Debugging stuck vdsm jobs

[Nir Soffer]

Hi all,

We had 2 issues causing vdsm check-patch and check-merge jobs to get stuck.

I fixed the one that caused most trouble:
https://gerrit.ovirt.org/57993

The other issue may be related to ioprocess, I fixed a related issue:
https://gerrit.ovirt.org/57473

But I have seen stuck jobs after this change, so the issue may not
be fixed yet.

If you see a stuck vdsm job - job that run more than 15 minutes, please
get me a backtrace:

1. locate the test_runner process pid:

    $ ps aux | grep testrunner.py | grep -v grep
    nsoffer  26297 82.6  0.9 389592 111144 pts/3   R+   22:52   0:02
/usr/bin/python ../tests/testrunner.py ...

2. save a backtrace:

    gdb attach 26297 --batch -ex "thread apply all py-bt" > py-bt.out

Thanks,
Nir