$ cat l4p_bench.pl
#!/usr/bin/perl

# Benchmark penalty of having disabled log4perl statements left in
# production code.

use strict;
use warnings;
use Log::Log4perl;
use Benchmark qw(cmpthese);

my $conf = q(
  log4perl.category.screen = WARN, Screen
  log4perl.appender.Screen = Log::Log4perl::Appender::Screen
  log4perl.appender.Screen.layout = PatternLayout
  log4perl.appender.Screen.layout.ConversionPattern=[%p] %d %F:%L - 
);
Log::Log4perl::init( \$conf );
my $log = Log::Log4perl::get_logger("screen");

my @fibonacci = (0, 1);
my $n         = 1;
my $sum       = 0;

# projecteuler.net - problem 2
#
# Find the sum of all the even-valued terms in the Fibonacci sequence
# which do not exceed four million.

sub fib_no_log {
  while ($n < 1_000_000) {
    $n = $fibonacci[$#fibonacci] + $fibonacci[ $#fibonacci - 1 ];
    push @fibonacci, $n;    # append n to fibonacci list
    if (($n % 2) == 0) {
      $sum += $n;           # add even number n to sum
    } 
  }
  return $sum;
}

sub fib_log_1 {
  while ($n < 1_000_000) {
    $log->debug(qq{n:$n}) if $log->is_debug();
    $n = $fibonacci[$#fibonacci] + $fibonacci[ $#fibonacci - 1 ];
    push @fibonacci, $n;    # append n to fibonacci list
    if (($n % 2) == 0) {
      $sum += $n;           # add even number n to sum
    } 
  }
  return $sum;
}

           
cmpthese(
  -5,
  {
    'fib_no_log' => sub { fib_no_log() },
    'fib_log_1' => sub { fib_log_1() }
  }
);

__END__
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