Pros and cons using IDLED?

[Simon Matter]

Ken Murchison schrieb:
> 
> Simon Matter wrote:
> >
> > I have enabled compilation of idled in my newest RPM but am wondering
> > whether that was a good idea. I have two questions:
> >
> > 1) I was searching the archives and docs but still can't find a
> > description of the advantages and drawbacks when using idled instead of
> > poll. What are the drawback of possible problems I may face when using
> > idled?
> 
> Being the guy that wrote idled, I guess I have to answer  ;)
> 
> The main advantage of idled versus polling is that you get event-driven
> instant notification of message changes (new, delete, flag changes, etc)
> in your client when IDLEing (light load on the server, because it only
> checks the mailbox when told to).  With polling, you can can updates as
> fast as 1 sec, but you can beat the crap out of the server if you have a
> lot of users polling that much.
> 
> The downside of using idled is that it might not scale well.  I haven't
> received any input from a large site using idled.
> 
> Keep in mind that idled (or polling) is only used when the client issues
> the IDLE command.  The only mainstream client that I'm aware of that
> uses IDLE is Outlook.

Thanks. So it means it's only interesting in an Outlook environment for
now.

> 
> >
> > 2) I have read the man pages but still don't fully understand how things
> > work.
> > From the man page:
> > =====
> > imapidlepoll: 60
> >   The  interval  (in  seconds) for polling the mailbox for changes while
> > running the IDLE command.  This option is
> >   used when idled can not be contacted or when polling is used
> > exclusively.  The minimum value is 1.  A value of 0
> >   will disable polling (and disable IDLE if polling is the only method
> > available).
> > =====
> >
> > 60 is the default value for imapidlepoll. It means that unless specified
> > otherwise, IDLE is always enabled, using polling or idled. Only setting
> > it to 0 does in fact disable IDLE. The man pages also say that if idled
> > can not be contacted, poll is used instead.
> > My problem is now that I have compiled with idled but not enabled it in
> > cyrus.conf. I then get following messages:
> > /var/log/messages:Nov 22 22:26:56 xxl imapd[2594]: error sending to
> > idled: 2
> > Is this message only a warning message or does it mean I really have to
> > start idled if it's compiled in?
> 
> If you compile with idled enabled, it expects it to be running.  IIRC,
> it will try talking to idled a handful of times, and then give up (using
> polling exclusively).

Okay, that explains it. Thanks!

Simon

> 
> Ken
> --
> Kenneth Murchison     Oceana Matrix Ltd.
> Software Engineer     21 Princeton Place
> 716-662-8973 x26      Orchard Park, NY 14127
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