Periodic_interval time affects cinder-scheduler service status

[wangwei]

There are a lot of volumes in my cinder-volumes, so it takes a lot of time for cinder to perform the periodic tasks.

I set the following parameters to 3600s in cinder.conf:

```
# Interval, in seconds, between running periodic tasks (integer value)
#periodic_interval = 60
```

This modification solves the problem of performing task time intervals. But there was another problem. When I restarted cinder-schulder, it only made the heartbeat after an hour to report status is up, and I could not create a volume during this time.

I debugged the code and found the reason here(cinder\cinder\service.py).

```
    def start(self):
        ...
        self.manager.init_host_with_rpc()
        ...
```
And in init_host_with_rpc function will sleep the time represented by the periodic_interval parameter:

```
    def init_host_with_rpc(self):
        print self.driver.is_ready()
        ctxt = context.get_admin_context()
        self.request_service_capabilities(ctxt)

        eventlet.sleep(CONF.periodic_interval)
        self._startup_delay = False
```

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/616440

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/616440
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=0db593d86c2566ee24af8f29b9f2cb2b805dc682
Submitter: Zuul
Branch: master

commit 0db593d86c2566ee24af8f29b9f2cb2b805dc682
Author: wangwei <email address hidden>
Date: Thu Nov 8 16:47:57 2018 +0900

    Fix the problem of the scheduler status

    During the startup process of cinder-scheduler, the time corresponding
    to the periodic_interval parameter will be sleeped. If the value of
    this parameter is large, such as one hour, then during this period the
    cinder-scheduler is always down and the volume cannot be created.

    This patch fixes this problem.

    Change-Id: I932a725c1665add590f09fa8d26e84b79b06e159
    Closes-bug: #1802249

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinder 14.0.0.0rc1 release candidate.