forwardRef() components should not re-render on deep setState() #12690

gaearon · 2018-04-25T18:09:01Z

Fixes #12688. This is not just related to legacy context: as far as I can tell from the test I added, we're currently re-rendering all forwardRef components on a deeper setState. This seems bad.

I changed memoization to store the props instead of the returned child. Not sure if it matters. Maybe for DevTools?

I'm also not sure if what I'm doing here is safe. Can ref provided by React ever be different in this scenario and "justify" re-render?

bvaughn · 2018-04-25T18:16:51Z

packages/react-reconciler/src/ReactFiberBeginWork.js

+    if (hasLegacyContextChanged()) {
+      // Normally we can bail out on props equality but if context has changed
+      // we don't do the bailout and we have to reuse existing props instead.
+    } else if (workInProgress.memoizedProps === nextProps) {


I think we should also compare workInProgress.ref

With what?

(Sorry if I'm being dense)

Also, is it possible for a deep update to influence the value of a ref above it?

Also, is it possible for a deep update to influence the value of a ref above it?

I'm not sure, but it seems conceivable that a ref could be the only changed "prop" (if it's an inline arrow function for a non-PureComponent) and we might bail out when we shouldn't here?

Although in that case it probably wouldn't matter anyway.

Hm... maybe Foo gets new properties that causes it to recreate the ref, but only a filtered set of those props are passed through to the ForwardRef component, so from it's POV nothing has changed?

Maybe this is too contrived.

maybe Foo gets new properties that causes it to recreate the ref, but only a filtered set of those props are passed through to the ForwardRef component, so from it's POV nothing has changed?

OK, that sounds potentially plausible. If you find any free time to hack on this I'd appreciate a test.

I think maybe this is too contrived to be a real concern.

Ref callbacks would be re-invoked if the underlying instance/ref changed. If the ref callback itself changed, most likely this just means it's an arrow functions and has an identical implementation.

createRef would be more problematic, but it is only expected to be created once in the first place, so in practice shouldn't be a problem.

Maybe we should just add an inline comment saying this is technically possible but probably not a concern in practice?

If the ref callback itself changed, most likely this just means it's an arrow functions and has an identical implementation.

I don’t think we can rely on something like this. Otherwise we might as well never update refs.

We handled this correctly so far so I don’t think we should regress in this particular case.

I tried to write a contrived test to catch the case we're talking about, and it looks like I was mistaken to begin with. Even if props are shallowly equal, the memoizedProps and pendingProps objects themselves won't be equal- so we won't bail out- which side steps the issue I mentioned.

Sorry for the dead end. 😄

We chatted a bit with @acdlite and he proposed to check against current.ref. Seems like it wouldn’t hurt but I’ll think about it more tomorrow.

bvaughn

It's interesting how a ref owned by Foo can change without a subsequent did-update lifecycle being called on Foo(but that isn't new from this PR, and was also already the case for refs "forwarded" via props so maybe it's fine).

pull-bot · 2018-04-25T18:18:32Z

ReactDOM: size: 🔺+0.1%, gzip: 🔺+0.1%

Details of bundled changes.

Comparing: 9c77ffb...60ddc00

react-dom

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react-dom.development.js	+0.1%	0.0%	595.56 KB	596.03 KB	137.14 KB	137.18 KB	NODE_DEV
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ReactDOM-prod.js	🔺+0.1%	0.0%	283.99 KB	284.32 KB	51.93 KB	51.93 KB	FB_WWW_PROD

react-art

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react-test-renderer

File	Filesize Diff	Gzip Diff	Prev Size	Current Size	Prev Gzip	Current Gzip	ENV
react-test-renderer.development.js	+0.1%	+0.1%	348.03 KB	348.5 KB	73.21 KB	73.25 KB	UMD_DEV
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ReactTestRenderer-dev.js	+0.1%	0.0%	347.4 KB	347.86 KB	70.15 KB	70.19 KB	FB_WWW_DEV

react-reconciler

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react-reconciler.development.js	+0.1%	+0.1%	319.2 KB	319.67 KB	65.98 KB	66.03 KB	NODE_DEV
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react-reconciler-persistent.development.js	+0.1%	+0.1%	318.53 KB	319 KB	65.75 KB	65.79 KB	NODE_DEV
react-reconciler-persistent.production.min.js	🔺+0.2%	🔺+0.1%	46.16 KB	46.23 KB	14.11 KB	14.12 KB	NODE_PROD

react-native-renderer

File	Filesize Diff	Gzip Diff	Prev Size	Current Size	Prev Gzip	Current Gzip	ENV
ReactNativeRenderer-dev.js	+0.1%	0.0%	459.01 KB	459.48 KB	98.2 KB	98.23 KB	RN_FB_DEV
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ReactFabric-prod.js	🔺+0.2%	0.0%	202.54 KB	202.87 KB	33.67 KB	33.67 KB	RN_OSS_PROD

Generated by 🚫 dangerJS

bvaughn · 2018-04-25T22:05:08Z

packages/react-reconciler/src/ReactFiberBeginWork.js

+    if (hasLegacyContextChanged()) {
+      // Normally we can bail out on props equality but if context has changed
+      // we don't do the bailout and we have to reuse existing props instead.
+    } else if (workInProgress.memoizedProps === nextProps) {


I tried to write a contrived test to catch the case we're talking about, and it looks like I was mistaken to begin with. Even if props are shallowly equal, the memoizedProps and pendingProps objects themselves won't be equal- so we won't bail out- which side steps the issue I mentioned.

Sorry for the dead end. 😄

acdlite

Compare workInProgress.ref to current.ref as discussed offline

bvaughn · 2018-04-26T01:50:20Z

Cool! Agreed it wouldn't hurt, although I can't think of a case where it would currently matter.

nonken · 2018-04-30T19:09:47Z

❤️ awesome fix! When will a new version be released?

gaearon · 2018-04-30T20:46:54Z

Hopefully soon

slorber · 2018-05-01T13:58:35Z

Great! just encountered this bug where my "middle" component renders for unknown reasons after adding forwardRef

gaearon · 2018-05-24T01:23:00Z

Should be fixed in React 16.4.
https://reactjs.org/blog/2018/05/23/react-v-16-4.html

20: Update react monorepo to v16.4.0 r=renovate[bot] a=renovate[bot] This Pull Request renovates the package group "react monorepo". - [react-dom](https://github.com/facebook/react) (`dependencies`): from `16.3.2` to `16.4.0` - [react](https://github.com/facebook/react) (`dependencies`): from `16.3.2` to `16.4.0` # Release Notes <details> <summary>facebook/react</summary> ### [`v16.4.0`](https://github.com/facebook/react/blob/master/CHANGELOG.md#1640-May-23-2018) [Compare Source](facebook/react@8e5f12c...v16.4.0) ##### React * Add a new [experimental](`reactjs/rfcs#51) `React.unstable_Profiler` component for measuring performance. ([@bvaughn] in [#12745](`facebook/react#12745)) ##### React DOM * Add support for the Pointer Events specification. ([@philipp-spiess] in [#12507](`facebook/react#12507)) * Properly call `getDerivedStateFromProps()` regardless of the reason for re-rendering. ([@acdlite] in [#12600](`facebook/react#12600) and [#12802](`facebook/react#12802)) * Fix a bug that prevented context propagation in some cases. ([@gaearon] in [#12708](`facebook/react#12708)) * Fix re-rendering of components using `forwardRef()` on a deeper `setState()`. ([@gaearon] in [#12690](`facebook/react#12690)) * Fix some attributes incorrectly getting removed from custom element nodes. ([@airamrguez] in [#12702](`facebook/react#12702)) * Fix context providers to not bail out on children if there's a legacy context provider above. ([@gaearon] in [#12586](`facebook/react#12586)) * Add the ability to specify `propTypes` on a context provider component. ([@nicolevy] in [#12658](`facebook/react#12658)) * Fix a false positive warning when using `react-lifecycles-compat` in `<StrictMode>`. ([@bvaughn] in [#12644](`facebook/react#12644)) * Warn when the `forwardRef()` render function has `propTypes` or `defaultProps`. ([@bvaughn] in [#12644](`facebook/react#12644)) * Improve how `forwardRef()` and context consumers are displayed in the component stack. ([@sophiebits] in [#12777](`facebook/react#12777)) * Change internal event names. This can break third-party packages that rely on React internals in unsupported ways. ([@philipp-spiess] in [#12629](`facebook/react#12629)) ##### React Test Renderer * Fix the `getDerivedStateFromProps()` support to match the new React DOM behavior. ([@koba04] in [#12676](`facebook/react#12676)) * Fix a `testInstance.parent` crash when the parent is a fragment or another special node. ([@gaearon] in [#12813](`facebook/react#12813)) * `forwardRef()` components are now discoverable by the test renderer traversal methods. ([@gaearon] in [#12725](`facebook/react#12725)) * Shallow renderer now ignores `setState()` updaters that return `null` or `undefined`. ([@koba04] in [#12756](`facebook/react#12756)) ##### React ART * Fix reading context provided from the tree managed by React DOM. ([@acdlite] in [#12779](`facebook/react#12779)) ##### React Call Return (Experimental) * This experiment was deleted because it was affecting the bundle size and the API wasn't good enough. It's likely to come back in the future in some other form. ([@gaearon] in [#12820](`facebook/react#12820)) ##### React Reconciler (Experimental) * The [new host config shape](https://github.com/facebook/react/blob/c601f7a64640290af85c9f0e33c78480656b46bc/packages/react-noop-renderer/src/createReactNoop.js#L82-L285) is flat and doesn't use nested objects. ([@gaearon] in [#12792](`facebook/react#12792)) --- </details> --- This PR has been generated by [Renovate Bot](https://renovatebot.com). Co-authored-by: Renovate Bot <bot@renovateapp.com>

164: Update react monorepo to v16.4.0 r=rehandalal a=renovate[bot] This Pull Request renovates the package group "react monorepo". - [react-dom](https://github.com/facebook/react) (`dependencies`): from `16.3.2` to `16.4.0` - [react](https://github.com/facebook/react) (`dependencies`): from `16.3.2` to `16.4.0` # Release Notes <details> <summary>facebook/react</summary> ### [`v16.4.0`](https://github.com/facebook/react/blob/master/CHANGELOG.md#1640-May-23-2018) [Compare Source](facebook/react@8e5f12c...v16.4.0) ##### React * Add a new [experimental](`reactjs/rfcs#51) `React.unstable_Profiler` component for measuring performance. ([@bvaughn] in [#12745](`facebook/react#12745)) ##### React DOM * Add support for the Pointer Events specification. ([@philipp-spiess] in [#12507](`facebook/react#12507)) * Properly call `getDerivedStateFromProps()` regardless of the reason for re-rendering. ([@acdlite] in [#12600](`facebook/react#12600) and [#12802](`facebook/react#12802)) * Fix a bug that prevented context propagation in some cases. ([@gaearon] in [#12708](`facebook/react#12708)) * Fix re-rendering of components using `forwardRef()` on a deeper `setState()`. ([@gaearon] in [#12690](`facebook/react#12690)) * Fix some attributes incorrectly getting removed from custom element nodes. ([@airamrguez] in [#12702](`facebook/react#12702)) * Fix context providers to not bail out on children if there's a legacy context provider above. ([@gaearon] in [#12586](`facebook/react#12586)) * Add the ability to specify `propTypes` on a context provider component. ([@nicolevy] in [#12658](`facebook/react#12658)) * Fix a false positive warning when using `react-lifecycles-compat` in `<StrictMode>`. ([@bvaughn] in [#12644](`facebook/react#12644)) * Warn when the `forwardRef()` render function has `propTypes` or `defaultProps`. ([@bvaughn] in [#12644](`facebook/react#12644)) * Improve how `forwardRef()` and context consumers are displayed in the component stack. ([@sophiebits] in [#12777](`facebook/react#12777)) * Change internal event names. This can break third-party packages that rely on React internals in unsupported ways. ([@philipp-spiess] in [#12629](`facebook/react#12629)) ##### React Test Renderer * Fix the `getDerivedStateFromProps()` support to match the new React DOM behavior. ([@koba04] in [#12676](`facebook/react#12676)) * Fix a `testInstance.parent` crash when the parent is a fragment or another special node. ([@gaearon] in [#12813](`facebook/react#12813)) * `forwardRef()` components are now discoverable by the test renderer traversal methods. ([@gaearon] in [#12725](`facebook/react#12725)) * Shallow renderer now ignores `setState()` updaters that return `null` or `undefined`. ([@koba04] in [#12756](`facebook/react#12756)) ##### React ART * Fix reading context provided from the tree managed by React DOM. ([@acdlite] in [#12779](`facebook/react#12779)) ##### React Call Return (Experimental) * This experiment was deleted because it was affecting the bundle size and the API wasn't good enough. It's likely to come back in the future in some other form. ([@gaearon] in [#12820](`facebook/react#12820)) ##### React Reconciler (Experimental) * The [new host config shape](https://github.com/facebook/react/blob/c601f7a64640290af85c9f0e33c78480656b46bc/packages/react-noop-renderer/src/createReactNoop.js#L82-L285) is flat and doesn't use nested objects. ([@gaearon] in [#12792](`facebook/react#12792)) --- </details> --- This PR has been generated by [Renovate Bot](https://renovatebot.com). Co-authored-by: Renovate Bot <bot@renovateapp.com>

nonken · 2018-05-24T13:25:42Z

Woot woot @gaearon

gaearon added 2 commits April 25, 2018 19:03

Add a failing test for forwardRef memoization

876298f

Memoize forwardRef props and bail out on strict equality

e3fdd87

gaearon requested review from bvaughn, sebmarkbage and acdlite April 25, 2018 18:09

facebook-github-bot added the CLA Signed label Apr 25, 2018

bvaughn reviewed Apr 25, 2018

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Bail out only when ref matches the current ref

60ddc00

gaearon merged commit d883d59 into facebook:master Apr 26, 2018

gaearon deleted the forward-memoize branch April 26, 2018 18:47

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forwardRef causes componentWillReceiveProps after setState #12736

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forwardRef() components should not re-render on deep setState() #12690

forwardRef() components should not re-render on deep setState() #12690

gaearon commented Apr 25, 2018

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forwardRef() components should not re-render on deep setState() #12690

forwardRef() components should not re-render on deep setState() #12690

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