Comment 44 for bug 1626675

Reviewed: https://review.openstack.org/384718
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=df889488ede2d3cad30afdc8cd66fb1b92492ede
Submitter: Jenkins
Branch: master

commit df889488ede2d3cad30afdc8cd66fb1b92492ede
Author: Zane Bitter <email address hidden>
Date: Mon Oct 10 15:11:42 2016 -0400

    Avoid loading nested stacks in memory where possible

    Prior to changing StackResource to do stack operations over RPC, we made
    liberal use of the StackResource.nested() method to access the nested stack
    that was likely always loaded in memory. Now that that is no longer
    required, it adds additional memory overhead that we need not have. We can
    now obtain the stack identifier without loading the stack, and that is
    sufficient for performing operations over RPC.

    The exceptions are prepare_abandon(), which cannot be done over RPC at
    present, and get_output(), which may be addressed in a separate patch. The
    gratuitous loading of the nested stack in TemplateResource.get_attribute()
    is eliminated, so although it still ends up loading the nested stack in
    many cases, it will no longer do so once get_output() stops doing it.

    Change-Id: I669d2a077381d7e4e913f6ad1a86fb3f094da6c5
    Co-Authored-By: Thomas Herve <email address hidden>
    Related-Bug: #1626675