Debugging CRI-O

Below is a non-comprehensive document on some tips and tricks for troubleshooting/debugging/inspecting the behavior of CRI-O.

Printing go routines

Often with a long-running process, it can be useful to know what that process is up to. CRI-O has built-in functionality to print the go routine stacks to provide such information. All one has to do is send SIGUSR1 to CRI-O, either with kill or systemctl (if running CRI-O as a systemd unit):

kill -USR1 $crio-pid
systemctl kill -s USR1 crio.service

CRI-O will catch the signal, and write the routine stacks to /tmp/crio-goroutine-stacks-$timestamp.log

Forcing Go Garbage Collection

You may have a need to manually run Go garbage collection for CRI-O. To force garbage collection, send CRI-O SIGUSR2 using kill or systemctl (if running CRI-O as a systemd unit).

kill -s SIGUSR2 $crio-pid

systemctl kill -s USR2 crio.service