Library implements cohort scheduling.
Fundamental action in a StagedServer system is to invoke an operation by creating and initializing a closure and handing it to a stage.
The same operations continues to be scheduled on the same processor (for affinity).
Scheduling details: wavefront algorithm to assign processors to stages. Also a threshold to force activation of a stage if too many waiting operations or wait too long.
Downside of waiting for operations with affinity is that they may not come or other stages might have a continual supply of operations.
Closure class used to implement operations and their continuations (what to do when invoked operation is done).