perlMunger has asked for the wisdom of the Perl Monks concerning the following question:

Here's my thought, I have a script that I want to monitor, if the script hangs for 20 minutes. The script will run from cron every 10 minutes. currently the script creates a lock file, so concurrent script (same script) can't run. Within this script, I would like to spawn a monitor (sub routine within script) that will kill the parent and itself, if the script hangs for 20 minutes and send a notification when it happens. Is this possible, with out having to write another monitor type script? TIA! PerlMunger
  • Comment on Monitor Perl script within the same script?

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Re: Monitor Perl script within the same script?
by Animator (Hermit) on Dec 14, 2004 at 18:33 UTC
    I think you can use the alarm-function. (perldoc -f alarm)
[reply]
      Animator, thanks for the help. After reading the docs (perldoc -f alarm), I still can't seem to figure out who to use it within a sub/function. Should I fork a process from the sub to monitor the parent? If so, do you have any suggestions that might help me with my quest. TIA! perlMunger
[reply]
        It's been quite some time since I've written anything dealing with alarm but something like this may do what you need 

        
$SIG{ALRM} = sub {
   #cleanup lockfile
   #cleanup anything else
   exit;
}

alarm(1200);
# do stuff
# If you have system calls here (i.e. sysread) you
# may need to do some wrapping with eval etc.  (as per
# the alarm perldoc
alarm(0);

        [download]
        This is untested. I think the approach will work, but as always, you mileage may vary. Update: time is in seconds not minutes.
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Re: Monitor Perl script within the same script?
by mifflin (Curate) on Dec 15, 2004 at 16:37 UTC

    The perl Cookbook has a recipe on using alarm to solve your problem. See 16.22 if you have the book.

    Here is the code it uses 
    $SIG{ALRM} = sub { die "timeout" };

eval {
   alarm(1200); # 20 minutes
   # long-time operations here
   alarm(0);
};
if ($@) {
   if ($@ =~ /timeout/) {
      #timed out, do what you will here
   }
   else {
      die; # propagate the unexpected exception
   }
}

    [download]
[reply]
[d/l]
Re: Monitor Perl script within the same script?
by perlMunger (Novice) on Dec 15, 2004 at 20:16 UTC
    I want to thank all that replied, the code (both) worked like a charm. Thanks again for the help. perlMunger
[reply]

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