Erlang routinely runs 100,000 processes in the same memory space and scales very well. The reason it is possible to even handle this is that it is not based on

Erlang routinely runs 100,000 processes in the same memory space and scales very well. The reason it is possible to even handle this is that it is not based on shared memory but on message passing. There are two things at play here: a) Is the solution easy to design/code. b) Is the solution fast enough. There is far too much focus on (b) and relatively little attention is given to (a). The claim is that writing code in a direct style in a highly concurrent environment (Go, Erlang, Haskell, SML, ...) is easier and achieves roughly the same performance (within a factor of, say, 2). My experience is that this is true. I have seen fast evented and threaded systems. But I do feel the threaded systems were easier to write.