[Bug 1715254] Re: nova-novncproxy process gets wedged, requiring kill -HUP

[Seyeong Kim]

Hello Corey,
I've tested Trusty & UCA Icehouse.
However, I couldn't reproduce this issue. 
msgs in logs are different to kilo, mitaka, xenial

There is no 'Reaing zombies, active child count is'.
There are a lot of them on kilo, mitaka, xenial

I saw jame's latest commit which is patch for multiprocessing
but it seems not working on trusty, uca icehouse ( not sure 100% )

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Title:
  nova-novncproxy process gets wedged, requiring kill -HUP

Status in OpenStack nova-cloud-controller charm:
  Invalid
Status in Ubuntu Cloud Archive:
  Invalid
Status in Ubuntu Cloud Archive icehouse series:
  Triaged
Status in Ubuntu Cloud Archive kilo series:
  Triaged
Status in Ubuntu Cloud Archive mitaka series:
  Triaged
Status in websockify package in Ubuntu:
  Invalid
Status in websockify source package in Trusty:
  Triaged
Status in websockify source package in Xenial:
  Triaged

Bug description:
  [Impact]

  affected
  - UCA Mitaka, Kilo
  - Xenial

  not affected
  - UCA Icehouse
  - Trusty
  ( log symptom is different, there is no reaing(which is errata) zombie... etc)

  When number of connections are many or frequently reconnecting to
  console, nova-novncproxy daemon is stuck because websockify is hang.

  [Test case]

  1. Deploy openstack
  2. Creating instances
  3. open console in browser with auto refresh extension ( set 5 seconds )
  4. after several hours connection rejected

  [Regression Potential]

  Components that using websockify, escpecially nova-novncproxy, will be
  affected by this patch. However, After upgrading this and refreshing
  test above mentioned for 2 days without restarting any services, no
  hang happens. I tested this test in my local simple environment, so
  need to be considered possibility in different circumstances.

  [Others]

  related commits

  - https://github.com/novnc/websockify/pull/226
  - https://github.com/novnc/websockify/pull/219

  [Original Description]

  Users reported they were unable to connect to instance consoles via
  either Horizon or direct URL. Upon investigation we found errors
  suggesting the address and port were in use:

  2017-08-23 14:51:56.248 1355081 INFO nova.console.websocketproxy [-] WebSocket server settings:
  2017-08-23 14:51:56.248 1355081 INFO nova.console.websocketproxy [-]   - Listen on 0.0.0.0:6080
  2017-08-23 14:51:56.248 1355081 INFO nova.console.websocketproxy [-]   - Flash security policy server
  2017-08-23 14:51:56.248 1355081 INFO nova.console.websocketproxy [-]   - Web server (no directory listings). Web root: /usr/share/novnc
  2017-08-23 14:51:56.248 1355081 INFO nova.console.websocketproxy [-]   - No SSL/TLS support (no cert file)
  2017-08-23 14:51:56.249 1355081 CRITICAL nova [-] error: [Errno 98] Address already in use
  2017-08-23 14:51:56.249 1355081 ERROR nova Traceback (most recent call last):
  2017-08-23 14:51:56.249 1355081 ERROR nova   File "/usr/bin/nova-novncproxy", line 10, in <module>
  2017-08-23 14:51:56.249 1355081 ERROR nova     sys.exit(main())
  2017-08-23 14:51:56.249 1355081 ERROR nova   File "/usr/lib/python2.7/dist-packages/nova/cmd/novncproxy.py", line 41, in main
  2017-08-23 14:51:56.249 1355081 ERROR nova     port=CONF.vnc.novncproxy_port)
  2017-08-23 14:51:56.249 1355081 ERROR nova   File "/usr/lib/python2.7/dist-packages/nova/cmd/baseproxy.py", line 73, in proxy
  2017-08-23 14:51:56.249 1355081 ERROR nova     RequestHandlerClass=websocketproxy.NovaProxyRequestHandler
  2017-08-23 14:51:56.249 1355081 ERROR nova   File "/usr/lib/python2.7/dist-packages/websockify/websocket.py", line 909, in start_server
  2017-08-23 14:51:56.249 1355081 ERROR nova     tcp_keepintvl=self.tcp_keepintvl)
  2017-08-23 14:51:56.249 1355081 ERROR nova   File "/usr/lib/python2.7/dist-packages/websockify/websocket.py", line 698, in socket
  2017-08-23 14:51:56.249 1355081 ERROR nova     sock.bind(addrs[0][4])
  2017-08-23 14:51:56.249 1355081 ERROR nova   File "/usr/lib/python2.7/socket.py", line 224, in meth
  2017-08-23 14:51:56.249 1355081 ERROR nova     return getattr(self._sock,name)(*args)
  2017-08-23 14:51:56.249 1355081 ERROR nova error: [Errno 98] Address already in use
  2017-08-23 14:51:56.249 1355081 ERROR nova

  This lead us to the discovery of a stuck nova-novncproxy process after
  stopping the service. Once we sent a kill -HUP to that process, we
  were able to start the nova-novncproxy and restore service to the
  users.

  This was not the first time we have had to restart nova-novncproxy
  services after users reported that were unable to connect with VNC.
  This time, as well as at least 2 other times, we have seen the
  following errors in the nova-novncproxy.log during the time frame of
  the issue:

  gaierror: [Errno -8] Servname not supported for ai_socktype

  which seems to correspond to a log entries for connection strings with
  an invalid port ('port': u'-1'). As well as a bunch of:

  error: [Errno 104] Connection reset by peer

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