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


my $file="/path_to_the_file" ;
our $file_handler ;
our $ref_file_handler ;
my ( $process_1 , $process_2 , $process_3 ) ;
my $flag_on_file = Thread::Queue->new ;


# main
open $file_handler, '<', $file or warn "$file : $!" and die;
$flag_on_file->enqueue(fileno($file_handler));

# threads creation
$process_1 = threads->new( \&my_sub );
$process_2 = threads->new( \&my_sub );
$process_3 = threads->new( \&my_sub );

# waiting for all threads to stop before exit
$process_1->join;
$process_2->join;
$process_3->join;

# end main


# sub
sub my_sub
{
	my( $fileno ) = $flag_on_file->dequeue ;
	open $ref_file_handler, "<&=$fileno" or warn $! and die;
for ( 1..10 )
	{
	# do something with the file
	# exemple
	print threads->self->tid.": ".scalar <$ref_file_handler> ;
	}
	close $ref_file_handler;
	$flag_on_file->enqueue(fileno($file_handler));
	# do something with data
}


exit;