Adjusting queue settings for access patterns

In many cases, only a fraction of the requests passing through one queue enters the next queue downstream. In a site with many static pages, many requests are fulfilled at the Web server and are not passed to the Web container. In this circumstance, the Web server queue can be significantly larger than the Web container queue. In the previous section, the Web server queue was set to 75 rather than closer to the value of Max Application Concurrency. Similar adjustments need to be made when different components have different execution times. As the percentage of static content decreases, however, a significant gap in the Web server queue and the appserver queue can create poorly performing sites overall. Remember that tuning is an art, not a science, and different Web sites have different requirements.

For example, in an application that spends 90% of its time in a complex servlet and only 10% making a short JDBC query, on average 10% of the servlets are using database connections at any time, so the database connection queue can be significantly smaller than the Web container queue. Conversely, if much of a servlet execution time is spent making a complex query to a database, consider increasing the queue values at both the Web container and the data source. Always monitor the CPU and memory utilization for both the WAS and the database servers to ensure the CPU or memory are not being saturated.

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