Infinite startTimer loop causing high CPU load

[Grzegorz Tańczyk]

Hello!

I'm not able to give exact reproduction steps, but this screenshot demonstrates the problem:

I'm using useDebouncedCallback in a regular component. The component itself is not re-rendered, and there is nothing that could call the callback itself.

Version of React: 16.9.46

Thanks for help!

[Nik]

Hi @gtanczyk
I'd like to ask which arguments were provided to the component?
It seems the problem is connected to shouldInvoke func https://github.com/xnimorz/use-debounce/blob/master/src/useDebouncedCallback.ts#L135-L153, but I need a little bit more info to understand

[Grzegorz Tańczyk]

I'm observing this behavior in many different instances of useDebouncedCallback, but this is the most common setup:

const debouncedFunc = useDebouncedCallback(func, 500, { maxWait: 1000 });

func is not invoked, shouldInvoke is returning false, because this hook is unmounted. (mounted.current === false)

Unfortunately I'm not able to provide reliable reproduction steps.

[Grzegorz Tańczyk]

@xnimorz Please have a look at this example: https://codesandbox.io/s/determined-antonelli-4lhw6?file=/src/App.js
so looks like it's a problem of unmounted components.

[Kelly Milligan]

seeing a similar issue.

const saveScroll = useDebouncedCallback((scrollOffset: number) => {
    //do stuff
  }, 200);

<List
            ref={listRef}
            itemKey={getItemKey}
            className="AvailabilitySearch-destinationResultList AvailabilitySearch-destinationResultList--simple"
            innerElementType="ul"
            height={height}
            itemCount={results?.offeringAvailability.length ?? 0}
            width={width}
            itemSize={getItemSize}
            onScroll={({ scrollOffset }) => saveScroll.callback(scrollOffset)}
          >
            {Row}
          </List>

after a little bit of scrolling, the tab spikes the cpu.

[Nik]

Hi @kelly-tock, could you provide a little bit more information? cause, I won't be able to reproduce the error.

[Nik]

@gtanczyk Thank you for the information! I fixed it in use-debounce@5.2.1

[Nik]

I'm closing this issue at the moment, as the problem with the unmounted component is gone. If you still have any problems with infinite timeouts, please feel free to create a new issue or reopen this one

[Grzegorz Tańczyk]

@xnimorz Thanks a lot