Hi Edric,

It looks like we may have unintentionally inverted the logic on that function return value. I’ll submit a PR to fix. Thanks for bringing it to our attention.

Ken

From: Edric Ellis via discuss <discuss@mpich.org>
Reply-To: "discuss@mpich.org" <discuss@mpich.org>
Date: Monday, April 22, 2024 at 9:44 AM
To: "discuss@mpich.org" <discuss@mpich.org>
Cc: Edric Ellis <eellis@mathworks.com>
Subject: [mpich-discuss] Environment variable forwarding using Hydra and "-launcher ssh"

We’re in the process of moving from mpich-3. x to mpich-4. 1. 2. We’ve run into some odd behaviour on SLURM related to environment variable forwarding by mpiexec. It looks like mpiexec now propagates only SLURM_* environment variables,

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We’re in the process of moving from mpich-3.x to mpich-4.1.2. We’ve run into some odd behaviour on SLURM related to environment variable forwarding by mpiexec. It looks like mpiexec now propagates only SLURM_* environment variables, instead of filtering them out (or intending to). Consider something like this:

$ mpiexec -launcher slurm printenv HOME SLURM_JOBID

Using mpich-3.x, the HOME variable gets forward. Using mpich-4.1.2, it does not. I believe that mpich-3.x intends to filter out SLURM_JOBID, but the value still seems to be present, maybe srun forwards that. It’s the fact that HOME doesn’t get through using mpich-4.1.2 that is causing us problems.

Running mpich-

Here’s what I think is the relevant change for SLURM: https://github.com/pmodels/mpich/commit/95ba4ddc7efc7ddc7f25ed41480ee35248184680 . Am I reading that correctly?

The doc here https://github.com/pmodels/mpich/blob/main/doc/wiki/how_to/Using_the_Hydra_Process_Manager.md#environment-settings states that SLURM_ things should be filtered out, but that doesn’t appear to be happening?

For reference, here’s what mpich-4.1.2 “mpiexec -verbose -launcher slurm” prints:

mpiexec options:                                                                                                                                                                                                                                                                                            

----------------                                                                                                                                                                                                                                                                                            

  Base path: /path/to/mpich-4.1.2

  Launcher: slurm                                                                                                                                                                                                                                                                                           

  Debug level: 1                                                                                                                                                                                                                                                                                            

  Enable X: -1                                                                                                                                                                                                                                                                                              

  Global environment:                                                                                                                                                                                                                                                                                       

  -------------------                                                                                                                                                                                                                                                                                       

    SLURM_JOBID=102437                                                                                                                                                                                                                                                                                      

    SLURM_JOB_USER=eellis                                                                                                                                                                                                                                                                                   

    SLURM_JOB_QOS=normal                                                                                                                                                                                                                                                                                    

    SLURM_JOB_NUM_NODES=2                                                                                                                                                                                                                                                                                   

    SLURM_TASKS_PER_NODE=1(x2)                                                                                                                                                                                                                                                                              

    SLURM_TOPOLOGY_ADDR_PATTERN=node

    … many more SLURM_*

And here’s what mpich-3.x prints:

mpiexec options:                                                                                                                                                                                                                                                                                            

----------------                                                                                                                                                                                                                                                                                            

  Base path: /path/to/mpich-3.x

  Launcher: slurm                                                                                                                                                                                                                                                                                           

  Debug level: 1                                                                                                                                                                                                                                                                                            

  Enable X: -1                                                                                                                                                                                                                                                                                              

  Global environment:                                                                                                                                                                                                                                                                                       

  -------------------                                                                                                                                                                                                                                                                                       

    ALTERNATE_EDITOR=emacs                                                                                                                                                                                                                                                                                  

    MAIL=/var/mail/eellis                                                                                                                                                                                                                                                                                   

    USER=eellis                                                                                                                                                                                                                                                                                             

    SLURM_JOB_USER=eellis                                                                                                                                                                                                                                                                                   

    l=/local/eellis                                                                                                                                                                                                                                                                                         

    XDG_SESSION_TYPE=unspecified                                                                                                                                                                                                                                                                            

    SLURM_JOB_QOS=normal

    … no SLURM_JOBID                                                                                                                                                                                                                                                                                    

Cheers,

Edric.