Performance Hands-On 8 - Thread Pool

Web Workers Demo

Click the button below to start multiple web workers that perform CPU-intensive tasks in parallel.

Ready to start workers

How to Use the Performance Tool to Analyze Thread Pool Usage

Open Chrome DevTools (F12 or Ctrl+Shift+I)
Switch to the Performance tab
Click the ⚫ Record button
Click the "Start Worker Tasks" button above
Wait for all workers to complete
Click the ⏹ Stop button in DevTools

What to Look For

Main Thread: Should remain responsive during worker execution
Worker Threads: Multiple workers executing in parallel
Thread Pool: Browsers typically limit the number of concurrent workers (usually 4-6)
Timeline: Check how work is distributed across available threads

Tip: Try increasing the number of workers in the code to exceed your browser's thread pool size and observe what happens!

Browser Thread Pools

Modern browsers manage computational resources through a thread pool. When you create multiple web workers:

They run in parallel on separate threads from the main UI thread
The browser will typically limit concurrent workers to protect system resources
If you create more workers than the thread pool size, some will be queued
This demo helps visualize how the browser schedules and manages these worker threads