Region-based GC for Julia: worst event pause 4 ms → 55 µs

I run discrete-event simulations that drive hardware in the loop, which means every event has a deadline of about 100 µs. Julia’s collector is fine on throughput but occasionally it stops the world for milliseconds, and one collection in the wrong place is a missed deadline. The usual fix is pooling everything by hand. It works, but it turns every allocation site into ownership bookkeeping. I wanted to keep writing ordinary allocating Julia code and still bound the tail. So I built a region-ba...