Bump up Erlang Thread pool using RABBITMQ_SERVER_ERL_ARGS

[Davanum Srinivas (DIMS)]

The default thread pool for rabbitmq-server is set to 30, when there are more cores available we should be bumping up this number higher for better performance

Background:
https://github.com/rabbitmq/rabbitmq-server/pull/212/commits
http://www.rabbitmq.com/networking.html
https://github.com/rabbitmq/rabbitmq-server/issues/178
https://github.com/rabbitmq/rabbitmq-server/issues/176

[Davanum Srinivas (DIMS) (dims-v)]

In our older rabbitmq environment, we should set RABBITMQ_SERVER_ERL_ARGS

[root@node-13 ~]# find / -name rabbitmq-* -exec grep -H -i RABBITMQ_SERVER_ERL_ARGS {} \;
/usr/lib/rabbitmq/lib/rabbitmq_server-3.3.5/sbin/rabbitmq-server:[ "x" = "x$RABBITMQ_SERVER_ERL_ARGS" ] && RABBITMQ_SERVER_ERL_ARGS=${SERVER_ERL_ARGS}
/usr/lib/rabbitmq/lib/rabbitmq_server-3.3.5/sbin/rabbitmq-server:# RABBITMQ_SERVER_ERL_ARGS, contain terms that look like globs and
/usr/lib/rabbitmq/lib/rabbitmq_server-3.3.5/sbin/rabbitmq-server: ${RABBITMQ_SERVER_ERL_ARGS} \
/usr/lib/rabbitmq/bin/rabbitmq-server:[ "x" = "x$RABBITMQ_SERVER_ERL_ARGS" ] && RABBITMQ_SERVER_ERL_ARGS=${SERVER_ERL_ARGS}
/usr/lib/rabbitmq/bin/rabbitmq-server:# RABBITMQ_SERVER_ERL_ARGS, contain terms that look like globs and
/usr/lib/rabbitmq/bin/rabbitmq-server: ${RABBITMQ_SERVER_ERL_ARGS} \
/etc/puppet/modules/nailgun/examples/rabbitmq-only.pp: 'RABBITMQ_SERVER_ERL_ARGS' => '+K true +A30 +P 1048576',

[Davanum Srinivas (DIMS) (dims-v)]

A note from Alex:

Alexander Nevenchannyy: @dims: yes, i'm agree. but i'm think we must use +A N from fuel library according cpu count at controller node

[Alexey Khivin (akhivin)]

Suggested to set default thread pool to N*12
Where N is number of real cores

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/201064

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/201064
Committed: https://git.openstack.org/cgit/stackforge/fuel-library/commit/?id=d2573ceea0b726b81c9e82680108fdfa92b2ec6f
Submitter: Jenkins
Branch: master

commit d2573ceea0b726b81c9e82680108fdfa92b2ec6f
Author: Alexander Arzhanov <email address hidden>
Date: Mon Aug 3 14:48:44 2015 +0300

    Bumping up thread pool for rabbitmq-server

    The default thread pool for rabbitmq-server is set to 30,
    when there are more cores available we should be bumping
    up this number higher for better performance.

    Change-Id: Ie98fcd49a2dc35fd212e15d4d78a9a4c8c4e44bf
    Closes-bug: 1472793

[Nastya Urlapova (aurlapova)]

VERSION:
  feature_groups:
    - mirantis
  production: "docker"
  release: "7.0"
  openstack_version: "2015.1.0-7.0"
  api: "1.0"
  build_number: "301"
  build_id: "301"
  nailgun_sha: "4162b0c15adb425b37608c787944d1983f543aa8"
  python-fuelclient_sha: "486bde57cda1badb68f915f66c61b544108606f3"
  fuel-agent_sha: "50e90af6e3d560e9085ff71d2950cfbcca91af67"
  fuel-nailgun-agent_sha: "d7027952870a35db8dc52f185bb1158cdd3d1ebd"
  astute_sha: "6c5b73f93e24cc781c809db9159927655ced5012"
  fuel-library_sha: "5d50055aeca1dd0dc53b43825dc4c8f7780be9dd"
  fuel-ostf_sha: "2cd967dccd66cfc3a0abd6af9f31e5b4d150a11c"
  fuelmain_sha: "a65d453215edb0284a2e4761be7a156bb5627677"