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Path: utzoo!watmath!clyde!bonnie!akgua!gatech!seismo!hao!noao!amd!pesnta!pyramid!decwrl!sun!calma!adams
From: adams@calma.UUCP (Robert Adams)
Newsgroups: net.news.sa
Subject: Re: Are there problems if expire runs while news is being received?
Message-ID: <65@calma.UUCP>
Date: Mon, 18-Nov-85 12:27:14 EST
Article-I.D.: calma.65
Posted: Mon Nov 18 12:27:14 1985
Date-Received: Thu, 21-Nov-85 07:05:31 EST
References: <186@pluto.UUCP>
Organization: GE/Calma Co., R&D Systems Engineering, Milpitas, CA
Lines: 46

> I saw this happening, just wondered if this is a thing to avoid.  Won't
> both programs be updating the active file at the same time?

Yes, there are problems if expire and the unbatcher run at the
same time.  Here I run a program called /usr/lib/new/newexpire
which looks like:
---------------
#! /bin/csh -f
# expire that waits for the mail sender to be finished
while ( -e /usr/spool/uucp/LCK..sun )
	sleep 60
end
sleep 10
# now wait for the unbatcher to finish
while ( -e /usr/spool/uucp/LCK..ACTIVE )
	sleep 60
end
echo "$$" > /usr/spool/uucp/LCK..ACTIVE
/usr/lib/news/expire -e 14 -a -A /user/adams/news/archive -n mod.ai net.ai
/usr/lib/news/expire -e 14 -a -A /nfs/news_archive -n net.sources mod.sources
/usr/lib/news/expire -e 14
rm -f /usr/spool/uucp/LCK..ACTIVE
-------------
and then the program that is run by the news feeder ('sun' in
this case) was replaced by the script:
-------------
#! /bin/csh -f
while ( -e /usr/spool/uucp/LCK..ACTIVE )
	sleep 60
end
echo "$$" > /usr/spool/uucp/LCK..ACTIVE
echo "$$" > /usr/spool/uucp/LCK..BATCHER
/usr/lib/news/unbatchnews $*
rm -f /usr/spool/uucp/LCK..BATCHER
rm -f /usr/spool/uucp/LCK..ACTIVE
-------------
There are other things in the system that look for LCK..BATCHER
(we feed other sites).  Yes, this has critical region problems
but, compared to what happens to /usr/lib/news/active when both
expire and the unbatcher run at the same time, it is a little price.

An aside, the advantage of using filenames as "LCK..*" is that
they are already cleaned up by /etc/rc when the system boots.

	adams@calma.UUCP		-- Robert Adams
	...!ucbvax!calma!adams