The one axis isn't instantaneous workload; it is queue length(work items not being handled by threads). The PID controller is finding a reasonable number of wo

The one axis isn't instantaneous workload; it is queue length(work items not being handled by threads). The PID controller is finding a reasonable number of workers that handle the peak bursts without allowing the queue to get too long, and without spamming and destroying threads unnecessarily. The cost is that under peak load the queue does back up a little, but if the queue stayed long for too long, the PID should create new threads.