1. A system, comprising: a server cluster, comprising: a plurality of server nodes, wherein each server node comprises: a server container; one or more applications configured to execute within the server container, wherein the one or more applications are configured to process requests from a plurality of users as sessions, wherein each session comprises a series of requests from a same user, wherein the one or more applications access and modify application state data during the processing of a given one of the sessions, wherein the application state data comprises session state data for the given one of the sessions; and a Java Data Object (JDO) persistence manager configured to detect changes to the application state data within the server container and to persist the application state data; and a persistent data store coupled to the cluster, configured to store application state data of the one or more applications of each respective server container, and configured to make the application state data accessible to each of the plurality of server nodes; wherein one of the applications of one of the plurality of server nodes is configured to access from the persistent data store application state data for a session that has previously been processed on another one of the plurality of server nodes; wherein in response to detecting a change in application state data within the server container, the JDO persistence manager is configured to persist only a changed portion of the application state data within the respective server container to the persistent data store.