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Keval Morabia 19e0121d0a Fix 2-GPU test_model_load_utils hang; test import and fixture cleanup (#2079)
### What does this PR do?

Type of change: Bug fix + new tests (test-suite only; changes are
confined to `tests/`)

- **Fix `test_parallel_load_and_export` hang on 2 GPUs.** The temp paths
were built from `os.getpid()` *inside* the workers, so each rank got a
different `ckpt_dir`; rank 1 then took `_resolve_checkpoint_dir`'s Hub
branch and blocked on an extra barrier while rank 0 ran the loader's
broadcasts. The checkpoint is now built once in the parent under
`tmp_path` and passed in, so all ranks agree on the path.
- **Imports moved to module top** across `tests/gpu*` and
`tests/examples`; function-local imports kept only where guarded
(`importorskip`/`try`), where the import *is* the test (JIT compile), or
where it must follow `sys.path` setup.
- **Reuse `_test_utils` instead of local copies:** added
`get_tiny_mixtral`; deduped `assert_nodes_are_quantized` (5 copies), the
accelerate-offload/layerwise config helpers, `make_quant_attention`,
`get_dflash_config`, the NVFP4 amax assertions, and 3 copies of the
`tiny_wan22_path` fixture.
- **Shared model-dir fixtures assert they were not modified**
(`assert_unmodified_tree`): a file manifest is compared on teardown, so
a test that writes into a session-scoped fixture directory fails instead
of silently changing what later tests see.
- **Dropped dependency guards the CI env already guarantees**
(diffusers, tensorrt_llm in `gpu_trtllm`, transformer_engine in
`gpu_megatron`, transformers in examples) so a missing dep fails loudly
instead of skipping.
- **`test_heterogenous_sharded_state_dict` is skipped on Blackwell**
(sm_120), matching the existing marker and its TE/CUDA-13 rationale —
same tracking issue as #1901.

### Testing

Local, 2x RTX 6000 Ada: `tests/gpu/torch/utils/test_model_load_utils.py`
passes on 2 GPUs and on 1 GPU (previously hung on 2). Also ran the
touched files in `tests/unit` (608 passed) and `tests/gpu` (~340
passed).

### Before your PR is "*Ready for review*"

- Is this change backward compatible?: ✅
- If you copied code from any other sources or added a new PIP
dependency, did you follow guidance in `CONTRIBUTING.md`: N/A
- Did you write any new necessary tests?: N/A — test-only PR
- Did you update
[Changelog](https://github.com/NVIDIA/Model-Optimizer/blob/main/CHANGELOG.rst)?:
N/A
- Did you get Claude approval on this PR?: ❌ — not yet run


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Tests**
* Added reusable validation utilities for generated files, quantization
behavior, attention modules, model fixtures, offloading, and speculative
decoding.
* Expanded coverage for tiny Wan, Mixtral, Llama, and related model
scenarios.
* Consolidated duplicated setup and assertions across ONNX, GPU,
quantization, export, and sparsity tests.
* Improved fixture integrity checks, NVFP4 validation, and handling of
identity inputs.
* Reduced unnecessary dependency-based skips and isolated known
platform-specific flakiness.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: Keval Morabia <28916987+kevalmorabia97@users.noreply.github.com>
2026-08-05 21:00:42 +05:30
..
2025-10-28 18:03:46 +00:00