log {
  my @args = @_;
  my $fmt   = shift @args;
  open my $fh, ">>", "/var/log/error.log" or return;
  printf {$fh} $fmt, @args;
  close $fh;
  return;
}

##</code><code>##

{
  my $buffer = "";
  sub _print {
    my @args = @_;
    $buffer .= sprintf shift @args, @args;
    return;
   }

   sub _flush {
     my $content = $buffer;
     $buffer = "";
     local $| = 1;
     print $content;
   }
}

_print($cgi->header( -type => .... ));
......
_flus();