...

      my $fbits = '';
      vec($fbits, fileno($socket), 1) = 1;

...

         my $rbits = $fbits;
         my $wbits = $write_wait ? undef : $fbits;
         my $nfound = select($rbits, $wbits, undef, $sel_timeout);

...

         if (defined($rbits) && $rbits =~ /[^\0]/) {
            # readable
            my $buf = $socket->_rbuf;
            my $n = $socket->sysread($buf, 1024, length($buf));
            unless ($n) {
               die "EOF";
            }

...