1 /* 2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoader.hpp" 27 #include "classfile/javaClasses.hpp" 28 #include "classfile/systemDictionary.hpp" 29 #include "classfile/vmSymbols.hpp" 30 #include "code/scopeDesc.hpp" 31 #include "compiler/compileBroker.hpp" 32 #include "interpreter/interpreter.hpp" 33 #include "interpreter/linkResolver.hpp" 34 #include "interpreter/oopMapCache.hpp" 35 #include "jvmtifiles/jvmtiEnv.hpp" 36 #include "memory/gcLocker.inline.hpp" 37 #include "memory/oopFactory.hpp" 38 #include "memory/universe.inline.hpp" 39 #include "oops/instanceKlass.hpp" 40 #include "oops/objArrayOop.hpp" 41 #include "oops/oop.inline.hpp" 42 #include "oops/symbol.hpp" 43 #include "prims/jvm_misc.hpp" 44 #include "prims/jvmtiExport.hpp" 45 #include "prims/jvmtiThreadState.hpp" 46 #include "prims/privilegedStack.hpp" 47 #include "runtime/aprofiler.hpp" 48 #include "runtime/arguments.hpp" 49 #include "runtime/biasedLocking.hpp" 50 #include "runtime/deoptimization.hpp" 51 #include "runtime/fprofiler.hpp" 52 #include "runtime/frame.inline.hpp" 53 #include "runtime/init.hpp" 54 #include "runtime/interfaceSupport.hpp" 55 #include "runtime/java.hpp" 56 #include "runtime/javaCalls.hpp" 57 #include "runtime/jniPeriodicChecker.hpp" 58 #include "runtime/memprofiler.hpp" 59 #include "runtime/mutexLocker.hpp" 60 #include "runtime/objectMonitor.hpp" 61 #include "runtime/osThread.hpp" 62 #include "runtime/safepoint.hpp" 63 #include "runtime/sharedRuntime.hpp" 64 #include "runtime/statSampler.hpp" 65 #include "runtime/stubRoutines.hpp" 66 #include "runtime/task.hpp" 67 #include "runtime/threadCritical.hpp" 68 #include "runtime/threadLocalStorage.hpp" 69 #include "runtime/vframe.hpp" 70 #include "runtime/vframeArray.hpp" 71 #include "runtime/vframe_hp.hpp" 72 #include "runtime/vmThread.hpp" 73 #include "runtime/vm_operations.hpp" 74 #include "services/attachListener.hpp" 75 #include "services/management.hpp" 76 #include "services/threadService.hpp" 77 #include "trace/traceEventTypes.hpp" 78 #include "utilities/defaultStream.hpp" 79 #include "utilities/dtrace.hpp" 80 #include "utilities/events.hpp" 81 #include "utilities/preserveException.hpp" 82 #ifdef TARGET_OS_FAMILY_linux 83 # include "os_linux.inline.hpp" 84 # include "thread_linux.inline.hpp" 85 #endif 86 #ifdef TARGET_OS_FAMILY_solaris 87 # include "os_solaris.inline.hpp" 88 # include "thread_solaris.inline.hpp" 89 #endif 90 #ifdef TARGET_OS_FAMILY_windows 91 # include "os_windows.inline.hpp" 92 # include "thread_windows.inline.hpp" 93 #endif 94 #ifdef TARGET_OS_FAMILY_bsd 95 # include "os_bsd.inline.hpp" 96 # include "thread_bsd.inline.hpp" 97 #endif 98 #ifndef SERIALGC 99 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 100 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 101 #include "gc_implementation/parallelScavenge/pcTasks.hpp" 102 #endif 103 #ifdef COMPILER1 104 #include "c1/c1_Compiler.hpp" 105 #endif 106 #ifdef COMPILER2 107 #include "opto/c2compiler.hpp" 108 #include "opto/idealGraphPrinter.hpp" 109 #endif 110 111 #ifdef DTRACE_ENABLED 112 113 // Only bother with this argument setup if dtrace is available 114 115 #ifndef USDT2 116 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin); 117 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end); 118 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t, 119 intptr_t, intptr_t, bool); 120 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t, 121 intptr_t, intptr_t, bool); 122 123 #define DTRACE_THREAD_PROBE(probe, javathread) \ 124 { \ 125 ResourceMark rm(this); \ 126 int len = 0; \ 127 const char* name = (javathread)->get_thread_name(); \ 128 len = strlen(name); \ 129 HS_DTRACE_PROBE5(hotspot, thread__##probe, \ 130 name, len, \ 131 java_lang_Thread::thread_id((javathread)->threadObj()), \ 132 (javathread)->osthread()->thread_id(), \ 133 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 134 } 135 136 #else /* USDT2 */ 137 138 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_PROBE_START 139 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_PROBE_STOP 140 141 #define DTRACE_THREAD_PROBE(probe, javathread) \ 142 { \ 143 ResourceMark rm(this); \ 144 int len = 0; \ 145 const char* name = (javathread)->get_thread_name(); \ 146 len = strlen(name); \ 147 HOTSPOT_THREAD_PROBE_##probe( /* probe = start, stop */ \ 148 (char *) name, len, \ 149 java_lang_Thread::thread_id((javathread)->threadObj()), \ 150 (uintptr_t) (javathread)->osthread()->thread_id(), \ 151 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 152 } 153 154 #endif /* USDT2 */ 155 156 #else // ndef DTRACE_ENABLED 157 158 #define DTRACE_THREAD_PROBE(probe, javathread) 159 160 #endif // ndef DTRACE_ENABLED 161 162 // Class hierarchy 163 // - Thread 164 // - VMThread 165 // - WatcherThread 166 // - ConcurrentMarkSweepThread 167 // - JavaThread 168 // - CompilerThread 169 170 // ======= Thread ======== 171 172 // Support for forcing alignment of thread objects for biased locking 173 void* Thread::operator new(size_t size) { 174 if (UseBiasedLocking) { 175 const int alignment = markOopDesc::biased_lock_alignment; 176 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 177 void* real_malloc_addr = CHeapObj::operator new(aligned_size); 178 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 179 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 180 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 181 "JavaThread alignment code overflowed allocated storage"); 182 if (TraceBiasedLocking) { 183 if (aligned_addr != real_malloc_addr) 184 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 185 real_malloc_addr, aligned_addr); 186 } 187 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 188 return aligned_addr; 189 } else { 190 return CHeapObj::operator new(size); 191 } 192 } 193 194 void Thread::operator delete(void* p) { 195 if (UseBiasedLocking) { 196 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 197 CHeapObj::operator delete(real_malloc_addr); 198 } else { 199 CHeapObj::operator delete(p); 200 } 201 } 202 203 204 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 205 // JavaThread 206 207 208 Thread::Thread() { 209 // stack and get_thread 210 set_stack_base(NULL); 211 set_stack_size(0); 212 set_self_raw_id(0); 213 set_lgrp_id(-1); 214 215 // allocated data structures 216 set_osthread(NULL); 217 set_resource_area(new ResourceArea()); 218 set_handle_area(new HandleArea(NULL)); 219 set_active_handles(NULL); 220 set_free_handle_block(NULL); 221 set_last_handle_mark(NULL); 222 223 // This initial value ==> never claimed. 224 _oops_do_parity = 0; 225 226 // the handle mark links itself to last_handle_mark 227 new HandleMark(this); 228 229 // plain initialization 230 debug_only(_owned_locks = NULL;) 231 debug_only(_allow_allocation_count = 0;) 232 NOT_PRODUCT(_allow_safepoint_count = 0;) 233 NOT_PRODUCT(_skip_gcalot = false;) 234 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;) 235 _jvmti_env_iteration_count = 0; 236 set_allocated_bytes(0); 237 set_trace_buffer(NULL); 238 _vm_operation_started_count = 0; 239 _vm_operation_completed_count = 0; 240 _current_pending_monitor = NULL; 241 _current_pending_monitor_is_from_java = true; 242 _current_waiting_monitor = NULL; 243 _num_nested_signal = 0; 244 omFreeList = NULL ; 245 omFreeCount = 0 ; 246 omFreeProvision = 32 ; 247 omInUseList = NULL ; 248 omInUseCount = 0 ; 249 250 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true); 251 _suspend_flags = 0; 252 253 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 254 _hashStateX = os::random() ; 255 _hashStateY = 842502087 ; 256 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ; 257 _hashStateW = 273326509 ; 258 259 _OnTrap = 0 ; 260 _schedctl = NULL ; 261 _Stalled = 0 ; 262 _TypeTag = 0x2BAD ; 263 264 // Many of the following fields are effectively final - immutable 265 // Note that nascent threads can't use the Native Monitor-Mutex 266 // construct until the _MutexEvent is initialized ... 267 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 268 // we might instead use a stack of ParkEvents that we could provision on-demand. 269 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 270 // and ::Release() 271 _ParkEvent = ParkEvent::Allocate (this) ; 272 _SleepEvent = ParkEvent::Allocate (this) ; 273 _MutexEvent = ParkEvent::Allocate (this) ; 274 _MuxEvent = ParkEvent::Allocate (this) ; 275 276 #ifdef CHECK_UNHANDLED_OOPS 277 if (CheckUnhandledOops) { 278 _unhandled_oops = new UnhandledOops(this); 279 } 280 #endif // CHECK_UNHANDLED_OOPS 281 #ifdef ASSERT 282 if (UseBiasedLocking) { 283 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 284 assert(this == _real_malloc_address || 285 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 286 "bug in forced alignment of thread objects"); 287 } 288 #endif /* ASSERT */ 289 } 290 291 void Thread::initialize_thread_local_storage() { 292 // Note: Make sure this method only calls 293 // non-blocking operations. Otherwise, it might not work 294 // with the thread-startup/safepoint interaction. 295 296 // During Java thread startup, safepoint code should allow this 297 // method to complete because it may need to allocate memory to 298 // store information for the new thread. 299 300 // initialize structure dependent on thread local storage 301 ThreadLocalStorage::set_thread(this); 302 303 // set up any platform-specific state. 304 os::initialize_thread(); 305 306 } 307 308 void Thread::record_stack_base_and_size() { 309 set_stack_base(os::current_stack_base()); 310 set_stack_size(os::current_stack_size()); 311 } 312 313 314 Thread::~Thread() { 315 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 316 ObjectSynchronizer::omFlush (this) ; 317 318 // deallocate data structures 319 delete resource_area(); 320 // since the handle marks are using the handle area, we have to deallocated the root 321 // handle mark before deallocating the thread's handle area, 322 assert(last_handle_mark() != NULL, "check we have an element"); 323 delete last_handle_mark(); 324 assert(last_handle_mark() == NULL, "check we have reached the end"); 325 326 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 327 // We NULL out the fields for good hygiene. 328 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ; 329 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ; 330 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ; 331 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ; 332 333 delete handle_area(); 334 335 // osthread() can be NULL, if creation of thread failed. 336 if (osthread() != NULL) os::free_thread(osthread()); 337 338 delete _SR_lock; 339 340 // clear thread local storage if the Thread is deleting itself 341 if (this == Thread::current()) { 342 ThreadLocalStorage::set_thread(NULL); 343 } else { 344 // In the case where we're not the current thread, invalidate all the 345 // caches in case some code tries to get the current thread or the 346 // thread that was destroyed, and gets stale information. 347 ThreadLocalStorage::invalidate_all(); 348 } 349 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 350 } 351 352 // NOTE: dummy function for assertion purpose. 353 void Thread::run() { 354 ShouldNotReachHere(); 355 } 356 357 #ifdef ASSERT 358 // Private method to check for dangling thread pointer 359 void check_for_dangling_thread_pointer(Thread *thread) { 360 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 361 "possibility of dangling Thread pointer"); 362 } 363 #endif 364 365 366 #ifndef PRODUCT 367 // Tracing method for basic thread operations 368 void Thread::trace(const char* msg, const Thread* const thread) { 369 if (!TraceThreadEvents) return; 370 ResourceMark rm; 371 ThreadCritical tc; 372 const char *name = "non-Java thread"; 373 int prio = -1; 374 if (thread->is_Java_thread() 375 && !thread->is_Compiler_thread()) { 376 // The Threads_lock must be held to get information about 377 // this thread but may not be in some situations when 378 // tracing thread events. 379 bool release_Threads_lock = false; 380 if (!Threads_lock->owned_by_self()) { 381 Threads_lock->lock(); 382 release_Threads_lock = true; 383 } 384 JavaThread* jt = (JavaThread *)thread; 385 name = (char *)jt->get_thread_name(); 386 oop thread_oop = jt->threadObj(); 387 if (thread_oop != NULL) { 388 prio = java_lang_Thread::priority(thread_oop); 389 } 390 if (release_Threads_lock) { 391 Threads_lock->unlock(); 392 } 393 } 394 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio); 395 } 396 #endif 397 398 399 ThreadPriority Thread::get_priority(const Thread* const thread) { 400 trace("get priority", thread); 401 ThreadPriority priority; 402 // Can return an error! 403 (void)os::get_priority(thread, priority); 404 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 405 return priority; 406 } 407 408 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 409 trace("set priority", thread); 410 debug_only(check_for_dangling_thread_pointer(thread);) 411 // Can return an error! 412 (void)os::set_priority(thread, priority); 413 } 414 415 416 void Thread::start(Thread* thread) { 417 trace("start", thread); 418 // Start is different from resume in that its safety is guaranteed by context or 419 // being called from a Java method synchronized on the Thread object. 420 if (!DisableStartThread) { 421 if (thread->is_Java_thread()) { 422 // Initialize the thread state to RUNNABLE before starting this thread. 423 // Can not set it after the thread started because we do not know the 424 // exact thread state at that time. It could be in MONITOR_WAIT or 425 // in SLEEPING or some other state. 426 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 427 java_lang_Thread::RUNNABLE); 428 } 429 os::start_thread(thread); 430 } 431 } 432 433 // Enqueue a VM_Operation to do the job for us - sometime later 434 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 435 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 436 VMThread::execute(vm_stop); 437 } 438 439 440 // 441 // Check if an external suspend request has completed (or has been 442 // cancelled). Returns true if the thread is externally suspended and 443 // false otherwise. 444 // 445 // The bits parameter returns information about the code path through 446 // the routine. Useful for debugging: 447 // 448 // set in is_ext_suspend_completed(): 449 // 0x00000001 - routine was entered 450 // 0x00000010 - routine return false at end 451 // 0x00000100 - thread exited (return false) 452 // 0x00000200 - suspend request cancelled (return false) 453 // 0x00000400 - thread suspended (return true) 454 // 0x00001000 - thread is in a suspend equivalent state (return true) 455 // 0x00002000 - thread is native and walkable (return true) 456 // 0x00004000 - thread is native_trans and walkable (needed retry) 457 // 458 // set in wait_for_ext_suspend_completion(): 459 // 0x00010000 - routine was entered 460 // 0x00020000 - suspend request cancelled before loop (return false) 461 // 0x00040000 - thread suspended before loop (return true) 462 // 0x00080000 - suspend request cancelled in loop (return false) 463 // 0x00100000 - thread suspended in loop (return true) 464 // 0x00200000 - suspend not completed during retry loop (return false) 465 // 466 467 // Helper class for tracing suspend wait debug bits. 468 // 469 // 0x00000100 indicates that the target thread exited before it could 470 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 471 // 0x00080000 each indicate a cancelled suspend request so they don't 472 // count as wait failures either. 473 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 474 475 class TraceSuspendDebugBits : public StackObj { 476 private: 477 JavaThread * jt; 478 bool is_wait; 479 bool called_by_wait; // meaningful when !is_wait 480 uint32_t * bits; 481 482 public: 483 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 484 uint32_t *_bits) { 485 jt = _jt; 486 is_wait = _is_wait; 487 called_by_wait = _called_by_wait; 488 bits = _bits; 489 } 490 491 ~TraceSuspendDebugBits() { 492 if (!is_wait) { 493 #if 1 494 // By default, don't trace bits for is_ext_suspend_completed() calls. 495 // That trace is very chatty. 496 return; 497 #else 498 if (!called_by_wait) { 499 // If tracing for is_ext_suspend_completed() is enabled, then only 500 // trace calls to it from wait_for_ext_suspend_completion() 501 return; 502 } 503 #endif 504 } 505 506 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 507 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 508 MutexLocker ml(Threads_lock); // needed for get_thread_name() 509 ResourceMark rm; 510 511 tty->print_cr( 512 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 513 jt->get_thread_name(), *bits); 514 515 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 516 } 517 } 518 } 519 }; 520 #undef DEBUG_FALSE_BITS 521 522 523 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) { 524 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 525 526 bool did_trans_retry = false; // only do thread_in_native_trans retry once 527 bool do_trans_retry; // flag to force the retry 528 529 *bits |= 0x00000001; 530 531 do { 532 do_trans_retry = false; 533 534 if (is_exiting()) { 535 // Thread is in the process of exiting. This is always checked 536 // first to reduce the risk of dereferencing a freed JavaThread. 537 *bits |= 0x00000100; 538 return false; 539 } 540 541 if (!is_external_suspend()) { 542 // Suspend request is cancelled. This is always checked before 543 // is_ext_suspended() to reduce the risk of a rogue resume 544 // confusing the thread that made the suspend request. 545 *bits |= 0x00000200; 546 return false; 547 } 548 549 if (is_ext_suspended()) { 550 // thread is suspended 551 *bits |= 0x00000400; 552 return true; 553 } 554 555 // Now that we no longer do hard suspends of threads running 556 // native code, the target thread can be changing thread state 557 // while we are in this routine: 558 // 559 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 560 // 561 // We save a copy of the thread state as observed at this moment 562 // and make our decision about suspend completeness based on the 563 // copy. This closes the race where the thread state is seen as 564 // _thread_in_native_trans in the if-thread_blocked check, but is 565 // seen as _thread_blocked in if-thread_in_native_trans check. 566 JavaThreadState save_state = thread_state(); 567 568 if (save_state == _thread_blocked && is_suspend_equivalent()) { 569 // If the thread's state is _thread_blocked and this blocking 570 // condition is known to be equivalent to a suspend, then we can 571 // consider the thread to be externally suspended. This means that 572 // the code that sets _thread_blocked has been modified to do 573 // self-suspension if the blocking condition releases. We also 574 // used to check for CONDVAR_WAIT here, but that is now covered by 575 // the _thread_blocked with self-suspension check. 576 // 577 // Return true since we wouldn't be here unless there was still an 578 // external suspend request. 579 *bits |= 0x00001000; 580 return true; 581 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 582 // Threads running native code will self-suspend on native==>VM/Java 583 // transitions. If its stack is walkable (should always be the case 584 // unless this function is called before the actual java_suspend() 585 // call), then the wait is done. 586 *bits |= 0x00002000; 587 return true; 588 } else if (!called_by_wait && !did_trans_retry && 589 save_state == _thread_in_native_trans && 590 frame_anchor()->walkable()) { 591 // The thread is transitioning from thread_in_native to another 592 // thread state. check_safepoint_and_suspend_for_native_trans() 593 // will force the thread to self-suspend. If it hasn't gotten 594 // there yet we may have caught the thread in-between the native 595 // code check above and the self-suspend. Lucky us. If we were 596 // called by wait_for_ext_suspend_completion(), then it 597 // will be doing the retries so we don't have to. 598 // 599 // Since we use the saved thread state in the if-statement above, 600 // there is a chance that the thread has already transitioned to 601 // _thread_blocked by the time we get here. In that case, we will 602 // make a single unnecessary pass through the logic below. This 603 // doesn't hurt anything since we still do the trans retry. 604 605 *bits |= 0x00004000; 606 607 // Once the thread leaves thread_in_native_trans for another 608 // thread state, we break out of this retry loop. We shouldn't 609 // need this flag to prevent us from getting back here, but 610 // sometimes paranoia is good. 611 did_trans_retry = true; 612 613 // We wait for the thread to transition to a more usable state. 614 for (int i = 1; i <= SuspendRetryCount; i++) { 615 // We used to do an "os::yield_all(i)" call here with the intention 616 // that yielding would increase on each retry. However, the parameter 617 // is ignored on Linux which means the yield didn't scale up. Waiting 618 // on the SR_lock below provides a much more predictable scale up for 619 // the delay. It also provides a simple/direct point to check for any 620 // safepoint requests from the VMThread 621 622 // temporarily drops SR_lock while doing wait with safepoint check 623 // (if we're a JavaThread - the WatcherThread can also call this) 624 // and increase delay with each retry 625 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 626 627 // check the actual thread state instead of what we saved above 628 if (thread_state() != _thread_in_native_trans) { 629 // the thread has transitioned to another thread state so 630 // try all the checks (except this one) one more time. 631 do_trans_retry = true; 632 break; 633 } 634 } // end retry loop 635 636 637 } 638 } while (do_trans_retry); 639 640 *bits |= 0x00000010; 641 return false; 642 } 643 644 // 645 // Wait for an external suspend request to complete (or be cancelled). 646 // Returns true if the thread is externally suspended and false otherwise. 647 // 648 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 649 uint32_t *bits) { 650 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 651 false /* !called_by_wait */, bits); 652 653 // local flag copies to minimize SR_lock hold time 654 bool is_suspended; 655 bool pending; 656 uint32_t reset_bits; 657 658 // set a marker so is_ext_suspend_completed() knows we are the caller 659 *bits |= 0x00010000; 660 661 // We use reset_bits to reinitialize the bits value at the top of 662 // each retry loop. This allows the caller to make use of any 663 // unused bits for their own marking purposes. 664 reset_bits = *bits; 665 666 { 667 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 668 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 669 delay, bits); 670 pending = is_external_suspend(); 671 } 672 // must release SR_lock to allow suspension to complete 673 674 if (!pending) { 675 // A cancelled suspend request is the only false return from 676 // is_ext_suspend_completed() that keeps us from entering the 677 // retry loop. 678 *bits |= 0x00020000; 679 return false; 680 } 681 682 if (is_suspended) { 683 *bits |= 0x00040000; 684 return true; 685 } 686 687 for (int i = 1; i <= retries; i++) { 688 *bits = reset_bits; // reinit to only track last retry 689 690 // We used to do an "os::yield_all(i)" call here with the intention 691 // that yielding would increase on each retry. However, the parameter 692 // is ignored on Linux which means the yield didn't scale up. Waiting 693 // on the SR_lock below provides a much more predictable scale up for 694 // the delay. It also provides a simple/direct point to check for any 695 // safepoint requests from the VMThread 696 697 { 698 MutexLocker ml(SR_lock()); 699 // wait with safepoint check (if we're a JavaThread - the WatcherThread 700 // can also call this) and increase delay with each retry 701 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 702 703 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 704 delay, bits); 705 706 // It is possible for the external suspend request to be cancelled 707 // (by a resume) before the actual suspend operation is completed. 708 // Refresh our local copy to see if we still need to wait. 709 pending = is_external_suspend(); 710 } 711 712 if (!pending) { 713 // A cancelled suspend request is the only false return from 714 // is_ext_suspend_completed() that keeps us from staying in the 715 // retry loop. 716 *bits |= 0x00080000; 717 return false; 718 } 719 720 if (is_suspended) { 721 *bits |= 0x00100000; 722 return true; 723 } 724 } // end retry loop 725 726 // thread did not suspend after all our retries 727 *bits |= 0x00200000; 728 return false; 729 } 730 731 #ifndef PRODUCT 732 void JavaThread::record_jump(address target, address instr, const char* file, int line) { 733 734 // This should not need to be atomic as the only way for simultaneous 735 // updates is via interrupts. Even then this should be rare or non-existant 736 // and we don't care that much anyway. 737 738 int index = _jmp_ring_index; 739 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1); 740 _jmp_ring[index]._target = (intptr_t) target; 741 _jmp_ring[index]._instruction = (intptr_t) instr; 742 _jmp_ring[index]._file = file; 743 _jmp_ring[index]._line = line; 744 } 745 #endif /* PRODUCT */ 746 747 // Called by flat profiler 748 // Callers have already called wait_for_ext_suspend_completion 749 // The assertion for that is currently too complex to put here: 750 bool JavaThread::profile_last_Java_frame(frame* _fr) { 751 bool gotframe = false; 752 // self suspension saves needed state. 753 if (has_last_Java_frame() && _anchor.walkable()) { 754 *_fr = pd_last_frame(); 755 gotframe = true; 756 } 757 return gotframe; 758 } 759 760 void Thread::interrupt(Thread* thread) { 761 trace("interrupt", thread); 762 debug_only(check_for_dangling_thread_pointer(thread);) 763 os::interrupt(thread); 764 } 765 766 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 767 trace("is_interrupted", thread); 768 debug_only(check_for_dangling_thread_pointer(thread);) 769 // Note: If clear_interrupted==false, this simply fetches and 770 // returns the value of the field osthread()->interrupted(). 771 return os::is_interrupted(thread, clear_interrupted); 772 } 773 774 775 // GC Support 776 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 777 jint thread_parity = _oops_do_parity; 778 if (thread_parity != strong_roots_parity) { 779 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 780 if (res == thread_parity) { 781 return true; 782 } else { 783 guarantee(res == strong_roots_parity, "Or else what?"); 784 assert(SharedHeap::heap()->workers()->active_workers() > 0, 785 "Should only fail when parallel."); 786 return false; 787 } 788 } 789 assert(SharedHeap::heap()->workers()->active_workers() > 0, 790 "Should only fail when parallel."); 791 return false; 792 } 793 794 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 795 active_handles()->oops_do(f); 796 // Do oop for ThreadShadow 797 f->do_oop((oop*)&_pending_exception); 798 handle_area()->oops_do(f); 799 } 800 801 void Thread::nmethods_do(CodeBlobClosure* cf) { 802 // no nmethods in a generic thread... 803 } 804 805 void Thread::print_on(outputStream* st) const { 806 // get_priority assumes osthread initialized 807 if (osthread() != NULL) { 808 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this); 809 osthread()->print_on(st); 810 } 811 debug_only(if (WizardMode) print_owned_locks_on(st);) 812 } 813 814 // Thread::print_on_error() is called by fatal error handler. Don't use 815 // any lock or allocate memory. 816 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 817 if (is_VM_thread()) st->print("VMThread"); 818 else if (is_Compiler_thread()) st->print("CompilerThread"); 819 else if (is_Java_thread()) st->print("JavaThread"); 820 else if (is_GC_task_thread()) st->print("GCTaskThread"); 821 else if (is_Watcher_thread()) st->print("WatcherThread"); 822 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 823 else st->print("Thread"); 824 825 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 826 _stack_base - _stack_size, _stack_base); 827 828 if (osthread()) { 829 st->print(" [id=%d]", osthread()->thread_id()); 830 } 831 } 832 833 #ifdef ASSERT 834 void Thread::print_owned_locks_on(outputStream* st) const { 835 Monitor *cur = _owned_locks; 836 if (cur == NULL) { 837 st->print(" (no locks) "); 838 } else { 839 st->print_cr(" Locks owned:"); 840 while(cur) { 841 cur->print_on(st); 842 cur = cur->next(); 843 } 844 } 845 } 846 847 static int ref_use_count = 0; 848 849 bool Thread::owns_locks_but_compiled_lock() const { 850 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { 851 if (cur != Compile_lock) return true; 852 } 853 return false; 854 } 855 856 857 #endif 858 859 #ifndef PRODUCT 860 861 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 862 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 863 // no threads which allow_vm_block's are held 864 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 865 // Check if current thread is allowed to block at a safepoint 866 if (!(_allow_safepoint_count == 0)) 867 fatal("Possible safepoint reached by thread that does not allow it"); 868 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 869 fatal("LEAF method calling lock?"); 870 } 871 872 #ifdef ASSERT 873 if (potential_vm_operation && is_Java_thread() 874 && !Universe::is_bootstrapping()) { 875 // Make sure we do not hold any locks that the VM thread also uses. 876 // This could potentially lead to deadlocks 877 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { 878 // Threads_lock is special, since the safepoint synchronization will not start before this is 879 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 880 // since it is used to transfer control between JavaThreads and the VMThread 881 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first! 882 if ( (cur->allow_vm_block() && 883 cur != Threads_lock && 884 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation 885 cur != VMOperationRequest_lock && 886 cur != VMOperationQueue_lock) || 887 cur->rank() == Mutex::special) { 888 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 889 } 890 } 891 } 892 893 if (GCALotAtAllSafepoints) { 894 // We could enter a safepoint here and thus have a gc 895 InterfaceSupport::check_gc_alot(); 896 } 897 #endif 898 } 899 #endif 900 901 bool Thread::is_in_stack(address adr) const { 902 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 903 address end = os::current_stack_pointer(); 904 if (stack_base() >= adr && adr >= end) return true; 905 906 return false; 907 } 908 909 910 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 911 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 912 // used for compilation in the future. If that change is made, the need for these methods 913 // should be revisited, and they should be removed if possible. 914 915 bool Thread::is_lock_owned(address adr) const { 916 return on_local_stack(adr); 917 } 918 919 bool Thread::set_as_starting_thread() { 920 // NOTE: this must be called inside the main thread. 921 return os::create_main_thread((JavaThread*)this); 922 } 923 924 static void initialize_class(Symbol* class_name, TRAPS) { 925 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 926 instanceKlass::cast(klass)->initialize(CHECK); 927 } 928 929 930 // Creates the initial ThreadGroup 931 static Handle create_initial_thread_group(TRAPS) { 932 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 933 instanceKlassHandle klass (THREAD, k); 934 935 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 936 { 937 JavaValue result(T_VOID); 938 JavaCalls::call_special(&result, 939 system_instance, 940 klass, 941 vmSymbols::object_initializer_name(), 942 vmSymbols::void_method_signature(), 943 CHECK_NH); 944 } 945 Universe::set_system_thread_group(system_instance()); 946 947 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 948 { 949 JavaValue result(T_VOID); 950 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 951 JavaCalls::call_special(&result, 952 main_instance, 953 klass, 954 vmSymbols::object_initializer_name(), 955 vmSymbols::threadgroup_string_void_signature(), 956 system_instance, 957 string, 958 CHECK_NH); 959 } 960 return main_instance; 961 } 962 963 // Creates the initial Thread 964 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) { 965 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 966 instanceKlassHandle klass (THREAD, k); 967 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 968 969 java_lang_Thread::set_thread(thread_oop(), thread); 970 java_lang_Thread::set_priority(thread_oop(), NormPriority); 971 thread->set_threadObj(thread_oop()); 972 973 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 974 975 JavaValue result(T_VOID); 976 JavaCalls::call_special(&result, thread_oop, 977 klass, 978 vmSymbols::object_initializer_name(), 979 vmSymbols::threadgroup_string_void_signature(), 980 thread_group, 981 string, 982 CHECK_NULL); 983 return thread_oop(); 984 } 985 986 static void call_initializeSystemClass(TRAPS) { 987 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 988 instanceKlassHandle klass (THREAD, k); 989 990 JavaValue result(T_VOID); 991 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), 992 vmSymbols::void_method_signature(), CHECK); 993 } 994 995 // General purpose hook into Java code, run once when the VM is initialized. 996 // The Java library method itself may be changed independently from the VM. 997 static void call_postVMInitHook(TRAPS) { 998 klassOop k = SystemDictionary::PostVMInitHook_klass(); 999 instanceKlassHandle klass (THREAD, k); 1000 if (klass.not_null()) { 1001 JavaValue result(T_VOID); 1002 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1003 vmSymbols::void_method_signature(), 1004 CHECK); 1005 } 1006 } 1007 1008 static void reset_vm_info_property(TRAPS) { 1009 // the vm info string 1010 ResourceMark rm(THREAD); 1011 const char *vm_info = VM_Version::vm_info_string(); 1012 1013 // java.lang.System class 1014 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1015 instanceKlassHandle klass (THREAD, k); 1016 1017 // setProperty arguments 1018 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1019 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1020 1021 // return value 1022 JavaValue r(T_OBJECT); 1023 1024 // public static String setProperty(String key, String value); 1025 JavaCalls::call_static(&r, 1026 klass, 1027 vmSymbols::setProperty_name(), 1028 vmSymbols::string_string_string_signature(), 1029 key_str, 1030 value_str, 1031 CHECK); 1032 } 1033 1034 1035 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) { 1036 assert(thread_group.not_null(), "thread group should be specified"); 1037 assert(threadObj() == NULL, "should only create Java thread object once"); 1038 1039 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1040 instanceKlassHandle klass (THREAD, k); 1041 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1042 1043 java_lang_Thread::set_thread(thread_oop(), this); 1044 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1045 set_threadObj(thread_oop()); 1046 1047 JavaValue result(T_VOID); 1048 if (thread_name != NULL) { 1049 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1050 // Thread gets assigned specified name and null target 1051 JavaCalls::call_special(&result, 1052 thread_oop, 1053 klass, 1054 vmSymbols::object_initializer_name(), 1055 vmSymbols::threadgroup_string_void_signature(), 1056 thread_group, // Argument 1 1057 name, // Argument 2 1058 THREAD); 1059 } else { 1060 // Thread gets assigned name "Thread-nnn" and null target 1061 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1062 JavaCalls::call_special(&result, 1063 thread_oop, 1064 klass, 1065 vmSymbols::object_initializer_name(), 1066 vmSymbols::threadgroup_runnable_void_signature(), 1067 thread_group, // Argument 1 1068 Handle(), // Argument 2 1069 THREAD); 1070 } 1071 1072 1073 if (daemon) { 1074 java_lang_Thread::set_daemon(thread_oop()); 1075 } 1076 1077 if (HAS_PENDING_EXCEPTION) { 1078 return; 1079 } 1080 1081 KlassHandle group(this, SystemDictionary::ThreadGroup_klass()); 1082 Handle threadObj(this, this->threadObj()); 1083 1084 JavaCalls::call_special(&result, 1085 thread_group, 1086 group, 1087 vmSymbols::add_method_name(), 1088 vmSymbols::thread_void_signature(), 1089 threadObj, // Arg 1 1090 THREAD); 1091 1092 1093 } 1094 1095 // NamedThread -- non-JavaThread subclasses with multiple 1096 // uniquely named instances should derive from this. 1097 NamedThread::NamedThread() : Thread() { 1098 _name = NULL; 1099 _processed_thread = NULL; 1100 } 1101 1102 NamedThread::~NamedThread() { 1103 if (_name != NULL) { 1104 FREE_C_HEAP_ARRAY(char, _name); 1105 _name = NULL; 1106 } 1107 } 1108 1109 void NamedThread::set_name(const char* format, ...) { 1110 guarantee(_name == NULL, "Only get to set name once."); 1111 _name = NEW_C_HEAP_ARRAY(char, max_name_len); 1112 guarantee(_name != NULL, "alloc failure"); 1113 va_list ap; 1114 va_start(ap, format); 1115 jio_vsnprintf(_name, max_name_len, format, ap); 1116 va_end(ap); 1117 } 1118 1119 // ======= WatcherThread ======== 1120 1121 // The watcher thread exists to simulate timer interrupts. It should 1122 // be replaced by an abstraction over whatever native support for 1123 // timer interrupts exists on the platform. 1124 1125 WatcherThread* WatcherThread::_watcher_thread = NULL; 1126 volatile bool WatcherThread::_should_terminate = false; 1127 1128 WatcherThread::WatcherThread() : Thread() { 1129 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1130 if (os::create_thread(this, os::watcher_thread)) { 1131 _watcher_thread = this; 1132 1133 // Set the watcher thread to the highest OS priority which should not be 1134 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1135 // is created. The only normal thread using this priority is the reference 1136 // handler thread, which runs for very short intervals only. 1137 // If the VMThread's priority is not lower than the WatcherThread profiling 1138 // will be inaccurate. 1139 os::set_priority(this, MaxPriority); 1140 if (!DisableStartThread) { 1141 os::start_thread(this); 1142 } 1143 } 1144 } 1145 1146 void WatcherThread::run() { 1147 assert(this == watcher_thread(), "just checking"); 1148 1149 this->record_stack_base_and_size(); 1150 this->initialize_thread_local_storage(); 1151 this->set_active_handles(JNIHandleBlock::allocate_block()); 1152 while(!_should_terminate) { 1153 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1154 assert(watcher_thread() == this, "thread consistency check"); 1155 1156 // Calculate how long it'll be until the next PeriodicTask work 1157 // should be done, and sleep that amount of time. 1158 size_t time_to_wait = PeriodicTask::time_to_wait(); 1159 1160 // we expect this to timeout - we only ever get unparked when 1161 // we should terminate 1162 { 1163 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1164 1165 jlong prev_time = os::javaTimeNanos(); 1166 for (;;) { 1167 int res= _SleepEvent->park(time_to_wait); 1168 if (res == OS_TIMEOUT || _should_terminate) 1169 break; 1170 // spurious wakeup of some kind 1171 jlong now = os::javaTimeNanos(); 1172 time_to_wait -= (now - prev_time) / 1000000; 1173 if (time_to_wait <= 0) 1174 break; 1175 prev_time = now; 1176 } 1177 } 1178 1179 if (is_error_reported()) { 1180 // A fatal error has happened, the error handler(VMError::report_and_die) 1181 // should abort JVM after creating an error log file. However in some 1182 // rare cases, the error handler itself might deadlock. Here we try to 1183 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1184 // 1185 // This code is in WatcherThread because WatcherThread wakes up 1186 // periodically so the fatal error handler doesn't need to do anything; 1187 // also because the WatcherThread is less likely to crash than other 1188 // threads. 1189 1190 for (;;) { 1191 if (!ShowMessageBoxOnError 1192 && (OnError == NULL || OnError[0] == '\0') 1193 && Arguments::abort_hook() == NULL) { 1194 os::sleep(this, 2 * 60 * 1000, false); 1195 fdStream err(defaultStream::output_fd()); 1196 err.print_raw_cr("# [ timer expired, abort... ]"); 1197 // skip atexit/vm_exit/vm_abort hooks 1198 os::die(); 1199 } 1200 1201 // Wake up 5 seconds later, the fatal handler may reset OnError or 1202 // ShowMessageBoxOnError when it is ready to abort. 1203 os::sleep(this, 5 * 1000, false); 1204 } 1205 } 1206 1207 PeriodicTask::real_time_tick(time_to_wait); 1208 1209 // If we have no more tasks left due to dynamic disenrollment, 1210 // shut down the thread since we don't currently support dynamic enrollment 1211 if (PeriodicTask::num_tasks() == 0) { 1212 _should_terminate = true; 1213 } 1214 } 1215 1216 // Signal that it is terminated 1217 { 1218 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1219 _watcher_thread = NULL; 1220 Terminator_lock->notify(); 1221 } 1222 1223 // Thread destructor usually does this.. 1224 ThreadLocalStorage::set_thread(NULL); 1225 } 1226 1227 void WatcherThread::start() { 1228 if (watcher_thread() == NULL) { 1229 _should_terminate = false; 1230 // Create the single instance of WatcherThread 1231 new WatcherThread(); 1232 } 1233 } 1234 1235 void WatcherThread::stop() { 1236 // it is ok to take late safepoints here, if needed 1237 MutexLocker mu(Terminator_lock); 1238 _should_terminate = true; 1239 OrderAccess::fence(); // ensure WatcherThread sees update in main loop 1240 1241 Thread* watcher = watcher_thread(); 1242 if (watcher != NULL) 1243 watcher->_SleepEvent->unpark(); 1244 1245 while(watcher_thread() != NULL) { 1246 // This wait should make safepoint checks, wait without a timeout, 1247 // and wait as a suspend-equivalent condition. 1248 // 1249 // Note: If the FlatProfiler is running, then this thread is waiting 1250 // for the WatcherThread to terminate and the WatcherThread, via the 1251 // FlatProfiler task, is waiting for the external suspend request on 1252 // this thread to complete. wait_for_ext_suspend_completion() will 1253 // eventually timeout, but that takes time. Making this wait a 1254 // suspend-equivalent condition solves that timeout problem. 1255 // 1256 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1257 Mutex::_as_suspend_equivalent_flag); 1258 } 1259 } 1260 1261 void WatcherThread::print_on(outputStream* st) const { 1262 st->print("\"%s\" ", name()); 1263 Thread::print_on(st); 1264 st->cr(); 1265 } 1266 1267 // ======= JavaThread ======== 1268 1269 // A JavaThread is a normal Java thread 1270 1271 void JavaThread::initialize() { 1272 // Initialize fields 1273 1274 // Set the claimed par_id to -1 (ie not claiming any par_ids) 1275 set_claimed_par_id(-1); 1276 1277 set_saved_exception_pc(NULL); 1278 set_threadObj(NULL); 1279 _anchor.clear(); 1280 set_entry_point(NULL); 1281 set_jni_functions(jni_functions()); 1282 set_callee_target(NULL); 1283 set_vm_result(NULL); 1284 set_vm_result_2(NULL); 1285 set_vframe_array_head(NULL); 1286 set_vframe_array_last(NULL); 1287 set_deferred_locals(NULL); 1288 set_deopt_mark(NULL); 1289 set_deopt_nmethod(NULL); 1290 clear_must_deopt_id(); 1291 set_monitor_chunks(NULL); 1292 set_next(NULL); 1293 set_thread_state(_thread_new); 1294 _terminated = _not_terminated; 1295 _privileged_stack_top = NULL; 1296 _array_for_gc = NULL; 1297 _suspend_equivalent = false; 1298 _in_deopt_handler = 0; 1299 _doing_unsafe_access = false; 1300 _stack_guard_state = stack_guard_unused; 1301 _exception_oop = NULL; 1302 _exception_pc = 0; 1303 _exception_handler_pc = 0; 1304 _is_method_handle_return = 0; 1305 _jvmti_thread_state= NULL; 1306 _should_post_on_exceptions_flag = JNI_FALSE; 1307 _jvmti_get_loaded_classes_closure = NULL; 1308 _interp_only_mode = 0; 1309 _special_runtime_exit_condition = _no_async_condition; 1310 _pending_async_exception = NULL; 1311 _is_compiling = false; 1312 _thread_stat = NULL; 1313 _thread_stat = new ThreadStatistics(); 1314 _blocked_on_compilation = false; 1315 _jni_active_critical = 0; 1316 _do_not_unlock_if_synchronized = false; 1317 _cached_monitor_info = NULL; 1318 _parker = Parker::Allocate(this) ; 1319 1320 #ifndef PRODUCT 1321 _jmp_ring_index = 0; 1322 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) { 1323 record_jump(NULL, NULL, NULL, 0); 1324 } 1325 #endif /* PRODUCT */ 1326 1327 set_thread_profiler(NULL); 1328 if (FlatProfiler::is_active()) { 1329 // This is where we would decide to either give each thread it's own profiler 1330 // or use one global one from FlatProfiler, 1331 // or up to some count of the number of profiled threads, etc. 1332 ThreadProfiler* pp = new ThreadProfiler(); 1333 pp->engage(); 1334 set_thread_profiler(pp); 1335 } 1336 1337 // Setup safepoint state info for this thread 1338 ThreadSafepointState::create(this); 1339 1340 debug_only(_java_call_counter = 0); 1341 1342 // JVMTI PopFrame support 1343 _popframe_condition = popframe_inactive; 1344 _popframe_preserved_args = NULL; 1345 _popframe_preserved_args_size = 0; 1346 1347 pd_initialize(); 1348 } 1349 1350 #ifndef SERIALGC 1351 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1352 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1353 #endif // !SERIALGC 1354 1355 JavaThread::JavaThread(bool is_attaching_via_jni) : 1356 Thread() 1357 #ifndef SERIALGC 1358 , _satb_mark_queue(&_satb_mark_queue_set), 1359 _dirty_card_queue(&_dirty_card_queue_set) 1360 #endif // !SERIALGC 1361 { 1362 initialize(); 1363 if (is_attaching_via_jni) { 1364 _jni_attach_state = _attaching_via_jni; 1365 } else { 1366 _jni_attach_state = _not_attaching_via_jni; 1367 } 1368 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor"); 1369 } 1370 1371 bool JavaThread::reguard_stack(address cur_sp) { 1372 if (_stack_guard_state != stack_guard_yellow_disabled) { 1373 return true; // Stack already guarded or guard pages not needed. 1374 } 1375 1376 if (register_stack_overflow()) { 1377 // For those architectures which have separate register and 1378 // memory stacks, we must check the register stack to see if 1379 // it has overflowed. 1380 return false; 1381 } 1382 1383 // Java code never executes within the yellow zone: the latter is only 1384 // there to provoke an exception during stack banging. If java code 1385 // is executing there, either StackShadowPages should be larger, or 1386 // some exception code in c1, c2 or the interpreter isn't unwinding 1387 // when it should. 1388 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); 1389 1390 enable_stack_yellow_zone(); 1391 return true; 1392 } 1393 1394 bool JavaThread::reguard_stack(void) { 1395 return reguard_stack(os::current_stack_pointer()); 1396 } 1397 1398 1399 void JavaThread::block_if_vm_exited() { 1400 if (_terminated == _vm_exited) { 1401 // _vm_exited is set at safepoint, and Threads_lock is never released 1402 // we will block here forever 1403 Threads_lock->lock_without_safepoint_check(); 1404 ShouldNotReachHere(); 1405 } 1406 } 1407 1408 1409 // Remove this ifdef when C1 is ported to the compiler interface. 1410 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1411 1412 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1413 Thread() 1414 #ifndef SERIALGC 1415 , _satb_mark_queue(&_satb_mark_queue_set), 1416 _dirty_card_queue(&_dirty_card_queue_set) 1417 #endif // !SERIALGC 1418 { 1419 if (TraceThreadEvents) { 1420 tty->print_cr("creating thread %p", this); 1421 } 1422 initialize(); 1423 _jni_attach_state = _not_attaching_via_jni; 1424 set_entry_point(entry_point); 1425 // Create the native thread itself. 1426 // %note runtime_23 1427 os::ThreadType thr_type = os::java_thread; 1428 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1429 os::java_thread; 1430 os::create_thread(this, thr_type, stack_sz); 1431 1432 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1433 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1434 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1435 // the exception consists of creating the exception object & initializing it, initialization 1436 // will leave the VM via a JavaCall and then all locks must be unlocked). 1437 // 1438 // The thread is still suspended when we reach here. Thread must be explicit started 1439 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1440 // by calling Threads:add. The reason why this is not done here, is because the thread 1441 // object must be fully initialized (take a look at JVM_Start) 1442 } 1443 1444 JavaThread::~JavaThread() { 1445 if (TraceThreadEvents) { 1446 tty->print_cr("terminate thread %p", this); 1447 } 1448 1449 // JSR166 -- return the parker to the free list 1450 Parker::Release(_parker); 1451 _parker = NULL ; 1452 1453 // Free any remaining previous UnrollBlock 1454 vframeArray* old_array = vframe_array_last(); 1455 1456 if (old_array != NULL) { 1457 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1458 old_array->set_unroll_block(NULL); 1459 delete old_info; 1460 delete old_array; 1461 } 1462 1463 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1464 if (deferred != NULL) { 1465 // This can only happen if thread is destroyed before deoptimization occurs. 1466 assert(deferred->length() != 0, "empty array!"); 1467 do { 1468 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1469 deferred->remove_at(0); 1470 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1471 delete dlv; 1472 } while (deferred->length() != 0); 1473 delete deferred; 1474 } 1475 1476 // All Java related clean up happens in exit 1477 ThreadSafepointState::destroy(this); 1478 if (_thread_profiler != NULL) delete _thread_profiler; 1479 if (_thread_stat != NULL) delete _thread_stat; 1480 } 1481 1482 1483 // The first routine called by a new Java thread 1484 void JavaThread::run() { 1485 // initialize thread-local alloc buffer related fields 1486 this->initialize_tlab(); 1487 1488 // used to test validitity of stack trace backs 1489 this->record_base_of_stack_pointer(); 1490 1491 // Record real stack base and size. 1492 this->record_stack_base_and_size(); 1493 1494 // Initialize thread local storage; set before calling MutexLocker 1495 this->initialize_thread_local_storage(); 1496 1497 this->create_stack_guard_pages(); 1498 1499 this->cache_global_variables(); 1500 1501 // Thread is now sufficient initialized to be handled by the safepoint code as being 1502 // in the VM. Change thread state from _thread_new to _thread_in_vm 1503 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1504 1505 assert(JavaThread::current() == this, "sanity check"); 1506 assert(!Thread::current()->owns_locks(), "sanity check"); 1507 1508 DTRACE_THREAD_PROBE(start, this); 1509 1510 // This operation might block. We call that after all safepoint checks for a new thread has 1511 // been completed. 1512 this->set_active_handles(JNIHandleBlock::allocate_block()); 1513 1514 if (JvmtiExport::should_post_thread_life()) { 1515 JvmtiExport::post_thread_start(this); 1516 } 1517 1518 EVENT_BEGIN(TraceEventThreadStart, event); 1519 EVENT_COMMIT(event, 1520 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj()))); 1521 1522 // We call another function to do the rest so we are sure that the stack addresses used 1523 // from there will be lower than the stack base just computed 1524 thread_main_inner(); 1525 1526 // Note, thread is no longer valid at this point! 1527 } 1528 1529 1530 void JavaThread::thread_main_inner() { 1531 assert(JavaThread::current() == this, "sanity check"); 1532 assert(this->threadObj() != NULL, "just checking"); 1533 1534 // Execute thread entry point unless this thread has a pending exception 1535 // or has been stopped before starting. 1536 // Note: Due to JVM_StopThread we can have pending exceptions already! 1537 if (!this->has_pending_exception() && 1538 !java_lang_Thread::is_stillborn(this->threadObj())) { 1539 { 1540 ResourceMark rm(this); 1541 this->set_native_thread_name(this->get_thread_name()); 1542 } 1543 HandleMark hm(this); 1544 this->entry_point()(this, this); 1545 } 1546 1547 DTRACE_THREAD_PROBE(stop, this); 1548 1549 this->exit(false); 1550 delete this; 1551 } 1552 1553 1554 static void ensure_join(JavaThread* thread) { 1555 // We do not need to grap the Threads_lock, since we are operating on ourself. 1556 Handle threadObj(thread, thread->threadObj()); 1557 assert(threadObj.not_null(), "java thread object must exist"); 1558 ObjectLocker lock(threadObj, thread); 1559 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1560 thread->clear_pending_exception(); 1561 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1562 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1563 // Clear the native thread instance - this makes isAlive return false and allows the join() 1564 // to complete once we've done the notify_all below 1565 java_lang_Thread::set_thread(threadObj(), NULL); 1566 lock.notify_all(thread); 1567 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1568 thread->clear_pending_exception(); 1569 } 1570 1571 1572 // For any new cleanup additions, please check to see if they need to be applied to 1573 // cleanup_failed_attach_current_thread as well. 1574 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1575 assert(this == JavaThread::current(), "thread consistency check"); 1576 if (!InitializeJavaLangSystem) return; 1577 1578 HandleMark hm(this); 1579 Handle uncaught_exception(this, this->pending_exception()); 1580 this->clear_pending_exception(); 1581 Handle threadObj(this, this->threadObj()); 1582 assert(threadObj.not_null(), "Java thread object should be created"); 1583 1584 if (get_thread_profiler() != NULL) { 1585 get_thread_profiler()->disengage(); 1586 ResourceMark rm; 1587 get_thread_profiler()->print(get_thread_name()); 1588 } 1589 1590 1591 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1592 { 1593 EXCEPTION_MARK; 1594 1595 CLEAR_PENDING_EXCEPTION; 1596 } 1597 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This 1598 // has to be fixed by a runtime query method 1599 if (!destroy_vm || JDK_Version::is_jdk12x_version()) { 1600 // JSR-166: change call from from ThreadGroup.uncaughtException to 1601 // java.lang.Thread.dispatchUncaughtException 1602 if (uncaught_exception.not_null()) { 1603 Handle group(this, java_lang_Thread::threadGroup(threadObj())); 1604 { 1605 EXCEPTION_MARK; 1606 // Check if the method Thread.dispatchUncaughtException() exists. If so 1607 // call it. Otherwise we have an older library without the JSR-166 changes, 1608 // so call ThreadGroup.uncaughtException() 1609 KlassHandle recvrKlass(THREAD, threadObj->klass()); 1610 CallInfo callinfo; 1611 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1612 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass, 1613 vmSymbols::dispatchUncaughtException_name(), 1614 vmSymbols::throwable_void_signature(), 1615 KlassHandle(), false, false, THREAD); 1616 CLEAR_PENDING_EXCEPTION; 1617 methodHandle method = callinfo.selected_method(); 1618 if (method.not_null()) { 1619 JavaValue result(T_VOID); 1620 JavaCalls::call_virtual(&result, 1621 threadObj, thread_klass, 1622 vmSymbols::dispatchUncaughtException_name(), 1623 vmSymbols::throwable_void_signature(), 1624 uncaught_exception, 1625 THREAD); 1626 } else { 1627 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass()); 1628 JavaValue result(T_VOID); 1629 JavaCalls::call_virtual(&result, 1630 group, thread_group, 1631 vmSymbols::uncaughtException_name(), 1632 vmSymbols::thread_throwable_void_signature(), 1633 threadObj, // Arg 1 1634 uncaught_exception, // Arg 2 1635 THREAD); 1636 } 1637 if (HAS_PENDING_EXCEPTION) { 1638 ResourceMark rm(this); 1639 jio_fprintf(defaultStream::error_stream(), 1640 "\nException: %s thrown from the UncaughtExceptionHandler" 1641 " in thread \"%s\"\n", 1642 Klass::cast(pending_exception()->klass())->external_name(), 1643 get_thread_name()); 1644 CLEAR_PENDING_EXCEPTION; 1645 } 1646 } 1647 } 1648 1649 // Called before the java thread exit since we want to read info 1650 // from java_lang_Thread object 1651 EVENT_BEGIN(TraceEventThreadEnd, event); 1652 EVENT_COMMIT(event, 1653 EVENT_SET(event, javalangthread, java_lang_Thread::thread_id(this->threadObj()))); 1654 1655 // Call after last event on thread 1656 EVENT_THREAD_EXIT(this); 1657 1658 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1659 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1660 // is deprecated anyhow. 1661 { int count = 3; 1662 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1663 EXCEPTION_MARK; 1664 JavaValue result(T_VOID); 1665 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1666 JavaCalls::call_virtual(&result, 1667 threadObj, thread_klass, 1668 vmSymbols::exit_method_name(), 1669 vmSymbols::void_method_signature(), 1670 THREAD); 1671 CLEAR_PENDING_EXCEPTION; 1672 } 1673 } 1674 1675 // notify JVMTI 1676 if (JvmtiExport::should_post_thread_life()) { 1677 JvmtiExport::post_thread_end(this); 1678 } 1679 1680 // We have notified the agents that we are exiting, before we go on, 1681 // we must check for a pending external suspend request and honor it 1682 // in order to not surprise the thread that made the suspend request. 1683 while (true) { 1684 { 1685 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1686 if (!is_external_suspend()) { 1687 set_terminated(_thread_exiting); 1688 ThreadService::current_thread_exiting(this); 1689 break; 1690 } 1691 // Implied else: 1692 // Things get a little tricky here. We have a pending external 1693 // suspend request, but we are holding the SR_lock so we 1694 // can't just self-suspend. So we temporarily drop the lock 1695 // and then self-suspend. 1696 } 1697 1698 ThreadBlockInVM tbivm(this); 1699 java_suspend_self(); 1700 1701 // We're done with this suspend request, but we have to loop around 1702 // and check again. Eventually we will get SR_lock without a pending 1703 // external suspend request and will be able to mark ourselves as 1704 // exiting. 1705 } 1706 // no more external suspends are allowed at this point 1707 } else { 1708 // before_exit() has already posted JVMTI THREAD_END events 1709 } 1710 1711 // Notify waiters on thread object. This has to be done after exit() is called 1712 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1713 // group should have the destroyed bit set before waiters are notified). 1714 ensure_join(this); 1715 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1716 1717 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1718 // held by this thread must be released. A detach operation must only 1719 // get here if there are no Java frames on the stack. Therefore, any 1720 // owned monitors at this point MUST be JNI-acquired monitors which are 1721 // pre-inflated and in the monitor cache. 1722 // 1723 // ensure_join() ignores IllegalThreadStateExceptions, and so does this. 1724 if (exit_type == jni_detach && JNIDetachReleasesMonitors) { 1725 assert(!this->has_last_Java_frame(), "detaching with Java frames?"); 1726 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1727 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1728 } 1729 1730 // These things needs to be done while we are still a Java Thread. Make sure that thread 1731 // is in a consistent state, in case GC happens 1732 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1733 1734 if (active_handles() != NULL) { 1735 JNIHandleBlock* block = active_handles(); 1736 set_active_handles(NULL); 1737 JNIHandleBlock::release_block(block); 1738 } 1739 1740 if (free_handle_block() != NULL) { 1741 JNIHandleBlock* block = free_handle_block(); 1742 set_free_handle_block(NULL); 1743 JNIHandleBlock::release_block(block); 1744 } 1745 1746 // These have to be removed while this is still a valid thread. 1747 remove_stack_guard_pages(); 1748 1749 if (UseTLAB) { 1750 tlab().make_parsable(true); // retire TLAB 1751 } 1752 1753 if (JvmtiEnv::environments_might_exist()) { 1754 JvmtiExport::cleanup_thread(this); 1755 } 1756 1757 #ifndef SERIALGC 1758 // We must flush G1-related buffers before removing a thread from 1759 // the list of active threads. 1760 if (UseG1GC) { 1761 flush_barrier_queues(); 1762 } 1763 #endif 1764 1765 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1766 Threads::remove(this); 1767 } 1768 1769 #ifndef SERIALGC 1770 // Flush G1-related queues. 1771 void JavaThread::flush_barrier_queues() { 1772 satb_mark_queue().flush(); 1773 dirty_card_queue().flush(); 1774 } 1775 1776 void JavaThread::initialize_queues() { 1777 assert(!SafepointSynchronize::is_at_safepoint(), 1778 "we should not be at a safepoint"); 1779 1780 ObjPtrQueue& satb_queue = satb_mark_queue(); 1781 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1782 // The SATB queue should have been constructed with its active 1783 // field set to false. 1784 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1785 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1786 // If we are creating the thread during a marking cycle, we should 1787 // set the active field of the SATB queue to true. 1788 if (satb_queue_set.is_active()) { 1789 satb_queue.set_active(true); 1790 } 1791 1792 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1793 // The dirty card queue should have been constructed with its 1794 // active field set to true. 1795 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1796 } 1797 #endif // !SERIALGC 1798 1799 void JavaThread::cleanup_failed_attach_current_thread() { 1800 if (get_thread_profiler() != NULL) { 1801 get_thread_profiler()->disengage(); 1802 ResourceMark rm; 1803 get_thread_profiler()->print(get_thread_name()); 1804 } 1805 1806 if (active_handles() != NULL) { 1807 JNIHandleBlock* block = active_handles(); 1808 set_active_handles(NULL); 1809 JNIHandleBlock::release_block(block); 1810 } 1811 1812 if (free_handle_block() != NULL) { 1813 JNIHandleBlock* block = free_handle_block(); 1814 set_free_handle_block(NULL); 1815 JNIHandleBlock::release_block(block); 1816 } 1817 1818 // These have to be removed while this is still a valid thread. 1819 remove_stack_guard_pages(); 1820 1821 if (UseTLAB) { 1822 tlab().make_parsable(true); // retire TLAB, if any 1823 } 1824 1825 #ifndef SERIALGC 1826 if (UseG1GC) { 1827 flush_barrier_queues(); 1828 } 1829 #endif 1830 1831 Threads::remove(this); 1832 delete this; 1833 } 1834 1835 1836 1837 1838 JavaThread* JavaThread::active() { 1839 Thread* thread = ThreadLocalStorage::thread(); 1840 assert(thread != NULL, "just checking"); 1841 if (thread->is_Java_thread()) { 1842 return (JavaThread*) thread; 1843 } else { 1844 assert(thread->is_VM_thread(), "this must be a vm thread"); 1845 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1846 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1847 assert(ret->is_Java_thread(), "must be a Java thread"); 1848 return ret; 1849 } 1850 } 1851 1852 bool JavaThread::is_lock_owned(address adr) const { 1853 if (Thread::is_lock_owned(adr)) return true; 1854 1855 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1856 if (chunk->contains(adr)) return true; 1857 } 1858 1859 return false; 1860 } 1861 1862 1863 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 1864 chunk->set_next(monitor_chunks()); 1865 set_monitor_chunks(chunk); 1866 } 1867 1868 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 1869 guarantee(monitor_chunks() != NULL, "must be non empty"); 1870 if (monitor_chunks() == chunk) { 1871 set_monitor_chunks(chunk->next()); 1872 } else { 1873 MonitorChunk* prev = monitor_chunks(); 1874 while (prev->next() != chunk) prev = prev->next(); 1875 prev->set_next(chunk->next()); 1876 } 1877 } 1878 1879 // JVM support. 1880 1881 // Note: this function shouldn't block if it's called in 1882 // _thread_in_native_trans state (such as from 1883 // check_special_condition_for_native_trans()). 1884 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 1885 1886 if (has_last_Java_frame() && has_async_condition()) { 1887 // If we are at a polling page safepoint (not a poll return) 1888 // then we must defer async exception because live registers 1889 // will be clobbered by the exception path. Poll return is 1890 // ok because the call we a returning from already collides 1891 // with exception handling registers and so there is no issue. 1892 // (The exception handling path kills call result registers but 1893 // this is ok since the exception kills the result anyway). 1894 1895 if (is_at_poll_safepoint()) { 1896 // if the code we are returning to has deoptimized we must defer 1897 // the exception otherwise live registers get clobbered on the 1898 // exception path before deoptimization is able to retrieve them. 1899 // 1900 RegisterMap map(this, false); 1901 frame caller_fr = last_frame().sender(&map); 1902 assert(caller_fr.is_compiled_frame(), "what?"); 1903 if (caller_fr.is_deoptimized_frame()) { 1904 if (TraceExceptions) { 1905 ResourceMark rm; 1906 tty->print_cr("deferred async exception at compiled safepoint"); 1907 } 1908 return; 1909 } 1910 } 1911 } 1912 1913 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 1914 if (condition == _no_async_condition) { 1915 // Conditions have changed since has_special_runtime_exit_condition() 1916 // was called: 1917 // - if we were here only because of an external suspend request, 1918 // then that was taken care of above (or cancelled) so we are done 1919 // - if we were here because of another async request, then it has 1920 // been cleared between the has_special_runtime_exit_condition() 1921 // and now so again we are done 1922 return; 1923 } 1924 1925 // Check for pending async. exception 1926 if (_pending_async_exception != NULL) { 1927 // Only overwrite an already pending exception, if it is not a threadDeath. 1928 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 1929 1930 // We cannot call Exceptions::_throw(...) here because we cannot block 1931 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 1932 1933 if (TraceExceptions) { 1934 ResourceMark rm; 1935 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); 1936 if (has_last_Java_frame() ) { 1937 frame f = last_frame(); 1938 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); 1939 } 1940 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name()); 1941 } 1942 _pending_async_exception = NULL; 1943 clear_has_async_exception(); 1944 } 1945 } 1946 1947 if (check_unsafe_error && 1948 condition == _async_unsafe_access_error && !has_pending_exception()) { 1949 condition = _no_async_condition; // done 1950 switch (thread_state()) { 1951 case _thread_in_vm: 1952 { 1953 JavaThread* THREAD = this; 1954 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 1955 } 1956 case _thread_in_native: 1957 { 1958 ThreadInVMfromNative tiv(this); 1959 JavaThread* THREAD = this; 1960 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 1961 } 1962 case _thread_in_Java: 1963 { 1964 ThreadInVMfromJava tiv(this); 1965 JavaThread* THREAD = this; 1966 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 1967 } 1968 default: 1969 ShouldNotReachHere(); 1970 } 1971 } 1972 1973 assert(condition == _no_async_condition || has_pending_exception() || 1974 (!check_unsafe_error && condition == _async_unsafe_access_error), 1975 "must have handled the async condition, if no exception"); 1976 } 1977 1978 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 1979 // 1980 // Check for pending external suspend. Internal suspend requests do 1981 // not use handle_special_runtime_exit_condition(). 1982 // If JNIEnv proxies are allowed, don't self-suspend if the target 1983 // thread is not the current thread. In older versions of jdbx, jdbx 1984 // threads could call into the VM with another thread's JNIEnv so we 1985 // can be here operating on behalf of a suspended thread (4432884). 1986 bool do_self_suspend = is_external_suspend_with_lock(); 1987 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 1988 // 1989 // Because thread is external suspended the safepoint code will count 1990 // thread as at a safepoint. This can be odd because we can be here 1991 // as _thread_in_Java which would normally transition to _thread_blocked 1992 // at a safepoint. We would like to mark the thread as _thread_blocked 1993 // before calling java_suspend_self like all other callers of it but 1994 // we must then observe proper safepoint protocol. (We can't leave 1995 // _thread_blocked with a safepoint in progress). However we can be 1996 // here as _thread_in_native_trans so we can't use a normal transition 1997 // constructor/destructor pair because they assert on that type of 1998 // transition. We could do something like: 1999 // 2000 // JavaThreadState state = thread_state(); 2001 // set_thread_state(_thread_in_vm); 2002 // { 2003 // ThreadBlockInVM tbivm(this); 2004 // java_suspend_self() 2005 // } 2006 // set_thread_state(_thread_in_vm_trans); 2007 // if (safepoint) block; 2008 // set_thread_state(state); 2009 // 2010 // but that is pretty messy. Instead we just go with the way the 2011 // code has worked before and note that this is the only path to 2012 // java_suspend_self that doesn't put the thread in _thread_blocked 2013 // mode. 2014 2015 frame_anchor()->make_walkable(this); 2016 java_suspend_self(); 2017 2018 // We might be here for reasons in addition to the self-suspend request 2019 // so check for other async requests. 2020 } 2021 2022 if (check_asyncs) { 2023 check_and_handle_async_exceptions(); 2024 } 2025 } 2026 2027 void JavaThread::send_thread_stop(oop java_throwable) { 2028 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2029 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2030 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2031 2032 // Do not throw asynchronous exceptions against the compiler thread 2033 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2034 if (is_Compiler_thread()) return; 2035 2036 { 2037 // Actually throw the Throwable against the target Thread - however 2038 // only if there is no thread death exception installed already. 2039 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2040 // If the topmost frame is a runtime stub, then we are calling into 2041 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2042 // must deoptimize the caller before continuing, as the compiled exception handler table 2043 // may not be valid 2044 if (has_last_Java_frame()) { 2045 frame f = last_frame(); 2046 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2047 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2048 RegisterMap reg_map(this, UseBiasedLocking); 2049 frame compiled_frame = f.sender(®_map); 2050 if (compiled_frame.can_be_deoptimized()) { 2051 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2052 } 2053 } 2054 } 2055 2056 // Set async. pending exception in thread. 2057 set_pending_async_exception(java_throwable); 2058 2059 if (TraceExceptions) { 2060 ResourceMark rm; 2061 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name()); 2062 } 2063 // for AbortVMOnException flag 2064 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name())); 2065 } 2066 } 2067 2068 2069 // Interrupt thread so it will wake up from a potential wait() 2070 Thread::interrupt(this); 2071 } 2072 2073 // External suspension mechanism. 2074 // 2075 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2076 // to any VM_locks and it is at a transition 2077 // Self-suspension will happen on the transition out of the vm. 2078 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2079 // 2080 // Guarantees on return: 2081 // + Target thread will not execute any new bytecode (that's why we need to 2082 // force a safepoint) 2083 // + Target thread will not enter any new monitors 2084 // 2085 void JavaThread::java_suspend() { 2086 { MutexLocker mu(Threads_lock); 2087 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2088 return; 2089 } 2090 } 2091 2092 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2093 if (!is_external_suspend()) { 2094 // a racing resume has cancelled us; bail out now 2095 return; 2096 } 2097 2098 // suspend is done 2099 uint32_t debug_bits = 0; 2100 // Warning: is_ext_suspend_completed() may temporarily drop the 2101 // SR_lock to allow the thread to reach a stable thread state if 2102 // it is currently in a transient thread state. 2103 if (is_ext_suspend_completed(false /* !called_by_wait */, 2104 SuspendRetryDelay, &debug_bits) ) { 2105 return; 2106 } 2107 } 2108 2109 VM_ForceSafepoint vm_suspend; 2110 VMThread::execute(&vm_suspend); 2111 } 2112 2113 // Part II of external suspension. 2114 // A JavaThread self suspends when it detects a pending external suspend 2115 // request. This is usually on transitions. It is also done in places 2116 // where continuing to the next transition would surprise the caller, 2117 // e.g., monitor entry. 2118 // 2119 // Returns the number of times that the thread self-suspended. 2120 // 2121 // Note: DO NOT call java_suspend_self() when you just want to block current 2122 // thread. java_suspend_self() is the second stage of cooperative 2123 // suspension for external suspend requests and should only be used 2124 // to complete an external suspend request. 2125 // 2126 int JavaThread::java_suspend_self() { 2127 int ret = 0; 2128 2129 // we are in the process of exiting so don't suspend 2130 if (is_exiting()) { 2131 clear_external_suspend(); 2132 return ret; 2133 } 2134 2135 assert(_anchor.walkable() || 2136 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2137 "must have walkable stack"); 2138 2139 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2140 2141 assert(!this->is_ext_suspended(), 2142 "a thread trying to self-suspend should not already be suspended"); 2143 2144 if (this->is_suspend_equivalent()) { 2145 // If we are self-suspending as a result of the lifting of a 2146 // suspend equivalent condition, then the suspend_equivalent 2147 // flag is not cleared until we set the ext_suspended flag so 2148 // that wait_for_ext_suspend_completion() returns consistent 2149 // results. 2150 this->clear_suspend_equivalent(); 2151 } 2152 2153 // A racing resume may have cancelled us before we grabbed SR_lock 2154 // above. Or another external suspend request could be waiting for us 2155 // by the time we return from SR_lock()->wait(). The thread 2156 // that requested the suspension may already be trying to walk our 2157 // stack and if we return now, we can change the stack out from under 2158 // it. This would be a "bad thing (TM)" and cause the stack walker 2159 // to crash. We stay self-suspended until there are no more pending 2160 // external suspend requests. 2161 while (is_external_suspend()) { 2162 ret++; 2163 this->set_ext_suspended(); 2164 2165 // _ext_suspended flag is cleared by java_resume() 2166 while (is_ext_suspended()) { 2167 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2168 } 2169 } 2170 2171 return ret; 2172 } 2173 2174 #ifdef ASSERT 2175 // verify the JavaThread has not yet been published in the Threads::list, and 2176 // hence doesn't need protection from concurrent access at this stage 2177 void JavaThread::verify_not_published() { 2178 if (!Threads_lock->owned_by_self()) { 2179 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2180 assert( !Threads::includes(this), 2181 "java thread shouldn't have been published yet!"); 2182 } 2183 else { 2184 assert( !Threads::includes(this), 2185 "java thread shouldn't have been published yet!"); 2186 } 2187 } 2188 #endif 2189 2190 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2191 // progress or when _suspend_flags is non-zero. 2192 // Current thread needs to self-suspend if there is a suspend request and/or 2193 // block if a safepoint is in progress. 2194 // Async exception ISN'T checked. 2195 // Note only the ThreadInVMfromNative transition can call this function 2196 // directly and when thread state is _thread_in_native_trans 2197 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2198 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2199 2200 JavaThread *curJT = JavaThread::current(); 2201 bool do_self_suspend = thread->is_external_suspend(); 2202 2203 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2204 2205 // If JNIEnv proxies are allowed, don't self-suspend if the target 2206 // thread is not the current thread. In older versions of jdbx, jdbx 2207 // threads could call into the VM with another thread's JNIEnv so we 2208 // can be here operating on behalf of a suspended thread (4432884). 2209 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2210 JavaThreadState state = thread->thread_state(); 2211 2212 // We mark this thread_blocked state as a suspend-equivalent so 2213 // that a caller to is_ext_suspend_completed() won't be confused. 2214 // The suspend-equivalent state is cleared by java_suspend_self(). 2215 thread->set_suspend_equivalent(); 2216 2217 // If the safepoint code sees the _thread_in_native_trans state, it will 2218 // wait until the thread changes to other thread state. There is no 2219 // guarantee on how soon we can obtain the SR_lock and complete the 2220 // self-suspend request. It would be a bad idea to let safepoint wait for 2221 // too long. Temporarily change the state to _thread_blocked to 2222 // let the VM thread know that this thread is ready for GC. The problem 2223 // of changing thread state is that safepoint could happen just after 2224 // java_suspend_self() returns after being resumed, and VM thread will 2225 // see the _thread_blocked state. We must check for safepoint 2226 // after restoring the state and make sure we won't leave while a safepoint 2227 // is in progress. 2228 thread->set_thread_state(_thread_blocked); 2229 thread->java_suspend_self(); 2230 thread->set_thread_state(state); 2231 // Make sure new state is seen by VM thread 2232 if (os::is_MP()) { 2233 if (UseMembar) { 2234 // Force a fence between the write above and read below 2235 OrderAccess::fence(); 2236 } else { 2237 // Must use this rather than serialization page in particular on Windows 2238 InterfaceSupport::serialize_memory(thread); 2239 } 2240 } 2241 } 2242 2243 if (SafepointSynchronize::do_call_back()) { 2244 // If we are safepointing, then block the caller which may not be 2245 // the same as the target thread (see above). 2246 SafepointSynchronize::block(curJT); 2247 } 2248 2249 if (thread->is_deopt_suspend()) { 2250 thread->clear_deopt_suspend(); 2251 RegisterMap map(thread, false); 2252 frame f = thread->last_frame(); 2253 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2254 f = f.sender(&map); 2255 } 2256 if (f.id() == thread->must_deopt_id()) { 2257 thread->clear_must_deopt_id(); 2258 f.deoptimize(thread); 2259 } else { 2260 fatal("missed deoptimization!"); 2261 } 2262 } 2263 } 2264 2265 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2266 // progress or when _suspend_flags is non-zero. 2267 // Current thread needs to self-suspend if there is a suspend request and/or 2268 // block if a safepoint is in progress. 2269 // Also check for pending async exception (not including unsafe access error). 2270 // Note only the native==>VM/Java barriers can call this function and when 2271 // thread state is _thread_in_native_trans. 2272 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2273 check_safepoint_and_suspend_for_native_trans(thread); 2274 2275 if (thread->has_async_exception()) { 2276 // We are in _thread_in_native_trans state, don't handle unsafe 2277 // access error since that may block. 2278 thread->check_and_handle_async_exceptions(false); 2279 } 2280 } 2281 2282 // This is a variant of the normal 2283 // check_special_condition_for_native_trans with slightly different 2284 // semantics for use by critical native wrappers. It does all the 2285 // normal checks but also performs the transition back into 2286 // thread_in_Java state. This is required so that critical natives 2287 // can potentially block and perform a GC if they are the last thread 2288 // exiting the GC_locker. 2289 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2290 check_special_condition_for_native_trans(thread); 2291 2292 // Finish the transition 2293 thread->set_thread_state(_thread_in_Java); 2294 2295 if (thread->do_critical_native_unlock()) { 2296 ThreadInVMfromJavaNoAsyncException tiv(thread); 2297 GC_locker::unlock_critical(thread); 2298 thread->clear_critical_native_unlock(); 2299 } 2300 } 2301 2302 // We need to guarantee the Threads_lock here, since resumes are not 2303 // allowed during safepoint synchronization 2304 // Can only resume from an external suspension 2305 void JavaThread::java_resume() { 2306 assert_locked_or_safepoint(Threads_lock); 2307 2308 // Sanity check: thread is gone, has started exiting or the thread 2309 // was not externally suspended. 2310 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2311 return; 2312 } 2313 2314 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2315 2316 clear_external_suspend(); 2317 2318 if (is_ext_suspended()) { 2319 clear_ext_suspended(); 2320 SR_lock()->notify_all(); 2321 } 2322 } 2323 2324 void JavaThread::create_stack_guard_pages() { 2325 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; 2326 address low_addr = stack_base() - stack_size(); 2327 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2328 2329 int allocate = os::allocate_stack_guard_pages(); 2330 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2331 2332 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2333 warning("Attempt to allocate stack guard pages failed."); 2334 return; 2335 } 2336 2337 if (os::guard_memory((char *) low_addr, len)) { 2338 _stack_guard_state = stack_guard_enabled; 2339 } else { 2340 warning("Attempt to protect stack guard pages failed."); 2341 if (os::uncommit_memory((char *) low_addr, len)) { 2342 warning("Attempt to deallocate stack guard pages failed."); 2343 } 2344 } 2345 } 2346 2347 void JavaThread::remove_stack_guard_pages() { 2348 if (_stack_guard_state == stack_guard_unused) return; 2349 address low_addr = stack_base() - stack_size(); 2350 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2351 2352 if (os::allocate_stack_guard_pages()) { 2353 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2354 _stack_guard_state = stack_guard_unused; 2355 } else { 2356 warning("Attempt to deallocate stack guard pages failed."); 2357 } 2358 } else { 2359 if (_stack_guard_state == stack_guard_unused) return; 2360 if (os::unguard_memory((char *) low_addr, len)) { 2361 _stack_guard_state = stack_guard_unused; 2362 } else { 2363 warning("Attempt to unprotect stack guard pages failed."); 2364 } 2365 } 2366 } 2367 2368 void JavaThread::enable_stack_yellow_zone() { 2369 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2370 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2371 2372 // The base notation is from the stacks point of view, growing downward. 2373 // We need to adjust it to work correctly with guard_memory() 2374 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2375 2376 guarantee(base < stack_base(),"Error calculating stack yellow zone"); 2377 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone"); 2378 2379 if (os::guard_memory((char *) base, stack_yellow_zone_size())) { 2380 _stack_guard_state = stack_guard_enabled; 2381 } else { 2382 warning("Attempt to guard stack yellow zone failed."); 2383 } 2384 enable_register_stack_guard(); 2385 } 2386 2387 void JavaThread::disable_stack_yellow_zone() { 2388 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2389 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); 2390 2391 // Simply return if called for a thread that does not use guard pages. 2392 if (_stack_guard_state == stack_guard_unused) return; 2393 2394 // The base notation is from the stacks point of view, growing downward. 2395 // We need to adjust it to work correctly with guard_memory() 2396 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2397 2398 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { 2399 _stack_guard_state = stack_guard_yellow_disabled; 2400 } else { 2401 warning("Attempt to unguard stack yellow zone failed."); 2402 } 2403 disable_register_stack_guard(); 2404 } 2405 2406 void JavaThread::enable_stack_red_zone() { 2407 // The base notation is from the stacks point of view, growing downward. 2408 // We need to adjust it to work correctly with guard_memory() 2409 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2410 address base = stack_red_zone_base() - stack_red_zone_size(); 2411 2412 guarantee(base < stack_base(),"Error calculating stack red zone"); 2413 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone"); 2414 2415 if(!os::guard_memory((char *) base, stack_red_zone_size())) { 2416 warning("Attempt to guard stack red zone failed."); 2417 } 2418 } 2419 2420 void JavaThread::disable_stack_red_zone() { 2421 // The base notation is from the stacks point of view, growing downward. 2422 // We need to adjust it to work correctly with guard_memory() 2423 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2424 address base = stack_red_zone_base() - stack_red_zone_size(); 2425 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2426 warning("Attempt to unguard stack red zone failed."); 2427 } 2428 } 2429 2430 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2431 // ignore is there is no stack 2432 if (!has_last_Java_frame()) return; 2433 // traverse the stack frames. Starts from top frame. 2434 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2435 frame* fr = fst.current(); 2436 f(fr, fst.register_map()); 2437 } 2438 } 2439 2440 2441 #ifndef PRODUCT 2442 // Deoptimization 2443 // Function for testing deoptimization 2444 void JavaThread::deoptimize() { 2445 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2446 StackFrameStream fst(this, UseBiasedLocking); 2447 bool deopt = false; // Dump stack only if a deopt actually happens. 2448 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2449 // Iterate over all frames in the thread and deoptimize 2450 for(; !fst.is_done(); fst.next()) { 2451 if(fst.current()->can_be_deoptimized()) { 2452 2453 if (only_at) { 2454 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2455 // consists of comma or carriage return separated numbers so 2456 // search for the current bci in that string. 2457 address pc = fst.current()->pc(); 2458 nmethod* nm = (nmethod*) fst.current()->cb(); 2459 ScopeDesc* sd = nm->scope_desc_at( pc); 2460 char buffer[8]; 2461 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2462 size_t len = strlen(buffer); 2463 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2464 while (found != NULL) { 2465 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2466 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2467 // Check that the bci found is bracketed by terminators. 2468 break; 2469 } 2470 found = strstr(found + 1, buffer); 2471 } 2472 if (!found) { 2473 continue; 2474 } 2475 } 2476 2477 if (DebugDeoptimization && !deopt) { 2478 deopt = true; // One-time only print before deopt 2479 tty->print_cr("[BEFORE Deoptimization]"); 2480 trace_frames(); 2481 trace_stack(); 2482 } 2483 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2484 } 2485 } 2486 2487 if (DebugDeoptimization && deopt) { 2488 tty->print_cr("[AFTER Deoptimization]"); 2489 trace_frames(); 2490 } 2491 } 2492 2493 2494 // Make zombies 2495 void JavaThread::make_zombies() { 2496 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2497 if (fst.current()->can_be_deoptimized()) { 2498 // it is a Java nmethod 2499 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2500 nm->make_not_entrant(); 2501 } 2502 } 2503 } 2504 #endif // PRODUCT 2505 2506 2507 void JavaThread::deoptimized_wrt_marked_nmethods() { 2508 if (!has_last_Java_frame()) return; 2509 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2510 StackFrameStream fst(this, UseBiasedLocking); 2511 for(; !fst.is_done(); fst.next()) { 2512 if (fst.current()->should_be_deoptimized()) { 2513 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2514 } 2515 } 2516 } 2517 2518 2519 // GC support 2520 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); } 2521 2522 void JavaThread::gc_epilogue() { 2523 frames_do(frame_gc_epilogue); 2524 } 2525 2526 2527 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); } 2528 2529 void JavaThread::gc_prologue() { 2530 frames_do(frame_gc_prologue); 2531 } 2532 2533 // If the caller is a NamedThread, then remember, in the current scope, 2534 // the given JavaThread in its _processed_thread field. 2535 class RememberProcessedThread: public StackObj { 2536 NamedThread* _cur_thr; 2537 public: 2538 RememberProcessedThread(JavaThread* jthr) { 2539 Thread* thread = Thread::current(); 2540 if (thread->is_Named_thread()) { 2541 _cur_thr = (NamedThread *)thread; 2542 _cur_thr->set_processed_thread(jthr); 2543 } else { 2544 _cur_thr = NULL; 2545 } 2546 } 2547 2548 ~RememberProcessedThread() { 2549 if (_cur_thr) { 2550 _cur_thr->set_processed_thread(NULL); 2551 } 2552 } 2553 }; 2554 2555 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2556 // Verify that the deferred card marks have been flushed. 2557 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2558 2559 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2560 // since there may be more than one thread using each ThreadProfiler. 2561 2562 // Traverse the GCHandles 2563 Thread::oops_do(f, cf); 2564 2565 assert( (!has_last_Java_frame() && java_call_counter() == 0) || 2566 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2567 2568 if (has_last_Java_frame()) { 2569 // Record JavaThread to GC thread 2570 RememberProcessedThread rpt(this); 2571 2572 // Traverse the privileged stack 2573 if (_privileged_stack_top != NULL) { 2574 _privileged_stack_top->oops_do(f); 2575 } 2576 2577 // traverse the registered growable array 2578 if (_array_for_gc != NULL) { 2579 for (int index = 0; index < _array_for_gc->length(); index++) { 2580 f->do_oop(_array_for_gc->adr_at(index)); 2581 } 2582 } 2583 2584 // Traverse the monitor chunks 2585 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2586 chunk->oops_do(f); 2587 } 2588 2589 // Traverse the execution stack 2590 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2591 fst.current()->oops_do(f, cf, fst.register_map()); 2592 } 2593 } 2594 2595 // callee_target is never live across a gc point so NULL it here should 2596 // it still contain a methdOop. 2597 2598 set_callee_target(NULL); 2599 2600 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2601 // If we have deferred set_locals there might be oops waiting to be 2602 // written 2603 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2604 if (list != NULL) { 2605 for (int i = 0; i < list->length(); i++) { 2606 list->at(i)->oops_do(f); 2607 } 2608 } 2609 2610 // Traverse instance variables at the end since the GC may be moving things 2611 // around using this function 2612 f->do_oop((oop*) &_threadObj); 2613 f->do_oop((oop*) &_vm_result); 2614 f->do_oop((oop*) &_vm_result_2); 2615 f->do_oop((oop*) &_exception_oop); 2616 f->do_oop((oop*) &_pending_async_exception); 2617 2618 if (jvmti_thread_state() != NULL) { 2619 jvmti_thread_state()->oops_do(f); 2620 } 2621 } 2622 2623 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2624 Thread::nmethods_do(cf); // (super method is a no-op) 2625 2626 assert( (!has_last_Java_frame() && java_call_counter() == 0) || 2627 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2628 2629 if (has_last_Java_frame()) { 2630 // Traverse the execution stack 2631 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2632 fst.current()->nmethods_do(cf); 2633 } 2634 } 2635 } 2636 2637 // Printing 2638 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2639 switch (_thread_state) { 2640 case _thread_uninitialized: return "_thread_uninitialized"; 2641 case _thread_new: return "_thread_new"; 2642 case _thread_new_trans: return "_thread_new_trans"; 2643 case _thread_in_native: return "_thread_in_native"; 2644 case _thread_in_native_trans: return "_thread_in_native_trans"; 2645 case _thread_in_vm: return "_thread_in_vm"; 2646 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2647 case _thread_in_Java: return "_thread_in_Java"; 2648 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2649 case _thread_blocked: return "_thread_blocked"; 2650 case _thread_blocked_trans: return "_thread_blocked_trans"; 2651 default: return "unknown thread state"; 2652 } 2653 } 2654 2655 #ifndef PRODUCT 2656 void JavaThread::print_thread_state_on(outputStream *st) const { 2657 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2658 }; 2659 void JavaThread::print_thread_state() const { 2660 print_thread_state_on(tty); 2661 }; 2662 #endif // PRODUCT 2663 2664 // Called by Threads::print() for VM_PrintThreads operation 2665 void JavaThread::print_on(outputStream *st) const { 2666 st->print("\"%s\" ", get_thread_name()); 2667 oop thread_oop = threadObj(); 2668 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2669 Thread::print_on(st); 2670 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2671 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2672 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) { 2673 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2674 } 2675 #ifndef PRODUCT 2676 print_thread_state_on(st); 2677 _safepoint_state->print_on(st); 2678 #endif // PRODUCT 2679 } 2680 2681 // Called by fatal error handler. The difference between this and 2682 // JavaThread::print() is that we can't grab lock or allocate memory. 2683 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2684 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2685 oop thread_obj = threadObj(); 2686 if (thread_obj != NULL) { 2687 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2688 } 2689 st->print(" ["); 2690 st->print("%s", _get_thread_state_name(_thread_state)); 2691 if (osthread()) { 2692 st->print(", id=%d", osthread()->thread_id()); 2693 } 2694 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2695 _stack_base - _stack_size, _stack_base); 2696 st->print("]"); 2697 return; 2698 } 2699 2700 // Verification 2701 2702 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2703 2704 void JavaThread::verify() { 2705 // Verify oops in the thread. 2706 oops_do(&VerifyOopClosure::verify_oop, NULL); 2707 2708 // Verify the stack frames. 2709 frames_do(frame_verify); 2710 } 2711 2712 // CR 6300358 (sub-CR 2137150) 2713 // Most callers of this method assume that it can't return NULL but a 2714 // thread may not have a name whilst it is in the process of attaching to 2715 // the VM - see CR 6412693, and there are places where a JavaThread can be 2716 // seen prior to having it's threadObj set (eg JNI attaching threads and 2717 // if vm exit occurs during initialization). These cases can all be accounted 2718 // for such that this method never returns NULL. 2719 const char* JavaThread::get_thread_name() const { 2720 #ifdef ASSERT 2721 // early safepoints can hit while current thread does not yet have TLS 2722 if (!SafepointSynchronize::is_at_safepoint()) { 2723 Thread *cur = Thread::current(); 2724 if (!(cur->is_Java_thread() && cur == this)) { 2725 // Current JavaThreads are allowed to get their own name without 2726 // the Threads_lock. 2727 assert_locked_or_safepoint(Threads_lock); 2728 } 2729 } 2730 #endif // ASSERT 2731 return get_thread_name_string(); 2732 } 2733 2734 // Returns a non-NULL representation of this thread's name, or a suitable 2735 // descriptive string if there is no set name 2736 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2737 const char* name_str; 2738 oop thread_obj = threadObj(); 2739 if (thread_obj != NULL) { 2740 typeArrayOop name = java_lang_Thread::name(thread_obj); 2741 if (name != NULL) { 2742 if (buf == NULL) { 2743 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2744 } 2745 else { 2746 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen); 2747 } 2748 } 2749 else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2750 name_str = "<no-name - thread is attaching>"; 2751 } 2752 else { 2753 name_str = Thread::name(); 2754 } 2755 } 2756 else { 2757 name_str = Thread::name(); 2758 } 2759 assert(name_str != NULL, "unexpected NULL thread name"); 2760 return name_str; 2761 } 2762 2763 2764 const char* JavaThread::get_threadgroup_name() const { 2765 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2766 oop thread_obj = threadObj(); 2767 if (thread_obj != NULL) { 2768 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2769 if (thread_group != NULL) { 2770 typeArrayOop name = java_lang_ThreadGroup::name(thread_group); 2771 // ThreadGroup.name can be null 2772 if (name != NULL) { 2773 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2774 return str; 2775 } 2776 } 2777 } 2778 return NULL; 2779 } 2780 2781 const char* JavaThread::get_parent_name() const { 2782 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2783 oop thread_obj = threadObj(); 2784 if (thread_obj != NULL) { 2785 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2786 if (thread_group != NULL) { 2787 oop parent = java_lang_ThreadGroup::parent(thread_group); 2788 if (parent != NULL) { 2789 typeArrayOop name = java_lang_ThreadGroup::name(parent); 2790 // ThreadGroup.name can be null 2791 if (name != NULL) { 2792 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2793 return str; 2794 } 2795 } 2796 } 2797 } 2798 return NULL; 2799 } 2800 2801 ThreadPriority JavaThread::java_priority() const { 2802 oop thr_oop = threadObj(); 2803 if (thr_oop == NULL) return NormPriority; // Bootstrapping 2804 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 2805 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 2806 return priority; 2807 } 2808 2809 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 2810 2811 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 2812 // Link Java Thread object <-> C++ Thread 2813 2814 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 2815 // and put it into a new Handle. The Handle "thread_oop" can then 2816 // be used to pass the C++ thread object to other methods. 2817 2818 // Set the Java level thread object (jthread) field of the 2819 // new thread (a JavaThread *) to C++ thread object using the 2820 // "thread_oop" handle. 2821 2822 // Set the thread field (a JavaThread *) of the 2823 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 2824 2825 Handle thread_oop(Thread::current(), 2826 JNIHandles::resolve_non_null(jni_thread)); 2827 assert(instanceKlass::cast(thread_oop->klass())->is_linked(), 2828 "must be initialized"); 2829 set_threadObj(thread_oop()); 2830 java_lang_Thread::set_thread(thread_oop(), this); 2831 2832 if (prio == NoPriority) { 2833 prio = java_lang_Thread::priority(thread_oop()); 2834 assert(prio != NoPriority, "A valid priority should be present"); 2835 } 2836 2837 // Push the Java priority down to the native thread; needs Threads_lock 2838 Thread::set_priority(this, prio); 2839 2840 // Add the new thread to the Threads list and set it in motion. 2841 // We must have threads lock in order to call Threads::add. 2842 // It is crucial that we do not block before the thread is 2843 // added to the Threads list for if a GC happens, then the java_thread oop 2844 // will not be visited by GC. 2845 Threads::add(this); 2846 } 2847 2848 oop JavaThread::current_park_blocker() { 2849 // Support for JSR-166 locks 2850 oop thread_oop = threadObj(); 2851 if (thread_oop != NULL && 2852 JDK_Version::current().supports_thread_park_blocker()) { 2853 return java_lang_Thread::park_blocker(thread_oop); 2854 } 2855 return NULL; 2856 } 2857 2858 2859 void JavaThread::print_stack_on(outputStream* st) { 2860 if (!has_last_Java_frame()) return; 2861 ResourceMark rm; 2862 HandleMark hm; 2863 2864 RegisterMap reg_map(this); 2865 vframe* start_vf = last_java_vframe(®_map); 2866 int count = 0; 2867 for (vframe* f = start_vf; f; f = f->sender() ) { 2868 if (f->is_java_frame()) { 2869 javaVFrame* jvf = javaVFrame::cast(f); 2870 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 2871 2872 // Print out lock information 2873 if (JavaMonitorsInStackTrace) { 2874 jvf->print_lock_info_on(st, count); 2875 } 2876 } else { 2877 // Ignore non-Java frames 2878 } 2879 2880 // Bail-out case for too deep stacks 2881 count++; 2882 if (MaxJavaStackTraceDepth == count) return; 2883 } 2884 } 2885 2886 2887 // JVMTI PopFrame support 2888 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 2889 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 2890 if (in_bytes(size_in_bytes) != 0) { 2891 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes)); 2892 _popframe_preserved_args_size = in_bytes(size_in_bytes); 2893 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 2894 } 2895 } 2896 2897 void* JavaThread::popframe_preserved_args() { 2898 return _popframe_preserved_args; 2899 } 2900 2901 ByteSize JavaThread::popframe_preserved_args_size() { 2902 return in_ByteSize(_popframe_preserved_args_size); 2903 } 2904 2905 WordSize JavaThread::popframe_preserved_args_size_in_words() { 2906 int sz = in_bytes(popframe_preserved_args_size()); 2907 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 2908 return in_WordSize(sz / wordSize); 2909 } 2910 2911 void JavaThread::popframe_free_preserved_args() { 2912 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 2913 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 2914 _popframe_preserved_args = NULL; 2915 _popframe_preserved_args_size = 0; 2916 } 2917 2918 #ifndef PRODUCT 2919 2920 void JavaThread::trace_frames() { 2921 tty->print_cr("[Describe stack]"); 2922 int frame_no = 1; 2923 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2924 tty->print(" %d. ", frame_no++); 2925 fst.current()->print_value_on(tty,this); 2926 tty->cr(); 2927 } 2928 } 2929 2930 class PrintAndVerifyOopClosure: public OopClosure { 2931 protected: 2932 template <class T> inline void do_oop_work(T* p) { 2933 oop obj = oopDesc::load_decode_heap_oop(p); 2934 if (obj == NULL) return; 2935 tty->print(INTPTR_FORMAT ": ", p); 2936 if (obj->is_oop_or_null()) { 2937 if (obj->is_objArray()) { 2938 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj); 2939 } else { 2940 obj->print(); 2941 } 2942 } else { 2943 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj); 2944 } 2945 tty->cr(); 2946 } 2947 public: 2948 virtual void do_oop(oop* p) { do_oop_work(p); } 2949 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 2950 }; 2951 2952 2953 static void oops_print(frame* f, const RegisterMap *map) { 2954 PrintAndVerifyOopClosure print; 2955 f->print_value(); 2956 f->oops_do(&print, NULL, (RegisterMap*)map); 2957 } 2958 2959 // Print our all the locations that contain oops and whether they are 2960 // valid or not. This useful when trying to find the oldest frame 2961 // where an oop has gone bad since the frame walk is from youngest to 2962 // oldest. 2963 void JavaThread::trace_oops() { 2964 tty->print_cr("[Trace oops]"); 2965 frames_do(oops_print); 2966 } 2967 2968 2969 #ifdef ASSERT 2970 // Print or validate the layout of stack frames 2971 void JavaThread::print_frame_layout(int depth, bool validate_only) { 2972 ResourceMark rm; 2973 PRESERVE_EXCEPTION_MARK; 2974 FrameValues values; 2975 int frame_no = 0; 2976 for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 2977 fst.current()->describe(values, ++frame_no); 2978 if (depth == frame_no) break; 2979 } 2980 if (validate_only) { 2981 values.validate(); 2982 } else { 2983 tty->print_cr("[Describe stack layout]"); 2984 values.print(this); 2985 } 2986 } 2987 #endif 2988 2989 void JavaThread::trace_stack_from(vframe* start_vf) { 2990 ResourceMark rm; 2991 int vframe_no = 1; 2992 for (vframe* f = start_vf; f; f = f->sender() ) { 2993 if (f->is_java_frame()) { 2994 javaVFrame::cast(f)->print_activation(vframe_no++); 2995 } else { 2996 f->print(); 2997 } 2998 if (vframe_no > StackPrintLimit) { 2999 tty->print_cr("...<more frames>..."); 3000 return; 3001 } 3002 } 3003 } 3004 3005 3006 void JavaThread::trace_stack() { 3007 if (!has_last_Java_frame()) return; 3008 ResourceMark rm; 3009 HandleMark hm; 3010 RegisterMap reg_map(this); 3011 trace_stack_from(last_java_vframe(®_map)); 3012 } 3013 3014 3015 #endif // PRODUCT 3016 3017 3018 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3019 assert(reg_map != NULL, "a map must be given"); 3020 frame f = last_frame(); 3021 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) { 3022 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3023 } 3024 return NULL; 3025 } 3026 3027 3028 klassOop JavaThread::security_get_caller_class(int depth) { 3029 vframeStream vfst(this); 3030 vfst.security_get_caller_frame(depth); 3031 if (!vfst.at_end()) { 3032 return vfst.method()->method_holder(); 3033 } 3034 return NULL; 3035 } 3036 3037 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3038 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3039 CompileBroker::compiler_thread_loop(); 3040 } 3041 3042 // Create a CompilerThread 3043 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters) 3044 : JavaThread(&compiler_thread_entry) { 3045 _env = NULL; 3046 _log = NULL; 3047 _task = NULL; 3048 _queue = queue; 3049 _counters = counters; 3050 _buffer_blob = NULL; 3051 _scanned_nmethod = NULL; 3052 3053 #ifndef PRODUCT 3054 _ideal_graph_printer = NULL; 3055 #endif 3056 } 3057 3058 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3059 JavaThread::oops_do(f, cf); 3060 if (_scanned_nmethod != NULL && cf != NULL) { 3061 // Safepoints can occur when the sweeper is scanning an nmethod so 3062 // process it here to make sure it isn't unloaded in the middle of 3063 // a scan. 3064 cf->do_code_blob(_scanned_nmethod); 3065 } 3066 } 3067 3068 // ======= Threads ======== 3069 3070 // The Threads class links together all active threads, and provides 3071 // operations over all threads. It is protected by its own Mutex 3072 // lock, which is also used in other contexts to protect thread 3073 // operations from having the thread being operated on from exiting 3074 // and going away unexpectedly (e.g., safepoint synchronization) 3075 3076 JavaThread* Threads::_thread_list = NULL; 3077 int Threads::_number_of_threads = 0; 3078 int Threads::_number_of_non_daemon_threads = 0; 3079 int Threads::_return_code = 0; 3080 size_t JavaThread::_stack_size_at_create = 0; 3081 3082 // All JavaThreads 3083 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3084 3085 void os_stream(); 3086 3087 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3088 void Threads::threads_do(ThreadClosure* tc) { 3089 assert_locked_or_safepoint(Threads_lock); 3090 // ALL_JAVA_THREADS iterates through all JavaThreads 3091 ALL_JAVA_THREADS(p) { 3092 tc->do_thread(p); 3093 } 3094 // Someday we could have a table or list of all non-JavaThreads. 3095 // For now, just manually iterate through them. 3096 tc->do_thread(VMThread::vm_thread()); 3097 Universe::heap()->gc_threads_do(tc); 3098 WatcherThread *wt = WatcherThread::watcher_thread(); 3099 // Strictly speaking, the following NULL check isn't sufficient to make sure 3100 // the data for WatcherThread is still valid upon being examined. However, 3101 // considering that WatchThread terminates when the VM is on the way to 3102 // exit at safepoint, the chance of the above is extremely small. The right 3103 // way to prevent termination of WatcherThread would be to acquire 3104 // Terminator_lock, but we can't do that without violating the lock rank 3105 // checking in some cases. 3106 if (wt != NULL) 3107 tc->do_thread(wt); 3108 3109 // If CompilerThreads ever become non-JavaThreads, add them here 3110 } 3111 3112 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3113 3114 extern void JDK_Version_init(); 3115 3116 // Check version 3117 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3118 3119 // Initialize the output stream module 3120 ostream_init(); 3121 3122 // Process java launcher properties. 3123 Arguments::process_sun_java_launcher_properties(args); 3124 3125 // Initialize the os module before using TLS 3126 os::init(); 3127 3128 // Initialize system properties. 3129 Arguments::init_system_properties(); 3130 3131 // So that JDK version can be used as a discrimintor when parsing arguments 3132 JDK_Version_init(); 3133 3134 // Update/Initialize System properties after JDK version number is known 3135 Arguments::init_version_specific_system_properties(); 3136 3137 // Parse arguments 3138 jint parse_result = Arguments::parse(args); 3139 if (parse_result != JNI_OK) return parse_result; 3140 3141 if (PauseAtStartup) { 3142 os::pause(); 3143 } 3144 3145 #ifndef USDT2 3146 HS_DTRACE_PROBE(hotspot, vm__init__begin); 3147 #else /* USDT2 */ 3148 HOTSPOT_VM_INIT_BEGIN(); 3149 #endif /* USDT2 */ 3150 3151 // Record VM creation timing statistics 3152 TraceVmCreationTime create_vm_timer; 3153 create_vm_timer.start(); 3154 3155 // Timing (must come after argument parsing) 3156 TraceTime timer("Create VM", TraceStartupTime); 3157 3158 // Initialize the os module after parsing the args 3159 jint os_init_2_result = os::init_2(); 3160 if (os_init_2_result != JNI_OK) return os_init_2_result; 3161 3162 // Initialize output stream logging 3163 ostream_init_log(); 3164 3165 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3166 // Must be before create_vm_init_agents() 3167 if (Arguments::init_libraries_at_startup()) { 3168 convert_vm_init_libraries_to_agents(); 3169 } 3170 3171 // Launch -agentlib/-agentpath and converted -Xrun agents 3172 if (Arguments::init_agents_at_startup()) { 3173 create_vm_init_agents(); 3174 } 3175 3176 // Initialize Threads state 3177 _thread_list = NULL; 3178 _number_of_threads = 0; 3179 _number_of_non_daemon_threads = 0; 3180 3181 // Initialize TLS 3182 ThreadLocalStorage::init(); 3183 3184 // Initialize global data structures and create system classes in heap 3185 vm_init_globals(); 3186 3187 // Attach the main thread to this os thread 3188 JavaThread* main_thread = new JavaThread(); 3189 main_thread->set_thread_state(_thread_in_vm); 3190 // must do this before set_active_handles and initialize_thread_local_storage 3191 // Note: on solaris initialize_thread_local_storage() will (indirectly) 3192 // change the stack size recorded here to one based on the java thread 3193 // stacksize. This adjusted size is what is used to figure the placement 3194 // of the guard pages. 3195 main_thread->record_stack_base_and_size(); 3196 main_thread->initialize_thread_local_storage(); 3197 3198 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3199 3200 if (!main_thread->set_as_starting_thread()) { 3201 vm_shutdown_during_initialization( 3202 "Failed necessary internal allocation. Out of swap space"); 3203 delete main_thread; 3204 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3205 return JNI_ENOMEM; 3206 } 3207 3208 // Enable guard page *after* os::create_main_thread(), otherwise it would 3209 // crash Linux VM, see notes in os_linux.cpp. 3210 main_thread->create_stack_guard_pages(); 3211 3212 // Initialize Java-Level synchronization subsystem 3213 ObjectMonitor::Initialize() ; 3214 3215 // Initialize global modules 3216 jint status = init_globals(); 3217 if (status != JNI_OK) { 3218 delete main_thread; 3219 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3220 return status; 3221 } 3222 3223 // Must be run after init_ft which initializes ft_enabled 3224 if (TRACE_INITIALIZE() != JNI_OK) { 3225 vm_exit_during_initialization("Failed to initialize tracing backend"); 3226 } 3227 3228 // Should be done after the heap is fully created 3229 main_thread->cache_global_variables(); 3230 3231 HandleMark hm; 3232 3233 { MutexLocker mu(Threads_lock); 3234 Threads::add(main_thread); 3235 } 3236 3237 // Any JVMTI raw monitors entered in onload will transition into 3238 // real raw monitor. VM is setup enough here for raw monitor enter. 3239 JvmtiExport::transition_pending_onload_raw_monitors(); 3240 3241 if (VerifyBeforeGC && 3242 Universe::heap()->total_collections() >= VerifyGCStartAt) { 3243 Universe::heap()->prepare_for_verify(); 3244 Universe::verify(); // make sure we're starting with a clean slate 3245 } 3246 3247 // Create the VMThread 3248 { TraceTime timer("Start VMThread", TraceStartupTime); 3249 VMThread::create(); 3250 Thread* vmthread = VMThread::vm_thread(); 3251 3252 if (!os::create_thread(vmthread, os::vm_thread)) 3253 vm_exit_during_initialization("Cannot create VM thread. Out of system resources."); 3254 3255 // Wait for the VM thread to become ready, and VMThread::run to initialize 3256 // Monitors can have spurious returns, must always check another state flag 3257 { 3258 MutexLocker ml(Notify_lock); 3259 os::start_thread(vmthread); 3260 while (vmthread->active_handles() == NULL) { 3261 Notify_lock->wait(); 3262 } 3263 } 3264 } 3265 3266 assert (Universe::is_fully_initialized(), "not initialized"); 3267 EXCEPTION_MARK; 3268 3269 // At this point, the Universe is initialized, but we have not executed 3270 // any byte code. Now is a good time (the only time) to dump out the 3271 // internal state of the JVM for sharing. 3272 3273 if (DumpSharedSpaces) { 3274 Universe::heap()->preload_and_dump(CHECK_0); 3275 ShouldNotReachHere(); 3276 } 3277 3278 // Always call even when there are not JVMTI environments yet, since environments 3279 // may be attached late and JVMTI must track phases of VM execution 3280 JvmtiExport::enter_start_phase(); 3281 3282 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3283 JvmtiExport::post_vm_start(); 3284 3285 { 3286 TraceTime timer("Initialize java.lang classes", TraceStartupTime); 3287 3288 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3289 create_vm_init_libraries(); 3290 } 3291 3292 if (InitializeJavaLangString) { 3293 initialize_class(vmSymbols::java_lang_String(), CHECK_0); 3294 } else { 3295 warning("java.lang.String not initialized"); 3296 } 3297 3298 if (AggressiveOpts) { 3299 { 3300 // Forcibly initialize java/util/HashMap and mutate the private 3301 // static final "frontCacheEnabled" field before we start creating instances 3302 #ifdef ASSERT 3303 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0); 3304 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet"); 3305 #endif 3306 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0); 3307 KlassHandle k = KlassHandle(THREAD, k_o); 3308 guarantee(k.not_null(), "Must find java/util/HashMap"); 3309 instanceKlassHandle ik = instanceKlassHandle(THREAD, k()); 3310 ik->initialize(CHECK_0); 3311 fieldDescriptor fd; 3312 // Possible we might not find this field; if so, don't break 3313 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) { 3314 k()->java_mirror()->bool_field_put(fd.offset(), true); 3315 } 3316 } 3317 3318 if (UseStringCache) { 3319 // Forcibly initialize java/lang/StringValue and mutate the private 3320 // static final "stringCacheEnabled" field before we start creating instances 3321 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0); 3322 // Possible that StringValue isn't present: if so, silently don't break 3323 if (k_o != NULL) { 3324 KlassHandle k = KlassHandle(THREAD, k_o); 3325 instanceKlassHandle ik = instanceKlassHandle(THREAD, k()); 3326 ik->initialize(CHECK_0); 3327 fieldDescriptor fd; 3328 // Possible we might not find this field: if so, silently don't break 3329 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) { 3330 k()->java_mirror()->bool_field_put(fd.offset(), true); 3331 } 3332 } 3333 } 3334 } 3335 3336 // Initialize java_lang.System (needed before creating the thread) 3337 if (InitializeJavaLangSystem) { 3338 initialize_class(vmSymbols::java_lang_System(), CHECK_0); 3339 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0); 3340 Handle thread_group = create_initial_thread_group(CHECK_0); 3341 Universe::set_main_thread_group(thread_group()); 3342 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0); 3343 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0); 3344 main_thread->set_threadObj(thread_object); 3345 // Set thread status to running since main thread has 3346 // been started and running. 3347 java_lang_Thread::set_thread_status(thread_object, 3348 java_lang_Thread::RUNNABLE); 3349 3350 // The VM preresolve methods to these classes. Make sure that get initialized 3351 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0); 3352 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0); 3353 // The VM creates & returns objects of this class. Make sure it's initialized. 3354 initialize_class(vmSymbols::java_lang_Class(), CHECK_0); 3355 call_initializeSystemClass(CHECK_0); 3356 } else { 3357 warning("java.lang.System not initialized"); 3358 } 3359 3360 // an instance of OutOfMemory exception has been allocated earlier 3361 if (InitializeJavaLangExceptionsErrors) { 3362 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0); 3363 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0); 3364 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0); 3365 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0); 3366 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0); 3367 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0); 3368 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0); 3369 } else { 3370 warning("java.lang.OutOfMemoryError has not been initialized"); 3371 warning("java.lang.NullPointerException has not been initialized"); 3372 warning("java.lang.ClassCastException has not been initialized"); 3373 warning("java.lang.ArrayStoreException has not been initialized"); 3374 warning("java.lang.ArithmeticException has not been initialized"); 3375 warning("java.lang.StackOverflowError has not been initialized"); 3376 } 3377 } 3378 3379 // See : bugid 4211085. 3380 // Background : the static initializer of java.lang.Compiler tries to read 3381 // property"java.compiler" and read & write property "java.vm.info". 3382 // When a security manager is installed through the command line 3383 // option "-Djava.security.manager", the above properties are not 3384 // readable and the static initializer for java.lang.Compiler fails 3385 // resulting in a NoClassDefFoundError. This can happen in any 3386 // user code which calls methods in java.lang.Compiler. 3387 // Hack : the hack is to pre-load and initialize this class, so that only 3388 // system domains are on the stack when the properties are read. 3389 // Currently even the AWT code has calls to methods in java.lang.Compiler. 3390 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT. 3391 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and 3392 // read and write"java.vm.info" in the default policy file. See bugid 4211383 3393 // Once that is done, we should remove this hack. 3394 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0); 3395 3396 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to 3397 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot 3398 // compiler does not get loaded through java.lang.Compiler). "java -version" with the 3399 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here. 3400 // This should also be taken out as soon as 4211383 gets fixed. 3401 reset_vm_info_property(CHECK_0); 3402 3403 quicken_jni_functions(); 3404 3405 // Set flag that basic initialization has completed. Used by exceptions and various 3406 // debug stuff, that does not work until all basic classes have been initialized. 3407 set_init_completed(); 3408 3409 #ifndef USDT2 3410 HS_DTRACE_PROBE(hotspot, vm__init__end); 3411 #else /* USDT2 */ 3412 HOTSPOT_VM_INIT_END(); 3413 #endif /* USDT2 */ 3414 3415 // record VM initialization completion time 3416 Management::record_vm_init_completed(); 3417 3418 // Compute system loader. Note that this has to occur after set_init_completed, since 3419 // valid exceptions may be thrown in the process. 3420 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3421 // set_init_completed has just been called, causing exceptions not to be shortcut 3422 // anymore. We call vm_exit_during_initialization directly instead. 3423 SystemDictionary::compute_java_system_loader(THREAD); 3424 if (HAS_PENDING_EXCEPTION) { 3425 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); 3426 } 3427 3428 #ifndef SERIALGC 3429 // Support for ConcurrentMarkSweep. This should be cleaned up 3430 // and better encapsulated. The ugly nested if test would go away 3431 // once things are properly refactored. XXX YSR 3432 if (UseConcMarkSweepGC || UseG1GC) { 3433 if (UseConcMarkSweepGC) { 3434 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD); 3435 } else { 3436 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD); 3437 } 3438 if (HAS_PENDING_EXCEPTION) { 3439 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); 3440 } 3441 } 3442 #endif // SERIALGC 3443 3444 // Always call even when there are not JVMTI environments yet, since environments 3445 // may be attached late and JVMTI must track phases of VM execution 3446 JvmtiExport::enter_live_phase(); 3447 3448 // Signal Dispatcher needs to be started before VMInit event is posted 3449 os::signal_init(); 3450 3451 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3452 if (!DisableAttachMechanism) { 3453 if (StartAttachListener || AttachListener::init_at_startup()) { 3454 AttachListener::init(); 3455 } 3456 } 3457 3458 // Launch -Xrun agents 3459 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3460 // back-end can launch with -Xdebug -Xrunjdwp. 3461 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3462 create_vm_init_libraries(); 3463 } 3464 3465 if (!TRACE_START()) { 3466 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); 3467 } 3468 3469 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3470 JvmtiExport::post_vm_initialized(); 3471 3472 if (CleanChunkPoolAsync) { 3473 Chunk::start_chunk_pool_cleaner_task(); 3474 } 3475 3476 // initialize compiler(s) 3477 CompileBroker::compilation_init(); 3478 3479 Management::initialize(THREAD); 3480 if (HAS_PENDING_EXCEPTION) { 3481 // management agent fails to start possibly due to 3482 // configuration problem and is responsible for printing 3483 // stack trace if appropriate. Simply exit VM. 3484 vm_exit(1); 3485 } 3486 3487 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3488 if (Arguments::has_alloc_profile()) AllocationProfiler::engage(); 3489 if (MemProfiling) MemProfiler::engage(); 3490 StatSampler::engage(); 3491 if (CheckJNICalls) JniPeriodicChecker::engage(); 3492 3493 BiasedLocking::init(); 3494 3495 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3496 call_postVMInitHook(THREAD); 3497 // The Java side of PostVMInitHook.run must deal with all 3498 // exceptions and provide means of diagnosis. 3499 if (HAS_PENDING_EXCEPTION) { 3500 CLEAR_PENDING_EXCEPTION; 3501 } 3502 } 3503 3504 // Start up the WatcherThread if there are any periodic tasks 3505 // NOTE: All PeriodicTasks should be registered by now. If they 3506 // aren't, late joiners might appear to start slowly (we might 3507 // take a while to process their first tick). 3508 if (PeriodicTask::num_tasks() > 0) { 3509 WatcherThread::start(); 3510 } 3511 3512 // Give os specific code one last chance to start 3513 os::init_3(); 3514 3515 create_vm_timer.end(); 3516 return JNI_OK; 3517 } 3518 3519 // type for the Agent_OnLoad and JVM_OnLoad entry points 3520 extern "C" { 3521 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3522 } 3523 // Find a command line agent library and return its entry point for 3524 // -agentlib: -agentpath: -Xrun 3525 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3526 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) { 3527 OnLoadEntry_t on_load_entry = NULL; 3528 void *library = agent->os_lib(); // check if we have looked it up before 3529 3530 if (library == NULL) { 3531 char buffer[JVM_MAXPATHLEN]; 3532 char ebuf[1024]; 3533 const char *name = agent->name(); 3534 const char *msg = "Could not find agent library "; 3535 3536 if (agent->is_absolute_path()) { 3537 library = os::dll_load(name, ebuf, sizeof ebuf); 3538 if (library == NULL) { 3539 const char *sub_msg = " in absolute path, with error: "; 3540 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3541 char *buf = NEW_C_HEAP_ARRAY(char, len); 3542 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3543 // If we can't find the agent, exit. 3544 vm_exit_during_initialization(buf, NULL); 3545 FREE_C_HEAP_ARRAY(char, buf); 3546 } 3547 } else { 3548 // Try to load the agent from the standard dll directory 3549 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name); 3550 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3551 #ifdef KERNEL 3552 // Download instrument dll 3553 if (library == NULL && strcmp(name, "instrument") == 0) { 3554 char *props = Arguments::get_kernel_properties(); 3555 char *home = Arguments::get_java_home(); 3556 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false" 3557 " sun.jkernel.DownloadManager -download client_jvm"; 3558 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1; 3559 char *cmd = NEW_C_HEAP_ARRAY(char, length); 3560 jio_snprintf(cmd, length, fmt, home, props); 3561 int status = os::fork_and_exec(cmd); 3562 FreeHeap(props); 3563 if (status == -1) { 3564 warning(cmd); 3565 vm_exit_during_initialization("fork_and_exec failed: %s", 3566 strerror(errno)); 3567 } 3568 FREE_C_HEAP_ARRAY(char, cmd); 3569 // when this comes back the instrument.dll should be where it belongs. 3570 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3571 } 3572 #endif // KERNEL 3573 if (library == NULL) { // Try the local directory 3574 char ns[1] = {0}; 3575 os::dll_build_name(buffer, sizeof(buffer), ns, name); 3576 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3577 if (library == NULL) { 3578 const char *sub_msg = " on the library path, with error: "; 3579 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3580 char *buf = NEW_C_HEAP_ARRAY(char, len); 3581 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3582 // If we can't find the agent, exit. 3583 vm_exit_during_initialization(buf, NULL); 3584 FREE_C_HEAP_ARRAY(char, buf); 3585 } 3586 } 3587 } 3588 agent->set_os_lib(library); 3589 } 3590 3591 // Find the OnLoad function. 3592 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) { 3593 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index])); 3594 if (on_load_entry != NULL) break; 3595 } 3596 return on_load_entry; 3597 } 3598 3599 // Find the JVM_OnLoad entry point 3600 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3601 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3602 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3603 } 3604 3605 // Find the Agent_OnLoad entry point 3606 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3607 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3608 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3609 } 3610 3611 // For backwards compatibility with -Xrun 3612 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3613 // treated like -agentpath: 3614 // Must be called before agent libraries are created 3615 void Threads::convert_vm_init_libraries_to_agents() { 3616 AgentLibrary* agent; 3617 AgentLibrary* next; 3618 3619 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3620 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3621 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3622 3623 // If there is an JVM_OnLoad function it will get called later, 3624 // otherwise see if there is an Agent_OnLoad 3625 if (on_load_entry == NULL) { 3626 on_load_entry = lookup_agent_on_load(agent); 3627 if (on_load_entry != NULL) { 3628 // switch it to the agent list -- so that Agent_OnLoad will be called, 3629 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3630 Arguments::convert_library_to_agent(agent); 3631 } else { 3632 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3633 } 3634 } 3635 } 3636 } 3637 3638 // Create agents for -agentlib: -agentpath: and converted -Xrun 3639 // Invokes Agent_OnLoad 3640 // Called very early -- before JavaThreads exist 3641 void Threads::create_vm_init_agents() { 3642 extern struct JavaVM_ main_vm; 3643 AgentLibrary* agent; 3644 3645 JvmtiExport::enter_onload_phase(); 3646 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3647 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3648 3649 if (on_load_entry != NULL) { 3650 // Invoke the Agent_OnLoad function 3651 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3652 if (err != JNI_OK) { 3653 vm_exit_during_initialization("agent library failed to init", agent->name()); 3654 } 3655 } else { 3656 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3657 } 3658 } 3659 JvmtiExport::enter_primordial_phase(); 3660 } 3661 3662 extern "C" { 3663 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3664 } 3665 3666 void Threads::shutdown_vm_agents() { 3667 // Send any Agent_OnUnload notifications 3668 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3669 extern struct JavaVM_ main_vm; 3670 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3671 3672 // Find the Agent_OnUnload function. 3673 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) { 3674 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3675 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index])); 3676 3677 // Invoke the Agent_OnUnload function 3678 if (unload_entry != NULL) { 3679 JavaThread* thread = JavaThread::current(); 3680 ThreadToNativeFromVM ttn(thread); 3681 HandleMark hm(thread); 3682 (*unload_entry)(&main_vm); 3683 break; 3684 } 3685 } 3686 } 3687 } 3688 3689 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3690 // Invokes JVM_OnLoad 3691 void Threads::create_vm_init_libraries() { 3692 extern struct JavaVM_ main_vm; 3693 AgentLibrary* agent; 3694 3695 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3696 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3697 3698 if (on_load_entry != NULL) { 3699 // Invoke the JVM_OnLoad function 3700 JavaThread* thread = JavaThread::current(); 3701 ThreadToNativeFromVM ttn(thread); 3702 HandleMark hm(thread); 3703 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3704 if (err != JNI_OK) { 3705 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 3706 } 3707 } else { 3708 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 3709 } 3710 } 3711 } 3712 3713 // Last thread running calls java.lang.Shutdown.shutdown() 3714 void JavaThread::invoke_shutdown_hooks() { 3715 HandleMark hm(this); 3716 3717 // We could get here with a pending exception, if so clear it now. 3718 if (this->has_pending_exception()) { 3719 this->clear_pending_exception(); 3720 } 3721 3722 EXCEPTION_MARK; 3723 klassOop k = 3724 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 3725 THREAD); 3726 if (k != NULL) { 3727 // SystemDictionary::resolve_or_null will return null if there was 3728 // an exception. If we cannot load the Shutdown class, just don't 3729 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 3730 // and finalizers (if runFinalizersOnExit is set) won't be run. 3731 // Note that if a shutdown hook was registered or runFinalizersOnExit 3732 // was called, the Shutdown class would have already been loaded 3733 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 3734 instanceKlassHandle shutdown_klass (THREAD, k); 3735 JavaValue result(T_VOID); 3736 JavaCalls::call_static(&result, 3737 shutdown_klass, 3738 vmSymbols::shutdown_method_name(), 3739 vmSymbols::void_method_signature(), 3740 THREAD); 3741 } 3742 CLEAR_PENDING_EXCEPTION; 3743 } 3744 3745 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 3746 // the program falls off the end of main(). Another VM exit path is through 3747 // vm_exit() when the program calls System.exit() to return a value or when 3748 // there is a serious error in VM. The two shutdown paths are not exactly 3749 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 3750 // and VM_Exit op at VM level. 3751 // 3752 // Shutdown sequence: 3753 // + Wait until we are the last non-daemon thread to execute 3754 // <-- every thing is still working at this moment --> 3755 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 3756 // shutdown hooks, run finalizers if finalization-on-exit 3757 // + Call before_exit(), prepare for VM exit 3758 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 3759 // currently the only user of this mechanism is File.deleteOnExit()) 3760 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 3761 // post thread end and vm death events to JVMTI, 3762 // stop signal thread 3763 // + Call JavaThread::exit(), it will: 3764 // > release JNI handle blocks, remove stack guard pages 3765 // > remove this thread from Threads list 3766 // <-- no more Java code from this thread after this point --> 3767 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 3768 // the compiler threads at safepoint 3769 // <-- do not use anything that could get blocked by Safepoint --> 3770 // + Disable tracing at JNI/JVM barriers 3771 // + Set _vm_exited flag for threads that are still running native code 3772 // + Delete this thread 3773 // + Call exit_globals() 3774 // > deletes tty 3775 // > deletes PerfMemory resources 3776 // + Return to caller 3777 3778 bool Threads::destroy_vm() { 3779 JavaThread* thread = JavaThread::current(); 3780 3781 // Wait until we are the last non-daemon thread to execute 3782 { MutexLocker nu(Threads_lock); 3783 while (Threads::number_of_non_daemon_threads() > 1 ) 3784 // This wait should make safepoint checks, wait without a timeout, 3785 // and wait as a suspend-equivalent condition. 3786 // 3787 // Note: If the FlatProfiler is running and this thread is waiting 3788 // for another non-daemon thread to finish, then the FlatProfiler 3789 // is waiting for the external suspend request on this thread to 3790 // complete. wait_for_ext_suspend_completion() will eventually 3791 // timeout, but that takes time. Making this wait a suspend- 3792 // equivalent condition solves that timeout problem. 3793 // 3794 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 3795 Mutex::_as_suspend_equivalent_flag); 3796 } 3797 3798 // Hang forever on exit if we are reporting an error. 3799 if (ShowMessageBoxOnError && is_error_reported()) { 3800 os::infinite_sleep(); 3801 } 3802 os::wait_for_keypress_at_exit(); 3803 3804 if (JDK_Version::is_jdk12x_version()) { 3805 // We are the last thread running, so check if finalizers should be run. 3806 // For 1.3 or later this is done in thread->invoke_shutdown_hooks() 3807 HandleMark rm(thread); 3808 Universe::run_finalizers_on_exit(); 3809 } else { 3810 // run Java level shutdown hooks 3811 thread->invoke_shutdown_hooks(); 3812 } 3813 3814 before_exit(thread); 3815 3816 thread->exit(true); 3817 3818 // Stop VM thread. 3819 { 3820 // 4945125 The vm thread comes to a safepoint during exit. 3821 // GC vm_operations can get caught at the safepoint, and the 3822 // heap is unparseable if they are caught. Grab the Heap_lock 3823 // to prevent this. The GC vm_operations will not be able to 3824 // queue until after the vm thread is dead. 3825 // After this point, we'll never emerge out of the safepoint before 3826 // the VM exits, so concurrent GC threads do not need to be explicitly 3827 // stopped; they remain inactive until the process exits. 3828 // Note: some concurrent G1 threads may be running during a safepoint, 3829 // but these will not be accessing the heap, just some G1-specific side 3830 // data structures that are not accessed by any other threads but them 3831 // after this point in a terminal safepoint. 3832 3833 MutexLocker ml(Heap_lock); 3834 3835 VMThread::wait_for_vm_thread_exit(); 3836 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 3837 VMThread::destroy(); 3838 } 3839 3840 // clean up ideal graph printers 3841 #if defined(COMPILER2) && !defined(PRODUCT) 3842 IdealGraphPrinter::clean_up(); 3843 #endif 3844 3845 // Now, all Java threads are gone except daemon threads. Daemon threads 3846 // running Java code or in VM are stopped by the Safepoint. However, 3847 // daemon threads executing native code are still running. But they 3848 // will be stopped at native=>Java/VM barriers. Note that we can't 3849 // simply kill or suspend them, as it is inherently deadlock-prone. 3850 3851 #ifndef PRODUCT 3852 // disable function tracing at JNI/JVM barriers 3853 TraceJNICalls = false; 3854 TraceJVMCalls = false; 3855 TraceRuntimeCalls = false; 3856 #endif 3857 3858 VM_Exit::set_vm_exited(); 3859 3860 notify_vm_shutdown(); 3861 3862 delete thread; 3863 3864 // exit_globals() will delete tty 3865 exit_globals(); 3866 3867 return true; 3868 } 3869 3870 3871 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 3872 if (version == JNI_VERSION_1_1) return JNI_TRUE; 3873 return is_supported_jni_version(version); 3874 } 3875 3876 3877 jboolean Threads::is_supported_jni_version(jint version) { 3878 if (version == JNI_VERSION_1_2) return JNI_TRUE; 3879 if (version == JNI_VERSION_1_4) return JNI_TRUE; 3880 if (version == JNI_VERSION_1_6) return JNI_TRUE; 3881 return JNI_FALSE; 3882 } 3883 3884 3885 void Threads::add(JavaThread* p, bool force_daemon) { 3886 // The threads lock must be owned at this point 3887 assert_locked_or_safepoint(Threads_lock); 3888 3889 // See the comment for this method in thread.hpp for its purpose and 3890 // why it is called here. 3891 p->initialize_queues(); 3892 p->set_next(_thread_list); 3893 _thread_list = p; 3894 _number_of_threads++; 3895 oop threadObj = p->threadObj(); 3896 bool daemon = true; 3897 // Bootstrapping problem: threadObj can be null for initial 3898 // JavaThread (or for threads attached via JNI) 3899 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 3900 _number_of_non_daemon_threads++; 3901 daemon = false; 3902 } 3903 3904 ThreadService::add_thread(p, daemon); 3905 3906 // Possible GC point. 3907 Events::log(p, "Thread added: " INTPTR_FORMAT, p); 3908 } 3909 3910 void Threads::remove(JavaThread* p) { 3911 // Extra scope needed for Thread_lock, so we can check 3912 // that we do not remove thread without safepoint code notice 3913 { MutexLocker ml(Threads_lock); 3914 3915 assert(includes(p), "p must be present"); 3916 3917 JavaThread* current = _thread_list; 3918 JavaThread* prev = NULL; 3919 3920 while (current != p) { 3921 prev = current; 3922 current = current->next(); 3923 } 3924 3925 if (prev) { 3926 prev->set_next(current->next()); 3927 } else { 3928 _thread_list = p->next(); 3929 } 3930 _number_of_threads--; 3931 oop threadObj = p->threadObj(); 3932 bool daemon = true; 3933 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 3934 _number_of_non_daemon_threads--; 3935 daemon = false; 3936 3937 // Only one thread left, do a notify on the Threads_lock so a thread waiting 3938 // on destroy_vm will wake up. 3939 if (number_of_non_daemon_threads() == 1) 3940 Threads_lock->notify_all(); 3941 } 3942 ThreadService::remove_thread(p, daemon); 3943 3944 // Make sure that safepoint code disregard this thread. This is needed since 3945 // the thread might mess around with locks after this point. This can cause it 3946 // to do callbacks into the safepoint code. However, the safepoint code is not aware 3947 // of this thread since it is removed from the queue. 3948 p->set_terminated_value(); 3949 } // unlock Threads_lock 3950 3951 // Since Events::log uses a lock, we grab it outside the Threads_lock 3952 Events::log(p, "Thread exited: " INTPTR_FORMAT, p); 3953 } 3954 3955 // Threads_lock must be held when this is called (or must be called during a safepoint) 3956 bool Threads::includes(JavaThread* p) { 3957 assert(Threads_lock->is_locked(), "sanity check"); 3958 ALL_JAVA_THREADS(q) { 3959 if (q == p ) { 3960 return true; 3961 } 3962 } 3963 return false; 3964 } 3965 3966 // Operations on the Threads list for GC. These are not explicitly locked, 3967 // but the garbage collector must provide a safe context for them to run. 3968 // In particular, these things should never be called when the Threads_lock 3969 // is held by some other thread. (Note: the Safepoint abstraction also 3970 // uses the Threads_lock to gurantee this property. It also makes sure that 3971 // all threads gets blocked when exiting or starting). 3972 3973 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3974 ALL_JAVA_THREADS(p) { 3975 p->oops_do(f, cf); 3976 } 3977 VMThread::vm_thread()->oops_do(f, cf); 3978 } 3979 3980 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) { 3981 // Introduce a mechanism allowing parallel threads to claim threads as 3982 // root groups. Overhead should be small enough to use all the time, 3983 // even in sequential code. 3984 SharedHeap* sh = SharedHeap::heap(); 3985 // Cannot yet substitute active_workers for n_par_threads 3986 // because of G1CollectedHeap::verify() use of 3987 // SharedHeap::process_strong_roots(). n_par_threads == 0 will 3988 // turn off parallelism in process_strong_roots while active_workers 3989 // is being used for parallelism elsewhere. 3990 bool is_par = sh->n_par_threads() > 0; 3991 assert(!is_par || 3992 (SharedHeap::heap()->n_par_threads() == 3993 SharedHeap::heap()->workers()->active_workers()), "Mismatch"); 3994 int cp = SharedHeap::heap()->strong_roots_parity(); 3995 ALL_JAVA_THREADS(p) { 3996 if (p->claim_oops_do(is_par, cp)) { 3997 p->oops_do(f, cf); 3998 } 3999 } 4000 VMThread* vmt = VMThread::vm_thread(); 4001 if (vmt->claim_oops_do(is_par, cp)) { 4002 vmt->oops_do(f, cf); 4003 } 4004 } 4005 4006 #ifndef SERIALGC 4007 // Used by ParallelScavenge 4008 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4009 ALL_JAVA_THREADS(p) { 4010 q->enqueue(new ThreadRootsTask(p)); 4011 } 4012 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4013 } 4014 4015 // Used by Parallel Old 4016 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4017 ALL_JAVA_THREADS(p) { 4018 q->enqueue(new ThreadRootsMarkingTask(p)); 4019 } 4020 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4021 } 4022 #endif // SERIALGC 4023 4024 void Threads::nmethods_do(CodeBlobClosure* cf) { 4025 ALL_JAVA_THREADS(p) { 4026 p->nmethods_do(cf); 4027 } 4028 VMThread::vm_thread()->nmethods_do(cf); 4029 } 4030 4031 void Threads::gc_epilogue() { 4032 ALL_JAVA_THREADS(p) { 4033 p->gc_epilogue(); 4034 } 4035 } 4036 4037 void Threads::gc_prologue() { 4038 ALL_JAVA_THREADS(p) { 4039 p->gc_prologue(); 4040 } 4041 } 4042 4043 void Threads::deoptimized_wrt_marked_nmethods() { 4044 ALL_JAVA_THREADS(p) { 4045 p->deoptimized_wrt_marked_nmethods(); 4046 } 4047 } 4048 4049 4050 // Get count Java threads that are waiting to enter the specified monitor. 4051 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4052 address monitor, bool doLock) { 4053 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4054 "must grab Threads_lock or be at safepoint"); 4055 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4056 4057 int i = 0; 4058 { 4059 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4060 ALL_JAVA_THREADS(p) { 4061 if (p->is_Compiler_thread()) continue; 4062 4063 address pending = (address)p->current_pending_monitor(); 4064 if (pending == monitor) { // found a match 4065 if (i < count) result->append(p); // save the first count matches 4066 i++; 4067 } 4068 } 4069 } 4070 return result; 4071 } 4072 4073 4074 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) { 4075 assert(doLock || 4076 Threads_lock->owned_by_self() || 4077 SafepointSynchronize::is_at_safepoint(), 4078 "must grab Threads_lock or be at safepoint"); 4079 4080 // NULL owner means not locked so we can skip the search 4081 if (owner == NULL) return NULL; 4082 4083 { 4084 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4085 ALL_JAVA_THREADS(p) { 4086 // first, see if owner is the address of a Java thread 4087 if (owner == (address)p) return p; 4088 } 4089 } 4090 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled"); 4091 if (UseHeavyMonitors) return NULL; 4092 4093 // 4094 // If we didn't find a matching Java thread and we didn't force use of 4095 // heavyweight monitors, then the owner is the stack address of the 4096 // Lock Word in the owning Java thread's stack. 4097 // 4098 JavaThread* the_owner = NULL; 4099 { 4100 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4101 ALL_JAVA_THREADS(q) { 4102 if (q->is_lock_owned(owner)) { 4103 the_owner = q; 4104 break; 4105 } 4106 } 4107 } 4108 assert(the_owner != NULL, "Did not find owning Java thread for lock word address"); 4109 return the_owner; 4110 } 4111 4112 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4113 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) { 4114 char buf[32]; 4115 st->print_cr(os::local_time_string(buf, sizeof(buf))); 4116 4117 st->print_cr("Full thread dump %s (%s %s):", 4118 Abstract_VM_Version::vm_name(), 4119 Abstract_VM_Version::vm_release(), 4120 Abstract_VM_Version::vm_info_string() 4121 ); 4122 st->cr(); 4123 4124 #ifndef SERIALGC 4125 // Dump concurrent locks 4126 ConcurrentLocksDump concurrent_locks; 4127 if (print_concurrent_locks) { 4128 concurrent_locks.dump_at_safepoint(); 4129 } 4130 #endif // SERIALGC 4131 4132 ALL_JAVA_THREADS(p) { 4133 ResourceMark rm; 4134 p->print_on(st); 4135 if (print_stacks) { 4136 if (internal_format) { 4137 p->trace_stack(); 4138 } else { 4139 p->print_stack_on(st); 4140 } 4141 } 4142 st->cr(); 4143 #ifndef SERIALGC 4144 if (print_concurrent_locks) { 4145 concurrent_locks.print_locks_on(p, st); 4146 } 4147 #endif // SERIALGC 4148 } 4149 4150 VMThread::vm_thread()->print_on(st); 4151 st->cr(); 4152 Universe::heap()->print_gc_threads_on(st); 4153 WatcherThread* wt = WatcherThread::watcher_thread(); 4154 if (wt != NULL) wt->print_on(st); 4155 st->cr(); 4156 CompileBroker::print_compiler_threads_on(st); 4157 st->flush(); 4158 } 4159 4160 // Threads::print_on_error() is called by fatal error handler. It's possible 4161 // that VM is not at safepoint and/or current thread is inside signal handler. 4162 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4163 // memory (even in resource area), it might deadlock the error handler. 4164 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) { 4165 bool found_current = false; 4166 st->print_cr("Java Threads: ( => current thread )"); 4167 ALL_JAVA_THREADS(thread) { 4168 bool is_current = (current == thread); 4169 found_current = found_current || is_current; 4170 4171 st->print("%s", is_current ? "=>" : " "); 4172 4173 st->print(PTR_FORMAT, thread); 4174 st->print(" "); 4175 thread->print_on_error(st, buf, buflen); 4176 st->cr(); 4177 } 4178 st->cr(); 4179 4180 st->print_cr("Other Threads:"); 4181 if (VMThread::vm_thread()) { 4182 bool is_current = (current == VMThread::vm_thread()); 4183 found_current = found_current || is_current; 4184 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4185 4186 st->print(PTR_FORMAT, VMThread::vm_thread()); 4187 st->print(" "); 4188 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4189 st->cr(); 4190 } 4191 WatcherThread* wt = WatcherThread::watcher_thread(); 4192 if (wt != NULL) { 4193 bool is_current = (current == wt); 4194 found_current = found_current || is_current; 4195 st->print("%s", is_current ? "=>" : " "); 4196 4197 st->print(PTR_FORMAT, wt); 4198 st->print(" "); 4199 wt->print_on_error(st, buf, buflen); 4200 st->cr(); 4201 } 4202 if (!found_current) { 4203 st->cr(); 4204 st->print("=>" PTR_FORMAT " (exited) ", current); 4205 current->print_on_error(st, buf, buflen); 4206 st->cr(); 4207 } 4208 } 4209 4210 // Internal SpinLock and Mutex 4211 // Based on ParkEvent 4212 4213 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4214 // 4215 // We employ SpinLocks _only for low-contention, fixed-length 4216 // short-duration critical sections where we're concerned 4217 // about native mutex_t or HotSpot Mutex:: latency. 4218 // The mux construct provides a spin-then-block mutual exclusion 4219 // mechanism. 4220 // 4221 // Testing has shown that contention on the ListLock guarding gFreeList 4222 // is common. If we implement ListLock as a simple SpinLock it's common 4223 // for the JVM to devolve to yielding with little progress. This is true 4224 // despite the fact that the critical sections protected by ListLock are 4225 // extremely short. 4226 // 4227 // TODO-FIXME: ListLock should be of type SpinLock. 4228 // We should make this a 1st-class type, integrated into the lock 4229 // hierarchy as leaf-locks. Critically, the SpinLock structure 4230 // should have sufficient padding to avoid false-sharing and excessive 4231 // cache-coherency traffic. 4232 4233 4234 typedef volatile int SpinLockT ; 4235 4236 void Thread::SpinAcquire (volatile int * adr, const char * LockName) { 4237 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4238 return ; // normal fast-path return 4239 } 4240 4241 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4242 TEVENT (SpinAcquire - ctx) ; 4243 int ctr = 0 ; 4244 int Yields = 0 ; 4245 for (;;) { 4246 while (*adr != 0) { 4247 ++ctr ; 4248 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4249 if (Yields > 5) { 4250 // Consider using a simple NakedSleep() instead. 4251 // Then SpinAcquire could be called by non-JVM threads 4252 Thread::current()->_ParkEvent->park(1) ; 4253 } else { 4254 os::NakedYield() ; 4255 ++Yields ; 4256 } 4257 } else { 4258 SpinPause() ; 4259 } 4260 } 4261 if (Atomic::cmpxchg (1, adr, 0) == 0) return ; 4262 } 4263 } 4264 4265 void Thread::SpinRelease (volatile int * adr) { 4266 assert (*adr != 0, "invariant") ; 4267 OrderAccess::fence() ; // guarantee at least release consistency. 4268 // Roach-motel semantics. 4269 // It's safe if subsequent LDs and STs float "up" into the critical section, 4270 // but prior LDs and STs within the critical section can't be allowed 4271 // to reorder or float past the ST that releases the lock. 4272 *adr = 0 ; 4273 } 4274 4275 // muxAcquire and muxRelease: 4276 // 4277 // * muxAcquire and muxRelease support a single-word lock-word construct. 4278 // The LSB of the word is set IFF the lock is held. 4279 // The remainder of the word points to the head of a singly-linked list 4280 // of threads blocked on the lock. 4281 // 4282 // * The current implementation of muxAcquire-muxRelease uses its own 4283 // dedicated Thread._MuxEvent instance. If we're interested in 4284 // minimizing the peak number of extant ParkEvent instances then 4285 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4286 // as certain invariants were satisfied. Specifically, care would need 4287 // to be taken with regards to consuming unpark() "permits". 4288 // A safe rule of thumb is that a thread would never call muxAcquire() 4289 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4290 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4291 // consume an unpark() permit intended for monitorenter, for instance. 4292 // One way around this would be to widen the restricted-range semaphore 4293 // implemented in park(). Another alternative would be to provide 4294 // multiple instances of the PlatformEvent() for each thread. One 4295 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4296 // 4297 // * Usage: 4298 // -- Only as leaf locks 4299 // -- for short-term locking only as muxAcquire does not perform 4300 // thread state transitions. 4301 // 4302 // Alternatives: 4303 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4304 // but with parking or spin-then-park instead of pure spinning. 4305 // * Use Taura-Oyama-Yonenzawa locks. 4306 // * It's possible to construct a 1-0 lock if we encode the lockword as 4307 // (List,LockByte). Acquire will CAS the full lockword while Release 4308 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4309 // acquiring threads use timers (ParkTimed) to detect and recover from 4310 // the stranding window. Thread/Node structures must be aligned on 256-byte 4311 // boundaries by using placement-new. 4312 // * Augment MCS with advisory back-link fields maintained with CAS(). 4313 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4314 // The validity of the backlinks must be ratified before we trust the value. 4315 // If the backlinks are invalid the exiting thread must back-track through the 4316 // the forward links, which are always trustworthy. 4317 // * Add a successor indication. The LockWord is currently encoded as 4318 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4319 // to provide the usual futile-wakeup optimization. 4320 // See RTStt for details. 4321 // * Consider schedctl.sc_nopreempt to cover the critical section. 4322 // 4323 4324 4325 typedef volatile intptr_t MutexT ; // Mux Lock-word 4326 enum MuxBits { LOCKBIT = 1 } ; 4327 4328 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) { 4329 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; 4330 if (w == 0) return ; 4331 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4332 return ; 4333 } 4334 4335 TEVENT (muxAcquire - Contention) ; 4336 ParkEvent * const Self = Thread::current()->_MuxEvent ; 4337 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ; 4338 for (;;) { 4339 int its = (os::is_MP() ? 100 : 0) + 1 ; 4340 4341 // Optional spin phase: spin-then-park strategy 4342 while (--its >= 0) { 4343 w = *Lock ; 4344 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4345 return ; 4346 } 4347 } 4348 4349 Self->reset() ; 4350 Self->OnList = intptr_t(Lock) ; 4351 // The following fence() isn't _strictly necessary as the subsequent 4352 // CAS() both serializes execution and ratifies the fetched *Lock value. 4353 OrderAccess::fence(); 4354 for (;;) { 4355 w = *Lock ; 4356 if ((w & LOCKBIT) == 0) { 4357 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4358 Self->OnList = 0 ; // hygiene - allows stronger asserts 4359 return ; 4360 } 4361 continue ; // Interference -- *Lock changed -- Just retry 4362 } 4363 assert (w & LOCKBIT, "invariant") ; 4364 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT ); 4365 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ; 4366 } 4367 4368 while (Self->OnList != 0) { 4369 Self->park() ; 4370 } 4371 } 4372 } 4373 4374 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) { 4375 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; 4376 if (w == 0) return ; 4377 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4378 return ; 4379 } 4380 4381 TEVENT (muxAcquire - Contention) ; 4382 ParkEvent * ReleaseAfter = NULL ; 4383 if (ev == NULL) { 4384 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ; 4385 } 4386 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ; 4387 for (;;) { 4388 guarantee (ev->OnList == 0, "invariant") ; 4389 int its = (os::is_MP() ? 100 : 0) + 1 ; 4390 4391 // Optional spin phase: spin-then-park strategy 4392 while (--its >= 0) { 4393 w = *Lock ; 4394 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4395 if (ReleaseAfter != NULL) { 4396 ParkEvent::Release (ReleaseAfter) ; 4397 } 4398 return ; 4399 } 4400 } 4401 4402 ev->reset() ; 4403 ev->OnList = intptr_t(Lock) ; 4404 // The following fence() isn't _strictly necessary as the subsequent 4405 // CAS() both serializes execution and ratifies the fetched *Lock value. 4406 OrderAccess::fence(); 4407 for (;;) { 4408 w = *Lock ; 4409 if ((w & LOCKBIT) == 0) { 4410 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4411 ev->OnList = 0 ; 4412 // We call ::Release while holding the outer lock, thus 4413 // artificially lengthening the critical section. 4414 // Consider deferring the ::Release() until the subsequent unlock(), 4415 // after we've dropped the outer lock. 4416 if (ReleaseAfter != NULL) { 4417 ParkEvent::Release (ReleaseAfter) ; 4418 } 4419 return ; 4420 } 4421 continue ; // Interference -- *Lock changed -- Just retry 4422 } 4423 assert (w & LOCKBIT, "invariant") ; 4424 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT ); 4425 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ; 4426 } 4427 4428 while (ev->OnList != 0) { 4429 ev->park() ; 4430 } 4431 } 4432 } 4433 4434 // Release() must extract a successor from the list and then wake that thread. 4435 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4436 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4437 // Release() would : 4438 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4439 // (B) Extract a successor from the private list "in-hand" 4440 // (C) attempt to CAS() the residual back into *Lock over null. 4441 // If there were any newly arrived threads and the CAS() would fail. 4442 // In that case Release() would detach the RATs, re-merge the list in-hand 4443 // with the RATs and repeat as needed. Alternately, Release() might 4444 // detach and extract a successor, but then pass the residual list to the wakee. 4445 // The wakee would be responsible for reattaching and remerging before it 4446 // competed for the lock. 4447 // 4448 // Both "pop" and DMR are immune from ABA corruption -- there can be 4449 // multiple concurrent pushers, but only one popper or detacher. 4450 // This implementation pops from the head of the list. This is unfair, 4451 // but tends to provide excellent throughput as hot threads remain hot. 4452 // (We wake recently run threads first). 4453 4454 void Thread::muxRelease (volatile intptr_t * Lock) { 4455 for (;;) { 4456 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ; 4457 assert (w & LOCKBIT, "invariant") ; 4458 if (w == LOCKBIT) return ; 4459 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ; 4460 assert (List != NULL, "invariant") ; 4461 assert (List->OnList == intptr_t(Lock), "invariant") ; 4462 ParkEvent * nxt = List->ListNext ; 4463 4464 // The following CAS() releases the lock and pops the head element. 4465 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4466 continue ; 4467 } 4468 List->OnList = 0 ; 4469 OrderAccess::fence() ; 4470 List->unpark () ; 4471 return ; 4472 } 4473 } 4474 4475 4476 void Threads::verify() { 4477 ALL_JAVA_THREADS(p) { 4478 p->verify(); 4479 } 4480 VMThread* thread = VMThread::vm_thread(); 4481 if (thread != NULL) thread->verify(); 4482 }