I changed my code so filedescriptor will be closed before threads starts and it works , so why this strange behavier ? i thought that filedescriptors r duped per thread on windows

use strict;
use warnings;
use threads;

mxu_install();

sub mxu_install
{
    my $count=0;
    my $kit_temp=$ARGV[0];
    if(!opendir(MXU_DIR,"$kit_temp/MXU"))
    {
    print "Can't open $kit_temp/MXU: $!";
    }
    

    
   while( defined (my $file = readdir MXU_DIR) ) 
    {
    next if $file =~ /^\.\.?$/;
    }
    
    closedir(MXU_DIR);
    install_mxu_comp();
    return;    
    
}

sub install_mxu_comp
{
    my $count=0;
    $|=1;
    my $thread1 = threads->new(\&blah);
    my $thread2=threads->new(\&blah);
    $thread1->join();
    $thread2->join();
    print "Father exiting\n";
    return 0;
}
sub blah
{
    print "inthread\n";
    sleep(5);
}
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