dovecot - Aug 2009 - BUG: mbox_snarf causes message duplication when two IMAP connections are open

Hello,

I have used dovecot to replace an ageing wu-imap installation using
the mbox_snarf plugin however I have noticed that when we have more
than one client checking the INBOX we then have messages being
duplicated in the INBOX.

Below is the configuration used as requested in the bug report page.
I have confirmed that the duplicates are being caused by dovecot by
doing an strace of both processes that have both the INBOX
(/mail_home/$username/INBOX) and mail spool file
(/var/spool/dovecot/$username) open and delivering a new message
through exim to the mail spool file in /var/spool/dovecot/$username.
I then see in strace first one process check the spool and copy the
message over and then the other processes do the same.

If anyone requires any further information to confirm this bug please
let me know.

Kind regards.

Version: 1.2.1

[root at wine ~]# dovecot -n
# 1.2.1: /etc/dovecot.conf
# OS: Linux 2.6.18-128.el5 i686 CentOS release 5.3 (Final) ext3
protocols: imap
listen: *:10143 *:143
ssl: no
login_dir: /var/run/dovecot/login
login_executable: /usr/libexec/dovecot/imap-login
mail_access_groups: accounts agen directors extsw fax ftpguest imapshared operat
ions personnel sysadmin
mail_privileged_group: mail
mail_location: mbox:/mail_home/%u/:INBOX=/var/spool/dovecot/%u
mail_debug: yes
mbox_dirty_syncs: no
mbox_lazy_writes: no
mail_plugins: mbox_snarf
imap_client_workarounds: tb-extra-mailbox-sep
namespace:
  type: shared
  prefix: shared/
  location: mbox:/mail_home/imapshared/
  list: yes
namespace:
  type: private
  separator: /
  inbox: yes
  list: yes
  subscriptions: yes
namespace:
  type: private
  separator: /
  prefix: mail/
  hidden: yes
  list: no
  subscriptions: yes
namespace:
  type: private
  separator: /
  prefix: ~/mail/
  hidden: yes
  list: no
  subscriptions: yes
namespace:
  type: private
  separator: /
  prefix: ~%u/mail/
  hidden: yes
  list: no
  subscriptions: yes
auth default:
  passdb:
    driver: pam
  userdb:
    driver: passwd
plugin:
  mbox_snarf: /mail_home/%u/INBOX

On 8/3/2009, Robert Lazzurs (rob at lazzurs.net) wrote:
> If anyone requires any further information to confirm this bug please
> let me know.
What are the clients?

-- 

Best regards,

Charles

On Mon, Aug 3, 2009 at 11:39, Charles Marcus<CMarcus at media-brokers.com>
wrote:
> On 8/3/2009, Robert Lazzurs (rob at lazzurs.net) wrote:
>> If anyone requires any further information to confirm this bug please
>> let me know.
>
> What are the clients?
Hello,

The clients are thunderbird and GNOME mail-notification.

On Mon, Aug 3, 2009 at 11:48, Robert Lazzurs<rob at lazzurs.net>
wrote:
> On Mon, Aug 3, 2009 at 11:39, Charles Marcus<CMarcus at
media-brokers.com> wrote:
>> On 8/3/2009, Robert Lazzurs (rob at lazzurs.net) wrote:
>>> If anyone requires any further information to confirm this bug
please
>>> let me know.
>>
>> What are the clients?
>
> Hello,
>
> The clients are thunderbird and GNOME mail-notification.
Sorry for replying to my own message, however I was wondering if there
was any more help anyone needed or anything more I could do to fix
this bug.

The work around for us has been to stop using mail-notification but
that is not a solution we can continue with.

Thanks again for the fantastic IMAP server software :)

Take care.

Does the attached patch help? Although it makes performance slightly
worse.. Probably not noticeably. If it works, I'll just commit it to the
next release.

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