Use Flashlight to Monitor Activity

Flashlight is an open-source performance monitoring tool. For Vega apps, it monitors CPU and memory performance data. Frames per second (FPS) monitoring is for inclusion in future releases. Flashlight with Vega works only on macOS and Linux.

This page explains how to setup and use Flashlight with Fire TV Stick device and Vega Virtual Device simulator).

Prerequisites

Make sure you complete the following:

1. Install the Vega SDK
2. Install yarn

Install Flashlight

1. Download Flashlight:

   flashlight-kepler-becb05f.zip

2. Extract to flashlight directory:

   Copy code Copied to clipboard.

   unzip flashlight-kepler-e0ad4ee.zip -d ~/flashlight
   

3. Build using yarn:

   a. <div id="c21" markdown="block">

   Copy code Copied to clipboard.

      cd ~/flashlight/flashlight-private-kepler-secret
   

   </div>

   b. <div id="c22" markdown="block">

   Copy code Copied to clipboard.

      yarn
   

   </div>

   c. <div id="c3" markdown="block">

   Copy code Copied to clipboard.

      yarn build
   

   </div>

Run Flashlight

1. Launch your sideloaded app on Fire TV Stick or Vega Virtual Device.

2. Navigate to Flashlight directory:

   Copy code Copied to clipboard.

   cd ~/flashlight/flashlight-private-kepler-secret
   

3. Run measure command to start Flashlight web interface.

   • For Vega Virtual Device:

     Copy code Copied to clipboard.

     PLATFORM=keplersimulator node packages/commands/measure/dist/server/bin.js measure
     

   • For Fire TV Stick:

     Copy code Copied to clipboard.

     PLATFORM=keplerdevice node packages/commands/measure/dist/server/bin.js measure
     

4. In the Flashlight web interface, do the following:

   • Select the "Auto Detect" to find your app's package ID.
   • Select the "Start Measuring" to begin monitoring.
   Important: Flashlight works only with sideloaded apps, not system apps.

Watch how to use Flashlight

The following video shows how to use Flashlight with VegaVideoApp on a Fire TV device:

1. Build, sideload, and launch VegaVideoApp on Fire TV.
2. Use Flashlight to monitor VegaVideoApp's live performance.

Related topics

• Monitor and Record Memory
• Monitor CPU Usage

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Last updated: Oct 01, 2025