bug: alleviate the data race between Release() and Reboot() (#330)

ants_test.go

@@ -503,15 +503,15 @@ func TestMaxBlockingSubmitWithFunc(t *testing.T) {
 
 func TestRebootDefaultPool(t *testing.T) {
 	defer Release()
-	Reboot()
+	Reboot() // should do nothing inside
 	var wg sync.WaitGroup
 	wg.Add(1)
 	_ = Submit(func() {
 		demoFunc()
 		wg.Done()
 	})
 	wg.Wait()
-	Release()
+	assert.NoError(t, ReleaseTimeout(time.Second))
 	assert.EqualError(t, Submit(nil), ErrPoolClosed.Error(), "pool should be closed")
 	Reboot()
 	wg.Add(1)
@@ -530,7 +530,7 @@ func TestRebootNewPool(t *testing.T) {
 		wg.Done()
 	})
 	wg.Wait()
-	p.Release()
+	assert.NoError(t, p.ReleaseTimeout(time.Second))
 	assert.EqualError(t, p.Submit(nil), ErrPoolClosed.Error(), "pool should be closed")
 	p.Reboot()
 	wg.Add(1)
@@ -546,7 +546,7 @@ func TestRebootNewPool(t *testing.T) {
 	wg.Add(1)
 	_ = p1.Invoke(1)
 	wg.Wait()
-	p1.Release()
+	assert.NoError(t, p1.ReleaseTimeout(time.Second))
 	assert.EqualError(t, p1.Invoke(nil), ErrPoolClosed.Error(), "pool should be closed")
 	p1.Reboot()
 	wg.Add(1)
@@ -975,7 +975,7 @@ func TestReleaseTimeout(t *testing.T) {
 }
 
 func TestDefaultPoolReleaseTimeout(t *testing.T) {
-	Reboot()
+	Reboot() // should do nothing inside
 	for i := 0; i < 5; i++ {
 		_ = Submit(func() {
 			time.Sleep(time.Second)

pool.go

@@ -91,9 +91,10 @@ func (p *Pool) purgeStaleWorkers() {
 		atomic.StoreInt32(&p.purgeDone, 1)
 	}()
 
+	purgeCtx := p.purgeCtx // copy to the local variable to avoid race from Reboot()
 	for {
 		select {
-		case <-p.purgeCtx.Done():
+		case <-purgeCtx.Done():
 			return
 		case <-ticker.C:
 		}
@@ -344,7 +345,10 @@ func (p *Pool) ReleaseTimeout(timeout time.Duration) error {
 	}
 }
 
-// Reboot reboots a closed pool.
+// Reboot reboots a closed pool, it does nothing if the pool is not closed.
+// If you intend to reboot a closed pool, use ReleaseTimeout() instead of
+// Release() to ensure that all workers are stopped and resource are released
+// before rebooting, otherwise you may run into data race.
 func (p *Pool) Reboot() {
 	if atomic.CompareAndSwapInt32(&p.state, CLOSED, OPENED) {
 		atomic.StoreInt32(&p.purgeDone, 0)

pool_func.go

@@ -48,9 +48,10 @@ func (p *PoolWithFunc) purgeStaleWorkers() {
 		atomic.StoreInt32(&p.purgeDone, 1)
 	}()
 
+	purgeCtx := p.purgeCtx // copy to the local variable to avoid race from Reboot()
 	for {
 		select {
-		case <-p.purgeCtx.Done():
+		case <-purgeCtx.Done():
 			return
 		case <-ticker.C:
 		}
@@ -308,7 +309,10 @@ func (p *PoolWithFunc) ReleaseTimeout(timeout time.Duration) error {
 	}
 }
 
-// Reboot reboots a closed pool.
+// Reboot reboots a closed pool, it does nothing if the pool is not closed.
+// If you intend to reboot a closed pool, use ReleaseTimeout() instead of
+// Release() to ensure that all workers are stopped and resource are released
+// before rebooting, otherwise you may run into data race.
 func (p *PoolWithFunc) Reboot() {
 	if atomic.CompareAndSwapInt32(&p.state, CLOSED, OPENED) {
 		atomic.StoreInt32(&p.purgeDone, 0)