[Bug]: False positive memory leak when running with --experimental-vm-modules and using --detectLeaks

[enisdenjo]

Version

^29.7.0

Steps to reproduce

1. Clone enisdenjo/jest-fetch-leak repo
2. Read its readme for local repro

Expected behavior

No leak. Or at least consistent behaviour between CJS and ESM.

Actual behavior

Leaks in ESM, doesn't leak in CJS.

Additional context

Exact same test leaks with:

node --experimental-vm-modules node_modules/jest/bin/jest.js --detectLeaks

but doesn't leak with:

node node_modules/jest/bin/jest.js --detectLeaks

Environment

ubuntu-latest from GitHub Actions

[enisdenjo]

Seems like it's not only Jest, I've implemented the leak detector and tested pure Node (https://github.com/enisdenjo/node-leak). Running an ESM script in the vm leaks, while CJS script doesn't. 🤔

[SimenB]

See #14526 and its linked upstream Node comment (about how it's not really possible to create a good leak detector from JS). Dunno if it helps in this case - the point is more that it's inherently not possible to get 100% precise.

Node has had some ESM vm API leak fixes recently (nodejs/node#48510), not sure if those help?.

---

Might be worth opening an issue upstream and pinging @joyeecheung with your minimal version without Jest.

[enisdenjo]

Opened an issue with Node (nodejs/node#50964). Let's see.

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