< prev index next >

src/hotspot/share/runtime/vm_operations.cpp

Print this page
rev 47862 : imported patch 10.07.open.rebase_20171110.dcubed


  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/symbolTable.hpp"
  27 #include "classfile/vmSymbols.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "compiler/compileBroker.hpp"
  30 #include "gc/shared/isGCActiveMark.hpp"
  31 #include "logging/log.hpp"
  32 #include "logging/logStream.hpp"
  33 #include "memory/heapInspection.hpp"
  34 #include "memory/resourceArea.hpp"
  35 #include "oops/symbol.hpp"
  36 #include "runtime/arguments.hpp"
  37 #include "runtime/deoptimization.hpp"
  38 #include "runtime/interfaceSupport.hpp"
  39 #include "runtime/sweeper.hpp"
  40 #include "runtime/thread.inline.hpp"

  41 #include "runtime/vm_operations.hpp"
  42 #include "services/threadService.hpp"
  43 #include "trace/tracing.hpp"
  44 
  45 #define VM_OP_NAME_INITIALIZE(name) #name,
  46 
  47 const char* VM_Operation::_names[VM_Operation::VMOp_Terminating] = \
  48   { VM_OPS_DO(VM_OP_NAME_INITIALIZE) };
  49 
  50 void VM_Operation::set_calling_thread(Thread* thread, ThreadPriority priority) {
  51   _calling_thread = thread;
  52   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
  53   _priority = priority;
  54 }
  55 
  56 
  57 void VM_Operation::evaluate() {
  58   ResourceMark rm;
  59   LogTarget(Debug, vmoperation) lt;
  60   if (lt.is_enabled()) {


  79     case _concurrent     : return "concurrent";
  80     case _async_safepoint: return "async safepoint";
  81     default              : return "unknown";
  82   }
  83 }
  84 // Called by fatal error handler.
  85 void VM_Operation::print_on_error(outputStream* st) const {
  86   st->print("VM_Operation (" PTR_FORMAT "): ", p2i(this));
  87   st->print("%s", name());
  88 
  89   const char* mode = mode_to_string(evaluation_mode());
  90   st->print(", mode: %s", mode);
  91 
  92   if (calling_thread()) {
  93     st->print(", requested by thread " PTR_FORMAT, p2i(calling_thread()));
  94   }
  95 }
  96 
  97 void VM_ThreadStop::doit() {
  98   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");

  99   JavaThread* target = java_lang_Thread::thread(target_thread());
 100   // Note that this now allows multiple ThreadDeath exceptions to be
 101   // thrown at a thread.
 102   if (target != NULL) {
 103     // the thread has run and is not already in the process of exiting
 104     target->send_thread_stop(throwable());
 105   }
 106 }
 107 
 108 void VM_ClearICs::doit() {
 109   if (_preserve_static_stubs) {
 110     CodeCache::cleanup_inline_caches();
 111   } else {
 112     CodeCache::clear_inline_caches();
 113   }
 114 }
 115 
 116 void VM_Deoptimize::doit() {
 117   // We do not want any GCs to happen while we are in the middle of this VM operation
 118   ResourceMark rm;
 119   DeoptimizationMarker dm;
 120 
 121   // Deoptimize all activations depending on marked nmethods
 122   Deoptimization::deoptimize_dependents();
 123 


 129   NMethodSweeper::mark_active_nmethods();
 130 }
 131 
 132 VM_DeoptimizeFrame::VM_DeoptimizeFrame(JavaThread* thread, intptr_t* id, int reason) {
 133   _thread = thread;
 134   _id     = id;
 135   _reason = reason;
 136 }
 137 
 138 
 139 void VM_DeoptimizeFrame::doit() {
 140   assert(_reason > Deoptimization::Reason_none && _reason < Deoptimization::Reason_LIMIT, "invalid deopt reason");
 141   Deoptimization::deoptimize_frame_internal(_thread, _id, (Deoptimization::DeoptReason)_reason);
 142 }
 143 
 144 
 145 #ifndef PRODUCT
 146 
 147 void VM_DeoptimizeAll::doit() {
 148   DeoptimizationMarker dm;

 149   // deoptimize all java threads in the system
 150   if (DeoptimizeALot) {
 151     for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
 152       if (thread->has_last_Java_frame()) {
 153         thread->deoptimize();
 154       }
 155     }
 156   } else if (DeoptimizeRandom) {
 157 
 158     // Deoptimize some selected threads and frames
 159     int tnum = os::random() & 0x3;
 160     int fnum =  os::random() & 0x3;
 161     int tcount = 0;
 162     for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
 163       if (thread->has_last_Java_frame()) {
 164         if (tcount++ == tnum)  {
 165         tcount = 0;
 166           int fcount = 0;
 167           // Deoptimize some selected frames.
 168           // Biased llocking wants a updated register map
 169           for(StackFrameStream fst(thread, UseBiasedLocking); !fst.is_done(); fst.next()) {
 170             if (fst.current()->can_be_deoptimized()) {
 171               if (fcount++ == fnum) {
 172                 fcount = 0;
 173                 Deoptimization::deoptimize(thread, *fst.current(), fst.register_map());
 174               }
 175             }
 176           }
 177         }
 178       }
 179     }
 180   }
 181 }
 182 


 242       cycle = cycle->next();
 243       delete d;
 244     }
 245   }
 246 }
 247 
 248 bool VM_FindDeadlocks::doit_prologue() {
 249   if (_concurrent_locks) {
 250     // Make sure AbstractOwnableSynchronizer is loaded
 251     JavaThread* jt = JavaThread::current();
 252     java_util_concurrent_locks_AbstractOwnableSynchronizer::initialize(jt);
 253     if (jt->has_pending_exception()) {
 254       return false;
 255     }
 256   }
 257 
 258   return true;
 259 }
 260 
 261 void VM_FindDeadlocks::doit() {
 262   _deadlocks = ThreadService::find_deadlocks_at_safepoint(_concurrent_locks);







 263   if (_out != NULL) {
 264     int num_deadlocks = 0;
 265     for (DeadlockCycle* cycle = _deadlocks; cycle != NULL; cycle = cycle->next()) {
 266       num_deadlocks++;
 267       cycle->print_on(_out);
 268     }
 269 
 270     if (num_deadlocks == 1) {
 271       _out->print_cr("\nFound 1 deadlock.\n");
 272       _out->flush();
 273     } else if (num_deadlocks > 1) {
 274       _out->print_cr("\nFound %d deadlocks.\n", num_deadlocks);
 275       _out->flush();
 276     }
 277   }
 278 }
 279 
 280 VM_ThreadDump::VM_ThreadDump(ThreadDumpResult* result,
 281                              int max_depth,
 282                              bool with_locked_monitors,
 283                              bool with_locked_synchronizers) {
 284   _result = result;
 285   _num_threads = 0; // 0 indicates all threads
 286   _threads = NULL;
 287   _result = result;


 314   }
 315 
 316   if (_with_locked_synchronizers) {
 317     // Acquire Heap_lock to dump concurrent locks
 318     Heap_lock->lock();
 319   }
 320 
 321   return true;
 322 }
 323 
 324 void VM_ThreadDump::doit_epilogue() {
 325   if (_with_locked_synchronizers) {
 326     // Release Heap_lock
 327     Heap_lock->unlock();
 328   }
 329 }
 330 
 331 void VM_ThreadDump::doit() {
 332   ResourceMark rm;
 333 






 334   ConcurrentLocksDump concurrent_locks(true);
 335   if (_with_locked_synchronizers) {
 336     concurrent_locks.dump_at_safepoint();
 337   }
 338 
 339   if (_num_threads == 0) {
 340     // Snapshot all live threads
 341     for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {


 342       if (jt->is_exiting() ||
 343           jt->is_hidden_from_external_view())  {
 344         // skip terminating threads and hidden threads
 345         continue;
 346       }
 347       ThreadConcurrentLocks* tcl = NULL;
 348       if (_with_locked_synchronizers) {
 349         tcl = concurrent_locks.thread_concurrent_locks(jt);
 350       }
 351       ThreadSnapshot* ts = snapshot_thread(jt, tcl);
 352       _result->add_thread_snapshot(ts);
 353     }
 354   } else {
 355     // Snapshot threads in the given _threads array
 356     // A dummy snapshot is created if a thread doesn't exist

 357     for (int i = 0; i < _num_threads; i++) {
 358       instanceHandle th = _threads->at(i);
 359       if (th() == NULL) {
 360         // skip if the thread doesn't exist
 361         // Add a dummy snapshot
 362         _result->add_thread_snapshot(new ThreadSnapshot());
 363         continue;
 364       }
 365 
 366       // Dump thread stack only if the thread is alive and not exiting
 367       // and not VM internal thread.
 368       JavaThread* jt = java_lang_Thread::thread(th());






 369       if (jt == NULL || /* thread not alive */
 370           jt->is_exiting() ||
 371           jt->is_hidden_from_external_view())  {
 372         // add a NULL snapshot if skipped
 373         _result->add_thread_snapshot(new ThreadSnapshot());
 374         continue;
 375       }
 376       ThreadConcurrentLocks* tcl = NULL;
 377       if (_with_locked_synchronizers) {
 378         tcl = concurrent_locks.thread_concurrent_locks(jt);
 379       }
 380       ThreadSnapshot* ts = snapshot_thread(jt, tcl);
 381       _result->add_thread_snapshot(ts);
 382     }
 383   }
 384 }
 385 
 386 ThreadSnapshot* VM_ThreadDump::snapshot_thread(JavaThread* java_thread, ThreadConcurrentLocks* tcl) {
 387   ThreadSnapshot* snapshot = new ThreadSnapshot(java_thread);
 388   snapshot->dump_stack_at_safepoint(_max_depth, _with_locked_monitors);
 389   snapshot->set_concurrent_locks(tcl);
 390   return snapshot;
 391 }
 392 
 393 volatile bool VM_Exit::_vm_exited = false;
 394 Thread * VM_Exit::_shutdown_thread = NULL;
 395 
 396 int VM_Exit::set_vm_exited() {
 397 
 398   Thread * thr_cur = Thread::current();
 399 
 400   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint already");
 401 
 402   int num_active = 0;
 403 
 404   _shutdown_thread = thr_cur;
 405   _vm_exited = true;                                // global flag
 406   for(JavaThread *thr = Threads::first(); thr != NULL; thr = thr->next())
 407     if (thr!=thr_cur && thr->thread_state() == _thread_in_native) {
 408       ++num_active;
 409       thr->set_terminated(JavaThread::_vm_exited);  // per-thread flag
 410     }

 411 
 412   return num_active;
 413 }
 414 
 415 int VM_Exit::wait_for_threads_in_native_to_block() {
 416   // VM exits at safepoint. This function must be called at the final safepoint
 417   // to wait for threads in _thread_in_native state to be quiescent.
 418   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint already");
 419 
 420   Thread * thr_cur = Thread::current();
 421   Monitor timer(Mutex::leaf, "VM_Exit timer", true,
 422                 Monitor::_safepoint_check_never);
 423 
 424   // Compiler threads need longer wait because they can access VM data directly
 425   // while in native. If they are active and some structures being used are
 426   // deleted by the shutdown sequence, they will crash. On the other hand, user
 427   // threads must go through native=>Java/VM transitions first to access VM
 428   // data, and they will be stopped during state transition. In theory, we
 429   // don't have to wait for user threads to be quiescent, but it's always
 430   // better to terminate VM when current thread is the only active thread, so
 431   // wait for user threads too. Numbers are in 10 milliseconds.
 432   int max_wait_user_thread = 30;                  // at least 300 milliseconds
 433   int max_wait_compiler_thread = 1000;            // at least 10 seconds
 434 
 435   int max_wait = max_wait_compiler_thread;
 436 
 437   int attempts = 0;

 438   while (true) {
 439     int num_active = 0;
 440     int num_active_compiler_thread = 0;
 441 
 442     for(JavaThread *thr = Threads::first(); thr != NULL; thr = thr->next()) {

 443       if (thr!=thr_cur && thr->thread_state() == _thread_in_native) {
 444         num_active++;
 445         if (thr->is_Compiler_thread()) {
 446           num_active_compiler_thread++;
 447         }
 448       }
 449     }
 450 
 451     if (num_active == 0) {
 452        return 0;
 453     } else if (attempts > max_wait) {
 454        return num_active;
 455     } else if (num_active_compiler_thread == 0 && attempts > max_wait_user_thread) {
 456        return num_active;
 457     }
 458 
 459     attempts++;
 460 
 461     MutexLockerEx ml(&timer, Mutex::_no_safepoint_check_flag);
 462     timer.wait(Mutex::_no_safepoint_check_flag, 10);




  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/symbolTable.hpp"
  27 #include "classfile/vmSymbols.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "compiler/compileBroker.hpp"
  30 #include "gc/shared/isGCActiveMark.hpp"
  31 #include "logging/log.hpp"
  32 #include "logging/logStream.hpp"
  33 #include "memory/heapInspection.hpp"
  34 #include "memory/resourceArea.hpp"
  35 #include "oops/symbol.hpp"
  36 #include "runtime/arguments.hpp"
  37 #include "runtime/deoptimization.hpp"
  38 #include "runtime/interfaceSupport.hpp"
  39 #include "runtime/sweeper.hpp"
  40 #include "runtime/thread.inline.hpp"
  41 #include "runtime/threadSMR.inline.hpp"
  42 #include "runtime/vm_operations.hpp"
  43 #include "services/threadService.hpp"
  44 #include "trace/tracing.hpp"
  45 
  46 #define VM_OP_NAME_INITIALIZE(name) #name,
  47 
  48 const char* VM_Operation::_names[VM_Operation::VMOp_Terminating] = \
  49   { VM_OPS_DO(VM_OP_NAME_INITIALIZE) };
  50 
  51 void VM_Operation::set_calling_thread(Thread* thread, ThreadPriority priority) {
  52   _calling_thread = thread;
  53   assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
  54   _priority = priority;
  55 }
  56 
  57 
  58 void VM_Operation::evaluate() {
  59   ResourceMark rm;
  60   LogTarget(Debug, vmoperation) lt;
  61   if (lt.is_enabled()) {


  80     case _concurrent     : return "concurrent";
  81     case _async_safepoint: return "async safepoint";
  82     default              : return "unknown";
  83   }
  84 }
  85 // Called by fatal error handler.
  86 void VM_Operation::print_on_error(outputStream* st) const {
  87   st->print("VM_Operation (" PTR_FORMAT "): ", p2i(this));
  88   st->print("%s", name());
  89 
  90   const char* mode = mode_to_string(evaluation_mode());
  91   st->print(", mode: %s", mode);
  92 
  93   if (calling_thread()) {
  94     st->print(", requested by thread " PTR_FORMAT, p2i(calling_thread()));
  95   }
  96 }
  97 
  98 void VM_ThreadStop::doit() {
  99   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
 100   ThreadsListHandle tlh;
 101   JavaThread* target = java_lang_Thread::thread(target_thread());
 102   // Note that this now allows multiple ThreadDeath exceptions to be
 103   // thrown at a thread.
 104   if (target != NULL && (!EnableThreadSMRExtraValidityChecks || tlh.includes(target))) {
 105     // The target thread has run and has not exited yet.
 106     target->send_thread_stop(throwable());
 107   }
 108 }
 109 
 110 void VM_ClearICs::doit() {
 111   if (_preserve_static_stubs) {
 112     CodeCache::cleanup_inline_caches();
 113   } else {
 114     CodeCache::clear_inline_caches();
 115   }
 116 }
 117 
 118 void VM_Deoptimize::doit() {
 119   // We do not want any GCs to happen while we are in the middle of this VM operation
 120   ResourceMark rm;
 121   DeoptimizationMarker dm;
 122 
 123   // Deoptimize all activations depending on marked nmethods
 124   Deoptimization::deoptimize_dependents();
 125 


 131   NMethodSweeper::mark_active_nmethods();
 132 }
 133 
 134 VM_DeoptimizeFrame::VM_DeoptimizeFrame(JavaThread* thread, intptr_t* id, int reason) {
 135   _thread = thread;
 136   _id     = id;
 137   _reason = reason;
 138 }
 139 
 140 
 141 void VM_DeoptimizeFrame::doit() {
 142   assert(_reason > Deoptimization::Reason_none && _reason < Deoptimization::Reason_LIMIT, "invalid deopt reason");
 143   Deoptimization::deoptimize_frame_internal(_thread, _id, (Deoptimization::DeoptReason)_reason);
 144 }
 145 
 146 
 147 #ifndef PRODUCT
 148 
 149 void VM_DeoptimizeAll::doit() {
 150   DeoptimizationMarker dm;
 151   JavaThreadIteratorWithHandle jtiwh;
 152   // deoptimize all java threads in the system
 153   if (DeoptimizeALot) {
 154     for (; JavaThread *thread = jtiwh.next(); ) {
 155       if (thread->has_last_Java_frame()) {
 156         thread->deoptimize();
 157       }
 158     }
 159   } else if (DeoptimizeRandom) {
 160 
 161     // Deoptimize some selected threads and frames
 162     int tnum = os::random() & 0x3;
 163     int fnum =  os::random() & 0x3;
 164     int tcount = 0;
 165     for (; JavaThread *thread = jtiwh.next(); ) {
 166       if (thread->has_last_Java_frame()) {
 167         if (tcount++ == tnum)  {
 168         tcount = 0;
 169           int fcount = 0;
 170           // Deoptimize some selected frames.
 171           // Biased llocking wants a updated register map
 172           for(StackFrameStream fst(thread, UseBiasedLocking); !fst.is_done(); fst.next()) {
 173             if (fst.current()->can_be_deoptimized()) {
 174               if (fcount++ == fnum) {
 175                 fcount = 0;
 176                 Deoptimization::deoptimize(thread, *fst.current(), fst.register_map());
 177               }
 178             }
 179           }
 180         }
 181       }
 182     }
 183   }
 184 }
 185 


 245       cycle = cycle->next();
 246       delete d;
 247     }
 248   }
 249 }
 250 
 251 bool VM_FindDeadlocks::doit_prologue() {
 252   if (_concurrent_locks) {
 253     // Make sure AbstractOwnableSynchronizer is loaded
 254     JavaThread* jt = JavaThread::current();
 255     java_util_concurrent_locks_AbstractOwnableSynchronizer::initialize(jt);
 256     if (jt->has_pending_exception()) {
 257       return false;
 258     }
 259   }
 260 
 261   return true;
 262 }
 263 
 264 void VM_FindDeadlocks::doit() {
 265   // Update the hazard ptr in the originating thread to the current
 266   // list of threads. This VM operation needs the current list of
 267   // threads for proper deadlock detection and those are the
 268   // JavaThreads we need to be protected when we return info to the
 269   // originating thread.
 270   _setter.set();
 271 
 272   _deadlocks = ThreadService::find_deadlocks_at_safepoint(_setter.list(), _concurrent_locks);
 273   if (_out != NULL) {
 274     int num_deadlocks = 0;
 275     for (DeadlockCycle* cycle = _deadlocks; cycle != NULL; cycle = cycle->next()) {
 276       num_deadlocks++;
 277       cycle->print_on_with(_setter.list(), _out);
 278     }
 279 
 280     if (num_deadlocks == 1) {
 281       _out->print_cr("\nFound 1 deadlock.\n");
 282       _out->flush();
 283     } else if (num_deadlocks > 1) {
 284       _out->print_cr("\nFound %d deadlocks.\n", num_deadlocks);
 285       _out->flush();
 286     }
 287   }
 288 }
 289 
 290 VM_ThreadDump::VM_ThreadDump(ThreadDumpResult* result,
 291                              int max_depth,
 292                              bool with_locked_monitors,
 293                              bool with_locked_synchronizers) {
 294   _result = result;
 295   _num_threads = 0; // 0 indicates all threads
 296   _threads = NULL;
 297   _result = result;


 324   }
 325 
 326   if (_with_locked_synchronizers) {
 327     // Acquire Heap_lock to dump concurrent locks
 328     Heap_lock->lock();
 329   }
 330 
 331   return true;
 332 }
 333 
 334 void VM_ThreadDump::doit_epilogue() {
 335   if (_with_locked_synchronizers) {
 336     // Release Heap_lock
 337     Heap_lock->unlock();
 338   }
 339 }
 340 
 341 void VM_ThreadDump::doit() {
 342   ResourceMark rm;
 343 
 344   // Set the hazard ptr in the originating thread to protect the
 345   // current list of threads. This VM operation needs the current list
 346   // of threads for a proper dump and those are the JavaThreads we need
 347   // to be protected when we return info to the originating thread.
 348   _result->set_t_list();
 349 
 350   ConcurrentLocksDump concurrent_locks(true);
 351   if (_with_locked_synchronizers) {
 352     concurrent_locks.dump_at_safepoint();
 353   }
 354 
 355   if (_num_threads == 0) {
 356     // Snapshot all live threads
 357 
 358     for (uint i = 0; i < _result->t_list()->length(); i++) {
 359       JavaThread* jt = _result->t_list()->thread_at(i);
 360       if (jt->is_exiting() ||
 361           jt->is_hidden_from_external_view())  {
 362         // skip terminating threads and hidden threads
 363         continue;
 364       }
 365       ThreadConcurrentLocks* tcl = NULL;
 366       if (_with_locked_synchronizers) {
 367         tcl = concurrent_locks.thread_concurrent_locks(jt);
 368       }
 369       ThreadSnapshot* ts = snapshot_thread(jt, tcl);
 370       _result->add_thread_snapshot(ts);
 371     }
 372   } else {
 373     // Snapshot threads in the given _threads array
 374     // A dummy snapshot is created if a thread doesn't exist
 375 
 376     for (int i = 0; i < _num_threads; i++) {
 377       instanceHandle th = _threads->at(i);
 378       if (th() == NULL) {
 379         // skip if the thread doesn't exist
 380         // Add a dummy snapshot
 381         _result->add_thread_snapshot(new ThreadSnapshot());
 382         continue;
 383       }
 384 
 385       // Dump thread stack only if the thread is alive and not exiting
 386       // and not VM internal thread.
 387       JavaThread* jt = java_lang_Thread::thread(th());
 388       if (jt != NULL && !_result->t_list()->includes(jt)) {
 389         // _threads[i] doesn't refer to a valid JavaThread; this check
 390         // is primarily for JVM_DumpThreads() which doesn't have a good
 391         // way to validate the _threads array.
 392         jt = NULL;
 393       }
 394       if (jt == NULL || /* thread not alive */
 395           jt->is_exiting() ||
 396           jt->is_hidden_from_external_view())  {
 397         // add a NULL snapshot if skipped
 398         _result->add_thread_snapshot(new ThreadSnapshot());
 399         continue;
 400       }
 401       ThreadConcurrentLocks* tcl = NULL;
 402       if (_with_locked_synchronizers) {
 403         tcl = concurrent_locks.thread_concurrent_locks(jt);
 404       }
 405       ThreadSnapshot* ts = snapshot_thread(jt, tcl);
 406       _result->add_thread_snapshot(ts);
 407     }
 408   }
 409 }
 410 
 411 ThreadSnapshot* VM_ThreadDump::snapshot_thread(JavaThread* java_thread, ThreadConcurrentLocks* tcl) {
 412   ThreadSnapshot* snapshot = new ThreadSnapshot(_result->t_list(), java_thread);
 413   snapshot->dump_stack_at_safepoint(_max_depth, _with_locked_monitors);
 414   snapshot->set_concurrent_locks(tcl);
 415   return snapshot;
 416 }
 417 
 418 volatile bool VM_Exit::_vm_exited = false;
 419 Thread * VM_Exit::_shutdown_thread = NULL;
 420 
 421 int VM_Exit::set_vm_exited() {
 422 
 423   Thread * thr_cur = Thread::current();
 424 
 425   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint already");
 426 
 427   int num_active = 0;
 428 
 429   _shutdown_thread = thr_cur;
 430   _vm_exited = true;                                // global flag
 431   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thr = jtiwh.next(); ) {
 432     if (thr!=thr_cur && thr->thread_state() == _thread_in_native) {
 433       ++num_active;
 434       thr->set_terminated(JavaThread::_vm_exited);  // per-thread flag
 435     }
 436   }
 437 
 438   return num_active;
 439 }
 440 
 441 int VM_Exit::wait_for_threads_in_native_to_block() {
 442   // VM exits at safepoint. This function must be called at the final safepoint
 443   // to wait for threads in _thread_in_native state to be quiescent.
 444   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint already");
 445 
 446   Thread * thr_cur = Thread::current();
 447   Monitor timer(Mutex::leaf, "VM_Exit timer", true,
 448                 Monitor::_safepoint_check_never);
 449 
 450   // Compiler threads need longer wait because they can access VM data directly
 451   // while in native. If they are active and some structures being used are
 452   // deleted by the shutdown sequence, they will crash. On the other hand, user
 453   // threads must go through native=>Java/VM transitions first to access VM
 454   // data, and they will be stopped during state transition. In theory, we
 455   // don't have to wait for user threads to be quiescent, but it's always
 456   // better to terminate VM when current thread is the only active thread, so
 457   // wait for user threads too. Numbers are in 10 milliseconds.
 458   int max_wait_user_thread = 30;                  // at least 300 milliseconds
 459   int max_wait_compiler_thread = 1000;            // at least 10 seconds
 460 
 461   int max_wait = max_wait_compiler_thread;
 462 
 463   int attempts = 0;
 464   JavaThreadIteratorWithHandle jtiwh;
 465   while (true) {
 466     int num_active = 0;
 467     int num_active_compiler_thread = 0;
 468 
 469     jtiwh.rewind();
 470     for (; JavaThread *thr = jtiwh.next(); ) {
 471       if (thr!=thr_cur && thr->thread_state() == _thread_in_native) {
 472         num_active++;
 473         if (thr->is_Compiler_thread()) {
 474           num_active_compiler_thread++;
 475         }
 476       }
 477     }
 478 
 479     if (num_active == 0) {
 480        return 0;
 481     } else if (attempts > max_wait) {
 482        return num_active;
 483     } else if (num_active_compiler_thread == 0 && attempts > max_wait_user_thread) {
 484        return num_active;
 485     }
 486 
 487     attempts++;
 488 
 489     MutexLockerEx ml(&timer, Mutex::_no_safepoint_check_flag);
 490     timer.wait(Mutex::_no_safepoint_check_flag, 10);


< prev index next >