Скачать или смотреть Solving the CANCELLED: io.grpc.Context was cancelled without error Issue in gRPC Clients

Discover how to resolve the "CANCELLED: io.grpc.Context was cancelled without error" error in gRPC clients when switching from blocking to asynchronous calls.
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Solving the CANCELLED: io.grpc.Context was cancelled without error Issue in gRPC Clients

When working with gRPC, it’s not uncommon to encounter challenges while transitioning between different methods of communication. One common issue developers face is the CANCELLED: io.grpc.Context was cancelled without error error message. This can be particularly perplexing when everything appears to function correctly in a blocking stub but fails after switching to an asynchronous stub. In this guide, we'll dissect this issue and provide a clear solution to help you navigate through it.

The Scenario

A developer had a gRPC server implemented in C+ + , working seamlessly with a Java client using a blocking stub. The developer decided to switch to asynchronous calls to improve performance. Here’s a brief outline of what they did:

Original Call: Used a blocking stub for a unary RPC call.

[[See Video to Reveal this Text or Code Snippet]]

Changed to Async Call: Switched to an asynchronous stub for the same rpc call.

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Despite making these changes, the developer encountered an error response invoking onError with the message "CANCELLED: io.grpc.Context was cancelled without error" most of the time.

The Investigation

The developer delved into the issue, realizing some key points:

The context used by gRPC is indeed applicable on the client-side as well.

They suspected it might be a server-side error, yet everything seemed fine from that end.

An interesting observation was made: placing a brief sleep after the async call temporarily alleviated the problem.

This led to the key realization: context management was impacting the client-side behavior.

The Solution

The solution revolved around managing the gRPC context effectively when making asynchronous calls. Specifically, the developer needed to fork a new context to ensure it remained alive throughout the async call’s execution. Here's how to implement it:

[[See Video to Reveal this Text or Code Snippet]]

Why This Works

By forking a new context, the gRPC client can ensure that the context remains available during the asynchronous operation. The original context is temporarily attached, ensuring that any resources or state tied to it remain intact. Once the async call completes, detaching the context helps maintain the client’s stability for subsequent calls.

Key Takeaways

Changing from a blocking to an asynchronous call can cause context issues due to the lifecycle of the context in gRPC.

Always fork a new context for asynchronous operations to avoid unexpected cancellations and errors.

Context management is essential when dealing with concurrency in gRPC calls.

Conclusion

Hopefully, this explanation sheds light on the CANCELLED: io.grpc.Context was cancelled without error error and provides a useful resolution for anyone facing a similar challenge when working with gRPC in Java. If you're transitioning from blocking to async calls, remember to manage your context thoughtfully. This small change can make a significant difference in your application's efficiency and robustness.

If you have any further questions or would like to share your experiences with gRPC, feel free to comment below!