#!/usr/bin/perl
use warnings;
use strict;
use Time::HiRes;
my $hr_log;
BEGIN {
    open($hr_log, ">", "/tmp/hrlog")
        or die "can't open hi-res log";
    sub hr_logger {
        my ($secs, $msecs) = Time::HiRes::gettimeofday();
        print $hr_log "$secs.$msecs: ", join("|", @_), "\n";
    }
    hr_logger("BEGIN");
}
# Obviously, you'll have all your modules here
use CGI;

# Put this just before you actually do any work in your code
# i.e. after all your 'use' lines
hr_logger("Ready to run");

# This bit would be your app
print "Now get on with running the app\n";

# And put this before you exit, for completeness
hr_logger("finished");
exit 0;

##</code><code>##

1178122211.615440: BEGIN
1178122211.646999: Ready to run
1178122211.647111: finished