mpi4py: Regression in MPI_Alltoallv() using MPI_INPLACE

[dalcinl]

Thank you for taking the time to submit an issue!

Background information

What version of Open MPI are you using? (e.g., v3.0.5, v4.0.2, git branch name and hash, etc.)

git master

Describe how Open MPI was installed (e.g., from a source/distribution tarball, from a git clone, from an operating system distribution package, etc.)

See logs.

If you are building/installing from a git clone, please copy-n-paste the output from git submodule status.

Fresh clone in a GitHub Actions runner. See logs.

Please describe the system on which you are running

• Operating system/version: Linux
• Computer hardware: x86_64
• Network type:

---

Details of the problem

See logs: https://github.com/mpi4py/mpi4py-testing/runs/3847097248?check_suite_focus=true

This same test was working 6 days ago.

[awlauria]

#9330

Could possibly indicate the regression on master. Is there a link to the source?

[jsquyres]

Note that the ALLTOALLV change was backported to all the current release branches.

[awlauria]

10/11 RM call - we think this is a master problem only. #9330 is currently master only.

[awlauria]

Unfortunately, I was wrong. This was merged into v5.0.x here: #9493

It will need to be fixed prior to a v5.0.0 release.