Comment by bjourne

But that scheme is the same as green threading and has the same faults. Start Julia with one system thread. Run one infinite loop in one green thread and another in another green thread. One of the loops will run while the other will wait until the other completes (which it never does). This is inferior to Java and C# which both uses system threads by default, allowing both infinite loops to run. Erlang/Elixir has the same problem. You can run thousands of green threads, but if one of them is stupid enough to call a blocking C function then all others have to wait.