We had a messy problem with procmail today. Our server was down briefly due
to a lightning storm, and when I brought it back up (apparently with a
backlog of mail to deliver), it began to malfunction terribly. Each time it
booted, sendmail invoked procmail (the local delivery agent), which in turn
was using John Hardin's e-mail "sanitizing" recipes. I watched as procmail
consumed 5 MB of memory, then 10, then more.... I saw a procmail error
message in the logs saying that it had tried to grab a 10 MB chunk all at
once and failed. Programs began to fail for lack of memory -- including
login and inetd, which couldn't even get the buffer space to open the
password file. Even sendmail reported that it couldn't get memory it needed.
I disabled user logins and tried to solve the problem by replacing our
procmailrc with one that invoked no recipes. The system groaned, shuddered,
and BARELY got through the backlog. Even as it did, other programs were
failing.
How can we prevent this from happening?
--Brett Glass