Set Up

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

To automatically send traces, you must configure SentryTracingFilter in web.xml for Servlet applications configured with XML, or WebApplicationInitializer for Servlet applications configured with Java code:

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import io.sentry.spring.tracing.SentryTracingFilter;
import javax.servlet.Filter;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class AppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
  // ...
  @Override
  protected Filter[] getServletFilters() {
    return new Filter[] {new SentryTracingFilter()};
  }
}

Configure the Sample Rate

Once you configure the sample rate, tracing will be enabled in your app. Set the sample rate for your transactions by either:

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

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

Or alternatively:

Configure sample rate in sentry.properties:

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traces-sample-rate=0.3

Or through providing a bean of type SentryOptions#TracesSamplerCallback:

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import io.sentry.SentryOptions.TracesSamplerCallback;
import io.sentry.SamplingContext;
import org.springframework.stereotype.Component;

@Component
class CustomTracesSamplerCallback implements TracesSamplerCallback {
  @Override
  public Double sample(SamplingContext samplingContext) {
    CustomSamplingContext customSamplingContext = context.getCustomSamplingContext();
    if (customSamplingContext != null) {
      HttpServletRequest request = (HttpServletRequest) customSamplingContext.get("request");
      // return a number between 0 and 1 or null (to fallback to configured value)
    } else {
      // return a number between 0 and 1 or null (to fallback to configured value)
    }
  }
}

Without sampling, automatically-captured transactions can add up quickly. The Spring integration, for example, will send a transaction for every request made to the server.

High-Throughput Transport

For high traffic applications, we recommend using high-throughput HTTP transport based on Apache HTTP Client 5. Add the following dependency sentry-apache-http-client-5:

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<dependency>
    <groupId>io.sentry</groupId>
    <artifactId>sentry-apache-http-client-5</artifactId>
    <version>4.3.0</version>
</dependency>

Define the bean, which will be automatically used by Sentry SDK:

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import org.springframework.context.annotation.Bean;
import io.sentry.transport.apache.ApacheHttpClientTransportFactory;

@Bean
public ApacheHttpClientTransportFactory apacheHttpClientTransportFactory() {
  return new ApacheHttpClientTransportFactory();
}

Learn more about how the options work in Sampling Transactions.

Verify

Test out tracing by adding our included instrumentation or by starting and finishing a transaction using custom instrumentation.

Verify that performance monitoring is working correctly by setting traces-sample-rate to 1.0 as that ensures that every transaction will be sent to Sentry.

Once testing is complete, we recommend lowering this value in production by either lowering your traces-sample-rate value, or switching to using traces-sampler to dynamically sample and filter your transactions.

Next Steps:

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