Some time ago, we added the ability to optionally configure a pool so that it would count a deferred task as taking up a pool slot.
It strikes me that there isn't much point in specifying a pool for a deferrable task if the task will not take up a slot when it is deferred. why? well the point of deferrable task is, the task spends most of it's lifecycle in deferred state. is it useful to have it take up a slot at the first and last couple seconds of its lifecycle? methinks no. seems to me for 3.0 we should just declare that tasks that have a pool will occupy a pool slot for the whole "running" lifecycle (which may include task execution and deferral). and ideally it would occupy the slot continuously (and not vacate the slot e.g. when the task momentarily becomes "scheduled" after coming out of deferral. maybe we need better precision without states to do this but let's think about what is ideal for the moment. DISCUSS
