To support the Lwt kind of modules interface, orpc includes a port of the Lwt cooperative threads library to run on top of Ocamlnet’s Equeue, lwt-equeue. (XXX this is currently based on LWT 1.x; the next version of orpc will support LWT 2.x.)
Most of Lwt is unchaged; the Lwt_unix module is reimplemented in terms of Equeue operations. There is a new Lwt_equeue module for setting the event system. The intention is that lwt-equeue be link-compatible with regular Lwt.
In addition there are some new modules for condition variables, blocking queues and blocking priority queues.
See the Ocamldoc.