10.11.2 Reducing persistent store I/O
From a performance point of view, the Web developer's considerations are the following:
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| Optimize the use of the HttpSession within a servlet. Only store the minimum amount of data required in HttpSession. Data that does not have to be recovered after a cluster member fails or is shut down can be best kept elsewhere, such as in a hash table. Recall that HttpSession is intended to be used as a temporary store for state information between browser invocations.
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| Specify session=false in the JSP directive for JSPs that do not need to access the session object.
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| Use time-based write frequency mode. This greatly reduces the amount of I/O, because the persistent store updates are deferred up to a configurable number of seconds. Using this mode, all of the outstanding updates for a Web application are written periodically based on the configured write interval.
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| Use the Schedule sessions cleanup option. When using the End of servlet service write frequency mode, WebSphere does not have to write out the last access time with every HTTP request. This is because WebSphere does not have to synchronize the invalidator thread's deletion with the HTTP request's access.
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