[Dovecot] Stale imap processes

[Pete Slagle]

Brad wrote:

> On Tue, Aug 01, 2006 at 05:38:00PM -0700, Pete Slagle wrote:
>> Fran Fabrizio wrote:
>>
>>> Anyone have any theories or experiences as to why for a certain user, 
>>> some of his imap processes hang, and stay around for days and days?  He 
>>> just reported that his Thunderbird was timing out when trying to open 
>>> folders, I looked on the server, and he had 3 old imap processes from 1 
>>> week+ ago.  I killed those and his performance immediately improved.
>>>
>>> He checks mail with Thunderbird > 1.5 from both Win and Linux, 
>>> Squirrelmail webmail, and pine.  Of those, pine is the only one that is 
>>> somewhat rare around here - any specific problems with pine's imap 
>>> client code that anyone knows about?
>>>
>>> We have been using the dovecot-1.0-0.beta2.7 rpm for Fedora Core 5, I'm 
>>> updating to 1.0-0.beta8.2.fc5 to see if that helps, as well.  Just 
>>> curious if anyone else has seen this lately.
>>>
>>> Thanks,
>>> Fran
>> I have just seen this problem, big time. I was poking around on a
>> FreeBSD 6.1 server because of Thunderbird hangs (see thread
>> "dovecot-1.0rc2 problems with Thunderbird" if you are interested), and I
>> found over 900 (!) imap process. Only two users were using the dovecot
>> server at the time.
>>
>> I restarted dovecot, but this did NOT kill the multitudinous imap
>> processes. After another restart, with a 'killall imap' in the middle,
>> things were temporarily fine, but the number of imap processes
>> immediately started to grow again. Apparently they never exit. or use
>> any CPU, but just sit around in KQREAD state, eventually getting swapped
>> out. No error messages are generated.
> 
> Stop using the kqueue support! It is broken and has never fully worked
> properly. This is a known issue if you back in the list archives.

Thanks for the tip.  But, it's perplexing: kqueue support is built in by
default to the FreeBSD port of dovecot, which presumably means that
almost everyone running dovecot on FreeBSD is using it.

I had some trouble finding a good way to search the dovecot list
archives. Can you provide a pointer to the thread you mention? It might
be something I should send to the maintainer of the FreeBSD dovecot port.

Pete