[Fizz] Batch Suspense Boundary Reveal with Throttle #33076
Merged
Conversation
This file contains hidden or 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
github-actions
bot
added
the
React Core Team
|
One thing that needs to be resolved is how to deal with #31620 because it assumes that these are synchronously evaluated before the content loads. I think that solution has an existing problem though because a stylesheet can also block reveal, which will allow client rendering. That commit is likely itself blocked on the same stylesheet loading though. Once it commits it'll replace the SSR content that has also already streamed in which it really shouldn't ideally and may have consequences for View Transitions. Follow up here #33087. |
gnoff
approved these changes
May 1, 2025
| @@ -5217,10 +5217,19 @@ function flushCompletedQueues( | |||
| ); | |||
| flushSegment(request, destination, completedRootSegment, null); | |||
| request.completedRootSegment = null; | |||
| const isComplete = | |||
| request.allPendingTasks === 0 && | |||
| request.pingedTasks.length === 0 && | |||
There was a problem hiding this comment.
remove here and in finally of flushCompletedQueues
This is implied by the allPendingTasks check
sebmarkbage
added a commit
that referenced
this pull request
May 1, 2025
Stacked on #33076. This fixes a bug where we used the "complete" status but the DOMContentLoaded event. This checks for not "loading" instead. We also add a new status where the boundary has been marked as complete by the server but has not yet flushed either due to being throttled, suspended on CSS or animating.
github-actions bot
pushed a commit
that referenced
this pull request
May 1, 2025
Stacked on #33073. React semantics is that Suspense boundaries reveal with a throttle (300ms). That helps avoid flashing reveals when a stream reveals many individual steps back to back. It can also improve overall performance by batching the layout and paint work that has to happen at each step. Unfortunately we never implemented this for SSR streaming - only for client navigations. This is highly noticeable on very dynamic sites with lots of Suspense boundaries. It can look good with a client nav but feel glitchy when you reload the page or initial load. This fixes the Fizz runtime to be throttled and reveals batched into a single paint at a time. We do this by first tracking the last paint after the complete (this will be the first paint if `rel="expect"` is respected). Then in the `completeBoundary` operation we queue the operation and then flush it all into a throttled batch. Another motivation is that View Transitions need to operate as a batch and individual steps get queued in a sequence so it's extra important to include as much content as possible in each animated step. This will be done in a follow up for SSR View Transitions. DiffTrain build for [ee7fee8](ee7fee8)
github-actions bot
pushed a commit
that referenced
this pull request
May 1, 2025
Stacked on #33076. This fixes a bug where we used the "complete" status but the DOMContentLoaded event. This checks for not "loading" instead. We also add a new status where the boundary has been marked as complete by the server but has not yet flushed either due to being throttled, suspended on CSS or animating. DiffTrain build for [0ed6ceb](0ed6ceb)
github-actions bot
pushed a commit
that referenced
this pull request
May 1, 2025
Stacked on #33076. This fixes a bug where we used the "complete" status but the DOMContentLoaded event. This checks for not "loading" instead. We also add a new status where the boundary has been marked as complete by the server but has not yet flushed either due to being throttled, suspended on CSS or animating. DiffTrain build for [0ed6ceb](0ed6ceb)
This was referenced May 2, 2025
This was referenced May 12, 2025
This was referenced May 19, 2025
17 tasks
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.
Stacked on #33073.
React semantics is that Suspense boundaries reveal with a throttle (300ms). That helps avoid flashing reveals when a stream reveals many individual steps back to back. It can also improve overall performance by batching the layout and paint work that has to happen at each step.
Unfortunately we never implemented this for SSR streaming - only for client navigations. This is highly noticeable on very dynamic sites with lots of Suspense boundaries. It can look good with a client nav but feel glitchy when you reload the page or initial load.
This fixes the Fizz runtime to be throttled and reveals batched into a single paint at a time. We do this by first tracking the last paint after the complete (this will be the first paint if
rel="expect"is respected). Then in thecompleteBoundaryoperation we queue the operation and then flush it all into a throttled batch.Another motivation is that View Transitions need to operate as a batch and individual steps get queued in a sequence so it's extra important to include as much content as possible in each animated step. This will be done in a follow up for SSR View Transitions.