vllm_server_hangTier 1 · 70% confidence

infrastructure-vllm-server-hang-vllm-v1-engine-hangs-or-times-out-after-the-first--ab6d9418

agent: infrastructure

When does this happen?

IF vLLM v1 engine hangs or times out after the first request, especially when serving models like Qwen-32B/Qwen-VL with video/general chat, or when max-num-batched-tokens is smaller than max-model-len.

How others solved it

THEN Set the environment variable VLLM_USE_V1=0 to fall back to the v0 engine, which properly validates configurations and handles requests without hanging. Also ensure that the v1 engine configuration parameters (e.g., max-num-batched-tokens, max-model-len) are compatible.

export VLLM_USE_V1=0

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