CORBA 3.4 RTF Avatar
  1. OMG Issue

CORBA34 — MAIN_THREAD_MODEL questions

  • Key: CORBA34-304
  • Legacy Issue Number: 4155
  • Status: closed  
  • Source: Borland Software Corporation ( Andy Cutright)
  • Summary:

    i have a few questions about the POA ThreadPolicy type
    MAIN_THREAD_MODEL.

    first, the 2.4.1 spec (00-11-03), sec 4.2.3.2 , 'perform_work' states,
    "If called by the main thread, this operation performs an
    implementation-defined unit of work; otherwise it does nothing."

    how is a distinguished main thread supposed to be reliably determined?
    i'm not sure we really need to define this. i'd think what we're trying
    to say is that the thread that calls perform_work() is the thread that
    will be used to do the work, and it is up to the application to make
    sure this happens. in section 4.2.3.3, the spec states,
    "For maximum portability an application should call either run or
    perform_work on its main thread."

    to me it seems the intent is to let the application determine what the
    'main thread' is.

    second, what happens if an application calls both run & perform_work?
    and what happens if the application calls run from multiple threads? it
    isn't really clear what the difference in request handling with regard
    to the thread used is between run() & perform_work().

    right now the spec seems to imply through the use of the message loop
    example in section 4.2.3.2 that perform_work is really intended to be
    used to handle situations where a single thread must be used for all
    application activity. now add to that the note on pg 11-12 about using
    the main thread model:
    "Note - Not all environments have such a special requirement. If
    not, while requests will be processessed sequentially, they may not all
    be processed on the same thread."

    my interpretation is that ORB::run would be used in cases where you
    simply want the POAs to be accessed sequentially, but the application
    doesn't care about which thread the implementation uses, but you would
    need to call perform_work to specifically hand the application defined
    main thread to process requests.

    my suggestion (finally ;^) is that we should state perform_work should
    be called, on whichever thread the application likes, if it wants to
    hand a specific thread to the ORB to do work. otherwise, calling
    ORB::run from any thread simply means the implementation is free to
    handle requests for servants associated with main thread model POAs on
    whatever thread the implementation may choose (including a new one), in
    keeping
    with the requirement that the requests be processed on each POA's
    servants sequentially..

    one more question: does it make sense to state that a callback type of
    architecture won't work when using this threading model?

  • Reported: CORBA 2.4.1 — Wed, 17 Jan 2001 05:00 GMT
  • Disposition: Deferred — CORBA 3.4
  • Disposition Summary:

    Deferred

    This proposal was generated automatically by request of the Task Force Chair Adam Mitz.

  • Updated: Mon, 30 Mar 2020 19:47 GMT