[Mimedefang] Mimedefang processes are blocking

[Dave Close]

I've been running Mimedefang with Sendmail 8.12 for several months. Most
of the time, it works great. Although I am running the multiplexor, I
rarely see more than two mimedefang.pl processes. However, about once per
week, I find several mimedefang processes in state D, blocking. When this
happens, the system stops processing mail. The load average climbs from
its normal 1 or 2 to as high as 27, most of which represents the blocked
mimedefang processes. However, while the CPU load is under 2%, console
response time is terrible. I can get a response, but it takes very long.

Thus far, I haven't found a solution to this short of rebooting. I've
stopped sendmail, mimedefang, and milter-sender, and killed -9 all the
hung mimedefang processes. When I do that, the load average drops and
console response time returns to normal. But when I restart the daemons,
the problem returns within a few minutes. Clearly, I haven't found the
cause of the blockage, and stopping the daemon is not sufficient to
clear it. Debugging is possible, but painful, while the system is hung,
so I don't do much of it; I want to restore service ASAP. But with some
clue as to where to look, I can certainly do so.

Details: Red Hat Linux 9.0, completely up-to-date with yum. Sendmail
8.12.11 built from source to include the milter interface. Mimedefang
2.43. Milter-sender 0.55.

Dave Close, Compata, Costa Mesa CA  "The cost of silicon chips has been
dave at compata.com, +1 714 434 7359    steady at about $1bn per acre for
dhclose at alumni.caltech.edu           40 years." --Gordon Moore