[imp] Re: IMP authentication and email access very slow

[Gavin Kelman]

Craig White wrote:
> On Fri, 2005-02-11 at 17:13 +0000, Gavin Kelman wrote:
>>I've started to do some tests against our IMAP server. Telnetting to it
>>on port 143 and doing '. login username password' is fine, but then
>>'. list "" *' takes anything upto 30 seconds. Thus, leading me to
>>believe it's our Cyrus IMAP server at fault. Squirrelmail somehow brings
>>up the folder list in no time at all.
>>
>>Getting a bit off topic now, but does anyone know why Cyrus would take
>>_SUCH_ a long to return a folder list with the '. list "" *' command?
> 
> ----
> It would seem to me - and I am not all knowledgable on these matters,
> that in a way, you have answered your own question. You can't expect IMP
> to return the folder list faster than a direct telnet to the imap server
> would unless it somehow kept a cache of the folder list and provided you
> the list of mailboxes before it received them from your imap server.

Absolutely. It seems (at a guess) that IMP (PHP/C-Client) is using the
list command rather than lsub, hence it takes a long time. If I telnet
to our Cyrus IMAP server and do '. lsub "" *', I get a list of
subscribed folders back straight away. I think I'll have to look into
how to make IMP and it's underlying tools use lsub instead of list...

> Cyrus comes with a number of utilities to 'reconstruct' your mailboxes
> and it would seem useful to try this function out and see if that helps.

Tried it. Made a little difference, but still takes about 15 seconds or
more.

Someone else mentioned monitoring the CPU usage and so on. I've got
graphing of CPU and Memory usage, and I'm running top while trying
to diagnose this problem. The CPU usage is almost zero, while I'm
waiting for the list command to return. It seems to me it's doing,
quite literally, nothing for 15 seconds and then returning the
folder list. I've mentioned this on the Cyrus mailing list.

Thanks for your help. It seems the underlying problem is Cyrus rather
than IMP.

Cheers,
Gavin.

-- 
Gavin Kelman
UNIX Administrator
LION Bioscience Ltd.