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.

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.

Sentry.init do |config|
  # set a uniform sample rate between 0.0 and 1.0
  config.traces_sample_rate = 0.2

  # or control sampling dynamically
  config.traces_sampler = lambda do |sampling_context|
    # sampling_context[:transaction_context] contains the information about the transaction
    # sampling_context[:parent_sampled] contains the transaction's parent's sample decision
    true # return value can be a boolean or a float between 0.0 and 1.0
  end
end

Learn more about how the options work in Sampling Transactions.

Verify

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

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.

Connecting Services

If you are also using Performance Monitoring for JavaScript, depending on where your request originates, you can connect traces:

1. For requests that start in your backend, by adding a meta tag in your HTML template that contains tracing information.
2. For requests that start in JavaScript, by the SDK setting a header on requests to your backend.

Otherwise, backend services with Performance Monitoring connect automatically.

Next Steps: