Job and thread priorities
An IBM® i thread competes with threads throughout the system for scheduling resources in addition to competing with other threads in the same job.
The system schedules processing resources by using a delay cost scheduler that is based on several delay cost curves (priority ranges).
On IBM i, numerically lower priority values indicate higher priority with regard to scheduling. By adding its thread priority adjustment value to the job's priority, you can specify the priority of a thread. The default priority for a thread is no change from the process priority or a thread priority adjustment value of zero.
You can directly affect the application performance by assigning different thread priority adjustment values to the threads in your application.