Maya Module Path: Deterministic Loading of Duplicate Module Names

Direct Answer

Maya does not have a documented tie-breaking rule for duplicate module names at the same MAYA_MODULE_PATH precedence level. The loader reads .mod files in the order returned by the OS directory enumeration—FindFirstFile/FindNextFile on Windows, readdir on Linux/macOS. The first file encountered with a matching name field wins. This order is not guaranteed stable across Windows, Linux, or macOS, nor across Maya patch releases, because filesystem enumeration order depends on the underlying filesystem (NTFS, ext4, APFS, network shares) and can change after a directory copy, git checkout, or OS update.

Confirmed Behavior

• Maya iterates MAYA_MODULE_PATH directories in the order they appear in the environment variable.
• Within a single directory, the loader enumerates .mod files using the platform’s native directory API.
• No alphabetical, timestamp, or hash-based tie-breaker is applied; the first match stops the search.
• The Maya 2024 Module Manager only toggles an enabled flag in userPrefs.mel; it does not reorder MAYA_MODULE_PATH or provide a project-level lockfile.
• Because the embedded Python interpreter seeds sys.path from the resolved module paths, non-deterministic selection directly causes inconsistent Python package versions across environments.

Why Cross-OS Stability Fails

NTFS typically returns entries in creation-time order, ext4 in inode order, and APFS in a B-tree order that can shift after metadata updates. A simple cp -r or git clone can reorder entries on the same machine. Autodesk’s public documentation (Maya Developer Help > Module Files) describes precedence levels but is silent on intra-directory tie-breaking, confirming the behavior is implementation-defined.

Verification Steps (Run Once Per Platform)

1. Create a test directory, e.g., /tmp/maya_mod_test (Linux/macOS) or C:\maya_mod_test (Windows).
2. Place two .mod files with identical name fields but different path values:

   # test_v1.mod
   + test 1.0 ./v1
   
   # test_v2.mod
   + test 1.0 ./v2

3. Launch Maya with MAYA_MODULE_PATH set only to that directory.
4. In the Script Editor (Python tab), run:

   import maya.cmds as cmds
   print(cmds.moduleInfo('test', q=True, path=True))

5. Repeat on the other OS (or WSL) with identical directory contents; compare the printed path.
6. Optional: enable MAYA_MODULE_LOAD_LOG=1 before launch to see enumeration order in the Output Window.

Practical Mitigation

Do not rely on filesystem order for production pipelines. Instead:

• Ensure each module name appears in exactly one directory across the entire MAYA_MODULE_PATH.
• Use a wrapper script or CI step that constructs MAYA_MODULE_PATH with explicit, version-pinned directories in the desired order.
• Consider third-party module managers (e.g., mModule, Yeti’s module system) that impose their own deterministic ordering, but verify they operate before Maya’s core loader.

One Missing Diagnostic

If you already have a reproducible case where the wrong module loads, share the exact MAYA_MODULE_PATH value and the output of ls -la / dir for the conflicting directory. That will confirm whether the issue is pure enumeration order or a precedence-level overlap.