Servlet Instances
By default, (at most) one instance of a given servlet class will ever be created by a Web server process.
By default, the servlet class is loaded into the Web server’s JVM, and the unique servlet instance is created, the first time any client sends a request to a URL identifying the servlet class.
Subsequent requests to the same URL are all handled by the same servlet class instance.
- By default, however, each request is handled in a different Java thread.
This means that a later request can access results of processing an earlier request through values of instance variables (or class variables).