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Simplify structured outputs logic across vLLM versions in scripts/vllm_serve#5273

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albertvillanova merged 8 commits into
huggingface:mainfrom
albertvillanova:fu-5215
Mar 16, 2026
Merged

Simplify structured outputs logic across vLLM versions in scripts/vllm_serve#5273
albertvillanova merged 8 commits into
huggingface:mainfrom
albertvillanova:fu-5215

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@albertvillanova albertvillanova commented Mar 12, 2026 •
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Simplify structured outputs logic across vLLM versions in scripts/vllm_serve.

This PR refactors the handling of structured output parameters for vLLM generation to improve compatibility across different vLLM versions and simplify the logic for setting structured output options. The main changes focus on unifying the way structured output parameters are imported and used, and on reducing code duplication related to vLLM version checks.

Follow-up to:

Note

Medium Risk
Moderate risk because it changes how structured-output kwargs are mapped/overridden across vLLM versions, which can alter runtime generation behavior if callers pass generation_kwargs or regex constraints incorrectly.

Overview
Simplifies structured outputs handling in trl/scripts/vllm_serve.py by unifying the vLLM version split: older vLLM uses GuidedDecodingParams (aliased to StructuredOutputsParams) with the guided_decoding key, while newer versions use StructuredOutputsParams with the structured_outputs key.

Both /generate and /chat now share the same post-processing rules: structured_outputs_regex consistently overrides any existing structured-output entry (with a warning), and dict-based structured-output kwargs are coerced into a params object before constructing SamplingParams.

Written by Cursor Bugbot for commit 6989e16. This will update automatically on new commits. Configure here.

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HuggingFaceDocBuilderDev commented Mar 12, 2026

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The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

qgallouedec
qgallouedec reviewed Mar 13, 2026
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thanks!

@albertvillanova albertvillanova merged commit 5fceaa7 into huggingface:main Mar 16, 2026
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qgallouedec added a commit that referenced this pull request Mar 18, 2026
@qgallouedec
Squashed commit of the following:
56cff26 
commit 52cd0cc
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Tue Mar 17 15:31:26 2026 +0100

    Fix UNEXPECTED lm_head.weight warning when loading a CausalLM as a reward model (#5295)

commit 7b42fc4
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Tue Mar 17 15:29:11 2026 +0100

    Prevent corruption of DPO VLM training if "keep_end" truncation_mode (#5286)

commit 3acb8e8
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Tue Mar 17 15:27:10 2026 +0100

    Support max_length in DPO VLM training (#5284)

commit ee339a0
Author: Carlos Miguel Patiño <carlos.patino@huggingface.co>
Date:   Tue Mar 17 14:01:44 2026 +0100

    [GKD] Buffer Implementation for Distillation Trainer (#5137)

    Co-authored-by: lewtun <lewis.c.tunstall@gmail.com>

commit d46131f
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Mon Mar 16 15:27:19 2026 +0100

    Remove custom get_train/eval_dataloader from OnlineDPO (#5291)

commit 85cf8f4
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Mon Mar 16 15:24:24 2026 +0100

    Remove TrainingArguments import from experimental trainers (#5290)

commit 91e3da0
Author: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
Date:   Mon Mar 16 07:19:51 2026 -0600

    Fix `accuracy_reward` crash when called from non-main thread (#5281)

commit 4996631
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Mon Mar 16 07:44:28 2026 +0100

    Fix support for model_init_kwargs in MiniLLM when passed as CLI JSON string (#5274)

commit 5fceaa7
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Mon Mar 16 07:43:34 2026 +0100

    Simplify structured outputs logic across vLLM versions in scripts/vllm_serve (#5273)

commit 406d406
Author: casinca <47400729+casinca@users.noreply.github.com>
Date:   Sat Mar 14 04:12:49 2026 +0100

    feat(`grpo_trainer.py`): Variational Sequence-Level Soft Policy Optimization (VESPO) (#5199)

commit d0ac7ef
Author: LeonEricsson <70749762+LeonEricsson@users.noreply.github.com>
Date:   Sat Mar 14 02:53:33 2026 +0100

    Allow nullable logprobs in vLLM serve responses  (#5203)

    Co-authored-by: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
    Co-authored-by: Quentin Gallouédec <gallouedec.quentin@gmail.com>

commit c0eabc4
Author: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
Date:   Fri Mar 13 18:19:15 2026 -0600

    Change default `vllm_mode` to `"colocate"` and add v0→v1 migration guide (#5255)

    Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

commit 6c0fccd
Author: Mario Šaško <mariosasko777@gmail.com>
Date:   Sat Mar 14 00:19:38 2026 +0100

    35% faster packing + rename `bfd-requeue` to `bfd_split` (#5189)

    Co-authored-by: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
    Co-authored-by: Quentin Gallouédec <gallouedec.quentin@gmail.com>
qgallouedec added a commit that referenced this pull request Mar 18, 2026
@qgallouedec
Squashed commit of the following:
14dbaf1 
commit 3972d66
Author: Quentin Lhoest <42851186+lhoestq@users.noreply.github.com>
Date:   Wed Mar 18 22:26:44 2026 +0100

    Suggest the `Json()` type for tool calling dataset format (#5307)

    Co-authored-by: Quentin Gallouédec <gallouedec.quentin@gmail.com>
    Co-authored-by: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>

commit 5c6e915
Author: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
Date:   Wed Mar 18 14:55:19 2026 -0600

    Update `RewardFunc` type annotation to allow `None`values in reward list (#5297)

commit ee96845
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Wed Mar 18 17:03:54 2026 +0100

    Fix DPOTrainer collators to truncate sequences before padding (#5305)

commit 435c2ae
Author: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
Date:   Wed Mar 18 08:09:42 2026 -0600

    Add guidance to avoid `hasattr` and `getattr` with defaults in `AGENTS.md` (#5294)

commit 26ce6a3
Author: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
Date:   Wed Mar 18 00:44:12 2026 -0600

    Apply docstyle (#5296)

commit 52cd0cc
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Tue Mar 17 15:31:26 2026 +0100

    Fix UNEXPECTED lm_head.weight warning when loading a CausalLM as a reward model (#5295)

commit 7b42fc4
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Tue Mar 17 15:29:11 2026 +0100

    Prevent corruption of DPO VLM training if "keep_end" truncation_mode (#5286)

commit 3acb8e8
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Tue Mar 17 15:27:10 2026 +0100

    Support max_length in DPO VLM training (#5284)

commit ee339a0
Author: Carlos Miguel Patiño <carlos.patino@huggingface.co>
Date:   Tue Mar 17 14:01:44 2026 +0100

    [GKD] Buffer Implementation for Distillation Trainer (#5137)

    Co-authored-by: lewtun <lewis.c.tunstall@gmail.com>

commit d46131f
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Mon Mar 16 15:27:19 2026 +0100

    Remove custom get_train/eval_dataloader from OnlineDPO (#5291)

commit 85cf8f4
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Mon Mar 16 15:24:24 2026 +0100

    Remove TrainingArguments import from experimental trainers (#5290)

commit 91e3da0
Author: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
Date:   Mon Mar 16 07:19:51 2026 -0600

    Fix `accuracy_reward` crash when called from non-main thread (#5281)

commit 4996631
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Mon Mar 16 07:44:28 2026 +0100

    Fix support for model_init_kwargs in MiniLLM when passed as CLI JSON string (#5274)

commit 5fceaa7
Author: Albert Villanova del Moral <8515462+albertvillanova@users.noreply.github.com>
Date:   Mon Mar 16 07:43:34 2026 +0100

    Simplify structured outputs logic across vLLM versions in scripts/vllm_serve (#5273)

commit 406d406
Author: casinca <47400729+casinca@users.noreply.github.com>
Date:   Sat Mar 14 04:12:49 2026 +0100

    feat(`grpo_trainer.py`): Variational Sequence-Level Soft Policy Optimization (VESPO) (#5199)

commit d0ac7ef
Author: LeonEricsson <70749762+LeonEricsson@users.noreply.github.com>
Date:   Sat Mar 14 02:53:33 2026 +0100

    Allow nullable logprobs in vLLM serve responses  (#5203)

    Co-authored-by: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
    Co-authored-by: Quentin Gallouédec <gallouedec.quentin@gmail.com>

commit c0eabc4
Author: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
Date:   Fri Mar 13 18:19:15 2026 -0600

    Change default `vllm_mode` to `"colocate"` and add v0→v1 migration guide (#5255)

    Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

commit 6c0fccd
Author: Mario Šaško <mariosasko777@gmail.com>
Date:   Sat Mar 14 00:19:38 2026 +0100

    35% faster packing + rename `bfd-requeue` to `bfd_split` (#5189)

    Co-authored-by: Quentin Gallouédec <45557362+qgallouedec@users.noreply.github.com>
    Co-authored-by: Quentin Gallouédec <gallouedec.quentin@gmail.com>
@albertvillanova albertvillanova mentioned this pull request Apr 1, 2026
Merged
songhappy pushed a commit to songhappy/trl that referenced this pull request Apr 20, 2026
@albertvillanova
Simplify structured outputs logic across vLLM versions in scripts/vll…
5ed36d5 
…m_serve (huggingface#5273)
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