On Sunday, 12 June 2016 at 08:38:03 UTC, chmike wrote:
Fibers don't need synchronization to access shared data. This removes the overhead of synchronization and simplifies "multitheaded" programming greatly.
This is misleading. Any sort of cooperative system needs synchronization when two or more tasks try to access the same data, whether those "tasks" are OS threads, fibers, different machines on a network, etc.
Fibers do make it easier, as no task can run in parallel with the current one and switching tasks is done explicitly via yield, effectively giving the current fiber exclusive access to the entire program state in between yields. But if you need to hold onto a resource across a yield, you will need the usual set of concurrency primitives, like locks.
(A practical example: making a commit using the Node.js libgit bindings involves several asynchronous steps, during which other tasks may access it. If you don't want anyone else messing with the Git repo while you are making a commit, you must protect the repo with a lock.)
Also note that Vibe.d, the largest fiber-based framework D has to offer, is capable of running several coroutines in parallel on multiple threads, meaning you must use the same level of synchronization as if you were using threads.
