mailboxes.db locking problem after updating from 2.4 to 2.5.9

Wolfgang Breyha wbreyha at
Thu Nov 17 18:51:46 EST 2016

On 17/11/16 14:00, Deniss via Info-cyrus wrote:
> Hello,
> I trying to migrate one big cyrus imap server from 2.4 to 2.5.9.
> I updated binaries, fix db backend in imapd.conf and converted
> mailboxes.db with ctl_mboxlist -d & -u to twoskip.
> cyrus ran fine until morning when a count of simultanious sessions
> started to rise.

Sounds familiar;-)

> I converted mailboxes.db back to skiplist and got a bunch (10-20 per
> sec) of following logs:

I did the same. twoskip was and is useless on my frontends. With skiplist my
loads dropped at least down to 2-5. After doubling our vCPUs it runs quite well.

Do you use roundcube by any chance? If yes update to 2.5.10 and do not use
$config['imap_disabled_caps'] = array('LIST-EXTENDED');

Otherwise roundcube sends two 'LIST "" "*"' on each login and triggers two
full table scans on your mailboxes.db

> 180M /var/imap/mailboxes.db.skiplist.24
> 215M /var/imap/mailboxes.db.skiplist.25
> 262M /var/imap/mailboxes.db.twoskip.25

Wow, larger then ours. We've ~140MB on skiplist.25.

> Any ideas or suggestion for investigation ?

I already filed a bug
but no response so far. I directly asked Bron, but no response as well.

Greetings, Wolfgang
Wolfgang Breyha <wbreyha at> |
Vienna University Computer Center | Austria

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