I just want to be able to set the program to run for a couple of hours (if need be) and then stop.

(additional emphasis by me)

I personally believe that for such prolonged times a solution along the lines of that suggested by L~R is best suited. Playing with alarm as duly suggested by ccn is more important in short lived situations in which finer control over time is needed and/or you need to timeout "no matter what" e.g. when running external processes:

#!/usr/bin/perl

use strict;
use warnings;
use 5.010;

use File::Basename;
my $pname; BEGIN { ($pname)=fileparse $0, qr/\.pl/i }

my $TIME = 10;

if (@ARGV) {  # Working as a generic external program
    sleep +(my $time=shift);
    say "Slept $time seconds";
} else {      # Example of timeout via alarm()
    my ($msg, $timeout) = ("died in SIG ALRM", int rand 2*$TIME);
    eval {
        local $SIG{ALRM} = sub {die $msg};
        warn "[$pname] Trying to collect output from external program.
+\n",
             "(Setting timeout to $timeout seconds.)\n";
        alarm($timeout);
        chomp(my $output = qx/perl $0 $TIME/);
        say "The output got from external program is: `$output'";
        alarm(0);
    };
    if ($@ and $@ ~~ /\Q$msg/) {
        warn "[$pname] Timed out!\n";
    }
}

__END__

[download]

Incidentally, it is worth reminding that for finer control over (not necessarily) short times a precious module would be Time::HiRes, which is in core.

--
If you can't understand the incipit, then please check the IPB Campaign.

In reply to Re: Running code a certain amount of time by blazar
in thread Running code a certain amount of time by Ninth Prince

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.