Comment 8 for bug 1045152

Reviewed: https://review.openstack.org/12985
Committed: http://github.com/openstack/nova/commit/47dabb30dc09282d56ad1e54c7652bf35394f7df
Submitter: Jenkins
Branch: stable/essex

commit 47dabb30dc09282d56ad1e54c7652bf35394f7df
Author: TianTian Gao <gtt116@126.com>
Date: Tue Sep 4 12:01:41 2012 +0800

    Yield to another greenthread when some time-consuming task finished.

    Partially addresses bug #1045152

    On a heavily loaded compute node, it can be observed that periodic tasks
    take so long to run that the report_state() looping call can be blocked from
    running long enough that the scheduler thinks the host is dead.

    Reduce the chance of this happening by yielding to another greenthread
    after each periodic task has completed and each loop in some methods
    that has linear relationship with the number of instances.

    Change-Id: If2b125708da8298b20497e2e08e52280c102f1e1