It might make sense to add some stall-related status variables to the Unix implementation of the thread pool.
This could get incremented if the timer thread detects a stall. Around here:
This could get incremented if the timer thread does not create a new worker thread when a stall is detected because the thread group was still within the throttling interval. Around here:
This could get incremented every time a thread has to go to sleep because the thread group already has thread_pool_oversubscribe active threads. Around here: