If we are going to go through a major rewrite, I would suggest that we spend some serious time improving our test coverage, especially integration/smoketests. We need to know when our changes are breaking things. Any manpower that we can devote to this now will dramatically decrease the pain of switching over components in the future. I think switching one component at a time is probably the right way to go as well.
Vish On Wed, Aug 4, 2010 at 9:03 AM, Michael Gundlach < [email protected]> wrote: > All, > > I propose that we go ahead and decide to use Eventlet. We've all had a > chance to talk, the decision isn't going to make itself, and it seems like > we're coalescing around Eventlet: > > > - In a long discussion about how to keep our code loosely coupled and > easy to maintain (see Architecture For Shared Components on the openstack > list), we concluded that WSGI would be a great solution, and eday has > prototyped an Eventlet-powered WSGI app talking AMQP to Rabbit. The > Twisted > WSGI approach apparently isn't stable or standard, but WSGI works just as > you'd expect in Eventlet. > > > > - As hazmat points out in the "twisted v. eventlet" thread, you can't > use pdb with Twisted, while pdb works just as you'd hope in Eventlet. > > > > - hazmat's experience during his lightning talk (see the same thread) > is a good datapoint verifying that people unfamiliar with either project > will probably prefer to work with Eventlet over Twisted: good for > recruiting. > > > > - It's a weaker argument, but it's really hard to find any comparisons > between Twisted and Eventlet on the web that say Twisted is preferable (has > anyone found any?) > > > And as always, there's the argument that Eventlet code is easier to read > and understand, and therefore to maintain. > > I'm going to be working on adding the RS API to Nova, and I'm going to > proceed in Eventlet. If anyone feels strongly that we must use Twisted > instead, speak up; otherwise, shall we call this decision made? > > trying-to-build-consensus-ly yrs, > Michael > > > On Tue, Aug 3, 2010 at 8:13 AM, Soren Hansen > <[email protected]>wrote: > >> On Mon, Aug 02, 2010 at 05:21:23PM -0500, Eric Day wrote: >> > I took a closer look at the inner workings of how Twisted is currently >> > being used, and I think there is still a good chunk of work to be done >> > to make things work properly. For example, both Redis and AMQP modules >> > are not using the Twisted I/O event loop. Both are still issuing sync >> > socket calls in their own libs which could block the entire >> > application. >> >> Yup, this definitely needs fixing. >> >> > These things are very doable in Twisted, it will just require using >> > the txRedis and txAMQP modules. It will also introduce more deferreds >> > into the mix since we'll have non-blocking connections dependent on >> > each other. From this perspective, Eventlet may be easier since we >> > could still use the current libraries by patching >> > (http://eventlet.net/doc/patching.html). >> >> Yes, both python-redis and python-amqplib use Python's standard socket >> module, so they can be patched. >> >> Does anyone know how eventlet would deal with libvirt calls? >> python-libvirt just calls into libvirt obviously doesn't use Python's >> socket module. >> >> -- >> Soren Hansen >> Systems Architect >> The Rackspace Cloud >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~nova >> Post to : [email protected] >> Unsubscribe : https://launchpad.net/~nova >> More help : https://help.launchpad.net/ListHelp >> > > Confidentiality Notice: This e-mail message (including any attached or > embedded documents) is intended for the exclusive and confidential use of the > individual or entity to which this message is addressed, and unless otherwise > expressly indicated, is confidential and privileged information of Rackspace. > Any dissemination, distribution or copying of the enclosed material is > prohibited. > If you receive this transmission in error, please notify us immediately by > e-mail > at [email protected], and delete the original message. > Your cooperation is appreciated. > > > _______________________________________________ > Mailing list: https://launchpad.net/~nova > Post to : [email protected] > Unsubscribe : https://launchpad.net/~nova > More help : https://help.launchpad.net/ListHelp > >
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