Comment 35 for bug 1946339

Reviewed: https://review.opendev.org/c/openstack/nova/+/908806
Committed: https://opendev.org/openstack/nova/commit/22cccb9bd9b5e1eb27f7e94855e734ed3863ab8a
Submitter: "Zuul (22348)"
Branch: stable/2023.1

commit 22cccb9bd9b5e1eb27f7e94855e734ed3863ab8a
Author: melanie witt <email address hidden>
Date: Thu May 11 19:23:52 2023 +0000

    tests: Use GreenThreadPoolExecutor.shutdown(wait=True)

    We are still having some issues in the gate where greenlets from
    previous tests continue to run while the next test starts, causing
    false negative failures in unit or functional test jobs.

    This adds a new fixture that will ensure
    GreenThreadPoolExecutor.shutdown() is called with wait=True, to wait
    for greenlets in the pool to finish running before moving on.

    In local testing, doing this does not appear to adversely affect test
    run times, which was my primary concern.

    As a baseline, I ran a subset of functional tests in a loop
    until failure without the patch and after 11 hours, I got a failure
    reproducing the bug. With the patch, running the same subset of
    functional tests in a loop has been running for 24 hours and has not
    failed yet.

    Based on this, I think it may be worth trying this out to see if it
    will help stability of our unit and functional test jobs. And if it
    ends up impacting test run times or causes other issues, we can
    revert it.

    Partial-Bug: #1946339

    Change-Id: Ia916310522b007061660172fa4d63d0fde9a55ac
    (cherry picked from commit c095cfe04e2c71efcfbfdd95948af080a98065e6)