在模型运行时遇到报错“RuntimeError: context has already been set”
2025/03/18
83
问题信息
| 问题来源 | 产品大类 | 产品子类 | 关键字 |
|---|---|---|---|
| 官方 | 模型训练 | PyTorch | -- |
问题现象描述
报错文本：
Traceback (most recent call last):
File "bad.py", line 6, in <module>
mp.set_start_method('spawn')
File "/usr/local/python3.8.5/lib/python3.8/multiprocessing/context.py", line 243, in set_start_method
raise RuntimeError('context has already been set')
RuntimeError: context has already been set
[ERROR] 2024-11-28-14:57:00 (PID:731691, Device:-1, RankID:-1) ERR99999 UNKNOWN application exception原因分析
昇腾NPU依赖python的multiprocessing.get_context多进程管理能力，受限于python本身的约束，用户如果使用mp.set_start_method('spawn')再次设置多进程启动方式，python会抛异常。
解决措施
使用try-except语句进行异常处理，具体操作如下：
import torch
import torch_npu
import multiprocessing as mp
if __name__ == "__main__":
try:
mp.set_start_method('spawn')
except:
print("context has already been set")