App Start Instrumentation

Sentry's app start instrumentation provides insight into how long your application takes to launch.

Instrumentation Behaviour

Before diving into the configuration, it's important to understand how app start instrumentation behaves:

App start instrumentation tracks the duration between the earliest native process initialization and the first frame rendered (as reported by addTimingsCallback). Once the app start is processed, we remove the callback to avoid additional overhead.

When the SDK receives the start and end times of the app launch, we:

• Create a transaction named ui.load
• Attach a span with either app.start.cold or app.start.warm operation
• Add app start metrics to the transaction

Prerequisites

Before starting, ensure:

1. The Sentry Flutter SDK is initialized. Learn more here
2. Tracing is set up. Learn more here.

Configure

This instrumentation is automatically enabled. There is no need for further configuration.

Verify

1. Launch Your App:

Launch your Sentry configured app.

2. Locate Your Transaction:

Open the sentry.io performance dashboard, find, and select the 'root /' transaction and navigate to the trace view of a sampled event.

3. View App Start Metrics:

Select the event within your transaction. Sentry.io displays the app start metrics on the right side of the screen in the Mobile Vitals section.