Since I can't really rely on a fix time run time basis, this doesn't
make too much sense either, Instead of that i thought i'd rather
execute a littler bash script from the crontab that's like:
#!/bin/bash
if [ -e /var/run/myPIDfile ]
then
echo "script still running";
else
execute my perl script
fi
exit 0
How would that be? But then again, i don't see the difference to the
snippet in my perl script... :o
One step further would be to check the process list with "ps ax | grep
'HOWEVER/THE/CALL/FROM/CRON/LOOKS'| wc -l" and verify that only one
line is being returned (from the actual call)... - any suggestions/
comments?
Thanks,
Ron
On Dec 10, 11:31 pm, jimsgib...@gmail.com (Jim Gibson) wrote:
> At 11:43 AM -0800 12/9/09, cerr wrote:
>
>
>
> >Hi There,
>
> >I use below code to make sure i have only one instance of my script
> >running at a time. But weirdly enough i sometimes seem to have running
> >two instances. This script is getting called on a regular basis by a
> >cron job and may take a long time (30+min)to complete but still...I
> >can't figure out what would be wrong with this code, anyone?
>
> >#[PID]
> > #Check ifPIDfilealready exists
> > if ( -s $PIDloc){
> > print "THERE IS ALREADY AN INSTANCE OF UPDATESERVER RUNNING\n
> >check \"".$PIDloc."\"\n";
> > syslog('info',"THERE IS ALREADY AN INSTANCE OF UPDATESERVER RUNNING
> >\n check \"".$PIDloc."\"");
> > exit(999);
> > }
> > #if it doesn't exist, create it (gets ereased atr the bottom of MAIN
> >on completion)
> > my $pid= $$;
> > open my $fd,'>', $PIDloc or die $!;
> > print $fd $pid;
> > close $fd or die $!;
> >#[/PID]
>
> >Thanks for any hints or suggestions!
>
> Are you deleting thefileor trying to delete its contents? If the
> latter, try just deleting (unlinking) thefile. Maybe you are not
> zeroing out thefilecorrectly. Presence or absence of afilemay be
> a more reliable test than the number of bytes of content.
>
> There is also the possibility that an instance of your program
> terminated prematurely without cleaning up thefile. When that
> happens, you can look at the modification time of thefileand its
> contents to see which execution did not terminate cleanly.
>
> There is, of course, the possibility that your program took an
> abnormally time to execute. How often is your program scheduled to
> run? Are you logging start and stop time for each execution?
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