net_connect_unix(imap) failed

[Alessio Cecchi]

Hi Philips,

I have the same error after upgrade from dovecot 2.2 to dovecot 2.3, 
could be related to "service stats",

try to grep in the dovecot.log for "reached" and look for an error like:

dovecot: master: Warning: service(stats): client_limit (1000) reached, 
client connections are being dropped

If you find it add to 10-master.conf:

service stats {
   client_limit = 10240
   unix_listener stats-writer {
     mode = 0660
     #user = vmail
     #group = vmail
   }
}

then restart dovecot.

Let me know if you solve or find others limit reached in the log.

Ciao

Il 31/03/20 18:22, Philipp Ewald ha scritto:
> Hello everyone,
>
> we have a huge problem with dovecot and IMAP connections.
>
> we got the following errors: 39665 today
>
> dovecot: imap-login: Error: master(imap): net_connect_unix(imap) 
> failed: Resource temporarily unavailable - 
> http://wiki2.dovecot.org/SocketUnavailable (client-pid=29066, 
> client-id=1755, rip=IP, created 562 msecs ago, received 0/4 bytes)
>
> we thinks this may be a problem with authorization take too long? 
> Authorization is not local and with SQL.
>
> i found the following in source code of Dovecot:
> #define SOCKET_CONNECT_RETRY_MSECS 500
> #define SOCKET_CONNECT_RETRY_WARNING_INTERVAL_SECS 2
> [...]
> i_error("master(%s): %s (client-pid=%u, client-id=%u, rip=%s, created 
> %u msecs ago, received %u/%zu bytes)",
>
> This is no process limit problem:
>
> ps auxf | grep -c "[d]ovecot/imap$"
> 688
>
> ps auxf | grep -c "[d]ovecot/imap-login$"
> 100
>
>
> cat /proc/`pidof dovecot`/limits
> Limit                     Soft Limit           Hard Limit           Units
> Max cpu time              unlimited unlimited            seconds
> Max file size             unlimited unlimited            bytes
> Max data size             unlimited unlimited            bytes
> Max stack size            8388608 unlimited            bytes
> Max core file size        0 unlimited            bytes
> Max resident set          unlimited unlimited            bytes
> Max processes             64053 64053                processes
> Max open files            65535 65535                files
> Max locked memory         65536 65536                bytes
> Max address space         unlimited unlimited            bytes
> Max file locks            unlimited unlimited            locks
> Max pending signals       64053 64053                signals
> Max msgqueue size         819200 819200               bytes
> Max nice priority         0                    0
> Max realtime priority     0                    0
> Max realtime timeout      unlimited unlimited            us
>
> ulimit -n
> 1024
>
>
> dovecot --version
> 2.3.4.1 (f79e8e7e4)
>
>
> protocols = imap pop3
> service imap-login {
>   process_min_avail = 4
>   service_count = 0
> }
> service imap {
>   process_limit = 4096
> }
> service pop3-login {
>   process_min_avail = 4
>   service_count = 0
> }
> service pop3 {
>   process_limit = 4096
> }
>
>
>
> Can someone explain why we got this error and how to fix? If you need 
> another information please tell me.
>
>
-- 
Alessio Cecchi
Postmaster @ http://www.qboxmail.it
https://www.linkedin.com/in/alessice

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