I completely agree it is difficult and that's also my point - that shared multi-thread is very tricky to get right, and there is a significant benefit to isolat

I completely agree it is difficult and that's also my point - that shared multi-thread is very tricky to get right, and there is a significant benefit to isolated event loops (even if they are running on threads, they should be isolated). I like this article by Herb Sutter "The Trouble With Locks". http://gotw.ca/publications/mill36.htm http://gotw.ca/publications/mill36.htm I have used multi-(fiber/thread/process) extensively, and at the right place they are useful tools. But by far, threads which share data (especially opaque) are the most tricky to get right. The combinatorial explosion of program states is very hard to deal with in practice and "it works for me" is a very common testing strategy.