5 retries executed on deadlock by default but config shows 20

[Joanna Taryma]

The number of retries in case of database deadlock depends on configuration option [database]db_max_retries. The operation will be retried until it succeeds, but no more than db_max_retries times.

The default value of configuration option [database]db_max_retries is programmatically set to 5 in ironic. In originally comes from oslo.db, where it's set to 20.

Due to that, sample configuration for ironic will contain:
#db_max_retries = 20

Which can be misleading for operators - they may think the default is 20.

There was a patch posted to oslo.db to decrease the value to 5, but the value of 20 was rationalized:
https://review.openstack.org/#/c/442106/

Due to that, overwriting of the default value should be removed from ironic.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/440865
Committed: https://git.openstack.org/cgit/openstack/ironic/commit/?id=66b0bcfd0840a1c0e97c4337db8a8ad2c98f66a7
Submitter: Jenkins
Branch: master

commit 66b0bcfd0840a1c0e97c4337db8a8ad2c98f66a7
Author: Joanna Taryma <email address hidden>
Date: Fri Mar 10 10:41:27 2017 -0800

    Remove overwriting the default value of db_max_retries.

    Remove overwriting the default value of db_max_retries, instead use
    default value defined by oslo.db which is 20.
    Adjust the default value of db_max_retries in the release note and sample
    configuration file.

    Closes-Bug: #1671629
    Change-Id: I1e5f632d687c1cebab895cc91958d502b9fce884

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/ironic 8.0.0 release.