I believe the original benchamrk code as posted is broken.
Thanks to
Aighearach for questioning my earlier
results and leading me along this path.
Consider this code:
my $now = 8;
my %url = ( monday => { @{[map(($_,1), (1..1000))]} } );
timethese(0, {
Grep => 'Grep();',
Grep2 => q{(sort grep {$_ <= $now} keys %{$url{"monday"}})[-1];
+},
Grep3 => sub{(sort grep {$_ <= $now} keys %{$url{"monday"}})[-1
+];}
});
sub Grep{
$now = (sort grep {$_ <= $now} keys %{$url{'monday'}})[-1];
}
The output from that:
Benchmark: running Grep, Grep2, Grep3, each for at least 3 CPU seconds...
Grep: 4 wallclock secs ( 3.00 usr + 0.02 sys = 3.02 CPU) @ 219.21/s (n=662)
Grep2: 4 wallclock secs ( 3.14 usr + 0.01 sys = 3.15 CPU) @ 356475.56/s (n=1122898)
Grep3: 4 wallclock secs ( 3.30 usr + 0.04 sys = 3.34 CPU) @ 213.47/s (n=713)
shows that something is definitely up, the "inline sub"
and "called sub" take the same time, but the
"inline quoted" version is unbelievably faster. I think it has
something to do with the inline quoted version not
really working the way the original poster intended (I think
its some sort of quoting/scoping problem, but I'm not sure
exactly what).
I have rerun my benchmarks with all the routines as
"inline subs" and the results follow:
dataset size | Grep | Max | Ternary |
100 | 2440.20/s | 2511.96/s | 2495.22/s |
1000 | 207.32/s | 222.81/s | 216.31/s |
10000 | 15.31/s | 16.77/s | 16.61/s |
And here is the code I used to run the test:
my %url;
my $now = 8;
my @size=(100,1000,10000);
foreach(@size){
my $size=$_;
print "size=$size\n";
%url = ( monday => { @{[map(($_,1), (1..$size))]} } );
timethese(0, {
Grep => sub {(sort grep {$_ <= $now} keys %{$url{"mond
+ay"}})[-1];},
Ternary => sub {($now < $_ && $_ < 8 ? $_ : $now) for key
+s %{$url{"monday"}};},
Max => sub {foreach ( keys %{$url{"monday"}} ) { $now
+ = $_ if $_ > $now };}
});
undef %url;
}
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