use strict;
use warnings;

my ($tot1, $tot2);
while (<DATA>) {
	chomp;
	s/\s+$//g;
	next unless /TP Service Request$/ or /P5 Move request$/;
	my ($datetime, $ms, $inid, $message) = split /,/, $_;
	my $date = substr $datetime,11;
	my ($hours, $min, $sec) = map { $_ * 1000} split /:/, $date;
	$hours *= 60 * 60;
	$min *= 60;
	my $total_time = $hours + $min + $sec + $ms;
	$tot1 = $total_time if $message eq "TP Service Request";
	$tot2 = $total_time if $message eq "P5 Move request";
	next unless defined $tot2;
	print "Duration is: ", $tot2 - $tot1, " ms.\n";
	last;
}
		

__DATA__
2014-05-29 10:22:21,880,165ab6a8-e736-11e3-8748-8d365226be24,TP Service Request 
2014-05-29 10:22:21,962,165ab6a8-e736-11e3-8748-8d365226be24,ProcessName: TC 
... (rest of data omitted from this post for brevity)

##</code><code>##

$ perl  log_files.pl
Duration is: 46426 ms.