<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">I cannot speak to the threading issue, but I can say that MPI Sessions is of greater interest than just that area. Specifically, non-traditional programming models are looking for MPI to adopt methods that support async formation and teardown of communicators so they can augment their models with MPI support. Sessions was of interest from that perspective, but if not embraced by the MPI Forum in the not-too-distant future, people will simply drop MPI and go forward with PMIx Groups combined with direct messaging via libfabric or suitable alternative.<div class=""><br class=""></div><div class="">I think you all know I’m relatively neutral in the debate over programming models. I do fear, however, that MPI is making itself irrelevant by remaining stuck on static behaviors in an increasingly dynamic world. IMO, Sessions represents an interesting attempt to modernize the MPI programming model - I do hope it moves forward soon.</div><div class=""><br class=""></div><div class="">Ralph</div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Apr 23, 2019, at 12:48 PM, Aurelien Bouteiller via mpiwg-sessions <<a href="mailto:mpiwg-sessions@lists.mpi-forum.org" class="">mpiwg-sessions@lists.mpi-forum.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Guys, unfortunately I couldn’t attend the latest telecon, but I have been following the discussion from a distance. I’ll take the time to review the minutes of latest meetings. Is there one in particular that is summarizing the discussion?<div class=""><br class=""></div><div class="">Now my reticence is not only about thread levels. I really need to get convinced that sessions, as the interface is proposed, is a first step in achieving new capabilities (beyond fixing the threaded initialization problem). Most of the thread-safety capabilities we are talking about, especially when hidden behind the request, can be achieved with per-communicator with INFO keys, for example. Thus, in this case (and some others) sessions, as a concept, are not really improving on the state of the art, or provide a more elegant interface to achieve the goal. I hope that helps clarify my objections, which are not that sessions 'cannot do it’, but more on the line that often ’communicators can do it equally well’.<div class=""><div class=""><div class=""><div class=""><br class=""><div class=""><div class="">
<div style="caret-color: rgb(0, 0, 0); font-family: "Meslo LG S for Powerline"; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">Best,</div><div style="caret-color: rgb(0, 0, 0); font-family: "Meslo LG S for Powerline"; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">Aurelien</div>
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<div class=""><br class=""><blockquote type="cite" class=""><div class="">On Apr 22, 2019, at 12:47, HOLMES Daniel via mpiwg-sessions <<a href="mailto:mpiwg-sessions@lists.mpi-forum.org" class="">mpiwg-sessions@lists.mpi-forum.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" class="">
<div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">
Hi Howard,
<div class=""><br class="">
</div>
<div class="">I’ll be there today.</div>
<div class=""><br class="">
</div>
<div class="">We need to figure out what our purpose is for the meeting on 24th April - or cancel our involvement. Martin added two for us so they existed but we don’t have to use the 2nd one if we have nothing new to present/ask/etc.</div>
<div class=""><br class="">
</div>
<div class="">Point of information: the "function pointers” group just decided today that explicit function pointers as part of the MPI user-facing interface, are not necessary for any of the use-cases for which they were proposed. Thus, we are likely not going
to get function pointers + sessions any time ever. This is not a bad thing because one of those driving use-cases for function pointers was sessions - we convinced ourselves that the function pointers needed for sessions, e.g. to support different thread support
levels, can be hidden behind the existing MPI functions and opaque handles. For example, the MPI_Request handle could lead to a function pointer for the actual “wait” function inside the MPI library and another for the actual “test” function. The MPI_WAIT
and MPI_TEST functions will then be implemented as straightforward delegation shim functions that call down into the appropriate function pointer from the passed-in MPI_Request parameter. We should socialise that proposed approach with Aurelien (in particular)
because he voted against sessions in the Chattanooga straw poll because of the perceived lack of support for multiple thread support levels in use at the same time.<br class="">
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Cheers,</div>
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Dan.</div>
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—<br class="">
Dr Daniel Holmes PhD<br class="">
Applications Consultant in HPC Research<br class="">
<a href="mailto:d.holmes@epcc.ed.ac.uk" class="">d.holmes@epcc.ed.ac.uk</a><br class="">
Phone: +44 (0) 131 651 3465<br class="">
Mobile: +44 (0) 7940 524 088<br class="">
Address: Room 2.09, Bayes Centre, 47 Potterrow, Central Area, Edinburgh, EH8 9BT</div>
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—</div>
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The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.</div>
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—</div>
</div>
<div class=""><br class="">
<blockquote type="cite" class="">
<div class="">On 22 Apr 2019, at 17:16, Pritchard Jr.,<span class="Apple-tab-span" style="white-space:pre">
</span>Howard via mpiwg-sessions <<a href="mailto:mpiwg-sessions@lists.mpi-forum.org" class="">mpiwg-sessions@lists.mpi-forum.org</a>> wrote:</div>
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<div class="">
<div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class="">HI Sessions activists,<o:p class=""></o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class="">If possible, I’d like to meet today to discuss<o:p class=""></o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<a href="https://github.com/mpiwg-sessions/mpi-standard/pull/27" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">https://github.com/mpiwg-sessions/mpi-standard/pull/27</a><o:p class=""></o:p></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class="">and<o:p class=""></o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<a href="https://github.com/mpiwg-sessions/mpi-standard/pull/26" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">https://github.com/mpiwg-sessions/mpi-standard/pull/26</a><o:p class=""></o:p></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class="">as well as what to knock off next in<o:p class=""></o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<a href="https://github.com/mpiwg-sessions/sessions-issues/issues/10" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">https://github.com/mpiwg-sessions/sessions-issues/issues/10</a><o:p class=""></o:p></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class="">Reminder we have an hour in the upcoming virtual forum on 4/24.<o:p class=""></o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class="">Thanks,<o:p class=""></o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class="">Howard<o:p class=""></o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class="">-- <o:p class=""></o:p></span></div>
<div class="">
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 10.5pt;" class="">Howard Pritchard<o:p class=""></o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 10.5pt;" class="">HPC-ENV<o:p class=""></o:p></span></div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<span style="font-size: 10.5pt;" class="">Los Alamos National Laboratory<o:p class=""></o:p></span></div>
</div>
<div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif;" class="">
<o:p class=""> </o:p></div>
</div>
<span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">_______________________________________________</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">
<span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">mpiwg-sessions
mailing list</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">
<a href="mailto:mpiwg-sessions@lists.mpi-forum.org" style="color: rgb(149, 79, 114); text-decoration: underline; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">mpiwg-sessions@lists.mpi-forum.org</a><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">
<a href="https://lists.mpi-forum.org/mailman/listinfo/mpiwg-sessions" style="color: rgb(149, 79, 114); text-decoration: underline; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">https://lists.mpi-forum.org/mailman/listinfo/mpiwg-sessions</a></div>
</blockquote>
</div>
<br class="">
</div>
</div>
_______________________________________________<br class="">mpiwg-sessions mailing list<br class=""><a href="mailto:mpiwg-sessions@lists.mpi-forum.org" class="">mpiwg-sessions@lists.mpi-forum.org</a><br class=""><a href="https://lists.mpi-forum.org/mailman/listinfo/mpiwg-sessions" class="">https://lists.mpi-forum.org/mailman/listinfo/mpiwg-sessions</a><br class=""></div></blockquote></div><br class=""></div></div></div></div></div></div></div>_______________________________________________<br class="">mpiwg-sessions mailing list<br class=""><a href="mailto:mpiwg-sessions@lists.mpi-forum.org" class="">mpiwg-sessions@lists.mpi-forum.org</a><br class="">https://lists.mpi-forum.org/mailman/listinfo/mpiwg-sessions<br class=""></div></blockquote></div><br class=""></div></body></html>