rbspy is a ruby profiler that lets you profile Ruby processes that are already running.

rbspy has an explicit output format for speedscope (See rbspy/rbspy#161).

To record a profile on an already-running process with rbspy, run:

sudo rbspy record --pid $PID --format speedscope --file profile.speedscope.json

Then drop the resulting profile.speedscope.json into https://www.speedscope.app/

To view it offline, you'll need to install speedscope via npm:

npm install -g speedscope

Then you should be able to open it like so:

speedscope /path/to/profile.speedscope.json