Comment by gf000

Does preventing data races (which is not particularly hard if you are willing to give up certain properties, e.g. just immutability alone solves it) that much of a win?

You just made a bunch of concurrent algorithms un-implementable that would give much better performance for the benefit of.. having all the other unsolvable issues with concurrency? Like, all the same issues are trivially reproducible at a higher level, with loops within actors' communication that only appear under certain, very dynamic conditions, or a bunch of message passing ending up in an inconsistent state, just not on an "object" level, but on a "group of object" level.