High memory usage

[Hanna Ruotsalainen]

Hi

I recently (about 2 weeks ago) moved over my users over to a new version
of dovecot (2.0.9) and now the memory usage on the new server seems much
higher than it was before.
The new server is a CentOS 6 VM with 4 GB of RAM and 4 CPUs and
according to top, it's used up all of the RAM and all of the Swap.
Here's a sample of the output from top (sorted by allocated memory).

top - 10:42:36 up 22 days, 21:57, 1 user, load average: 1.04, 1.40, 1.52
Tasks: 1643 total, 1 running, 1642 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.7%us, 0.7%sy, 0.0%ni, 93.3%id, 5.1%wa, 0.0%hi, 0.1%si,
0.0%st
Mem: 3924432k total, 3779236k used, 145196k free, 23740k buffers
Swap: 4063228k total, 3181164k used, 882064k free, 156420k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
16738 root 20 0 399m 182m 436 S 0.0 4.8 5:50.58 config
18790 dovenull 20 0 54528 11m 2036 S 0.0 0.3 0:00.05 imap-login
22277 dovenull 20 0 54528 11m 2156 S 0.0 0.3 0:00.04 imap-login
22796 dovenull 20 0 54528 11m 2140 S 0.0 0.3 0:00.03 imap-login
22749 dovenull 20 0 54528 11m 2148 S 0.0 0.3 0:00.03 imap-login
22825 dovenull 20 0 54528 11m 2156 S 0.0 0.3 0:00.03 imap-login

This is with 1015 imap processes and 484 imap-login processes.
The old version was 1.0.rc15 and running on a CentOS 4 box with 2GB of
RAM. It was overloaded but the RAM usage wasn't maxed out like this one
is (not much swap usage and a large amount of cached memory).

Is this amount of memory usage normal? What could be causing it, if it
isn't?

Thanks for your help,

Hanna

Here is the output of dovecot -n:

# 2.0.9: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-431.29.2.el6.x86_64 x86_64 CentOS release 6.5 (Final) nfs
auth_verbose = yes
disable_plaintext_auth = no
listen = *
login_greeting = Ready.
mail_debug = yes
mail_location =
maildir:/mail/%1Lu/%u:INDEX=/var/cache/dovecot/indexes/%1Lu/%u
mail_plugins = " mail_log notify"
maildir_very_dirty_syncs = yes
mbox_lazy_writes = no
namespace {
inbox = yes
location =
prefix =
separator = /
type = private
}
passdb {
args = /etc/dovecot/dovecot-ldap-pass.conf
driver = ldap
}
plugin {
mail_log_events = delete undelete expunge copy mailbox_delete
mailbox_rename
mail_log_fields = uid box msgid size
}
protocols = imap pop3
service anvil {
client_limit = 1250
}
service auth {
client_limit = 4300
user = root
}
service imap-login {
process_limit = 600
service_count = 1
}
service imap {
process_limit = 1536
}
service pop3-login {
process_limit = 600
service_count = 1
}
service pop3 {
process_limit = 1536
}
ssl_ca = </etc/pki/tls/certs/ca-bundle.crt
ssl_cert = </etc/pki/dovecot/certs/dovecot.pem
ssl_key = </etc/pki/dovecot/private/dovecot.pem
userdb {
args = /etc/dovecot/dovecot-ldap-user.conf
driver = ldap
}
version_ignore = yes
protocol imap {
mail_max_userip_connections = 10
ssl_cert = </etc/pki/dovecot/certs/imap.ecuad.ca.pem
ssl_key = </etc/pki/dovecot/private/imap.ecuad.ca.pem
}
protocol pop3 {
pop3_uidl_format = %08Xv%08Xu
ssl_cert = </etc/pki/dovecot/certs/pop.ecuad.ca.pem
ssl_key = </etc/pki/dovecot/private/pop.ecuad.ca.pem
}
protocol lda {
postmaster_address = _postmaster at example.com_
}