Comment 4 for bug 1654086

Reviewed: https://review.openstack.org/417131
Committed: https://git.openstack.org/cgit/openstack/charm-percona-cluster/commit/?id=e47c4ad13517996963867e6d6a4765a0a8aa29f4
Submitter: Jenkins
Branch: master

commit e47c4ad13517996963867e6d6a4765a0a8aa29f4
Author: David Ames <email address hidden>
Date: Thu Jan 5 10:08:55 2017 -0800

    Default performance schema to off

    The 5.6 version of mysql defauls to performance_schema=on at server
    startup. This allocates all the memory that would be required to
    handle max-connections plus several other memory settings.

    We occasionally saw connection exhaustion in HA clouds with
    max-connections near 2000. The common practice became to set
    max-connections unrealistically high near 10k or 20k. In the move to
    5.6 on Xenial this became a problem as the memory requirements for
    values that high are unrealistic.

    This change adds performance schema as a configuration option and
    defaults to off giving 5.5 like behavior. It also considerably
    updates documentation and highlights the need to carefully consider
    memory related configuration settings for production environments.

    Make the amulet test python2 and python3 capable.

    Change-Id: Id01095ac2f73fa041b25b2602496a4c04a13e3ef
    Partial-Bug: #1654086
    Closes-Bug: #1600001