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Re: perl alarms not working as expected

by betterworld (Deacon)
on Oct 15, 2012 at 21:23 UTC ( #999186=note: print w/ replies, xml ) Need Help??


in reply to perl alarms not working as expected

Well, it works for me when I run it in the shell. However I see that you seem to be running it as a CGI script. The web server is probably waiting for that shell script to finish, because the shell script still has an open file handle to your standard output.

You should try killing the other script from your signal handler.


Comment on Re: perl alarms not working as expected
Re^2: perl alarms not working as expected
by kavkazi (Initiate) on Oct 16, 2012 at 13:18 UTC
    That's exactly what's happening. Can you please tell me how do I kill the other script from the signal handler. What is a signal handler? Please provide the code as I am a newbie :)

      The signal handler is that sub{} that you stored in $SIG{ALRM}.

      To kill the other script, you'd have to get its pid. Unfortunately I don't know any way to this without any ugly hacks. Maybe someone else does.

      So for instance, you can use this temporary file handle hack:

      #!/usr/bin/perl use strict; use warnings; use CGI; use File::Temp; my $q = new CGI; print $q->header; my $tmp = File::Temp->new(UNLINK => 0); my $tmpnam = $tmp->filename; eval { local %SIG; $SIG{ALRM}= sub{ $tmp->close; system("fuser", "-sk", "-TERM", $tmpnam); unlink $tmpnam; die "timeout reached, after 20 seconds!\n"; }; alarm 3; #sleep (60); system("sleep 10 3>$tmpnam"); alarm 0; }; alarm 0; if($@) { print "Error: $@\n"; } exit(0);

      This requires the "fuser" command, which is shipped with most Linux distros.

      If this does not make the other script die, then leave out the "-TERM".

      I replaced the name of your shell script with "sleep 10", otherwise I can't test it. I also replaced 20 with 3 because I did not want to wait 20 seconds.

        Thank You @betterworld for the line: system("sleep 10 3>$tmpnam"); what does 3>$tmpnam do? If I need to replace the sleep 10 with a call to script that needs arguments, how would I do that? i.e: system("/opt/bea/domains/fsa/scripts/start.sh fsaAs02 -q 3>$tmpnam");

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