void YieldingFlexibleWorkGang::wait_for_gang() {
assert(monitor()->owned_by_self(), "Data race");
// Wait for task to complete or yield
for (Status status = yielding_task()->status();
status != COMPLETED && status != YIELDED && status != ABORTED;
status = yielding_task()->status()) {
assert(started_workers() <= active_workers(), "invariant");
assert(finished_workers() <= active_workers(), "invariant");
assert(yielded_workers() <= active_workers(), "invariant");
monitor()->wait(Mutex::_no_safepoint_check_flag);
}
switch (yielding_task()->status()) {
case COMPLETED:
case ABORTED: {
assert(finished_workers() == active_workers(), "Inconsistent status");
assert(yielded_workers() == 0, "Invariant");
reset(); // for next task; gang<->task binding released
break;
}
case YIELDED: {
assert(yielded_workers() > 0, "Invariant");
assert(yielded_workers() + finished_workers() == active_workers(),
"Inconsistent counts");
break;
}
case ACTIVE:
case INACTIVE:
case COMPLETING:
case YIELDING:
case ABORTING:
default:
ShouldNotReachHere();
}
}
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() < active_workers()) {
if (TraceWorkGang) {
tty->print_cr("Waiting in work gang %s: %d/%d finished",
name(), finished_workers(), active_workers());
}
monitor()->wait(/* no_safepoint_check */ true);
}
}
/**
* 将任务交给若no_of_parallel_workers个工作线程去执行,并等待该任务被执行
*/
void WorkGang::run_task(AbstractGangTask* task, uint no_of_parallel_workers) {
task->set_for_termination(no_of_parallel_workers);
//占用锁以阻塞其它线程再提交任务
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");
//初始化本次任务
_task = task;
_sequence_number += 1; //任务编号
_started_workers = 0; //开始当前任务的线程数量
_finished_workers = 0; //完成当前任务的线程数量
//唤醒所有的工作线程
monitor()->notify_all();
//等待任务被完成
while (finished_workers() < no_of_parallel_workers) {
if (TraceWorkGang) {
tty->print_cr("Waiting in work gang %s: %d/%d finished sequence %d",
name(), finished_workers(), no_of_parallel_workers,
_sequence_number);
}
printf("%s[%d] [tid: %lu]: 当前线程开始等待...\n", __FILE__, __LINE__, pthread_self());
monitor()->wait(/* no_safepoint_check */ true);
}
_task = NULL;
if (TraceWorkGang) {
tty->print_cr("\nFinished work gang %s: %d/%d sequence %d",
name(), finished_workers(), no_of_parallel_workers,
_sequence_number);
Thread* me = Thread::current();
tty->print_cr(" T: 0x%x VM_thread: %d", me, me->is_VM_thread());
}
}
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: %d/%d 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: %d/%d sequence %d",
name(), finished_workers(), no_of_parallel_workers,
_sequence_number);
Thread* me = Thread::current();
tty->print_cr(" T: 0x%x VM_thread: %d", me, me->is_VM_thread());
}
}
void YieldingFlexibleWorkGang::yield() {
assert(task() != NULL, "Inconsistency; should have task binding");
MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
assert(yielded_workers() < active_workers(), "Consistency check");
if (yielding_task()->status() == ABORTING) {
// Do not yield; we need to abort as soon as possible
// XXX NOTE: This can cause a performance pathology in the
// current implementation in Mustang, as of today, and
// pre-Mustang in that as soon as an overflow occurs,
// yields will not be honoured. The right way to proceed
// of course is to fix bug # TBF, so that abort's cause
// us to return at each potential yield point.
return;
}
if (++_yielded_workers + finished_workers() == active_workers()) {
yielding_task()->set_status(YIELDED);
monitor()->notify_all();
} else {
yielding_task()->set_status(YIELDING);
}
while (true) {
switch (yielding_task()->status()) {
case YIELDING:
case YIELDED: {
monitor()->wait(Mutex::_no_safepoint_check_flag);
break; // from switch
}
case ACTIVE:
case ABORTING:
case COMPLETING: {
assert(_yielded_workers > 0, "Else why am i here?");
_yielded_workers--;
return;
}
case INACTIVE:
case ABORTED:
case COMPLETED:
default: {
ShouldNotReachHere();
}
}
}
// Only return is from inside switch statement above
ShouldNotReachHere();
}
