That concurrency testing capability is a pretty well-studied area and we implement a couple existing algorithms. The first is our adaptation of the PCT algorithm (ASPLOS'10 https://www.microsoft.com/en-us/research/wp-content/uploads/...). That's what you get by default with `--chaos`.
But we also have variations on straight up randomized scheduler (random thread selection at each time step).
I was going to ask if it could do the flip side - instead of stabilizing the scheduler, make it less predictable.
AFAICT, it can! Awesome, looking forward to giving it a try.