boost-coroutine

I'd like to create an asynchronous function which takes as it's last argument boost::asio::yield_context. E.g.: int async_meaning_of_life(asio::yield_context yield); I'd also like to be consistent with how Asio returns error codes. That is, if the user does: int result = async_meaning_of_life(yield); and the function fails, then it throws the system_error exception. But if the user does: boost::error_code ec; int result = async_meaning_of_life(yield[ec]); Then - instead of throwing - the error is returned in ec . The problem is that when implementing the function, I can't seem to find a clean

Background: I'm asking this because I currently have an application with many (hundreds to thousands) of threads. Most of those threads are idle a great portion of the time, waiting on work items to be placed in a queue. When a work item comes available, it is then processed by calling some arbitrarily-complex existing code. On some operating system configurations, the application bumps up against kernel parameters governing the maximum number of user processes, so I'd like to experiment with means to reduce the number of worker threads. My proposed solution: It seems like a coroutine-based