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fix: Memoize AsyncLocalStorage instance#8831

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lforst merged 1 commit intodevelopfrom
lforst-fix-als-mem-leak
Aug 17, 2023
Merged

fix: Memoize AsyncLocalStorage instance#8831
lforst merged 1 commit intodevelopfrom
lforst-fix-als-mem-leak

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@lforst lforst commented Aug 17, 2023

Attempts to fix the memory leak reported in #8829 by memoizing the AsyncLocalStorage instance we create when setting the async context strategy.

Note for reviewers: Can you think of any problems this may cause?

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github-actions bot commented Aug 17, 2023

size-limit report 📦

Path Size
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped) 75.16 KB (+0.41% 🔺)
@sentry/browser (incl. Tracing) - Webpack (gzipped) 31.17 KB (+0.2% 🔺)
@sentry/browser - Webpack (gzipped) 21.85 KB (+0.19% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped) 69.73 KB (+0.27% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped) 28.18 KB (+0.1% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped) 20.18 KB (+0.05% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed) 219.89 KB (+0.38% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed) 84.78 KB (+0.13% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed) 59.86 KB (+0.04% 🔺)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped) 31.04 KB (+0.09% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped) 75.18 KB (+15.57% 🔺)
@sentry/react - Webpack (gzipped) 21.88 KB (+0.18% 🔺)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped) 92.97 KB (+0.35% 🔺)
@sentry/nextjs Client - Webpack (gzipped) 50.7 KB (+0.19% 🔺)

Lms24
Lms24 reviewed Aug 17, 2023
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Hmm I'm not sure but wouldn't this mean we potentially reuse the same asyncLocalStorage instance across multiple requests which we actually want to isolate? Don't have a ton of context around ALS so not sure if this concern makes sense

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lforst commented Aug 17, 2023

Hmm I'm not sure but wouldn't this mean we potentially reuse the same asyncLocalStorage instance across multiple requests

Well yes, but that is theoretically not an issue. What matters is that localStorage.run(obj) is called for each separate isolate. To give you some insight, whenever you run localStorage.run(obj) you set what localStorage.get() returns in that particular async context. It shouldn't matter that it's the same AsyncLocalStorage instance.

I am trying to come up with a case where we might run into problems here, but I am struggling. I guess the baseline where this potentially messes up always involves calling Sentry.init() multiple times (which is already kinda funky and not supported) and then doing weird stuff with hubs.

Lms24
Lms24 approved these changes Aug 17, 2023
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Thanks for explaining, this makes sense to me now! I'd say we give it a try and if the issue author is comfortable with trying this out locally first, it'd be even better.

@lforst lforst requested review from AbhiPrasad and timfish August 17, 2023 08:30
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lforst commented Aug 17, 2023

TIL the leak is likely because AsyncLocalStorage objects need to be disabled in order to be garbage collected: docs

mydea
mydea approved these changes Aug 17, 2023
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:shipit:

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timfish commented Aug 17, 2023

Wouldn't this stop us or customers from overriding the async strategy after it's been set by @sentry/node?

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timfish commented Aug 17, 2023

Wouldn't this stop us or customers from overriding the async strategy after it's been set by @sentry/node?

No sorry, I misundersttod the changes!

@lforst lforst merged commit e5a3885 into develop Aug 17, 2023
@lforst lforst deleted the lforst-fix-als-mem-leak branch August 17, 2023 11:52
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@timfish timfish timfish approved these changes

@mydea mydea mydea approved these changes

@Lms24 Lms24 Lms24 approved these changes

@AbhiPrasad AbhiPrasad Awaiting requested review from AbhiPrasad

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