pm2 stop only seems to kill 2 processes at a time?

Using the latest pm2 on ubuntu 20.04.

I have a config.js file that starts 50 copies of my program. Starting it works fine, all start immediately.

However when using "pm2 stop my_config.js" I notice it takes a long time, because my program catches the signal and does some cleanup work before exiting, and pm2 only seems to be sending signals to groups of 2 out of my 50 processes at a time?

I see it stop 2 processes... then 2 more... etc. It takes a long time for all 50 to get stopped because it doesn't appear to send signals simultaneously to all 50 processes. Can I configure it somehow to kill all 50 at once?

Start at the PM2 stop command entry point and trace how it signals processes in a configured group. Reproduce the behavior with config.js starting 50 copies and cleanup handlers that delay exit. Done means the stop behavior or its configuration is documented and verified against all 50 processes.