jdk8-mips64-public/hotspot: src/share/vm/utilities/workgroup.cpp@8b10f48633dc (annotated)

src/share/vm/utilities/workgroup.cpp@8b10f48633dc (annotated)

src/share/vm/utilities/workgroup.cpp

Mon, 20 Sep 2010 14:38:38 -0700

author: jmasa
date: Mon, 20 Sep 2010 14:38:38 -0700
changeset 2188: 8b10f48633dc
parent 1907: c18cbe5936b8
child 2314: f95d63e2154a
permissions: -rw-r--r--

6984287: Regularize how GC parallel workers are specified.
Summary: Associate number of GC workers with the workgang as opposed to the task.
Reviewed-by: johnc, ysr

 /*
  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.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;
 }
 GangWorker* WorkGang::allocate_worker(int which) {
   GangWorker* new_worker = new GangWorker(this, which);
   return new_worker;
 }
 // The current implementation will exit if the allocation
 // of any worker fails.  Still, return a boolean so that
 // a future implementation can possibly do a partial
 // initialization of the workers and report such to the
 // caller.
 bool WorkGang::initialize_workers() {
   if (TraceWorkGang) {
     tty->print_cr("Constructing work gang %s with %d threads",
                   name(),
                   total_workers());
   }
   _gang_workers = NEW_C_HEAP_ARRAY(GangWorker*, total_workers());
   if (gang_workers() == NULL) {
     vm_exit_out_of_memory(0, "Cannot create GangWorker array.");
     return false;
   }
   os::ThreadType worker_type;
   if (are_ConcurrentGC_threads()) {
     worker_type = os::cgc_thread;
   } else {
     worker_type = os::pgc_thread;
   }
   for (int worker = 0; worker < total_workers(); worker += 1) {
     GangWorker* new_worker = allocate_worker(worker);
     assert(new_worker != NULL, "Failed to allocate GangWorker");
     _gang_workers[worker] = new_worker;
     if (new_worker == NULL || !os::create_thread(new_worker, worker_type)) {
       vm_exit_out_of_memory(0, "Cannot create worker GC thread. Out of system resources.");
       return false;
     }
     if (!DisableStartThread) {
       os::start_thread(new_worker);
     }
   }
   return true;
 }
 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_n_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@8b10f48633dc (annotated)

src/share/vm/utilities/workgroup.cpp