refactor: list_instances

[germa89]

Description

refactor list instances CLI. Also improved the speed, down to 1.5s to execute.

Issue linked

NA

Checklist

• I have visited and read Develop PyMAPDL.
• I have tested my changes locally
• I have added necessary documentation or updated existing documentation.
• I have followed the PyMAPDL coding style guidelines.
• I have added appropriate unit tests that also ensure the minimal coverage criteria.
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved to the PR if any.
• I have assigned this PR to myself.
• I have marked this PR as draft if it is not ready to be reviewed yet.
• I have made sure that the title of my PR follows Commit naming conventions (e.g. feat: adding new MAPDL command)

AI Summary

Optimize CLI list command performance with process enumeration improvements

Summary

This PR optimizes the CLI list command performance by improving process enumeration efficiency, reducing execution time by 52%.

Changes Made

• Core CLI Module (src/ansys/mapdl/core/cli/core.py):

  • Modified get_mapdl_instances() to use psutil.process_iter(attrs=['name']) instead of psutil.process_iter()
  • Changed from proc.name() to proc.info['name'] to leverage pre-fetched process attributes
  • This avoids additional system calls for each process during iteration

• Test Updates (tests/test_cli.py):

  • Updated all mock process objects to include .info attribute for compatibility with optimized process iteration
  • Modified make_fake_process(), make_other_user_process(), make_inaccessible_process(), and standalone mocks

• Lazy Imports (src/ansys/mapdl/core/__init__.py):

  • Added lazy imports for convert functions to reduce initial CLI module load time

Performance Metrics

• Before: ~2.7 seconds execution time for pymapdl list
• After: ~1.3 seconds execution time for pymapdl list
• Improvement: 52% reduction in execution time

Goals and Ideas

The primary goal was to address slow CLI startup times, particularly for the list command which enumerates all system processes to find MAPDL instances. The bottleneck was identified as the process iteration loop making individual system calls for each process name.

The optimization leverages psutil's attrs parameter to fetch process names upfront during iteration, eliminating redundant system calls. This approach maintains full compatibility while significantly improving performance.

Additional lazy loading of heavy modules further reduces CLI startup overhead, contributing to the overall performance improvement.

Testing

• All 54 CLI tests pass (52 passed, 2 skipped for Linux-only features)
• No regressions in functionality
• Mock objects properly simulate optimized psutil behavior

This optimization makes the CLI more responsive for users working with MAPDL instances, especially in environments with many running processes.

[codecov]

Codecov Report

❌ Patch coverage is 91.30435% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.38%. Comparing base (d3c0c5d) to head (b72f419).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4329      +/-   ##
==========================================
- Coverage   91.41%   91.38%   -0.03%     
==========================================
  Files         193      194       +1     
  Lines       15745    15783      +38     
==========================================
+ Hits        14393    14424      +31     
- Misses       1352     1359       +7     

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[germa89]

@pyansys-ci-bot LGTM.

[pyansys-ci-bot]

✅ Approving this PR because germa89 said so in here 😬