On Tuesday, 9 February 2016 at 17:41:34 UTC, NX wrote:
I would want it to be solved rather than being worked on... which requires design change which is probably not going to happen. There is still room for improvement though.
Right. I think there are at least two things that can improve current GC without any changes in design: parallel marking and lazy sweeping. Currently (at least last time I checked) GC pauses the world, then does all the marking in one thread, then all the sweeping. We can do the marking in several parallel threads (this is much harder to implement but still doable), and we can kick the sweeping out of stop-the-world pause and do the sweeping lazily: when you try to allocate some memory it will not just look in free lists, it will try to collect some unused unswept memory from the heap first. This way allocations become a bit slower but GC pause time reduces significantly. Concurrent sweeping is another possibility. Of course, it's all easier said than done, without an actual hero who would code this, it remains just talk.
