> A ton of energy’s been poured into research for garbage collection, particularly since Java has come up. There’s been hundreds of papers written in the academ

> A ton of energy’s been poured into research for garbage collection, particularly since Java has come up. There’s been hundreds of papers written in the academic circles, tons of work in HotSpot and other Java [2:03:30] implementations to do different tweaks and different tunings and different new kinds of algorithms in garbage collecting. That work really hasn’t been done for ARC yet, so really, I think there’s still a a big future ahead. I disagree strongly; there has been plenty of work in optimising reference counting systems. A quick look through Jones, Moss and Hosking's Garbage Collection Handbook provides many descriptions of high performance reference counting, but they all use deferred reference counting [1], rather than the immediate reference counting that Swift/Objective-C/Apple uses. That Apple is stuck in 1975 does not say much about other reference counting users. (Though Lattner only says "ARC", and I believe only Apple calls their refcounting "ARC"; I guess Rust has "Arc" as well, but that is a different thing completely. Else I haven't seen the acronym used elsewhere.) > But to do that, they use this tricolor algorithm which dramatically lowers throughput, because they’re doing almost exactly the same kinds of operations that ARC is doing. Concurrent tracing algorithms often log into a local buffer, without synchronisation. Whereas concurrent immediate reference counting performs atomic updates - it's almost exactly the same except for the parts where they really aren't the same. High performance concurrent RC systems also use local buffers [2] to avoid atomic updates too. Go figure. [1] http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.63.4603&rep=rep1&type=pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.63.... [2] https://sites.cs.ucsb.edu/~ckrintz/racelab/gc/papers/levanoni-on-the-fly-rc.pdf https://sites.cs.ucsb.edu/~ckrintz/racelab/gc/papers/levanon... page 5, figure 2 in particular