What is "Collecting build traces" doing?

[selalipop]

Summary

It's adding 10 minutes to my CI build, and I assumed it was the tracing required for 'standalone' builds.

But now even with next build + next start it's running and taking more time than the actual build.

Is this behavior expected? This isn't an extremely large project either.

Additional information

No response

Example

No response

[icyJoseph]

This is documented in long form here, https://nextjs.org/docs/app/api-reference/config/next-config-js/output

During a build, Next.js will automatically trace each page and its dependencies to determine all of the files that are needed for deploying a production version of your application.

This feature helps reduce the size of deployments drastically. Previously, when deploying with Docker you would need to have all files from your package's dependencies installed to run next start. Starting with Next.js 12, you can leverage Output File Tracing in the .next/ directory to only include the necessary files.

One of the special things with standalone builds, is that:

Next.js can automatically create a standalone folder that copies only the necessary files for a production deployment including select files in node_modules.

[icyJoseph]

There seems to be an experimental option, parallelServerBuildTraces, could you set that to true, and see if that bumps up the speed of CI? And I guess, webpackBuildWorker should also be set

[icyJoseph]

Need to switch context now, but yeah, I'd expect a way to turn this off, if it is optional, but maybe it is not? I'll take a look later.

[selalipop]

I'll check out parallelServerBuildTraces but I'd still love to get an answer to why outputFileTracing was removed, I didn't see any rationale skimming PRs related to it.

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It seems like there are only two where cases you'd want tracing:

• You're using a standalone export
• You're manually parsing the trace files

If you're using a standalone build, Next can pick up on that and enable tracing. And if you're manually parsing the trace files, then opting into tracing is the least of your worries.

So it seems like the sane default would be having tracing be opt-in, and having standalone builds automatically opt you in. That is unless there's some aspect to this that I'm missing here.

[Aritra1235]

I have the exact same issue, for some reason it is just stuck or takes way too long at Collecting build traces. It is a hit or miss, sometimes its over in seconds sometime not even in 10

[Mykybo]

i have the same issue, how do you disable build traces? does parallelServerBuildTraces help?