fix(browser): Fix bug causing unintentional dropping of transactions #12933
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To add some context, this happens for me with the replay integration and particularly for the spans for the request to the worker blob, and only in Chrome. |
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andreiborza
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Jul 17, 2024
| // There is a SO post attempting to explain this, but it leaves one with open questions: https://stackoverflow.com/questions/23191918/peformance-getentries-and-negative-duration-display | ||
| // The way we clamp the value is probably not accurate, since we have observed this happen for things that may take a while to load, like for example the replay worker. | ||
| // TODO: Investigate why this happens and how to properly mitigate. For now, this is a workaround to prevent transactions being dropped due to negative duration spans. | ||
| entry.duration < 0 ? 0 : entry.duration, |
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l: any reason for not using Math.max?
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| entry.duration < 0 ? 0 : entry.duration, | |
| Math.max(0, entry.duration), |
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I have a theory that performance is better for the inline if but can change
Lms24
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Jul 17, 2024
| const duration = msToSec( | ||
| // Inexplicibly, Chrome sometimes emits a negative duration. We need to work around this. | ||
| // There is a SO post attempting to explain this, but it leaves one with open questions: https://stackoverflow.com/questions/23191918/peformance-getentries-and-negative-duration-display | ||
| // The way we clamp the value is probably not accurate, since we have observed this happen for things that may take a while to load, like for example the replay worker. |
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does the worker take a while to load though? I'd imagine creating the blob should be fairly fast since the code ships with the already loaded JS SDK bundle by default? My guess yesterday was the opposite: that it's too fast and therefore causing weird timing problems 😅
(maybe this is also blob-specific?)
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I think it loaded in something like 4ms when we tested it (which was locally in dev mode). So not too fast. Even if it loaded "too fast" a negative duration doesn't make sense in my eyes 🤔
This was referenced Aug 9, 2024
This was referenced Aug 27, 2024
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We saw instances of pageload transactions being dropped because they contained spans with negative durations (
timestamp<start_timestamp).After investigating it seems like performance entries by the browser are emitted with a negative duration. We could only observe this happening in Chrome.
The particular environment this could be (flakily) reproduced is on Chrome, for the scaffold Next.js app, with the Sentry SDK and Replay installed. The negative duration span that was recorded was for the replay worker resource.
Other people also seem to be running into this but so far I don't really understand why the duration is negative and how we would mitigate this properly. This PR is more of a hot-fix than anything else.
Attempts to fix: #12914