Comment 5 for bug 1526045

Reviewed: https://review.openstack.org/259172
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=adb21217955e59fce5fb194635b36b5b40d6d8c8
Submitter: Jenkins
Branch: master

commit adb21217955e59fce5fb194635b36b5b40d6d8c8
Author: Steve Baker <email address hidden>
Date: Fri Dec 18 09:10:46 2015 +1300

    Make minimum default num_engine_workers>=4

    Downstream test environments are frequently having failing stacks with
    error messages like:

      MessagingTimeout: resources[0]: Timed out waiting for a reply to
      message ID ...

    These environments generally have 1 or 2 cores, so only spawn one or two
    engine workers. This deadlocks with stacks that have many nested stacks
    due to engine->engine RPC calls.

    Even our own functional tests don't work reliably with less than 4
    workers, and the workaround has been to set that explicitly in
    pre_test_hook.sh.

    This change sets the default minimum number of workers to 4, but still
    matches workers to cores for larger servers.

    This change also moves the default evaluation to heat.cmd.engine so that
    generated configuration doesn't get a inappropriate default value.

    Change-Id: Iae6b3956bad414406d901bb2213c9ec230ff4304
    Closes-Bug: #1526045