Re^9: "exists $hash{key}" is slower than "$hash{key}"

is it noise?

sub BenchIt {
    print "\n\n## $^O $]\n";
    use Benchmark qw {:all};
    our %hash;
    for (1001..2000) {
        $hash{$_}++;
    }
    our $key1 = 2000 - int rand 1001;
    our $key2 = 2000 - int rand 1001;
    $hash{$key1} = 1;
    $hash{$key2} = {1..10};
    our $xx_global;
    cmpthese (
        -2,
        {
            svExist   => 'for(1..10_000){$xx_global = exists $hash{$ke
+y1} ? 1 : 2}',
            svValue   => 'for(1..10_000){$xx_global = $hash{$key1} ? 1
+ : 2}',
            refExist  => 'for(1..10_000){$xx_global = exists $hash{$ke
+y2} ? 1 : 2}  ',
            refValue  => 'for(1..10_000){$xx_global = $hash{$key2} ? 1
+ : 2}',
        }
    );
    return;
}
[download]

a few old perls


## msys 5.008008
          Rate  svValue  svExist refValue refExist
svValue  212/s       --      -0%     -10%     -16%
svExist  212/s       0%       --     -10%     -16%
refValue 235/s      11%      11%       --      -6%
refExist 250/s      18%      18%       6%       --


## MSWin32 5.008009
          Rate  svValue refValue refExist  svExist
svValue  210/s       --     -10%     -15%     -16%
refValue 234/s      11%       --      -6%      -6%
refExist 249/s      18%       6%       --      -0%
svExist  250/s      19%       7%       1%       --


## MSWin32 5.012002
          Rate refValue  svValue refExist  svExist
refValue 232/s       --      -2%      -4%      -6%
svValue  237/s       2%       --      -2%      -4%
refExist 242/s       4%       2%       --      -2%
svExist  247/s       6%       4%       2%       --


## MSWin32 5.014001
          Rate refValue refExist  svExist  svValue
refValue 245/s       --      -4%      -5%      -5%
refExist 254/s       4%       --      -1%      -1%
svExist  258/s       5%       1%       --      -0%
svValue  258/s       5%       1%       0%       --


## MSWin32 5.016003
          Rate refValue  svValue  svExist refExist
refValue 237/s       --      -2%      -5%      -6%
svValue  242/s       2%       --      -3%      -4%
svExist  250/s       6%       4%       --      -1%
refExist 252/s       6%       4%       1%       --


## MSWin32 5.016003
          Rate refValue  svValue  svExist refExist
refValue 222/s       --      -2%     -16%     -16%
svValue  228/s       2%       --     -14%     -14%
svExist  264/s      19%      16%       --      -0%
refExist 265/s      19%      16%       0%       --


## MSWin32 5.018002
          Rate  svValue  svExist refValue refExist
svValue  234/s       --      -9%     -10%     -13%
svExist  258/s      10%       --      -0%      -4%
refValue 258/s      11%       0%       --      -4%
refExist 269/s      15%       4%       4%       --


## MSWin32 5.020003
          Rate refValue refExist  svValue  svExist
refValue 231/s       --      -1%      -5%      -7%
refExist 234/s       1%       --      -4%      -6%
svValue  243/s       5%       4%       --      -3%
svExist  249/s       8%       7%       3%       --
[download]

laptops fluctuate :)

## msys 5.008008
          Rate  svValue refValue refExist  svExist
svValue  223/s       --      -5%      -8%      -9%
refValue 235/s       5%       --      -4%      -4%
refExist 244/s       9%       4%       --      -0%
svExist  244/s       9%       4%       0%       --


## msys 5.008008
          Rate  svValue  svExist refValue refExist
svValue  212/s       --      -2%     -12%     -16%
svExist  216/s       2%       --     -10%     -14%
refValue 240/s      14%      11%       --      -5%
refExist 252/s      19%      17%       5%       --

## msys 5.008008
          Rate  svValue refValue  svExist refExist
svValue  221/s       --      -7%     -11%     -12%
refValue 238/s       8%       --      -4%      -5%
svExist  248/s      12%       4%       --      -1%
refExist 250/s      13%       5%       1%       --
[download]

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XP is just a number
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