RE: [Xen-devel] xend leaks/bugs/etc

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> Hi. I'm a Twisted developer interested in improving xend. 
> First, I'm going to ensure that it runs on Twisted 2.0. I'd 
> also like to see if I can reproduce the memory leaks I've 
> seen reported here, and find out what can be done about them. 
> Eventually I'd like to refactor most of xend to use Twisted's 
> service architecture, which handles things like startup and 
> shutdown in a more modular fashion. (I'm working on a project 
> that could benefit from tighter integration with xend, but 
> the current codebase is not very friendly to that.) Is there 
> a list of existing problems with xend that I could refer to? 
> I attempted to reproduce the "xm list" memory leak, but was 
> not able to do so. (I am using Python 2.4.1 and yesterday's 
> xeno-unstable.) 

Allen, I think we've come to the conclusion that Twisted was rather
overkill for our needs, and led to some rather confusing code that has
proved hard to maintain. I've no doubt that someone more experienced
with using Twisted could have done a better job, but do you really think
it's the best route forward?  Xend is a 'control plane' daemon and
doesn't have to handle a high rate of invocations. It needs some ability
to handle asynchronous or out-of-order events, but this could be handled
by simple language-level threads (we don't need concurrency). 

The other downside of using Twisted is that its not available in some
distros, and we've had a few issues with version mismatches. It also has
quite an impact on the RSS memory footprint, which is not ideal.

What do you think?

Thanks,
Ian

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