Logical Pool Distribution

The Logical Pool Distribution (LPD) thread pool mechanism implements a strategy to improve the performance of requests that have shorter execution times.

If you notice a mixture of EJB requests with varying execution times across the request types, and the ORB thread pool must be constrained for performance reasons, you can use LPD to optimize performance. In this situation, requests with longer execution times might cause the response times to increase for requests with shorter execution times. Requests with long exection times might deny the other requests adequate access to threads in the thread pool. LPD allows requests with shorter execution times to have greater access to execution threads.

LPD divides the ORB thread pool into logical pools. To specify the number and size of these logical pools, use the administrative console to configure ORB custom properties that start with the string com.ibm.websphere.threadpool.strategy.*. The size of each pool is a percentage of the maximum number of ORB threads. The sum of the logical pool percentages should equal 100.

When LPD is active, incoming ORB requests are routed to a pool based on historical execution time data for the request type. The LPD mechanism adjusts pool targets at run time to optimize the distribution of requests across logical pools.

To enable and configure LPD, specify the appropriate custom properties for the ORB. For more information, see Set custom properties for the ORB service.

After you enable LPD, you can monitor its performance and tune its configuration. LPD tuning should be based on response time and throughput measurements, as well as statistics produced by the LPD mechanism.