Dear monks I have modified as per zentara's advice but now it goes into a endless loop and get's killed ultimately. can some one help me in this.

use threads ;
use feature "say";
#use strict;
use warnings;


`tr -d '\n' </home/guru/Desktop/sequence.fasta >modified_human_chr_1.t
+xt`;

my $input_file = "modified_human_chr_1.txt";
open my $hd, "<", $input_file or die "Couldn't open '$input_file' - $!
+";
my $text=<$hd>;
chomp($text);

my $window=5;
my $i=0;
LOOP:seek $hd,$i,0;
read ($hd,my $substring,$window);
my %hash;
if(length($substring)==$window)
{
    $hash{$substring}=$i;
    $i++;
    goto LOOP;
}

my $count = keys %hash;
my $j=0;

foreach my $pattern (keys %hash)
{
    if($j<=$count)
    {
        my $thr="thread".$j;
        $$thr=threads->create(\&hunter,$text,$pattern);
        
        $j++;
    }
}

my @returns;

foreach $thread (threads->list) 
{
       if ($thread->is_joinable() ) {  push @returns, $thread->join; }
       if( scalar (threads->list) == 0 ) {last;} 
}

print "@returns\n";

sub hunter
{
    my ($text,$pattern) = @_ ;
    
    my $offset = 0;

    print "\n$pattern ($window)\n";
    print '~' x $window,"\n";
    
    my $pos=index $text,$pattern,$offset;
    
    while ($pos != -1) 
    {
        print $pos+1," to ",$pos+$window,"\n";
        $offset = $pos + 99;
        $pos = index($text, $pattern, $offset);
    }
}
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