Set Up Performance

With performance monitoring, Sentry tracks your software performance, measuring metrics like throughput and latency, and displaying the impact of errors across multiple systems. Sentry captures distributed traces consisting of transactions and spans, which measure individual services and individual operations within those services. Learn more about our model in Distributed Tracing.

Enable Tracing

Tracing is available by default in the Sentry JavaScript npm packages.

If you are using the Loader Script, make sure to enable "Performance" under Settings > Projects > Client Keys (DSN).

If you are using the CDN, make sure you are using a CDN bundle that has performance monitoring enabled.

Configure

First, enable tracing and configure the sampling rate for transactions. Set the sample rate for your transactions by either:

• Setting a uniform sample rate for all transactions using the tracesSampleRate option in your SDK config to a number between 0 and 1. (For example, to send 20% of transactions, set tracesSampleRate to 0.2.)
• Controlling the sample rate based on the transaction itself and the context in which it's captured, by providing a function to the tracesSampler config option.

The two options are meant to be mutually exclusive. If you set both, tracesSampler will take precedence.

// If you're using one of our framework SDK packages, like `@sentry/react`,
// substitute its name for `@sentry/browser` here
import * as Sentry from "@sentry/browser";

Sentry.init({
  dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",

  // This enables automatic instrumentation (highly recommended),
  // but is not necessary for purely manual usage
  // If you only want to use custom instrumentation:
  // * Remove the `BrowserTracing` integration
  // * add `Sentry.addTracingExtensions()` above your Sentry.init() call
  integrations: [Sentry.browserTracingIntegration()],

  // We recommend adjusting this value in production, or using tracesSampler
  // for finer control
  tracesSampleRate: 1.0,

  // Set `tracePropagationTargets` to control for which URLs distributed tracing should be enabled
  tracePropagationTargets: ["localhost", /^https:\/\/yourserver\.io\/api/],
});

Learn more about performance monitoring options, how to use the tracesSampler function, or how to sample transactions.

Verify

Verify that performance monitoring is working correctly by using our automatic instrumentation or by starting and finishing a transaction using custom instrumentation.

While you're testing, set tracesSampleRate to 1.0, as that ensures that every transaction will be sent to Sentry.

Once testing is complete, you may want to set a lower tracesSampleRate value, or switch to using tracesSampler to selectively sample and filter your transactions, based on contextual data.

If you leave your sample rate at 1.0, a transaction will be sent every time a user loads a page or navigates within your app. Depending on the amount of traffic your application gets, this may mean a lot of transactions. If you have a high-load, backend application, you may want to consider setting a lower tracesSampleRate value, or switching to using tracesSampler to selectively sample and filter your transactions, based on contextual data.

Next Steps