Removing thread support is _NOT_ an option (https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/MPI3Hybrid).
Unlike the usual claims on this mailing list, MPI_THREAD_MULTIPLE had been fully supported for several BTLs in Open MPI (http://www.springerlink.com/content/lmh1144p51317313/). The long term goal is to go back to at least the same level of support, and not to totally annihilate the efforts put into this in the past.
On Mar 11, 2011, at 03:54 , N.M. Maclaren wrote:
> On Mar 11 2011, Eugene Loh wrote:
>> The idea would be to hardwire support for MPI_THREAD_MULTIPLE to be off, just as we have done for progress threads. Threads might still be used for other purposes -- e.g., ORTE, openib async thread, etc.
> That's what I was assuming, too. Threads used behind the scene are not
> a problem - IF you can solve the infernal synchronisation and signalling
> problems and stop them causing trouble in other ways!
> Whether this should be done for MPI_THREAD_SERIALIZED, too, is debatable,
> but it can't be done using a cautious interpretation of any published
> standards that I know of, and in my experience can't be done reliably.
> That's not nice, and I don't want to go there :-(
> Nick Maclaren.
> devel mailing list
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