I use PyCharm to work on a big Django project.
Lately, I noticed that my tests aren’t finishing, when running all of them at once. They quit at some point with the error:

Process finished with exit code 137 (interrupted by signal 9:SIGKILL)

First, I thought my MacBook Pro is out of memory. But after looking at the activity monitor and even quitting some other applications, it wasn’t resolved.
After some research, I realized it might still be connected to memory issues, but not on my Mac. Since, I use Docker on a Mac, I have to have a virtual machine running. And that was the cause of the problem. Not too long ago I switched from Docker Desktop to Colima, because of reasons. As I learned today, Colima uses 2 GB of memory for their VMs. So, the easy fix for the problem was increasing the memory of the VM:

colima start --vm-type=vz --memory 4