rxjs: RxJS asapScheduler stops working in 7.5.1

Describe the bug

While trying to upgrade from RxJS6 to RxJS7 I noticed that sometimes our observables were not being executed. After debugging I found that at least asapScheduler did not always run the passed in callback function.

Expected behavior

asapScheduler should always run

Reproduction code

See the stackblitz

See the instructions in the stackblitz:

// To reproduce the issue (rxjs @ 7.5.1):
// 1. load this in stackblitz
// 2. observe that the logs up to '))) n 4' are printed
// 3. make a change to this file, note that it does not work (nothing runs)
// 4. reload the stackblitz page, you will see it work again

// To have it always work (rxjs @ 6.6.7):
// 1. load this in stackblitz
// 2. in the "Dependencies" on the left, enter rxjs@6.6.7
// 2. observe that the logs up to '))) n 4' are printed
// 3. make a change to this file, note that it still works

In our own application, this stops working after ~135 calls to the asapScheduler. The same two calls were failing, but I could cause it to fail sooner if I used asapScheduler more frequently. I managed to get it to fail in stackblitz, but only while changing the stackblitz file. I’m not 100% sure this reproduces the issue in our own application, but the symptoms are the same, and in both 6.6.7 works

Reproduction URL

https://stackblitz.com/edit/rxjs-htf8tz?file=index.ts

Version

7.5.1

Environment

7.5.1 is causing the issue, but 6.6.7 works as expected

Additional context

Experienced in our corporate Angular 13 application

About this issue

Original URL
State: closed
Created 2 years ago
Reactions: 8
Comments: 29 (10 by maintainers)

Most upvoted comments

Okay… so here’s the thing… THE ORIGINAL ISSUE that was filed here is indeed fixed as of 7.5.7.

There’s a separate issue that is documented here: https://github.com/ReactiveX/rxjs/issues/6747#issuecomment-1360958245

I’m going to open a new Issue for that, and close this one to prevent confusion.

A friendly reminder to some of the snark in here: This is free software maintained by unpaid volunteers. I understand you’re frustrated, but I’m quite literally not paid to deal with you.

benlesh on Feb 28, 2023

It’s this line:

https://github.com/ReactiveX/rxjs/blob/6d011f0dc67b736adc0979d3bc14d93b49064efa/src/internal/scheduler/AsapAction.ts#L35

_scheduled cannot be set to undefined unless it’s equal to id. That’s what’s preventing further actions from being executed in this issue. However, looking at the source, I’m not sure that’s the only problem. I’m going to create a failing test for this situation and will then open a PR to fix it. And I’ll have more of a think about what I suspect are additional issues with the current implementation.

cartant on Jan 12, 2022

CORE TEAM: Needs to be fixed in v7 and v8. We’ll likely be introducing new/better/smaller schedulers for v9.

benlesh on Feb 8, 2023

We’ll discuss this in next core team meeting again to confirm.

kwonoj on Jan 4, 2023

Can this please be addressed? It is a blocking bug and it is not fixed in any rxjs version. It has been broken for a year now with no one attempting to resolve the issue thus far.

arobinson on Jan 4, 2023

This should be fixed as of rxjs@7.5.7, please update.

benlesh on Dec 14, 2022

Ane news about that? Ngrx component store debounce use it… With this bug the debounced selectors stop working from time to time which means it’s a blocker. We can’t upgrade above 7.4.x with this bug

Harpush on Aug 2, 2022

This should be fixed as of rxjs@7.5.7, please update.

Still doesn’t work for our project after updating to 7.5.7. This issue should not be closed.

aldrashan on Dec 15, 2022