Merge pull request #6189 from fuweid/followup-6166

sys/reaper/reaper_unix.go

@@ -119,23 +119,33 @@ func (m *Monitor) Wait(c *exec.Cmd, ec chan runc.Exit) (int, error) {
 
 // WaitTimeout is used to skip the blocked command and kill the left process.
 func (m *Monitor) WaitTimeout(c *exec.Cmd, ec chan runc.Exit, timeout time.Duration) (int, error) {
-	sch := make(chan int)
-	ech := make(chan error)
+	type exitStatusWrapper struct {
+		status int
+		err    error
+	}
+
+	// capacity can make sure that the following goroutine will not be
+	// blocked if there is no receiver when timeout.
+	waitCh := make(chan *exitStatusWrapper, 1)
 	go func() {
+		defer close(waitCh)
+
 		status, err := m.Wait(c, ec)
-		sch <- status
-		if err != nil {
-			ech <- err
+		waitCh <- &exitStatusWrapper{
+			status: status,
+			err:    err,
 		}
 	}()
+
+	timer := time.NewTimer(timeout)
+	defer timer.Stop()
+
 	select {
-	case <-time.After(timeout):
+	case <-timer.C:
 		syscall.Kill(c.Process.Pid, syscall.SIGKILL)
-		return 0, errors.Errorf("timeout %ds for cmd(pid=%d): %s, %s", timeout/time.Second, c.Process.Pid, c.Path, c.Args)
-	case status := <-sch:
-		return status, nil
-	case err := <-ech:
-		return -1, err
+		return 0, errors.Errorf("timeout %v for cmd(pid=%d): %s, %s", timeout, c.Process.Pid, c.Path, c.Args)
+	case res := <-waitCh:
+		return res.status, res.err
 	}
 }