md/20251011.md

崩溃原因

• 一个请求被发送到 vLLM 服务，该请求包含了结构化输出的意图
• vLLM 在处理请求时，进入 structured_output_request.structured_output_key 的逻辑，最终调用 get_structured_output_key(sampling_params)函数。
• 该函数遍历 sampling_params 中的各种参数（如 grammar, json_schema, regex 等），但没有找到任何一个有效的结构化输出参数。
• 因此抛出异常：raise ValueError("No valid structured output parameter found")
• 这个 ValueError 在后台线程中抛出，但未被捕获，导致 EngineCore 进程（PID 2738693）崩溃
• 主 API 服务（APIServer）检测到 EngineCore 崩溃，抛出 EngineDeadError，最终整个服务终止。

解决方案一

确保请求进入vllm的时候，提供有效的结构化输出参数。例如：

{
  "prompt": "生成一个用户信息",
  "structured_output": {
    "type": "json",
    "schema": {
      "type": "object",
      "properties": {
        "name": {"type": "string"},
        "age": {"type": "integer"}
      },
      "required": ["name", "age"]
    }
  }
}

错误示例

{
  "prompt": "生成一个JSON",
  "structured_output": {}
}

{
  "prompt": "生成一个JSON",
  "json_schema": null
}

解决方案二

升级vllm的版本到最新稳定版，官方已做出大量优化和改进。

崩溃日志片段

(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710] EngineCore encountered a fatal error.
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710] Traceback (most recent call last):
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core.py", line 701, in run_engine_core
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     engine_core.run_busy_loop()
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core.py", line 728, in run_busy_loop
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     self._process_engine_step()
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core.py", line 754, in _process_engine_step
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     outputs, model_executed = self.step_fn()
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core.py", line 283, in step
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     scheduler_output = self.scheduler.schedule()
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/core/sched/scheduler.py", line 359, in schedule
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     if structured_output_req and structured_output_req.grammar:
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/request.py", line 45, in grammar
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     completed = self._check_grammar_completion()
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/request.py", line 33, in _check_grammar_completion
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     self._grammar = self._grammar.result(timeout=0.0001)
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/concurrent/futures/_base.py", line 458, in result
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     return self.__get_result()
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/concurrent/futures/_base.py", line 403, in __get_result
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     raise self._exception
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/concurrent/futures/thread.py", line 58, in run
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     result = self.fn(*self.args, **self.kwargs)
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/__init__.py", line 128, in _async_create_grammar
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     key = request.structured_output_request.structured_output_key  # type: ignore[union-attr]
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/functools.py", line 981, in __get__
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     val = self.func(instance)
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/request.py", line 58, in structured_output_key
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     return get_structured_output_key(self.sampling_params)
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/request.py", line 86, in get_structured_output_key
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710]     raise ValueError("No valid structured output parameter found")
(EngineCore_DP0 pid=2738693) ERROR 10-10 10:43:10 [core.py:710] ValueError: No valid structured output parameter found
(EngineCore_DP0 pid=2738693) Process EngineCore_DP0:
(EngineCore_DP0 pid=2738693) Traceback (most recent call last):
(APIServer pid=2738423) ERROR 10-10 10:43:10 [async_llm.py:480] AsyncLLM output_handler failed.
(APIServer pid=2738423) ERROR 10-10 10:43:10 [async_llm.py:480] Traceback (most recent call last):
(APIServer pid=2738423) ERROR 10-10 10:43:10 [async_llm.py:480]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/async_llm.py", line 439, in output_handler
(APIServer pid=2738423) ERROR 10-10 10:43:10 [async_llm.py:480]     outputs = await engine_core.get_output_async()
(APIServer pid=2738423) ERROR 10-10 10:43:10 [async_llm.py:480]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core_client.py", line 846, in get_output_async
(APIServer pid=2738423) ERROR 10-10 10:43:10 [async_llm.py:480]     raise self._format_exception(outputs) from None
(APIServer pid=2738423) ERROR 10-10 10:43:10 [async_llm.py:480] vllm.v1.engine.exceptions.EngineDeadError: EngineCore encountered an issue. See stack trace (above) for the root cause.
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/multiprocessing/process.py", line 314, in _bootstrap
(EngineCore_DP0 pid=2738693)     self.run()
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/multiprocessing/process.py", line 108, in run
(EngineCore_DP0 pid=2738693)     self._target(*self._args, **self._kwargs)
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core.py", line 712, in run_engine_core
(EngineCore_DP0 pid=2738693)     raise e
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core.py", line 701, in run_engine_core
(EngineCore_DP0 pid=2738693)     engine_core.run_busy_loop()
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core.py", line 728, in run_busy_loop
(EngineCore_DP0 pid=2738693)     self._process_engine_step()
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core.py", line 754, in _process_engine_step
(EngineCore_DP0 pid=2738693)     outputs, model_executed = self.step_fn()
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core.py", line 283, in step
(EngineCore_DP0 pid=2738693)     scheduler_output = self.scheduler.schedule()
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/core/sched/scheduler.py", line 359, in schedule
(EngineCore_DP0 pid=2738693)     if structured_output_req and structured_output_req.grammar:
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/request.py", line 45, in grammar
(EngineCore_DP0 pid=2738693)     completed = self._check_grammar_completion()
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/request.py", line 33, in _check_grammar_completion
(EngineCore_DP0 pid=2738693)     self._grammar = self._grammar.result(timeout=0.0001)
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/concurrent/futures/_base.py", line 458, in result
(EngineCore_DP0 pid=2738693)     return self.__get_result()
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/concurrent/futures/_base.py", line 403, in __get_result
(EngineCore_DP0 pid=2738693)     raise self._exception
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/concurrent/futures/thread.py", line 58, in run
(EngineCore_DP0 pid=2738693)     result = self.fn(*self.args, **self.kwargs)
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/__init__.py", line 128, in _async_create_grammar
(EngineCore_DP0 pid=2738693)     key = request.structured_output_request.structured_output_key  # type: ignore[union-attr]
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/functools.py", line 981, in __get__
(EngineCore_DP0 pid=2738693)     val = self.func(instance)
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/request.py", line 58, in structured_output_key
(EngineCore_DP0 pid=2738693)     return get_structured_output_key(self.sampling_params)
(EngineCore_DP0 pid=2738693)   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/structured_output/request.py", line 86, in get_structured_output_key
(EngineCore_DP0 pid=2738693)     raise ValueError("No valid structured output parameter found")
(EngineCore_DP0 pid=2738693) ValueError: No valid structured output parameter found
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145] Error in chat completion stream generator.
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145] Traceback (most recent call last):
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/entrypoints/openai/serving_chat.py", line 574, in chat_completion_stream_generator
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]     async for res in result_generator:
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/async_llm.py", line 387, in generate
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]     out = q.get_nowait() or await q.get()
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/output_processor.py", line 59, in get
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]     raise output
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/async_llm.py", line 439, in output_handler
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]     outputs = await engine_core.get_output_async()
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]   File "/aisoft/conda/env/vllm2/lib/python3.10/site-packages/vllm/v1/engine/core_client.py", line 846, in get_output_async
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145]     raise self._format_exception(outputs) from None
(APIServer pid=2738423) ERROR 10-10 10:43:10 [serving_chat.py:1145] vllm.v1.engine.exceptions.EngineDeadError: EngineCore encountered an issue. See stack trace (above) for the root cause.
[rank0]:[W1010 10:43:10.666166970 ProcessGroupNCCL.cpp:1538] Warning: WARNING: destroy_process_group() was not called before program exit, which can leak resources. For more info, please see https://pytorch.org/docs/stable/distributed.html#shutdown (function operator())
(APIServer pid=2738423) INFO:     Shutting down
(APIServer pid=2738423) INFO:     Waiting for application shutdown.
(APIServer pid=2738423) INFO:     Application shutdown complete.
(APIServer pid=2738423) INFO:     Finished server process [2738423]