about imap-login: Error and imap: Error after Version-UP

[Aki Tuomi]

> On 16/11/2020 13:44 森川　孝司 <morikawa-k6 at itec.hankyu-hanshin.co.jp> wrote:
> 
>  
> We have upgraded dovecot from 2.0.9 (centos6) to 2.2.36 (centos8).
> 
> If more than 1000 users log in, the following error will occur.
> -------------------------
> Nov 16 11:33:00 xxxxxxxx dovecot[1361]: imap-login: Error: master(imap):
> net_connect_unix(imap) failed: Resource temporarily unavailable -
> http://wiki2.dovecot.org/SocketUnavailable (client-pid=1362,
> client-id=129834, rip=10.10.10.10, created 551 msecs ago, received 0/4
> bytes)
> Nov 16 11:30:26 xxxxxxxx dovecot[1361]: imap: Error:
> net_connect_unix(/var/run/dovecot/stats-writer) failed: Resource temporarily
> unavailable
> -------------------------
> 
> I set the following because I thought it was a problem with the number of
> connections, but I get an error.
> 
> service imap-login {
>   service_count=0
>   client_limit = $default_client_limit
>   process_min_avail = 4
>   process_limit = $default_process_limit
>   vsz_limit = 1G
> }
> 
> limits.conf
> -------------------------
> * soft nofile 4096
> * hard nofile 4096
> -------------------------
> 
> cat /proc/sys/net/core/somaxconn
> -------------------------
> 4096
> -------------------------
> 
> Is there any other tuning point?
> Where should I look?

https://wiki.dovecot.org/SocketUnavailable

Aki