openstack/openstack-ansible
Code Issues Proposed changes

Limit the number of Ansible forks used to 10

Browse Source 
The default MaxSessions setting for SSHD is 10. Each Ansible fork makes use of
a Session, so this patch still uses the CPU number to set the number of forks
used but limits it to 10 forks when the number of CPU's is larger.

Developer Docs and Install Guide Docs entries have been included.

Closes-Bug: #1479812
Change-Id: I9abd33e184c706796ede9963393876a8aae9837c
This commit is contained in:
Jesse Pretorius
2015-10-01 10:12:03 +01:00
parent 7a12374003
commit fe3b328023
4 changed files with 54 additions and 2 deletions
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12
doc/source/developer-docs/scripts.rst
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@@ -58,6 +58,18 @@ to skip the execution of the Ceilometer playbook, execute:
export DEPLOY_CEILOMETER='no'
The default MaxSessions setting for the OpenSSH Daemon is 10. Each Ansible
fork makes use of a Session. By default Ansible sets the number of forks to 5,
but the ``run-playbooks.sh`` script sets the number of forks used based on the
number of CPU's on the deployment host up to a maximum of 10.
If a developer wishes to increase the number of forks used when using this
script, override the FORKS environment variable. For example:
.. code-block:: bash
export FORKS=20
run-tempest.sh
--------------

27
doc/source/install-guide/app-tips.rst Normal file
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@@ -0,0 +1,27 @@
`Home <index.html>`__ OpenStack Ansible Installation Guide
Appendix C. Tips and Tricks
---------------------------
Ansible Forks
~~~~~~~~~~~~~
The default MaxSessions setting for the OpenSSH Daemon is 10. Each Ansible
fork makes use of a Session. By default Ansible sets the number of forks to 5,
but a deployer may wish to increase the number of forks used in order to
improve deployment performance in large environments.
This may be done on a permanent basis by adding the `forks`_ configuration
entry in ``ansible.cfg``, or for a particular playbook execution by using the
``--forks`` CLI parameter. For example, to execute the
``os-keystone-install.yml`` playbook using 10 forks:
.. code-block:: bash
openstack-ansible --forks 10 os-keystone-install.yml
.. _forks: http://docs.ansible.com/ansible/intro_configuration.html#forks
--------------
.. include:: navigation.txt

1
doc/source/install-guide/index.rst
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@@ -60,3 +60,4 @@ Appendices
app-configfiles.rst
app-resources.rst
app-tips.rst

16
scripts/scripts-library.sh
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@@ -23,8 +23,20 @@ REPORT_DATA=${REPORT_DATA:-""}
ANSIBLE_PARAMETERS=${ANSIBLE_PARAMETERS:-""}
STARTTIME="${STARTTIME:-$(date +%s)}"
# the number of forks is set as the number of CPU's present
FORKS=${FORKS:-$(grep -c ^processor /proc/cpuinfo)}
# The default SSHD configuration has MaxSessions = 10. If a deployer changes
# their SSHD config, then the FORKS may be set to a higher number. We set the
# value to 10 or the number of CPU's, whichever is less. This is to balance
# between performance gains from the higher number, and CPU consumption. If
# FORKS is already set to a value, then we leave it alone.
if [ -z "${FORKS:-}" ]; then
CPU_NUM=$(grep -c ^processor /proc/cpuinfo)
if [ ${CPU_NUM} -lt "10" ]; then
FORKS=${CPU_NUM}
else
FORKS=10
fi
fi
## Functions -----------------------------------------------------------------
# Used to retry a process that may fail due to random issues.