Hi，大家好，我是编程小6，很荣幸遇见你，我把这些年在开发过程中遇到的问题或想法写出来，今天说一说settingwithcopywarning_thread.start,希望能够帮助你!!!。

Setting OMP_NUM_THREADS environment variable for each process to be 1 in default, to avoid your system being overloaded, please further tune the variable for optimal performance in your application as needed. 

(pytorch1.3-cuda10.2) [huanghaiyang@dgx02 semantic-segmentation-main]$ python -m runx.runx scripts/eval_cityscapes.yml -i
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Setting OMP_NUM_THREADS environment variable for each process to be 1 in default, to avoid your system being overloaded, please further tune the variable for optimal performance in your application as needed. 
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跑代码的时候出现上述问题，这是由于pytouch分布式训练的问题。别人的代码设置了多个GPU并行，然而你跑的时候只用了一个或者两个，这个参数需要指定

python -m torch.distributed.launch --nproc_per_node=1 --master_port 88888 train.py

--nproc_per_node=1 这个1表示你实际的GPU数量，

--master_port 88888 这个表示端口，一般不用设置，或者随便设置一个数字就行。当出现

runtimeerror: address already in use

这时候加--master_port 12345 就行