Event Loop Block
Monitor for blocked event loops in all threads of a Node.js application.
This integration only works in the Node.js runtime.
Import name: eventLoopBlockIntegration from @sentry/node-native
The eventLoopBlockIntegration can be used to monitor for blocked event loops in all threads of a Node.js application. This integration provides better performance and more comprehensive monitoring compared to the deprecated anrIntegration.
# Using yarn
yarn add @sentry/node @sentry/node-native
# Using npm
npm install --save @sentry/node @sentry/node-native
If you instrument your application via the Node.js --import flag, Sentry will be started and this instrumentation will be automatically applied to all worker threads.
instrument.mjs
import * as Sentry from "@sentry/node";
import { eventLoopBlockIntegration } from "@sentry/node-native";
Sentry.init({
dsn: "__YOUR_DSN__",
// Capture stack traces when the event loop is blocked for more than 500ms
integrations: [eventLoopBlockIntegration({ threshold: 500 })],
});
app.mjs
import { Worker } from "worker_threads";
const worker = new Worker(new URL("./worker.mjs", import.meta.url));
// This main thread will be monitored for blocked event loops
worker.mjs
// This worker thread will also be monitored for blocked event loops too
Start your application:
node --import instrument.mjs app.mjs
If a thread is blocked for more than the configured threshold, stack traces will be captured for all threads and sent to Sentry.
You can pass a configuration object to the eventLoopBlockIntegration to customize the behavior:
interface ThreadBlockedIntegrationOptions {
/**
* Threshold in milliseconds to trigger an event.
*
* Defaults to 1000ms.
*/
threshold: number;
/**
* Maximum number of blocked events to send per clock hour.
*
* Defaults to 1.
*/
maxEventsPerHour: number;
/**
* Tags to include with blocked events.
*/
staticTags: { [key: string]: Primitive };
}
import * as Sentry from "@sentry/node";
import { eventLoopBlockIntegration } from "@sentry/node-native";
Sentry.init({
dsn: "__YOUR_DSN__",
integrations: [
eventLoopBlockIntegration({
threshold: 500, // Trigger after 500ms of blocking
maxEventsPerHour: 5, // Maximum 5 events per hour
staticTags: {
component: "main-thread",
environment: "production",
},
}),
],
});
Our documentation is open source and available on GitHub. Your contributions are welcome, whether fixing a typo (drat!) or suggesting an update ("yeah, this would be better").