[Python-Dev] microthreading vs. async io (original) (raw)

Phillip J. Eby pje at telecommunity.com
Thu Feb 15 17:32:03 CET 2007

At 11:00 PM 2/14/2007 -0600, dustin at v.igoro.us wrote:

Instead, I would like to concentrate on producing a small, clean, consistent, generator-based microthreading library. I've seen several such libraries (including the one in PEP 342, which is fairly skeletal), and they all work almost the same way, but differ in, for example, the kinds of values that can be yielded, their handling of nested calls, and the names for the various "special" values one can yield.

Which is one reason that any "standard" coroutine library would need to be extensible with respect to the handling of yielded values, e.g. by using a generic function to implement the yielding. See the 'yield_to' function in the example I posted.

Actually, the example I posted would work fine as a microthreads core by adding a thread-local variable that points to some kind of "scheduler" to replace the Twisted scheduling functions I used. It would need to be a variable, because applications would have to be able to replace it, e.g. with the Twisted reactor.

In other words, the code I posted isn't really depending on Twisted for anything but reactor.callLater() and the corresponding .isActive() and .cancel() methods of the objects it returns. If you add a default implementation of those features that can be replaced with the Twisted reactor, and dropped the code that deals with Deferreds and TimeoutErrors, you'd have a nice standalone library.

More information about the Python-Dev mailing list