1 /* 2 * Copyright (c) 1997, 2017, 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/moduleEntry.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/scopeDesc.hpp" 33 #include "compiler/compileBroker.hpp" 34 #include "compiler/compileTask.hpp" 35 #include "gc/shared/gcId.hpp" 36 #include "gc/shared/gcLocker.inline.hpp" 37 #include "gc/shared/workgroup.hpp" 38 #include "interpreter/interpreter.hpp" 39 #include "interpreter/linkResolver.hpp" 40 #include "interpreter/oopMapCache.hpp" 41 #include "jvmtifiles/jvmtiEnv.hpp" 42 #include "logging/log.hpp" 43 #include "logging/logConfiguration.hpp" 44 #include "logging/logStream.hpp" 45 #include "memory/metaspaceShared.hpp" 46 #include "memory/oopFactory.hpp" 47 #include "memory/resourceArea.hpp" 48 #include "memory/universe.inline.hpp" 49 #include "oops/instanceKlass.hpp" 50 #include "oops/objArrayOop.hpp" 51 #include "oops/oop.inline.hpp" 52 #include "oops/symbol.hpp" 53 #include "oops/verifyOopClosure.hpp" 54 #include "prims/jvm.h" 55 #include "prims/jvm_misc.hpp" 56 #include "prims/jvmtiExport.hpp" 57 #include "prims/jvmtiThreadState.hpp" 58 #include "prims/privilegedStack.hpp" 59 #include "runtime/arguments.hpp" 60 #include "runtime/atomic.hpp" 61 #include "runtime/biasedLocking.hpp" 62 #include "runtime/commandLineFlagConstraintList.hpp" 63 #include "runtime/commandLineFlagWriteableList.hpp" 64 #include "runtime/commandLineFlagRangeList.hpp" 65 #include "runtime/deoptimization.hpp" 66 #include "runtime/frame.inline.hpp" 67 #include "runtime/globals.hpp" 68 #include "runtime/init.hpp" 69 #include "runtime/interfaceSupport.hpp" 70 #include "runtime/java.hpp" 71 #include "runtime/javaCalls.hpp" 72 #include "runtime/jniPeriodicChecker.hpp" 73 #include "runtime/timerTrace.hpp" 74 #include "runtime/memprofiler.hpp" 75 #include "runtime/mutexLocker.hpp" 76 #include "runtime/objectMonitor.hpp" 77 #include "runtime/orderAccess.inline.hpp" 78 #include "runtime/osThread.hpp" 79 #include "runtime/safepoint.hpp" 80 #include "runtime/safepointMechanism.inline.hpp" 81 #include "runtime/sharedRuntime.hpp" 82 #include "runtime/statSampler.hpp" 83 #include "runtime/stubRoutines.hpp" 84 #include "runtime/sweeper.hpp" 85 #include "runtime/task.hpp" 86 #include "runtime/thread.inline.hpp" 87 #include "runtime/threadCritical.hpp" 88 #include "runtime/vframe.hpp" 89 #include "runtime/vframeArray.hpp" 90 #include "runtime/vframe_hp.hpp" 91 #include "runtime/vmThread.hpp" 92 #include "runtime/vm_operations.hpp" 93 #include "runtime/vm_version.hpp" 94 #include "services/attachListener.hpp" 95 #include "services/management.hpp" 96 #include "services/memTracker.hpp" 97 #include "services/threadService.hpp" 98 #include "trace/traceMacros.hpp" 99 #include "trace/tracing.hpp" 100 #include "utilities/align.hpp" 101 #include "utilities/defaultStream.hpp" 102 #include "utilities/dtrace.hpp" 103 #include "utilities/events.hpp" 104 #include "utilities/macros.hpp" 105 #include "utilities/preserveException.hpp" 106 #include "utilities/vmError.hpp" 107 #if INCLUDE_ALL_GCS 108 #include "gc/cms/concurrentMarkSweepThread.hpp" 109 #include "gc/g1/concurrentMarkThread.inline.hpp" 110 #include "gc/parallel/pcTasks.hpp" 111 #endif // INCLUDE_ALL_GCS 112 #if INCLUDE_JVMCI 113 #include "jvmci/jvmciCompiler.hpp" 114 #include "jvmci/jvmciRuntime.hpp" 115 #include "logging/logHandle.hpp" 116 #endif 117 #ifdef COMPILER1 118 #include "c1/c1_Compiler.hpp" 119 #endif 120 #ifdef COMPILER2 121 #include "opto/c2compiler.hpp" 122 #include "opto/idealGraphPrinter.hpp" 123 #endif 124 #if INCLUDE_RTM_OPT 125 #include "runtime/rtmLocking.hpp" 126 #endif 127 128 // Initialization after module runtime initialization 129 void universe_post_module_init(); // must happen after call_initPhase2 130 131 #ifdef DTRACE_ENABLED 132 133 // Only bother with this argument setup if dtrace is available 134 135 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 136 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 137 138 #define DTRACE_THREAD_PROBE(probe, javathread) \ 139 { \ 140 ResourceMark rm(this); \ 141 int len = 0; \ 142 const char* name = (javathread)->get_thread_name(); \ 143 len = strlen(name); \ 144 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 145 (char *) name, len, \ 146 java_lang_Thread::thread_id((javathread)->threadObj()), \ 147 (uintptr_t) (javathread)->osthread()->thread_id(), \ 148 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 149 } 150 151 #else // ndef DTRACE_ENABLED 152 153 #define DTRACE_THREAD_PROBE(probe, javathread) 154 155 #endif // ndef DTRACE_ENABLED 156 157 #ifndef USE_LIBRARY_BASED_TLS_ONLY 158 // Current thread is maintained as a thread-local variable 159 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 160 #endif 161 // Class hierarchy 162 // - Thread 163 // - VMThread 164 // - WatcherThread 165 // - ConcurrentMarkSweepThread 166 // - JavaThread 167 // - CompilerThread 168 169 // ======= Thread ======== 170 // Support for forcing alignment of thread objects for biased locking 171 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 172 if (UseBiasedLocking) { 173 const int alignment = markOopDesc::biased_lock_alignment; 174 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 175 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 176 : AllocateHeap(aligned_size, flags, CURRENT_PC, 177 AllocFailStrategy::RETURN_NULL); 178 void* aligned_addr = align_up(real_malloc_addr, alignment); 179 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 180 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 181 "JavaThread alignment code overflowed allocated storage"); 182 if (aligned_addr != real_malloc_addr) { 183 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 184 p2i(real_malloc_addr), 185 p2i(aligned_addr)); 186 } 187 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 188 return aligned_addr; 189 } else { 190 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 191 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 192 } 193 } 194 195 void Thread::operator delete(void* p) { 196 if (UseBiasedLocking) { 197 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 198 FreeHeap(real_malloc_addr); 199 } else { 200 FreeHeap(p); 201 } 202 } 203 204 205 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 206 // JavaThread 207 208 209 Thread::Thread() { 210 // stack and get_thread 211 set_stack_base(NULL); 212 set_stack_size(0); 213 set_self_raw_id(0); 214 set_lgrp_id(-1); 215 DEBUG_ONLY(clear_suspendible_thread();) 216 217 // allocated data structures 218 set_osthread(NULL); 219 set_resource_area(new (mtThread)ResourceArea()); 220 DEBUG_ONLY(_current_resource_mark = NULL;) 221 set_handle_area(new (mtThread) HandleArea(NULL)); 222 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 223 set_active_handles(NULL); 224 set_free_handle_block(NULL); 225 set_last_handle_mark(NULL); 226 227 // This initial value ==> never claimed. 228 _oops_do_parity = 0; 229 230 // the handle mark links itself to last_handle_mark 231 new HandleMark(this); 232 233 // plain initialization 234 debug_only(_owned_locks = NULL;) 235 debug_only(_allow_allocation_count = 0;) 236 NOT_PRODUCT(_allow_safepoint_count = 0;) 237 NOT_PRODUCT(_skip_gcalot = false;) 238 _jvmti_env_iteration_count = 0; 239 set_allocated_bytes(0); 240 _vm_operation_started_count = 0; 241 _vm_operation_completed_count = 0; 242 _current_pending_monitor = NULL; 243 _current_pending_monitor_is_from_java = true; 244 _current_waiting_monitor = NULL; 245 _num_nested_signal = 0; 246 omFreeList = NULL; 247 omFreeCount = 0; 248 omFreeProvision = 32; 249 omInUseList = NULL; 250 omInUseCount = 0; 251 252 #ifdef ASSERT 253 _visited_for_critical_count = false; 254 #endif 255 256 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 257 Monitor::_safepoint_check_sometimes); 258 _suspend_flags = 0; 259 260 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 261 _hashStateX = os::random(); 262 _hashStateY = 842502087; 263 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 264 _hashStateW = 273326509; 265 266 _OnTrap = 0; 267 _schedctl = NULL; 268 _Stalled = 0; 269 _TypeTag = 0x2BAD; 270 271 // Many of the following fields are effectively final - immutable 272 // Note that nascent threads can't use the Native Monitor-Mutex 273 // construct until the _MutexEvent is initialized ... 274 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 275 // we might instead use a stack of ParkEvents that we could provision on-demand. 276 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 277 // and ::Release() 278 _ParkEvent = ParkEvent::Allocate(this); 279 _SleepEvent = ParkEvent::Allocate(this); 280 _MutexEvent = ParkEvent::Allocate(this); 281 _MuxEvent = ParkEvent::Allocate(this); 282 283 #ifdef CHECK_UNHANDLED_OOPS 284 if (CheckUnhandledOops) { 285 _unhandled_oops = new UnhandledOops(this); 286 } 287 #endif // CHECK_UNHANDLED_OOPS 288 #ifdef ASSERT 289 if (UseBiasedLocking) { 290 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 291 assert(this == _real_malloc_address || 292 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 293 "bug in forced alignment of thread objects"); 294 } 295 #endif // ASSERT 296 } 297 298 void Thread::initialize_thread_current() { 299 #ifndef USE_LIBRARY_BASED_TLS_ONLY 300 assert(_thr_current == NULL, "Thread::current already initialized"); 301 _thr_current = this; 302 #endif 303 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 304 ThreadLocalStorage::set_thread(this); 305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 306 } 307 308 void Thread::clear_thread_current() { 309 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 310 #ifndef USE_LIBRARY_BASED_TLS_ONLY 311 _thr_current = NULL; 312 #endif 313 ThreadLocalStorage::set_thread(NULL); 314 } 315 316 void Thread::record_stack_base_and_size() { 317 set_stack_base(os::current_stack_base()); 318 set_stack_size(os::current_stack_size()); 319 // CR 7190089: on Solaris, primordial thread's stack is adjusted 320 // in initialize_thread(). Without the adjustment, stack size is 321 // incorrect if stack is set to unlimited (ulimit -s unlimited). 322 // So far, only Solaris has real implementation of initialize_thread(). 323 // 324 // set up any platform-specific state. 325 os::initialize_thread(this); 326 327 // Set stack limits after thread is initialized. 328 if (is_Java_thread()) { 329 ((JavaThread*) this)->set_stack_overflow_limit(); 330 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 331 } 332 #if INCLUDE_NMT 333 // record thread's native stack, stack grows downward 334 MemTracker::record_thread_stack(stack_end(), stack_size()); 335 #endif // INCLUDE_NMT 336 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 337 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 338 os::current_thread_id(), p2i(stack_base() - stack_size()), 339 p2i(stack_base()), stack_size()/1024); 340 } 341 342 343 Thread::~Thread() { 344 EVENT_THREAD_DESTRUCT(this); 345 346 // stack_base can be NULL if the thread is never started or exited before 347 // record_stack_base_and_size called. Although, we would like to ensure 348 // that all started threads do call record_stack_base_and_size(), there is 349 // not proper way to enforce that. 350 #if INCLUDE_NMT 351 if (_stack_base != NULL) { 352 MemTracker::release_thread_stack(stack_end(), stack_size()); 353 #ifdef ASSERT 354 set_stack_base(NULL); 355 #endif 356 } 357 #endif // INCLUDE_NMT 358 359 // deallocate data structures 360 delete resource_area(); 361 // since the handle marks are using the handle area, we have to deallocated the root 362 // handle mark before deallocating the thread's handle area, 363 assert(last_handle_mark() != NULL, "check we have an element"); 364 delete last_handle_mark(); 365 assert(last_handle_mark() == NULL, "check we have reached the end"); 366 367 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 368 // We NULL out the fields for good hygiene. 369 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 370 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 371 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 372 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 373 374 delete handle_area(); 375 delete metadata_handles(); 376 377 // SR_handler uses this as a termination indicator - 378 // needs to happen before os::free_thread() 379 delete _SR_lock; 380 _SR_lock = NULL; 381 382 // osthread() can be NULL, if creation of thread failed. 383 if (osthread() != NULL) os::free_thread(osthread()); 384 385 // clear Thread::current if thread is deleting itself. 386 // Needed to ensure JNI correctly detects non-attached threads. 387 if (this == Thread::current()) { 388 clear_thread_current(); 389 } 390 391 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 392 } 393 394 // NOTE: dummy function for assertion purpose. 395 void Thread::run() { 396 ShouldNotReachHere(); 397 } 398 399 #ifdef ASSERT 400 // Private method to check for dangling thread pointer 401 void check_for_dangling_thread_pointer(Thread *thread) { 402 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 403 "possibility of dangling Thread pointer"); 404 } 405 #endif 406 407 ThreadPriority Thread::get_priority(const Thread* const thread) { 408 ThreadPriority priority; 409 // Can return an error! 410 (void)os::get_priority(thread, priority); 411 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 412 return priority; 413 } 414 415 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 416 debug_only(check_for_dangling_thread_pointer(thread);) 417 // Can return an error! 418 (void)os::set_priority(thread, priority); 419 } 420 421 422 void Thread::start(Thread* thread) { 423 // Start is different from resume in that its safety is guaranteed by context or 424 // being called from a Java method synchronized on the Thread object. 425 if (!DisableStartThread) { 426 if (thread->is_Java_thread()) { 427 // Initialize the thread state to RUNNABLE before starting this thread. 428 // Can not set it after the thread started because we do not know the 429 // exact thread state at that time. It could be in MONITOR_WAIT or 430 // in SLEEPING or some other state. 431 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 432 java_lang_Thread::RUNNABLE); 433 } 434 os::start_thread(thread); 435 } 436 } 437 438 // Enqueue a VM_Operation to do the job for us - sometime later 439 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 440 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 441 VMThread::execute(vm_stop); 442 } 443 444 445 // Check if an external suspend request has completed (or has been 446 // cancelled). Returns true if the thread is externally suspended and 447 // false otherwise. 448 // 449 // The bits parameter returns information about the code path through 450 // the routine. Useful for debugging: 451 // 452 // set in is_ext_suspend_completed(): 453 // 0x00000001 - routine was entered 454 // 0x00000010 - routine return false at end 455 // 0x00000100 - thread exited (return false) 456 // 0x00000200 - suspend request cancelled (return false) 457 // 0x00000400 - thread suspended (return true) 458 // 0x00001000 - thread is in a suspend equivalent state (return true) 459 // 0x00002000 - thread is native and walkable (return true) 460 // 0x00004000 - thread is native_trans and walkable (needed retry) 461 // 462 // set in wait_for_ext_suspend_completion(): 463 // 0x00010000 - routine was entered 464 // 0x00020000 - suspend request cancelled before loop (return false) 465 // 0x00040000 - thread suspended before loop (return true) 466 // 0x00080000 - suspend request cancelled in loop (return false) 467 // 0x00100000 - thread suspended in loop (return true) 468 // 0x00200000 - suspend not completed during retry loop (return false) 469 470 // Helper class for tracing suspend wait debug bits. 471 // 472 // 0x00000100 indicates that the target thread exited before it could 473 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 474 // 0x00080000 each indicate a cancelled suspend request so they don't 475 // count as wait failures either. 476 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 477 478 class TraceSuspendDebugBits : public StackObj { 479 private: 480 JavaThread * jt; 481 bool is_wait; 482 bool called_by_wait; // meaningful when !is_wait 483 uint32_t * bits; 484 485 public: 486 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 487 uint32_t *_bits) { 488 jt = _jt; 489 is_wait = _is_wait; 490 called_by_wait = _called_by_wait; 491 bits = _bits; 492 } 493 494 ~TraceSuspendDebugBits() { 495 if (!is_wait) { 496 #if 1 497 // By default, don't trace bits for is_ext_suspend_completed() calls. 498 // That trace is very chatty. 499 return; 500 #else 501 if (!called_by_wait) { 502 // If tracing for is_ext_suspend_completed() is enabled, then only 503 // trace calls to it from wait_for_ext_suspend_completion() 504 return; 505 } 506 #endif 507 } 508 509 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 510 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 511 MutexLocker ml(Threads_lock); // needed for get_thread_name() 512 ResourceMark rm; 513 514 tty->print_cr( 515 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 516 jt->get_thread_name(), *bits); 517 518 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 519 } 520 } 521 } 522 }; 523 #undef DEBUG_FALSE_BITS 524 525 526 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 527 uint32_t *bits) { 528 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 529 530 bool did_trans_retry = false; // only do thread_in_native_trans retry once 531 bool do_trans_retry; // flag to force the retry 532 533 *bits |= 0x00000001; 534 535 do { 536 do_trans_retry = false; 537 538 if (is_exiting()) { 539 // Thread is in the process of exiting. This is always checked 540 // first to reduce the risk of dereferencing a freed JavaThread. 541 *bits |= 0x00000100; 542 return false; 543 } 544 545 if (!is_external_suspend()) { 546 // Suspend request is cancelled. This is always checked before 547 // is_ext_suspended() to reduce the risk of a rogue resume 548 // confusing the thread that made the suspend request. 549 *bits |= 0x00000200; 550 return false; 551 } 552 553 if (is_ext_suspended()) { 554 // thread is suspended 555 *bits |= 0x00000400; 556 return true; 557 } 558 559 // Now that we no longer do hard suspends of threads running 560 // native code, the target thread can be changing thread state 561 // while we are in this routine: 562 // 563 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 564 // 565 // We save a copy of the thread state as observed at this moment 566 // and make our decision about suspend completeness based on the 567 // copy. This closes the race where the thread state is seen as 568 // _thread_in_native_trans in the if-thread_blocked check, but is 569 // seen as _thread_blocked in if-thread_in_native_trans check. 570 JavaThreadState save_state = thread_state(); 571 572 if (save_state == _thread_blocked && is_suspend_equivalent()) { 573 // If the thread's state is _thread_blocked and this blocking 574 // condition is known to be equivalent to a suspend, then we can 575 // consider the thread to be externally suspended. This means that 576 // the code that sets _thread_blocked has been modified to do 577 // self-suspension if the blocking condition releases. We also 578 // used to check for CONDVAR_WAIT here, but that is now covered by 579 // the _thread_blocked with self-suspension check. 580 // 581 // Return true since we wouldn't be here unless there was still an 582 // external suspend request. 583 *bits |= 0x00001000; 584 return true; 585 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 586 // Threads running native code will self-suspend on native==>VM/Java 587 // transitions. If its stack is walkable (should always be the case 588 // unless this function is called before the actual java_suspend() 589 // call), then the wait is done. 590 *bits |= 0x00002000; 591 return true; 592 } else if (!called_by_wait && !did_trans_retry && 593 save_state == _thread_in_native_trans && 594 frame_anchor()->walkable()) { 595 // The thread is transitioning from thread_in_native to another 596 // thread state. check_safepoint_and_suspend_for_native_trans() 597 // will force the thread to self-suspend. If it hasn't gotten 598 // there yet we may have caught the thread in-between the native 599 // code check above and the self-suspend. Lucky us. If we were 600 // called by wait_for_ext_suspend_completion(), then it 601 // will be doing the retries so we don't have to. 602 // 603 // Since we use the saved thread state in the if-statement above, 604 // there is a chance that the thread has already transitioned to 605 // _thread_blocked by the time we get here. In that case, we will 606 // make a single unnecessary pass through the logic below. This 607 // doesn't hurt anything since we still do the trans retry. 608 609 *bits |= 0x00004000; 610 611 // Once the thread leaves thread_in_native_trans for another 612 // thread state, we break out of this retry loop. We shouldn't 613 // need this flag to prevent us from getting back here, but 614 // sometimes paranoia is good. 615 did_trans_retry = true; 616 617 // We wait for the thread to transition to a more usable state. 618 for (int i = 1; i <= SuspendRetryCount; i++) { 619 // We used to do an "os::yield_all(i)" call here with the intention 620 // that yielding would increase on each retry. However, the parameter 621 // is ignored on Linux which means the yield didn't scale up. Waiting 622 // on the SR_lock below provides a much more predictable scale up for 623 // the delay. It also provides a simple/direct point to check for any 624 // safepoint requests from the VMThread 625 626 // temporarily drops SR_lock while doing wait with safepoint check 627 // (if we're a JavaThread - the WatcherThread can also call this) 628 // and increase delay with each retry 629 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 630 631 // check the actual thread state instead of what we saved above 632 if (thread_state() != _thread_in_native_trans) { 633 // the thread has transitioned to another thread state so 634 // try all the checks (except this one) one more time. 635 do_trans_retry = true; 636 break; 637 } 638 } // end retry loop 639 640 641 } 642 } while (do_trans_retry); 643 644 *bits |= 0x00000010; 645 return false; 646 } 647 648 // Wait for an external suspend request to complete (or be cancelled). 649 // Returns true if the thread is externally suspended and false otherwise. 650 // 651 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 652 uint32_t *bits) { 653 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 654 false /* !called_by_wait */, bits); 655 656 // local flag copies to minimize SR_lock hold time 657 bool is_suspended; 658 bool pending; 659 uint32_t reset_bits; 660 661 // set a marker so is_ext_suspend_completed() knows we are the caller 662 *bits |= 0x00010000; 663 664 // We use reset_bits to reinitialize the bits value at the top of 665 // each retry loop. This allows the caller to make use of any 666 // unused bits for their own marking purposes. 667 reset_bits = *bits; 668 669 { 670 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 671 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 672 delay, bits); 673 pending = is_external_suspend(); 674 } 675 // must release SR_lock to allow suspension to complete 676 677 if (!pending) { 678 // A cancelled suspend request is the only false return from 679 // is_ext_suspend_completed() that keeps us from entering the 680 // retry loop. 681 *bits |= 0x00020000; 682 return false; 683 } 684 685 if (is_suspended) { 686 *bits |= 0x00040000; 687 return true; 688 } 689 690 for (int i = 1; i <= retries; i++) { 691 *bits = reset_bits; // reinit to only track last retry 692 693 // We used to do an "os::yield_all(i)" call here with the intention 694 // that yielding would increase on each retry. However, the parameter 695 // is ignored on Linux which means the yield didn't scale up. Waiting 696 // on the SR_lock below provides a much more predictable scale up for 697 // the delay. It also provides a simple/direct point to check for any 698 // safepoint requests from the VMThread 699 700 { 701 MutexLocker ml(SR_lock()); 702 // wait with safepoint check (if we're a JavaThread - the WatcherThread 703 // can also call this) and increase delay with each retry 704 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 705 706 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 707 delay, bits); 708 709 // It is possible for the external suspend request to be cancelled 710 // (by a resume) before the actual suspend operation is completed. 711 // Refresh our local copy to see if we still need to wait. 712 pending = is_external_suspend(); 713 } 714 715 if (!pending) { 716 // A cancelled suspend request is the only false return from 717 // is_ext_suspend_completed() that keeps us from staying in the 718 // retry loop. 719 *bits |= 0x00080000; 720 return false; 721 } 722 723 if (is_suspended) { 724 *bits |= 0x00100000; 725 return true; 726 } 727 } // end retry loop 728 729 // thread did not suspend after all our retries 730 *bits |= 0x00200000; 731 return false; 732 } 733 734 #ifndef PRODUCT 735 void JavaThread::record_jump(address target, address instr, const char* file, 736 int line) { 737 738 // This should not need to be atomic as the only way for simultaneous 739 // updates is via interrupts. Even then this should be rare or non-existent 740 // and we don't care that much anyway. 741 742 int index = _jmp_ring_index; 743 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 744 _jmp_ring[index]._target = (intptr_t) target; 745 _jmp_ring[index]._instruction = (intptr_t) instr; 746 _jmp_ring[index]._file = file; 747 _jmp_ring[index]._line = line; 748 } 749 #endif // PRODUCT 750 751 void Thread::interrupt(Thread* thread) { 752 debug_only(check_for_dangling_thread_pointer(thread);) 753 os::interrupt(thread); 754 } 755 756 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 757 debug_only(check_for_dangling_thread_pointer(thread);) 758 // Note: If clear_interrupted==false, this simply fetches and 759 // returns the value of the field osthread()->interrupted(). 760 return os::is_interrupted(thread, clear_interrupted); 761 } 762 763 764 // GC Support 765 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 766 jint thread_parity = _oops_do_parity; 767 if (thread_parity != strong_roots_parity) { 768 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 769 if (res == thread_parity) { 770 return true; 771 } else { 772 guarantee(res == strong_roots_parity, "Or else what?"); 773 return false; 774 } 775 } 776 return false; 777 } 778 779 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 780 active_handles()->oops_do(f); 781 // Do oop for ThreadShadow 782 f->do_oop((oop*)&_pending_exception); 783 handle_area()->oops_do(f); 784 785 if (MonitorInUseLists) { 786 // When using thread local monitor lists, we scan them here, 787 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 788 ObjectSynchronizer::thread_local_used_oops_do(this, f); 789 } 790 } 791 792 void Thread::metadata_handles_do(void f(Metadata*)) { 793 // Only walk the Handles in Thread. 794 if (metadata_handles() != NULL) { 795 for (int i = 0; i< metadata_handles()->length(); i++) { 796 f(metadata_handles()->at(i)); 797 } 798 } 799 } 800 801 void Thread::print_on(outputStream* st) const { 802 // get_priority assumes osthread initialized 803 if (osthread() != NULL) { 804 int os_prio; 805 if (os::get_native_priority(this, &os_prio) == OS_OK) { 806 st->print("os_prio=%d ", os_prio); 807 } 808 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 809 ext().print_on(st); 810 osthread()->print_on(st); 811 } 812 debug_only(if (WizardMode) print_owned_locks_on(st);) 813 } 814 815 // Thread::print_on_error() is called by fatal error handler. Don't use 816 // any lock or allocate memory. 817 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 818 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 819 820 if (is_VM_thread()) { st->print("VMThread"); } 821 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 822 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 823 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 824 else { st->print("Thread"); } 825 826 if (is_Named_thread()) { 827 st->print(" \"%s\"", name()); 828 } 829 830 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 831 p2i(stack_end()), p2i(stack_base())); 832 833 if (osthread()) { 834 st->print(" [id=%d]", osthread()->thread_id()); 835 } 836 } 837 838 void Thread::print_value_on(outputStream* st) const { 839 if (is_Named_thread()) { 840 st->print(" \"%s\" ", name()); 841 } 842 st->print(INTPTR_FORMAT, p2i(this)); // print address 843 } 844 845 #ifdef ASSERT 846 void Thread::print_owned_locks_on(outputStream* st) const { 847 Monitor *cur = _owned_locks; 848 if (cur == NULL) { 849 st->print(" (no locks) "); 850 } else { 851 st->print_cr(" Locks owned:"); 852 while (cur) { 853 cur->print_on(st); 854 cur = cur->next(); 855 } 856 } 857 } 858 859 static int ref_use_count = 0; 860 861 bool Thread::owns_locks_but_compiled_lock() const { 862 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 863 if (cur != Compile_lock) return true; 864 } 865 return false; 866 } 867 868 869 #endif 870 871 #ifndef PRODUCT 872 873 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 874 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 875 // no threads which allow_vm_block's are held 876 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 877 // Check if current thread is allowed to block at a safepoint 878 if (!(_allow_safepoint_count == 0)) { 879 fatal("Possible safepoint reached by thread that does not allow it"); 880 } 881 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 882 fatal("LEAF method calling lock?"); 883 } 884 885 #ifdef ASSERT 886 if (potential_vm_operation && is_Java_thread() 887 && !Universe::is_bootstrapping()) { 888 // Make sure we do not hold any locks that the VM thread also uses. 889 // This could potentially lead to deadlocks 890 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 891 // Threads_lock is special, since the safepoint synchronization will not start before this is 892 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 893 // since it is used to transfer control between JavaThreads and the VMThread 894 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 895 if ((cur->allow_vm_block() && 896 cur != Threads_lock && 897 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 898 cur != VMOperationRequest_lock && 899 cur != VMOperationQueue_lock) || 900 cur->rank() == Mutex::special) { 901 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 902 } 903 } 904 } 905 906 if (GCALotAtAllSafepoints) { 907 // We could enter a safepoint here and thus have a gc 908 InterfaceSupport::check_gc_alot(); 909 } 910 #endif 911 } 912 #endif 913 914 bool Thread::is_in_stack(address adr) const { 915 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 916 address end = os::current_stack_pointer(); 917 // Allow non Java threads to call this without stack_base 918 if (_stack_base == NULL) return true; 919 if (stack_base() >= adr && adr >= end) return true; 920 921 return false; 922 } 923 924 bool Thread::is_in_usable_stack(address adr) const { 925 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 926 size_t usable_stack_size = _stack_size - stack_guard_size; 927 928 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 929 } 930 931 932 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 933 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 934 // used for compilation in the future. If that change is made, the need for these methods 935 // should be revisited, and they should be removed if possible. 936 937 bool Thread::is_lock_owned(address adr) const { 938 return on_local_stack(adr); 939 } 940 941 bool Thread::set_as_starting_thread() { 942 // NOTE: this must be called inside the main thread. 943 return os::create_main_thread((JavaThread*)this); 944 } 945 946 static void initialize_class(Symbol* class_name, TRAPS) { 947 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 948 InstanceKlass::cast(klass)->initialize(CHECK); 949 } 950 951 952 // Creates the initial ThreadGroup 953 static Handle create_initial_thread_group(TRAPS) { 954 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 955 InstanceKlass* ik = InstanceKlass::cast(k); 956 957 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 958 { 959 JavaValue result(T_VOID); 960 JavaCalls::call_special(&result, 961 system_instance, 962 ik, 963 vmSymbols::object_initializer_name(), 964 vmSymbols::void_method_signature(), 965 CHECK_NH); 966 } 967 Universe::set_system_thread_group(system_instance()); 968 969 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 970 { 971 JavaValue result(T_VOID); 972 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 973 JavaCalls::call_special(&result, 974 main_instance, 975 ik, 976 vmSymbols::object_initializer_name(), 977 vmSymbols::threadgroup_string_void_signature(), 978 system_instance, 979 string, 980 CHECK_NH); 981 } 982 return main_instance; 983 } 984 985 // Creates the initial Thread 986 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 987 TRAPS) { 988 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 989 InstanceKlass* ik = InstanceKlass::cast(k); 990 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 991 992 java_lang_Thread::set_thread(thread_oop(), thread); 993 java_lang_Thread::set_priority(thread_oop(), NormPriority); 994 thread->set_threadObj(thread_oop()); 995 996 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 997 998 JavaValue result(T_VOID); 999 JavaCalls::call_special(&result, thread_oop, 1000 ik, 1001 vmSymbols::object_initializer_name(), 1002 vmSymbols::threadgroup_string_void_signature(), 1003 thread_group, 1004 string, 1005 CHECK_NULL); 1006 return thread_oop(); 1007 } 1008 1009 char java_runtime_name[128] = ""; 1010 char java_runtime_version[128] = ""; 1011 1012 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1013 static const char* get_java_runtime_name(TRAPS) { 1014 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1015 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1016 fieldDescriptor fd; 1017 bool found = k != NULL && 1018 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1019 vmSymbols::string_signature(), &fd); 1020 if (found) { 1021 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1022 if (name_oop == NULL) { 1023 return NULL; 1024 } 1025 const char* name = java_lang_String::as_utf8_string(name_oop, 1026 java_runtime_name, 1027 sizeof(java_runtime_name)); 1028 return name; 1029 } else { 1030 return NULL; 1031 } 1032 } 1033 1034 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1035 static const char* get_java_runtime_version(TRAPS) { 1036 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1037 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1038 fieldDescriptor fd; 1039 bool found = k != NULL && 1040 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1041 vmSymbols::string_signature(), &fd); 1042 if (found) { 1043 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1044 if (name_oop == NULL) { 1045 return NULL; 1046 } 1047 const char* name = java_lang_String::as_utf8_string(name_oop, 1048 java_runtime_version, 1049 sizeof(java_runtime_version)); 1050 return name; 1051 } else { 1052 return NULL; 1053 } 1054 } 1055 1056 // General purpose hook into Java code, run once when the VM is initialized. 1057 // The Java library method itself may be changed independently from the VM. 1058 static void call_postVMInitHook(TRAPS) { 1059 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1060 if (klass != NULL) { 1061 JavaValue result(T_VOID); 1062 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1063 vmSymbols::void_method_signature(), 1064 CHECK); 1065 } 1066 } 1067 1068 static void reset_vm_info_property(TRAPS) { 1069 // the vm info string 1070 ResourceMark rm(THREAD); 1071 const char *vm_info = VM_Version::vm_info_string(); 1072 1073 // java.lang.System class 1074 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1075 1076 // setProperty arguments 1077 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1078 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1079 1080 // return value 1081 JavaValue r(T_OBJECT); 1082 1083 // public static String setProperty(String key, String value); 1084 JavaCalls::call_static(&r, 1085 klass, 1086 vmSymbols::setProperty_name(), 1087 vmSymbols::string_string_string_signature(), 1088 key_str, 1089 value_str, 1090 CHECK); 1091 } 1092 1093 1094 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1095 bool daemon, TRAPS) { 1096 assert(thread_group.not_null(), "thread group should be specified"); 1097 assert(threadObj() == NULL, "should only create Java thread object once"); 1098 1099 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1100 InstanceKlass* ik = InstanceKlass::cast(k); 1101 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1102 1103 java_lang_Thread::set_thread(thread_oop(), this); 1104 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1105 set_threadObj(thread_oop()); 1106 1107 JavaValue result(T_VOID); 1108 if (thread_name != NULL) { 1109 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1110 // Thread gets assigned specified name and null target 1111 JavaCalls::call_special(&result, 1112 thread_oop, 1113 ik, 1114 vmSymbols::object_initializer_name(), 1115 vmSymbols::threadgroup_string_void_signature(), 1116 thread_group, // Argument 1 1117 name, // Argument 2 1118 THREAD); 1119 } else { 1120 // Thread gets assigned name "Thread-nnn" and null target 1121 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1122 JavaCalls::call_special(&result, 1123 thread_oop, 1124 ik, 1125 vmSymbols::object_initializer_name(), 1126 vmSymbols::threadgroup_runnable_void_signature(), 1127 thread_group, // Argument 1 1128 Handle(), // Argument 2 1129 THREAD); 1130 } 1131 1132 1133 if (daemon) { 1134 java_lang_Thread::set_daemon(thread_oop()); 1135 } 1136 1137 if (HAS_PENDING_EXCEPTION) { 1138 return; 1139 } 1140 1141 Klass* group = SystemDictionary::ThreadGroup_klass(); 1142 Handle threadObj(THREAD, this->threadObj()); 1143 1144 JavaCalls::call_special(&result, 1145 thread_group, 1146 group, 1147 vmSymbols::add_method_name(), 1148 vmSymbols::thread_void_signature(), 1149 threadObj, // Arg 1 1150 THREAD); 1151 } 1152 1153 // NamedThread -- non-JavaThread subclasses with multiple 1154 // uniquely named instances should derive from this. 1155 NamedThread::NamedThread() : Thread() { 1156 _name = NULL; 1157 _processed_thread = NULL; 1158 _gc_id = GCId::undefined(); 1159 } 1160 1161 NamedThread::~NamedThread() { 1162 if (_name != NULL) { 1163 FREE_C_HEAP_ARRAY(char, _name); 1164 _name = NULL; 1165 } 1166 } 1167 1168 void NamedThread::set_name(const char* format, ...) { 1169 guarantee(_name == NULL, "Only get to set name once."); 1170 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1171 guarantee(_name != NULL, "alloc failure"); 1172 va_list ap; 1173 va_start(ap, format); 1174 jio_vsnprintf(_name, max_name_len, format, ap); 1175 va_end(ap); 1176 } 1177 1178 void NamedThread::initialize_named_thread() { 1179 set_native_thread_name(name()); 1180 } 1181 1182 void NamedThread::print_on(outputStream* st) const { 1183 st->print("\"%s\" ", name()); 1184 Thread::print_on(st); 1185 st->cr(); 1186 } 1187 1188 1189 // ======= WatcherThread ======== 1190 1191 // The watcher thread exists to simulate timer interrupts. It should 1192 // be replaced by an abstraction over whatever native support for 1193 // timer interrupts exists on the platform. 1194 1195 WatcherThread* WatcherThread::_watcher_thread = NULL; 1196 bool WatcherThread::_startable = false; 1197 volatile bool WatcherThread::_should_terminate = false; 1198 1199 WatcherThread::WatcherThread() : Thread() { 1200 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1201 if (os::create_thread(this, os::watcher_thread)) { 1202 _watcher_thread = this; 1203 1204 // Set the watcher thread to the highest OS priority which should not be 1205 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1206 // is created. The only normal thread using this priority is the reference 1207 // handler thread, which runs for very short intervals only. 1208 // If the VMThread's priority is not lower than the WatcherThread profiling 1209 // will be inaccurate. 1210 os::set_priority(this, MaxPriority); 1211 if (!DisableStartThread) { 1212 os::start_thread(this); 1213 } 1214 } 1215 } 1216 1217 int WatcherThread::sleep() const { 1218 // The WatcherThread does not participate in the safepoint protocol 1219 // for the PeriodicTask_lock because it is not a JavaThread. 1220 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1221 1222 if (_should_terminate) { 1223 // check for termination before we do any housekeeping or wait 1224 return 0; // we did not sleep. 1225 } 1226 1227 // remaining will be zero if there are no tasks, 1228 // causing the WatcherThread to sleep until a task is 1229 // enrolled 1230 int remaining = PeriodicTask::time_to_wait(); 1231 int time_slept = 0; 1232 1233 // we expect this to timeout - we only ever get unparked when 1234 // we should terminate or when a new task has been enrolled 1235 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1236 1237 jlong time_before_loop = os::javaTimeNanos(); 1238 1239 while (true) { 1240 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1241 remaining); 1242 jlong now = os::javaTimeNanos(); 1243 1244 if (remaining == 0) { 1245 // if we didn't have any tasks we could have waited for a long time 1246 // consider the time_slept zero and reset time_before_loop 1247 time_slept = 0; 1248 time_before_loop = now; 1249 } else { 1250 // need to recalculate since we might have new tasks in _tasks 1251 time_slept = (int) ((now - time_before_loop) / 1000000); 1252 } 1253 1254 // Change to task list or spurious wakeup of some kind 1255 if (timedout || _should_terminate) { 1256 break; 1257 } 1258 1259 remaining = PeriodicTask::time_to_wait(); 1260 if (remaining == 0) { 1261 // Last task was just disenrolled so loop around and wait until 1262 // another task gets enrolled 1263 continue; 1264 } 1265 1266 remaining -= time_slept; 1267 if (remaining <= 0) { 1268 break; 1269 } 1270 } 1271 1272 return time_slept; 1273 } 1274 1275 void WatcherThread::run() { 1276 assert(this == watcher_thread(), "just checking"); 1277 1278 this->record_stack_base_and_size(); 1279 this->set_native_thread_name(this->name()); 1280 this->set_active_handles(JNIHandleBlock::allocate_block()); 1281 while (true) { 1282 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1283 assert(watcher_thread() == this, "thread consistency check"); 1284 1285 // Calculate how long it'll be until the next PeriodicTask work 1286 // should be done, and sleep that amount of time. 1287 int time_waited = sleep(); 1288 1289 if (VMError::is_error_reported()) { 1290 // A fatal error has happened, the error handler(VMError::report_and_die) 1291 // should abort JVM after creating an error log file. However in some 1292 // rare cases, the error handler itself might deadlock. Here periodically 1293 // check for error reporting timeouts, and if it happens, just proceed to 1294 // abort the VM. 1295 1296 // This code is in WatcherThread because WatcherThread wakes up 1297 // periodically so the fatal error handler doesn't need to do anything; 1298 // also because the WatcherThread is less likely to crash than other 1299 // threads. 1300 1301 for (;;) { 1302 // Note: we use naked sleep in this loop because we want to avoid using 1303 // any kind of VM infrastructure which may be broken at this point. 1304 if (VMError::check_timeout()) { 1305 // We hit error reporting timeout. Error reporting was interrupted and 1306 // will be wrapping things up now (closing files etc). Give it some more 1307 // time, then quit the VM. 1308 os::naked_short_sleep(200); 1309 // Print a message to stderr. 1310 fdStream err(defaultStream::output_fd()); 1311 err.print_raw_cr("# [ timer expired, abort... ]"); 1312 // skip atexit/vm_exit/vm_abort hooks 1313 os::die(); 1314 } 1315 1316 // Wait a second, then recheck for timeout. 1317 os::naked_short_sleep(999); 1318 } 1319 } 1320 1321 if (_should_terminate) { 1322 // check for termination before posting the next tick 1323 break; 1324 } 1325 1326 PeriodicTask::real_time_tick(time_waited); 1327 } 1328 1329 // Signal that it is terminated 1330 { 1331 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1332 _watcher_thread = NULL; 1333 Terminator_lock->notify(); 1334 } 1335 } 1336 1337 void WatcherThread::start() { 1338 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1339 1340 if (watcher_thread() == NULL && _startable) { 1341 _should_terminate = false; 1342 // Create the single instance of WatcherThread 1343 new WatcherThread(); 1344 } 1345 } 1346 1347 void WatcherThread::make_startable() { 1348 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1349 _startable = true; 1350 } 1351 1352 void WatcherThread::stop() { 1353 { 1354 // Follow normal safepoint aware lock enter protocol since the 1355 // WatcherThread is stopped by another JavaThread. 1356 MutexLocker ml(PeriodicTask_lock); 1357 _should_terminate = true; 1358 1359 WatcherThread* watcher = watcher_thread(); 1360 if (watcher != NULL) { 1361 // unpark the WatcherThread so it can see that it should terminate 1362 watcher->unpark(); 1363 } 1364 } 1365 1366 MutexLocker mu(Terminator_lock); 1367 1368 while (watcher_thread() != NULL) { 1369 // This wait should make safepoint checks, wait without a timeout, 1370 // and wait as a suspend-equivalent condition. 1371 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1372 Mutex::_as_suspend_equivalent_flag); 1373 } 1374 } 1375 1376 void WatcherThread::unpark() { 1377 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1378 PeriodicTask_lock->notify(); 1379 } 1380 1381 void WatcherThread::print_on(outputStream* st) const { 1382 st->print("\"%s\" ", name()); 1383 Thread::print_on(st); 1384 st->cr(); 1385 } 1386 1387 // ======= JavaThread ======== 1388 1389 #if INCLUDE_JVMCI 1390 1391 jlong* JavaThread::_jvmci_old_thread_counters; 1392 1393 bool jvmci_counters_include(JavaThread* thread) { 1394 oop threadObj = thread->threadObj(); 1395 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1396 } 1397 1398 void JavaThread::collect_counters(typeArrayOop array) { 1399 if (JVMCICounterSize > 0) { 1400 MutexLocker tl(Threads_lock); 1401 for (int i = 0; i < array->length(); i++) { 1402 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1403 } 1404 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) { 1405 if (jvmci_counters_include(tp)) { 1406 for (int i = 0; i < array->length(); i++) { 1407 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1408 } 1409 } 1410 } 1411 } 1412 } 1413 1414 #endif // INCLUDE_JVMCI 1415 1416 // A JavaThread is a normal Java thread 1417 1418 void JavaThread::initialize() { 1419 // Initialize fields 1420 1421 set_saved_exception_pc(NULL); 1422 set_threadObj(NULL); 1423 _anchor.clear(); 1424 set_entry_point(NULL); 1425 set_jni_functions(jni_functions()); 1426 set_callee_target(NULL); 1427 set_vm_result(NULL); 1428 set_vm_result_2(NULL); 1429 set_vframe_array_head(NULL); 1430 set_vframe_array_last(NULL); 1431 set_deferred_locals(NULL); 1432 set_deopt_mark(NULL); 1433 set_deopt_compiled_method(NULL); 1434 clear_must_deopt_id(); 1435 set_monitor_chunks(NULL); 1436 set_next(NULL); 1437 set_thread_state(_thread_new); 1438 _terminated = _not_terminated; 1439 _privileged_stack_top = NULL; 1440 _array_for_gc = NULL; 1441 _suspend_equivalent = false; 1442 _in_deopt_handler = 0; 1443 _doing_unsafe_access = false; 1444 _stack_guard_state = stack_guard_unused; 1445 #if INCLUDE_JVMCI 1446 _pending_monitorenter = false; 1447 _pending_deoptimization = -1; 1448 _pending_failed_speculation = NULL; 1449 _pending_transfer_to_interpreter = false; 1450 _adjusting_comp_level = false; 1451 _jvmci._alternate_call_target = NULL; 1452 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1453 if (JVMCICounterSize > 0) { 1454 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1455 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1456 } else { 1457 _jvmci_counters = NULL; 1458 } 1459 #endif // INCLUDE_JVMCI 1460 _reserved_stack_activation = NULL; // stack base not known yet 1461 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1462 _exception_pc = 0; 1463 _exception_handler_pc = 0; 1464 _is_method_handle_return = 0; 1465 _jvmti_thread_state= NULL; 1466 _should_post_on_exceptions_flag = JNI_FALSE; 1467 _jvmti_get_loaded_classes_closure = NULL; 1468 _interp_only_mode = 0; 1469 _special_runtime_exit_condition = _no_async_condition; 1470 _pending_async_exception = NULL; 1471 _thread_stat = NULL; 1472 _thread_stat = new ThreadStatistics(); 1473 _blocked_on_compilation = false; 1474 _jni_active_critical = 0; 1475 _pending_jni_exception_check_fn = NULL; 1476 _do_not_unlock_if_synchronized = false; 1477 _cached_monitor_info = NULL; 1478 _parker = Parker::Allocate(this); 1479 1480 #ifndef PRODUCT 1481 _jmp_ring_index = 0; 1482 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1483 record_jump(NULL, NULL, NULL, 0); 1484 } 1485 #endif // PRODUCT 1486 1487 // Setup safepoint state info for this thread 1488 ThreadSafepointState::create(this); 1489 1490 debug_only(_java_call_counter = 0); 1491 1492 // JVMTI PopFrame support 1493 _popframe_condition = popframe_inactive; 1494 _popframe_preserved_args = NULL; 1495 _popframe_preserved_args_size = 0; 1496 _frames_to_pop_failed_realloc = 0; 1497 1498 pd_initialize(); 1499 } 1500 1501 #if INCLUDE_ALL_GCS 1502 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1503 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1504 #endif // INCLUDE_ALL_GCS 1505 1506 JavaThread::JavaThread(bool is_attaching_via_jni) : 1507 Thread() 1508 #if INCLUDE_ALL_GCS 1509 , _satb_mark_queue(&_satb_mark_queue_set), 1510 _dirty_card_queue(&_dirty_card_queue_set) 1511 #endif // INCLUDE_ALL_GCS 1512 { 1513 initialize(); 1514 if (is_attaching_via_jni) { 1515 _jni_attach_state = _attaching_via_jni; 1516 } else { 1517 _jni_attach_state = _not_attaching_via_jni; 1518 } 1519 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1520 } 1521 1522 bool JavaThread::reguard_stack(address cur_sp) { 1523 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1524 && _stack_guard_state != stack_guard_reserved_disabled) { 1525 return true; // Stack already guarded or guard pages not needed. 1526 } 1527 1528 if (register_stack_overflow()) { 1529 // For those architectures which have separate register and 1530 // memory stacks, we must check the register stack to see if 1531 // it has overflowed. 1532 return false; 1533 } 1534 1535 // Java code never executes within the yellow zone: the latter is only 1536 // there to provoke an exception during stack banging. If java code 1537 // is executing there, either StackShadowPages should be larger, or 1538 // some exception code in c1, c2 or the interpreter isn't unwinding 1539 // when it should. 1540 guarantee(cur_sp > stack_reserved_zone_base(), 1541 "not enough space to reguard - increase StackShadowPages"); 1542 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1543 enable_stack_yellow_reserved_zone(); 1544 if (reserved_stack_activation() != stack_base()) { 1545 set_reserved_stack_activation(stack_base()); 1546 } 1547 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1548 set_reserved_stack_activation(stack_base()); 1549 enable_stack_reserved_zone(); 1550 } 1551 return true; 1552 } 1553 1554 bool JavaThread::reguard_stack(void) { 1555 return reguard_stack(os::current_stack_pointer()); 1556 } 1557 1558 1559 void JavaThread::block_if_vm_exited() { 1560 if (_terminated == _vm_exited) { 1561 // _vm_exited is set at safepoint, and Threads_lock is never released 1562 // we will block here forever 1563 Threads_lock->lock_without_safepoint_check(); 1564 ShouldNotReachHere(); 1565 } 1566 } 1567 1568 1569 // Remove this ifdef when C1 is ported to the compiler interface. 1570 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1571 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1572 1573 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1574 Thread() 1575 #if INCLUDE_ALL_GCS 1576 , _satb_mark_queue(&_satb_mark_queue_set), 1577 _dirty_card_queue(&_dirty_card_queue_set) 1578 #endif // INCLUDE_ALL_GCS 1579 { 1580 initialize(); 1581 _jni_attach_state = _not_attaching_via_jni; 1582 set_entry_point(entry_point); 1583 // Create the native thread itself. 1584 // %note runtime_23 1585 os::ThreadType thr_type = os::java_thread; 1586 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1587 os::java_thread; 1588 os::create_thread(this, thr_type, stack_sz); 1589 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1590 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1591 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1592 // the exception consists of creating the exception object & initializing it, initialization 1593 // will leave the VM via a JavaCall and then all locks must be unlocked). 1594 // 1595 // The thread is still suspended when we reach here. Thread must be explicit started 1596 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1597 // by calling Threads:add. The reason why this is not done here, is because the thread 1598 // object must be fully initialized (take a look at JVM_Start) 1599 } 1600 1601 JavaThread::~JavaThread() { 1602 1603 // JSR166 -- return the parker to the free list 1604 Parker::Release(_parker); 1605 _parker = NULL; 1606 1607 // Free any remaining previous UnrollBlock 1608 vframeArray* old_array = vframe_array_last(); 1609 1610 if (old_array != NULL) { 1611 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1612 old_array->set_unroll_block(NULL); 1613 delete old_info; 1614 delete old_array; 1615 } 1616 1617 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1618 if (deferred != NULL) { 1619 // This can only happen if thread is destroyed before deoptimization occurs. 1620 assert(deferred->length() != 0, "empty array!"); 1621 do { 1622 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1623 deferred->remove_at(0); 1624 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1625 delete dlv; 1626 } while (deferred->length() != 0); 1627 delete deferred; 1628 } 1629 1630 // All Java related clean up happens in exit 1631 ThreadSafepointState::destroy(this); 1632 if (_thread_stat != NULL) delete _thread_stat; 1633 1634 #if INCLUDE_JVMCI 1635 if (JVMCICounterSize > 0) { 1636 if (jvmci_counters_include(this)) { 1637 for (int i = 0; i < JVMCICounterSize; i++) { 1638 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1639 } 1640 } 1641 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1642 } 1643 #endif // INCLUDE_JVMCI 1644 } 1645 1646 1647 // The first routine called by a new Java thread 1648 void JavaThread::run() { 1649 // initialize thread-local alloc buffer related fields 1650 this->initialize_tlab(); 1651 1652 // used to test validity of stack trace backs 1653 this->record_base_of_stack_pointer(); 1654 1655 // Record real stack base and size. 1656 this->record_stack_base_and_size(); 1657 1658 this->create_stack_guard_pages(); 1659 1660 this->cache_global_variables(); 1661 1662 // Thread is now sufficient initialized to be handled by the safepoint code as being 1663 // in the VM. Change thread state from _thread_new to _thread_in_vm 1664 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1665 1666 assert(JavaThread::current() == this, "sanity check"); 1667 assert(!Thread::current()->owns_locks(), "sanity check"); 1668 1669 DTRACE_THREAD_PROBE(start, this); 1670 1671 // This operation might block. We call that after all safepoint checks for a new thread has 1672 // been completed. 1673 this->set_active_handles(JNIHandleBlock::allocate_block()); 1674 1675 if (JvmtiExport::should_post_thread_life()) { 1676 JvmtiExport::post_thread_start(this); 1677 } 1678 1679 EventThreadStart event; 1680 if (event.should_commit()) { 1681 event.set_thread(THREAD_TRACE_ID(this)); 1682 event.commit(); 1683 } 1684 1685 // We call another function to do the rest so we are sure that the stack addresses used 1686 // from there will be lower than the stack base just computed 1687 thread_main_inner(); 1688 1689 // Note, thread is no longer valid at this point! 1690 } 1691 1692 1693 void JavaThread::thread_main_inner() { 1694 assert(JavaThread::current() == this, "sanity check"); 1695 assert(this->threadObj() != NULL, "just checking"); 1696 1697 // Execute thread entry point unless this thread has a pending exception 1698 // or has been stopped before starting. 1699 // Note: Due to JVM_StopThread we can have pending exceptions already! 1700 if (!this->has_pending_exception() && 1701 !java_lang_Thread::is_stillborn(this->threadObj())) { 1702 { 1703 ResourceMark rm(this); 1704 this->set_native_thread_name(this->get_thread_name()); 1705 } 1706 HandleMark hm(this); 1707 this->entry_point()(this, this); 1708 } 1709 1710 DTRACE_THREAD_PROBE(stop, this); 1711 1712 this->exit(false); 1713 delete this; 1714 } 1715 1716 1717 static void ensure_join(JavaThread* thread) { 1718 // We do not need to grap the Threads_lock, since we are operating on ourself. 1719 Handle threadObj(thread, thread->threadObj()); 1720 assert(threadObj.not_null(), "java thread object must exist"); 1721 ObjectLocker lock(threadObj, thread); 1722 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1723 thread->clear_pending_exception(); 1724 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1725 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1726 // Clear the native thread instance - this makes isAlive return false and allows the join() 1727 // to complete once we've done the notify_all below 1728 java_lang_Thread::set_thread(threadObj(), NULL); 1729 lock.notify_all(thread); 1730 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1731 thread->clear_pending_exception(); 1732 } 1733 1734 1735 // For any new cleanup additions, please check to see if they need to be applied to 1736 // cleanup_failed_attach_current_thread as well. 1737 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1738 assert(this == JavaThread::current(), "thread consistency check"); 1739 1740 HandleMark hm(this); 1741 Handle uncaught_exception(this, this->pending_exception()); 1742 this->clear_pending_exception(); 1743 Handle threadObj(this, this->threadObj()); 1744 assert(threadObj.not_null(), "Java thread object should be created"); 1745 1746 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1747 { 1748 EXCEPTION_MARK; 1749 1750 CLEAR_PENDING_EXCEPTION; 1751 } 1752 if (!destroy_vm) { 1753 if (uncaught_exception.not_null()) { 1754 EXCEPTION_MARK; 1755 // Call method Thread.dispatchUncaughtException(). 1756 Klass* thread_klass = SystemDictionary::Thread_klass(); 1757 JavaValue result(T_VOID); 1758 JavaCalls::call_virtual(&result, 1759 threadObj, thread_klass, 1760 vmSymbols::dispatchUncaughtException_name(), 1761 vmSymbols::throwable_void_signature(), 1762 uncaught_exception, 1763 THREAD); 1764 if (HAS_PENDING_EXCEPTION) { 1765 ResourceMark rm(this); 1766 jio_fprintf(defaultStream::error_stream(), 1767 "\nException: %s thrown from the UncaughtExceptionHandler" 1768 " in thread \"%s\"\n", 1769 pending_exception()->klass()->external_name(), 1770 get_thread_name()); 1771 CLEAR_PENDING_EXCEPTION; 1772 } 1773 } 1774 1775 // Called before the java thread exit since we want to read info 1776 // from java_lang_Thread object 1777 EventThreadEnd event; 1778 if (event.should_commit()) { 1779 event.set_thread(THREAD_TRACE_ID(this)); 1780 event.commit(); 1781 } 1782 1783 // Call after last event on thread 1784 EVENT_THREAD_EXIT(this); 1785 1786 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1787 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1788 // is deprecated anyhow. 1789 if (!is_Compiler_thread()) { 1790 int count = 3; 1791 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1792 EXCEPTION_MARK; 1793 JavaValue result(T_VOID); 1794 Klass* thread_klass = SystemDictionary::Thread_klass(); 1795 JavaCalls::call_virtual(&result, 1796 threadObj, thread_klass, 1797 vmSymbols::exit_method_name(), 1798 vmSymbols::void_method_signature(), 1799 THREAD); 1800 CLEAR_PENDING_EXCEPTION; 1801 } 1802 } 1803 // notify JVMTI 1804 if (JvmtiExport::should_post_thread_life()) { 1805 JvmtiExport::post_thread_end(this); 1806 } 1807 1808 // We have notified the agents that we are exiting, before we go on, 1809 // we must check for a pending external suspend request and honor it 1810 // in order to not surprise the thread that made the suspend request. 1811 while (true) { 1812 { 1813 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1814 if (!is_external_suspend()) { 1815 set_terminated(_thread_exiting); 1816 ThreadService::current_thread_exiting(this); 1817 break; 1818 } 1819 // Implied else: 1820 // Things get a little tricky here. We have a pending external 1821 // suspend request, but we are holding the SR_lock so we 1822 // can't just self-suspend. So we temporarily drop the lock 1823 // and then self-suspend. 1824 } 1825 1826 ThreadBlockInVM tbivm(this); 1827 java_suspend_self(); 1828 1829 // We're done with this suspend request, but we have to loop around 1830 // and check again. Eventually we will get SR_lock without a pending 1831 // external suspend request and will be able to mark ourselves as 1832 // exiting. 1833 } 1834 // no more external suspends are allowed at this point 1835 } else { 1836 // before_exit() has already posted JVMTI THREAD_END events 1837 } 1838 1839 // Notify waiters on thread object. This has to be done after exit() is called 1840 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1841 // group should have the destroyed bit set before waiters are notified). 1842 ensure_join(this); 1843 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1844 1845 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1846 // held by this thread must be released. The spec does not distinguish 1847 // between JNI-acquired and regular Java monitors. We can only see 1848 // regular Java monitors here if monitor enter-exit matching is broken. 1849 // 1850 // Optionally release any monitors for regular JavaThread exits. This 1851 // is provided as a work around for any bugs in monitor enter-exit 1852 // matching. This can be expensive so it is not enabled by default. 1853 // 1854 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1855 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1856 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1857 // Sanity check even though JNI DetachCurrentThread() would have 1858 // returned JNI_ERR if there was a Java frame. JavaThread exit 1859 // should be done executing Java code by the time we get here. 1860 assert(!this->has_last_Java_frame(), 1861 "should not have a Java frame when detaching or exiting"); 1862 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1863 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1864 } 1865 1866 // These things needs to be done while we are still a Java Thread. Make sure that thread 1867 // is in a consistent state, in case GC happens 1868 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1869 1870 if (active_handles() != NULL) { 1871 JNIHandleBlock* block = active_handles(); 1872 set_active_handles(NULL); 1873 JNIHandleBlock::release_block(block); 1874 } 1875 1876 if (free_handle_block() != NULL) { 1877 JNIHandleBlock* block = free_handle_block(); 1878 set_free_handle_block(NULL); 1879 JNIHandleBlock::release_block(block); 1880 } 1881 1882 // These have to be removed while this is still a valid thread. 1883 remove_stack_guard_pages(); 1884 1885 if (UseTLAB) { 1886 tlab().make_parsable(true); // retire TLAB 1887 } 1888 1889 if (JvmtiEnv::environments_might_exist()) { 1890 JvmtiExport::cleanup_thread(this); 1891 } 1892 1893 // We must flush any deferred card marks before removing a thread from 1894 // the list of active threads. 1895 Universe::heap()->flush_deferred_store_barrier(this); 1896 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1897 1898 #if INCLUDE_ALL_GCS 1899 // We must flush the G1-related buffers before removing a thread 1900 // from the list of active threads. We must do this after any deferred 1901 // card marks have been flushed (above) so that any entries that are 1902 // added to the thread's dirty card queue as a result are not lost. 1903 if (UseG1GC) { 1904 flush_barrier_queues(); 1905 } 1906 #endif // INCLUDE_ALL_GCS 1907 1908 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1909 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1910 os::current_thread_id()); 1911 1912 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1913 Threads::remove(this); 1914 } 1915 1916 #if INCLUDE_ALL_GCS 1917 // Flush G1-related queues. 1918 void JavaThread::flush_barrier_queues() { 1919 satb_mark_queue().flush(); 1920 dirty_card_queue().flush(); 1921 } 1922 1923 void JavaThread::initialize_queues() { 1924 assert(!SafepointSynchronize::is_at_safepoint(), 1925 "we should not be at a safepoint"); 1926 1927 SATBMarkQueue& satb_queue = satb_mark_queue(); 1928 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1929 // The SATB queue should have been constructed with its active 1930 // field set to false. 1931 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1932 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1933 // If we are creating the thread during a marking cycle, we should 1934 // set the active field of the SATB queue to true. 1935 if (satb_queue_set.is_active()) { 1936 satb_queue.set_active(true); 1937 } 1938 1939 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1940 // The dirty card queue should have been constructed with its 1941 // active field set to true. 1942 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1943 } 1944 #endif // INCLUDE_ALL_GCS 1945 1946 void JavaThread::cleanup_failed_attach_current_thread() { 1947 if (active_handles() != NULL) { 1948 JNIHandleBlock* block = active_handles(); 1949 set_active_handles(NULL); 1950 JNIHandleBlock::release_block(block); 1951 } 1952 1953 if (free_handle_block() != NULL) { 1954 JNIHandleBlock* block = free_handle_block(); 1955 set_free_handle_block(NULL); 1956 JNIHandleBlock::release_block(block); 1957 } 1958 1959 // These have to be removed while this is still a valid thread. 1960 remove_stack_guard_pages(); 1961 1962 if (UseTLAB) { 1963 tlab().make_parsable(true); // retire TLAB, if any 1964 } 1965 1966 #if INCLUDE_ALL_GCS 1967 if (UseG1GC) { 1968 flush_barrier_queues(); 1969 } 1970 #endif // INCLUDE_ALL_GCS 1971 1972 Threads::remove(this); 1973 delete this; 1974 } 1975 1976 1977 1978 1979 JavaThread* JavaThread::active() { 1980 Thread* thread = Thread::current(); 1981 if (thread->is_Java_thread()) { 1982 return (JavaThread*) thread; 1983 } else { 1984 assert(thread->is_VM_thread(), "this must be a vm thread"); 1985 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1986 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1987 assert(ret->is_Java_thread(), "must be a Java thread"); 1988 return ret; 1989 } 1990 } 1991 1992 bool JavaThread::is_lock_owned(address adr) const { 1993 if (Thread::is_lock_owned(adr)) return true; 1994 1995 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1996 if (chunk->contains(adr)) return true; 1997 } 1998 1999 return false; 2000 } 2001 2002 2003 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2004 chunk->set_next(monitor_chunks()); 2005 set_monitor_chunks(chunk); 2006 } 2007 2008 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2009 guarantee(monitor_chunks() != NULL, "must be non empty"); 2010 if (monitor_chunks() == chunk) { 2011 set_monitor_chunks(chunk->next()); 2012 } else { 2013 MonitorChunk* prev = monitor_chunks(); 2014 while (prev->next() != chunk) prev = prev->next(); 2015 prev->set_next(chunk->next()); 2016 } 2017 } 2018 2019 // JVM support. 2020 2021 // Note: this function shouldn't block if it's called in 2022 // _thread_in_native_trans state (such as from 2023 // check_special_condition_for_native_trans()). 2024 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2025 2026 if (has_last_Java_frame() && has_async_condition()) { 2027 // If we are at a polling page safepoint (not a poll return) 2028 // then we must defer async exception because live registers 2029 // will be clobbered by the exception path. Poll return is 2030 // ok because the call we a returning from already collides 2031 // with exception handling registers and so there is no issue. 2032 // (The exception handling path kills call result registers but 2033 // this is ok since the exception kills the result anyway). 2034 2035 if (is_at_poll_safepoint()) { 2036 // if the code we are returning to has deoptimized we must defer 2037 // the exception otherwise live registers get clobbered on the 2038 // exception path before deoptimization is able to retrieve them. 2039 // 2040 RegisterMap map(this, false); 2041 frame caller_fr = last_frame().sender(&map); 2042 assert(caller_fr.is_compiled_frame(), "what?"); 2043 if (caller_fr.is_deoptimized_frame()) { 2044 log_info(exceptions)("deferred async exception at compiled safepoint"); 2045 return; 2046 } 2047 } 2048 } 2049 2050 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2051 if (condition == _no_async_condition) { 2052 // Conditions have changed since has_special_runtime_exit_condition() 2053 // was called: 2054 // - if we were here only because of an external suspend request, 2055 // then that was taken care of above (or cancelled) so we are done 2056 // - if we were here because of another async request, then it has 2057 // been cleared between the has_special_runtime_exit_condition() 2058 // and now so again we are done 2059 return; 2060 } 2061 2062 // Check for pending async. exception 2063 if (_pending_async_exception != NULL) { 2064 // Only overwrite an already pending exception, if it is not a threadDeath. 2065 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2066 2067 // We cannot call Exceptions::_throw(...) here because we cannot block 2068 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2069 2070 LogTarget(Info, exceptions) lt; 2071 if (lt.is_enabled()) { 2072 ResourceMark rm; 2073 LogStream ls(lt); 2074 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2075 if (has_last_Java_frame()) { 2076 frame f = last_frame(); 2077 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2078 } 2079 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2080 } 2081 _pending_async_exception = NULL; 2082 clear_has_async_exception(); 2083 } 2084 } 2085 2086 if (check_unsafe_error && 2087 condition == _async_unsafe_access_error && !has_pending_exception()) { 2088 condition = _no_async_condition; // done 2089 switch (thread_state()) { 2090 case _thread_in_vm: { 2091 JavaThread* THREAD = this; 2092 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2093 } 2094 case _thread_in_native: { 2095 ThreadInVMfromNative tiv(this); 2096 JavaThread* THREAD = this; 2097 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2098 } 2099 case _thread_in_Java: { 2100 ThreadInVMfromJava tiv(this); 2101 JavaThread* THREAD = this; 2102 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2103 } 2104 default: 2105 ShouldNotReachHere(); 2106 } 2107 } 2108 2109 assert(condition == _no_async_condition || has_pending_exception() || 2110 (!check_unsafe_error && condition == _async_unsafe_access_error), 2111 "must have handled the async condition, if no exception"); 2112 } 2113 2114 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2115 // 2116 // Check for pending external suspend. Internal suspend requests do 2117 // not use handle_special_runtime_exit_condition(). 2118 // If JNIEnv proxies are allowed, don't self-suspend if the target 2119 // thread is not the current thread. In older versions of jdbx, jdbx 2120 // threads could call into the VM with another thread's JNIEnv so we 2121 // can be here operating on behalf of a suspended thread (4432884). 2122 bool do_self_suspend = is_external_suspend_with_lock(); 2123 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2124 // 2125 // Because thread is external suspended the safepoint code will count 2126 // thread as at a safepoint. This can be odd because we can be here 2127 // as _thread_in_Java which would normally transition to _thread_blocked 2128 // at a safepoint. We would like to mark the thread as _thread_blocked 2129 // before calling java_suspend_self like all other callers of it but 2130 // we must then observe proper safepoint protocol. (We can't leave 2131 // _thread_blocked with a safepoint in progress). However we can be 2132 // here as _thread_in_native_trans so we can't use a normal transition 2133 // constructor/destructor pair because they assert on that type of 2134 // transition. We could do something like: 2135 // 2136 // JavaThreadState state = thread_state(); 2137 // set_thread_state(_thread_in_vm); 2138 // { 2139 // ThreadBlockInVM tbivm(this); 2140 // java_suspend_self() 2141 // } 2142 // set_thread_state(_thread_in_vm_trans); 2143 // if (safepoint) block; 2144 // set_thread_state(state); 2145 // 2146 // but that is pretty messy. Instead we just go with the way the 2147 // code has worked before and note that this is the only path to 2148 // java_suspend_self that doesn't put the thread in _thread_blocked 2149 // mode. 2150 2151 frame_anchor()->make_walkable(this); 2152 java_suspend_self(); 2153 2154 // We might be here for reasons in addition to the self-suspend request 2155 // so check for other async requests. 2156 } 2157 2158 if (check_asyncs) { 2159 check_and_handle_async_exceptions(); 2160 } 2161 #if INCLUDE_TRACE 2162 if (is_trace_suspend()) { 2163 TRACE_SUSPEND_THREAD(this); 2164 } 2165 #endif 2166 } 2167 2168 void JavaThread::send_thread_stop(oop java_throwable) { 2169 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2170 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2171 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2172 2173 // Do not throw asynchronous exceptions against the compiler thread 2174 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2175 if (!can_call_java()) return; 2176 2177 { 2178 // Actually throw the Throwable against the target Thread - however 2179 // only if there is no thread death exception installed already. 2180 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2181 // If the topmost frame is a runtime stub, then we are calling into 2182 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2183 // must deoptimize the caller before continuing, as the compiled exception handler table 2184 // may not be valid 2185 if (has_last_Java_frame()) { 2186 frame f = last_frame(); 2187 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2188 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2189 RegisterMap reg_map(this, UseBiasedLocking); 2190 frame compiled_frame = f.sender(®_map); 2191 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2192 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2193 } 2194 } 2195 } 2196 2197 // Set async. pending exception in thread. 2198 set_pending_async_exception(java_throwable); 2199 2200 if (log_is_enabled(Info, exceptions)) { 2201 ResourceMark rm; 2202 log_info(exceptions)("Pending Async. exception installed of type: %s", 2203 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2204 } 2205 // for AbortVMOnException flag 2206 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2207 } 2208 } 2209 2210 2211 // Interrupt thread so it will wake up from a potential wait() 2212 Thread::interrupt(this); 2213 } 2214 2215 // External suspension mechanism. 2216 // 2217 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2218 // to any VM_locks and it is at a transition 2219 // Self-suspension will happen on the transition out of the vm. 2220 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2221 // 2222 // Guarantees on return: 2223 // + Target thread will not execute any new bytecode (that's why we need to 2224 // force a safepoint) 2225 // + Target thread will not enter any new monitors 2226 // 2227 void JavaThread::java_suspend() { 2228 { MutexLocker mu(Threads_lock); 2229 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2230 return; 2231 } 2232 } 2233 2234 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2235 if (!is_external_suspend()) { 2236 // a racing resume has cancelled us; bail out now 2237 return; 2238 } 2239 2240 // suspend is done 2241 uint32_t debug_bits = 0; 2242 // Warning: is_ext_suspend_completed() may temporarily drop the 2243 // SR_lock to allow the thread to reach a stable thread state if 2244 // it is currently in a transient thread state. 2245 if (is_ext_suspend_completed(false /* !called_by_wait */, 2246 SuspendRetryDelay, &debug_bits)) { 2247 return; 2248 } 2249 } 2250 2251 VM_ThreadSuspend vm_suspend; 2252 VMThread::execute(&vm_suspend); 2253 } 2254 2255 // Part II of external suspension. 2256 // A JavaThread self suspends when it detects a pending external suspend 2257 // request. This is usually on transitions. It is also done in places 2258 // where continuing to the next transition would surprise the caller, 2259 // e.g., monitor entry. 2260 // 2261 // Returns the number of times that the thread self-suspended. 2262 // 2263 // Note: DO NOT call java_suspend_self() when you just want to block current 2264 // thread. java_suspend_self() is the second stage of cooperative 2265 // suspension for external suspend requests and should only be used 2266 // to complete an external suspend request. 2267 // 2268 int JavaThread::java_suspend_self() { 2269 int ret = 0; 2270 2271 // we are in the process of exiting so don't suspend 2272 if (is_exiting()) { 2273 clear_external_suspend(); 2274 return ret; 2275 } 2276 2277 assert(_anchor.walkable() || 2278 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2279 "must have walkable stack"); 2280 2281 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2282 2283 assert(!this->is_ext_suspended(), 2284 "a thread trying to self-suspend should not already be suspended"); 2285 2286 if (this->is_suspend_equivalent()) { 2287 // If we are self-suspending as a result of the lifting of a 2288 // suspend equivalent condition, then the suspend_equivalent 2289 // flag is not cleared until we set the ext_suspended flag so 2290 // that wait_for_ext_suspend_completion() returns consistent 2291 // results. 2292 this->clear_suspend_equivalent(); 2293 } 2294 2295 // A racing resume may have cancelled us before we grabbed SR_lock 2296 // above. Or another external suspend request could be waiting for us 2297 // by the time we return from SR_lock()->wait(). The thread 2298 // that requested the suspension may already be trying to walk our 2299 // stack and if we return now, we can change the stack out from under 2300 // it. This would be a "bad thing (TM)" and cause the stack walker 2301 // to crash. We stay self-suspended until there are no more pending 2302 // external suspend requests. 2303 while (is_external_suspend()) { 2304 ret++; 2305 this->set_ext_suspended(); 2306 2307 // _ext_suspended flag is cleared by java_resume() 2308 while (is_ext_suspended()) { 2309 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2310 } 2311 } 2312 2313 return ret; 2314 } 2315 2316 #ifdef ASSERT 2317 // verify the JavaThread has not yet been published in the Threads::list, and 2318 // hence doesn't need protection from concurrent access at this stage 2319 void JavaThread::verify_not_published() { 2320 if (!Threads_lock->owned_by_self()) { 2321 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2322 assert(!Threads::includes(this), 2323 "java thread shouldn't have been published yet!"); 2324 } else { 2325 assert(!Threads::includes(this), 2326 "java thread shouldn't have been published yet!"); 2327 } 2328 } 2329 #endif 2330 2331 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2332 // progress or when _suspend_flags is non-zero. 2333 // Current thread needs to self-suspend if there is a suspend request and/or 2334 // block if a safepoint is in progress. 2335 // Async exception ISN'T checked. 2336 // Note only the ThreadInVMfromNative transition can call this function 2337 // directly and when thread state is _thread_in_native_trans 2338 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2339 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2340 2341 JavaThread *curJT = JavaThread::current(); 2342 bool do_self_suspend = thread->is_external_suspend(); 2343 2344 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2345 2346 // If JNIEnv proxies are allowed, don't self-suspend if the target 2347 // thread is not the current thread. In older versions of jdbx, jdbx 2348 // threads could call into the VM with another thread's JNIEnv so we 2349 // can be here operating on behalf of a suspended thread (4432884). 2350 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2351 JavaThreadState state = thread->thread_state(); 2352 2353 // We mark this thread_blocked state as a suspend-equivalent so 2354 // that a caller to is_ext_suspend_completed() won't be confused. 2355 // The suspend-equivalent state is cleared by java_suspend_self(). 2356 thread->set_suspend_equivalent(); 2357 2358 // If the safepoint code sees the _thread_in_native_trans state, it will 2359 // wait until the thread changes to other thread state. There is no 2360 // guarantee on how soon we can obtain the SR_lock and complete the 2361 // self-suspend request. It would be a bad idea to let safepoint wait for 2362 // too long. Temporarily change the state to _thread_blocked to 2363 // let the VM thread know that this thread is ready for GC. The problem 2364 // of changing thread state is that safepoint could happen just after 2365 // java_suspend_self() returns after being resumed, and VM thread will 2366 // see the _thread_blocked state. We must check for safepoint 2367 // after restoring the state and make sure we won't leave while a safepoint 2368 // is in progress. 2369 thread->set_thread_state(_thread_blocked); 2370 thread->java_suspend_self(); 2371 thread->set_thread_state(state); 2372 2373 InterfaceSupport::serialize_thread_state_with_handler(thread); 2374 } 2375 2376 SafepointMechanism::block_if_requested(curJT); 2377 2378 if (thread->is_deopt_suspend()) { 2379 thread->clear_deopt_suspend(); 2380 RegisterMap map(thread, false); 2381 frame f = thread->last_frame(); 2382 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2383 f = f.sender(&map); 2384 } 2385 if (f.id() == thread->must_deopt_id()) { 2386 thread->clear_must_deopt_id(); 2387 f.deoptimize(thread); 2388 } else { 2389 fatal("missed deoptimization!"); 2390 } 2391 } 2392 #if INCLUDE_TRACE 2393 if (thread->is_trace_suspend()) { 2394 TRACE_SUSPEND_THREAD(thread); 2395 } 2396 #endif 2397 } 2398 2399 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2400 // progress or when _suspend_flags is non-zero. 2401 // Current thread needs to self-suspend if there is a suspend request and/or 2402 // block if a safepoint is in progress. 2403 // Also check for pending async exception (not including unsafe access error). 2404 // Note only the native==>VM/Java barriers can call this function and when 2405 // thread state is _thread_in_native_trans. 2406 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2407 check_safepoint_and_suspend_for_native_trans(thread); 2408 2409 if (thread->has_async_exception()) { 2410 // We are in _thread_in_native_trans state, don't handle unsafe 2411 // access error since that may block. 2412 thread->check_and_handle_async_exceptions(false); 2413 } 2414 } 2415 2416 // This is a variant of the normal 2417 // check_special_condition_for_native_trans with slightly different 2418 // semantics for use by critical native wrappers. It does all the 2419 // normal checks but also performs the transition back into 2420 // thread_in_Java state. This is required so that critical natives 2421 // can potentially block and perform a GC if they are the last thread 2422 // exiting the GCLocker. 2423 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2424 check_special_condition_for_native_trans(thread); 2425 2426 // Finish the transition 2427 thread->set_thread_state(_thread_in_Java); 2428 2429 if (thread->do_critical_native_unlock()) { 2430 ThreadInVMfromJavaNoAsyncException tiv(thread); 2431 GCLocker::unlock_critical(thread); 2432 thread->clear_critical_native_unlock(); 2433 } 2434 } 2435 2436 // We need to guarantee the Threads_lock here, since resumes are not 2437 // allowed during safepoint synchronization 2438 // Can only resume from an external suspension 2439 void JavaThread::java_resume() { 2440 assert_locked_or_safepoint(Threads_lock); 2441 2442 // Sanity check: thread is gone, has started exiting or the thread 2443 // was not externally suspended. 2444 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2445 return; 2446 } 2447 2448 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2449 2450 clear_external_suspend(); 2451 2452 if (is_ext_suspended()) { 2453 clear_ext_suspended(); 2454 SR_lock()->notify_all(); 2455 } 2456 } 2457 2458 size_t JavaThread::_stack_red_zone_size = 0; 2459 size_t JavaThread::_stack_yellow_zone_size = 0; 2460 size_t JavaThread::_stack_reserved_zone_size = 0; 2461 size_t JavaThread::_stack_shadow_zone_size = 0; 2462 2463 void JavaThread::create_stack_guard_pages() { 2464 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2465 address low_addr = stack_end(); 2466 size_t len = stack_guard_zone_size(); 2467 2468 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2469 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2470 2471 int must_commit = os::must_commit_stack_guard_pages(); 2472 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2473 2474 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2475 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2476 return; 2477 } 2478 2479 if (os::guard_memory((char *) low_addr, len)) { 2480 _stack_guard_state = stack_guard_enabled; 2481 } else { 2482 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2483 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2484 if (os::uncommit_memory((char *) low_addr, len)) { 2485 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2486 } 2487 return; 2488 } 2489 2490 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2491 PTR_FORMAT "-" PTR_FORMAT ".", 2492 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2493 } 2494 2495 void JavaThread::remove_stack_guard_pages() { 2496 assert(Thread::current() == this, "from different thread"); 2497 if (_stack_guard_state == stack_guard_unused) return; 2498 address low_addr = stack_end(); 2499 size_t len = stack_guard_zone_size(); 2500 2501 if (os::must_commit_stack_guard_pages()) { 2502 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2503 _stack_guard_state = stack_guard_unused; 2504 } else { 2505 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2506 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2507 return; 2508 } 2509 } else { 2510 if (_stack_guard_state == stack_guard_unused) return; 2511 if (os::unguard_memory((char *) low_addr, len)) { 2512 _stack_guard_state = stack_guard_unused; 2513 } else { 2514 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2515 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2516 return; 2517 } 2518 } 2519 2520 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2521 PTR_FORMAT "-" PTR_FORMAT ".", 2522 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2523 } 2524 2525 void JavaThread::enable_stack_reserved_zone() { 2526 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2527 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2528 2529 // The base notation is from the stack's point of view, growing downward. 2530 // We need to adjust it to work correctly with guard_memory() 2531 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2532 2533 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2534 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2535 2536 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2537 _stack_guard_state = stack_guard_enabled; 2538 } else { 2539 warning("Attempt to guard stack reserved zone failed."); 2540 } 2541 enable_register_stack_guard(); 2542 } 2543 2544 void JavaThread::disable_stack_reserved_zone() { 2545 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2546 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2547 2548 // Simply return if called for a thread that does not use guard pages. 2549 if (_stack_guard_state == stack_guard_unused) return; 2550 2551 // The base notation is from the stack's point of view, growing downward. 2552 // We need to adjust it to work correctly with guard_memory() 2553 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2554 2555 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2556 _stack_guard_state = stack_guard_reserved_disabled; 2557 } else { 2558 warning("Attempt to unguard stack reserved zone failed."); 2559 } 2560 disable_register_stack_guard(); 2561 } 2562 2563 void JavaThread::enable_stack_yellow_reserved_zone() { 2564 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2565 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2566 2567 // The base notation is from the stacks point of view, growing downward. 2568 // We need to adjust it to work correctly with guard_memory() 2569 address base = stack_red_zone_base(); 2570 2571 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2572 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2573 2574 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2575 _stack_guard_state = stack_guard_enabled; 2576 } else { 2577 warning("Attempt to guard stack yellow zone failed."); 2578 } 2579 enable_register_stack_guard(); 2580 } 2581 2582 void JavaThread::disable_stack_yellow_reserved_zone() { 2583 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2584 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2585 2586 // Simply return if called for a thread that does not use guard pages. 2587 if (_stack_guard_state == stack_guard_unused) return; 2588 2589 // The base notation is from the stacks point of view, growing downward. 2590 // We need to adjust it to work correctly with guard_memory() 2591 address base = stack_red_zone_base(); 2592 2593 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2594 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2595 } else { 2596 warning("Attempt to unguard stack yellow zone failed."); 2597 } 2598 disable_register_stack_guard(); 2599 } 2600 2601 void JavaThread::enable_stack_red_zone() { 2602 // The base notation is from the stacks point of view, growing downward. 2603 // We need to adjust it to work correctly with guard_memory() 2604 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2605 address base = stack_red_zone_base() - stack_red_zone_size(); 2606 2607 guarantee(base < stack_base(), "Error calculating stack red zone"); 2608 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2609 2610 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2611 warning("Attempt to guard stack red zone failed."); 2612 } 2613 } 2614 2615 void JavaThread::disable_stack_red_zone() { 2616 // The base notation is from the stacks point of view, growing downward. 2617 // We need to adjust it to work correctly with guard_memory() 2618 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2619 address base = stack_red_zone_base() - stack_red_zone_size(); 2620 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2621 warning("Attempt to unguard stack red zone failed."); 2622 } 2623 } 2624 2625 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2626 // ignore is there is no stack 2627 if (!has_last_Java_frame()) return; 2628 // traverse the stack frames. Starts from top frame. 2629 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2630 frame* fr = fst.current(); 2631 f(fr, fst.register_map()); 2632 } 2633 } 2634 2635 2636 #ifndef PRODUCT 2637 // Deoptimization 2638 // Function for testing deoptimization 2639 void JavaThread::deoptimize() { 2640 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2641 StackFrameStream fst(this, UseBiasedLocking); 2642 bool deopt = false; // Dump stack only if a deopt actually happens. 2643 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2644 // Iterate over all frames in the thread and deoptimize 2645 for (; !fst.is_done(); fst.next()) { 2646 if (fst.current()->can_be_deoptimized()) { 2647 2648 if (only_at) { 2649 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2650 // consists of comma or carriage return separated numbers so 2651 // search for the current bci in that string. 2652 address pc = fst.current()->pc(); 2653 nmethod* nm = (nmethod*) fst.current()->cb(); 2654 ScopeDesc* sd = nm->scope_desc_at(pc); 2655 char buffer[8]; 2656 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2657 size_t len = strlen(buffer); 2658 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2659 while (found != NULL) { 2660 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2661 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2662 // Check that the bci found is bracketed by terminators. 2663 break; 2664 } 2665 found = strstr(found + 1, buffer); 2666 } 2667 if (!found) { 2668 continue; 2669 } 2670 } 2671 2672 if (DebugDeoptimization && !deopt) { 2673 deopt = true; // One-time only print before deopt 2674 tty->print_cr("[BEFORE Deoptimization]"); 2675 trace_frames(); 2676 trace_stack(); 2677 } 2678 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2679 } 2680 } 2681 2682 if (DebugDeoptimization && deopt) { 2683 tty->print_cr("[AFTER Deoptimization]"); 2684 trace_frames(); 2685 } 2686 } 2687 2688 2689 // Make zombies 2690 void JavaThread::make_zombies() { 2691 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2692 if (fst.current()->can_be_deoptimized()) { 2693 // it is a Java nmethod 2694 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2695 nm->make_not_entrant(); 2696 } 2697 } 2698 } 2699 #endif // PRODUCT 2700 2701 2702 void JavaThread::deoptimized_wrt_marked_nmethods() { 2703 if (!has_last_Java_frame()) return; 2704 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2705 StackFrameStream fst(this, UseBiasedLocking); 2706 for (; !fst.is_done(); fst.next()) { 2707 if (fst.current()->should_be_deoptimized()) { 2708 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2709 } 2710 } 2711 } 2712 2713 2714 // If the caller is a NamedThread, then remember, in the current scope, 2715 // the given JavaThread in its _processed_thread field. 2716 class RememberProcessedThread: public StackObj { 2717 NamedThread* _cur_thr; 2718 public: 2719 RememberProcessedThread(JavaThread* jthr) { 2720 Thread* thread = Thread::current(); 2721 if (thread->is_Named_thread()) { 2722 _cur_thr = (NamedThread *)thread; 2723 _cur_thr->set_processed_thread(jthr); 2724 } else { 2725 _cur_thr = NULL; 2726 } 2727 } 2728 2729 ~RememberProcessedThread() { 2730 if (_cur_thr) { 2731 _cur_thr->set_processed_thread(NULL); 2732 } 2733 } 2734 }; 2735 2736 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2737 // Verify that the deferred card marks have been flushed. 2738 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2739 2740 // Traverse the GCHandles 2741 Thread::oops_do(f, cf); 2742 2743 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2744 2745 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2746 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2747 2748 if (has_last_Java_frame()) { 2749 // Record JavaThread to GC thread 2750 RememberProcessedThread rpt(this); 2751 2752 // Traverse the privileged stack 2753 if (_privileged_stack_top != NULL) { 2754 _privileged_stack_top->oops_do(f); 2755 } 2756 2757 // traverse the registered growable array 2758 if (_array_for_gc != NULL) { 2759 for (int index = 0; index < _array_for_gc->length(); index++) { 2760 f->do_oop(_array_for_gc->adr_at(index)); 2761 } 2762 } 2763 2764 // Traverse the monitor chunks 2765 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2766 chunk->oops_do(f); 2767 } 2768 2769 // Traverse the execution stack 2770 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2771 fst.current()->oops_do(f, cf, fst.register_map()); 2772 } 2773 } 2774 2775 // callee_target is never live across a gc point so NULL it here should 2776 // it still contain a methdOop. 2777 2778 set_callee_target(NULL); 2779 2780 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2781 // If we have deferred set_locals there might be oops waiting to be 2782 // written 2783 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2784 if (list != NULL) { 2785 for (int i = 0; i < list->length(); i++) { 2786 list->at(i)->oops_do(f); 2787 } 2788 } 2789 2790 // Traverse instance variables at the end since the GC may be moving things 2791 // around using this function 2792 f->do_oop((oop*) &_threadObj); 2793 f->do_oop((oop*) &_vm_result); 2794 f->do_oop((oop*) &_exception_oop); 2795 f->do_oop((oop*) &_pending_async_exception); 2796 2797 if (jvmti_thread_state() != NULL) { 2798 jvmti_thread_state()->oops_do(f); 2799 } 2800 } 2801 2802 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2803 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2804 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2805 2806 if (has_last_Java_frame()) { 2807 // Traverse the execution stack 2808 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2809 fst.current()->nmethods_do(cf); 2810 } 2811 } 2812 } 2813 2814 void JavaThread::metadata_do(void f(Metadata*)) { 2815 if (has_last_Java_frame()) { 2816 // Traverse the execution stack to call f() on the methods in the stack 2817 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2818 fst.current()->metadata_do(f); 2819 } 2820 } else if (is_Compiler_thread()) { 2821 // need to walk ciMetadata in current compile tasks to keep alive. 2822 CompilerThread* ct = (CompilerThread*)this; 2823 if (ct->env() != NULL) { 2824 ct->env()->metadata_do(f); 2825 } 2826 if (ct->task() != NULL) { 2827 ct->task()->metadata_do(f); 2828 } 2829 } 2830 } 2831 2832 // Printing 2833 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2834 switch (_thread_state) { 2835 case _thread_uninitialized: return "_thread_uninitialized"; 2836 case _thread_new: return "_thread_new"; 2837 case _thread_new_trans: return "_thread_new_trans"; 2838 case _thread_in_native: return "_thread_in_native"; 2839 case _thread_in_native_trans: return "_thread_in_native_trans"; 2840 case _thread_in_vm: return "_thread_in_vm"; 2841 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2842 case _thread_in_Java: return "_thread_in_Java"; 2843 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2844 case _thread_blocked: return "_thread_blocked"; 2845 case _thread_blocked_trans: return "_thread_blocked_trans"; 2846 default: return "unknown thread state"; 2847 } 2848 } 2849 2850 #ifndef PRODUCT 2851 void JavaThread::print_thread_state_on(outputStream *st) const { 2852 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2853 }; 2854 void JavaThread::print_thread_state() const { 2855 print_thread_state_on(tty); 2856 } 2857 #endif // PRODUCT 2858 2859 // Called by Threads::print() for VM_PrintThreads operation 2860 void JavaThread::print_on(outputStream *st) const { 2861 st->print_raw("\""); 2862 st->print_raw(get_thread_name()); 2863 st->print_raw("\" "); 2864 oop thread_oop = threadObj(); 2865 if (thread_oop != NULL) { 2866 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2867 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2868 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2869 } 2870 Thread::print_on(st); 2871 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2872 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2873 if (thread_oop != NULL) { 2874 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2875 } 2876 #ifndef PRODUCT 2877 print_thread_state_on(st); 2878 _safepoint_state->print_on(st); 2879 #endif // PRODUCT 2880 if (is_Compiler_thread()) { 2881 CompilerThread* ct = (CompilerThread*)this; 2882 if (ct->task() != NULL) { 2883 st->print(" Compiling: "); 2884 ct->task()->print(st, NULL, true, false); 2885 } else { 2886 st->print(" No compile task"); 2887 } 2888 st->cr(); 2889 } 2890 } 2891 2892 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2893 st->print("%s", get_thread_name_string(buf, buflen)); 2894 } 2895 2896 // Called by fatal error handler. The difference between this and 2897 // JavaThread::print() is that we can't grab lock or allocate memory. 2898 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2899 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2900 oop thread_obj = threadObj(); 2901 if (thread_obj != NULL) { 2902 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2903 } 2904 st->print(" ["); 2905 st->print("%s", _get_thread_state_name(_thread_state)); 2906 if (osthread()) { 2907 st->print(", id=%d", osthread()->thread_id()); 2908 } 2909 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2910 p2i(stack_end()), p2i(stack_base())); 2911 st->print("]"); 2912 return; 2913 } 2914 2915 // Verification 2916 2917 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2918 2919 void JavaThread::verify() { 2920 // Verify oops in the thread. 2921 oops_do(&VerifyOopClosure::verify_oop, NULL); 2922 2923 // Verify the stack frames. 2924 frames_do(frame_verify); 2925 } 2926 2927 // CR 6300358 (sub-CR 2137150) 2928 // Most callers of this method assume that it can't return NULL but a 2929 // thread may not have a name whilst it is in the process of attaching to 2930 // the VM - see CR 6412693, and there are places where a JavaThread can be 2931 // seen prior to having it's threadObj set (eg JNI attaching threads and 2932 // if vm exit occurs during initialization). These cases can all be accounted 2933 // for such that this method never returns NULL. 2934 const char* JavaThread::get_thread_name() const { 2935 #ifdef ASSERT 2936 // early safepoints can hit while current thread does not yet have TLS 2937 if (!SafepointSynchronize::is_at_safepoint()) { 2938 Thread *cur = Thread::current(); 2939 if (!(cur->is_Java_thread() && cur == this)) { 2940 // Current JavaThreads are allowed to get their own name without 2941 // the Threads_lock. 2942 assert_locked_or_safepoint(Threads_lock); 2943 } 2944 } 2945 #endif // ASSERT 2946 return get_thread_name_string(); 2947 } 2948 2949 // Returns a non-NULL representation of this thread's name, or a suitable 2950 // descriptive string if there is no set name 2951 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2952 const char* name_str; 2953 oop thread_obj = threadObj(); 2954 if (thread_obj != NULL) { 2955 oop name = java_lang_Thread::name(thread_obj); 2956 if (name != NULL) { 2957 if (buf == NULL) { 2958 name_str = java_lang_String::as_utf8_string(name); 2959 } else { 2960 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2961 } 2962 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2963 name_str = "<no-name - thread is attaching>"; 2964 } else { 2965 name_str = Thread::name(); 2966 } 2967 } else { 2968 name_str = Thread::name(); 2969 } 2970 assert(name_str != NULL, "unexpected NULL thread name"); 2971 return name_str; 2972 } 2973 2974 2975 const char* JavaThread::get_threadgroup_name() const { 2976 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2977 oop thread_obj = threadObj(); 2978 if (thread_obj != NULL) { 2979 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2980 if (thread_group != NULL) { 2981 // ThreadGroup.name can be null 2982 return java_lang_ThreadGroup::name(thread_group); 2983 } 2984 } 2985 return NULL; 2986 } 2987 2988 const char* JavaThread::get_parent_name() const { 2989 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2990 oop thread_obj = threadObj(); 2991 if (thread_obj != NULL) { 2992 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2993 if (thread_group != NULL) { 2994 oop parent = java_lang_ThreadGroup::parent(thread_group); 2995 if (parent != NULL) { 2996 // ThreadGroup.name can be null 2997 return java_lang_ThreadGroup::name(parent); 2998 } 2999 } 3000 } 3001 return NULL; 3002 } 3003 3004 ThreadPriority JavaThread::java_priority() const { 3005 oop thr_oop = threadObj(); 3006 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3007 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3008 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3009 return priority; 3010 } 3011 3012 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3013 3014 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3015 // Link Java Thread object <-> C++ Thread 3016 3017 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3018 // and put it into a new Handle. The Handle "thread_oop" can then 3019 // be used to pass the C++ thread object to other methods. 3020 3021 // Set the Java level thread object (jthread) field of the 3022 // new thread (a JavaThread *) to C++ thread object using the 3023 // "thread_oop" handle. 3024 3025 // Set the thread field (a JavaThread *) of the 3026 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3027 3028 Handle thread_oop(Thread::current(), 3029 JNIHandles::resolve_non_null(jni_thread)); 3030 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3031 "must be initialized"); 3032 set_threadObj(thread_oop()); 3033 java_lang_Thread::set_thread(thread_oop(), this); 3034 3035 if (prio == NoPriority) { 3036 prio = java_lang_Thread::priority(thread_oop()); 3037 assert(prio != NoPriority, "A valid priority should be present"); 3038 } 3039 3040 // Push the Java priority down to the native thread; needs Threads_lock 3041 Thread::set_priority(this, prio); 3042 3043 prepare_ext(); 3044 3045 // Add the new thread to the Threads list and set it in motion. 3046 // We must have threads lock in order to call Threads::add. 3047 // It is crucial that we do not block before the thread is 3048 // added to the Threads list for if a GC happens, then the java_thread oop 3049 // will not be visited by GC. 3050 Threads::add(this); 3051 } 3052 3053 oop JavaThread::current_park_blocker() { 3054 // Support for JSR-166 locks 3055 oop thread_oop = threadObj(); 3056 if (thread_oop != NULL && 3057 JDK_Version::current().supports_thread_park_blocker()) { 3058 return java_lang_Thread::park_blocker(thread_oop); 3059 } 3060 return NULL; 3061 } 3062 3063 3064 void JavaThread::print_stack_on(outputStream* st) { 3065 if (!has_last_Java_frame()) return; 3066 ResourceMark rm; 3067 HandleMark hm; 3068 3069 RegisterMap reg_map(this); 3070 vframe* start_vf = last_java_vframe(®_map); 3071 int count = 0; 3072 for (vframe* f = start_vf; f; f = f->sender()) { 3073 if (f->is_java_frame()) { 3074 javaVFrame* jvf = javaVFrame::cast(f); 3075 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3076 3077 // Print out lock information 3078 if (JavaMonitorsInStackTrace) { 3079 jvf->print_lock_info_on(st, count); 3080 } 3081 } else { 3082 // Ignore non-Java frames 3083 } 3084 3085 // Bail-out case for too deep stacks 3086 count++; 3087 if (MaxJavaStackTraceDepth == count) return; 3088 } 3089 } 3090 3091 3092 // JVMTI PopFrame support 3093 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3094 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3095 if (in_bytes(size_in_bytes) != 0) { 3096 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3097 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3098 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3099 } 3100 } 3101 3102 void* JavaThread::popframe_preserved_args() { 3103 return _popframe_preserved_args; 3104 } 3105 3106 ByteSize JavaThread::popframe_preserved_args_size() { 3107 return in_ByteSize(_popframe_preserved_args_size); 3108 } 3109 3110 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3111 int sz = in_bytes(popframe_preserved_args_size()); 3112 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3113 return in_WordSize(sz / wordSize); 3114 } 3115 3116 void JavaThread::popframe_free_preserved_args() { 3117 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3118 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3119 _popframe_preserved_args = NULL; 3120 _popframe_preserved_args_size = 0; 3121 } 3122 3123 #ifndef PRODUCT 3124 3125 void JavaThread::trace_frames() { 3126 tty->print_cr("[Describe stack]"); 3127 int frame_no = 1; 3128 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3129 tty->print(" %d. ", frame_no++); 3130 fst.current()->print_value_on(tty, this); 3131 tty->cr(); 3132 } 3133 } 3134 3135 class PrintAndVerifyOopClosure: public OopClosure { 3136 protected: 3137 template <class T> inline void do_oop_work(T* p) { 3138 oop obj = oopDesc::load_decode_heap_oop(p); 3139 if (obj == NULL) return; 3140 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3141 if (oopDesc::is_oop_or_null(obj)) { 3142 if (obj->is_objArray()) { 3143 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3144 } else { 3145 obj->print(); 3146 } 3147 } else { 3148 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3149 } 3150 tty->cr(); 3151 } 3152 public: 3153 virtual void do_oop(oop* p) { do_oop_work(p); } 3154 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3155 }; 3156 3157 3158 static void oops_print(frame* f, const RegisterMap *map) { 3159 PrintAndVerifyOopClosure print; 3160 f->print_value(); 3161 f->oops_do(&print, NULL, (RegisterMap*)map); 3162 } 3163 3164 // Print our all the locations that contain oops and whether they are 3165 // valid or not. This useful when trying to find the oldest frame 3166 // where an oop has gone bad since the frame walk is from youngest to 3167 // oldest. 3168 void JavaThread::trace_oops() { 3169 tty->print_cr("[Trace oops]"); 3170 frames_do(oops_print); 3171 } 3172 3173 3174 #ifdef ASSERT 3175 // Print or validate the layout of stack frames 3176 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3177 ResourceMark rm; 3178 PRESERVE_EXCEPTION_MARK; 3179 FrameValues values; 3180 int frame_no = 0; 3181 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3182 fst.current()->describe(values, ++frame_no); 3183 if (depth == frame_no) break; 3184 } 3185 if (validate_only) { 3186 values.validate(); 3187 } else { 3188 tty->print_cr("[Describe stack layout]"); 3189 values.print(this); 3190 } 3191 } 3192 #endif 3193 3194 void JavaThread::trace_stack_from(vframe* start_vf) { 3195 ResourceMark rm; 3196 int vframe_no = 1; 3197 for (vframe* f = start_vf; f; f = f->sender()) { 3198 if (f->is_java_frame()) { 3199 javaVFrame::cast(f)->print_activation(vframe_no++); 3200 } else { 3201 f->print(); 3202 } 3203 if (vframe_no > StackPrintLimit) { 3204 tty->print_cr("...<more frames>..."); 3205 return; 3206 } 3207 } 3208 } 3209 3210 3211 void JavaThread::trace_stack() { 3212 if (!has_last_Java_frame()) return; 3213 ResourceMark rm; 3214 HandleMark hm; 3215 RegisterMap reg_map(this); 3216 trace_stack_from(last_java_vframe(®_map)); 3217 } 3218 3219 3220 #endif // PRODUCT 3221 3222 3223 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3224 assert(reg_map != NULL, "a map must be given"); 3225 frame f = last_frame(); 3226 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3227 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3228 } 3229 return NULL; 3230 } 3231 3232 3233 Klass* JavaThread::security_get_caller_class(int depth) { 3234 vframeStream vfst(this); 3235 vfst.security_get_caller_frame(depth); 3236 if (!vfst.at_end()) { 3237 return vfst.method()->method_holder(); 3238 } 3239 return NULL; 3240 } 3241 3242 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3243 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3244 CompileBroker::compiler_thread_loop(); 3245 } 3246 3247 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3248 NMethodSweeper::sweeper_loop(); 3249 } 3250 3251 // Create a CompilerThread 3252 CompilerThread::CompilerThread(CompileQueue* queue, 3253 CompilerCounters* counters) 3254 : JavaThread(&compiler_thread_entry) { 3255 _env = NULL; 3256 _log = NULL; 3257 _task = NULL; 3258 _queue = queue; 3259 _counters = counters; 3260 _buffer_blob = NULL; 3261 _compiler = NULL; 3262 3263 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3264 resource_area()->bias_to(mtCompiler); 3265 3266 #ifndef PRODUCT 3267 _ideal_graph_printer = NULL; 3268 #endif 3269 } 3270 3271 bool CompilerThread::can_call_java() const { 3272 return _compiler != NULL && _compiler->is_jvmci(); 3273 } 3274 3275 // Create sweeper thread 3276 CodeCacheSweeperThread::CodeCacheSweeperThread() 3277 : JavaThread(&sweeper_thread_entry) { 3278 _scanned_compiled_method = NULL; 3279 } 3280 3281 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3282 JavaThread::oops_do(f, cf); 3283 if (_scanned_compiled_method != NULL && cf != NULL) { 3284 // Safepoints can occur when the sweeper is scanning an nmethod so 3285 // process it here to make sure it isn't unloaded in the middle of 3286 // a scan. 3287 cf->do_code_blob(_scanned_compiled_method); 3288 } 3289 } 3290 3291 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3292 JavaThread::nmethods_do(cf); 3293 if (_scanned_compiled_method != NULL && cf != NULL) { 3294 // Safepoints can occur when the sweeper is scanning an nmethod so 3295 // process it here to make sure it isn't unloaded in the middle of 3296 // a scan. 3297 cf->do_code_blob(_scanned_compiled_method); 3298 } 3299 } 3300 3301 3302 // ======= Threads ======== 3303 3304 // The Threads class links together all active threads, and provides 3305 // operations over all threads. It is protected by its own Mutex 3306 // lock, which is also used in other contexts to protect thread 3307 // operations from having the thread being operated on from exiting 3308 // and going away unexpectedly (e.g., safepoint synchronization) 3309 3310 JavaThread* Threads::_thread_list = NULL; 3311 int Threads::_number_of_threads = 0; 3312 int Threads::_number_of_non_daemon_threads = 0; 3313 int Threads::_return_code = 0; 3314 int Threads::_thread_claim_parity = 0; 3315 size_t JavaThread::_stack_size_at_create = 0; 3316 #ifdef ASSERT 3317 bool Threads::_vm_complete = false; 3318 #endif 3319 3320 // All JavaThreads 3321 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3322 3323 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3324 void Threads::threads_do(ThreadClosure* tc) { 3325 assert_locked_or_safepoint(Threads_lock); 3326 // ALL_JAVA_THREADS iterates through all JavaThreads 3327 ALL_JAVA_THREADS(p) { 3328 tc->do_thread(p); 3329 } 3330 // Someday we could have a table or list of all non-JavaThreads. 3331 // For now, just manually iterate through them. 3332 tc->do_thread(VMThread::vm_thread()); 3333 Universe::heap()->gc_threads_do(tc); 3334 WatcherThread *wt = WatcherThread::watcher_thread(); 3335 // Strictly speaking, the following NULL check isn't sufficient to make sure 3336 // the data for WatcherThread is still valid upon being examined. However, 3337 // considering that WatchThread terminates when the VM is on the way to 3338 // exit at safepoint, the chance of the above is extremely small. The right 3339 // way to prevent termination of WatcherThread would be to acquire 3340 // Terminator_lock, but we can't do that without violating the lock rank 3341 // checking in some cases. 3342 if (wt != NULL) { 3343 tc->do_thread(wt); 3344 } 3345 3346 // If CompilerThreads ever become non-JavaThreads, add them here 3347 } 3348 3349 void Threads::parallel_java_threads_do(ThreadClosure* tc) { 3350 int cp = Threads::thread_claim_parity(); 3351 ALL_JAVA_THREADS(p) { 3352 if (p->claim_oops_do(true, cp)) { 3353 tc->do_thread(p); 3354 } 3355 } 3356 // Thread claiming protocol requires us to claim the same interesting 3357 // threads on all paths. Notably, Threads::possibly_parallel_threads_do 3358 // claims all Java threads *and* the VMThread. To avoid breaking the 3359 // claiming protocol, we have to claim VMThread on this path too, even 3360 // if we do not apply the closure to the VMThread. 3361 VMThread* vmt = VMThread::vm_thread(); 3362 (void)vmt->claim_oops_do(true, cp); 3363 } 3364 3365 // The system initialization in the library has three phases. 3366 // 3367 // Phase 1: java.lang.System class initialization 3368 // java.lang.System is a primordial class loaded and initialized 3369 // by the VM early during startup. java.lang.System.<clinit> 3370 // only does registerNatives and keeps the rest of the class 3371 // initialization work later until thread initialization completes. 3372 // 3373 // System.initPhase1 initializes the system properties, the static 3374 // fields in, out, and err. Set up java signal handlers, OS-specific 3375 // system settings, and thread group of the main thread. 3376 static void call_initPhase1(TRAPS) { 3377 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3378 JavaValue result(T_VOID); 3379 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3380 vmSymbols::void_method_signature(), CHECK); 3381 } 3382 3383 // Phase 2. Module system initialization 3384 // This will initialize the module system. Only java.base classes 3385 // can be loaded until phase 2 completes. 3386 // 3387 // Call System.initPhase2 after the compiler initialization and jsr292 3388 // classes get initialized because module initialization runs a lot of java 3389 // code, that for performance reasons, should be compiled. Also, this will 3390 // enable the startup code to use lambda and other language features in this 3391 // phase and onward. 3392 // 3393 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3394 static void call_initPhase2(TRAPS) { 3395 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3396 3397 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3398 3399 JavaValue result(T_INT); 3400 JavaCallArguments args; 3401 args.push_int(DisplayVMOutputToStderr); 3402 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3403 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3404 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3405 if (result.get_jint() != JNI_OK) { 3406 vm_exit_during_initialization(); // no message or exception 3407 } 3408 3409 universe_post_module_init(); 3410 } 3411 3412 // Phase 3. final setup - set security manager, system class loader and TCCL 3413 // 3414 // This will instantiate and set the security manager, set the system class 3415 // loader as well as the thread context class loader. The security manager 3416 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3417 // other modules or the application's classpath. 3418 static void call_initPhase3(TRAPS) { 3419 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3420 JavaValue result(T_VOID); 3421 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3422 vmSymbols::void_method_signature(), CHECK); 3423 } 3424 3425 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3426 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3427 3428 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3429 create_vm_init_libraries(); 3430 } 3431 3432 initialize_class(vmSymbols::java_lang_String(), CHECK); 3433 3434 // Inject CompactStrings value after the static initializers for String ran. 3435 java_lang_String::set_compact_strings(CompactStrings); 3436 3437 // Initialize java_lang.System (needed before creating the thread) 3438 initialize_class(vmSymbols::java_lang_System(), CHECK); 3439 // The VM creates & returns objects of this class. Make sure it's initialized. 3440 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3441 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3442 Handle thread_group = create_initial_thread_group(CHECK); 3443 Universe::set_main_thread_group(thread_group()); 3444 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3445 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3446 main_thread->set_threadObj(thread_object); 3447 // Set thread status to running since main thread has 3448 // been started and running. 3449 java_lang_Thread::set_thread_status(thread_object, 3450 java_lang_Thread::RUNNABLE); 3451 3452 // The VM creates objects of this class. 3453 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3454 3455 // The VM preresolves methods to these classes. Make sure that they get initialized 3456 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3457 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3458 3459 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3460 call_initPhase1(CHECK); 3461 3462 // get the Java runtime name after java.lang.System is initialized 3463 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3464 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3465 3466 // an instance of OutOfMemory exception has been allocated earlier 3467 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3468 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3469 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3470 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3471 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3472 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3473 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3474 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3475 } 3476 3477 void Threads::initialize_jsr292_core_classes(TRAPS) { 3478 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3479 3480 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3481 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3482 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3483 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3484 } 3485 3486 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3487 extern void JDK_Version_init(); 3488 3489 // Preinitialize version info. 3490 VM_Version::early_initialize(); 3491 3492 // Check version 3493 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3494 3495 // Initialize library-based TLS 3496 ThreadLocalStorage::init(); 3497 3498 // Initialize the output stream module 3499 ostream_init(); 3500 3501 // Process java launcher properties. 3502 Arguments::process_sun_java_launcher_properties(args); 3503 3504 // Initialize the os module 3505 os::init(); 3506 3507 // Record VM creation timing statistics 3508 TraceVmCreationTime create_vm_timer; 3509 create_vm_timer.start(); 3510 3511 // Initialize system properties. 3512 Arguments::init_system_properties(); 3513 3514 // So that JDK version can be used as a discriminator when parsing arguments 3515 JDK_Version_init(); 3516 3517 // Update/Initialize System properties after JDK version number is known 3518 Arguments::init_version_specific_system_properties(); 3519 3520 // Make sure to initialize log configuration *before* parsing arguments 3521 LogConfiguration::initialize(create_vm_timer.begin_time()); 3522 3523 // Parse arguments 3524 jint parse_result = Arguments::parse(args); 3525 if (parse_result != JNI_OK) return parse_result; 3526 3527 os::init_before_ergo(); 3528 3529 jint ergo_result = Arguments::apply_ergo(); 3530 if (ergo_result != JNI_OK) return ergo_result; 3531 3532 // Final check of all ranges after ergonomics which may change values. 3533 if (!CommandLineFlagRangeList::check_ranges()) { 3534 return JNI_EINVAL; 3535 } 3536 3537 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3538 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3539 if (!constraint_result) { 3540 return JNI_EINVAL; 3541 } 3542 3543 CommandLineFlagWriteableList::mark_startup(); 3544 3545 if (PauseAtStartup) { 3546 os::pause(); 3547 } 3548 3549 HOTSPOT_VM_INIT_BEGIN(); 3550 3551 // Timing (must come after argument parsing) 3552 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3553 3554 SafepointMechanism::initialize(); 3555 3556 // Initialize the os module after parsing the args 3557 jint os_init_2_result = os::init_2(); 3558 if (os_init_2_result != JNI_OK) return os_init_2_result; 3559 3560 jint adjust_after_os_result = Arguments::adjust_after_os(); 3561 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3562 3563 // Initialize output stream logging 3564 ostream_init_log(); 3565 3566 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3567 // Must be before create_vm_init_agents() 3568 if (Arguments::init_libraries_at_startup()) { 3569 convert_vm_init_libraries_to_agents(); 3570 } 3571 3572 // Launch -agentlib/-agentpath and converted -Xrun agents 3573 if (Arguments::init_agents_at_startup()) { 3574 create_vm_init_agents(); 3575 } 3576 3577 // Initialize Threads state 3578 _thread_list = NULL; 3579 _number_of_threads = 0; 3580 _number_of_non_daemon_threads = 0; 3581 3582 // Initialize global data structures and create system classes in heap 3583 vm_init_globals(); 3584 3585 #if INCLUDE_JVMCI 3586 if (JVMCICounterSize > 0) { 3587 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3588 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3589 } else { 3590 JavaThread::_jvmci_old_thread_counters = NULL; 3591 } 3592 #endif // INCLUDE_JVMCI 3593 3594 // Attach the main thread to this os thread 3595 JavaThread* main_thread = new JavaThread(); 3596 main_thread->set_thread_state(_thread_in_vm); 3597 main_thread->initialize_thread_current(); 3598 // must do this before set_active_handles 3599 main_thread->record_stack_base_and_size(); 3600 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3601 3602 if (!main_thread->set_as_starting_thread()) { 3603 vm_shutdown_during_initialization( 3604 "Failed necessary internal allocation. Out of swap space"); 3605 delete main_thread; 3606 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3607 return JNI_ENOMEM; 3608 } 3609 3610 // Enable guard page *after* os::create_main_thread(), otherwise it would 3611 // crash Linux VM, see notes in os_linux.cpp. 3612 main_thread->create_stack_guard_pages(); 3613 3614 // Initialize Java-Level synchronization subsystem 3615 ObjectMonitor::Initialize(); 3616 3617 // Initialize global modules 3618 jint status = init_globals(); 3619 if (status != JNI_OK) { 3620 delete main_thread; 3621 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3622 return status; 3623 } 3624 3625 if (TRACE_INITIALIZE() != JNI_OK) { 3626 vm_exit_during_initialization("Failed to initialize tracing backend"); 3627 } 3628 3629 // Should be done after the heap is fully created 3630 main_thread->cache_global_variables(); 3631 3632 HandleMark hm; 3633 3634 { MutexLocker mu(Threads_lock); 3635 Threads::add(main_thread); 3636 } 3637 3638 // Any JVMTI raw monitors entered in onload will transition into 3639 // real raw monitor. VM is setup enough here for raw monitor enter. 3640 JvmtiExport::transition_pending_onload_raw_monitors(); 3641 3642 // Create the VMThread 3643 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3644 3645 VMThread::create(); 3646 Thread* vmthread = VMThread::vm_thread(); 3647 3648 if (!os::create_thread(vmthread, os::vm_thread)) { 3649 vm_exit_during_initialization("Cannot create VM thread. " 3650 "Out of system resources."); 3651 } 3652 3653 // Wait for the VM thread to become ready, and VMThread::run to initialize 3654 // Monitors can have spurious returns, must always check another state flag 3655 { 3656 MutexLocker ml(Notify_lock); 3657 os::start_thread(vmthread); 3658 while (vmthread->active_handles() == NULL) { 3659 Notify_lock->wait(); 3660 } 3661 } 3662 } 3663 3664 assert(Universe::is_fully_initialized(), "not initialized"); 3665 if (VerifyDuringStartup) { 3666 // Make sure we're starting with a clean slate. 3667 VM_Verify verify_op; 3668 VMThread::execute(&verify_op); 3669 } 3670 3671 Thread* THREAD = Thread::current(); 3672 3673 // Always call even when there are not JVMTI environments yet, since environments 3674 // may be attached late and JVMTI must track phases of VM execution 3675 JvmtiExport::enter_early_start_phase(); 3676 3677 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3678 JvmtiExport::post_early_vm_start(); 3679 3680 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3681 3682 // We need this for ClassDataSharing - the initial vm.info property is set 3683 // with the default value of CDS "sharing" which may be reset through 3684 // command line options. 3685 reset_vm_info_property(CHECK_JNI_ERR); 3686 3687 quicken_jni_functions(); 3688 3689 // No more stub generation allowed after that point. 3690 StubCodeDesc::freeze(); 3691 3692 // Set flag that basic initialization has completed. Used by exceptions and various 3693 // debug stuff, that does not work until all basic classes have been initialized. 3694 set_init_completed(); 3695 3696 LogConfiguration::post_initialize(); 3697 Metaspace::post_initialize(); 3698 3699 HOTSPOT_VM_INIT_END(); 3700 3701 // record VM initialization completion time 3702 #if INCLUDE_MANAGEMENT 3703 Management::record_vm_init_completed(); 3704 #endif // INCLUDE_MANAGEMENT 3705 3706 // Signal Dispatcher needs to be started before VMInit event is posted 3707 os::signal_init(CHECK_JNI_ERR); 3708 3709 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3710 if (!DisableAttachMechanism) { 3711 AttachListener::vm_start(); 3712 if (StartAttachListener || AttachListener::init_at_startup()) { 3713 AttachListener::init(); 3714 } 3715 } 3716 3717 // Launch -Xrun agents 3718 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3719 // back-end can launch with -Xdebug -Xrunjdwp. 3720 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3721 create_vm_init_libraries(); 3722 } 3723 3724 if (CleanChunkPoolAsync) { 3725 Chunk::start_chunk_pool_cleaner_task(); 3726 } 3727 3728 // initialize compiler(s) 3729 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 3730 CompileBroker::compilation_init(CHECK_JNI_ERR); 3731 #endif 3732 3733 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3734 // It is done after compilers are initialized, because otherwise compilations of 3735 // signature polymorphic MH intrinsics can be missed 3736 // (see SystemDictionary::find_method_handle_intrinsic). 3737 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3738 3739 // This will initialize the module system. Only java.base classes can be 3740 // loaded until phase 2 completes 3741 call_initPhase2(CHECK_JNI_ERR); 3742 3743 // Always call even when there are not JVMTI environments yet, since environments 3744 // may be attached late and JVMTI must track phases of VM execution 3745 JvmtiExport::enter_start_phase(); 3746 3747 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3748 JvmtiExport::post_vm_start(); 3749 3750 // Final system initialization including security manager and system class loader 3751 call_initPhase3(CHECK_JNI_ERR); 3752 3753 // cache the system and platform class loaders 3754 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3755 3756 #if INCLUDE_JVMCI 3757 if (EnableJVMCI) { 3758 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled. 3759 // The JVMCI Java initialization code will read this flag and 3760 // do the printing if it's set. 3761 bool init = JVMCIPrintProperties; 3762 3763 if (!init) { 3764 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3765 // compilations via JVMCI will not actually block until JVMCI is initialized. 3766 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3767 } 3768 3769 if (init) { 3770 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3771 } 3772 } 3773 #endif 3774 3775 // Always call even when there are not JVMTI environments yet, since environments 3776 // may be attached late and JVMTI must track phases of VM execution 3777 JvmtiExport::enter_live_phase(); 3778 3779 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3780 JvmtiExport::post_vm_initialized(); 3781 3782 if (TRACE_START() != JNI_OK) { 3783 vm_exit_during_initialization("Failed to start tracing backend."); 3784 } 3785 3786 #if INCLUDE_MANAGEMENT 3787 Management::initialize(THREAD); 3788 3789 if (HAS_PENDING_EXCEPTION) { 3790 // management agent fails to start possibly due to 3791 // configuration problem and is responsible for printing 3792 // stack trace if appropriate. Simply exit VM. 3793 vm_exit(1); 3794 } 3795 #endif // INCLUDE_MANAGEMENT 3796 3797 if (MemProfiling) MemProfiler::engage(); 3798 StatSampler::engage(); 3799 if (CheckJNICalls) JniPeriodicChecker::engage(); 3800 3801 BiasedLocking::init(); 3802 3803 #if INCLUDE_RTM_OPT 3804 RTMLockingCounters::init(); 3805 #endif 3806 3807 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3808 call_postVMInitHook(THREAD); 3809 // The Java side of PostVMInitHook.run must deal with all 3810 // exceptions and provide means of diagnosis. 3811 if (HAS_PENDING_EXCEPTION) { 3812 CLEAR_PENDING_EXCEPTION; 3813 } 3814 } 3815 3816 { 3817 MutexLocker ml(PeriodicTask_lock); 3818 // Make sure the WatcherThread can be started by WatcherThread::start() 3819 // or by dynamic enrollment. 3820 WatcherThread::make_startable(); 3821 // Start up the WatcherThread if there are any periodic tasks 3822 // NOTE: All PeriodicTasks should be registered by now. If they 3823 // aren't, late joiners might appear to start slowly (we might 3824 // take a while to process their first tick). 3825 if (PeriodicTask::num_tasks() > 0) { 3826 WatcherThread::start(); 3827 } 3828 } 3829 3830 create_vm_timer.end(); 3831 #ifdef ASSERT 3832 _vm_complete = true; 3833 #endif 3834 3835 if (DumpSharedSpaces) { 3836 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3837 ShouldNotReachHere(); 3838 } 3839 3840 return JNI_OK; 3841 } 3842 3843 // type for the Agent_OnLoad and JVM_OnLoad entry points 3844 extern "C" { 3845 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3846 } 3847 // Find a command line agent library and return its entry point for 3848 // -agentlib: -agentpath: -Xrun 3849 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3850 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3851 const char *on_load_symbols[], 3852 size_t num_symbol_entries) { 3853 OnLoadEntry_t on_load_entry = NULL; 3854 void *library = NULL; 3855 3856 if (!agent->valid()) { 3857 char buffer[JVM_MAXPATHLEN]; 3858 char ebuf[1024] = ""; 3859 const char *name = agent->name(); 3860 const char *msg = "Could not find agent library "; 3861 3862 // First check to see if agent is statically linked into executable 3863 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3864 library = agent->os_lib(); 3865 } else if (agent->is_absolute_path()) { 3866 library = os::dll_load(name, ebuf, sizeof ebuf); 3867 if (library == NULL) { 3868 const char *sub_msg = " in absolute path, with error: "; 3869 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3870 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3871 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3872 // If we can't find the agent, exit. 3873 vm_exit_during_initialization(buf, NULL); 3874 FREE_C_HEAP_ARRAY(char, buf); 3875 } 3876 } else { 3877 // Try to load the agent from the standard dll directory 3878 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3879 name)) { 3880 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3881 } 3882 if (library == NULL) { // Try the library path directory. 3883 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 3884 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3885 } 3886 if (library == NULL) { 3887 const char *sub_msg = " on the library path, with error: "; 3888 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3889 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3890 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3891 // If we can't find the agent, exit. 3892 vm_exit_during_initialization(buf, NULL); 3893 FREE_C_HEAP_ARRAY(char, buf); 3894 } 3895 } 3896 } 3897 agent->set_os_lib(library); 3898 agent->set_valid(); 3899 } 3900 3901 // Find the OnLoad function. 3902 on_load_entry = 3903 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3904 false, 3905 on_load_symbols, 3906 num_symbol_entries)); 3907 return on_load_entry; 3908 } 3909 3910 // Find the JVM_OnLoad entry point 3911 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3912 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3913 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3914 } 3915 3916 // Find the Agent_OnLoad entry point 3917 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3918 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3919 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3920 } 3921 3922 // For backwards compatibility with -Xrun 3923 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3924 // treated like -agentpath: 3925 // Must be called before agent libraries are created 3926 void Threads::convert_vm_init_libraries_to_agents() { 3927 AgentLibrary* agent; 3928 AgentLibrary* next; 3929 3930 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3931 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3932 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3933 3934 // If there is an JVM_OnLoad function it will get called later, 3935 // otherwise see if there is an Agent_OnLoad 3936 if (on_load_entry == NULL) { 3937 on_load_entry = lookup_agent_on_load(agent); 3938 if (on_load_entry != NULL) { 3939 // switch it to the agent list -- so that Agent_OnLoad will be called, 3940 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3941 Arguments::convert_library_to_agent(agent); 3942 } else { 3943 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3944 } 3945 } 3946 } 3947 } 3948 3949 // Create agents for -agentlib: -agentpath: and converted -Xrun 3950 // Invokes Agent_OnLoad 3951 // Called very early -- before JavaThreads exist 3952 void Threads::create_vm_init_agents() { 3953 extern struct JavaVM_ main_vm; 3954 AgentLibrary* agent; 3955 3956 JvmtiExport::enter_onload_phase(); 3957 3958 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3959 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3960 3961 if (on_load_entry != NULL) { 3962 // Invoke the Agent_OnLoad function 3963 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3964 if (err != JNI_OK) { 3965 vm_exit_during_initialization("agent library failed to init", agent->name()); 3966 } 3967 } else { 3968 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3969 } 3970 } 3971 JvmtiExport::enter_primordial_phase(); 3972 } 3973 3974 extern "C" { 3975 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3976 } 3977 3978 void Threads::shutdown_vm_agents() { 3979 // Send any Agent_OnUnload notifications 3980 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3981 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3982 extern struct JavaVM_ main_vm; 3983 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3984 3985 // Find the Agent_OnUnload function. 3986 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3987 os::find_agent_function(agent, 3988 false, 3989 on_unload_symbols, 3990 num_symbol_entries)); 3991 3992 // Invoke the Agent_OnUnload function 3993 if (unload_entry != NULL) { 3994 JavaThread* thread = JavaThread::current(); 3995 ThreadToNativeFromVM ttn(thread); 3996 HandleMark hm(thread); 3997 (*unload_entry)(&main_vm); 3998 } 3999 } 4000 } 4001 4002 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4003 // Invokes JVM_OnLoad 4004 void Threads::create_vm_init_libraries() { 4005 extern struct JavaVM_ main_vm; 4006 AgentLibrary* agent; 4007 4008 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4009 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4010 4011 if (on_load_entry != NULL) { 4012 // Invoke the JVM_OnLoad function 4013 JavaThread* thread = JavaThread::current(); 4014 ThreadToNativeFromVM ttn(thread); 4015 HandleMark hm(thread); 4016 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4017 if (err != JNI_OK) { 4018 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4019 } 4020 } else { 4021 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4022 } 4023 } 4024 } 4025 4026 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 4027 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 4028 4029 JavaThread* java_thread = NULL; 4030 // Sequential search for now. Need to do better optimization later. 4031 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 4032 oop tobj = thread->threadObj(); 4033 if (!thread->is_exiting() && 4034 tobj != NULL && 4035 java_tid == java_lang_Thread::thread_id(tobj)) { 4036 java_thread = thread; 4037 break; 4038 } 4039 } 4040 return java_thread; 4041 } 4042 4043 4044 // Last thread running calls java.lang.Shutdown.shutdown() 4045 void JavaThread::invoke_shutdown_hooks() { 4046 HandleMark hm(this); 4047 4048 // We could get here with a pending exception, if so clear it now. 4049 if (this->has_pending_exception()) { 4050 this->clear_pending_exception(); 4051 } 4052 4053 EXCEPTION_MARK; 4054 Klass* shutdown_klass = 4055 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4056 THREAD); 4057 if (shutdown_klass != NULL) { 4058 // SystemDictionary::resolve_or_null will return null if there was 4059 // an exception. If we cannot load the Shutdown class, just don't 4060 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4061 // and finalizers (if runFinalizersOnExit is set) won't be run. 4062 // Note that if a shutdown hook was registered or runFinalizersOnExit 4063 // was called, the Shutdown class would have already been loaded 4064 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4065 JavaValue result(T_VOID); 4066 JavaCalls::call_static(&result, 4067 shutdown_klass, 4068 vmSymbols::shutdown_method_name(), 4069 vmSymbols::void_method_signature(), 4070 THREAD); 4071 } 4072 CLEAR_PENDING_EXCEPTION; 4073 } 4074 4075 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4076 // the program falls off the end of main(). Another VM exit path is through 4077 // vm_exit() when the program calls System.exit() to return a value or when 4078 // there is a serious error in VM. The two shutdown paths are not exactly 4079 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4080 // and VM_Exit op at VM level. 4081 // 4082 // Shutdown sequence: 4083 // + Shutdown native memory tracking if it is on 4084 // + Wait until we are the last non-daemon thread to execute 4085 // <-- every thing is still working at this moment --> 4086 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4087 // shutdown hooks, run finalizers if finalization-on-exit 4088 // + Call before_exit(), prepare for VM exit 4089 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4090 // currently the only user of this mechanism is File.deleteOnExit()) 4091 // > stop StatSampler, watcher thread, CMS threads, 4092 // post thread end and vm death events to JVMTI, 4093 // stop signal thread 4094 // + Call JavaThread::exit(), it will: 4095 // > release JNI handle blocks, remove stack guard pages 4096 // > remove this thread from Threads list 4097 // <-- no more Java code from this thread after this point --> 4098 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4099 // the compiler threads at safepoint 4100 // <-- do not use anything that could get blocked by Safepoint --> 4101 // + Disable tracing at JNI/JVM barriers 4102 // + Set _vm_exited flag for threads that are still running native code 4103 // + Delete this thread 4104 // + Call exit_globals() 4105 // > deletes tty 4106 // > deletes PerfMemory resources 4107 // + Return to caller 4108 4109 bool Threads::destroy_vm() { 4110 JavaThread* thread = JavaThread::current(); 4111 4112 #ifdef ASSERT 4113 _vm_complete = false; 4114 #endif 4115 // Wait until we are the last non-daemon thread to execute 4116 { MutexLocker nu(Threads_lock); 4117 while (Threads::number_of_non_daemon_threads() > 1) 4118 // This wait should make safepoint checks, wait without a timeout, 4119 // and wait as a suspend-equivalent condition. 4120 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4121 Mutex::_as_suspend_equivalent_flag); 4122 } 4123 4124 // Hang forever on exit if we are reporting an error. 4125 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4126 os::infinite_sleep(); 4127 } 4128 os::wait_for_keypress_at_exit(); 4129 4130 // run Java level shutdown hooks 4131 thread->invoke_shutdown_hooks(); 4132 4133 before_exit(thread); 4134 4135 thread->exit(true); 4136 4137 // Stop VM thread. 4138 { 4139 // 4945125 The vm thread comes to a safepoint during exit. 4140 // GC vm_operations can get caught at the safepoint, and the 4141 // heap is unparseable if they are caught. Grab the Heap_lock 4142 // to prevent this. The GC vm_operations will not be able to 4143 // queue until after the vm thread is dead. After this point, 4144 // we'll never emerge out of the safepoint before the VM exits. 4145 4146 MutexLocker ml(Heap_lock); 4147 4148 VMThread::wait_for_vm_thread_exit(); 4149 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4150 VMThread::destroy(); 4151 } 4152 4153 // clean up ideal graph printers 4154 #if defined(COMPILER2) && !defined(PRODUCT) 4155 IdealGraphPrinter::clean_up(); 4156 #endif 4157 4158 // Now, all Java threads are gone except daemon threads. Daemon threads 4159 // running Java code or in VM are stopped by the Safepoint. However, 4160 // daemon threads executing native code are still running. But they 4161 // will be stopped at native=>Java/VM barriers. Note that we can't 4162 // simply kill or suspend them, as it is inherently deadlock-prone. 4163 4164 VM_Exit::set_vm_exited(); 4165 4166 notify_vm_shutdown(); 4167 4168 delete thread; 4169 4170 #if INCLUDE_JVMCI 4171 if (JVMCICounterSize > 0) { 4172 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4173 } 4174 #endif 4175 4176 // exit_globals() will delete tty 4177 exit_globals(); 4178 4179 LogConfiguration::finalize(); 4180 4181 return true; 4182 } 4183 4184 4185 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4186 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4187 return is_supported_jni_version(version); 4188 } 4189 4190 4191 jboolean Threads::is_supported_jni_version(jint version) { 4192 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4193 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4194 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4195 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4196 if (version == JNI_VERSION_9) return JNI_TRUE; 4197 if (version == JNI_VERSION_10) return JNI_TRUE; 4198 return JNI_FALSE; 4199 } 4200 4201 4202 void Threads::add(JavaThread* p, bool force_daemon) { 4203 // The threads lock must be owned at this point 4204 assert_locked_or_safepoint(Threads_lock); 4205 4206 // See the comment for this method in thread.hpp for its purpose and 4207 // why it is called here. 4208 p->initialize_queues(); 4209 p->set_next(_thread_list); 4210 _thread_list = p; 4211 _number_of_threads++; 4212 oop threadObj = p->threadObj(); 4213 bool daemon = true; 4214 // Bootstrapping problem: threadObj can be null for initial 4215 // JavaThread (or for threads attached via JNI) 4216 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4217 _number_of_non_daemon_threads++; 4218 daemon = false; 4219 } 4220 4221 ThreadService::add_thread(p, daemon); 4222 4223 // Possible GC point. 4224 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4225 } 4226 4227 void Threads::remove(JavaThread* p) { 4228 4229 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4230 ObjectSynchronizer::omFlush(p); 4231 4232 // Extra scope needed for Thread_lock, so we can check 4233 // that we do not remove thread without safepoint code notice 4234 { MutexLocker ml(Threads_lock); 4235 4236 assert(includes(p), "p must be present"); 4237 4238 JavaThread* current = _thread_list; 4239 JavaThread* prev = NULL; 4240 4241 while (current != p) { 4242 prev = current; 4243 current = current->next(); 4244 } 4245 4246 if (prev) { 4247 prev->set_next(current->next()); 4248 } else { 4249 _thread_list = p->next(); 4250 } 4251 _number_of_threads--; 4252 oop threadObj = p->threadObj(); 4253 bool daemon = true; 4254 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4255 _number_of_non_daemon_threads--; 4256 daemon = false; 4257 4258 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4259 // on destroy_vm will wake up. 4260 if (number_of_non_daemon_threads() == 1) { 4261 Threads_lock->notify_all(); 4262 } 4263 } 4264 ThreadService::remove_thread(p, daemon); 4265 4266 // Make sure that safepoint code disregard this thread. This is needed since 4267 // the thread might mess around with locks after this point. This can cause it 4268 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4269 // of this thread since it is removed from the queue. 4270 p->set_terminated_value(); 4271 } // unlock Threads_lock 4272 4273 // Since Events::log uses a lock, we grab it outside the Threads_lock 4274 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4275 } 4276 4277 // Threads_lock must be held when this is called (or must be called during a safepoint) 4278 bool Threads::includes(JavaThread* p) { 4279 assert(Threads_lock->is_locked(), "sanity check"); 4280 ALL_JAVA_THREADS(q) { 4281 if (q == p) { 4282 return true; 4283 } 4284 } 4285 return false; 4286 } 4287 4288 // Operations on the Threads list for GC. These are not explicitly locked, 4289 // but the garbage collector must provide a safe context for them to run. 4290 // In particular, these things should never be called when the Threads_lock 4291 // is held by some other thread. (Note: the Safepoint abstraction also 4292 // uses the Threads_lock to guarantee this property. It also makes sure that 4293 // all threads gets blocked when exiting or starting). 4294 4295 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4296 ALL_JAVA_THREADS(p) { 4297 p->oops_do(f, cf); 4298 } 4299 VMThread::vm_thread()->oops_do(f, cf); 4300 } 4301 4302 void Threads::change_thread_claim_parity() { 4303 // Set the new claim parity. 4304 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4305 "Not in range."); 4306 _thread_claim_parity++; 4307 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4308 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4309 "Not in range."); 4310 } 4311 4312 #ifdef ASSERT 4313 void Threads::assert_all_threads_claimed() { 4314 ALL_JAVA_THREADS(p) { 4315 const int thread_parity = p->oops_do_parity(); 4316 assert((thread_parity == _thread_claim_parity), 4317 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4318 } 4319 VMThread* vmt = VMThread::vm_thread(); 4320 const int thread_parity = vmt->oops_do_parity(); 4321 assert((thread_parity == _thread_claim_parity), 4322 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4323 } 4324 #endif // ASSERT 4325 4326 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4327 int cp = Threads::thread_claim_parity(); 4328 ALL_JAVA_THREADS(p) { 4329 if (p->claim_oops_do(is_par, cp)) { 4330 p->oops_do(f, cf); 4331 } 4332 } 4333 VMThread* vmt = VMThread::vm_thread(); 4334 if (vmt->claim_oops_do(is_par, cp)) { 4335 vmt->oops_do(f, cf); 4336 } 4337 } 4338 4339 #if INCLUDE_ALL_GCS 4340 // Used by ParallelScavenge 4341 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4342 ALL_JAVA_THREADS(p) { 4343 q->enqueue(new ThreadRootsTask(p)); 4344 } 4345 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4346 } 4347 4348 // Used by Parallel Old 4349 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4350 ALL_JAVA_THREADS(p) { 4351 q->enqueue(new ThreadRootsMarkingTask(p)); 4352 } 4353 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4354 } 4355 #endif // INCLUDE_ALL_GCS 4356 4357 void Threads::nmethods_do(CodeBlobClosure* cf) { 4358 ALL_JAVA_THREADS(p) { 4359 // This is used by the code cache sweeper to mark nmethods that are active 4360 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4361 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4362 if(!p->is_Code_cache_sweeper_thread()) { 4363 p->nmethods_do(cf); 4364 } 4365 } 4366 } 4367 4368 void Threads::metadata_do(void f(Metadata*)) { 4369 ALL_JAVA_THREADS(p) { 4370 p->metadata_do(f); 4371 } 4372 } 4373 4374 class ThreadHandlesClosure : public ThreadClosure { 4375 void (*_f)(Metadata*); 4376 public: 4377 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4378 virtual void do_thread(Thread* thread) { 4379 thread->metadata_handles_do(_f); 4380 } 4381 }; 4382 4383 void Threads::metadata_handles_do(void f(Metadata*)) { 4384 // Only walk the Handles in Thread. 4385 ThreadHandlesClosure handles_closure(f); 4386 threads_do(&handles_closure); 4387 } 4388 4389 void Threads::deoptimized_wrt_marked_nmethods() { 4390 ALL_JAVA_THREADS(p) { 4391 p->deoptimized_wrt_marked_nmethods(); 4392 } 4393 } 4394 4395 4396 // Get count Java threads that are waiting to enter the specified monitor. 4397 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4398 address monitor, 4399 bool doLock) { 4400 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4401 "must grab Threads_lock or be at safepoint"); 4402 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4403 4404 int i = 0; 4405 { 4406 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4407 ALL_JAVA_THREADS(p) { 4408 if (!p->can_call_java()) continue; 4409 4410 address pending = (address)p->current_pending_monitor(); 4411 if (pending == monitor) { // found a match 4412 if (i < count) result->append(p); // save the first count matches 4413 i++; 4414 } 4415 } 4416 } 4417 return result; 4418 } 4419 4420 4421 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4422 bool doLock) { 4423 assert(doLock || 4424 Threads_lock->owned_by_self() || 4425 SafepointSynchronize::is_at_safepoint(), 4426 "must grab Threads_lock or be at safepoint"); 4427 4428 // NULL owner means not locked so we can skip the search 4429 if (owner == NULL) return NULL; 4430 4431 { 4432 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4433 ALL_JAVA_THREADS(p) { 4434 // first, see if owner is the address of a Java thread 4435 if (owner == (address)p) return p; 4436 } 4437 } 4438 // Cannot assert on lack of success here since this function may be 4439 // used by code that is trying to report useful problem information 4440 // like deadlock detection. 4441 if (UseHeavyMonitors) return NULL; 4442 4443 // If we didn't find a matching Java thread and we didn't force use of 4444 // heavyweight monitors, then the owner is the stack address of the 4445 // Lock Word in the owning Java thread's stack. 4446 // 4447 JavaThread* the_owner = NULL; 4448 { 4449 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4450 ALL_JAVA_THREADS(q) { 4451 if (q->is_lock_owned(owner)) { 4452 the_owner = q; 4453 break; 4454 } 4455 } 4456 } 4457 // cannot assert on lack of success here; see above comment 4458 return the_owner; 4459 } 4460 4461 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4462 void Threads::print_on(outputStream* st, bool print_stacks, 4463 bool internal_format, bool print_concurrent_locks) { 4464 char buf[32]; 4465 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4466 4467 st->print_cr("Full thread dump %s (%s %s):", 4468 Abstract_VM_Version::vm_name(), 4469 Abstract_VM_Version::vm_release(), 4470 Abstract_VM_Version::vm_info_string()); 4471 st->cr(); 4472 4473 #if INCLUDE_SERVICES 4474 // Dump concurrent locks 4475 ConcurrentLocksDump concurrent_locks; 4476 if (print_concurrent_locks) { 4477 concurrent_locks.dump_at_safepoint(); 4478 } 4479 #endif // INCLUDE_SERVICES 4480 4481 ALL_JAVA_THREADS(p) { 4482 ResourceMark rm; 4483 p->print_on(st); 4484 if (print_stacks) { 4485 if (internal_format) { 4486 p->trace_stack(); 4487 } else { 4488 p->print_stack_on(st); 4489 } 4490 } 4491 st->cr(); 4492 #if INCLUDE_SERVICES 4493 if (print_concurrent_locks) { 4494 concurrent_locks.print_locks_on(p, st); 4495 } 4496 #endif // INCLUDE_SERVICES 4497 } 4498 4499 VMThread::vm_thread()->print_on(st); 4500 st->cr(); 4501 Universe::heap()->print_gc_threads_on(st); 4502 WatcherThread* wt = WatcherThread::watcher_thread(); 4503 if (wt != NULL) { 4504 wt->print_on(st); 4505 st->cr(); 4506 } 4507 st->flush(); 4508 } 4509 4510 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4511 int buflen, bool* found_current) { 4512 if (this_thread != NULL) { 4513 bool is_current = (current == this_thread); 4514 *found_current = *found_current || is_current; 4515 st->print("%s", is_current ? "=>" : " "); 4516 4517 st->print(PTR_FORMAT, p2i(this_thread)); 4518 st->print(" "); 4519 this_thread->print_on_error(st, buf, buflen); 4520 st->cr(); 4521 } 4522 } 4523 4524 class PrintOnErrorClosure : public ThreadClosure { 4525 outputStream* _st; 4526 Thread* _current; 4527 char* _buf; 4528 int _buflen; 4529 bool* _found_current; 4530 public: 4531 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4532 int buflen, bool* found_current) : 4533 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4534 4535 virtual void do_thread(Thread* thread) { 4536 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4537 } 4538 }; 4539 4540 // Threads::print_on_error() is called by fatal error handler. It's possible 4541 // that VM is not at safepoint and/or current thread is inside signal handler. 4542 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4543 // memory (even in resource area), it might deadlock the error handler. 4544 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4545 int buflen) { 4546 bool found_current = false; 4547 st->print_cr("Java Threads: ( => current thread )"); 4548 ALL_JAVA_THREADS(thread) { 4549 print_on_error(thread, st, current, buf, buflen, &found_current); 4550 } 4551 st->cr(); 4552 4553 st->print_cr("Other Threads:"); 4554 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4555 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4556 4557 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4558 Universe::heap()->gc_threads_do(&print_closure); 4559 4560 if (!found_current) { 4561 st->cr(); 4562 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4563 current->print_on_error(st, buf, buflen); 4564 st->cr(); 4565 } 4566 st->cr(); 4567 st->print_cr("Threads with active compile tasks:"); 4568 print_threads_compiling(st, buf, buflen); 4569 } 4570 4571 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4572 ALL_JAVA_THREADS(thread) { 4573 if (thread->is_Compiler_thread()) { 4574 CompilerThread* ct = (CompilerThread*) thread; 4575 if (ct->task() != NULL) { 4576 thread->print_name_on_error(st, buf, buflen); 4577 ct->task()->print(st, NULL, true, true); 4578 } 4579 } 4580 } 4581 } 4582 4583 4584 // Internal SpinLock and Mutex 4585 // Based on ParkEvent 4586 4587 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4588 // 4589 // We employ SpinLocks _only for low-contention, fixed-length 4590 // short-duration critical sections where we're concerned 4591 // about native mutex_t or HotSpot Mutex:: latency. 4592 // The mux construct provides a spin-then-block mutual exclusion 4593 // mechanism. 4594 // 4595 // Testing has shown that contention on the ListLock guarding gFreeList 4596 // is common. If we implement ListLock as a simple SpinLock it's common 4597 // for the JVM to devolve to yielding with little progress. This is true 4598 // despite the fact that the critical sections protected by ListLock are 4599 // extremely short. 4600 // 4601 // TODO-FIXME: ListLock should be of type SpinLock. 4602 // We should make this a 1st-class type, integrated into the lock 4603 // hierarchy as leaf-locks. Critically, the SpinLock structure 4604 // should have sufficient padding to avoid false-sharing and excessive 4605 // cache-coherency traffic. 4606 4607 4608 typedef volatile int SpinLockT; 4609 4610 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4611 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4612 return; // normal fast-path return 4613 } 4614 4615 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4616 TEVENT(SpinAcquire - ctx); 4617 int ctr = 0; 4618 int Yields = 0; 4619 for (;;) { 4620 while (*adr != 0) { 4621 ++ctr; 4622 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4623 if (Yields > 5) { 4624 os::naked_short_sleep(1); 4625 } else { 4626 os::naked_yield(); 4627 ++Yields; 4628 } 4629 } else { 4630 SpinPause(); 4631 } 4632 } 4633 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4634 } 4635 } 4636 4637 void Thread::SpinRelease(volatile int * adr) { 4638 assert(*adr != 0, "invariant"); 4639 OrderAccess::fence(); // guarantee at least release consistency. 4640 // Roach-motel semantics. 4641 // It's safe if subsequent LDs and STs float "up" into the critical section, 4642 // but prior LDs and STs within the critical section can't be allowed 4643 // to reorder or float past the ST that releases the lock. 4644 // Loads and stores in the critical section - which appear in program 4645 // order before the store that releases the lock - must also appear 4646 // before the store that releases the lock in memory visibility order. 4647 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4648 // the ST of 0 into the lock-word which releases the lock, so fence 4649 // more than covers this on all platforms. 4650 *adr = 0; 4651 } 4652 4653 // muxAcquire and muxRelease: 4654 // 4655 // * muxAcquire and muxRelease support a single-word lock-word construct. 4656 // The LSB of the word is set IFF the lock is held. 4657 // The remainder of the word points to the head of a singly-linked list 4658 // of threads blocked on the lock. 4659 // 4660 // * The current implementation of muxAcquire-muxRelease uses its own 4661 // dedicated Thread._MuxEvent instance. If we're interested in 4662 // minimizing the peak number of extant ParkEvent instances then 4663 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4664 // as certain invariants were satisfied. Specifically, care would need 4665 // to be taken with regards to consuming unpark() "permits". 4666 // A safe rule of thumb is that a thread would never call muxAcquire() 4667 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4668 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4669 // consume an unpark() permit intended for monitorenter, for instance. 4670 // One way around this would be to widen the restricted-range semaphore 4671 // implemented in park(). Another alternative would be to provide 4672 // multiple instances of the PlatformEvent() for each thread. One 4673 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4674 // 4675 // * Usage: 4676 // -- Only as leaf locks 4677 // -- for short-term locking only as muxAcquire does not perform 4678 // thread state transitions. 4679 // 4680 // Alternatives: 4681 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4682 // but with parking or spin-then-park instead of pure spinning. 4683 // * Use Taura-Oyama-Yonenzawa locks. 4684 // * It's possible to construct a 1-0 lock if we encode the lockword as 4685 // (List,LockByte). Acquire will CAS the full lockword while Release 4686 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4687 // acquiring threads use timers (ParkTimed) to detect and recover from 4688 // the stranding window. Thread/Node structures must be aligned on 256-byte 4689 // boundaries by using placement-new. 4690 // * Augment MCS with advisory back-link fields maintained with CAS(). 4691 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4692 // The validity of the backlinks must be ratified before we trust the value. 4693 // If the backlinks are invalid the exiting thread must back-track through the 4694 // the forward links, which are always trustworthy. 4695 // * Add a successor indication. The LockWord is currently encoded as 4696 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4697 // to provide the usual futile-wakeup optimization. 4698 // See RTStt for details. 4699 // * Consider schedctl.sc_nopreempt to cover the critical section. 4700 // 4701 4702 4703 typedef volatile intptr_t MutexT; // Mux Lock-word 4704 enum MuxBits { LOCKBIT = 1 }; 4705 4706 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4707 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4708 if (w == 0) return; 4709 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4710 return; 4711 } 4712 4713 TEVENT(muxAcquire - Contention); 4714 ParkEvent * const Self = Thread::current()->_MuxEvent; 4715 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4716 for (;;) { 4717 int its = (os::is_MP() ? 100 : 0) + 1; 4718 4719 // Optional spin phase: spin-then-park strategy 4720 while (--its >= 0) { 4721 w = *Lock; 4722 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4723 return; 4724 } 4725 } 4726 4727 Self->reset(); 4728 Self->OnList = intptr_t(Lock); 4729 // The following fence() isn't _strictly necessary as the subsequent 4730 // CAS() both serializes execution and ratifies the fetched *Lock value. 4731 OrderAccess::fence(); 4732 for (;;) { 4733 w = *Lock; 4734 if ((w & LOCKBIT) == 0) { 4735 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4736 Self->OnList = 0; // hygiene - allows stronger asserts 4737 return; 4738 } 4739 continue; // Interference -- *Lock changed -- Just retry 4740 } 4741 assert(w & LOCKBIT, "invariant"); 4742 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4743 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4744 } 4745 4746 while (Self->OnList != 0) { 4747 Self->park(); 4748 } 4749 } 4750 } 4751 4752 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4753 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4754 if (w == 0) return; 4755 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4756 return; 4757 } 4758 4759 TEVENT(muxAcquire - Contention); 4760 ParkEvent * ReleaseAfter = NULL; 4761 if (ev == NULL) { 4762 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4763 } 4764 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4765 for (;;) { 4766 guarantee(ev->OnList == 0, "invariant"); 4767 int its = (os::is_MP() ? 100 : 0) + 1; 4768 4769 // Optional spin phase: spin-then-park strategy 4770 while (--its >= 0) { 4771 w = *Lock; 4772 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4773 if (ReleaseAfter != NULL) { 4774 ParkEvent::Release(ReleaseAfter); 4775 } 4776 return; 4777 } 4778 } 4779 4780 ev->reset(); 4781 ev->OnList = intptr_t(Lock); 4782 // The following fence() isn't _strictly necessary as the subsequent 4783 // CAS() both serializes execution and ratifies the fetched *Lock value. 4784 OrderAccess::fence(); 4785 for (;;) { 4786 w = *Lock; 4787 if ((w & LOCKBIT) == 0) { 4788 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4789 ev->OnList = 0; 4790 // We call ::Release while holding the outer lock, thus 4791 // artificially lengthening the critical section. 4792 // Consider deferring the ::Release() until the subsequent unlock(), 4793 // after we've dropped the outer lock. 4794 if (ReleaseAfter != NULL) { 4795 ParkEvent::Release(ReleaseAfter); 4796 } 4797 return; 4798 } 4799 continue; // Interference -- *Lock changed -- Just retry 4800 } 4801 assert(w & LOCKBIT, "invariant"); 4802 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4803 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4804 } 4805 4806 while (ev->OnList != 0) { 4807 ev->park(); 4808 } 4809 } 4810 } 4811 4812 // Release() must extract a successor from the list and then wake that thread. 4813 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4814 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4815 // Release() would : 4816 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4817 // (B) Extract a successor from the private list "in-hand" 4818 // (C) attempt to CAS() the residual back into *Lock over null. 4819 // If there were any newly arrived threads and the CAS() would fail. 4820 // In that case Release() would detach the RATs, re-merge the list in-hand 4821 // with the RATs and repeat as needed. Alternately, Release() might 4822 // detach and extract a successor, but then pass the residual list to the wakee. 4823 // The wakee would be responsible for reattaching and remerging before it 4824 // competed for the lock. 4825 // 4826 // Both "pop" and DMR are immune from ABA corruption -- there can be 4827 // multiple concurrent pushers, but only one popper or detacher. 4828 // This implementation pops from the head of the list. This is unfair, 4829 // but tends to provide excellent throughput as hot threads remain hot. 4830 // (We wake recently run threads first). 4831 // 4832 // All paths through muxRelease() will execute a CAS. 4833 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4834 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4835 // executed within the critical section are complete and globally visible before the 4836 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4837 void Thread::muxRelease(volatile intptr_t * Lock) { 4838 for (;;) { 4839 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4840 assert(w & LOCKBIT, "invariant"); 4841 if (w == LOCKBIT) return; 4842 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4843 assert(List != NULL, "invariant"); 4844 assert(List->OnList == intptr_t(Lock), "invariant"); 4845 ParkEvent * const nxt = List->ListNext; 4846 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4847 4848 // The following CAS() releases the lock and pops the head element. 4849 // The CAS() also ratifies the previously fetched lock-word value. 4850 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4851 continue; 4852 } 4853 List->OnList = 0; 4854 OrderAccess::fence(); 4855 List->unpark(); 4856 return; 4857 } 4858 } 4859 4860 4861 void Threads::verify() { 4862 ALL_JAVA_THREADS(p) { 4863 p->verify(); 4864 } 4865 VMThread* thread = VMThread::vm_thread(); 4866 if (thread != NULL) thread->verify(); 4867 }