Concurrency

Warning

Concurrency is not yet fully implemented.

Concurrency is implemented with stackful fibers scheduled by a cooperative (not preemptive) scheduler. Only one fiber can run at a time, which essentially makes Mys single core. Multi core support may be added in the future if requested.

Fibers and asynchronous IO is currently implemented using pthreads and libuv.

See the fibers example for example code.

Scheduler

There are two fibers that are always present; the main fiber and the idle fiber. The main fiber calls the application entry point main(). The idle fiber is running when no other fiber is ready to run. It waits for IO events to occur and then reschedules to run other ready fibers.

The diagram below is an example of how three fibers; shell, main and idle are scheduled over time.

As it is a single core scheduler only one fiber is running at a time. In the beginning the system is idle and the idle fiber is running. After a while the main and shell fibers have some work to do, and since they have higher priority than the idle fiber they are scheduled. At the end the idle fiber is running again.