jdk8-mips64-public/hotspot: src/share/vm/runtime/vmThread.cpp@9f4457a14b58 (annotated)

src/share/vm/runtime/vmThread.cpp@9f4457a14b58 (annotated)

src/share/vm/runtime/vmThread.cpp

Wed, 09 Apr 2008 15:10:22 -0700

author: rasbold
date: Wed, 09 Apr 2008 15:10:22 -0700
changeset 544: 9f4457a14b58
parent 435: a61af66fc99e
child 1241: 821269eca479
permissions: -rw-r--r--

Merge

 /*
  * Copyright 1998-2007 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 # include "incls/_precompiled.incl"
 # include "incls/_vmThread.cpp.incl"
 // Dummy VM operation to act as first element in our circular double-linked list
 class VM_Dummy: public VM_Operation {
   VMOp_Type type() const { return VMOp_Dummy; }
   void  doit() {};
 };
 VMOperationQueue::VMOperationQueue() {
   // The queue is a circular doubled-linked list, which always contains
   // one element (i.e., one element means empty).
   for(int i = 0; i < nof_priorities; i++) {
     _queue_length[i] = 0;
     _queue_counter = 0;
     _queue[i] = new VM_Dummy();
     _queue[i]->set_next(_queue[i]);
     _queue[i]->set_prev(_queue[i]);
   }
   _drain_list = NULL;
 }
 bool VMOperationQueue::queue_empty(int prio) {
   // It is empty if there is exactly one element
   bool empty = (_queue[prio] == _queue[prio]->next());
   assert( (_queue_length[prio] == 0 && empty) ||
           (_queue_length[prio] > 0  && !empty), "sanity check");
   return _queue_length[prio] == 0;
 }
 // Inserts an element to the right of the q element
 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) {
   assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
   n->set_prev(q);
   n->set_next(q->next());
   q->next()->set_prev(n);
   q->set_next(n);
 }
 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) {
   _queue_length[prio]++;
   insert(_queue[prio]->next(), op);
 }
 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) {
   _queue_length[prio]++;
   insert(_queue[prio]->prev(), op);
 }
 void VMOperationQueue::unlink(VM_Operation* q) {
   assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
   q->prev()->set_next(q->next());
   q->next()->set_prev(q->prev());
 }
 VM_Operation* VMOperationQueue::queue_remove_front(int prio) {
   if (queue_empty(prio)) return NULL;
   assert(_queue_length[prio] >= 0, "sanity check");
   _queue_length[prio]--;
   VM_Operation* r = _queue[prio]->next();
   assert(r != _queue[prio], "cannot remove base element");
   unlink(r);
   return r;
 }
 VM_Operation* VMOperationQueue::queue_drain(int prio) {
   if (queue_empty(prio)) return NULL;
   DEBUG_ONLY(int length = _queue_length[prio];);
   assert(length >= 0, "sanity check");
   _queue_length[prio] = 0;
   VM_Operation* r = _queue[prio]->next();
   assert(r != _queue[prio], "cannot remove base element");
   // remove links to base element from head and tail
   r->set_prev(NULL);
   _queue[prio]->prev()->set_next(NULL);
   // restore queue to empty state
   _queue[prio]->set_next(_queue[prio]);
   _queue[prio]->set_prev(_queue[prio]);
   assert(queue_empty(prio), "drain corrupted queue")
 #ifdef DEBUG
   int len = 0;
   VM_Operation* cur;
   for(cur = r; cur != NULL; cur=cur->next()) len++;
   assert(len == length, "drain lost some ops");
 #endif
   return r;
 }
 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) {
   VM_Operation* cur = _queue[queue];
   cur = cur->next();
   while (cur != _queue[queue]) {
     cur->oops_do(f);
     cur = cur->next();
   }
 }
 void VMOperationQueue::drain_list_oops_do(OopClosure* f) {
   VM_Operation* cur = _drain_list;
   while (cur != NULL) {
     cur->oops_do(f);
     cur = cur->next();
   }
 }
 //-----------------------------------------------------------------
 // High-level interface
 bool VMOperationQueue::add(VM_Operation *op) {
   // Encapsulates VM queue policy. Currently, that
   // only involves putting them on the right list
   if (op->evaluate_at_safepoint()) {
     queue_add_back(SafepointPriority, op);
     return true;
   }
   queue_add_back(MediumPriority, op);
   return true;
 }
 VM_Operation* VMOperationQueue::remove_next() {
   // Assuming VMOperation queue is two-level priority queue. If there are
   // more than two priorities, we need a different scheduling algorithm.
   assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2,
          "current algorithm does not work");
   // simple counter based scheduling to prevent starvation of lower priority
   // queue. -- see 4390175
   int high_prio, low_prio;
   if (_queue_counter++ < 10) {
       high_prio = SafepointPriority;
       low_prio  = MediumPriority;
   } else {
       _queue_counter = 0;
       high_prio = MediumPriority;
       low_prio  = SafepointPriority;
   }
   return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio);
 }
 void VMOperationQueue::oops_do(OopClosure* f) {
   for(int i = 0; i < nof_priorities; i++) {
     queue_oops_do(i, f);
   }
   drain_list_oops_do(f);
 }
 //------------------------------------------------------------------------------------------------------------------
 // Implementation of VMThread stuff
 bool                VMThread::_should_terminate   = false;
 bool              VMThread::_terminated         = false;
 Monitor*          VMThread::_terminate_lock     = NULL;
 VMThread*         VMThread::_vm_thread          = NULL;
 VM_Operation*     VMThread::_cur_vm_operation   = NULL;
 VMOperationQueue* VMThread::_vm_queue           = NULL;
 PerfCounter*      VMThread::_perf_accumulated_vm_operation_time = NULL;
 void VMThread::create() {
   assert(vm_thread() == NULL, "we can only allocate one VMThread");
   _vm_thread = new VMThread();
   // Create VM operation queue
   _vm_queue = new VMOperationQueue();
   guarantee(_vm_queue != NULL, "just checking");
   _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true);
   if (UsePerfData) {
     // jvmstat performance counters
     Thread* THREAD = Thread::current();
     _perf_accumulated_vm_operation_time =
                  PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime",
                                                  PerfData::U_Ticks, CHECK);
   }
 }
 VMThread::VMThread() : Thread() {
   // nothing to do
 }
 void VMThread::destroy() {
   if (_vm_thread != NULL) {
     delete _vm_thread;
     _vm_thread = NULL;      // VM thread is gone
   }
 }
 void VMThread::run() {
   assert(this == vm_thread(), "check");
   this->initialize_thread_local_storage();
   this->record_stack_base_and_size();
   // Notify_lock wait checks on active_handles() to rewait in
   // case of spurious wakeup, it should wait on the last
   // value set prior to the notify
   this->set_active_handles(JNIHandleBlock::allocate_block());
   {
     MutexLocker ml(Notify_lock);
     Notify_lock->notify();
   }
   // Notify_lock is destroyed by Threads::create_vm()
   int prio = (VMThreadPriority == -1)
     ? os::java_to_os_priority[NearMaxPriority]
     : VMThreadPriority;
   // Note that I cannot call os::set_priority because it expects Java
   // priorities and I am *explicitly* using OS priorities so that it's
   // possible to set the VM thread priority higher than any Java thread.
   os::set_native_priority( this, prio );
   // Wait for VM_Operations until termination
   this->loop();
   // Note the intention to exit before safepointing.
   // 6295565  This has the effect of waiting for any large tty
   // outputs to finish.
   if (xtty != NULL) {
     ttyLocker ttyl;
     xtty->begin_elem("destroy_vm");
     xtty->stamp();
     xtty->end_elem();
     assert(should_terminate(), "termination flag must be set");
   }
   // 4526887 let VM thread exit at Safepoint
   SafepointSynchronize::begin();
   if (VerifyBeforeExit) {
     HandleMark hm(VMThread::vm_thread());
     // Among other things, this ensures that Eden top is correct.
     Universe::heap()->prepare_for_verify();
     os::check_heap();
     Universe::verify(true, true); // Silent verification to not polute normal output
   }
   CompileBroker::set_should_block();
   // wait for threads (compiler threads or daemon threads) in the
   // _thread_in_native state to block.
   VM_Exit::wait_for_threads_in_native_to_block();
   // signal other threads that VM process is gone
   {
     // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows
     // VM thread to enter any lock at Safepoint as long as its _owner is NULL.
     // If that happens after _terminate_lock->wait() has unset _owner
     // but before it actually drops the lock and waits, the notification below
     // may get lost and we will have a hang. To avoid this, we need to use
     // Mutex::lock_without_safepoint_check().
     MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
     _terminated = true;
     _terminate_lock->notify();
   }
   // Deletion must be done synchronously by the JNI DestroyJavaVM thread
   // so that the VMThread deletion completes before the main thread frees
   // up the CodeHeap.
 }
 // Notify the VMThread that the last non-daemon JavaThread has terminated,
 // and wait until operation is performed.
 void VMThread::wait_for_vm_thread_exit() {
   { MutexLocker mu(VMOperationQueue_lock);
     _should_terminate = true;
     VMOperationQueue_lock->notify();
   }
   // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint
   // because this thread has been removed from the threads list. But anything
   // that could get blocked by Safepoint should not be used after this point,
   // otherwise we will hang, since there is no one can end the safepoint.
   // Wait until VM thread is terminated
   // Note: it should be OK to use Terminator_lock here. But this is called
   // at a very delicate time (VM shutdown) and we are operating in non- VM
   // thread at Safepoint. It's safer to not share lock with other threads.
   { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
     while(!VMThread::is_terminated()) {
         _terminate_lock->wait(Mutex::_no_safepoint_check_flag);
     }
   }
 }
 void VMThread::print_on(outputStream* st) const {
   st->print("\"%s\" ", name());
   Thread::print_on(st);
   st->cr();
 }
 void VMThread::evaluate_operation(VM_Operation* op) {
   ResourceMark rm;
   {
     PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time());
     op->evaluate();
   }
   // Last access of info in _cur_vm_operation!
   bool c_heap_allocated = op->is_cheap_allocated();
   // Mark as completed
   if (!op->evaluate_concurrently()) {
     op->calling_thread()->increment_vm_operation_completed_count();
   }
   // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call,
   // since if it is stack allocated the calling thread might have deallocated
   if (c_heap_allocated) {
     delete _cur_vm_operation;
   }
 }
 void VMThread::loop() {
   assert(_cur_vm_operation == NULL, "no current one should be executing");
   while(true) {
     VM_Operation* safepoint_ops = NULL;
     //
     // Wait for VM operation
     //
     // use no_safepoint_check to get lock without attempting to "sneak"
     { MutexLockerEx mu_queue(VMOperationQueue_lock,
                              Mutex::_no_safepoint_check_flag);
       // Look for new operation
       assert(_cur_vm_operation == NULL, "no current one should be executing");
       _cur_vm_operation = _vm_queue->remove_next();
       // Stall time tracking code
       if (PrintVMQWaitTime && _cur_vm_operation != NULL &&
           !_cur_vm_operation->evaluate_concurrently()) {
         long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp();
         if (stall > 0)
           tty->print_cr("%s stall: %Ld",  _cur_vm_operation->name(), stall);
       }
       while (!should_terminate() && _cur_vm_operation == NULL) {
         // wait with a timeout to guarantee safepoints at regular intervals
         bool timedout =
           VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag,
                                       GuaranteedSafepointInterval);
         // Support for self destruction
         if ((SelfDestructTimer != 0) && !is_error_reported() &&
             (os::elapsedTime() > SelfDestructTimer * 60)) {
           tty->print_cr("VM self-destructed");
           exit(-1);
         }
         if (timedout && (SafepointALot ||
                          SafepointSynchronize::is_cleanup_needed())) {
           MutexUnlockerEx mul(VMOperationQueue_lock,
                               Mutex::_no_safepoint_check_flag);
           // Force a safepoint since we have not had one for at least
           // 'GuaranteedSafepointInterval' milliseconds.  This will run all
           // the clean-up processing that needs to be done regularly at a
           // safepoint
           SafepointSynchronize::begin();
           #ifdef ASSERT
             if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
           #endif
           SafepointSynchronize::end();
         }
         _cur_vm_operation = _vm_queue->remove_next();
         // If we are at a safepoint we will evaluate all the operations that
         // follow that also require a safepoint
         if (_cur_vm_operation != NULL &&
             _cur_vm_operation->evaluate_at_safepoint()) {
           safepoint_ops = _vm_queue->drain_at_safepoint_priority();
         }
       }
       if (should_terminate()) break;
     } // Release mu_queue_lock
     //
     // Execute VM operation
     //
     { HandleMark hm(VMThread::vm_thread());
       EventMark em("Executing VM operation: %s", vm_operation()->name());
       assert(_cur_vm_operation != NULL, "we should have found an operation to execute");
       // Give the VM thread an extra quantum.  Jobs tend to be bursty and this
       // helps the VM thread to finish up the job.
       // FIXME: When this is enabled and there are many threads, this can degrade
       // performance significantly.
       if( VMThreadHintNoPreempt )
         os::hint_no_preempt();
       // If we are at a safepoint we will evaluate all the operations that
       // follow that also require a safepoint
       if (_cur_vm_operation->evaluate_at_safepoint()) {
         if (PrintGCApplicationConcurrentTime) {
            gclog_or_tty->print_cr("Application time: %3.7f seconds",
                                   RuntimeService::last_application_time_sec());
         }
         _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned
         SafepointSynchronize::begin();
         evaluate_operation(_cur_vm_operation);
         // now process all queued safepoint ops, iteratively draining
         // the queue until there are none left
         do {
           _cur_vm_operation = safepoint_ops;
           if (_cur_vm_operation != NULL) {
             do {
               // evaluate_operation deletes the op object so we have
               // to grab the next op now
               VM_Operation* next = _cur_vm_operation->next();
               _vm_queue->set_drain_list(next);
               evaluate_operation(_cur_vm_operation);
               _cur_vm_operation = next;
               if (PrintSafepointStatistics) {
                 SafepointSynchronize::inc_vmop_coalesced_count();
               }
             } while (_cur_vm_operation != NULL);
           }
           // There is a chance that a thread enqueued a safepoint op
           // since we released the op-queue lock and initiated the safepoint.
           // So we drain the queue again if there is anything there, as an
           // optimization to try and reduce the number of safepoints.
           // As the safepoint synchronizes us with JavaThreads we will see
           // any enqueue made by a JavaThread, but the peek will not
           // necessarily detect a concurrent enqueue by a GC thread, but
           // that simply means the op will wait for the next major cycle of the
           // VMThread - just as it would if the GC thread lost the race for
           // the lock.
           if (_vm_queue->peek_at_safepoint_priority()) {
             // must hold lock while draining queue
             MutexLockerEx mu_queue(VMOperationQueue_lock,
                                      Mutex::_no_safepoint_check_flag);
             safepoint_ops = _vm_queue->drain_at_safepoint_priority();
           } else {
             safepoint_ops = NULL;
           }
         } while(safepoint_ops != NULL);
         _vm_queue->set_drain_list(NULL);
         // Complete safepoint synchronization
         SafepointSynchronize::end();
         if (PrintGCApplicationStoppedTime) {
           gclog_or_tty->print_cr("Total time for which application threads "
                                  "were stopped: %3.7f seconds",
                                  RuntimeService::last_safepoint_time_sec());
         }
       } else {  // not a safepoint operation
         if (TraceLongCompiles) {
           elapsedTimer t;
           t.start();
           evaluate_operation(_cur_vm_operation);
           t.stop();
           double secs = t.seconds();
           if (secs * 1e3 > LongCompileThreshold) {
             // XXX - _cur_vm_operation should not be accessed after
             // the completed count has been incremented; the waiting
             // thread may have already freed this memory.
             tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs);
           }
         } else {
           evaluate_operation(_cur_vm_operation);
         }
         _cur_vm_operation = NULL;
       }
     }
     //
     //  Notify (potential) waiting Java thread(s) - lock without safepoint
     //  check so that sneaking is not possible
     { MutexLockerEx mu(VMOperationRequest_lock,
                        Mutex::_no_safepoint_check_flag);
       VMOperationRequest_lock->notify_all();
     }
     //
     // We want to make sure that we get to a safepoint regularly.
     //
     if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) {
       long interval          = SafepointSynchronize::last_non_safepoint_interval();
       bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval);
       if (SafepointALot || max_time_exceeded) {
         HandleMark hm(VMThread::vm_thread());
         SafepointSynchronize::begin();
         SafepointSynchronize::end();
       }
     }
   }
 }
 void VMThread::execute(VM_Operation* op) {
   Thread* t = Thread::current();
   if (!t->is_VM_thread()) {
     // JavaThread or WatcherThread
     t->check_for_valid_safepoint_state(true);
     // New request from Java thread, evaluate prologue
     if (!op->doit_prologue()) {
       return;   // op was cancelled
     }
     // Setup VM_operations for execution
     op->set_calling_thread(t, Thread::get_priority(t));
     // It does not make sense to execute the epilogue, if the VM operation object is getting
     // deallocated by the VM thread.
     bool concurrent     = op->evaluate_concurrently();
     bool execute_epilog = !op->is_cheap_allocated();
     assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated");
     // Get ticket number for non-concurrent VM operations
     int ticket = 0;
     if (!concurrent) {
       ticket = t->vm_operation_ticket();
     }
     // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the
     // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests
     // to be queued up during a safepoint synchronization.
     {
       VMOperationQueue_lock->lock_without_safepoint_check();
       bool ok = _vm_queue->add(op);
       op->set_timestamp(os::javaTimeMillis());
       VMOperationQueue_lock->notify();
       VMOperationQueue_lock->unlock();
       // VM_Operation got skipped
       if (!ok) {
         assert(concurrent, "can only skip concurrent tasks");
         if (op->is_cheap_allocated()) delete op;
         return;
       }
     }
     if (!concurrent) {
       // Wait for completion of request (non-concurrent)
       // Note: only a JavaThread triggers the safepoint check when locking
       MutexLocker mu(VMOperationRequest_lock);
       while(t->vm_operation_completed_count() < ticket) {
         VMOperationRequest_lock->wait(!t->is_Java_thread());
       }
     }
     if (execute_epilog) {
       op->doit_epilogue();
     }
   } else {
     // invoked by VM thread; usually nested VM operation
     assert(t->is_VM_thread(), "must be a VM thread");
     VM_Operation* prev_vm_operation = vm_operation();
     if (prev_vm_operation != NULL) {
       // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler
       // does not allow nested scavenges or compiles.
       if (!prev_vm_operation->allow_nested_vm_operations()) {
         fatal2("Nested VM operation %s requested by operation %s", op->name(), vm_operation()->name());
       }
       op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority());
     }
     EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name());
     // Release all internal handles after operation is evaluated
     HandleMark hm(t);
     _cur_vm_operation = op;
     if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) {
       SafepointSynchronize::begin();
       op->evaluate();
       SafepointSynchronize::end();
     } else {
       op->evaluate();
     }
     // Free memory if needed
     if (op->is_cheap_allocated()) delete op;
     _cur_vm_operation = prev_vm_operation;
   }
 }
 void VMThread::oops_do(OopClosure* f) {
   Thread::oops_do(f);
   _vm_queue->oops_do(f);
 }
 //------------------------------------------------------------------------------------------------------------------
 #ifndef PRODUCT
 void VMOperationQueue::verify_queue(int prio) {
   // Check that list is correctly linked
   int length = _queue_length[prio];
   VM_Operation *cur = _queue[prio];
   int i;
   // Check forward links
   for(i = 0; i < length; i++) {
     cur = cur->next();
     assert(cur != _queue[prio], "list to short (forward)");
   }
   assert(cur->next() == _queue[prio], "list to long (forward)");
   // Check backwards links
   cur = _queue[prio];
   for(i = 0; i < length; i++) {
     cur = cur->prev();
     assert(cur != _queue[prio], "list to short (backwards)");
   }
   assert(cur->prev() == _queue[prio], "list to long (backwards)");
 }
 #endif
 void VMThread::verify() {
   oops_do(&VerifyOopClosure::verify_oop);
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/runtime/vmThread.cpp@9f4457a14b58 (annotated)

src/share/vm/runtime/vmThread.cpp