Debian 10 LXC containers become unresponsive

Hi everyone,

On Debian 10, almost all LXCs was reachable but their services(like nginx) were not responding. I have restarted the lxc.service on the host while all containers are running, they back to normal state and become responding.

I’ve checked syslog file and see entries like:
-Memory cgroup out of memory: Kill process 22355 (apache2) score 9 or sacrifice child
-memory+swap: usage 0kB, limit 9007199254740988kB, failcnt 0

there were about 30GB of free memory on the host itself. btw after restarting the lxc.service, the log entries I mentioned above disappeared. What would be the root cause.

Thank you