runtime-error-attemp-to-start-a-new-process-before-the-current-process

RuntimeError: Attempt to start a new process before the current process has finished its bootstrapping phase. This probably means that you are on Windows 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 a Windows executable.

Solution

As the note said, add __main__`` guard and add freeze_support()` and the begining.

if __name__ == "__main__":
    # multiprocessing.freeze_support() # may be not needed
    start = time.time()
    ...

Ref:

https://discuss.pytorch.org/t/runtimeerror-an-attempt-has-been-made-to-start-a-new-process-before-the-current-process-has-finished-its-bootstrapping-phase/145462/9