1 /* 2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "jvm.h" 27 #include "classfile/classLoader.hpp" 28 #include "classfile/javaClasses.hpp" 29 #include "classfile/moduleEntry.hpp" 30 #include "classfile/systemDictionary.hpp" 31 #include "classfile/vmSymbols.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/scopeDesc.hpp" 34 #include "compiler/compileBroker.hpp" 35 #include "compiler/compileTask.hpp" 36 #include "gc/shared/gcId.hpp" 37 #include "gc/shared/gcLocker.inline.hpp" 38 #include "gc/shared/workgroup.hpp" 39 #include "interpreter/interpreter.hpp" 40 #include "interpreter/linkResolver.hpp" 41 #include "interpreter/oopMapCache.hpp" 42 #include "jvmtifiles/jvmtiEnv.hpp" 43 #include "logging/log.hpp" 44 #include "logging/logConfiguration.hpp" 45 #include "logging/logStream.hpp" 46 #include "memory/allocation.inline.hpp" 47 #include "memory/metaspaceShared.hpp" 48 #include "memory/oopFactory.hpp" 49 #include "memory/resourceArea.hpp" 50 #include "memory/universe.hpp" 51 #include "oops/instanceKlass.hpp" 52 #include "oops/objArrayOop.hpp" 53 #include "oops/oop.inline.hpp" 54 #include "oops/symbol.hpp" 55 #include "oops/typeArrayOop.inline.hpp" 56 #include "oops/verifyOopClosure.hpp" 57 #include "prims/jvm_misc.hpp" 58 #include "prims/jvmtiExport.hpp" 59 #include "prims/jvmtiThreadState.hpp" 60 #include "prims/privilegedStack.hpp" 61 #include "runtime/arguments.hpp" 62 #include "runtime/atomic.hpp" 63 #include "runtime/biasedLocking.hpp" 64 #include "runtime/commandLineFlagConstraintList.hpp" 65 #include "runtime/commandLineFlagWriteableList.hpp" 66 #include "runtime/commandLineFlagRangeList.hpp" 67 #include "runtime/deoptimization.hpp" 68 #include "runtime/frame.inline.hpp" 69 #include "runtime/globals.hpp" 70 #include "runtime/handshake.hpp" 71 #include "runtime/init.hpp" 72 #include "runtime/interfaceSupport.inline.hpp" 73 #include "runtime/java.hpp" 74 #include "runtime/javaCalls.hpp" 75 #include "runtime/jniHandles.inline.hpp" 76 #include "runtime/jniPeriodicChecker.hpp" 77 #include "runtime/memprofiler.hpp" 78 #include "runtime/mutexLocker.hpp" 79 #include "runtime/objectMonitor.hpp" 80 #include "runtime/orderAccess.inline.hpp" 81 #include "runtime/osThread.hpp" 82 #include "runtime/prefetch.inline.hpp" 83 #include "runtime/safepoint.hpp" 84 #include "runtime/safepointMechanism.inline.hpp" 85 #include "runtime/sharedRuntime.hpp" 86 #include "runtime/statSampler.hpp" 87 #include "runtime/stubRoutines.hpp" 88 #include "runtime/sweeper.hpp" 89 #include "runtime/task.hpp" 90 #include "runtime/thread.inline.hpp" 91 #include "runtime/threadCritical.hpp" 92 #include "runtime/threadSMR.inline.hpp" 93 #include "runtime/timer.hpp" 94 #include "runtime/timerTrace.hpp" 95 #include "runtime/vframe.hpp" 96 #include "runtime/vframeArray.hpp" 97 #include "runtime/vframe_hp.hpp" 98 #include "runtime/vmThread.hpp" 99 #include "runtime/vm_operations.hpp" 100 #include "runtime/vm_version.hpp" 101 #include "services/attachListener.hpp" 102 #include "services/management.hpp" 103 #include "services/memTracker.hpp" 104 #include "services/threadService.hpp" 105 #include "trace/traceMacros.hpp" 106 #include "trace/tracing.hpp" 107 #include "utilities/align.hpp" 108 #include "utilities/defaultStream.hpp" 109 #include "utilities/dtrace.hpp" 110 #include "utilities/events.hpp" 111 #include "utilities/macros.hpp" 112 #include "utilities/preserveException.hpp" 113 #include "utilities/vmError.hpp" 114 #if INCLUDE_ALL_GCS 115 #include "gc/cms/concurrentMarkSweepThread.hpp" 116 #include "gc/g1/concurrentMarkThread.inline.hpp" 117 #include "gc/parallel/pcTasks.hpp" 118 #endif // INCLUDE_ALL_GCS 119 #if INCLUDE_JVMCI 120 #include "jvmci/jvmciCompiler.hpp" 121 #include "jvmci/jvmciRuntime.hpp" 122 #include "logging/logHandle.hpp" 123 #endif 124 #ifdef COMPILER1 125 #include "c1/c1_Compiler.hpp" 126 #endif 127 #ifdef COMPILER2 128 #include "opto/c2compiler.hpp" 129 #include "opto/idealGraphPrinter.hpp" 130 #endif 131 #if INCLUDE_RTM_OPT 132 #include "runtime/rtmLocking.hpp" 133 #endif 134 135 // Initialization after module runtime initialization 136 void universe_post_module_init(); // must happen after call_initPhase2 137 138 #ifdef DTRACE_ENABLED 139 140 // Only bother with this argument setup if dtrace is available 141 142 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 143 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 144 145 #define DTRACE_THREAD_PROBE(probe, javathread) \ 146 { \ 147 ResourceMark rm(this); \ 148 int len = 0; \ 149 const char* name = (javathread)->get_thread_name(); \ 150 len = strlen(name); \ 151 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 152 (char *) name, len, \ 153 java_lang_Thread::thread_id((javathread)->threadObj()), \ 154 (uintptr_t) (javathread)->osthread()->thread_id(), \ 155 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 156 } 157 158 #else // ndef DTRACE_ENABLED 159 160 #define DTRACE_THREAD_PROBE(probe, javathread) 161 162 #endif // ndef DTRACE_ENABLED 163 164 #ifndef USE_LIBRARY_BASED_TLS_ONLY 165 // Current thread is maintained as a thread-local variable 166 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 167 #endif 168 // Class hierarchy 169 // - Thread 170 // - VMThread 171 // - WatcherThread 172 // - ConcurrentMarkSweepThread 173 // - JavaThread 174 // - CompilerThread 175 176 // ======= Thread ======== 177 // Support for forcing alignment of thread objects for biased locking 178 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 179 if (UseBiasedLocking) { 180 const int alignment = markOopDesc::biased_lock_alignment; 181 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 182 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 183 : AllocateHeap(aligned_size, flags, CURRENT_PC, 184 AllocFailStrategy::RETURN_NULL); 185 void* aligned_addr = align_up(real_malloc_addr, alignment); 186 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 187 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 188 "JavaThread alignment code overflowed allocated storage"); 189 if (aligned_addr != real_malloc_addr) { 190 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 191 p2i(real_malloc_addr), 192 p2i(aligned_addr)); 193 } 194 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 195 return aligned_addr; 196 } else { 197 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 198 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 199 } 200 } 201 202 void Thread::operator delete(void* p) { 203 if (UseBiasedLocking) { 204 FreeHeap(((Thread*) p)->_real_malloc_address); 205 } else { 206 FreeHeap(p); 207 } 208 } 209 210 void JavaThread::smr_delete() { 211 if (_on_thread_list) { 212 ThreadsSMRSupport::smr_delete(this); 213 } else { 214 delete this; 215 } 216 } 217 218 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 219 // JavaThread 220 221 222 Thread::Thread() { 223 // stack and get_thread 224 set_stack_base(NULL); 225 set_stack_size(0); 226 set_self_raw_id(0); 227 set_lgrp_id(-1); 228 DEBUG_ONLY(clear_suspendible_thread();) 229 230 // allocated data structures 231 set_osthread(NULL); 232 set_resource_area(new (mtThread)ResourceArea()); 233 DEBUG_ONLY(_current_resource_mark = NULL;) 234 set_handle_area(new (mtThread) HandleArea(NULL)); 235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 236 set_active_handles(NULL); 237 set_free_handle_block(NULL); 238 set_last_handle_mark(NULL); 239 _heap_sampler.set_thread(this); 240 241 // This initial value ==> never claimed. 242 _oops_do_parity = 0; 243 _threads_hazard_ptr = NULL; 244 _nested_threads_hazard_ptr = NULL; 245 _nested_threads_hazard_ptr_cnt = 0; 246 247 // the handle mark links itself to last_handle_mark 248 new HandleMark(this); 249 250 // plain initialization 251 debug_only(_owned_locks = NULL;) 252 debug_only(_allow_allocation_count = 0;) 253 NOT_PRODUCT(_allow_safepoint_count = 0;) 254 NOT_PRODUCT(_skip_gcalot = false;) 255 _jvmti_env_iteration_count = 0; 256 set_allocated_bytes(0); 257 _vm_operation_started_count = 0; 258 _vm_operation_completed_count = 0; 259 _current_pending_monitor = NULL; 260 _current_pending_monitor_is_from_java = true; 261 _current_waiting_monitor = NULL; 262 _num_nested_signal = 0; 263 omFreeList = NULL; 264 omFreeCount = 0; 265 omFreeProvision = 32; 266 omInUseList = NULL; 267 omInUseCount = 0; 268 269 #ifdef ASSERT 270 _visited_for_critical_count = false; 271 #endif 272 273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 274 Monitor::_safepoint_check_sometimes); 275 _suspend_flags = 0; 276 277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 278 _hashStateX = os::random(); 279 _hashStateY = 842502087; 280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 281 _hashStateW = 273326509; 282 283 _OnTrap = 0; 284 _schedctl = NULL; 285 _Stalled = 0; 286 _TypeTag = 0x2BAD; 287 288 // Many of the following fields are effectively final - immutable 289 // Note that nascent threads can't use the Native Monitor-Mutex 290 // construct until the _MutexEvent is initialized ... 291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 292 // we might instead use a stack of ParkEvents that we could provision on-demand. 293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 294 // and ::Release() 295 _ParkEvent = ParkEvent::Allocate(this); 296 _SleepEvent = ParkEvent::Allocate(this); 297 _MutexEvent = ParkEvent::Allocate(this); 298 _MuxEvent = ParkEvent::Allocate(this); 299 300 #ifdef CHECK_UNHANDLED_OOPS 301 if (CheckUnhandledOops) { 302 _unhandled_oops = new UnhandledOops(this); 303 } 304 #endif // CHECK_UNHANDLED_OOPS 305 #ifdef ASSERT 306 if (UseBiasedLocking) { 307 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 308 assert(this == _real_malloc_address || 309 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 310 "bug in forced alignment of thread objects"); 311 } 312 #endif // ASSERT 313 } 314 315 void Thread::initialize_thread_current() { 316 #ifndef USE_LIBRARY_BASED_TLS_ONLY 317 assert(_thr_current == NULL, "Thread::current already initialized"); 318 _thr_current = this; 319 #endif 320 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 321 ThreadLocalStorage::set_thread(this); 322 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 323 } 324 325 void Thread::clear_thread_current() { 326 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 327 #ifndef USE_LIBRARY_BASED_TLS_ONLY 328 _thr_current = NULL; 329 #endif 330 ThreadLocalStorage::set_thread(NULL); 331 } 332 333 void Thread::record_stack_base_and_size() { 334 set_stack_base(os::current_stack_base()); 335 set_stack_size(os::current_stack_size()); 336 // CR 7190089: on Solaris, primordial thread's stack is adjusted 337 // in initialize_thread(). Without the adjustment, stack size is 338 // incorrect if stack is set to unlimited (ulimit -s unlimited). 339 // So far, only Solaris has real implementation of initialize_thread(). 340 // 341 // set up any platform-specific state. 342 os::initialize_thread(this); 343 344 // Set stack limits after thread is initialized. 345 if (is_Java_thread()) { 346 ((JavaThread*) this)->set_stack_overflow_limit(); 347 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 348 } 349 #if INCLUDE_NMT 350 // record thread's native stack, stack grows downward 351 MemTracker::record_thread_stack(stack_end(), stack_size()); 352 #endif // INCLUDE_NMT 353 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 354 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 355 os::current_thread_id(), p2i(stack_base() - stack_size()), 356 p2i(stack_base()), stack_size()/1024); 357 } 358 359 360 Thread::~Thread() { 361 EVENT_THREAD_DESTRUCT(this); 362 363 // stack_base can be NULL if the thread is never started or exited before 364 // record_stack_base_and_size called. Although, we would like to ensure 365 // that all started threads do call record_stack_base_and_size(), there is 366 // not proper way to enforce that. 367 #if INCLUDE_NMT 368 if (_stack_base != NULL) { 369 MemTracker::release_thread_stack(stack_end(), stack_size()); 370 #ifdef ASSERT 371 set_stack_base(NULL); 372 #endif 373 } 374 #endif // INCLUDE_NMT 375 376 // deallocate data structures 377 delete resource_area(); 378 // since the handle marks are using the handle area, we have to deallocated the root 379 // handle mark before deallocating the thread's handle area, 380 assert(last_handle_mark() != NULL, "check we have an element"); 381 delete last_handle_mark(); 382 assert(last_handle_mark() == NULL, "check we have reached the end"); 383 384 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 385 // We NULL out the fields for good hygiene. 386 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 387 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 388 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 389 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 390 391 delete handle_area(); 392 delete metadata_handles(); 393 394 // SR_handler uses this as a termination indicator - 395 // needs to happen before os::free_thread() 396 delete _SR_lock; 397 _SR_lock = NULL; 398 399 // osthread() can be NULL, if creation of thread failed. 400 if (osthread() != NULL) os::free_thread(osthread()); 401 402 // clear Thread::current if thread is deleting itself. 403 // Needed to ensure JNI correctly detects non-attached threads. 404 if (this == Thread::current()) { 405 clear_thread_current(); 406 } 407 408 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 409 } 410 411 // NOTE: dummy function for assertion purpose. 412 void Thread::run() { 413 ShouldNotReachHere(); 414 } 415 416 #ifdef ASSERT 417 // A JavaThread is considered "dangling" if it is not the current 418 // thread, has been added the Threads list, the system is not at a 419 // safepoint and the Thread is not "protected". 420 // 421 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 422 assert(!thread->is_Java_thread() || Thread::current() == thread || 423 !((JavaThread *) thread)->on_thread_list() || 424 SafepointSynchronize::is_at_safepoint() || 425 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 426 "possibility of dangling Thread pointer"); 427 } 428 #endif 429 430 ThreadPriority Thread::get_priority(const Thread* const thread) { 431 ThreadPriority priority; 432 // Can return an error! 433 (void)os::get_priority(thread, priority); 434 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 435 return priority; 436 } 437 438 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 439 debug_only(check_for_dangling_thread_pointer(thread);) 440 // Can return an error! 441 (void)os::set_priority(thread, priority); 442 } 443 444 445 void Thread::start(Thread* thread) { 446 // Start is different from resume in that its safety is guaranteed by context or 447 // being called from a Java method synchronized on the Thread object. 448 if (!DisableStartThread) { 449 if (thread->is_Java_thread()) { 450 // Initialize the thread state to RUNNABLE before starting this thread. 451 // Can not set it after the thread started because we do not know the 452 // exact thread state at that time. It could be in MONITOR_WAIT or 453 // in SLEEPING or some other state. 454 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 455 java_lang_Thread::RUNNABLE); 456 } 457 os::start_thread(thread); 458 } 459 } 460 461 // Enqueue a VM_Operation to do the job for us - sometime later 462 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 463 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 464 VMThread::execute(vm_stop); 465 } 466 467 468 // Check if an external suspend request has completed (or has been 469 // cancelled). Returns true if the thread is externally suspended and 470 // false otherwise. 471 // 472 // The bits parameter returns information about the code path through 473 // the routine. Useful for debugging: 474 // 475 // set in is_ext_suspend_completed(): 476 // 0x00000001 - routine was entered 477 // 0x00000010 - routine return false at end 478 // 0x00000100 - thread exited (return false) 479 // 0x00000200 - suspend request cancelled (return false) 480 // 0x00000400 - thread suspended (return true) 481 // 0x00001000 - thread is in a suspend equivalent state (return true) 482 // 0x00002000 - thread is native and walkable (return true) 483 // 0x00004000 - thread is native_trans and walkable (needed retry) 484 // 485 // set in wait_for_ext_suspend_completion(): 486 // 0x00010000 - routine was entered 487 // 0x00020000 - suspend request cancelled before loop (return false) 488 // 0x00040000 - thread suspended before loop (return true) 489 // 0x00080000 - suspend request cancelled in loop (return false) 490 // 0x00100000 - thread suspended in loop (return true) 491 // 0x00200000 - suspend not completed during retry loop (return false) 492 493 // Helper class for tracing suspend wait debug bits. 494 // 495 // 0x00000100 indicates that the target thread exited before it could 496 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 497 // 0x00080000 each indicate a cancelled suspend request so they don't 498 // count as wait failures either. 499 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 500 501 class TraceSuspendDebugBits : public StackObj { 502 private: 503 JavaThread * jt; 504 bool is_wait; 505 bool called_by_wait; // meaningful when !is_wait 506 uint32_t * bits; 507 508 public: 509 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 510 uint32_t *_bits) { 511 jt = _jt; 512 is_wait = _is_wait; 513 called_by_wait = _called_by_wait; 514 bits = _bits; 515 } 516 517 ~TraceSuspendDebugBits() { 518 if (!is_wait) { 519 #if 1 520 // By default, don't trace bits for is_ext_suspend_completed() calls. 521 // That trace is very chatty. 522 return; 523 #else 524 if (!called_by_wait) { 525 // If tracing for is_ext_suspend_completed() is enabled, then only 526 // trace calls to it from wait_for_ext_suspend_completion() 527 return; 528 } 529 #endif 530 } 531 532 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 533 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 534 MutexLocker ml(Threads_lock); // needed for get_thread_name() 535 ResourceMark rm; 536 537 tty->print_cr( 538 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 539 jt->get_thread_name(), *bits); 540 541 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 542 } 543 } 544 } 545 }; 546 #undef DEBUG_FALSE_BITS 547 548 549 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 550 uint32_t *bits) { 551 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 552 553 bool did_trans_retry = false; // only do thread_in_native_trans retry once 554 bool do_trans_retry; // flag to force the retry 555 556 *bits |= 0x00000001; 557 558 do { 559 do_trans_retry = false; 560 561 if (is_exiting()) { 562 // Thread is in the process of exiting. This is always checked 563 // first to reduce the risk of dereferencing a freed JavaThread. 564 *bits |= 0x00000100; 565 return false; 566 } 567 568 if (!is_external_suspend()) { 569 // Suspend request is cancelled. This is always checked before 570 // is_ext_suspended() to reduce the risk of a rogue resume 571 // confusing the thread that made the suspend request. 572 *bits |= 0x00000200; 573 return false; 574 } 575 576 if (is_ext_suspended()) { 577 // thread is suspended 578 *bits |= 0x00000400; 579 return true; 580 } 581 582 // Now that we no longer do hard suspends of threads running 583 // native code, the target thread can be changing thread state 584 // while we are in this routine: 585 // 586 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 587 // 588 // We save a copy of the thread state as observed at this moment 589 // and make our decision about suspend completeness based on the 590 // copy. This closes the race where the thread state is seen as 591 // _thread_in_native_trans in the if-thread_blocked check, but is 592 // seen as _thread_blocked in if-thread_in_native_trans check. 593 JavaThreadState save_state = thread_state(); 594 595 if (save_state == _thread_blocked && is_suspend_equivalent()) { 596 // If the thread's state is _thread_blocked and this blocking 597 // condition is known to be equivalent to a suspend, then we can 598 // consider the thread to be externally suspended. This means that 599 // the code that sets _thread_blocked has been modified to do 600 // self-suspension if the blocking condition releases. We also 601 // used to check for CONDVAR_WAIT here, but that is now covered by 602 // the _thread_blocked with self-suspension check. 603 // 604 // Return true since we wouldn't be here unless there was still an 605 // external suspend request. 606 *bits |= 0x00001000; 607 return true; 608 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 609 // Threads running native code will self-suspend on native==>VM/Java 610 // transitions. If its stack is walkable (should always be the case 611 // unless this function is called before the actual java_suspend() 612 // call), then the wait is done. 613 *bits |= 0x00002000; 614 return true; 615 } else if (!called_by_wait && !did_trans_retry && 616 save_state == _thread_in_native_trans && 617 frame_anchor()->walkable()) { 618 // The thread is transitioning from thread_in_native to another 619 // thread state. check_safepoint_and_suspend_for_native_trans() 620 // will force the thread to self-suspend. If it hasn't gotten 621 // there yet we may have caught the thread in-between the native 622 // code check above and the self-suspend. Lucky us. If we were 623 // called by wait_for_ext_suspend_completion(), then it 624 // will be doing the retries so we don't have to. 625 // 626 // Since we use the saved thread state in the if-statement above, 627 // there is a chance that the thread has already transitioned to 628 // _thread_blocked by the time we get here. In that case, we will 629 // make a single unnecessary pass through the logic below. This 630 // doesn't hurt anything since we still do the trans retry. 631 632 *bits |= 0x00004000; 633 634 // Once the thread leaves thread_in_native_trans for another 635 // thread state, we break out of this retry loop. We shouldn't 636 // need this flag to prevent us from getting back here, but 637 // sometimes paranoia is good. 638 did_trans_retry = true; 639 640 // We wait for the thread to transition to a more usable state. 641 for (int i = 1; i <= SuspendRetryCount; i++) { 642 // We used to do an "os::yield_all(i)" call here with the intention 643 // that yielding would increase on each retry. However, the parameter 644 // is ignored on Linux which means the yield didn't scale up. Waiting 645 // on the SR_lock below provides a much more predictable scale up for 646 // the delay. It also provides a simple/direct point to check for any 647 // safepoint requests from the VMThread 648 649 // temporarily drops SR_lock while doing wait with safepoint check 650 // (if we're a JavaThread - the WatcherThread can also call this) 651 // and increase delay with each retry 652 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 653 654 // check the actual thread state instead of what we saved above 655 if (thread_state() != _thread_in_native_trans) { 656 // the thread has transitioned to another thread state so 657 // try all the checks (except this one) one more time. 658 do_trans_retry = true; 659 break; 660 } 661 } // end retry loop 662 663 664 } 665 } while (do_trans_retry); 666 667 *bits |= 0x00000010; 668 return false; 669 } 670 671 // Wait for an external suspend request to complete (or be cancelled). 672 // Returns true if the thread is externally suspended and false otherwise. 673 // 674 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 675 uint32_t *bits) { 676 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 677 false /* !called_by_wait */, bits); 678 679 // local flag copies to minimize SR_lock hold time 680 bool is_suspended; 681 bool pending; 682 uint32_t reset_bits; 683 684 // set a marker so is_ext_suspend_completed() knows we are the caller 685 *bits |= 0x00010000; 686 687 // We use reset_bits to reinitialize the bits value at the top of 688 // each retry loop. This allows the caller to make use of any 689 // unused bits for their own marking purposes. 690 reset_bits = *bits; 691 692 { 693 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 694 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 695 delay, bits); 696 pending = is_external_suspend(); 697 } 698 // must release SR_lock to allow suspension to complete 699 700 if (!pending) { 701 // A cancelled suspend request is the only false return from 702 // is_ext_suspend_completed() that keeps us from entering the 703 // retry loop. 704 *bits |= 0x00020000; 705 return false; 706 } 707 708 if (is_suspended) { 709 *bits |= 0x00040000; 710 return true; 711 } 712 713 for (int i = 1; i <= retries; i++) { 714 *bits = reset_bits; // reinit to only track last retry 715 716 // We used to do an "os::yield_all(i)" call here with the intention 717 // that yielding would increase on each retry. However, the parameter 718 // is ignored on Linux which means the yield didn't scale up. Waiting 719 // on the SR_lock below provides a much more predictable scale up for 720 // the delay. It also provides a simple/direct point to check for any 721 // safepoint requests from the VMThread 722 723 { 724 MutexLocker ml(SR_lock()); 725 // wait with safepoint check (if we're a JavaThread - the WatcherThread 726 // can also call this) and increase delay with each retry 727 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 728 729 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 730 delay, bits); 731 732 // It is possible for the external suspend request to be cancelled 733 // (by a resume) before the actual suspend operation is completed. 734 // Refresh our local copy to see if we still need to wait. 735 pending = is_external_suspend(); 736 } 737 738 if (!pending) { 739 // A cancelled suspend request is the only false return from 740 // is_ext_suspend_completed() that keeps us from staying in the 741 // retry loop. 742 *bits |= 0x00080000; 743 return false; 744 } 745 746 if (is_suspended) { 747 *bits |= 0x00100000; 748 return true; 749 } 750 } // end retry loop 751 752 // thread did not suspend after all our retries 753 *bits |= 0x00200000; 754 return false; 755 } 756 757 // Called from API entry points which perform stack walking. If the 758 // associated JavaThread is the current thread, then wait_for_suspend 759 // is not used. Otherwise, it determines if we should wait for the 760 // "other" thread to complete external suspension. (NOTE: in future 761 // releases the suspension mechanism should be reimplemented so this 762 // is not necessary.) 763 // 764 bool 765 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 766 if (this != JavaThread::current()) { 767 // "other" threads require special handling. 768 if (wait_for_suspend) { 769 // We are allowed to wait for the external suspend to complete 770 // so give the other thread a chance to get suspended. 771 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 772 SuspendRetryDelay, bits)) { 773 // Didn't make it so let the caller know. 774 return false; 775 } 776 } 777 // We aren't allowed to wait for the external suspend to complete 778 // so if the other thread isn't externally suspended we need to 779 // let the caller know. 780 else if (!is_ext_suspend_completed_with_lock(bits)) { 781 return false; 782 } 783 } 784 785 return true; 786 } 787 788 #ifndef PRODUCT 789 void JavaThread::record_jump(address target, address instr, const char* file, 790 int line) { 791 792 // This should not need to be atomic as the only way for simultaneous 793 // updates is via interrupts. Even then this should be rare or non-existent 794 // and we don't care that much anyway. 795 796 int index = _jmp_ring_index; 797 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 798 _jmp_ring[index]._target = (intptr_t) target; 799 _jmp_ring[index]._instruction = (intptr_t) instr; 800 _jmp_ring[index]._file = file; 801 _jmp_ring[index]._line = line; 802 } 803 #endif // PRODUCT 804 805 void Thread::interrupt(Thread* thread) { 806 debug_only(check_for_dangling_thread_pointer(thread);) 807 os::interrupt(thread); 808 } 809 810 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 811 debug_only(check_for_dangling_thread_pointer(thread);) 812 // Note: If clear_interrupted==false, this simply fetches and 813 // returns the value of the field osthread()->interrupted(). 814 return os::is_interrupted(thread, clear_interrupted); 815 } 816 817 818 // GC Support 819 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 820 int thread_parity = _oops_do_parity; 821 if (thread_parity != strong_roots_parity) { 822 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 823 if (res == thread_parity) { 824 return true; 825 } else { 826 guarantee(res == strong_roots_parity, "Or else what?"); 827 return false; 828 } 829 } 830 return false; 831 } 832 833 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 834 active_handles()->oops_do(f); 835 // Do oop for ThreadShadow 836 f->do_oop((oop*)&_pending_exception); 837 handle_area()->oops_do(f); 838 839 if (MonitorInUseLists) { 840 // When using thread local monitor lists, we scan them here, 841 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 842 ObjectSynchronizer::thread_local_used_oops_do(this, f); 843 } 844 } 845 846 void Thread::metadata_handles_do(void f(Metadata*)) { 847 // Only walk the Handles in Thread. 848 if (metadata_handles() != NULL) { 849 for (int i = 0; i< metadata_handles()->length(); i++) { 850 f(metadata_handles()->at(i)); 851 } 852 } 853 } 854 855 void Thread::print_on(outputStream* st) const { 856 // get_priority assumes osthread initialized 857 if (osthread() != NULL) { 858 int os_prio; 859 if (os::get_native_priority(this, &os_prio) == OS_OK) { 860 st->print("os_prio=%d ", os_prio); 861 } 862 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 863 osthread()->print_on(st); 864 } 865 if (_threads_hazard_ptr != NULL) { 866 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 867 } 868 if (_nested_threads_hazard_ptr != NULL) { 869 print_nested_threads_hazard_ptrs_on(st); 870 } 871 st->print(" "); 872 debug_only(if (WizardMode) print_owned_locks_on(st);) 873 } 874 875 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const { 876 assert(_nested_threads_hazard_ptr != NULL, "must be set to print"); 877 878 if (EnableThreadSMRStatistics) { 879 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt); 880 } 881 st->print(", _nested_threads_hazard_ptrs="); 882 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL; 883 node = node->next()) { 884 if (node != _nested_threads_hazard_ptr) { 885 // First node does not need a comma-space separator. 886 st->print(", "); 887 } 888 st->print(INTPTR_FORMAT, p2i(node->t_list())); 889 } 890 } 891 892 // Thread::print_on_error() is called by fatal error handler. Don't use 893 // any lock or allocate memory. 894 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 895 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 896 897 if (is_VM_thread()) { st->print("VMThread"); } 898 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 899 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 900 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 901 else { st->print("Thread"); } 902 903 if (is_Named_thread()) { 904 st->print(" \"%s\"", name()); 905 } 906 907 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 908 p2i(stack_end()), p2i(stack_base())); 909 910 if (osthread()) { 911 st->print(" [id=%d]", osthread()->thread_id()); 912 } 913 914 if (_threads_hazard_ptr != NULL) { 915 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 916 } 917 if (_nested_threads_hazard_ptr != NULL) { 918 print_nested_threads_hazard_ptrs_on(st); 919 } 920 } 921 922 void Thread::print_value_on(outputStream* st) const { 923 if (is_Named_thread()) { 924 st->print(" \"%s\" ", name()); 925 } 926 st->print(INTPTR_FORMAT, p2i(this)); // print address 927 } 928 929 #ifdef ASSERT 930 void Thread::print_owned_locks_on(outputStream* st) const { 931 Monitor *cur = _owned_locks; 932 if (cur == NULL) { 933 st->print(" (no locks) "); 934 } else { 935 st->print_cr(" Locks owned:"); 936 while (cur) { 937 cur->print_on(st); 938 cur = cur->next(); 939 } 940 } 941 } 942 943 static int ref_use_count = 0; 944 945 bool Thread::owns_locks_but_compiled_lock() const { 946 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 947 if (cur != Compile_lock) return true; 948 } 949 return false; 950 } 951 952 953 #endif 954 955 #ifndef PRODUCT 956 957 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 958 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 959 // no threads which allow_vm_block's are held 960 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 961 // Check if current thread is allowed to block at a safepoint 962 if (!(_allow_safepoint_count == 0)) { 963 fatal("Possible safepoint reached by thread that does not allow it"); 964 } 965 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 966 fatal("LEAF method calling lock?"); 967 } 968 969 #ifdef ASSERT 970 if (potential_vm_operation && is_Java_thread() 971 && !Universe::is_bootstrapping()) { 972 // Make sure we do not hold any locks that the VM thread also uses. 973 // This could potentially lead to deadlocks 974 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 975 // Threads_lock is special, since the safepoint synchronization will not start before this is 976 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 977 // since it is used to transfer control between JavaThreads and the VMThread 978 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 979 if ((cur->allow_vm_block() && 980 cur != Threads_lock && 981 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 982 cur != VMOperationRequest_lock && 983 cur != VMOperationQueue_lock) || 984 cur->rank() == Mutex::special) { 985 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 986 } 987 } 988 } 989 990 if (GCALotAtAllSafepoints) { 991 // We could enter a safepoint here and thus have a gc 992 InterfaceSupport::check_gc_alot(); 993 } 994 #endif 995 } 996 #endif 997 998 bool Thread::is_in_stack(address adr) const { 999 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1000 address end = os::current_stack_pointer(); 1001 // Allow non Java threads to call this without stack_base 1002 if (_stack_base == NULL) return true; 1003 if (stack_base() >= adr && adr >= end) return true; 1004 1005 return false; 1006 } 1007 1008 bool Thread::is_in_usable_stack(address adr) const { 1009 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1010 size_t usable_stack_size = _stack_size - stack_guard_size; 1011 1012 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1013 } 1014 1015 1016 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1017 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1018 // used for compilation in the future. If that change is made, the need for these methods 1019 // should be revisited, and they should be removed if possible. 1020 1021 bool Thread::is_lock_owned(address adr) const { 1022 return on_local_stack(adr); 1023 } 1024 1025 bool Thread::set_as_starting_thread() { 1026 // NOTE: this must be called inside the main thread. 1027 return os::create_main_thread((JavaThread*)this); 1028 } 1029 1030 static void initialize_class(Symbol* class_name, TRAPS) { 1031 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1032 InstanceKlass::cast(klass)->initialize(CHECK); 1033 } 1034 1035 1036 // Creates the initial ThreadGroup 1037 static Handle create_initial_thread_group(TRAPS) { 1038 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 1039 InstanceKlass* ik = InstanceKlass::cast(k); 1040 1041 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 1042 { 1043 JavaValue result(T_VOID); 1044 JavaCalls::call_special(&result, 1045 system_instance, 1046 ik, 1047 vmSymbols::object_initializer_name(), 1048 vmSymbols::void_method_signature(), 1049 CHECK_NH); 1050 } 1051 Universe::set_system_thread_group(system_instance()); 1052 1053 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 1054 { 1055 JavaValue result(T_VOID); 1056 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1057 JavaCalls::call_special(&result, 1058 main_instance, 1059 ik, 1060 vmSymbols::object_initializer_name(), 1061 vmSymbols::threadgroup_string_void_signature(), 1062 system_instance, 1063 string, 1064 CHECK_NH); 1065 } 1066 return main_instance; 1067 } 1068 1069 // Creates the initial Thread 1070 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1071 TRAPS) { 1072 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 1073 InstanceKlass* ik = InstanceKlass::cast(k); 1074 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1075 1076 java_lang_Thread::set_thread(thread_oop(), thread); 1077 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1078 thread->set_threadObj(thread_oop()); 1079 1080 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1081 1082 JavaValue result(T_VOID); 1083 JavaCalls::call_special(&result, thread_oop, 1084 ik, 1085 vmSymbols::object_initializer_name(), 1086 vmSymbols::threadgroup_string_void_signature(), 1087 thread_group, 1088 string, 1089 CHECK_NULL); 1090 return thread_oop(); 1091 } 1092 1093 char java_runtime_name[128] = ""; 1094 char java_runtime_version[128] = ""; 1095 1096 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1097 static const char* get_java_runtime_name(TRAPS) { 1098 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1099 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1100 fieldDescriptor fd; 1101 bool found = k != NULL && 1102 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1103 vmSymbols::string_signature(), &fd); 1104 if (found) { 1105 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1106 if (name_oop == NULL) { 1107 return NULL; 1108 } 1109 const char* name = java_lang_String::as_utf8_string(name_oop, 1110 java_runtime_name, 1111 sizeof(java_runtime_name)); 1112 return name; 1113 } else { 1114 return NULL; 1115 } 1116 } 1117 1118 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1119 static const char* get_java_runtime_version(TRAPS) { 1120 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1121 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1122 fieldDescriptor fd; 1123 bool found = k != NULL && 1124 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1125 vmSymbols::string_signature(), &fd); 1126 if (found) { 1127 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1128 if (name_oop == NULL) { 1129 return NULL; 1130 } 1131 const char* name = java_lang_String::as_utf8_string(name_oop, 1132 java_runtime_version, 1133 sizeof(java_runtime_version)); 1134 return name; 1135 } else { 1136 return NULL; 1137 } 1138 } 1139 1140 // General purpose hook into Java code, run once when the VM is initialized. 1141 // The Java library method itself may be changed independently from the VM. 1142 static void call_postVMInitHook(TRAPS) { 1143 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1144 if (klass != NULL) { 1145 JavaValue result(T_VOID); 1146 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1147 vmSymbols::void_method_signature(), 1148 CHECK); 1149 } 1150 } 1151 1152 static void reset_vm_info_property(TRAPS) { 1153 // the vm info string 1154 ResourceMark rm(THREAD); 1155 const char *vm_info = VM_Version::vm_info_string(); 1156 1157 // java.lang.System class 1158 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1159 1160 // setProperty arguments 1161 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1162 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1163 1164 // return value 1165 JavaValue r(T_OBJECT); 1166 1167 // public static String setProperty(String key, String value); 1168 JavaCalls::call_static(&r, 1169 klass, 1170 vmSymbols::setProperty_name(), 1171 vmSymbols::string_string_string_signature(), 1172 key_str, 1173 value_str, 1174 CHECK); 1175 } 1176 1177 1178 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1179 bool daemon, TRAPS) { 1180 assert(thread_group.not_null(), "thread group should be specified"); 1181 assert(threadObj() == NULL, "should only create Java thread object once"); 1182 1183 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1184 InstanceKlass* ik = InstanceKlass::cast(k); 1185 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1186 1187 java_lang_Thread::set_thread(thread_oop(), this); 1188 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1189 set_threadObj(thread_oop()); 1190 1191 JavaValue result(T_VOID); 1192 if (thread_name != NULL) { 1193 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1194 // Thread gets assigned specified name and null target 1195 JavaCalls::call_special(&result, 1196 thread_oop, 1197 ik, 1198 vmSymbols::object_initializer_name(), 1199 vmSymbols::threadgroup_string_void_signature(), 1200 thread_group, // Argument 1 1201 name, // Argument 2 1202 THREAD); 1203 } else { 1204 // Thread gets assigned name "Thread-nnn" and null target 1205 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1206 JavaCalls::call_special(&result, 1207 thread_oop, 1208 ik, 1209 vmSymbols::object_initializer_name(), 1210 vmSymbols::threadgroup_runnable_void_signature(), 1211 thread_group, // Argument 1 1212 Handle(), // Argument 2 1213 THREAD); 1214 } 1215 1216 1217 if (daemon) { 1218 java_lang_Thread::set_daemon(thread_oop()); 1219 } 1220 1221 if (HAS_PENDING_EXCEPTION) { 1222 return; 1223 } 1224 1225 Klass* group = SystemDictionary::ThreadGroup_klass(); 1226 Handle threadObj(THREAD, this->threadObj()); 1227 1228 JavaCalls::call_special(&result, 1229 thread_group, 1230 group, 1231 vmSymbols::add_method_name(), 1232 vmSymbols::thread_void_signature(), 1233 threadObj, // Arg 1 1234 THREAD); 1235 } 1236 1237 // NamedThread -- non-JavaThread subclasses with multiple 1238 // uniquely named instances should derive from this. 1239 NamedThread::NamedThread() : Thread() { 1240 _name = NULL; 1241 _processed_thread = NULL; 1242 _gc_id = GCId::undefined(); 1243 } 1244 1245 NamedThread::~NamedThread() { 1246 if (_name != NULL) { 1247 FREE_C_HEAP_ARRAY(char, _name); 1248 _name = NULL; 1249 } 1250 } 1251 1252 void NamedThread::set_name(const char* format, ...) { 1253 guarantee(_name == NULL, "Only get to set name once."); 1254 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1255 guarantee(_name != NULL, "alloc failure"); 1256 va_list ap; 1257 va_start(ap, format); 1258 jio_vsnprintf(_name, max_name_len, format, ap); 1259 va_end(ap); 1260 } 1261 1262 void NamedThread::initialize_named_thread() { 1263 set_native_thread_name(name()); 1264 } 1265 1266 void NamedThread::print_on(outputStream* st) const { 1267 st->print("\"%s\" ", name()); 1268 Thread::print_on(st); 1269 st->cr(); 1270 } 1271 1272 1273 // ======= WatcherThread ======== 1274 1275 // The watcher thread exists to simulate timer interrupts. It should 1276 // be replaced by an abstraction over whatever native support for 1277 // timer interrupts exists on the platform. 1278 1279 WatcherThread* WatcherThread::_watcher_thread = NULL; 1280 bool WatcherThread::_startable = false; 1281 volatile bool WatcherThread::_should_terminate = false; 1282 1283 WatcherThread::WatcherThread() : Thread() { 1284 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1285 if (os::create_thread(this, os::watcher_thread)) { 1286 _watcher_thread = this; 1287 1288 // Set the watcher thread to the highest OS priority which should not be 1289 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1290 // is created. The only normal thread using this priority is the reference 1291 // handler thread, which runs for very short intervals only. 1292 // If the VMThread's priority is not lower than the WatcherThread profiling 1293 // will be inaccurate. 1294 os::set_priority(this, MaxPriority); 1295 if (!DisableStartThread) { 1296 os::start_thread(this); 1297 } 1298 } 1299 } 1300 1301 int WatcherThread::sleep() const { 1302 // The WatcherThread does not participate in the safepoint protocol 1303 // for the PeriodicTask_lock because it is not a JavaThread. 1304 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1305 1306 if (_should_terminate) { 1307 // check for termination before we do any housekeeping or wait 1308 return 0; // we did not sleep. 1309 } 1310 1311 // remaining will be zero if there are no tasks, 1312 // causing the WatcherThread to sleep until a task is 1313 // enrolled 1314 int remaining = PeriodicTask::time_to_wait(); 1315 int time_slept = 0; 1316 1317 // we expect this to timeout - we only ever get unparked when 1318 // we should terminate or when a new task has been enrolled 1319 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1320 1321 jlong time_before_loop = os::javaTimeNanos(); 1322 1323 while (true) { 1324 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1325 remaining); 1326 jlong now = os::javaTimeNanos(); 1327 1328 if (remaining == 0) { 1329 // if we didn't have any tasks we could have waited for a long time 1330 // consider the time_slept zero and reset time_before_loop 1331 time_slept = 0; 1332 time_before_loop = now; 1333 } else { 1334 // need to recalculate since we might have new tasks in _tasks 1335 time_slept = (int) ((now - time_before_loop) / 1000000); 1336 } 1337 1338 // Change to task list or spurious wakeup of some kind 1339 if (timedout || _should_terminate) { 1340 break; 1341 } 1342 1343 remaining = PeriodicTask::time_to_wait(); 1344 if (remaining == 0) { 1345 // Last task was just disenrolled so loop around and wait until 1346 // another task gets enrolled 1347 continue; 1348 } 1349 1350 remaining -= time_slept; 1351 if (remaining <= 0) { 1352 break; 1353 } 1354 } 1355 1356 return time_slept; 1357 } 1358 1359 void WatcherThread::run() { 1360 assert(this == watcher_thread(), "just checking"); 1361 1362 this->record_stack_base_and_size(); 1363 this->set_native_thread_name(this->name()); 1364 this->set_active_handles(JNIHandleBlock::allocate_block()); 1365 while (true) { 1366 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1367 assert(watcher_thread() == this, "thread consistency check"); 1368 1369 // Calculate how long it'll be until the next PeriodicTask work 1370 // should be done, and sleep that amount of time. 1371 int time_waited = sleep(); 1372 1373 if (VMError::is_error_reported()) { 1374 // A fatal error has happened, the error handler(VMError::report_and_die) 1375 // should abort JVM after creating an error log file. However in some 1376 // rare cases, the error handler itself might deadlock. Here periodically 1377 // check for error reporting timeouts, and if it happens, just proceed to 1378 // abort the VM. 1379 1380 // This code is in WatcherThread because WatcherThread wakes up 1381 // periodically so the fatal error handler doesn't need to do anything; 1382 // also because the WatcherThread is less likely to crash than other 1383 // threads. 1384 1385 for (;;) { 1386 // Note: we use naked sleep in this loop because we want to avoid using 1387 // any kind of VM infrastructure which may be broken at this point. 1388 if (VMError::check_timeout()) { 1389 // We hit error reporting timeout. Error reporting was interrupted and 1390 // will be wrapping things up now (closing files etc). Give it some more 1391 // time, then quit the VM. 1392 os::naked_short_sleep(200); 1393 // Print a message to stderr. 1394 fdStream err(defaultStream::output_fd()); 1395 err.print_raw_cr("# [ timer expired, abort... ]"); 1396 // skip atexit/vm_exit/vm_abort hooks 1397 os::die(); 1398 } 1399 1400 // Wait a second, then recheck for timeout. 1401 os::naked_short_sleep(999); 1402 } 1403 } 1404 1405 if (_should_terminate) { 1406 // check for termination before posting the next tick 1407 break; 1408 } 1409 1410 PeriodicTask::real_time_tick(time_waited); 1411 } 1412 1413 // Signal that it is terminated 1414 { 1415 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1416 _watcher_thread = NULL; 1417 Terminator_lock->notify(); 1418 } 1419 } 1420 1421 void WatcherThread::start() { 1422 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1423 1424 if (watcher_thread() == NULL && _startable) { 1425 _should_terminate = false; 1426 // Create the single instance of WatcherThread 1427 new WatcherThread(); 1428 } 1429 } 1430 1431 void WatcherThread::make_startable() { 1432 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1433 _startable = true; 1434 } 1435 1436 void WatcherThread::stop() { 1437 { 1438 // Follow normal safepoint aware lock enter protocol since the 1439 // WatcherThread is stopped by another JavaThread. 1440 MutexLocker ml(PeriodicTask_lock); 1441 _should_terminate = true; 1442 1443 WatcherThread* watcher = watcher_thread(); 1444 if (watcher != NULL) { 1445 // unpark the WatcherThread so it can see that it should terminate 1446 watcher->unpark(); 1447 } 1448 } 1449 1450 MutexLocker mu(Terminator_lock); 1451 1452 while (watcher_thread() != NULL) { 1453 // This wait should make safepoint checks, wait without a timeout, 1454 // and wait as a suspend-equivalent condition. 1455 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1456 Mutex::_as_suspend_equivalent_flag); 1457 } 1458 } 1459 1460 void WatcherThread::unpark() { 1461 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1462 PeriodicTask_lock->notify(); 1463 } 1464 1465 void WatcherThread::print_on(outputStream* st) const { 1466 st->print("\"%s\" ", name()); 1467 Thread::print_on(st); 1468 st->cr(); 1469 } 1470 1471 // ======= JavaThread ======== 1472 1473 #if INCLUDE_JVMCI 1474 1475 jlong* JavaThread::_jvmci_old_thread_counters; 1476 1477 bool jvmci_counters_include(JavaThread* thread) { 1478 oop threadObj = thread->threadObj(); 1479 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1480 } 1481 1482 void JavaThread::collect_counters(typeArrayOop array) { 1483 if (JVMCICounterSize > 0) { 1484 MutexLocker tl(Threads_lock); 1485 JavaThreadIteratorWithHandle jtiwh; 1486 for (int i = 0; i < array->length(); i++) { 1487 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1488 } 1489 for (; JavaThread *tp = jtiwh.next(); ) { 1490 if (jvmci_counters_include(tp)) { 1491 for (int i = 0; i < array->length(); i++) { 1492 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1493 } 1494 } 1495 } 1496 } 1497 } 1498 1499 #endif // INCLUDE_JVMCI 1500 1501 // A JavaThread is a normal Java thread 1502 1503 void JavaThread::initialize() { 1504 // Initialize fields 1505 1506 set_saved_exception_pc(NULL); 1507 set_threadObj(NULL); 1508 _anchor.clear(); 1509 set_entry_point(NULL); 1510 set_jni_functions(jni_functions()); 1511 set_callee_target(NULL); 1512 set_vm_result(NULL); 1513 set_vm_result_2(NULL); 1514 set_vframe_array_head(NULL); 1515 set_vframe_array_last(NULL); 1516 set_deferred_locals(NULL); 1517 set_deopt_mark(NULL); 1518 set_deopt_compiled_method(NULL); 1519 clear_must_deopt_id(); 1520 set_monitor_chunks(NULL); 1521 set_next(NULL); 1522 _on_thread_list = false; 1523 set_thread_state(_thread_new); 1524 _terminated = _not_terminated; 1525 _privileged_stack_top = NULL; 1526 _array_for_gc = NULL; 1527 _suspend_equivalent = false; 1528 _in_deopt_handler = 0; 1529 _doing_unsafe_access = false; 1530 _stack_guard_state = stack_guard_unused; 1531 #if INCLUDE_JVMCI 1532 _pending_monitorenter = false; 1533 _pending_deoptimization = -1; 1534 _pending_failed_speculation = NULL; 1535 _pending_transfer_to_interpreter = false; 1536 _adjusting_comp_level = false; 1537 _jvmci._alternate_call_target = NULL; 1538 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1539 if (JVMCICounterSize > 0) { 1540 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1541 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1542 } else { 1543 _jvmci_counters = NULL; 1544 } 1545 #endif // INCLUDE_JVMCI 1546 _reserved_stack_activation = NULL; // stack base not known yet 1547 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1548 _exception_pc = 0; 1549 _exception_handler_pc = 0; 1550 _is_method_handle_return = 0; 1551 _jvmti_thread_state= NULL; 1552 _should_post_on_exceptions_flag = JNI_FALSE; 1553 _jvmti_get_loaded_classes_closure = NULL; 1554 _interp_only_mode = 0; 1555 _special_runtime_exit_condition = _no_async_condition; 1556 _pending_async_exception = NULL; 1557 _thread_stat = NULL; 1558 _thread_stat = new ThreadStatistics(); 1559 _blocked_on_compilation = false; 1560 _jni_active_critical = 0; 1561 _pending_jni_exception_check_fn = NULL; 1562 _do_not_unlock_if_synchronized = false; 1563 _cached_monitor_info = NULL; 1564 _parker = Parker::Allocate(this); 1565 1566 #ifndef PRODUCT 1567 _jmp_ring_index = 0; 1568 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1569 record_jump(NULL, NULL, NULL, 0); 1570 } 1571 #endif // PRODUCT 1572 1573 // Setup safepoint state info for this thread 1574 ThreadSafepointState::create(this); 1575 1576 debug_only(_java_call_counter = 0); 1577 1578 // JVMTI PopFrame support 1579 _popframe_condition = popframe_inactive; 1580 _popframe_preserved_args = NULL; 1581 _popframe_preserved_args_size = 0; 1582 _frames_to_pop_failed_realloc = 0; 1583 1584 if (SafepointMechanism::uses_thread_local_poll()) { 1585 SafepointMechanism::initialize_header(this); 1586 } 1587 1588 pd_initialize(); 1589 } 1590 1591 #if INCLUDE_ALL_GCS 1592 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1593 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1594 #endif // INCLUDE_ALL_GCS 1595 1596 JavaThread::JavaThread(bool is_attaching_via_jni) : 1597 Thread() 1598 #if INCLUDE_ALL_GCS 1599 , _satb_mark_queue(&_satb_mark_queue_set), 1600 _dirty_card_queue(&_dirty_card_queue_set) 1601 #endif // INCLUDE_ALL_GCS 1602 { 1603 initialize(); 1604 if (is_attaching_via_jni) { 1605 _jni_attach_state = _attaching_via_jni; 1606 } else { 1607 _jni_attach_state = _not_attaching_via_jni; 1608 } 1609 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1610 } 1611 1612 bool JavaThread::reguard_stack(address cur_sp) { 1613 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1614 && _stack_guard_state != stack_guard_reserved_disabled) { 1615 return true; // Stack already guarded or guard pages not needed. 1616 } 1617 1618 if (register_stack_overflow()) { 1619 // For those architectures which have separate register and 1620 // memory stacks, we must check the register stack to see if 1621 // it has overflowed. 1622 return false; 1623 } 1624 1625 // Java code never executes within the yellow zone: the latter is only 1626 // there to provoke an exception during stack banging. If java code 1627 // is executing there, either StackShadowPages should be larger, or 1628 // some exception code in c1, c2 or the interpreter isn't unwinding 1629 // when it should. 1630 guarantee(cur_sp > stack_reserved_zone_base(), 1631 "not enough space to reguard - increase StackShadowPages"); 1632 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1633 enable_stack_yellow_reserved_zone(); 1634 if (reserved_stack_activation() != stack_base()) { 1635 set_reserved_stack_activation(stack_base()); 1636 } 1637 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1638 set_reserved_stack_activation(stack_base()); 1639 enable_stack_reserved_zone(); 1640 } 1641 return true; 1642 } 1643 1644 bool JavaThread::reguard_stack(void) { 1645 return reguard_stack(os::current_stack_pointer()); 1646 } 1647 1648 1649 void JavaThread::block_if_vm_exited() { 1650 if (_terminated == _vm_exited) { 1651 // _vm_exited is set at safepoint, and Threads_lock is never released 1652 // we will block here forever 1653 Threads_lock->lock_without_safepoint_check(); 1654 ShouldNotReachHere(); 1655 } 1656 } 1657 1658 1659 // Remove this ifdef when C1 is ported to the compiler interface. 1660 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1661 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1662 1663 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1664 Thread() 1665 #if INCLUDE_ALL_GCS 1666 , _satb_mark_queue(&_satb_mark_queue_set), 1667 _dirty_card_queue(&_dirty_card_queue_set) 1668 #endif // INCLUDE_ALL_GCS 1669 { 1670 initialize(); 1671 _jni_attach_state = _not_attaching_via_jni; 1672 set_entry_point(entry_point); 1673 // Create the native thread itself. 1674 // %note runtime_23 1675 os::ThreadType thr_type = os::java_thread; 1676 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1677 os::java_thread; 1678 os::create_thread(this, thr_type, stack_sz); 1679 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1680 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1681 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1682 // the exception consists of creating the exception object & initializing it, initialization 1683 // will leave the VM via a JavaCall and then all locks must be unlocked). 1684 // 1685 // The thread is still suspended when we reach here. Thread must be explicit started 1686 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1687 // by calling Threads:add. The reason why this is not done here, is because the thread 1688 // object must be fully initialized (take a look at JVM_Start) 1689 } 1690 1691 JavaThread::~JavaThread() { 1692 1693 // JSR166 -- return the parker to the free list 1694 Parker::Release(_parker); 1695 _parker = NULL; 1696 1697 // Free any remaining previous UnrollBlock 1698 vframeArray* old_array = vframe_array_last(); 1699 1700 if (old_array != NULL) { 1701 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1702 old_array->set_unroll_block(NULL); 1703 delete old_info; 1704 delete old_array; 1705 } 1706 1707 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1708 if (deferred != NULL) { 1709 // This can only happen if thread is destroyed before deoptimization occurs. 1710 assert(deferred->length() != 0, "empty array!"); 1711 do { 1712 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1713 deferred->remove_at(0); 1714 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1715 delete dlv; 1716 } while (deferred->length() != 0); 1717 delete deferred; 1718 } 1719 1720 // All Java related clean up happens in exit 1721 ThreadSafepointState::destroy(this); 1722 if (_thread_stat != NULL) delete _thread_stat; 1723 1724 #if INCLUDE_JVMCI 1725 if (JVMCICounterSize > 0) { 1726 if (jvmci_counters_include(this)) { 1727 for (int i = 0; i < JVMCICounterSize; i++) { 1728 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1729 } 1730 } 1731 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1732 } 1733 #endif // INCLUDE_JVMCI 1734 } 1735 1736 1737 // The first routine called by a new Java thread 1738 void JavaThread::run() { 1739 // initialize thread-local alloc buffer related fields 1740 this->initialize_tlab(); 1741 1742 // used to test validity of stack trace backs 1743 this->record_base_of_stack_pointer(); 1744 1745 // Record real stack base and size. 1746 this->record_stack_base_and_size(); 1747 1748 this->create_stack_guard_pages(); 1749 1750 this->cache_global_variables(); 1751 1752 // Thread is now sufficient initialized to be handled by the safepoint code as being 1753 // in the VM. Change thread state from _thread_new to _thread_in_vm 1754 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1755 1756 assert(JavaThread::current() == this, "sanity check"); 1757 assert(!Thread::current()->owns_locks(), "sanity check"); 1758 1759 DTRACE_THREAD_PROBE(start, this); 1760 1761 // This operation might block. We call that after all safepoint checks for a new thread has 1762 // been completed. 1763 this->set_active_handles(JNIHandleBlock::allocate_block()); 1764 1765 if (JvmtiExport::should_post_thread_life()) { 1766 JvmtiExport::post_thread_start(this); 1767 } 1768 1769 EventThreadStart event; 1770 if (event.should_commit()) { 1771 event.set_thread(THREAD_TRACE_ID(this)); 1772 event.commit(); 1773 } 1774 1775 // We call another function to do the rest so we are sure that the stack addresses used 1776 // from there will be lower than the stack base just computed 1777 thread_main_inner(); 1778 1779 // Note, thread is no longer valid at this point! 1780 } 1781 1782 1783 void JavaThread::thread_main_inner() { 1784 assert(JavaThread::current() == this, "sanity check"); 1785 assert(this->threadObj() != NULL, "just checking"); 1786 1787 // Execute thread entry point unless this thread has a pending exception 1788 // or has been stopped before starting. 1789 // Note: Due to JVM_StopThread we can have pending exceptions already! 1790 if (!this->has_pending_exception() && 1791 !java_lang_Thread::is_stillborn(this->threadObj())) { 1792 { 1793 ResourceMark rm(this); 1794 this->set_native_thread_name(this->get_thread_name()); 1795 } 1796 HandleMark hm(this); 1797 this->entry_point()(this, this); 1798 } 1799 1800 DTRACE_THREAD_PROBE(stop, this); 1801 1802 this->exit(false); 1803 this->smr_delete(); 1804 } 1805 1806 1807 static void ensure_join(JavaThread* thread) { 1808 // We do not need to grab the Threads_lock, since we are operating on ourself. 1809 Handle threadObj(thread, thread->threadObj()); 1810 assert(threadObj.not_null(), "java thread object must exist"); 1811 ObjectLocker lock(threadObj, thread); 1812 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1813 thread->clear_pending_exception(); 1814 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1815 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1816 // Clear the native thread instance - this makes isAlive return false and allows the join() 1817 // to complete once we've done the notify_all below 1818 java_lang_Thread::set_thread(threadObj(), NULL); 1819 lock.notify_all(thread); 1820 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1821 thread->clear_pending_exception(); 1822 } 1823 1824 1825 // For any new cleanup additions, please check to see if they need to be applied to 1826 // cleanup_failed_attach_current_thread as well. 1827 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1828 assert(this == JavaThread::current(), "thread consistency check"); 1829 1830 elapsedTimer _timer_exit_phase1; 1831 elapsedTimer _timer_exit_phase2; 1832 elapsedTimer _timer_exit_phase3; 1833 elapsedTimer _timer_exit_phase4; 1834 1835 if (log_is_enabled(Debug, os, thread, timer)) { 1836 _timer_exit_phase1.start(); 1837 } 1838 1839 HandleMark hm(this); 1840 Handle uncaught_exception(this, this->pending_exception()); 1841 this->clear_pending_exception(); 1842 Handle threadObj(this, this->threadObj()); 1843 assert(threadObj.not_null(), "Java thread object should be created"); 1844 1845 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1846 { 1847 EXCEPTION_MARK; 1848 1849 CLEAR_PENDING_EXCEPTION; 1850 } 1851 if (!destroy_vm) { 1852 if (uncaught_exception.not_null()) { 1853 EXCEPTION_MARK; 1854 // Call method Thread.dispatchUncaughtException(). 1855 Klass* thread_klass = SystemDictionary::Thread_klass(); 1856 JavaValue result(T_VOID); 1857 JavaCalls::call_virtual(&result, 1858 threadObj, thread_klass, 1859 vmSymbols::dispatchUncaughtException_name(), 1860 vmSymbols::throwable_void_signature(), 1861 uncaught_exception, 1862 THREAD); 1863 if (HAS_PENDING_EXCEPTION) { 1864 ResourceMark rm(this); 1865 jio_fprintf(defaultStream::error_stream(), 1866 "\nException: %s thrown from the UncaughtExceptionHandler" 1867 " in thread \"%s\"\n", 1868 pending_exception()->klass()->external_name(), 1869 get_thread_name()); 1870 CLEAR_PENDING_EXCEPTION; 1871 } 1872 } 1873 1874 // Called before the java thread exit since we want to read info 1875 // from java_lang_Thread object 1876 EventThreadEnd event; 1877 if (event.should_commit()) { 1878 event.set_thread(THREAD_TRACE_ID(this)); 1879 event.commit(); 1880 } 1881 1882 // Call after last event on thread 1883 EVENT_THREAD_EXIT(this); 1884 1885 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1886 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1887 // is deprecated anyhow. 1888 if (!is_Compiler_thread()) { 1889 int count = 3; 1890 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1891 EXCEPTION_MARK; 1892 JavaValue result(T_VOID); 1893 Klass* thread_klass = SystemDictionary::Thread_klass(); 1894 JavaCalls::call_virtual(&result, 1895 threadObj, thread_klass, 1896 vmSymbols::exit_method_name(), 1897 vmSymbols::void_method_signature(), 1898 THREAD); 1899 CLEAR_PENDING_EXCEPTION; 1900 } 1901 } 1902 // notify JVMTI 1903 if (JvmtiExport::should_post_thread_life()) { 1904 JvmtiExport::post_thread_end(this); 1905 } 1906 1907 // We have notified the agents that we are exiting, before we go on, 1908 // we must check for a pending external suspend request and honor it 1909 // in order to not surprise the thread that made the suspend request. 1910 while (true) { 1911 { 1912 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1913 if (!is_external_suspend()) { 1914 set_terminated(_thread_exiting); 1915 ThreadService::current_thread_exiting(this); 1916 break; 1917 } 1918 // Implied else: 1919 // Things get a little tricky here. We have a pending external 1920 // suspend request, but we are holding the SR_lock so we 1921 // can't just self-suspend. So we temporarily drop the lock 1922 // and then self-suspend. 1923 } 1924 1925 ThreadBlockInVM tbivm(this); 1926 java_suspend_self(); 1927 1928 // We're done with this suspend request, but we have to loop around 1929 // and check again. Eventually we will get SR_lock without a pending 1930 // external suspend request and will be able to mark ourselves as 1931 // exiting. 1932 } 1933 // no more external suspends are allowed at this point 1934 } else { 1935 // before_exit() has already posted JVMTI THREAD_END events 1936 } 1937 1938 if (log_is_enabled(Debug, os, thread, timer)) { 1939 _timer_exit_phase1.stop(); 1940 _timer_exit_phase2.start(); 1941 } 1942 // Notify waiters on thread object. This has to be done after exit() is called 1943 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1944 // group should have the destroyed bit set before waiters are notified). 1945 ensure_join(this); 1946 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1947 1948 if (log_is_enabled(Debug, os, thread, timer)) { 1949 _timer_exit_phase2.stop(); 1950 _timer_exit_phase3.start(); 1951 } 1952 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1953 // held by this thread must be released. The spec does not distinguish 1954 // between JNI-acquired and regular Java monitors. We can only see 1955 // regular Java monitors here if monitor enter-exit matching is broken. 1956 // 1957 // Optionally release any monitors for regular JavaThread exits. This 1958 // is provided as a work around for any bugs in monitor enter-exit 1959 // matching. This can be expensive so it is not enabled by default. 1960 // 1961 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1962 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1963 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1964 // Sanity check even though JNI DetachCurrentThread() would have 1965 // returned JNI_ERR if there was a Java frame. JavaThread exit 1966 // should be done executing Java code by the time we get here. 1967 assert(!this->has_last_Java_frame(), 1968 "should not have a Java frame when detaching or exiting"); 1969 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1970 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1971 } 1972 1973 // These things needs to be done while we are still a Java Thread. Make sure that thread 1974 // is in a consistent state, in case GC happens 1975 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1976 1977 if (active_handles() != NULL) { 1978 JNIHandleBlock* block = active_handles(); 1979 set_active_handles(NULL); 1980 JNIHandleBlock::release_block(block); 1981 } 1982 1983 if (free_handle_block() != NULL) { 1984 JNIHandleBlock* block = free_handle_block(); 1985 set_free_handle_block(NULL); 1986 JNIHandleBlock::release_block(block); 1987 } 1988 1989 // These have to be removed while this is still a valid thread. 1990 remove_stack_guard_pages(); 1991 1992 if (UseTLAB) { 1993 tlab().make_parsable(true); // retire TLAB 1994 } 1995 1996 if (JvmtiEnv::environments_might_exist()) { 1997 JvmtiExport::cleanup_thread(this); 1998 } 1999 2000 // We must flush any deferred card marks and other various GC barrier 2001 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2002 // before removing a thread from the list of active threads. 2003 BarrierSet::barrier_set()->on_thread_detach(this); 2004 2005 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2006 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2007 os::current_thread_id()); 2008 2009 if (log_is_enabled(Debug, os, thread, timer)) { 2010 _timer_exit_phase3.stop(); 2011 _timer_exit_phase4.start(); 2012 } 2013 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2014 Threads::remove(this); 2015 2016 if (log_is_enabled(Debug, os, thread, timer)) { 2017 _timer_exit_phase4.stop(); 2018 ResourceMark rm(this); 2019 log_debug(os, thread, timer)("name='%s'" 2020 ", exit-phase1=" JLONG_FORMAT 2021 ", exit-phase2=" JLONG_FORMAT 2022 ", exit-phase3=" JLONG_FORMAT 2023 ", exit-phase4=" JLONG_FORMAT, 2024 get_thread_name(), 2025 _timer_exit_phase1.milliseconds(), 2026 _timer_exit_phase2.milliseconds(), 2027 _timer_exit_phase3.milliseconds(), 2028 _timer_exit_phase4.milliseconds()); 2029 } 2030 } 2031 2032 void JavaThread::cleanup_failed_attach_current_thread() { 2033 if (active_handles() != NULL) { 2034 JNIHandleBlock* block = active_handles(); 2035 set_active_handles(NULL); 2036 JNIHandleBlock::release_block(block); 2037 } 2038 2039 if (free_handle_block() != NULL) { 2040 JNIHandleBlock* block = free_handle_block(); 2041 set_free_handle_block(NULL); 2042 JNIHandleBlock::release_block(block); 2043 } 2044 2045 // These have to be removed while this is still a valid thread. 2046 remove_stack_guard_pages(); 2047 2048 if (UseTLAB) { 2049 tlab().make_parsable(true); // retire TLAB, if any 2050 } 2051 2052 2053 BarrierSet::barrier_set()->on_thread_detach(this); 2054 2055 Threads::remove(this); 2056 this->smr_delete(); 2057 } 2058 2059 JavaThread* JavaThread::active() { 2060 Thread* thread = Thread::current(); 2061 if (thread->is_Java_thread()) { 2062 return (JavaThread*) thread; 2063 } else { 2064 assert(thread->is_VM_thread(), "this must be a vm thread"); 2065 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2066 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2067 assert(ret->is_Java_thread(), "must be a Java thread"); 2068 return ret; 2069 } 2070 } 2071 2072 bool JavaThread::is_lock_owned(address adr) const { 2073 if (Thread::is_lock_owned(adr)) return true; 2074 2075 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2076 if (chunk->contains(adr)) return true; 2077 } 2078 2079 return false; 2080 } 2081 2082 2083 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2084 chunk->set_next(monitor_chunks()); 2085 set_monitor_chunks(chunk); 2086 } 2087 2088 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2089 guarantee(monitor_chunks() != NULL, "must be non empty"); 2090 if (monitor_chunks() == chunk) { 2091 set_monitor_chunks(chunk->next()); 2092 } else { 2093 MonitorChunk* prev = monitor_chunks(); 2094 while (prev->next() != chunk) prev = prev->next(); 2095 prev->set_next(chunk->next()); 2096 } 2097 } 2098 2099 // JVM support. 2100 2101 // Note: this function shouldn't block if it's called in 2102 // _thread_in_native_trans state (such as from 2103 // check_special_condition_for_native_trans()). 2104 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2105 2106 if (has_last_Java_frame() && has_async_condition()) { 2107 // If we are at a polling page safepoint (not a poll return) 2108 // then we must defer async exception because live registers 2109 // will be clobbered by the exception path. Poll return is 2110 // ok because the call we a returning from already collides 2111 // with exception handling registers and so there is no issue. 2112 // (The exception handling path kills call result registers but 2113 // this is ok since the exception kills the result anyway). 2114 2115 if (is_at_poll_safepoint()) { 2116 // if the code we are returning to has deoptimized we must defer 2117 // the exception otherwise live registers get clobbered on the 2118 // exception path before deoptimization is able to retrieve them. 2119 // 2120 RegisterMap map(this, false); 2121 frame caller_fr = last_frame().sender(&map); 2122 assert(caller_fr.is_compiled_frame(), "what?"); 2123 if (caller_fr.is_deoptimized_frame()) { 2124 log_info(exceptions)("deferred async exception at compiled safepoint"); 2125 return; 2126 } 2127 } 2128 } 2129 2130 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2131 if (condition == _no_async_condition) { 2132 // Conditions have changed since has_special_runtime_exit_condition() 2133 // was called: 2134 // - if we were here only because of an external suspend request, 2135 // then that was taken care of above (or cancelled) so we are done 2136 // - if we were here because of another async request, then it has 2137 // been cleared between the has_special_runtime_exit_condition() 2138 // and now so again we are done 2139 return; 2140 } 2141 2142 // Check for pending async. exception 2143 if (_pending_async_exception != NULL) { 2144 // Only overwrite an already pending exception, if it is not a threadDeath. 2145 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2146 2147 // We cannot call Exceptions::_throw(...) here because we cannot block 2148 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2149 2150 LogTarget(Info, exceptions) lt; 2151 if (lt.is_enabled()) { 2152 ResourceMark rm; 2153 LogStream ls(lt); 2154 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2155 if (has_last_Java_frame()) { 2156 frame f = last_frame(); 2157 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2158 } 2159 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2160 } 2161 _pending_async_exception = NULL; 2162 clear_has_async_exception(); 2163 } 2164 } 2165 2166 if (check_unsafe_error && 2167 condition == _async_unsafe_access_error && !has_pending_exception()) { 2168 condition = _no_async_condition; // done 2169 switch (thread_state()) { 2170 case _thread_in_vm: { 2171 JavaThread* THREAD = this; 2172 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2173 } 2174 case _thread_in_native: { 2175 ThreadInVMfromNative tiv(this); 2176 JavaThread* THREAD = this; 2177 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2178 } 2179 case _thread_in_Java: { 2180 ThreadInVMfromJava tiv(this); 2181 JavaThread* THREAD = this; 2182 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2183 } 2184 default: 2185 ShouldNotReachHere(); 2186 } 2187 } 2188 2189 assert(condition == _no_async_condition || has_pending_exception() || 2190 (!check_unsafe_error && condition == _async_unsafe_access_error), 2191 "must have handled the async condition, if no exception"); 2192 } 2193 2194 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2195 // 2196 // Check for pending external suspend. Internal suspend requests do 2197 // not use handle_special_runtime_exit_condition(). 2198 // If JNIEnv proxies are allowed, don't self-suspend if the target 2199 // thread is not the current thread. In older versions of jdbx, jdbx 2200 // threads could call into the VM with another thread's JNIEnv so we 2201 // can be here operating on behalf of a suspended thread (4432884). 2202 bool do_self_suspend = is_external_suspend_with_lock(); 2203 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2204 // 2205 // Because thread is external suspended the safepoint code will count 2206 // thread as at a safepoint. This can be odd because we can be here 2207 // as _thread_in_Java which would normally transition to _thread_blocked 2208 // at a safepoint. We would like to mark the thread as _thread_blocked 2209 // before calling java_suspend_self like all other callers of it but 2210 // we must then observe proper safepoint protocol. (We can't leave 2211 // _thread_blocked with a safepoint in progress). However we can be 2212 // here as _thread_in_native_trans so we can't use a normal transition 2213 // constructor/destructor pair because they assert on that type of 2214 // transition. We could do something like: 2215 // 2216 // JavaThreadState state = thread_state(); 2217 // set_thread_state(_thread_in_vm); 2218 // { 2219 // ThreadBlockInVM tbivm(this); 2220 // java_suspend_self() 2221 // } 2222 // set_thread_state(_thread_in_vm_trans); 2223 // if (safepoint) block; 2224 // set_thread_state(state); 2225 // 2226 // but that is pretty messy. Instead we just go with the way the 2227 // code has worked before and note that this is the only path to 2228 // java_suspend_self that doesn't put the thread in _thread_blocked 2229 // mode. 2230 2231 frame_anchor()->make_walkable(this); 2232 java_suspend_self(); 2233 2234 // We might be here for reasons in addition to the self-suspend request 2235 // so check for other async requests. 2236 } 2237 2238 if (check_asyncs) { 2239 check_and_handle_async_exceptions(); 2240 } 2241 #if INCLUDE_TRACE 2242 if (is_trace_suspend()) { 2243 TRACE_SUSPEND_THREAD(this); 2244 } 2245 #endif 2246 } 2247 2248 void JavaThread::send_thread_stop(oop java_throwable) { 2249 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2250 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2251 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2252 2253 // Do not throw asynchronous exceptions against the compiler thread 2254 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2255 if (!can_call_java()) return; 2256 2257 { 2258 // Actually throw the Throwable against the target Thread - however 2259 // only if there is no thread death exception installed already. 2260 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2261 // If the topmost frame is a runtime stub, then we are calling into 2262 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2263 // must deoptimize the caller before continuing, as the compiled exception handler table 2264 // may not be valid 2265 if (has_last_Java_frame()) { 2266 frame f = last_frame(); 2267 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2268 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2269 RegisterMap reg_map(this, UseBiasedLocking); 2270 frame compiled_frame = f.sender(®_map); 2271 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2272 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2273 } 2274 } 2275 } 2276 2277 // Set async. pending exception in thread. 2278 set_pending_async_exception(java_throwable); 2279 2280 if (log_is_enabled(Info, exceptions)) { 2281 ResourceMark rm; 2282 log_info(exceptions)("Pending Async. exception installed of type: %s", 2283 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2284 } 2285 // for AbortVMOnException flag 2286 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2287 } 2288 } 2289 2290 2291 // Interrupt thread so it will wake up from a potential wait() 2292 Thread::interrupt(this); 2293 } 2294 2295 // External suspension mechanism. 2296 // 2297 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2298 // to any VM_locks and it is at a transition 2299 // Self-suspension will happen on the transition out of the vm. 2300 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2301 // 2302 // Guarantees on return: 2303 // + Target thread will not execute any new bytecode (that's why we need to 2304 // force a safepoint) 2305 // + Target thread will not enter any new monitors 2306 // 2307 void JavaThread::java_suspend() { 2308 ThreadsListHandle tlh; 2309 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2310 return; 2311 } 2312 2313 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2314 if (!is_external_suspend()) { 2315 // a racing resume has cancelled us; bail out now 2316 return; 2317 } 2318 2319 // suspend is done 2320 uint32_t debug_bits = 0; 2321 // Warning: is_ext_suspend_completed() may temporarily drop the 2322 // SR_lock to allow the thread to reach a stable thread state if 2323 // it is currently in a transient thread state. 2324 if (is_ext_suspend_completed(false /* !called_by_wait */, 2325 SuspendRetryDelay, &debug_bits)) { 2326 return; 2327 } 2328 } 2329 2330 VM_ThreadSuspend vm_suspend; 2331 VMThread::execute(&vm_suspend); 2332 } 2333 2334 // Part II of external suspension. 2335 // A JavaThread self suspends when it detects a pending external suspend 2336 // request. This is usually on transitions. It is also done in places 2337 // where continuing to the next transition would surprise the caller, 2338 // e.g., monitor entry. 2339 // 2340 // Returns the number of times that the thread self-suspended. 2341 // 2342 // Note: DO NOT call java_suspend_self() when you just want to block current 2343 // thread. java_suspend_self() is the second stage of cooperative 2344 // suspension for external suspend requests and should only be used 2345 // to complete an external suspend request. 2346 // 2347 int JavaThread::java_suspend_self() { 2348 int ret = 0; 2349 2350 // we are in the process of exiting so don't suspend 2351 if (is_exiting()) { 2352 clear_external_suspend(); 2353 return ret; 2354 } 2355 2356 assert(_anchor.walkable() || 2357 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2358 "must have walkable stack"); 2359 2360 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2361 2362 assert(!this->is_ext_suspended(), 2363 "a thread trying to self-suspend should not already be suspended"); 2364 2365 if (this->is_suspend_equivalent()) { 2366 // If we are self-suspending as a result of the lifting of a 2367 // suspend equivalent condition, then the suspend_equivalent 2368 // flag is not cleared until we set the ext_suspended flag so 2369 // that wait_for_ext_suspend_completion() returns consistent 2370 // results. 2371 this->clear_suspend_equivalent(); 2372 } 2373 2374 // A racing resume may have cancelled us before we grabbed SR_lock 2375 // above. Or another external suspend request could be waiting for us 2376 // by the time we return from SR_lock()->wait(). The thread 2377 // that requested the suspension may already be trying to walk our 2378 // stack and if we return now, we can change the stack out from under 2379 // it. This would be a "bad thing (TM)" and cause the stack walker 2380 // to crash. We stay self-suspended until there are no more pending 2381 // external suspend requests. 2382 while (is_external_suspend()) { 2383 ret++; 2384 this->set_ext_suspended(); 2385 2386 // _ext_suspended flag is cleared by java_resume() 2387 while (is_ext_suspended()) { 2388 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2389 } 2390 } 2391 2392 return ret; 2393 } 2394 2395 #ifdef ASSERT 2396 // verify the JavaThread has not yet been published in the Threads::list, and 2397 // hence doesn't need protection from concurrent access at this stage 2398 void JavaThread::verify_not_published() { 2399 ThreadsListHandle tlh; 2400 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!"); 2401 } 2402 #endif 2403 2404 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2405 // progress or when _suspend_flags is non-zero. 2406 // Current thread needs to self-suspend if there is a suspend request and/or 2407 // block if a safepoint is in progress. 2408 // Async exception ISN'T checked. 2409 // Note only the ThreadInVMfromNative transition can call this function 2410 // directly and when thread state is _thread_in_native_trans 2411 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2412 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2413 2414 JavaThread *curJT = JavaThread::current(); 2415 bool do_self_suspend = thread->is_external_suspend(); 2416 2417 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2418 2419 // If JNIEnv proxies are allowed, don't self-suspend if the target 2420 // thread is not the current thread. In older versions of jdbx, jdbx 2421 // threads could call into the VM with another thread's JNIEnv so we 2422 // can be here operating on behalf of a suspended thread (4432884). 2423 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2424 JavaThreadState state = thread->thread_state(); 2425 2426 // We mark this thread_blocked state as a suspend-equivalent so 2427 // that a caller to is_ext_suspend_completed() won't be confused. 2428 // The suspend-equivalent state is cleared by java_suspend_self(). 2429 thread->set_suspend_equivalent(); 2430 2431 // If the safepoint code sees the _thread_in_native_trans state, it will 2432 // wait until the thread changes to other thread state. There is no 2433 // guarantee on how soon we can obtain the SR_lock and complete the 2434 // self-suspend request. It would be a bad idea to let safepoint wait for 2435 // too long. Temporarily change the state to _thread_blocked to 2436 // let the VM thread know that this thread is ready for GC. The problem 2437 // of changing thread state is that safepoint could happen just after 2438 // java_suspend_self() returns after being resumed, and VM thread will 2439 // see the _thread_blocked state. We must check for safepoint 2440 // after restoring the state and make sure we won't leave while a safepoint 2441 // is in progress. 2442 thread->set_thread_state(_thread_blocked); 2443 thread->java_suspend_self(); 2444 thread->set_thread_state(state); 2445 2446 InterfaceSupport::serialize_thread_state_with_handler(thread); 2447 } 2448 2449 SafepointMechanism::block_if_requested(curJT); 2450 2451 if (thread->is_deopt_suspend()) { 2452 thread->clear_deopt_suspend(); 2453 RegisterMap map(thread, false); 2454 frame f = thread->last_frame(); 2455 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2456 f = f.sender(&map); 2457 } 2458 if (f.id() == thread->must_deopt_id()) { 2459 thread->clear_must_deopt_id(); 2460 f.deoptimize(thread); 2461 } else { 2462 fatal("missed deoptimization!"); 2463 } 2464 } 2465 #if INCLUDE_TRACE 2466 if (thread->is_trace_suspend()) { 2467 TRACE_SUSPEND_THREAD(thread); 2468 } 2469 #endif 2470 } 2471 2472 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2473 // progress or when _suspend_flags is non-zero. 2474 // Current thread needs to self-suspend if there is a suspend request and/or 2475 // block if a safepoint is in progress. 2476 // Also check for pending async exception (not including unsafe access error). 2477 // Note only the native==>VM/Java barriers can call this function and when 2478 // thread state is _thread_in_native_trans. 2479 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2480 check_safepoint_and_suspend_for_native_trans(thread); 2481 2482 if (thread->has_async_exception()) { 2483 // We are in _thread_in_native_trans state, don't handle unsafe 2484 // access error since that may block. 2485 thread->check_and_handle_async_exceptions(false); 2486 } 2487 } 2488 2489 // This is a variant of the normal 2490 // check_special_condition_for_native_trans with slightly different 2491 // semantics for use by critical native wrappers. It does all the 2492 // normal checks but also performs the transition back into 2493 // thread_in_Java state. This is required so that critical natives 2494 // can potentially block and perform a GC if they are the last thread 2495 // exiting the GCLocker. 2496 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2497 check_special_condition_for_native_trans(thread); 2498 2499 // Finish the transition 2500 thread->set_thread_state(_thread_in_Java); 2501 2502 if (thread->do_critical_native_unlock()) { 2503 ThreadInVMfromJavaNoAsyncException tiv(thread); 2504 GCLocker::unlock_critical(thread); 2505 thread->clear_critical_native_unlock(); 2506 } 2507 } 2508 2509 // We need to guarantee the Threads_lock here, since resumes are not 2510 // allowed during safepoint synchronization 2511 // Can only resume from an external suspension 2512 void JavaThread::java_resume() { 2513 assert_locked_or_safepoint(Threads_lock); 2514 2515 // Sanity check: thread is gone, has started exiting or the thread 2516 // was not externally suspended. 2517 ThreadsListHandle tlh; 2518 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2519 return; 2520 } 2521 2522 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2523 2524 clear_external_suspend(); 2525 2526 if (is_ext_suspended()) { 2527 clear_ext_suspended(); 2528 SR_lock()->notify_all(); 2529 } 2530 } 2531 2532 size_t JavaThread::_stack_red_zone_size = 0; 2533 size_t JavaThread::_stack_yellow_zone_size = 0; 2534 size_t JavaThread::_stack_reserved_zone_size = 0; 2535 size_t JavaThread::_stack_shadow_zone_size = 0; 2536 2537 void JavaThread::create_stack_guard_pages() { 2538 if (!os::uses_stack_guard_pages() || 2539 _stack_guard_state != stack_guard_unused || 2540 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2541 log_info(os, thread)("Stack guard page creation for thread " 2542 UINTX_FORMAT " disabled", os::current_thread_id()); 2543 return; 2544 } 2545 address low_addr = stack_end(); 2546 size_t len = stack_guard_zone_size(); 2547 2548 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2549 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2550 2551 int must_commit = os::must_commit_stack_guard_pages(); 2552 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2553 2554 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2555 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2556 return; 2557 } 2558 2559 if (os::guard_memory((char *) low_addr, len)) { 2560 _stack_guard_state = stack_guard_enabled; 2561 } else { 2562 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2563 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2564 if (os::uncommit_memory((char *) low_addr, len)) { 2565 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2566 } 2567 return; 2568 } 2569 2570 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2571 PTR_FORMAT "-" PTR_FORMAT ".", 2572 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2573 } 2574 2575 void JavaThread::remove_stack_guard_pages() { 2576 assert(Thread::current() == this, "from different thread"); 2577 if (_stack_guard_state == stack_guard_unused) return; 2578 address low_addr = stack_end(); 2579 size_t len = stack_guard_zone_size(); 2580 2581 if (os::must_commit_stack_guard_pages()) { 2582 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2583 _stack_guard_state = stack_guard_unused; 2584 } else { 2585 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2586 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2587 return; 2588 } 2589 } else { 2590 if (_stack_guard_state == stack_guard_unused) return; 2591 if (os::unguard_memory((char *) low_addr, len)) { 2592 _stack_guard_state = stack_guard_unused; 2593 } else { 2594 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2595 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2596 return; 2597 } 2598 } 2599 2600 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2601 PTR_FORMAT "-" PTR_FORMAT ".", 2602 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2603 } 2604 2605 void JavaThread::enable_stack_reserved_zone() { 2606 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2607 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2608 2609 // The base notation is from the stack's point of view, growing downward. 2610 // We need to adjust it to work correctly with guard_memory() 2611 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2612 2613 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2614 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2615 2616 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2617 _stack_guard_state = stack_guard_enabled; 2618 } else { 2619 warning("Attempt to guard stack reserved zone failed."); 2620 } 2621 enable_register_stack_guard(); 2622 } 2623 2624 void JavaThread::disable_stack_reserved_zone() { 2625 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2626 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2627 2628 // Simply return if called for a thread that does not use guard pages. 2629 if (_stack_guard_state == stack_guard_unused) return; 2630 2631 // The base notation is from the stack's point of view, growing downward. 2632 // We need to adjust it to work correctly with guard_memory() 2633 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2634 2635 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2636 _stack_guard_state = stack_guard_reserved_disabled; 2637 } else { 2638 warning("Attempt to unguard stack reserved zone failed."); 2639 } 2640 disable_register_stack_guard(); 2641 } 2642 2643 void JavaThread::enable_stack_yellow_reserved_zone() { 2644 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2645 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2646 2647 // The base notation is from the stacks point of view, growing downward. 2648 // We need to adjust it to work correctly with guard_memory() 2649 address base = stack_red_zone_base(); 2650 2651 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2652 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2653 2654 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2655 _stack_guard_state = stack_guard_enabled; 2656 } else { 2657 warning("Attempt to guard stack yellow zone failed."); 2658 } 2659 enable_register_stack_guard(); 2660 } 2661 2662 void JavaThread::disable_stack_yellow_reserved_zone() { 2663 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2664 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2665 2666 // Simply return if called for a thread that does not use guard pages. 2667 if (_stack_guard_state == stack_guard_unused) return; 2668 2669 // The base notation is from the stacks point of view, growing downward. 2670 // We need to adjust it to work correctly with guard_memory() 2671 address base = stack_red_zone_base(); 2672 2673 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2674 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2675 } else { 2676 warning("Attempt to unguard stack yellow zone failed."); 2677 } 2678 disable_register_stack_guard(); 2679 } 2680 2681 void JavaThread::enable_stack_red_zone() { 2682 // The base notation is from the stacks point of view, growing downward. 2683 // We need to adjust it to work correctly with guard_memory() 2684 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2685 address base = stack_red_zone_base() - stack_red_zone_size(); 2686 2687 guarantee(base < stack_base(), "Error calculating stack red zone"); 2688 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2689 2690 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2691 warning("Attempt to guard stack red zone failed."); 2692 } 2693 } 2694 2695 void JavaThread::disable_stack_red_zone() { 2696 // The base notation is from the stacks point of view, growing downward. 2697 // We need to adjust it to work correctly with guard_memory() 2698 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2699 address base = stack_red_zone_base() - stack_red_zone_size(); 2700 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2701 warning("Attempt to unguard stack red zone failed."); 2702 } 2703 } 2704 2705 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2706 // ignore is there is no stack 2707 if (!has_last_Java_frame()) return; 2708 // traverse the stack frames. Starts from top frame. 2709 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2710 frame* fr = fst.current(); 2711 f(fr, fst.register_map()); 2712 } 2713 } 2714 2715 2716 #ifndef PRODUCT 2717 // Deoptimization 2718 // Function for testing deoptimization 2719 void JavaThread::deoptimize() { 2720 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2721 StackFrameStream fst(this, UseBiasedLocking); 2722 bool deopt = false; // Dump stack only if a deopt actually happens. 2723 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2724 // Iterate over all frames in the thread and deoptimize 2725 for (; !fst.is_done(); fst.next()) { 2726 if (fst.current()->can_be_deoptimized()) { 2727 2728 if (only_at) { 2729 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2730 // consists of comma or carriage return separated numbers so 2731 // search for the current bci in that string. 2732 address pc = fst.current()->pc(); 2733 nmethod* nm = (nmethod*) fst.current()->cb(); 2734 ScopeDesc* sd = nm->scope_desc_at(pc); 2735 char buffer[8]; 2736 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2737 size_t len = strlen(buffer); 2738 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2739 while (found != NULL) { 2740 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2741 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2742 // Check that the bci found is bracketed by terminators. 2743 break; 2744 } 2745 found = strstr(found + 1, buffer); 2746 } 2747 if (!found) { 2748 continue; 2749 } 2750 } 2751 2752 if (DebugDeoptimization && !deopt) { 2753 deopt = true; // One-time only print before deopt 2754 tty->print_cr("[BEFORE Deoptimization]"); 2755 trace_frames(); 2756 trace_stack(); 2757 } 2758 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2759 } 2760 } 2761 2762 if (DebugDeoptimization && deopt) { 2763 tty->print_cr("[AFTER Deoptimization]"); 2764 trace_frames(); 2765 } 2766 } 2767 2768 2769 // Make zombies 2770 void JavaThread::make_zombies() { 2771 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2772 if (fst.current()->can_be_deoptimized()) { 2773 // it is a Java nmethod 2774 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2775 nm->make_not_entrant(); 2776 } 2777 } 2778 } 2779 #endif // PRODUCT 2780 2781 2782 void JavaThread::deoptimized_wrt_marked_nmethods() { 2783 if (!has_last_Java_frame()) return; 2784 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2785 StackFrameStream fst(this, UseBiasedLocking); 2786 for (; !fst.is_done(); fst.next()) { 2787 if (fst.current()->should_be_deoptimized()) { 2788 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2789 } 2790 } 2791 } 2792 2793 2794 // If the caller is a NamedThread, then remember, in the current scope, 2795 // the given JavaThread in its _processed_thread field. 2796 class RememberProcessedThread: public StackObj { 2797 NamedThread* _cur_thr; 2798 public: 2799 RememberProcessedThread(JavaThread* jthr) { 2800 Thread* thread = Thread::current(); 2801 if (thread->is_Named_thread()) { 2802 _cur_thr = (NamedThread *)thread; 2803 _cur_thr->set_processed_thread(jthr); 2804 } else { 2805 _cur_thr = NULL; 2806 } 2807 } 2808 2809 ~RememberProcessedThread() { 2810 if (_cur_thr) { 2811 _cur_thr->set_processed_thread(NULL); 2812 } 2813 } 2814 }; 2815 2816 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2817 // Verify that the deferred card marks have been flushed. 2818 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2819 2820 // Traverse the GCHandles 2821 Thread::oops_do(f, cf); 2822 2823 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2824 2825 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2826 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2827 2828 if (has_last_Java_frame()) { 2829 // Record JavaThread to GC thread 2830 RememberProcessedThread rpt(this); 2831 2832 // Traverse the privileged stack 2833 if (_privileged_stack_top != NULL) { 2834 _privileged_stack_top->oops_do(f); 2835 } 2836 2837 // traverse the registered growable array 2838 if (_array_for_gc != NULL) { 2839 for (int index = 0; index < _array_for_gc->length(); index++) { 2840 f->do_oop(_array_for_gc->adr_at(index)); 2841 } 2842 } 2843 2844 // Traverse the monitor chunks 2845 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2846 chunk->oops_do(f); 2847 } 2848 2849 // Traverse the execution stack 2850 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2851 fst.current()->oops_do(f, cf, fst.register_map()); 2852 } 2853 } 2854 2855 // callee_target is never live across a gc point so NULL it here should 2856 // it still contain a methdOop. 2857 2858 set_callee_target(NULL); 2859 2860 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2861 // If we have deferred set_locals there might be oops waiting to be 2862 // written 2863 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2864 if (list != NULL) { 2865 for (int i = 0; i < list->length(); i++) { 2866 list->at(i)->oops_do(f); 2867 } 2868 } 2869 2870 // Traverse instance variables at the end since the GC may be moving things 2871 // around using this function 2872 f->do_oop((oop*) &_threadObj); 2873 f->do_oop((oop*) &_vm_result); 2874 f->do_oop((oop*) &_exception_oop); 2875 f->do_oop((oop*) &_pending_async_exception); 2876 2877 if (jvmti_thread_state() != NULL) { 2878 jvmti_thread_state()->oops_do(f); 2879 } 2880 } 2881 2882 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2883 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2884 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2885 2886 if (has_last_Java_frame()) { 2887 // Traverse the execution stack 2888 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2889 fst.current()->nmethods_do(cf); 2890 } 2891 } 2892 } 2893 2894 void JavaThread::metadata_do(void f(Metadata*)) { 2895 if (has_last_Java_frame()) { 2896 // Traverse the execution stack to call f() on the methods in the stack 2897 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2898 fst.current()->metadata_do(f); 2899 } 2900 } else if (is_Compiler_thread()) { 2901 // need to walk ciMetadata in current compile tasks to keep alive. 2902 CompilerThread* ct = (CompilerThread*)this; 2903 if (ct->env() != NULL) { 2904 ct->env()->metadata_do(f); 2905 } 2906 CompileTask* task = ct->task(); 2907 if (task != NULL) { 2908 task->metadata_do(f); 2909 } 2910 } 2911 } 2912 2913 // Printing 2914 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2915 switch (_thread_state) { 2916 case _thread_uninitialized: return "_thread_uninitialized"; 2917 case _thread_new: return "_thread_new"; 2918 case _thread_new_trans: return "_thread_new_trans"; 2919 case _thread_in_native: return "_thread_in_native"; 2920 case _thread_in_native_trans: return "_thread_in_native_trans"; 2921 case _thread_in_vm: return "_thread_in_vm"; 2922 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2923 case _thread_in_Java: return "_thread_in_Java"; 2924 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2925 case _thread_blocked: return "_thread_blocked"; 2926 case _thread_blocked_trans: return "_thread_blocked_trans"; 2927 default: return "unknown thread state"; 2928 } 2929 } 2930 2931 #ifndef PRODUCT 2932 void JavaThread::print_thread_state_on(outputStream *st) const { 2933 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2934 }; 2935 void JavaThread::print_thread_state() const { 2936 print_thread_state_on(tty); 2937 } 2938 #endif // PRODUCT 2939 2940 // Called by Threads::print() for VM_PrintThreads operation 2941 void JavaThread::print_on(outputStream *st) const { 2942 st->print_raw("\""); 2943 st->print_raw(get_thread_name()); 2944 st->print_raw("\" "); 2945 oop thread_oop = threadObj(); 2946 if (thread_oop != NULL) { 2947 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2948 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2949 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2950 } 2951 Thread::print_on(st); 2952 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2953 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2954 if (thread_oop != NULL) { 2955 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2956 } 2957 #ifndef PRODUCT 2958 print_thread_state_on(st); 2959 _safepoint_state->print_on(st); 2960 #endif // PRODUCT 2961 if (is_Compiler_thread()) { 2962 CompileTask *task = ((CompilerThread*)this)->task(); 2963 if (task != NULL) { 2964 st->print(" Compiling: "); 2965 task->print(st, NULL, true, false); 2966 } else { 2967 st->print(" No compile task"); 2968 } 2969 st->cr(); 2970 } 2971 } 2972 2973 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2974 st->print("%s", get_thread_name_string(buf, buflen)); 2975 } 2976 2977 // Called by fatal error handler. The difference between this and 2978 // JavaThread::print() is that we can't grab lock or allocate memory. 2979 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2980 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2981 oop thread_obj = threadObj(); 2982 if (thread_obj != NULL) { 2983 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2984 } 2985 st->print(" ["); 2986 st->print("%s", _get_thread_state_name(_thread_state)); 2987 if (osthread()) { 2988 st->print(", id=%d", osthread()->thread_id()); 2989 } 2990 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2991 p2i(stack_end()), p2i(stack_base())); 2992 st->print("]"); 2993 2994 if (_threads_hazard_ptr != NULL) { 2995 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 2996 } 2997 if (_nested_threads_hazard_ptr != NULL) { 2998 print_nested_threads_hazard_ptrs_on(st); 2999 } 3000 return; 3001 } 3002 3003 // Verification 3004 3005 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3006 3007 void JavaThread::verify() { 3008 // Verify oops in the thread. 3009 oops_do(&VerifyOopClosure::verify_oop, NULL); 3010 3011 // Verify the stack frames. 3012 frames_do(frame_verify); 3013 } 3014 3015 // CR 6300358 (sub-CR 2137150) 3016 // Most callers of this method assume that it can't return NULL but a 3017 // thread may not have a name whilst it is in the process of attaching to 3018 // the VM - see CR 6412693, and there are places where a JavaThread can be 3019 // seen prior to having it's threadObj set (eg JNI attaching threads and 3020 // if vm exit occurs during initialization). These cases can all be accounted 3021 // for such that this method never returns NULL. 3022 const char* JavaThread::get_thread_name() const { 3023 #ifdef ASSERT 3024 // early safepoints can hit while current thread does not yet have TLS 3025 if (!SafepointSynchronize::is_at_safepoint()) { 3026 Thread *cur = Thread::current(); 3027 if (!(cur->is_Java_thread() && cur == this)) { 3028 // Current JavaThreads are allowed to get their own name without 3029 // the Threads_lock. 3030 assert_locked_or_safepoint(Threads_lock); 3031 } 3032 } 3033 #endif // ASSERT 3034 return get_thread_name_string(); 3035 } 3036 3037 // Returns a non-NULL representation of this thread's name, or a suitable 3038 // descriptive string if there is no set name 3039 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3040 const char* name_str; 3041 oop thread_obj = threadObj(); 3042 if (thread_obj != NULL) { 3043 oop name = java_lang_Thread::name(thread_obj); 3044 if (name != NULL) { 3045 if (buf == NULL) { 3046 name_str = java_lang_String::as_utf8_string(name); 3047 } else { 3048 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3049 } 3050 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3051 name_str = "<no-name - thread is attaching>"; 3052 } else { 3053 name_str = Thread::name(); 3054 } 3055 } else { 3056 name_str = Thread::name(); 3057 } 3058 assert(name_str != NULL, "unexpected NULL thread name"); 3059 return name_str; 3060 } 3061 3062 3063 const char* JavaThread::get_threadgroup_name() const { 3064 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3065 oop thread_obj = threadObj(); 3066 if (thread_obj != NULL) { 3067 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3068 if (thread_group != NULL) { 3069 // ThreadGroup.name can be null 3070 return java_lang_ThreadGroup::name(thread_group); 3071 } 3072 } 3073 return NULL; 3074 } 3075 3076 const char* JavaThread::get_parent_name() const { 3077 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3078 oop thread_obj = threadObj(); 3079 if (thread_obj != NULL) { 3080 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3081 if (thread_group != NULL) { 3082 oop parent = java_lang_ThreadGroup::parent(thread_group); 3083 if (parent != NULL) { 3084 // ThreadGroup.name can be null 3085 return java_lang_ThreadGroup::name(parent); 3086 } 3087 } 3088 } 3089 return NULL; 3090 } 3091 3092 ThreadPriority JavaThread::java_priority() const { 3093 oop thr_oop = threadObj(); 3094 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3095 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3096 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3097 return priority; 3098 } 3099 3100 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3101 3102 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3103 // Link Java Thread object <-> C++ Thread 3104 3105 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3106 // and put it into a new Handle. The Handle "thread_oop" can then 3107 // be used to pass the C++ thread object to other methods. 3108 3109 // Set the Java level thread object (jthread) field of the 3110 // new thread (a JavaThread *) to C++ thread object using the 3111 // "thread_oop" handle. 3112 3113 // Set the thread field (a JavaThread *) of the 3114 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3115 3116 Handle thread_oop(Thread::current(), 3117 JNIHandles::resolve_non_null(jni_thread)); 3118 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3119 "must be initialized"); 3120 set_threadObj(thread_oop()); 3121 java_lang_Thread::set_thread(thread_oop(), this); 3122 3123 if (prio == NoPriority) { 3124 prio = java_lang_Thread::priority(thread_oop()); 3125 assert(prio != NoPriority, "A valid priority should be present"); 3126 } 3127 3128 // Push the Java priority down to the native thread; needs Threads_lock 3129 Thread::set_priority(this, prio); 3130 3131 // Add the new thread to the Threads list and set it in motion. 3132 // We must have threads lock in order to call Threads::add. 3133 // It is crucial that we do not block before the thread is 3134 // added to the Threads list for if a GC happens, then the java_thread oop 3135 // will not be visited by GC. 3136 Threads::add(this); 3137 } 3138 3139 oop JavaThread::current_park_blocker() { 3140 // Support for JSR-166 locks 3141 oop thread_oop = threadObj(); 3142 if (thread_oop != NULL && 3143 JDK_Version::current().supports_thread_park_blocker()) { 3144 return java_lang_Thread::park_blocker(thread_oop); 3145 } 3146 return NULL; 3147 } 3148 3149 3150 void JavaThread::print_stack_on(outputStream* st) { 3151 if (!has_last_Java_frame()) return; 3152 ResourceMark rm; 3153 HandleMark hm; 3154 3155 RegisterMap reg_map(this); 3156 vframe* start_vf = last_java_vframe(®_map); 3157 int count = 0; 3158 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3159 if (f->is_java_frame()) { 3160 javaVFrame* jvf = javaVFrame::cast(f); 3161 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3162 3163 // Print out lock information 3164 if (JavaMonitorsInStackTrace) { 3165 jvf->print_lock_info_on(st, count); 3166 } 3167 } else { 3168 // Ignore non-Java frames 3169 } 3170 3171 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3172 count++; 3173 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3174 } 3175 } 3176 3177 3178 // JVMTI PopFrame support 3179 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3180 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3181 if (in_bytes(size_in_bytes) != 0) { 3182 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3183 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3184 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3185 } 3186 } 3187 3188 void* JavaThread::popframe_preserved_args() { 3189 return _popframe_preserved_args; 3190 } 3191 3192 ByteSize JavaThread::popframe_preserved_args_size() { 3193 return in_ByteSize(_popframe_preserved_args_size); 3194 } 3195 3196 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3197 int sz = in_bytes(popframe_preserved_args_size()); 3198 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3199 return in_WordSize(sz / wordSize); 3200 } 3201 3202 void JavaThread::popframe_free_preserved_args() { 3203 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3204 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3205 _popframe_preserved_args = NULL; 3206 _popframe_preserved_args_size = 0; 3207 } 3208 3209 #ifndef PRODUCT 3210 3211 void JavaThread::trace_frames() { 3212 tty->print_cr("[Describe stack]"); 3213 int frame_no = 1; 3214 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3215 tty->print(" %d. ", frame_no++); 3216 fst.current()->print_value_on(tty, this); 3217 tty->cr(); 3218 } 3219 } 3220 3221 class PrintAndVerifyOopClosure: public OopClosure { 3222 protected: 3223 template <class T> inline void do_oop_work(T* p) { 3224 oop obj = oopDesc::load_decode_heap_oop(p); 3225 if (obj == NULL) return; 3226 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3227 if (oopDesc::is_oop_or_null(obj)) { 3228 if (obj->is_objArray()) { 3229 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3230 } else { 3231 obj->print(); 3232 } 3233 } else { 3234 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3235 } 3236 tty->cr(); 3237 } 3238 public: 3239 virtual void do_oop(oop* p) { do_oop_work(p); } 3240 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3241 }; 3242 3243 3244 static void oops_print(frame* f, const RegisterMap *map) { 3245 PrintAndVerifyOopClosure print; 3246 f->print_value(); 3247 f->oops_do(&print, NULL, (RegisterMap*)map); 3248 } 3249 3250 // Print our all the locations that contain oops and whether they are 3251 // valid or not. This useful when trying to find the oldest frame 3252 // where an oop has gone bad since the frame walk is from youngest to 3253 // oldest. 3254 void JavaThread::trace_oops() { 3255 tty->print_cr("[Trace oops]"); 3256 frames_do(oops_print); 3257 } 3258 3259 3260 #ifdef ASSERT 3261 // Print or validate the layout of stack frames 3262 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3263 ResourceMark rm; 3264 PRESERVE_EXCEPTION_MARK; 3265 FrameValues values; 3266 int frame_no = 0; 3267 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3268 fst.current()->describe(values, ++frame_no); 3269 if (depth == frame_no) break; 3270 } 3271 if (validate_only) { 3272 values.validate(); 3273 } else { 3274 tty->print_cr("[Describe stack layout]"); 3275 values.print(this); 3276 } 3277 } 3278 #endif 3279 3280 void JavaThread::trace_stack_from(vframe* start_vf) { 3281 ResourceMark rm; 3282 int vframe_no = 1; 3283 for (vframe* f = start_vf; f; f = f->sender()) { 3284 if (f->is_java_frame()) { 3285 javaVFrame::cast(f)->print_activation(vframe_no++); 3286 } else { 3287 f->print(); 3288 } 3289 if (vframe_no > StackPrintLimit) { 3290 tty->print_cr("...<more frames>..."); 3291 return; 3292 } 3293 } 3294 } 3295 3296 3297 void JavaThread::trace_stack() { 3298 if (!has_last_Java_frame()) return; 3299 ResourceMark rm; 3300 HandleMark hm; 3301 RegisterMap reg_map(this); 3302 trace_stack_from(last_java_vframe(®_map)); 3303 } 3304 3305 3306 #endif // PRODUCT 3307 3308 3309 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3310 assert(reg_map != NULL, "a map must be given"); 3311 frame f = last_frame(); 3312 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3313 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3314 } 3315 return NULL; 3316 } 3317 3318 3319 Klass* JavaThread::security_get_caller_class(int depth) { 3320 vframeStream vfst(this); 3321 vfst.security_get_caller_frame(depth); 3322 if (!vfst.at_end()) { 3323 return vfst.method()->method_holder(); 3324 } 3325 return NULL; 3326 } 3327 3328 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3329 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3330 CompileBroker::compiler_thread_loop(); 3331 } 3332 3333 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3334 NMethodSweeper::sweeper_loop(); 3335 } 3336 3337 // Create a CompilerThread 3338 CompilerThread::CompilerThread(CompileQueue* queue, 3339 CompilerCounters* counters) 3340 : JavaThread(&compiler_thread_entry) { 3341 _env = NULL; 3342 _log = NULL; 3343 _task = NULL; 3344 _queue = queue; 3345 _counters = counters; 3346 _buffer_blob = NULL; 3347 _compiler = NULL; 3348 3349 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3350 resource_area()->bias_to(mtCompiler); 3351 3352 #ifndef PRODUCT 3353 _ideal_graph_printer = NULL; 3354 #endif 3355 } 3356 3357 bool CompilerThread::can_call_java() const { 3358 return _compiler != NULL && _compiler->is_jvmci(); 3359 } 3360 3361 // Create sweeper thread 3362 CodeCacheSweeperThread::CodeCacheSweeperThread() 3363 : JavaThread(&sweeper_thread_entry) { 3364 _scanned_compiled_method = NULL; 3365 } 3366 3367 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3368 JavaThread::oops_do(f, cf); 3369 if (_scanned_compiled_method != NULL && cf != NULL) { 3370 // Safepoints can occur when the sweeper is scanning an nmethod so 3371 // process it here to make sure it isn't unloaded in the middle of 3372 // a scan. 3373 cf->do_code_blob(_scanned_compiled_method); 3374 } 3375 } 3376 3377 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3378 JavaThread::nmethods_do(cf); 3379 if (_scanned_compiled_method != NULL && cf != NULL) { 3380 // Safepoints can occur when the sweeper is scanning an nmethod so 3381 // process it here to make sure it isn't unloaded in the middle of 3382 // a scan. 3383 cf->do_code_blob(_scanned_compiled_method); 3384 } 3385 } 3386 3387 3388 // ======= Threads ======== 3389 3390 // The Threads class links together all active threads, and provides 3391 // operations over all threads. It is protected by the Threads_lock, 3392 // which is also used in other global contexts like safepointing. 3393 // ThreadsListHandles are used to safely perform operations on one 3394 // or more threads without the risk of the thread exiting during the 3395 // operation. 3396 // 3397 // Note: The Threads_lock is currently more widely used than we 3398 // would like. We are actively migrating Threads_lock uses to other 3399 // mechanisms in order to reduce Threads_lock contention. 3400 3401 JavaThread* Threads::_thread_list = NULL; 3402 int Threads::_number_of_threads = 0; 3403 int Threads::_number_of_non_daemon_threads = 0; 3404 int Threads::_return_code = 0; 3405 int Threads::_thread_claim_parity = 0; 3406 size_t JavaThread::_stack_size_at_create = 0; 3407 3408 #ifdef ASSERT 3409 bool Threads::_vm_complete = false; 3410 #endif 3411 3412 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3413 Prefetch::read((void*)addr, prefetch_interval); 3414 return *addr; 3415 } 3416 3417 // Possibly the ugliest for loop the world has seen. C++ does not allow 3418 // multiple types in the declaration section of the for loop. In this case 3419 // we are only dealing with pointers and hence can cast them. It looks ugly 3420 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3421 #define DO_JAVA_THREADS(LIST, X) \ 3422 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3423 *MACRO_list = (JavaThread*)(LIST), \ 3424 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3425 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3426 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3427 MACRO_current_p != MACRO_end; \ 3428 MACRO_current_p++, \ 3429 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3430 3431 // All JavaThreads 3432 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3433 3434 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3435 void Threads::threads_do(ThreadClosure* tc) { 3436 assert_locked_or_safepoint(Threads_lock); 3437 // ALL_JAVA_THREADS iterates through all JavaThreads 3438 ALL_JAVA_THREADS(p) { 3439 tc->do_thread(p); 3440 } 3441 // Someday we could have a table or list of all non-JavaThreads. 3442 // For now, just manually iterate through them. 3443 tc->do_thread(VMThread::vm_thread()); 3444 Universe::heap()->gc_threads_do(tc); 3445 WatcherThread *wt = WatcherThread::watcher_thread(); 3446 // Strictly speaking, the following NULL check isn't sufficient to make sure 3447 // the data for WatcherThread is still valid upon being examined. However, 3448 // considering that WatchThread terminates when the VM is on the way to 3449 // exit at safepoint, the chance of the above is extremely small. The right 3450 // way to prevent termination of WatcherThread would be to acquire 3451 // Terminator_lock, but we can't do that without violating the lock rank 3452 // checking in some cases. 3453 if (wt != NULL) { 3454 tc->do_thread(wt); 3455 } 3456 3457 // If CompilerThreads ever become non-JavaThreads, add them here 3458 } 3459 3460 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3461 int cp = Threads::thread_claim_parity(); 3462 ALL_JAVA_THREADS(p) { 3463 if (p->claim_oops_do(is_par, cp)) { 3464 tc->do_thread(p); 3465 } 3466 } 3467 VMThread* vmt = VMThread::vm_thread(); 3468 if (vmt->claim_oops_do(is_par, cp)) { 3469 tc->do_thread(vmt); 3470 } 3471 } 3472 3473 // The system initialization in the library has three phases. 3474 // 3475 // Phase 1: java.lang.System class initialization 3476 // java.lang.System is a primordial class loaded and initialized 3477 // by the VM early during startup. java.lang.System.<clinit> 3478 // only does registerNatives and keeps the rest of the class 3479 // initialization work later until thread initialization completes. 3480 // 3481 // System.initPhase1 initializes the system properties, the static 3482 // fields in, out, and err. Set up java signal handlers, OS-specific 3483 // system settings, and thread group of the main thread. 3484 static void call_initPhase1(TRAPS) { 3485 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3486 JavaValue result(T_VOID); 3487 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3488 vmSymbols::void_method_signature(), CHECK); 3489 } 3490 3491 // Phase 2. Module system initialization 3492 // This will initialize the module system. Only java.base classes 3493 // can be loaded until phase 2 completes. 3494 // 3495 // Call System.initPhase2 after the compiler initialization and jsr292 3496 // classes get initialized because module initialization runs a lot of java 3497 // code, that for performance reasons, should be compiled. Also, this will 3498 // enable the startup code to use lambda and other language features in this 3499 // phase and onward. 3500 // 3501 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3502 static void call_initPhase2(TRAPS) { 3503 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3504 3505 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3506 3507 JavaValue result(T_INT); 3508 JavaCallArguments args; 3509 args.push_int(DisplayVMOutputToStderr); 3510 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3511 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3512 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3513 if (result.get_jint() != JNI_OK) { 3514 vm_exit_during_initialization(); // no message or exception 3515 } 3516 3517 universe_post_module_init(); 3518 } 3519 3520 // Phase 3. final setup - set security manager, system class loader and TCCL 3521 // 3522 // This will instantiate and set the security manager, set the system class 3523 // loader as well as the thread context class loader. The security manager 3524 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3525 // other modules or the application's classpath. 3526 static void call_initPhase3(TRAPS) { 3527 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3528 JavaValue result(T_VOID); 3529 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3530 vmSymbols::void_method_signature(), CHECK); 3531 } 3532 3533 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3534 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3535 3536 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3537 create_vm_init_libraries(); 3538 } 3539 3540 initialize_class(vmSymbols::java_lang_String(), CHECK); 3541 3542 // Inject CompactStrings value after the static initializers for String ran. 3543 java_lang_String::set_compact_strings(CompactStrings); 3544 3545 // Initialize java_lang.System (needed before creating the thread) 3546 initialize_class(vmSymbols::java_lang_System(), CHECK); 3547 // The VM creates & returns objects of this class. Make sure it's initialized. 3548 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3549 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3550 Handle thread_group = create_initial_thread_group(CHECK); 3551 Universe::set_main_thread_group(thread_group()); 3552 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3553 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3554 main_thread->set_threadObj(thread_object); 3555 // Set thread status to running since main thread has 3556 // been started and running. 3557 java_lang_Thread::set_thread_status(thread_object, 3558 java_lang_Thread::RUNNABLE); 3559 3560 // The VM creates objects of this class. 3561 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3562 3563 // The VM preresolves methods to these classes. Make sure that they get initialized 3564 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3565 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3566 3567 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3568 call_initPhase1(CHECK); 3569 3570 // get the Java runtime name after java.lang.System is initialized 3571 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3572 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3573 3574 // an instance of OutOfMemory exception has been allocated earlier 3575 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3576 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3577 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3578 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3579 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3580 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3581 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3582 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3583 } 3584 3585 void Threads::initialize_jsr292_core_classes(TRAPS) { 3586 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3587 3588 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3589 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3590 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3591 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3592 } 3593 3594 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3595 extern void JDK_Version_init(); 3596 3597 // Preinitialize version info. 3598 VM_Version::early_initialize(); 3599 3600 // Check version 3601 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3602 3603 // Initialize library-based TLS 3604 ThreadLocalStorage::init(); 3605 3606 // Initialize the output stream module 3607 ostream_init(); 3608 3609 // Process java launcher properties. 3610 Arguments::process_sun_java_launcher_properties(args); 3611 3612 // Initialize the os module 3613 os::init(); 3614 3615 // Record VM creation timing statistics 3616 TraceVmCreationTime create_vm_timer; 3617 create_vm_timer.start(); 3618 3619 // Initialize system properties. 3620 Arguments::init_system_properties(); 3621 3622 // So that JDK version can be used as a discriminator when parsing arguments 3623 JDK_Version_init(); 3624 3625 // Update/Initialize System properties after JDK version number is known 3626 Arguments::init_version_specific_system_properties(); 3627 3628 // Make sure to initialize log configuration *before* parsing arguments 3629 LogConfiguration::initialize(create_vm_timer.begin_time()); 3630 3631 // Parse arguments 3632 // Note: this internally calls os::init_container_support() 3633 jint parse_result = Arguments::parse(args); 3634 if (parse_result != JNI_OK) return parse_result; 3635 3636 os::init_before_ergo(); 3637 3638 jint ergo_result = Arguments::apply_ergo(); 3639 if (ergo_result != JNI_OK) return ergo_result; 3640 3641 // Final check of all ranges after ergonomics which may change values. 3642 if (!CommandLineFlagRangeList::check_ranges()) { 3643 return JNI_EINVAL; 3644 } 3645 3646 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3647 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3648 if (!constraint_result) { 3649 return JNI_EINVAL; 3650 } 3651 3652 CommandLineFlagWriteableList::mark_startup(); 3653 3654 if (PauseAtStartup) { 3655 os::pause(); 3656 } 3657 3658 HOTSPOT_VM_INIT_BEGIN(); 3659 3660 // Timing (must come after argument parsing) 3661 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3662 3663 // Initialize the os module after parsing the args 3664 jint os_init_2_result = os::init_2(); 3665 if (os_init_2_result != JNI_OK) return os_init_2_result; 3666 3667 SafepointMechanism::initialize(); 3668 3669 jint adjust_after_os_result = Arguments::adjust_after_os(); 3670 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3671 3672 // Initialize output stream logging 3673 ostream_init_log(); 3674 3675 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3676 // Must be before create_vm_init_agents() 3677 if (Arguments::init_libraries_at_startup()) { 3678 convert_vm_init_libraries_to_agents(); 3679 } 3680 3681 // Launch -agentlib/-agentpath and converted -Xrun agents 3682 if (Arguments::init_agents_at_startup()) { 3683 create_vm_init_agents(); 3684 } 3685 3686 // Initialize Threads state 3687 _thread_list = NULL; 3688 _number_of_threads = 0; 3689 _number_of_non_daemon_threads = 0; 3690 3691 // Initialize global data structures and create system classes in heap 3692 vm_init_globals(); 3693 3694 #if INCLUDE_JVMCI 3695 if (JVMCICounterSize > 0) { 3696 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3697 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3698 } else { 3699 JavaThread::_jvmci_old_thread_counters = NULL; 3700 } 3701 #endif // INCLUDE_JVMCI 3702 3703 // Attach the main thread to this os thread 3704 JavaThread* main_thread = new JavaThread(); 3705 main_thread->set_thread_state(_thread_in_vm); 3706 main_thread->initialize_thread_current(); 3707 // must do this before set_active_handles 3708 main_thread->record_stack_base_and_size(); 3709 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3710 3711 if (!main_thread->set_as_starting_thread()) { 3712 vm_shutdown_during_initialization( 3713 "Failed necessary internal allocation. Out of swap space"); 3714 main_thread->smr_delete(); 3715 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3716 return JNI_ENOMEM; 3717 } 3718 3719 // Enable guard page *after* os::create_main_thread(), otherwise it would 3720 // crash Linux VM, see notes in os_linux.cpp. 3721 main_thread->create_stack_guard_pages(); 3722 3723 // Initialize Java-Level synchronization subsystem 3724 ObjectMonitor::Initialize(); 3725 3726 // Initialize global modules 3727 jint status = init_globals(); 3728 if (status != JNI_OK) { 3729 main_thread->smr_delete(); 3730 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3731 return status; 3732 } 3733 3734 if (TRACE_INITIALIZE() != JNI_OK) { 3735 vm_exit_during_initialization("Failed to initialize tracing backend"); 3736 } 3737 3738 // Should be done after the heap is fully created 3739 main_thread->cache_global_variables(); 3740 3741 HandleMark hm; 3742 3743 { MutexLocker mu(Threads_lock); 3744 Threads::add(main_thread); 3745 } 3746 3747 // Any JVMTI raw monitors entered in onload will transition into 3748 // real raw monitor. VM is setup enough here for raw monitor enter. 3749 JvmtiExport::transition_pending_onload_raw_monitors(); 3750 3751 // Create the VMThread 3752 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3753 3754 VMThread::create(); 3755 Thread* vmthread = VMThread::vm_thread(); 3756 3757 if (!os::create_thread(vmthread, os::vm_thread)) { 3758 vm_exit_during_initialization("Cannot create VM thread. " 3759 "Out of system resources."); 3760 } 3761 3762 // Wait for the VM thread to become ready, and VMThread::run to initialize 3763 // Monitors can have spurious returns, must always check another state flag 3764 { 3765 MutexLocker ml(Notify_lock); 3766 os::start_thread(vmthread); 3767 while (vmthread->active_handles() == NULL) { 3768 Notify_lock->wait(); 3769 } 3770 } 3771 } 3772 3773 assert(Universe::is_fully_initialized(), "not initialized"); 3774 if (VerifyDuringStartup) { 3775 // Make sure we're starting with a clean slate. 3776 VM_Verify verify_op; 3777 VMThread::execute(&verify_op); 3778 } 3779 3780 Thread* THREAD = Thread::current(); 3781 3782 // Always call even when there are not JVMTI environments yet, since environments 3783 // may be attached late and JVMTI must track phases of VM execution 3784 JvmtiExport::enter_early_start_phase(); 3785 3786 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3787 JvmtiExport::post_early_vm_start(); 3788 3789 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3790 3791 // We need this for ClassDataSharing - the initial vm.info property is set 3792 // with the default value of CDS "sharing" which may be reset through 3793 // command line options. 3794 reset_vm_info_property(CHECK_JNI_ERR); 3795 3796 quicken_jni_functions(); 3797 3798 // No more stub generation allowed after that point. 3799 StubCodeDesc::freeze(); 3800 3801 // Set flag that basic initialization has completed. Used by exceptions and various 3802 // debug stuff, that does not work until all basic classes have been initialized. 3803 set_init_completed(); 3804 3805 LogConfiguration::post_initialize(); 3806 Metaspace::post_initialize(); 3807 3808 HOTSPOT_VM_INIT_END(); 3809 3810 // record VM initialization completion time 3811 #if INCLUDE_MANAGEMENT 3812 Management::record_vm_init_completed(); 3813 #endif // INCLUDE_MANAGEMENT 3814 3815 // Signal Dispatcher needs to be started before VMInit event is posted 3816 os::signal_init(CHECK_JNI_ERR); 3817 3818 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3819 if (!DisableAttachMechanism) { 3820 AttachListener::vm_start(); 3821 if (StartAttachListener || AttachListener::init_at_startup()) { 3822 AttachListener::init(); 3823 } 3824 } 3825 3826 // Launch -Xrun agents 3827 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3828 // back-end can launch with -Xdebug -Xrunjdwp. 3829 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3830 create_vm_init_libraries(); 3831 } 3832 3833 if (CleanChunkPoolAsync) { 3834 Chunk::start_chunk_pool_cleaner_task(); 3835 } 3836 3837 // initialize compiler(s) 3838 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3839 CompileBroker::compilation_init(CHECK_JNI_ERR); 3840 #endif 3841 3842 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3843 // It is done after compilers are initialized, because otherwise compilations of 3844 // signature polymorphic MH intrinsics can be missed 3845 // (see SystemDictionary::find_method_handle_intrinsic). 3846 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3847 3848 // This will initialize the module system. Only java.base classes can be 3849 // loaded until phase 2 completes 3850 call_initPhase2(CHECK_JNI_ERR); 3851 3852 // Always call even when there are not JVMTI environments yet, since environments 3853 // may be attached late and JVMTI must track phases of VM execution 3854 JvmtiExport::enter_start_phase(); 3855 3856 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3857 JvmtiExport::post_vm_start(); 3858 3859 // Final system initialization including security manager and system class loader 3860 call_initPhase3(CHECK_JNI_ERR); 3861 3862 // cache the system and platform class loaders 3863 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3864 3865 #if INCLUDE_JVMCI 3866 if (EnableJVMCI) { 3867 // Initialize JVMCI eagerly when it is explicitly requested. 3868 // Or when JVMCIPrintProperties is enabled. 3869 // The JVMCI Java initialization code will read this flag and 3870 // do the printing if it's set. 3871 bool init = EagerJVMCI || JVMCIPrintProperties; 3872 3873 if (!init) { 3874 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3875 // compilations via JVMCI will not actually block until JVMCI is initialized. 3876 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3877 } 3878 3879 if (init) { 3880 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3881 } 3882 } 3883 #endif 3884 3885 // Always call even when there are not JVMTI environments yet, since environments 3886 // may be attached late and JVMTI must track phases of VM execution 3887 JvmtiExport::enter_live_phase(); 3888 3889 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3890 JvmtiExport::post_vm_initialized(); 3891 3892 if (TRACE_START() != JNI_OK) { 3893 vm_exit_during_initialization("Failed to start tracing backend."); 3894 } 3895 3896 #if INCLUDE_MANAGEMENT 3897 Management::initialize(THREAD); 3898 3899 if (HAS_PENDING_EXCEPTION) { 3900 // management agent fails to start possibly due to 3901 // configuration problem and is responsible for printing 3902 // stack trace if appropriate. Simply exit VM. 3903 vm_exit(1); 3904 } 3905 #endif // INCLUDE_MANAGEMENT 3906 3907 if (MemProfiling) MemProfiler::engage(); 3908 StatSampler::engage(); 3909 if (CheckJNICalls) JniPeriodicChecker::engage(); 3910 3911 BiasedLocking::init(); 3912 3913 #if INCLUDE_RTM_OPT 3914 RTMLockingCounters::init(); 3915 #endif 3916 3917 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3918 call_postVMInitHook(THREAD); 3919 // The Java side of PostVMInitHook.run must deal with all 3920 // exceptions and provide means of diagnosis. 3921 if (HAS_PENDING_EXCEPTION) { 3922 CLEAR_PENDING_EXCEPTION; 3923 } 3924 } 3925 3926 { 3927 MutexLocker ml(PeriodicTask_lock); 3928 // Make sure the WatcherThread can be started by WatcherThread::start() 3929 // or by dynamic enrollment. 3930 WatcherThread::make_startable(); 3931 // Start up the WatcherThread if there are any periodic tasks 3932 // NOTE: All PeriodicTasks should be registered by now. If they 3933 // aren't, late joiners might appear to start slowly (we might 3934 // take a while to process their first tick). 3935 if (PeriodicTask::num_tasks() > 0) { 3936 WatcherThread::start(); 3937 } 3938 } 3939 3940 create_vm_timer.end(); 3941 #ifdef ASSERT 3942 _vm_complete = true; 3943 #endif 3944 3945 if (DumpSharedSpaces) { 3946 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3947 ShouldNotReachHere(); 3948 } 3949 3950 return JNI_OK; 3951 } 3952 3953 // type for the Agent_OnLoad and JVM_OnLoad entry points 3954 extern "C" { 3955 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3956 } 3957 // Find a command line agent library and return its entry point for 3958 // -agentlib: -agentpath: -Xrun 3959 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3960 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3961 const char *on_load_symbols[], 3962 size_t num_symbol_entries) { 3963 OnLoadEntry_t on_load_entry = NULL; 3964 void *library = NULL; 3965 3966 if (!agent->valid()) { 3967 char buffer[JVM_MAXPATHLEN]; 3968 char ebuf[1024] = ""; 3969 const char *name = agent->name(); 3970 const char *msg = "Could not find agent library "; 3971 3972 // First check to see if agent is statically linked into executable 3973 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3974 library = agent->os_lib(); 3975 } else if (agent->is_absolute_path()) { 3976 library = os::dll_load(name, ebuf, sizeof ebuf); 3977 if (library == NULL) { 3978 const char *sub_msg = " in absolute path, with error: "; 3979 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3980 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3981 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3982 // If we can't find the agent, exit. 3983 vm_exit_during_initialization(buf, NULL); 3984 FREE_C_HEAP_ARRAY(char, buf); 3985 } 3986 } else { 3987 // Try to load the agent from the standard dll directory 3988 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3989 name)) { 3990 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3991 } 3992 if (library == NULL) { // Try the library path directory. 3993 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 3994 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3995 } 3996 if (library == NULL) { 3997 const char *sub_msg = " on the library path, with error: "; 3998 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 3999 4000 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4001 strlen(ebuf) + strlen(sub_msg2) + 1; 4002 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4003 if (!agent->is_instrument_lib()) { 4004 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4005 } else { 4006 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4007 } 4008 // If we can't find the agent, exit. 4009 vm_exit_during_initialization(buf, NULL); 4010 FREE_C_HEAP_ARRAY(char, buf); 4011 } 4012 } 4013 } 4014 agent->set_os_lib(library); 4015 agent->set_valid(); 4016 } 4017 4018 // Find the OnLoad function. 4019 on_load_entry = 4020 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4021 false, 4022 on_load_symbols, 4023 num_symbol_entries)); 4024 return on_load_entry; 4025 } 4026 4027 // Find the JVM_OnLoad entry point 4028 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4029 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4030 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4031 } 4032 4033 // Find the Agent_OnLoad entry point 4034 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4035 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4036 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4037 } 4038 4039 // For backwards compatibility with -Xrun 4040 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4041 // treated like -agentpath: 4042 // Must be called before agent libraries are created 4043 void Threads::convert_vm_init_libraries_to_agents() { 4044 AgentLibrary* agent; 4045 AgentLibrary* next; 4046 4047 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4048 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4049 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4050 4051 // If there is an JVM_OnLoad function it will get called later, 4052 // otherwise see if there is an Agent_OnLoad 4053 if (on_load_entry == NULL) { 4054 on_load_entry = lookup_agent_on_load(agent); 4055 if (on_load_entry != NULL) { 4056 // switch it to the agent list -- so that Agent_OnLoad will be called, 4057 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4058 Arguments::convert_library_to_agent(agent); 4059 } else { 4060 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4061 } 4062 } 4063 } 4064 } 4065 4066 // Create agents for -agentlib: -agentpath: and converted -Xrun 4067 // Invokes Agent_OnLoad 4068 // Called very early -- before JavaThreads exist 4069 void Threads::create_vm_init_agents() { 4070 extern struct JavaVM_ main_vm; 4071 AgentLibrary* agent; 4072 4073 JvmtiExport::enter_onload_phase(); 4074 4075 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4076 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4077 4078 if (on_load_entry != NULL) { 4079 // Invoke the Agent_OnLoad function 4080 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4081 if (err != JNI_OK) { 4082 vm_exit_during_initialization("agent library failed to init", agent->name()); 4083 } 4084 } else { 4085 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4086 } 4087 } 4088 JvmtiExport::enter_primordial_phase(); 4089 } 4090 4091 extern "C" { 4092 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4093 } 4094 4095 void Threads::shutdown_vm_agents() { 4096 // Send any Agent_OnUnload notifications 4097 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4098 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4099 extern struct JavaVM_ main_vm; 4100 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4101 4102 // Find the Agent_OnUnload function. 4103 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4104 os::find_agent_function(agent, 4105 false, 4106 on_unload_symbols, 4107 num_symbol_entries)); 4108 4109 // Invoke the Agent_OnUnload function 4110 if (unload_entry != NULL) { 4111 JavaThread* thread = JavaThread::current(); 4112 ThreadToNativeFromVM ttn(thread); 4113 HandleMark hm(thread); 4114 (*unload_entry)(&main_vm); 4115 } 4116 } 4117 } 4118 4119 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4120 // Invokes JVM_OnLoad 4121 void Threads::create_vm_init_libraries() { 4122 extern struct JavaVM_ main_vm; 4123 AgentLibrary* agent; 4124 4125 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4126 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4127 4128 if (on_load_entry != NULL) { 4129 // Invoke the JVM_OnLoad function 4130 JavaThread* thread = JavaThread::current(); 4131 ThreadToNativeFromVM ttn(thread); 4132 HandleMark hm(thread); 4133 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4134 if (err != JNI_OK) { 4135 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4136 } 4137 } else { 4138 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4139 } 4140 } 4141 } 4142 4143 4144 // Last thread running calls java.lang.Shutdown.shutdown() 4145 void JavaThread::invoke_shutdown_hooks() { 4146 HandleMark hm(this); 4147 4148 // We could get here with a pending exception, if so clear it now. 4149 if (this->has_pending_exception()) { 4150 this->clear_pending_exception(); 4151 } 4152 4153 EXCEPTION_MARK; 4154 Klass* shutdown_klass = 4155 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4156 THREAD); 4157 if (shutdown_klass != NULL) { 4158 // SystemDictionary::resolve_or_null will return null if there was 4159 // an exception. If we cannot load the Shutdown class, just don't 4160 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4161 // won't be run. Note that if a shutdown hook was registered, 4162 // the Shutdown class would have already been loaded 4163 // (Runtime.addShutdownHook will load it). 4164 JavaValue result(T_VOID); 4165 JavaCalls::call_static(&result, 4166 shutdown_klass, 4167 vmSymbols::shutdown_method_name(), 4168 vmSymbols::void_method_signature(), 4169 THREAD); 4170 } 4171 CLEAR_PENDING_EXCEPTION; 4172 } 4173 4174 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4175 // the program falls off the end of main(). Another VM exit path is through 4176 // vm_exit() when the program calls System.exit() to return a value or when 4177 // there is a serious error in VM. The two shutdown paths are not exactly 4178 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4179 // and VM_Exit op at VM level. 4180 // 4181 // Shutdown sequence: 4182 // + Shutdown native memory tracking if it is on 4183 // + Wait until we are the last non-daemon thread to execute 4184 // <-- every thing is still working at this moment --> 4185 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4186 // shutdown hooks 4187 // + Call before_exit(), prepare for VM exit 4188 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4189 // currently the only user of this mechanism is File.deleteOnExit()) 4190 // > stop StatSampler, watcher thread, CMS threads, 4191 // post thread end and vm death events to JVMTI, 4192 // stop signal thread 4193 // + Call JavaThread::exit(), it will: 4194 // > release JNI handle blocks, remove stack guard pages 4195 // > remove this thread from Threads list 4196 // <-- no more Java code from this thread after this point --> 4197 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4198 // the compiler threads at safepoint 4199 // <-- do not use anything that could get blocked by Safepoint --> 4200 // + Disable tracing at JNI/JVM barriers 4201 // + Set _vm_exited flag for threads that are still running native code 4202 // + Delete this thread 4203 // + Call exit_globals() 4204 // > deletes tty 4205 // > deletes PerfMemory resources 4206 // + Return to caller 4207 4208 bool Threads::destroy_vm() { 4209 JavaThread* thread = JavaThread::current(); 4210 4211 #ifdef ASSERT 4212 _vm_complete = false; 4213 #endif 4214 // Wait until we are the last non-daemon thread to execute 4215 { MutexLocker nu(Threads_lock); 4216 while (Threads::number_of_non_daemon_threads() > 1) 4217 // This wait should make safepoint checks, wait without a timeout, 4218 // and wait as a suspend-equivalent condition. 4219 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4220 Mutex::_as_suspend_equivalent_flag); 4221 } 4222 4223 EventShutdown e; 4224 if (e.should_commit()) { 4225 e.set_reason("No remaining non-daemon Java threads"); 4226 e.commit(); 4227 } 4228 4229 // Hang forever on exit if we are reporting an error. 4230 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4231 os::infinite_sleep(); 4232 } 4233 os::wait_for_keypress_at_exit(); 4234 4235 // run Java level shutdown hooks 4236 thread->invoke_shutdown_hooks(); 4237 4238 before_exit(thread); 4239 4240 thread->exit(true); 4241 4242 // Stop VM thread. 4243 { 4244 // 4945125 The vm thread comes to a safepoint during exit. 4245 // GC vm_operations can get caught at the safepoint, and the 4246 // heap is unparseable if they are caught. Grab the Heap_lock 4247 // to prevent this. The GC vm_operations will not be able to 4248 // queue until after the vm thread is dead. After this point, 4249 // we'll never emerge out of the safepoint before the VM exits. 4250 4251 MutexLocker ml(Heap_lock); 4252 4253 VMThread::wait_for_vm_thread_exit(); 4254 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4255 VMThread::destroy(); 4256 } 4257 4258 // clean up ideal graph printers 4259 #if defined(COMPILER2) && !defined(PRODUCT) 4260 IdealGraphPrinter::clean_up(); 4261 #endif 4262 4263 // Now, all Java threads are gone except daemon threads. Daemon threads 4264 // running Java code or in VM are stopped by the Safepoint. However, 4265 // daemon threads executing native code are still running. But they 4266 // will be stopped at native=>Java/VM barriers. Note that we can't 4267 // simply kill or suspend them, as it is inherently deadlock-prone. 4268 4269 VM_Exit::set_vm_exited(); 4270 4271 notify_vm_shutdown(); 4272 4273 // We are after VM_Exit::set_vm_exited() so we can't call 4274 // thread->smr_delete() or we will block on the Threads_lock. 4275 // Deleting the shutdown thread here is safe because another 4276 // JavaThread cannot have an active ThreadsListHandle for 4277 // this JavaThread. 4278 delete thread; 4279 4280 #if INCLUDE_JVMCI 4281 if (JVMCICounterSize > 0) { 4282 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4283 } 4284 #endif 4285 4286 // exit_globals() will delete tty 4287 exit_globals(); 4288 4289 LogConfiguration::finalize(); 4290 4291 return true; 4292 } 4293 4294 4295 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4296 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4297 return is_supported_jni_version(version); 4298 } 4299 4300 4301 jboolean Threads::is_supported_jni_version(jint version) { 4302 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4303 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4304 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4305 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4306 if (version == JNI_VERSION_9) return JNI_TRUE; 4307 if (version == JNI_VERSION_10) return JNI_TRUE; 4308 return JNI_FALSE; 4309 } 4310 4311 4312 void Threads::add(JavaThread* p, bool force_daemon) { 4313 // The threads lock must be owned at this point 4314 assert_locked_or_safepoint(Threads_lock); 4315 4316 BarrierSet::barrier_set()->on_thread_attach(p); 4317 p->set_next(_thread_list); 4318 _thread_list = p; 4319 4320 // Once a JavaThread is added to the Threads list, smr_delete() has 4321 // to be used to delete it. Otherwise we can just delete it directly. 4322 p->set_on_thread_list(); 4323 4324 _number_of_threads++; 4325 oop threadObj = p->threadObj(); 4326 bool daemon = true; 4327 // Bootstrapping problem: threadObj can be null for initial 4328 // JavaThread (or for threads attached via JNI) 4329 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4330 _number_of_non_daemon_threads++; 4331 daemon = false; 4332 } 4333 4334 ThreadService::add_thread(p, daemon); 4335 4336 // Maintain fast thread list 4337 ThreadsSMRSupport::add_thread(p); 4338 4339 // Possible GC point. 4340 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4341 } 4342 4343 void Threads::remove(JavaThread* p) { 4344 4345 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4346 ObjectSynchronizer::omFlush(p); 4347 4348 // Extra scope needed for Thread_lock, so we can check 4349 // that we do not remove thread without safepoint code notice 4350 { MutexLocker ml(Threads_lock); 4351 4352 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4353 4354 // Maintain fast thread list 4355 ThreadsSMRSupport::remove_thread(p); 4356 4357 JavaThread* current = _thread_list; 4358 JavaThread* prev = NULL; 4359 4360 while (current != p) { 4361 prev = current; 4362 current = current->next(); 4363 } 4364 4365 if (prev) { 4366 prev->set_next(current->next()); 4367 } else { 4368 _thread_list = p->next(); 4369 } 4370 4371 _number_of_threads--; 4372 oop threadObj = p->threadObj(); 4373 bool daemon = true; 4374 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4375 _number_of_non_daemon_threads--; 4376 daemon = false; 4377 4378 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4379 // on destroy_vm will wake up. 4380 if (number_of_non_daemon_threads() == 1) { 4381 Threads_lock->notify_all(); 4382 } 4383 } 4384 ThreadService::remove_thread(p, daemon); 4385 4386 // Make sure that safepoint code disregard this thread. This is needed since 4387 // the thread might mess around with locks after this point. This can cause it 4388 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4389 // of this thread since it is removed from the queue. 4390 p->set_terminated_value(); 4391 } // unlock Threads_lock 4392 4393 // Since Events::log uses a lock, we grab it outside the Threads_lock 4394 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4395 } 4396 4397 // Operations on the Threads list for GC. These are not explicitly locked, 4398 // but the garbage collector must provide a safe context for them to run. 4399 // In particular, these things should never be called when the Threads_lock 4400 // is held by some other thread. (Note: the Safepoint abstraction also 4401 // uses the Threads_lock to guarantee this property. It also makes sure that 4402 // all threads gets blocked when exiting or starting). 4403 4404 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4405 ALL_JAVA_THREADS(p) { 4406 p->oops_do(f, cf); 4407 } 4408 VMThread::vm_thread()->oops_do(f, cf); 4409 } 4410 4411 void Threads::change_thread_claim_parity() { 4412 // Set the new claim parity. 4413 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4414 "Not in range."); 4415 _thread_claim_parity++; 4416 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4417 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4418 "Not in range."); 4419 } 4420 4421 #ifdef ASSERT 4422 void Threads::assert_all_threads_claimed() { 4423 ALL_JAVA_THREADS(p) { 4424 const int thread_parity = p->oops_do_parity(); 4425 assert((thread_parity == _thread_claim_parity), 4426 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4427 } 4428 VMThread* vmt = VMThread::vm_thread(); 4429 const int thread_parity = vmt->oops_do_parity(); 4430 assert((thread_parity == _thread_claim_parity), 4431 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4432 } 4433 #endif // ASSERT 4434 4435 class ParallelOopsDoThreadClosure : public ThreadClosure { 4436 private: 4437 OopClosure* _f; 4438 CodeBlobClosure* _cf; 4439 public: 4440 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4441 void do_thread(Thread* t) { 4442 t->oops_do(_f, _cf); 4443 } 4444 }; 4445 4446 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4447 ParallelOopsDoThreadClosure tc(f, cf); 4448 possibly_parallel_threads_do(is_par, &tc); 4449 } 4450 4451 #if INCLUDE_ALL_GCS 4452 // Used by ParallelScavenge 4453 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4454 ALL_JAVA_THREADS(p) { 4455 q->enqueue(new ThreadRootsTask(p)); 4456 } 4457 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4458 } 4459 4460 // Used by Parallel Old 4461 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4462 ALL_JAVA_THREADS(p) { 4463 q->enqueue(new ThreadRootsMarkingTask(p)); 4464 } 4465 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4466 } 4467 #endif // INCLUDE_ALL_GCS 4468 4469 void Threads::nmethods_do(CodeBlobClosure* cf) { 4470 ALL_JAVA_THREADS(p) { 4471 // This is used by the code cache sweeper to mark nmethods that are active 4472 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4473 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4474 if(!p->is_Code_cache_sweeper_thread()) { 4475 p->nmethods_do(cf); 4476 } 4477 } 4478 } 4479 4480 void Threads::metadata_do(void f(Metadata*)) { 4481 ALL_JAVA_THREADS(p) { 4482 p->metadata_do(f); 4483 } 4484 } 4485 4486 class ThreadHandlesClosure : public ThreadClosure { 4487 void (*_f)(Metadata*); 4488 public: 4489 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4490 virtual void do_thread(Thread* thread) { 4491 thread->metadata_handles_do(_f); 4492 } 4493 }; 4494 4495 void Threads::metadata_handles_do(void f(Metadata*)) { 4496 // Only walk the Handles in Thread. 4497 ThreadHandlesClosure handles_closure(f); 4498 threads_do(&handles_closure); 4499 } 4500 4501 void Threads::deoptimized_wrt_marked_nmethods() { 4502 ALL_JAVA_THREADS(p) { 4503 p->deoptimized_wrt_marked_nmethods(); 4504 } 4505 } 4506 4507 4508 // Get count Java threads that are waiting to enter the specified monitor. 4509 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4510 int count, 4511 address monitor) { 4512 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4513 4514 int i = 0; 4515 DO_JAVA_THREADS(t_list, p) { 4516 if (!p->can_call_java()) continue; 4517 4518 address pending = (address)p->current_pending_monitor(); 4519 if (pending == monitor) { // found a match 4520 if (i < count) result->append(p); // save the first count matches 4521 i++; 4522 } 4523 } 4524 4525 return result; 4526 } 4527 4528 4529 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4530 address owner) { 4531 // NULL owner means not locked so we can skip the search 4532 if (owner == NULL) return NULL; 4533 4534 DO_JAVA_THREADS(t_list, p) { 4535 // first, see if owner is the address of a Java thread 4536 if (owner == (address)p) return p; 4537 } 4538 4539 // Cannot assert on lack of success here since this function may be 4540 // used by code that is trying to report useful problem information 4541 // like deadlock detection. 4542 if (UseHeavyMonitors) return NULL; 4543 4544 // If we didn't find a matching Java thread and we didn't force use of 4545 // heavyweight monitors, then the owner is the stack address of the 4546 // Lock Word in the owning Java thread's stack. 4547 // 4548 JavaThread* the_owner = NULL; 4549 DO_JAVA_THREADS(t_list, q) { 4550 if (q->is_lock_owned(owner)) { 4551 the_owner = q; 4552 break; 4553 } 4554 } 4555 4556 // cannot assert on lack of success here; see above comment 4557 return the_owner; 4558 } 4559 4560 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4561 void Threads::print_on(outputStream* st, bool print_stacks, 4562 bool internal_format, bool print_concurrent_locks) { 4563 char buf[32]; 4564 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4565 4566 st->print_cr("Full thread dump %s (%s %s):", 4567 Abstract_VM_Version::vm_name(), 4568 Abstract_VM_Version::vm_release(), 4569 Abstract_VM_Version::vm_info_string()); 4570 st->cr(); 4571 4572 #if INCLUDE_SERVICES 4573 // Dump concurrent locks 4574 ConcurrentLocksDump concurrent_locks; 4575 if (print_concurrent_locks) { 4576 concurrent_locks.dump_at_safepoint(); 4577 } 4578 #endif // INCLUDE_SERVICES 4579 4580 ThreadsSMRSupport::print_info_on(st); 4581 st->cr(); 4582 4583 ALL_JAVA_THREADS(p) { 4584 ResourceMark rm; 4585 p->print_on(st); 4586 if (print_stacks) { 4587 if (internal_format) { 4588 p->trace_stack(); 4589 } else { 4590 p->print_stack_on(st); 4591 } 4592 } 4593 st->cr(); 4594 #if INCLUDE_SERVICES 4595 if (print_concurrent_locks) { 4596 concurrent_locks.print_locks_on(p, st); 4597 } 4598 #endif // INCLUDE_SERVICES 4599 } 4600 4601 VMThread::vm_thread()->print_on(st); 4602 st->cr(); 4603 Universe::heap()->print_gc_threads_on(st); 4604 WatcherThread* wt = WatcherThread::watcher_thread(); 4605 if (wt != NULL) { 4606 wt->print_on(st); 4607 st->cr(); 4608 } 4609 4610 st->flush(); 4611 } 4612 4613 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4614 int buflen, bool* found_current) { 4615 if (this_thread != NULL) { 4616 bool is_current = (current == this_thread); 4617 *found_current = *found_current || is_current; 4618 st->print("%s", is_current ? "=>" : " "); 4619 4620 st->print(PTR_FORMAT, p2i(this_thread)); 4621 st->print(" "); 4622 this_thread->print_on_error(st, buf, buflen); 4623 st->cr(); 4624 } 4625 } 4626 4627 class PrintOnErrorClosure : public ThreadClosure { 4628 outputStream* _st; 4629 Thread* _current; 4630 char* _buf; 4631 int _buflen; 4632 bool* _found_current; 4633 public: 4634 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4635 int buflen, bool* found_current) : 4636 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4637 4638 virtual void do_thread(Thread* thread) { 4639 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4640 } 4641 }; 4642 4643 // Threads::print_on_error() is called by fatal error handler. It's possible 4644 // that VM is not at safepoint and/or current thread is inside signal handler. 4645 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4646 // memory (even in resource area), it might deadlock the error handler. 4647 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4648 int buflen) { 4649 ThreadsSMRSupport::print_info_on(st); 4650 st->cr(); 4651 4652 bool found_current = false; 4653 st->print_cr("Java Threads: ( => current thread )"); 4654 ALL_JAVA_THREADS(thread) { 4655 print_on_error(thread, st, current, buf, buflen, &found_current); 4656 } 4657 st->cr(); 4658 4659 st->print_cr("Other Threads:"); 4660 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4661 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4662 4663 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4664 Universe::heap()->gc_threads_do(&print_closure); 4665 4666 if (!found_current) { 4667 st->cr(); 4668 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4669 current->print_on_error(st, buf, buflen); 4670 st->cr(); 4671 } 4672 st->cr(); 4673 4674 st->print_cr("Threads with active compile tasks:"); 4675 print_threads_compiling(st, buf, buflen); 4676 } 4677 4678 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4679 ALL_JAVA_THREADS(thread) { 4680 if (thread->is_Compiler_thread()) { 4681 CompilerThread* ct = (CompilerThread*) thread; 4682 4683 // Keep task in local variable for NULL check. 4684 // ct->_task might be set to NULL by concurring compiler thread 4685 // because it completed the compilation. The task is never freed, 4686 // though, just returned to a free list. 4687 CompileTask* task = ct->task(); 4688 if (task != NULL) { 4689 thread->print_name_on_error(st, buf, buflen); 4690 task->print(st, NULL, true, true); 4691 } 4692 } 4693 } 4694 } 4695 4696 4697 // Internal SpinLock and Mutex 4698 // Based on ParkEvent 4699 4700 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4701 // 4702 // We employ SpinLocks _only for low-contention, fixed-length 4703 // short-duration critical sections where we're concerned 4704 // about native mutex_t or HotSpot Mutex:: latency. 4705 // The mux construct provides a spin-then-block mutual exclusion 4706 // mechanism. 4707 // 4708 // Testing has shown that contention on the ListLock guarding gFreeList 4709 // is common. If we implement ListLock as a simple SpinLock it's common 4710 // for the JVM to devolve to yielding with little progress. This is true 4711 // despite the fact that the critical sections protected by ListLock are 4712 // extremely short. 4713 // 4714 // TODO-FIXME: ListLock should be of type SpinLock. 4715 // We should make this a 1st-class type, integrated into the lock 4716 // hierarchy as leaf-locks. Critically, the SpinLock structure 4717 // should have sufficient padding to avoid false-sharing and excessive 4718 // cache-coherency traffic. 4719 4720 4721 typedef volatile int SpinLockT; 4722 4723 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4724 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4725 return; // normal fast-path return 4726 } 4727 4728 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4729 TEVENT(SpinAcquire - ctx); 4730 int ctr = 0; 4731 int Yields = 0; 4732 for (;;) { 4733 while (*adr != 0) { 4734 ++ctr; 4735 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4736 if (Yields > 5) { 4737 os::naked_short_sleep(1); 4738 } else { 4739 os::naked_yield(); 4740 ++Yields; 4741 } 4742 } else { 4743 SpinPause(); 4744 } 4745 } 4746 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4747 } 4748 } 4749 4750 void Thread::SpinRelease(volatile int * adr) { 4751 assert(*adr != 0, "invariant"); 4752 OrderAccess::fence(); // guarantee at least release consistency. 4753 // Roach-motel semantics. 4754 // It's safe if subsequent LDs and STs float "up" into the critical section, 4755 // but prior LDs and STs within the critical section can't be allowed 4756 // to reorder or float past the ST that releases the lock. 4757 // Loads and stores in the critical section - which appear in program 4758 // order before the store that releases the lock - must also appear 4759 // before the store that releases the lock in memory visibility order. 4760 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4761 // the ST of 0 into the lock-word which releases the lock, so fence 4762 // more than covers this on all platforms. 4763 *adr = 0; 4764 } 4765 4766 // muxAcquire and muxRelease: 4767 // 4768 // * muxAcquire and muxRelease support a single-word lock-word construct. 4769 // The LSB of the word is set IFF the lock is held. 4770 // The remainder of the word points to the head of a singly-linked list 4771 // of threads blocked on the lock. 4772 // 4773 // * The current implementation of muxAcquire-muxRelease uses its own 4774 // dedicated Thread._MuxEvent instance. If we're interested in 4775 // minimizing the peak number of extant ParkEvent instances then 4776 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4777 // as certain invariants were satisfied. Specifically, care would need 4778 // to be taken with regards to consuming unpark() "permits". 4779 // A safe rule of thumb is that a thread would never call muxAcquire() 4780 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4781 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4782 // consume an unpark() permit intended for monitorenter, for instance. 4783 // One way around this would be to widen the restricted-range semaphore 4784 // implemented in park(). Another alternative would be to provide 4785 // multiple instances of the PlatformEvent() for each thread. One 4786 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4787 // 4788 // * Usage: 4789 // -- Only as leaf locks 4790 // -- for short-term locking only as muxAcquire does not perform 4791 // thread state transitions. 4792 // 4793 // Alternatives: 4794 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4795 // but with parking or spin-then-park instead of pure spinning. 4796 // * Use Taura-Oyama-Yonenzawa locks. 4797 // * It's possible to construct a 1-0 lock if we encode the lockword as 4798 // (List,LockByte). Acquire will CAS the full lockword while Release 4799 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4800 // acquiring threads use timers (ParkTimed) to detect and recover from 4801 // the stranding window. Thread/Node structures must be aligned on 256-byte 4802 // boundaries by using placement-new. 4803 // * Augment MCS with advisory back-link fields maintained with CAS(). 4804 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4805 // The validity of the backlinks must be ratified before we trust the value. 4806 // If the backlinks are invalid the exiting thread must back-track through the 4807 // the forward links, which are always trustworthy. 4808 // * Add a successor indication. The LockWord is currently encoded as 4809 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4810 // to provide the usual futile-wakeup optimization. 4811 // See RTStt for details. 4812 // * Consider schedctl.sc_nopreempt to cover the critical section. 4813 // 4814 4815 4816 const intptr_t LOCKBIT = 1; 4817 4818 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4819 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4820 if (w == 0) return; 4821 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4822 return; 4823 } 4824 4825 TEVENT(muxAcquire - Contention); 4826 ParkEvent * const Self = Thread::current()->_MuxEvent; 4827 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4828 for (;;) { 4829 int its = (os::is_MP() ? 100 : 0) + 1; 4830 4831 // Optional spin phase: spin-then-park strategy 4832 while (--its >= 0) { 4833 w = *Lock; 4834 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4835 return; 4836 } 4837 } 4838 4839 Self->reset(); 4840 Self->OnList = intptr_t(Lock); 4841 // The following fence() isn't _strictly necessary as the subsequent 4842 // CAS() both serializes execution and ratifies the fetched *Lock value. 4843 OrderAccess::fence(); 4844 for (;;) { 4845 w = *Lock; 4846 if ((w & LOCKBIT) == 0) { 4847 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4848 Self->OnList = 0; // hygiene - allows stronger asserts 4849 return; 4850 } 4851 continue; // Interference -- *Lock changed -- Just retry 4852 } 4853 assert(w & LOCKBIT, "invariant"); 4854 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4855 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4856 } 4857 4858 while (Self->OnList != 0) { 4859 Self->park(); 4860 } 4861 } 4862 } 4863 4864 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4865 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4866 if (w == 0) return; 4867 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4868 return; 4869 } 4870 4871 TEVENT(muxAcquire - Contention); 4872 ParkEvent * ReleaseAfter = NULL; 4873 if (ev == NULL) { 4874 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4875 } 4876 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4877 for (;;) { 4878 guarantee(ev->OnList == 0, "invariant"); 4879 int its = (os::is_MP() ? 100 : 0) + 1; 4880 4881 // Optional spin phase: spin-then-park strategy 4882 while (--its >= 0) { 4883 w = *Lock; 4884 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4885 if (ReleaseAfter != NULL) { 4886 ParkEvent::Release(ReleaseAfter); 4887 } 4888 return; 4889 } 4890 } 4891 4892 ev->reset(); 4893 ev->OnList = intptr_t(Lock); 4894 // The following fence() isn't _strictly necessary as the subsequent 4895 // CAS() both serializes execution and ratifies the fetched *Lock value. 4896 OrderAccess::fence(); 4897 for (;;) { 4898 w = *Lock; 4899 if ((w & LOCKBIT) == 0) { 4900 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4901 ev->OnList = 0; 4902 // We call ::Release while holding the outer lock, thus 4903 // artificially lengthening the critical section. 4904 // Consider deferring the ::Release() until the subsequent unlock(), 4905 // after we've dropped the outer lock. 4906 if (ReleaseAfter != NULL) { 4907 ParkEvent::Release(ReleaseAfter); 4908 } 4909 return; 4910 } 4911 continue; // Interference -- *Lock changed -- Just retry 4912 } 4913 assert(w & LOCKBIT, "invariant"); 4914 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4915 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4916 } 4917 4918 while (ev->OnList != 0) { 4919 ev->park(); 4920 } 4921 } 4922 } 4923 4924 // Release() must extract a successor from the list and then wake that thread. 4925 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4926 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4927 // Release() would : 4928 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4929 // (B) Extract a successor from the private list "in-hand" 4930 // (C) attempt to CAS() the residual back into *Lock over null. 4931 // If there were any newly arrived threads and the CAS() would fail. 4932 // In that case Release() would detach the RATs, re-merge the list in-hand 4933 // with the RATs and repeat as needed. Alternately, Release() might 4934 // detach and extract a successor, but then pass the residual list to the wakee. 4935 // The wakee would be responsible for reattaching and remerging before it 4936 // competed for the lock. 4937 // 4938 // Both "pop" and DMR are immune from ABA corruption -- there can be 4939 // multiple concurrent pushers, but only one popper or detacher. 4940 // This implementation pops from the head of the list. This is unfair, 4941 // but tends to provide excellent throughput as hot threads remain hot. 4942 // (We wake recently run threads first). 4943 // 4944 // All paths through muxRelease() will execute a CAS. 4945 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4946 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4947 // executed within the critical section are complete and globally visible before the 4948 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4949 void Thread::muxRelease(volatile intptr_t * Lock) { 4950 for (;;) { 4951 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4952 assert(w & LOCKBIT, "invariant"); 4953 if (w == LOCKBIT) return; 4954 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4955 assert(List != NULL, "invariant"); 4956 assert(List->OnList == intptr_t(Lock), "invariant"); 4957 ParkEvent * const nxt = List->ListNext; 4958 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4959 4960 // The following CAS() releases the lock and pops the head element. 4961 // The CAS() also ratifies the previously fetched lock-word value. 4962 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4963 continue; 4964 } 4965 List->OnList = 0; 4966 OrderAccess::fence(); 4967 List->unpark(); 4968 return; 4969 } 4970 } 4971 4972 4973 void Threads::verify() { 4974 ALL_JAVA_THREADS(p) { 4975 p->verify(); 4976 } 4977 VMThread* thread = VMThread::vm_thread(); 4978 if (thread != NULL) thread->verify(); 4979 }