dm-master: fix DM-master can not exit when starting timeout (pingcap#513

)

dm/master/etcd.go

@@ -41,7 +41,7 @@ const (
 // startEtcd starts an embedded etcd server.
 func startEtcd(etcdCfg *embed.Config,
 	gRPCSvr func(*grpc.Server),
-	httpHandles map[string]http.Handler) (*embed.Etcd, error) {
+	httpHandles map[string]http.Handler, startTimeout time.Duration) (*embed.Etcd, error) {
 	// attach extra gRPC and HTTP server
 	if gRPCSvr != nil {
 		etcdCfg.ServiceRegister = gRPCSvr
@@ -57,10 +57,17 @@ func startEtcd(etcdCfg *embed.Config,
 
 	select {
 	case <-e.Server.ReadyNotify():
-	case <-time.After(etcdStartTimeout):
+	case <-time.After(startTimeout):
+		// if fail to startup, the etcd server may be still blocking in
+		// https://github.com/etcd-io/etcd/blob/3cf2f69b5738fb702ba1a935590f36b52b18979b/embed/serve.go#L92
+		// then `e.Close` will block in
+		// https://github.com/etcd-io/etcd/blob/3cf2f69b5738fb702ba1a935590f36b52b18979b/embed/etcd.go#L377
+		// because `close(sctx.serversC)` has not been called in
+		// https://github.com/etcd-io/etcd/blob/3cf2f69b5738fb702ba1a935590f36b52b18979b/embed/serve.go#L200.
+		// so for `ReadyNotify` timeout, we choose to only call `e.Server.Stop()` now,
+		// and we should exit the DM-master process after returned with error from this function.
 		e.Server.Stop()
-		e.Close()
-		return nil, terror.ErrMasterStartEmbedEtcdFail.Generatef("start embed etcd timeout %v", etcdStartTimeout)
+		return nil, terror.ErrMasterStartEmbedEtcdFail.Generatef("start embed etcd timeout %v", startTimeout)
 	}
 	return e, nil
 }

dm/master/etcd_test.go

@@ -40,6 +40,28 @@ func (t *testEtcdSuite) SetUpSuite(c *check.C) {
 	log.InitLogger(&log.Config{})
 }
 
+func (t *testEtcdSuite) TestStartEtcdFail(c *check.C) {
+	cfgCluster := NewConfig()
+	cfgCluster.Name = "dm-master-1"
+	cfgCluster.DataDir = c.MkDir()
+	cfgCluster.MasterAddr = tempurl.Alloc()[len("http://"):]
+	cfgCluster.PeerUrls = tempurl.Alloc()
+	c.Assert(cfgCluster.adjust(), check.IsNil)
+
+	// add another non-existing member for bootstrapping.
+	cfgCluster.InitialCluster = fmt.Sprintf("%s=%s,%s=%s",
+		cfgCluster.Name, cfgCluster.AdvertisePeerUrls,
+		"dm-master-2", tempurl.Alloc())
+	c.Assert(cfgCluster.adjust(), check.IsNil)
+
+	// start an etcd cluster
+	cfgClusterEtcd, err := cfgCluster.genEmbedEtcdConfig()
+	c.Assert(err, check.IsNil)
+	e, err := startEtcd(cfgClusterEtcd, nil, nil, 3*time.Second)
+	c.Assert(terror.ErrMasterStartEmbedEtcdFail.Equal(err), check.IsTrue)
+	c.Assert(e, check.IsNil)
+}
+
 func (t *testEtcdSuite) TestPrepareJoinEtcd(c *check.C) {
 	cfgCluster := NewConfig() // used to start an etcd cluster
 	cfgCluster.Name = "dm-master-1"
@@ -103,7 +125,7 @@ func (t *testEtcdSuite) TestPrepareJoinEtcd(c *check.C) {
 	c.Assert(os.RemoveAll(memberDP), check.IsNil) // remove previous data
 
 	// start an etcd cluster
-	e1, err := startEtcd(cfgClusterEtcd, nil, nil)
+	e1, err := startEtcd(cfgClusterEtcd, nil, nil, etcdStartTimeout)
 	c.Assert(err, check.IsNil)
 	defer e1.Close()
 
@@ -156,7 +178,7 @@ func (t *testEtcdSuite) TestPrepareJoinEtcd(c *check.C) {
 	// start the joining etcd
 	cfgAfterEtcd, err := cfgAfter.genEmbedEtcdConfig()
 	c.Assert(err, check.IsNil)
-	e2, err := startEtcd(cfgAfterEtcd, nil, nil)
+	e2, err := startEtcd(cfgAfterEtcd, nil, nil, etcdStartTimeout)
 	c.Assert(err, check.IsNil)
 	defer e2.Close()
 

dm/master/server.go

@@ -161,7 +161,7 @@ func (s *Server) Start(ctx context.Context) (err error) {
 	gRPCSvr := func(gs *grpc.Server) { pb.RegisterMasterServer(gs, s) }
 
 	// start embed etcd server, gRPC API server and HTTP (API, status and debug) server.
-	s.etcd, err = startEtcd(etcdCfg, gRPCSvr, userHandles)
+	s.etcd, err = startEtcd(etcdCfg, gRPCSvr, userHandles, etcdStartTimeout)
 	if err != nil {
 		return
 	}