[Bug]: `--detectLeaks` CPU hammering on Node 20

[EmrysMyrddin]

Version

Starting from version 30, was not happening on version 29.

Steps to reproduce

On Node 20, it seems --detectLeaks is causing a massive CPU hammering, making tests super slow and finally failing with a ELIFECYCLE  Command failed.
https://github.com/graphql-hive/graphql-yoga/actions/runs/15902848813/job/44849836112?pr=4088#step:11:55

Expected behavior

To pass tests as in other versions of Node.

Actual behavior

Running with leaks detector on Node 20 fails.

Additional context

No response

Environment

System:
    OS: macOS 15.3
    CPU: (12) arm64 Apple M3 Pro
  Binaries:
    Node: 20.11.1 - ~/.local/share/mise/installs/node/20/bin/node
    npm: 10.2.4 - ~/.local/share/mise/installs/node/20/bin/npm
    pnpm: 10.12.3 - ~/.local/share/mise/installs/node/20/bin/pnpm
    bun: 1.2.17 - ~/Dev/Projects/TheGuild/graphql-yoga/node_modules/.bin/bun
  npmPackages:
    jest: 30.0.3 => 30.0.3

[eyalroth]

After a bit of debugging, it looks like what's happening in node 20 is that Jest is detecting a leak and calls getHeapSnapshot, which is slow and consumes a lot of CPU in this repo.

There's even a comment in the source code:

// triggering a heap snapshot is more aggressive than just global.gc(),
// but it's also quite slow, so only do it if we still think we're leaking.
// nodejs/node#48510 (comment)
getHeapSnapshot();

Jest will only reach this code if the NodeEnvironment object was yet to be GC-ed at this stage.

Indeed when running in Node 20, I can see in heap snapshots that this object (NodeEnvironment) is still referenced from the root (>20 distance, so quite deep), so it cannot be garbage collected. With Node 22 it doesn't happen.

I'm guessing this suggests some form of memory leak in the repo under Node 20.

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[github-actions]

This issue was closed because it has been stalled for 30 days with no activity. Please open a new issue if the issue is still relevant, linking to this one.