p>
 The status code of the response always should be set for a servlet that throws or sends an error.

 
 <p>
 Servlets typically run inside multithreaded servlet containers that can handle multiple requests concurrently.
 Developers must be aware to synchronize access to any shared resources such as files, network connections, and as
 well as the servlet's class and instance variables.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>req</code> - the <code>ServletRequest</code> obj