libevent2 (which tokio is very similar to) has the same constraint: > Currently, only one thread can be dispatching a given event_base at a time. If you want t

libevent2 (which tokio is very similar to) has the same constraint: > Currently, only one thread can be dispatching a given event_base at a time. If you want to run events in multiple threads at once, you can either have a single event_base whose events add work to a work queue, or you can create multiple event_base objects. http://www.wangafu.net/~nickm/libevent-2.1/doxygen/html/ http://www.wangafu.net/~nickm/libevent-2.1/doxygen/html/