Rspack 1.4 Release Plan

[h-a-n-a]

Rspack 1.4 is estimated to be released in the middle of June, 2025.

Features

1. Remove experiments.parallelCodeSplitting

experiments.parallelCodeSplitting has been enabled by default in 1.3.0. The old code splitting will be removed in 1.4.0.

Issue #9059
Author @JSerFeng

2. SWC upgrade

Issue #10293
Author @GiveMe-A-Name

3. New CssChunkingPlugin

Issue #10235
Author @SyMind

4. Lazy compilation supports multiCompiler

PR #9828
Author @JSerFeng

Performance

1. Enable experiments.incremental by default

experiments.incremental config will be enabled by default in 1.4.0 to speed up HMR.

Author @ahabhgk

Bug fixes

TODO

Chore

1. Upgrade zod to v4

#10467

Author @colinaaa

Tasks

TODO

[markmssd]

In our project (big one), parallelCodeSitting was slowing startup and HMR time quite lot, and we disabled it when upgrading to 1.3. It might be because of our code splitting configuration, not sure yet. I'll try to do a repro.

[n0th1ng-else]

Thank you for the headsup! indeed there are a couple of things that we are suffering from while I am trying to update the version. and turns out parallelCodeSitting is one of them

[JSerFeng]

Did you disable optimization.removeAvailableModules?

You can set stats.logging = 'verbose', then check the time cost for rebuild chunk graph

[h-a-n-a]

Oh here's someone else experiencing this: #8976 (comment)! (@n0th1ng-else)

We've been working on this. Just stay tuned for future updates ;-).

[JSerFeng]

For parallelCodeSplitting, we better create a separate issue, are you available to make one with repro or more detail info? It would be very helpful❤️ @markmssd @n0th1ng-else

[n0th1ng-else]

Thank you. took it separatelly