v147 · developer trial · workers · perf

Profiler API Explorer

Interactively start, stop, and inspect Profiler instances on the main thread and inside a Dedicated Worker. Overlay both traces side-by-side to see where CPU time lands.

Profile CPU-intensive work on the main thread. Adjust the sample interval and buffer size, run a workload, then inspect the trace as a flame-graph bar chart.

10 ms
300 samples
Ready
main thread trace — hot functions (by sample count)

Run a workload to see the trace…

Same profiling API, now running inside a Dedicated Worker — the capability added in Chrome 147. The worker profiles its own execution and sends the trace back to the main thread.

Checking if Profiler is available inside Workers in this browser…
10 ms
300 samples
Ready
worker thread trace — hot functions (by sample count)

Start the worker to see its trace…

Run both the main thread and worker profilers to compare where CPU time lands. The overlay chart shows sample counts for each function on both threads side-by-side.

Main thread
Worker thread
Run both threads to compare traces.
main vs worker — overlaid by function name

No traces yet — click ▶ Profile both threads.

references

implementation reference

Need the exact API surface, compatibility boundaries, errors, lifecycle, and source links? Read the matching gendn reference ↗