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fix(browser): Avoid recording long task spans starting before their parent span #14183

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Merged
merged 4 commits into from
Nov 5, 2024
Merged

fix(browser): Avoid recording long task spans starting before their parent span #14183

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a3acd38
fix(browser): Avoid recording long task spans starting before their p…
Lms24 Nov 5, 2024
6bf0b8f
add regression test
Lms24 Nov 5, 2024
1b57b94
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Lms24 Nov 5, 2024
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Lms24 Nov 5, 2024
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19 changes: 19 additions & 0 deletions ...ation-tests/suites/tracing/browserTracingIntegration/long-tasks-before-navigation/init.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
import * as Sentry from '@sentry/browser';

window.Sentry = Sentry;

Sentry.init({
dsn: 'https://[email protected]/1337',
integrations: [
Sentry.browserTracingIntegration({
idleTimeout: 9000,
enableLongAnimationFrame: false,
instrumentPageLoad: false,
instrumentNavigation: true,
enableInp: false,
enableLongTask: true,
}),
],
tracesSampleRate: 1,
debug: true,
});
17 changes: 17 additions & 0 deletions ...on-tests/suites/tracing/browserTracingIntegration/long-tasks-before-navigation/subject.js
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@@ -0,0 +1,17 @@
const longTaskButton = document.getElementById('myButton');

longTaskButton?.addEventListener('click', () => {
const startTime = Date.now();

function getElapsed() {
const time = Date.now();
return time - startTime;
}

while (getElapsed() < 500) {
//
}

// trigger a navigation in the same event loop tick
window.history.pushState({}, '', '/#myHeading');
});
13 changes: 13 additions & 0 deletions ...tests/suites/tracing/browserTracingIntegration/long-tasks-before-navigation/template.html
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@@ -0,0 +1,13 @@
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
</head>
<body>
<div>Rendered Before Long Task</div>
<script src="https://example.com/path/to/script.js"></script>

<button id="myButton">Start long task</button>
<h1 id="myHeading">Heading</h1>
</body>
</html>
27 changes: 27 additions & 0 deletions ...ation-tests/suites/tracing/browserTracingIntegration/long-tasks-before-navigation/test.ts
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@@ -0,0 +1,27 @@
import type { Event } from '@sentry/types';
import { expect } from '@playwright/test';

import { sentryTest } from '../../../../utils/fixtures';
import { getFirstSentryEnvelopeRequest, shouldSkipTracingTest } from '../../../../utils/helpers';

sentryTest(
"doesn't capture long task spans starting before a navigation in the navigation transaction",
async ({ browserName, getLocalTestPath, page }) => {
// Long tasks only work on chrome
if (shouldSkipTracingTest() || browserName !== 'chromium') {
sentryTest.skip();
}
const url = await getLocalTestPath({ testDir: __dirname });

await page.goto(url);

await page.locator('#myButton').click();

const navigationTransactionEvent = await getFirstSentryEnvelopeRequest<Event>(page, url);

expect(navigationTransactionEvent.contexts?.trace?.op).toBe('navigation');

const longTaskSpans = navigationTransactionEvent?.spans?.filter(span => span.op === 'ui.long-task');
expect(longTaskSpans).toHaveLength(0);
},
);
20 changes: 14 additions & 6 deletions packages/browser-utils/src/metrics/browserMetrics.ts
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Expand Up @@ -105,24 +105,32 @@ export function startTrackingWebVitals({ recordClsStandaloneSpans }: StartTracki
*/
export function startTrackingLongTasks(): void {
addPerformanceInstrumentationHandler('longtask', ({ entries }) => {
if (!getActiveSpan()) {
const parent = getActiveSpan();
if (!parent) {
return;
}

const { op: parentOp, start_timestamp: parentStartTimestamp } = spanToJSON(parent);

for (const entry of entries) {
const startTime = msToSec((browserPerformanceTimeOrigin as number) + entry.startTime);
const duration = msToSec(entry.duration);

const span = startInactiveSpan({
if (parentOp === 'navigation' && parentStartTimestamp && startTime < parentStartTimestamp) {
// Skip adding a span if the long task started before the navigation started.
// `startAndEndSpan` will otherwise adjust the parent's start time to the span's start
// time, potentially skewing the duration of the actual navigation as reported via our
// routing instrumentations
continue;
}

startAndEndSpan(parent, startTime, startTime + duration, {
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@Lms24 Lms24 Nov 5, 2024 •
edited
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small refactor: I switched from manually starting and ending the span to using the startAndEndSpan helper which does just that. However, the helper would also adjust the navigation span start time stamp if the stamp was started beforehand.
I medium-strongly feel we should not adjust this start time stamp b/c the long task might have nothing to do with the navigation but it would look like it otherwise.
If reviewers prefer the other way around (i.e. actually record the span and adjust the transaction start time), I'm also fine with that.

name: 'Main UI thread blocked',
op: 'ui.long-task',
startTime,
attributes: {
[SEMANTIC_ATTRIBUTE_SENTRY_ORIGIN]: 'auto.ui.browser.metrics',
},
});
if (span) {
span.end(startTime + duration);
}
}
});
}
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10 changes: 3 additions & 7 deletions packages/browser/package.json
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Expand Up @@ -9,9 +9,7 @@
"engines": {
"node": ">=14.18"
},
"files": [
"/build/npm"
],
"files": ["/build/npm"],
"main": "build/npm/cjs/index.js",
"module": "build/npm/esm/index.js",
"types": "build/npm/types/index.d.ts",
Expand All @@ -30,9 +28,7 @@
},
"typesVersions": {
"<4.9": {
"build/npm/types/index.d.ts": [
"build/npm/types-ts3.8/index.d.ts"
]
"build/npm/types/index.d.ts": ["build/npm/types-ts3.8/index.d.ts"]
}
},
"publishConfig": {
Expand All @@ -53,7 +49,7 @@
},
"scripts": {
"build": "run-p build:transpile build:bundle build:types",
"build:dev": "yarn build",
"build:dev": "run-p build:transpile build:types",
"build:bundle": "rollup -c rollup.bundle.config.mjs",
"build:transpile": "rollup -c rollup.npm.config.mjs",
"build:types": "run-s build:types:core build:types:downlevel",
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