Improving Debugging With Clear Timeout Stack Traces In Ts-retry-promise

Hey everyone! Let's dive into a crucial discussion about improving the debugging experience with ts-retry-promise, particularly when dealing with timeouts. As developers, we know how frustrating it can be when timeout errors don't provide enough context to pinpoint the issue. So, let’s break down the problem, explore a potential solution, and discuss how we can make this awesome library even better.

The Issue: Obscure Timeout Stack Traces

When you're using a library like ts-retry-promise, timeouts are a common way to handle potentially failing operations. You might have a piece of code that looks something like this:

import { retry } from "ts-retry-promise";

async function main() {
    await retry(
        async () => {
            await delay(1000);
            throw new Error("request was unsuccessful");
        },
        {
            retries: "INFINITELY",
            timeout: 5000,
        }
    );
}

main();

In this example, we're using retry to attempt an operation that might fail. We've set a timeout of 5000ms, meaning if the operation doesn't complete within that time, we expect a timeout error. However, the current implementation of ts-retry-promise can lead to stack traces that aren't as helpful as they could be. Imagine you get an error like this:

Error: Timeout after 5000ms
      at Timeout._onTimeout (/node_modules/ts-retry-promise/src/timeout.ts:14:20)
      at listOnTimeout (node:internal/timers:594:17)
      at process.processTimers (node:internal/timers:529:7)

See the problem? The stack trace points to the internals of ts-retry-promise and Node.js timers, but it doesn't tell you where in your application the timeout actually occurred. This can be super frustrating when you're trying to debug a complex application with multiple retry operations. You're left scratching your head, wondering which part of your code is timing out. This lack of context makes debugging significantly harder.

Why This Matters

Debugging is a crucial part of software development, and clear, informative error messages are essential for efficient troubleshooting. When a timeout occurs, you need to know exactly where it happened in your code so you can quickly identify the problematic operation. Obscure stack traces force you to spend more time tracing the issue, slowing down your development process. Improving the clarity of timeout stack traces directly enhances developer productivity and reduces the time spent on debugging. This not only saves time but also makes the overall development experience smoother and more enjoyable.

The Current Pain Points

To really understand the frustration, let's zoom in on the current pain points. When a timeout error occurs, developers often face these challenges:

1. Difficulty Pinpointing the Source: The stack trace doesn't lead you to the specific function or operation that timed out. You end up having to manually trace through your code, which can be time-consuming and error-prone.
2. Increased Debugging Time: The lack of clear information means you spend more time debugging than you should. This can be particularly problematic in large projects with multiple asynchronous operations.
3. Frustration and Cognitive Load: Debugging obscure errors can be mentally taxing. The added frustration can lead to developer burnout and reduced job satisfaction. Clearer stack traces can alleviate this cognitive load, making the debugging process less stressful.

In essence, the current timeout stack traces are a significant impediment to efficient debugging. They add unnecessary complexity to the troubleshooting process, leading to increased development time and developer frustration.

A Potential Solution: Throwing Errors in Async Functions

One clever solution to this problem involves a small but significant change in how timeout errors are handled within ts-retry-promise. Instead of using reject() to signal a timeout, the library can throw an error inside an async function. This seemingly minor tweak can have a profound impact on the clarity of stack traces.

MurkyMeow, in their fork of the repository, implemented this change and observed that it produces much more informative errors. The key here is that when you throw an error within an async function, the resulting stack trace includes the context of where the error originated in your application code. This is because the JavaScript engine preserves the call stack as it propagates the error up the call chain.

How It Works

To illustrate this, let's revisit the example code:

import { retry } from "ts-retry-promise";

async function main() {
    await retry(
        async () => {
            await delay(1000);
            throw new Error("request was unsuccessful");
        },
        {
            retries: "INFINITELY",
            timeout: 5000,
        }
    );
}

main();

With the proposed change, when the timeout occurs, ts-retry-promise would effectively do something like this internally:

async function timeoutHandler() {
    throw new Error("Timeout after 5000ms");
}

// Instead of reject(new Error("Timeout after 5000ms"));
await timeoutHandler();

By throwing the error within an async function (timeoutHandler in this example), the stack trace will now include the call to retry within the main function. This means you'll see a stack trace that looks something like this (this is just an illustration, the exact format may vary):

Error: Timeout after 5000ms
      at timeoutHandler (/path/to/your/file.ts:20:10)
      at retry (/node_modules/ts-retry-promise/src/retry.ts:XX:YY)
      at main (/path/to/your/file.ts:15:5)
      ...

Notice how the stack trace now includes main and the line where retry was called? This is a huge improvement because it directly points you to the location in your code where the timeout originated.

Benefits of This Approach

1. Clearer Stack Traces: As we've seen, throwing errors in async functions provides stack traces that include the context of your application code, making it much easier to pinpoint the source of the timeout.
2. Faster Debugging: With more informative stack traces, you can quickly identify and fix timeout issues, reducing the time spent debugging.
3. Reduced Frustration: Clearer errors make the debugging process less frustrating, improving the overall developer experience.

Comparing reject() vs. throw

To fully appreciate the benefit, let's briefly compare the original approach of using reject() with the proposed throw approach:

• reject(): When a promise is rejected with reject(new Error(...)), the stack trace typically starts from the point where the promise was rejected, which is often deep within the library's internals. This obscures the context of the original call.
• throw in async: By throwing an error within an async function, the JavaScript engine captures the full call stack, including the context of the original call. This provides a much more complete and informative stack trace.

In summary, switching from reject() to throw within an async function is a simple yet powerful way to significantly improve the clarity of timeout stack traces in ts-retry-promise.

Community Interest and Next Steps

The question now is: is there interest in merging this change into the main ts-retry-promise repository? Based on the potential benefits we've discussed, it seems like a valuable improvement that could greatly enhance the debugging experience for users of the library.

Call to Action

If you're a user of ts-retry-promise or interested in improving error handling in asynchronous JavaScript, now is the time to voice your opinion! Let's discuss the following:

• Do you find the current timeout stack traces in ts-retry-promise to be problematic?
• Do you think the proposed solution of throwing errors in async functions is a good approach?
• Are there any potential drawbacks or alternative solutions we should consider?

Your feedback and insights are crucial in shaping the future of this library. By working together, we can make ts-retry-promise even more robust and developer-friendly.

Potential Considerations

Before merging any changes, it's important to consider potential drawbacks and ensure the solution is as robust as possible. Here are a few things to think about:

1. Backward Compatibility: Will this change break existing code that relies on the current error handling behavior? We need to ensure a smooth transition for existing users of the library.
2. Performance Impact: Could throwing errors instead of rejecting promises have a performance impact? While it's unlikely to be significant, it's worth investigating.
3. Alternative Solutions: Are there other ways to improve stack traces, such as using custom error types or stack trace manipulation techniques?

By carefully considering these factors, we can make an informed decision about the best way forward.

How to Contribute

If you're excited about this improvement and want to contribute, here are a few ways you can get involved:

1. Share Your Thoughts: Leave comments and feedback on this discussion. Your experiences and insights are invaluable.
2. Test the Change: Try out MurkyMeow's fork and see how the improved stack traces work in your own projects.
3. Contribute Code: If you have ideas for further improvements or want to help with implementation, consider submitting a pull request.

Together, we can make ts-retry-promise an even better tool for handling retries in TypeScript applications.

Conclusion

Improving timeout stack traces in ts-retry-promise is a significant step towards enhancing the debugging experience for developers. The proposed solution of throwing errors within async functions offers a promising way to provide clearer, more informative stack traces. By addressing this issue, we can reduce debugging time, minimize frustration, and make the overall development process smoother and more efficient.

Let's continue this discussion and work together to make ts-retry-promise the best it can be. Your feedback and contributions are essential in shaping the future of this valuable library. Thanks for being part of this important conversation!