Reviewed: https://review.openstack.org/553857 Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=0372d82c2c5ae5651b00c5ab9e1cf5c77a8f87d9 Submitter: Zuul Branch: master
commit 0372d82c2c5ae5651b00c5ab9e1cf5c77a8f87d9 Author: Chris Dent <[email protected]> Date: Fri Mar 16 16:54:14 2018 +0000 Ensure that os-traits sync is attempted only at start of process Traits sync had been tried any time a request that might involve traits was called. If the global was set no syncing was done, but lock handling was happening. This change moves the syncing into the the deploy.load_app() handling. This means that the syncing will be attempted any time a new WSGI application is created. Most of the time this will be at the start of a new process, but some WSGI servers have interesting threading models so there's a (slim) possibility that it could be in a thread. Because of this latter possibility, the locking is still in place. Functional tests are updated to explicitly do the sync in their setUp(). Some changes in fixtures are required to make sure that the database is present prior to the sync. While these changes are not strictly part of extracting placement, the consolidation and isolation of database handling code makes where to put this stuff a bit cleaner and more evident: an update_database() method in deploy uses an empty DbContext class from db_api to the call the ensure_trait_sync method in resource_provider. update_database is in deploy because it an app deployment task and because putting it in db_api leads to circual import problems. blueprint placement-extract Closes-Bug: #1756151 Change-Id: Ic87518948ed5bf4ab79f9819cd94714e350ce265 ** Changed in: nova Status: In Progress => Fix Released -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1756151 Title: placement os-traits sync checked every request Status in OpenStack Compute (nova): Fix Released Bug description: Most requests to the placement service eventually reach the database code in the resource_provider.py file and as a result eventually run _ensure_trait_sync to make sure that this process has synced the os- traits library to its traits database table. While there is a flag to make sure that the syncing doesn't happen if it already happened before, we lock around checking that flag for nearly every request. This isn't the end of the world, but it is wasted activity and it can make a lot of noise in the logs if you're running DEBUG: 2018-03-15 17:35:37.653 7 DEBUG oslo_concurrency.lockutils [req-7904bbbe-52f7-420f-b058-13779dc018d1 admin admin - - -] Acquired semaphore "trait_sync" lock /usr/lib/python3.6/site-packages/oslo_concurrency/lockutils.py:212 2018-03-15 17:35:37.653 7 DEBUG oslo_concurrency.lockutils [req-7904bbbe-52f7-420f-b058-13779dc018d1 admin admin - - -] Releasing semaphore "trait_sync" lock /usr/lib/python3.6/site-packages/oslo_concurrency/lockutils.py:228 This is redundant. I'm pretty sure I wrote this code, so I'm not sure what I was thinking, probably cargo culting off ensuring the resource classes. We only need to sync the traits to the database once and we only need to check if it has been done once per process. The traits are read from a python module that is only imported once per process. So, what we could do is move the calling of ensure_trait_sync to the part of placement that establishes the database connection facade thingie. If we merge https://review.openstack.org/#/c/541435/ (which moves placement database connection establishment to its own file) or something like it, we have an easy place to do it, at server boot time. We find the session, make a context, do the sync, set the global and never worry about it again. All the _ensure_trait_sync calls can be removed. To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1756151/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
