spamd dies with

[A J Thew]

It appears that this (or similar) has been see by others but I'll give my 2p worth
http://bugzilla.spamassassin.org/show_bug.cgi?id=4594

Sep 28 20:16:53 mx1 spamd[25801]: prefork: syswrite(9) failed, retrying... at /usr/lib/perl5/site_perl/5.6.1/Mail/SpamAssassin/SpamdForkScaling.pm line 554.
Sep 28 20:16:58 mx1 spamd[25801]: prefork: syswrite(9) failed, retrying... at /usr/lib/perl5/site_perl/5.6.1/Mail/SpamAssassin/SpamdForkScaling.pm line 554.

and later

Sep 28 20:21:54 mx1 spamd[22685]: prefork: sysread(10) failed after 300 secs at /usr/lib/perl5/site_perl/5.6.1/Mail/SpamAssassin/SpamdForkScaling.pm line 501.
Sep 28 20:21:54 mx1 spamd[24252]: prefork: sysread(11) failed after 300 secs at /usr/lib/perl5/site_perl/5.6.1/Mail/SpamAssassin/SpamdForkScaling.pm line 501.
Sep 28 20:21:54 mx1 spamd[22395]: prefork: sysread(11) failed after 300 secs at /usr/lib/perl5/site_perl/5.6.1/Mail/SpamAssassin/SpamdForkScaling.pm line 501.

and then
Sep 28 20:22:00 mx1 spamd[25801]: spamd: handled cleanup of child pid 19646 due to SIGCHLD
Sep 28 20:22:00 mx1 spamd[25801]: prefork: syswrite(9) failed, retrying... at /usr/lib/perl5/site_perl/5.6.1/Mail/SpamAssassin/SpamdForkScaling.pm line 554.

at this point spamd stops responding complely until shutdiwn and re-started.

I've reverted to --round-robin

Alan Thew