[Python-ideas] yield from multiple iterables (was Re: The async API of the future: yield-from)

[Brett Cannon]

Go is available for Windows: http://golang.org/doc/install#windows

On Tue, Oct 23, 2012 at 10:48 AM, Guido van Rossum <guido at python.org> wrote:

> Thanks for the pointer to and description of libuv; it had come up in
> my research yet but so far I have not looked it up actively. Now I
> will. Also thanks for your reminder of the Goroutine model -- this is
> definitely something to look at for inspiration as well. (Though does
> Go run on Windows? Or is it part of a secret anti-Microsoft plan? :-)
>
> --Guido
>
> On Tue, Oct 23, 2012 at 12:19 AM, Benoit Chesneau <benoitc at gunicorn.org>
> wrote:
> >
> > On Oct 22, 2012, at 4:59 PM, Guido van Rossum <guido at python.org> wrote:
> >
> >> On Sun, Oct 21, 2012 at 10:30 PM, Steve Dower <
> Steve.Dower at microsoft.com> wrote:
> >> [Stuff about Futures and threads]
> >>
> >> Personally, I'm interested in designing a system, including an event
> >> loop, where you can rely on the properties of cooperative scheduling
> >> to avoid ever touching (OS) threading locks. I think such a system
> >> should be "pure" and all interaction with threads should be mediated
> >> by the event loop. (It's okay if this means that the implementation of
> >> the event loop must at some point acquire a threading lock.) The
> >> Futures used by the tasks to coordinate amongst themselves should not
> >> require locking -- they should themselves be able to rely on the
> >> guarantees of the event loop not to invoke multiple callbacks in
> >> parallel.
> >>
> >> IIUC you can do this on Windows with IOCP too, simply by only having a
> >> single thread reading events.
> >>
> >
> > Maybe it is worth to have a look on libuv and the way it mixes threads
> and  and event loop [1]. Libuv is one of the good event loop around able to
> use IOCP and other events systems on other arch (kqueue, …) and I was
> thinking when reading all the exchange around that it would perfectly fit
> in our cases. Or at least something like it:
> >
> > - It provides a common api for IO watchers: read, write, writelines,
> readable, writeable that can probably be extend over remote systems
> > - Have a job queue system for threds that is working mostly like the
> Futures but using the event loop
> >
> > In any case there is a pyuv binding [2] if some want to test. Even a
> twisted reactor [3]
> >
> > I myself toying with the idea of porting the Go concurrency model to
> Python [4] using greenlets and pyuv. Both the scheduler and the way IOs are
> handled:
> >
> > - In Go all coroutines are independent from each others and can only
> communicate via channel. Which has the advantage to allows them to run on
> different threads when one is blocking. In normal case they are mostly
> working like grrenlets on a single thread and are simply scheduled in a
> round-robin way. (mostly like in stackless). On the difference that
> goroutines can be executed in parallel. When one is blocking another thread
> will be created to handle other goroutines in the runnable queue.
> >
> > - For I/Os it exists a common api to all Connections and Listeners (Conn
> & Listen classes) that generally ask on a poll server. This poll server has
> for only task to register FDs and wake up the groutines that wait on read
> or fd events. This this poll server is running in a blocking loop it is
> automatically let by the scheduler in a thread. This pol server could be
> likely be replaced by an event loop if someone want.
> >
> > In my opinion the Go concurrency & memory model [5] could perfectly fit
> in the Python world and I'm surprised none already spoke about it.
> >
> > In flower greenlets could probably be replaced by generators but i like
> the API proposed by any coroutine pattern. I wonder if continulets [6]
> couldn't be ported in cpython to handle that…
> >
> > - benoît
> >
> >
> > [1] http://nikhilm.github.com/uvbook/threads.html &
> http://github.com/joyent/libuv
> > [2] https://github.com/saghul/pyuv
> > [3] https://github.com/saghul/twisted-pyuv
> > [4] https://github.com/benoitc/flower
> > [5] http://golang.org/ref/mem
> > [6] http://doc.pypy.org/en/latest/stackless.html#continulets
>
>
>
> --
> --Guido van Rossum (python.org/~guido)
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