Why do lmtpd processes accumulate?
murch at andrew.cmu.edu
Fri Apr 3 09:09:52 EDT 2009
Have you done an strace on one of the lmtpd on the backend to see what
it is doing?
Gary Mills wrote:
> We have a fairly conventional Cyrus server with one front-end and one
> back-end. Recently, I've noticed that when the number of lmtpd
> processes on the back-end server increases to the 400 range,
> performance drops to a crawl, including local deliveries. When I put
> an upper limit of 128 or 64 to these processes on the front-end, which
> requires a Cyrus restart, all of the local deliveries succeed in a
> short time. Performance also comes back to normal.
> I can't tell if it's the restart that fixes the problem or if it's
> the limit on lmtpd children. I'm wondering, though, if the lmtpd
> processes are all waiting on some Cyrus database, so that more of
> them just makes it worse. These are the databases, from imapd.conf:
> annotation_db: skiplist
> duplicate_db: berkeley-nosync
> mboxkey_db: skiplist
> mboxlist_db: skiplist
> quota_db: quotalegacy
> seenstate_db: skiplist
> subscription_db: flat
> tlscache_db: berkeley-nosync
> I believe those are current recommendations. Which ones might be
> causing the problem? Is there tuning that can be done on them?
Carnegie Mellon University
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