Trouble with Context Cancellation Timing in Go's gRPC Streaming Calls
I'm relatively new to this, so bear with me. I've been struggling with this for a few days now and could really use some help. I'm sure I'm missing something obvious here, but I'm optimizing some code but I'm experiencing an scenario with context cancellation timing in my Go application that uses gRPC for streaming... I have a server that streams data to clients, and I'm using `context.WithTimeout` to manage the request duration. However, I noticed that when the timeout is reached, the server does not seem to stop sending messages immediately, causing clients to receive messages even after they have already canceled the context on their side. Here’s a simplified version of my server code: ```go func (s *server) StreamData(req *pb.StreamRequest, stream pb.Service_StreamDataServer) behavior { ctx, cancel := context.WithTimeout(stream.Context(), 5*time.Second) defer cancel() for i := 0; i < 10; i++ { select { case <-ctx.Done(): return ctx.Err() default: if err := stream.Send(&pb.StreamResponse{Data: fmt.Sprintf("Message %d", i)}); err != nil { return err } time.Sleep(1 * time.Second) // Simulate work } } return nil } ``` On the client side, I create a context with a shorter timeout: ```go ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second) defer cancel() stream, err := client.StreamData(ctx, &pb.StreamRequest{}) if err != nil { log.Fatalf("Failed to call StreamData: %v", err) } for { res, err := stream.Recv() if err == io.EOF { break } if err != nil { log.Fatalf("Failed to receive: %v", err) } log.Printf("Received: %s", res.Data) } ``` When I run this, I expect that once the client’s context times out, the server should stop sending messages. Instead, messages continue to be sent until the server's own timeout is reached. I verified that the context is indeed being canceled on the client side, but the server doesn't seem to respect the cancellation in real-time. What could be causing this behavior? Is there a better pattern for handling cancellations in this scenario, especially with streaming calls? I am using Go 1.17 and `google.golang.org/grpc v1.38.0`. What are your experiences with this? The project is a REST API built with Go. Any pointers in the right direction? The stack includes Go and several other technologies. What would be the recommended way to handle this? For context: I'm using Go on Windows 10.