code: boolean incrementRequestCount( HttpServletRequest request, HttpServletResponse response,
                                     ServletContext servletContext )
          throws IOException
      {
          //
          // First cache the max-concurrent-request-count value.
          //
          if ( _maxConcurrentRequestCount == -1 )
          {
              _maxConcurrentRequestCount = DEFAULT_MAX_CONCURRENT_REQUEST_COUNT;
              assert servletContext != null;
  
              String countStr = servletContext.getInitParameter( MAX_CONCURRENT_REQUESTS_PARAM );
              if ( countStr != null )
              {
                  try
                  {
                      _maxConcurrentRequestCount = Integer.parseInt( countStr );
                  }
                  catch ( NumberFormatException e )
                  {
                      _log.error( "Invalid value for servlet context parameter" + MAX_CONCURRENT_REQUESTS_PARAM
                                  + ": " + countStr, e );
                  }
  
                  if ( _maxConcurrentRequestCount < 1 )
                  {
                      _maxConcurrentRequestCount = DEFAULT_MAX_CONCURRENT_REQUEST_COUNT;
                      _log.error( "Invalid value for servlet context parameter" + MAX_CONCURRENT_REQUESTS_PARAM
                                  + ": " + countStr );
                  }
              }
          }
  
          //
          // Now, if the current count of concurrent requests to this instance is greater than the max,
          // send an error on the response.
          //
          if ( _requestCount >= _maxConcurrentRequestCount )
          {
              if ( _log.isInfoEnabled() )
              {
                  _log.info( "Too many requests to FlowController " + getDisplayName() + " ("
                             + ( _requestCount + 1 ) + '>' + _maxConcurrentRequestCount + "); returning error code "
                             + EXCEEDED_MAX_CONCURRENT_REQUESTS_ERRORCODE );
              }
  
              response.sendError( EXCEEDED_MAX_CONCURRENT_REQUESTS_ERRORCODE );
              return false;
          }
  
          //
          // We're ok -- increment the count and continue.
          //
          ++_requestCount;
          return true;
      }
docs: Increment the count of concurrent requests to this FlowController.  Note that this method
  is not synchronized -- we use it to decide whether to synchronize on this instance,
  or to bail out with an error message about too many concurrent requests.