2b6135364e
There was a bug when the ready queue wasn't empty, but there was no lower-priority fiber already in the queue. In that case the fiber wouldn't be inserted. We want the loop just to advance the iterator, but to perform the insert regardless of where the iterator ends up. (With this logic, empty() is no longer a special case.) Restore the ~Verbose() message.
boost.fiber
boost.fiber provides a framework for micro-/userland-threads (fibers) scheduled cooperativly. The API contains classes and functions to manage and synchronize fibers similiar to boost.thread.
A fiber is able to store the current execution state, including all registers and CPU flags, the instruction pointer, and the stack pointer and later restore this state. The idea is to have multiple execution paths running on a single thread using a sort of cooperative scheduling (threads are preemptively scheduled) - the running fiber decides explicitly when its yields to allow another fiber to run (context switching).
A context switch between threads costs usally thousends of CPU cycles on x86 compared to a fiber switch with less than 100 cycles. A fiber can only run on a single thread at any point in time.
Building: Detailed instructions can be found at https://svn.boost.org/trac/boost/wiki/TryModBoost.
boost.fiber is C++14-only!