Dovecot starts multiple php processes which results in OOM killer

[kidhab]

We run a low traffic mail server with around 100 mailboxes. We repeatedly (about once a week) experience the following situation: The IMAP login process/ checkpassword starts a lot of php processes (about 100) which results in a very high system load. After the kernel kills the php process due to an out of memory situation the Dovecot process isn't available any more.

According to the monitoring the overall memory use is never a problem. We tried to limit php's memory_limit to a very low value like 16 M but this didn't prevent the situation. As a workaround systemd is now restarting Dovecot in this situations (Restart=on-failure).

I don't expect our setup to be special in any way - so I'm curious if you encounter similiar behaviour.

[t2d]

Hey, thanks for creating this issue. What OS are you using? We've never experienced an issue like this on Debian stable.

[kidhab]

Same here: Userli is running on Debian Bullseye. Do you use any special PHP or Dovecot settings that may incluence behaviour like this?

[t2d]

Are you using https://github.com/systemli/ansible-role-userli/ ?

[kidhab]

We installed Userli without the role - just followed your well written documentation.

[t2d]

But you can find all the config there. No idea why this problem occurs for you. Sorry

[doobry-systemli]

@kidhab do you still experience this problem?

[kidhab]

Looking at our monitoring there were no anomalies for some weeks now and we didn't change anything.