Re: [PATCH] python/xc: add missing Py_DECREF() to fix a memory leak

[Ian Campbell <ian.campbell@citrix.com>]

On Mon, 2015-08-31 at 13:32 +0100, Wei Liu wrote:
> On Mon, Aug 31, 2015 at 01:27:35PM +0100, Andrew Cooper wrote:
> > On 31/08/2015 13:04, Wei Liu wrote:
> > > On Fri, Aug 28, 2015 at 05:35:18PM -0400, Zhigang Wang wrote:
> > > > Python PyList_Append() will increase reference count of the item. 
> > > > We have to
> > > > decrease its reference count to let it garbage collected.
> > > > 
> > > > We missed the Py_DECREF() for 'cpuinfo_obj' here, thus we have a 
> > > > memory leak.
> > > > 
> > > > The memory leak could be easily confirmed by:
> > > > 
> > > >   # python
> > > >   >>> import xen.lowlevel.xc
> > > >   >>> xc = xen.lowlevel.xc.xc()
> > > >   >>> for i in range(1000): xc.getcpuinfo(1)
> > > > 
> > > > And check the python process memory usage before and after:
> > > > 
> > > >   # ps f -o vsize,rss,%mem,size,cmd -p <pid>
> > > > 
> > > > Signed-off-by: Zhigang Wang <zhigang.x.wang@oracle.com>
> > > Acked-by: Wei Liu <wei.liu2@citrix.com>
> > > 
> > > There is no in-tree user of python binding, I was planning to remove 
> > > it
> > > in 4.7 window.
> > 
> > I am sure I have mentioned this in the past, but XenServer still uses
> > them in places, and they are very useful to use from interactive 
> > sessions.
> > 
> 
> That's why I said "was". :-)
> 
> I don't mind leaving it in-tree given there is out-of-tree users.  The
> problem is I don't think I can do a good job maintaining this piece of
> code that I don't use and can't test, hence I encourage users to step
> forward to maintain this piece of code.

I too would be happy to see a patch to MAINTAINERS adding a section
covering at least tools/python/xen/lowlevel/xc (maybe xs too) and some
names of some actual users/maintainers of that code.

I think the xl bindings are properly dead and should be removed.

Ian.