Logical Pool Distribution (LPD)

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

The need for LPD is indicated by a mixture of EJB requests where the execution times vary across the request types, and the ORB thread pool must be constrained for performance reasons. In this case, longer execution time requests may tend to elongate the response times for shorter execution time requests by denying them adequate access to threads in the thread pool. LPD provides a mechanism allow shorter execution time requests greater access to execution threads.

LPD divides the ORB thread pool into logical pools, as configured by the administrator using ORB custom properties starting with 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 vectored to a pool based on historical execution time history for the request type. The request type is determined by the method which is qualified internally as unique across components. The LPD mechanism adjusts pool targets at runtime to optimize the distribution of requests across logical pools.

After it is enabled, the LPD mechanism can be tuned. Tuning exercises should be driven by response time and throughput measurements, as well as statistics produced by the LPD mechanism.


See Also

Managing Object Request Brokers
Object Request Broker service settings that can be added to the administrative console