dbapi_use_tpool exposes problems in eventlet

[Russell Bryant]

The dbapi_use_tpool option doesn't work completely because of problems in eventlet. Even though this is technically an eventlet issue, it's important for Nova so this bug is to track the issue getting fixed in eventlet.

There is a patch in progress here:

https://bitbucket.org/eventlet/eventlet/pull-request/29/fix-use-of-semaphore-with-tpool-issue-137/diff

[Viktor Serhieiev (vsergeyev)]

After the patch https://review.openstack.org/#/c/60031/ (Remove eventlet tpool from common db.api) was merged, eventlet tpool is not used for work with database in Oslo code

[Matt Riedemann (mriedem)]

This merged in nova on 4/22, so are we considering this bug closed?

https://review.openstack.org/#/c/59760/

[Chris Behrens (cbehrens)]

We still have the tpool option in nova... It was added back for nova specifically. We're still waiting on a release from eventlet with a fix. They some patches that they claim work... but they are not yet in any release, AFAIK.

[Sean Dague (sdague)]

seems like no one is working on this, putting it back into the pool.

[Davanum Srinivas (DIMS) (dims-v)]

Turning this into wishlist, since i don't see any signs of the eventlet fix getting in and there's nothing we can do in nova or oslo.db

[Markus Zoeller (markus_z) (mzoeller)]

The "use_tpool" option (formerly "dbapi_use_tpool") isn't anymore part of Nova with commit [1]. "oslo.db" on the other hand is still using this [2]. Therefore I'm removing "nova" as affected project but add "oslo.db" instead.

Unfortunately the eventlet fix is sill open [3].

References:
[1] https://github.com/openstack/nova/commit/1b83b2f#diff-83e0a63a67e7c5f5759f002a5fde8da9L51
[2] http://git.openstack.org/cgit/openstack/oslo.db/tree/oslo_db/concurrency.py#n29
[3] https://bitbucket.org/eventlet/eventlet/pull-requests/29/fix-use-of-semaphore-with-tpool-issue-137/diff