2009-05-13 1 year ago
Issue at work today: our mailserver was a bit overloaded. We run spamassassin in daemon mode to filter incoming mail that made it past the simple smtp checks. I noticed that mail to all staff members caused lots of waiting spamc processes from time to time which made mail pile up. A lot of the spamc processes were killed after a while because maildrop limits the time mail delivery can take. The big fix will be to increase the memory on the mail server, it is now swapping a lot. But the small fix was to tune spamd to not try to kill all its child processes when idle. Starting and stopping spamd child processes is an 'expensive' operation and mails to all staff members trigger a lot of simultaneous spamc calls, so it works better if a mail to a lot of local users finds already running spamd servers. I changed the setting to --max-spare=5 which made the load problem go away. We will still get a memory upgrade, but this simple processing fix also helped.
