I'm trying to find an example where using perlIO really makes a performance difference. To my surprise, when using PerlIO::via::MD5, I found that it is significantly slower than using traditional IO with Digest::MD5: 
    perlio:  1 wallclock secs ( 1.04 usr +  0.07 sys =  1.11 CPU) @ 62
+.16/s (n=69)
   regular:  1 wallclock secs ( 0.92 usr +  0.20 sys =  1.12 CPU) @ 19
+4.64/s (n=218)

[download]
Given that PerlIO::via::MD5 uses Digest::MD5 under the hood, this is really surprising. Is this just a bad example? Also, if you have examples on how perlIO significantly improved the performance of a task or made your life easier programming it, I'd like to hear about it.

Here's the code for the benchmark, the file examined was 500K in size: 

     use PerlIO::via::MD5;
     use Digest::MD5 qw(md5_hex);
     use Benchmark qw(:all);
 
     my $file = "somebigfile.dat";
 
     timethese(-1, {
         perlio  => \&perlio,
         regular => \&regular,
     });
 
     sub perlio {
         open(my $in,"<:via(MD5)", $file)
             or die "Can't open file for digesting: $!\n";
         my $digest = <$in>;
         close $in;
         return $digest;
     }
 
     sub regular {
         local($/) = undef;
         open FILE, $file
             or die "Can't open file for digesting: $!\n";
         my $data = <FILE>;
         close FILE;
 
         return md5_hex($data);
     }

[download]

In reply to PerlIO slower than traditional IO? by saintmike

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.