NIO and servlets

Java 1.4 introduced a brand-new I/O API, commonly known as NIO. The
 arrival of NIO, which among other things lets you work efficiently with I/O streams without them
 blocking one another, prompted discussion about using it in servlet containers.

Greg Wilkins, the author of the Jetty
 web server and servlet container, wrote about combining NIO and the Servlet API. He identified the main challenge as
 combining the non-blocking features of NIO with the blocking streams used by servlets.