1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/gcId.hpp"
37 #include "gc/shared/gcLocker.inline.hpp"
38 #include "gc/shared/workgroup.hpp"
39 #include "interpreter/interpreter.hpp"
40 #include "interpreter/linkResolver.hpp"
41 #include "interpreter/oopMapCache.hpp"
42 #include "jvmtifiles/jvmtiEnv.hpp"
43 #include "logging/log.hpp"
44 #include "logging/logConfiguration.hpp"
45 #include "logging/logStream.hpp"
46 #include "memory/metaspaceShared.hpp"
47 #include "memory/oopFactory.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "memory/universe.inline.hpp"
50 #include "oops/instanceKlass.hpp"
51 #include "oops/objArrayOop.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/symbol.hpp"
54 #include "oops/typeArrayOop.inline.hpp"
55 #include "oops/verifyOopClosure.hpp"
56 #include "prims/jvm_misc.hpp"
57 #include "prims/jvmtiExport.hpp"
58 #include "prims/jvmtiThreadState.hpp"
59 #include "prims/privilegedStack.hpp"
60 #include "runtime/arguments.hpp"
61 #include "runtime/atomic.hpp"
62 #include "runtime/biasedLocking.hpp"
63 #include "runtime/commandLineFlagConstraintList.hpp"
64 #include "runtime/commandLineFlagWriteableList.hpp"
65 #include "runtime/commandLineFlagRangeList.hpp"
66 #include "runtime/deoptimization.hpp"
67 #include "runtime/frame.inline.hpp"
68 #include "runtime/globals.hpp"
69 #include "runtime/handshake.hpp"
70 #include "runtime/init.hpp"
71 #include "runtime/interfaceSupport.hpp"
72 #include "runtime/java.hpp"
73 #include "runtime/javaCalls.hpp"
74 #include "runtime/jniPeriodicChecker.hpp"
75 #include "runtime/memprofiler.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/objectMonitor.hpp"
78 #include "runtime/orderAccess.inline.hpp"
79 #include "runtime/osThread.hpp"
80 #include "runtime/prefetch.inline.hpp"
81 #include "runtime/safepoint.hpp"
82 #include "runtime/safepointMechanism.inline.hpp"
83 #include "runtime/sharedRuntime.hpp"
84 #include "runtime/statSampler.hpp"
85 #include "runtime/stubRoutines.hpp"
86 #include "runtime/sweeper.hpp"
87 #include "runtime/task.hpp"
88 #include "runtime/thread.inline.hpp"
89 #include "runtime/threadCritical.hpp"
90 #include "runtime/threadSMR.inline.hpp"
91 #include "runtime/timer.hpp"
92 #include "runtime/timerTrace.hpp"
93 #include "runtime/vframe.hpp"
94 #include "runtime/vframeArray.hpp"
95 #include "runtime/vframe_hp.hpp"
96 #include "runtime/vmThread.hpp"
97 #include "runtime/vm_operations.hpp"
98 #include "runtime/vm_version.hpp"
99 #include "services/attachListener.hpp"
100 #include "services/management.hpp"
101 #include "services/memTracker.hpp"
102 #include "services/threadService.hpp"
103 #include "trace/traceMacros.hpp"
104 #include "trace/tracing.hpp"
105 #include "utilities/align.hpp"
106 #include "utilities/defaultStream.hpp"
107 #include "utilities/dtrace.hpp"
108 #include "utilities/events.hpp"
109 #include "utilities/macros.hpp"
110 #include "utilities/preserveException.hpp"
111 #include "utilities/vmError.hpp"
112 #if INCLUDE_ALL_GCS
113 #include "gc/cms/concurrentMarkSweepThread.hpp"
114 #include "gc/g1/concurrentMarkThread.inline.hpp"
115 #include "gc/parallel/pcTasks.hpp"
116 #endif // INCLUDE_ALL_GCS
117 #if INCLUDE_JVMCI
118 #include "jvmci/jvmciCompiler.hpp"
119 #include "jvmci/jvmciRuntime.hpp"
120 #include "logging/logHandle.hpp"
121 #endif
122 #ifdef COMPILER1
123 #include "c1/c1_Compiler.hpp"
124 #endif
125 #ifdef COMPILER2
126 #include "opto/c2compiler.hpp"
127 #include "opto/idealGraphPrinter.hpp"
128 #endif
129 #if INCLUDE_RTM_OPT
130 #include "runtime/rtmLocking.hpp"
131 #endif
132
133 // Initialization after module runtime initialization
134 void universe_post_module_init(); // must happen after call_initPhase2
135
136 #ifdef DTRACE_ENABLED
137
138 // Only bother with this argument setup if dtrace is available
139
140 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
141 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
142
143 #define DTRACE_THREAD_PROBE(probe, javathread) \
144 { \
145 ResourceMark rm(this); \
146 int len = 0; \
147 const char* name = (javathread)->get_thread_name(); \
148 len = strlen(name); \
149 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
150 (char *) name, len, \
151 java_lang_Thread::thread_id((javathread)->threadObj()), \
152 (uintptr_t) (javathread)->osthread()->thread_id(), \
153 java_lang_Thread::is_daemon((javathread)->threadObj())); \
154 }
155
156 #else // ndef DTRACE_ENABLED
157
158 #define DTRACE_THREAD_PROBE(probe, javathread)
159
160 #endif // ndef DTRACE_ENABLED
161
162 #ifndef USE_LIBRARY_BASED_TLS_ONLY
163 // Current thread is maintained as a thread-local variable
164 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
165 #endif
166 // Class hierarchy
167 // - Thread
168 // - VMThread
169 // - WatcherThread
170 // - ConcurrentMarkSweepThread
171 // - JavaThread
172 // - CompilerThread
173
174 // ======= Thread ========
175 // Support for forcing alignment of thread objects for biased locking
176 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
177 if (UseBiasedLocking) {
178 const int alignment = markOopDesc::biased_lock_alignment;
179 size_t aligned_size = size + (alignment - sizeof(intptr_t));
180 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
181 : AllocateHeap(aligned_size, flags, CURRENT_PC,
182 AllocFailStrategy::RETURN_NULL);
183 void* aligned_addr = align_up(real_malloc_addr, alignment);
184 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
185 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
186 "JavaThread alignment code overflowed allocated storage");
187 if (aligned_addr != real_malloc_addr) {
188 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
189 p2i(real_malloc_addr),
190 p2i(aligned_addr));
191 }
192 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
193 return aligned_addr;
194 } else {
195 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
196 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
197 }
198 }
199
200 void Thread::operator delete(void* p) {
201 if (UseBiasedLocking) {
202 FreeHeap(((Thread*) p)->_real_malloc_address);
203 } else {
204 FreeHeap(p);
205 }
206 }
207
208 void JavaThread::smr_delete() {
209 if (_on_thread_list) {
210 ThreadsSMRSupport::smr_delete(this);
211 } else {
212 delete this;
213 }
214 }
215
216 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
217 // JavaThread
218
219
220 Thread::Thread() {
221 // stack and get_thread
222 set_stack_base(NULL);
223 set_stack_size(0);
224 set_self_raw_id(0);
225 set_lgrp_id(-1);
226 DEBUG_ONLY(clear_suspendible_thread();)
227
228 // allocated data structures
229 set_osthread(NULL);
230 set_resource_area(new (mtThread)ResourceArea());
231 DEBUG_ONLY(_current_resource_mark = NULL;)
232 set_handle_area(new (mtThread) HandleArea(NULL));
233 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
234 set_active_handles(NULL);
235 set_free_handle_block(NULL);
236 set_last_handle_mark(NULL);
237
238 // This initial value ==> never claimed.
239 _oops_do_parity = 0;
240 _threads_hazard_ptr = NULL;
241 _nested_threads_hazard_ptr = NULL;
242 _nested_threads_hazard_ptr_cnt = 0;
243
244 // the handle mark links itself to last_handle_mark
245 new HandleMark(this);
246
247 // plain initialization
248 debug_only(_owned_locks = NULL;)
249 debug_only(_allow_allocation_count = 0;)
250 NOT_PRODUCT(_allow_safepoint_count = 0;)
251 NOT_PRODUCT(_skip_gcalot = false;)
252 _jvmti_env_iteration_count = 0;
253 set_allocated_bytes(0);
254 _vm_operation_started_count = 0;
255 _vm_operation_completed_count = 0;
256 _current_pending_monitor = NULL;
257 _current_pending_monitor_is_from_java = true;
258 _current_waiting_monitor = NULL;
259 _num_nested_signal = 0;
260 omFreeList = NULL;
261 omFreeCount = 0;
262 omFreeProvision = 32;
263 omInUseList = NULL;
264 omInUseCount = 0;
265
266 #ifdef ASSERT
267 _visited_for_critical_count = false;
268 #endif
269
270 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
271 Monitor::_safepoint_check_sometimes);
272 _suspend_flags = 0;
273
274 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
275 _hashStateX = os::random();
276 _hashStateY = 842502087;
277 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
278 _hashStateW = 273326509;
279
280 _OnTrap = 0;
281 _schedctl = NULL;
282 _Stalled = 0;
283 _TypeTag = 0x2BAD;
284
285 // Many of the following fields are effectively final - immutable
286 // Note that nascent threads can't use the Native Monitor-Mutex
287 // construct until the _MutexEvent is initialized ...
288 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
289 // we might instead use a stack of ParkEvents that we could provision on-demand.
290 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
291 // and ::Release()
292 _ParkEvent = ParkEvent::Allocate(this);
293 _SleepEvent = ParkEvent::Allocate(this);
294 _MutexEvent = ParkEvent::Allocate(this);
295 _MuxEvent = ParkEvent::Allocate(this);
296
297 #ifdef CHECK_UNHANDLED_OOPS
298 if (CheckUnhandledOops) {
299 _unhandled_oops = new UnhandledOops(this);
300 }
301 #endif // CHECK_UNHANDLED_OOPS
302 #ifdef ASSERT
303 if (UseBiasedLocking) {
304 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
305 assert(this == _real_malloc_address ||
306 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
307 "bug in forced alignment of thread objects");
308 }
309 #endif // ASSERT
310 }
311
312 void Thread::initialize_thread_current() {
313 #ifndef USE_LIBRARY_BASED_TLS_ONLY
314 assert(_thr_current == NULL, "Thread::current already initialized");
315 _thr_current = this;
316 #endif
317 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
318 ThreadLocalStorage::set_thread(this);
319 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
320 }
321
322 void Thread::clear_thread_current() {
323 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
324 #ifndef USE_LIBRARY_BASED_TLS_ONLY
325 _thr_current = NULL;
326 #endif
327 ThreadLocalStorage::set_thread(NULL);
328 }
329
330 void Thread::record_stack_base_and_size() {
331 set_stack_base(os::current_stack_base());
332 set_stack_size(os::current_stack_size());
333 // CR 7190089: on Solaris, primordial thread's stack is adjusted
334 // in initialize_thread(). Without the adjustment, stack size is
335 // incorrect if stack is set to unlimited (ulimit -s unlimited).
336 // So far, only Solaris has real implementation of initialize_thread().
337 //
338 // set up any platform-specific state.
339 os::initialize_thread(this);
340
341 // Set stack limits after thread is initialized.
342 if (is_Java_thread()) {
343 ((JavaThread*) this)->set_stack_overflow_limit();
344 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
345 }
346 #if INCLUDE_NMT
347 // record thread's native stack, stack grows downward
348 MemTracker::record_thread_stack(stack_end(), stack_size());
349 #endif // INCLUDE_NMT
350 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
351 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
352 os::current_thread_id(), p2i(stack_base() - stack_size()),
353 p2i(stack_base()), stack_size()/1024);
354 }
355
356
357 Thread::~Thread() {
358 EVENT_THREAD_DESTRUCT(this);
359
360 // stack_base can be NULL if the thread is never started or exited before
361 // record_stack_base_and_size called. Although, we would like to ensure
362 // that all started threads do call record_stack_base_and_size(), there is
363 // not proper way to enforce that.
364 #if INCLUDE_NMT
365 if (_stack_base != NULL) {
366 MemTracker::release_thread_stack(stack_end(), stack_size());
367 #ifdef ASSERT
368 set_stack_base(NULL);
369 #endif
370 }
371 #endif // INCLUDE_NMT
372
373 // deallocate data structures
374 delete resource_area();
375 // since the handle marks are using the handle area, we have to deallocated the root
376 // handle mark before deallocating the thread's handle area,
377 assert(last_handle_mark() != NULL, "check we have an element");
378 delete last_handle_mark();
379 assert(last_handle_mark() == NULL, "check we have reached the end");
380
381 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
382 // We NULL out the fields for good hygiene.
383 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
384 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
385 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
386 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
387
388 delete handle_area();
389 delete metadata_handles();
390
391 // SR_handler uses this as a termination indicator -
392 // needs to happen before os::free_thread()
393 delete _SR_lock;
394 _SR_lock = NULL;
395
396 // osthread() can be NULL, if creation of thread failed.
397 if (osthread() != NULL) os::free_thread(osthread());
398
399 // clear Thread::current if thread is deleting itself.
400 // Needed to ensure JNI correctly detects non-attached threads.
401 if (this == Thread::current()) {
402 clear_thread_current();
403 }
404
405 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
406 }
407
408 // NOTE: dummy function for assertion purpose.
409 void Thread::run() {
410 ShouldNotReachHere();
411 }
412
413 #ifdef ASSERT
414 // A JavaThread is considered "dangling" if it is not the current
415 // thread, has been added the Threads list, the system is not at a
416 // safepoint and the Thread is not "protected".
417 //
418 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
419 assert(!thread->is_Java_thread() || Thread::current() == thread ||
420 !((JavaThread *) thread)->on_thread_list() ||
421 SafepointSynchronize::is_at_safepoint() ||
422 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
423 "possibility of dangling Thread pointer");
424 }
425 #endif
426
427 ThreadPriority Thread::get_priority(const Thread* const thread) {
428 ThreadPriority priority;
429 // Can return an error!
430 (void)os::get_priority(thread, priority);
431 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
432 return priority;
433 }
434
435 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
436 debug_only(check_for_dangling_thread_pointer(thread);)
437 // Can return an error!
438 (void)os::set_priority(thread, priority);
439 }
440
441
442 void Thread::start(Thread* thread) {
443 // Start is different from resume in that its safety is guaranteed by context or
444 // being called from a Java method synchronized on the Thread object.
445 if (!DisableStartThread) {
446 if (thread->is_Java_thread()) {
447 // Initialize the thread state to RUNNABLE before starting this thread.
448 // Can not set it after the thread started because we do not know the
449 // exact thread state at that time. It could be in MONITOR_WAIT or
450 // in SLEEPING or some other state.
451 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
452 java_lang_Thread::RUNNABLE);
453 }
454 os::start_thread(thread);
455 }
456 }
457
458 // Enqueue a VM_Operation to do the job for us - sometime later
459 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
460 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
461 VMThread::execute(vm_stop);
462 }
463
464
465 // Check if an external suspend request has completed (or has been
466 // cancelled). Returns true if the thread is externally suspended and
467 // false otherwise.
468 //
469 // The bits parameter returns information about the code path through
470 // the routine. Useful for debugging:
471 //
472 // set in is_ext_suspend_completed():
473 // 0x00000001 - routine was entered
474 // 0x00000010 - routine return false at end
475 // 0x00000100 - thread exited (return false)
476 // 0x00000200 - suspend request cancelled (return false)
477 // 0x00000400 - thread suspended (return true)
478 // 0x00001000 - thread is in a suspend equivalent state (return true)
479 // 0x00002000 - thread is native and walkable (return true)
480 // 0x00004000 - thread is native_trans and walkable (needed retry)
481 //
482 // set in wait_for_ext_suspend_completion():
483 // 0x00010000 - routine was entered
484 // 0x00020000 - suspend request cancelled before loop (return false)
485 // 0x00040000 - thread suspended before loop (return true)
486 // 0x00080000 - suspend request cancelled in loop (return false)
487 // 0x00100000 - thread suspended in loop (return true)
488 // 0x00200000 - suspend not completed during retry loop (return false)
489
490 // Helper class for tracing suspend wait debug bits.
491 //
492 // 0x00000100 indicates that the target thread exited before it could
493 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
494 // 0x00080000 each indicate a cancelled suspend request so they don't
495 // count as wait failures either.
496 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
497
498 class TraceSuspendDebugBits : public StackObj {
499 private:
500 JavaThread * jt;
501 bool is_wait;
502 bool called_by_wait; // meaningful when !is_wait
503 uint32_t * bits;
504
505 public:
506 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
507 uint32_t *_bits) {
508 jt = _jt;
509 is_wait = _is_wait;
510 called_by_wait = _called_by_wait;
511 bits = _bits;
512 }
513
514 ~TraceSuspendDebugBits() {
515 if (!is_wait) {
516 #if 1
517 // By default, don't trace bits for is_ext_suspend_completed() calls.
518 // That trace is very chatty.
519 return;
520 #else
521 if (!called_by_wait) {
522 // If tracing for is_ext_suspend_completed() is enabled, then only
523 // trace calls to it from wait_for_ext_suspend_completion()
524 return;
525 }
526 #endif
527 }
528
529 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
530 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
531 MutexLocker ml(Threads_lock); // needed for get_thread_name()
532 ResourceMark rm;
533
534 tty->print_cr(
535 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
536 jt->get_thread_name(), *bits);
537
538 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
539 }
540 }
541 }
542 };
543 #undef DEBUG_FALSE_BITS
544
545
546 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
547 uint32_t *bits) {
548 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
549
550 bool did_trans_retry = false; // only do thread_in_native_trans retry once
551 bool do_trans_retry; // flag to force the retry
552
553 *bits |= 0x00000001;
554
555 do {
556 do_trans_retry = false;
557
558 if (is_exiting()) {
559 // Thread is in the process of exiting. This is always checked
560 // first to reduce the risk of dereferencing a freed JavaThread.
561 *bits |= 0x00000100;
562 return false;
563 }
564
565 if (!is_external_suspend()) {
566 // Suspend request is cancelled. This is always checked before
567 // is_ext_suspended() to reduce the risk of a rogue resume
568 // confusing the thread that made the suspend request.
569 *bits |= 0x00000200;
570 return false;
571 }
572
573 if (is_ext_suspended()) {
574 // thread is suspended
575 *bits |= 0x00000400;
576 return true;
577 }
578
579 // Now that we no longer do hard suspends of threads running
580 // native code, the target thread can be changing thread state
581 // while we are in this routine:
582 //
583 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
584 //
585 // We save a copy of the thread state as observed at this moment
586 // and make our decision about suspend completeness based on the
587 // copy. This closes the race where the thread state is seen as
588 // _thread_in_native_trans in the if-thread_blocked check, but is
589 // seen as _thread_blocked in if-thread_in_native_trans check.
590 JavaThreadState save_state = thread_state();
591
592 if (save_state == _thread_blocked && is_suspend_equivalent()) {
593 // If the thread's state is _thread_blocked and this blocking
594 // condition is known to be equivalent to a suspend, then we can
595 // consider the thread to be externally suspended. This means that
596 // the code that sets _thread_blocked has been modified to do
597 // self-suspension if the blocking condition releases. We also
598 // used to check for CONDVAR_WAIT here, but that is now covered by
599 // the _thread_blocked with self-suspension check.
600 //
601 // Return true since we wouldn't be here unless there was still an
602 // external suspend request.
603 *bits |= 0x00001000;
604 return true;
605 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
606 // Threads running native code will self-suspend on native==>VM/Java
607 // transitions. If its stack is walkable (should always be the case
608 // unless this function is called before the actual java_suspend()
609 // call), then the wait is done.
610 *bits |= 0x00002000;
611 return true;
612 } else if (!called_by_wait && !did_trans_retry &&
613 save_state == _thread_in_native_trans &&
614 frame_anchor()->walkable()) {
615 // The thread is transitioning from thread_in_native to another
616 // thread state. check_safepoint_and_suspend_for_native_trans()
617 // will force the thread to self-suspend. If it hasn't gotten
618 // there yet we may have caught the thread in-between the native
619 // code check above and the self-suspend. Lucky us. If we were
620 // called by wait_for_ext_suspend_completion(), then it
621 // will be doing the retries so we don't have to.
622 //
623 // Since we use the saved thread state in the if-statement above,
624 // there is a chance that the thread has already transitioned to
625 // _thread_blocked by the time we get here. In that case, we will
626 // make a single unnecessary pass through the logic below. This
627 // doesn't hurt anything since we still do the trans retry.
628
629 *bits |= 0x00004000;
630
631 // Once the thread leaves thread_in_native_trans for another
632 // thread state, we break out of this retry loop. We shouldn't
633 // need this flag to prevent us from getting back here, but
634 // sometimes paranoia is good.
635 did_trans_retry = true;
636
637 // We wait for the thread to transition to a more usable state.
638 for (int i = 1; i <= SuspendRetryCount; i++) {
639 // We used to do an "os::yield_all(i)" call here with the intention
640 // that yielding would increase on each retry. However, the parameter
641 // is ignored on Linux which means the yield didn't scale up. Waiting
642 // on the SR_lock below provides a much more predictable scale up for
643 // the delay. It also provides a simple/direct point to check for any
644 // safepoint requests from the VMThread
645
646 // temporarily drops SR_lock while doing wait with safepoint check
647 // (if we're a JavaThread - the WatcherThread can also call this)
648 // and increase delay with each retry
649 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
650
651 // check the actual thread state instead of what we saved above
652 if (thread_state() != _thread_in_native_trans) {
653 // the thread has transitioned to another thread state so
654 // try all the checks (except this one) one more time.
655 do_trans_retry = true;
656 break;
657 }
658 } // end retry loop
659
660
661 }
662 } while (do_trans_retry);
663
664 *bits |= 0x00000010;
665 return false;
666 }
667
668 // Wait for an external suspend request to complete (or be cancelled).
669 // Returns true if the thread is externally suspended and false otherwise.
670 //
671 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
672 uint32_t *bits) {
673 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
674 false /* !called_by_wait */, bits);
675
676 // local flag copies to minimize SR_lock hold time
677 bool is_suspended;
678 bool pending;
679 uint32_t reset_bits;
680
681 // set a marker so is_ext_suspend_completed() knows we are the caller
682 *bits |= 0x00010000;
683
684 // We use reset_bits to reinitialize the bits value at the top of
685 // each retry loop. This allows the caller to make use of any
686 // unused bits for their own marking purposes.
687 reset_bits = *bits;
688
689 {
690 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
691 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
692 delay, bits);
693 pending = is_external_suspend();
694 }
695 // must release SR_lock to allow suspension to complete
696
697 if (!pending) {
698 // A cancelled suspend request is the only false return from
699 // is_ext_suspend_completed() that keeps us from entering the
700 // retry loop.
701 *bits |= 0x00020000;
702 return false;
703 }
704
705 if (is_suspended) {
706 *bits |= 0x00040000;
707 return true;
708 }
709
710 for (int i = 1; i <= retries; i++) {
711 *bits = reset_bits; // reinit to only track last retry
712
713 // We used to do an "os::yield_all(i)" call here with the intention
714 // that yielding would increase on each retry. However, the parameter
715 // is ignored on Linux which means the yield didn't scale up. Waiting
716 // on the SR_lock below provides a much more predictable scale up for
717 // the delay. It also provides a simple/direct point to check for any
718 // safepoint requests from the VMThread
719
720 {
721 MutexLocker ml(SR_lock());
722 // wait with safepoint check (if we're a JavaThread - the WatcherThread
723 // can also call this) and increase delay with each retry
724 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
725
726 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
727 delay, bits);
728
729 // It is possible for the external suspend request to be cancelled
730 // (by a resume) before the actual suspend operation is completed.
731 // Refresh our local copy to see if we still need to wait.
732 pending = is_external_suspend();
733 }
734
735 if (!pending) {
736 // A cancelled suspend request is the only false return from
737 // is_ext_suspend_completed() that keeps us from staying in the
738 // retry loop.
739 *bits |= 0x00080000;
740 return false;
741 }
742
743 if (is_suspended) {
744 *bits |= 0x00100000;
745 return true;
746 }
747 } // end retry loop
748
749 // thread did not suspend after all our retries
750 *bits |= 0x00200000;
751 return false;
752 }
753
754 // Called from API entry points which perform stack walking. If the
755 // associated JavaThread is the current thread, then wait_for_suspend
756 // is not used. Otherwise, it determines if we should wait for the
757 // "other" thread to complete external suspension. (NOTE: in future
758 // releases the suspension mechanism should be reimplemented so this
759 // is not necessary.)
760 //
761 bool
762 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
763 if (this != JavaThread::current()) {
764 // "other" threads require special handling.
765 if (wait_for_suspend) {
766 // We are allowed to wait for the external suspend to complete
767 // so give the other thread a chance to get suspended.
768 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
769 SuspendRetryDelay, bits)) {
770 // Didn't make it so let the caller know.
771 return false;
772 }
773 }
774 // We aren't allowed to wait for the external suspend to complete
775 // so if the other thread isn't externally suspended we need to
776 // let the caller know.
777 else if (!is_ext_suspend_completed_with_lock(bits)) {
778 return false;
779 }
780 }
781
782 return true;
783 }
784
785 #ifndef PRODUCT
786 void JavaThread::record_jump(address target, address instr, const char* file,
787 int line) {
788
789 // This should not need to be atomic as the only way for simultaneous
790 // updates is via interrupts. Even then this should be rare or non-existent
791 // and we don't care that much anyway.
792
793 int index = _jmp_ring_index;
794 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
795 _jmp_ring[index]._target = (intptr_t) target;
796 _jmp_ring[index]._instruction = (intptr_t) instr;
797 _jmp_ring[index]._file = file;
798 _jmp_ring[index]._line = line;
799 }
800 #endif // PRODUCT
801
802 void Thread::interrupt(Thread* thread) {
803 debug_only(check_for_dangling_thread_pointer(thread);)
804 os::interrupt(thread);
805 }
806
807 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
808 debug_only(check_for_dangling_thread_pointer(thread);)
809 // Note: If clear_interrupted==false, this simply fetches and
810 // returns the value of the field osthread()->interrupted().
811 return os::is_interrupted(thread, clear_interrupted);
812 }
813
814
815 // GC Support
816 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
817 int thread_parity = _oops_do_parity;
818 if (thread_parity != strong_roots_parity) {
819 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
820 if (res == thread_parity) {
821 return true;
822 } else {
823 guarantee(res == strong_roots_parity, "Or else what?");
824 return false;
825 }
826 }
827 return false;
828 }
829
830 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
831 active_handles()->oops_do(f);
832 // Do oop for ThreadShadow
833 f->do_oop((oop*)&_pending_exception);
834 handle_area()->oops_do(f);
835
836 if (MonitorInUseLists) {
837 // When using thread local monitor lists, we scan them here,
838 // and the remaining global monitors in ObjectSynchronizer::oops_do().
839 ObjectSynchronizer::thread_local_used_oops_do(this, f);
840 }
841 }
842
843 void Thread::metadata_handles_do(void f(Metadata*)) {
844 // Only walk the Handles in Thread.
845 if (metadata_handles() != NULL) {
846 for (int i = 0; i< metadata_handles()->length(); i++) {
847 f(metadata_handles()->at(i));
848 }
849 }
850 }
851
852 void Thread::print_on(outputStream* st) const {
853 // get_priority assumes osthread initialized
854 if (osthread() != NULL) {
855 int os_prio;
856 if (os::get_native_priority(this, &os_prio) == OS_OK) {
857 st->print("os_prio=%d ", os_prio);
858 }
859 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
860 ext().print_on(st);
861 osthread()->print_on(st);
862 }
863 if (_threads_hazard_ptr != NULL) {
864 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
865 }
866 if (_nested_threads_hazard_ptr != NULL) {
867 print_nested_threads_hazard_ptrs_on(st);
868 }
869 st->print(" ");
870 debug_only(if (WizardMode) print_owned_locks_on(st);)
871 }
872
873 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
874 assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
875
876 if (EnableThreadSMRStatistics) {
877 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
878 }
879 st->print(", _nested_threads_hazard_ptrs=");
880 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
881 node = node->next()) {
882 if (node != _nested_threads_hazard_ptr) {
883 // First node does not need a comma-space separator.
884 st->print(", ");
885 }
886 st->print(INTPTR_FORMAT, p2i(node->t_list()));
887 }
888 }
889
890 // Thread::print_on_error() is called by fatal error handler. Don't use
891 // any lock or allocate memory.
892 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
893 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
894
895 if (is_VM_thread()) { st->print("VMThread"); }
896 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
897 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
898 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
899 else { st->print("Thread"); }
900
901 if (is_Named_thread()) {
902 st->print(" \"%s\"", name());
903 }
904
905 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
906 p2i(stack_end()), p2i(stack_base()));
907
908 if (osthread()) {
909 st->print(" [id=%d]", osthread()->thread_id());
910 }
911
912 if (_threads_hazard_ptr != NULL) {
913 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
914 }
915 if (_nested_threads_hazard_ptr != NULL) {
916 print_nested_threads_hazard_ptrs_on(st);
917 }
918 }
919
920 void Thread::print_value_on(outputStream* st) const {
921 if (is_Named_thread()) {
922 st->print(" \"%s\" ", name());
923 }
924 st->print(INTPTR_FORMAT, p2i(this)); // print address
925 }
926
927 #ifdef ASSERT
928 void Thread::print_owned_locks_on(outputStream* st) const {
929 Monitor *cur = _owned_locks;
930 if (cur == NULL) {
931 st->print(" (no locks) ");
932 } else {
933 st->print_cr(" Locks owned:");
934 while (cur) {
935 cur->print_on(st);
936 cur = cur->next();
937 }
938 }
939 }
940
941 static int ref_use_count = 0;
942
943 bool Thread::owns_locks_but_compiled_lock() const {
944 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
945 if (cur != Compile_lock) return true;
946 }
947 return false;
948 }
949
950
951 #endif
952
953 #ifndef PRODUCT
954
955 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
956 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
957 // no threads which allow_vm_block's are held
958 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
959 // Check if current thread is allowed to block at a safepoint
960 if (!(_allow_safepoint_count == 0)) {
961 fatal("Possible safepoint reached by thread that does not allow it");
962 }
963 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
964 fatal("LEAF method calling lock?");
965 }
966
967 #ifdef ASSERT
968 if (potential_vm_operation && is_Java_thread()
969 && !Universe::is_bootstrapping()) {
970 // Make sure we do not hold any locks that the VM thread also uses.
971 // This could potentially lead to deadlocks
972 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
973 // Threads_lock is special, since the safepoint synchronization will not start before this is
974 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
975 // since it is used to transfer control between JavaThreads and the VMThread
976 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
977 if ((cur->allow_vm_block() &&
978 cur != Threads_lock &&
979 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
980 cur != VMOperationRequest_lock &&
981 cur != VMOperationQueue_lock) ||
982 cur->rank() == Mutex::special) {
983 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
984 }
985 }
986 }
987
988 if (GCALotAtAllSafepoints) {
989 // We could enter a safepoint here and thus have a gc
990 InterfaceSupport::check_gc_alot();
991 }
992 #endif
993 }
994 #endif
995
996 bool Thread::is_in_stack(address adr) const {
997 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
998 address end = os::current_stack_pointer();
999 // Allow non Java threads to call this without stack_base
1000 if (_stack_base == NULL) return true;
1001 if (stack_base() >= adr && adr >= end) return true;
1002
1003 return false;
1004 }
1005
1006 bool Thread::is_in_usable_stack(address adr) const {
1007 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1008 size_t usable_stack_size = _stack_size - stack_guard_size;
1009
1010 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1011 }
1012
1013
1014 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1015 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1016 // used for compilation in the future. If that change is made, the need for these methods
1017 // should be revisited, and they should be removed if possible.
1018
1019 bool Thread::is_lock_owned(address adr) const {
1020 return on_local_stack(adr);
1021 }
1022
1023 bool Thread::set_as_starting_thread() {
1024 // NOTE: this must be called inside the main thread.
1025 return os::create_main_thread((JavaThread*)this);
1026 }
1027
1028 static void initialize_class(Symbol* class_name, TRAPS) {
1029 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1030 InstanceKlass::cast(klass)->initialize(CHECK);
1031 }
1032
1033
1034 // Creates the initial ThreadGroup
1035 static Handle create_initial_thread_group(TRAPS) {
1036 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1037 InstanceKlass* ik = InstanceKlass::cast(k);
1038
1039 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1040 {
1041 JavaValue result(T_VOID);
1042 JavaCalls::call_special(&result,
1043 system_instance,
1044 ik,
1045 vmSymbols::object_initializer_name(),
1046 vmSymbols::void_method_signature(),
1047 CHECK_NH);
1048 }
1049 Universe::set_system_thread_group(system_instance());
1050
1051 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1052 {
1053 JavaValue result(T_VOID);
1054 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1055 JavaCalls::call_special(&result,
1056 main_instance,
1057 ik,
1058 vmSymbols::object_initializer_name(),
1059 vmSymbols::threadgroup_string_void_signature(),
1060 system_instance,
1061 string,
1062 CHECK_NH);
1063 }
1064 return main_instance;
1065 }
1066
1067 // Creates the initial Thread
1068 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1069 TRAPS) {
1070 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1071 InstanceKlass* ik = InstanceKlass::cast(k);
1072 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1073
1074 java_lang_Thread::set_thread(thread_oop(), thread);
1075 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1076 thread->set_threadObj(thread_oop());
1077
1078 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1079
1080 JavaValue result(T_VOID);
1081 JavaCalls::call_special(&result, thread_oop,
1082 ik,
1083 vmSymbols::object_initializer_name(),
1084 vmSymbols::threadgroup_string_void_signature(),
1085 thread_group,
1086 string,
1087 CHECK_NULL);
1088 return thread_oop();
1089 }
1090
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093
1094 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1095 static const char* get_java_runtime_name(TRAPS) {
1096 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1097 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1098 fieldDescriptor fd;
1099 bool found = k != NULL &&
1100 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1101 vmSymbols::string_signature(), &fd);
1102 if (found) {
1103 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1104 if (name_oop == NULL) {
1105 return NULL;
1106 }
1107 const char* name = java_lang_String::as_utf8_string(name_oop,
1108 java_runtime_name,
1109 sizeof(java_runtime_name));
1110 return name;
1111 } else {
1112 return NULL;
1113 }
1114 }
1115
1116 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1117 static const char* get_java_runtime_version(TRAPS) {
1118 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1119 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1120 fieldDescriptor fd;
1121 bool found = k != NULL &&
1122 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1123 vmSymbols::string_signature(), &fd);
1124 if (found) {
1125 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1126 if (name_oop == NULL) {
1127 return NULL;
1128 }
1129 const char* name = java_lang_String::as_utf8_string(name_oop,
1130 java_runtime_version,
1131 sizeof(java_runtime_version));
1132 return name;
1133 } else {
1134 return NULL;
1135 }
1136 }
1137
1138 // General purpose hook into Java code, run once when the VM is initialized.
1139 // The Java library method itself may be changed independently from the VM.
1140 static void call_postVMInitHook(TRAPS) {
1141 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1142 if (klass != NULL) {
1143 JavaValue result(T_VOID);
1144 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1145 vmSymbols::void_method_signature(),
1146 CHECK);
1147 }
1148 }
1149
1150 static void reset_vm_info_property(TRAPS) {
1151 // the vm info string
1152 ResourceMark rm(THREAD);
1153 const char *vm_info = VM_Version::vm_info_string();
1154
1155 // java.lang.System class
1156 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1157
1158 // setProperty arguments
1159 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1160 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1161
1162 // return value
1163 JavaValue r(T_OBJECT);
1164
1165 // public static String setProperty(String key, String value);
1166 JavaCalls::call_static(&r,
1167 klass,
1168 vmSymbols::setProperty_name(),
1169 vmSymbols::string_string_string_signature(),
1170 key_str,
1171 value_str,
1172 CHECK);
1173 }
1174
1175
1176 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1177 bool daemon, TRAPS) {
1178 assert(thread_group.not_null(), "thread group should be specified");
1179 assert(threadObj() == NULL, "should only create Java thread object once");
1180
1181 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1182 InstanceKlass* ik = InstanceKlass::cast(k);
1183 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1184
1185 java_lang_Thread::set_thread(thread_oop(), this);
1186 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1187 set_threadObj(thread_oop());
1188
1189 JavaValue result(T_VOID);
1190 if (thread_name != NULL) {
1191 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1192 // Thread gets assigned specified name and null target
1193 JavaCalls::call_special(&result,
1194 thread_oop,
1195 ik,
1196 vmSymbols::object_initializer_name(),
1197 vmSymbols::threadgroup_string_void_signature(),
1198 thread_group, // Argument 1
1199 name, // Argument 2
1200 THREAD);
1201 } else {
1202 // Thread gets assigned name "Thread-nnn" and null target
1203 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1204 JavaCalls::call_special(&result,
1205 thread_oop,
1206 ik,
1207 vmSymbols::object_initializer_name(),
1208 vmSymbols::threadgroup_runnable_void_signature(),
1209 thread_group, // Argument 1
1210 Handle(), // Argument 2
1211 THREAD);
1212 }
1213
1214
1215 if (daemon) {
1216 java_lang_Thread::set_daemon(thread_oop());
1217 }
1218
1219 if (HAS_PENDING_EXCEPTION) {
1220 return;
1221 }
1222
1223 Klass* group = SystemDictionary::ThreadGroup_klass();
1224 Handle threadObj(THREAD, this->threadObj());
1225
1226 JavaCalls::call_special(&result,
1227 thread_group,
1228 group,
1229 vmSymbols::add_method_name(),
1230 vmSymbols::thread_void_signature(),
1231 threadObj, // Arg 1
1232 THREAD);
1233 }
1234
1235 // NamedThread -- non-JavaThread subclasses with multiple
1236 // uniquely named instances should derive from this.
1237 NamedThread::NamedThread() : Thread() {
1238 _name = NULL;
1239 _processed_thread = NULL;
1240 _gc_id = GCId::undefined();
1241 }
1242
1243 NamedThread::~NamedThread() {
1244 if (_name != NULL) {
1245 FREE_C_HEAP_ARRAY(char, _name);
1246 _name = NULL;
1247 }
1248 }
1249
1250 void NamedThread::set_name(const char* format, ...) {
1251 guarantee(_name == NULL, "Only get to set name once.");
1252 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1253 guarantee(_name != NULL, "alloc failure");
1254 va_list ap;
1255 va_start(ap, format);
1256 jio_vsnprintf(_name, max_name_len, format, ap);
1257 va_end(ap);
1258 }
1259
1260 void NamedThread::initialize_named_thread() {
1261 set_native_thread_name(name());
1262 }
1263
1264 void NamedThread::print_on(outputStream* st) const {
1265 st->print("\"%s\" ", name());
1266 Thread::print_on(st);
1267 st->cr();
1268 }
1269
1270
1271 // ======= WatcherThread ========
1272
1273 // The watcher thread exists to simulate timer interrupts. It should
1274 // be replaced by an abstraction over whatever native support for
1275 // timer interrupts exists on the platform.
1276
1277 WatcherThread* WatcherThread::_watcher_thread = NULL;
1278 bool WatcherThread::_startable = false;
1279 volatile bool WatcherThread::_should_terminate = false;
1280
1281 WatcherThread::WatcherThread() : Thread() {
1282 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1283 if (os::create_thread(this, os::watcher_thread)) {
1284 _watcher_thread = this;
1285
1286 // Set the watcher thread to the highest OS priority which should not be
1287 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1288 // is created. The only normal thread using this priority is the reference
1289 // handler thread, which runs for very short intervals only.
1290 // If the VMThread's priority is not lower than the WatcherThread profiling
1291 // will be inaccurate.
1292 os::set_priority(this, MaxPriority);
1293 if (!DisableStartThread) {
1294 os::start_thread(this);
1295 }
1296 }
1297 }
1298
1299 int WatcherThread::sleep() const {
1300 // The WatcherThread does not participate in the safepoint protocol
1301 // for the PeriodicTask_lock because it is not a JavaThread.
1302 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1303
1304 if (_should_terminate) {
1305 // check for termination before we do any housekeeping or wait
1306 return 0; // we did not sleep.
1307 }
1308
1309 // remaining will be zero if there are no tasks,
1310 // causing the WatcherThread to sleep until a task is
1311 // enrolled
1312 int remaining = PeriodicTask::time_to_wait();
1313 int time_slept = 0;
1314
1315 // we expect this to timeout - we only ever get unparked when
1316 // we should terminate or when a new task has been enrolled
1317 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1318
1319 jlong time_before_loop = os::javaTimeNanos();
1320
1321 while (true) {
1322 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1323 remaining);
1324 jlong now = os::javaTimeNanos();
1325
1326 if (remaining == 0) {
1327 // if we didn't have any tasks we could have waited for a long time
1328 // consider the time_slept zero and reset time_before_loop
1329 time_slept = 0;
1330 time_before_loop = now;
1331 } else {
1332 // need to recalculate since we might have new tasks in _tasks
1333 time_slept = (int) ((now - time_before_loop) / 1000000);
1334 }
1335
1336 // Change to task list or spurious wakeup of some kind
1337 if (timedout || _should_terminate) {
1338 break;
1339 }
1340
1341 remaining = PeriodicTask::time_to_wait();
1342 if (remaining == 0) {
1343 // Last task was just disenrolled so loop around and wait until
1344 // another task gets enrolled
1345 continue;
1346 }
1347
1348 remaining -= time_slept;
1349 if (remaining <= 0) {
1350 break;
1351 }
1352 }
1353
1354 return time_slept;
1355 }
1356
1357 void WatcherThread::run() {
1358 assert(this == watcher_thread(), "just checking");
1359
1360 this->record_stack_base_and_size();
1361 this->set_native_thread_name(this->name());
1362 this->set_active_handles(JNIHandleBlock::allocate_block());
1363 while (true) {
1364 assert(watcher_thread() == Thread::current(), "thread consistency check");
1365 assert(watcher_thread() == this, "thread consistency check");
1366
1367 // Calculate how long it'll be until the next PeriodicTask work
1368 // should be done, and sleep that amount of time.
1369 int time_waited = sleep();
1370
1371 if (VMError::is_error_reported()) {
1372 // A fatal error has happened, the error handler(VMError::report_and_die)
1373 // should abort JVM after creating an error log file. However in some
1374 // rare cases, the error handler itself might deadlock. Here periodically
1375 // check for error reporting timeouts, and if it happens, just proceed to
1376 // abort the VM.
1377
1378 // This code is in WatcherThread because WatcherThread wakes up
1379 // periodically so the fatal error handler doesn't need to do anything;
1380 // also because the WatcherThread is less likely to crash than other
1381 // threads.
1382
1383 for (;;) {
1384 // Note: we use naked sleep in this loop because we want to avoid using
1385 // any kind of VM infrastructure which may be broken at this point.
1386 if (VMError::check_timeout()) {
1387 // We hit error reporting timeout. Error reporting was interrupted and
1388 // will be wrapping things up now (closing files etc). Give it some more
1389 // time, then quit the VM.
1390 os::naked_short_sleep(200);
1391 // Print a message to stderr.
1392 fdStream err(defaultStream::output_fd());
1393 err.print_raw_cr("# [ timer expired, abort... ]");
1394 // skip atexit/vm_exit/vm_abort hooks
1395 os::die();
1396 }
1397
1398 // Wait a second, then recheck for timeout.
1399 os::naked_short_sleep(999);
1400 }
1401 }
1402
1403 if (_should_terminate) {
1404 // check for termination before posting the next tick
1405 break;
1406 }
1407
1408 PeriodicTask::real_time_tick(time_waited);
1409 }
1410
1411 // Signal that it is terminated
1412 {
1413 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1414 _watcher_thread = NULL;
1415 Terminator_lock->notify();
1416 }
1417 }
1418
1419 void WatcherThread::start() {
1420 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1421
1422 if (watcher_thread() == NULL && _startable) {
1423 _should_terminate = false;
1424 // Create the single instance of WatcherThread
1425 new WatcherThread();
1426 }
1427 }
1428
1429 void WatcherThread::make_startable() {
1430 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1431 _startable = true;
1432 }
1433
1434 void WatcherThread::stop() {
1435 {
1436 // Follow normal safepoint aware lock enter protocol since the
1437 // WatcherThread is stopped by another JavaThread.
1438 MutexLocker ml(PeriodicTask_lock);
1439 _should_terminate = true;
1440
1441 WatcherThread* watcher = watcher_thread();
1442 if (watcher != NULL) {
1443 // unpark the WatcherThread so it can see that it should terminate
1444 watcher->unpark();
1445 }
1446 }
1447
1448 MutexLocker mu(Terminator_lock);
1449
1450 while (watcher_thread() != NULL) {
1451 // This wait should make safepoint checks, wait without a timeout,
1452 // and wait as a suspend-equivalent condition.
1453 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1454 Mutex::_as_suspend_equivalent_flag);
1455 }
1456 }
1457
1458 void WatcherThread::unpark() {
1459 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1460 PeriodicTask_lock->notify();
1461 }
1462
1463 void WatcherThread::print_on(outputStream* st) const {
1464 st->print("\"%s\" ", name());
1465 Thread::print_on(st);
1466 st->cr();
1467 }
1468
1469 // ======= JavaThread ========
1470
1471 #if INCLUDE_JVMCI
1472
1473 jlong* JavaThread::_jvmci_old_thread_counters;
1474
1475 bool jvmci_counters_include(JavaThread* thread) {
1476 oop threadObj = thread->threadObj();
1477 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1478 }
1479
1480 void JavaThread::collect_counters(typeArrayOop array) {
1481 if (JVMCICounterSize > 0) {
1482 MutexLocker tl(Threads_lock);
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 #if INCLUDE_ALL_GCS
1590 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1591 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1592 #endif // INCLUDE_ALL_GCS
1593
1594 JavaThread::JavaThread(bool is_attaching_via_jni) :
1595 Thread()
1596 #if INCLUDE_ALL_GCS
1597 , _satb_mark_queue(&_satb_mark_queue_set),
1598 _dirty_card_queue(&_dirty_card_queue_set)
1599 #endif // INCLUDE_ALL_GCS
1600 {
1601 initialize();
1602 if (is_attaching_via_jni) {
1603 _jni_attach_state = _attaching_via_jni;
1604 } else {
1605 _jni_attach_state = _not_attaching_via_jni;
1606 }
1607 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1608 }
1609
1610 bool JavaThread::reguard_stack(address cur_sp) {
1611 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1612 && _stack_guard_state != stack_guard_reserved_disabled) {
1613 return true; // Stack already guarded or guard pages not needed.
1614 }
1615
1616 if (register_stack_overflow()) {
1617 // For those architectures which have separate register and
1618 // memory stacks, we must check the register stack to see if
1619 // it has overflowed.
1620 return false;
1621 }
1622
1623 // Java code never executes within the yellow zone: the latter is only
1624 // there to provoke an exception during stack banging. If java code
1625 // is executing there, either StackShadowPages should be larger, or
1626 // some exception code in c1, c2 or the interpreter isn't unwinding
1627 // when it should.
1628 guarantee(cur_sp > stack_reserved_zone_base(),
1629 "not enough space to reguard - increase StackShadowPages");
1630 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1631 enable_stack_yellow_reserved_zone();
1632 if (reserved_stack_activation() != stack_base()) {
1633 set_reserved_stack_activation(stack_base());
1634 }
1635 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1636 set_reserved_stack_activation(stack_base());
1637 enable_stack_reserved_zone();
1638 }
1639 return true;
1640 }
1641
1642 bool JavaThread::reguard_stack(void) {
1643 return reguard_stack(os::current_stack_pointer());
1644 }
1645
1646
1647 void JavaThread::block_if_vm_exited() {
1648 if (_terminated == _vm_exited) {
1649 // _vm_exited is set at safepoint, and Threads_lock is never released
1650 // we will block here forever
1651 Threads_lock->lock_without_safepoint_check();
1652 ShouldNotReachHere();
1653 }
1654 }
1655
1656
1657 // Remove this ifdef when C1 is ported to the compiler interface.
1658 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1659 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1660
1661 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1662 Thread()
1663 #if INCLUDE_ALL_GCS
1664 , _satb_mark_queue(&_satb_mark_queue_set),
1665 _dirty_card_queue(&_dirty_card_queue_set)
1666 #endif // INCLUDE_ALL_GCS
1667 {
1668 initialize();
1669 _jni_attach_state = _not_attaching_via_jni;
1670 set_entry_point(entry_point);
1671 // Create the native thread itself.
1672 // %note runtime_23
1673 os::ThreadType thr_type = os::java_thread;
1674 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1675 os::java_thread;
1676 os::create_thread(this, thr_type, stack_sz);
1677 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1678 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1679 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1680 // the exception consists of creating the exception object & initializing it, initialization
1681 // will leave the VM via a JavaCall and then all locks must be unlocked).
1682 //
1683 // The thread is still suspended when we reach here. Thread must be explicit started
1684 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1685 // by calling Threads:add. The reason why this is not done here, is because the thread
1686 // object must be fully initialized (take a look at JVM_Start)
1687 }
1688
1689 JavaThread::~JavaThread() {
1690
1691 // JSR166 -- return the parker to the free list
1692 Parker::Release(_parker);
1693 _parker = NULL;
1694
1695 // Free any remaining previous UnrollBlock
1696 vframeArray* old_array = vframe_array_last();
1697
1698 if (old_array != NULL) {
1699 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1700 old_array->set_unroll_block(NULL);
1701 delete old_info;
1702 delete old_array;
1703 }
1704
1705 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1706 if (deferred != NULL) {
1707 // This can only happen if thread is destroyed before deoptimization occurs.
1708 assert(deferred->length() != 0, "empty array!");
1709 do {
1710 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1711 deferred->remove_at(0);
1712 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1713 delete dlv;
1714 } while (deferred->length() != 0);
1715 delete deferred;
1716 }
1717
1718 // All Java related clean up happens in exit
1719 ThreadSafepointState::destroy(this);
1720 if (_thread_stat != NULL) delete _thread_stat;
1721
1722 #if INCLUDE_JVMCI
1723 if (JVMCICounterSize > 0) {
1724 if (jvmci_counters_include(this)) {
1725 for (int i = 0; i < JVMCICounterSize; i++) {
1726 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1727 }
1728 }
1729 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1730 }
1731 #endif // INCLUDE_JVMCI
1732 }
1733
1734
1735 // The first routine called by a new Java thread
1736 void JavaThread::run() {
1737 // initialize thread-local alloc buffer related fields
1738 this->initialize_tlab();
1739
1740 // used to test validity of stack trace backs
1741 this->record_base_of_stack_pointer();
1742
1743 // Record real stack base and size.
1744 this->record_stack_base_and_size();
1745
1746 this->create_stack_guard_pages();
1747
1748 this->cache_global_variables();
1749
1750 // Thread is now sufficient initialized to be handled by the safepoint code as being
1751 // in the VM. Change thread state from _thread_new to _thread_in_vm
1752 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1753
1754 assert(JavaThread::current() == this, "sanity check");
1755 assert(!Thread::current()->owns_locks(), "sanity check");
1756
1757 DTRACE_THREAD_PROBE(start, this);
1758
1759 // This operation might block. We call that after all safepoint checks for a new thread has
1760 // been completed.
1761 this->set_active_handles(JNIHandleBlock::allocate_block());
1762
1763 if (JvmtiExport::should_post_thread_life()) {
1764 JvmtiExport::post_thread_start(this);
1765 }
1766
1767 EventThreadStart event;
1768 if (event.should_commit()) {
1769 event.set_thread(THREAD_TRACE_ID(this));
1770 event.commit();
1771 }
1772
1773 // We call another function to do the rest so we are sure that the stack addresses used
1774 // from there will be lower than the stack base just computed
1775 thread_main_inner();
1776
1777 // Note, thread is no longer valid at this point!
1778 }
1779
1780
1781 void JavaThread::thread_main_inner() {
1782 assert(JavaThread::current() == this, "sanity check");
1783 assert(this->threadObj() != NULL, "just checking");
1784
1785 // Execute thread entry point unless this thread has a pending exception
1786 // or has been stopped before starting.
1787 // Note: Due to JVM_StopThread we can have pending exceptions already!
1788 if (!this->has_pending_exception() &&
1789 !java_lang_Thread::is_stillborn(this->threadObj())) {
1790 {
1791 ResourceMark rm(this);
1792 this->set_native_thread_name(this->get_thread_name());
1793 }
1794 HandleMark hm(this);
1795 this->entry_point()(this, this);
1796 }
1797
1798 DTRACE_THREAD_PROBE(stop, this);
1799
1800 this->exit(false);
1801 this->smr_delete();
1802 }
1803
1804
1805 static void ensure_join(JavaThread* thread) {
1806 // We do not need to grab the Threads_lock, since we are operating on ourself.
1807 Handle threadObj(thread, thread->threadObj());
1808 assert(threadObj.not_null(), "java thread object must exist");
1809 ObjectLocker lock(threadObj, thread);
1810 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1811 thread->clear_pending_exception();
1812 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1813 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1814 // Clear the native thread instance - this makes isAlive return false and allows the join()
1815 // to complete once we've done the notify_all below
1816 java_lang_Thread::set_thread(threadObj(), NULL);
1817 lock.notify_all(thread);
1818 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1819 thread->clear_pending_exception();
1820 }
1821
1822
1823 // For any new cleanup additions, please check to see if they need to be applied to
1824 // cleanup_failed_attach_current_thread as well.
1825 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1826 assert(this == JavaThread::current(), "thread consistency check");
1827
1828 elapsedTimer _timer_exit_phase1;
1829 elapsedTimer _timer_exit_phase2;
1830 elapsedTimer _timer_exit_phase3;
1831 elapsedTimer _timer_exit_phase4;
1832
1833 if (log_is_enabled(Debug, os, thread, timer)) {
1834 _timer_exit_phase1.start();
1835 }
1836
1837 HandleMark hm(this);
1838 Handle uncaught_exception(this, this->pending_exception());
1839 this->clear_pending_exception();
1840 Handle threadObj(this, this->threadObj());
1841 assert(threadObj.not_null(), "Java thread object should be created");
1842
1843 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1844 {
1845 EXCEPTION_MARK;
1846
1847 CLEAR_PENDING_EXCEPTION;
1848 }
1849 if (!destroy_vm) {
1850 if (uncaught_exception.not_null()) {
1851 EXCEPTION_MARK;
1852 // Call method Thread.dispatchUncaughtException().
1853 Klass* thread_klass = SystemDictionary::Thread_klass();
1854 JavaValue result(T_VOID);
1855 JavaCalls::call_virtual(&result,
1856 threadObj, thread_klass,
1857 vmSymbols::dispatchUncaughtException_name(),
1858 vmSymbols::throwable_void_signature(),
1859 uncaught_exception,
1860 THREAD);
1861 if (HAS_PENDING_EXCEPTION) {
1862 ResourceMark rm(this);
1863 jio_fprintf(defaultStream::error_stream(),
1864 "\nException: %s thrown from the UncaughtExceptionHandler"
1865 " in thread \"%s\"\n",
1866 pending_exception()->klass()->external_name(),
1867 get_thread_name());
1868 CLEAR_PENDING_EXCEPTION;
1869 }
1870 }
1871
1872 // Called before the java thread exit since we want to read info
1873 // from java_lang_Thread object
1874 EventThreadEnd event;
1875 if (event.should_commit()) {
1876 event.set_thread(THREAD_TRACE_ID(this));
1877 event.commit();
1878 }
1879
1880 // Call after last event on thread
1881 EVENT_THREAD_EXIT(this);
1882
1883 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1884 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1885 // is deprecated anyhow.
1886 if (!is_Compiler_thread()) {
1887 int count = 3;
1888 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1889 EXCEPTION_MARK;
1890 JavaValue result(T_VOID);
1891 Klass* thread_klass = SystemDictionary::Thread_klass();
1892 JavaCalls::call_virtual(&result,
1893 threadObj, thread_klass,
1894 vmSymbols::exit_method_name(),
1895 vmSymbols::void_method_signature(),
1896 THREAD);
1897 CLEAR_PENDING_EXCEPTION;
1898 }
1899 }
1900 // notify JVMTI
1901 if (JvmtiExport::should_post_thread_life()) {
1902 JvmtiExport::post_thread_end(this);
1903 }
1904
1905 // We have notified the agents that we are exiting, before we go on,
1906 // we must check for a pending external suspend request and honor it
1907 // in order to not surprise the thread that made the suspend request.
1908 while (true) {
1909 {
1910 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1911 if (!is_external_suspend()) {
1912 set_terminated(_thread_exiting);
1913 ThreadService::current_thread_exiting(this);
1914 break;
1915 }
1916 // Implied else:
1917 // Things get a little tricky here. We have a pending external
1918 // suspend request, but we are holding the SR_lock so we
1919 // can't just self-suspend. So we temporarily drop the lock
1920 // and then self-suspend.
1921 }
1922
1923 ThreadBlockInVM tbivm(this);
1924 java_suspend_self();
1925
1926 // We're done with this suspend request, but we have to loop around
1927 // and check again. Eventually we will get SR_lock without a pending
1928 // external suspend request and will be able to mark ourselves as
1929 // exiting.
1930 }
1931 // no more external suspends are allowed at this point
1932 } else {
1933 // before_exit() has already posted JVMTI THREAD_END events
1934 }
1935
1936 if (log_is_enabled(Debug, os, thread, timer)) {
1937 _timer_exit_phase1.stop();
1938 _timer_exit_phase2.start();
1939 }
1940 // Notify waiters on thread object. This has to be done after exit() is called
1941 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1942 // group should have the destroyed bit set before waiters are notified).
1943 ensure_join(this);
1944 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1945
1946 if (log_is_enabled(Debug, os, thread, timer)) {
1947 _timer_exit_phase2.stop();
1948 _timer_exit_phase3.start();
1949 }
1950 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1951 // held by this thread must be released. The spec does not distinguish
1952 // between JNI-acquired and regular Java monitors. We can only see
1953 // regular Java monitors here if monitor enter-exit matching is broken.
1954 //
1955 // Optionally release any monitors for regular JavaThread exits. This
1956 // is provided as a work around for any bugs in monitor enter-exit
1957 // matching. This can be expensive so it is not enabled by default.
1958 //
1959 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1960 // ObjectSynchronizer::release_monitors_owned_by_thread().
1961 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1962 // Sanity check even though JNI DetachCurrentThread() would have
1963 // returned JNI_ERR if there was a Java frame. JavaThread exit
1964 // should be done executing Java code by the time we get here.
1965 assert(!this->has_last_Java_frame(),
1966 "should not have a Java frame when detaching or exiting");
1967 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1968 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1969 }
1970
1971 // These things needs to be done while we are still a Java Thread. Make sure that thread
1972 // is in a consistent state, in case GC happens
1973 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1974
1975 if (active_handles() != NULL) {
1976 JNIHandleBlock* block = active_handles();
1977 set_active_handles(NULL);
1978 JNIHandleBlock::release_block(block);
1979 }
1980
1981 if (free_handle_block() != NULL) {
1982 JNIHandleBlock* block = free_handle_block();
1983 set_free_handle_block(NULL);
1984 JNIHandleBlock::release_block(block);
1985 }
1986
1987 // These have to be removed while this is still a valid thread.
1988 remove_stack_guard_pages();
1989
1990 if (UseTLAB) {
1991 tlab().make_parsable(true); // retire TLAB
1992 }
1993
1994 if (JvmtiEnv::environments_might_exist()) {
1995 JvmtiExport::cleanup_thread(this);
1996 }
1997
1998 BarrierSet::barrier_set()->on_thread_detach(this);
1999
2000 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2001 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2002 os::current_thread_id());
2003
2004 if (log_is_enabled(Debug, os, thread, timer)) {
2005 _timer_exit_phase3.stop();
2006 _timer_exit_phase4.start();
2007 }
2008 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2009 Threads::remove(this);
2010
2011 if (log_is_enabled(Debug, os, thread, timer)) {
2012 _timer_exit_phase4.stop();
2013 ResourceMark rm(this);
2014 log_debug(os, thread, timer)("name='%s'"
2015 ", exit-phase1=" JLONG_FORMAT
2016 ", exit-phase2=" JLONG_FORMAT
2017 ", exit-phase3=" JLONG_FORMAT
2018 ", exit-phase4=" JLONG_FORMAT,
2019 get_thread_name(),
2020 _timer_exit_phase1.milliseconds(),
2021 _timer_exit_phase2.milliseconds(),
2022 _timer_exit_phase3.milliseconds(),
2023 _timer_exit_phase4.milliseconds());
2024 }
2025 }
2026
2027 void JavaThread::cleanup_failed_attach_current_thread() {
2028 if (active_handles() != NULL) {
2029 JNIHandleBlock* block = active_handles();
2030 set_active_handles(NULL);
2031 JNIHandleBlock::release_block(block);
2032 }
2033
2034 if (free_handle_block() != NULL) {
2035 JNIHandleBlock* block = free_handle_block();
2036 set_free_handle_block(NULL);
2037 JNIHandleBlock::release_block(block);
2038 }
2039
2040 // These have to be removed while this is still a valid thread.
2041 remove_stack_guard_pages();
2042
2043 if (UseTLAB) {
2044 tlab().make_parsable(true); // retire TLAB, if any
2045 }
2046
2047 BarrierSet::barrier_set()->on_thread_detach(this);
2048
2049 Threads::remove(this);
2050 this->smr_delete();
2051 }
2052
2053 JavaThread* JavaThread::active() {
2054 Thread* thread = Thread::current();
2055 if (thread->is_Java_thread()) {
2056 return (JavaThread*) thread;
2057 } else {
2058 assert(thread->is_VM_thread(), "this must be a vm thread");
2059 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2060 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2061 assert(ret->is_Java_thread(), "must be a Java thread");
2062 return ret;
2063 }
2064 }
2065
2066 bool JavaThread::is_lock_owned(address adr) const {
2067 if (Thread::is_lock_owned(adr)) return true;
2068
2069 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2070 if (chunk->contains(adr)) return true;
2071 }
2072
2073 return false;
2074 }
2075
2076
2077 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2078 chunk->set_next(monitor_chunks());
2079 set_monitor_chunks(chunk);
2080 }
2081
2082 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2083 guarantee(monitor_chunks() != NULL, "must be non empty");
2084 if (monitor_chunks() == chunk) {
2085 set_monitor_chunks(chunk->next());
2086 } else {
2087 MonitorChunk* prev = monitor_chunks();
2088 while (prev->next() != chunk) prev = prev->next();
2089 prev->set_next(chunk->next());
2090 }
2091 }
2092
2093 // JVM support.
2094
2095 // Note: this function shouldn't block if it's called in
2096 // _thread_in_native_trans state (such as from
2097 // check_special_condition_for_native_trans()).
2098 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2099
2100 if (has_last_Java_frame() && has_async_condition()) {
2101 // If we are at a polling page safepoint (not a poll return)
2102 // then we must defer async exception because live registers
2103 // will be clobbered by the exception path. Poll return is
2104 // ok because the call we a returning from already collides
2105 // with exception handling registers and so there is no issue.
2106 // (The exception handling path kills call result registers but
2107 // this is ok since the exception kills the result anyway).
2108
2109 if (is_at_poll_safepoint()) {
2110 // if the code we are returning to has deoptimized we must defer
2111 // the exception otherwise live registers get clobbered on the
2112 // exception path before deoptimization is able to retrieve them.
2113 //
2114 RegisterMap map(this, false);
2115 frame caller_fr = last_frame().sender(&map);
2116 assert(caller_fr.is_compiled_frame(), "what?");
2117 if (caller_fr.is_deoptimized_frame()) {
2118 log_info(exceptions)("deferred async exception at compiled safepoint");
2119 return;
2120 }
2121 }
2122 }
2123
2124 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2125 if (condition == _no_async_condition) {
2126 // Conditions have changed since has_special_runtime_exit_condition()
2127 // was called:
2128 // - if we were here only because of an external suspend request,
2129 // then that was taken care of above (or cancelled) so we are done
2130 // - if we were here because of another async request, then it has
2131 // been cleared between the has_special_runtime_exit_condition()
2132 // and now so again we are done
2133 return;
2134 }
2135
2136 // Check for pending async. exception
2137 if (_pending_async_exception != NULL) {
2138 // Only overwrite an already pending exception, if it is not a threadDeath.
2139 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2140
2141 // We cannot call Exceptions::_throw(...) here because we cannot block
2142 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2143
2144 LogTarget(Info, exceptions) lt;
2145 if (lt.is_enabled()) {
2146 ResourceMark rm;
2147 LogStream ls(lt);
2148 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2149 if (has_last_Java_frame()) {
2150 frame f = last_frame();
2151 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2152 }
2153 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2154 }
2155 _pending_async_exception = NULL;
2156 clear_has_async_exception();
2157 }
2158 }
2159
2160 if (check_unsafe_error &&
2161 condition == _async_unsafe_access_error && !has_pending_exception()) {
2162 condition = _no_async_condition; // done
2163 switch (thread_state()) {
2164 case _thread_in_vm: {
2165 JavaThread* THREAD = this;
2166 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2167 }
2168 case _thread_in_native: {
2169 ThreadInVMfromNative tiv(this);
2170 JavaThread* THREAD = this;
2171 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2172 }
2173 case _thread_in_Java: {
2174 ThreadInVMfromJava tiv(this);
2175 JavaThread* THREAD = this;
2176 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2177 }
2178 default:
2179 ShouldNotReachHere();
2180 }
2181 }
2182
2183 assert(condition == _no_async_condition || has_pending_exception() ||
2184 (!check_unsafe_error && condition == _async_unsafe_access_error),
2185 "must have handled the async condition, if no exception");
2186 }
2187
2188 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2189 //
2190 // Check for pending external suspend. Internal suspend requests do
2191 // not use handle_special_runtime_exit_condition().
2192 // If JNIEnv proxies are allowed, don't self-suspend if the target
2193 // thread is not the current thread. In older versions of jdbx, jdbx
2194 // threads could call into the VM with another thread's JNIEnv so we
2195 // can be here operating on behalf of a suspended thread (4432884).
2196 bool do_self_suspend = is_external_suspend_with_lock();
2197 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2198 //
2199 // Because thread is external suspended the safepoint code will count
2200 // thread as at a safepoint. This can be odd because we can be here
2201 // as _thread_in_Java which would normally transition to _thread_blocked
2202 // at a safepoint. We would like to mark the thread as _thread_blocked
2203 // before calling java_suspend_self like all other callers of it but
2204 // we must then observe proper safepoint protocol. (We can't leave
2205 // _thread_blocked with a safepoint in progress). However we can be
2206 // here as _thread_in_native_trans so we can't use a normal transition
2207 // constructor/destructor pair because they assert on that type of
2208 // transition. We could do something like:
2209 //
2210 // JavaThreadState state = thread_state();
2211 // set_thread_state(_thread_in_vm);
2212 // {
2213 // ThreadBlockInVM tbivm(this);
2214 // java_suspend_self()
2215 // }
2216 // set_thread_state(_thread_in_vm_trans);
2217 // if (safepoint) block;
2218 // set_thread_state(state);
2219 //
2220 // but that is pretty messy. Instead we just go with the way the
2221 // code has worked before and note that this is the only path to
2222 // java_suspend_self that doesn't put the thread in _thread_blocked
2223 // mode.
2224
2225 frame_anchor()->make_walkable(this);
2226 java_suspend_self();
2227
2228 // We might be here for reasons in addition to the self-suspend request
2229 // so check for other async requests.
2230 }
2231
2232 if (check_asyncs) {
2233 check_and_handle_async_exceptions();
2234 }
2235 #if INCLUDE_TRACE
2236 if (is_trace_suspend()) {
2237 TRACE_SUSPEND_THREAD(this);
2238 }
2239 #endif
2240 }
2241
2242 void JavaThread::send_thread_stop(oop java_throwable) {
2243 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2244 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2245 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2246
2247 // Do not throw asynchronous exceptions against the compiler thread
2248 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2249 if (!can_call_java()) return;
2250
2251 {
2252 // Actually throw the Throwable against the target Thread - however
2253 // only if there is no thread death exception installed already.
2254 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2255 // If the topmost frame is a runtime stub, then we are calling into
2256 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2257 // must deoptimize the caller before continuing, as the compiled exception handler table
2258 // may not be valid
2259 if (has_last_Java_frame()) {
2260 frame f = last_frame();
2261 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2262 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2263 RegisterMap reg_map(this, UseBiasedLocking);
2264 frame compiled_frame = f.sender(®_map);
2265 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2266 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2267 }
2268 }
2269 }
2270
2271 // Set async. pending exception in thread.
2272 set_pending_async_exception(java_throwable);
2273
2274 if (log_is_enabled(Info, exceptions)) {
2275 ResourceMark rm;
2276 log_info(exceptions)("Pending Async. exception installed of type: %s",
2277 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2278 }
2279 // for AbortVMOnException flag
2280 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2281 }
2282 }
2283
2284
2285 // Interrupt thread so it will wake up from a potential wait()
2286 Thread::interrupt(this);
2287 }
2288
2289 // External suspension mechanism.
2290 //
2291 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2292 // to any VM_locks and it is at a transition
2293 // Self-suspension will happen on the transition out of the vm.
2294 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2295 //
2296 // Guarantees on return:
2297 // + Target thread will not execute any new bytecode (that's why we need to
2298 // force a safepoint)
2299 // + Target thread will not enter any new monitors
2300 //
2301 void JavaThread::java_suspend() {
2302 ThreadsListHandle tlh;
2303 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2304 return;
2305 }
2306
2307 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2308 if (!is_external_suspend()) {
2309 // a racing resume has cancelled us; bail out now
2310 return;
2311 }
2312
2313 // suspend is done
2314 uint32_t debug_bits = 0;
2315 // Warning: is_ext_suspend_completed() may temporarily drop the
2316 // SR_lock to allow the thread to reach a stable thread state if
2317 // it is currently in a transient thread state.
2318 if (is_ext_suspend_completed(false /* !called_by_wait */,
2319 SuspendRetryDelay, &debug_bits)) {
2320 return;
2321 }
2322 }
2323
2324 VM_ThreadSuspend vm_suspend;
2325 VMThread::execute(&vm_suspend);
2326 }
2327
2328 // Part II of external suspension.
2329 // A JavaThread self suspends when it detects a pending external suspend
2330 // request. This is usually on transitions. It is also done in places
2331 // where continuing to the next transition would surprise the caller,
2332 // e.g., monitor entry.
2333 //
2334 // Returns the number of times that the thread self-suspended.
2335 //
2336 // Note: DO NOT call java_suspend_self() when you just want to block current
2337 // thread. java_suspend_self() is the second stage of cooperative
2338 // suspension for external suspend requests and should only be used
2339 // to complete an external suspend request.
2340 //
2341 int JavaThread::java_suspend_self() {
2342 int ret = 0;
2343
2344 // we are in the process of exiting so don't suspend
2345 if (is_exiting()) {
2346 clear_external_suspend();
2347 return ret;
2348 }
2349
2350 assert(_anchor.walkable() ||
2351 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2352 "must have walkable stack");
2353
2354 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2355
2356 assert(!this->is_ext_suspended(),
2357 "a thread trying to self-suspend should not already be suspended");
2358
2359 if (this->is_suspend_equivalent()) {
2360 // If we are self-suspending as a result of the lifting of a
2361 // suspend equivalent condition, then the suspend_equivalent
2362 // flag is not cleared until we set the ext_suspended flag so
2363 // that wait_for_ext_suspend_completion() returns consistent
2364 // results.
2365 this->clear_suspend_equivalent();
2366 }
2367
2368 // A racing resume may have cancelled us before we grabbed SR_lock
2369 // above. Or another external suspend request could be waiting for us
2370 // by the time we return from SR_lock()->wait(). The thread
2371 // that requested the suspension may already be trying to walk our
2372 // stack and if we return now, we can change the stack out from under
2373 // it. This would be a "bad thing (TM)" and cause the stack walker
2374 // to crash. We stay self-suspended until there are no more pending
2375 // external suspend requests.
2376 while (is_external_suspend()) {
2377 ret++;
2378 this->set_ext_suspended();
2379
2380 // _ext_suspended flag is cleared by java_resume()
2381 while (is_ext_suspended()) {
2382 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2383 }
2384 }
2385
2386 return ret;
2387 }
2388
2389 #ifdef ASSERT
2390 // verify the JavaThread has not yet been published in the Threads::list, and
2391 // hence doesn't need protection from concurrent access at this stage
2392 void JavaThread::verify_not_published() {
2393 ThreadsListHandle tlh;
2394 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
2395 }
2396 #endif
2397
2398 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2399 // progress or when _suspend_flags is non-zero.
2400 // Current thread needs to self-suspend if there is a suspend request and/or
2401 // block if a safepoint is in progress.
2402 // Async exception ISN'T checked.
2403 // Note only the ThreadInVMfromNative transition can call this function
2404 // directly and when thread state is _thread_in_native_trans
2405 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2406 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2407
2408 JavaThread *curJT = JavaThread::current();
2409 bool do_self_suspend = thread->is_external_suspend();
2410
2411 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2412
2413 // If JNIEnv proxies are allowed, don't self-suspend if the target
2414 // thread is not the current thread. In older versions of jdbx, jdbx
2415 // threads could call into the VM with another thread's JNIEnv so we
2416 // can be here operating on behalf of a suspended thread (4432884).
2417 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2418 JavaThreadState state = thread->thread_state();
2419
2420 // We mark this thread_blocked state as a suspend-equivalent so
2421 // that a caller to is_ext_suspend_completed() won't be confused.
2422 // The suspend-equivalent state is cleared by java_suspend_self().
2423 thread->set_suspend_equivalent();
2424
2425 // If the safepoint code sees the _thread_in_native_trans state, it will
2426 // wait until the thread changes to other thread state. There is no
2427 // guarantee on how soon we can obtain the SR_lock and complete the
2428 // self-suspend request. It would be a bad idea to let safepoint wait for
2429 // too long. Temporarily change the state to _thread_blocked to
2430 // let the VM thread know that this thread is ready for GC. The problem
2431 // of changing thread state is that safepoint could happen just after
2432 // java_suspend_self() returns after being resumed, and VM thread will
2433 // see the _thread_blocked state. We must check for safepoint
2434 // after restoring the state and make sure we won't leave while a safepoint
2435 // is in progress.
2436 thread->set_thread_state(_thread_blocked);
2437 thread->java_suspend_self();
2438 thread->set_thread_state(state);
2439
2440 InterfaceSupport::serialize_thread_state_with_handler(thread);
2441 }
2442
2443 SafepointMechanism::block_if_requested(curJT);
2444
2445 if (thread->is_deopt_suspend()) {
2446 thread->clear_deopt_suspend();
2447 RegisterMap map(thread, false);
2448 frame f = thread->last_frame();
2449 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2450 f = f.sender(&map);
2451 }
2452 if (f.id() == thread->must_deopt_id()) {
2453 thread->clear_must_deopt_id();
2454 f.deoptimize(thread);
2455 } else {
2456 fatal("missed deoptimization!");
2457 }
2458 }
2459 #if INCLUDE_TRACE
2460 if (thread->is_trace_suspend()) {
2461 TRACE_SUSPEND_THREAD(thread);
2462 }
2463 #endif
2464 }
2465
2466 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2467 // progress or when _suspend_flags is non-zero.
2468 // Current thread needs to self-suspend if there is a suspend request and/or
2469 // block if a safepoint is in progress.
2470 // Also check for pending async exception (not including unsafe access error).
2471 // Note only the native==>VM/Java barriers can call this function and when
2472 // thread state is _thread_in_native_trans.
2473 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2474 check_safepoint_and_suspend_for_native_trans(thread);
2475
2476 if (thread->has_async_exception()) {
2477 // We are in _thread_in_native_trans state, don't handle unsafe
2478 // access error since that may block.
2479 thread->check_and_handle_async_exceptions(false);
2480 }
2481 }
2482
2483 // This is a variant of the normal
2484 // check_special_condition_for_native_trans with slightly different
2485 // semantics for use by critical native wrappers. It does all the
2486 // normal checks but also performs the transition back into
2487 // thread_in_Java state. This is required so that critical natives
2488 // can potentially block and perform a GC if they are the last thread
2489 // exiting the GCLocker.
2490 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2491 check_special_condition_for_native_trans(thread);
2492
2493 // Finish the transition
2494 thread->set_thread_state(_thread_in_Java);
2495
2496 if (thread->do_critical_native_unlock()) {
2497 ThreadInVMfromJavaNoAsyncException tiv(thread);
2498 GCLocker::unlock_critical(thread);
2499 thread->clear_critical_native_unlock();
2500 }
2501 }
2502
2503 // We need to guarantee the Threads_lock here, since resumes are not
2504 // allowed during safepoint synchronization
2505 // Can only resume from an external suspension
2506 void JavaThread::java_resume() {
2507 assert_locked_or_safepoint(Threads_lock);
2508
2509 // Sanity check: thread is gone, has started exiting or the thread
2510 // was not externally suspended.
2511 ThreadsListHandle tlh;
2512 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2513 return;
2514 }
2515
2516 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2517
2518 clear_external_suspend();
2519
2520 if (is_ext_suspended()) {
2521 clear_ext_suspended();
2522 SR_lock()->notify_all();
2523 }
2524 }
2525
2526 size_t JavaThread::_stack_red_zone_size = 0;
2527 size_t JavaThread::_stack_yellow_zone_size = 0;
2528 size_t JavaThread::_stack_reserved_zone_size = 0;
2529 size_t JavaThread::_stack_shadow_zone_size = 0;
2530
2531 void JavaThread::create_stack_guard_pages() {
2532 if (!os::uses_stack_guard_pages() ||
2533 _stack_guard_state != stack_guard_unused ||
2534 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2535 log_info(os, thread)("Stack guard page creation for thread "
2536 UINTX_FORMAT " disabled", os::current_thread_id());
2537 return;
2538 }
2539 address low_addr = stack_end();
2540 size_t len = stack_guard_zone_size();
2541
2542 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2543 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2544
2545 int must_commit = os::must_commit_stack_guard_pages();
2546 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2547
2548 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2549 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2550 return;
2551 }
2552
2553 if (os::guard_memory((char *) low_addr, len)) {
2554 _stack_guard_state = stack_guard_enabled;
2555 } else {
2556 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2557 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2558 if (os::uncommit_memory((char *) low_addr, len)) {
2559 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2560 }
2561 return;
2562 }
2563
2564 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2565 PTR_FORMAT "-" PTR_FORMAT ".",
2566 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2567 }
2568
2569 void JavaThread::remove_stack_guard_pages() {
2570 assert(Thread::current() == this, "from different thread");
2571 if (_stack_guard_state == stack_guard_unused) return;
2572 address low_addr = stack_end();
2573 size_t len = stack_guard_zone_size();
2574
2575 if (os::must_commit_stack_guard_pages()) {
2576 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2577 _stack_guard_state = stack_guard_unused;
2578 } else {
2579 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2580 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2581 return;
2582 }
2583 } else {
2584 if (_stack_guard_state == stack_guard_unused) return;
2585 if (os::unguard_memory((char *) low_addr, len)) {
2586 _stack_guard_state = stack_guard_unused;
2587 } else {
2588 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2589 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2590 return;
2591 }
2592 }
2593
2594 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2595 PTR_FORMAT "-" PTR_FORMAT ".",
2596 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2597 }
2598
2599 void JavaThread::enable_stack_reserved_zone() {
2600 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2601 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2602
2603 // The base notation is from the stack's point of view, growing downward.
2604 // We need to adjust it to work correctly with guard_memory()
2605 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2606
2607 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2608 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2609
2610 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2611 _stack_guard_state = stack_guard_enabled;
2612 } else {
2613 warning("Attempt to guard stack reserved zone failed.");
2614 }
2615 enable_register_stack_guard();
2616 }
2617
2618 void JavaThread::disable_stack_reserved_zone() {
2619 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2620 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2621
2622 // Simply return if called for a thread that does not use guard pages.
2623 if (_stack_guard_state == stack_guard_unused) return;
2624
2625 // The base notation is from the stack's point of view, growing downward.
2626 // We need to adjust it to work correctly with guard_memory()
2627 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2628
2629 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2630 _stack_guard_state = stack_guard_reserved_disabled;
2631 } else {
2632 warning("Attempt to unguard stack reserved zone failed.");
2633 }
2634 disable_register_stack_guard();
2635 }
2636
2637 void JavaThread::enable_stack_yellow_reserved_zone() {
2638 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2639 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2640
2641 // The base notation is from the stacks point of view, growing downward.
2642 // We need to adjust it to work correctly with guard_memory()
2643 address base = stack_red_zone_base();
2644
2645 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2646 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2647
2648 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2649 _stack_guard_state = stack_guard_enabled;
2650 } else {
2651 warning("Attempt to guard stack yellow zone failed.");
2652 }
2653 enable_register_stack_guard();
2654 }
2655
2656 void JavaThread::disable_stack_yellow_reserved_zone() {
2657 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2658 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2659
2660 // Simply return if called for a thread that does not use guard pages.
2661 if (_stack_guard_state == stack_guard_unused) return;
2662
2663 // The base notation is from the stacks point of view, growing downward.
2664 // We need to adjust it to work correctly with guard_memory()
2665 address base = stack_red_zone_base();
2666
2667 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2668 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2669 } else {
2670 warning("Attempt to unguard stack yellow zone failed.");
2671 }
2672 disable_register_stack_guard();
2673 }
2674
2675 void JavaThread::enable_stack_red_zone() {
2676 // The base notation is from the stacks point of view, growing downward.
2677 // We need to adjust it to work correctly with guard_memory()
2678 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2679 address base = stack_red_zone_base() - stack_red_zone_size();
2680
2681 guarantee(base < stack_base(), "Error calculating stack red zone");
2682 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2683
2684 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2685 warning("Attempt to guard stack red zone failed.");
2686 }
2687 }
2688
2689 void JavaThread::disable_stack_red_zone() {
2690 // The base notation is from the stacks point of view, growing downward.
2691 // We need to adjust it to work correctly with guard_memory()
2692 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2693 address base = stack_red_zone_base() - stack_red_zone_size();
2694 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2695 warning("Attempt to unguard stack red zone failed.");
2696 }
2697 }
2698
2699 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2700 // ignore is there is no stack
2701 if (!has_last_Java_frame()) return;
2702 // traverse the stack frames. Starts from top frame.
2703 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2704 frame* fr = fst.current();
2705 f(fr, fst.register_map());
2706 }
2707 }
2708
2709
2710 #ifndef PRODUCT
2711 // Deoptimization
2712 // Function for testing deoptimization
2713 void JavaThread::deoptimize() {
2714 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2715 StackFrameStream fst(this, UseBiasedLocking);
2716 bool deopt = false; // Dump stack only if a deopt actually happens.
2717 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2718 // Iterate over all frames in the thread and deoptimize
2719 for (; !fst.is_done(); fst.next()) {
2720 if (fst.current()->can_be_deoptimized()) {
2721
2722 if (only_at) {
2723 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2724 // consists of comma or carriage return separated numbers so
2725 // search for the current bci in that string.
2726 address pc = fst.current()->pc();
2727 nmethod* nm = (nmethod*) fst.current()->cb();
2728 ScopeDesc* sd = nm->scope_desc_at(pc);
2729 char buffer[8];
2730 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2731 size_t len = strlen(buffer);
2732 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2733 while (found != NULL) {
2734 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2735 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2736 // Check that the bci found is bracketed by terminators.
2737 break;
2738 }
2739 found = strstr(found + 1, buffer);
2740 }
2741 if (!found) {
2742 continue;
2743 }
2744 }
2745
2746 if (DebugDeoptimization && !deopt) {
2747 deopt = true; // One-time only print before deopt
2748 tty->print_cr("[BEFORE Deoptimization]");
2749 trace_frames();
2750 trace_stack();
2751 }
2752 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2753 }
2754 }
2755
2756 if (DebugDeoptimization && deopt) {
2757 tty->print_cr("[AFTER Deoptimization]");
2758 trace_frames();
2759 }
2760 }
2761
2762
2763 // Make zombies
2764 void JavaThread::make_zombies() {
2765 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2766 if (fst.current()->can_be_deoptimized()) {
2767 // it is a Java nmethod
2768 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2769 nm->make_not_entrant();
2770 }
2771 }
2772 }
2773 #endif // PRODUCT
2774
2775
2776 void JavaThread::deoptimized_wrt_marked_nmethods() {
2777 if (!has_last_Java_frame()) return;
2778 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2779 StackFrameStream fst(this, UseBiasedLocking);
2780 for (; !fst.is_done(); fst.next()) {
2781 if (fst.current()->should_be_deoptimized()) {
2782 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2783 }
2784 }
2785 }
2786
2787
2788 // If the caller is a NamedThread, then remember, in the current scope,
2789 // the given JavaThread in its _processed_thread field.
2790 class RememberProcessedThread: public StackObj {
2791 NamedThread* _cur_thr;
2792 public:
2793 RememberProcessedThread(JavaThread* jthr) {
2794 Thread* thread = Thread::current();
2795 if (thread->is_Named_thread()) {
2796 _cur_thr = (NamedThread *)thread;
2797 _cur_thr->set_processed_thread(jthr);
2798 } else {
2799 _cur_thr = NULL;
2800 }
2801 }
2802
2803 ~RememberProcessedThread() {
2804 if (_cur_thr) {
2805 _cur_thr->set_processed_thread(NULL);
2806 }
2807 }
2808 };
2809
2810 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2811 // Verify that the deferred card marks have been flushed.
2812 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2813
2814 // Traverse the GCHandles
2815 Thread::oops_do(f, cf);
2816
2817 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2818
2819 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2820 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2821
2822 if (has_last_Java_frame()) {
2823 // Record JavaThread to GC thread
2824 RememberProcessedThread rpt(this);
2825
2826 // Traverse the privileged stack
2827 if (_privileged_stack_top != NULL) {
2828 _privileged_stack_top->oops_do(f);
2829 }
2830
2831 // traverse the registered growable array
2832 if (_array_for_gc != NULL) {
2833 for (int index = 0; index < _array_for_gc->length(); index++) {
2834 f->do_oop(_array_for_gc->adr_at(index));
2835 }
2836 }
2837
2838 // Traverse the monitor chunks
2839 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2840 chunk->oops_do(f);
2841 }
2842
2843 // Traverse the execution stack
2844 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2845 fst.current()->oops_do(f, cf, fst.register_map());
2846 }
2847 }
2848
2849 // callee_target is never live across a gc point so NULL it here should
2850 // it still contain a methdOop.
2851
2852 set_callee_target(NULL);
2853
2854 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2855 // If we have deferred set_locals there might be oops waiting to be
2856 // written
2857 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2858 if (list != NULL) {
2859 for (int i = 0; i < list->length(); i++) {
2860 list->at(i)->oops_do(f);
2861 }
2862 }
2863
2864 // Traverse instance variables at the end since the GC may be moving things
2865 // around using this function
2866 f->do_oop((oop*) &_threadObj);
2867 f->do_oop((oop*) &_vm_result);
2868 f->do_oop((oop*) &_exception_oop);
2869 f->do_oop((oop*) &_pending_async_exception);
2870
2871 if (jvmti_thread_state() != NULL) {
2872 jvmti_thread_state()->oops_do(f);
2873 }
2874 }
2875
2876 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2877 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2878 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2879
2880 if (has_last_Java_frame()) {
2881 // Traverse the execution stack
2882 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2883 fst.current()->nmethods_do(cf);
2884 }
2885 }
2886 }
2887
2888 void JavaThread::metadata_do(void f(Metadata*)) {
2889 if (has_last_Java_frame()) {
2890 // Traverse the execution stack to call f() on the methods in the stack
2891 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2892 fst.current()->metadata_do(f);
2893 }
2894 } else if (is_Compiler_thread()) {
2895 // need to walk ciMetadata in current compile tasks to keep alive.
2896 CompilerThread* ct = (CompilerThread*)this;
2897 if (ct->env() != NULL) {
2898 ct->env()->metadata_do(f);
2899 }
2900 CompileTask* task = ct->task();
2901 if (task != NULL) {
2902 task->metadata_do(f);
2903 }
2904 }
2905 }
2906
2907 // Printing
2908 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2909 switch (_thread_state) {
2910 case _thread_uninitialized: return "_thread_uninitialized";
2911 case _thread_new: return "_thread_new";
2912 case _thread_new_trans: return "_thread_new_trans";
2913 case _thread_in_native: return "_thread_in_native";
2914 case _thread_in_native_trans: return "_thread_in_native_trans";
2915 case _thread_in_vm: return "_thread_in_vm";
2916 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2917 case _thread_in_Java: return "_thread_in_Java";
2918 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2919 case _thread_blocked: return "_thread_blocked";
2920 case _thread_blocked_trans: return "_thread_blocked_trans";
2921 default: return "unknown thread state";
2922 }
2923 }
2924
2925 #ifndef PRODUCT
2926 void JavaThread::print_thread_state_on(outputStream *st) const {
2927 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2928 };
2929 void JavaThread::print_thread_state() const {
2930 print_thread_state_on(tty);
2931 }
2932 #endif // PRODUCT
2933
2934 // Called by Threads::print() for VM_PrintThreads operation
2935 void JavaThread::print_on(outputStream *st) const {
2936 st->print_raw("\"");
2937 st->print_raw(get_thread_name());
2938 st->print_raw("\" ");
2939 oop thread_oop = threadObj();
2940 if (thread_oop != NULL) {
2941 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2942 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2943 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2944 }
2945 Thread::print_on(st);
2946 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2947 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2948 if (thread_oop != NULL) {
2949 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2950 }
2951 #ifndef PRODUCT
2952 print_thread_state_on(st);
2953 _safepoint_state->print_on(st);
2954 #endif // PRODUCT
2955 if (is_Compiler_thread()) {
2956 CompileTask *task = ((CompilerThread*)this)->task();
2957 if (task != NULL) {
2958 st->print(" Compiling: ");
2959 task->print(st, NULL, true, false);
2960 } else {
2961 st->print(" No compile task");
2962 }
2963 st->cr();
2964 }
2965 }
2966
2967 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2968 st->print("%s", get_thread_name_string(buf, buflen));
2969 }
2970
2971 // Called by fatal error handler. The difference between this and
2972 // JavaThread::print() is that we can't grab lock or allocate memory.
2973 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2974 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2975 oop thread_obj = threadObj();
2976 if (thread_obj != NULL) {
2977 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2978 }
2979 st->print(" [");
2980 st->print("%s", _get_thread_state_name(_thread_state));
2981 if (osthread()) {
2982 st->print(", id=%d", osthread()->thread_id());
2983 }
2984 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2985 p2i(stack_end()), p2i(stack_base()));
2986 st->print("]");
2987
2988 if (_threads_hazard_ptr != NULL) {
2989 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
2990 }
2991 if (_nested_threads_hazard_ptr != NULL) {
2992 print_nested_threads_hazard_ptrs_on(st);
2993 }
2994 return;
2995 }
2996
2997 // Verification
2998
2999 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3000
3001 void JavaThread::verify() {
3002 // Verify oops in the thread.
3003 oops_do(&VerifyOopClosure::verify_oop, NULL);
3004
3005 // Verify the stack frames.
3006 frames_do(frame_verify);
3007 }
3008
3009 // CR 6300358 (sub-CR 2137150)
3010 // Most callers of this method assume that it can't return NULL but a
3011 // thread may not have a name whilst it is in the process of attaching to
3012 // the VM - see CR 6412693, and there are places where a JavaThread can be
3013 // seen prior to having it's threadObj set (eg JNI attaching threads and
3014 // if vm exit occurs during initialization). These cases can all be accounted
3015 // for such that this method never returns NULL.
3016 const char* JavaThread::get_thread_name() const {
3017 #ifdef ASSERT
3018 // early safepoints can hit while current thread does not yet have TLS
3019 if (!SafepointSynchronize::is_at_safepoint()) {
3020 Thread *cur = Thread::current();
3021 if (!(cur->is_Java_thread() && cur == this)) {
3022 // Current JavaThreads are allowed to get their own name without
3023 // the Threads_lock.
3024 assert_locked_or_safepoint(Threads_lock);
3025 }
3026 }
3027 #endif // ASSERT
3028 return get_thread_name_string();
3029 }
3030
3031 // Returns a non-NULL representation of this thread's name, or a suitable
3032 // descriptive string if there is no set name
3033 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3034 const char* name_str;
3035 oop thread_obj = threadObj();
3036 if (thread_obj != NULL) {
3037 oop name = java_lang_Thread::name(thread_obj);
3038 if (name != NULL) {
3039 if (buf == NULL) {
3040 name_str = java_lang_String::as_utf8_string(name);
3041 } else {
3042 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3043 }
3044 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3045 name_str = "<no-name - thread is attaching>";
3046 } else {
3047 name_str = Thread::name();
3048 }
3049 } else {
3050 name_str = Thread::name();
3051 }
3052 assert(name_str != NULL, "unexpected NULL thread name");
3053 return name_str;
3054 }
3055
3056
3057 const char* JavaThread::get_threadgroup_name() const {
3058 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3059 oop thread_obj = threadObj();
3060 if (thread_obj != NULL) {
3061 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3062 if (thread_group != NULL) {
3063 // ThreadGroup.name can be null
3064 return java_lang_ThreadGroup::name(thread_group);
3065 }
3066 }
3067 return NULL;
3068 }
3069
3070 const char* JavaThread::get_parent_name() const {
3071 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3072 oop thread_obj = threadObj();
3073 if (thread_obj != NULL) {
3074 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3075 if (thread_group != NULL) {
3076 oop parent = java_lang_ThreadGroup::parent(thread_group);
3077 if (parent != NULL) {
3078 // ThreadGroup.name can be null
3079 return java_lang_ThreadGroup::name(parent);
3080 }
3081 }
3082 }
3083 return NULL;
3084 }
3085
3086 ThreadPriority JavaThread::java_priority() const {
3087 oop thr_oop = threadObj();
3088 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3089 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3090 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3091 return priority;
3092 }
3093
3094 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3095
3096 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3097 // Link Java Thread object <-> C++ Thread
3098
3099 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3100 // and put it into a new Handle. The Handle "thread_oop" can then
3101 // be used to pass the C++ thread object to other methods.
3102
3103 // Set the Java level thread object (jthread) field of the
3104 // new thread (a JavaThread *) to C++ thread object using the
3105 // "thread_oop" handle.
3106
3107 // Set the thread field (a JavaThread *) of the
3108 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3109
3110 Handle thread_oop(Thread::current(),
3111 JNIHandles::resolve_non_null(jni_thread));
3112 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3113 "must be initialized");
3114 set_threadObj(thread_oop());
3115 java_lang_Thread::set_thread(thread_oop(), this);
3116
3117 if (prio == NoPriority) {
3118 prio = java_lang_Thread::priority(thread_oop());
3119 assert(prio != NoPriority, "A valid priority should be present");
3120 }
3121
3122 // Push the Java priority down to the native thread; needs Threads_lock
3123 Thread::set_priority(this, prio);
3124
3125 prepare_ext();
3126
3127 // Add the new thread to the Threads list and set it in motion.
3128 // We must have threads lock in order to call Threads::add.
3129 // It is crucial that we do not block before the thread is
3130 // added to the Threads list for if a GC happens, then the java_thread oop
3131 // will not be visited by GC.
3132 Threads::add(this);
3133 }
3134
3135 oop JavaThread::current_park_blocker() {
3136 // Support for JSR-166 locks
3137 oop thread_oop = threadObj();
3138 if (thread_oop != NULL &&
3139 JDK_Version::current().supports_thread_park_blocker()) {
3140 return java_lang_Thread::park_blocker(thread_oop);
3141 }
3142 return NULL;
3143 }
3144
3145
3146 void JavaThread::print_stack_on(outputStream* st) {
3147 if (!has_last_Java_frame()) return;
3148 ResourceMark rm;
3149 HandleMark hm;
3150
3151 RegisterMap reg_map(this);
3152 vframe* start_vf = last_java_vframe(®_map);
3153 int count = 0;
3154 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3155 if (f->is_java_frame()) {
3156 javaVFrame* jvf = javaVFrame::cast(f);
3157 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3158
3159 // Print out lock information
3160 if (JavaMonitorsInStackTrace) {
3161 jvf->print_lock_info_on(st, count);
3162 }
3163 } else {
3164 // Ignore non-Java frames
3165 }
3166
3167 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3168 count++;
3169 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3170 }
3171 }
3172
3173
3174 // JVMTI PopFrame support
3175 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3176 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3177 if (in_bytes(size_in_bytes) != 0) {
3178 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3179 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3180 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3181 }
3182 }
3183
3184 void* JavaThread::popframe_preserved_args() {
3185 return _popframe_preserved_args;
3186 }
3187
3188 ByteSize JavaThread::popframe_preserved_args_size() {
3189 return in_ByteSize(_popframe_preserved_args_size);
3190 }
3191
3192 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3193 int sz = in_bytes(popframe_preserved_args_size());
3194 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3195 return in_WordSize(sz / wordSize);
3196 }
3197
3198 void JavaThread::popframe_free_preserved_args() {
3199 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3200 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3201 _popframe_preserved_args = NULL;
3202 _popframe_preserved_args_size = 0;
3203 }
3204
3205 #ifndef PRODUCT
3206
3207 void JavaThread::trace_frames() {
3208 tty->print_cr("[Describe stack]");
3209 int frame_no = 1;
3210 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3211 tty->print(" %d. ", frame_no++);
3212 fst.current()->print_value_on(tty, this);
3213 tty->cr();
3214 }
3215 }
3216
3217 class PrintAndVerifyOopClosure: public OopClosure {
3218 protected:
3219 template <class T> inline void do_oop_work(T* p) {
3220 oop obj = oopDesc::load_decode_heap_oop(p);
3221 if (obj == NULL) return;
3222 tty->print(INTPTR_FORMAT ": ", p2i(p));
3223 if (oopDesc::is_oop_or_null(obj)) {
3224 if (obj->is_objArray()) {
3225 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3226 } else {
3227 obj->print();
3228 }
3229 } else {
3230 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3231 }
3232 tty->cr();
3233 }
3234 public:
3235 virtual void do_oop(oop* p) { do_oop_work(p); }
3236 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3237 };
3238
3239
3240 static void oops_print(frame* f, const RegisterMap *map) {
3241 PrintAndVerifyOopClosure print;
3242 f->print_value();
3243 f->oops_do(&print, NULL, (RegisterMap*)map);
3244 }
3245
3246 // Print our all the locations that contain oops and whether they are
3247 // valid or not. This useful when trying to find the oldest frame
3248 // where an oop has gone bad since the frame walk is from youngest to
3249 // oldest.
3250 void JavaThread::trace_oops() {
3251 tty->print_cr("[Trace oops]");
3252 frames_do(oops_print);
3253 }
3254
3255
3256 #ifdef ASSERT
3257 // Print or validate the layout of stack frames
3258 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3259 ResourceMark rm;
3260 PRESERVE_EXCEPTION_MARK;
3261 FrameValues values;
3262 int frame_no = 0;
3263 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3264 fst.current()->describe(values, ++frame_no);
3265 if (depth == frame_no) break;
3266 }
3267 if (validate_only) {
3268 values.validate();
3269 } else {
3270 tty->print_cr("[Describe stack layout]");
3271 values.print(this);
3272 }
3273 }
3274 #endif
3275
3276 void JavaThread::trace_stack_from(vframe* start_vf) {
3277 ResourceMark rm;
3278 int vframe_no = 1;
3279 for (vframe* f = start_vf; f; f = f->sender()) {
3280 if (f->is_java_frame()) {
3281 javaVFrame::cast(f)->print_activation(vframe_no++);
3282 } else {
3283 f->print();
3284 }
3285 if (vframe_no > StackPrintLimit) {
3286 tty->print_cr("...<more frames>...");
3287 return;
3288 }
3289 }
3290 }
3291
3292
3293 void JavaThread::trace_stack() {
3294 if (!has_last_Java_frame()) return;
3295 ResourceMark rm;
3296 HandleMark hm;
3297 RegisterMap reg_map(this);
3298 trace_stack_from(last_java_vframe(®_map));
3299 }
3300
3301
3302 #endif // PRODUCT
3303
3304
3305 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3306 assert(reg_map != NULL, "a map must be given");
3307 frame f = last_frame();
3308 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3309 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3310 }
3311 return NULL;
3312 }
3313
3314
3315 Klass* JavaThread::security_get_caller_class(int depth) {
3316 vframeStream vfst(this);
3317 vfst.security_get_caller_frame(depth);
3318 if (!vfst.at_end()) {
3319 return vfst.method()->method_holder();
3320 }
3321 return NULL;
3322 }
3323
3324 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3325 assert(thread->is_Compiler_thread(), "must be compiler thread");
3326 CompileBroker::compiler_thread_loop();
3327 }
3328
3329 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3330 NMethodSweeper::sweeper_loop();
3331 }
3332
3333 // Create a CompilerThread
3334 CompilerThread::CompilerThread(CompileQueue* queue,
3335 CompilerCounters* counters)
3336 : JavaThread(&compiler_thread_entry) {
3337 _env = NULL;
3338 _log = NULL;
3339 _task = NULL;
3340 _queue = queue;
3341 _counters = counters;
3342 _buffer_blob = NULL;
3343 _compiler = NULL;
3344
3345 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3346 resource_area()->bias_to(mtCompiler);
3347
3348 #ifndef PRODUCT
3349 _ideal_graph_printer = NULL;
3350 #endif
3351 }
3352
3353 bool CompilerThread::can_call_java() const {
3354 return _compiler != NULL && _compiler->is_jvmci();
3355 }
3356
3357 // Create sweeper thread
3358 CodeCacheSweeperThread::CodeCacheSweeperThread()
3359 : JavaThread(&sweeper_thread_entry) {
3360 _scanned_compiled_method = NULL;
3361 }
3362
3363 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3364 JavaThread::oops_do(f, cf);
3365 if (_scanned_compiled_method != NULL && cf != NULL) {
3366 // Safepoints can occur when the sweeper is scanning an nmethod so
3367 // process it here to make sure it isn't unloaded in the middle of
3368 // a scan.
3369 cf->do_code_blob(_scanned_compiled_method);
3370 }
3371 }
3372
3373 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3374 JavaThread::nmethods_do(cf);
3375 if (_scanned_compiled_method != NULL && cf != NULL) {
3376 // Safepoints can occur when the sweeper is scanning an nmethod so
3377 // process it here to make sure it isn't unloaded in the middle of
3378 // a scan.
3379 cf->do_code_blob(_scanned_compiled_method);
3380 }
3381 }
3382
3383
3384 // ======= Threads ========
3385
3386 // The Threads class links together all active threads, and provides
3387 // operations over all threads. It is protected by the Threads_lock,
3388 // which is also used in other global contexts like safepointing.
3389 // ThreadsListHandles are used to safely perform operations on one
3390 // or more threads without the risk of the thread exiting during the
3391 // operation.
3392 //
3393 // Note: The Threads_lock is currently more widely used than we
3394 // would like. We are actively migrating Threads_lock uses to other
3395 // mechanisms in order to reduce Threads_lock contention.
3396
3397 JavaThread* Threads::_thread_list = NULL;
3398 int Threads::_number_of_threads = 0;
3399 int Threads::_number_of_non_daemon_threads = 0;
3400 int Threads::_return_code = 0;
3401 int Threads::_thread_claim_parity = 0;
3402 size_t JavaThread::_stack_size_at_create = 0;
3403
3404 #ifdef ASSERT
3405 bool Threads::_vm_complete = false;
3406 #endif
3407
3408 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3409 Prefetch::read((void*)addr, prefetch_interval);
3410 return *addr;
3411 }
3412
3413 // Possibly the ugliest for loop the world has seen. C++ does not allow
3414 // multiple types in the declaration section of the for loop. In this case
3415 // we are only dealing with pointers and hence can cast them. It looks ugly
3416 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3417 #define DO_JAVA_THREADS(LIST, X) \
3418 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3419 *MACRO_list = (JavaThread*)(LIST), \
3420 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3421 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3422 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3423 MACRO_current_p != MACRO_end; \
3424 MACRO_current_p++, \
3425 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3426
3427 // All JavaThreads
3428 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3429
3430 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3431 void Threads::threads_do(ThreadClosure* tc) {
3432 assert_locked_or_safepoint(Threads_lock);
3433 // ALL_JAVA_THREADS iterates through all JavaThreads
3434 ALL_JAVA_THREADS(p) {
3435 tc->do_thread(p);
3436 }
3437 // Someday we could have a table or list of all non-JavaThreads.
3438 // For now, just manually iterate through them.
3439 tc->do_thread(VMThread::vm_thread());
3440 Universe::heap()->gc_threads_do(tc);
3441 WatcherThread *wt = WatcherThread::watcher_thread();
3442 // Strictly speaking, the following NULL check isn't sufficient to make sure
3443 // the data for WatcherThread is still valid upon being examined. However,
3444 // considering that WatchThread terminates when the VM is on the way to
3445 // exit at safepoint, the chance of the above is extremely small. The right
3446 // way to prevent termination of WatcherThread would be to acquire
3447 // Terminator_lock, but we can't do that without violating the lock rank
3448 // checking in some cases.
3449 if (wt != NULL) {
3450 tc->do_thread(wt);
3451 }
3452
3453 // If CompilerThreads ever become non-JavaThreads, add them here
3454 }
3455
3456 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3457 int cp = Threads::thread_claim_parity();
3458 ALL_JAVA_THREADS(p) {
3459 if (p->claim_oops_do(is_par, cp)) {
3460 tc->do_thread(p);
3461 }
3462 }
3463 VMThread* vmt = VMThread::vm_thread();
3464 if (vmt->claim_oops_do(is_par, cp)) {
3465 tc->do_thread(vmt);
3466 }
3467 }
3468
3469 // The system initialization in the library has three phases.
3470 //
3471 // Phase 1: java.lang.System class initialization
3472 // java.lang.System is a primordial class loaded and initialized
3473 // by the VM early during startup. java.lang.System.<clinit>
3474 // only does registerNatives and keeps the rest of the class
3475 // initialization work later until thread initialization completes.
3476 //
3477 // System.initPhase1 initializes the system properties, the static
3478 // fields in, out, and err. Set up java signal handlers, OS-specific
3479 // system settings, and thread group of the main thread.
3480 static void call_initPhase1(TRAPS) {
3481 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3482 JavaValue result(T_VOID);
3483 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3484 vmSymbols::void_method_signature(), CHECK);
3485 }
3486
3487 // Phase 2. Module system initialization
3488 // This will initialize the module system. Only java.base classes
3489 // can be loaded until phase 2 completes.
3490 //
3491 // Call System.initPhase2 after the compiler initialization and jsr292
3492 // classes get initialized because module initialization runs a lot of java
3493 // code, that for performance reasons, should be compiled. Also, this will
3494 // enable the startup code to use lambda and other language features in this
3495 // phase and onward.
3496 //
3497 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3498 static void call_initPhase2(TRAPS) {
3499 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3500
3501 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3502
3503 JavaValue result(T_INT);
3504 JavaCallArguments args;
3505 args.push_int(DisplayVMOutputToStderr);
3506 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3507 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3508 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3509 if (result.get_jint() != JNI_OK) {
3510 vm_exit_during_initialization(); // no message or exception
3511 }
3512
3513 universe_post_module_init();
3514 }
3515
3516 // Phase 3. final setup - set security manager, system class loader and TCCL
3517 //
3518 // This will instantiate and set the security manager, set the system class
3519 // loader as well as the thread context class loader. The security manager
3520 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3521 // other modules or the application's classpath.
3522 static void call_initPhase3(TRAPS) {
3523 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3524 JavaValue result(T_VOID);
3525 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3526 vmSymbols::void_method_signature(), CHECK);
3527 }
3528
3529 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3530 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3531
3532 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3533 create_vm_init_libraries();
3534 }
3535
3536 initialize_class(vmSymbols::java_lang_String(), CHECK);
3537
3538 // Inject CompactStrings value after the static initializers for String ran.
3539 java_lang_String::set_compact_strings(CompactStrings);
3540
3541 // Initialize java_lang.System (needed before creating the thread)
3542 initialize_class(vmSymbols::java_lang_System(), CHECK);
3543 // The VM creates & returns objects of this class. Make sure it's initialized.
3544 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3545 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3546 Handle thread_group = create_initial_thread_group(CHECK);
3547 Universe::set_main_thread_group(thread_group());
3548 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3549 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3550 main_thread->set_threadObj(thread_object);
3551 // Set thread status to running since main thread has
3552 // been started and running.
3553 java_lang_Thread::set_thread_status(thread_object,
3554 java_lang_Thread::RUNNABLE);
3555
3556 // The VM creates objects of this class.
3557 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3558
3559 // The VM preresolves methods to these classes. Make sure that they get initialized
3560 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3561 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3562
3563 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3564 call_initPhase1(CHECK);
3565
3566 // get the Java runtime name after java.lang.System is initialized
3567 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3568 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3569
3570 // an instance of OutOfMemory exception has been allocated earlier
3571 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3572 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3573 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3574 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3575 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3576 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3577 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3578 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3579 }
3580
3581 void Threads::initialize_jsr292_core_classes(TRAPS) {
3582 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3583
3584 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3585 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3586 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3587 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3588 }
3589
3590 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3591 extern void JDK_Version_init();
3592
3593 // Preinitialize version info.
3594 VM_Version::early_initialize();
3595
3596 // Check version
3597 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3598
3599 // Initialize library-based TLS
3600 ThreadLocalStorage::init();
3601
3602 // Initialize the output stream module
3603 ostream_init();
3604
3605 // Process java launcher properties.
3606 Arguments::process_sun_java_launcher_properties(args);
3607
3608 // Initialize the os module
3609 os::init();
3610
3611 // Record VM creation timing statistics
3612 TraceVmCreationTime create_vm_timer;
3613 create_vm_timer.start();
3614
3615 // Initialize system properties.
3616 Arguments::init_system_properties();
3617
3618 // So that JDK version can be used as a discriminator when parsing arguments
3619 JDK_Version_init();
3620
3621 // Update/Initialize System properties after JDK version number is known
3622 Arguments::init_version_specific_system_properties();
3623
3624 // Make sure to initialize log configuration *before* parsing arguments
3625 LogConfiguration::initialize(create_vm_timer.begin_time());
3626
3627 // Parse arguments
3628 // Note: this internally calls os::init_container_support()
3629 jint parse_result = Arguments::parse(args);
3630 if (parse_result != JNI_OK) return parse_result;
3631
3632 os::init_before_ergo();
3633
3634 jint ergo_result = Arguments::apply_ergo();
3635 if (ergo_result != JNI_OK) return ergo_result;
3636
3637 // Final check of all ranges after ergonomics which may change values.
3638 if (!CommandLineFlagRangeList::check_ranges()) {
3639 return JNI_EINVAL;
3640 }
3641
3642 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3643 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3644 if (!constraint_result) {
3645 return JNI_EINVAL;
3646 }
3647
3648 CommandLineFlagWriteableList::mark_startup();
3649
3650 if (PauseAtStartup) {
3651 os::pause();
3652 }
3653
3654 HOTSPOT_VM_INIT_BEGIN();
3655
3656 // Timing (must come after argument parsing)
3657 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3658
3659 // Initialize the os module after parsing the args
3660 jint os_init_2_result = os::init_2();
3661 if (os_init_2_result != JNI_OK) return os_init_2_result;
3662
3663 SafepointMechanism::initialize();
3664
3665 jint adjust_after_os_result = Arguments::adjust_after_os();
3666 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3667
3668 // Initialize output stream logging
3669 ostream_init_log();
3670
3671 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3672 // Must be before create_vm_init_agents()
3673 if (Arguments::init_libraries_at_startup()) {
3674 convert_vm_init_libraries_to_agents();
3675 }
3676
3677 // Launch -agentlib/-agentpath and converted -Xrun agents
3678 if (Arguments::init_agents_at_startup()) {
3679 create_vm_init_agents();
3680 }
3681
3682 // Initialize Threads state
3683 _thread_list = NULL;
3684 _number_of_threads = 0;
3685 _number_of_non_daemon_threads = 0;
3686
3687 // Initialize global data structures and create system classes in heap
3688 vm_init_globals();
3689
3690 #if INCLUDE_JVMCI
3691 if (JVMCICounterSize > 0) {
3692 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3693 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3694 } else {
3695 JavaThread::_jvmci_old_thread_counters = NULL;
3696 }
3697 #endif // INCLUDE_JVMCI
3698
3699 // Attach the main thread to this os thread
3700 JavaThread* main_thread = new JavaThread();
3701 main_thread->set_thread_state(_thread_in_vm);
3702 main_thread->initialize_thread_current();
3703 // must do this before set_active_handles
3704 main_thread->record_stack_base_and_size();
3705 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3706
3707 if (!main_thread->set_as_starting_thread()) {
3708 vm_shutdown_during_initialization(
3709 "Failed necessary internal allocation. Out of swap space");
3710 main_thread->smr_delete();
3711 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3712 return JNI_ENOMEM;
3713 }
3714
3715 // Enable guard page *after* os::create_main_thread(), otherwise it would
3716 // crash Linux VM, see notes in os_linux.cpp.
3717 main_thread->create_stack_guard_pages();
3718
3719 // Initialize Java-Level synchronization subsystem
3720 ObjectMonitor::Initialize();
3721
3722 // Initialize global modules
3723 jint status = init_globals();
3724 if (status != JNI_OK) {
3725 main_thread->smr_delete();
3726 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3727 return status;
3728 }
3729
3730 if (TRACE_INITIALIZE() != JNI_OK) {
3731 vm_exit_during_initialization("Failed to initialize tracing backend");
3732 }
3733
3734 // Should be done after the heap is fully created
3735 main_thread->cache_global_variables();
3736
3737 HandleMark hm;
3738
3739 { MutexLocker mu(Threads_lock);
3740 Threads::add(main_thread);
3741 }
3742
3743 // Any JVMTI raw monitors entered in onload will transition into
3744 // real raw monitor. VM is setup enough here for raw monitor enter.
3745 JvmtiExport::transition_pending_onload_raw_monitors();
3746
3747 // Create the VMThread
3748 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3749
3750 VMThread::create();
3751 Thread* vmthread = VMThread::vm_thread();
3752
3753 if (!os::create_thread(vmthread, os::vm_thread)) {
3754 vm_exit_during_initialization("Cannot create VM thread. "
3755 "Out of system resources.");
3756 }
3757
3758 // Wait for the VM thread to become ready, and VMThread::run to initialize
3759 // Monitors can have spurious returns, must always check another state flag
3760 {
3761 MutexLocker ml(Notify_lock);
3762 os::start_thread(vmthread);
3763 while (vmthread->active_handles() == NULL) {
3764 Notify_lock->wait();
3765 }
3766 }
3767 }
3768
3769 assert(Universe::is_fully_initialized(), "not initialized");
3770 if (VerifyDuringStartup) {
3771 // Make sure we're starting with a clean slate.
3772 VM_Verify verify_op;
3773 VMThread::execute(&verify_op);
3774 }
3775
3776 Thread* THREAD = Thread::current();
3777
3778 // Always call even when there are not JVMTI environments yet, since environments
3779 // may be attached late and JVMTI must track phases of VM execution
3780 JvmtiExport::enter_early_start_phase();
3781
3782 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3783 JvmtiExport::post_early_vm_start();
3784
3785 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3786
3787 // We need this for ClassDataSharing - the initial vm.info property is set
3788 // with the default value of CDS "sharing" which may be reset through
3789 // command line options.
3790 reset_vm_info_property(CHECK_JNI_ERR);
3791
3792 quicken_jni_functions();
3793
3794 // No more stub generation allowed after that point.
3795 StubCodeDesc::freeze();
3796
3797 // Set flag that basic initialization has completed. Used by exceptions and various
3798 // debug stuff, that does not work until all basic classes have been initialized.
3799 set_init_completed();
3800
3801 LogConfiguration::post_initialize();
3802 Metaspace::post_initialize();
3803
3804 HOTSPOT_VM_INIT_END();
3805
3806 // record VM initialization completion time
3807 #if INCLUDE_MANAGEMENT
3808 Management::record_vm_init_completed();
3809 #endif // INCLUDE_MANAGEMENT
3810
3811 // Signal Dispatcher needs to be started before VMInit event is posted
3812 os::signal_init(CHECK_JNI_ERR);
3813
3814 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3815 if (!DisableAttachMechanism) {
3816 AttachListener::vm_start();
3817 if (StartAttachListener || AttachListener::init_at_startup()) {
3818 AttachListener::init();
3819 }
3820 }
3821
3822 // Launch -Xrun agents
3823 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3824 // back-end can launch with -Xdebug -Xrunjdwp.
3825 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3826 create_vm_init_libraries();
3827 }
3828
3829 if (CleanChunkPoolAsync) {
3830 Chunk::start_chunk_pool_cleaner_task();
3831 }
3832
3833 // initialize compiler(s)
3834 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3835 CompileBroker::compilation_init(CHECK_JNI_ERR);
3836 #endif
3837
3838 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3839 // It is done after compilers are initialized, because otherwise compilations of
3840 // signature polymorphic MH intrinsics can be missed
3841 // (see SystemDictionary::find_method_handle_intrinsic).
3842 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3843
3844 // This will initialize the module system. Only java.base classes can be
3845 // loaded until phase 2 completes
3846 call_initPhase2(CHECK_JNI_ERR);
3847
3848 // Always call even when there are not JVMTI environments yet, since environments
3849 // may be attached late and JVMTI must track phases of VM execution
3850 JvmtiExport::enter_start_phase();
3851
3852 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3853 JvmtiExport::post_vm_start();
3854
3855 // Final system initialization including security manager and system class loader
3856 call_initPhase3(CHECK_JNI_ERR);
3857
3858 // cache the system and platform class loaders
3859 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3860
3861 #if INCLUDE_JVMCI
3862 if (EnableJVMCI) {
3863 // Initialize JVMCI eagerly when it is explicitly requested.
3864 // Or when JVMCIPrintProperties is enabled.
3865 // The JVMCI Java initialization code will read this flag and
3866 // do the printing if it's set.
3867 bool init = EagerJVMCI || JVMCIPrintProperties;
3868
3869 if (!init) {
3870 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3871 // compilations via JVMCI will not actually block until JVMCI is initialized.
3872 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3873 }
3874
3875 if (init) {
3876 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3877 }
3878 }
3879 #endif
3880
3881 // Always call even when there are not JVMTI environments yet, since environments
3882 // may be attached late and JVMTI must track phases of VM execution
3883 JvmtiExport::enter_live_phase();
3884
3885 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3886 JvmtiExport::post_vm_initialized();
3887
3888 if (TRACE_START() != JNI_OK) {
3889 vm_exit_during_initialization("Failed to start tracing backend.");
3890 }
3891
3892 #if INCLUDE_MANAGEMENT
3893 Management::initialize(THREAD);
3894
3895 if (HAS_PENDING_EXCEPTION) {
3896 // management agent fails to start possibly due to
3897 // configuration problem and is responsible for printing
3898 // stack trace if appropriate. Simply exit VM.
3899 vm_exit(1);
3900 }
3901 #endif // INCLUDE_MANAGEMENT
3902
3903 if (MemProfiling) MemProfiler::engage();
3904 StatSampler::engage();
3905 if (CheckJNICalls) JniPeriodicChecker::engage();
3906
3907 BiasedLocking::init();
3908
3909 #if INCLUDE_RTM_OPT
3910 RTMLockingCounters::init();
3911 #endif
3912
3913 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3914 call_postVMInitHook(THREAD);
3915 // The Java side of PostVMInitHook.run must deal with all
3916 // exceptions and provide means of diagnosis.
3917 if (HAS_PENDING_EXCEPTION) {
3918 CLEAR_PENDING_EXCEPTION;
3919 }
3920 }
3921
3922 {
3923 MutexLocker ml(PeriodicTask_lock);
3924 // Make sure the WatcherThread can be started by WatcherThread::start()
3925 // or by dynamic enrollment.
3926 WatcherThread::make_startable();
3927 // Start up the WatcherThread if there are any periodic tasks
3928 // NOTE: All PeriodicTasks should be registered by now. If they
3929 // aren't, late joiners might appear to start slowly (we might
3930 // take a while to process their first tick).
3931 if (PeriodicTask::num_tasks() > 0) {
3932 WatcherThread::start();
3933 }
3934 }
3935
3936 create_vm_timer.end();
3937 #ifdef ASSERT
3938 _vm_complete = true;
3939 #endif
3940
3941 if (DumpSharedSpaces) {
3942 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3943 ShouldNotReachHere();
3944 }
3945
3946 return JNI_OK;
3947 }
3948
3949 // type for the Agent_OnLoad and JVM_OnLoad entry points
3950 extern "C" {
3951 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3952 }
3953 // Find a command line agent library and return its entry point for
3954 // -agentlib: -agentpath: -Xrun
3955 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3956 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3957 const char *on_load_symbols[],
3958 size_t num_symbol_entries) {
3959 OnLoadEntry_t on_load_entry = NULL;
3960 void *library = NULL;
3961
3962 if (!agent->valid()) {
3963 char buffer[JVM_MAXPATHLEN];
3964 char ebuf[1024] = "";
3965 const char *name = agent->name();
3966 const char *msg = "Could not find agent library ";
3967
3968 // First check to see if agent is statically linked into executable
3969 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3970 library = agent->os_lib();
3971 } else if (agent->is_absolute_path()) {
3972 library = os::dll_load(name, ebuf, sizeof ebuf);
3973 if (library == NULL) {
3974 const char *sub_msg = " in absolute path, with error: ";
3975 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3976 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3977 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3978 // If we can't find the agent, exit.
3979 vm_exit_during_initialization(buf, NULL);
3980 FREE_C_HEAP_ARRAY(char, buf);
3981 }
3982 } else {
3983 // Try to load the agent from the standard dll directory
3984 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3985 name)) {
3986 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3987 }
3988 if (library == NULL) { // Try the library path directory.
3989 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3990 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3991 }
3992 if (library == NULL) {
3993 const char *sub_msg = " on the library path, with error: ";
3994 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
3995
3996 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
3997 strlen(ebuf) + strlen(sub_msg2) + 1;
3998 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3999 if (!agent->is_instrument_lib()) {
4000 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4001 } else {
4002 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4003 }
4004 // If we can't find the agent, exit.
4005 vm_exit_during_initialization(buf, NULL);
4006 FREE_C_HEAP_ARRAY(char, buf);
4007 }
4008 }
4009 }
4010 agent->set_os_lib(library);
4011 agent->set_valid();
4012 }
4013
4014 // Find the OnLoad function.
4015 on_load_entry =
4016 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4017 false,
4018 on_load_symbols,
4019 num_symbol_entries));
4020 return on_load_entry;
4021 }
4022
4023 // Find the JVM_OnLoad entry point
4024 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4025 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4026 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4027 }
4028
4029 // Find the Agent_OnLoad entry point
4030 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4031 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4032 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4033 }
4034
4035 // For backwards compatibility with -Xrun
4036 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4037 // treated like -agentpath:
4038 // Must be called before agent libraries are created
4039 void Threads::convert_vm_init_libraries_to_agents() {
4040 AgentLibrary* agent;
4041 AgentLibrary* next;
4042
4043 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4044 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4045 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4046
4047 // If there is an JVM_OnLoad function it will get called later,
4048 // otherwise see if there is an Agent_OnLoad
4049 if (on_load_entry == NULL) {
4050 on_load_entry = lookup_agent_on_load(agent);
4051 if (on_load_entry != NULL) {
4052 // switch it to the agent list -- so that Agent_OnLoad will be called,
4053 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4054 Arguments::convert_library_to_agent(agent);
4055 } else {
4056 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4057 }
4058 }
4059 }
4060 }
4061
4062 // Create agents for -agentlib: -agentpath: and converted -Xrun
4063 // Invokes Agent_OnLoad
4064 // Called very early -- before JavaThreads exist
4065 void Threads::create_vm_init_agents() {
4066 extern struct JavaVM_ main_vm;
4067 AgentLibrary* agent;
4068
4069 JvmtiExport::enter_onload_phase();
4070
4071 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4072 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4073
4074 if (on_load_entry != NULL) {
4075 // Invoke the Agent_OnLoad function
4076 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4077 if (err != JNI_OK) {
4078 vm_exit_during_initialization("agent library failed to init", agent->name());
4079 }
4080 } else {
4081 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4082 }
4083 }
4084 JvmtiExport::enter_primordial_phase();
4085 }
4086
4087 extern "C" {
4088 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4089 }
4090
4091 void Threads::shutdown_vm_agents() {
4092 // Send any Agent_OnUnload notifications
4093 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4094 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4095 extern struct JavaVM_ main_vm;
4096 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4097
4098 // Find the Agent_OnUnload function.
4099 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4100 os::find_agent_function(agent,
4101 false,
4102 on_unload_symbols,
4103 num_symbol_entries));
4104
4105 // Invoke the Agent_OnUnload function
4106 if (unload_entry != NULL) {
4107 JavaThread* thread = JavaThread::current();
4108 ThreadToNativeFromVM ttn(thread);
4109 HandleMark hm(thread);
4110 (*unload_entry)(&main_vm);
4111 }
4112 }
4113 }
4114
4115 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4116 // Invokes JVM_OnLoad
4117 void Threads::create_vm_init_libraries() {
4118 extern struct JavaVM_ main_vm;
4119 AgentLibrary* agent;
4120
4121 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4122 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4123
4124 if (on_load_entry != NULL) {
4125 // Invoke the JVM_OnLoad function
4126 JavaThread* thread = JavaThread::current();
4127 ThreadToNativeFromVM ttn(thread);
4128 HandleMark hm(thread);
4129 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4130 if (err != JNI_OK) {
4131 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4132 }
4133 } else {
4134 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4135 }
4136 }
4137 }
4138
4139
4140 // Last thread running calls java.lang.Shutdown.shutdown()
4141 void JavaThread::invoke_shutdown_hooks() {
4142 HandleMark hm(this);
4143
4144 // We could get here with a pending exception, if so clear it now.
4145 if (this->has_pending_exception()) {
4146 this->clear_pending_exception();
4147 }
4148
4149 EXCEPTION_MARK;
4150 Klass* shutdown_klass =
4151 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4152 THREAD);
4153 if (shutdown_klass != NULL) {
4154 // SystemDictionary::resolve_or_null will return null if there was
4155 // an exception. If we cannot load the Shutdown class, just don't
4156 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4157 // and finalizers (if runFinalizersOnExit is set) won't be run.
4158 // Note that if a shutdown hook was registered or runFinalizersOnExit
4159 // was called, the Shutdown class would have already been loaded
4160 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4161 JavaValue result(T_VOID);
4162 JavaCalls::call_static(&result,
4163 shutdown_klass,
4164 vmSymbols::shutdown_method_name(),
4165 vmSymbols::void_method_signature(),
4166 THREAD);
4167 }
4168 CLEAR_PENDING_EXCEPTION;
4169 }
4170
4171 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4172 // the program falls off the end of main(). Another VM exit path is through
4173 // vm_exit() when the program calls System.exit() to return a value or when
4174 // there is a serious error in VM. The two shutdown paths are not exactly
4175 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4176 // and VM_Exit op at VM level.
4177 //
4178 // Shutdown sequence:
4179 // + Shutdown native memory tracking if it is on
4180 // + Wait until we are the last non-daemon thread to execute
4181 // <-- every thing is still working at this moment -->
4182 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4183 // shutdown hooks, run finalizers if finalization-on-exit
4184 // + Call before_exit(), prepare for VM exit
4185 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4186 // currently the only user of this mechanism is File.deleteOnExit())
4187 // > stop StatSampler, watcher thread, CMS threads,
4188 // post thread end and vm death events to JVMTI,
4189 // stop signal thread
4190 // + Call JavaThread::exit(), it will:
4191 // > release JNI handle blocks, remove stack guard pages
4192 // > remove this thread from Threads list
4193 // <-- no more Java code from this thread after this point -->
4194 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4195 // the compiler threads at safepoint
4196 // <-- do not use anything that could get blocked by Safepoint -->
4197 // + Disable tracing at JNI/JVM barriers
4198 // + Set _vm_exited flag for threads that are still running native code
4199 // + Delete this thread
4200 // + Call exit_globals()
4201 // > deletes tty
4202 // > deletes PerfMemory resources
4203 // + Return to caller
4204
4205 bool Threads::destroy_vm() {
4206 JavaThread* thread = JavaThread::current();
4207
4208 #ifdef ASSERT
4209 _vm_complete = false;
4210 #endif
4211 // Wait until we are the last non-daemon thread to execute
4212 { MutexLocker nu(Threads_lock);
4213 while (Threads::number_of_non_daemon_threads() > 1)
4214 // This wait should make safepoint checks, wait without a timeout,
4215 // and wait as a suspend-equivalent condition.
4216 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4217 Mutex::_as_suspend_equivalent_flag);
4218 }
4219
4220 EventShutdown e;
4221 if (e.should_commit()) {
4222 e.set_reason("No remaining non-daemon Java threads");
4223 e.commit();
4224 }
4225
4226 // Hang forever on exit if we are reporting an error.
4227 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4228 os::infinite_sleep();
4229 }
4230 os::wait_for_keypress_at_exit();
4231
4232 // run Java level shutdown hooks
4233 thread->invoke_shutdown_hooks();
4234
4235 before_exit(thread);
4236
4237 thread->exit(true);
4238
4239 // Stop VM thread.
4240 {
4241 // 4945125 The vm thread comes to a safepoint during exit.
4242 // GC vm_operations can get caught at the safepoint, and the
4243 // heap is unparseable if they are caught. Grab the Heap_lock
4244 // to prevent this. The GC vm_operations will not be able to
4245 // queue until after the vm thread is dead. After this point,
4246 // we'll never emerge out of the safepoint before the VM exits.
4247
4248 MutexLocker ml(Heap_lock);
4249
4250 VMThread::wait_for_vm_thread_exit();
4251 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4252 VMThread::destroy();
4253 }
4254
4255 // clean up ideal graph printers
4256 #if defined(COMPILER2) && !defined(PRODUCT)
4257 IdealGraphPrinter::clean_up();
4258 #endif
4259
4260 // Now, all Java threads are gone except daemon threads. Daemon threads
4261 // running Java code or in VM are stopped by the Safepoint. However,
4262 // daemon threads executing native code are still running. But they
4263 // will be stopped at native=>Java/VM barriers. Note that we can't
4264 // simply kill or suspend them, as it is inherently deadlock-prone.
4265
4266 VM_Exit::set_vm_exited();
4267
4268 notify_vm_shutdown();
4269
4270 // We are after VM_Exit::set_vm_exited() so we can't call
4271 // thread->smr_delete() or we will block on the Threads_lock.
4272 // Deleting the shutdown thread here is safe because another
4273 // JavaThread cannot have an active ThreadsListHandle for
4274 // this JavaThread.
4275 delete thread;
4276
4277 #if INCLUDE_JVMCI
4278 if (JVMCICounterSize > 0) {
4279 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4280 }
4281 #endif
4282
4283 // exit_globals() will delete tty
4284 exit_globals();
4285
4286 LogConfiguration::finalize();
4287
4288 return true;
4289 }
4290
4291
4292 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4293 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4294 return is_supported_jni_version(version);
4295 }
4296
4297
4298 jboolean Threads::is_supported_jni_version(jint version) {
4299 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4300 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4301 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4302 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4303 if (version == JNI_VERSION_9) return JNI_TRUE;
4304 if (version == JNI_VERSION_10) return JNI_TRUE;
4305 return JNI_FALSE;
4306 }
4307
4308
4309 void Threads::add(JavaThread* p, bool force_daemon) {
4310 // The threads lock must be owned at this point
4311 assert_locked_or_safepoint(Threads_lock);
4312
4313 BarrierSet::barrier_set()->on_thread_attach(p);
4314
4315 p->set_next(_thread_list);
4316 _thread_list = p;
4317
4318 // Once a JavaThread is added to the Threads list, smr_delete() has
4319 // to be used to delete it. Otherwise we can just delete it directly.
4320 p->set_on_thread_list();
4321
4322 _number_of_threads++;
4323 oop threadObj = p->threadObj();
4324 bool daemon = true;
4325 // Bootstrapping problem: threadObj can be null for initial
4326 // JavaThread (or for threads attached via JNI)
4327 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4328 _number_of_non_daemon_threads++;
4329 daemon = false;
4330 }
4331
4332 ThreadService::add_thread(p, daemon);
4333
4334 // Maintain fast thread list
4335 ThreadsSMRSupport::add_thread(p);
4336
4337 // Possible GC point.
4338 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4339 }
4340
4341 void Threads::remove(JavaThread* p) {
4342
4343 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4344 ObjectSynchronizer::omFlush(p);
4345
4346 // Extra scope needed for Thread_lock, so we can check
4347 // that we do not remove thread without safepoint code notice
4348 { MutexLocker ml(Threads_lock);
4349
4350 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4351
4352 // Maintain fast thread list
4353 ThreadsSMRSupport::remove_thread(p);
4354
4355 JavaThread* current = _thread_list;
4356 JavaThread* prev = NULL;
4357
4358 while (current != p) {
4359 prev = current;
4360 current = current->next();
4361 }
4362
4363 if (prev) {
4364 prev->set_next(current->next());
4365 } else {
4366 _thread_list = p->next();
4367 }
4368
4369 _number_of_threads--;
4370 oop threadObj = p->threadObj();
4371 bool daemon = true;
4372 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4373 _number_of_non_daemon_threads--;
4374 daemon = false;
4375
4376 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4377 // on destroy_vm will wake up.
4378 if (number_of_non_daemon_threads() == 1) {
4379 Threads_lock->notify_all();
4380 }
4381 }
4382 ThreadService::remove_thread(p, daemon);
4383
4384 // Make sure that safepoint code disregard this thread. This is needed since
4385 // the thread might mess around with locks after this point. This can cause it
4386 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4387 // of this thread since it is removed from the queue.
4388 p->set_terminated_value();
4389 } // unlock Threads_lock
4390
4391 // Since Events::log uses a lock, we grab it outside the Threads_lock
4392 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4393 }
4394
4395 // Operations on the Threads list for GC. These are not explicitly locked,
4396 // but the garbage collector must provide a safe context for them to run.
4397 // In particular, these things should never be called when the Threads_lock
4398 // is held by some other thread. (Note: the Safepoint abstraction also
4399 // uses the Threads_lock to guarantee this property. It also makes sure that
4400 // all threads gets blocked when exiting or starting).
4401
4402 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4403 ALL_JAVA_THREADS(p) {
4404 p->oops_do(f, cf);
4405 }
4406 VMThread::vm_thread()->oops_do(f, cf);
4407 }
4408
4409 void Threads::change_thread_claim_parity() {
4410 // Set the new claim parity.
4411 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4412 "Not in range.");
4413 _thread_claim_parity++;
4414 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4415 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4416 "Not in range.");
4417 }
4418
4419 #ifdef ASSERT
4420 void Threads::assert_all_threads_claimed() {
4421 ALL_JAVA_THREADS(p) {
4422 const int thread_parity = p->oops_do_parity();
4423 assert((thread_parity == _thread_claim_parity),
4424 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4425 }
4426 VMThread* vmt = VMThread::vm_thread();
4427 const int thread_parity = vmt->oops_do_parity();
4428 assert((thread_parity == _thread_claim_parity),
4429 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4430 }
4431 #endif // ASSERT
4432
4433 class ParallelOopsDoThreadClosure : public ThreadClosure {
4434 private:
4435 OopClosure* _f;
4436 CodeBlobClosure* _cf;
4437 public:
4438 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4439 void do_thread(Thread* t) {
4440 t->oops_do(_f, _cf);
4441 }
4442 };
4443
4444 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4445 ParallelOopsDoThreadClosure tc(f, cf);
4446 possibly_parallel_threads_do(is_par, &tc);
4447 }
4448
4449 #if INCLUDE_ALL_GCS
4450 // Used by ParallelScavenge
4451 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4452 ALL_JAVA_THREADS(p) {
4453 q->enqueue(new ThreadRootsTask(p));
4454 }
4455 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4456 }
4457
4458 // Used by Parallel Old
4459 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4460 ALL_JAVA_THREADS(p) {
4461 q->enqueue(new ThreadRootsMarkingTask(p));
4462 }
4463 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4464 }
4465 #endif // INCLUDE_ALL_GCS
4466
4467 void Threads::nmethods_do(CodeBlobClosure* cf) {
4468 ALL_JAVA_THREADS(p) {
4469 // This is used by the code cache sweeper to mark nmethods that are active
4470 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4471 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4472 if(!p->is_Code_cache_sweeper_thread()) {
4473 p->nmethods_do(cf);
4474 }
4475 }
4476 }
4477
4478 void Threads::metadata_do(void f(Metadata*)) {
4479 ALL_JAVA_THREADS(p) {
4480 p->metadata_do(f);
4481 }
4482 }
4483
4484 class ThreadHandlesClosure : public ThreadClosure {
4485 void (*_f)(Metadata*);
4486 public:
4487 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4488 virtual void do_thread(Thread* thread) {
4489 thread->metadata_handles_do(_f);
4490 }
4491 };
4492
4493 void Threads::metadata_handles_do(void f(Metadata*)) {
4494 // Only walk the Handles in Thread.
4495 ThreadHandlesClosure handles_closure(f);
4496 threads_do(&handles_closure);
4497 }
4498
4499 void Threads::deoptimized_wrt_marked_nmethods() {
4500 ALL_JAVA_THREADS(p) {
4501 p->deoptimized_wrt_marked_nmethods();
4502 }
4503 }
4504
4505
4506 // Get count Java threads that are waiting to enter the specified monitor.
4507 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4508 int count,
4509 address monitor) {
4510 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4511
4512 int i = 0;
4513 DO_JAVA_THREADS(t_list, p) {
4514 if (!p->can_call_java()) continue;
4515
4516 address pending = (address)p->current_pending_monitor();
4517 if (pending == monitor) { // found a match
4518 if (i < count) result->append(p); // save the first count matches
4519 i++;
4520 }
4521 }
4522
4523 return result;
4524 }
4525
4526
4527 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4528 address owner) {
4529 // NULL owner means not locked so we can skip the search
4530 if (owner == NULL) return NULL;
4531
4532 DO_JAVA_THREADS(t_list, p) {
4533 // first, see if owner is the address of a Java thread
4534 if (owner == (address)p) return p;
4535 }
4536
4537 // Cannot assert on lack of success here since this function may be
4538 // used by code that is trying to report useful problem information
4539 // like deadlock detection.
4540 if (UseHeavyMonitors) return NULL;
4541
4542 // If we didn't find a matching Java thread and we didn't force use of
4543 // heavyweight monitors, then the owner is the stack address of the
4544 // Lock Word in the owning Java thread's stack.
4545 //
4546 JavaThread* the_owner = NULL;
4547 DO_JAVA_THREADS(t_list, q) {
4548 if (q->is_lock_owned(owner)) {
4549 the_owner = q;
4550 break;
4551 }
4552 }
4553
4554 // cannot assert on lack of success here; see above comment
4555 return the_owner;
4556 }
4557
4558 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4559 void Threads::print_on(outputStream* st, bool print_stacks,
4560 bool internal_format, bool print_concurrent_locks) {
4561 char buf[32];
4562 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4563
4564 st->print_cr("Full thread dump %s (%s %s):",
4565 Abstract_VM_Version::vm_name(),
4566 Abstract_VM_Version::vm_release(),
4567 Abstract_VM_Version::vm_info_string());
4568 st->cr();
4569
4570 #if INCLUDE_SERVICES
4571 // Dump concurrent locks
4572 ConcurrentLocksDump concurrent_locks;
4573 if (print_concurrent_locks) {
4574 concurrent_locks.dump_at_safepoint();
4575 }
4576 #endif // INCLUDE_SERVICES
4577
4578 ThreadsSMRSupport::print_info_on(st);
4579 st->cr();
4580
4581 ALL_JAVA_THREADS(p) {
4582 ResourceMark rm;
4583 p->print_on(st);
4584 if (print_stacks) {
4585 if (internal_format) {
4586 p->trace_stack();
4587 } else {
4588 p->print_stack_on(st);
4589 }
4590 }
4591 st->cr();
4592 #if INCLUDE_SERVICES
4593 if (print_concurrent_locks) {
4594 concurrent_locks.print_locks_on(p, st);
4595 }
4596 #endif // INCLUDE_SERVICES
4597 }
4598
4599 VMThread::vm_thread()->print_on(st);
4600 st->cr();
4601 Universe::heap()->print_gc_threads_on(st);
4602 WatcherThread* wt = WatcherThread::watcher_thread();
4603 if (wt != NULL) {
4604 wt->print_on(st);
4605 st->cr();
4606 }
4607
4608 st->flush();
4609 }
4610
4611 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4612 int buflen, bool* found_current) {
4613 if (this_thread != NULL) {
4614 bool is_current = (current == this_thread);
4615 *found_current = *found_current || is_current;
4616 st->print("%s", is_current ? "=>" : " ");
4617
4618 st->print(PTR_FORMAT, p2i(this_thread));
4619 st->print(" ");
4620 this_thread->print_on_error(st, buf, buflen);
4621 st->cr();
4622 }
4623 }
4624
4625 class PrintOnErrorClosure : public ThreadClosure {
4626 outputStream* _st;
4627 Thread* _current;
4628 char* _buf;
4629 int _buflen;
4630 bool* _found_current;
4631 public:
4632 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4633 int buflen, bool* found_current) :
4634 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4635
4636 virtual void do_thread(Thread* thread) {
4637 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4638 }
4639 };
4640
4641 // Threads::print_on_error() is called by fatal error handler. It's possible
4642 // that VM is not at safepoint and/or current thread is inside signal handler.
4643 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4644 // memory (even in resource area), it might deadlock the error handler.
4645 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4646 int buflen) {
4647 ThreadsSMRSupport::print_info_on(st);
4648 st->cr();
4649
4650 bool found_current = false;
4651 st->print_cr("Java Threads: ( => current thread )");
4652 ALL_JAVA_THREADS(thread) {
4653 print_on_error(thread, st, current, buf, buflen, &found_current);
4654 }
4655 st->cr();
4656
4657 st->print_cr("Other Threads:");
4658 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4659 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4660
4661 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4662 Universe::heap()->gc_threads_do(&print_closure);
4663
4664 if (!found_current) {
4665 st->cr();
4666 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4667 current->print_on_error(st, buf, buflen);
4668 st->cr();
4669 }
4670 st->cr();
4671
4672 st->print_cr("Threads with active compile tasks:");
4673 print_threads_compiling(st, buf, buflen);
4674 }
4675
4676 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4677 ALL_JAVA_THREADS(thread) {
4678 if (thread->is_Compiler_thread()) {
4679 CompilerThread* ct = (CompilerThread*) thread;
4680
4681 // Keep task in local variable for NULL check.
4682 // ct->_task might be set to NULL by concurring compiler thread
4683 // because it completed the compilation. The task is never freed,
4684 // though, just returned to a free list.
4685 CompileTask* task = ct->task();
4686 if (task != NULL) {
4687 thread->print_name_on_error(st, buf, buflen);
4688 task->print(st, NULL, true, true);
4689 }
4690 }
4691 }
4692 }
4693
4694
4695 // Internal SpinLock and Mutex
4696 // Based on ParkEvent
4697
4698 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4699 //
4700 // We employ SpinLocks _only for low-contention, fixed-length
4701 // short-duration critical sections where we're concerned
4702 // about native mutex_t or HotSpot Mutex:: latency.
4703 // The mux construct provides a spin-then-block mutual exclusion
4704 // mechanism.
4705 //
4706 // Testing has shown that contention on the ListLock guarding gFreeList
4707 // is common. If we implement ListLock as a simple SpinLock it's common
4708 // for the JVM to devolve to yielding with little progress. This is true
4709 // despite the fact that the critical sections protected by ListLock are
4710 // extremely short.
4711 //
4712 // TODO-FIXME: ListLock should be of type SpinLock.
4713 // We should make this a 1st-class type, integrated into the lock
4714 // hierarchy as leaf-locks. Critically, the SpinLock structure
4715 // should have sufficient padding to avoid false-sharing and excessive
4716 // cache-coherency traffic.
4717
4718
4719 typedef volatile int SpinLockT;
4720
4721 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4722 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4723 return; // normal fast-path return
4724 }
4725
4726 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4727 TEVENT(SpinAcquire - ctx);
4728 int ctr = 0;
4729 int Yields = 0;
4730 for (;;) {
4731 while (*adr != 0) {
4732 ++ctr;
4733 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4734 if (Yields > 5) {
4735 os::naked_short_sleep(1);
4736 } else {
4737 os::naked_yield();
4738 ++Yields;
4739 }
4740 } else {
4741 SpinPause();
4742 }
4743 }
4744 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4745 }
4746 }
4747
4748 void Thread::SpinRelease(volatile int * adr) {
4749 assert(*adr != 0, "invariant");
4750 OrderAccess::fence(); // guarantee at least release consistency.
4751 // Roach-motel semantics.
4752 // It's safe if subsequent LDs and STs float "up" into the critical section,
4753 // but prior LDs and STs within the critical section can't be allowed
4754 // to reorder or float past the ST that releases the lock.
4755 // Loads and stores in the critical section - which appear in program
4756 // order before the store that releases the lock - must also appear
4757 // before the store that releases the lock in memory visibility order.
4758 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4759 // the ST of 0 into the lock-word which releases the lock, so fence
4760 // more than covers this on all platforms.
4761 *adr = 0;
4762 }
4763
4764 // muxAcquire and muxRelease:
4765 //
4766 // * muxAcquire and muxRelease support a single-word lock-word construct.
4767 // The LSB of the word is set IFF the lock is held.
4768 // The remainder of the word points to the head of a singly-linked list
4769 // of threads blocked on the lock.
4770 //
4771 // * The current implementation of muxAcquire-muxRelease uses its own
4772 // dedicated Thread._MuxEvent instance. If we're interested in
4773 // minimizing the peak number of extant ParkEvent instances then
4774 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4775 // as certain invariants were satisfied. Specifically, care would need
4776 // to be taken with regards to consuming unpark() "permits".
4777 // A safe rule of thumb is that a thread would never call muxAcquire()
4778 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4779 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4780 // consume an unpark() permit intended for monitorenter, for instance.
4781 // One way around this would be to widen the restricted-range semaphore
4782 // implemented in park(). Another alternative would be to provide
4783 // multiple instances of the PlatformEvent() for each thread. One
4784 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4785 //
4786 // * Usage:
4787 // -- Only as leaf locks
4788 // -- for short-term locking only as muxAcquire does not perform
4789 // thread state transitions.
4790 //
4791 // Alternatives:
4792 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4793 // but with parking or spin-then-park instead of pure spinning.
4794 // * Use Taura-Oyama-Yonenzawa locks.
4795 // * It's possible to construct a 1-0 lock if we encode the lockword as
4796 // (List,LockByte). Acquire will CAS the full lockword while Release
4797 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4798 // acquiring threads use timers (ParkTimed) to detect and recover from
4799 // the stranding window. Thread/Node structures must be aligned on 256-byte
4800 // boundaries by using placement-new.
4801 // * Augment MCS with advisory back-link fields maintained with CAS().
4802 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4803 // The validity of the backlinks must be ratified before we trust the value.
4804 // If the backlinks are invalid the exiting thread must back-track through the
4805 // the forward links, which are always trustworthy.
4806 // * Add a successor indication. The LockWord is currently encoded as
4807 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4808 // to provide the usual futile-wakeup optimization.
4809 // See RTStt for details.
4810 // * Consider schedctl.sc_nopreempt to cover the critical section.
4811 //
4812
4813
4814 const intptr_t LOCKBIT = 1;
4815
4816 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4817 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4818 if (w == 0) return;
4819 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4820 return;
4821 }
4822
4823 TEVENT(muxAcquire - Contention);
4824 ParkEvent * const Self = Thread::current()->_MuxEvent;
4825 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4826 for (;;) {
4827 int its = (os::is_MP() ? 100 : 0) + 1;
4828
4829 // Optional spin phase: spin-then-park strategy
4830 while (--its >= 0) {
4831 w = *Lock;
4832 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4833 return;
4834 }
4835 }
4836
4837 Self->reset();
4838 Self->OnList = intptr_t(Lock);
4839 // The following fence() isn't _strictly necessary as the subsequent
4840 // CAS() both serializes execution and ratifies the fetched *Lock value.
4841 OrderAccess::fence();
4842 for (;;) {
4843 w = *Lock;
4844 if ((w & LOCKBIT) == 0) {
4845 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4846 Self->OnList = 0; // hygiene - allows stronger asserts
4847 return;
4848 }
4849 continue; // Interference -- *Lock changed -- Just retry
4850 }
4851 assert(w & LOCKBIT, "invariant");
4852 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4853 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4854 }
4855
4856 while (Self->OnList != 0) {
4857 Self->park();
4858 }
4859 }
4860 }
4861
4862 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4863 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4864 if (w == 0) return;
4865 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4866 return;
4867 }
4868
4869 TEVENT(muxAcquire - Contention);
4870 ParkEvent * ReleaseAfter = NULL;
4871 if (ev == NULL) {
4872 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4873 }
4874 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4875 for (;;) {
4876 guarantee(ev->OnList == 0, "invariant");
4877 int its = (os::is_MP() ? 100 : 0) + 1;
4878
4879 // Optional spin phase: spin-then-park strategy
4880 while (--its >= 0) {
4881 w = *Lock;
4882 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4883 if (ReleaseAfter != NULL) {
4884 ParkEvent::Release(ReleaseAfter);
4885 }
4886 return;
4887 }
4888 }
4889
4890 ev->reset();
4891 ev->OnList = intptr_t(Lock);
4892 // The following fence() isn't _strictly necessary as the subsequent
4893 // CAS() both serializes execution and ratifies the fetched *Lock value.
4894 OrderAccess::fence();
4895 for (;;) {
4896 w = *Lock;
4897 if ((w & LOCKBIT) == 0) {
4898 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4899 ev->OnList = 0;
4900 // We call ::Release while holding the outer lock, thus
4901 // artificially lengthening the critical section.
4902 // Consider deferring the ::Release() until the subsequent unlock(),
4903 // after we've dropped the outer lock.
4904 if (ReleaseAfter != NULL) {
4905 ParkEvent::Release(ReleaseAfter);
4906 }
4907 return;
4908 }
4909 continue; // Interference -- *Lock changed -- Just retry
4910 }
4911 assert(w & LOCKBIT, "invariant");
4912 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4913 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4914 }
4915
4916 while (ev->OnList != 0) {
4917 ev->park();
4918 }
4919 }
4920 }
4921
4922 // Release() must extract a successor from the list and then wake that thread.
4923 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4924 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4925 // Release() would :
4926 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4927 // (B) Extract a successor from the private list "in-hand"
4928 // (C) attempt to CAS() the residual back into *Lock over null.
4929 // If there were any newly arrived threads and the CAS() would fail.
4930 // In that case Release() would detach the RATs, re-merge the list in-hand
4931 // with the RATs and repeat as needed. Alternately, Release() might
4932 // detach and extract a successor, but then pass the residual list to the wakee.
4933 // The wakee would be responsible for reattaching and remerging before it
4934 // competed for the lock.
4935 //
4936 // Both "pop" and DMR are immune from ABA corruption -- there can be
4937 // multiple concurrent pushers, but only one popper or detacher.
4938 // This implementation pops from the head of the list. This is unfair,
4939 // but tends to provide excellent throughput as hot threads remain hot.
4940 // (We wake recently run threads first).
4941 //
4942 // All paths through muxRelease() will execute a CAS.
4943 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4944 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4945 // executed within the critical section are complete and globally visible before the
4946 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4947 void Thread::muxRelease(volatile intptr_t * Lock) {
4948 for (;;) {
4949 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4950 assert(w & LOCKBIT, "invariant");
4951 if (w == LOCKBIT) return;
4952 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4953 assert(List != NULL, "invariant");
4954 assert(List->OnList == intptr_t(Lock), "invariant");
4955 ParkEvent * const nxt = List->ListNext;
4956 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4957
4958 // The following CAS() releases the lock and pops the head element.
4959 // The CAS() also ratifies the previously fetched lock-word value.
4960 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4961 continue;
4962 }
4963 List->OnList = 0;
4964 OrderAccess::fence();
4965 List->unpark();
4966 return;
4967 }
4968 }
4969
4970
4971 void Threads::verify() {
4972 ALL_JAVA_THREADS(p) {
4973 p->verify();
4974 }
4975 VMThread* thread = VMThread::vm_thread();
4976 if (thread != NULL) thread->verify();
4977 }