$tumblingWindow, $group, $sort, $lookup can have arbitrarily high memory usage. We need to detect all such high memory usage scenarios and throw necessary exceptions to prevent the pod from OOMing.

Filing this ticket to for tracking purposes. We should break up this ticket into multiple tickets eventually. Given how important it is to get this right, we would need a design doc for this.

Our behavior here also needs to be clearly documented for our users.