Discussion: Criteria for upgrading worker_threads module from experimental to stable

[Trott]

• User-space modules built on worker_threads
  • worker-threads-pool
  • microjob
  • node-worker-threads-pool
• Modules in citgm that exercise worker_threads in tests
  • ...
• Reports of worker_threads deployed in production
  • ...
• Framework adoption
  • ...
• full test coverage
  • test coverage is now 100% for worker_threads JS files in core
• No flaky tests
  • fix flaky test/parallel/parallel.status:test-worker-debug (Investigate flaky parallel/test-worker-debug on Windows #28106)
  • fix flaky test/parallel/parallel.status:test-worker-prof
  • fix flaky test/parallel/parallel.status:test-worker-syntax-error
  • fix flaky test/parallel/parallel.status:test-worker-syntax-error-file
  • fix flaky test/parallel/parallel.status:test-worker-memory
• Review source code for compatibility with terminate()
• No reliance on experimental V8 APIs (ValueSerializer in particular)

/cc @nodejs/workers

[AyushG3112]

Question: Is the API more or less frozen?

[devsnek]

Would be nice to see locks be stable by then too, but maybe that's a separate thing to track?

[addaleax]

@devsnek I’d track that separately, given that it’s a fully separate API and is useful independently of Workers?

[joyeecheung]

Question: Is the API more or less frozen?

From Node's side it's still experimental so I believe it's not frozen, but it's related to Web Workers which has a stable spec and we (kind of? correct me if I am wrong) agreed in nodejs/TSC#557 that we don't want to deviate too far from the existing design.

[addaleax]

Fwiw, there’s also the issue of workers not playing well with fs stat watchers because their cleanup code calls its callback prematurely on the libuv side (libuv/libuv#1869) … should things like that go on the list?

[Trott]

should things like that go on the list?

I guess if we don't want it to be stable before that's fixed, then yes.

[devsnek]

just reading the microjob readme... So, Microjob treats Node.js threads as temporary working units: if you need to spawn a long-living thread, then you should...

I think another thing to block on is better documentation. people should be re-using threads as much as possible.

[benjamingr]

@KromDaniel

[benjamingr]

Does the inspector work already? (I was away and didn't notice)

Would also be interested in getting sockets transferable - @KromDaniel has expressed interest in working on that (although I'm definitely not blocking on this)

[addaleax]

Does the inspector work already? (I was away and didn't notice)

It should, yes. :)

Would also be interested in getting sockets transferable

I wouldn’t list that as a criterion here, but I’d also love to see that! Adressing libuv/libuv#390 would be the “hard” part here.

[stevenvachon]

https://github.com/mvcbox/node-function-thread is interesting as well for running a single function in a thread. Perhaps not low-level enough and could be rewritten to use the new APIs.