Comment 2 for bug 1554233

Reviewed: https://review.openstack.org/289664
Committed: https://git.openstack.org/cgit/openstack/swift/commit/?id=d9c4913e3b1aaba378d4786ddfefa6265c195f71
Submitter: Jenkins
Branch: master

commit d9c4913e3b1aaba378d4786ddfefa6265c195f71
Author: Samuel Merritt <email address hidden>
Date: Mon Mar 7 18:18:35 2016 -0800

    Make eventlet.tpool's thread count configurable in object server

    If you're running servers_per_port > 0 and threads_per_disk = 0 (as it
    should be with servers_per_port on), each object-server process will
    have 20 IO threads waiting around to service eventlet.tpool
    calls. This is far too many; with servers_per_port, there's no real
    benefit to having so many IO threads.

    This commit makes it so that, when servers_per_port > 0, each object
    server defaults to having one main thread and one IO thread.

    Also, eventlet's tpool size is now configurable via the object-server
    config file. If a tpool size is set, that's what we'll use regardless
    of servers_per_port. This allows operators with an excess of threads
    to remove some regardless of servers_per_port.

    Change-Id: I8f8914b7e70f2510393eb7c5e6be9708631ac027
    Closes-Bug: 1554233