Comment 3 for bug 1431097

Reviewed: https://review.openstack.org/276536
Committed: https://git.openstack.org/cgit/openstack/taskflow/commit/?id=cea71f27998cfa911044103fcb8fca79b6989717
Submitter: Jenkins
Branch: master

commit cea71f27998cfa911044103fcb8fca79b6989717
Author: Joshua Harlow <email address hidden>
Date: Thu Feb 4 18:09:24 2016 -0800

    Fix for WBE sporadic timeout of tasks

    This fixes the sporadic of tasks that would happen
    under certain circumstances. What happened was that
    a new worker notification would be sent to a callback
    while at the same time a task submission would come in
    and there would be a small race period where the task
    would insert itself into the requests cache while the
    callback was processing.

    So to work around this the whole concept of a requests
    cache was revamped and now the WBE executor just maintains
    its own local dictionary of ongoing requests and accesses
    it safely.

    During the on_wait function that is periodically called
    by kombu the previous expiry of work happens but now any
    requests that are pending are matched to any new workers
    that may have appeared.

    This avoids the race (and ensures that even if a new
    worker is found but a submission is in progress that the
    duration until that submission happens will only be until
    the next on_wait call happens).

    Related-Bug: #1431097

    Change-Id: I98b0caeedc77ab2f7214847763ae1eb0433d4a78