thread::current(), "thread consistency check");
1367 assert(watcher_thread() == this, "thread consistency check");
1368
1369 // Calculate how long it'll be until the next PeriodicTask work
1370 // should be done, and sleep that amount of time.
1371 int time_waited = sleep();
1372
1373 if (VMError::is_error_reported()) {
1374 // A fatal error has happened, the error handler(VMError::report_and_die)
1375 // should abort JVM after creating an error log file. However in some
1376 // rare cases, the error handler itself might deadlock. Here periodically
1377 // check for error reporting timeouts, and if it happens, just proceed to
1378 // abort the VM.
1379
1380 // This code is in WatcherThread because WatcherThread wakes up
1381 // periodically so the fatal error handler doesn't need to do anything;
1382 // also because the WatcherThread is less likely to crash than other
1383 // threads.
1384
1385 for (;;) {
1386 // Note: we use naked sleep in this loop because we want to avoid using
1387 // any kind of VM infrastructure which may be broken at this point.
1388 if (VMError::check_timeout()) {
1389 // We hit error reporting timeout. Error reporting was interrupted and
1390 // will be wrapping things up now (closing files etc). Give it some more
1391 // time, then quit the VM.
1392 os::naked_short_sleep(200);
1393 // Print a message to stderr.
1394 fdStream err(defaultStream::output_fd());
1395 err.print_raw_cr("# [ timer expired, abort... ]");
1396 // skip atexit/vm_exit/vm_abort hooks
1397 os::die();
1398 }
1399
1400 // Wait a second, then recheck for timeout.
1401 os::naked_short_sleep(999);
1402 }
1403 }
1404
1405 if (_should_terminate) {
1406 // check for termination before posting the next tick
1407 break;
1408 }
1409
1410 PeriodicTask::real_time_tick(time_waited);
1411 }
1412
1413 // Signal that it is terminated
1414 {
1415 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1416 _watcher_thread = NULL;
1417 Terminator_lock->notify();
1418 }
1419 }
1420
1421 void WatcherThread::start() {
1422 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1423
1424 if (watcher_thread() == NULL && _startable) {
1425 _should_terminate = false;
1426 // Create the single instance of WatcherThread
1427 new WatcherThread();
1428 }
1429 }
1430
1431 void WatcherThread::make_startable() {
1432 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1433 _startable = true;
1434 }
1435
1436 void WatcherThread::stop() {
1437 {
1438 // Follow normal safepoint aware lock enter protocol since the
1439 // WatcherThread is stopped by another JavaThread.
1440 MutexLocker ml(PeriodicTask_lock);
1441 _should_terminate = true;
1442
1443 WatcherThread* watcher = watcher_thread();
1444 if (watcher != NULL) {
1445 // unpark the WatcherThread so it can see that it should terminate
1446 watcher->unpark();
1447 }
1448 }
1449
1450 MutexLocker mu(Terminator_lock);
1451
1452 while (watcher_thread() != NULL) {
1453 // This wait should make safepoint checks, wait without a timeout,
1454 // and wait as a suspend-equivalent condition.
1455 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1456 Mutex::_as_suspend_equivalent_flag);
1457 }
1458 }
1459
1460 void WatcherThread::unpark() {
1461 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1462 PeriodicTask_lock->notify();
1463 }
1464
1465 void WatcherThread::print_on(outputStream* st) const {
1466 st->print("\"%s\" ", name());
1467 Thread::print_on(st);
1468 st->cr();
1469 }
1470
1471 // ======= JavaThread ========
1472
1473 #if INCLUDE_JVMCI
1474
1475 jlong* JavaThread::_jvmci_old_thread_counters;
1476
1477 bool jvmci_counters_include(JavaThread* thread) {
1478 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1479 }
1480
1481 void JavaThread::collect_counters(typeArrayOop array) {
1482 if (JVMCICounterSize > 0) {
1483 JavaThreadIteratorWithHandle jtiwh;
1484 for (int i = 0; i < array->length(); i++) {
1485 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1486 }
1487 for (; JavaThread *tp = jtiwh.next(); ) {
1488 if (jvmci_counters_include(tp)) {
1489 for (int i = 0; i < array->length(); i++) {
1490 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1491 }
1492 }
1493 }
1494 }
1495 }
1496
1497 #endif // INCLUDE_JVMCI
1498
1499 // A JavaThread is a normal Java thread
1500
1501 void JavaThread::initialize() {
1502 // Initialize fields
1503
1504 set_saved_exception_pc(NULL);
1505 set_threadObj(NULL);
1506 _anchor.clear();
1507 set_entry_point(NULL);
1508 set_jni_functions(jni_functions());
1509 set_callee_target(NULL);
1510 set_vm_result(NULL);
1511 set_vm_result_2(NULL);
1512 set_vframe_array_head(NULL);
1513 set_vframe_array_last(NULL);
1514 set_deferred_locals(NULL);
1515 set_deopt_mark(NULL);
1516 set_deopt_compiled_method(NULL);
1517 clear_must_deopt_id();
1518 set_monitor_chunks(NULL);
1519 set_next(NULL);
1520 _on_thread_list = false;
1521 set_thread_state(_thread_new);
1522 _terminated = _not_terminated;
1523 _privileged_stack_top = NULL;
1524 _array_for_gc = NULL;
1525 _suspend_equivalent = false;
1526 _in_deopt_handler = 0;
1527 _doing_unsafe_access = false;
1528 _stack_guard_state = stack_guard_unused;
1529 #if INCLUDE_JVMCI
1530 _pending_monitorenter = false;
1531 _pending_deoptimization = -1;
1532 _pending_failed_speculation = NULL;
1533 _pending_transfer_to_interpreter = false;
1534 _adjusting_comp_level = false;
1535 _jvmci._alternate_call_target = NULL;
1536 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1537 if (JVMCICounterSize > 0) {
1538 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1539 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1540 } else {
1541 _jvmci_counters = NULL;
1542 }
1543 #endif // INCLUDE_JVMCI
1544 _reserved_stack_activation = NULL; // stack base not known yet
1545 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1546 _exception_pc = 0;
1547 _exception_handler_pc = 0;
1548 _is_method_handle_return = 0;
1549 _jvmti_thread_state= NULL;
1550 _should_post_on_exceptions_flag = JNI_FALSE;
1551 _jvmti_get_loaded_classes_closure = NULL;
1552 _interp_only_mode = 0;
1553 _special_runtime_exit_condition = _no_async_condition;
1554 _pending_async_exception = NULL;
1555 _thread_stat = NULL;
1556 _thread_stat = new ThreadStatistics();
1557 _blocked_on_compilation = false;
1558 _jni_active_critical = 0;
1559 _pending_jni_exception_check_fn = NULL;
1560 _do_not_unlock_if_synchronized = false;
1561 _cached_monitor_info = NULL;
1562 _parker = Parker::Allocate(this);
1563
1564 #ifndef PRODUCT
1565 _jmp_ring_index = 0;
1566 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1567 record_jump(NULL, NULL, NULL, 0);
1568 }
1569 #endif // PRODUCT
1570
1571 // Setup safepoint state info for this thread
1572 ThreadSafepointState::create(this);
1573
1574 debug_only(_java_call_counter = 0);
1575
1576 // JVMTI PopFrame support
1577 _popframe_condition = popframe_inactive;
1578 _popframe_preserved_args = NULL;
1579 _popframe_preserved_args_size = 0;
1580 _frames_to_pop_failed_realloc = 0;
1581
1582 if (SafepointMechanism::uses_thread_local_poll()) {
1583 SafepointMechanism::initialize_header(this);
1584 }
1585
1586 pd_initialize();
1587 }
1588
1589 JavaThread::JavaThread(bool is_attaching_via_jni) :
1590 Thread() {
1591 initialize();
1592 if (is_attaching_via_jni) {
1593 _jni_attach_state = _attaching_via_jni;
1594 } else {
1595 _jni_attach_state = _not_attaching_via_jni;
1596 }
1597 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1598 }
1599
1600 bool JavaThread::reguard_stack(address cur_sp) {
1601 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1602 && _stack_guard_state != stack_guard_reserved_disabled) {
1603 return true; // Stack already guarded or guard pages not needed.
1604 }
1605
1606 if (register_stack_overflow()) {
1607 // For those architectures which have separate register and
1608 // memory stacks, we must check the register stack to see if
1609 // it has overflowed.
1610 return false;
1611 }
1612
1613 // Java code never executes within the yellow zone: the latter is only
1614 // there to provoke an exception during stack banging. If java code
1615 // is executing there, either StackShadowPages should be larger, or
1616 // some exception code in c1, c2 or the interpreter isn't unwinding
1617 // when it should.
1618 guarantee(cur_sp > stack_reserved_zone_base(),
1619 "not enough space to reguard - increase StackShadowPages");
1620 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1621 enable_stack_yellow_reserved_zone();
1622 if (reserved_stack_activation() != stack_base()) {
1623 set_reserved_stack_activation(stack_base());
1624 }
1625 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1626 set_reserved_stack_activation(stack_base());
1627 enable_stack_reserved_zone();
1628 }
1629 return true;
1630 }
1631
1632 bool JavaThread::reguard_stack(void) {
1633 return reguard_stack(os::current_stack_pointer());
1634 }
1635
1636
1637 void JavaThread::block_if_vm_exited() {
1638 if (_terminated == _vm_exited) {
1639 // _vm_exited is set at safepoint, and Threads_lock is never released
1640 // we will block here forever
1641 Threads_lock->lock_without_safepoint_check();
1642 ShouldNotReachHere();
1643 }
1644 }
1645
1646
1647 // Remove this ifdef when C1 is ported to the compiler interface.
1648 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1649 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1650
1651 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1652 Thread() {
1653 initialize();
1654 _jni_attach_state = _not_attaching_via_jni;
1655 set_entry_point(entry_point);
1656 // Create the native thread itself.
1657 // %note runtime_23
1658 os::ThreadType thr_type = os::java_thread;
1659 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1660 os::java_thread;
1661 os::create_thread(this, thr_type, stack_sz);
1662 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1663 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1664 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1665 // the exception consists of creating the exception object & initializing it, initialization
1666 // will leave the VM via a JavaCall and then all locks must be unlocked).
1667 //
1668 // The thread is still suspended when we reach here. Thread must be explicit started
1669 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1670 // by calling Threads:add. The reason why this is not done here, is because the thread
1671 // object must be fully initialized (take a look at JVM_Start)
1672 }
1673
1674 JavaThread::~JavaThread() {
1675
1676 // JSR166 -- return the parker to the free list
1677 Parker::Release(_parker);
1678 _parker = NULL;
1679
1680 // Free any remaining previous UnrollBlock
1681 vframeArray* old_array = vframe_array_last();
1682
1683 if (old_array != NULL) {
1684 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1685 old_array->set_unroll_block(NULL);
1686 delete old_info;
1687 delete old_array;
1688 }
1689
1690 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1691 if (deferred != NULL) {
1692 // This can only happen if thread is destroyed before deoptimization occurs.
1693 assert(deferred->length() != 0, "empty array!");
1694 do {
1695 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1696 deferred->remove_at(0);
1697 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1698 delete dlv;
1699 } while (deferred->length() != 0);
1700 delete deferred;
1701 }
1702
1703 // All Java related clean up happens in exit
1704 ThreadSafepointState::destroy(this);
1705 if (_thread_stat != NULL) delete _thread_stat;
1706
1707 #if INCLUDE_JVMCI
1708 if (JVMCICounterSize > 0) {
1709 if (jvmci_counters_include(this)) {
1710 for (int i = 0; i < JVMCICounterSize; i++) {
1711 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1712 }
1713 }
1714 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1715 }
1716 #endif // INCLUDE_JVMCI
1717 }
1718
1719
1720 // The first routine called by a new Java thread
1721 void JavaThread::run() {
1722 // initialize thread-local alloc buffer related fields
1723 this->initialize_tlab();
1724
1725 // used to test validity of stack trace backs
1726 this->record_base_of_stack_pointer();
1727
1728 // Record real stack base and size.
1729 this->record_stack_base_and_size();
1730
1731 this->create_stack_guard_pages();
1732
1733 this->cache_global_variables();
1734
1735 // Thread is now sufficient initialized to be handled by the safepoint code as being
1736 // in the VM. Change thread state from _thread_new to _thread_in_vm
1737 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1738
1739 assert(JavaThread::current() == this, "sanity check");
1740 assert(!Thread::current()->owns_locks(), "sanity check");
1741
1742 DTRACE_THREAD_PROBE(start, this);
1743
1744 // This operation might block. We call that after all safepoint checks for a new thread has
1745 // been completed.
1746 this->set_active_handles(JNIHandleBlock::allocate_block());
1747
1748 if (JvmtiExport::should_post_thread_life()) {
1749 JvmtiExport::post_thread_start(this);
1750 }
1751
1752 EventThreadStart event;
1753 if (event.should_commit()) {
1754 event.set_thread(JFR_THREAD_ID(this));
1755 event.commit();
1756 }
1757
1758 // We call another function to do the rest so we are sure that the stack addresses used
1759 // from there will be lower than the stack base just computed
1760 thread_main_inner();
1761
1762 // Note, thread is no longer valid at this point!
1763 }
1764
1765
1766 void JavaThread::thread_main_inner() {
1767 assert(JavaThread::current() == this, "sanity check");
1768 assert(this->threadObj() != NULL, "just checking");
1769
1770 // Execute thread entry point unless this thread has a pending exception
1771 // or has been stopped before starting.
1772 // Note: Due to JVM_StopThread we can have pending exceptions already!
1773 if (!this->has_pending_exception() &&
1774 !java_lang_Thread::is_stillborn(this->threadObj())) {
1775 {
1776 ResourceMark rm(this);
1777 this->set_native_thread_name(this->get_thread_name());
1778 }
1779 HandleMark hm(this);
1780 this->entry_point()(this, this);
1781 }
1782
1783 DTRACE_THREAD_PROBE(stop, this);
1784
1785 this->exit(false);
1786 this->smr_delete();
1787 }
1788
1789
1790 static void ensure_join(JavaThread* thread) {
1791 // We do not need to grab the Threads_lock, since we are operating on ourself.
1792 Handle threadObj(thread, thread->threadObj());
1793 assert(threadObj.not_null(), "java thread object must exist");
1794 ObjectLocker lock(threadObj, thread);
1795 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1796 thread->clear_pending_exception();
1797 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1798 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1799 // Clear the native thread instance - this makes isAlive return false and allows the join()
1800 // to complete once we've done the notify_all below
1801 java_lang_Thread::set_thread(threadObj(), NULL);
1802 lock.notify_all(thread);
1803 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1804 thread->clear_pending_exception();
1805 }
1806
1807
1808 // For any new cleanup additions, please check to see if they need to be applied to
1809 // cleanup_failed_attach_current_thread as well.
1810 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1811 assert(this == JavaThread::current(), "thread consistency check");
1812
1813 elapsedTimer _timer_exit_phase1;
1814 elapsedTimer _timer_exit_phase2;
1815 elapsedTimer _timer_exit_phase3;
1816 elapsedTimer _timer_exit_phase4;
1817
1818 if (log_is_enabled(Debug, os, thread, timer)) {
1819 _timer_exit_phase1.start();
1820 }
1821
1822 HandleMark hm(this);
1823 Handle uncaught_exception(this, this->pending_exception());
1824 this->clear_pending_exception();
1825 Handle threadObj(this, this->threadObj());
1826 assert(threadObj.not_null(), "Java thread object should be created");
1827
1828 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1829 {
1830 EXCEPTION_MARK;
1831
1832 CLEAR_PENDING_EXCEPTION;
1833 }
1834 if (!destroy_vm) {
1835 if (uncaught_exception.not_null()) {
1836 EXCEPTION_MARK;
1837 // Call method Thread.dispatchUncaughtException().
1838 Klass* thread_klass = SystemDictionary::Thread_klass();
1839 JavaValue result(T_VOID);
1840 JavaCalls::call_virtual(&result,
1841 threadObj, thread_klass,
1842 vmSymbols::dispatchUncaughtException_name(),
1843 vmSymbols::throwable_void_signature(),
1844 uncaught_exception,
1845 THREAD);
1846 if (HAS_PENDING_EXCEPTION) {
1847 ResourceMark rm(this);
1848 jio_fprintf(defaultStream::error_stream(),
1849 "\nException: %s thrown from the UncaughtExceptionHandler"
1850 " in thread \"%s\"\n",
1851 pending_exception()->klass()->external_name(),
1852 get_thread_name());
1853 CLEAR_PENDING_EXCEPTION;
1854 }
1855 }
1856
1857 // Called before the java thread exit since we want to read info
1858 // from java_lang_Thread object
1859 EventThreadEnd event;
1860 if (event.should_commit()) {
1861 event.set_thread(JFR_THREAD_ID(this));
1862 event.commit();
1863 }
1864
1865 // Call after last event on thread
1866 JFR_ONLY(Jfr::on_thread_exit(this);)
1867
1868 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1869 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1870 // is deprecated anyhow.
1871 if (!is_Compiler_thread()) {
1872 int count = 3;
1873 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1874 EXCEPTION_MARK;
1875 JavaValue result(T_VOID);
1876 Klass* thread_klass = SystemDictionary::Thread_klass();
1877 JavaCalls::call_virtual(&result,
1878 threadObj, thread_klass,
1879 vmSymbols::exit_method_name(),
1880 vmSymbols::void_method_signature(),
1881 THREAD);
1882 CLEAR_PENDING_EXCEPTION;
1883 }
1884 }
1885 // notify JVMTI
1886 if (JvmtiExport::should_post_thread_life()) {
1887 JvmtiExport::post_thread_end(this);
1888 }
1889
1890 // We have notified the agents that we are exiting, before we go on,
1891 // we must check for a pending external suspend request and honor it
1892 // in order to not surprise the thread that made the suspend request.
1893 while (true) {
1894 {
1895 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1896 if (!is_external_suspend()) {
1897 set_terminated(_thread_exiting);
1898 ThreadService::current_thread_exiting(this);
1899 break;
1900 }
1901 // Implied else:
1902 // Things get a little tricky here. We have a pending external
1903 // suspend request, but we are holding the SR_lock so we
1904 // can't just self-suspend. So we temporarily drop the lock
1905 // and then self-suspend.
1906 }
1907
1908 ThreadBlockInVM tbivm(this);
1909 java_suspend_self();
1910
1911 // We're done with this suspend request, but we have to loop around
1912 // and check again. Eventually we will get SR_lock without a pending
1913 // external suspend request and will be able to mark ourselves as
1914 // exiting.
1915 }
1916 // no more external suspends are allowed at this point
1917 } else {
1918 // before_exit() has already posted JVMTI THREAD_END events
1919 }
1920
1921 if (log_is_enabled(Debug, os, thread, timer)) {
1922 _timer_exit_phase1.stop();
1923 _timer_exit_phase2.start();
1924 }
1925 // Notify waiters on thread object. This has to be done after exit() is called
1926 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1927 // group should have the destroyed bit set before waiters are notified).
1928 ensure_join(this);
1929 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1930
1931 if (log_is_enabled(Debug, os, thread, timer)) {
1932 _timer_exit_phase2.stop();
1933 _timer_exit_phase3.start();
1934 }
1935 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1936 // held by this thread must be released. The spec does not distinguish
1937 // between JNI-acquired and regular Java monitors. We can only see
1938 // regular Java monitors here if monitor enter-exit matching is broken.
1939 //
1940 // Optionally release any monitors for regular JavaThread exits. This
1941 // is provided as a work around for any bugs in monitor enter-exit
1942 // matching. This can be expensive so it is not enabled by default.
1943 //
1944 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1945 // ObjectSynchronizer::release_monitors_owned_by_thread().
1946 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1947 // Sanity check even though JNI DetachCurrentThread() would have
1948 // returned JNI_ERR if there was a Java frame. JavaThread exit
1949 // should be done executing Java code by the time we get here.
1950 assert(!this->has_last_Java_frame(),
1951 "should not have a Java frame when detaching or exiting");
1952 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1953 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1954 }
1955
1956 // These things needs to be done while we are still a Java Thread. Make sure that thread
1957 // is in a consistent state, in case GC happens
1958 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1959
1960 if (active_handles() != NULL) {
1961 JNIHandleBlock* block = active_handles();
1962 set_active_handles(NULL);
1963 JNIHandleBlock::release_block(block);
1964 }
1965
1966 if (free_handle_block() != NULL) {
1967 JNIHandleBlock* block = free_handle_block();
1968 set_free_handle_block(NULL);
1969 JNIHandleBlock::release_block(block);
1970 }
1971
1972 // These have to be removed while this is still a valid thread.
1973 remove_stack_guard_pages();
1974
1975 if (UseTLAB) {
1976 tlab().make_parsable(true); // retire TLAB
1977 }
1978
1979 if (JvmtiEnv::environments_might_exist()) {
1980 JvmtiExport::cleanup_thread(this);
1981 }
1982
1983 // We must flush any deferred card marks and other various GC barrier
1984 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
1985 // before removing a thread from the list of active threads.
1986 BarrierSet::barrier_set()->on_thread_detach(this);
1987
1988 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1989 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1990 os::current_thread_id());
1991
1992 if (log_is_enabled(Debug, os, thread, timer)) {
1993 _timer_exit_phase3.stop();
1994 _timer_exit_phase4.start();
1995 }
1996 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1997 Threads::remove(this);
1998
1999 if (log_is_enabled(Debug, os, thread, timer)) {
2000 _timer_exit_phase4.stop();
2001 ResourceMark rm(this);
2002 log_debug(os, thread, timer)("name='%s'"
2003 ", exit-phase1=" JLONG_FORMAT
2004 ", exit-phase2=" JLONG_FORMAT
2005 ", exit-phase3=" JLONG_FORMAT
2006 ", exit-phase4=" JLONG_FORMAT,
2007 get_thread_name(),
2008 _timer_exit_phase1.milliseconds(),
2009 _timer_exit_phase2.milliseconds(),
2010 _timer_exit_phase3.milliseconds(),
2011 _timer_exit_phase4.milliseconds());
2012 }
2013 }
2014
2015 void JavaThread::cleanup_failed_attach_current_thread() {
2016 if (active_handles() != NULL) {
2017 JNIHandleBlock* block = active_handles();
2018 set_active_handles(NULL);
2019 JNIHandleBlock::release_block(block);
2020 }
2021
2022 if (free_handle_block() != NULL) {
2023 JNIHandleBlock* block = free_handle_block();
2024 set_free_handle_block(NULL);
2025 JNIHandleBlock::release_block(block);
2026 }
2027
2028 // These have to be removed while this is still a valid thread.
2029 remove_stack_guard_pages();
2030
2031 if (UseTLAB) {
2032 tlab().make_parsable(true); // retire TLAB, if any
2033 }
2034
2035 BarrierSet::barrier_set()->on_thread_detach(this);
2036
2037 Threads::remove(this);
2038 this->smr_delete();
2039 }
2040
2041 JavaThread* JavaThread::active() {
2042 Thread* thread = Thread::current();
2043 if (thread->is_Java_thread()) {
2044 return (JavaThread*) thread;
2045 } else {
2046 assert(thread->is_VM_thread(), "this must be a vm thread");
2047 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2048 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2049 assert(ret->is_Java_thread(), "must be a Java thread");
2050 return ret;
2051 }
2052 }
2053
2054 bool JavaThread::is_lock_owned(address adr) const {
2055 if (Thread::is_lock_owned(adr)) return true;
2056
2057 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2058 if (chunk->contains(adr)) return true;
2059 }
2060
2061 return false;
2062 }
2063
2064
2065 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2066 chunk->set_next(monitor_chunks());
2067 set_monitor_chunks(chunk);
2068 }
2069
2070 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2071 guarantee(monitor_chunks() != NULL, "must be non empty");
2072 if (monitor_chunks() == chunk) {
2073 set_monitor_chunks(chunk->next());
2074 } else {
2075 MonitorChunk* prev = monitor_chunks();
2076 while (prev->next() != chunk) prev = prev->next();
2077 prev->set_next(chunk->next());
2078 }
2079 }
2080
2081 // JVM support.
2082
2083 // Note: this function shouldn't block if it's called in
2084 // _thread_in_native_trans state (such as from
2085 // check_special_condition_for_native_trans()).
2086 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2087
2088 if (has_last_Java_frame() && has_async_condition()) {
2089 // If we are at a polling page safepoint (not a poll return)
2090 // then we must defer async exception because live registers
2091 // will be clobbered by the exception path. Poll return is
2092 // ok because the call we a returning from already collides
2093 // with exception handling registers and so there is no issue.
2094 // (The exception handling path kills call result registers but
2095 // this is ok since the exception kills the result anyway).
2096
2097 if (is_at_poll_safepoint()) {
2098 // if the code we are returning to has deoptimized we must defer
2099 // the exception otherwise live registers get clobbered on the
2100 // exception path before deoptimization is able to retrieve them.
2101 //
2102 RegisterMap map(this, false);
2103 frame caller_fr = last_frame().sender(&map);
2104 assert(caller_fr.is_compiled_frame(), "what?");
2105 if (caller_fr.is_deoptimized_frame()) {
2106 log_info(exceptions)("deferred async exception at compiled safepoint");
2107 return;
2108 }
2109 }
2110 }
2111
2112 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2113 if (condition == _no_async_condition) {
2114 // Conditions have changed since has_special_runtime_exit_condition()
2115 // was called:
2116 // - if we were here only because of an external suspend request,
2117 // then that was taken care of above (or cancelled) so we are done
2118 // - if we were here because of another async request, then it has
2119 // been cleared between the has_special_runtime_exit_condition()
2120 // and now so again we are done
2121 return;
2122 }
2123
2124 // Check for pending async. exception
2125 if (_pending_async_exception != NULL) {
2126 // Only overwrite an already pending exception, if it is not a threadDeath.
2127 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2128
2129 // We cannot call Exceptions::_throw(...) here because we cannot block
2130 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2131
2132 LogTarget(Info, exceptions) lt;
2133 if (lt.is_enabled()) {
2134 ResourceMark rm;
2135 LogStream ls(lt);
2136 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2137 if (has_last_Java_frame()) {
2138 frame f = last_frame();
2139 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2140 }
2141 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2142 }
2143 _pending_async_exception = NULL;
2144 clear_has_async_exception();
2145 }
2146 }
2147
2148 if (check_unsafe_error &&
2149 condition == _async_unsafe_access_error && !has_pending_exception()) {
2150 condition = _no_async_condition; // done
2151 switch (thread_state()) {
2152 case _thread_in_vm: {
2153 JavaThread* THREAD = this;
2154 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2155 }
2156 case _thread_in_native: {
2157 ThreadInVMfromNative tiv(this);
2158 JavaThread* THREAD = this;
2159 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2160 }
2161 case _thread_in_Java: {
2162 ThreadInVMfromJava tiv(this);
2163 JavaThread* THREAD = this;
2164 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2165 }
2166 default:
2167 ShouldNotReachHere();
2168 }
2169 }
2170
2171 assert(condition == _no_async_condition || has_pending_exception() ||
2172 (!check_unsafe_error && condition == _async_unsafe_access_error),
2173 "must have handled the async condition, if no exception");
2174 }
2175
2176 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2177 //
2178 // Check for pending external suspend. Internal suspend requests do
2179 // not use handle_special_runtime_exit_condition().
2180 // If JNIEnv proxies are allowed, don't self-suspend if the target
2181 // thread is not the current thread. In older versions of jdbx, jdbx
2182 // threads could call into the VM with another thread's JNIEnv so we
2183 // can be here operating on behalf of a suspended thread (4432884).
2184 bool do_self_suspend = is_external_suspend_with_lock();
2185 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2186 //
2187 // Because thread is external suspended the safepoint code will count
2188 // thread as at a safepoint. This can be odd because we can be here
2189 // as _thread_in_Java which would normally transition to _thread_blocked
2190 // at a safepoint. We would like to mark the thread as _thread_blocked
2191 // before calling java_suspend_self like all other callers of it but
2192 // we must then observe proper safepoint protocol. (We can't leave
2193 // _thread_blocked with a safepoint in progress). However we can be
2194 // here as _thread_in_native_trans so we can't use a normal transition
2195 // constructor/destructor pair because they assert on that type of
2196 // transition. We could do something like:
2197 //
2198 // JavaThreadState state = thread_state();
2199 // set_thread_state(_thread_in_vm);
2200 // {
2201 // ThreadBlockInVM tbivm(this);
2202 // java_suspend_self()
2203 // }
2204 // set_thread_state(_thread_in_vm_trans);
2205 // if (safepoint) block;
2206 // set_thread_state(state);
2207 //
2208 // but that is pretty messy. Instead we just go with the way the
2209 // code has worked before and note that this is the only path to
2210 // java_suspend_self that doesn't put the thread in _thread_blocked
2211 // mode.
2212
2213 frame_anchor()->make_walkable(this);
2214 java_suspend_self();
2215
2216 // We might be here for reasons in addition to the self-suspend request
2217 // so check for other async requests.
2218 }
2219
2220 if (check_asyncs) {
2221 check_and_handle_async_exceptions();
2222 }
2223
2224 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2225 }
2226
2227 void JavaThread::send_thread_stop(oop java_throwable) {
2228 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2229 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2230 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2231
2232 // Do not throw asynchronous exceptions against the compiler thread
2233 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2234 if (!can_call_java()) return;
2235
2236 {
2237 // Actually throw the Throwable against the target Thread - however
2238 // only if there is no thread death exception installed already.
2239 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2240 // If the topmost frame is a runtime stub, then we are calling into
2241 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2242 // must deoptimize the caller before continuing, as the compiled exception handler table
2243 // may not be valid
2244 if (has_last_Java_frame()) {
2245 frame f = last_frame();
2246 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2247 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2248 RegisterMap reg_map(this, UseBiasedLocking);
2249 frame compiled_frame = f.sender(®_map);
2250 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2251 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2252 }
2253 }
2254 }
2255
2256 // Set async. pending exception in thread.
2257 set_pending_async_exception(java_throwable);
2258
2259 if (log_is_enabled(Info, exceptions)) {
2260 ResourceMark rm;
2261 log_info(exceptions)("Pending Async. exception installed of type: %s",
2262 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2263 }
2264 // for AbortVMOnException flag
2265 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2266 }
2267 }
2268
2269
2270 // Interrupt thread so it will wake up from a potential wait()
2271 Thread::interrupt(this);
2272 }
2273
2274 // External suspension mechanism.
2275 //
2276 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2277 // to any VM_locks and it is at a transition
2278 // Self-suspension will happen on the transition out of the vm.
2279 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2280 //
2281 // Guarantees on return:
2282 // + Target thread will not execute any new bytecode (that's why we need to
2283 // force a safepoint)
2284 // + Target thread will not enter any new monitors
2285 //
2286 void JavaThread::java_suspend() {
2287 ThreadsListHandle tlh;
2288 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2289 return;
2290 }
2291
2292 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2293 if (!is_external_suspend()) {
2294 // a racing resume has cancelled us; bail out now
2295 return;
2296 }
2297
2298 // suspend is done
2299 uint32_t debug_bits = 0;
2300 // Warning: is_ext_suspend_completed() may temporarily drop the
2301 // SR_lock to allow the thread to reach a stable thread state if
2302 // it is currently in a transient thread state.
2303 if (is_ext_suspend_completed(false /* !called_by_wait */,
2304 SuspendRetryDelay, &debug_bits)) {
2305 return;
2306 }
2307 }
2308
2309 VM_ThreadSuspend vm_suspend;
2310 VMThread::execute(&vm_suspend);
2311 }
2312
2313 // Part II of external suspension.
2314 // A JavaThread self suspends when it detects a pending external suspend
2315 // request. This is usually on transitions. It is also done in places
2316 // where continuing to the next transition would surprise the caller,
2317 // e.g., monitor entry.
2318 //
2319 // Returns the number of times that the thread self-suspended.
2320 //
2321 // Note: DO NOT call java_suspend_self() when you just want to block current
2322 // thread. java_suspend_self() is the second stage of cooperative
2323 // suspension for external suspend requests and should only be used
2324 // to complete an external suspend request.
2325 //
2326 int JavaThread::java_suspend_self() {
2327 int ret = 0;
2328
2329 // we are in the process of exiting so don't suspend
2330 if (is_exiting()) {
2331 clear_external_suspend();
2332 return ret;
2333 }
2334
2335 assert(_anchor.walkable() ||
2336 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2337 "must have walkable stack");
2338
2339 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2340
2341 assert(!this->is_ext_suspended(),
2342 "a thread trying to self-suspend should not already be suspended");
2343
2344 if (this->is_suspend_equivalent()) {
2345 // If we are self-suspending as a result of the lifting of a
2346 // suspend equivalent condition, then the suspend_equivalent
2347 // flag is not cleared until we set the ext_suspended flag so
2348 // that wait_for_ext_suspend_completion() returns consistent
2349 // results.
2350 this->clear_suspend_equivalent();
2351 }
2352
2353 // A racing resume may have cancelled us before we grabbed SR_lock
2354 // above. Or another external suspend request could be waiting for us
2355 // by the time we return from SR_lock()->wait(). The thread
2356 // that requested the suspension may already be trying to walk our
2357 // stack and if we return now, we can change the stack out from under
2358 // it. This would be a "bad thing (TM)" and cause the stack walker
2359 // to crash. We stay self-suspended until there are no more pending
2360 // external suspend requests.
2361 while (is_external_suspend()) {
2362 ret++;
2363 this->set_ext_suspended();
2364
2365 // _ext_suspended flag is cleared by java_resume()
2366 while (is_ext_suspended()) {
2367 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2368 }
2369 }
2370
2371 return ret;
2372 }
2373
2374 #ifdef ASSERT
2375 // Verify the JavaThread has not yet been published in the Threads::list, and
2376 // hence doesn't need protection from concurrent access at this stage.
2377 void JavaThread::verify_not_published() {
2378 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2379 // since an unpublished JavaThread doesn't participate in the
2380 // Thread-SMR protocol for keeping a ThreadsList alive.
2381 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2382 }
2383 #endif
2384
2385 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2386 // progress or when _suspend_flags is non-zero.
2387 // Current thread needs to self-suspend if there is a suspend request and/or
2388 // block if a safepoint is in progress.
2389 // Async exception ISN'T checked.
2390 // Note only the ThreadInVMfromNative transition can call this function
2391 // directly and when thread state is _thread_in_native_trans
2392 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2393 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2394
2395 JavaThread *curJT = JavaThread::current();
2396 bool do_self_suspend = thread->is_external_suspend();
2397
2398 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2399
2400 // If JNIEnv proxies are allowed, don't self-suspend if the target
2401 // thread is not the current thread. In older versions of jdbx, jdbx
2402 // threads could call into the VM with another thread's JNIEnv so we
2403 // can be here operating on behalf of a suspended thread (4432884).
2404 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2405 JavaThreadState state = thread->thread_state();
2406
2407 // We mark this thread_blocked state as a suspend-equivalent so
2408 // that a caller to is_ext_suspend_completed() won't be confused.
2409 // The suspend-equivalent state is cleared by java_suspend_self().
2410 thread->set_suspend_equivalent();
2411
2412 // If the safepoint code sees the _thread_in_native_trans state, it will
2413 // wait until the thread changes to other thread state. There is no
2414 // guarantee on how soon we can obtain the SR_lock and complete the
2415 // self-suspend request. It would be a bad idea to let safepoint wait for
2416 // too long. Temporarily change the state to _thread_blocked to
2417 // let the VM thread know that this thread is ready for GC. The problem
2418 // of changing thread state is that safepoint could happen just after
2419 // java_suspend_self() returns after being resumed, and VM thread will
2420 // see the _thread_blocked state. We must check for safepoint
2421 // after restoring the state and make sure we won't leave while a safepoint
2422 // is in progress.
2423 thread->set_thread_state(_thread_blocked);
2424 thread->java_suspend_self();
2425 thread->set_thread_state(state);
2426
2427 InterfaceSupport::serialize_thread_state_with_handler(thread);
2428 }
2429
2430 SafepointMechanism::block_if_requested(curJT);
2431
2432 if (thread->is_deopt_suspend()) {
2433 thread->clear_deopt_suspend();
2434 RegisterMap map(thread, false);
2435 frame f = thread->last_frame();
2436 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2437 f = f.sender(&map);
2438 }
2439 if (f.id() == thread->must_deopt_id()) {
2440 thread->clear_must_deopt_id();
2441 f.deoptimize(thread);
2442 } else {
2443 fatal("missed deoptimization!");
2444 }
2445 }
2446
2447 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2448 }
2449
2450 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2451 // progress or when _suspend_flags is non-zero.
2452 // Current thread needs to self-suspend if there is a suspend request and/or
2453 // block if a safepoint is in progress.
2454 // Also check for pending async exception (not including unsafe access error).
2455 // Note only the native==>VM/Java barriers can call this function and when
2456 // thread state is _thread_in_native_trans.
2457 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2458 check_safepoint_and_suspend_for_native_trans(thread);
2459
2460 if (thread->has_async_exception()) {
2461 // We are in _thread_in_native_trans state, don't handle unsafe
2462 // access error since that may block.
2463 thread->check_and_handle_async_exceptions(false);
2464 }
2465 }
2466
2467 // This is a variant of the normal
2468 // check_special_condition_for_native_trans with slightly different
2469 // semantics for use by critical native wrappers. It does all the
2470 // normal checks but also performs the transition back into
2471 // thread_in_Java state. This is required so that critical natives
2472 // can potentially block and perform a GC if they are the last thread
2473 // exiting the GCLocker.
2474 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2475 check_special_condition_for_native_trans(thread);
2476
2477 // Finish the transition
2478 thread->set_thread_state(_thread_in_Java);
2479
2480 if (thread->do_critical_native_unlock()) {
2481 ThreadInVMfromJavaNoAsyncException tiv(thread);
2482 GCLocker::unlock_critical(thread);
2483 thread->clear_critical_native_unlock();
2484 }
2485 }
2486
2487 // We need to guarantee the Threads_lock here, since resumes are not
2488 // allowed during safepoint synchronization
2489 // Can only resume from an external suspension
2490 void JavaThread::java_resume() {
2491 assert_locked_or_safepoint(Threads_lock);
2492
2493 // Sanity check: thread is gone, has started exiting or the thread
2494 // was not externally suspended.
2495 ThreadsListHandle tlh;
2496 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2497 return;
2498 }
2499
2500 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2501
2502 clear_external_suspend();
2503
2504 if (is_ext_suspended()) {
2505 clear_ext_suspended();
2506 SR_lock()->notify_all();
2507 }
2508 }
2509
2510 size_t JavaThread::_stack_red_zone_size = 0;
2511 size_t JavaThread::_stack_yellow_zone_size = 0;
2512 size_t JavaThread::_stack_reserved_zone_size = 0;
2513 size_t JavaThread::_stack_shadow_zone_size = 0;
2514
2515 void JavaThread::create_stack_guard_pages() {
2516 if (!os::uses_stack_guard_pages() ||
2517 _stack_guard_state != stack_guard_unused ||
2518 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2519 log_info(os, thread)("Stack guard page creation for thread "
2520 UINTX_FORMAT " disabled", os::current_thread_id());
2521 return;
2522 }
2523 address low_addr = stack_end();
2524 size_t len = stack_guard_zone_size();
2525
2526 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2527 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2528
2529 int must_commit = os::must_commit_stack_guard_pages();
2530 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2531
2532 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2533 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2534 return;
2535 }
2536
2537 if (os::guard_memory((char *) low_addr, len)) {
2538 _stack_guard_state = stack_guard_enabled;
2539 } else {
2540 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2541 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2542 if (os::uncommit_memory((char *) low_addr, len)) {
2543 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2544 }
2545 return;
2546 }
2547
2548 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2549 PTR_FORMAT "-" PTR_FORMAT ".",
2550 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2551 }
2552
2553 void JavaThread::remove_stack_guard_pages() {
2554 assert(Thread::current() == this, "from different thread");
2555 if (_stack_guard_state == stack_guard_unused) return;
2556 address low_addr = stack_end();
2557 size_t len = stack_guard_zone_size();
2558
2559 if (os::must_commit_stack_guard_pages()) {
2560 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2561 _stack_guard_state = stack_guard_unused;
2562 } else {
2563 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2564 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2565 return;
2566 }
2567 } else {
2568 if (_stack_guard_state == stack_guard_unused) return;
2569 if (os::unguard_memory((char *) low_addr, len)) {
2570 _stack_guard_state = stack_guard_unused;
2571 } else {
2572 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2573 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2574 return;
2575 }
2576 }
2577
2578 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2579 PTR_FORMAT "-" PTR_FORMAT ".",
2580 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2581 }
2582
2583 void JavaThread::enable_stack_reserved_zone() {
2584 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2585 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2586
2587 // The base notation is from the stack's point of view, growing downward.
2588 // We need to adjust it to work correctly with guard_memory()
2589 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2590
2591 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2592 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2593
2594 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2595 _stack_guard_state = stack_guard_enabled;
2596 } else {
2597 warning("Attempt to guard stack reserved zone failed.");
2598 }
2599 enable_register_stack_guard();
2600 }
2601
2602 void JavaThread::disable_stack_reserved_zone() {
2603 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2604 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2605
2606 // Simply return if called for a thread that does not use guard pages.
2607 if (_stack_guard_state == stack_guard_unused) return;
2608
2609 // The base notation is from the stack's point of view, growing downward.
2610 // We need to adjust it to work correctly with guard_memory()
2611 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2612
2613 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2614 _stack_guard_state = stack_guard_reserved_disabled;
2615 } else {
2616 warning("Attempt to unguard stack reserved zone failed.");
2617 }
2618 disable_register_stack_guard();
2619 }
2620
2621 void JavaThread::enable_stack_yellow_reserved_zone() {
2622 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2623 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2624
2625 // The base notation is from the stacks point of view, growing downward.
2626 // We need to adjust it to work correctly with guard_memory()
2627 address base = stack_red_zone_base();
2628
2629 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2630 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2631
2632 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2633 _stack_guard_state = stack_guard_enabled;
2634 } else {
2635 warning("Attempt to guard stack yellow zone failed.");
2636 }
2637 enable_register_stack_guard();
2638 }
2639
2640 void JavaThread::disable_stack_yellow_reserved_zone() {
2641 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2642 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2643
2644 // Simply return if called for a thread that does not use guard pages.
2645 if (_stack_guard_state == stack_guard_unused) return;
2646
2647 // The base notation is from the stacks point of view, growing downward.
2648 // We need to adjust it to work correctly with guard_memory()
2649 address base = stack_red_zone_base();
2650
2651 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2652 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2653 } else {
2654 warning("Attempt to unguard stack yellow zone failed.");
2655 }
2656 disable_register_stack_guard();
2657 }
2658
2659 void JavaThread::enable_stack_red_zone() {
2660 // The base notation is from the stacks point of view, growing downward.
2661 // We need to adjust it to work correctly with guard_memory()
2662 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2663 address base = stack_red_zone_base() - stack_red_zone_size();
2664
2665 guarantee(base < stack_base(), "Error calculating stack red zone");
2666 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2667
2668 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2669 warning("Attempt to guard stack red zone failed.");
2670 }
2671 }
2672
2673 void JavaThread::disable_stack_red_zone() {
2674 // The base notation is from the stacks point of view, growing downward.
2675 // We need to adjust it to work correctly with guard_memory()
2676 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2677 address base = stack_red_zone_base() - stack_red_zone_size();
2678 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2679 warning("Attempt to unguard stack red zone failed.");
2680 }
2681 }
2682
2683 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2684 // ignore is there is no stack
2685 if (!has_last_Java_frame()) return;
2686 // traverse the stack frames. Starts from top frame.
2687 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2688 frame* fr = fst.current();
2689 f(fr, fst.register_map());
2690 }
2691 }
2692
2693
2694 #ifndef PRODUCT
2695 // Deoptimization
2696 // Function for testing deoptimization
2697 void JavaThread::deoptimize() {
2698 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2699 StackFrameStream fst(this, UseBiasedLocking);
2700 bool deopt = false; // Dump stack only if a deopt actually happens.
2701 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2702 // Iterate over all frames in the thread and deoptimize
2703 for (; !fst.is_done(); fst.next()) {
2704 if (fst.current()->can_be_deoptimized()) {
2705
2706 if (only_at) {
2707 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2708 // consists of comma or carriage return separated numbers so
2709 // search for the current bci in that string.
2710 address pc = fst.current()->pc();
2711 nmethod* nm = (nmethod*) fst.current()->cb();
2712 ScopeDesc* sd = nm->scope_desc_at(pc);
2713 char buffer[8];
2714 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2715 size_t len = strlen(buffer);
2716 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2717 while (found != NULL) {
2718 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2719 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2720 // Check that the bci found is bracketed by terminators.
2721 break;
2722 }
2723 found = strstr(found + 1, buffer);
2724 }
2725 if (!found) {
2726 continue;
2727 }
2728 }
2729
2730 if (DebugDeoptimization && !deopt) {
2731 deopt = true; // One-time only print before deopt
2732 tty->print_cr("[BEFORE Deoptimization]");
2733 trace_frames();
2734 trace_stack();
2735 }
2736 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2737 }
2738 }
2739
2740 if (DebugDeoptimization && deopt) {
2741 tty->print_cr("[AFTER Deoptimization]");
2742 trace_frames();
2743 }
2744 }
2745
2746
2747 // Make zombies
2748 void JavaThread::make_zombies() {
2749 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2750 if (fst.current()->can_be_deoptimized()) {
2751 // it is a Java nmethod
2752 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2753 nm->make_not_entrant();
2754 }
2755 }
2756 }
2757 #endif // PRODUCT
2758
2759
2760 void JavaThread::deoptimized_wrt_marked_nmethods() {
2761 if (!has_last_Java_frame()) return;
2762 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2763 StackFrameStream fst(this, UseBiasedLocking);
2764 for (; !fst.is_done(); fst.next()) {
2765 if (fst.current()->should_be_deoptimized()) {
2766 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2767 }
2768 }
2769 }
2770
2771
2772 // If the caller is a NamedThread, then remember, in the current scope,
2773 // the given JavaThread in its _processed_thread field.
2774 class RememberProcessedThread: public StackObj {
2775 NamedThread* _cur_thr;
2776 public:
2777 RememberProcessedThread(JavaThread* jthr) {
2778 Thread* thread = Thread::current();
2779 if (thread->is_Named_thread()) {
2780 _cur_thr = (NamedThread *)thread;
2781 _cur_thr->set_processed_thread(jthr);
2782 } else {
2783 _cur_thr = NULL;
2784 }
2785 }
2786
2787 ~RememberProcessedThread() {
2788 if (_cur_thr) {
2789 _cur_thr->set_processed_thread(NULL);
2790 }
2791 }
2792 };
2793
2794 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2795 // Verify that the deferred card marks have been flushed.
2796 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2797
2798 // Traverse the GCHandles
2799 Thread::oops_do(f, cf);
2800
2801 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2802
2803 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2804 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2805
2806 if (has_last_Java_frame()) {
2807 // Record JavaThread to GC thread
2808 RememberProcessedThread rpt(this);
2809
2810 // Traverse the privileged stack
2811 if (_privileged_stack_top != NULL) {
2812 _privileged_stack_top->oops_do(f);
2813 }
2814
2815 // traverse the registered growable array
2816 if (_array_for_gc != NULL) {
2817 for (int index = 0; index < _array_for_gc->length(); index++) {
2818 f->do_oop(_array_for_gc->adr_at(index));
2819 }
2820 }
2821
2822 // Traverse the monitor chunks
2823 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2824 chunk->oops_do(f);
2825 }
2826
2827 // Traverse the execution stack
2828 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2829 fst.current()->oops_do(f, cf, fst.register_map());
2830 }
2831 }
2832
2833 // callee_target is never live across a gc point so NULL it here should
2834 // it still contain a methdOop.
2835
2836 set_callee_target(NULL);
2837
2838 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2839 // If we have deferred set_locals there might be oops waiting to be
2840 // written
2841 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2842 if (list != NULL) {
2843 for (int i = 0; i < list->length(); i++) {
2844 list->at(i)->oops_do(f);
2845 }
2846 }
2847
2848 // Traverse instance variables at the end since the GC may be moving things
2849 // around using this function
2850 f->do_oop((oop*) &_threadObj);
2851 f->do_oop((oop*) &_vm_result);
2852 f->do_oop((oop*) &_exception_oop);
2853 f->do_oop((oop*) &_pending_async_exception);
2854
2855 if (jvmti_thread_state() != NULL) {
2856 jvmti_thread_state()->oops_do(f);
2857 }
2858 }
2859
2860 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2861 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2862 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2863
2864 if (has_last_Java_frame()) {
2865 // Traverse the execution stack
2866 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2867 fst.current()->nmethods_do(cf);
2868 }
2869 }
2870 }
2871
2872 void JavaThread::metadata_do(void f(Metadata*)) {
2873 if (has_last_Java_frame()) {
2874 // Traverse the execution stack to call f() on the methods in the stack
2875 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2876 fst.current()->metadata_do(f);
2877 }
2878 } else if (is_Compiler_thread()) {
2879 // need to walk ciMetadata in current compile tasks to keep alive.
2880 CompilerThread* ct = (CompilerThread*)this;
2881 if (ct->env() != NULL) {
2882 ct->env()->metadata_do(f);
2883 }
2884 CompileTask* task = ct->task();
2885 if (task != NULL) {
2886 task->metadata_do(f);
2887 }
2888 }
2889 }
2890
2891 // Printing
2892 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2893 switch (_thread_state) {
2894 case _thread_uninitialized: return "_thread_uninitialized";
2895 case _thread_new: return "_thread_new";
2896 case _thread_new_trans: return "_thread_new_trans";
2897 case _thread_in_native: return "_thread_in_native";
2898 case _thread_in_native_trans: return "_thread_in_native_trans";
2899 case _thread_in_vm: return "_thread_in_vm";
2900 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2901 case _thread_in_Java: return "_thread_in_Java";
2902 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2903 case _thread_blocked: return "_thread_blocked";
2904 case _thread_blocked_trans: return "_thread_blocked_trans";
2905 default: return "unknown thread state";
2906 }
2907 }
2908
2909 #ifndef PRODUCT
2910 void JavaThread::print_thread_state_on(outputStream *st) const {
2911 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2912 };
2913 void JavaThread::print_thread_state() const {
2914 print_thread_state_on(tty);
2915 }
2916 #endif // PRODUCT
2917
2918 // Called by Threads::print() for VM_PrintThreads operation
2919 void JavaThread::print_on(outputStream *st, bool extended_thread_info) const {
2920 st->print_raw("\"");
2921 st->print_raw(get_thread_name());
2922 st->print_raw("\" ");
2923 oop thread_oop = threadObj();
2924 if (thread_oop != NULL) {
2925 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2926 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2927 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2928 }
2929 Thread::print_on(st, extended_thread_info);
2930 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2931 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2932 if (thread_oop != NULL) {
2933 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2934 }
2935 #ifndef PRODUCT
2936 print_thread_state_on(st);
2937 _safepoint_state->print_on(st);
2938 #endif // PRODUCT
2939 if (is_Compiler_thread()) {
2940 CompileTask *task = ((CompilerThread*)this)->task();
2941 if (task != NULL) {
2942 st->print(" Compiling: ");
2943 task->print(st, NULL, true, false);
2944 } else {
2945 st->print(" No compile task");
2946 }
2947 st->cr();
2948 }
2949 }
2950
2951 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2952 st->print("%s", get_thread_name_string(buf, buflen));
2953 }
2954
2955 // Called by fatal error handler. The difference between this and
2956 // JavaThread::print() is that we can't grab lock or allocate memory.
2957 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2958 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2959 oop thread_obj = threadObj();
2960 if (thread_obj != NULL) {
2961 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2962 }
2963 st->print(" [");
2964 st->print("%s", _get_thread_state_name(_thread_state));
2965 if (osthread()) {
2966 st->print(", id=%d", osthread()->thread_id());
2967 }
2968 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2969 p2i(stack_end()), p2i(stack_base()));
2970 st->print("]");
2971
2972 ThreadsSMRSupport::print_info_on(this, st);
2973 return;
2974 }
2975
2976 // Verification
2977
2978 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2979
2980 void JavaThread::verify() {
2981 // Verify oops in the thread.
2982 oops_do(&VerifyOopClosure::verify_oop, NULL);
2983
2984 // Verify the stack frames.
2985 frames_do(frame_verify);
2986 }
2987
2988 // CR 6300358 (sub-CR 2137150)
2989 // Most callers of this method assume that it can't return NULL but a
2990 // thread may not have a name whilst it is in the process of attaching to
2991 // the VM - see CR 6412693, and there are places where a JavaThread can be
2992 // seen prior to having it's threadObj set (eg JNI attaching threads and
2993 // if vm exit occurs during initialization). These cases can all be accounted
2994 // for such that this method never returns NULL.
2995 const char* JavaThread::get_thread_name() const {
2996 #ifdef ASSERT
2997 // early safepoints can hit while current thread does not yet have TLS
2998 if (!SafepointSynchronize::is_at_safepoint()) {
2999 Thread *cur = Thread::current();
3000 if (!(cur->is_Java_thread() && cur == this)) {
3001 // Current JavaThreads are allowed to get their own name without
3002 // the Threads_lock.
3003 assert_locked_or_safepoint(Threads_lock);
3004 }
3005 }
3006 #endif // ASSERT
3007 return get_thread_name_string();
3008 }
3009
3010 // Returns a non-NULL representation of this thread's name, or a suitable
3011 // descriptive string if there is no set name
3012 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3013 const char* name_str;
3014 oop thread_obj = threadObj();
3015 if (thread_obj != NULL) {
3016 oop name = java_lang_Thread::name(thread_obj);
3017 if (name != NULL) {
3018 if (buf == NULL) {
3019 name_str = java_lang_String::as_utf8_string(name);
3020 } else {
3021 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3022 }
3023 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3024 name_str = "<no-name - thread is attaching>";
3025 } else {
3026 name_str = Thread::name();
3027 }
3028 } else {
3029 name_str = Thread::name();
3030 }
3031 assert(name_str != NULL, "unexpected NULL thread name");
3032 return name_str;
3033 }
3034
3035
3036 const char* JavaThread::get_threadgroup_name() const {
3037 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3038 oop thread_obj = threadObj();
3039 if (thread_obj != NULL) {
3040 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3041 if (thread_group != NULL) {
3042 // ThreadGroup.name can be null
3043 return java_lang_ThreadGroup::name(thread_group);
3044 }
3045 }
3046 return NULL;
3047 }
3048
3049 const char* JavaThread::get_parent_name() const {
3050 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3051 oop thread_obj = threadObj();
3052 if (thread_obj != NULL) {
3053 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3054 if (thread_group != NULL) {
3055 oop parent = java_lang_ThreadGroup::parent(thread_group);
3056 if (parent != NULL) {
3057 // ThreadGroup.name can be null
3058 return java_lang_ThreadGroup::name(parent);
3059 }
3060 }
3061 }
3062 return NULL;
3063 }
3064
3065 ThreadPriority JavaThread::java_priority() const {
3066 oop thr_oop = threadObj();
3067 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3068 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3069 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3070 return priority;
3071 }
3072
3073 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3074
3075 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3076 // Link Java Thread object <-> C++ Thread
3077
3078 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3079 // and put it into a new Handle. The Handle "thread_oop" can then
3080 // be used to pass the C++ thread object to other methods.
3081
3082 // Set the Java level thread object (jthread) field of the
3083 // new thread (a JavaThread *) to C++ thread object using the
3084 // "thread_oop" handle.
3085
3086 // Set the thread field (a JavaThread *) of the
3087 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3088
3089 Handle thread_oop(Thread::current(),
3090 JNIHandles::resolve_non_null(jni_thread));
3091 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3092 "must be initialized");
3093 set_threadObj(thread_oop());
3094 java_lang_Thread::set_thread(thread_oop(), this);
3095
3096 if (prio == NoPriority) {
3097 prio = java_lang_Thread::priority(thread_oop());
3098 assert(prio != NoPriority, "A valid priority should be present");
3099 }
3100
3101 // Push the Java priority down to the native thread; needs Threads_lock
3102 Thread::set_priority(this, prio);
3103
3104 // Add the new thread to the Threads list and set it in motion.
3105 // We must have threads lock in order to call Threads::add.
3106 // It is crucial that we do not block before the thread is
3107 // added to the Threads list for if a GC happens, then the java_thread oop
3108 // will not be visited by GC.
3109 Threads::add(this);
3110 }
3111
3112 oop JavaThread::current_park_blocker() {
3113 // Support for JSR-166 locks
3114 oop thread_oop = threadObj();
3115 if (thread_oop != NULL &&
3116 JDK_Version::current().supports_thread_park_blocker()) {
3117 return java_lang_Thread::park_blocker(thread_oop);
3118 }
3119 return NULL;
3120 }
3121
3122
3123 void JavaThread::print_stack_on(outputStream* st) {
3124 if (!has_last_Java_frame()) return;
3125 ResourceMark rm;
3126 HandleMark hm;
3127
3128 RegisterMap reg_map(this);
3129 vframe* start_vf = last_java_vframe(®_map);
3130 int count = 0;
3131 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3132 if (f->is_java_frame()) {
3133 javaVFrame* jvf = javaVFrame::cast(f);
3134 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3135
3136 // Print out lock information
3137 if (JavaMonitorsInStackTrace) {
3138 jvf->print_lock_info_on(st, count);
3139 }
3140 } else {
3141 // Ignore non-Java frames
3142 }
3143
3144 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3145 count++;
3146 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3147 }
3148 }
3149
3150
3151 // JVMTI PopFrame support
3152 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3153 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3154 if (in_bytes(size_in_bytes) != 0) {
3155 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3156 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3157 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3158 }
3159 }
3160
3161 void* JavaThread::popframe_preserved_args() {
3162 return _popframe_preserved_args;
3163 }
3164
3165 ByteSize JavaThread::popframe_preserved_args_size() {
3166 return in_ByteSize(_popframe_preserved_args_size);
3167 }
3168
3169 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3170 int sz = in_bytes(popframe_preserved_args_size());
3171 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3172 return in_WordSize(sz / wordSize);
3173 }
3174
3175 void JavaThread::popframe_free_preserved_args() {
3176 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3177 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3178 _popframe_preserved_args = NULL;
3179 _popframe_preserved_args_size = 0;
3180 }
3181
3182 #ifndef PRODUCT
3183
3184 void JavaThread::trace_frames() {
3185 tty->print_cr("[Describe stack]");
3186 int frame_no = 1;
3187 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3188 tty->print(" %d. ", frame_no++);
3189 fst.current()->print_value_on(tty, this);
3190 tty->cr();
3191 }
3192 }
3193
3194 class PrintAndVerifyOopClosure: public OopClosure {
3195 protected:
3196 template <class T> inline void do_oop_work(T* p) {
3197 oop obj = RawAccess<>::oop_load(p);
3198 if (obj == NULL) return;
3199 tty->print(INTPTR_FORMAT ": ", p2i(p));
3200 if (oopDesc::is_oop_or_null(obj)) {
3201 if (obj->is_objArray()) {
3202 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3203 } else {
3204 obj->print();
3205 }
3206 } else {
3207 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3208 }
3209 tty->cr();
3210 }
3211 public:
3212 virtual void do_oop(oop* p) { do_oop_work(p); }
3213 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3214 };
3215
3216
3217 static void oops_print(frame* f, const RegisterMap *map) {
3218 PrintAndVerifyOopClosure print;
3219 f->print_value();
3220 f->oops_do(&print, NULL, (RegisterMap*)map);
3221 }
3222
3223 // Print our all the locations that contain oops and whether they are
3224 // valid or not. This useful when trying to find the oldest frame
3225 // where an oop has gone bad since the frame walk is from youngest to
3226 // oldest.
3227 void JavaThread::trace_oops() {
3228 tty->print_cr("[Trace oops]");
3229 frames_do(oops_print);
3230 }
3231
3232
3233 #ifdef ASSERT
3234 // Print or validate the layout of stack frames
3235 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3236 ResourceMark rm;
3237 PRESERVE_EXCEPTION_MARK;
3238 FrameValues values;
3239 int frame_no = 0;
3240 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3241 fst.current()->describe(values, ++frame_no);
3242 if (depth == frame_no) break;
3243 }
3244 if (validate_only) {
3245 values.validate();
3246 } else {
3247 tty->print_cr("[Describe stack layout]");
3248 values.print(this);
3249 }
3250 }
3251 #endif
3252
3253 void JavaThread::trace_stack_from(vframe* start_vf) {
3254 ResourceMark rm;
3255 int vframe_no = 1;
3256 for (vframe* f = start_vf; f; f = f->sender()) {
3257 if (f->is_java_frame()) {
3258 javaVFrame::cast(f)->print_activation(vframe_no++);
3259 } else {
3260 f->print();
3261 }
3262 if (vframe_no > StackPrintLimit) {
3263 tty->print_cr("...<more frames>...");
3264 return;
3265 }
3266 }
3267 }
3268
3269
3270 void JavaThread::trace_stack() {
3271 if (!has_last_Java_frame()) return;
3272 ResourceMark rm;
3273 HandleMark hm;
3274 RegisterMap reg_map(this);
3275 trace_stack_from(last_java_vframe(®_map));
3276 }
3277
3278
3279 #endif // PRODUCT
3280
3281
3282 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3283 assert(reg_map != NULL, "a map must be given");
3284 frame f = last_frame();
3285 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3286 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3287 }
3288 return NULL;
3289 }
3290
3291
3292 Klass* JavaThread::security_get_caller_class(int depth) {
3293 vframeStream vfst(this);
3294 vfst.security_get_caller_frame(depth);
3295 if (!vfst.at_end()) {
3296 return vfst.method()->method_holder();
3297 }
3298 return NULL;
3299 }
3300
3301 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3302 assert(thread->is_Compiler_thread(), "must be compiler thread");
3303 CompileBroker::compiler_thread_loop();
3304 }
3305
3306 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3307 NMethodSweeper::sweeper_loop();
3308 }
3309
3310 // Create a CompilerThread
3311 CompilerThread::CompilerThread(CompileQueue* queue,
3312 CompilerCounters* counters)
3313 : JavaThread(&compiler_thread_entry) {
3314 _env = NULL;
3315 _log = NULL;
3316 _task = NULL;
3317 _queue = queue;
3318 _counters = counters;
3319 _buffer_blob = NULL;
3320 _compiler = NULL;
3321
3322 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3323 resource_area()->bias_to(mtCompiler);
3324
3325 #ifndef PRODUCT
3326 _ideal_graph_printer = NULL;
3327 #endif
3328 }
3329
3330 CompilerThread::~CompilerThread() {
3331 // Delete objects which were allocated on heap.
3332 delete _counters;
3333 }
3334
3335 bool CompilerThread::can_call_java() const {
3336 return _compiler != NULL && _compiler->is_jvmci();
3337 }
3338
3339 // Create sweeper thread
3340 CodeCacheSweeperThread::CodeCacheSweeperThread()
3341 : JavaThread(&sweeper_thread_entry) {
3342 _scanned_compiled_method = NULL;
3343 }
3344
3345 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3346 JavaThread::oops_do(f, cf);
3347 if (_scanned_compiled_method != NULL && cf != NULL) {
3348 // Safepoints can occur when the sweeper is scanning an nmethod so
3349 // process it here to make sure it isn't unloaded in the middle of
3350 // a scan.
3351 cf->do_code_blob(_scanned_compiled_method);
3352 }
3353 }
3354
3355 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3356 JavaThread::nmethods_do(cf);
3357 if (_scanned_compiled_method != NULL && cf != NULL) {
3358 // Safepoints can occur when the sweeper is scanning an nmethod so
3359 // process it here to make sure it isn't unloaded in the middle of
3360 // a scan.
3361 cf->do_code_blob(_scanned_compiled_method);
3362 }
3363 }
3364
3365
3366 // ======= Threads ========
3367
3368 // The Threads class links together all active threads, and provides
3369 // operations over all threads. It is protected by the Threads_lock,
3370 // which is also used in other global contexts like safepointing.
3371 // ThreadsListHandles are used to safely perform operations on one
3372 // or more threads without the risk of the thread exiting during the
3373 // operation.
3374 //
3375 // Note: The Threads_lock is currently more widely used than we
3376 // would like. We are actively migrating Threads_lock uses to other
3377 // mechanisms in order to reduce Threads_lock contention.
3378
3379 JavaThread* Threads::_thread_list = NULL;
3380 int Threads::_number_of_threads = 0;
3381 int Threads::_number_of_non_daemon_threads = 0;
3382 int Threads::_return_code = 0;
3383 int Threads::_thread_claim_parity = 0;
3384 size_t JavaThread::_stack_size_at_create = 0;
3385
3386 #ifdef ASSERT
3387 bool Threads::_vm_complete = false;
3388 #endif
3389
3390 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3391 Prefetch::read((void*)addr, prefetch_interval);
3392 return *addr;
3393 }
3394
3395 // Possibly the ugliest for loop the world has seen. C++ does not allow
3396 // multiple types in the declaration section of the for loop. In this case
3397 // we are only dealing with pointers and hence can cast them. It looks ugly
3398 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3399 #define DO_JAVA_THREADS(LIST, X) \
3400 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3401 *MACRO_list = (JavaThread*)(LIST), \
3402 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3403 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3404 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3405 MACRO_current_p != MACRO_end; \
3406 MACRO_current_p++, \
3407 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3408
3409 // All JavaThreads
3410 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3411
3412 // All non-JavaThreads (i.e., every non-JavaThread in the system).
3413 void Threads::non_java_threads_do(ThreadClosure* tc) {
3414 // Someday we could have a table or list of all non-JavaThreads.
3415 // For now, just manually iterate through them.
3416 tc->do_thread(VMThread::vm_thread());
3417 if (Universe::heap() != NULL) {
3418 Universe::heap()->gc_threads_do(tc);
3419 }
3420 WatcherThread *wt = WatcherThread::watcher_thread();
3421 // Strictly speaking, the following NULL check isn't sufficient to make sure
3422 // the data for WatcherThread is still valid upon being examined. However,
3423 // considering that WatchThread terminates when the VM is on the way to
3424 // exit at safepoint, the chance of the above is extremely small. The right
3425 // way to prevent termination of WatcherThread would be to acquire
3426 // Terminator_lock, but we can't do that without violating the lock rank
3427 // checking in some cases.
3428 if (wt != NULL) {
3429 tc->do_thread(wt);
3430 }
3431
3432 #if INCLUDE_JFR
3433 Thread* sampler_thread = Jfr::sampler_thread();
3434 if (sampler_thread != NULL) {
3435 tc->do_thread(sampler_thread);
3436 }
3437
3438 #endif
3439
3440 // If CompilerThreads ever become non-JavaThreads, add them here
3441 }
3442
3443 // All JavaThreads
3444 void Threads::java_threads_do(ThreadClosure* tc) {
3445 assert_locked_or_safepoint(Threads_lock);
3446 // ALL_JAVA_THREADS iterates through all JavaThreads.
3447 ALL_JAVA_THREADS(p) {
3448 tc->do_thread(p);
3449 }
3450 }
3451
3452 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3453 assert_locked_or_safepoint(Threads_lock);
3454 java_threads_do(tc);
3455 tc->do_thread(VMThread::vm_thread());
3456 }
3457
3458 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3459 void Threads::threads_do(ThreadClosure* tc) {
3460 assert_locked_or_safepoint(Threads_lock);
3461 java_threads_do(tc);
3462 non_java_threads_do(tc);
3463 }
3464
3465 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3466 int cp = Threads::thread_claim_parity();
3467 ALL_JAVA_THREADS(p) {
3468 if (p->claim_oops_do(is_par, cp)) {
3469 tc->do_thread(p);
3470 }
3471 }
3472 VMThread* vmt = VMThread::vm_thread();
3473 if (vmt->claim_oops_do(is_par, cp)) {
3474 tc->do_thread(vmt);
3475 }
3476 }
3477
3478 // The system initialization in the library has three phases.
3479 //
3480 // Phase 1: java.lang.System class initialization
3481 // java.lang.System is a primordial class loaded and initialized
3482 // by the VM early during startup. java.lang.System.<clinit>
3483 // only does registerNatives and keeps the rest of the class
3484 // initialization work later until thread initialization completes.
3485 //
3486 // System.initPhase1 initializes the system properties, the static
3487 // fields in, out, and err. Set up java signal handlers, OS-specific
3488 // system settings, and thread group of the main thread.
3489 static void call_initPhase1(TRAPS) {
3490 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3491 JavaValue result(T_VOID);
3492 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3493 vmSymbols::void_method_signature(), CHECK);
3494 }
3495
3496 // Phase 2. Module system initialization
3497 // This will initialize the module system. Only java.base classes
3498 // can be loaded until phase 2 completes.
3499 //
3500 // Call System.initPhase2 after the compiler initialization and jsr292
3501 // classes get initialized because module initialization runs a lot of java
3502 // code, that for performance reasons, should be compiled. Also, this will
3503 // enable the startup code to use lambda and other language features in this
3504 // phase and onward.
3505 //
3506 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3507 static void call_initPhase2(TRAPS) {
3508 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3509
3510 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3511
3512 JavaValue result(T_INT);
3513 JavaCallArguments args;
3514 args.push_int(DisplayVMOutputToStderr);
3515 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3516 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3517 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3518 if (result.get_jint() != JNI_OK) {
3519 vm_exit_during_initialization(); // no message or exception
3520 }
3521
3522 universe_post_module_init();
3523 }
3524
3525 // Phase 3. final setup - set security manager, system class loader and TCCL
3526 //
3527 // This will instantiate and set the security manager, set the system class
3528 // loader as well as the thread context class loader. The security manager
3529 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3530 // other modules or the application's classpath.
3531 static void call_initPhase3(TRAPS) {
3532 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3533 JavaValue result(T_VOID);
3534 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3535 vmSymbols::void_method_signature(), CHECK);
3536 }
3537
3538 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3539 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3540
3541 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3542 create_vm_init_libraries();
3543 }
3544
3545 initialize_class(vmSymbols::java_lang_String(), CHECK);
3546
3547 // Inject CompactStrings value after the static initializers for String ran.
3548 java_lang_String::set_compact_strings(CompactStrings);
3549
3550 // Initialize java_lang.System (needed before creating the thread)
3551 initialize_class(vmSymbols::java_lang_System(), CHECK);
3552 // The VM creates & returns objects of this class. Make sure it's initialized.
3553 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3554 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3555 Handle thread_group = create_initial_thread_group(CHECK);
3556 Universe::set_main_thread_group(thread_group());
3557 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3558 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3559 main_thread->set_threadObj(thread_object);
3560 // Set thread status to running since main thread has
3561 // been started and running.
3562 java_lang_Thread::set_thread_status(thread_object,
3563 java_lang_Thread::RUNNABLE);
3564
3565 // The VM creates objects of this class.
3566 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3567
3568 // The VM preresolves methods to these classes. Make sure that they get initialized
3569 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3570 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3571
3572 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3573 call_initPhase1(CHECK);
3574
3575 // get the Java runtime name after java.lang.System is initialized
3576 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3577 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3578
3579 // an instance of OutOfMemory exception has been allocated earlier
3580 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3581 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3582 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3583 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3584 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3585 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3586 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3587 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3588 }
3589
3590 void Threads::initialize_jsr292_core_classes(TRAPS) {
3591 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3592
3593 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3594 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3595 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3596 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3597 }
3598
3599 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3600 extern void JDK_Version_init();
3601
3602 // Preinitialize version info.
3603 VM_Version::early_initialize();
3604
3605 // Check version
3606 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3607
3608 // Initialize library-based TLS
3609 ThreadLocalStorage::init();
3610
3611 // Initialize the output stream module
3612 ostream_init();
3613
3614 // Process java launcher properties.
3615 Arguments::process_sun_java_launcher_properties(args);
3616
3617 // Initialize the os module
3618 os::init();
3619
3620 // Record VM creation timing statistics
3621 TraceVmCreationTime create_vm_timer;
3622 create_vm_timer.start();
3623
3624 // Initialize system properties.
3625 Arguments::init_system_properties();
3626
3627 // So that JDK version can be used as a discriminator when parsing arguments
3628 JDK_Version_init();
3629
3630 // Update/Initialize System properties after JDK version number is known
3631 Arguments::init_version_specific_system_properties();
3632
3633 // Make sure to initialize log configuration *before* parsing arguments
3634 LogConfiguration::initialize(create_vm_timer.begin_time());
3635
3636 // Parse arguments
3637 // Note: this internally calls os::init_container_support()
3638 jint parse_result = Arguments::parse(args);
3639 if (parse_result != JNI_OK) return parse_result;
3640
3641 os::init_before_ergo();
3642
3643 jint ergo_result = Arguments::apply_ergo();
3644 if (ergo_result != JNI_OK) return ergo_result;
3645
3646 // Final check of all ranges after ergonomics which may change values.
3647 if (!JVMFlagRangeList::check_ranges()) {
3648 return JNI_EINVAL;
3649 }
3650
3651 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3652 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3653 if (!constraint_result) {
3654 return JNI_EINVAL;
3655 }
3656
3657 JVMFlagWriteableList::mark_startup();
3658
3659 if (PauseAtStartup) {
3660 os::pause();
3661 }
3662
3663 HOTSPOT_VM_INIT_BEGIN();
3664
3665 // Timing (must come after argument parsing)
3666 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3667
3668 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3669 // Initialize assert poison page mechanism.
3670 if (ShowRegistersOnAssert) {
3671 initialize_assert_poison();
3672 }
3673 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3674
3675 // Initialize the os module after parsing the args
3676 jint os_init_2_result = os::init_2();
3677 if (os_init_2_result != JNI_OK) return os_init_2_result;
3678
3679 SafepointMechanism::initialize();
3680
3681 jint adjust_after_os_result = Arguments::adjust_after_os();
3682 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3683
3684 // Initialize output stream logging
3685 ostream_init_log();
3686
3687 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3688 // Must be before create_vm_init_agents()
3689 if (Arguments::init_libraries_at_startup()) {
3690 convert_vm_init_libraries_to_agents();
3691 }
3692
3693 // Launch -agentlib/-agentpath and converted -Xrun agents
3694 if (Arguments::init_agents_at_startup()) {
3695 create_vm_init_agents();
3696 }
3697
3698 // Initialize Threads state
3699 _thread_list = NULL;
3700 _number_of_threads = 0;
3701 _number_of_non_daemon_threads = 0;
3702
3703 // Initialize global data structures and create system classes in heap
3704 vm_init_globals();
3705
3706 #if INCLUDE_JVMCI
3707 if (JVMCICounterSize > 0) {
3708 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3709 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3710 } else {
3711 JavaThread::_jvmci_old_thread_counters = NULL;
3712 }
3713 #endif // INCLUDE_JVMCI
3714
3715 // Attach the main thread to this os thread
3716 JavaThread* main_thread = new JavaThread();
3717 main_thread->set_thread_state(_thread_in_vm);
3718 main_thread->initialize_thread_current();
3719 // must do this before set_active_handles
3720 main_thread->record_stack_base_and_size();
3721 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3722
3723 if (!main_thread->set_as_starting_thread()) {
3724 vm_shutdown_during_initialization(
3725 "Failed necessary internal allocation. Out of swap space");
3726 main_thread->smr_delete();
3727 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3728 return JNI_ENOMEM;
3729 }
3730
3731 // Enable guard page *after* os::create_main_thread(), otherwise it would
3732 // crash Linux VM, see notes in os_linux.cpp.
3733 main_thread->create_stack_guard_pages();
3734
3735 // Initialize Java-Level synchronization subsystem
3736 ObjectMonitor::Initialize();
3737
3738 // Initialize global modules
3739 jint status = init_globals();
3740 if (status != JNI_OK) {
3741 main_thread->smr_delete();
3742 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3743 return status;
3744 }
3745
3746 JFR_ONLY(Jfr::on_vm_init();)
3747
3748 // Should be done after the heap is fully created
3749 main_thread->cache_global_variables();
3750
3751 HandleMark hm;
3752
3753 { MutexLocker mu(Threads_lock);
3754 Threads::add(main_thread);
3755 }
3756
3757 // Any JVMTI raw monitors entered in onload will transition into
3758 // real raw monitor. VM is setup enough here for raw monitor enter.
3759 JvmtiExport::transition_pending_onload_raw_monitors();
3760
3761 // Create the VMThread
3762 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3763
3764 VMThread::create();
3765 Thread* vmthread = VMThread::vm_thread();
3766
3767 if (!os::create_thread(vmthread, os::vm_thread)) {
3768 vm_exit_during_initialization("Cannot create VM thread. "
3769 "Out of system resources.");
3770 }
3771
3772 // Wait for the VM thread to become ready, and VMThread::run to initialize
3773 // Monitors can have spurious returns, must always check another state flag
3774 {
3775 MutexLocker ml(Notify_lock);
3776 os::start_thread(vmthread);
3777 while (vmthread->active_handles() == NULL) {
3778 Notify_lock->wait();
3779 }
3780 }
3781 }
3782
3783 assert(Universe::is_fully_initialized(), "not initialized");
3784 if (VerifyDuringStartup) {
3785 // Make sure we're starting with a clean slate.
3786 VM_Verify verify_op;
3787 VMThread::execute(&verify_op);
3788 }
3789
3790 Thread* THREAD = Thread::current();
3791
3792 // Always call even when there are not JVMTI environments yet, since environments
3793 // may be attached late and JVMTI must track phases of VM execution
3794 JvmtiExport::enter_early_start_phase();
3795
3796 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3797 JvmtiExport::post_early_vm_start();
3798
3799 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3800
3801 // We need this to update the java.vm.info property in case any flags used
3802 // to initially define it have been changed. This is needed for both CDS and
3803 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3804 // is initially computed. See Abstract_VM_Version::vm_info_string().
3805 reset_vm_info_property(CHECK_JNI_ERR);
3806
3807 quicken_jni_functions();
3808
3809 // No more stub generation allowed after that point.
3810 StubCodeDesc::freeze();
3811
3812 // Set flag that basic initialization has completed. Used by exceptions and various
3813 // debug stuff, that does not work until all basic classes have been initialized.
3814 set_init_completed();
3815
3816 LogConfiguration::post_initialize();
3817 Metaspace::post_initialize();
3818
3819 HOTSPOT_VM_INIT_END();
3820
3821 // record VM initialization completion time
3822 #if INCLUDE_MANAGEMENT
3823 Management::record_vm_init_completed();
3824 #endif // INCLUDE_MANAGEMENT
3825
3826 // Signal Dispatcher needs to be started before VMInit event is posted
3827 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3828
3829 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3830 if (!DisableAttachMechanism) {
3831 AttachListener::vm_start();
3832 if (StartAttachListener || AttachListener::init_at_startup()) {
3833 AttachListener::init();
3834 }
3835 }
3836
3837 // Launch -Xrun agents
3838 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3839 // back-end can launch with -Xdebug -Xrunjdwp.
3840 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3841 create_vm_init_libraries();
3842 }
3843
3844 if (CleanChunkPoolAsync) {
3845 Chunk::start_chunk_pool_cleaner_task();
3846 }
3847
3848 // initialize compiler(s)
3849 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3850 #if INCLUDE_JVMCI
3851 bool force_JVMCI_intialization = false;
3852 if (EnableJVMCI) {
3853 // Initialize JVMCI eagerly when it is explicitly requested.
3854 // Or when JVMCIPrintProperties is enabled.
3855 // The JVMCI Java initialization code will read this flag and
3856 // do the printing if it's set.
3857 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3858
3859 if (!force_JVMCI_intialization) {
3860 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3861 // compilations via JVMCI will not actually block until JVMCI is initialized.
3862 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3863 }
3864 }
3865 #endif
3866 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3867 // Postpone completion of compiler initialization to after JVMCI
3868 // is initialized to avoid timeouts of blocking compilations.
3869 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3870 CompileBroker::compilation_init_phase2();
3871 }
3872 #endif
3873
3874 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3875 // It is done after compilers are initialized, because otherwise compilations of
3876 // signature polymorphic MH intrinsics can be missed
3877 // (see SystemDictionary::find_method_handle_intrinsic).
3878 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3879
3880 // This will initialize the module system. Only java.base classes can be
3881 // loaded until phase 2 completes
3882 call_initPhase2(CHECK_JNI_ERR);
3883
3884 // Always call even when there are not JVMTI environments yet, since environments
3885 // may be attached late and JVMTI must track phases of VM execution
3886 JvmtiExport::enter_start_phase();
3887
3888 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3889 JvmtiExport::post_vm_start();
3890
3891 // Final system initialization including security manager and system class loader
3892 call_initPhase3(CHECK_JNI_ERR);
3893
3894 // cache the system and platform class loaders
3895 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3896
3897 #if INCLUDE_CDS
3898 if (DumpSharedSpaces) {
3899 // capture the module path info from the ModuleEntryTable
3900 ClassLoader::initialize_module_path(THREAD);
3901 }
3902 #endif
3903
3904 #if INCLUDE_JVMCI
3905 if (force_JVMCI_intialization) {
3906 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3907 CompileBroker::compilation_init_phase2();
3908 }
3909 #endif
3910
3911 // Always call even when there are not JVMTI environments yet, since environments
3912 // may be attached late and JVMTI must track phases of VM execution
3913 JvmtiExport::enter_live_phase();
3914
3915 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3916 JvmtiExport::post_vm_initialized();
3917
3918 JFR_ONLY(Jfr::on_vm_start();)
3919
3920 #if INCLUDE_MANAGEMENT
3921 Management::initialize(THREAD);
3922
3923 if (HAS_PENDING_EXCEPTION) {
3924 // management agent fails to start possibly due to
3925 // configuration problem and is responsible for printing
3926 // stack trace if appropriate. Simply exit VM.
3927 vm_exit(1);
3928 }
3929 #endif // INCLUDE_MANAGEMENT
3930
3931 if (MemProfiling) MemProfiler::engage();
3932 StatSampler::engage();
3933 if (CheckJNICalls) JniPeriodicChecker::engage();
3934
3935 BiasedLocking::init();
3936
3937 #if INCLUDE_RTM_OPT
3938 RTMLockingCounters::init();
3939 #endif
3940
3941 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3942 call_postVMInitHook(THREAD);
3943 // The Java side of PostVMInitHook.run must deal with all
3944 // exceptions and provide means of diagnosis.
3945 if (HAS_PENDING_EXCEPTION) {
3946 CLEAR_PENDING_EXCEPTION;
3947 }
3948 }
3949
3950 {
3951 MutexLocker ml(PeriodicTask_lock);
3952 // Make sure the WatcherThread can be started by WatcherThread::start()
3953 // or by dynamic enrollment.
3954 WatcherThread::make_startable();
3955 // Start up the WatcherThread if there are any periodic tasks
3956 // NOTE: All PeriodicTasks should be registered by now. If they
3957 // aren't, late joiners might appear to start slowly (we might
3958 // take a while to process their first tick).
3959 if (PeriodicTask::num_tasks() > 0) {
3960 WatcherThread::start();
3961 }
3962 }
3963
3964 create_vm_timer.end();
3965 #ifdef ASSERT
3966 _vm_complete = true;
3967 #endif
3968
3969 if (DumpSharedSpaces) {
3970 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3971 ShouldNotReachHere();
3972 }
3973
3974 return JNI_OK;
3975 }
3976
3977 // type for the Agent_OnLoad and JVM_OnLoad entry points
3978 extern "C" {
3979 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3980 }
3981 // Find a command line agent library and return its entry point for
3982 // -agentlib: -agentpath: -Xrun
3983 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3984 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3985 const char *on_load_symbols[],
3986 size_t num_symbol_entries) {
3987 OnLoadEntry_t on_load_entry = NULL;
3988 void *library = NULL;
3989
3990 if (!agent->valid()) {
3991 char buffer[JVM_MAXPATHLEN];
3992 char ebuf[1024] = "";
3993 const char *name = agent->name();
3994 const char *msg = "Could not find agent library ";
3995
3996 // First check to see if agent is statically linked into executable
3997 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3998 library = agent->os_lib();
3999 } else if (agent->is_absolute_path()) {
4000 library = os::dll_load(name, ebuf, sizeof ebuf);
4001 if (library == NULL) {
4002 const char *sub_msg = " in absolute path, with error: ";
4003 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4004 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4005 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4006 // If we can't find the agent, exit.
4007 vm_exit_during_initialization(buf, NULL);
4008 FREE_C_HEAP_ARRAY(char, buf);
4009 }
4010 } else {
4011 // Try to load the agent from the standard dll directory
4012 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4013 name)) {
4014 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4015 }
4016 if (library == NULL) { // Try the library path directory.
4017 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4018 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4019 }
4020 if (library == NULL) {
4021 const char *sub_msg = " on the library path, with error: ";
4022 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4023
4024 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4025 strlen(ebuf) + strlen(sub_msg2) + 1;
4026 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4027 if (!agent->is_instrument_lib()) {
4028 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4029 } else {
4030 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4031 }
4032 // If we can't find the agent, exit.
4033 vm_exit_during_initialization(buf, NULL);
4034 FREE_C_HEAP_ARRAY(char, buf);
4035 }
4036 }
4037 }
4038 agent->set_os_lib(library);
4039 agent->set_valid();
4040 }
4041
4042 // Find the OnLoad function.
4043 on_load_entry =
4044 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4045 false,
4046 on_load_symbols,
4047 num_symbol_entries));
4048 return on_load_entry;
4049 }
4050
4051 // Find the JVM_OnLoad entry point
4052 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4053 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4054 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4055 }
4056
4057 // Find the Agent_OnLoad entry point
4058 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4059 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4060 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4061 }
4062
4063 // For backwards compatibility with -Xrun
4064 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4065 // treated like -agentpath:
4066 // Must be called before agent libraries are created
4067 void Threads::convert_vm_init_libraries_to_agents() {
4068 AgentLibrary* agent;
4069 AgentLibrary* next;
4070
4071 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4072 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4073 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4074
4075 // If there is an JVM_OnLoad function it will get called later,
4076 // otherwise see if there is an Agent_OnLoad
4077 if (on_load_entry == NULL) {
4078 on_load_entry = lookup_agent_on_load(agent);
4079 if (on_load_entry != NULL) {
4080 // switch it to the agent list -- so that Agent_OnLoad will be called,
4081 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4082 Arguments::convert_library_to_agent(agent);
4083 } else {
4084 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4085 }
4086 }
4087 }
4088 }
4089
4090 // Create agents for -agentlib: -agentpath: and converted -Xrun
4091 // Invokes Agent_OnLoad
4092 // Called very early -- before JavaThreads exist
4093 void Threads::create_vm_init_agents() {
4094 extern struct JavaVM_ main_vm;
4095 AgentLibrary* agent;
4096
4097 JvmtiExport::enter_onload_phase();
4098
4099 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4100 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4101
4102 if (on_load_entry != NULL) {
4103 // Invoke the Agent_OnLoad function
4104 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4105 if (err != JNI_OK) {
4106 vm_exit_during_initialization("agent library failed to init", agent->name());
4107 }
4108 } else {
4109 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4110 }
4111 }
4112 JvmtiExport::enter_primordial_phase();
4113 }
4114
4115 extern "C" {
4116 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4117 }
4118
4119 void Threads::shutdown_vm_agents() {
4120 // Send any Agent_OnUnload notifications
4121 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4122 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4123 extern struct JavaVM_ main_vm;
4124 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4125
4126 // Find the Agent_OnUnload function.
4127 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4128 os::find_agent_function(agent,
4129 false,
4130 on_unload_symbols,
4131 num_symbol_entries));
4132
4133 // Invoke the Agent_OnUnload function
4134 if (unload_entry != NULL) {
4135 JavaThread* thread = JavaThread::current();
4136 ThreadToNativeFromVM ttn(thread);
4137 HandleMark hm(thread);
4138 (*unload_entry)(&main_vm);
4139 }
4140 }
4141 }
4142
4143 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4144 // Invokes JVM_OnLoad
4145 void Threads::create_vm_init_libraries() {
4146 extern struct JavaVM_ main_vm;
4147 AgentLibrary* agent;
4148
4149 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4150 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4151
4152 if (on_load_entry != NULL) {
4153 // Invoke the JVM_OnLoad function
4154 JavaThread* thread = JavaThread::current();
4155 ThreadToNativeFromVM ttn(thread);
4156 HandleMark hm(thread);
4157 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4158 if (err != JNI_OK) {
4159 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4160 }
4161 } else {
4162 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4163 }
4164 }
4165 }
4166
4167
4168 // Last thread running calls java.lang.Shutdown.shutdown()
4169 void JavaThread::invoke_shutdown_hooks() {
4170 HandleMark hm(this);
4171
4172 // We could get here with a pending exception, if so clear it now.
4173 if (this->has_pending_exception()) {
4174 this->clear_pending_exception();
4175 }
4176
4177 EXCEPTION_MARK;
4178 Klass* shutdown_klass =
4179 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4180 THREAD);
4181 if (shutdown_klass != NULL) {
4182 // SystemDictionary::resolve_or_null will return null if there was
4183 // an exception. If we cannot load the Shutdown class, just don't
4184 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4185 // won't be run. Note that if a shutdown hook was registered,
4186 // the Shutdown class would have already been loaded
4187 // (Runtime.addShutdownHook will load it).
4188 JavaValue result(T_VOID);
4189 JavaCalls::call_static(&result,
4190 shutdown_klass,
4191 vmSymbols::shutdown_method_name(),
4192 vmSymbols::void_method_signature(),
4193 THREAD);
4194 }
4195 CLEAR_PENDING_EXCEPTION;
4196 }
4197
4198 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4199 // the program falls off the end of main(). Another VM exit path is through
4200 // vm_exit() when the program calls System.exit() to return a value or when
4201 // there is a serious error in VM. The two shutdown paths are not exactly
4202 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4203 // and VM_Exit op at VM level.
4204 //
4205 // Shutdown sequence:
4206 // + Shutdown native memory tracking if it is on
4207 // + Wait until we are the last non-daemon thread to execute
4208 // <-- every thing is still working at this moment -->
4209 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4210 // shutdown hooks
4211 // + Call before_exit(), prepare for VM exit
4212 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4213 // currently the only user of this mechanism is File.deleteOnExit())
4214 // > stop StatSampler, watcher thread, CMS threads,
4215 // post thread end and vm death events to JVMTI,
4216 // stop signal thread
4217 // + Call JavaThread::exit(), it will:
4218 // > release JNI handle blocks, remove stack guard pages
4219 // > remove this thread from Threads list
4220 // <-- no more Java code from this thread after this point -->
4221 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4222 // the compiler threads at safepoint
4223 // <-- do not use anything that could get blocked by Safepoint -->
4224 // + Disable tracing at JNI/JVM barriers
4225 // + Set _vm_exited flag for threads that are still running native code
4226 // + Delete this thread
4227 // + Call exit_globals()
4228 // > deletes tty
4229 // > deletes PerfMemory resources
4230 // + Return to caller
4231
4232 bool Threads::destroy_vm() {
4233 JavaThread* thread = JavaThread::current();
4234
4235 #ifdef ASSERT
4236 _vm_complete = false;
4237 #endif
4238 // Wait until we are the last non-daemon thread to execute
4239 { MutexLocker nu(Threads_lock);
4240 while (Threads::number_of_non_daemon_threads() > 1)
4241 // This wait should make safepoint checks, wait without a timeout,
4242 // and wait as a suspend-equivalent condition.
4243 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4244 Mutex::_as_suspend_equivalent_flag);
4245 }
4246
4247 EventShutdown e;
4248 if (e.should_commit()) {
4249 e.set_reason("No remaining non-daemon Java threads");
4250 e.commit();
4251 }
4252
4253 // Hang forever on exit if we are reporting an error.
4254 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4255 os::infinite_sleep();
4256 }
4257 os::wait_for_keypress_at_exit();
4258
4259 // run Java level shutdown hooks
4260 thread->invoke_shutdown_hooks();
4261
4262 before_exit(thread);
4263
4264 thread->exit(true);
4265
4266 // Stop VM thread.
4267 {
4268 // 4945125 The vm thread comes to a safepoint during exit.
4269 // GC vm_operations can get caught at the safepoint, and the
4270 // heap is unparseable if they are caught. Grab the Heap_lock
4271 // to prevent this. The GC vm_operations will not be able to
4272 // queue until after the vm thread is dead. After this point,
4273 // we'll never emerge out of the safepoint before the VM exits.
4274
4275 MutexLocker ml(Heap_lock);
4276
4277 VMThread::wait_for_vm_thread_exit();
4278 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4279 VMThread::destroy();
4280 }
4281
4282 // Now, all Java threads are gone except daemon threads. Daemon threads
4283 // running Java code or in VM are stopped by the Safepoint. However,
4284 // daemon threads executing native code are still running. But they
4285 // will be stopped at native=>Java/VM barriers. Note that we can't
4286 // simply kill or suspend them, as it is inherently deadlock-prone.
4287
4288 VM_Exit::set_vm_exited();
4289
4290 // Clean up ideal graph printers after the VMThread has started
4291 // the final safepoint which will block all the Compiler threads.
4292 // Note that this Thread has already logically exited so the
4293 // clean_up() function's use of a JavaThreadIteratorWithHandle
4294 // would be a problem except set_vm_exited() has remembered the
4295 // shutdown thread which is granted a policy exception.
4296 #if defined(COMPILER2) && !defined(PRODUCT)
4297 IdealGraphPrinter::clean_up();
4298 #endif
4299
4300 notify_vm_shutdown();
4301
4302 // We are after VM_Exit::set_vm_exited() so we can't call
4303 // thread->smr_delete() or we will block on the Threads_lock.
4304 // Deleting the shutdown thread here is safe because another
4305 // JavaThread cannot have an active ThreadsListHandle for
4306 // this JavaThread.
4307 delete thread;
4308
4309 #if INCLUDE_JVMCI
4310 if (JVMCICounterSize > 0) {
4311 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4312 }
4313 #endif
4314
4315 // exit_globals() will delete tty
4316 exit_globals();
4317
4318 LogConfiguration::finalize();
4319
4320 return true;
4321 }
4322
4323
4324 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4325 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4326 return is_supported_jni_version(version);
4327 }
4328
4329
4330 jboolean Threads::is_supported_jni_version(jint version) {
4331 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4332 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4333 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4334 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4335 if (version == JNI_VERSION_9) return JNI_TRUE;
4336 if (version == JNI_VERSION_10) return JNI_TRUE;
4337 return JNI_FALSE;
4338 }
4339
4340
4341 void Threads::add(JavaThread* p, bool force_daemon) {
4342 // The threads lock must be owned at this point
4343 assert_locked_or_safepoint(Threads_lock);
4344
4345 BarrierSet::barrier_set()->on_thread_attach(p);
4346
4347 p->set_next(_thread_list);
4348 _thread_list = p;
4349
4350 // Once a JavaThread is added to the Threads list, smr_delete() has
4351 // to be used to delete it. Otherwise we can just delete it directly.
4352 p->set_on_thread_list();
4353
4354 _number_of_threads++;
4355 oop threadObj = p->threadObj();
4356 bool daemon = true;
4357 // Bootstrapping problem: threadObj can be null for initial
4358 // JavaThread (or for threads attached via JNI)
4359 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4360 _number_of_non_daemon_threads++;
4361 daemon = false;
4362 }
4363
4364 ThreadService::add_thread(p, daemon);
4365
4366 // Maintain fast thread list
4367 ThreadsSMRSupport::add_thread(p);
4368
4369 // Possible GC point.
4370 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4371 }
4372
4373 void Threads::remove(JavaThread* p) {
4374
4375 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4376 ObjectSynchronizer::omFlush(p);
4377
4378 // Extra scope needed for Thread_lock, so we can check
4379 // that we do not remove thread without safepoint code notice
4380 { MutexLocker ml(Threads_lock);
4381
4382 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4383
4384 // Maintain fast thread list
4385 ThreadsSMRSupport::remove_thread(p);
4386
4387 JavaThread* current = _thread_list;
4388 JavaThread* prev = NULL;
4389
4390 while (current != p) {
4391 prev = current;
4392 current = current->next();
4393 }
4394
4395 if (prev) {
4396 prev->set_next(current->next());
4397 } else {
4398 _thread_list = p->next();
4399 }
4400
4401 _number_of_threads--;
4402 oop threadObj = p->threadObj();
4403 bool daemon = true;
4404 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4405 _number_of_non_daemon_threads--;
4406 daemon = false;
4407
4408 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4409 // on destroy_vm will wake up.
4410 if (number_of_non_daemon_threads() == 1) {
4411 Threads_lock->notify_all();
4412 }
4413 }
4414 ThreadService::remove_thread(p, daemon);
4415
4416 // Make sure that safepoint code disregard this thread. This is needed since
4417 // the thread might mess around with locks after this point. This can cause it
4418 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4419 // of this thread since it is removed from the queue.
4420 p->set_terminated_value();
4421 } // unlock Threads_lock
4422
4423 // Since Events::log uses a lock, we grab it outside the Threads_lock
4424 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4425 }
4426
4427 // Operations on the Threads list for GC. These are not explicitly locked,
4428 // but the garbage collector must provide a safe context for them to run.
4429 // In particular, these things should never be called when the Threads_lock
4430 // is held by some other thread. (Note: the Safepoint abstraction also
4431 // uses the Threads_lock to guarantee this property. It also makes sure that
4432 // all threads gets blocked when exiting or starting).
4433
4434 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4435 ALL_JAVA_THREADS(p) {
4436 p->oops_do(f, cf);
4437 }
4438 VMThread::vm_thread()->oops_do(f, cf);
4439 }
4440
4441 void Threads::change_thread_claim_parity() {
4442 // Set the new claim parity.
4443 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4444 "Not in range.");
4445 _thread_claim_parity++;
4446 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4447 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4448 "Not in range.");
4449 }
4450
4451 #ifdef ASSERT
4452 void Threads::assert_all_threads_claimed() {
4453 ALL_JAVA_THREADS(p) {
4454 const int thread_parity = p->oops_do_parity();
4455 assert((thread_parity == _thread_claim_parity),
4456 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4457 }
4458 VMThread* vmt = VMThread::vm_thread();
4459 const int thread_parity = vmt->oops_do_parity();
4460 assert((thread_parity == _thread_claim_parity),
4461 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4462 }
4463 #endif // ASSERT
4464
4465 class ParallelOopsDoThreadClosure : public ThreadClosure {
4466 private:
4467 OopClosure* _f;
4468 CodeBlobClosure* _cf;
4469 public:
4470 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4471 void do_thread(Thread* t) {
4472 t->oops_do(_f, _cf);
4473 }
4474 };
4475
4476 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4477 ParallelOopsDoThreadClosure tc(f, cf);
4478 possibly_parallel_threads_do(is_par, &tc);
4479 }
4480
4481 void Threads::nmethods_do(CodeBlobClosure* cf) {
4482 ALL_JAVA_THREADS(p) {
4483 // This is used by the code cache sweeper to mark nmethods that are active
4484 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4485 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4486 if(!p->is_Code_cache_sweeper_thread()) {
4487 p->nmethods_do(cf);
4488 }
4489 }
4490 }
4491
4492 void Threads::metadata_do(void f(Metadata*)) {
4493 ALL_JAVA_THREADS(p) {
4494 p->metadata_do(f);
4495 }
4496 }
4497
4498 class ThreadHandlesClosure : public ThreadClosure {
4499 void (*_f)(Metadata*);
4500 public:
4501 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4502 virtual void do_thread(Thread* thread) {
4503 thread->metadata_handles_do(_f);
4504 }
4505 };
4506
4507 void Threads::metadata_handles_do(void f(Metadata*)) {
4508 // Only walk the Handles in Thread.
4509 ThreadHandlesClosure handles_closure(f);
4510 threads_do(&handles_closure);
4511 }
4512
4513 void Threads::deoptimized_wrt_marked_nmethods() {
4514 ALL_JAVA_THREADS(p) {
4515 p->deoptimized_wrt_marked_nmethods();
4516 }
4517 }
4518
4519
4520 // Get count Java threads that are waiting to enter the specified monitor.
4521 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4522 int count,
4523 address monitor) {
4524 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4525
4526 int i = 0;
4527 DO_JAVA_THREADS(t_list, p) {
4528 if (!p->can_call_java()) continue;
4529
4530 address pending = (address)p->current_pending_monitor();
4531 if (pending == monitor) { // found a match
4532 if (i < count) result->append(p); // save the first count matches
4533 i++;
4534 }
4535 }
4536
4537 return result;
4538 }
4539
4540
4541 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4542 address owner) {
4543 // NULL owner means not locked so we can skip the search
4544 if (owner == NULL) return NULL;
4545
4546 DO_JAVA_THREADS(t_list, p) {
4547 // first, see if owner is the address of a Java thread
4548 if (owner == (address)p) return p;
4549 }
4550
4551 // Cannot assert on lack of success here since this function may be
4552 // used by code that is trying to report useful problem information
4553 // like deadlock detection.
4554 if (UseHeavyMonitors) return NULL;
4555
4556 // If we didn't find a matching Java thread and we didn't force use of
4557 // heavyweight monitors, then the owner is the stack address of the
4558 // Lock Word in the owning Java thread's stack.
4559 //
4560 JavaThread* the_owner = NULL;
4561 DO_JAVA_THREADS(t_list, q) {
4562 if (q->is_lock_owned(owner)) {
4563 the_owner = q;
4564 break;
4565 }
4566 }
4567
4568 // cannot assert on lack of success here; see above comment
4569 return the_owner;
4570 }
4571
4572 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4573 void Threads::print_on(outputStream* st, bool print_stacks,
4574 bool internal_format, bool print_concurrent_locks,
4575 bool extended_thread_info) {
4576 char buf[32];
4577 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4578
4579 st->print_cr("Full thread dump %s (%s %s):",
4580 Abstract_VM_Version::vm_name(),
4581 Abstract_VM_Version::vm_release(),
4582 Abstract_VM_Version::vm_info_string());
4583 st->cr();
4584
4585 #if INCLUDE_SERVICES
4586 // Dump concurrent locks
4587 ConcurrentLocksDump concurrent_locks;
4588 if (print_concurrent_locks) {
4589 concurrent_locks.dump_at_safepoint();
4590 }
4591 #endif // INCLUDE_SERVICES
4592
4593 ThreadsSMRSupport::print_info_on(st);
4594 st->cr();
4595
4596 ALL_JAVA_THREADS(p) {
4597 ResourceMark rm;
4598 p->print_on(st, extended_thread_info);
4599 if (print_stacks) {
4600 if (internal_format) {
4601 p->trace_stack();
4602 } else {
4603 p->print_stack_on(st);
4604 }
4605 }
4606 st->cr();
4607 #if INCLUDE_SERVICES
4608 if (print_concurrent_locks) {
4609 concurrent_locks.print_locks_on(p, st);
4610 }
4611 #endif // INCLUDE_SERVICES
4612 }
4613
4614 VMThread::vm_thread()->print_on(st);
4615 st->cr();
4616 Universe::heap()->print_gc_threads_on(st);
4617 WatcherThread* wt = WatcherThread::watcher_thread();
4618 if (wt != NULL) {
4619 wt->print_on(st);
4620 st->cr();
4621 }
4622
4623 st->flush();
4624 }
4625
4626 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4627 int buflen, bool* found_current) {
4628 if (this_thread != NULL) {
4629 bool is_current = (current == this_thread);
4630 *found_current = *found_current || is_current;
4631 st->print("%s", is_current ? "=>" : " ");
4632
4633 st->print(PTR_FORMAT, p2i(this_thread));
4634 st->print(" ");
4635 this_thread->print_on_error(st, buf, buflen);
4636 st->cr();
4637 }
4638 }
4639
4640 class PrintOnErrorClosure : public ThreadClosure {
4641 outputStream* _st;
4642 Thread* _current;
4643 char* _buf;
4644 int _buflen;
4645 bool* _found_current;
4646 public:
4647 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4648 int buflen, bool* found_current) :
4649 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4650
4651 virtual void do_thread(Thread* thread) {
4652 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4653 }
4654 };
4655
4656 // Threads::print_on_error() is called by fatal error handler. It's possible
4657 // that VM is not at safepoint and/or current thread is inside signal handler.
4658 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4659 // memory (even in resource area), it might deadlock the error handler.
4660 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4661 int buflen) {
4662 ThreadsSMRSupport::print_info_on(st);
4663 st->cr();
4664
4665 bool found_current = false;
4666 st->print_cr("Java Threads: ( => current thread )");
4667 ALL_JAVA_THREADS(thread) {
4668 print_on_error(thread, st, current, buf, buflen, &found_current);
4669 }
4670 st->cr();
4671
4672 st->print_cr("Other Threads:");
4673 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4674 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4675
4676 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4677 Universe::heap()->gc_threads_do(&print_closure);
4678
4679 if (!found_current) {
4680 st->cr();
4681 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4682 current->print_on_error(st, buf, buflen);
4683 st->cr();
4684 }
4685 st->cr();
4686
4687 st->print_cr("Threads with active compile tasks:");
4688 print_threads_compiling(st, buf, buflen);
4689 }
4690
4691 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4692 ALL_JAVA_THREADS(thread) {
4693 if (thread->is_Compiler_thread()) {
4694 CompilerThread* ct = (CompilerThread*) thread;
4695
4696 // Keep task in local variable for NULL check.
4697 // ct->_task might be set to NULL by concurring compiler thread
4698 // because it completed the compilation. The task is never freed,
4699 // though, just returned to a free list.
4700 CompileTask* task = ct->task();
4701 if (task != NULL) {
4702 thread->print_name_on_error(st, buf, buflen);
4703 task->print(st, NULL, true, true);
4704 }
4705 }
4706 }
4707 }
4708
4709
4710 // Internal SpinLock and Mutex
4711 // Based on ParkEvent
4712
4713 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4714 //
4715 // We employ SpinLocks _only for low-contention, fixed-length
4716 // short-duration critical sections where we're concerned
4717 // about native mutex_t or HotSpot Mutex:: latency.
4718 // The mux construct provides a spin-then-block mutual exclusion
4719 // mechanism.
4720 //
4721 // Testing has shown that contention on the ListLock guarding gFreeList
4722 // is common. If we implement ListLock as a simple SpinLock it's common
4723 // for the JVM to devolve to yielding with little progress. This is true
4724 // despite the fact that the critical sections protected by ListLock are
4725 // extremely short.
4726 //
4727 // TODO-FIXME: ListLock should be of type SpinLock.
4728 // We should make this a 1st-class type, integrated into the lock
4729 // hierarchy as leaf-locks. Critically, the SpinLock structure
4730 // should have sufficient padding to avoid false-sharing and excessive
4731 // cache-coherency traffic.
4732
4733
4734 typedef volatile int SpinLockT;
4735
4736 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4737 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4738 return; // normal fast-path return
4739 }
4740
4741 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4742 TEVENT(SpinAcquire - ctx);
4743 int ctr = 0;
4744 int Yields = 0;
4745 for (;;) {
4746 while (*adr != 0) {
4747 ++ctr;
4748 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4749 if (Yields > 5) {
4750 os::naked_short_sleep(1);
4751 } else {
4752 os::naked_yield();
4753 ++Yields;
4754 }
4755 } else {
4756 SpinPause();
4757 }
4758 }
4759 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4760 }
4761 }
4762
4763 void Thread::SpinRelease(volatile int * adr) {
4764 assert(*adr != 0, "invariant");
4765 OrderAccess::fence(); // guarantee at least release consistency.
4766 // Roach-motel semantics.
4767 // It's safe if subsequent LDs and STs float "up" into the critical section,
4768 // but prior LDs and STs within the critical section can't be allowed
4769 // to reorder or float past the ST that releases the lock.
4770 // Loads and stores in the critical section - which appear in program
4771 // order before the store that releases the lock - must also appear
4772 // before the store that releases the lock in memory visibility order.
4773 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4774 // the ST of 0 into the lock-word which releases the lock, so fence
4775 // more than covers this on all platforms.
4776 *adr = 0;
4777 }
4778
4779 // muxAcquire and muxRelease:
4780 //
4781 // * muxAcquire and muxRelease support a single-word lock-word construct.
4782 // The LSB of the word is set IFF the lock is held.
4783 // The remainder of the word points to the head of a singly-linked list
4784 // of threads blocked on the lock.
4785 //
4786 // * The current implementation of muxAcquire-muxRelease uses its own
4787 // dedicated Thread._MuxEvent instance. If we're interested in
4788 // minimizing the peak number of extant ParkEvent instances then
4789 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4790 // as certain invariants were satisfied. Specifically, care would need
4791 // to be taken with regards to consuming unpark() "permits".
4792 // A safe rule of thumb is that a thread would never call muxAcquire()
4793 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4794 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4795 // consume an unpark() permit intended for monitorenter, for instance.
4796 // One way around this would be to widen the restricted-range semaphore
4797 // implemented in park(). Another alternative would be to provide
4798 // multiple instances of the PlatformEvent() for each thread. One
4799 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4800 //
4801 // * Usage:
4802 // -- Only as leaf locks
4803 // -- for short-term locking only as muxAcquire does not perform
4804 // thread state transitions.
4805 //
4806 // Alternatives:
4807 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4808 // but with parking or spin-then-park instead of pure spinning.
4809 // * Use Taura-Oyama-Yonenzawa locks.
4810 // * It's possible to construct a 1-0 lock if we encode the lockword as
4811 // (List,LockByte). Acquire will CAS the full lockword while Release
4812 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4813 // acquiring threads use timers (ParkTimed) to detect and recover from
4814 // the stranding window. Thread/Node structures must be aligned on 256-byte
4815 // boundaries by using placement-new.
4816 // * Augment MCS with advisory back-link fields maintained with CAS().
4817 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4818 // The validity of the backlinks must be ratified before we trust the value.
4819 // If the backlinks are invalid the exiting thread must back-track through the
4820 // the forward links, which are always trustworthy.
4821 // * Add a successor indication. The LockWord is currently encoded as
4822 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4823 // to provide the usual futile-wakeup optimization.
4824 // See RTStt for details.
4825 // * Consider schedctl.sc_nopreempt to cover the critical section.
4826 //
4827
4828
4829 const intptr_t LOCKBIT = 1;
4830
4831 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4832 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4833 if (w == 0) return;
4834 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4835 return;
4836 }
4837
4838 TEVENT(muxAcquire - Contention);
4839 ParkEvent * const Self = Thread::current()->_MuxEvent;
4840 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4841 for (;;) {
4842 int its = (os::is_MP() ? 100 : 0) + 1;
4843
4844 // Optional spin phase: spin-then-park strategy
4845 while (--its >= 0) {
4846 w = *Lock;
4847 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4848 return;
4849 }
4850 }
4851
4852 Self->reset();
4853 Self->OnList = intptr_t(Lock);
4854 // The following fence() isn't _strictly necessary as the subsequent
4855 // CAS() both serializes execution and ratifies the fetched *Lock value.
4856 OrderAccess::fence();
4857 for (;;) {
4858 w = *Lock;
4859 if ((w & LOCKBIT) == 0) {
4860 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4861 Self->OnList = 0; // hygiene - allows stronger asserts
4862 return;
4863 }
4864 continue; // Interference -- *Lock changed -- Just retry
4865 }
4866 assert(w & LOCKBIT, "invariant");
4867 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4868 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4869 }
4870
4871 while (Self->OnList != 0) {
4872 Self->park();
4873 }
4874 }
4875 }
4876
4877 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4878 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4879 if (w == 0) return;
4880 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4881 return;
4882 }
4883
4884 TEVENT(muxAcquire - Contention);
4885 ParkEvent * ReleaseAfter = NULL;
4886 if (ev == NULL) {
4887 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4888 }
4889 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4890 for (;;) {
4891 guarantee(ev->OnList == 0, "invariant");
4892 int its = (os::is_MP() ? 100 : 0) + 1;
4893
4894 // Optional spin phase: spin-then-park strategy
4895 while (--its >= 0) {
4896 w = *Lock;
4897 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4898 if (ReleaseAfter != NULL) {
4899 ParkEvent::Release(ReleaseAfter);
4900 }
4901 return;
4902 }
4903 }
4904
4905 ev->reset();
4906 ev->OnList = intptr_t(Lock);
4907 // The following fence() isn't _strictly necessary as the subsequent
4908 // CAS() both serializes execution and ratifies the fetched *Lock value.
4909 OrderAccess::fence();
4910 for (;;) {
4911 w = *Lock;
4912 if ((w & LOCKBIT) == 0) {
4913 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4914 ev->OnList = 0;
4915 // We call ::Release while holding the outer lock, thus
4916 // artificially lengthening the critical section.
4917 // Consider deferring the ::Release() until the subsequent unlock(),
4918 // after we've dropped the outer lock.
4919 if (ReleaseAfter != NULL) {
4920 ParkEvent::Release(ReleaseAfter);
4921 }
4922 return;
4923 }
4924 continue; // Interference -- *Lock changed -- Just retry
4925 }
4926 assert(w & LOCKBIT, "invariant");
4927 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4928 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4929 }
4930
4931 while (ev->OnList != 0) {
4932 ev->park();
4933 }
4934 }
4935 }
4936
4937 // Release() must extract a successor from the list and then wake that thread.
4938 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4939 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4940 // Release() would :
4941 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4942 // (B) Extract a successor from the private list "in-hand"
4943 // (C) attempt to CAS() the residual back into *Lock over null.
4944 // If there were any newly arrived threads and the CAS() would fail.
4945 // In that case Release() would detach the RATs, re-merge the list in-hand
4946 // with the RATs and repeat as needed. Alternately, Release() might
4947 // detach and extract a successor, but then pass the residual list to the wakee.
4948 // The wakee would be responsible for reattaching and remerging before it
4949 // competed for the lock.
4950 //
4951 // Both "pop" and DMR are immune from ABA corruption -- there can be
4952 // multiple concurrent pushers, but only one popper or detacher.
4953 // This implementation pops from the head of the list. This is unfair,
4954 // but tends to provide excellent throughput as hot threads remain hot.
4955 // (We wake recently run threads first).
4956 //
4957 // All paths through muxRelease() will execute a CAS.
4958 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4959 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4960 // executed within the critical section are complete and globally visible before the
4961 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4962 void Thread::muxRelease(volatile intptr_t * Lock) {
4963 for (;;) {
4964 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4965 assert(w & LOCKBIT, "invariant");
4966 if (w == LOCKBIT) return;
4967 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4968 assert(List != NULL, "invariant");
4969 assert(List->OnList == intptr_t(Lock), "invariant");
4970 ParkEvent * const nxt = List->ListNext;
4971 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4972
4973 // The following CAS() releases the lock and pops the head element.
4974 // The CAS() also ratifies the previously fetched lock-word value.
4975 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4976 continue;
4977 }
4978 List->OnList = 0;
4979 OrderAccess::fence();
4980 List->unpark();
4981 return;
4982 }
4983 }
4984
4985
4986 void Threads::verify() {
4987 ALL_JAVA_THREADS(p) {
4988 p->verify();
4989 }
4990 VMThread* thread = VMThread::vm_thread();
4991 if (thread != NULL) thread->verify();
4992 }