added wating for the parent after sending 'SIGKILL' signal

Author: ssgreg

app.go

@@ -376,12 +376,24 @@ func protocolActAsChild(m *StreamMessenger, waitChildTimeout time.Duration, wait
 	return nil
 }
 
-func killParent() (int, error) {
+func killParent() (parentPID int, err error) {
+	return killProcess(os.Getppid())
+}
+
+func killProcess(pid int) (parentPID int, err error) {
 	// If it's systemd - keep it alive. Possible e.g. when systemd
 	// performs 'socket activation'.
-	parentPID := os.Getppid()
-	if parentPID == 1 {
-		return parentPID, fmt.Errorf("failed to kill parent. It's systemd")
+	if pid == 1 {
+		return pid, fmt.Errorf("failed to kill process. It's systemd")
+	}
+	p, err := os.FindProcess(pid)
+	if err != nil {
+		return
+	}
+	err = p.Signal(syscall.SIGKILL)
+	if err != nil {
+		return
 	}
-	return parentPID, syscall.Kill(parentPID, syscall.SIGKILL)
+	_, err = p.Wait()
+	return
 }

app_test.go

@@ -291,6 +291,29 @@ func TestTrippleRestartStateless(t *testing.T) {
 	require.Equal(t, 1, <-ch)
 }
 
+func TestKillParent(t *testing.T) {
+	d := newRun(t, 2608)
+	d.start(true)
+
+	_, err := killProcess(d.lastProcess().Pid)
+	require.NoError(t, err)
+	st, err := d.lastProcess().Wait()
+	assert.Nil(t, st)
+	assert.EqualValues(t, syscall.ECHILD, underlyingError(err).(syscall.Errno))
+}
+
+func underlyingError(err error) error {
+	switch err := err.(type) {
+	case *os.PathError:
+		return err.Err
+	case *os.LinkError:
+		return err.Err
+	case *os.SyscallError:
+		return err.Err
+	}
+	return err
+}
+
 //
 // A server live here.
 //