gRPC Deadlines

May 3, 2021

Deadlines allow gRPC lcients to specify how long they ar willing to wait for and RPC to complete before the RPC is terminated with error DEADLINE_EXCEEDED. The gRPC documentation recommends you set a deadline for all client RPC calls. Setting the deadline is up to you: how long do you feel your API should have to complete?

The server should check if the deadline has exceeded and cancel the work it is doing.

Note: Deadlines are propagated accross if gRPC calls are chained

• A => B => C (deadline for A is passed to B and thend passed to C)

Server

for i := 0; i < 3; i ++ {
	if ctx.Err() == context.Canceled {
		// the client canceled the request
		fmt.Println("The client canceled the request!")
		return nil, status.Error(codes.Canceled, "The client canceled the request")
	}
	time.Sleep(1* time.Second)
}

Client

ctx, cancel := context.WithTimeout(context.Background(), timeout)
defer cancel()

res, err := c.HelloWithDeadline(ctx, req)
if err != nil {
	statusErr, ok := status.FromError(err)
	if ok {
		if statusErr.Code() == codes.DeadlineExceeded {
			fmt.Println("Timeout was hit! Deadline was exceeded")
		} else {
			fmt.Printf("Unexpected error: %v", statusErr)
		}
	} else {
		log.Fatalf("Error while calling Hello RPC: %v", err)
	}
	return
}
log.Printf("Response from Hello: %v", res.Result)

Console

❯ go run hello/hello_server/server.go
Hello server
HelloWithDeadline function was invoked with hello:{first_name:"Younghyun" last_name:"Ahn"}
HelloWithDeadline function was invoked with hello:{first_name:"Younghyun" last_name:"Ahn"}

❯ go run hello/hello_client/client.go
Hello client
2021/05/03 22:46:56 Response from Hello: Hello Younghyun
Timeout was hit! Deadline was exceeded

Check out the gRPC and Deadlines for more info.