mbexamine blocks mailbox

[Michael Menge]

Quoting David Carter <dpc22 at cam.ac.uk>:

> 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).

I know, but i don't understand why the mailbox was left in a locked state.
even if the mbexamine needs a to lock the mailbox it should release the lock
if it's not needed anymore.

>> 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.
>

Postfix reportet time outs, and attempted an other delivery. But i  
can't tell howmany lmtpd-processes waited for a lock on the mailbox  
and if any of them timed out, but the user reportet that he had some  
mails deliverd 70 times, so i thing none timed out all all got  
deliverd when the lock was released.

>> 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.

I know that these processed aren't supposed to be long running, but  
the lock should be hold as short as possible.

>
> --
> 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.
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>



--------------------------------------------------------------------------------
M.Menge                                 Tel.: (49) 7071/29-70316
Universitaet Tuebingen                  Fax.: (49) 7071/29-5912
Zentrum fuer Datenverarbeitung          mail:  
michael.menge at zdv.uni-tuebingen.de
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72074 Tuebingen
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