[masklinn]

> In fact, I found it helpful. If your database is under load and is already running 4 heavy queries, not giving it any more jobs is actually a good thing.

Actually the threadpool shouldn't be a factor then, unless there are no nonblocking/async drivers for the database: internally, libuv uses its threadpool to asyncify operations for which no async/nonblocking version exists (Erlang does the same IIRC), for the most part it's filesystem operations, getaddrinfo and getnameinfo (I'm guessing it could include other stuff depending on what the underlying OS provides).

Socket or file IO should have native non-blocking APIs, so it does not need to use the threadpool.