Create MPI_INFO_ENV before MPI_INIT

[wesbland]

Problem

As part of a number of proposals (improving error handling - #102, sessions - #103, and tools) it is helpful to have access to an MPI_INFO_ENV-like object before MPI_INIT is called. The ability to manipulate MPI_INFO objects before initialization is being proposed as part of Sessions (#103), but the ability to construct such an object is not part of that proposal.

Proposal

This proposes a new function called MPI_INFO_ENV_CREATE_ARGV which would allow the user to pass in the argc and argv parameters and receive an MPI_INFO_ENV-like object back, which could be used for all of the same functionality as MPI_INFO_ENV.

Changes to the Text

The new function MPI_INFO_ENV_CREATE_ARV is added and described.

Impact on Implementations

Implementations will need to implement the new function, which should hopefully be the same code as is currently used in MPI_INIT. It's possible that if the implementation relies on the input parameters to MPI_INIT for argc and argv and doesn't currently have another way of getting those values, the output info object here might not be the same as MPI_INFO_ENV.

Impact on Users

Users not using this function will not be impacted. Users who want to use this function for the purposes mentioned above will be able to access the MPI_INFO_ENV-like object before initialization.

References

The pull request is available at https://github.com/mpi-forum/mpi-standard/pull/126

[wesbland]

PDF including no-no changes made on 2019-09-06: mpi40-report-get_info_env.pdf

[wesbland]

PDF including no-no changes for 2019-09-07: mpi40-report-get_info_env.pdf

[ahori]

I wonder why you did not mention that this routine can be called before calling MPI_INIT. Isn't this the point of this routine?

[wesbland]

That's a good point. I'll fix that before the reading.

mpi40-report-get_info_env.pdf

[wesbland]

This is the PDF to be read at the December 2019 meeting.

[wesbland]

This commit, https://github.com/mpi-forum/mpi-standard/pull/126/commits/67b597098d3880d4fc282badcae0d051be5af72a, will be read as a no-no item at the December 2019 meeting.

[wesbland]

This passed the no-no vote in Albuquerque, New Mexico on 2019-12-12.

[wesbland]

This proposal passed a first vote at the February 2020 meeting:

Yes - 23
No - 0
Abstain - 1

[wesbland]

This passed a second vote on 2020-06-30.

https://www.mpi-forum.org/meetings/2020/06/votes