Re: [Kimchi-devel] [PATCH 2/3] model test for updating template

on 2014/10/24 21:12, Christy Perez wrote: > > > On 10/24/2014 01:43 AM, Zhou Zheng Sheng wrote: >> Hi Christy, >> >> I only found some indentation errors when running pep8 on this file. >> Maybe you can run a pep8 check manually and fix those problems. For the >> code itself, I think it's good. >> > Thanks Zhou. I'll take care of those. One question for you: > Did you happen to run the all the tests with this patch (sudo > ./run_tests.sh)? If I run that, I get a strange failure and a hang. If I > run just ./run_tests.sh test_model, the tests pass fine. > > I haven't been able to figure out what's going on. I noticed that if I > add a new test routine of any sort (so a stubbed out method) that I get > the error. As soon as I delete that new method signature, it goes away. > > It's always just after a debug report test failure, and then I just got > an abrt notification about the sos package. So, I'm wondering if this > has something to do with what I have installed (sos-3.1-1.fc20.noarch on > Fedora 20). > > None of the other test buckets in isolation will hit it, though. > > Regards, > > - Christy I just located the problem. It's a very nasty bug. The root cause is that libvirt connection is not shared between model instance. As you can see, each test method creates a new model instance, and each new model instance creates a new LibvirtConnection instance. The original purpose of LibvirtConnection is to share connections among the same instance. However in test_model, it results a fresh LibvirtConnection instance for each test method. It seems even after the model and LibvirtConnection instances go out of scope, the underlying libvirt connection is not closed. Maybe Python's garbage collection algorithm does not decide to clean those objects yet. There is also a known problem of circular reference counting in Python. Usually Python deal with circular reference very well. However if one of the object in the reference circle has customized __delete__() method, Python can not possibly know the correct release order, so it just refuse to garbage collect them. Unfortunately each class in libvirt Python binding has customized __delete__() method. I think this might be the cause why the underlying connection doesn't get freed. This problem is not related to your patch. Everyone who adds a new test case will hit this problem. I already drafted a fix for LibvirtConnection, I'm sending it after I address other problems in test_model.