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How do I profile my Perl programs?

by faq_monk (Initiate)
on Oct 08, 1999 at 00:12 UTC ( #525=perlfaq nodetype: print w/ replies, xml ) Need Help??

Current Perl documentation can be found at perldoc.perl.org.

Here is our local, out-dated (pre-5.6) version:

You should get the Devel::DProf module from CPAN, and also use Benchmark.pm from the standard distribution. Benchmark lets you time specific portions of your code, while Devel::DProf gives detailed breakdowns of where your code spends its time.

Here's a sample use of Benchmark:

  use Benchmark;

  @junk = `cat /etc/motd`;
  $count = 10_000;

  timethese($count, {
            'map' => sub { my @a = @junk;
                           map { s/a/b/ } @a;
                           return @a
                         },
            'for' => sub { my @a = @junk;
                           local $_;
                           for (@a) { s/a/b/ };
                           return @a },
           });

This is what it prints (on one machine--your results will be dependent on your hardware, operating system, and the load on your machine):

  Benchmark: timing 10000 iterations of for, map...
         for:  4 secs ( 3.97 usr  0.01 sys =  3.98 cpu)
         map:  6 secs ( 4.97 usr  0.00 sys =  4.97 cpu)

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