ART: Change ThreadPool::Wait behavior
When a pool is in the stopped state, Wait() will not wait for all
tasks to complete.
Bug: 31385354
Test: m test-art-host-gtest-thread_pool_test
Change-Id: Id0144b685ee2fddf1a1c2c2ca334251130121033
diff --git a/runtime/thread_pool.cc b/runtime/thread_pool.cc
index b14f340..65fd999 100644
--- a/runtime/thread_pool.cc
+++ b/runtime/thread_pool.cc
@@ -177,7 +177,7 @@
}
++waiting_count_;
- if (waiting_count_ == GetThreadCount() && tasks_.empty()) {
+ if (waiting_count_ == GetThreadCount() && !HasOutstandingTasks()) {
// We may be done, lets broadcast to the completion condition.
completion_condition_.Broadcast(self);
}
@@ -200,7 +200,7 @@
}
Task* ThreadPool::TryGetTaskLocked() {
- if (started_ && !tasks_.empty()) {
+ if (HasOutstandingTasks()) {
Task* task = tasks_.front();
tasks_.pop_front();
return task;
@@ -218,7 +218,7 @@
}
// Wait until each thread is waiting and the task list is empty.
MutexLock mu(self, task_queue_lock_);
- while (!shutting_down_ && (waiting_count_ != GetThreadCount() || !tasks_.empty())) {
+ while (!shutting_down_ && (waiting_count_ != GetThreadCount() || HasOutstandingTasks())) {
if (!may_hold_locks) {
completion_condition_.Wait(self);
} else {
diff --git a/runtime/thread_pool.h b/runtime/thread_pool.h
index b6c6f02..2ff33a6 100644
--- a/runtime/thread_pool.h
+++ b/runtime/thread_pool.h
@@ -100,7 +100,8 @@
ThreadPool(const char* name, size_t num_threads);
virtual ~ThreadPool();
- // Wait for all tasks currently on queue to get completed.
+ // Wait for all tasks currently on queue to get completed. If the pool has been stopped, only
+ // wait till all already running tasks are done.
void Wait(Thread* self, bool do_work, bool may_hold_locks) REQUIRES(!task_queue_lock_);
size_t GetTaskCount(Thread* self) REQUIRES(!task_queue_lock_);
@@ -130,6 +131,10 @@
return shutting_down_;
}
+ bool HasOutstandingTasks() const REQUIRES(task_queue_lock_) {
+ return started_ && !tasks_.empty();
+ }
+
const std::string name_;
Mutex task_queue_lock_;
ConditionVariable task_queue_condition_ GUARDED_BY(task_queue_lock_);
diff --git a/runtime/thread_pool_test.cc b/runtime/thread_pool_test.cc
index d5f17d1..2ae2ecf 100644
--- a/runtime/thread_pool_test.cc
+++ b/runtime/thread_pool_test.cc
@@ -98,6 +98,24 @@
thread_pool.Wait(self, false, false);
}
+TEST_F(ThreadPoolTest, StopWait) {
+ Thread* self = Thread::Current();
+ ThreadPool thread_pool("Thread pool test thread pool", num_threads);
+
+ AtomicInteger count(0);
+ static const int32_t num_tasks = num_threads * 100;
+ for (int32_t i = 0; i < num_tasks; ++i) {
+ thread_pool.AddTask(self, new CountTask(&count));
+ }
+
+ // Signal the threads to start processing tasks.
+ thread_pool.StartWorkers(self);
+ usleep(200);
+ thread_pool.StopWorkers(self);
+
+ thread_pool.Wait(self, false, false); // We should not deadlock here.
+}
+
class TreeTask : public Task {
public:
TreeTask(ThreadPool* const thread_pool, AtomicInteger* count, int depth)