User-reported memory leak in createListenerMiddleware

[markerikson]

Pasted from https://stackoverflow.com/questions/74852458/memory-leak-with-redux-toolkits-createlistenermiddleware

Original Report

I use Redux Toolkit, and in particular the new listener api, to perform tasks similar to what I could do with Redux-Saga.

Unfortunately, since a few days, I'm stuck with a memory leak and I can't find the cause.

I have reproduced a minimal example of the code that produces this memory leak, link to the example : https://github.com/MrSquaare/rtk-memory-leak

To observe this memory leak :

• I use Chromium, DevTools memory tool
• I trigger a garbage collector
• I make a heap memory snapshot
• I dispatch entity/load (via the UI button)
• I make several heap memory snapshots every 2-3 seconds
• I use the comparison tool, I notice that I have the array allocation size growing infinitely

And after dispatch entity/unload, then make a snapshot heap memory, we can observe that the allocations disappear...

Has anyone observed similar behavior? Or does anyone have an idea of the cause? Thanks!

EDIT 1:

I made an example with only the listener middleware (only-middleware branch), and compared it with different ways of doing :

• With forkApi.pause : Important leaks, especially of the generated entities
• Without forkApi.pause : I use directly api.dispatch, no more leaks of the generated entities, some leaks of other kinds, but maybe normal things (I am not qualified enough to pronounce on this)
• Without api.dispatch : I call directly the function that generates an entity, same result as with api.dispatch

It seems that the leak is related to forkApi.pause, but again I am not qualified enough to know the real cause...

Other Notes

Lenz pointed to nodejs/node#17469 (comment) - it may be related to use of Promise.race():

export const createPause = <T>(signal: AbortSignal) => {
  return (promise: Promise<T>): Promise<T> => {
    return catchRejection(
      Promise.race([promisifyAbortSignal(signal), promise]).then((output) => {
        validateActive(signal)
        return output
      })
    )
  }
}

Lenz's note:

So the problem is that promisifyAbortSignal will stick around for a very long time