recycle timer.

watchdog.go

@@ -267,9 +267,19 @@ func SystemDriven(limit uint64, frequency time.Duration, policyCtor PolicyCtor)
 		// initialize the threshold.
 		renewThreshold()
 
+		// initialize an empty timer.
+		timer := Clock.Timer(0)
+		stopTimer := func() {
+			if !timer.Stop() {
+				<-timer.C
+			}
+		}
+
 		for {
+			timer.Reset(frequency)
+
 			select {
-			case <-Clock.After(frequency):
+			case <-timer.C:
 				// get the current usage.
 				if err := sysmemFn(&sysmem); err != nil {
 					Logger.Warnf("failed to obtain system memory stats; err: %s", err)
@@ -290,7 +300,10 @@ func SystemDriven(limit uint64, frequency time.Duration, policyCtor PolicyCtor)
 
 				renewThreshold()
 
+				stopTimer()
+
 			case <-_watchdog.closing:
+				stopTimer()
 				return
 			}
 		}

watchdog_test.go

@@ -52,7 +52,7 @@ func TestControl(t *testing.T) {
 
 	var ms runtime.MemStats
 	runtime.ReadMemStats(&ms)
-	require.LessOrEqual(t, ms.NumGC, uint32(8)) // a maximum of 8 GCs should've happened.
+	require.LessOrEqual(t, ms.NumGC, uint32(5)) // a maximum of 8 GCs should've happened.
 	require.Zero(t, ms.NumForcedGC)             // no forced GCs.
 }
 
@@ -91,7 +91,7 @@ func TestHeapDriven(t *testing.T) {
 
 	var ms runtime.MemStats
 	runtime.ReadMemStats(&ms)
-	require.GreaterOrEqual(t, ms.NumGC, uint32(10)) // over 12 GCs should've taken place.
+	require.GreaterOrEqual(t, ms.NumGC, uint32(9)) // over 9 GCs should've taken place.
 }
 
 func TestSystemDriven(t *testing.T) {