[Matthias247]

> Embedding islands of cooperative multitasking in a sea of pre-emptive multitasking seems to make a lot more sense than the other way around.

Pretty much my opinion. I think a preemptive threaded environment where some threads might run multiple async tasks (in order to boost efficiency) can make a lot of sense.

Pure cooperative environments seem too error-prone for bigger systems, because they lack the necessary isolation between tasks. Any bad task can degenerate the performance of all others tasks by blocking the execution thread.