in reply to Re^3: while reading a file, transfer the same data to two different processes.
in thread while reading a file, transfer the same data to two different processes.

Without 32M scalar it outputs: 

         Rate Threads   Forks
Threads 230/s      --     -0%
Forks   231/s      0%      --

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Re^5: while reading a file, transfer the same data to two different processes.
by BrowserUk (Patriarch) on May 20, 2010 at 23:23 UTC

    Thanks. If you've the inclination to indulge me a little further, what results do you get from the following? 

    use strict;
use warnings;
use threads;

my $str = 'x' x 32_000_000;

sub fork_wait {
    my $pid = fork;
    if ($pid) {
        wait;
    }
    else {
        my $l = length( $str );
        exit 0;
    }
}

sub create_thread_join {
    threads->create( sub { my $l = length( $str ) } )->join;
}

use Benchmark qw( cmpthese );

cmpthese - 3,
  {
    Forks   => \&fork_wait,
    Threads => \&create_thread_join,
  };

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                Rate Threads   Forks
Threads 25.2/s      --    -54%
Forks   54.7/s    118%      --

perl v5.10.1 built for x86_64-linux-thread-multi  (Ubuntu 8.04)


          Rate Threads   Forks
Threads 21.5/s      --    -72%
Forks   77.6/s    261%      --

perl v5.12.0 built for x86_64-linux-thread-multi  (openSUSE 11.1)

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[d/l]

        Interesting, thank you Almut.

        If you have time & inclination, I've one final line of enquiry: 

        use strict;
use warnings;
use threads;

my $str = 'x' x 32_000_000;

sub fork_wait {
    my $pid = fork;
    if ($pid) {
        wait;
    }
    else {
        substr( $str, $_, 1 ) &= ~ ' ' for 0 .. length( $str ) -1;
        exit 0;
    }
}

sub create_thread_join {
    threads->create( sub {
        substr( $str, $_, 1 ) &= ~ ' ' for 0 .. length( $str ) -1;
    } )->join;
}

use Benchmark qw( cmpthese );

cmpthese - 3,
  {
    Forks   => \&fork_wait,
    Threads => \&create_thread_join,
  };

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[reply]
[d/l]

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