Comment 6 for bug 1808668

I also observed - I do not get above error on my other server which is RHEL 6 . I checked "ps -ef | grep mistral"found a small difference - Server which is failing does not have "/var/run/mistral/mistral-api.pid"

Server where mistral runs fine -

```
ps -ef | grep mistral
postgres 7240 7090 9 21:43 ? 00:05:25 postgres: mistral mistral 127.0.0.1(53346) idle
mistral 7445 1 0 2018 ? 00:15:20 /opt/stackstorm/mistral/bin/python /opt/stackstorm/mistral/bin/gunicorn --log-file /var/log/mistral/mistral-api.log -b 127.0.0.1:8989 -w 2 mistral.api.wsgi --graceful-timeout 10 --pid /var/run/mistral/mistral-api.pid
mistral 7506 1 18 2018 ? 10-17:17:49 /opt/stackstorm/mistral/bin/python /opt/stackstorm/mistral/bin/mistral-server --server engine,executor,notifier --config-file /etc/mistral/mistral.conf --log-file /var/log/mistral/mistral-server.log
postgres 7535 7090 0 21:45 ? 00:00:02 postgres: mistral mistral 127.0.0.1(53508) idle
postgres 8335 7090 0 21:51 ? 00:00:01 postgres: mistral mistral 127.0.0.1(54070) idle
postgres 8525 7090 0 21:53 ? 00:00:01 postgres: mistral mistral 127.0.0.1(54194) idle
mistral 8876 7445 2 2018 ? 1-14:17:09 /opt/stackstorm/mistral/bin/python /opt/stackstorm/mistral/bin/gunicorn --log-file /var/log/mistral/mistral-api.log -b 127.0.0.1:8989 -w 2 mistral.api.wsgi --graceful-timeout 10 --pid /var/run/mistral/mistral-api.pid
mistral 8877 7445 2 2018 ? 1-14:46:51 /opt/stackstorm/mistral/bin/python /opt/stackstorm/mistral/bin/gunicorn --log-file /var/log/mistral/mistral-api.log -b 127.0.0.1:8989 -w 2 mistral.api.wsgi --graceful-timeout 10 --pid /var/run/mistral/mistral-api.pid
postgres 16168 7090 9 22:09 ? 00:02:56 postgres: mistral mistral 127.0.0.1(55562) idle
postgres 16413 7090 9 22:11 ? 00:02:44 postgres: mistral mistral 127.0.0.1(55784) idle
postgres 16429 7090 9 22:11 ? 00:02:42 postgres: mistral mistral 127.0.0.1(55786) idle
postgres 17522 7090 9 22:21 ? 00:01:52 postgres: mistral mistral 127.0.0.1(56528) idle
postgres 17528 7090 9 22:21 ? 00:01:50 postgres: mistral mistral 127.0.0.1(56534) idle
postgres 17801 7090 9 22:23 ? 00:01:38 postgres: mistral mistral 127.0.0.1(56748) idle
postgres 21356 7090 0 22:39 ? 00:00:00 postgres: mistral mistral 127.0.0.1(58096) idle
```

servers where problem occurs -

```
 ps -ef | grep mistral
mistral 5076 1 0 2018 ? 00:02:29 /opt/stackstorm/mistral/bin/python /opt/stackstorm/mistral/bin/gunicorn --log-file /var/log/mistral/mistral-api.log -b 127.0.0.1:8989 -w 2 mistral.api.wsgi --graceful-timeout 10
mistral 5077 1 9 2018 ? 1-19:00:36 /opt/stackstorm/mistral/bin/python /opt/stackstorm/mistral/bin/mistral-server --server engine,executor,notifier --config-file /etc/mistral/mistral.conf --log-file /var/log/mistral/mistral-server.log
mistral 5109 5076 1 2018 ? 05:38:08 /opt/stackstorm/mistral/bin/python /opt/stackstorm/mistral/bin/gunicorn --log-file /var/log/mistral/mistral-api.log -b 127.0.0.1:8989 -w 2 mistral.api.wsgi --graceful-timeout 10
mistral 5110 5076 1 2018 ? 05:34:45 /opt/stackstorm/mistral/bin/python /opt/stackstorm/mistral/bin/gunicorn --log-file /var/log/mistral/mistral-api.log -b 127.0.0.1:8989 -w 2 mistral.api.wsgi --graceful-timeout 10
postgres 64806 1352 0 00:09 ? 00:00:01 postgres: mistral mistral 127.0.0.1(51245) idle
postgres 64808 1352 0 00:09 ? 00:00:08 postgres: mistral mistral 127.0.0.1(51247) idle
postgres 64922 1352 0 00:10 ? 00:00:08 postgres: mistral mistral 127.0.0.1(51351) idle
postgres 64971 1352 0 00:10 ? 00:00:07 postgres: mistral mistral 127.0.0.1(51355) idle
postgres 66303 1352 0 00:14 ? 00:00:00 postgres: mistral mistral 127.0.0.1(51379) idle
postgres 66642 1352 0 00:18 ? 00:00:00 postgres: mistral mistral 127.0.0.1(51389) idle
postgres 66733 1352 0 00:18 ? 00:00:05 postgres: mistral mistral 127.0.0.1(51391) idle
```