jdk8-mips64-public/hotspot: src/share/vm/utilities/workgroup.cpp@c96030fff130 (annotated)

src/share/vm/utilities/workgroup.cpp@c96030fff130 (annotated)

src/share/vm/utilities/workgroup.cpp

Thu, 20 Nov 2008 16:56:09 -0800

author: ysr
date: Thu, 20 Nov 2008 16:56:09 -0800
changeset 888: c96030fff130
parent 777: 37f87013dfd8
child 1907: c18cbe5936b8
permissions: -rw-r--r--

6684579: SoftReference processing can be made more efficient
Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa

 /*
  * Copyright 2001-2007 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/_workgroup.cpp.incl"
 // Definitions of WorkGang methods.
 AbstractWorkGang::AbstractWorkGang(const char* name,
                                    bool  are_GC_task_threads,
                                    bool  are_ConcurrentGC_threads) :
   _name(name),
   _are_GC_task_threads(are_GC_task_threads),
   _are_ConcurrentGC_threads(are_ConcurrentGC_threads) {
   assert(!(are_GC_task_threads && are_ConcurrentGC_threads),
          "They cannot both be STW GC and Concurrent threads" );
   // Other initialization.
   _monitor = new Monitor(/* priority */       Mutex::leaf,
                          /* name */           "WorkGroup monitor",
                          /* allow_vm_block */ are_GC_task_threads);
   assert(monitor() != NULL, "Failed to allocate monitor");
   _terminate = false;
   _task = NULL;
   _sequence_number = 0;
   _started_workers = 0;
   _finished_workers = 0;
 }
 WorkGang::WorkGang(const char* name,
                    int         workers,
                    bool        are_GC_task_threads,
                    bool        are_ConcurrentGC_threads) :
   AbstractWorkGang(name, are_GC_task_threads, are_ConcurrentGC_threads)
 {
   // Save arguments.
   _total_workers = workers;
   if (TraceWorkGang) {
     tty->print_cr("Constructing work gang %s with %d threads", name, workers);
   }
   _gang_workers = NEW_C_HEAP_ARRAY(GangWorker*, workers);
   if (gang_workers() == NULL) {
     vm_exit_out_of_memory(0, "Cannot create GangWorker array.");
   }
   for (int worker = 0; worker < total_workers(); worker += 1) {
     GangWorker* new_worker = new GangWorker(this, worker);
     assert(new_worker != NULL, "Failed to allocate GangWorker");
     _gang_workers[worker] = new_worker;
     if (new_worker == NULL || !os::create_thread(new_worker, os::pgc_thread))
       vm_exit_out_of_memory(0, "Cannot create worker GC thread. Out of system resources.");
     if (!DisableStartThread) {
       os::start_thread(new_worker);
     }
   }
 }
 AbstractWorkGang::~AbstractWorkGang() {
   if (TraceWorkGang) {
     tty->print_cr("Destructing work gang %s", name());
   }
   stop();   // stop all the workers
   for (int worker = 0; worker < total_workers(); worker += 1) {
     delete gang_worker(worker);
   }
   delete gang_workers();
   delete monitor();
 }
 GangWorker* AbstractWorkGang::gang_worker(int i) const {
   // Array index bounds checking.
   GangWorker* result = NULL;
   assert(gang_workers() != NULL, "No workers for indexing");
   assert(((i >= 0) && (i < total_workers())), "Worker index out of bounds");
   result = _gang_workers[i];
   assert(result != NULL, "Indexing to null worker");
   return result;
 }
 void WorkGang::run_task(AbstractGangTask* task) {
   // This thread is executed by the VM thread which does not block
   // on ordinary MutexLocker's.
   MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
   if (TraceWorkGang) {
     tty->print_cr("Running work gang %s task %s", name(), task->name());
   }
   // Tell all the workers to run a task.
   assert(task != NULL, "Running a null task");
   // Initialize.
   _task = task;
   _sequence_number += 1;
   _started_workers = 0;
   _finished_workers = 0;
   // Tell the workers to get to work.
   monitor()->notify_all();
   // Wait for them to be finished
   while (finished_workers() < total_workers()) {
     if (TraceWorkGang) {
       tty->print_cr("Waiting in work gang %s: %d/%d finished sequence %d",
                     name(), finished_workers(), total_workers(),
                     _sequence_number);
     }
     monitor()->wait(/* no_safepoint_check */ true);
   }
   _task = NULL;
   if (TraceWorkGang) {
     tty->print_cr("/nFinished work gang %s: %d/%d sequence %d",
                   name(), finished_workers(), total_workers(),
                   _sequence_number);
     }
 }
 void AbstractWorkGang::stop() {
   // Tell all workers to terminate, then wait for them to become inactive.
   MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
   if (TraceWorkGang) {
     tty->print_cr("Stopping work gang %s task %s", name(), task()->name());
   }
   _task = NULL;
   _terminate = true;
   monitor()->notify_all();
   while (finished_workers() < total_workers()) {
     if (TraceWorkGang) {
       tty->print_cr("Waiting in work gang %s: %d/%d finished",
                     name(), finished_workers(), total_workers());
     }
     monitor()->wait(/* no_safepoint_check */ true);
   }
 }
 void AbstractWorkGang::internal_worker_poll(WorkData* data) const {
   assert(monitor()->owned_by_self(), "worker_poll is an internal method");
   assert(data != NULL, "worker data is null");
   data->set_terminate(terminate());
   data->set_task(task());
   data->set_sequence_number(sequence_number());
 }
 void AbstractWorkGang::internal_note_start() {
   assert(monitor()->owned_by_self(), "note_finish is an internal method");
   _started_workers += 1;
 }
 void AbstractWorkGang::internal_note_finish() {
   assert(monitor()->owned_by_self(), "note_finish is an internal method");
   _finished_workers += 1;
 }
 void AbstractWorkGang::print_worker_threads_on(outputStream* st) const {
   uint    num_thr = total_workers();
   for (uint i = 0; i < num_thr; i++) {
     gang_worker(i)->print_on(st);
     st->cr();
   }
 }
 void AbstractWorkGang::threads_do(ThreadClosure* tc) const {
   assert(tc != NULL, "Null ThreadClosure");
   uint num_thr = total_workers();
   for (uint i = 0; i < num_thr; i++) {
     tc->do_thread(gang_worker(i));
   }
 }
 // GangWorker methods.
 GangWorker::GangWorker(AbstractWorkGang* gang, uint id) {
   _gang = gang;
   set_id(id);
   set_name("Gang worker#%d (%s)", id, gang->name());
 }
 void GangWorker::run() {
   initialize();
   loop();
 }
 void GangWorker::initialize() {
   this->initialize_thread_local_storage();
   assert(_gang != NULL, "No gang to run in");
   os::set_priority(this, NearMaxPriority);
   if (TraceWorkGang) {
     tty->print_cr("Running gang worker for gang %s id %d",
                   gang()->name(), id());
   }
   // The VM thread should not execute here because MutexLocker's are used
   // as (opposed to MutexLockerEx's).
   assert(!Thread::current()->is_VM_thread(), "VM thread should not be part"
          " of a work gang");
 }
 void GangWorker::loop() {
   int previous_sequence_number = 0;
   Monitor* gang_monitor = gang()->monitor();
   for ( ; /* !terminate() */; ) {
     WorkData data;
     int part;  // Initialized below.
     {
       // Grab the gang mutex.
       MutexLocker ml(gang_monitor);
       // Wait for something to do.
       // Polling outside the while { wait } avoids missed notifies
       // in the outer loop.
       gang()->internal_worker_poll(&data);
       if (TraceWorkGang) {
         tty->print("Polled outside for work in gang %s worker %d",
                    gang()->name(), id());
         tty->print("  terminate: %s",
                    data.terminate() ? "true" : "false");
         tty->print("  sequence: %d (prev: %d)",
                    data.sequence_number(), previous_sequence_number);
         if (data.task() != NULL) {
           tty->print("  task: %s", data.task()->name());
         } else {
           tty->print("  task: NULL");
         }
         tty->cr();
       }
       for ( ; /* break or return */; ) {
         // Terminate if requested.
         if (data.terminate()) {
           gang()->internal_note_finish();
           gang_monitor->notify_all();
           return;
         }
         // Check for new work.
         if ((data.task() != NULL) &&
             (data.sequence_number() != previous_sequence_number)) {
           gang()->internal_note_start();
           gang_monitor->notify_all();
           part = gang()->started_workers() - 1;
           break;
         }
         // Nothing to do.
         gang_monitor->wait(/* no_safepoint_check */ true);
         gang()->internal_worker_poll(&data);
         if (TraceWorkGang) {
           tty->print("Polled inside for work in gang %s worker %d",
                      gang()->name(), id());
           tty->print("  terminate: %s",
                      data.terminate() ? "true" : "false");
           tty->print("  sequence: %d (prev: %d)",
                      data.sequence_number(), previous_sequence_number);
           if (data.task() != NULL) {
             tty->print("  task: %s", data.task()->name());
           } else {
             tty->print("  task: NULL");
           }
           tty->cr();
         }
       }
       // Drop gang mutex.
     }
     if (TraceWorkGang) {
       tty->print("Work for work gang %s id %d task %s part %d",
                  gang()->name(), id(), data.task()->name(), part);
     }
     assert(data.task() != NULL, "Got null task");
     data.task()->work(part);
     {
       if (TraceWorkGang) {
         tty->print("Finish for work gang %s id %d task %s part %d",
                    gang()->name(), id(), data.task()->name(), part);
       }
       // Grab the gang mutex.
       MutexLocker ml(gang_monitor);
       gang()->internal_note_finish();
       // Tell the gang you are done.
       gang_monitor->notify_all();
       // Drop the gang mutex.
     }
     previous_sequence_number = data.sequence_number();
   }
 }
 bool GangWorker::is_GC_task_thread() const {
   return gang()->are_GC_task_threads();
 }
 bool GangWorker::is_ConcurrentGC_thread() const {
   return gang()->are_ConcurrentGC_threads();
 }
 void GangWorker::print_on(outputStream* st) const {
   st->print("\"%s\" ", name());
   Thread::print_on(st);
   st->cr();
 }
 // Printing methods
 const char* AbstractWorkGang::name() const {
   return _name;
 }
 #ifndef PRODUCT
 const char* AbstractGangTask::name() const {
   return _name;
 }
 #endif /* PRODUCT */
 // *** WorkGangBarrierSync
 WorkGangBarrierSync::WorkGangBarrierSync()
   : _monitor(Mutex::safepoint, "work gang barrier sync", true),
     _n_workers(0), _n_completed(0), _should_reset(false) {
 }
 WorkGangBarrierSync::WorkGangBarrierSync(int n_workers, const char* name)
   : _monitor(Mutex::safepoint, name, true),
     _n_workers(n_workers), _n_completed(0), _should_reset(false) {
 }
 void WorkGangBarrierSync::set_n_workers(int n_workers) {
   _n_workers   = n_workers;
   _n_completed = 0;
   _should_reset = false;
 }
 void WorkGangBarrierSync::enter() {
   MutexLockerEx x(monitor(), Mutex::_no_safepoint_check_flag);
   if (should_reset()) {
     // The should_reset() was set and we are the first worker to enter
     // the sync barrier. We will zero the n_completed() count which
     // effectively resets the barrier.
     zero_completed();
     set_should_reset(false);
   }
   inc_completed();
   if (n_completed() == n_workers()) {
     // At this point we would like to reset the barrier to be ready in
     // case it is used again. However, we cannot set n_completed() to
     // 0, even after the notify_all(), given that some other workers
     // might still be waiting for n_completed() to become ==
     // n_workers(). So, if we set n_completed() to 0, those workers
     // will get stuck (as they will wake up, see that n_completed() !=
     // n_workers() and go back to sleep). Instead, we raise the
     // should_reset() flag and the barrier will be reset the first
     // time a worker enters it again.
     set_should_reset(true);
     monitor()->notify_all();
   } else {
     while (n_completed() != n_workers()) {
       monitor()->wait(/* no_safepoint_check */ true);
     }
   }
 }
 // SubTasksDone functions.
 SubTasksDone::SubTasksDone(int n) :
   _n_tasks(n), _n_threads(1), _tasks(NULL) {
   _tasks = NEW_C_HEAP_ARRAY(jint, n);
   guarantee(_tasks != NULL, "alloc failure");
   clear();
 }
 bool SubTasksDone::valid() {
   return _tasks != NULL;
 }
 void SubTasksDone::set_par_threads(int t) {
 #ifdef ASSERT
   assert(_claimed == 0 || _threads_completed == _n_threads,
          "should not be called while tasks are being processed!");
 #endif
   _n_threads = (t == 0 ? 1 : t);
 }
 void SubTasksDone::clear() {
   for (int i = 0; i < _n_tasks; i++) {
     _tasks[i] = 0;
   }
   _threads_completed = 0;
 #ifdef ASSERT
   _claimed = 0;
 #endif
 }
 bool SubTasksDone::is_task_claimed(int t) {
   assert(0 <= t && t < _n_tasks, "bad task id.");
   jint old = _tasks[t];
   if (old == 0) {
     old = Atomic::cmpxchg(1, &_tasks[t], 0);
   }
   assert(_tasks[t] == 1, "What else?");
   bool res = old != 0;
 #ifdef ASSERT
   if (!res) {
     assert(_claimed < _n_tasks, "Too many tasks claimed; missing clear?");
     Atomic::inc(&_claimed);
   }
 #endif
   return res;
 }
 void SubTasksDone::all_tasks_completed() {
   jint observed = _threads_completed;
   jint old;
   do {
     old = observed;
     observed = Atomic::cmpxchg(old+1, &_threads_completed, old);
   } while (observed != old);
   // If this was the last thread checking in, clear the tasks.
   if (observed+1 == _n_threads) clear();
 }
 SubTasksDone::~SubTasksDone() {
   if (_tasks != NULL) FREE_C_HEAP_ARRAY(jint, _tasks);
 }
 // *** SequentialSubTasksDone
 void SequentialSubTasksDone::clear() {
   _n_tasks   = _n_claimed   = 0;
   _n_threads = _n_completed = 0;
 }
 bool SequentialSubTasksDone::valid() {
   return _n_threads > 0;
 }
 bool SequentialSubTasksDone::is_task_claimed(int& t) {
   jint* n_claimed_ptr = &_n_claimed;
   t = *n_claimed_ptr;
   while (t < _n_tasks) {
     jint res = Atomic::cmpxchg(t+1, n_claimed_ptr, t);
     if (res == t) {
       return false;
     }
     t = *n_claimed_ptr;
   }
   return true;
 }
 bool SequentialSubTasksDone::all_tasks_completed() {
   jint* n_completed_ptr = &_n_completed;
   jint  complete        = *n_completed_ptr;
   while (true) {
     jint res = Atomic::cmpxchg(complete+1, n_completed_ptr, complete);
     if (res == complete) {
       break;
     }
     complete = res;
   }
   if (complete+1 == _n_threads) {
     clear();
     return true;
   }
   return false;
 }
 bool FreeIdSet::_stat_init = false;
 FreeIdSet* FreeIdSet::_sets[NSets];
 bool FreeIdSet::_safepoint;
 FreeIdSet::FreeIdSet(int sz, Monitor* mon) :
   _sz(sz), _mon(mon), _hd(0), _waiters(0), _index(-1), _claimed(0)
 {
   _ids = new int[sz];
   for (int i = 0; i < sz; i++) _ids[i] = i+1;
   _ids[sz-1] = end_of_list; // end of list.
   if (_stat_init) {
     for (int j = 0; j < NSets; j++) _sets[j] = NULL;
     _stat_init = true;
   }
   // Add to sets.  (This should happen while the system is still single-threaded.)
   for (int j = 0; j < NSets; j++) {
     if (_sets[j] == NULL) {
       _sets[j] = this;
       _index = j;
       break;
     }
   }
   guarantee(_index != -1, "Too many FreeIdSets in use!");
 }
 FreeIdSet::~FreeIdSet() {
   _sets[_index] = NULL;
 }
 void FreeIdSet::set_safepoint(bool b) {
   _safepoint = b;
   if (b) {
     for (int j = 0; j < NSets; j++) {
       if (_sets[j] != NULL && _sets[j]->_waiters > 0) {
         Monitor* mon = _sets[j]->_mon;
         mon->lock_without_safepoint_check();
         mon->notify_all();
         mon->unlock();
       }
     }
   }
 }
 #define FID_STATS 0
 int FreeIdSet::claim_par_id() {
 #if FID_STATS
   thread_t tslf = thr_self();
   tty->print("claim_par_id[%d]: sz = %d, claimed = %d\n", tslf, _sz, _claimed);
 #endif
   MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
   while (!_safepoint && _hd == end_of_list) {
     _waiters++;
 #if FID_STATS
     if (_waiters > 5) {
       tty->print("claim_par_id waiting[%d]: %d waiters, %d claimed.\n",
                  tslf, _waiters, _claimed);
     }
 #endif
     _mon->wait(Mutex::_no_safepoint_check_flag);
     _waiters--;
   }
   if (_hd == end_of_list) {
 #if FID_STATS
     tty->print("claim_par_id[%d]: returning EOL.\n", tslf);
 #endif
     return -1;
   } else {
     int res = _hd;
     _hd = _ids[res];
     _ids[res] = claimed;  // For debugging.
     _claimed++;
 #if FID_STATS
     tty->print("claim_par_id[%d]: returning %d, claimed = %d.\n",
                tslf, res, _claimed);
 #endif
     return res;
   }
 }
 bool FreeIdSet::claim_perm_id(int i) {
   assert(0 <= i && i < _sz, "Out of range.");
   MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
   int prev = end_of_list;
   int cur = _hd;
   while (cur != end_of_list) {
     if (cur == i) {
       if (prev == end_of_list) {
         _hd = _ids[cur];
       } else {
         _ids[prev] = _ids[cur];
       }
       _ids[cur] = claimed;
       _claimed++;
       return true;
     } else {
       prev = cur;
       cur = _ids[cur];
     }
   }
   return false;
 }
 void FreeIdSet::release_par_id(int id) {
   MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
   assert(_ids[id] == claimed, "Precondition.");
   _ids[id] = _hd;
   _hd = id;
   _claimed--;
 #if FID_STATS
   tty->print("[%d] release_par_id(%d), waiters =%d,  claimed = %d.\n",
              thr_self(), id, _waiters, _claimed);
 #endif
   if (_waiters > 0)
     // Notify all would be safer, but this is OK, right?
     _mon->notify_all();
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/utilities/workgroup.cpp@c96030fff130 (annotated)

src/share/vm/utilities/workgroup.cpp