Description of problem:

Satellite fails with "HTTP error (500 - Internal Server Error): PG::UniqueViolation: ERROR: duplicate key value violates unique constraint" while ruining concurrent registrations

Version-Release number of selected component (if applicable):

katello_version = katello-3.16.0-1.el7sat.noarch
satellite_version = satellite-6.8.0-1.el7sat.noarch

Steps to Reproduce:

• Try to run concurrent registration on Satellite 6.8

Actual results:

~~~

HTTP error (500 - Internal Server Error): PG::UniqueViolation: ERROR: duplicate key value violates unique constraint \"index_operatingsystems_on_title

~~~

Expected results: It should register at least 300 hosts concurrently (300 number in comparison to Satellite 6.7)

Additional info:

when pool size is set : 30 (suggested on BZ - https://projects.theforeman.org/issues/29370) : concurrent registration failed with specified error.

Similar or related to this bug

https://bugzilla.redhat.com/show_bug.cgi?id=1878067