151–160 of 223 posts
Years ago I used Adobe LiveCycle, a horrible "low code" enterprise framework foisted on us from far above.
One thing I always did like about it though was its replay tool which this reminds me of. I was always surprised it wasn't more of a thing in the dev space, it seems very useful.
Engineer @ Replay here - If you're a console.log kind of developer (isn't everyone at least some of the time?), you should check this out. Imagine being able to add console.log() statements to code that already ran and seeing the results immediately! It's a bit mind blowing the first time you use it.
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> First, nobody uses breakpoints. It saddens me that a lot of people don't use debuggers and default to adding print statements. As far as I can tell, it's for several reasons: 1. The debugger is primitive (e.g. Godot GDScript - no conditional breakpoints or watches). 2. The debugger is unstable (e.g. Android Studio - frequently hangs, or takes a long time to populate data needlessly) 3. The debugger's UI is not frie…
I think print statements are actually useful in ways that typical debuggers are not meant to be; they make it easy to show changes over time, and they provide a tight feedback loop between observing the value of some data and performing interactions that update that data. For example, if you wanted to know how a coordinate calculation changed as you scrolled the page, print statements would be more useful than a debu…
The debugger saves so much time wasted recompiling/reloading with new print statements, IMO it's strictly better on every aspect.
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(Replay engineer): we basically record all the inputs and outputs to a program. In the example of an HTTP request: when recording we'd record that a request was made, and the response. When replaying, rather than make the HTTP request, we return the response that was recorded. If you're interested you can learn more about how Replay works here: https://medium.com/replay-io/how-replay-works-5c9c29580c58
> Likewise, the raw pointer values don’t have an effect on the behavior of the JavaScript There are actually some cases where raw pointer values can effect user-visible browser behavior indirectly. Notably if the pointer values affect iteration order in an associative data structure which the browser uses in some way that tickles JS differently depending on the order. There are bunches of other bizarre edge cases you…
Really impressive. Will keep it around for sure to try debugging a real issue next time. Congrats on the launch and the great app!
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Hey! Sorry to hear you're having an issue. That message occurs when we try to asynchronously load a JavaScript bundle for the app and it fails. Typically, that's because we've updated the app and that bundle has been replaced with another file. That shouldn't be the case for you though so perhaps there's a network issue? Clearing your cache and trying again might resolve it. Feel free to jump on our discord ( https:/…
I'm using just a slightly outdated browser, which is probably the cause. I'm on Ungoogled Chromium 81 (by choice) which doesn't automatically update, and the ||= (boolean OR assignment) operator wasn't added until 85. Your payload appears to compile down for older browsers (as is evident by the use of `var`, unless.. you actually write code using `var`) but it misses the ||= operator transformation it seems. Thus, th…
I read the medium post ( https://medium.com/replay-io/how-replay-works-5c9c29580c58 ), which gives an overview of how Replay works, but there are a few things I still don't understand. 1) How does the step backward functionality work? Do you take snapshots every so often of the Javascript environment? How do you handle destructive assignments? 2) Does Replay record actual syscalls made by the browser, or is it record…
> The interface which Replay uses for the recording boundary is the API between an executable and the system libraries it is dynamically linked to.
I assume the ordered locks use a global order.
I read the medium post ( https://medium.com/replay-io/how-replay-works-5c9c29580c58 ), which gives an overview of how Replay works, but there are a few things I still don't understand. 1) How does the step backward functionality work? Do you take snapshots every so often of the Javascript environment? How do you handle destructive assignments? 2) Does Replay record actual syscalls made by the browser, or is it record…
1. Rather than having to restore state to the point at the previous step, we can step backwards by replaying a separate process to the point before the step, and looking at the state there (this post talks about how that works: https://medium.com/replay-io/inspecting-runtimes-caeca007a4b...). Because everything is deterministic it doesn't matter if we step around 10 times and use 10 different processes to look at the state at those points.
2. We record the calls made by the browser, though it is the calls into the system libraries rather than the syscalls themselves (the syscall interfaces aren't stable/documented on mac or windows).
3. Maintaining ordering like this isn't normally necessary for ensuring that behavior is the same when replaying. In the case of memory locations, the access made by thread 2 to location B will behave the same regardless of accesses made by thread 1 to location A, because the values stored in locations A and B are independent from one another.
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Congratulations! This looks super interesting! How are side effects (mutating HTTP calls, cookie creation, other I/O) handled?
(Replay engineer): we basically record all the inputs and outputs to a program. In the example of an HTTP request: when recording we'd record that a request was made, and the response. When replaying, rather than make the HTTP request, we return the response that was recorded. If you're interested you can learn more about how Replay works here: https://medium.com/replay-io/how-replay-works-5c9c29580c58
I read the medium post ( https://medium.com/replay-io/how-replay-works-5c9c29580c58 ), which gives an overview of how Replay works, but there are a few things I still don't understand. 1) How does the step backward functionality work? Do you take snapshots every so often of the Javascript environment? How do you handle destructive assignments? 2) Does Replay record actual syscalls made by the browser, or is it record…
Thanks for the links to the blogs. I was wondering how it worked and the "How it works" bit on that page said nothing. Nice that they've explained it. It looks like the blog does answer your questions though: > The interface which Replay uses for the recording boundary is the API between an executable and the system libraries it is dynamically linked to. I assume the ordered locks use a global order.