Path: utzoo!mnetor!uunet!husc6!mailrus!nrl-cmf!ames!necntc!culdev1!boh
From: boh@culdev1.UUCP (Brian O'Halloran)
Newsgroups: comp.os.minix
Subject: cron
Message-ID: <2017@culdev1.UUCP>
Date: 24 Mar 88 18:33:46 GMT
References: <1053@suvax1.UUCP>
Organization: Cullinet Software, Westwood, MA, USA
Lines: 53
Keywords: cron, sleep()
Summary: problems with cron or sleep() or both



Could some one please give me a hand.  I'm trying to get the recently
posted version of cron up on MINIX 1.2, but I'm having some problems as
I have noted below.  Any help would be greatly appreciated and I will
post summary on comp.os.minix.
 
o	The line in rc "/etc/update &" does not work when "/etc/cron &"
	is anywhere in rc.
o	If I have "/etc/cron &" alone in rc by removing "/etc/update &"
	cron works fine.  Likewise if I have "/etc/update &" alone in rc update
	works fine.
o	After rc is executed the process counter (F1) for "/etc/cron &"
	increments at a rate consistent with what one would expect until
	the first process counter for "/etc/update &" increments.  At that
	point they both freeze forever.  It seems as if when update returns
	from sleep(30) that both tasks freeze.
o	If I "/etc/cron &" after I logon to /usr/ast from /bin/sh cron
	works fine.
o	I have changed sleep() in cron.c to pass various times from 1 to 60
	with the same results as above.

Here is my rc;

/bin/clr
/etc/mount /dev/hd1 /minix
/etc/mount /dev/hd2 /bin
/etc/clock > /tmp/temp.file
/bin/date -q < /tmp/temp.file > /dev/null
/bin/rm /tmp/temp.file
/etc/cron &
/etc/update &

I have a clock routine which reads the AT clock.  If I replace this with
the line /bin/date -q < /dev/tty I still get the same results as above.  If
I flip the two lines from
/etc/cron &
/etc/update &
to
/etc/update &
/etc/cron &
I get the same results as above.
It appears as if I am causing a deadlock for the clock resources which both
update and cron use.  Do you have any ideas?  Yesterday I installed ast's
fix for deadlock and I still have the problem.

I am using an IBM PC/AT (6MHz), 640K RAM, 1408K extended,
30MByte hard disk, EGA, MINIX 1.2 with fix for boot from hard disk and load
root into extended memory.

Thanks,
Brian P. O'Halloran
boh@culdev1.uucp