Need PMIX1.2.1 for v2.1 release

[hppritcha]

This issue tracks getting PMIX2 in the v2.1 release. The shared memory dstore is an important feature when trying to support 100's of MPI processes on a single node.

[hppritcha]

per discussion in Dallas this is being marked as a blocker.

[ggouaillardet]

btw, is this feature working on master now ?
It was disabled because it broke MPI_Comm_spawn, and i do not recall that has been fixed

[jsquyres]

Per discussion with @rhc54 this morning, there is still some development work occurring for PMIx 2.0. After that is complete and merged to master, then it can be ported to v2.1.0.

[jjhursey]

@rhc54 Which branch of PMIx is tracking the PMIx 2.0 effort? I found three references to v2.x in the PMIx set of repos:

• https://github.com/pmix/master/tree/v2.x
• https://github.com/pmix/releases/tree/v2.x
• https://github.com/pmix/releases/tree/release/v2.x

I would be interested in helping test.

[rhc54]

I've been shifting the release tree over to the master repo, just as we did for ompi. However, I can't say for certain that I have it fully up-to-date. I'll get things squared away tomorrow

[rhc54]

@jjhursey I have consolidated the PMIx release branches into the pmix/master repo, and all branches over there are now up-to-date.

[jjhursey]

Ref openpmix/openpmix#141

Timeline (rough - certainly up for discussion):

• Get that PR into PMIx master (after pending testing)
• Update Open MPI master internal PMIx component (opal/mca/pmix/pmix3x)
• Test Open MPI master branch via MTT (iterate on any further bug fixes)
• Once clean in MTT, then cherry-pick PR into PMIx v2.x branch
• Roll a v2.0rc1 release
• Test the v2.0.rc1 in Open MPI master with the external PMIx component (opal/mca/pmix/ext2x)
  • Consider making a v2.0 internal PMIx component - maybe just on a side branch
• Test Open MPI master branch via MTT (iterate on any further bug fixes)
• Once stable then start working on a new internal v2.0 PMIx component on the Open MPI v2.x branch for the Open MPI v2.1 release
• Test Open MPI v2.x branch via MTT (iterate on any further bug fixes)

[jjhursey]

I've opened PR #2286 to bring PMIx v1.2 into Open MPI v2.x. Once merged, that PR will fix this issue.

[jjhursey]

PR #2286 was merged in, but we are waiting for PMIx v1.2.1 release which includes some scalability improvements. See Issue #2744 for more details (maybe close this as a dup?)

[jsquyres]

This is now done.