Sun Microsystems 820434310 manual Manager Properties Reap Interval, Disable Dynamic JSP Reloading

Web Container Settings

Manager Properties: Reap Interval

Modifying the reap interval can improve performance, but setting it without considering the nature of your sessions and business logic can cause data inconsistency, especially for time-based persistence-frequency.

For example, if you set the reap interval to 60 seconds, the value of session data will be recorded every 60 seconds. But if a client accesses a servlet to update a value at 20 second increments, then inconsistencies will result.

For example, consider an online auction scenario as follows:

■Bidding starts at $5, in 60 seconds the value recorded will be $8 (three 20 second intervals).

■During the next 40 seconds, the client starts incrementing the price. The value the client sees is $10.

■During the client’s 20 second rest, the Application Server stops and starts in 10 seconds. As a result, the latest value recorded at the 60 second interval ($8) is be loaded into the session.

■The client clicks again expecting to see $11; but instead sees is $9, which is incorrect.

■So, to avoid data inconsistencies, take into the account the expected behavior of the application when adjusting the reap interval.

Disable Dynamic JSP Reloading

On a production system, improve web container performance by disabling dynamic JSP reloading. To do so, edit the default-web.xml file in theconfig directory for each instance. Change the servlet definition for a JSP file to look like this:

<servlet> <servlet-name>jsp</servlet-name>

<servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class> <init-param>

<param-name>development</param-name> <param-value>false</param-value>

</init-param> <init-param>

<param-name>xpoweredBy</param-name> <param-value>true</param-value>

</init-param> <init-param>

<param-name>genStrAsCharArray</param-name> <param-value>true</param-value>

</init-param> <load-on-startup>3</load-on-startup> </servlet>

52 Sun GlassFish Enterprise Server 2.1 Performance Tuning Guide • January 2009