[libvirt] [ libvirt-python BUG ?] Memory leak in libvirt_virConnectDomainEventJobCompletedCallback

[Michal Privoznik]

On 01/18/2017 08:51 AM, Hailiang Zhang wrote:
> Hi all,
> 
> It seems that, there is a memory leak bug in
> libvirt_virConnectDomainEventJobCompletedCallback()
> function of libvirt-override.c.
> 
> We didn't decrease the reference of 'pyobj_dict' in this function or any
> other places
> while pyt0bj_ret is not zero.
> 
> libvirt_virConnectDomainEventJobCompletedCallback()
> {
>   ... ...
> 
>   pyobj_ret = PyObject_CallMethod(pyobj_conn,
>                                    
> (char*)"_dispatchDomainEventJobCompletedCallback",
>                                     (char*)"OOO",
>                                     pyobj_dom, pyobj_dict, pyobj_cbData);
> 
>     Py_DECREF(pyobj_cbData);
>     Py_DECREF(pyobj_dom);
> 
>  cleanup:
>     if (!pyobj_ret) {
>         DEBUG("%s - ret:%p\n", __FUNCTION__, pyobj_ret);
>         PyErr_Print();
>         Py_XDECREF(pyobj_dict);
>     } else {
>         Py_DECREF(pyobj_ret);
>         ret = 0;
>     }
> 
>     LIBVIRT_RELEASE_THREAD_STATE;
>     return ret;
> }
> 
> I don't think the reference of pyobj_dict will be stolen by
> PyObject_CallMethod
> when it is passed to the Python function
> _dispatchDomainEventJobCompletedCallback.
> 
> In fact, we have a test which triggered lots of events and found that
> the memory
> of the test process will keep raising slowly and could not be reclaimed
> even we called gc.collect() explicitly in our codes.
> 
> So, is it a bug ? Any comments ?

Yes. we need to decrement the reference counter. Wanna propose the patch
and have the first contribution to libvirt-python? :-)

Michal