MaxListenersExceededWarning when having 11+ content scripts defined

[vladgabriel]

Describe the bug

When adding over 11 content scripts the following error is displayed:

(node:38511) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 SIGTERM listeners added to [process]. MaxListeners is 10. Use emitter.setMaxListeners() to increase limit

Reproduction

memory-setup.zip

Steps to reproduce

Run yarn install and yarn dev

System Info

System:
    OS: macOS 14.2.1
    CPU: (10) arm64 Apple M1 Pro
    Memory: 76.14 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.15.1 - ~/.asdf/installs/nodejs/20.15.1/bin/node
    Yarn: 4.5.0 - ~/.asdf/installs/nodejs/20.15.1/bin/yarn
    npm: 10.7.0 - ~/.asdf/plugins/nodejs/shims/npm
    bun: 1.0.26 - ~/.bun/bin/bun
  Browsers:
    Chrome: 131.0.6778.86
    Chrome Canary: 133.0.6858.0
    Safari: 17.2.1

Used Package Manager

yarn

Validations

• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[aklinker1]

I've noticed this as well, seems like each entrypoint group (build step) adds a listener... I assume because vite is adding it? Not 100% sure which dependency is causing it, but vite is my best guess.

This only happens on node 20 and up.

[aklinker1]

This is caused by:

wxt/packages/wxt/src/core/utils/building/find-entrypoints.ts

Lines 360 to 361 in 5a3790a

	const defaultExport =
	await wxt.builder.importEntrypoint<ContentScriptDefinition>(inputPath);

Specifically when importing multiple entrypoints to extract their options during the build process, like content script matches, we use vite-node to import the TS file and do some preprocessing to speed things up.

However, for every imported entrypoint, we have to create a Vite dev server, and that's where the warning comes from, the dev server setting up a listener to close the server when stopping the process.

Fix is simple, only create a single dev server when importing entrypoint files, but refactoring the code to support that won't be... An easier fix is to import the files one by one, not in parallel, or setup a queue that only allows 9 imports be running at a time.

But I'd rather refactor and get this done right. For now, you can ignore this warning. It shouldn't be causing any problems.