fix: https://github.com/NVIDIA/Model-Optimizer/issues/981

[ChenhanYu]

What does this PR do?

Type of change: ? Bug fix

An issue is reported in #981 where str(v) on some TransformerConfig fields will raise TypeError. The fix is to catch this error and do repr(type(v)) instead.

Usage

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Testing

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Additional Information

Summary by CodeRabbit

• Bug Fixes
  • Improved checkpoint loading stability by handling unusual configuration values more gracefully; such values no longer cause failures and are skipped with a warning instead.
  • Reduced risk of crashes during configuration processing when encountering non-standard or unsupported objects.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between 014c1a0 and 6e567e6.

📒 Files selected for processing (1)

• modelopt/torch/opt/plugins/mcore_dist_checkpointing.py

🚧 Files skipped from review as they are similar to previous changes (1)

• modelopt/torch/opt/plugins/mcore_dist_checkpointing.py

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📝 Walkthrough

Walkthrough

The _parse_transformer_config function in the Megatron-Core distributed checkpointing plugin now attempts str(v) inside a try/except that catches AttributeError and TypeError; if conversion raises, a warning is logged and that config key is left out of the stringified mapping.

Changes

Cohort / File(s)	Summary
Dist checkpoint parsing modelopt/torch/opt/plugins/mcore_dist_checkpointing.py	In _parse_transformer_config wrap str(v) in try/except catching AttributeError/TypeError; on exception logs a warning and skips converting that key instead of crashing.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 2 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Title check	⚠️ Warning	The PR title is a bare issue URL with no descriptive summary of the actual change, making it unclear to reviewers scanning history what the fix addresses.	Replace the issue URL with a clear, concise title describing the fix, such as: 'fix: Handle TypeError when converting TransformerConfig fields to string' or 'fix: Add try-except for str(v) conversion in _parse_transformer_config'
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Security Anti-Patterns	✅ Passed	No security anti-patterns detected. The change adds try/except error handling for type conversion in _parse_transformer_config, which is a defensive programming improvement with no security risks.

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• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch chenhany/fix_issue_981

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@modelopt/torch/opt/plugins/mcore_dist_checkpointing.py`:
- Around line 151-157: Remove the stray pre-try conversion so the fallback runs:
delete the initial `config[k] = str(v)` before the try block and leave the
try/except that attempts `str(v)` and on `AttributeError`/`TypeError` sets
`config[k] = repr(type(v))`; update the block around `config`, `k`, and `v` in
`mcore_dist_checkpointing.py` so only the `try: config[k] = str(v)` / `except
(AttributeError, TypeError): config[k] = repr(type(v))` sequence exists.

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Configuration used: Path: .coderabbit.yaml

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Run ID: 782435f7-d420-4661-8805-3bf2d93883dd

📥 Commits

Reviewing files that changed from the base of the PR and between 31f0783 and 6ab53db.

📒 Files selected for processing (1)

• modelopt/torch/opt/plugins/mcore_dist_checkpointing.py

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.12%. Comparing base (edde087) to head (6e567e6).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #983      +/-   ##
==========================================
+ Coverage   72.10%   72.12%   +0.02%     
==========================================
  Files         209      209              
  Lines       23629    23628       -1     
==========================================
+ Hits        17037    17042       +5     
+ Misses       6592     6586       -6     

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[kevalmorabia97]

Did you mean to add something to the empty {}?