TS-Retry-Promise: Fixing Unhelpful Timeout Stack Traces

Hey guys! Today, we're diving into a pretty common issue when using the ts-retry-promise library: unhelpful timeout stack traces. Imagine you're building a robust application, and you're using ts-retry-promise to handle those pesky intermittent errors. You set up a retry mechanism with a timeout, but when a timeout actually occurs, the stack trace you get points you straight into the library's internals, leaving you scratching your head about where the timeout originated in your own code. Frustrating, right? Let's break down the problem, explore a proposed solution, and discuss how we can make this awesome library even better.

The Problem: Unhelpful Timeout Stack Traces

So, let's get into the nitty-gritty. The core issue here is that when a timeout occurs within ts-retry-promise, the error stack trace doesn't clearly show the origin of the timed-out operation in your application's code. Instead, it primarily points to the ts-retry-promise library's internal timeout handling logic and some Node.js internals.

Consider this typical scenario:

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

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

main();

In this example, we're using retry to handle a potentially failing asynchronous operation. We've set a timeout of 5000 milliseconds. Now, if the operation exceeds this timeout, you'd expect the stack trace to lead you back to the main() function, right? But instead, you get something 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 directly to the ts-retry-promise library's timeout.ts file and some Node.js internals. This is less than ideal because it doesn't tell you where in your application the timeout actually happened. When you're dealing with complex applications and multiple retry scenarios, this lack of context can make debugging timeouts a real headache. You're left digging through your code, trying to figure out which operation timed out, rather than having the stack trace point you directly to the culprit. This can significantly increase the time it takes to diagnose and fix timeout-related issues, impacting your development workflow and potentially delaying releases. The core challenge is that the reject() call, used to signal the timeout, doesn't preserve the original context of the asynchronous operation. This leads to a stack trace that reflects the timeout handling mechanism within the library, rather than the initiating call site in your application. So, how can we improve this? Let's explore a potential solution.

The Proposed Solution: Throwing Errors for Better Stack Traces

Okay, so we've identified the problem: unhelpful timeout stack traces. Now, let's talk about a potential solution. One clever approach, as suggested by MurkyMeow in their fork, is to replace the reject() call with a throw inside an async function. This seemingly small change can have a significant impact on the quality of the stack trace you receive.

Here's the basic idea: Instead of using reject() to signal a timeout, we use throw to raise an error. The key is to do this within an async function. Why? Because async functions have a neat way of preserving the stack trace context. When an error is thrown within an async function, the stack trace will include the call sites leading up to the point where the error was thrown, effectively giving you a much more informative trace.

To illustrate, let's revisit our previous example and imagine how this change would affect the stack trace. With the throw approach, the stack trace would now include the main() function in our example, pinpointing the exact location where the timeout occurred. This is a game-changer for debugging. Instead of having to manually trace through your code, the stack trace directly shows you where the problem originated.

Here's a simplified view of how the change works:

1. A timeout occurs within ts-retry-promise.
2. Instead of calling reject(), the code now throws an error within an async function.
3. The async function ensures that the stack trace includes the context of the original call site in your application.
4. The resulting stack trace clearly shows the origin of the timeout, making debugging much easier.

This approach leverages the natural error handling mechanisms of JavaScript and async functions to provide a more intuitive and helpful debugging experience. By preserving the context of the error, developers can quickly identify and resolve timeout issues, leading to more robust and maintainable applications. It's a simple yet powerful change that can significantly improve the usability of the ts-retry-promise library.

Benefits of the Proposed Change

So, why are we so excited about this potential change? Let's break down the key benefits of using throw instead of reject() for timeout errors:

• Improved Debugging Experience: This is the big one. With more informative stack traces, you can quickly pinpoint the exact location in your code where the timeout occurred. No more digging through layers of library internals – the stack trace guides you directly to the source of the problem. This can save you significant time and effort when troubleshooting timeout-related issues.
• Faster Issue Resolution: When you can easily identify the source of a timeout, you can fix it faster. This means less time spent debugging and more time spent building features and delivering value. In fast-paced development environments, this efficiency gain can be a major advantage.
• Increased Developer Productivity: A better debugging experience translates to increased developer productivity. When developers aren't bogged down by cryptic error messages and unhelpful stack traces, they can focus on writing code and solving problems. This leads to a more efficient and enjoyable development process.
• More Robust Applications: By making it easier to debug timeouts, this change contributes to the creation of more robust applications. You'll be able to identify and address timeout issues more effectively, leading to a more stable and reliable system.
• Better Error Context: The throw approach preserves the context of the error, providing valuable information about the state of your application when the timeout occurred. This context can be crucial for understanding the root cause of the issue and implementing effective solutions.
• More Intuitive Error Handling: Using throw aligns with the standard JavaScript error handling paradigm, making the library's behavior more intuitive for developers. This reduces the learning curve and makes it easier to integrate ts-retry-promise into existing projects.

In short, this seemingly small change has the potential to significantly improve the developer experience and the overall quality of applications that use ts-retry-promise. It's a win-win situation for everyone involved. By adopting this approach, we can make the library even more user-friendly and empower developers to build more reliable and efficient systems.

Community Interest and Next Steps

Now, the big question: Is there interest in merging this change into the main ts-retry-promise repository? From the initial discussion, it seems like there's definitely a need for improved timeout error handling. The current stack traces can be frustrating, and the proposed solution offers a clear path forward.

MurkyMeow has already done the heavy lifting by implementing the change in their fork. This provides a concrete example of how the solution works and allows others to try it out and provide feedback. This is a fantastic starting point for a community discussion.

The next steps would likely involve:

1. Gathering more feedback: It's crucial to get input from other users of the library. Do they also experience this issue? Do they agree that the proposed solution is an improvement? Sharing experiences and perspectives will help validate the change and identify any potential edge cases.
2. Testing and refinement: Thorough testing is essential to ensure that the change doesn't introduce any regressions or unexpected behavior. This includes unit tests, integration tests, and potentially even real-world testing in applications that use the library. The implementation might also need some refinement based on the feedback received.
3. Creating a pull request: Once the change has been thoroughly vetted, a pull request can be submitted to the main repository. This will allow the library maintainers to review the code and consider it for inclusion in a future release.
4. Documentation: If the change is merged, it's important to update the library's documentation to reflect the new error handling behavior. This will help users understand how timeouts are reported and how to debug them effectively.

The open-source community thrives on collaboration and shared effort. By discussing this issue, proposing solutions, and working together, we can make ts-retry-promise an even more valuable tool for developers. So, let's keep the conversation going and explore how we can best implement this improvement.

Conclusion

Alright guys, we've covered a lot! We've dived deep into the issue of unhelpful timeout stack traces in ts-retry-promise, explored a promising solution involving throwing errors in async functions, and discussed the potential benefits and next steps. The key takeaway here is that small changes can make a big difference in developer experience. By improving the clarity of timeout error messages, we can save developers time, reduce frustration, and ultimately build more robust applications.

The proposed solution by MurkyMeow is a great example of how a simple tweak can significantly enhance the usability of a library. Replacing reject() with throw in an async function preserves the context of the error, leading to stack traces that directly point to the source of the timeout. This is a game-changer for debugging and can dramatically improve developer productivity.

Now, it's up to the community to weigh in, provide feedback, and help shape the future of ts-retry-promise. If you've experienced this issue, or if you have thoughts on the proposed solution, please share your insights! Open-source projects thrive on collaboration, and your input is valuable. Let's work together to make this library the best it can be. By addressing this issue, we can ensure that ts-retry-promise remains a powerful and user-friendly tool for handling retries and timeouts in asynchronous operations. So, let's keep the conversation going and strive for a better debugging experience for everyone!