[Mailman-Users] Mailman causing strange slowdown in SMTP
brad at stop.mail-abuse.org
Sat Aug 12 02:33:26 CEST 2006
At 12:42 AM -0500 2006-08-11, Craig Pettersen wrote:
> Thanks for the response. The slow down has continued and nothing I've tried
> has helped. I answer the questions put to me in context below. Any further
> ideas would be greatly appreciated.
Just a guess, but have you stopped the MTA, moved the mail queue
directory structure aside, re-created the mail queue directory
structure with the same ownership and permissions, and then restarted
the MTA? You'll need to find a way to get all that old mail
processed, but that would at least get you accepting new mail again
faster -- until the next time when you have to do this kind of
process all over again.
The problem here is that mail queue directories get bigger and
bigger, and never shrink. So, even if you think you only have a
hundred files in the queue, if you look in the deep filesystem
structure there may be space for hundreds of thousands or millions of
files, dating back from a time when you had a serious backlog in the
past. Problem is, when the MTA is trying to create new files in the
queue directory to represent a given message, the code to create a
new file has to lock the entire directory structure from all changes
by any other process, search the entire directory structure to ensure
that there are no other files by that same name, and only then can it
actually create the file, unlock the directory, and return the file
handle to the calling program.
Mailman can suffer from this same problem, too. Same solution --
stop the program, move the queue directory structure aside, recreate
the queue directory structure with the same ownership and
permissions, then restart the program. And you also have to find a
way to deal with all those old messages sitting in the queue that has
now been set aside.
The only other thing I can think of is that your MTA is trying to do
an IDENT query (which usually time out at ten to fifteen seconds), or
some other sort of anti-spam/anti-virus processing on your outbound
mail. If the latter is the case, then you want to turn that off for
outbound mail from the mailing list, since that should have been
scanned on input.
Other than that, I'm out of ideas for the moment.
Brad Knowles, <brad at stop.mail-abuse.org>
"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."
-- Benjamin Franklin (1706-1790), reply of the Pennsylvania
Assembly to the Governor, November 11, 1755
Founding Individual Sponsor of LOPSA. See <http://www.lopsa.org/>.
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