Python的多处理管理器dict连接错误

Question

我正在尝试与多处理共享词典。 问题与这些类似：

• python multiprocessing manager - shared list - connection reset by peer 104
• Share list between process in python server

但是，建议的解决方案不适合我（添加process.join（））。 最简单的代码示例是：

import multiprocessing as mp
from multiprocessing import Manager


def test(i, multi_cache):
    print(i)
    multi_cache[i] = 'Test'
    print('inside', multi_cache.items())
    


with Manager() as manager:
    multi_cache = manager.dict()

    processes = [mp.Process(target=test, args=(i, multi_cache)) for i in range(3)]
    for p in processes:
        p.start()
    for p in processes:
        p.join()

    print(multi_cache.items())

输出为：

0
1
inside [(0, 'Test'), (1, 'Test')]
2

然后我得到了这个错误：

Process Process-8:
Process Process-6:
Traceback (most recent call last):
Traceback (most recent call last):
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "<ipython-input-3-c78e9bf0d6ec>", line 8, in test
    print('inside', multi_cache.items())
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 749, in _callmethod
    conn = self._tls.connection
  File "<string>", line 2, in items
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 757, in _callmethod
    kind, result = conn.recv()
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 250, in recv
    buf = self._recv_bytes()
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 407, in _recv_bytes
    buf = self._recv(4)
AttributeError: 'ForkAwareLocal' object has no attribute 'connection'
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 379, in _recv
    chunk = read(handle, remaining)
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
ConnectionResetError: [Errno 104] Connection reset by peer
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "<ipython-input-3-c78e9bf0d6ec>", line 7, in test
    multi_cache[i] = 'Test'
  File "<string>", line 2, in __setitem__
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 753, in _callmethod
    self._connect()
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 741, in _connect
    dispatch(conn, None, 'accept_connection', (name,))
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 79, in dispatch
    kind, result = c.recv()
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 250, in recv
    buf = self._recv_bytes()
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 407, in _recv_bytes
    buf = self._recv(4)
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 379, in _recv
    chunk = read(handle, remaining)
ConnectionResetError: [Errno 104] Connection reset by peer
Traceback (most recent call last):
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 749, in _callmethod
    conn = self._tls.connection
AttributeError: 'ForkAwareLocal' object has no attribute 'connection'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2961, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-3-c78e9bf0d6ec>", line 21, in <module>
    print(multi_cache.items())
  File "<string>", line 2, in items
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 753, in _callmethod
    self._connect()
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 740, in _connect
    conn = self._Client(self._token.address, authkey=self._authkey)
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 487, in Client
    c = SocketClient(address)
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 614, in SocketClient
    s.connect(address)
ConnectionRefusedError: [Errno 111] Connection refused

奇怪的是，当只启动一个进程时，错误略有不同，并在print语句处中断：

Traceback (most recent call last):
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 749, in _callmethod
    conn = self._tls.connection
AttributeError: 'ForkAwareLocal' object has no attribute 'connection'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2961, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-2-d7a43009862c>", line 21, in <module>
    print(multi_cache.items())
  File "<string>", line 2, in items
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 753, in _callmethod
    self._connect()
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/managers.py", line 740, in _connect
    conn = self._Client(self._token.address, authkey=self._authkey)
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 493, in Client
    answer_challenge(c, authkey)
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 732, in answer_challenge
    message = connection.recv_bytes(256)         # reject large message
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 216, in recv_bytes
    buf = self._recv_bytes(maxlength)
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 407, in _recv_bytes
    buf = self._recv(4)
  File "/home/user/src/anaconda3/envs/pythonenv/lib/python3.6/multiprocessing/connection.py", line 379, in _recv
    chunk = read(handle, remaining)
ConnectionResetError: [Errno 104] Connection reset by peer

我正在用Python3.6.10在Ubuntu16.04上进行尝试。你知道怎么解决这个问题吗？谢谢