Re: sluggish IMAP updating?

[Simon Josefsson <simon@josefsson.org>]

Greg Troxel <gdt@work.lexort.com> writes:

> Simon Josefsson <simon@josefsson.org> writes:
>
>>> The word from dovecot is that STATUS on a selected mailbox is SHOULD NOT
>>> to start with, and MUST NOT to check for new mail.  See 6.3.10 of
>>> RFC3501.
>>>
>>> http://dovecot.org/pipermail/dovecot/2007-May/023045.html
>>>
>>> Plus, doing lots of STATUS commands seems to be disfavored but I don't
>>> understand IMAP well enough to understand.
>>
>> nnimap was written when RFC 2060 was current, and we haven't really
>> updated it for RFC 3501.  I suspect the notes in 6.3.10 was added as a
>> result of nnimap and other implementations behaviour, but the problem is
>> that I don't know of a good way to implement this in Gnus without using
>> STATUS (and, alas, I wouldn't have time to implement anything even if I
>> had some ideas).  Note that I cannot see that RFC 3501 allows servers to
>> respond with incorrect data in this situation, which dovecot appears to
>> be doing.
>
> The dovecot people talk about 'synchronizing the mailbox', and
> apparently they are in an implementation bind because they aren't
> allowed to clear recent flags.
>
> I see your point, but the RFC says "MUST NOT" use STATUS on a selected
> mailbox to check for new mail.

RFC 2060 didn't, and nnimap was written for that RFC.  Ideally, someone
could revise nnimap to make it more modern.

> I think one is supposed to use SEARCH RECENT, but I really  just barely
> understand imap.

Alternatively use something like the IDLE extension.  Or issue a NOOP.

>> I don't have a strong opinion on what the default should be.  If others
>> think it is safer to let it be t by default, by all means change it.
>
> Someone else was having trouble with courier imap, so this seems not to
> just be a dovecot issue.   I'd favor safety over efficiency.   for me
> 'g' takes a while and does 100 STATUS checks, so an unselect hardly
> seems like a big deal.

The unselect happens in a few other situations too, though, which could
trigger other kind of bugs.

Still, let's try it for a while.  I have installed it in CVS.

Heads up: if anyone notices that nnimap has become significantly slower
and/or some new IMAP is showing up that can be traced to this change,
let us know!

/Simon