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https://github.com/facebook/react.git
synced 2025-11-01 09:12:30 +00:00
Samuel Susla
2cd3c424ea
This is a fix for a problem where React retains shadow nodes longer than it needs to. The behaviour is shown in React Native test: https://github.com/facebook/react-native/blob/main/packages/react-native/src/private/__tests__/utilities/__tests__/ShadowNodeReferenceCounter-itest.js#L169 When React commits a new shadow tree, old shadow nodes are stored inside `fiber.alternate.stateNode`. This is not cleared up until React clones the node again. This may be problematic if mutation deletes a subtree, in that case `fiber.alternate.stateNode` will retain entire subtree until next update. In case of image nodes, this means retaining entire images. So when React goes from revision A: `<View><View /></View>` to revision B: `<View />`, `fiber.alternate.stateNode` will be pointing to Shadow Node that represents revision A..  To fix this, this PR adds a new feature flag `enableEagerAlternateStateNodeCleanup`. When enabled, `alternate.stateNode` is proactively pointed towards finishedWork's stateNode, releasing resources sooner. I have verified this fixes the issue [demonstrated by React Native tests](https://github.com/facebook/react-native/blob/main/packages/react-native/src/private/__tests__/utilities/__tests__/ShadowNodeReferenceCounter-itest.js#L169). All existing React tests pass when the flag is enabled.
36 lines
1.5 KiB
JavaScript
36 lines
1.5 KiB
JavaScript
/**
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow strict
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*/
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// In xplat, these flags are controlled by GKs. Because most GKs have some
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// population running in either mode, we should run our tests that way, too,
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//
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// Use __VARIANT__ to simulate a GK. The tests will be run twice: once
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// with the __VARIANT__ set to `true`, and once set to `false`.
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//
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// TODO: __VARIANT__ isn't supported for React Native flags yet. You can set the
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// flag here but it won't be set to `true` in any of our test runs. Need to
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// add a test configuration for React Native.
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export const alwaysThrottleRetries = __VARIANT__;
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export const enableObjectFiber = __VARIANT__;
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export const enableHiddenSubtreeInsertionEffectCleanup = __VARIANT__;
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export const enablePersistedModeClonedFlag = __VARIANT__;
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export const enableShallowPropDiffing = __VARIANT__;
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export const enableEagerAlternateStateNodeCleanup = __VARIANT__;
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export const passChildrenWhenCloningPersistedNodes = __VARIANT__;
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export const enableSiblingPrerendering = __VARIANT__;
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export const enableUseEffectCRUDOverload = __VARIANT__;
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export const enableFastAddPropertiesInDiffing = __VARIANT__;
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export const enableLazyPublicInstanceInFabric = __VARIANT__;
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export const renameElementSymbol = __VARIANT__;
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export const ownerStackLimit: number = __VARIANT__
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? // Some value that doesn't impact existing tests
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500
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: 1e4;
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