Pyspy

Steps

1. Ask the user which script to profile (full or relative path).

2. Run py-spy to record the profile. The output is always written to profile.speedscope.json in the current directory.

   Linux (no sudo needed):

   pixi run -e profiling pyspy script.py
   

   macOS (sudo required — py-spy needs to attach to the process):

   sudo pixi run -e profiling pyspy script.py
   

   If sudo fails to find the pixi environment, use absolute paths:

   sudo /path/to/.pixi/envs/profiling/bin/py-spy record --gil \
     -o profile.speedscope.json --format speedscope \
     -- /path/to/.pixi/envs/profiling/bin/python script.py
   

3. Open the result in speedscope:

   pixi run -e profiling speedscope
   

   This opens profile.speedscope.json in the browser via the local speedscope CLI.

Notes

• If the speedscope view is blank, switch threads using the thread selector in the top-right corner.
• To save a profile before overwriting: cp profile.speedscope.json profile-before.speedscope.json
• --gil records only time when the GIL is held (Python-level CPU time). Drop it to include C extension time.
• speedscope must be installed globally: npm install -g speedscope