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<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Hi Howard,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">It was always intended that MPI_Session_init was a local procedure. In fact, “initialise a session” is not even an MPI operation, so it doesn’t make sense for it to be expressed
via a nonlocal procedure.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Further, it was intended that the nonlocal portion of the work done by MPI_Init that is eventually needed in the pure sessions pattern would be done during the first nonlocal procedure
call in that pattern, as follows:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">MPI_Session_init // local – PMIx fence prohibited<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">MPI_Group_from_pset // local – PMIx fence prohibited<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">MPI_Comm_create_from_group // nonlocal – PMIx fence permitted, if needed<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">The nonlocal work should be unnecessary until the first nonlocal procedure call, so this should all work out fine (modulo some refactoring/debugging).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Best wishes,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Dan.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt">From:</span></b><span lang="EN-US" style="font-size:11.0pt"> mpiwg-sessions <mpiwg-sessions-bounces@lists.mpi-forum.org>
<b>On Behalf Of </b>Pritchard Jr., Howard via mpiwg-sessions<br>
<b>Sent:</b> 04 January 2023 18:32<br>
<b>To:</b> MPI Sessions working group <mpiwg-sessions@lists.mpi-forum.org><br>
<b>Cc:</b> Pritchard Jr., Howard <howardp@lanl.gov><br>
<b>Subject:</b> [mpiwg-sessions] MPI_Session_init semantics question/poll<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Hi All,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">First, Happy New Year!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">I’ve got a question about the semantics of MPI_Session_init. In particular, I’d be interested in knowing people’s opinion on whether this function is nonlocal or local.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">We don’t have any text in the current version of the standard that states whether or not MPI_Session_init is a nonlocal operation.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">I’m considering options for handling this issue:
<a href="https://github.com/open-mpi/ompi/issues/11166">https://github.com/open-mpi/ompi/issues/11166</a> . It turns out that the way to properly resolve this issue depends on whether or not MPI_Session_init has local or nonlocal semantics.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">I had been working under the assumption that we had intended session initialization to be a local function, but considering how to resolve issue 11166 made me begin to question this assumption.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Thanks for any ideas,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Howard<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
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—</span><span lang="EN-US" style="font-size:11.0pt"><o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-family:"Arial",sans-serif;color:#0B1A8C">Howard Pritchard<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#545961">Research Scientist<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#545961">HPC-ENV<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0B1A8C">Los Alamos National Laboratory<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0B1A8C"><a href="mailto:howardp@lanl.gov">howardp@lanl.gov</a><o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0B1A8C"><o:p> </o:p></span></b></p>
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