Comment 21 for bug 1479815

Reviewed: https://review.openstack.org/222614
Committed: https://git.openstack.org/cgit/stackforge/fuel-library/commit/?id=a304fac9bf1ee4e98cfc355e3058b9664c2768c2
Submitter: Jenkins
Branch: stable/6.1

commit a304fac9bf1ee4e98cfc355e3058b9664c2768c2
Author: Dmitry Mescheryakov <email address hidden>
Date: Tue Aug 25 17:38:44 2015 +0300

    Make RabbitMQ OCF script tolerate rabbitmqctl timeouts

    The change makes OCF script ignore small number of timeouts of rabbitmqctl
    for 'heavy' operations: list_channels, get_alarms and list_queues.
    Number of tolerated timeouts in a row is configured through a new variable
    'max_rabbitmqctl_timeouts'. By default it is set to 1, i.e. rabbitmqctl
    timeouts are not tolerated at all.

    Bug #1487517 is fixed by extracting declaration of local variables
    'rc_alarms' and 'rc_queues' from assignment operations.

    Text for Operations Guide:

    If on node where RabbitMQ is deployed
    other processes consume significant part of CPU, RabbitMQ starts
    responding slow to queries by 'rabbitmqctl' utility. The utility is
    used by RabbitMQ's OCF script to monitor state of the RabbitMQ.
    When utility fails to return in pre-defined timeout, OCF script
    considers RabbitMQ to be down and restarts it, which might lead to
    a limited (several minutes) OpenStack downtime. Such restarts
    are undesirable as they cause downtime without benefit. To
    mitigate the issue, the OCF script might be told to tolerate
    certain amount of rabbitmqctl timeouts in a row using the following
    command:
      crm_resource --resource p_rabbitmq-server --set-parameter \
          max_rabbitmqctl_timeouts --parameter-value N

    Here N should be replaced with the number of timeouts. For instance,
    if it is set to 3, the OCF script will tolerate two rabbitmqctl
    timeouts in a row, but fail if the third one occurs.

    By default the parameter is set to 1, i.e. rabbitmqctl timeout is not
    tolerated at all. The downside of increasing the parameter is that
    if a real issue occurs which causes rabbitmqctl timeout, OCF script
    will detect that only after N monitor runs and so the restart, which
    might fix the issue, will be delayed.

    To understand that RabbitMQ's restart was caused by rabbitmqctl timeout
    you should examine lrmd.log of the corresponding controller on Fuel
    master node in /var/log/docker-logs/remote/ directory. Here lines like
    "the invoked command exited 137: /usr/sbin/rabbitmqctl list_channels ..."

    indicate rabbitmqctl timeout. The next line will explain if it
    caused restart or not. For example:
    "rabbitmqctl timed out 2 of max. 3 time(s) in a row. Doing nothing for now."

    DocImpact: user-guide, operations-guide

    Closes-Bug: #1479815
    Closes-Bug: #1487517
    Change-Id: I9dec06fc08dbeefbc67249b9e9633c8aab5e09ca
    (cherry picked from commit 2707a5ebbff7012a94de77b60fd594f5bcb29e05)