dovecot - Apr 2012 - POP3 Dovecot Auth CPU usage 75%+

Hello all,

I hope someone can help me, I have been testing out Dovecot to switch from
popa3d which I use at the moment.  When I get several users connecting and
disconnection multiple times, the Dovecot process with command Auth uses
50-90% of the CPU for the period which they are connecting.  I am wondering
if there is something that I may have misconfigured, or if there is
something that I can change so that this spike doesn't occur.

If anyone could shed some light on the issue, I would appreciate it,

Kevin

/var/mail# dovecot -n
# 2.1.4: /usr/local/etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-33-generic-pae i686 Ubuntu 10.04.4 LTS ext4
auth_cache_size = 10 M
auth_verbose = yes
disable_plaintext_auth = no
instance_name = Mail Popper 1
listen = 172.20.20.222
login_greeting = Mail Popper 1 Ready
mail_location = mbox:/var/empty:INBOX=/var/mail/%u:INDEX=MEMORY
mail_privileged_group = mail
namespace inbox {
  inbox = yes
  location   mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix }
passdb {
  driver = shadow
}
protocols = pop3
service pop3-login {
  service_count = 0
}
ssl = no
userdb {
  driver = passwd
}
protocol pop3 {
  pop3_uidl_format = %08Xu%08Xv
}

Hello all,


I hope someone can help me, I have been testing out Dovecot to switch from
popa3d which I use at the moment.  When I get several users connecting and
disconnection multiple times, the Dovecot process with command Auth uses
50-90% of the CPU for the period which they are connecting.  I am wondering
if there is something that I may have misconfigured, or if there is
something that I can change so that this spike doesn't occur.

 If anyone could shed some light on the issue, I would appreciate it,

 Kevin

 /var/mail# dovecot -n
 # 2.1.4: /usr/local/etc/dovecot/dovecot.conf
 # OS: Linux 2.6.32-33-generic-pae i686 Ubuntu 10.04.4 LTS ext4
 auth_cache_size = 10 M
 auth_verbose = yes
 disable_plaintext_auth = no
 instance_name = Mail Popper 1
 listen = 172.20.20.222
 login_greeting = Mail Popper 1 Ready
 mail_location = mbox:/var/empty:INBOX=/var/mail/%u:INDEX=MEMORY
 mail_privileged_group = mail
 namespace inbox {
   inbox = yes
   location    mailbox Drafts {
     special_use = \Drafts
   }
   mailbox Junk {
     special_use = \Junk
   }
   mailbox Sent {
     special_use = \Sent
   }
   mailbox "Sent Messages" {
     special_use = \Sent
   }
   mailbox Trash {
     special_use = \Trash
   }
   prefix  }
 passdb {
   driver = shadow
 }
 protocols = pop3
 service pop3-login {
   service_count = 0
 }
 ssl = no
 userdb {
   driver = passwd
 }
 protocol pop3 {
   pop3_uidl_format = %08Xu%08Xv
 }

On 12.4.2012, at 23.46, Root Kev wrote:
> I hope someone can help me, I have been testing out Dovecot to switch from
> popa3d which I use at the moment.  When I get several users connecting and
> disconnection multiple times, the Dovecot process with command Auth uses
> 50-90% of the CPU for the period which they are connecting.  I am wondering
> if there is something that I may have misconfigured, or if there is
> something that I can change so that this spike doesn't occur.
So is it the "auth" process or "auth worker" process? What
if you add:
> passdb {
>  driver = shadow
> }
> userdb {
>  driver = passwd
args = blocking=yes
> }
does that move the CPU usage from "auth" to "auth worker"
process? Is it using /etc/shadow and /etc/passwd files? Are they large? Do you
have enabled other weird stuff in /etc/nsswitch.conf (and were there some other
files related to them as well?)