There were a lot of researchy implementations: "Writing Concurrent Object-Oriented Programs using Smalltalk-80" http://www.wolczko.com/mushroom/compj.pdf http

There were a lot of researchy implementations: "Writing Concurrent Object-Oriented Programs using Smalltalk-80" http://www.wolczko.com/mushroom/compj.pdf http://www.wolczko.com/mushroom/compj.pdf "Actra = A Multitasking / Multiprocessing Smalltalk" https://dl.acm.org/doi/10.1145/67387.67409 https://dl.acm.org/doi/10.1145/67387.67409 Actra -- an industrial strength concurrent object-oriented programming system https://dl.acm.org/doi/10.1145/127070.127090 https://dl.acm.org/doi/10.1145/127070.127090