Programming Perl, 3rd Edition

Benchmark

use Benchmark qw(timethese cmpthese timeit countit timestr);

# You can always pass in code as strings:
timethese $count, {
    'Name1' => '…code1…',
    'Name2' => '…code2…',
};

# Or as subroutines references:
timethese $count, {
    'Name1' => sub { …code1… },
    'Name2' => sub { …code2… },
};

cmpthese $count, {
    'Name1' => '…code1…',
    'Name2' => '…code2…',
};

$t = timeit $count, '…code…';
print "$count loops of code took:", timestr($t), "\n";

$t = countit $time, '…code…';
$count = $t->iters;
print "$count loops of code took:", timestr($t), "\n";

The Benchmark module can help you determine which of several possible choices executes the fastest. The timethese function runs the specified code segments the number of times requested and reports back how long each segment took. You can get a nicely sorted comparison chart if you call cmpthese the same way.

Code segments may be given as function references instead of strings (in fact, they must be if you use lexical variables from the calling scope), but call overhead can influence the timings. If you don't ask for enough iterations to get a good timing, the function emits a warning.

Lower-level interfaces are available that run just one piece of code either for some number of iterations (timeit) or for some number of seconds (countit). These functions return Benchmark objects (see the online documentation for a description). With countit, you know it will run in enough time to avoid warnings, because you specified a minimum run time.

To get the ...