The thread’s priority, which is specified by a floating point number from 0.0 to 1.0, where 1.0 is highest priority.
The priorities in this range are mapped to the operating system's priority values. A “typical” thread priority might be 0.5, but because the priority is determined by the kernel, there is no guarantee what this value actually will be.
Used to indicate the nature and importance of work to the system. Work with higher quality of service classes receive more resources than work with lower quality of service classes whenever there is resource contention.
This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.