#!/usr/bin/perl
use warnings; 
use strict;
use threads;
use IO::Select;
use FileHandle;

my @ranges = ( [1,10000000],[10000001,20000000],[20000001,30000000],
               [30000001,40000000],[40000001,50000000] );

my $sel = new IO::Select();

# thread launching

foreach (@ranges){
  my $fh = FileHandle->new();

  open ($fh,'+>', './dummyfile'); 
# needed to get filehandle to give a fileno
# maybe better to use IO::Handle and give it
# a fileno directly?

    my $start = $_->[0];
    my $end = $_->[1];
    my $fileno = fileno($fh);
    print "$start $end $fileno\n";

  threads->create( \&thread, $start, $end, $fileno )->detach;
  
  $sel->add($fh);
}

# watching thread output
print "Watching\n\n";
#while( scalar (threads->list) > 0 ){  # dosn't seem to work

while(1){     
       
     foreach my $h ($sel->can_read){
         my $buf;
         if ( (sysread($h, $buf, 1024) > 0 ) ){ 
           print "Main says: $buf\n"; 
           #truncate $h, 0;  # bad idea :-)
         }
     }
}


sub thread{

my( $start, $finish, $fileno ) = @_;

open my $fh, ">&=$fileno" or warn $! and die;
print $fh  "thread# ",threads->tid()," -> $start, $finish, $fileno \n"  ;

sleep 5;

print $fh  "thread# ",threads->tid()," -> finishing \n"  ;

}
__END__