Merge pull request #7240 from fanminshi/balancer_fix

clientv3: fix balancer update address bug

clientv3/balancer.go

@@ -124,7 +124,11 @@ func (b *simpleBalancer) updateAddrs(eps []string) {
 		addrs = append(addrs, grpc.Address{Addr: getHost(eps[i])})
 	}
 	b.addrs = addrs
-	b.notifyCh <- addrs
+	// updating notifyCh can trigger new connections,
+	// but balancer only expects new connections if all connections are down
+	if b.pinAddr == "" {
+		b.notifyCh <- addrs
+	}
 }
 
 func (b *simpleBalancer) Up(addr grpc.Address) func(error) {
@@ -220,7 +224,7 @@ func (b *simpleBalancer) Close() error {
 	close(b.notifyCh)
 	b.pinAddr = ""
 
-	// In the case of follwing scenerio:
+	// In the case of following scenario:
 	//	1. upc is not closed; no pinned address
 	// 	2. client issues an rpc, calling invoke(), which calls Get(), enters for loop, blocks
 	// 	3. clientconn.Close() calls balancer.Close(); closed = true

clientv3/integration/dial_test.go

@@ -26,7 +26,16 @@ import (
 )
 
 // TestDialSetEndpoints ensures SetEndpoints can replace unavailable endpoints with available ones.
-func TestDialSetEndpoints(t *testing.T) {
+func TestDialSetEndpointsBeforeFail(t *testing.T) {
+	testDialSetEndpoints(t, true)
+}
+
+func TestDialSetEndpointsAfterFail(t *testing.T) {
+	testDialSetEndpoints(t, false)
+}
+
+// testDialSetEndpoints ensures SetEndpoints can replace unavailable endpoints with available ones.
+func testDialSetEndpoints(t *testing.T, setBefore bool) {
 	defer testutil.AfterTest(t)
 	clus := integration.NewClusterV3(t, &integration.ClusterConfig{Size: 3})
 	defer clus.Terminate(t)
@@ -45,13 +54,16 @@ func TestDialSetEndpoints(t *testing.T) {
 	}
 	defer cli.Close()
 
+	if setBefore {
+		cli.SetEndpoints(eps[toKill%3], eps[(toKill+1)%3])
+	}
 	// make a dead node
 	clus.Members[toKill].Stop(t)
 	clus.WaitLeader(t)
 
-	// update client with available endpoints
-	cli.SetEndpoints(eps[(toKill+1)%3])
-
+	if !setBefore {
+		cli.SetEndpoints(eps[toKill%3], eps[(toKill+1)%3])
+	}
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
 	if _, err = cli.Get(ctx, "foo", clientv3.WithSerializable()); err != nil {
 		t.Fatal(err)