AH00493: SIGUSR1 received. Doing graceful restart - Apache2 crashes - Can't access maas server URL

[Larry Michel]

We stopped being able to access maas through its web address and this caused a crash:

  File "/usr/lib/python2.7/dist-packages/oil_ci/common/maas.py", line 137, in get_tagged_nodes
    all_nodes_list = self.nodes_list(user)
  File "/usr/lib/python2.7/dist-packages/oil_ci/common/maas.py", line 378, in nodes_list
    return json.loads(self.cmd(command))
  File "/usr/lib/python2.7/dist-packages/oil_ci/common/maas.py", line 281, in cmd
    content = self.client.get(command).read()
  File "/usr/lib/python2.7/dist-packages/apiclient/maas_client.py", line 237, in get
    url, method="GET", headers=headers)
  File "/usr/lib/python2.7/dist-packages/apiclient/maas_client.py", line 116, in dispatch_query
    res = urllib2.urlopen(req)
  File "/usr/lib/python2.7/urllib2.py", line 127, in urlopen
    return _opener.open(url, data, timeout)
  File "/usr/lib/python2.7/urllib2.py", line 404, in open
    response = self._open(req, data)
  File "/usr/lib/python2.7/urllib2.py", line 422, in _open
    '_open', req)
  File "/usr/lib/python2.7/urllib2.py", line 382, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.7/urllib2.py", line 1214, in http_open
    return self.do_open(httplib.HTTPConnection, req)
  File "/usr/lib/python2.7/urllib2.py", line 1184, in do_open
    raise URLError(err)
URLError: <urlopen error [Errno 111] Connection refused>

On the apache2 error log, I saw:

ue Sep 27 06:25:12.159028 2016] [mpm_event:notice] [pid 1895:tid 140037883340672] AH00489: Apache/2.4.18 (Ubuntu) configured -- resuming normal operations
[Tue Sep 27 06:25:12.159257 2016] [core:notice] [pid 1895:tid 140037883340672] AH00094: Command line: '/usr/sbin/apache2'
[Wed Sep 28 06:25:09.318844 2016] [mpm_event:notice] [pid 1895:tid 140037883340672] AH00493: SIGUSR1 received. Doing graceful restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Wed Sep 28 06:25:12.038905 2016] [mpm_event:notice] [pid 1895:tid 140037883340672] AH00489: Apache/2.4.18 (Ubuntu) configured -- resuming normal operations
[Wed Sep 28 06:25:12.038944 2016] [core:notice] [pid 1895:tid 140037883340672] AH00094: Command line: '/usr/sbin/apache2'
[Wed Sep 28 06:25:14.040425 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 06:25:15.041505 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 06:25:16.042554 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 06:25:17.043605 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 06:25:18.045062 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 06:25:19.046130 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 06:25:20.047475 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 06:25:21.048295 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
... <repeats non-stop>
ull, not at MaxRequestWorkers
[Wed Sep 28 12:53:25.662213 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 12:53:26.663278 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 12:53:27.664325 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 12:53:28.665413 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
[Wed Sep 28 12:53:29.666492 2016] [mpm_event:error] [pid 1895:tid 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers

The errors stopped when I restarted the apache2 service with sudo service apache2 restart.

I couldn't tell where to find the core. There was only this file from a week ago:
$ ls -l _usr_sbin_apache2.0.crash
-rw-r----- 1 root root 2526598 Sep 21 22:33 _usr_sbin_apache2.0.crash

I tried to rerun it again and timestamp changed but core info did not appear to change.

I have collected access and error logs of the past couple of days as well as other logs including maas logs. Tarball is attached to this bug and it contains the 2 crash files:

$ ls -l _usr_sbin_apache2.0.crash.*
-rw-r----- 1 ubuntu ubuntu 2698755 Sep 28 13:42 _usr_sbin_apache2.0.crash.new
-rw-r----- 1 ubuntu ubuntu 2526598 Sep 21 22:33 _usr_sbin_apache2.0.crash.old

These are the package versions:

ii maas 2.0.0+bzr5189-0 all "Metal as a Service" is a physical cloud and I
ii apache2 2.4.18-2ubuntu3.1 amd64 Apache HTTP Server
ii apache2-bin 2.4.18-2ubuntu3.1 amd64 Apache HTTP Server (modules and other binary files)
ii apache2-data 2.4.18-2ubuntu3.1 all Apache HTTP Server (common files)
ii apache2-utils 2.4.18-2ubuntu3.1 amd64 Apache HTTP Server (utility programs for web servers)
ii init 1.29ubuntu2 amd64 System-V-like init utilities - metapackage

$ lsb_release -rd
Description: Ubuntu 16.04.1 LTS
Release: 16.04

[Christian Ehrhardt  (paelzer)]

Hi Larry,
I can't spot anything out of the log other than what you listed.
Those errors usually indicate either:
- non thread safe software with worker
- just overloading with more threads than allowed per config

For the latter you could take a look at:
- https://www.tectut.com/2016/04/workaround-for-scoreboard-is-full-not-at-maxrequestworkers/
- http://serverfault.com/questions/516373/what-is-the-meaning-of-ah00485-scoreboard-is-full-not-at-maxrequestworkers

For the former depending on your config it might be https://bz.apache.org/bugzilla/show_bug.cgi?id=48471

Could you take a look and see if any of that resolves the issue for you?

[Andres Rodriguez (andreserl)]

Larry,

Can you discontinue accessing MAAS over port 80 and start accessing it
through port 5240? And see if you have issues.

Apache does a bad job proxying!

On Wednesday, September 28, 2016, Larry Michel <email address hidden>
wrote:

> Public bug reported:
>
> We stopped being able to access maas through its web address and this
> caused a crash:
>
> File "/usr/lib/python2.7/dist-packages/oil_ci/common/maas.py", line
> 137, in get_tagged_nodes
> all_nodes_list = self.nodes_list(user)
> File "/usr/lib/python2.7/dist-packages/oil_ci/common/maas.py", line
> 378, in nodes_list
> return json.loads(self.cmd(command))
> File "/usr/lib/python2.7/dist-packages/oil_ci/common/maas.py", line
> 281, in cmd
> content = self.client.get(command).read()
> File "/usr/lib/python2.7/dist-packages/apiclient/maas_client.py", line
> 237, in get
> url, method="GET", headers=headers)
> File "/usr/lib/python2.7/dist-packages/apiclient/maas_client.py", line
> 116, in dispatch_query
> res = urllib2.urlopen(req)
> File "/usr/lib/python2.7/urllib2.py", line 127, in urlopen
> return _opener.open(url, data, timeout)
> File "/usr/lib/python2.7/urllib2.py", line 404, in open
> response = self._open(req, data)
> File "/usr/lib/python2.7/urllib2.py", line 422, in _open
> '_open', req)
> File "/usr/lib/python2.7/urllib2.py", line 382, in _call_chain
> result = func(*args)
> File "/usr/lib/python2.7/urllib2.py", line 1214, in http_open
> return self.do_open(httplib.HTTPConnection, req)
> File "/usr/lib/python2.7/urllib2.py", line 1184, in do_open
> raise URLError(err)
> URLError: <urlopen error [Errno 111] Connection refused>
>
> On the apache2 error log, I saw:
>
> ue Sep 27 06:25:12.159028 2016] [mpm_event:notice] [pid 1895:tid
> 140037883340672] AH00489: Apache/2.4.18 (Ubuntu) configured -- resuming
> normal operations
> [Tue Sep 27 06:25:12.159257 2016] [core:notice] [pid 1895:tid
> 140037883340672] AH00094: Command line: '/usr/sbin/apache2'
> [Wed Sep 28 06:25:09.318844 2016] [mpm_event:notice] [pid 1895:tid
> 140037883340672] AH00493: SIGUSR1 received. Doing graceful restart
> AH00558: apache2: Could not reliably determine the server's fully
> qualified domain name, using 127.0.1.1. Set the 'ServerName' directive
> globally to suppress this message
> [Wed Sep 28 06:25:12.038905 2016] [mpm_event:notice] [pid 1895:tid
> 140037883340672] AH00489: Apache/2.4.18 (Ubuntu) configured -- resuming
> normal operations
> [Wed Sep 28 06:25:12.038944 2016] [core:notice] [pid 1895:tid
> 140037883340672] AH00094: Command line: '/usr/sbin/apache2'
> [Wed Sep 28 06:25:14.040425 2016] [mpm_event:error] [pid 1895:tid
> 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
> [Wed Sep 28 06:25:15.041505 2016] [mpm_event:error] [pid 1895:tid
> 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
> [Wed Sep 28 06:25:16.042554 2016] [mpm_event:error] [pid 1895:tid
> 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
> [Wed Sep 28 06:25:17.043605 2016] [mpm_event:error] [pid 1895:tid
> 140037883340672] AH00485: scoreboard is full, not at MaxRequestWorkers
> [Wed Sep 28...

[Jason Hobbs (jason-hobbs)]

marked as invalid since we were using the wrong port.

[Bryce Harrington (bryce)]

Closing as resolved per comment #4