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.

Configure the Sample Rate

Sampling for transactions must also be configured before

tracingThe process of logging the events that took place during a request, often across multiple services.
is 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.

// Specify a fixed sample rate:
'traces_sample_rate' => 0.2,
// Or provide a custom sampler:
'traces_sampler' => function (\Sentry\Tracing\SamplingContext $context): float {
    // return a number between 0 and 1

Learn more about how the options work in Sampling Transactions.


While you're testing, set 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.

Improve Response Time

Using the performance capabilities of PHP has some impact on your response time (depending on the traces_sample_rate you configured). Because of the nature of PHP, in most cases, requests are sent in the same process as the one in which you serve your users' response. In short, this process affects the time it takes to send a request to Sentry, because it is added to your servers' response time.

To account for this and reduce this addition to close to zero, you can use Relay running locally on the same machine or local network that acts as a proxy/agent. As a result, instead of your PHP process sending things to Sentry, the PHP process sends it to your local Relay, which then forwards it to Sentry.

To begin using Relay, check out our docs for getting started. Currently, we recommend using Relay in managed mode (which is the default).

Follow the instructions in the Relay docs to send a test event through Relay to Sentry. Don't forget to update your DSN to point to your running Relay instance. After you set up Relay, you should see a dramatic improvement to the impact on your server.

Next Steps:

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