use strict;
use List::Util qw(shuffle);
use Parallel::ForkManager;

my $multi_cpu_num  = 2;
my @chars_1        = split '', 'ACTCTGCATGCATACGCATCAGCATCAT';
my @chars_2        = split '', 'TAGCTCATGTCGATGCATGCTCGTCTCG';


my $pm        = Parallel::ForkManager->new( $multi_cpu_num );

PWM:
for my $pwm (1..5) {
    $pm->start and next PWM;
    my @chars_1_temp   = shuffle @chars_1;
    my @chars_2_temp   = shuffle @chars_2;
    print "this is $pwm....\n";
    print join '',@chars_1_temp,"\n";
    print join '',@chars_2_temp,"\n";
    $pm->finish;
}

$pm->wait_all_children;

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I tried to use the above code to generate 5 different paired sequences using 2 CPU. But the result was only one paired sequences generated, the other four were cloned paired without shuffle. They were identical each other. I expected those five paired sequences were different. Why? If I do not use Parallel::ForkManager module, then everything is OK.

In reply to shuffle in Parallel::ForkManager; by plagent

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