<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">NAME
    Benchmark::Forking - About the forking benchmarks distribution

MOTIVATION
    The standard Benchmark module can sometimes report inaccurate or
    misleading results, in part because it doesn't isolate its test cases
    from one another. This means that the order that cases are run in can
    influence the results, because side effects, either obvious or obscure,
    can accumulate and affect later tests.

    Data in global variables is an obvious source of side effects; in the
    below example, the grep takes longer as more items are pushed onto the
    array, so the test functions that run later will be reported by
    Benchmark as being slower, despite their code being identical:

      cmpthese( 1000, {
        "test_1" =&gt; sub { push @global, scalar grep 1, @global },
        "test_2" =&gt; sub { push @global, scalar grep 1, @global },
        "test_3" =&gt; sub { push @global, scalar grep 1, @global },
      } );

    More cryptic sources of side effects can include cache priming,
    idiosyncrasies of the underlying Perl implementation, or the state of
    the operating system and environment. For example, if the code to be
    benchmarked require a lot of in-process RAM, earlier tests may be slowed
    down by having to allocate the memory the first time, or later tests may
    be slowed down by having to pick through the heap looking for free
    space. These effects are difficult to predict and can be laborious to
    identify and compensate for.

    This module provides a solution to most aspects of this problem. Once
    you use Benchmark::Forking, the example benchmark above will report the
    correct conclusion that the three identical tests run at approximately
    the same speed.

VERSION
    This is version 1.00 of Benchmark::Forking.

INSTALLATION
    This module should work with any version of Perl 5, without platform
    dependencies or additional modules beyond the core distribution.

    You should be able to install this module using the CPAN shell
    interface:

      perl âMCPAN âe 'install Benchmark::Forking'

    Alternately, you may retrieve this package from CPAN
    ("http://search.cpan.org/~evo/") and follow the normal procedure to
    unpack and install it, using the commands shown below or their local
    equivalents on your system:

      tar xzf BenchmarkâForkingâ*.tar.gz
      cd BenchmarkâForkingâ*
      perl Makefile.PL
      make test &amp;&amp; sudo make install

SUPPORT
    Once installed, this moduleâs documentation is available as a manual
    page via "perldoc Benchmark::Forking" or on CPAN sites such as
    "http://search.cpan.org/dist/BenchmarkâForking".

    If you have questions or feedback about this module, please feel free
    to contact the author at the below address. Although there is no formal
    support program, I do attempt to answer email promptly.

    Bug reports that contain a failing test case are greatly appreciated,
    and suggested patches will be promptly considered for inclusion in
    future releases.

    To report bugs via the CPAN web tracking system, go to
    "http://rt.cpan.org/NoAuth/Bugs.html?Dist=BenchmarkâForking" or send
    mail to "Dist=BenchmarkâForking#rt.cpan.org", replacing "#" with "@".

    If youâve found this module useful or have feedback about your
    experience with it, consider sharing your opinion with other Perl users
    by posting your comment to CPANâs ratings system
    ("http://cpanratings.perl.org/rate/?distribution=BenchmarkâForking").

    For more general discussion, you may wish to post a message on
    PerlMonks ("http://perlmonks.org/?node=Seekers%20of%20Perl%20Wisdom")
    or on the comp.lang.perl.misc newsgroup
    ("http://groups.google.com/group/comp.lang.perl.misc/topics").

AUTHOR
    Developed by Matthew Simon Cavalletto.  You may contact the author
    directly at "evo@cpan.org" or "simonm@cavalletto.org".

    Inspired by a discussion with Jim Keenan in the Perl Monks community.

    My thanks also to other members of the Perl Monks community for
    feedback on this module, including graff, tachyon, Aristotle,
    pbeckingham, and others. http://perlmonks.org/?node_id=388481

LICENSE
    Copyright 2010, 2004 Matthew Simon Cavalletto.

    You may use, modify, and distribute this software under the same terms
    as Perl.

    See http://dev.perl.org/licenses/ for more information.
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