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Bugfix: memo drops lower pri updates on bail out - #18091
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Fixes a bug where lower priority updates on a components wrapped with `memo` are sometimes left dangling in the queue without ever being processed, if they are preceded by a higher priority bailout. Cause ----- The pending update priority field is cleared at the beginning of `beginWork`. If there is remaining work at a lower priority level, it's expected that it will be accumulated on the work-in-progress fiber during the begin phase. There's an exception where this assumption doesn't hold: SimpleMemoComponent contains a bailout that occurs *before* the component is evaluated and the update queues are processed, which means we don't accumulate the next priority level. When we complete the fiber, the work loop is left to believe that there's no remaining work. Mitigation ---------- Since this only happens in a single case, a late bailout in SimpleMemoComponent, I've mitigated the bug in that code path by restoring the original update priority from the current fiber. This same case does not apply to MemoComponent, because MemoComponent fibers do not contain hooks or update queues; rather, they wrap around an inner fiber that may contain those. However, I've added a test case for MemoComponent to protect against a possible future regression. Possible next steps ------------------- We should consider moving the update priority assignment in `beginWork` out of the common path and into each branch, to avoid similar bugs in the future.
sizebot
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Feb 20, 2020
Details of bundled changes.Comparing: ea6ed3d...0da64c2 react-dom
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Details of bundled changes.Comparing: ea6ed3d...0da64c2 react-dom
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ReactDOM: size: 0.0%, gzip: 🔺+0.1% Size changes (stable) |
sebmarkbage
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Feb 20, 2020
dai-shi
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Feb 20, 2020
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acdlite
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Feb 21, 2020
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@dai-shi Yes probably. I'll confirm in a sec. |
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Dec 12, 2024
 <h3>Snyk has created this PR to upgrade react-dom from 16.8.4 to 16.14.0.</h3> :information_source: Keep your dependencies up-to-date. This makes it easier to fix existing vulnerabilities and to more quickly identify and fix newly disclosed vulnerabilities when they affect your project. <hr/> - The recommended version is **13 versions** ahead of your current version. - The recommended version was released on **4 years ago**. <details> <summary><b>Release notes</b></summary> <br/> <details> <summary>Package name: <b>react-dom</b></summary> <ul> <li> <b>16.14.0</b> - <a href="https://redirect.github.com/facebook/react/releases/tag/v16.14.0">2020-10-14</a></br><h3>React</h3> <ul> <li>Add support for the <a href="https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html" rel="nofollow">new JSX transform</a>. (<a href="https://redirect.github.com/lunaruan">@ lunaruan</a> in <a href="https://redirect.github.com/facebook/react/pull/18299" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/18299/hovercard">#18299</a>)</li> </ul> </li> <li> <b>16.13.1</b> - <a href="https://redirect.github.com/facebook/react/releases/tag/v16.13.1">2020-03-19</a></br><h3>React DOM</h3> <ul> <li>Fix bug in legacy mode Suspense where effect clean-up functions are not fired. This only affects users who use Suspense for data fetching in legacy mode, which is not technically supported. (<a href="https://redirect.github.com/acdlite">@ acdlite</a> in <a href="https://redirect.github.com/facebook/react/pull/18238" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/18238/hovercard">#18238</a>)</li> <li>Revert warning for cross-component updates that happen inside class render lifecycles (<code>componentWillReceiveProps</code>, <code>shouldComponentUpdate</code>, and so on). (<a href="https://redirect.github.com/gaearon">@ gaearon</a> in <a href="https://redirect.github.com/facebook/react/pull/18330" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/18330/hovercard">#18330</a>)</li> </ul> <h2>Artifacts</h2> <ul> <li>react: <a href="https://unpkg.com/react@16.13.1/umd/" rel="nofollow">https://unpkg.com/react@16.13.1/umd/</a></li> <li>react-art: <a href="https://unpkg.com/react-art@16.13.1/umd/" rel="nofollow">https://unpkg.com/react-art@16.13.1/umd/</a></li> <li>react-dom: <a href="https://unpkg.com/react-dom@16.13.1/umd/" rel="nofollow">https://unpkg.com/react-dom@16.13.1/umd/</a></li> <li>react-is: <a href="https://unpkg.com/react-is@16.13.1/umd/" rel="nofollow">https://unpkg.com/react-is@16.13.1/umd/</a></li> <li>react-test-renderer: <a href="https://unpkg.com/react-test-renderer@16.13.1/umd/" rel="nofollow">https://unpkg.com/react-test-renderer@16.13.1/umd/</a></li> <li>scheduler: <a href="https://unpkg.com/scheduler@0.19.1/umd/" rel="nofollow">https://unpkg.com/scheduler@0.19.1/umd/</a></li> </ul> </li> <li> <b>16.13.0</b> - <a href="https://redirect.github.com/facebook/react/releases/tag/v16.13.0">2020-02-26</a></br><h3>React</h3> <ul> <li>Warn when a string ref is used in a manner that's not amenable to a future codemod (<a href="https://redirect.github.com/lunaruan">@ lunaruan</a> in <a href="https://redirect.github.com/facebook/react/pull/17864" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17864/hovercard">#17864</a>)</li> <li>Deprecate <code>React.createFactory()</code> (<a href="https://redirect.github.com/trueadm">@ trueadm</a> in <a href="https://redirect.github.com/facebook/react/pull/17878" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17878/hovercard">#17878</a>)</li> </ul> <h3>React DOM</h3> <ul> <li>Warn when changes in <code>style</code> may cause an unexpected collision (<a href="https://redirect.github.com/sophiebits">@ sophiebits</a> in <a href="https://redirect.github.com/facebook/react/pull/14181" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/14181/hovercard">#14181</a>, <a href="https://redirect.github.com/facebook/react/pull/18002" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/18002/hovercard">#18002</a>)</li> <li>Warn when a function component is updated during another component's render phase (<a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/acdlite/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://redirect.github.com/acdlite">@ acdlite</a> in <a href="https://redirect.github.com/facebook/react/pull/17099" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17099/hovercard">#17099</a>)</li> <li>Deprecate <code>unstable_createPortal</code> (<a href="https://redirect.github.com/trueadm">@ trueadm</a> in <a href="https://redirect.github.com/facebook/react/pull/17880" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17880/hovercard">#17880</a>)</li> <li>Fix <code>onMouseEnter</code> being fired on disabled buttons (<a href="https://redirect.github.com/AlfredoGJ">@ AlfredoGJ</a> in <a href="https://redirect.github.com/facebook/react/pull/17675" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17675/hovercard">#17675</a>)</li> <li>Call <code>shouldComponentUpdate</code> twice when developing in <code>StrictMode</code> (<a href="https://redirect.github.com/bvaughn">@ bvaughn</a> in <a href="https://redirect.github.com/facebook/react/pull/17942" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17942/hovercard">#17942</a>)</li> <li>Add <code>version</code> property to ReactDOM (<a href="https://redirect.github.com/ealush">@ ealush</a> in <a href="https://redirect.github.com/facebook/react/pull/15780" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/15780/hovercard">#15780</a>)</li> <li>Don't call <code>toString()</code> of <code>dangerouslySetInnerHTML</code> (<a href="https://redirect.github.com/sebmarkbage">@ sebmarkbage</a> in <a href="https://redirect.github.com/facebook/react/pull/17773" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17773/hovercard">#17773</a>)</li> <li>Show component stacks in more warnings (<a href="https://redirect.github.com/gaearon">@ gaearon</a> in <a href="https://redirect.github.com/facebook/react/pull/17922" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17922/hovercard">#17922</a>, <a href="https://redirect.github.com/facebook/react/pull/17586" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17586/hovercard">#17586</a>)</li> </ul> <h3>Concurrent Mode (Experimental)</h3> <ul> <li>Warn for problematic usages of <code>ReactDOM.createRoot()</code> (<a href="https://redirect.github.com/trueadm">@ trueadm</a> in <a href="https://redirect.github.com/facebook/react/pull/17937" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17937/hovercard">#17937</a>)</li> <li>Remove <code>ReactDOM.createRoot()</code> callback params and added warnings on usage (<a href="https://redirect.github.com/bvaughn">@ bvaughn</a> in <a href="https://redirect.github.com/facebook/react/pull/17916" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17916/hovercard">#17916</a>)</li> <li>Don't group Idle/Offscreen work with other work (<a href="https://redirect.github.com/sebmarkbage">@ sebmarkbage</a> in <a href="https://redirect.github.com/facebook/react/pull/17456" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17456/hovercard">#17456</a>)</li> <li>Adjust <code>SuspenseList</code> CPU bound heuristic (<a href="https://redirect.github.com/sebmarkbage">@ sebmarkbage</a> in <a href="https://redirect.github.com/facebook/react/pull/17455" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17455/hovercard">#17455</a>)</li> <li>Add missing event plugin priorities (<a href="https://redirect.github.com/trueadm">@ trueadm</a> in <a href="https://redirect.github.com/facebook/react/pull/17914" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17914/hovercard">#17914</a>)</li> <li>Fix <code>isPending</code> only being true when transitioning from inside an input event (<a href="https://redirect.github.com/acdlite">@ acdlite</a> in <a href="https://redirect.github.com/facebook/react/pull/17382" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17382/hovercard">#17382</a>)</li> <li>Fix <code>React.memo</code> components dropping updates when interrupted by a higher priority update (<a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/acdlite/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://redirect.github.com/acdlite">@ acdlite</a> in <a href="https://redirect.github.com/facebook/react/pull/18091" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/18091/hovercard">#18091</a>)</li> <li>Don't warn when suspending at the wrong priority (<a href="https://redirect.github.com/gaearon">@ gaearon</a> in <a href="https://redirect.github.com/facebook/react/pull/17971" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17971/hovercard">#17971</a>)</li> <li>Fix a bug with rebasing updates (<a href="https://redirect.github.com/acdlite">@ acdlite</a> and <a href="https://redirect.github.com/sebmarkbage">@ sebmarkbage</a> in <a href="https://redirect.github.com/facebook/react/pull/17560" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17560/hovercard">#17560</a>, <a href="https://redirect.github.com/facebook/react/pull/17510" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17510/hovercard">#17510</a>, <a href="https://redirect.github.com/facebook/react/pull/17483" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17483/hovercard">#17483</a>, <a href="https://redirect.github.com/facebook/react/pull/17480" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17480/hovercard">#17480</a>)</li> </ul> <h2>Artifacts</h2> <ul> <li>react: <a href="https://unpkg.com/react@16.13.0/umd/" rel="nofollow">https://unpkg.com/react@16.13.0/umd/</a></li> <li>react-art: <a href="https://unpkg.com/react-art@16.13.0/umd/" rel="nofollow">https://unpkg.com/react-art@16.13.0/umd/</a></li> <li>react-dom: <a href="https://unpkg.com/react-dom@16.13.0/umd/" rel="nofollow">https://unpkg.com/react-dom@16.13.0/umd/</a></li> <li>react-is: <a href="https://unpkg.com/react-is@16.13.0/umd/" rel="nofollow">https://unpkg.com/react-is@16.13.0/umd/</a></li> <li>react-test-renderer: <a href="https://unpkg.com/react-test-renderer@16.13.0/umd/" rel="nofollow">https://unpkg.com/react-test-renderer@16.13.0/umd/</a></li> <li>scheduler: <a href="https://unpkg.com/scheduler@0.19.0/umd/" rel="nofollow">https://unpkg.com/scheduler@0.19.0/umd/</a></li> </ul> </li> <li> <b>16.12.0</b> - <a href="https://redirect.github.com/facebook/react/releases/tag/v16.12.0">2019-11-14</a></br><h3>React DOM</h3> <ul> <li>Fix passive effects (<code>useEffect</code>) not being fired in a multi-root app. (<a href="https://redirect.github.com/acdlite">@ acdlite</a> in <a href="https://redirect.github.com/facebook/react/pull/17347" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17347/hovercard">#17347</a>)</li> </ul> <h3>React Is</h3> <ul> <li>Fix <code>lazy</code> and <code>memo</code> types considered elements instead of components (<a href="https://redirect.github.com/bvaughn">@ bvaughn</a> in <a href="https://redirect.github.com/facebook/react/pull/17278" data-hovercard-type="pull_request" data-hovercard-url="/react/react/pull/17278/hovercard">#17278</a>)</li> </ul> <h2>Artifacts</h2> <p>• react: <a href="https://unpkg.com/react@16.12.0/umd/" rel="nofollow">https://unpkg.com/react@16.12.0/umd/</a><br> • react-art: <a href="https://unpkg.com/react-art@16.12.0/umd/" rel="nofollow">https://unpkg.com/react-art@16.12.0/umd/</a><br> • react-dom: <a href="https://unpkg.com/react-dom@16.12.0/umd/" rel="nofollow">https://unpkg.com/react-dom@16.12.0/umd/</a><br> • react-is: <a href="https://unpkg.com/react-is@16.12.0/umd/" rel="nofollow">https://unpkg.com/react-is@16.12.0/umd/</a><br> • react-test-renderer: <a href="https://unpkg.com/react-test-renderer@16.12.0/umd/" rel="nofollow">https://unpkg.com/react-test-renderer@16.12.0/umd/</a><br> • scheduler: <a href="https://unpkg.com/scheduler@0.18.0/umd/" rel="nofollow">https://unpkg.com/scheduler@0.18.0/umd/</a></p> </li> <li> <b>16.11.0</b> - 2019-10-22 </li> <li> <b>16.10.2</b> - 2019-10-03 </li> <li> <b>16.10.1</b> - 2019-09-28 </li> <li> <b>16.10.0</b> - 2019-09-27 </li> <li> <b>16.9.0</b> - 2019-08-08 </li> <li> <b>16.9.0-rc.0</b> - 2019-08-05 </li> <li> <b>16.9.0-alpha.0</b> - 2019-04-03 </li> <li> <b>16.8.6</b> - 2019-03-28 </li> <li> <b>16.8.5</b> - 2019-03-22 </li> <li> <b>16.8.4</b> - 2019-03-05 </li> </ul> from <a href="https://redirect.github.com/facebook/react/releases">react-dom GitHub release notes</a> </details> </details> --- > [!IMPORTANT] > > - Check the changes in this PR to ensure they won't cause issues with your project. > - This PR was automatically created by Snyk using the credentials of a real user. --- **Note:** _You are seeing this because you or someone else with access to this repository has authorized Snyk to open upgrade PRs._ **For more information:** <img 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mrizwanashiq pushed a commit
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Jun 25, 2026
Fixes a bug where lower priority updates on a components wrapped with `memo` are sometimes left dangling in the queue without ever being processed, if they are preceded by a higher priority bailout. Cause ----- The pending update priority field is cleared at the beginning of `beginWork`. If there is remaining work at a lower priority level, it's expected that it will be accumulated on the work-in-progress fiber during the begin phase. There's an exception where this assumption doesn't hold: SimpleMemoComponent contains a bailout that occurs *before* the component is evaluated and the update queues are processed, which means we don't accumulate the next priority level. When we complete the fiber, the work loop is left to believe that there's no remaining work. Mitigation ---------- Since this only happens in a single case, a late bailout in SimpleMemoComponent, I've mitigated the bug in that code path by restoring the original update priority from the current fiber. This same case does not apply to MemoComponent, because MemoComponent fibers do not contain hooks or update queues; rather, they wrap around an inner fiber that may contain those. However, I've added a test case for MemoComponent to protect against a possible future regression. Possible next steps ------------------- We should consider moving the update priority assignment in `beginWork` out of the common path and into each branch, to avoid similar bugs in the future.
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Fixes a bug where lower priority updates on a components wrapped with
memoare sometimes left dangling in the queue without ever being processed, if they are preceded by a higher priority bailout.Cause
The pending update priority field is cleared at the beginning of
beginWork. If there is remaining work at a lower priority level, it's expected that it will be accumulated on the work-in-progress fiber during the begin phase.There's an exception where this assumption doesn't hold: SimpleMemoComponent contains a bailout that occurs before the component is evaluated and the update queues are processed, which means we don't accumulate the next priority level. When we complete the fiber, the work loop is left to believe that there's no remaining work.
Mitigation
Since this only happens in a single case, a late bailout in SimpleMemoComponent, I've mitigated the bug in that code path by restoring the original update priority from the current fiber.
This same case does not apply to MemoComponent, because MemoComponent fibers do not contain hooks or update queues; rather, they wrap around an inner fiber that may contain those. However, I've added a test case for MemoComponent to protect against a possible future regression.
Possible next steps
We should consider moving the update priority assignment in
beginWorkout of the common path and into each branch, to avoid similar bugs in the future.