Sync I/O API's are still an issue, the main one being JDBC. The approach with Quasar is to have a dedicate thread pool for the JDBC calls, which in that case is

Sync I/O API's are still an issue, the main one being JDBC. The approach with Quasar is to have a dedicate thread pool for the JDBC calls, which in that case isn't necessarily too bad as you don't want to overload your database. Comsat is the companion project which provides the quasar fiber integration to common libraries/services (http, servlet, db etc) which gives you the nice synchronous programming model (via bytecode instrumentation) with the async/light thread scalability. So your incoming servlet request would use the async servlet API integration to move the execution to a fiber. Then calls to an external http service, out-of-process cache, files, NoSQL db etc would all happen within the fibers. Its mainly the JDBC that requires a pool of normal threads. I've only just decided this is what I want to use next, so I'll be able to tell from experience over the coming months!