Finalizing a Servlet

A servlet container may determine that a servlet should be removed from service (for example, when a container wants to reclaim memory resources or when it is being shut down). In such a case, the container calls the destroy method of the Servlet interface. In this method, you release any resources the servlet is using and save any persistent state. The destroy method releases the database object created in the init method.

A servlet’s service methods should all be complete when a servlet is removed. The server tries to ensure this by calling the destroy method only after all service requests have returned or after a server-specific grace period, whichever comes first. If your servlet has operations that may run longer than the server’s grace period, the operations could still be running when destroy is called. You must make sure that any threads still handling client requests complete.