Clear finished discrete updates during commit phase #18515
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Details of bundled changes.Comparing: bce982b...6f67d0a react-dom
react-art
react-test-renderer
react-native-renderer
react-reconciler
Size changes (stable) |
Details of bundled changes.Comparing: bce982b...6f67d0a react-art
react-native-renderer
react-test-renderer
react-dom
react-reconciler
ReactDOM: size: 0.0%, gzip: 0.0% Size changes (experimental) |
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I'm not super familiar with this code but it seems a bit fragile. Are we treating the symptom or the cause? You said:
Do we understand why? |
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Thanks for the unit test! The underlying issue is that we're clearing the timeout without making sure the priority level that corresponds to that level is rescheduled. It's usually fine to clear a pending timeout at the beginning of a new render (in react/packages/react-reconciler/src/ReactFiberRoot.js Lines 216 to 226 in 8edcd03 However, There are multiple ways we could fix this. My instinct is to fix it inside We should also commit your changes here, but let's fix the underlying issue first. I'll take a closer look at this. |
Make sure the suspended level is marked as pinged so that we return back to it later, in case the render we're about to start gets aborted. Generally we only reach this path via a ping, but we shouldn't assume that will always be the case.
If a root is finished at a priority lower than that of the latest pending discrete updates on it, these updates must have been finished so we can clear them now. Otherwise, a later call of `flushDiscreteUpdates` would start a new empty render pass which may cause a scheduled timeout to be cancelled.
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Thanks again for the fix! 🎉 |
acdlite
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Apr 8, 2020
Adds a regression test for the same underlying bug as facebook#18515 but using pings. Test already passes, but I confirmed it fails if you revert the fix in facebook#18515.
acdlite
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Fix #18020
If a root is finished at a priority lower than that of the latest pending discrete updates on it, these updates must have been finished so we can clear them now. Otherwise, a later call of
flushDiscreteUpdateswould start a new empty render pass which may cause a scheduled timeout to be cancelled.