evaluate_sbert_multi_gpu run error

[ET-yzk]

i got some errors when runing example evaluate_sbert_multi_gpu.py:

File "/root/miniconda3/envs/qe/lib/python3.9/site-packages/beir/retrieval/evaluation.py", line 20, in retrieve
    return self.retriever.search(corpus, queries, self.top_k, self.score_function, **kwargs)
  File "/root/miniconda3/envs/qe/lib/python3.9/site-packages/beir/retrieval/search/dense/exact_search_multi_gpu.py", line 127, in search
    pool = self.model.start_multi_process_pool(self.target_devices)
  File "/root/miniconda3/envs/qe/lib/python3.9/site-packages/beir/retrieval/models/sentence_bert.py", line 35, in start_multi_process_pool
    p.start()
  File "/root/miniconda3/envs/qe/lib/python3.9/multiprocessing/process.py", line 121, in start
    self._popen = self._Popen(self)
  File "/root/miniconda3/envs/qe/lib/python3.9/multiprocessing/context.py", line 284, in _Popen
    return Popen(process_obj)
  File "/root/miniconda3/envs/qe/lib/python3.9/multiprocessing/popen_spawn_posix.py", line 32, in __init__
    super().__init__(process_obj)
  File "/root/miniconda3/envs/qe/lib/python3.9/multiprocessing/popen_fork.py", line 19, in __init__
    self._launch(process_obj)
  File "/root/miniconda3/envs/qe/lib/python3.9/multiprocessing/popen_spawn_posix.py", line 42, in _launch
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "/root/miniconda3/envs/qe/lib/python3.9/multiprocessing/spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "/root/miniconda3/envs/qe/lib/python3.9/multiprocessing/spawn.py", line 134, in _check_not_importing_main
    raise RuntimeError('''
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.