--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/shared/workgroup.cpp Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,655 @@
+/*
+ * Copyright (c) 2001, 2015, 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 "precompiled.hpp"
+#include "gc/shared/workgroup.hpp"
+#include "memory/allocation.hpp"
+#include "memory/allocation.inline.hpp"
+#include "runtime/atomic.inline.hpp"
+#include "runtime/os.hpp"
+
+// 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,
+ Monitor::_safepoint_check_sometimes);
+ 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,
+ uint workers,
+ bool are_GC_task_threads,
+ bool are_ConcurrentGC_threads) :
+ AbstractWorkGang(name, are_GC_task_threads, are_ConcurrentGC_threads) {
+ _total_workers = workers;
+}
+
+GangWorker* WorkGang::allocate_worker(uint 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(), mtInternal);
+ if (gang_workers() == NULL) {
+ vm_exit_out_of_memory(0, OOM_MALLOC_ERROR, "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 (uint 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, OOM_MALLOC_ERROR,
+ "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 (uint worker = 0; worker < total_workers(); worker += 1) {
+ delete gang_worker(worker);
+ }
+ delete gang_workers();
+ delete monitor();
+}
+
+GangWorker* AbstractWorkGang::gang_worker(uint i) const {
+ // Array index bounds checking.
+ GangWorker* result = NULL;
+ assert(gang_workers() != NULL, "No workers for indexing");
+ assert(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) {
+ run_task(task, total_workers());
+}
+
+void WorkGang::run_task(AbstractGangTask* task, uint no_of_parallel_workers) {
+ task->set_for_termination(no_of_parallel_workers);
+
+ // 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() < no_of_parallel_workers) {
+ if (TraceWorkGang) {
+ tty->print_cr("Waiting in work gang %s: %u/%u finished sequence %d",
+ name(), finished_workers(), no_of_parallel_workers,
+ _sequence_number);
+ }
+ monitor()->wait(/* no_safepoint_check */ true);
+ }
+ _task = NULL;
+ if (TraceWorkGang) {
+ tty->print_cr("\nFinished work gang %s: %u/%u sequence %d",
+ name(), finished_workers(), no_of_parallel_workers,
+ _sequence_number);
+ Thread* me = Thread::current();
+ tty->print_cr(" T: " PTR_FORMAT " VM_thread: %d", p2i(me), me->is_VM_thread());
+ }
+}
+
+void FlexibleWorkGang::run_task(AbstractGangTask* task) {
+ // If active_workers() is passed, _finished_workers
+ // must only be incremented for workers that find non_null
+ // work (as opposed to all those that just check that the
+ // task is not null).
+ WorkGang::run_task(task, (uint) active_workers());
+}
+
+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() < active_workers()) {
+ if (TraceWorkGang) {
+ tty->print_cr("Waiting in work gang %s: %u/%u finished",
+ name(), finished_workers(), active_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("%s#%d", gang->name(), id);
+}
+
+void GangWorker::run() {
+ initialize();
+ loop();
+}
+
+void GangWorker::initialize() {
+ this->initialize_thread_local_storage();
+ this->record_stack_base_and_size();
+ this->initialize_named_thread();
+ 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 %u",
+ 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 %u",
+ 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)) {
+ if (gang()->needs_more_workers()) {
+ 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 %u",
+ 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 %u 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 %u 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 */
+
+// FlexibleWorkGang
+
+
+// *** WorkGangBarrierSync
+
+WorkGangBarrierSync::WorkGangBarrierSync()
+ : _monitor(Mutex::safepoint, "work gang barrier sync", true,
+ Monitor::_safepoint_check_never),
+ _n_workers(0), _n_completed(0), _should_reset(false), _aborted(false) {
+}
+
+WorkGangBarrierSync::WorkGangBarrierSync(uint n_workers, const char* name)
+ : _monitor(Mutex::safepoint, name, true, Monitor::_safepoint_check_never),
+ _n_workers(n_workers), _n_completed(0), _should_reset(false), _aborted(false) {
+}
+
+void WorkGangBarrierSync::set_n_workers(uint n_workers) {
+ _n_workers = n_workers;
+ _n_completed = 0;
+ _should_reset = false;
+ _aborted = false;
+}
+
+bool 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() && !aborted()) {
+ monitor()->wait(/* no_safepoint_check */ true);
+ }
+ }
+ return !aborted();
+}
+
+void WorkGangBarrierSync::abort() {
+ MutexLockerEx x(monitor(), Mutex::_no_safepoint_check_flag);
+ set_aborted();
+ monitor()->notify_all();
+}
+
+// SubTasksDone functions.
+
+SubTasksDone::SubTasksDone(uint n) :
+ _n_tasks(n), _n_threads(1), _tasks(NULL) {
+ _tasks = NEW_C_HEAP_ARRAY(uint, n, mtInternal);
+ guarantee(_tasks != NULL, "alloc failure");
+ clear();
+}
+
+bool SubTasksDone::valid() {
+ return _tasks != NULL;
+}
+
+void SubTasksDone::set_n_threads(uint t) {
+ assert(_claimed == 0 || _threads_completed == _n_threads,
+ "should not be called while tasks are being processed!");
+ _n_threads = (t == 0 ? 1 : t);
+}
+
+void SubTasksDone::clear() {
+ for (uint i = 0; i < _n_tasks; i++) {
+ _tasks[i] = 0;
+ }
+ _threads_completed = 0;
+#ifdef ASSERT
+ _claimed = 0;
+#endif
+}
+
+bool SubTasksDone::is_task_claimed(uint t) {
+ assert(t < _n_tasks, "bad task id.");
+ uint 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((volatile jint*) &_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 == (jint)_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(uint& t) {
+ uint* 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 == (jint)t) {
+ return false;
+ }
+ t = *n_claimed_ptr;
+ }
+ return true;
+}
+
+bool SequentialSubTasksDone::all_tasks_completed() {
+ uint* n_completed_ptr = &_n_completed;
+ uint complete = *n_completed_ptr;
+ while (true) {
+ uint 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_C_HEAP_ARRAY(int, sz, mtInternal);
+ 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;
+ FREE_C_HEAP_ARRAY(int, _ids);
+}
+
+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();
+}