#! perl -slw
use strict;
use threads;
use Thread::Queue;

our $T //= 10;
our $N //= 1000;

my $Q = new Thread::Queue;

async{
    my $tid = threads->tid;

    open my $cmd, '-|', 'count.pl ' . int( rand $N ) or die $!;

    $Q->enqueue( "$tid:$_" ) while defined ( $_ = <$cmd> );
    $Q->enqueue( "$tid:done\n" );
    $Q->enqueue( undef );
}->detach for 1 .. $T;

for( 1 .. $T ) {
    while( $_ = $Q->dequeue ) {
        printf "%s", $_;
    }
}

__END__
##This is count.pl
#! perl -slw
use strict;

$|++;
my $i = $ARGV[0] // 30;

print --$i while $i and sleep 1;