[Bugfix] Infinite uDV loop in popstate event #32821
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Found a bug that occurs during a specific combination of very subtle implementation details. It occurs sometimes (not always) when 1) a transition is scheduled during a popstate event, and 2) as a result, a new value is passed to an already-mounted useDeferredValue hook. The fix is relatively straightforward, and I found it almost immediately; it took a bit longer to figure out exactly how the scenario occurred in production and create a test case to simulate it. Rather than couple the test to the implementation details, I've chosen to keep it as high-level as possible so that it doesn't break if the details change. In the future, it might not be trigger the exact set of internal circumstances anymore, but it could be useful for catching similar bugs because it represents a realistic real world situation — namely, switching tabs repeatedly in an app that uses useDeferredValue.
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Comparing: efb22d8...64acfd5 Critical size changesIncludes critical production bundles, as well as any change greater than 2%:
Significant size changesIncludes any change greater than 0.2%: (No significant changes) |
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Found a bug that occurs during a specific combination of very subtle implementation details. It occurs sometimes (not always) when 1) a transition is scheduled during a popstate event, and 2) as a result, a new value is passed to an already-mounted useDeferredValue hook. The fix is relatively straightforward, and I found it almost immediately; it took a bit longer to figure out exactly how the scenario occurred in production and create a test case to simulate it. Rather than couple the test to the implementation details, I've chosen to keep it as high-level as possible so that it doesn't break if the details change. In the future, it might not be trigger the exact set of internal circumstances anymore, but it could be useful for catching similar bugs because it represents a realistic real world situation — namely, switching tabs repeatedly in an app that uses useDeferredValue. DiffTrain build for [6a7650c](6a7650c)
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Found a bug that occurs during a specific combination of very subtle implementation details. It occurs sometimes (not always) when 1) a transition is scheduled during a popstate event, and 2) as a result, a new value is passed to an already-mounted useDeferredValue hook. The fix is relatively straightforward, and I found it almost immediately; it took a bit longer to figure out exactly how the scenario occurred in production and create a test case to simulate it. Rather than couple the test to the implementation details, I've chosen to keep it as high-level as possible so that it doesn't break if the details change. In the future, it might not be trigger the exact set of internal circumstances anymore, but it could be useful for catching similar bugs because it represents a realistic real world situation — namely, switching tabs repeatedly in an app that uses useDeferredValue. DiffTrain build for [6a7650c](6a7650c)
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<details> <summary>React upstream changes</summary> - facebook/react#32821 - facebook/react#32819 - facebook/react#32816 - facebook/react#32815 - facebook/react#32812 - facebook/react#32762 - facebook/react#32808 - facebook/react#32807 </details>
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5167170015919920 |
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This is such a good catch! I've been noticing this in next v15.3.0-canary.38. I only noticed it when the React DevTools extension was enabled. My suspicion was that it slowed down fiber enough for this to be more likely to occur. |
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[diff facebook/react@040f8286...33661467](facebook/react@040f828...3366146) <details> <summary>React upstream changes</summary> - facebook/react#32823 - facebook/react#32822 - facebook/react#32825 - facebook/react#32821 - facebook/react#32819 - facebook/react#32816 - facebook/react#32815 - facebook/react#32812 - facebook/react#32762 - facebook/react#32808 - facebook/react#32807 </details>
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This includes a React bugfix to popstate transitions. (See: facebook/react#32821.) Seems to fix the crashes on back/forward we were seeing.
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[diff facebook/react@040f8286...33661467](facebook/react@040f828...3366146) <details> <summary>React upstream changes</summary> - facebook/react#32823 - facebook/react#32822 - facebook/react#32825 - facebook/react#32821 - facebook/react#32819 - facebook/react#32816 - facebook/react#32815 - facebook/react#32812 - facebook/react#32762 - facebook/react#32808 - facebook/react#32807 </details>
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Found a bug that occurs during a specific combination of very subtle implementation details.
It occurs sometimes (not always) when 1) a transition is scheduled during a popstate event, and 2) as a result, a new value is passed to an already-mounted useDeferredValue hook.
The fix is relatively straightforward, and I found it almost immediately; it took a bit longer to figure out exactly how the scenario occurred in production and create a test case to simulate it.
Rather than couple the test to the implementation details, I've chosen to keep it as high-level as possible so that it doesn't break if the details change. In the future, it might not be trigger the exact set of internal circumstances anymore, but it could be useful for catching similar bugs because it represents a realistic real world situation — namely, switching tabs repeatedly in an app that uses useDeferredValue.