10.6. Python multiprocessing errors
You might experience Python multiprocessing warnings or runtime errors. This can be caused by code that is not properly structured for Python multiprocessing. The following is an example console warning:
WARNING 12-11 14:50:37 multiproc_worker_utils.py:281] CUDA was previously initialized. We must use the `spawn` multiprocessing start method. Setting VLLM_WORKER_MULTIPROC_METHOD to 'spawn'.The following is an example Python runtime error:
RuntimeError: An attempt has been made to start a new process before the current process has finished its bootstrapping phase. This probably means that you are not using fork to start your child processes and you have forgotten to use the proper idiom in the main module: if __name__ = "__main__": freeze_support() ... The "freeze_support()" line can be omitted if the program is not going to be frozen to produce an executable. To fix this issue, refer to the "Safe importing of main module" section in https://docs.python.org/3/library/multiprocessing.htmlTo resolve the runtime error, update your Python code to guard the usage of
vllmbehind anif__name__ = "__main__":block, for example:if __name__ = "__main__": import vllm llm = vllm.LLM(...)