Set Up Profiling

With profiling, Sentry tracks your software's performance by sampling your program's call stack in a variety of environments. This feature collects function-level information about your code and enables you to fine-tune your program's performance. Sentry's profiler captures function calls and their exact locations, aggregates them, and shows you the most common code paths of your program. This highlights areas you could optimize to help increase both the performance of your code and increase user satisfaction, as well as drive down costs.

Enable Tracing

Profiling depends on Sentry’s Tracing product being enabled beforehand. To enable tracing in the SDK:

import Sentry

SentrySDK.start { options in
    options.dsn = "https://examplePublicKey@o0.ingest.sentry.io/0"
    options.tracesSampleRate = 1.0
}

Check out the tracing setup documentation for more detailed information on how to configure sampling. Setting the sample rate to 1.0 means all transactions will be captured.

By default, some transactions will be created automatically for common operations like loading a view controller/activity and app startup.

Enable Profiling

import Sentry

SentrySDK.start { options in
    options.dsn = "https://examplePublicKey@o0.ingest.sentry.io/0"
    options.tracesSampleRate = 1.0 // tracing must be enabled for profiling
    options.profilesSampleRate = 1.0 // see also `profilesSampler` if you need custom sampling logic
    options.enableAppLaunchProfiling = true // experimental new feature to start profiling in the pre-main launch phase
}

Enable Launch Profiling

(New in version 8.21.0)

Normally, a profile can only be taken during a trace span after the SDK has been initialized. Now, you can configure the SDK to automatically profile certain app launches.

To set up launch profiling, use the enableAppLaunchProfiling option and configure the sample rates for traces and profiles with SentrySDK.startWithOptions to determine if the subsequent app launch should be automatically profiled. This allows you to gather information on what is going on in your app even before main is called, making it easier to diagnose issues with slow app launches.

If you use SentryOptions.tracesSampler or SentryOptions.profilesSampler, it will be invoked after you call SentrySDK.startWithOptions, with SentryTransactionContext.forNextAppLaunch set to true indicating that it's evaluating a launch profile sampling decision. If instead you simply set SentryOptions.tracesSampleRate and SentryOptions.profilesSampleRate, those numerical rates will be used directly.

Currently, launch profiles are attached to a special performance transaction operation called app.launch and displayed in the product simply as launch.

Continuous Profiling

(New in version 8.36.0)

The current profiling implementation stops the profiler automatically after 30 seconds (unless you manually stop it earlier). Naturally, this limitation makes it difficult to get full coverage of your app's execution. We now offer an experimental continuous mode, where profiling data is periodically uploaded while running, with no limit to how long the profiler may run.

Previously, profiles only ran in tandem with performance transactions that were started either automatically or manually with SentrySDK.startTransaction. Now, you can start and stop the profiler directly with SentrySDK.startProfiler and SentrySDK.stopProfiler. You can also start a profile at app launch by setting SentryOptions.enableAppLaunchProfiling = true in your call to SentrySDK.startWithOptions.

Continuous profiling mode is enabled by default, requiring no changes to SentryOptions when you start the SDK to opt in. If you had previously set SentryOptions.profilesSampleRate or SentryOptions.profilesSampler to use transaction-based profiling, then remove those lines of code from your configuration.

These new APIs do not offer any sampling functionality—every call to start the profiler will start it, and the same goes for launch profiles if you've configured that. If you are interested in reducing the amount of profiles that run, you must take care to do it at the call sites.

Continuous profiling has implications for your org's billing structure. This feature is only available for subscription plans that enrolled after June 5, 2024.