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python - python3.8下模块多处理错误

转载 作者:行者123 更新时间:2023-12-03 17:01:12 27 4
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直到今天,我的脚本都可以进行多处理。为了重现该问题,我简化了与下面显示的函数并行化的函数:

    from multiprocessing import Process, Queue
import random

def rand_num():
num = random.random()
print(num)

if __name__ == "__main__":
queue = Queue()

processes = [Process(target=rand_num, args=()) for x in range(4)]

for p in processes:
p.start()

for p in processes:
p.join()

呈现完全相同的错误消息(重复 4 次,为了便于阅读,我省略了重复):
    Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/spawn.py", line 116, in spawn_main
exitcode = _main(fd, parent_sentinel)
File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/spawn.py", line 125, in _main
prepare(preparation_data)
File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/spawn.py", line 236, in prepare
_fixup_main_from_path(data['init_main_from_path'])
File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/spawn.py", line 287, in _fixup_main_from_path
main_content = runpy.run_path(main_path,
File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/runpy.py", line 262, in run_path
code, fname = _get_code_from_file(run_name, path_name)
File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/runpy.py", line 232, in _get_code_from_file
with io.open_code(fname) as f:
FileNotFoundError: [Errno 2] No such file or directory: '/Users/myUserName/<stdin>'

我不知道从哪里开始调试这个错误。我在mac os Catalina(自制安装)下运行python3.8。请帮忙。

最佳答案

从 Python 3.7 升级到 3.8 时,我遇到了同样的问题。
特别是现在在 OSX 10.15.6 上运行 3.8.6,Python 由 pyenv 安装。
Darkonaut 的建议帮助解决了这个问题,但它并不那么明显,所以让我在这里重新表述一下:
MacOS 上的 Python 3.8 现在默认使用 spawn而不是 fork作为新进程的启动方法。尝试

multiprocessing.set_start_method("fork")
显然,spawn 的行为是错误的,如下简单示例所示:
import multiprocessing

def parallel_function(x):
print("Function called with", x)

def test_pool():
print("Running test_pool")
with multiprocessing.Pool(4) as pool:
pool.map(parallel_function, range(10))

print("Starting the test")
test_pool()
这会产生以下输出:
Starting the test
Running test_pool
Starting the test
Running test_pool
Starting the test
Running test_pool
Starting the test
Running test_pool
Starting the test
Running test_pool
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/Users/karel/.pyenv/versions/3.8.6/lib/python3.8/multiprocessing/spawn.py", line 116, in spawn_main
exitcode = _main(fd, parent_sentinel)
File "/Users/karel/.pyenv/versions/3.8.6/lib/python3.8/multiprocessing/spawn.py", line 125, in _main
prepare(preparation_data)
File "/Users/karel/.pyenv/versions/3.8.6/lib/python3.8/multiprocessing/spawn.py", line 236, in prepare
_fixup_main_from_path(data['init_main_from_path'])
File "/Users/karel/.pyenv/versions/3.8.6/lib/python3.8/multiprocessing/spawn.py", line 287, in _fixup_main_from_path
因此,池不会正确创建工作程序,而是尝试在每个生成的进程中运行整个脚本。

关于python - python3.8下模块多处理错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60518386/

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