dovecot - May 2009 - Inotify instance limit for user exceeded, disabling?

I'm seeing this message in my /var/log/maillog:

May 26 12:35:00 agencymail dovecot: IMAP(info at example.com): Inotify 
instance limit for user exceeded, disabling. Increase 
/proc/sys/fs/inotify/max_user_instances

I rummaged through google, and found :
http://www.dovecot.org/list/dovecot-cvs/2008-May/011132.html

which says I need to increase /proc/sys/fs/inotify/max_user_instances 
(no surprise given the error message really).  I can fix that with 
echo 256 > /proc/sys/fs/inotify/max_user_instances , but  as /proc is 
temporary, so if I change it won't it break if/when the system reboots?

The error message also implies that something has been disabled. If I 
increase /proc/sys/fs/inotify/max_user_instances will it fix 
automatically, or do I need to do something else?  since it's a 
kernel message, I suspect just restarting dovecot won't do it.

And what exactly is breaking when I receive this notification?  The 
proc docs indicate:
/proc/sys/fs/inotify (since Linux 2.6.13)
This directory contains files max_queued_events, max_user_instances, 
and max_user_watches, that can be used to limit the amount of kernel 
memory consumed by the inotify interface. For further details, see 
<http://linux.die.net/man/7/inotify>inotify(7).

Is this dovecot monitoring for new mail?

thanks

Rick



[root at agencymail inotify]# dovecot -n
# 1.1.8: /etc/dovecot.conf
# OS: Linux 2.6.18-92.el5 i686 Red Hat Enterprise Linux Server 
release 5.2 (Tikanga) ext3
ssl_cert_file: /etc/httpd/certs/agencymail_example_com.crt
ssl_key_file: /etc/httpd/certs/agencymail.example.com.key.no.password
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
login_max_processes_count: 256
mail_uid: 1015
mail_gid: 105
mail_location: maildir:/var/spool/mail/%d/%n/Maildir
mail_executable(default): /usr/libexec/dovecot/imap
mail_executable(imap): /usr/libexec/dovecot/imap
mail_executable(pop3): /usr/libexec/dovecot/pop3
mail_plugins(default): acl quota imap_quota expire trash
mail_plugins(imap): acl quota imap_quota expire trash
mail_plugins(pop3): expire 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 outlook-idle
imap_client_workarounds(imap): delay-newmail outlook-idle
imap_client_workarounds(pop3):
pop3_client_workarounds(default):
pop3_client_workarounds(imap):
pop3_client_workarounds(pop3): outlook-no-nuls oe-ns-eoh
dict_db_config: /etc/dovecot-db.conf
auth default:
   mechanisms: plain login
   passdb:
     driver: sql
     args: /etc/dovecot-sql.conf
   userdb:
     driver: passwd
   userdb:
     driver: sql
     args: /etc/dovecot-sql.conf
   userdb:
     driver: static
   socket:
     type: listen
     client:
       path: /var/spool/postfix/private/auth
       mode: 432
       user: postfix
       group: postfix
     master:
       path: /var/run/dovecot/auth-master
       mode: 384
       user: vuser
       group: vuser
plugin:
   quota: maildir
   quota_rule: *:storage=102400000
   quota_rule2: Trash:storage=100M
   acl: vfile:/etc/dovecot/acls
   trash: /etc/dovecot-trash.conf
   expire: Trash 14 Trash/* 14 Spam 14
   expire_dict: proxy::expire
dict:
   expire: mysql:/etc/dovecot-dict-expire.conf




Rick Steeves
http://www.sinister.net

"The more I learn, it seems, the less I know." Frazz

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On Wed, 27 May 2009, dovecot at corwyn.net wrote:
> surprise given the error message really).  I can fix that with echo 256
>
> /proc/sys/fs/inotify/max_user_instances , but  as /proc is temporary, so if
I
> change it won't it break if/when the system reboots?
See man sysctl

Bye,

- -- 
Steffen Kaiser
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On Wed, 2009-05-27 at 09:21 -0400, dovecot at corwyn.net
wrote:
> The error message also implies that something has been disabled. If I 
> increase /proc/sys/fs/inotify/max_user_instances will it fix 
> automatically, or do I need to do something else?  since it's a 
> kernel message, I suspect just restarting dovecot won't do it.
Kernel increases the limit immediately, so you don't need to do anything
else. There's no need to even restart Dovecot (although existing IMAP
processes that failed to use inotify before won't be using it until the
client reconnects).
> And what exactly is breaking when I receive this notification? 
When IMAP client uses IDLE command, Dovecot can't use inotify to notify
the client immediately after new message has been received.
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