Hello everybody!
We have a interesting issue about dovecot behavior here. First, the scenario: We have 2 server running with the same load, one with our old pop3 solution (out of date) and other with Dovecot. We realized that dovecot are comsuming more CPU, and this consumption is growing day by day. When we starts dovecot, it runs between 40%-45% of CPU consumption and our old solution runs on 30-35%. This is quite acceptable, so no problem here. The problem is one day after it jumps to 45%-55% of cpu comsunption while the old pop3 solution runs on the same CPU consumption of one day before (30%-35). I attached a graph with this information.
In this graph the green line is dovecot CPU consumption and the blue line is the old solution.
In this graph we restart dovecot at monday morning. This restart is noticed as a big fall of CPU consumption(green line) in the graph. After that, it stay between 40%-45%, one day after it runs on 45%-55% and next day, it reaches 50%-60%! You can notice that the blue line (old pop3 solution) runs with the same behavior, so we have the same load. We have other monitoring informations that confirm it.
I looked for some bugs about this, but I didn't find anything. The question is: Is there any dovecot problem or wrong configuration that could cause this degeneration of CPU performance? Any sugestion about what can be the cause of this?
I attached dovecot -n output. Two important information: we store the mailboxes in NFS and we are only using pop3 protocol.
Thanks in advance!
-- Thiago Monaco Papageorgiou <thiago.monaco@corp.terra.com.br>
Terra Networks Brasil S/A Tel: +55 (51) 3284-4274
# 1.1.6: /usr/local/dovecot/etc/dovecot.conf # OS: Linux 2.6.9-78.0.1.ELsmp i686 CentOS release 4.7 (Final) syslog_facility: local2 protocols: pop3 listen: *:1110 ssl_disable: yes disable_plaintext_auth: no login_dir: /usr/local/dovecot/var/run/dovecot/login login_executable: /usr/local/dovecot/libexec/dovecot/pop3-login login_user: nobody login_log_format_elements: user=<%u> idperm=<%i> command=%t method=%m rip=%r lip=%l %c login_process_per_connection: no login_process_size: 32 login_processes_count: 100 login_max_processes_count: 500 login_max_connections: 100 mail_uid: popmgr mail_gid: popmgr mail_cache_min_mail_count: 100 mmap_disable: yes mail_nfs_storage: yes mail_nfs_index: yes lock_method: dotlock maildir_copy_preserve_filename: yes mail_executable: /usr/local/dovecot/libexec/dovecot/pop3 mail_plugins: hashdir mail_plugin_dir: /usr/local/dovecot/lib/dovecot/pop3 mail_log_prefix: %Us: user %u (%e): pop3_uidl_format: %f pop3_client_workarounds: outlook-no-nuls oe-ns-eoh auth default: mechanisms: plain trrproxy_v1 worker_max_count: 64 passdb: driver: trrpam args: extra_fields=short_name,quota_caixa,mail_folders_limit,id_perm,mail_imap %s_dovecot userdb: driver: prefetch plugin: quota: trrquota uidlist_create_form: 1
