[Dovecot] dovecot imap auth fails to reconnect pgsql backend

[Frank Wang]

Hi,
    We've observed frequent auth failure recently from the SquirrelMail
frontend. The imap server is the dovecot-1.0.7-2 from Centos 5.2. The
auth backend is a pgsql database on another server. The only way to make
it work is to restart the dovecot, though sometimes it'll recover
automatically, but you don't know when. At first we thought there might
be a network problem, but we can always run pgsql client from the
dovecot server to connect and query the backend database during the auth
failure. We then upgraded to dovecot-1.1.3 from atrpms.net yesterday,
and still the same. It looks like the dovecot fails to reconnect/retry
pgsql backend.
    The related maillog in 1.0.7 version:
Sep 16 02:31:22 mail dovecot: imap-login: Disconnected: Inactivity:
method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Sep 16 02:33:20 mail dovecot: imap-login: Disconnected: Inactivity:
method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Sep 16 02:38:40 mail dovecot: imap-login: Disconnected: Inactivity:
method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured

    The related maillog in 1.1.3:
Sep 21 14:11:24 mail dovecot: imap-login: Disconnected: Inactivity (auth
failed, 1 attempts): method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Sep 21 14:14:39 mail dovecot: imap-login: Disconnected: Inactivity (auth
failed, 1 attempts): method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Sep 21 14:15:15 mail dovecot: imap-login: Disconnected: Inactivity (no
auth attempts): rip=127.0.0.1, lip=127.0.0.1, secured
Sep 21 14:23:49 mail dovecot: auth(default):
sql(user at our.domain,127.0.0.1): Password query failed: 
Sep 21 14:23:49 mail dovecot: child 15241 (auth) killed with signal 11
Sep 21 14:23:50 mail dovecot: auth(default): pgsql: Connected to
internal	

# dovecot -n
# 1.1.3: /etc/dovecot.conf
protocols: imap pop3
listen(default): *:143
listen(imap): *:143
listen(pop3): *:110
login_dir: /var/run/dovecot/login
login_executable(default): /usr/libexec/dovecot/imap-login
login_executable(imap): /usr/libexec/dovecot/imap-login
login_executable(pop3): /usr/libexec/dovecot/pop3-login
mail_location: maildir:/var/vmail/%d/%n
mail_executable(default): /usr/libexec/dovecot/imap
mail_executable(imap): /usr/libexec/dovecot/imap
mail_executable(pop3): /usr/libexec/dovecot/pop3
mail_plugins(default): quota imap_quota
mail_plugins(imap): quota imap_quota
mail_plugins(pop3): quota
mail_plugin_dir(default): /usr/lib/dovecot/imap
mail_plugin_dir(imap): /usr/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/lib/dovecot/pop3
imap_client_workarounds(default): delay-newmail tb-extra-mailbox-sep
imap_client_workarounds(imap): delay-newmail tb-extra-mailbox-sep
imap_client_workarounds(pop3): 
pop3_client_workarounds(default): 
pop3_client_workarounds(imap): 
pop3_client_workarounds(pop3): outlook-no-nuls oe-ns-eoh
auth default:
  mechanisms: plain login
  realms: our.domain1 our.domain2
  default_realm: our.domain1
  user: mail
  passdb:
    driver: sql
    args: /etc/dovecot-sql.conf
  userdb:
    driver: static
    args: uid=508 gid=509 home=/var/vmail/%d/%n/
quota=maildir:storage=512000
  socket:
    type: listen
    client:
      path: /var/spool/postfix/private/auth
      mode: 432
      user: postfix
      group: postfix
plugin:
  quota: maildir

grep -v '^ *\(#.*\)\?$' /etc/dovecot-sql.conf
driver = pgsql
connect = host=<pg_server_ip> dbname=<pg_dbname> user=<pg_user>
password=<pg_password>
default_pass_scheme = PLAIN
password_query = SELECT jm || '@%d' as user, password FROM usera where
jm = '%n' and forbid = 'N' and ( '%d' = 'our.domain1' or '%d' =
'our.domain2' )

    Can someone shed a light on this?
    Thanks!

Regards,
Frank Wang