speedscope

Jun 01, 2023

https://www.speedscope.app

speeding up javascript one library at a time shows how you can use this tool to generate flamegraphs that represent total time instead of exactly when the calls occurred.

It works by dropping a .cpuprofile file on it. Then at the top, select "⬅️ Left Heavy" to switch to a profile-by-call view instead of a profile-by-time.

I generated a profile of my eslint run by calling it like so: node --cpu-prof node_modules/.bin/eslint --ext js,jsx,ts,tsx ., that generated a file CPU.20230601.151131.57473.0.001.cpuprofile which I dropped on the profiler. Impressive stuff.

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