Async or event library

[rikki cattermole via Digitalmars-d-learn]

On 06/05/2016 9:40 PM, chmike wrote:
> On Thursday, 5 May 2016 at 09:21:04 UTC, rikki cattermole wrote:
>> Event loops needs to be thread local not per process.
>> So many API's such as WinAPI for e.g. GUI's have this requirement in
>> it that its just not worth fighting over.
>
> I don't understand. Do you mean that these event loops are single
> threaded and thus don't allow multi threaded use and parallel event
> handling ?
>
> Single threaded model avoids the overhead of synchronization. That would
> be another strong argument in favor of single threaded event loop. And
> another one is that single threaded application is much easier to get
> right than multi threaded applications.
>
> On the other side, WinAPI is old and the actual hardware evolution goes
> toward multi core computers and massive true parallelism. At CERN we use
> 16 core computers. Of course it's good to be backward compatible with
> existing APIs but D should be designed to best match the future of
> computing I think.
>
> So it seam the question boils down to determine if it's possible to have
> the best in both worlds.
>
> I agree that event loops working in isolation is the most simple API
> from the user perspective and is the most efficient since
> synchronization can be avoided. But worker thread pools has also its
> advantages when the app is running on a multicore computer.

Not even close :)

API's such as WinAPI are designed so that an event loop is per thread. 
This limitation is quite useful. You can see these limitations in X11 as 
well.

E.g. you can't go around drawing in another thread for a window.

For example WinAPI's GetMessage function has "Retrieves a message from 
the calling thread's message queue." 
https://msdn.microsoft.com/en-nz/library/windows/desktop/ms644936(v=vs.85).aspx

We can't fight stuff like this, its just not possible :)