RecompositionTracing

Compose Recomposition Tracing

record_recomposition_trace.py records a Perfetto system trace together with Compose composition and recomposition tracing from your app, and merges everything into a single file that you can open in ui.perfetto.dev.

Recomposition tracing shows which state reads and writes caused a composable to recompose. Composition tracing adds a trace section for each composable function. Both have a higher overhead than regular tracing, so use them for debugging, not for measuring performance.

Setup

Add the runtime-tracing dependency to your app module:

dependencies {
    // runtime-tracing 1.13.0 or newer is required
    implementation("androidx.compose.runtime:runtime-tracing:1.13.0")
}

You also need:

• A device running Android 10 (API 29) or newer, connected over adb.
• Python 3.10 or newer.
• adb on your PATH.

Usage

Start the app, then run:

./record_recomposition_trace.py -p com.example.app

Interact with the app and press Ctrl+C to stop recording. To record for a fixed time instead, pass the duration in seconds:

./record_recomposition_trace.py -p com.example.app -t 10

The script writes <package>-recompose-<timestamp>.zip to the current directory. Open the file in ui.perfetto.dev or load it with trace_processor.

Note

If the trace has no Compose events, check that animations are enabled on the device (Developer options > Animator duration scale) and that the app recomposes while the script is recording.

Options

Option	Default	Description
-p, --package	(required)	Application id of the app to trace.
-o, --out	current directory	Output .zip file or directory.
-t, --time	0	Trace duration in seconds. 0 records until Ctrl+C or SIGTERM.
-b, --buffer	64	Size of the system trace ring buffer in MB.
-c, --config	built-in config	Custom Perfetto text config. Overrides -t and -b.
-s, --serial	$ANDROID_SERIAL	Serial of the device to use.
--no-recompose	off	Skip recomposition tracing (state reads and writes). Only composition tracing and the system trace are captured.