[Mailman-Users] Problem with qrunner and too much incoming mail

J C Lawrence claw at kanga.nu
Fri Nov 3 21:53:35 CET 2000

On Fri, 3 Nov 2000 11:35:39 -0800 
Marc MERLIN <marc_news at valinux.com> wrote:

> The problem is due to qrunner being single threaded by default and
> having a global lock. Because some mailing lists have subscribers
> in domains where DNS is slow and unreliable, the MTA will hang on
> those rcpt to until DNS resolves or timeouts, and qrunner won't be
> done in time.  After that, it's all downhill from there, more mail
> queues up, qrunner falls even further behind, etc, etc...

Running a cacheing nameserver (I've recommended DJB's dnscache
before) would help significantly here.  This doesn't of course
remove the problem, just partially alleviates it.  

Further, in the case of Exim IIRC, it can be configured to not do
DNS lookups on RCPT addresses messages at the time of receipt by the
MTA based on the IP address/net of the source.  Thus you could
configure Exim to not do DNS lookups on everything received from
localhost.  Nigel -- can you confirm this?  I didn't see this on a
quick skim on the Exim docs but I seem to recall discussion of how
to do this previously.

Neither of these are real fixes of course.

J C Lawrence                                 Home: claw at kanga.nu
---------(*)                               Other: coder at kanga.nu
http://www.kanga.nu/~claw/        Keys etc: finger claw at kanga.nu
--=| A man is as sane as he is dangerous to his environment |=--

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