Update: Added serial code. Am happy that IO in MCE is not too far behind. One day, will try another technique. IO aside, any CPU intensive operations such as regex do benefit from running with multiple workers.

Yes, IO will only go as fast as the underlying IO capabilities. MCE does sequential IO, meaning only one worker reads at any given time. The regex operation benefits from having multiple workers. Eventually, IO becomes the bottleneck.

 1 worker:   9.437 secs.
 2 workers:  4.480 secs.
 3 workers:  3.248 secs.
 4 workers:  3.236 secs.
 8 workers:  3.240 secs.

[download]

Below, removed counting and regex from the equation and running with 1 worker. It completes as fast as IO allows in 3.256 seconds.

mce_flow_f {
   chunk_size => '24m', max_workers => 1,
   use_slurpio => 1,
},
sub {

}, 'Dictionary2GB.txt';

[download]

The following serial code, reader only and without MCE, takes 2.864 seconds to read directly from the PCIe-based SSD drive, not from FS cache.

use strict;
use warnings;

my $size = 24 * 1024 * 1024;

open my $fh, '<', 'Dictionary2GB.txt' or die "$!";

while ( read( $fh, my $b, $size ) ) {
   $b .= <$fh>;
}

close $fh;

[download]

In reply to Re^3: How to optimize a regex on a large file read line by line ? by marioroy
in thread How to optimize a regex on a large file read line by line ? by John FENDER

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.