fix: enormous memory consumption of the dev server

[jayu]

There was not issue for that, I've decided to fix the problem right away

Context

We have a blitz v2 app with ~290 queries and mutations.

Each query/mutation indirectly imports up to 900 source code files.
We use dependency injection and as a result each endpoint imports the whole backend code.

We use next@12 and have SWC enabled.

Our dev server used to take up to 18GB or RAM, which is enormous amount of memory for parsing and merging together 900 source code files + compiling the font-end.

The memory was allocated for short period of time, and then reduced to 6-8GB.

It was killing 2020 MacBook Pro with 16BG of Ram.

What are the changes and their implications?

I dig into the problem for quite a while and I found out that the issue was basically using dynamic imports for importing routes code.

Dynamic imports in Webpack automatically creates a separate chunk.

Separate chunk means a separate isolated compilation of code. Chunking backend code does not make any sense unless it's run as lambda function.

With dynamic imports and the size of our app, Webpack was bundling the same code ~290 times instead of doing it once.

That created huge memory peaks in quite random moments, eg. a 30 seconds after pages/api/rpc/[[...blitz]].ts finished to compile.

To fix that I simply changed the dynamic import into require call, which do not create separate chunk in Webpack.

We are using the patched version for more than a week now and everything works fine. Compilation is faster, there are no more memory peaks and most importantly we reduced the team frustration.

Preparing a reproducible demo that showcase the memory usage might not be easy without real production code, but at least I can prove that the chunks are created for each query/mutation file when using dynamic imports. Let me know if that's needed.

Bug Checklist

• Changeset added (run pnpm changeset in the root directory)
• Integration test added (see test docs if needed)
  • I believe existing tests should cover this change, cos it only changes how to code is bundled without affecting runtime

[changeset-bot]

🦋 Changeset detected

Latest commit: ecf8fca

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 8 packages

Name	Type
@blitzjs/rpc	Patch
next-blitz-auth	Patch
@blitzjs/next	Patch
@blitzjs/auth	Patch
@blitzjs/codemod	Patch
@blitzjs/config	Patch
@blitzjs/generator	Patch
blitz	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[siddhsuresh]

LGTM! Thanks for the PR!

[flybayer]

ok this is good, but resolversDynamicImport needs to default to true on vercel.

Secondly, add more info to the release notes describing why we have this, why we're changing, that the new default is different than before, and that it defaults to true on vercel.

[flybayer]

I just pushed a commit with a fix and refactor.

• resolversDynamicImport was not actually being passed to webpack
• We had duplicate loader option types, so I removed the one, now we have proper type safety to catch the first problem
• clean up the logic in the loader by defaulting the dynamic import config at the webpack config level

[blitzjs-bot]

Added @jayu contributions for doc and code

[jayu]

Thanks for help with shipping this 🙏