Method TestEnterIdleDuringResolverUpdateState

resolver_balancer_ext_test.go:173–214

TestEnterIdleDuringResolverUpdateState tests a scenario that used to deadlock while calling UpdateState at the same time as the resolver being closed while the channel enters idle mode.

(t *testing.T)

// while calling UpdateState at the same time as the resolver being closed while
// the channel enters idle mode.
func (s) TestEnterIdleDuringResolverUpdateState(t *testing.T) {
	enterIdle := internal.EnterIdleModeForTesting.(func(*grpc.ClientConn))
	name := strings.ReplaceAll(strings.ToLower(t.Name()), "/", "")

	// Create a manual resolver that spams UpdateState calls until it is closed.
	rb := manual.NewBuilderWithScheme(name)
	var cancel context.CancelFunc
	rb.BuildCallback = func(_ resolver.Target, cc resolver.ClientConn, _ resolver.BuildOptions) {
		var ctx context.Context
		ctx, cancel = context.WithCancel(context.Background())
		go func() {
			for ctx.Err() == nil {
				cc.UpdateState(resolver.State{Addresses: []resolver.Address{{Addr: "test"}}})
			}
		}()
	}
	rb.CloseCallback = func() {
		cancel()
	}
	resolver.Register(rb)

	cc, err := grpc.NewClient(name+":///", grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		t.Fatalf("grpc.NewClient error: %v", err)
	}
	defer cc.Close()

	// Enter/exit idle mode repeatedly.
	for i := 0; i < 2000; i++ {
		// Start a timer so we panic out of the deadlock and can see all the
		// stack traces to debug the problem.
		p := time.AfterFunc(time.Second, func() {
			buf := make([]byte, 8192)
			buf = buf[0:runtime.Stack(buf, true)]
			t.Error("Timed out waiting for enterIdle")
			panic(fmt.Sprint("Stack trace:\n", string(buf)))
		})
		enterIdle(cc)
		p.Stop()
		cc.Connect()
	}
}

// TestEnterIdleDuringBalancerUpdateState tests calling UpdateState at the same
// time as the balancer being closed while the channel enters idle mode.