Why use the performance advisors?

The performance advisors analyze the Performance Monitoring Infrastructure (PMI) data of WAS using general performance principles, best practices, and WebSphere-specific rules for tuning. The performance advisors that are based on this information provide advice on how to set some of your configuration parameters to better tune WebSphere Application Server.

The performance advisors provide a variety of advice on the following application server resources:

For example, consider the data source-prepared statement cache, which helps to decrease the cost of running a prepared statement by caching the compiled statement. If the cache is full, an old entry in the cache is discarded to make room for the new one. The best performance is generally obtained when the cache is large enough to hold all of the statements that are used in the application. The PMI counter prepared statement cache discards indicates the number of statements that are discarded from the cache. The performance advisors check this counter and provide recommendations to minimize the cache discards.

Using another example with pools in the application server, the idea behind pooling is to use an existing thread or connection from the pool instead of creating a new instance for each request. Because each thread or connection in the pool consumes memory and increases the context-switching cost, the pool size is an important configuration parameter. A pool that is too large can hurt performance as much as a pool that is too small. The performance advisors use PMI information about current pool usage, minimum or maximum pool size, and the application server CPU utilization to recommend efficient values for the pool sizes.

 

Related Tasks


Obtaining performance advice from the performance advisors