[slurm-users] PMIx and Slurm

[Philip Kovacs]

This issue is that pmi 2.0+ provides a "backward compatibility" feature, enabled by default, which installsboth libpmi.so and libpmi2.so in addition to libpmix.so.  The route with the least friction for you would probablybe to uninstall pmix, then install slurm normally, letting it install its libpmi and libpmi2.  Next configure and compilea custom pmix with that backward feature _disabled_, so it only installs libpmix.so.   Slurm will "see" the pmix libraryafter you install it and load it via its plugin when you use --mpi=pmix.   Again, just use the Slurm pmi and pmi2 and install pmix separately with the backward compatible option disabled.
There is a packaging issue there in which two packages are trying to install their own versions of the same files.  That should be brought to attention of the packages.  Meantime you can work around it.
For PMIX:
./configure --disable-pmi-backward-compatibility // ... etc ...
   

 On Tuesday, November 28, 2017 4:44 PM, Artem Polyakov <artpol84 at gmail.com> wrote:
 

 Hello, Paul
Please see below.

2017-11-28 13:13 GMT-08:00 Paul Edmon <pedmon at cfa.harvard.edu>:

So in an effort to future proof ourselves we are trying to build Slurm against PMIx, but when I tried to do so I got the following:

Transaction check error:
  file /usr/lib64/libpmi.so from install of slurm-17.02.9-1fasrc02.el7.cen tos.x86_64 conflicts with file from package pmix-2.0.2-1.el7.centos.x86_64
  file /usr/lib64/libpmi2.so from install of slurm-17.02.9-1fasrc02.el7.cen tos.x86_64 conflicts with file from package pmix-2.0.2-1.el7.centos.x86_64

This is with compiling Slurm with the --with-pmix=/usr option.  A few things:

1. I'm surprised when I tell it to use PMIx it still builds its own versions of libpmi and pmi2 given that PMIx handles that now.


PMIx is a plugin and from multiple perspectives it makes sense to keep the other versions available (i.e. backward compat or perf comparison)  

2. Does this mean I have to install PMIx in a nondefault location?  If so how does that work with user build codes?  I'd rather not have multiple versions of PMI around for people to build against.

When we introduced PMIx it was in the beta stage and we didn't want to build against it by default. Now it probably makes sense to assume --with-pmix by default.I'm also thinking that we might need to solve it at the packagers level by distributing "slurm-pmix" package that is builded and depends on the pmix package that is currently shipped with particular Linux distro. 

3.  What is the right way of building PMIx and Slurm such that they interoperate properly?

As for now it is better to have a PMIx installed in the well-known location. And then build your MPIs or other apps against this PMIx installation.Starting (I think) from PMIx v2.1 we will have a cross-version support that will give some flexibility about what installation to use with application, 

Suffice it to say little to no documentation exists on how to properly this, so any guidance would be much appreciated.
Indeed we have some problems with the documentation as PMIx technology is relatively new. Hopefully we can fix this in near future.Being the original developer of the PMIx plugin I'll be happy to answer any questions and help to resolve the issues.

 


-Paul Edmon-






-- 
С Уважением, Поляков Артем Юрьевич
Best regards, Artem Y. Polyakov

   
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