Exactly: one of the two must be threaded, the swapping subsystem or the side serving clients. Since Redis serves clients in an event driven fashion our VM I/O p

Exactly: one of the two must be threaded, the swapping subsystem or the side serving clients. Since Redis serves clients in an event driven fashion our VM I/O part is threaded. But it was much simpler to design a threaded VM compared to a fully threaded Redis, and anyway there were other good reasons for implementing VM at application level.