Files
Model-Optimizer/examples/dataset/utils.py
T
Chenhan D. Yu 0246041b01 feat(speculative): add vLLM data synthesis pipeline and Nemotron dataset preparation scripts (#1176)
### What does this PR do?

Type of change: New feature, new example, bug fix

Adds a vLLM-based synthetic data generation pipeline for speculative
decoding draft model training, along with dataset preparation scripts
for NVIDIA's Nemotron Post-Training dataset collections.

**Data synthesis pipeline** (`tools/launcher/common/vllm/query.sh` +
`common/query.py`):
- Launch a vLLM server and run multi-turn inference to synthesize
training data from input conversation skeletons
- Fork-safe OpenAI client: reinitializes HTTP connection pool after
`datasets.map()` forks worker processes, preventing 400 errors from
corrupted connections
- Clear Docker `ENTRYPOINT` so vLLM containers (which default to `vllm
serve`) work correctly under NeMo Run's executor
- `--max-tokens` argument to bound generation length
- Local file loading support (`--data /path/to/file.jsonl`)
- Re-raise connection errors so `datasets.map()` halts the shard instead
of silently producing empty rows
- Map `developer` role to `system` (OpenAI format compatibility)

**Multi-turn reasoning trace handling** (`common/query.py`):
- Strip `<think>...</think>` blocks from intermediate assistant turns
before re-feeding to the model; preserve the full trace only on the
final turn

**Nemotron dataset preparation** (`examples/dataset/`):
- `make_nemotron_ptv2_dataset.py` — prepares
[nvidia/Nemotron-Post-Training-Dataset-v2](https://huggingface.co/datasets/nvidia/Nemotron-Post-Training-Dataset-v2)
(~3.3M rows generate, ~1.9M rows train)
- `make_nemotron_ptv3_dataset.py` — prepares the [Nemotron PTv3
collection](https://huggingface.co/collections/nvidia/nemotron-post-training-v3)
of 16 datasets (~3.4M rows generate, ~3.9M rows train)
- Both support `generate` mode (strips assistant turns for synthesis
input) and `train` mode (normalizes to clean OpenAI format for SFT)
- `conversation_utils.py` — shared utilities: `strip_assistant_turns`,
`normalize_messages`, `make_augment_fn`, `AugmentationSpec`
- `augmentations.yaml` — 12 language-redirect variants + style/format
hints, cycled across dataset rows
- Scripts live in `examples/dataset/` (not under
`speculative_decoding/`) to signal reusability beyond speculative
decoding

**Bug fixes**:
- `strip_assistant_turns()`: return `{"messages": []}` when no user
turns remain (system-only rows were previously passed through instead of
being filtered)
- `concatenate_datasets()`: guard against empty parts list
- SSH tunnel user precedence: explicit `user` arg now correctly
overrides `slurm_config.user`

### Usage

```bash
# Prepare PTv3 input conversations for synthesis (~3.4M rows):
python examples/dataset/make_nemotron_ptv3_dataset.py --output-dir /tmp/ptv3_gen

# Launch vLLM server + synthesize responses:
bash tools/launcher/common/vllm/query.sh \
    --model /path/to/model \
    --tensor-parallel-size 4 \
    -- \
    --data /tmp/ptv3_gen/default.jsonl \
    --save /tmp/ptv3_responses \
    --num-shards 10 --num-proc 4 --max-tokens 4096

# Prepare PTv2 for direct SFT training (~1.9M rows):
python examples/dataset/make_nemotron_ptv2_dataset.py --mode train --output-dir /tmp/ptv2_train
```

### Testing

Tested end-to-end on an NVIDIA GB10 node (119 GiB GPU memory) with
`vllm/vllm-openai:qwen3_5-cu130` container and `Qwen/Qwen3.5-4B`:
- vLLM server starts correctly with cleared Docker entrypoint
- `datasets.map(num_proc=4)` runs without connection errors (fork-safe
client)
- Multi-turn synthesis produces correct assistant responses with
thinking traces handled

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

Make sure you read and follow [Contributor
guidelines](https://github.com/NVIDIA/Model-Optimizer/blob/main/CONTRIBUTING.md)
and your commits are signed (`git commit -s -S`).

Make sure you read and follow the [Security Best
Practices](https://github.com/NVIDIA/Model-Optimizer/blob/main/SECURITY.md#security-coding-practices-for-contributors)
(e.g. avoiding hardcoded `trust_remote_code=True`, `torch.load(...,
weights_only=False)`, `pickle`, etc.).

- 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 (data synthesis scripts;
tested manually)
- Did you update
[Changelog](https://github.com/NVIDIA/Model-Optimizer/blob/main/CHANGELOG.rst)?:
N/A


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

## Summary by CodeRabbit

* **New Features**
* Added dataset generation and augmentation capabilities for Nemotron
post-training datasets (v2 and v3)
* Enhanced query functionality with thinking-block filtering and
improved client management for robust parallel processing
* Added support for local dataset file paths alongside HuggingFace Hub
datasets

* **Bug Fixes**
* Fixed SLURM executor user resolution and Docker container entrypoint
configuration
* Improved error handling for connection failures during dataset
synthesis

* **Documentation**
* Updated dataset preparation guide with new generation modes and
augmentation configuration details

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Signed-off-by: Chenhan D. Yu <5185878+ChenhanYu@users.noreply.github.com>
Signed-off-by: Chenhan Yu <chenhany@nvidia.com>
2026-04-08 05:22:11 +00:00

42 lines
1.6 KiB
Python

# SPDX-FileCopyrightText: Copyright (c) 2023-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Utility functions."""
import hashlib
import json
from pathlib import Path
import aiohttp
async def download_file(url: str, destination: Path) -> None:
"""Download a file from a URL to a specified destination."""
destination.parent.mkdir(parents=True, exist_ok=True)
async with aiohttp.ClientSession() as session, session.get(url) as response:
if response.status != 200:
msg = f"Failed to download {url}: {response.status}"
raise RuntimeError(msg)
content = await response.read()
destination.write_bytes(content)
print(f"Downloaded {url} to {destination}")
def id_for_conversation(conversation: list) -> str:
"""Generate a unique ID for a conversation based on its content."""
json_str = json.dumps(conversation, sort_keys=True, separators=(",", ":"), ensure_ascii=False)
json_bytes = json_str.encode("utf-8")
return hashlib.sha256(json_bytes).hexdigest()