GC pauses can be hundreds of milliseconds. You could perhaps use a particular GC scheme that guarantees you never have more than a couple millisecond pause, but then you have lots of pauses. That might have unintended consequences as well. I'm also not sure that such GCs, like golangs, can really mathematically guarantee a minimum pause time.
Hard real time garbage collectors have existed for decades. Of course you can mathematically guarantee a minimum pause time given a cap on allocation rate. What's stopping you?
You don't even need a cap on allocation rate, GC can have during allocation w/o fully blocking, it'd 'gracefully' degrade the allocation, itself. It'd be limited by CPU/memory latency and throughput.
