Cuda multiprocessing

vision
1

Hi,
I am trying to run multiprocessing in my python program. I created two processes and passed a neural network in the one process and some heavy computational function in the other. I wanted the neural net to run on GPU and the other function on CPU and thereby I defined neural net using cuda() method. But when I run the program the got the following error:
RuntimeError: Cannot re-initialize CUDA in forked subprocess. To use CUDA with multiprocessing, you must use the ‘spawn’ start method

So I tried with spawn as well as forkserver start method, but then I got the other error:
RuntimeError: cuda runtime error (71) : operation not supported at …/torch/csrc/generic/StorageSharing.cpp:245

I have tried python3 multiprocessing and torch.multiprocessing both but nothing worked for me.

2

Hi,

Do you have a bit more context about the second error? What is the stack trace that you get?

3

1_LI
1_LI1068×490 166 KB

4

cc @ptrblck what is the reason for this error on cuda? Do you know where this is coming from?

5

Usually we see these kind of errors for IPC using CUDATensors on Windows (e.g. as explained here).
However, based on the output it looks like a Linux system is being used.

@aman_bharat could you post a reproducible code snippet, so that we can have a look?

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