Set Up Tracing

With tracing, 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.

Configure

First, enable tracing and configure the sample rate for transactions (or service spans in stream mode). Set the sample rate by either:

• Setting a uniform sample rate for all transactions/service spans using the tracesSampleRate option in your SDK config to a number between 0 and 1. (For example, to send 20% of transactions/service spans, set tracesSampleRate to 0.2.)
• Controlling the sample rate based on the transaction/service span 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.

Sentry.init((options) {
+   // To set a uniform sample rate
+   options.tracesSampleRate = 1.0;

+   // OR if you prefer, determine traces sample rate
+   // based on the sampling context
+   options.tracesSampler = (samplingContext) {
+     // return a number between 0 and 1 or null (to fallback
+     // to configured value)
+   };
});

Sentry.init((options) {
+   // To set a uniform sample rate
+   options.tracesSampleRate = 1.0;

+   // OR if you prefer, determine traces sample rate
+   // based on the sampling context
+   options.tracesSampler = (samplingContext) {
+     // return a number between 0 and 1 or null (to fallback
+     // to configured value)
+   };
});

Learn more about tracing options, how to use the tracesSampler function, or how to sample transactions and service spans.

Verify

Verify that tracing is working correctly by using our automatic instrumentation or by starting and finishing a transaction/service span using custom instrumentation.

Test out tracing by starting and finishing a transaction/service span, which you must do so data can be sent to Sentry. Learn how in our Custom Instrumentation content.

While you're testing, set tracesSampleRate to 1.0, as that ensures that every transaction/service span 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/service spans, based on contextual data.

Next Steps