useDeferredValue has higher priority than partial hydration #27550
+141
−10
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
By default, partial hydration is given the lowest possible priority, because until a tree is updated, the server-rendered HTML is assumed to match the final resolved HTML. However, this isn't completely true because a component may choose to "upgrade" itself upon hydration. The simplest example is a component that calls setState in a useEffect to switch to a richer implementation of the UI. Another example is a component that doesn't have a server- rendered implementation, so it intentionally suspends to force a client- only render. useDeferredValue is an example, too: the server only renders the first pass (the initialValue) argument, and relies on the client to upgrade to the final value. What we should really do in these cases is emit some information into the Fizz stream so that Fiber knows to prioritize the hydration of certain trees. We plan to add a mechanism for this in the future. In the meantime, though, we can at least ensure that the priority of the upgrade task is correct once it's "discovered" during hydration. In this case, the priority of the task spawned by useDeferredValue should have Transition priority, not Offscreen priority.
facebook-github-bot
added
CLA Signed
React Core Team
acdlite
changed the title
|
Comparing: f172fa7...17e48b1 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) |
gnoff
approved these changes
Oct 23, 2023
github-actions bot
pushed a commit
that referenced
this pull request
Oct 23, 2023
By default, partial hydration is given the lowest possible priority, because until a tree is updated, the server-rendered HTML is assumed to match the final resolved HTML. However, this isn't completely true because a component may choose to "upgrade" itself upon hydration. The simplest example is a component that calls setState in a useEffect to switch to a richer implementation of the UI. Another example is a component that doesn't have a server- rendered implementation, so it intentionally suspends to force a client- only render. useDeferredValue is an example, too: the server only renders the first pass (the initialValue) argument, and relies on the client to upgrade to the final value. What we should really do in these cases is emit some information into the Fizz stream so that Fiber knows to prioritize the hydration of certain trees. We plan to add a mechanism for this in the future. In the meantime, though, we can at least ensure that the priority of the upgrade task is correct once it's "discovered" during hydration. In this case, the priority of the task spawned by useDeferredValue should have Transition priority, not Offscreen priority. DiffTrain build for [779d593](779d593)
acdlite
added a commit
to acdlite/next.js
that referenced
this pull request
Oct 23, 2023
acdlite
added a commit
to acdlite/next.js
that referenced
this pull request
Oct 23, 2023
kodiakhq bot
pushed a commit
to vercel/next.js
that referenced
this pull request
Oct 23, 2023
React upstream changes: - facebook/react#27570 - facebook/react#27569 - facebook/react#27550 - facebook/react#27559 - facebook/react#27552 - facebook/react#27504 - facebook/react#27522 Co-authored-by: Josh Story <2716369+gnoff@users.noreply.github.com>
EdisonVan
pushed a commit
to EdisonVan/react
that referenced
this pull request
Apr 15, 2024
…#27550) By default, partial hydration is given the lowest possible priority, because until a tree is updated, the server-rendered HTML is assumed to match the final resolved HTML. However, this isn't completely true because a component may choose to "upgrade" itself upon hydration. The simplest example is a component that calls setState in a useEffect to switch to a richer implementation of the UI. Another example is a component that doesn't have a server- rendered implementation, so it intentionally suspends to force a client- only render. useDeferredValue is an example, too: the server only renders the first pass (the initialValue) argument, and relies on the client to upgrade to the final value. What we should really do in these cases is emit some information into the Fizz stream so that Fiber knows to prioritize the hydration of certain trees. We plan to add a mechanism for this in the future. In the meantime, though, we can at least ensure that the priority of the upgrade task is correct once it's "discovered" during hydration. In this case, the priority of the task spawned by useDeferredValue should have Transition priority, not Offscreen priority.
bigfootjon
pushed a commit
that referenced
this pull request
Apr 18, 2024
By default, partial hydration is given the lowest possible priority, because until a tree is updated, the server-rendered HTML is assumed to match the final resolved HTML. However, this isn't completely true because a component may choose to "upgrade" itself upon hydration. The simplest example is a component that calls setState in a useEffect to switch to a richer implementation of the UI. Another example is a component that doesn't have a server- rendered implementation, so it intentionally suspends to force a client- only render. useDeferredValue is an example, too: the server only renders the first pass (the initialValue) argument, and relies on the client to upgrade to the final value. What we should really do in these cases is emit some information into the Fizz stream so that Fiber knows to prioritize the hydration of certain trees. We plan to add a mechanism for this in the future. In the meantime, though, we can at least ensure that the priority of the upgrade task is correct once it's "discovered" during hydration. In this case, the priority of the task spawned by useDeferredValue should have Transition priority, not Offscreen priority. DiffTrain build for commit 779d593.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
By default, partial hydration is given the lowest possible priority, because until a tree is updated, the server-rendered HTML is assumed to match the final resolved HTML.
However, this isn't completely true because a component may choose to "upgrade" itself upon hydration. The simplest example is a component that calls setState in a useEffect to switch to a richer implementation of the UI. Another example is a component that doesn't have a server- rendered implementation, so it intentionally suspends to force a client- only render.
useDeferredValue is an example, too: the server only renders the first pass (the initialValue) argument, and relies on the client to upgrade to the final value.
What we should really do in these cases is emit some information into the Fizz stream so that Fiber knows to prioritize the hydration of certain trees. We plan to add a mechanism for this in the future.
In the meantime, though, we can at least ensure that the priority of the upgrade task is correct once it's "discovered" during hydration. In this case, the priority of the task spawned by useDeferredValue should have Transition priority, not Offscreen priority.