Comment 10 for bug 1454873

Reviewed: https://review.openstack.org/183217
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=60300b014952f5b2fa4c2a9010876f5b871f0f66
Submitter: Jenkins
Branch: master

commit 60300b014952f5b2fa4c2a9010876f5b871f0f66
Author: Zane Bitter <email address hidden>
Date: Fri May 15 17:18:12 2015 -0400

    Get rid of circular references in Resource and Function

    Circular references cause practically every bit of data that Heat uses to
    remain in memory until the completion of an operation, and even then to
    only be freed once the loop is detected by the garbage collector. By
    breaking all of the loops using weak references, we can ensure that things
    will get freed when they are no longer referenced without the need to wait
    for garbage collection (which should also take a lot less time). This
    change removes the loops from Resource and Function objects back to the
    Stack.

    Change-Id: Ibf80e95e69a2f27ed29754a2e0f1125e8eed0775
    Closes-Bug: #1454873