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

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