You can share filehandles between threads, thru the fileno. The following shows one way. You can also fork in a thread( piped-open, IPC::Open3), and pass the fileno back to the main thread thru a shared variable. Then you can read the IPC filehandle in the main thread, with select.

#!/usr/bin/perl
use warnings; 
use strict;
use threads;
use threads::shared;

# original idea from BrowserUK at  
# http://perlmonks.org?node_id=493754

for my $file ( map{ glob $_ } @ARGV ) {
  open my $fh, '<', $file or warn "$file : $!" and next;
  printf "From main: %s", scalar <$fh> for 1 .. 10;
  printf "Fileno:%d\n", fileno $fh;
  threads->create( \&thread, fileno( $fh ) )->detach;
  printf 'paused:';<STDIN>;
}


sub thread{
my( $fileno ) = @_;
open my $fh, "<&=$fileno" or warn $! and die;
printf "%d:%s", threads->self->tid, $_ while defined( $_ = <$fh> );
close $fh;
}
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