Comment 6 for bug 1247056

Reviewed: https://review.openstack.org/75196
Committed: https://git.openstack.org/cgit/openstack/python-novaclient/commit/?id=36db3b95f556d5f57a2bf49303b24a0b25b4b7e8
Submitter: Jenkins
Branch: master

commit 36db3b95f556d5f57a2bf49303b24a0b25b4b7e8
Author: Tihomir Trifonov <email address hidden>
Date: Thu Feb 20 23:11:34 2014 +0200

    Fix in in novaclient, to avoid excessive conns

    The current client creates new .Session() on each request,
    but since Horizon is a stateless app, each Session creates
    new HttpAdapter, which itself has its own connection pool,
    and each connection there is used (almost) once and then
    is being kept in the pool(with Keep-Alive) for a certain
    amount of time(waiting for inactivity timeout). The problem
    is that the connection cannot be used anymore from next Django
    calls - they create new connection pool with new connections, etc.
    This keeps lots of open connections on the server.

    Now the client will store an HTTPAdapter for each URL into
    a singleton object, and will reuse its connections between
    Django calls, but still taking advantage of Sessions during
    a single page load(although we do not fully use this).

    Note: the default pool behavior is non-blocking, which means
    that if the max_pool_size is reached, a new connection will
    still be opened, and when released - will be discarded.
    It could be useful to add max_pool_size param into settings,
    for performance fine-tuning. The default max_pool_size is 10.

    Since python-novaclient is also used from non-Django projects,
    I'd expect feedback from more people on the impact this change
    could have over other projects.

    Patch Set 3: Removed explicit connection closing, leaving
    connections open in the pool.

    Change-Id: Icc9dc2fa2863d0e0e26a86c8180f2e0fbcd1fcff
    Closes-Bug: #1247056