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