bpo-44155: Add backlog arg for multiprocessing manager server

Author: junnplus

Doc/library/multiprocessing.rst

@@ -2517,7 +2517,7 @@ multiple connections at the same time.
    ``'AF_UNIX'`` and address is ``None`` then the socket will be created in a
    private temporary directory created using :func:`tempfile.mkstemp`.
 
-   If the listener object uses a socket then *backlog* (1 by default) is passed
+   If the listener object uses a socket then *backlog* (None by default) is passed
    to the :meth:`~socket.socket.listen` method of the socket once it has been
    bound.
 

Lib/multiprocessing/connection.py

@@ -452,7 +452,7 @@ class Listener(object):
     This is a wrapper for a bound socket which is 'listening' for
     connections, or for a Windows named pipe.
     '''
-    def __init__(self, address=None, family=None, backlog=1, authkey=None):
+    def __init__(self, address=None, family=None, backlog=None, authkey=None):
         family = family or (address and address_type(address)) \
                  or default_family
         address = address or arbitrary_address(family)
@@ -597,7 +597,7 @@ class SocketListener(object):
     '''
     Representation of a socket which is bound to an address and listening
     '''
-    def __init__(self, address, family, backlog=1):
+    def __init__(self, address, family, backlog=None):
         self._socket = socket.socket(getattr(socket, family))
         try:
             # SO_REUSEADDR has different semantics on Windows (issue #2550).
@@ -606,7 +606,10 @@ def __init__(self, address, family, backlog=1):
                                         socket.SO_REUSEADDR, 1)
             self._socket.setblocking(True)
             self._socket.bind(address)
-            self._socket.listen(backlog)
+            if backlog is None:
+                self._socket.listen()
+            else:
+                self._socket.listen(backlog)
             self._address = self._socket.getsockname()
         except OSError:
             self._socket.close()

Lib/multiprocessing/managers.py

@@ -146,7 +146,7 @@ class Server(object):
     public = ['shutdown', 'create', 'accept_connection', 'get_methods',
               'debug_info', 'number_of_objects', 'dummy', 'incref', 'decref']
 
-    def __init__(self, registry, address, authkey, serializer):
+    def __init__(self, registry, address, authkey, serializer, backlog=None):
         if not isinstance(authkey, bytes):
             raise TypeError(
                 "Authkey {0!r} is type {1!s}, not bytes".format(
@@ -156,7 +156,7 @@ def __init__(self, registry, address, authkey, serializer):
         Listener, Client = listener_client[serializer]
 
         # do authentication later
-        self.listener = Listener(address=address, backlog=128)
+        self.listener = Listener(address=address, backlog=backlog)
         self.address = self.listener.address
 
         self.id_to_obj = {'0': (None, ())}