[comp.unix.questions] Tandy XENIX 3.01.02 cron sudden death

jrb@petro.UUCP (02/10/87)

We have had problems with the cron daemon summarily taking unexplained
vacations.  Local authorities are stumped, the cunning crontab crook comes 
creeping under curious circumstances, usually when the machine has been up
and running for some period of time.  Although the existing cron daemon can
be killed and a new one restarted but I personally prefer to re-boot the
computer to solve the problem.  "Death of a cron run" occurs infrequently,
but it is terribly frustrating.  If anyone has solved this problem or at least
experienced it, please let me know.

lyndon@ncc.UUCP (02/14/87)

In article <124@petro.UUCP> jrb@petro.UUCP (Jon Boede) writes:
>We have had problems with the cron daemon summarily taking unexplained
>vacations.  Local authorities are stumped, the cunning crontab crook comes 
>creeping under curious circumstances, usually when the machine has been up
>and running for some period of time.
>  [...]
>"Death of a cron run" occurs infrequently,
>but it is terribly frustrating.

I have seen this happen under CTIX as well. It happened on a very
sporadic basis. No core dumps were found. The only evidence was a
error return in the accounting logs when cron tried to fork at startup.

We don't have source, however I grabbed a copy of the binaries on the
failing machine and brought them across to our (identical) system. A
byte for byte comparison showed the files to be identical. I then
shipped our /etc/cron to the other system and installed it. No problems
noted for over three weeks.

Hmmm... Installed suspect version on our system. This time it lasted
three days before failing... Again a byte comparison was done. Again
they matched.

We eventually reinstalled everything from the distribution tape, and
haven't run into the problem since. It's still one of the great
unsolved mysteries though...
-- 
Lyndon Nerenberg - Nexus Computing Corp. - lyndon@ncc.UUCP
UUCP: {ihnp4,ubc-vision,vax135,watmath}!alberta!ncc!lyndon

abe@j.cc.purdue.edu.UUCP (02/19/87)

In article <1337@ncc.UUCP> lyndon@ncc.UUCP (Lyndon Nerenberg) writes:
>I have seen this happen under CTIX as well. It happened on a very
>sporadic basis. No core dumps were found. The only evidence was a
>error return in the accounting logs when cron tried to fork at startup.

One thing to check here: some Bourne shells run out of table space
for &'d processes when executing /etc/rc and fail to start daemons
in an unpredictable fashion.  Inserting a few strategic "wait" calls
in rc can sometimes help.

vrs@omssw2.UUCP (03/02/87)

I've seen this caused by a marginally too small stack size.  Try upping the
stack size to something reasonable with fixhdr if your cron is built with
0x100 bytes of stack or so.  The default of 0x1000 should work much more
nicely.