New option for num_threads for state change server

[OpenStack Infra]

https://review.openstack.org/317616
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.
Your project "openstack/neutron" is set up so that we directly report the documentation bugs against it. If this needs changing, the docimpact-group option needs to be added for the project. You can ask the OpenStack infra team (#openstack-infra on freenode) for help if you need to.

commit 70ea188f5d87c45fb60ace8b8405274e5f6dd489
Author: venkata anil <email address hidden>
Date: Tue May 17 16:30:13 2016 +0000

    New option for num_threads for state change server

    Currently max number of client connections(i.e greenlets spawned at
    a time) opened at any time by the WSGI server is set to 100 with
    wsgi_default_pool_size[1].

    This configuration may be fine for neutron api server. But with
    wsgi_default_pool_size(=100) requests, state change server
    is creating heavy cpu load on agent.
    So this server(which run on agents) need lesser value i.e
    can be configured to half the number of cpu on agent

    We use "ha_keepalived_state_change_server_threads" config option
    to configure number of threads in state change server instead of
    wsgi_default_pool_size.

    [1] https://review.openstack.org/#/c/278007/

    DocImpact: Add new config option -
    ha_keepalived_state_change_server_threads, to configure number
    of threads in state change server.

    Closes-Bug: #1581580
    Change-Id: I822ea3844792a7731fd24419b7e90e5aef141993

[Boden R (boden)]

As noted in the commit message; a new config option has been introduced. Moving this to the manual team so they can consume.

Note this is for master and there are separate bugs for other branches.

[Anne Gentle (annegentle)]

For this bug, the committer would run the config options script, autohelp_wrapper, in https://github.com/openstack/openstack-doc-tools/tree/master/autogenerate_config_docs. I think this was already run for ocata, as I'm finding the option in the new default values section of https://docs.openstack.org/ocata/config-reference/tables/conf-changes/neutron.html. I wanted to let you learn as you go, thanks Petra for looking for bugs to fix! You can close this with a Status of Fix Released. Here's more on the triaging process: https://docs.openstack.org/contributor-guide/doc-bugs.html#bug-triaging-process