[nvarsj]

Choice of 1:1 or M:N is all about trade offs. NPLT chose 1:1 for simplicity (and decided to focus instead on making context switches cheap as possible in the Linux kernel). But that doesn’t mean M:N has no benefits - I think it does, as golang, erlang, and other languages illustrate.

I agree with OP that golang seems to provide the best of both worlds in the “event” vs “thread” debate. We can get the performance benefits of an eventing model with a much simpler programming model of thread per request.

It’s all “semantically” similar but it’s the details that matter. And I think golang chose the correct trade offs here (and with their sub-ms GC as well). The JVM, as an opposing example, made all the wrong choices I think for the general use case. Slow GCs and 1:1 threading.

I always understood the overhead of kernel threads compared to user threads to be significant at large scale. It’s not just stacks either. It can be a lot cheaper to swap between user threads, depending on implementation, compared to the scheduler having to preempt and trap into kernel code and provide a general purpose context switch.