Exchange 2007 Issue Entering Large Groups

Exchange 2007 Issue Entering Large Groups

[Jake Colman]

This post is a follow-up to a series of posts regarding issues using
Gnus with Exchange 2007.  Most of the IMAP issues have been fixed with
the patches already included in the CVS version of Gnus.  The major
remaining issue is this: entering a group with a very large number of
read messages takes a very long time.

My imap-log shows the following:

1167 SELECT "INBOX/Principia"
* 15310 EXISTS
* 2 RECENT
* FLAGS (\Seen \Answered \Flagged \Deleted \Draft $MDNSent)
* OK [PERMANENTFLAGS (\Seen \Answered \Flagged \Deleted \Draft $MDNSent)]
  Permanent flags
* OK [UNSEEN 15309] Is the first unseen message
* OK [UIDVALIDITY 1296] UIDVALIDITY value
* OK [UIDNEXT 15320] The next unique identifier value
1167 OK [READ-WRITE] SELECT completed.
1168 UID SEARCH UNSEEN UNDELETED
* SEARCH 15318 15319
1168 OK SEARCH completed.
1169 UID SEARCH SEEN
* SEARCH 1 2 3 4..............

The result of the "SEARCH SEEN" is a huuuuuuuuuge amount of data.  It
totally floods my imap-log.  I am pretty sure that it is all this data
being returned by "SEARCH SEEN" that is taking up all this time.

For the record, following the out of "SEARCH SEEN" is the following:

1169 OK SEARCH completed.
1170 UID SEARCH FLAGGED
* SEARCH
1170 OK SEARCH completed.
1171 UID SEARCH ANSWERED
* SEARCH 15300
1171 OK SEARCH completed.
1172 UID SEARCH RECENT
* SEARCH 15318 15319
1172 OK SEARCH completed.
1173 EXAMINE "INBOX/Principia"

So I guess it all works at the end of it.

So what can we do to make this faster?

TIA!

...Jake


-- 
Jake Colman
Director of Software Development
Principia Partners LLC
101 West Elm Street
Suite 620
Conshohocken, PA  19428
+1 (610) 755-9786
www.principiapartners.com

Re: Exchange 2007 Issue Entering Large Groups

[Daniel Pittman]

Jake Colman <colman@ppllc.com> writes:

> This post is a follow-up to a series of posts regarding issues using
> Gnus with Exchange 2007.  Most of the IMAP issues have been fixed with
> the patches already included in the CVS version of Gnus.  The major
> remaining issue is this: entering a group with a very large number of
> read messages takes a very long time.

I recently upgraded my IMAP service from Cyrus to the Zimbra IMAP
server; it uses sparse UID allocation for messages which causes some
interesting behaviour in Gnus -- I trivially get groups that Gnus
believes have 65,000 new messages or more.

The biggest performance killer, since I don't use the agent, was the
setting of `nnimap-prune-cache', default `t', which causes an enormous
number of regexp searches in the cache.

I set that to `nil' and found my performance radically improved for
normal use, although there are still rare occasions that range
operations cause delays.

I intend working on the prune code at some point, and I am not sure it
will be what is slowing y'all down, but it may be worth a try.

Regards,
        Daniel