Hi, Recently we found in Neutron errors with starting our agents which uses eventlet.monkey_patch() method. Bug is described in [1]. I heard on IRC that it's not related only to Neutron so here is what we found about that. It looks that this issue happens on Ubuntu with python2.7 2.7.12-1ubuntu0~16.04.3 with eventlet < 0.22.0 (in OpenStack requirements it is set to 0.20.0). There is no this issue with python2.7.12-1ubuntu0~16.04.2 and eventlet 0.20.0 Something similar was already reported for monotonic in [2]. From one of comments there we found that problem can be caused because: "ctypes.util.find_library is now using subprocess.Popen, instead of os.popen (python/cpython at eb063011), and eventlet monkey-patches subprocess.Popen but not os.popen." It looks that eventlet patch [3] fixes/workaround this issue. I pushed similar patch to Neutron [4] and it looks that our issue is solved for now. I hope that maybe this info will be helpful for You :) [1] https://bugs.launchpad.net/neutron/+bug/1745013 [2] https://www.bountysource.com/issues/43892421-new-monotonic-broken-on-docker [3] https://github.comhttps://review.openstack.org/#/c/537863/1/eventlet/eventlet/commit/b756447bab51046dfc6f1e0e299cc997ab343701 [4] https://review.openstack.org/#/c/537863 — Best regards Slawek Kaplonski slawek at kaplonski.pl