[imp] IMP 5 polling

[Michael M Slusarz]

Quoting Joe Besko <jbesko at msu.edu>:

> I've installed Horde Webmail Edition 4.0.3 in a test environment.
>
> I've also noticed that it was taking about 18-20 seconds to go from  
> one message to the next (with an additional 15-20 seconds for the  
> sidebar to refresh.)
>
> I thought it was odd that it behaved that way, since my previous  
> version of Horde Webmail 1.2.5 did not behave this way.
>
> After some searching and some testing, I found that the "poll all  
> folders" option was the culprit to these long delays.  When I turn  
> off the "poll all folders", IMP and DIMP are very snappy and perform  
> as I would expect.
>
> Now I have a question, is IMP supposed to poll all folders after  
> deleting/moving to another message?  It seems in the prior version,  
> we just polled all the folders after we processed the current list  
> of messages we were viewing.

If you are using the traditional view, and you have the sidebar open,  
then yes - this is the intended behavior.  Horde 3 loaded the sidebar  
in an IFRAME so its refresh rate was independent of what was happening  
with the application.  Horde 4 now loads the sidebar in a DIV instead,  
so it is reloaded every time a page is changed (sidebar data is not  
loaded if the sidebar is collapsed).

The dynamic view does not have this problem.  It polls only at  
whatever interval you configure it to (and is independent from any  
message action).

> The problem I run into when I don't poll all folders is that I don't  
> know where the filter has moved new messages outside the inbox.

You should really be using dynamic view then.  Traditional  
view/sidebar was not designed for performance - dynamic view is.

Although some other issues are at play here also.  The base IMAP 4rev1  
spec was *NOT* designed with this sort of polling feature in mind and,  
in fact, the RFC explicitly discourages it  
(http://tools.ietf.org/html/rfc3501#section-6.3.10).

That being said, it is tremendously useful for practical purposes, so  
the LIST-STATUS IMAP extension was recently introduced (RFC 5819).   
15-20 seconds seems long to poll all mailboxes; my guess you are using  
an old IMAP server that doesn't support mailbox caching and/or  
LIST-STATUS and an upgrade to an IMAP server that does support this  
functionality (e.g. recent versions of Dovecot, Cyrus) will  
dramatically improve your performance.  We can only do so many tricks  
on the MUA side to increase performance.  If you truly need real-time  
updates of mailbox counts, we can't provide those updates any faster  
than the IMAP server gives them.

Also important - you should really rethink using poll ALL mailboxes.   
I use filtering, but I filter to a certain subset of mailboxes  
(10-12).  Unless you are truly using every mailbox in your mailstore  
to filter messages into - I highly doubt, for example, you are  
filtering incoming messages into things like your Drafts or Sent  
mailboxes - you should manually select the mailboxes to poll instead.

michael

___________________________________
Michael Slusarz [slusarz at horde.org]