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[Flight] Start initial work immediately #30961

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merged 1 commit into from
Sep 14, 2024

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@gnoff gnoff commented Sep 13, 2024

In a past update we made render and prerender have different work scheduling behavior because these methods are meant to be used in differeent environments with different performance tradeoffs in mind. For instance to prioritize streaming we want to allow as much IO to complete before triggering a round of work because we want to flush as few intermediate UI states. With Prerendering there will never be any intermediate UI states so we can more aggressively render tasks as they complete.

One thing we've found is that even during render we should ideally kick off work immediately. This update normalizes the intitial work for render and prerender to start in a microtask. Choosing microtask over sync is somewhat arbitrary but there really isn't a reason to make them different between render/prerender so for now we'll unify them and keep it as a microtask for now.

This change also updates pinging behavior. If the request is still in the initial task that spawned it then pings will schedule on the microtask queue. This allows immediately available async APIs to resolve right away. The concern with doing this for normal pings is that it might crowd out IO events but since this is the initial task there would be IO to already be scheduled.

In a past update we made render and prerender have different work scheduling behavior because these methods are meant to be used in differeent environments with different performance tradeoffs in mind. For instance to prioritize streaming we want to allow as much IO to complete before triggering a round of work because we want to flush as few intermediate UI states. With Prerendering there will never be any intermediate UI states so we can more aggressively render tasks as they complete.

One thing we've found is that even during render we should ideally kick off work immediately. This update normalizes the intitial work for render and prerender to start in a microtask. Choosing microtask over sync is somewhat arbitrary but there really isn't a reason to make them different between render/prerender so for now we'll unify them and keep it as a microtask for now.

This change also updates pinging behavior. If the request is still in the initial task that spawned it then pings will schedule on the microtask queue. This allows immediately available async APIs to resolve right away. The concern with doing this for normal pings is that it might crowd out IO events but since this is the initial task there would be IO to already be scheduled.
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@@ -1794,7 +1795,7 @@ function pingTask(request: Request, task: Task): void {
pingedTasks.push(task);
if (pingedTasks.length === 1) {
request.flushScheduled = request.destination !== null;
if (request.type === PRERENDER) {
if (request.type === PRERENDER || request.status === OPENING) {
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Maybe we can unify the prerender path here and avoid the double conditional?

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Comparing: 6774caa...77116a8

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name +/- Base Current +/- gzip Base gzip Current gzip
oss-stable/react-dom/cjs/react-dom.production.js = 6.68 kB 6.68 kB = 1.83 kB 1.83 kB
oss-stable/react-dom/cjs/react-dom-client.production.js = 509.13 kB 509.13 kB = 91.08 kB 91.08 kB
oss-experimental/react-dom/cjs/react-dom.production.js = 6.69 kB 6.69 kB = 1.83 kB 1.83 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js = 514.10 kB 514.06 kB = 91.80 kB 91.80 kB
facebook-www/ReactDOM-prod.classic.js = 604.68 kB 604.67 kB = 106.85 kB 106.85 kB
facebook-www/ReactDOM-prod.modern.js = 580.95 kB 580.95 kB = 103.00 kB 103.00 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against ec9a2f8

@gnoff gnoff merged commit fc5ef50 into facebook:main Sep 14, 2024
184 checks passed
@gnoff gnoff deleted the flight-start-work-immediately branch September 14, 2024 16:26
github-actions bot pushed a commit that referenced this pull request Sep 14, 2024
In a past update we made render and prerender have different work
scheduling behavior because these methods are meant to be used in
differeent environments with different performance tradeoffs in mind.
For instance to prioritize streaming we want to allow as much IO to
complete before triggering a round of work because we want to flush as
few intermediate UI states. With Prerendering there will never be any
intermediate UI states so we can more aggressively render tasks as they
complete.

One thing we've found is that even during render we should ideally kick
off work immediately. This update normalizes the intitial work for
render and prerender to start in a microtask. Choosing microtask over
sync is somewhat arbitrary but there really isn't a reason to make them
different between render/prerender so for now we'll unify them and keep
it as a microtask for now.

This change also updates pinging behavior. If the request is still in
the initial task that spawned it then pings will schedule on the
microtask queue. This allows immediately available async APIs to resolve
right away. The concern with doing this for normal pings is that it
might crowd out IO events but since this is the initial task there would
be IO to already be scheduled.

DiffTrain build for [fc5ef50](fc5ef50)
gnoff added a commit that referenced this pull request Sep 26, 2024
In a recent update we make Flight start working immediately rather than
waitin for a new task. This commit updates fizz to have similar
mechanics. We start the render in the currently running task but we do
so in a microtask to avoid reentrancy. This aligns Fizz with Flight.

ref: #30961
github-actions bot pushed a commit that referenced this pull request Sep 26, 2024
In a recent update we make Flight start working immediately rather than
waitin for a new task. This commit updates fizz to have similar
mechanics. We start the render in the currently running task but we do
so in a microtask to avoid reentrancy. This aligns Fizz with Flight.

ref: #30961

DiffTrain build for [67fee58](67fee58)
github-actions bot pushed a commit that referenced this pull request Sep 26, 2024
In a recent update we make Flight start working immediately rather than
waitin for a new task. This commit updates fizz to have similar
mechanics. We start the render in the currently running task but we do
so in a microtask to avoid reentrancy. This aligns Fizz with Flight.

ref: #30961

DiffTrain build for [67fee58](67fee58)
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4 participants