1 /* 2 * Copyright (c) 1997, 2014, 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 "classfile/classLoader.hpp" 27 #include "classfile/javaClasses.hpp" 28 #include "classfile/systemDictionary.hpp" 29 #include "classfile/vmSymbols.hpp" 30 #include "code/codeCache.hpp" 31 #include "code/scopeDesc.hpp" 32 #include "compiler/compileBroker.hpp" 33 #include "interpreter/interpreter.hpp" 34 #include "interpreter/linkResolver.hpp" 35 #include "interpreter/oopMapCache.hpp" 36 #include "jvmtifiles/jvmtiEnv.hpp" 37 #include "memory/gcLocker.inline.hpp" 38 #include "memory/metaspaceShared.hpp" 39 #include "memory/oopFactory.hpp" 40 #include "memory/universe.inline.hpp" 41 #include "oops/instanceKlass.hpp" 42 #include "oops/objArrayOop.hpp" 43 #include "oops/oop.inline.hpp" 44 #include "oops/symbol.hpp" 45 #include "prims/jvm_misc.hpp" 46 #include "prims/jvmtiExport.hpp" 47 #include "prims/jvmtiThreadState.hpp" 48 #include "prims/privilegedStack.hpp" 49 #include "runtime/arguments.hpp" 50 #include "runtime/atomic.inline.hpp" 51 #include "runtime/biasedLocking.hpp" 52 #include "runtime/deoptimization.hpp" 53 #include "runtime/fprofiler.hpp" 54 #include "runtime/frame.inline.hpp" 55 #include "runtime/init.hpp" 56 #include "runtime/interfaceSupport.hpp" 57 #include "runtime/java.hpp" 58 #include "runtime/javaCalls.hpp" 59 #include "runtime/jniPeriodicChecker.hpp" 60 #include "runtime/memprofiler.hpp" 61 #include "runtime/mutexLocker.hpp" 62 #include "runtime/objectMonitor.hpp" 63 #include "runtime/orderAccess.inline.hpp" 64 #include "runtime/osThread.hpp" 65 #include "runtime/safepoint.hpp" 66 #include "runtime/sharedRuntime.hpp" 67 #include "runtime/statSampler.hpp" 68 #include "runtime/stubRoutines.hpp" 69 #include "runtime/task.hpp" 70 #include "runtime/thread.inline.hpp" 71 #include "runtime/threadCritical.hpp" 72 #include "runtime/threadLocalStorage.hpp" 73 #include "runtime/vframe.hpp" 74 #include "runtime/vframeArray.hpp" 75 #include "runtime/vframe_hp.hpp" 76 #include "runtime/vmThread.hpp" 77 #include "runtime/vm_operations.hpp" 78 #include "runtime/vm_version.hpp" 79 #include "services/attachListener.hpp" 80 #include "services/management.hpp" 81 #include "services/memTracker.hpp" 82 #include "services/threadService.hpp" 83 #include "trace/tracing.hpp" 84 #include "trace/traceMacros.hpp" 85 #include "utilities/defaultStream.hpp" 86 #include "utilities/dtrace.hpp" 87 #include "utilities/events.hpp" 88 #include "utilities/preserveException.hpp" 89 #include "utilities/macros.hpp" 90 #if INCLUDE_ALL_GCS 91 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 92 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 93 #include "gc_implementation/parallelScavenge/pcTasks.hpp" 94 #endif // INCLUDE_ALL_GCS 95 #ifdef COMPILER1 96 #include "c1/c1_Compiler.hpp" 97 #endif 98 #ifdef COMPILER2 99 #include "opto/c2compiler.hpp" 100 #include "opto/idealGraphPrinter.hpp" 101 #endif 102 #if INCLUDE_RTM_OPT 103 #include "runtime/rtmLocking.hpp" 104 #endif 105 106 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 107 108 #ifdef DTRACE_ENABLED 109 110 // Only bother with this argument setup if dtrace is available 111 112 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 113 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 114 115 #define DTRACE_THREAD_PROBE(probe, javathread) \ 116 { \ 117 ResourceMark rm(this); \ 118 int len = 0; \ 119 const char* name = (javathread)->get_thread_name(); \ 120 len = strlen(name); \ 121 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 122 (char *) name, len, \ 123 java_lang_Thread::thread_id((javathread)->threadObj()), \ 124 (uintptr_t) (javathread)->osthread()->thread_id(), \ 125 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 126 } 127 128 #else // ndef DTRACE_ENABLED 129 130 #define DTRACE_THREAD_PROBE(probe, javathread) 131 132 #endif // ndef DTRACE_ENABLED 133 134 135 // Class hierarchy 136 // - Thread 137 // - VMThread 138 // - WatcherThread 139 // - ConcurrentMarkSweepThread 140 // - JavaThread 141 // - CompilerThread 142 143 // ======= Thread ======== 144 // Support for forcing alignment of thread objects for biased locking 145 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 146 if (UseBiasedLocking) { 147 const int alignment = markOopDesc::biased_lock_alignment; 148 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 149 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 150 : AllocateHeap(aligned_size, flags, CURRENT_PC, 151 AllocFailStrategy::RETURN_NULL); 152 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 153 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 154 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 155 "JavaThread alignment code overflowed allocated storage"); 156 if (TraceBiasedLocking) { 157 if (aligned_addr != real_malloc_addr) { 158 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 159 real_malloc_addr, aligned_addr); 160 } 161 } 162 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 163 return aligned_addr; 164 } else { 165 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 166 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 167 } 168 } 169 170 void Thread::operator delete(void* p) { 171 if (UseBiasedLocking) { 172 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 173 FreeHeap(real_malloc_addr, mtThread); 174 } else { 175 FreeHeap(p, mtThread); 176 } 177 } 178 179 180 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 181 // JavaThread 182 183 184 Thread::Thread() { 185 // stack and get_thread 186 set_stack_base(NULL); 187 set_stack_size(0); 188 set_self_raw_id(0); 189 set_lgrp_id(-1); 190 191 // allocated data structures 192 set_osthread(NULL); 193 set_resource_area(new (mtThread)ResourceArea()); 194 DEBUG_ONLY(_current_resource_mark = NULL;) 195 set_handle_area(new (mtThread) HandleArea(NULL)); 196 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 197 set_active_handles(NULL); 198 set_free_handle_block(NULL); 199 set_last_handle_mark(NULL); 200 201 // This initial value ==> never claimed. 202 _oops_do_parity = 0; 203 204 // the handle mark links itself to last_handle_mark 205 new HandleMark(this); 206 207 // plain initialization 208 debug_only(_owned_locks = NULL;) 209 debug_only(_allow_allocation_count = 0;) 210 NOT_PRODUCT(_allow_safepoint_count = 0;) 211 NOT_PRODUCT(_skip_gcalot = false;) 212 _jvmti_env_iteration_count = 0; 213 set_allocated_bytes(0); 214 _vm_operation_started_count = 0; 215 _vm_operation_completed_count = 0; 216 _current_pending_monitor = NULL; 217 _current_pending_monitor_is_from_java = true; 218 _current_waiting_monitor = NULL; 219 _num_nested_signal = 0; 220 omFreeList = NULL; 221 omFreeCount = 0; 222 omFreeProvision = 32; 223 omInUseList = NULL; 224 omInUseCount = 0; 225 226 #ifdef ASSERT 227 _visited_for_critical_count = false; 228 #endif 229 230 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true); 231 _suspend_flags = 0; 232 233 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 234 _hashStateX = os::random(); 235 _hashStateY = 842502087; 236 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 237 _hashStateW = 273326509; 238 239 _OnTrap = 0; 240 _schedctl = NULL; 241 _Stalled = 0; 242 _TypeTag = 0x2BAD; 243 244 // Many of the following fields are effectively final - immutable 245 // Note that nascent threads can't use the Native Monitor-Mutex 246 // construct until the _MutexEvent is initialized ... 247 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 248 // we might instead use a stack of ParkEvents that we could provision on-demand. 249 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 250 // and ::Release() 251 _ParkEvent = ParkEvent::Allocate(this); 252 _SleepEvent = ParkEvent::Allocate(this); 253 _MutexEvent = ParkEvent::Allocate(this); 254 _MuxEvent = ParkEvent::Allocate(this); 255 256 #ifdef CHECK_UNHANDLED_OOPS 257 if (CheckUnhandledOops) { 258 _unhandled_oops = new UnhandledOops(this); 259 } 260 #endif // CHECK_UNHANDLED_OOPS 261 #ifdef ASSERT 262 if (UseBiasedLocking) { 263 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 264 assert(this == _real_malloc_address || 265 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 266 "bug in forced alignment of thread objects"); 267 } 268 #endif // ASSERT 269 } 270 271 void Thread::initialize_thread_local_storage() { 272 // Note: Make sure this method only calls 273 // non-blocking operations. Otherwise, it might not work 274 // with the thread-startup/safepoint interaction. 275 276 // During Java thread startup, safepoint code should allow this 277 // method to complete because it may need to allocate memory to 278 // store information for the new thread. 279 280 // initialize structure dependent on thread local storage 281 ThreadLocalStorage::set_thread(this); 282 } 283 284 void Thread::record_stack_base_and_size() { 285 set_stack_base(os::current_stack_base()); 286 set_stack_size(os::current_stack_size()); 287 if (is_Java_thread()) { 288 ((JavaThread*) this)->set_stack_overflow_limit(); 289 } 290 // CR 7190089: on Solaris, primordial thread's stack is adjusted 291 // in initialize_thread(). Without the adjustment, stack size is 292 // incorrect if stack is set to unlimited (ulimit -s unlimited). 293 // So far, only Solaris has real implementation of initialize_thread(). 294 // 295 // set up any platform-specific state. 296 os::initialize_thread(this); 297 298 #if INCLUDE_NMT 299 // record thread's native stack, stack grows downward 300 address stack_low_addr = stack_base() - stack_size(); 301 MemTracker::record_thread_stack(stack_low_addr, stack_size()); 302 #endif // INCLUDE_NMT 303 } 304 305 306 Thread::~Thread() { 307 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 308 ObjectSynchronizer::omFlush(this); 309 310 EVENT_THREAD_DESTRUCT(this); 311 312 // stack_base can be NULL if the thread is never started or exited before 313 // record_stack_base_and_size called. Although, we would like to ensure 314 // that all started threads do call record_stack_base_and_size(), there is 315 // not proper way to enforce that. 316 #if INCLUDE_NMT 317 if (_stack_base != NULL) { 318 address low_stack_addr = stack_base() - stack_size(); 319 MemTracker::release_thread_stack(low_stack_addr, stack_size()); 320 #ifdef ASSERT 321 set_stack_base(NULL); 322 #endif 323 } 324 #endif // INCLUDE_NMT 325 326 // deallocate data structures 327 delete resource_area(); 328 // since the handle marks are using the handle area, we have to deallocated the root 329 // handle mark before deallocating the thread's handle area, 330 assert(last_handle_mark() != NULL, "check we have an element"); 331 delete last_handle_mark(); 332 assert(last_handle_mark() == NULL, "check we have reached the end"); 333 334 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 335 // We NULL out the fields for good hygiene. 336 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 337 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 338 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 339 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 340 341 delete handle_area(); 342 delete metadata_handles(); 343 344 // osthread() can be NULL, if creation of thread failed. 345 if (osthread() != NULL) os::free_thread(osthread()); 346 347 delete _SR_lock; 348 349 // clear thread local storage if the Thread is deleting itself 350 if (this == Thread::current()) { 351 ThreadLocalStorage::set_thread(NULL); 352 } else { 353 // In the case where we're not the current thread, invalidate all the 354 // caches in case some code tries to get the current thread or the 355 // thread that was destroyed, and gets stale information. 356 ThreadLocalStorage::invalidate_all(); 357 } 358 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 359 } 360 361 // NOTE: dummy function for assertion purpose. 362 void Thread::run() { 363 ShouldNotReachHere(); 364 } 365 366 #ifdef ASSERT 367 // Private method to check for dangling thread pointer 368 void check_for_dangling_thread_pointer(Thread *thread) { 369 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 370 "possibility of dangling Thread pointer"); 371 } 372 #endif 373 374 375 #ifndef PRODUCT 376 // Tracing method for basic thread operations 377 void Thread::trace(const char* msg, const Thread* const thread) { 378 if (!TraceThreadEvents) return; 379 ResourceMark rm; 380 ThreadCritical tc; 381 const char *name = "non-Java thread"; 382 int prio = -1; 383 if (thread->is_Java_thread() 384 && !thread->is_Compiler_thread()) { 385 // The Threads_lock must be held to get information about 386 // this thread but may not be in some situations when 387 // tracing thread events. 388 bool release_Threads_lock = false; 389 if (!Threads_lock->owned_by_self()) { 390 Threads_lock->lock(); 391 release_Threads_lock = true; 392 } 393 JavaThread* jt = (JavaThread *)thread; 394 name = (char *)jt->get_thread_name(); 395 oop thread_oop = jt->threadObj(); 396 if (thread_oop != NULL) { 397 prio = java_lang_Thread::priority(thread_oop); 398 } 399 if (release_Threads_lock) { 400 Threads_lock->unlock(); 401 } 402 } 403 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio); 404 } 405 #endif 406 407 408 ThreadPriority Thread::get_priority(const Thread* const thread) { 409 trace("get priority", thread); 410 ThreadPriority priority; 411 // Can return an error! 412 (void)os::get_priority(thread, priority); 413 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 414 return priority; 415 } 416 417 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 418 trace("set priority", thread); 419 debug_only(check_for_dangling_thread_pointer(thread);) 420 // Can return an error! 421 (void)os::set_priority(thread, priority); 422 } 423 424 425 void Thread::start(Thread* thread) { 426 trace("start", thread); 427 // Start is different from resume in that its safety is guaranteed by context or 428 // being called from a Java method synchronized on the Thread object. 429 if (!DisableStartThread) { 430 if (thread->is_Java_thread()) { 431 // Initialize the thread state to RUNNABLE before starting this thread. 432 // Can not set it after the thread started because we do not know the 433 // exact thread state at that time. It could be in MONITOR_WAIT or 434 // in SLEEPING or some other state. 435 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 436 java_lang_Thread::RUNNABLE); 437 } 438 os::start_thread(thread); 439 } 440 } 441 442 // Enqueue a VM_Operation to do the job for us - sometime later 443 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 444 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 445 VMThread::execute(vm_stop); 446 } 447 448 449 // Check if an external suspend request has completed (or has been 450 // cancelled). Returns true if the thread is externally suspended and 451 // false otherwise. 452 // 453 // The bits parameter returns information about the code path through 454 // the routine. Useful for debugging: 455 // 456 // set in is_ext_suspend_completed(): 457 // 0x00000001 - routine was entered 458 // 0x00000010 - routine return false at end 459 // 0x00000100 - thread exited (return false) 460 // 0x00000200 - suspend request cancelled (return false) 461 // 0x00000400 - thread suspended (return true) 462 // 0x00001000 - thread is in a suspend equivalent state (return true) 463 // 0x00002000 - thread is native and walkable (return true) 464 // 0x00004000 - thread is native_trans and walkable (needed retry) 465 // 466 // set in wait_for_ext_suspend_completion(): 467 // 0x00010000 - routine was entered 468 // 0x00020000 - suspend request cancelled before loop (return false) 469 // 0x00040000 - thread suspended before loop (return true) 470 // 0x00080000 - suspend request cancelled in loop (return false) 471 // 0x00100000 - thread suspended in loop (return true) 472 // 0x00200000 - suspend not completed during retry loop (return false) 473 474 // Helper class for tracing suspend wait debug bits. 475 // 476 // 0x00000100 indicates that the target thread exited before it could 477 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 478 // 0x00080000 each indicate a cancelled suspend request so they don't 479 // count as wait failures either. 480 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 481 482 class TraceSuspendDebugBits : public StackObj { 483 private: 484 JavaThread * jt; 485 bool is_wait; 486 bool called_by_wait; // meaningful when !is_wait 487 uint32_t * bits; 488 489 public: 490 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 491 uint32_t *_bits) { 492 jt = _jt; 493 is_wait = _is_wait; 494 called_by_wait = _called_by_wait; 495 bits = _bits; 496 } 497 498 ~TraceSuspendDebugBits() { 499 if (!is_wait) { 500 #if 1 501 // By default, don't trace bits for is_ext_suspend_completed() calls. 502 // That trace is very chatty. 503 return; 504 #else 505 if (!called_by_wait) { 506 // If tracing for is_ext_suspend_completed() is enabled, then only 507 // trace calls to it from wait_for_ext_suspend_completion() 508 return; 509 } 510 #endif 511 } 512 513 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 514 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 515 MutexLocker ml(Threads_lock); // needed for get_thread_name() 516 ResourceMark rm; 517 518 tty->print_cr( 519 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 520 jt->get_thread_name(), *bits); 521 522 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 523 } 524 } 525 } 526 }; 527 #undef DEBUG_FALSE_BITS 528 529 530 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 531 uint32_t *bits) { 532 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 533 534 bool did_trans_retry = false; // only do thread_in_native_trans retry once 535 bool do_trans_retry; // flag to force the retry 536 537 *bits |= 0x00000001; 538 539 do { 540 do_trans_retry = false; 541 542 if (is_exiting()) { 543 // Thread is in the process of exiting. This is always checked 544 // first to reduce the risk of dereferencing a freed JavaThread. 545 *bits |= 0x00000100; 546 return false; 547 } 548 549 if (!is_external_suspend()) { 550 // Suspend request is cancelled. This is always checked before 551 // is_ext_suspended() to reduce the risk of a rogue resume 552 // confusing the thread that made the suspend request. 553 *bits |= 0x00000200; 554 return false; 555 } 556 557 if (is_ext_suspended()) { 558 // thread is suspended 559 *bits |= 0x00000400; 560 return true; 561 } 562 563 // Now that we no longer do hard suspends of threads running 564 // native code, the target thread can be changing thread state 565 // while we are in this routine: 566 // 567 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 568 // 569 // We save a copy of the thread state as observed at this moment 570 // and make our decision about suspend completeness based on the 571 // copy. This closes the race where the thread state is seen as 572 // _thread_in_native_trans in the if-thread_blocked check, but is 573 // seen as _thread_blocked in if-thread_in_native_trans check. 574 JavaThreadState save_state = thread_state(); 575 576 if (save_state == _thread_blocked && is_suspend_equivalent()) { 577 // If the thread's state is _thread_blocked and this blocking 578 // condition is known to be equivalent to a suspend, then we can 579 // consider the thread to be externally suspended. This means that 580 // the code that sets _thread_blocked has been modified to do 581 // self-suspension if the blocking condition releases. We also 582 // used to check for CONDVAR_WAIT here, but that is now covered by 583 // the _thread_blocked with self-suspension check. 584 // 585 // Return true since we wouldn't be here unless there was still an 586 // external suspend request. 587 *bits |= 0x00001000; 588 return true; 589 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 590 // Threads running native code will self-suspend on native==>VM/Java 591 // transitions. If its stack is walkable (should always be the case 592 // unless this function is called before the actual java_suspend() 593 // call), then the wait is done. 594 *bits |= 0x00002000; 595 return true; 596 } else if (!called_by_wait && !did_trans_retry && 597 save_state == _thread_in_native_trans && 598 frame_anchor()->walkable()) { 599 // The thread is transitioning from thread_in_native to another 600 // thread state. check_safepoint_and_suspend_for_native_trans() 601 // will force the thread to self-suspend. If it hasn't gotten 602 // there yet we may have caught the thread in-between the native 603 // code check above and the self-suspend. Lucky us. If we were 604 // called by wait_for_ext_suspend_completion(), then it 605 // will be doing the retries so we don't have to. 606 // 607 // Since we use the saved thread state in the if-statement above, 608 // there is a chance that the thread has already transitioned to 609 // _thread_blocked by the time we get here. In that case, we will 610 // make a single unnecessary pass through the logic below. This 611 // doesn't hurt anything since we still do the trans retry. 612 613 *bits |= 0x00004000; 614 615 // Once the thread leaves thread_in_native_trans for another 616 // thread state, we break out of this retry loop. We shouldn't 617 // need this flag to prevent us from getting back here, but 618 // sometimes paranoia is good. 619 did_trans_retry = true; 620 621 // We wait for the thread to transition to a more usable state. 622 for (int i = 1; i <= SuspendRetryCount; i++) { 623 // We used to do an "os::yield_all(i)" call here with the intention 624 // that yielding would increase on each retry. However, the parameter 625 // is ignored on Linux which means the yield didn't scale up. Waiting 626 // on the SR_lock below provides a much more predictable scale up for 627 // the delay. It also provides a simple/direct point to check for any 628 // safepoint requests from the VMThread 629 630 // temporarily drops SR_lock while doing wait with safepoint check 631 // (if we're a JavaThread - the WatcherThread can also call this) 632 // and increase delay with each retry 633 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 634 635 // check the actual thread state instead of what we saved above 636 if (thread_state() != _thread_in_native_trans) { 637 // the thread has transitioned to another thread state so 638 // try all the checks (except this one) one more time. 639 do_trans_retry = true; 640 break; 641 } 642 } // end retry loop 643 644 645 } 646 } while (do_trans_retry); 647 648 *bits |= 0x00000010; 649 return false; 650 } 651 652 // Wait for an external suspend request to complete (or be cancelled). 653 // Returns true if the thread is externally suspended and false otherwise. 654 // 655 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 656 uint32_t *bits) { 657 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 658 false /* !called_by_wait */, bits); 659 660 // local flag copies to minimize SR_lock hold time 661 bool is_suspended; 662 bool pending; 663 uint32_t reset_bits; 664 665 // set a marker so is_ext_suspend_completed() knows we are the caller 666 *bits |= 0x00010000; 667 668 // We use reset_bits to reinitialize the bits value at the top of 669 // each retry loop. This allows the caller to make use of any 670 // unused bits for their own marking purposes. 671 reset_bits = *bits; 672 673 { 674 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 675 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 676 delay, bits); 677 pending = is_external_suspend(); 678 } 679 // must release SR_lock to allow suspension to complete 680 681 if (!pending) { 682 // A cancelled suspend request is the only false return from 683 // is_ext_suspend_completed() that keeps us from entering the 684 // retry loop. 685 *bits |= 0x00020000; 686 return false; 687 } 688 689 if (is_suspended) { 690 *bits |= 0x00040000; 691 return true; 692 } 693 694 for (int i = 1; i <= retries; i++) { 695 *bits = reset_bits; // reinit to only track last retry 696 697 // We used to do an "os::yield_all(i)" call here with the intention 698 // that yielding would increase on each retry. However, the parameter 699 // is ignored on Linux which means the yield didn't scale up. Waiting 700 // on the SR_lock below provides a much more predictable scale up for 701 // the delay. It also provides a simple/direct point to check for any 702 // safepoint requests from the VMThread 703 704 { 705 MutexLocker ml(SR_lock()); 706 // wait with safepoint check (if we're a JavaThread - the WatcherThread 707 // can also call this) and increase delay with each retry 708 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 709 710 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 711 delay, bits); 712 713 // It is possible for the external suspend request to be cancelled 714 // (by a resume) before the actual suspend operation is completed. 715 // Refresh our local copy to see if we still need to wait. 716 pending = is_external_suspend(); 717 } 718 719 if (!pending) { 720 // A cancelled suspend request is the only false return from 721 // is_ext_suspend_completed() that keeps us from staying in the 722 // retry loop. 723 *bits |= 0x00080000; 724 return false; 725 } 726 727 if (is_suspended) { 728 *bits |= 0x00100000; 729 return true; 730 } 731 } // end retry loop 732 733 // thread did not suspend after all our retries 734 *bits |= 0x00200000; 735 return false; 736 } 737 738 #ifndef PRODUCT 739 void JavaThread::record_jump(address target, address instr, const char* file, 740 int line) { 741 742 // This should not need to be atomic as the only way for simultaneous 743 // updates is via interrupts. Even then this should be rare or non-existent 744 // and we don't care that much anyway. 745 746 int index = _jmp_ring_index; 747 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 748 _jmp_ring[index]._target = (intptr_t) target; 749 _jmp_ring[index]._instruction = (intptr_t) instr; 750 _jmp_ring[index]._file = file; 751 _jmp_ring[index]._line = line; 752 } 753 #endif // PRODUCT 754 755 // Called by flat profiler 756 // Callers have already called wait_for_ext_suspend_completion 757 // The assertion for that is currently too complex to put here: 758 bool JavaThread::profile_last_Java_frame(frame* _fr) { 759 bool gotframe = false; 760 // self suspension saves needed state. 761 if (has_last_Java_frame() && _anchor.walkable()) { 762 *_fr = pd_last_frame(); 763 gotframe = true; 764 } 765 return gotframe; 766 } 767 768 void Thread::interrupt(Thread* thread) { 769 trace("interrupt", thread); 770 debug_only(check_for_dangling_thread_pointer(thread);) 771 os::interrupt(thread); 772 } 773 774 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 775 trace("is_interrupted", thread); 776 debug_only(check_for_dangling_thread_pointer(thread);) 777 // Note: If clear_interrupted==false, this simply fetches and 778 // returns the value of the field osthread()->interrupted(). 779 return os::is_interrupted(thread, clear_interrupted); 780 } 781 782 783 // GC Support 784 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 785 jint thread_parity = _oops_do_parity; 786 if (thread_parity != strong_roots_parity) { 787 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 788 if (res == thread_parity) { 789 return true; 790 } else { 791 guarantee(res == strong_roots_parity, "Or else what?"); 792 assert(SharedHeap::heap()->workers()->active_workers() > 0, 793 "Should only fail when parallel."); 794 return false; 795 } 796 } 797 assert(SharedHeap::heap()->workers()->active_workers() > 0, 798 "Should only fail when parallel."); 799 return false; 800 } 801 802 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 803 active_handles()->oops_do(f); 804 // Do oop for ThreadShadow 805 f->do_oop((oop*)&_pending_exception); 806 handle_area()->oops_do(f); 807 } 808 809 void Thread::nmethods_do(CodeBlobClosure* cf) { 810 // no nmethods in a generic thread... 811 } 812 813 void Thread::metadata_do(void f(Metadata*)) { 814 if (metadata_handles() != NULL) { 815 for (int i = 0; i< metadata_handles()->length(); i++) { 816 f(metadata_handles()->at(i)); 817 } 818 } 819 } 820 821 void Thread::print_on(outputStream* st) const { 822 // get_priority assumes osthread initialized 823 if (osthread() != NULL) { 824 int os_prio; 825 if (os::get_native_priority(this, &os_prio) == OS_OK) { 826 st->print("os_prio=%d ", os_prio); 827 } 828 st->print("tid=" INTPTR_FORMAT " ", this); 829 ext().print_on(st); 830 osthread()->print_on(st); 831 } 832 debug_only(if (WizardMode) print_owned_locks_on(st);) 833 } 834 835 // Thread::print_on_error() is called by fatal error handler. Don't use 836 // any lock or allocate memory. 837 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 838 if (is_VM_thread()) st->print("VMThread"); 839 else if (is_Compiler_thread()) st->print("CompilerThread"); 840 else if (is_Java_thread()) st->print("JavaThread"); 841 else if (is_GC_task_thread()) st->print("GCTaskThread"); 842 else if (is_Watcher_thread()) st->print("WatcherThread"); 843 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 844 else st->print("Thread"); 845 846 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 847 _stack_base - _stack_size, _stack_base); 848 849 if (osthread()) { 850 st->print(" [id=%d]", osthread()->thread_id()); 851 } 852 } 853 854 #ifdef ASSERT 855 void Thread::print_owned_locks_on(outputStream* st) const { 856 Monitor *cur = _owned_locks; 857 if (cur == NULL) { 858 st->print(" (no locks) "); 859 } else { 860 st->print_cr(" Locks owned:"); 861 while (cur) { 862 cur->print_on(st); 863 cur = cur->next(); 864 } 865 } 866 } 867 868 static int ref_use_count = 0; 869 870 bool Thread::owns_locks_but_compiled_lock() const { 871 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 872 if (cur != Compile_lock) return true; 873 } 874 return false; 875 } 876 877 878 #endif 879 880 #ifndef PRODUCT 881 882 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 883 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 884 // no threads which allow_vm_block's are held 885 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 886 // Check if current thread is allowed to block at a safepoint 887 if (!(_allow_safepoint_count == 0)) { 888 fatal("Possible safepoint reached by thread that does not allow it"); 889 } 890 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 891 fatal("LEAF method calling lock?"); 892 } 893 894 #ifdef ASSERT 895 if (potential_vm_operation && is_Java_thread() 896 && !Universe::is_bootstrapping()) { 897 // Make sure we do not hold any locks that the VM thread also uses. 898 // This could potentially lead to deadlocks 899 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 900 // Threads_lock is special, since the safepoint synchronization will not start before this is 901 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 902 // since it is used to transfer control between JavaThreads and the VMThread 903 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 904 if ((cur->allow_vm_block() && 905 cur != Threads_lock && 906 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 907 cur != VMOperationRequest_lock && 908 cur != VMOperationQueue_lock) || 909 cur->rank() == Mutex::special) { 910 fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name())); 911 } 912 } 913 } 914 915 if (GCALotAtAllSafepoints) { 916 // We could enter a safepoint here and thus have a gc 917 InterfaceSupport::check_gc_alot(); 918 } 919 #endif 920 } 921 #endif 922 923 bool Thread::is_in_stack(address adr) const { 924 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 925 address end = os::current_stack_pointer(); 926 // Allow non Java threads to call this without stack_base 927 if (_stack_base == NULL) return true; 928 if (stack_base() >= adr && adr >= end) return true; 929 930 return false; 931 } 932 933 934 bool Thread::is_in_usable_stack(address adr) const { 935 size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0; 936 size_t usable_stack_size = _stack_size - stack_guard_size; 937 938 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 939 } 940 941 942 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 943 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 944 // used for compilation in the future. If that change is made, the need for these methods 945 // should be revisited, and they should be removed if possible. 946 947 bool Thread::is_lock_owned(address adr) const { 948 return on_local_stack(adr); 949 } 950 951 bool Thread::set_as_starting_thread() { 952 // NOTE: this must be called inside the main thread. 953 return os::create_main_thread((JavaThread*)this); 954 } 955 956 static void initialize_class(Symbol* class_name, TRAPS) { 957 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 958 InstanceKlass::cast(klass)->initialize(CHECK); 959 } 960 961 962 // Creates the initial ThreadGroup 963 static Handle create_initial_thread_group(TRAPS) { 964 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 965 instanceKlassHandle klass (THREAD, k); 966 967 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 968 { 969 JavaValue result(T_VOID); 970 JavaCalls::call_special(&result, 971 system_instance, 972 klass, 973 vmSymbols::object_initializer_name(), 974 vmSymbols::void_method_signature(), 975 CHECK_NH); 976 } 977 Universe::set_system_thread_group(system_instance()); 978 979 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 980 { 981 JavaValue result(T_VOID); 982 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 983 JavaCalls::call_special(&result, 984 main_instance, 985 klass, 986 vmSymbols::object_initializer_name(), 987 vmSymbols::threadgroup_string_void_signature(), 988 system_instance, 989 string, 990 CHECK_NH); 991 } 992 return main_instance; 993 } 994 995 // Creates the initial Thread 996 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 997 TRAPS) { 998 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 999 instanceKlassHandle klass (THREAD, k); 1000 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 1001 1002 java_lang_Thread::set_thread(thread_oop(), thread); 1003 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1004 thread->set_threadObj(thread_oop()); 1005 1006 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1007 1008 JavaValue result(T_VOID); 1009 JavaCalls::call_special(&result, thread_oop, 1010 klass, 1011 vmSymbols::object_initializer_name(), 1012 vmSymbols::threadgroup_string_void_signature(), 1013 thread_group, 1014 string, 1015 CHECK_NULL); 1016 return thread_oop(); 1017 } 1018 1019 static void call_initializeSystemClass(TRAPS) { 1020 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1021 instanceKlassHandle klass (THREAD, k); 1022 1023 JavaValue result(T_VOID); 1024 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), 1025 vmSymbols::void_method_signature(), CHECK); 1026 } 1027 1028 char java_runtime_name[128] = ""; 1029 char java_runtime_version[128] = ""; 1030 1031 // extract the JRE name from sun.misc.Version.java_runtime_name 1032 static const char* get_java_runtime_name(TRAPS) { 1033 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 1034 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1035 fieldDescriptor fd; 1036 bool found = k != NULL && 1037 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1038 vmSymbols::string_signature(), &fd); 1039 if (found) { 1040 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1041 if (name_oop == NULL) { 1042 return NULL; 1043 } 1044 const char* name = java_lang_String::as_utf8_string(name_oop, 1045 java_runtime_name, 1046 sizeof(java_runtime_name)); 1047 return name; 1048 } else { 1049 return NULL; 1050 } 1051 } 1052 1053 // extract the JRE version from sun.misc.Version.java_runtime_version 1054 static const char* get_java_runtime_version(TRAPS) { 1055 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 1056 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1057 fieldDescriptor fd; 1058 bool found = k != NULL && 1059 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1060 vmSymbols::string_signature(), &fd); 1061 if (found) { 1062 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1063 if (name_oop == NULL) { 1064 return NULL; 1065 } 1066 const char* name = java_lang_String::as_utf8_string(name_oop, 1067 java_runtime_version, 1068 sizeof(java_runtime_version)); 1069 return name; 1070 } else { 1071 return NULL; 1072 } 1073 } 1074 1075 // General purpose hook into Java code, run once when the VM is initialized. 1076 // The Java library method itself may be changed independently from the VM. 1077 static void call_postVMInitHook(TRAPS) { 1078 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD); 1079 instanceKlassHandle klass (THREAD, k); 1080 if (klass.not_null()) { 1081 JavaValue result(T_VOID); 1082 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1083 vmSymbols::void_method_signature(), 1084 CHECK); 1085 } 1086 } 1087 1088 static void reset_vm_info_property(TRAPS) { 1089 // the vm info string 1090 ResourceMark rm(THREAD); 1091 const char *vm_info = VM_Version::vm_info_string(); 1092 1093 // java.lang.System class 1094 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1095 instanceKlassHandle klass (THREAD, k); 1096 1097 // setProperty arguments 1098 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1099 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1100 1101 // return value 1102 JavaValue r(T_OBJECT); 1103 1104 // public static String setProperty(String key, String value); 1105 JavaCalls::call_static(&r, 1106 klass, 1107 vmSymbols::setProperty_name(), 1108 vmSymbols::string_string_string_signature(), 1109 key_str, 1110 value_str, 1111 CHECK); 1112 } 1113 1114 1115 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, 1116 bool daemon, TRAPS) { 1117 assert(thread_group.not_null(), "thread group should be specified"); 1118 assert(threadObj() == NULL, "should only create Java thread object once"); 1119 1120 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1121 instanceKlassHandle klass (THREAD, k); 1122 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1123 1124 java_lang_Thread::set_thread(thread_oop(), this); 1125 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1126 set_threadObj(thread_oop()); 1127 1128 JavaValue result(T_VOID); 1129 if (thread_name != NULL) { 1130 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1131 // Thread gets assigned specified name and null target 1132 JavaCalls::call_special(&result, 1133 thread_oop, 1134 klass, 1135 vmSymbols::object_initializer_name(), 1136 vmSymbols::threadgroup_string_void_signature(), 1137 thread_group, // Argument 1 1138 name, // Argument 2 1139 THREAD); 1140 } else { 1141 // Thread gets assigned name "Thread-nnn" and null target 1142 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1143 JavaCalls::call_special(&result, 1144 thread_oop, 1145 klass, 1146 vmSymbols::object_initializer_name(), 1147 vmSymbols::threadgroup_runnable_void_signature(), 1148 thread_group, // Argument 1 1149 Handle(), // Argument 2 1150 THREAD); 1151 } 1152 1153 1154 if (daemon) { 1155 java_lang_Thread::set_daemon(thread_oop()); 1156 } 1157 1158 if (HAS_PENDING_EXCEPTION) { 1159 return; 1160 } 1161 1162 KlassHandle group(this, SystemDictionary::ThreadGroup_klass()); 1163 Handle threadObj(this, this->threadObj()); 1164 1165 JavaCalls::call_special(&result, 1166 thread_group, 1167 group, 1168 vmSymbols::add_method_name(), 1169 vmSymbols::thread_void_signature(), 1170 threadObj, // Arg 1 1171 THREAD); 1172 1173 1174 } 1175 1176 // NamedThread -- non-JavaThread subclasses with multiple 1177 // uniquely named instances should derive from this. 1178 NamedThread::NamedThread() : Thread() { 1179 _name = NULL; 1180 _processed_thread = NULL; 1181 } 1182 1183 NamedThread::~NamedThread() { 1184 if (_name != NULL) { 1185 FREE_C_HEAP_ARRAY(char, _name, mtThread); 1186 _name = NULL; 1187 } 1188 } 1189 1190 void NamedThread::set_name(const char* format, ...) { 1191 guarantee(_name == NULL, "Only get to set name once."); 1192 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1193 guarantee(_name != NULL, "alloc failure"); 1194 va_list ap; 1195 va_start(ap, format); 1196 jio_vsnprintf(_name, max_name_len, format, ap); 1197 va_end(ap); 1198 } 1199 1200 void NamedThread::print_on(outputStream* st) const { 1201 st->print("\"%s\" ", name()); 1202 Thread::print_on(st); 1203 st->cr(); 1204 } 1205 1206 1207 // ======= WatcherThread ======== 1208 1209 // The watcher thread exists to simulate timer interrupts. It should 1210 // be replaced by an abstraction over whatever native support for 1211 // timer interrupts exists on the platform. 1212 1213 WatcherThread* WatcherThread::_watcher_thread = NULL; 1214 bool WatcherThread::_startable = false; 1215 volatile bool WatcherThread::_should_terminate = false; 1216 1217 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1218 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1219 if (os::create_thread(this, os::watcher_thread)) { 1220 _watcher_thread = this; 1221 1222 // Set the watcher thread to the highest OS priority which should not be 1223 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1224 // is created. The only normal thread using this priority is the reference 1225 // handler thread, which runs for very short intervals only. 1226 // If the VMThread's priority is not lower than the WatcherThread profiling 1227 // will be inaccurate. 1228 os::set_priority(this, MaxPriority); 1229 if (!DisableStartThread) { 1230 os::start_thread(this); 1231 } 1232 } 1233 } 1234 1235 int WatcherThread::sleep() const { 1236 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1237 1238 // remaining will be zero if there are no tasks, 1239 // causing the WatcherThread to sleep until a task is 1240 // enrolled 1241 int remaining = PeriodicTask::time_to_wait(); 1242 int time_slept = 0; 1243 1244 // we expect this to timeout - we only ever get unparked when 1245 // we should terminate or when a new task has been enrolled 1246 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1247 1248 jlong time_before_loop = os::javaTimeNanos(); 1249 1250 for (;;) { 1251 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining); 1252 jlong now = os::javaTimeNanos(); 1253 1254 if (remaining == 0) { 1255 // if we didn't have any tasks we could have waited for a long time 1256 // consider the time_slept zero and reset time_before_loop 1257 time_slept = 0; 1258 time_before_loop = now; 1259 } else { 1260 // need to recalculate since we might have new tasks in _tasks 1261 time_slept = (int) ((now - time_before_loop) / 1000000); 1262 } 1263 1264 // Change to task list or spurious wakeup of some kind 1265 if (timedout || _should_terminate) { 1266 break; 1267 } 1268 1269 remaining = PeriodicTask::time_to_wait(); 1270 if (remaining == 0) { 1271 // Last task was just disenrolled so loop around and wait until 1272 // another task gets enrolled 1273 continue; 1274 } 1275 1276 remaining -= time_slept; 1277 if (remaining <= 0) { 1278 break; 1279 } 1280 } 1281 1282 return time_slept; 1283 } 1284 1285 void WatcherThread::run() { 1286 assert(this == watcher_thread(), "just checking"); 1287 1288 this->record_stack_base_and_size(); 1289 this->initialize_thread_local_storage(); 1290 this->set_active_handles(JNIHandleBlock::allocate_block()); 1291 while (!_should_terminate) { 1292 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1293 assert(watcher_thread() == this, "thread consistency check"); 1294 1295 // Calculate how long it'll be until the next PeriodicTask work 1296 // should be done, and sleep that amount of time. 1297 int time_waited = sleep(); 1298 1299 if (is_error_reported()) { 1300 // A fatal error has happened, the error handler(VMError::report_and_die) 1301 // should abort JVM after creating an error log file. However in some 1302 // rare cases, the error handler itself might deadlock. Here we try to 1303 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1304 // 1305 // This code is in WatcherThread because WatcherThread wakes up 1306 // periodically so the fatal error handler doesn't need to do anything; 1307 // also because the WatcherThread is less likely to crash than other 1308 // threads. 1309 1310 for (;;) { 1311 if (!ShowMessageBoxOnError 1312 && (OnError == NULL || OnError[0] == '\0') 1313 && Arguments::abort_hook() == NULL) { 1314 os::sleep(this, 2 * 60 * 1000, false); 1315 fdStream err(defaultStream::output_fd()); 1316 err.print_raw_cr("# [ timer expired, abort... ]"); 1317 // skip atexit/vm_exit/vm_abort hooks 1318 os::die(); 1319 } 1320 1321 // Wake up 5 seconds later, the fatal handler may reset OnError or 1322 // ShowMessageBoxOnError when it is ready to abort. 1323 os::sleep(this, 5 * 1000, false); 1324 } 1325 } 1326 1327 PeriodicTask::real_time_tick(time_waited); 1328 } 1329 1330 // Signal that it is terminated 1331 { 1332 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1333 _watcher_thread = NULL; 1334 Terminator_lock->notify(); 1335 } 1336 1337 // Thread destructor usually does this.. 1338 ThreadLocalStorage::set_thread(NULL); 1339 } 1340 1341 void WatcherThread::start() { 1342 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1343 1344 if (watcher_thread() == NULL && _startable) { 1345 _should_terminate = false; 1346 // Create the single instance of WatcherThread 1347 new WatcherThread(); 1348 } 1349 } 1350 1351 void WatcherThread::make_startable() { 1352 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1353 _startable = true; 1354 } 1355 1356 void WatcherThread::stop() { 1357 // Get the PeriodicTask_lock if we can. If we cannot, then the 1358 // WatcherThread is using it and we don't want to block on that lock 1359 // here because that might cause a safepoint deadlock depending on 1360 // what the current WatcherThread tasks are doing. 1361 bool have_lock = PeriodicTask_lock->try_lock(); 1362 1363 _should_terminate = true; 1364 OrderAccess::fence(); // ensure WatcherThread sees update in main loop 1365 1366 if (have_lock) { 1367 WatcherThread* watcher = watcher_thread(); 1368 if (watcher != NULL) { 1369 // If we managed to get the lock, then we should unpark the 1370 // WatcherThread so that it can see we want it to stop. 1371 watcher->unpark(); 1372 } 1373 1374 PeriodicTask_lock->unlock(); 1375 } 1376 1377 // it is ok to take late safepoints here, if needed 1378 MutexLocker mu(Terminator_lock); 1379 1380 while (watcher_thread() != NULL) { 1381 // This wait should make safepoint checks, wait without a timeout, 1382 // and wait as a suspend-equivalent condition. 1383 // 1384 // Note: If the FlatProfiler is running, then this thread is waiting 1385 // for the WatcherThread to terminate and the WatcherThread, via the 1386 // FlatProfiler task, is waiting for the external suspend request on 1387 // this thread to complete. wait_for_ext_suspend_completion() will 1388 // eventually timeout, but that takes time. Making this wait a 1389 // suspend-equivalent condition solves that timeout problem. 1390 // 1391 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1392 Mutex::_as_suspend_equivalent_flag); 1393 } 1394 } 1395 1396 void WatcherThread::unpark() { 1397 MutexLockerEx ml(PeriodicTask_lock->owned_by_self() 1398 ? NULL 1399 : PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1400 PeriodicTask_lock->notify(); 1401 } 1402 1403 void WatcherThread::print_on(outputStream* st) const { 1404 st->print("\"%s\" ", name()); 1405 Thread::print_on(st); 1406 st->cr(); 1407 } 1408 1409 // ======= JavaThread ======== 1410 1411 // A JavaThread is a normal Java thread 1412 1413 void JavaThread::initialize() { 1414 // Initialize fields 1415 1416 // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids) 1417 set_claimed_par_id(UINT_MAX); 1418 1419 set_saved_exception_pc(NULL); 1420 set_threadObj(NULL); 1421 _anchor.clear(); 1422 set_entry_point(NULL); 1423 set_jni_functions(jni_functions()); 1424 set_callee_target(NULL); 1425 set_vm_result(NULL); 1426 set_vm_result_2(NULL); 1427 set_vframe_array_head(NULL); 1428 set_vframe_array_last(NULL); 1429 set_deferred_locals(NULL); 1430 set_deopt_mark(NULL); 1431 set_deopt_nmethod(NULL); 1432 clear_must_deopt_id(); 1433 set_monitor_chunks(NULL); 1434 set_next(NULL); 1435 set_thread_state(_thread_new); 1436 _terminated = _not_terminated; 1437 _privileged_stack_top = NULL; 1438 _array_for_gc = NULL; 1439 _suspend_equivalent = false; 1440 _in_deopt_handler = 0; 1441 _doing_unsafe_access = false; 1442 _stack_guard_state = stack_guard_unused; 1443 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1444 _exception_pc = 0; 1445 _exception_handler_pc = 0; 1446 _is_method_handle_return = 0; 1447 _jvmti_thread_state= NULL; 1448 _should_post_on_exceptions_flag = JNI_FALSE; 1449 _jvmti_get_loaded_classes_closure = NULL; 1450 _interp_only_mode = 0; 1451 _special_runtime_exit_condition = _no_async_condition; 1452 _pending_async_exception = NULL; 1453 _thread_stat = NULL; 1454 _thread_stat = new ThreadStatistics(); 1455 _blocked_on_compilation = false; 1456 _jni_active_critical = 0; 1457 _pending_jni_exception_check_fn = NULL; 1458 _do_not_unlock_if_synchronized = false; 1459 _cached_monitor_info = NULL; 1460 _parker = Parker::Allocate(this); 1461 1462 #ifndef PRODUCT 1463 _jmp_ring_index = 0; 1464 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1465 record_jump(NULL, NULL, NULL, 0); 1466 } 1467 #endif // PRODUCT 1468 1469 set_thread_profiler(NULL); 1470 if (FlatProfiler::is_active()) { 1471 // This is where we would decide to either give each thread it's own profiler 1472 // or use one global one from FlatProfiler, 1473 // or up to some count of the number of profiled threads, etc. 1474 ThreadProfiler* pp = new ThreadProfiler(); 1475 pp->engage(); 1476 set_thread_profiler(pp); 1477 } 1478 1479 // Setup safepoint state info for this thread 1480 ThreadSafepointState::create(this); 1481 1482 debug_only(_java_call_counter = 0); 1483 1484 // JVMTI PopFrame support 1485 _popframe_condition = popframe_inactive; 1486 _popframe_preserved_args = NULL; 1487 _popframe_preserved_args_size = 0; 1488 1489 pd_initialize(); 1490 } 1491 1492 #if INCLUDE_ALL_GCS 1493 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1494 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1495 #endif // INCLUDE_ALL_GCS 1496 1497 JavaThread::JavaThread(bool is_attaching_via_jni) : 1498 Thread() 1499 #if INCLUDE_ALL_GCS 1500 , _satb_mark_queue(&_satb_mark_queue_set), 1501 _dirty_card_queue(&_dirty_card_queue_set) 1502 #endif // INCLUDE_ALL_GCS 1503 { 1504 initialize(); 1505 if (is_attaching_via_jni) { 1506 _jni_attach_state = _attaching_via_jni; 1507 } else { 1508 _jni_attach_state = _not_attaching_via_jni; 1509 } 1510 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1511 } 1512 1513 bool JavaThread::reguard_stack(address cur_sp) { 1514 if (_stack_guard_state != stack_guard_yellow_disabled) { 1515 return true; // Stack already guarded or guard pages not needed. 1516 } 1517 1518 if (register_stack_overflow()) { 1519 // For those architectures which have separate register and 1520 // memory stacks, we must check the register stack to see if 1521 // it has overflowed. 1522 return false; 1523 } 1524 1525 // Java code never executes within the yellow zone: the latter is only 1526 // there to provoke an exception during stack banging. If java code 1527 // is executing there, either StackShadowPages should be larger, or 1528 // some exception code in c1, c2 or the interpreter isn't unwinding 1529 // when it should. 1530 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); 1531 1532 enable_stack_yellow_zone(); 1533 return true; 1534 } 1535 1536 bool JavaThread::reguard_stack(void) { 1537 return reguard_stack(os::current_stack_pointer()); 1538 } 1539 1540 1541 void JavaThread::block_if_vm_exited() { 1542 if (_terminated == _vm_exited) { 1543 // _vm_exited is set at safepoint, and Threads_lock is never released 1544 // we will block here forever 1545 Threads_lock->lock_without_safepoint_check(); 1546 ShouldNotReachHere(); 1547 } 1548 } 1549 1550 1551 // Remove this ifdef when C1 is ported to the compiler interface. 1552 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1553 1554 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1555 Thread() 1556 #if INCLUDE_ALL_GCS 1557 , _satb_mark_queue(&_satb_mark_queue_set), 1558 _dirty_card_queue(&_dirty_card_queue_set) 1559 #endif // INCLUDE_ALL_GCS 1560 { 1561 if (TraceThreadEvents) { 1562 tty->print_cr("creating thread %p", this); 1563 } 1564 initialize(); 1565 _jni_attach_state = _not_attaching_via_jni; 1566 set_entry_point(entry_point); 1567 // Create the native thread itself. 1568 // %note runtime_23 1569 os::ThreadType thr_type = os::java_thread; 1570 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1571 os::java_thread; 1572 os::create_thread(this, thr_type, stack_sz); 1573 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1574 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1575 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1576 // the exception consists of creating the exception object & initializing it, initialization 1577 // will leave the VM via a JavaCall and then all locks must be unlocked). 1578 // 1579 // The thread is still suspended when we reach here. Thread must be explicit started 1580 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1581 // by calling Threads:add. The reason why this is not done here, is because the thread 1582 // object must be fully initialized (take a look at JVM_Start) 1583 } 1584 1585 JavaThread::~JavaThread() { 1586 if (TraceThreadEvents) { 1587 tty->print_cr("terminate thread %p", this); 1588 } 1589 1590 // JSR166 -- return the parker to the free list 1591 Parker::Release(_parker); 1592 _parker = NULL; 1593 1594 // Free any remaining previous UnrollBlock 1595 vframeArray* old_array = vframe_array_last(); 1596 1597 if (old_array != NULL) { 1598 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1599 old_array->set_unroll_block(NULL); 1600 delete old_info; 1601 delete old_array; 1602 } 1603 1604 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1605 if (deferred != NULL) { 1606 // This can only happen if thread is destroyed before deoptimization occurs. 1607 assert(deferred->length() != 0, "empty array!"); 1608 do { 1609 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1610 deferred->remove_at(0); 1611 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1612 delete dlv; 1613 } while (deferred->length() != 0); 1614 delete deferred; 1615 } 1616 1617 // All Java related clean up happens in exit 1618 ThreadSafepointState::destroy(this); 1619 if (_thread_profiler != NULL) delete _thread_profiler; 1620 if (_thread_stat != NULL) delete _thread_stat; 1621 } 1622 1623 1624 // The first routine called by a new Java thread 1625 void JavaThread::run() { 1626 // initialize thread-local alloc buffer related fields 1627 this->initialize_tlab(); 1628 1629 // used to test validity of stack trace backs 1630 this->record_base_of_stack_pointer(); 1631 1632 // Record real stack base and size. 1633 this->record_stack_base_and_size(); 1634 1635 // Initialize thread local storage; set before calling MutexLocker 1636 this->initialize_thread_local_storage(); 1637 1638 this->create_stack_guard_pages(); 1639 1640 this->cache_global_variables(); 1641 1642 // Thread is now sufficient initialized to be handled by the safepoint code as being 1643 // in the VM. Change thread state from _thread_new to _thread_in_vm 1644 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1645 1646 assert(JavaThread::current() == this, "sanity check"); 1647 assert(!Thread::current()->owns_locks(), "sanity check"); 1648 1649 DTRACE_THREAD_PROBE(start, this); 1650 1651 // This operation might block. We call that after all safepoint checks for a new thread has 1652 // been completed. 1653 this->set_active_handles(JNIHandleBlock::allocate_block()); 1654 1655 if (JvmtiExport::should_post_thread_life()) { 1656 JvmtiExport::post_thread_start(this); 1657 } 1658 1659 EventThreadStart event; 1660 if (event.should_commit()) { 1661 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1662 event.commit(); 1663 } 1664 1665 // We call another function to do the rest so we are sure that the stack addresses used 1666 // from there will be lower than the stack base just computed 1667 thread_main_inner(); 1668 1669 // Note, thread is no longer valid at this point! 1670 } 1671 1672 1673 void JavaThread::thread_main_inner() { 1674 assert(JavaThread::current() == this, "sanity check"); 1675 assert(this->threadObj() != NULL, "just checking"); 1676 1677 // Execute thread entry point unless this thread has a pending exception 1678 // or has been stopped before starting. 1679 // Note: Due to JVM_StopThread we can have pending exceptions already! 1680 if (!this->has_pending_exception() && 1681 !java_lang_Thread::is_stillborn(this->threadObj())) { 1682 { 1683 ResourceMark rm(this); 1684 this->set_native_thread_name(this->get_thread_name()); 1685 } 1686 HandleMark hm(this); 1687 this->entry_point()(this, this); 1688 } 1689 1690 DTRACE_THREAD_PROBE(stop, this); 1691 1692 this->exit(false); 1693 delete this; 1694 } 1695 1696 1697 static void ensure_join(JavaThread* thread) { 1698 // We do not need to grap the Threads_lock, since we are operating on ourself. 1699 Handle threadObj(thread, thread->threadObj()); 1700 assert(threadObj.not_null(), "java thread object must exist"); 1701 ObjectLocker lock(threadObj, thread); 1702 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1703 thread->clear_pending_exception(); 1704 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1705 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1706 // Clear the native thread instance - this makes isAlive return false and allows the join() 1707 // to complete once we've done the notify_all below 1708 java_lang_Thread::set_thread(threadObj(), NULL); 1709 lock.notify_all(thread); 1710 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1711 thread->clear_pending_exception(); 1712 } 1713 1714 1715 // For any new cleanup additions, please check to see if they need to be applied to 1716 // cleanup_failed_attach_current_thread as well. 1717 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1718 assert(this == JavaThread::current(), "thread consistency check"); 1719 1720 HandleMark hm(this); 1721 Handle uncaught_exception(this, this->pending_exception()); 1722 this->clear_pending_exception(); 1723 Handle threadObj(this, this->threadObj()); 1724 assert(threadObj.not_null(), "Java thread object should be created"); 1725 1726 if (get_thread_profiler() != NULL) { 1727 get_thread_profiler()->disengage(); 1728 ResourceMark rm; 1729 get_thread_profiler()->print(get_thread_name()); 1730 } 1731 1732 1733 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1734 { 1735 EXCEPTION_MARK; 1736 1737 CLEAR_PENDING_EXCEPTION; 1738 } 1739 if (!destroy_vm) { 1740 if (uncaught_exception.not_null()) { 1741 EXCEPTION_MARK; 1742 // Call method Thread.dispatchUncaughtException(). 1743 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1744 JavaValue result(T_VOID); 1745 JavaCalls::call_virtual(&result, 1746 threadObj, thread_klass, 1747 vmSymbols::dispatchUncaughtException_name(), 1748 vmSymbols::throwable_void_signature(), 1749 uncaught_exception, 1750 THREAD); 1751 if (HAS_PENDING_EXCEPTION) { 1752 ResourceMark rm(this); 1753 jio_fprintf(defaultStream::error_stream(), 1754 "\nException: %s thrown from the UncaughtExceptionHandler" 1755 " in thread \"%s\"\n", 1756 pending_exception()->klass()->external_name(), 1757 get_thread_name()); 1758 CLEAR_PENDING_EXCEPTION; 1759 } 1760 } 1761 1762 // Called before the java thread exit since we want to read info 1763 // from java_lang_Thread object 1764 EventThreadEnd event; 1765 if (event.should_commit()) { 1766 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1767 event.commit(); 1768 } 1769 1770 // Call after last event on thread 1771 EVENT_THREAD_EXIT(this); 1772 1773 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1774 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1775 // is deprecated anyhow. 1776 if (!is_Compiler_thread()) { 1777 int count = 3; 1778 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1779 EXCEPTION_MARK; 1780 JavaValue result(T_VOID); 1781 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1782 JavaCalls::call_virtual(&result, 1783 threadObj, thread_klass, 1784 vmSymbols::exit_method_name(), 1785 vmSymbols::void_method_signature(), 1786 THREAD); 1787 CLEAR_PENDING_EXCEPTION; 1788 } 1789 } 1790 // notify JVMTI 1791 if (JvmtiExport::should_post_thread_life()) { 1792 JvmtiExport::post_thread_end(this); 1793 } 1794 1795 // We have notified the agents that we are exiting, before we go on, 1796 // we must check for a pending external suspend request and honor it 1797 // in order to not surprise the thread that made the suspend request. 1798 while (true) { 1799 { 1800 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1801 if (!is_external_suspend()) { 1802 set_terminated(_thread_exiting); 1803 ThreadService::current_thread_exiting(this); 1804 break; 1805 } 1806 // Implied else: 1807 // Things get a little tricky here. We have a pending external 1808 // suspend request, but we are holding the SR_lock so we 1809 // can't just self-suspend. So we temporarily drop the lock 1810 // and then self-suspend. 1811 } 1812 1813 ThreadBlockInVM tbivm(this); 1814 java_suspend_self(); 1815 1816 // We're done with this suspend request, but we have to loop around 1817 // and check again. Eventually we will get SR_lock without a pending 1818 // external suspend request and will be able to mark ourselves as 1819 // exiting. 1820 } 1821 // no more external suspends are allowed at this point 1822 } else { 1823 // before_exit() has already posted JVMTI THREAD_END events 1824 } 1825 1826 // Notify waiters on thread object. This has to be done after exit() is called 1827 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1828 // group should have the destroyed bit set before waiters are notified). 1829 ensure_join(this); 1830 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1831 1832 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1833 // held by this thread must be released. A detach operation must only 1834 // get here if there are no Java frames on the stack. Therefore, any 1835 // owned monitors at this point MUST be JNI-acquired monitors which are 1836 // pre-inflated and in the monitor cache. 1837 // 1838 // ensure_join() ignores IllegalThreadStateExceptions, and so does this. 1839 if (exit_type == jni_detach && JNIDetachReleasesMonitors) { 1840 assert(!this->has_last_Java_frame(), "detaching with Java frames?"); 1841 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1842 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1843 } 1844 1845 // These things needs to be done while we are still a Java Thread. Make sure that thread 1846 // is in a consistent state, in case GC happens 1847 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1848 1849 if (active_handles() != NULL) { 1850 JNIHandleBlock* block = active_handles(); 1851 set_active_handles(NULL); 1852 JNIHandleBlock::release_block(block); 1853 } 1854 1855 if (free_handle_block() != NULL) { 1856 JNIHandleBlock* block = free_handle_block(); 1857 set_free_handle_block(NULL); 1858 JNIHandleBlock::release_block(block); 1859 } 1860 1861 // These have to be removed while this is still a valid thread. 1862 remove_stack_guard_pages(); 1863 1864 if (UseTLAB) { 1865 tlab().make_parsable(true); // retire TLAB 1866 } 1867 1868 if (JvmtiEnv::environments_might_exist()) { 1869 JvmtiExport::cleanup_thread(this); 1870 } 1871 1872 // We must flush any deferred card marks before removing a thread from 1873 // the list of active threads. 1874 Universe::heap()->flush_deferred_store_barrier(this); 1875 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1876 1877 #if INCLUDE_ALL_GCS 1878 // We must flush the G1-related buffers before removing a thread 1879 // from the list of active threads. We must do this after any deferred 1880 // card marks have been flushed (above) so that any entries that are 1881 // added to the thread's dirty card queue as a result are not lost. 1882 if (UseG1GC) { 1883 flush_barrier_queues(); 1884 } 1885 #endif // INCLUDE_ALL_GCS 1886 1887 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1888 Threads::remove(this); 1889 } 1890 1891 #if INCLUDE_ALL_GCS 1892 // Flush G1-related queues. 1893 void JavaThread::flush_barrier_queues() { 1894 satb_mark_queue().flush(); 1895 dirty_card_queue().flush(); 1896 } 1897 1898 void JavaThread::initialize_queues() { 1899 assert(!SafepointSynchronize::is_at_safepoint(), 1900 "we should not be at a safepoint"); 1901 1902 ObjPtrQueue& satb_queue = satb_mark_queue(); 1903 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1904 // The SATB queue should have been constructed with its active 1905 // field set to false. 1906 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1907 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1908 // If we are creating the thread during a marking cycle, we should 1909 // set the active field of the SATB queue to true. 1910 if (satb_queue_set.is_active()) { 1911 satb_queue.set_active(true); 1912 } 1913 1914 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1915 // The dirty card queue should have been constructed with its 1916 // active field set to true. 1917 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1918 } 1919 #endif // INCLUDE_ALL_GCS 1920 1921 void JavaThread::cleanup_failed_attach_current_thread() { 1922 if (get_thread_profiler() != NULL) { 1923 get_thread_profiler()->disengage(); 1924 ResourceMark rm; 1925 get_thread_profiler()->print(get_thread_name()); 1926 } 1927 1928 if (active_handles() != NULL) { 1929 JNIHandleBlock* block = active_handles(); 1930 set_active_handles(NULL); 1931 JNIHandleBlock::release_block(block); 1932 } 1933 1934 if (free_handle_block() != NULL) { 1935 JNIHandleBlock* block = free_handle_block(); 1936 set_free_handle_block(NULL); 1937 JNIHandleBlock::release_block(block); 1938 } 1939 1940 // These have to be removed while this is still a valid thread. 1941 remove_stack_guard_pages(); 1942 1943 if (UseTLAB) { 1944 tlab().make_parsable(true); // retire TLAB, if any 1945 } 1946 1947 #if INCLUDE_ALL_GCS 1948 if (UseG1GC) { 1949 flush_barrier_queues(); 1950 } 1951 #endif // INCLUDE_ALL_GCS 1952 1953 Threads::remove(this); 1954 delete this; 1955 } 1956 1957 1958 1959 1960 JavaThread* JavaThread::active() { 1961 Thread* thread = ThreadLocalStorage::thread(); 1962 assert(thread != NULL, "just checking"); 1963 if (thread->is_Java_thread()) { 1964 return (JavaThread*) thread; 1965 } else { 1966 assert(thread->is_VM_thread(), "this must be a vm thread"); 1967 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1968 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1969 assert(ret->is_Java_thread(), "must be a Java thread"); 1970 return ret; 1971 } 1972 } 1973 1974 bool JavaThread::is_lock_owned(address adr) const { 1975 if (Thread::is_lock_owned(adr)) return true; 1976 1977 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1978 if (chunk->contains(adr)) return true; 1979 } 1980 1981 return false; 1982 } 1983 1984 1985 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 1986 chunk->set_next(monitor_chunks()); 1987 set_monitor_chunks(chunk); 1988 } 1989 1990 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 1991 guarantee(monitor_chunks() != NULL, "must be non empty"); 1992 if (monitor_chunks() == chunk) { 1993 set_monitor_chunks(chunk->next()); 1994 } else { 1995 MonitorChunk* prev = monitor_chunks(); 1996 while (prev->next() != chunk) prev = prev->next(); 1997 prev->set_next(chunk->next()); 1998 } 1999 } 2000 2001 // JVM support. 2002 2003 // Note: this function shouldn't block if it's called in 2004 // _thread_in_native_trans state (such as from 2005 // check_special_condition_for_native_trans()). 2006 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2007 2008 if (has_last_Java_frame() && has_async_condition()) { 2009 // If we are at a polling page safepoint (not a poll return) 2010 // then we must defer async exception because live registers 2011 // will be clobbered by the exception path. Poll return is 2012 // ok because the call we a returning from already collides 2013 // with exception handling registers and so there is no issue. 2014 // (The exception handling path kills call result registers but 2015 // this is ok since the exception kills the result anyway). 2016 2017 if (is_at_poll_safepoint()) { 2018 // if the code we are returning to has deoptimized we must defer 2019 // the exception otherwise live registers get clobbered on the 2020 // exception path before deoptimization is able to retrieve them. 2021 // 2022 RegisterMap map(this, false); 2023 frame caller_fr = last_frame().sender(&map); 2024 assert(caller_fr.is_compiled_frame(), "what?"); 2025 if (caller_fr.is_deoptimized_frame()) { 2026 if (TraceExceptions) { 2027 ResourceMark rm; 2028 tty->print_cr("deferred async exception at compiled safepoint"); 2029 } 2030 return; 2031 } 2032 } 2033 } 2034 2035 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2036 if (condition == _no_async_condition) { 2037 // Conditions have changed since has_special_runtime_exit_condition() 2038 // was called: 2039 // - if we were here only because of an external suspend request, 2040 // then that was taken care of above (or cancelled) so we are done 2041 // - if we were here because of another async request, then it has 2042 // been cleared between the has_special_runtime_exit_condition() 2043 // and now so again we are done 2044 return; 2045 } 2046 2047 // Check for pending async. exception 2048 if (_pending_async_exception != NULL) { 2049 // Only overwrite an already pending exception, if it is not a threadDeath. 2050 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2051 2052 // We cannot call Exceptions::_throw(...) here because we cannot block 2053 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2054 2055 if (TraceExceptions) { 2056 ResourceMark rm; 2057 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); 2058 if (has_last_Java_frame()) { 2059 frame f = last_frame(); 2060 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); 2061 } 2062 tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2063 } 2064 _pending_async_exception = NULL; 2065 clear_has_async_exception(); 2066 } 2067 } 2068 2069 if (check_unsafe_error && 2070 condition == _async_unsafe_access_error && !has_pending_exception()) { 2071 condition = _no_async_condition; // done 2072 switch (thread_state()) { 2073 case _thread_in_vm: { 2074 JavaThread* THREAD = this; 2075 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2076 } 2077 case _thread_in_native: { 2078 ThreadInVMfromNative tiv(this); 2079 JavaThread* THREAD = this; 2080 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2081 } 2082 case _thread_in_Java: { 2083 ThreadInVMfromJava tiv(this); 2084 JavaThread* THREAD = this; 2085 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2086 } 2087 default: 2088 ShouldNotReachHere(); 2089 } 2090 } 2091 2092 assert(condition == _no_async_condition || has_pending_exception() || 2093 (!check_unsafe_error && condition == _async_unsafe_access_error), 2094 "must have handled the async condition, if no exception"); 2095 } 2096 2097 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2098 // 2099 // Check for pending external suspend. Internal suspend requests do 2100 // not use handle_special_runtime_exit_condition(). 2101 // If JNIEnv proxies are allowed, don't self-suspend if the target 2102 // thread is not the current thread. In older versions of jdbx, jdbx 2103 // threads could call into the VM with another thread's JNIEnv so we 2104 // can be here operating on behalf of a suspended thread (4432884). 2105 bool do_self_suspend = is_external_suspend_with_lock(); 2106 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2107 // 2108 // Because thread is external suspended the safepoint code will count 2109 // thread as at a safepoint. This can be odd because we can be here 2110 // as _thread_in_Java which would normally transition to _thread_blocked 2111 // at a safepoint. We would like to mark the thread as _thread_blocked 2112 // before calling java_suspend_self like all other callers of it but 2113 // we must then observe proper safepoint protocol. (We can't leave 2114 // _thread_blocked with a safepoint in progress). However we can be 2115 // here as _thread_in_native_trans so we can't use a normal transition 2116 // constructor/destructor pair because they assert on that type of 2117 // transition. We could do something like: 2118 // 2119 // JavaThreadState state = thread_state(); 2120 // set_thread_state(_thread_in_vm); 2121 // { 2122 // ThreadBlockInVM tbivm(this); 2123 // java_suspend_self() 2124 // } 2125 // set_thread_state(_thread_in_vm_trans); 2126 // if (safepoint) block; 2127 // set_thread_state(state); 2128 // 2129 // but that is pretty messy. Instead we just go with the way the 2130 // code has worked before and note that this is the only path to 2131 // java_suspend_self that doesn't put the thread in _thread_blocked 2132 // mode. 2133 2134 frame_anchor()->make_walkable(this); 2135 java_suspend_self(); 2136 2137 // We might be here for reasons in addition to the self-suspend request 2138 // so check for other async requests. 2139 } 2140 2141 if (check_asyncs) { 2142 check_and_handle_async_exceptions(); 2143 } 2144 } 2145 2146 void JavaThread::send_thread_stop(oop java_throwable) { 2147 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2148 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2149 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2150 2151 // Do not throw asynchronous exceptions against the compiler thread 2152 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2153 if (is_Compiler_thread()) return; 2154 2155 { 2156 // Actually throw the Throwable against the target Thread - however 2157 // only if there is no thread death exception installed already. 2158 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2159 // If the topmost frame is a runtime stub, then we are calling into 2160 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2161 // must deoptimize the caller before continuing, as the compiled exception handler table 2162 // may not be valid 2163 if (has_last_Java_frame()) { 2164 frame f = last_frame(); 2165 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2166 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2167 RegisterMap reg_map(this, UseBiasedLocking); 2168 frame compiled_frame = f.sender(®_map); 2169 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2170 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2171 } 2172 } 2173 } 2174 2175 // Set async. pending exception in thread. 2176 set_pending_async_exception(java_throwable); 2177 2178 if (TraceExceptions) { 2179 ResourceMark rm; 2180 tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2181 } 2182 // for AbortVMOnException flag 2183 NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name())); 2184 } 2185 } 2186 2187 2188 // Interrupt thread so it will wake up from a potential wait() 2189 Thread::interrupt(this); 2190 } 2191 2192 // External suspension mechanism. 2193 // 2194 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2195 // to any VM_locks and it is at a transition 2196 // Self-suspension will happen on the transition out of the vm. 2197 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2198 // 2199 // Guarantees on return: 2200 // + Target thread will not execute any new bytecode (that's why we need to 2201 // force a safepoint) 2202 // + Target thread will not enter any new monitors 2203 // 2204 void JavaThread::java_suspend() { 2205 { MutexLocker mu(Threads_lock); 2206 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2207 return; 2208 } 2209 } 2210 2211 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2212 if (!is_external_suspend()) { 2213 // a racing resume has cancelled us; bail out now 2214 return; 2215 } 2216 2217 // suspend is done 2218 uint32_t debug_bits = 0; 2219 // Warning: is_ext_suspend_completed() may temporarily drop the 2220 // SR_lock to allow the thread to reach a stable thread state if 2221 // it is currently in a transient thread state. 2222 if (is_ext_suspend_completed(false /* !called_by_wait */, 2223 SuspendRetryDelay, &debug_bits)) { 2224 return; 2225 } 2226 } 2227 2228 VM_ForceSafepoint vm_suspend; 2229 VMThread::execute(&vm_suspend); 2230 } 2231 2232 // Part II of external suspension. 2233 // A JavaThread self suspends when it detects a pending external suspend 2234 // request. This is usually on transitions. It is also done in places 2235 // where continuing to the next transition would surprise the caller, 2236 // e.g., monitor entry. 2237 // 2238 // Returns the number of times that the thread self-suspended. 2239 // 2240 // Note: DO NOT call java_suspend_self() when you just want to block current 2241 // thread. java_suspend_self() is the second stage of cooperative 2242 // suspension for external suspend requests and should only be used 2243 // to complete an external suspend request. 2244 // 2245 int JavaThread::java_suspend_self() { 2246 int ret = 0; 2247 2248 // we are in the process of exiting so don't suspend 2249 if (is_exiting()) { 2250 clear_external_suspend(); 2251 return ret; 2252 } 2253 2254 assert(_anchor.walkable() || 2255 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2256 "must have walkable stack"); 2257 2258 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2259 2260 assert(!this->is_ext_suspended(), 2261 "a thread trying to self-suspend should not already be suspended"); 2262 2263 if (this->is_suspend_equivalent()) { 2264 // If we are self-suspending as a result of the lifting of a 2265 // suspend equivalent condition, then the suspend_equivalent 2266 // flag is not cleared until we set the ext_suspended flag so 2267 // that wait_for_ext_suspend_completion() returns consistent 2268 // results. 2269 this->clear_suspend_equivalent(); 2270 } 2271 2272 // A racing resume may have cancelled us before we grabbed SR_lock 2273 // above. Or another external suspend request could be waiting for us 2274 // by the time we return from SR_lock()->wait(). The thread 2275 // that requested the suspension may already be trying to walk our 2276 // stack and if we return now, we can change the stack out from under 2277 // it. This would be a "bad thing (TM)" and cause the stack walker 2278 // to crash. We stay self-suspended until there are no more pending 2279 // external suspend requests. 2280 while (is_external_suspend()) { 2281 ret++; 2282 this->set_ext_suspended(); 2283 2284 // _ext_suspended flag is cleared by java_resume() 2285 while (is_ext_suspended()) { 2286 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2287 } 2288 } 2289 2290 return ret; 2291 } 2292 2293 #ifdef ASSERT 2294 // verify the JavaThread has not yet been published in the Threads::list, and 2295 // hence doesn't need protection from concurrent access at this stage 2296 void JavaThread::verify_not_published() { 2297 if (!Threads_lock->owned_by_self()) { 2298 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2299 assert(!Threads::includes(this), 2300 "java thread shouldn't have been published yet!"); 2301 } else { 2302 assert(!Threads::includes(this), 2303 "java thread shouldn't have been published yet!"); 2304 } 2305 } 2306 #endif 2307 2308 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2309 // progress or when _suspend_flags is non-zero. 2310 // Current thread needs to self-suspend if there is a suspend request and/or 2311 // block if a safepoint is in progress. 2312 // Async exception ISN'T checked. 2313 // Note only the ThreadInVMfromNative transition can call this function 2314 // directly and when thread state is _thread_in_native_trans 2315 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2316 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2317 2318 JavaThread *curJT = JavaThread::current(); 2319 bool do_self_suspend = thread->is_external_suspend(); 2320 2321 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2322 2323 // If JNIEnv proxies are allowed, don't self-suspend if the target 2324 // thread is not the current thread. In older versions of jdbx, jdbx 2325 // threads could call into the VM with another thread's JNIEnv so we 2326 // can be here operating on behalf of a suspended thread (4432884). 2327 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2328 JavaThreadState state = thread->thread_state(); 2329 2330 // We mark this thread_blocked state as a suspend-equivalent so 2331 // that a caller to is_ext_suspend_completed() won't be confused. 2332 // The suspend-equivalent state is cleared by java_suspend_self(). 2333 thread->set_suspend_equivalent(); 2334 2335 // If the safepoint code sees the _thread_in_native_trans state, it will 2336 // wait until the thread changes to other thread state. There is no 2337 // guarantee on how soon we can obtain the SR_lock and complete the 2338 // self-suspend request. It would be a bad idea to let safepoint wait for 2339 // too long. Temporarily change the state to _thread_blocked to 2340 // let the VM thread know that this thread is ready for GC. The problem 2341 // of changing thread state is that safepoint could happen just after 2342 // java_suspend_self() returns after being resumed, and VM thread will 2343 // see the _thread_blocked state. We must check for safepoint 2344 // after restoring the state and make sure we won't leave while a safepoint 2345 // is in progress. 2346 thread->set_thread_state(_thread_blocked); 2347 thread->java_suspend_self(); 2348 thread->set_thread_state(state); 2349 // Make sure new state is seen by VM thread 2350 if (os::is_MP()) { 2351 if (UseMembar) { 2352 // Force a fence between the write above and read below 2353 OrderAccess::fence(); 2354 } else { 2355 // Must use this rather than serialization page in particular on Windows 2356 InterfaceSupport::serialize_memory(thread); 2357 } 2358 } 2359 } 2360 2361 if (SafepointSynchronize::do_call_back()) { 2362 // If we are safepointing, then block the caller which may not be 2363 // the same as the target thread (see above). 2364 SafepointSynchronize::block(curJT); 2365 } 2366 2367 if (thread->is_deopt_suspend()) { 2368 thread->clear_deopt_suspend(); 2369 RegisterMap map(thread, false); 2370 frame f = thread->last_frame(); 2371 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2372 f = f.sender(&map); 2373 } 2374 if (f.id() == thread->must_deopt_id()) { 2375 thread->clear_must_deopt_id(); 2376 f.deoptimize(thread); 2377 } else { 2378 fatal("missed deoptimization!"); 2379 } 2380 } 2381 } 2382 2383 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2384 // progress or when _suspend_flags is non-zero. 2385 // Current thread needs to self-suspend if there is a suspend request and/or 2386 // block if a safepoint is in progress. 2387 // Also check for pending async exception (not including unsafe access error). 2388 // Note only the native==>VM/Java barriers can call this function and when 2389 // thread state is _thread_in_native_trans. 2390 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2391 check_safepoint_and_suspend_for_native_trans(thread); 2392 2393 if (thread->has_async_exception()) { 2394 // We are in _thread_in_native_trans state, don't handle unsafe 2395 // access error since that may block. 2396 thread->check_and_handle_async_exceptions(false); 2397 } 2398 } 2399 2400 // This is a variant of the normal 2401 // check_special_condition_for_native_trans with slightly different 2402 // semantics for use by critical native wrappers. It does all the 2403 // normal checks but also performs the transition back into 2404 // thread_in_Java state. This is required so that critical natives 2405 // can potentially block and perform a GC if they are the last thread 2406 // exiting the GC_locker. 2407 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2408 check_special_condition_for_native_trans(thread); 2409 2410 // Finish the transition 2411 thread->set_thread_state(_thread_in_Java); 2412 2413 if (thread->do_critical_native_unlock()) { 2414 ThreadInVMfromJavaNoAsyncException tiv(thread); 2415 GC_locker::unlock_critical(thread); 2416 thread->clear_critical_native_unlock(); 2417 } 2418 } 2419 2420 // We need to guarantee the Threads_lock here, since resumes are not 2421 // allowed during safepoint synchronization 2422 // Can only resume from an external suspension 2423 void JavaThread::java_resume() { 2424 assert_locked_or_safepoint(Threads_lock); 2425 2426 // Sanity check: thread is gone, has started exiting or the thread 2427 // was not externally suspended. 2428 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2429 return; 2430 } 2431 2432 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2433 2434 clear_external_suspend(); 2435 2436 if (is_ext_suspended()) { 2437 clear_ext_suspended(); 2438 SR_lock()->notify_all(); 2439 } 2440 } 2441 2442 void JavaThread::create_stack_guard_pages() { 2443 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; 2444 address low_addr = stack_base() - stack_size(); 2445 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2446 2447 int allocate = os::allocate_stack_guard_pages(); 2448 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2449 2450 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2451 warning("Attempt to allocate stack guard pages failed."); 2452 return; 2453 } 2454 2455 if (os::guard_memory((char *) low_addr, len)) { 2456 _stack_guard_state = stack_guard_enabled; 2457 } else { 2458 warning("Attempt to protect stack guard pages failed."); 2459 if (os::uncommit_memory((char *) low_addr, len)) { 2460 warning("Attempt to deallocate stack guard pages failed."); 2461 } 2462 } 2463 } 2464 2465 void JavaThread::remove_stack_guard_pages() { 2466 assert(Thread::current() == this, "from different thread"); 2467 if (_stack_guard_state == stack_guard_unused) return; 2468 address low_addr = stack_base() - stack_size(); 2469 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2470 2471 if (os::allocate_stack_guard_pages()) { 2472 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2473 _stack_guard_state = stack_guard_unused; 2474 } else { 2475 warning("Attempt to deallocate stack guard pages failed."); 2476 } 2477 } else { 2478 if (_stack_guard_state == stack_guard_unused) return; 2479 if (os::unguard_memory((char *) low_addr, len)) { 2480 _stack_guard_state = stack_guard_unused; 2481 } else { 2482 warning("Attempt to unprotect stack guard pages failed."); 2483 } 2484 } 2485 } 2486 2487 void JavaThread::enable_stack_yellow_zone() { 2488 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2489 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2490 2491 // The base notation is from the stacks point of view, growing downward. 2492 // We need to adjust it to work correctly with guard_memory() 2493 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2494 2495 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2496 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2497 2498 if (os::guard_memory((char *) base, stack_yellow_zone_size())) { 2499 _stack_guard_state = stack_guard_enabled; 2500 } else { 2501 warning("Attempt to guard stack yellow zone failed."); 2502 } 2503 enable_register_stack_guard(); 2504 } 2505 2506 void JavaThread::disable_stack_yellow_zone() { 2507 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2508 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); 2509 2510 // Simply return if called for a thread that does not use guard pages. 2511 if (_stack_guard_state == stack_guard_unused) return; 2512 2513 // The base notation is from the stacks point of view, growing downward. 2514 // We need to adjust it to work correctly with guard_memory() 2515 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2516 2517 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { 2518 _stack_guard_state = stack_guard_yellow_disabled; 2519 } else { 2520 warning("Attempt to unguard stack yellow zone failed."); 2521 } 2522 disable_register_stack_guard(); 2523 } 2524 2525 void JavaThread::enable_stack_red_zone() { 2526 // The base notation is from the stacks point of view, growing downward. 2527 // We need to adjust it to work correctly with guard_memory() 2528 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2529 address base = stack_red_zone_base() - stack_red_zone_size(); 2530 2531 guarantee(base < stack_base(), "Error calculating stack red zone"); 2532 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2533 2534 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2535 warning("Attempt to guard stack red zone failed."); 2536 } 2537 } 2538 2539 void JavaThread::disable_stack_red_zone() { 2540 // The base notation is from the stacks point of view, growing downward. 2541 // We need to adjust it to work correctly with guard_memory() 2542 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2543 address base = stack_red_zone_base() - stack_red_zone_size(); 2544 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2545 warning("Attempt to unguard stack red zone failed."); 2546 } 2547 } 2548 2549 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2550 // ignore is there is no stack 2551 if (!has_last_Java_frame()) return; 2552 // traverse the stack frames. Starts from top frame. 2553 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2554 frame* fr = fst.current(); 2555 f(fr, fst.register_map()); 2556 } 2557 } 2558 2559 2560 #ifndef PRODUCT 2561 // Deoptimization 2562 // Function for testing deoptimization 2563 void JavaThread::deoptimize() { 2564 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2565 StackFrameStream fst(this, UseBiasedLocking); 2566 bool deopt = false; // Dump stack only if a deopt actually happens. 2567 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2568 // Iterate over all frames in the thread and deoptimize 2569 for (; !fst.is_done(); fst.next()) { 2570 if (fst.current()->can_be_deoptimized()) { 2571 2572 if (only_at) { 2573 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2574 // consists of comma or carriage return separated numbers so 2575 // search for the current bci in that string. 2576 address pc = fst.current()->pc(); 2577 nmethod* nm = (nmethod*) fst.current()->cb(); 2578 ScopeDesc* sd = nm->scope_desc_at(pc); 2579 char buffer[8]; 2580 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2581 size_t len = strlen(buffer); 2582 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2583 while (found != NULL) { 2584 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2585 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2586 // Check that the bci found is bracketed by terminators. 2587 break; 2588 } 2589 found = strstr(found + 1, buffer); 2590 } 2591 if (!found) { 2592 continue; 2593 } 2594 } 2595 2596 if (DebugDeoptimization && !deopt) { 2597 deopt = true; // One-time only print before deopt 2598 tty->print_cr("[BEFORE Deoptimization]"); 2599 trace_frames(); 2600 trace_stack(); 2601 } 2602 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2603 } 2604 } 2605 2606 if (DebugDeoptimization && deopt) { 2607 tty->print_cr("[AFTER Deoptimization]"); 2608 trace_frames(); 2609 } 2610 } 2611 2612 2613 // Make zombies 2614 void JavaThread::make_zombies() { 2615 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2616 if (fst.current()->can_be_deoptimized()) { 2617 // it is a Java nmethod 2618 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2619 nm->make_not_entrant(); 2620 } 2621 } 2622 } 2623 #endif // PRODUCT 2624 2625 2626 void JavaThread::deoptimized_wrt_marked_nmethods() { 2627 if (!has_last_Java_frame()) return; 2628 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2629 StackFrameStream fst(this, UseBiasedLocking); 2630 for (; !fst.is_done(); fst.next()) { 2631 if (fst.current()->should_be_deoptimized()) { 2632 if (LogCompilation && xtty != NULL) { 2633 nmethod* nm = fst.current()->cb()->as_nmethod_or_null(); 2634 xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'", 2635 this->name(), nm != NULL ? nm->compile_id() : -1); 2636 } 2637 2638 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2639 } 2640 } 2641 } 2642 2643 2644 // If the caller is a NamedThread, then remember, in the current scope, 2645 // the given JavaThread in its _processed_thread field. 2646 class RememberProcessedThread: public StackObj { 2647 NamedThread* _cur_thr; 2648 public: 2649 RememberProcessedThread(JavaThread* jthr) { 2650 Thread* thread = Thread::current(); 2651 if (thread->is_Named_thread()) { 2652 _cur_thr = (NamedThread *)thread; 2653 _cur_thr->set_processed_thread(jthr); 2654 } else { 2655 _cur_thr = NULL; 2656 } 2657 } 2658 2659 ~RememberProcessedThread() { 2660 if (_cur_thr) { 2661 _cur_thr->set_processed_thread(NULL); 2662 } 2663 } 2664 }; 2665 2666 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 2667 // Verify that the deferred card marks have been flushed. 2668 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2669 2670 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2671 // since there may be more than one thread using each ThreadProfiler. 2672 2673 // Traverse the GCHandles 2674 Thread::oops_do(f, cld_f, cf); 2675 2676 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2677 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2678 2679 if (has_last_Java_frame()) { 2680 // Record JavaThread to GC thread 2681 RememberProcessedThread rpt(this); 2682 2683 // Traverse the privileged stack 2684 if (_privileged_stack_top != NULL) { 2685 _privileged_stack_top->oops_do(f); 2686 } 2687 2688 // traverse the registered growable array 2689 if (_array_for_gc != NULL) { 2690 for (int index = 0; index < _array_for_gc->length(); index++) { 2691 f->do_oop(_array_for_gc->adr_at(index)); 2692 } 2693 } 2694 2695 // Traverse the monitor chunks 2696 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2697 chunk->oops_do(f); 2698 } 2699 2700 // Traverse the execution stack 2701 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2702 fst.current()->oops_do(f, cld_f, cf, fst.register_map()); 2703 } 2704 } 2705 2706 // callee_target is never live across a gc point so NULL it here should 2707 // it still contain a methdOop. 2708 2709 set_callee_target(NULL); 2710 2711 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2712 // If we have deferred set_locals there might be oops waiting to be 2713 // written 2714 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2715 if (list != NULL) { 2716 for (int i = 0; i < list->length(); i++) { 2717 list->at(i)->oops_do(f); 2718 } 2719 } 2720 2721 // Traverse instance variables at the end since the GC may be moving things 2722 // around using this function 2723 f->do_oop((oop*) &_threadObj); 2724 f->do_oop((oop*) &_vm_result); 2725 f->do_oop((oop*) &_exception_oop); 2726 f->do_oop((oop*) &_pending_async_exception); 2727 2728 if (jvmti_thread_state() != NULL) { 2729 jvmti_thread_state()->oops_do(f); 2730 } 2731 } 2732 2733 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2734 Thread::nmethods_do(cf); // (super method is a no-op) 2735 2736 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2737 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2738 2739 if (has_last_Java_frame()) { 2740 // Traverse the execution stack 2741 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2742 fst.current()->nmethods_do(cf); 2743 } 2744 } 2745 } 2746 2747 void JavaThread::metadata_do(void f(Metadata*)) { 2748 Thread::metadata_do(f); 2749 if (has_last_Java_frame()) { 2750 // Traverse the execution stack to call f() on the methods in the stack 2751 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2752 fst.current()->metadata_do(f); 2753 } 2754 } else if (is_Compiler_thread()) { 2755 // need to walk ciMetadata in current compile tasks to keep alive. 2756 CompilerThread* ct = (CompilerThread*)this; 2757 if (ct->env() != NULL) { 2758 ct->env()->metadata_do(f); 2759 } 2760 } 2761 } 2762 2763 // Printing 2764 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2765 switch (_thread_state) { 2766 case _thread_uninitialized: return "_thread_uninitialized"; 2767 case _thread_new: return "_thread_new"; 2768 case _thread_new_trans: return "_thread_new_trans"; 2769 case _thread_in_native: return "_thread_in_native"; 2770 case _thread_in_native_trans: return "_thread_in_native_trans"; 2771 case _thread_in_vm: return "_thread_in_vm"; 2772 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2773 case _thread_in_Java: return "_thread_in_Java"; 2774 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2775 case _thread_blocked: return "_thread_blocked"; 2776 case _thread_blocked_trans: return "_thread_blocked_trans"; 2777 default: return "unknown thread state"; 2778 } 2779 } 2780 2781 #ifndef PRODUCT 2782 void JavaThread::print_thread_state_on(outputStream *st) const { 2783 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2784 }; 2785 void JavaThread::print_thread_state() const { 2786 print_thread_state_on(tty); 2787 } 2788 #endif // PRODUCT 2789 2790 // Called by Threads::print() for VM_PrintThreads operation 2791 void JavaThread::print_on(outputStream *st) const { 2792 st->print("\"%s\" ", get_thread_name()); 2793 oop thread_oop = threadObj(); 2794 if (thread_oop != NULL) { 2795 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2796 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2797 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2798 } 2799 Thread::print_on(st); 2800 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2801 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2802 if (thread_oop != NULL) { 2803 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2804 } 2805 #ifndef PRODUCT 2806 print_thread_state_on(st); 2807 _safepoint_state->print_on(st); 2808 #endif // PRODUCT 2809 } 2810 2811 // Called by fatal error handler. The difference between this and 2812 // JavaThread::print() is that we can't grab lock or allocate memory. 2813 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2814 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2815 oop thread_obj = threadObj(); 2816 if (thread_obj != NULL) { 2817 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2818 } 2819 st->print(" ["); 2820 st->print("%s", _get_thread_state_name(_thread_state)); 2821 if (osthread()) { 2822 st->print(", id=%d", osthread()->thread_id()); 2823 } 2824 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2825 _stack_base - _stack_size, _stack_base); 2826 st->print("]"); 2827 return; 2828 } 2829 2830 // Verification 2831 2832 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2833 2834 void JavaThread::verify() { 2835 // Verify oops in the thread. 2836 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); 2837 2838 // Verify the stack frames. 2839 frames_do(frame_verify); 2840 } 2841 2842 // CR 6300358 (sub-CR 2137150) 2843 // Most callers of this method assume that it can't return NULL but a 2844 // thread may not have a name whilst it is in the process of attaching to 2845 // the VM - see CR 6412693, and there are places where a JavaThread can be 2846 // seen prior to having it's threadObj set (eg JNI attaching threads and 2847 // if vm exit occurs during initialization). These cases can all be accounted 2848 // for such that this method never returns NULL. 2849 const char* JavaThread::get_thread_name() const { 2850 #ifdef ASSERT 2851 // early safepoints can hit while current thread does not yet have TLS 2852 if (!SafepointSynchronize::is_at_safepoint()) { 2853 Thread *cur = Thread::current(); 2854 if (!(cur->is_Java_thread() && cur == this)) { 2855 // Current JavaThreads are allowed to get their own name without 2856 // the Threads_lock. 2857 assert_locked_or_safepoint(Threads_lock); 2858 } 2859 } 2860 #endif // ASSERT 2861 return get_thread_name_string(); 2862 } 2863 2864 // Returns a non-NULL representation of this thread's name, or a suitable 2865 // descriptive string if there is no set name 2866 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2867 const char* name_str; 2868 oop thread_obj = threadObj(); 2869 if (thread_obj != NULL) { 2870 typeArrayOop name = java_lang_Thread::name(thread_obj); 2871 if (name != NULL) { 2872 if (buf == NULL) { 2873 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), 2874 name->length()); 2875 } else { 2876 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), 2877 name->length(), buf, buflen); 2878 } 2879 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2880 name_str = "<no-name - thread is attaching>"; 2881 } else { 2882 name_str = Thread::name(); 2883 } 2884 } else { 2885 name_str = Thread::name(); 2886 } 2887 assert(name_str != NULL, "unexpected NULL thread name"); 2888 return name_str; 2889 } 2890 2891 2892 const char* JavaThread::get_threadgroup_name() const { 2893 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2894 oop thread_obj = threadObj(); 2895 if (thread_obj != NULL) { 2896 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2897 if (thread_group != NULL) { 2898 typeArrayOop name = java_lang_ThreadGroup::name(thread_group); 2899 // ThreadGroup.name can be null 2900 if (name != NULL) { 2901 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2902 return str; 2903 } 2904 } 2905 } 2906 return NULL; 2907 } 2908 2909 const char* JavaThread::get_parent_name() const { 2910 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2911 oop thread_obj = threadObj(); 2912 if (thread_obj != NULL) { 2913 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2914 if (thread_group != NULL) { 2915 oop parent = java_lang_ThreadGroup::parent(thread_group); 2916 if (parent != NULL) { 2917 typeArrayOop name = java_lang_ThreadGroup::name(parent); 2918 // ThreadGroup.name can be null 2919 if (name != NULL) { 2920 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2921 return str; 2922 } 2923 } 2924 } 2925 } 2926 return NULL; 2927 } 2928 2929 ThreadPriority JavaThread::java_priority() const { 2930 oop thr_oop = threadObj(); 2931 if (thr_oop == NULL) return NormPriority; // Bootstrapping 2932 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 2933 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 2934 return priority; 2935 } 2936 2937 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 2938 2939 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 2940 // Link Java Thread object <-> C++ Thread 2941 2942 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 2943 // and put it into a new Handle. The Handle "thread_oop" can then 2944 // be used to pass the C++ thread object to other methods. 2945 2946 // Set the Java level thread object (jthread) field of the 2947 // new thread (a JavaThread *) to C++ thread object using the 2948 // "thread_oop" handle. 2949 2950 // Set the thread field (a JavaThread *) of the 2951 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 2952 2953 Handle thread_oop(Thread::current(), 2954 JNIHandles::resolve_non_null(jni_thread)); 2955 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 2956 "must be initialized"); 2957 set_threadObj(thread_oop()); 2958 java_lang_Thread::set_thread(thread_oop(), this); 2959 2960 if (prio == NoPriority) { 2961 prio = java_lang_Thread::priority(thread_oop()); 2962 assert(prio != NoPriority, "A valid priority should be present"); 2963 } 2964 2965 // Push the Java priority down to the native thread; needs Threads_lock 2966 Thread::set_priority(this, prio); 2967 2968 prepare_ext(); 2969 2970 // Add the new thread to the Threads list and set it in motion. 2971 // We must have threads lock in order to call Threads::add. 2972 // It is crucial that we do not block before the thread is 2973 // added to the Threads list for if a GC happens, then the java_thread oop 2974 // will not be visited by GC. 2975 Threads::add(this); 2976 } 2977 2978 oop JavaThread::current_park_blocker() { 2979 // Support for JSR-166 locks 2980 oop thread_oop = threadObj(); 2981 if (thread_oop != NULL && 2982 JDK_Version::current().supports_thread_park_blocker()) { 2983 return java_lang_Thread::park_blocker(thread_oop); 2984 } 2985 return NULL; 2986 } 2987 2988 2989 void JavaThread::print_stack_on(outputStream* st) { 2990 if (!has_last_Java_frame()) return; 2991 ResourceMark rm; 2992 HandleMark hm; 2993 2994 RegisterMap reg_map(this); 2995 vframe* start_vf = last_java_vframe(®_map); 2996 int count = 0; 2997 for (vframe* f = start_vf; f; f = f->sender()) { 2998 if (f->is_java_frame()) { 2999 javaVFrame* jvf = javaVFrame::cast(f); 3000 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3001 3002 // Print out lock information 3003 if (JavaMonitorsInStackTrace) { 3004 jvf->print_lock_info_on(st, count); 3005 } 3006 } else { 3007 // Ignore non-Java frames 3008 } 3009 3010 // Bail-out case for too deep stacks 3011 count++; 3012 if (MaxJavaStackTraceDepth == count) return; 3013 } 3014 } 3015 3016 3017 // JVMTI PopFrame support 3018 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3019 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3020 if (in_bytes(size_in_bytes) != 0) { 3021 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3022 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3023 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3024 } 3025 } 3026 3027 void* JavaThread::popframe_preserved_args() { 3028 return _popframe_preserved_args; 3029 } 3030 3031 ByteSize JavaThread::popframe_preserved_args_size() { 3032 return in_ByteSize(_popframe_preserved_args_size); 3033 } 3034 3035 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3036 int sz = in_bytes(popframe_preserved_args_size()); 3037 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3038 return in_WordSize(sz / wordSize); 3039 } 3040 3041 void JavaThread::popframe_free_preserved_args() { 3042 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3043 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread); 3044 _popframe_preserved_args = NULL; 3045 _popframe_preserved_args_size = 0; 3046 } 3047 3048 #ifndef PRODUCT 3049 3050 void JavaThread::trace_frames() { 3051 tty->print_cr("[Describe stack]"); 3052 int frame_no = 1; 3053 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3054 tty->print(" %d. ", frame_no++); 3055 fst.current()->print_value_on(tty, this); 3056 tty->cr(); 3057 } 3058 } 3059 3060 class PrintAndVerifyOopClosure: public OopClosure { 3061 protected: 3062 template <class T> inline void do_oop_work(T* p) { 3063 oop obj = oopDesc::load_decode_heap_oop(p); 3064 if (obj == NULL) return; 3065 tty->print(INTPTR_FORMAT ": ", p); 3066 if (obj->is_oop_or_null()) { 3067 if (obj->is_objArray()) { 3068 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj); 3069 } else { 3070 obj->print(); 3071 } 3072 } else { 3073 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj); 3074 } 3075 tty->cr(); 3076 } 3077 public: 3078 virtual void do_oop(oop* p) { do_oop_work(p); } 3079 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3080 }; 3081 3082 3083 static void oops_print(frame* f, const RegisterMap *map) { 3084 PrintAndVerifyOopClosure print; 3085 f->print_value(); 3086 f->oops_do(&print, NULL, NULL, (RegisterMap*)map); 3087 } 3088 3089 // Print our all the locations that contain oops and whether they are 3090 // valid or not. This useful when trying to find the oldest frame 3091 // where an oop has gone bad since the frame walk is from youngest to 3092 // oldest. 3093 void JavaThread::trace_oops() { 3094 tty->print_cr("[Trace oops]"); 3095 frames_do(oops_print); 3096 } 3097 3098 3099 #ifdef ASSERT 3100 // Print or validate the layout of stack frames 3101 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3102 ResourceMark rm; 3103 PRESERVE_EXCEPTION_MARK; 3104 FrameValues values; 3105 int frame_no = 0; 3106 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3107 fst.current()->describe(values, ++frame_no); 3108 if (depth == frame_no) break; 3109 } 3110 if (validate_only) { 3111 values.validate(); 3112 } else { 3113 tty->print_cr("[Describe stack layout]"); 3114 values.print(this); 3115 } 3116 } 3117 #endif 3118 3119 void JavaThread::trace_stack_from(vframe* start_vf) { 3120 ResourceMark rm; 3121 int vframe_no = 1; 3122 for (vframe* f = start_vf; f; f = f->sender()) { 3123 if (f->is_java_frame()) { 3124 javaVFrame::cast(f)->print_activation(vframe_no++); 3125 } else { 3126 f->print(); 3127 } 3128 if (vframe_no > StackPrintLimit) { 3129 tty->print_cr("...<more frames>..."); 3130 return; 3131 } 3132 } 3133 } 3134 3135 3136 void JavaThread::trace_stack() { 3137 if (!has_last_Java_frame()) return; 3138 ResourceMark rm; 3139 HandleMark hm; 3140 RegisterMap reg_map(this); 3141 trace_stack_from(last_java_vframe(®_map)); 3142 } 3143 3144 3145 #endif // PRODUCT 3146 3147 3148 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3149 assert(reg_map != NULL, "a map must be given"); 3150 frame f = last_frame(); 3151 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3152 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3153 } 3154 return NULL; 3155 } 3156 3157 3158 Klass* JavaThread::security_get_caller_class(int depth) { 3159 vframeStream vfst(this); 3160 vfst.security_get_caller_frame(depth); 3161 if (!vfst.at_end()) { 3162 return vfst.method()->method_holder(); 3163 } 3164 return NULL; 3165 } 3166 3167 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3168 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3169 CompileBroker::compiler_thread_loop(); 3170 } 3171 3172 // Create a CompilerThread 3173 CompilerThread::CompilerThread(CompileQueue* queue, 3174 CompilerCounters* counters) 3175 : JavaThread(&compiler_thread_entry) { 3176 _env = NULL; 3177 _log = NULL; 3178 _task = NULL; 3179 _queue = queue; 3180 _counters = counters; 3181 _buffer_blob = NULL; 3182 _scanned_nmethod = NULL; 3183 _compiler = NULL; 3184 3185 #ifndef PRODUCT 3186 _ideal_graph_printer = NULL; 3187 #endif 3188 } 3189 3190 void CompilerThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 3191 JavaThread::oops_do(f, cld_f, cf); 3192 if (_scanned_nmethod != NULL && cf != NULL) { 3193 // Safepoints can occur when the sweeper is scanning an nmethod so 3194 // process it here to make sure it isn't unloaded in the middle of 3195 // a scan. 3196 cf->do_code_blob(_scanned_nmethod); 3197 } 3198 } 3199 3200 3201 // ======= Threads ======== 3202 3203 // The Threads class links together all active threads, and provides 3204 // operations over all threads. It is protected by its own Mutex 3205 // lock, which is also used in other contexts to protect thread 3206 // operations from having the thread being operated on from exiting 3207 // and going away unexpectedly (e.g., safepoint synchronization) 3208 3209 JavaThread* Threads::_thread_list = NULL; 3210 int Threads::_number_of_threads = 0; 3211 int Threads::_number_of_non_daemon_threads = 0; 3212 int Threads::_return_code = 0; 3213 size_t JavaThread::_stack_size_at_create = 0; 3214 #ifdef ASSERT 3215 bool Threads::_vm_complete = false; 3216 #endif 3217 3218 // All JavaThreads 3219 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3220 3221 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3222 void Threads::threads_do(ThreadClosure* tc) { 3223 assert_locked_or_safepoint(Threads_lock); 3224 // ALL_JAVA_THREADS iterates through all JavaThreads 3225 ALL_JAVA_THREADS(p) { 3226 tc->do_thread(p); 3227 } 3228 // Someday we could have a table or list of all non-JavaThreads. 3229 // For now, just manually iterate through them. 3230 tc->do_thread(VMThread::vm_thread()); 3231 Universe::heap()->gc_threads_do(tc); 3232 WatcherThread *wt = WatcherThread::watcher_thread(); 3233 // Strictly speaking, the following NULL check isn't sufficient to make sure 3234 // the data for WatcherThread is still valid upon being examined. However, 3235 // considering that WatchThread terminates when the VM is on the way to 3236 // exit at safepoint, the chance of the above is extremely small. The right 3237 // way to prevent termination of WatcherThread would be to acquire 3238 // Terminator_lock, but we can't do that without violating the lock rank 3239 // checking in some cases. 3240 if (wt != NULL) { 3241 tc->do_thread(wt); 3242 } 3243 3244 // If CompilerThreads ever become non-JavaThreads, add them here 3245 } 3246 3247 3248 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3249 TraceTime timer("Initialize java.lang classes", TraceStartupTime); 3250 3251 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3252 create_vm_init_libraries(); 3253 } 3254 3255 initialize_class(vmSymbols::java_lang_String(), CHECK); 3256 3257 // Initialize java_lang.System (needed before creating the thread) 3258 initialize_class(vmSymbols::java_lang_System(), CHECK); 3259 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3260 Handle thread_group = create_initial_thread_group(CHECK); 3261 Universe::set_main_thread_group(thread_group()); 3262 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3263 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3264 main_thread->set_threadObj(thread_object); 3265 // Set thread status to running since main thread has 3266 // been started and running. 3267 java_lang_Thread::set_thread_status(thread_object, 3268 java_lang_Thread::RUNNABLE); 3269 3270 // The VM creates & returns objects of this class. Make sure it's initialized. 3271 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3272 3273 // The VM preresolves methods to these classes. Make sure that they get initialized 3274 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3275 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3276 call_initializeSystemClass(CHECK); 3277 3278 // get the Java runtime name after java.lang.System is initialized 3279 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3280 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3281 3282 // an instance of OutOfMemory exception has been allocated earlier 3283 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3284 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3285 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3286 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3287 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3288 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3289 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3290 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3291 } 3292 3293 void Threads::initialize_jsr292_core_classes(TRAPS) { 3294 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3295 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3296 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3297 } 3298 3299 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3300 extern void JDK_Version_init(); 3301 3302 // Check version 3303 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3304 3305 // Initialize the output stream module 3306 ostream_init(); 3307 3308 // Process java launcher properties. 3309 Arguments::process_sun_java_launcher_properties(args); 3310 3311 // Initialize the os module before using TLS 3312 os::init(); 3313 3314 // Initialize system properties. 3315 Arguments::init_system_properties(); 3316 3317 // So that JDK version can be used as a discriminator when parsing arguments 3318 JDK_Version_init(); 3319 3320 // Update/Initialize System properties after JDK version number is known 3321 Arguments::init_version_specific_system_properties(); 3322 3323 // Parse arguments 3324 jint parse_result = Arguments::parse(args); 3325 if (parse_result != JNI_OK) return parse_result; 3326 3327 os::init_before_ergo(); 3328 3329 jint ergo_result = Arguments::apply_ergo(); 3330 if (ergo_result != JNI_OK) return ergo_result; 3331 3332 if (PauseAtStartup) { 3333 os::pause(); 3334 } 3335 3336 HOTSPOT_VM_INIT_BEGIN(); 3337 3338 // Record VM creation timing statistics 3339 TraceVmCreationTime create_vm_timer; 3340 create_vm_timer.start(); 3341 3342 // Timing (must come after argument parsing) 3343 TraceTime timer("Create VM", TraceStartupTime); 3344 3345 // Initialize the os module after parsing the args 3346 jint os_init_2_result = os::init_2(); 3347 if (os_init_2_result != JNI_OK) return os_init_2_result; 3348 3349 jint adjust_after_os_result = Arguments::adjust_after_os(); 3350 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3351 3352 // initialize TLS 3353 ThreadLocalStorage::init(); 3354 3355 // Initialize output stream logging 3356 ostream_init_log(); 3357 3358 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3359 // Must be before create_vm_init_agents() 3360 if (Arguments::init_libraries_at_startup()) { 3361 convert_vm_init_libraries_to_agents(); 3362 } 3363 3364 // Launch -agentlib/-agentpath and converted -Xrun agents 3365 if (Arguments::init_agents_at_startup()) { 3366 create_vm_init_agents(); 3367 } 3368 3369 // Initialize Threads state 3370 _thread_list = NULL; 3371 _number_of_threads = 0; 3372 _number_of_non_daemon_threads = 0; 3373 3374 // Initialize global data structures and create system classes in heap 3375 vm_init_globals(); 3376 3377 // Attach the main thread to this os thread 3378 JavaThread* main_thread = new JavaThread(); 3379 main_thread->set_thread_state(_thread_in_vm); 3380 // must do this before set_active_handles and initialize_thread_local_storage 3381 // Note: on solaris initialize_thread_local_storage() will (indirectly) 3382 // change the stack size recorded here to one based on the java thread 3383 // stacksize. This adjusted size is what is used to figure the placement 3384 // of the guard pages. 3385 main_thread->record_stack_base_and_size(); 3386 main_thread->initialize_thread_local_storage(); 3387 3388 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3389 3390 if (!main_thread->set_as_starting_thread()) { 3391 vm_shutdown_during_initialization( 3392 "Failed necessary internal allocation. Out of swap space"); 3393 delete main_thread; 3394 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3395 return JNI_ENOMEM; 3396 } 3397 3398 // Enable guard page *after* os::create_main_thread(), otherwise it would 3399 // crash Linux VM, see notes in os_linux.cpp. 3400 main_thread->create_stack_guard_pages(); 3401 3402 // Initialize Java-Level synchronization subsystem 3403 ObjectMonitor::Initialize(); 3404 3405 // Initialize global modules 3406 jint status = init_globals(); 3407 if (status != JNI_OK) { 3408 delete main_thread; 3409 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3410 return status; 3411 } 3412 3413 // Should be done after the heap is fully created 3414 main_thread->cache_global_variables(); 3415 3416 HandleMark hm; 3417 3418 { MutexLocker mu(Threads_lock); 3419 Threads::add(main_thread); 3420 } 3421 3422 // Any JVMTI raw monitors entered in onload will transition into 3423 // real raw monitor. VM is setup enough here for raw monitor enter. 3424 JvmtiExport::transition_pending_onload_raw_monitors(); 3425 3426 // Create the VMThread 3427 { TraceTime timer("Start VMThread", TraceStartupTime); 3428 VMThread::create(); 3429 Thread* vmthread = VMThread::vm_thread(); 3430 3431 if (!os::create_thread(vmthread, os::vm_thread)) { 3432 vm_exit_during_initialization("Cannot create VM thread. " 3433 "Out of system resources."); 3434 } 3435 3436 // Wait for the VM thread to become ready, and VMThread::run to initialize 3437 // Monitors can have spurious returns, must always check another state flag 3438 { 3439 MutexLocker ml(Notify_lock); 3440 os::start_thread(vmthread); 3441 while (vmthread->active_handles() == NULL) { 3442 Notify_lock->wait(); 3443 } 3444 } 3445 } 3446 3447 assert(Universe::is_fully_initialized(), "not initialized"); 3448 if (VerifyDuringStartup) { 3449 // Make sure we're starting with a clean slate. 3450 VM_Verify verify_op; 3451 VMThread::execute(&verify_op); 3452 } 3453 3454 Thread* THREAD = Thread::current(); 3455 3456 // At this point, the Universe is initialized, but we have not executed 3457 // any byte code. Now is a good time (the only time) to dump out the 3458 // internal state of the JVM for sharing. 3459 if (DumpSharedSpaces) { 3460 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3461 ShouldNotReachHere(); 3462 } 3463 3464 // Always call even when there are not JVMTI environments yet, since environments 3465 // may be attached late and JVMTI must track phases of VM execution 3466 JvmtiExport::enter_start_phase(); 3467 3468 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3469 JvmtiExport::post_vm_start(); 3470 3471 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3472 3473 // We need this for ClassDataSharing - the initial vm.info property is set 3474 // with the default value of CDS "sharing" which may be reset through 3475 // command line options. 3476 reset_vm_info_property(CHECK_JNI_ERR); 3477 3478 quicken_jni_functions(); 3479 3480 // Must be run after init_ft which initializes ft_enabled 3481 if (TRACE_INITIALIZE() != JNI_OK) { 3482 vm_exit_during_initialization("Failed to initialize tracing backend"); 3483 } 3484 3485 // Set flag that basic initialization has completed. Used by exceptions and various 3486 // debug stuff, that does not work until all basic classes have been initialized. 3487 set_init_completed(); 3488 3489 Metaspace::post_initialize(); 3490 3491 HOTSPOT_VM_INIT_END(); 3492 3493 // record VM initialization completion time 3494 #if INCLUDE_MANAGEMENT 3495 Management::record_vm_init_completed(); 3496 #endif // INCLUDE_MANAGEMENT 3497 3498 // Compute system loader. Note that this has to occur after set_init_completed, since 3499 // valid exceptions may be thrown in the process. 3500 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3501 // set_init_completed has just been called, causing exceptions not to be shortcut 3502 // anymore. We call vm_exit_during_initialization directly instead. 3503 SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR); 3504 3505 #if INCLUDE_ALL_GCS 3506 // Support for ConcurrentMarkSweep. This should be cleaned up 3507 // and better encapsulated. The ugly nested if test would go away 3508 // once things are properly refactored. XXX YSR 3509 if (UseConcMarkSweepGC || UseG1GC) { 3510 if (UseConcMarkSweepGC) { 3511 ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3512 } else { 3513 ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3514 } 3515 } 3516 #endif // INCLUDE_ALL_GCS 3517 3518 // Always call even when there are not JVMTI environments yet, since environments 3519 // may be attached late and JVMTI must track phases of VM execution 3520 JvmtiExport::enter_live_phase(); 3521 3522 // Signal Dispatcher needs to be started before VMInit event is posted 3523 os::signal_init(); 3524 3525 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3526 if (!DisableAttachMechanism) { 3527 AttachListener::vm_start(); 3528 if (StartAttachListener || AttachListener::init_at_startup()) { 3529 AttachListener::init(); 3530 } 3531 } 3532 3533 // Launch -Xrun agents 3534 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3535 // back-end can launch with -Xdebug -Xrunjdwp. 3536 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3537 create_vm_init_libraries(); 3538 } 3539 3540 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3541 JvmtiExport::post_vm_initialized(); 3542 3543 if (TRACE_START() != JNI_OK) { 3544 vm_exit_during_initialization("Failed to start tracing backend."); 3545 } 3546 3547 if (CleanChunkPoolAsync) { 3548 Chunk::start_chunk_pool_cleaner_task(); 3549 } 3550 3551 // initialize compiler(s) 3552 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) 3553 CompileBroker::compilation_init(); 3554 #endif 3555 3556 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3557 // It is done after compilers are initialized, because otherwise compilations of 3558 // signature polymorphic MH intrinsics can be missed 3559 // (see SystemDictionary::find_method_handle_intrinsic). 3560 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3561 3562 #if INCLUDE_MANAGEMENT 3563 Management::initialize(THREAD); 3564 3565 if (HAS_PENDING_EXCEPTION) { 3566 // management agent fails to start possibly due to 3567 // configuration problem and is responsible for printing 3568 // stack trace if appropriate. Simply exit VM. 3569 vm_exit(1); 3570 } 3571 #endif // INCLUDE_MANAGEMENT 3572 3573 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3574 if (MemProfiling) MemProfiler::engage(); 3575 StatSampler::engage(); 3576 if (CheckJNICalls) JniPeriodicChecker::engage(); 3577 3578 BiasedLocking::init(); 3579 3580 #if INCLUDE_RTM_OPT 3581 RTMLockingCounters::init(); 3582 #endif 3583 3584 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3585 call_postVMInitHook(THREAD); 3586 // The Java side of PostVMInitHook.run must deal with all 3587 // exceptions and provide means of diagnosis. 3588 if (HAS_PENDING_EXCEPTION) { 3589 CLEAR_PENDING_EXCEPTION; 3590 } 3591 } 3592 3593 { 3594 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 3595 // Make sure the watcher thread can be started by WatcherThread::start() 3596 // or by dynamic enrollment. 3597 WatcherThread::make_startable(); 3598 // Start up the WatcherThread if there are any periodic tasks 3599 // NOTE: All PeriodicTasks should be registered by now. If they 3600 // aren't, late joiners might appear to start slowly (we might 3601 // take a while to process their first tick). 3602 if (PeriodicTask::num_tasks() > 0) { 3603 WatcherThread::start(); 3604 } 3605 } 3606 3607 // Give os specific code one last chance to start 3608 os::init_3(); 3609 3610 create_vm_timer.end(); 3611 #ifdef ASSERT 3612 _vm_complete = true; 3613 #endif 3614 return JNI_OK; 3615 } 3616 3617 // type for the Agent_OnLoad and JVM_OnLoad entry points 3618 extern "C" { 3619 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3620 } 3621 // Find a command line agent library and return its entry point for 3622 // -agentlib: -agentpath: -Xrun 3623 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3624 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3625 const char *on_load_symbols[], 3626 size_t num_symbol_entries) { 3627 OnLoadEntry_t on_load_entry = NULL; 3628 void *library = NULL; 3629 3630 if (!agent->valid()) { 3631 char buffer[JVM_MAXPATHLEN]; 3632 char ebuf[1024]; 3633 const char *name = agent->name(); 3634 const char *msg = "Could not find agent library "; 3635 3636 // First check to see if agent is statically linked into executable 3637 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3638 library = agent->os_lib(); 3639 } else if (agent->is_absolute_path()) { 3640 library = os::dll_load(name, ebuf, sizeof ebuf); 3641 if (library == NULL) { 3642 const char *sub_msg = " in absolute path, with error: "; 3643 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3644 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3645 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3646 // If we can't find the agent, exit. 3647 vm_exit_during_initialization(buf, NULL); 3648 FREE_C_HEAP_ARRAY(char, buf, mtThread); 3649 } 3650 } else { 3651 // Try to load the agent from the standard dll directory 3652 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3653 name)) { 3654 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3655 } 3656 if (library == NULL) { // Try the local directory 3657 char ns[1] = {0}; 3658 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3659 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3660 } 3661 if (library == NULL) { 3662 const char *sub_msg = " on the library path, with error: "; 3663 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3664 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3665 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3666 // If we can't find the agent, exit. 3667 vm_exit_during_initialization(buf, NULL); 3668 FREE_C_HEAP_ARRAY(char, buf, mtThread); 3669 } 3670 } 3671 } 3672 agent->set_os_lib(library); 3673 agent->set_valid(); 3674 } 3675 3676 // Find the OnLoad function. 3677 on_load_entry = 3678 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3679 false, 3680 on_load_symbols, 3681 num_symbol_entries)); 3682 return on_load_entry; 3683 } 3684 3685 // Find the JVM_OnLoad entry point 3686 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3687 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3688 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3689 } 3690 3691 // Find the Agent_OnLoad entry point 3692 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3693 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3694 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3695 } 3696 3697 // For backwards compatibility with -Xrun 3698 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3699 // treated like -agentpath: 3700 // Must be called before agent libraries are created 3701 void Threads::convert_vm_init_libraries_to_agents() { 3702 AgentLibrary* agent; 3703 AgentLibrary* next; 3704 3705 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3706 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3707 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3708 3709 // If there is an JVM_OnLoad function it will get called later, 3710 // otherwise see if there is an Agent_OnLoad 3711 if (on_load_entry == NULL) { 3712 on_load_entry = lookup_agent_on_load(agent); 3713 if (on_load_entry != NULL) { 3714 // switch it to the agent list -- so that Agent_OnLoad will be called, 3715 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3716 Arguments::convert_library_to_agent(agent); 3717 } else { 3718 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3719 } 3720 } 3721 } 3722 } 3723 3724 // Create agents for -agentlib: -agentpath: and converted -Xrun 3725 // Invokes Agent_OnLoad 3726 // Called very early -- before JavaThreads exist 3727 void Threads::create_vm_init_agents() { 3728 extern struct JavaVM_ main_vm; 3729 AgentLibrary* agent; 3730 3731 JvmtiExport::enter_onload_phase(); 3732 3733 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3734 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3735 3736 if (on_load_entry != NULL) { 3737 // Invoke the Agent_OnLoad function 3738 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3739 if (err != JNI_OK) { 3740 vm_exit_during_initialization("agent library failed to init", agent->name()); 3741 } 3742 } else { 3743 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3744 } 3745 } 3746 JvmtiExport::enter_primordial_phase(); 3747 } 3748 3749 extern "C" { 3750 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3751 } 3752 3753 void Threads::shutdown_vm_agents() { 3754 // Send any Agent_OnUnload notifications 3755 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3756 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3757 extern struct JavaVM_ main_vm; 3758 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3759 3760 // Find the Agent_OnUnload function. 3761 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3762 os::find_agent_function(agent, 3763 false, 3764 on_unload_symbols, 3765 num_symbol_entries)); 3766 3767 // Invoke the Agent_OnUnload function 3768 if (unload_entry != NULL) { 3769 JavaThread* thread = JavaThread::current(); 3770 ThreadToNativeFromVM ttn(thread); 3771 HandleMark hm(thread); 3772 (*unload_entry)(&main_vm); 3773 } 3774 } 3775 } 3776 3777 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3778 // Invokes JVM_OnLoad 3779 void Threads::create_vm_init_libraries() { 3780 extern struct JavaVM_ main_vm; 3781 AgentLibrary* agent; 3782 3783 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3784 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3785 3786 if (on_load_entry != NULL) { 3787 // Invoke the JVM_OnLoad function 3788 JavaThread* thread = JavaThread::current(); 3789 ThreadToNativeFromVM ttn(thread); 3790 HandleMark hm(thread); 3791 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3792 if (err != JNI_OK) { 3793 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 3794 } 3795 } else { 3796 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 3797 } 3798 } 3799 } 3800 3801 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 3802 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 3803 3804 JavaThread* java_thread = NULL; 3805 // Sequential search for now. Need to do better optimization later. 3806 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 3807 oop tobj = thread->threadObj(); 3808 if (!thread->is_exiting() && 3809 tobj != NULL && 3810 java_tid == java_lang_Thread::thread_id(tobj)) { 3811 java_thread = thread; 3812 break; 3813 } 3814 } 3815 return java_thread; 3816 } 3817 3818 3819 // Last thread running calls java.lang.Shutdown.shutdown() 3820 void JavaThread::invoke_shutdown_hooks() { 3821 HandleMark hm(this); 3822 3823 // We could get here with a pending exception, if so clear it now. 3824 if (this->has_pending_exception()) { 3825 this->clear_pending_exception(); 3826 } 3827 3828 EXCEPTION_MARK; 3829 Klass* k = 3830 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 3831 THREAD); 3832 if (k != NULL) { 3833 // SystemDictionary::resolve_or_null will return null if there was 3834 // an exception. If we cannot load the Shutdown class, just don't 3835 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 3836 // and finalizers (if runFinalizersOnExit is set) won't be run. 3837 // Note that if a shutdown hook was registered or runFinalizersOnExit 3838 // was called, the Shutdown class would have already been loaded 3839 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 3840 instanceKlassHandle shutdown_klass (THREAD, k); 3841 JavaValue result(T_VOID); 3842 JavaCalls::call_static(&result, 3843 shutdown_klass, 3844 vmSymbols::shutdown_method_name(), 3845 vmSymbols::void_method_signature(), 3846 THREAD); 3847 } 3848 CLEAR_PENDING_EXCEPTION; 3849 } 3850 3851 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 3852 // the program falls off the end of main(). Another VM exit path is through 3853 // vm_exit() when the program calls System.exit() to return a value or when 3854 // there is a serious error in VM. The two shutdown paths are not exactly 3855 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 3856 // and VM_Exit op at VM level. 3857 // 3858 // Shutdown sequence: 3859 // + Shutdown native memory tracking if it is on 3860 // + Wait until we are the last non-daemon thread to execute 3861 // <-- every thing is still working at this moment --> 3862 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 3863 // shutdown hooks, run finalizers if finalization-on-exit 3864 // + Call before_exit(), prepare for VM exit 3865 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 3866 // currently the only user of this mechanism is File.deleteOnExit()) 3867 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 3868 // post thread end and vm death events to JVMTI, 3869 // stop signal thread 3870 // + Call JavaThread::exit(), it will: 3871 // > release JNI handle blocks, remove stack guard pages 3872 // > remove this thread from Threads list 3873 // <-- no more Java code from this thread after this point --> 3874 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 3875 // the compiler threads at safepoint 3876 // <-- do not use anything that could get blocked by Safepoint --> 3877 // + Disable tracing at JNI/JVM barriers 3878 // + Set _vm_exited flag for threads that are still running native code 3879 // + Delete this thread 3880 // + Call exit_globals() 3881 // > deletes tty 3882 // > deletes PerfMemory resources 3883 // + Return to caller 3884 3885 bool Threads::destroy_vm() { 3886 JavaThread* thread = JavaThread::current(); 3887 3888 #ifdef ASSERT 3889 _vm_complete = false; 3890 #endif 3891 // Wait until we are the last non-daemon thread to execute 3892 { MutexLocker nu(Threads_lock); 3893 while (Threads::number_of_non_daemon_threads() > 1) 3894 // This wait should make safepoint checks, wait without a timeout, 3895 // and wait as a suspend-equivalent condition. 3896 // 3897 // Note: If the FlatProfiler is running and this thread is waiting 3898 // for another non-daemon thread to finish, then the FlatProfiler 3899 // is waiting for the external suspend request on this thread to 3900 // complete. wait_for_ext_suspend_completion() will eventually 3901 // timeout, but that takes time. Making this wait a suspend- 3902 // equivalent condition solves that timeout problem. 3903 // 3904 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 3905 Mutex::_as_suspend_equivalent_flag); 3906 } 3907 3908 // Hang forever on exit if we are reporting an error. 3909 if (ShowMessageBoxOnError && is_error_reported()) { 3910 os::infinite_sleep(); 3911 } 3912 os::wait_for_keypress_at_exit(); 3913 3914 // run Java level shutdown hooks 3915 thread->invoke_shutdown_hooks(); 3916 3917 before_exit(thread); 3918 3919 thread->exit(true); 3920 3921 // Stop VM thread. 3922 { 3923 // 4945125 The vm thread comes to a safepoint during exit. 3924 // GC vm_operations can get caught at the safepoint, and the 3925 // heap is unparseable if they are caught. Grab the Heap_lock 3926 // to prevent this. The GC vm_operations will not be able to 3927 // queue until after the vm thread is dead. After this point, 3928 // we'll never emerge out of the safepoint before the VM exits. 3929 3930 MutexLocker ml(Heap_lock); 3931 3932 VMThread::wait_for_vm_thread_exit(); 3933 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 3934 VMThread::destroy(); 3935 } 3936 3937 // clean up ideal graph printers 3938 #if defined(COMPILER2) && !defined(PRODUCT) 3939 IdealGraphPrinter::clean_up(); 3940 #endif 3941 3942 // Now, all Java threads are gone except daemon threads. Daemon threads 3943 // running Java code or in VM are stopped by the Safepoint. However, 3944 // daemon threads executing native code are still running. But they 3945 // will be stopped at native=>Java/VM barriers. Note that we can't 3946 // simply kill or suspend them, as it is inherently deadlock-prone. 3947 3948 #ifndef PRODUCT 3949 // disable function tracing at JNI/JVM barriers 3950 TraceJNICalls = false; 3951 TraceJVMCalls = false; 3952 TraceRuntimeCalls = false; 3953 #endif 3954 3955 VM_Exit::set_vm_exited(); 3956 3957 notify_vm_shutdown(); 3958 3959 delete thread; 3960 3961 // exit_globals() will delete tty 3962 exit_globals(); 3963 3964 return true; 3965 } 3966 3967 3968 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 3969 if (version == JNI_VERSION_1_1) return JNI_TRUE; 3970 return is_supported_jni_version(version); 3971 } 3972 3973 3974 jboolean Threads::is_supported_jni_version(jint version) { 3975 if (version == JNI_VERSION_1_2) return JNI_TRUE; 3976 if (version == JNI_VERSION_1_4) return JNI_TRUE; 3977 if (version == JNI_VERSION_1_6) return JNI_TRUE; 3978 if (version == JNI_VERSION_1_8) return JNI_TRUE; 3979 return JNI_FALSE; 3980 } 3981 3982 3983 void Threads::add(JavaThread* p, bool force_daemon) { 3984 // The threads lock must be owned at this point 3985 assert_locked_or_safepoint(Threads_lock); 3986 3987 // See the comment for this method in thread.hpp for its purpose and 3988 // why it is called here. 3989 p->initialize_queues(); 3990 p->set_next(_thread_list); 3991 _thread_list = p; 3992 _number_of_threads++; 3993 oop threadObj = p->threadObj(); 3994 bool daemon = true; 3995 // Bootstrapping problem: threadObj can be null for initial 3996 // JavaThread (or for threads attached via JNI) 3997 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 3998 _number_of_non_daemon_threads++; 3999 daemon = false; 4000 } 4001 4002 ThreadService::add_thread(p, daemon); 4003 4004 // Possible GC point. 4005 Events::log(p, "Thread added: " INTPTR_FORMAT, p); 4006 } 4007 4008 void Threads::remove(JavaThread* p) { 4009 // Extra scope needed for Thread_lock, so we can check 4010 // that we do not remove thread without safepoint code notice 4011 { MutexLocker ml(Threads_lock); 4012 4013 assert(includes(p), "p must be present"); 4014 4015 JavaThread* current = _thread_list; 4016 JavaThread* prev = NULL; 4017 4018 while (current != p) { 4019 prev = current; 4020 current = current->next(); 4021 } 4022 4023 if (prev) { 4024 prev->set_next(current->next()); 4025 } else { 4026 _thread_list = p->next(); 4027 } 4028 _number_of_threads--; 4029 oop threadObj = p->threadObj(); 4030 bool daemon = true; 4031 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4032 _number_of_non_daemon_threads--; 4033 daemon = false; 4034 4035 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4036 // on destroy_vm will wake up. 4037 if (number_of_non_daemon_threads() == 1) { 4038 Threads_lock->notify_all(); 4039 } 4040 } 4041 ThreadService::remove_thread(p, daemon); 4042 4043 // Make sure that safepoint code disregard this thread. This is needed since 4044 // the thread might mess around with locks after this point. This can cause it 4045 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4046 // of this thread since it is removed from the queue. 4047 p->set_terminated_value(); 4048 } // unlock Threads_lock 4049 4050 // Since Events::log uses a lock, we grab it outside the Threads_lock 4051 Events::log(p, "Thread exited: " INTPTR_FORMAT, p); 4052 } 4053 4054 // Threads_lock must be held when this is called (or must be called during a safepoint) 4055 bool Threads::includes(JavaThread* p) { 4056 assert(Threads_lock->is_locked(), "sanity check"); 4057 ALL_JAVA_THREADS(q) { 4058 if (q == p) { 4059 return true; 4060 } 4061 } 4062 return false; 4063 } 4064 4065 // Operations on the Threads list for GC. These are not explicitly locked, 4066 // but the garbage collector must provide a safe context for them to run. 4067 // In particular, these things should never be called when the Threads_lock 4068 // is held by some other thread. (Note: the Safepoint abstraction also 4069 // uses the Threads_lock to guarantee this property. It also makes sure that 4070 // all threads gets blocked when exiting or starting). 4071 4072 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4073 ALL_JAVA_THREADS(p) { 4074 p->oops_do(f, cld_f, cf); 4075 } 4076 VMThread::vm_thread()->oops_do(f, cld_f, cf); 4077 } 4078 4079 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4080 // Introduce a mechanism allowing parallel threads to claim threads as 4081 // root groups. Overhead should be small enough to use all the time, 4082 // even in sequential code. 4083 SharedHeap* sh = SharedHeap::heap(); 4084 // Cannot yet substitute active_workers for n_par_threads 4085 // because of G1CollectedHeap::verify() use of 4086 // SharedHeap::process_roots(). n_par_threads == 0 will 4087 // turn off parallelism in process_roots while active_workers 4088 // is being used for parallelism elsewhere. 4089 bool is_par = sh->n_par_threads() > 0; 4090 assert(!is_par || 4091 (SharedHeap::heap()->n_par_threads() == 4092 SharedHeap::heap()->workers()->active_workers()), "Mismatch"); 4093 int cp = SharedHeap::heap()->strong_roots_parity(); 4094 ALL_JAVA_THREADS(p) { 4095 if (p->claim_oops_do(is_par, cp)) { 4096 p->oops_do(f, cld_f, cf); 4097 } 4098 } 4099 VMThread* vmt = VMThread::vm_thread(); 4100 if (vmt->claim_oops_do(is_par, cp)) { 4101 vmt->oops_do(f, cld_f, cf); 4102 } 4103 } 4104 4105 #if INCLUDE_ALL_GCS 4106 // Used by ParallelScavenge 4107 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4108 ALL_JAVA_THREADS(p) { 4109 q->enqueue(new ThreadRootsTask(p)); 4110 } 4111 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4112 } 4113 4114 // Used by Parallel Old 4115 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4116 ALL_JAVA_THREADS(p) { 4117 q->enqueue(new ThreadRootsMarkingTask(p)); 4118 } 4119 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4120 } 4121 #endif // INCLUDE_ALL_GCS 4122 4123 void Threads::nmethods_do(CodeBlobClosure* cf) { 4124 ALL_JAVA_THREADS(p) { 4125 p->nmethods_do(cf); 4126 } 4127 VMThread::vm_thread()->nmethods_do(cf); 4128 } 4129 4130 void Threads::metadata_do(void f(Metadata*)) { 4131 ALL_JAVA_THREADS(p) { 4132 p->metadata_do(f); 4133 } 4134 } 4135 4136 void Threads::deoptimized_wrt_marked_nmethods() { 4137 ALL_JAVA_THREADS(p) { 4138 p->deoptimized_wrt_marked_nmethods(); 4139 } 4140 } 4141 4142 4143 // Get count Java threads that are waiting to enter the specified monitor. 4144 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4145 address monitor, 4146 bool doLock) { 4147 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4148 "must grab Threads_lock or be at safepoint"); 4149 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4150 4151 int i = 0; 4152 { 4153 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4154 ALL_JAVA_THREADS(p) { 4155 if (p->is_Compiler_thread()) continue; 4156 4157 address pending = (address)p->current_pending_monitor(); 4158 if (pending == monitor) { // found a match 4159 if (i < count) result->append(p); // save the first count matches 4160 i++; 4161 } 4162 } 4163 } 4164 return result; 4165 } 4166 4167 4168 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4169 bool doLock) { 4170 assert(doLock || 4171 Threads_lock->owned_by_self() || 4172 SafepointSynchronize::is_at_safepoint(), 4173 "must grab Threads_lock or be at safepoint"); 4174 4175 // NULL owner means not locked so we can skip the search 4176 if (owner == NULL) return NULL; 4177 4178 { 4179 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4180 ALL_JAVA_THREADS(p) { 4181 // first, see if owner is the address of a Java thread 4182 if (owner == (address)p) return p; 4183 } 4184 } 4185 // Cannot assert on lack of success here since this function may be 4186 // used by code that is trying to report useful problem information 4187 // like deadlock detection. 4188 if (UseHeavyMonitors) return NULL; 4189 4190 // If we didn't find a matching Java thread and we didn't force use of 4191 // heavyweight monitors, then the owner is the stack address of the 4192 // Lock Word in the owning Java thread's stack. 4193 // 4194 JavaThread* the_owner = NULL; 4195 { 4196 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4197 ALL_JAVA_THREADS(q) { 4198 if (q->is_lock_owned(owner)) { 4199 the_owner = q; 4200 break; 4201 } 4202 } 4203 } 4204 // cannot assert on lack of success here; see above comment 4205 return the_owner; 4206 } 4207 4208 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4209 void Threads::print_on(outputStream* st, bool print_stacks, 4210 bool internal_format, bool print_concurrent_locks) { 4211 char buf[32]; 4212 st->print_cr("%s", os::local_time_string(buf, sizeof(buf))); 4213 4214 st->print_cr("Full thread dump %s (%s %s):", 4215 Abstract_VM_Version::vm_name(), 4216 Abstract_VM_Version::vm_release(), 4217 Abstract_VM_Version::vm_info_string()); 4218 st->cr(); 4219 4220 #if INCLUDE_ALL_GCS 4221 // Dump concurrent locks 4222 ConcurrentLocksDump concurrent_locks; 4223 if (print_concurrent_locks) { 4224 concurrent_locks.dump_at_safepoint(); 4225 } 4226 #endif // INCLUDE_ALL_GCS 4227 4228 ALL_JAVA_THREADS(p) { 4229 ResourceMark rm; 4230 p->print_on(st); 4231 if (print_stacks) { 4232 if (internal_format) { 4233 p->trace_stack(); 4234 } else { 4235 p->print_stack_on(st); 4236 } 4237 } 4238 st->cr(); 4239 #if INCLUDE_ALL_GCS 4240 if (print_concurrent_locks) { 4241 concurrent_locks.print_locks_on(p, st); 4242 } 4243 #endif // INCLUDE_ALL_GCS 4244 } 4245 4246 VMThread::vm_thread()->print_on(st); 4247 st->cr(); 4248 Universe::heap()->print_gc_threads_on(st); 4249 WatcherThread* wt = WatcherThread::watcher_thread(); 4250 if (wt != NULL) { 4251 wt->print_on(st); 4252 st->cr(); 4253 } 4254 CompileBroker::print_compiler_threads_on(st); 4255 st->flush(); 4256 } 4257 4258 // Threads::print_on_error() is called by fatal error handler. It's possible 4259 // that VM is not at safepoint and/or current thread is inside signal handler. 4260 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4261 // memory (even in resource area), it might deadlock the error handler. 4262 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4263 int buflen) { 4264 bool found_current = false; 4265 st->print_cr("Java Threads: ( => current thread )"); 4266 ALL_JAVA_THREADS(thread) { 4267 bool is_current = (current == thread); 4268 found_current = found_current || is_current; 4269 4270 st->print("%s", is_current ? "=>" : " "); 4271 4272 st->print(PTR_FORMAT, thread); 4273 st->print(" "); 4274 thread->print_on_error(st, buf, buflen); 4275 st->cr(); 4276 } 4277 st->cr(); 4278 4279 st->print_cr("Other Threads:"); 4280 if (VMThread::vm_thread()) { 4281 bool is_current = (current == VMThread::vm_thread()); 4282 found_current = found_current || is_current; 4283 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4284 4285 st->print(PTR_FORMAT, VMThread::vm_thread()); 4286 st->print(" "); 4287 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4288 st->cr(); 4289 } 4290 WatcherThread* wt = WatcherThread::watcher_thread(); 4291 if (wt != NULL) { 4292 bool is_current = (current == wt); 4293 found_current = found_current || is_current; 4294 st->print("%s", is_current ? "=>" : " "); 4295 4296 st->print(PTR_FORMAT, wt); 4297 st->print(" "); 4298 wt->print_on_error(st, buf, buflen); 4299 st->cr(); 4300 } 4301 if (!found_current) { 4302 st->cr(); 4303 st->print("=>" PTR_FORMAT " (exited) ", current); 4304 current->print_on_error(st, buf, buflen); 4305 st->cr(); 4306 } 4307 } 4308 4309 // Internal SpinLock and Mutex 4310 // Based on ParkEvent 4311 4312 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4313 // 4314 // We employ SpinLocks _only for low-contention, fixed-length 4315 // short-duration critical sections where we're concerned 4316 // about native mutex_t or HotSpot Mutex:: latency. 4317 // The mux construct provides a spin-then-block mutual exclusion 4318 // mechanism. 4319 // 4320 // Testing has shown that contention on the ListLock guarding gFreeList 4321 // is common. If we implement ListLock as a simple SpinLock it's common 4322 // for the JVM to devolve to yielding with little progress. This is true 4323 // despite the fact that the critical sections protected by ListLock are 4324 // extremely short. 4325 // 4326 // TODO-FIXME: ListLock should be of type SpinLock. 4327 // We should make this a 1st-class type, integrated into the lock 4328 // hierarchy as leaf-locks. Critically, the SpinLock structure 4329 // should have sufficient padding to avoid false-sharing and excessive 4330 // cache-coherency traffic. 4331 4332 4333 typedef volatile int SpinLockT; 4334 4335 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4336 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4337 return; // normal fast-path return 4338 } 4339 4340 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4341 TEVENT(SpinAcquire - ctx); 4342 int ctr = 0; 4343 int Yields = 0; 4344 for (;;) { 4345 while (*adr != 0) { 4346 ++ctr; 4347 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4348 if (Yields > 5) { 4349 os::naked_short_sleep(1); 4350 } else { 4351 os::naked_yield(); 4352 ++Yields; 4353 } 4354 } else { 4355 SpinPause(); 4356 } 4357 } 4358 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4359 } 4360 } 4361 4362 void Thread::SpinRelease(volatile int * adr) { 4363 assert(*adr != 0, "invariant"); 4364 OrderAccess::fence(); // guarantee at least release consistency. 4365 // Roach-motel semantics. 4366 // It's safe if subsequent LDs and STs float "up" into the critical section, 4367 // but prior LDs and STs within the critical section can't be allowed 4368 // to reorder or float past the ST that releases the lock. 4369 // Loads and stores in the critical section - which appear in program 4370 // order before the store that releases the lock - must also appear 4371 // before the store that releases the lock in memory visibility order. 4372 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4373 // the ST of 0 into the lock-word which releases the lock, so fence 4374 // more than covers this on all platforms. 4375 *adr = 0; 4376 } 4377 4378 // muxAcquire and muxRelease: 4379 // 4380 // * muxAcquire and muxRelease support a single-word lock-word construct. 4381 // The LSB of the word is set IFF the lock is held. 4382 // The remainder of the word points to the head of a singly-linked list 4383 // of threads blocked on the lock. 4384 // 4385 // * The current implementation of muxAcquire-muxRelease uses its own 4386 // dedicated Thread._MuxEvent instance. If we're interested in 4387 // minimizing the peak number of extant ParkEvent instances then 4388 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4389 // as certain invariants were satisfied. Specifically, care would need 4390 // to be taken with regards to consuming unpark() "permits". 4391 // A safe rule of thumb is that a thread would never call muxAcquire() 4392 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4393 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4394 // consume an unpark() permit intended for monitorenter, for instance. 4395 // One way around this would be to widen the restricted-range semaphore 4396 // implemented in park(). Another alternative would be to provide 4397 // multiple instances of the PlatformEvent() for each thread. One 4398 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4399 // 4400 // * Usage: 4401 // -- Only as leaf locks 4402 // -- for short-term locking only as muxAcquire does not perform 4403 // thread state transitions. 4404 // 4405 // Alternatives: 4406 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4407 // but with parking or spin-then-park instead of pure spinning. 4408 // * Use Taura-Oyama-Yonenzawa locks. 4409 // * It's possible to construct a 1-0 lock if we encode the lockword as 4410 // (List,LockByte). Acquire will CAS the full lockword while Release 4411 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4412 // acquiring threads use timers (ParkTimed) to detect and recover from 4413 // the stranding window. Thread/Node structures must be aligned on 256-byte 4414 // boundaries by using placement-new. 4415 // * Augment MCS with advisory back-link fields maintained with CAS(). 4416 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4417 // The validity of the backlinks must be ratified before we trust the value. 4418 // If the backlinks are invalid the exiting thread must back-track through the 4419 // the forward links, which are always trustworthy. 4420 // * Add a successor indication. The LockWord is currently encoded as 4421 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4422 // to provide the usual futile-wakeup optimization. 4423 // See RTStt for details. 4424 // * Consider schedctl.sc_nopreempt to cover the critical section. 4425 // 4426 4427 4428 typedef volatile intptr_t MutexT; // Mux Lock-word 4429 enum MuxBits { LOCKBIT = 1 }; 4430 4431 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4432 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4433 if (w == 0) return; 4434 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4435 return; 4436 } 4437 4438 TEVENT(muxAcquire - Contention); 4439 ParkEvent * const Self = Thread::current()->_MuxEvent; 4440 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4441 for (;;) { 4442 int its = (os::is_MP() ? 100 : 0) + 1; 4443 4444 // Optional spin phase: spin-then-park strategy 4445 while (--its >= 0) { 4446 w = *Lock; 4447 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4448 return; 4449 } 4450 } 4451 4452 Self->reset(); 4453 Self->OnList = intptr_t(Lock); 4454 // The following fence() isn't _strictly necessary as the subsequent 4455 // CAS() both serializes execution and ratifies the fetched *Lock value. 4456 OrderAccess::fence(); 4457 for (;;) { 4458 w = *Lock; 4459 if ((w & LOCKBIT) == 0) { 4460 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4461 Self->OnList = 0; // hygiene - allows stronger asserts 4462 return; 4463 } 4464 continue; // Interference -- *Lock changed -- Just retry 4465 } 4466 assert(w & LOCKBIT, "invariant"); 4467 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4468 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4469 } 4470 4471 while (Self->OnList != 0) { 4472 Self->park(); 4473 } 4474 } 4475 } 4476 4477 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4478 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4479 if (w == 0) return; 4480 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4481 return; 4482 } 4483 4484 TEVENT(muxAcquire - Contention); 4485 ParkEvent * ReleaseAfter = NULL; 4486 if (ev == NULL) { 4487 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4488 } 4489 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4490 for (;;) { 4491 guarantee(ev->OnList == 0, "invariant"); 4492 int its = (os::is_MP() ? 100 : 0) + 1; 4493 4494 // Optional spin phase: spin-then-park strategy 4495 while (--its >= 0) { 4496 w = *Lock; 4497 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4498 if (ReleaseAfter != NULL) { 4499 ParkEvent::Release(ReleaseAfter); 4500 } 4501 return; 4502 } 4503 } 4504 4505 ev->reset(); 4506 ev->OnList = intptr_t(Lock); 4507 // The following fence() isn't _strictly necessary as the subsequent 4508 // CAS() both serializes execution and ratifies the fetched *Lock value. 4509 OrderAccess::fence(); 4510 for (;;) { 4511 w = *Lock; 4512 if ((w & LOCKBIT) == 0) { 4513 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4514 ev->OnList = 0; 4515 // We call ::Release while holding the outer lock, thus 4516 // artificially lengthening the critical section. 4517 // Consider deferring the ::Release() until the subsequent unlock(), 4518 // after we've dropped the outer lock. 4519 if (ReleaseAfter != NULL) { 4520 ParkEvent::Release(ReleaseAfter); 4521 } 4522 return; 4523 } 4524 continue; // Interference -- *Lock changed -- Just retry 4525 } 4526 assert(w & LOCKBIT, "invariant"); 4527 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4528 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4529 } 4530 4531 while (ev->OnList != 0) { 4532 ev->park(); 4533 } 4534 } 4535 } 4536 4537 // Release() must extract a successor from the list and then wake that thread. 4538 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4539 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4540 // Release() would : 4541 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4542 // (B) Extract a successor from the private list "in-hand" 4543 // (C) attempt to CAS() the residual back into *Lock over null. 4544 // If there were any newly arrived threads and the CAS() would fail. 4545 // In that case Release() would detach the RATs, re-merge the list in-hand 4546 // with the RATs and repeat as needed. Alternately, Release() might 4547 // detach and extract a successor, but then pass the residual list to the wakee. 4548 // The wakee would be responsible for reattaching and remerging before it 4549 // competed for the lock. 4550 // 4551 // Both "pop" and DMR are immune from ABA corruption -- there can be 4552 // multiple concurrent pushers, but only one popper or detacher. 4553 // This implementation pops from the head of the list. This is unfair, 4554 // but tends to provide excellent throughput as hot threads remain hot. 4555 // (We wake recently run threads first). 4556 // 4557 // All paths through muxRelease() will execute a CAS. 4558 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4559 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4560 // executed within the critical section are complete and globally visible before the 4561 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4562 void Thread::muxRelease(volatile intptr_t * Lock) { 4563 for (;;) { 4564 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4565 assert(w & LOCKBIT, "invariant"); 4566 if (w == LOCKBIT) return; 4567 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4568 assert(List != NULL, "invariant"); 4569 assert(List->OnList == intptr_t(Lock), "invariant"); 4570 ParkEvent * const nxt = List->ListNext; 4571 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4572 4573 // The following CAS() releases the lock and pops the head element. 4574 // The CAS() also ratifies the previously fetched lock-word value. 4575 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4576 continue; 4577 } 4578 List->OnList = 0; 4579 OrderAccess::fence(); 4580 List->unpark(); 4581 return; 4582 } 4583 } 4584 4585 4586 void Threads::verify() { 4587 ALL_JAVA_THREADS(p) { 4588 p->verify(); 4589 } 4590 VMThread* thread = VMThread::vm_thread(); 4591 if (thread != NULL) thread->verify(); 4592 }