Memory Leak in nodejs version 20.16.0

[SteffenHo]

We saw a massive increase in memory in our next.js application after updating to version 20.16.0. We build our application with docker and the 20-alpine image. Other users were also able to confirm this problem: https://www.reddit.com/r/node/comments/1ejzn64/sudden_inexplicable_memory_leak_on_new_builds/

We then switched to version 20.15.1 and the memory returned to normal.

Maybe someone else could confirm this problem too?

[RedYetiDev]

Hi! Could you possibly narrow down where the error is coming from and provide a minimal reproducible example?

Additionally, does this also occur on v22?

[SteffenHo]

I'm sorry. I could not provide a minimal reproducible example. We have an enterprise shop application with several hundred/thousands pages renderings per minute. We were only able to reproduce the error under higher load.

I therefore opened a discussion and not a bug to find out whether more developers could observe a similar behavior.

[khuezy]

Thanks for bringing this up. Here's a related issue with a min repro: vercel/next.js#68636

[snyamathi]

@RedYetiDev I was able to reproduce the issue locally and trace it back to this commit: 45c5ec8

the prior commit, e282925 works with no memory leak

the next commit, 45c5ec8 causes a memory leak

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Something was introduced in undici between 6.15.0 and 6.16.1 which is causing issues

[RedYetiDev]

@nodejs/undici

[snyamathi]

I'm able to trace it back to this commit nodejs/undici@63b7794

pretty sure it has something to do with https://github.com/nodejs/undici/blob/abec615bef89992e9fec5dd35c8f59aa33e00459/lib/web/fetch/response.js#L529

[snyamathi]

@RedYetiDev nodejs/undici#3445 This fixes the issue locally

[manuelseisl]

same issue, when using next.js application with node 20.16.0 on server we saw a massive increase in memory. upgrade to node 22.7.0 solved the issue

[mcollina]

This is solver in Node.js v22.7.0. The fix will be available in the next v20 release too.

[khuezy]

A heads up, 22.7.0 has a critical bug w/ buffers: #54518
Your app may crash if it uses buffers.