openstack team mailing list archive

[Duncan McGreggor <duncan@xxxxxxxxxxxxx>]

On Fri, Mar 2, 2012 at 2:40 PM, Johannes Erdfelt <johannes@xxxxxxxxxxx> wrote:
> On Fri, Mar 02, 2012, Armando Migliaccio <Armando.Migliaccio@xxxxxxxxxxxxx> wrote:
>> I agree, but then the whole assumption of adopting eventlet to simplify
>> the programming model is hindered by the fact that one has to think
>> harder to what is doing...Nova could've kept Twisted for that matter.
>> The programming model would have been harder, but at least it would
>> have been cleaner and free from icky patching (that's my own opinion
>> anyway).
>
> Twisted has a much harder programming model with the same blocking
> problem that eventlet has.

Like so many things that are aesthetic in nature, the statement above
is misleading. Using a callback, event-based, deferred/promise
oriented system is hard for *some*. It is far, far easier for others
(myself included).

It's a matter of perception and personal preference.

It may be apropos to mention that Guido van Rossum himself has stated
that he shares the same view of concurrent programming in Python as
Glyph (the founder of Twisted):
  https://plus.google.com/115212051037621986145/posts/a9SqS7faVWC

Glyph's post, if you can't see that G+ link:
  http://glyph.twistedmatrix.com/2012/01/concurrency-spectrum-from-callbacks-to.html

One thing to keep in mind is that with Twisted, you always have the
option of deferring to a thread for operations are not async-friendly.

d