Clarifying WebSphere XD's ODR Thread Limitation on CMT systems
By sunabl on Jan 04, 2008
In the IBM WebSphere eXtended Deployment (XD) On-Demand Router (ODR), the default thread pool size is set to a small value (i.e. 4 threads). The customers who use systems that have many hardware threads (e.g. Chip Multi-Thread (CMT) aka CoolThreads US-T1 and US-T2 processor based systems) perceive or are led to perceive that this is the limitation on these Sun CoolThreads system.
That is not true. The default thread pool size in ODR is configurable.
However, you do not want to make the default pool size to be too large (e.g. US-T2 has max 64 threads) as ODR does not need many threads to execute because of its asynchronous nature. It is more efficient to run the ODR with fewer threads to avoid getting into unnecessary context switching.