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Scheduling Profiler does not warn about long transitions (facebook#22614
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Brian Vaughn authored and zhengjitf committed Apr 15, 2022
1 parent 3b16cd9 commit 1048b02
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Original file line number Diff line number Diff line change
Expand Up @@ -1601,6 +1601,143 @@ describe('preprocessData', () => {
);
}
});

it('should not warn about transition updates scheduled during commit phase', async () => {
function Component() {
const [value, setValue] = React.useState(0);
// eslint-disable-next-line no-unused-vars
const [isPending, startTransition] = React.useTransition();

Scheduler.unstable_yieldValue(
`Component rendered with value ${value}`,
);

// Fake a long render
if (value !== 0) {
Scheduler.unstable_yieldValue('Long render');
startTime += 20000;
}

React.useLayoutEffect(() => {
startTransition(() => {
setValue(1);
});
}, []);

return value;
}

if (gate(flags => flags.enableSchedulingProfiler)) {
const cpuProfilerSample = creactCpuProfilerSample();

const root = ReactDOM.createRoot(document.createElement('div'));
act(() => {
root.render(<Component />);
});

expect(Scheduler).toHaveYielded([
'Component rendered with value 0',
'Component rendered with value 0',
'Component rendered with value 1',
'Long render',
]);

const testMarks = [];
clearedMarks.forEach(markName => {
if (markName === '--component-render-start-Component') {
// Fake a long running render
startTime += 20000;
}

testMarks.push({
pid: ++pid,
tid: ++tid,
ts: ++startTime,
args: {data: {}},
cat: 'blink.user_timing',
name: markName,
ph: 'R',
});
});

const data = await preprocessData([
cpuProfilerSample,
...createBoilerplateEntries(),
...testMarks,
]);

data.schedulingEvents.forEach(event => {
expect(event.warning).toBeNull();
});
}
});

it('should not warn about deferred value updates scheduled during commit phase', async () => {
function Component() {
const [value, setValue] = React.useState(0);
const deferredValue = React.useDeferredValue(value);

Scheduler.unstable_yieldValue(
`Component rendered with value ${value} and deferredValue ${deferredValue}`,
);

// Fake a long render
if (deferredValue !== 0) {
Scheduler.unstable_yieldValue('Long render');
startTime += 20000;
}

React.useLayoutEffect(() => {
setValue(1);
}, []);

return value + deferredValue;
}

if (gate(flags => flags.enableSchedulingProfiler)) {
const cpuProfilerSample = creactCpuProfilerSample();

const root = ReactDOM.createRoot(document.createElement('div'));
act(() => {
root.render(<Component />);
});

expect(Scheduler).toHaveYielded([
'Component rendered with value 0 and deferredValue 0',
'Component rendered with value 1 and deferredValue 0',
'Component rendered with value 1 and deferredValue 1',
'Long render',
]);

const testMarks = [];
clearedMarks.forEach(markName => {
if (markName === '--component-render-start-Component') {
// Fake a long running render
startTime += 20000;
}

testMarks.push({
pid: ++pid,
tid: ++tid,
ts: ++startTime,
args: {data: {}},
cat: 'blink.user_timing',
name: markName,
ph: 'R',
});
});

const data = await preprocessData([
cpuProfilerSample,
...createBoilerplateEntries(),
...testMarks,
]);

data.schedulingEvents.forEach(event => {
expect(event.warning).toBeNull();
});
}
});
});

describe('errors thrown while rendering', () => {
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Original file line number Diff line number Diff line change
Expand Up @@ -1160,7 +1160,16 @@ export default async function preprocessData(
// See how long the subsequent batch of React work was.
const [startTime, stopTime] = getBatchRange(batchUID, profilerData);
if (stopTime - startTime > NESTED_UPDATE_DURATION_THRESHOLD) {
schedulingEvent.warning = WARNING_STRINGS.NESTED_UPDATE;
// Don't warn about transition updates scheduled during the commit phase.
// e.g. useTransition, useDeferredValue
// These are allowed to be long-running.
if (
!schedulingEvent.lanes.some(
lane => profilerData.laneToLabelMap.get(lane) === 'Transition',
)
) {
schedulingEvent.warning = WARNING_STRINGS.NESTED_UPDATE;
}
}
});
state.potentialSuspenseEventsOutsideOfTransition.forEach(
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