#!/usr/bin/perl

use strict;
use warnings;
use IO::BufferedSelect;

my $fh1;
my $fh2;

my $bs = new IO::BufferedSelect($fh1, $fh2);
while(1)
{
    my @canBeRead = $bs->read_line();
    foreach (@canBeRead) 
    { 
        my ($fh, $line) = @$_;
        my $fh_name = ($fh == $fh1 ? "fh1" : "fh2");
        print "fh_name: $line\n";
    }
}