The $select->can_read() does not block, despite what documentation says. It keeps reporting that there's something in STDIN

Have you considered simplifying your code by using an event-loop system? For instance, can you use a simple program like this?

#!/usr/bin/perl 
use warnings;
use strict;
use Glib;

my $main_loop = Glib::MainLoop->new;

Glib::IO->add_watch (fileno 'STDIN', [qw/in/], \&watch_callback, 'STDI
+N');    

#just to show it's non blocking
my $timer1  = Glib::Timeout->add (1000, \&testcallback, undef, 1 );

$main_loop->run;

sub watch_callback {
#    print "@_\n";
    my ($fd, $condition, $fh) = @_;
    my $line = readline STDIN;
    print $line;
    #always return TRUE to continue the callback
    return 1;
}    

sub testcallback{
   print "\t\t\t".time."\n";

}
__END__
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POE is another eventloop alternative with an nice POE Cookbook See the section on ProcessManagement