use threads;
use Socket     qw( AF_UNIX SOCK_STREAM PF_UNSPEC );
use IO::Handle qw( );

sub _pipe {
    socketpair($_[0], $_[1], AF_UNIX, SOCK_STREAM, PF_UNSPEC)
        or return undef;
    shutdown($_[0], 1);  # No more writing for reader
    shutdown($_[1], 0);  # No more reading for writer
    return 1;
}

sub sockify_stdin {
    open(my $real_stdin, '<&', *STDIN)
        or die("Can't dup STDIN: $^E\n");
    _pipe(*STDIN, my $stdin_w)
        or die("Can't create socketpair: $^E\n");
    $stdin_w->autoflush(1);

    async {
        close(STDIN); # Close this threads's copy.
        print $stdin_w $_ while <$real_stdin>;
        close($stdin_w);
    }->detach();

    close($stdin_w); # Close this threads's copy.
}
[download]

use IO::Select qw( );

sockify_stdin();

my $stdin_buf = '';

my $sel = IO::Select->new(*STDIN);
while (my (@ready) = $sel->can_read()) {
    my $rv = sysread(*STDIN, $stdin_buf, 64*1024, length($stdin_buf));
    die if !defined($rv);
    last if !$rv;
    while ($stdin_buf =~ s/(.*\n)//g) {
        print "$1";
    }
}

print "$stdin_buf\n" if length($stdin_buf);
[download]

Thanks a lot!