Somewhat shorter than other suggestions (by using the Date::Time modules): 
use strict;
use DateTime::Format::Flexible;
use DateTime::Duration;

my $one_hour = DateTime::Duration->new(hours   => 1);

my %loglines;

while (<DATA>) {
    next unless /TWO/; # only handle log-items with for channel TWO
    my ($time, $ref)  = /(.*) UTC.*refs = (\d+)$/;
    my $dt = DateTime::Format::Flexible->build( $time );
    if (defined $loglines{$ref}) {
        my $difference = $dt->subtract_datetime( $loglines{$ref}->[0] 
+);
        if (DateTime::Duration->compare( $difference, $one_hour) == 1 
+) { # check if difference more than 1 hour
            print $loglines{$ref}->[1], $_, "-------------------------
+\n";
            delete $loglines{$ref}; # reset the item
        }
    } else {
        $loglines{$ref} = [$dt, $_]; # save the item
    }
}

__DATA__
2008-Jan-06 00:00:01 UTC (GMT +0000) - Poll: channel = ONE, refs = 595
+166299
2007-Jan-06 00:00:01 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+159906
2007-Jan-06 00:00:01 UTC (GMT +0000) - Poll: channel = THREE, refs = 6
+59975924
2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = ONE, refs = 595
+148941
2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+131400
2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = THREE, refs = 6
+59975924
2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = ONE, refs = 595
+159906
2007-Jan-06 01:00:05 UTC (GMT +0000) - Poll: channel = ONE, refs = 595
+166299
2007-Jan-06 01:00:06 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+131400
2007-Jan-06 01:00:06 UTC (GMT +0000) - Poll: channel = TWO, refs = 659
+975924
2007-Jan-06 01:00:07 UTC (GMT +0000) - Poll: channel = THREE, refs = 5
+95148941

[download]
And the result is: 
2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+131400
2007-Jan-06 01:00:06 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+131400
-------------------------

[download]
As the specification is a bit vague, I have chosen to reset the check once I have found two matching items more than 1 hour apart. You will then need again two new entries in the log more than one hour apart to trigger it.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

In reply to Re: comb a logfile for time diff and occourance by CountZero
in thread comb a logfile for time diff and occourance by tuakilan

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