目录

错误代码

报错信息

错误原因

解决方法

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错误代码

python多进程管理manager时候，当不使用join对当前进程（主进程）进行阻塞时会报错，具体代码及错误如下：

from multiprocessing import Process, Manager
import time
import os
 
 
def info(title):
    print(title)
    print('module name:', __name__)
    print('parent process:', os.getppid())
    print('process id:', os.getpid())
    print("\n\n")
 
 
 
def f(d, l,n):
    info('\033[32;1m subprocess line\033[0m')
    d[1] = '1'
    d['2'] = 2
    d[0.25] = None
    l.append(n)
    print(l)
 
 
if __name__ == '__main__':
    info('\033[32;1mmain process line\033[0m')
    with Manager() as manager:
        d = manager.dict()
 
        l = manager.list(range(5))
        p_list = []
        for i in range(10):
            p = Process(target=f, args=(d, l,i))
            p_list.append(p)
            # p.join()
        for p in p_list:
            p.start()

报错信息

Process Process-11:
Traceback (most recent call last):
  File "/usr/lib/python3.4/multiprocessing/managers.py", line 724, 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 "/usr/lib/python3.4/multiprocessing/process.py", line 254, in _bootstrap
    self.run()
  File "/usr/lib/python3.4/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "managerTest.py", line 19, in f
    d[1] = '1'
  File "<string>", line 2, in __setitem__
  File "/usr/lib/python3.4/multiprocessing/managers.py", line 728, in _callmethod
    self._connect()
  File "/usr/lib/python3.4/multiprocessing/managers.py", line 715, in _connect
    conn = self._Client(self._token.address, authkey=self._authkey)
  File "/usr/lib/python3.4/multiprocessing/connection.py", line 495, in Client
    c = SocketClient(address)
  File "/usr/lib/python3.4/multiprocessing/connection.py", line 624, in SocketClient
    s.connect(address)
FileNotFoundError: [Errno 2] No such file or directory

错误原因

启动工作进程后 主进程立即就结束了，创建multiprocessing.Manager的进程完成执行后，Manager服务器将关闭，这意味着您的共享列表对象现在无用了。

发生这种情况是因为Manager对象将其shutdown函数注册为multiprocessing模块的" finalizer"，这意味着它将在进程退出之前运行。这是在BaseManager.__init__中注册它的代码：

# register a finalizer
self._state.value = State.STARTED
self.shutdown = util.Finalize(
    self, type(self)._finalize_manager,
    args=(self._process, self._address, self._authkey,
          self._state, self._Client),
    exitpriority=0
    )

这是实际执行关闭操作的代码：

@staticmethod
def _finalize_manager(process, address, authkey, state, _Client):
    '''
    Shutdown the manager process; will be registered as a finalizer
    '''
    if process.is_alive():
        util.info('sending shutdown message to manager')
        try:
            conn = _Client(address, authkey=authkey)
            try:
                dispatch(conn, None, 'shutdown')
            finally:
                conn.close()
        except Exception:
            pass

        process.join(timeout=1.0)
        if process.is_alive():
            util.info('manager still alive')
            if hasattr(process, 'terminate'):
                util.info('trying to `terminate()` manager process')
                process.terminate()
                process.join(timeout=0.1)
                if process.is_alive():
                    util.info('manager still alive after terminate')

    state.value = State.SHUTDOWN
    try:
        del BaseProxy._address_to_local[address]
    except KeyError:
        pass

解决方法

在主进程中 对子进程进行 join 等待