mbexamine blocks mailbox

[David Carter]

On Mon, 21 Jan 2008, Michael Menge wrote:

> i used mbexamine user/testuser | less
> to check the check the mailbox of testuser. I forgot to quit less over
> the weekend and today i discoverd two problems.
>
> 1. The mailbox was blocked. No new mails were deliverd to this mailbox.

The mailbox was left in a locked state. (fcntl() or flock() locks on both 
cyrus.header and cyrus.index).

> 2. After quitting less, the new mails had been delivered multiple
> times depending on the retries of lmtpd.

I imagine that you had a whole stack of lmtp processes waiting to acquire 
the lock on the mailbox. I'm a little suprised that something didn't time 
out, but I guess that the entire message would be sitting in the staging 
directory before lmtpd attempts to lock the target mailbox.

> is this a (known) bug? Are there other cyrus tools which will have the
> same effect? unexpunge -l ?

Any command line tool which locks a mailbox and then generates output will 
have the same behaviour. unexpunge would be the obvious example.

Whether this is a bug is debatable.

Neither mbexamine or unexpunge actually needs to lock the mailbox when 
they are just dumping mailbox state, but locking is normally the safest 
course of action. They aren't supposed to be long running processes.

-- 
David Carter                             Email: David.Carter at ucs.cam.ac.uk
University Computing Service,            Phone: (01223) 334502
New Museums Site, Pembroke Street,       Fax:   (01223) 334679
Cambridge UK. CB2 3QH.