Handle Debugging Interface

[mahermanns]

Problem

There is currently no interface for debuggers to introspect handle information portably, which makes it harder for debuggers to provide in-depth information across multiple implementation.

Proposal

Expand on the ideas of the message queue interface and the OpenMP debugging interface to provide debugging information portably across different implementations.

Changes to the Text

tbd.

Impact on Implementations

Implementation of a debugging library that implements the proposed API and communicates the data with the MPI library itself.

Impact on Users

Introspection of handle information across different MPI implementations with a single API to support.

References and Pull Requests

API Discussion on Tools WG Wiki: https://github.com/mpiwg-tools/tools-issues/wiki/Handle-Debugging

[mahermanns]

As discussed in the tools working group meeting:

• As this interface is significantly separate from MPI_T (the tools information interface), this should get its own namespace
  • They will compiled into a different binary/library (you can link against this without linking against the rest of the MPI library)
• As this interface is primarily for debugging tools (or tools acting like debuggers), we want to call it "Debugging Interface"
• To keep similarities with OMPD and MPI_T, the prefix MPI_D_ should be used for API functions to have them under the existing "prefix protection clause"
• Still need to find out to mimic the definition of the callbacks and types
• MPI_D_dll_locations should be part of the 'MPI capable program' (the MPI
  process, not the starter programm)
• MPI Forum should host a header file and that should be the authoritative
  version. MPI library vendors don't have to package it.

[mahermanns]

Tools WG meeting 2025-01-27:

• How to properly handle the pointer * notation for the debugging handles
• How to typeset the enums/constants
• How to typeset multi-dimensional arrays (see topology query using int **)
• How to typeset structs