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:

• The SDK attaches the app start metrics to the first run transaction.
• It tracks the length of time from the earliest native process initialization until the very first PostFrameCallback is triggered.
• The SDK differentiates between a cold and a warm start, but doesn't track hot starts/resumes.

Prerequisites

Before starting, ensure:

1. The Sentry Flutter SDK is nitialized. Learn more here
2. Performance Monitoring is set up. Learn more here.

Configure

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

Verify

1. Execute the Transaction:

Initiate a transaction immediately after the app launches.

import 'package:sentry/sentry.dart';

final transaction = Sentry.startTransaction("test test", "my operation");
await Future.delayed(const Duration(milliseconds: 1000));
transaction.finish();

2. Locate Your Transaction:

Open the sentry.io performance dashboard, find, and select the transaction you executed.

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.

Additional Configuration

Change App Start Tracking End

1. Set autoAppStart to false in the Sentry options.
2. Call SentryFlutter.setAppStartEnd.

import 'package:sentry_flutter/sentry_flutter.dart';

// Run my App and do my things first

// Initialize the Flutter SDK
Future<void> main() async {
  await SentryFlutter.init(
    (options) => options.autoAppStart = false,
  );
}

// End the App Start metric
SentryFlutter.setAppStartEnd(DateTime.now().toUtc());