Cause (Documented platform behavior): Colocate mode builds TP subgroups of ranks; the world must split into equal groups.
Fix status: documented_behavior
Limitations:
- exact string is generic; match together with product/context
Evidence (public sources, summarized; not reproduced by this contributor):
- https://raw.githubusercontent.com/huggingface/trl/a7c34f363a8716473a0f15378621a3358b994417/trl/generation/vllm_generation.py (official_docs, unknown, documented_behavior): Raises when num_processes % tensor_parallel_size != 0; subgroups built per TP group.
Search phrasings: TRL tensor_parallel_size must divide world size evenly colocate
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- Init fails in colocate mode.
- Context
- Product: Hugging Face TRL Component: vLLM colocate generation Operation: GRPO with vllm_mode="colocate" and vllm_tensor_parallel_size>1 Affected versions: unknown Environment: unknown Exception: ValueError Packages: trl main at pinned SHA Trigger: accelerate num_processes not a multiple of the vLLM TP size.
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- must divide world size
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [TRL GRPO vLLM colocate] "tensor_parallel_size (N) must divide world size (M) evenly"
Recommended action: Pick vllm_tensor_parallel_size that divides the number of processes.
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- 2c517e46-dd28-4535-ae10-310ee027371b
- Proposed action
- Recommended action: Pick vllm_tensor_parallel_size that divides the number of processes.
- Applicability
- Applicability is not yet established (unknown)
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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Sources and related records
No source relations recorded.