Issue #3125: Remove copy_reg in multiprocessing and replace it with

ForkingPickler.register() to resolve conflict with ctypes.

Lib/multiprocessing/forking.py

@@ -12,7 +12,7 @@ import signal
 
 from multiprocessing import util, process
 
-__all__ = ['Popen', 'assert_spawning', 'exit', 'duplicate', 'close']
+__all__ = ['Popen', 'assert_spawning', 'exit', 'duplicate', 'close', 'ForkingPickler']
 
 #
 # Check that the current thread is spawning a child process
@@ -25,6 +25,50 @@ def assert_spawning(self):
             ' through inheritance' % type(self).__name__
             )
 
+#
+# Try making some callable types picklable
+#
+
+from pickle import _Pickler as Pickler
+class ForkingPickler(Pickler):
+    dispatch = Pickler.dispatch.copy()
+    @classmethod
+    def register(cls, type, reduce):
+        def dispatcher(self, obj):
+            rv = reduce(obj)
+            if isinstance(rv, str):
+                self.save_global(obj, rv)
+            else:
+                self.save_reduce(obj=obj, *rv)
+        cls.dispatch[type] = dispatcher
+
+def _reduce_method(m):
+    if m.__self__ is None:
+        return getattr, (m.__class__, m.__func__.__name__)
+    else:
+        return getattr, (m.__self__, m.__func__.__name__)
+class _C:
+    def f(self):
+        pass
+ForkingPickler.register(type(_C().f), _reduce_method)
+
+
+def _reduce_method_descriptor(m):
+    return getattr, (m.__objclass__, m.__name__)
+ForkingPickler.register(type(list.append), _reduce_method_descriptor)
+ForkingPickler.register(type(int.__add__), _reduce_method_descriptor)
+
+try:
+    from functools import partial
+except ImportError:
+    pass
+else:
+    def _reduce_partial(p):
+        return _rebuild_partial, (p.func, p.args, p.keywords or {})
+    def _rebuild_partial(func, args, keywords):
+        return partial(func, *args, **keywords)
+    ForkingPickler.register(partial, _reduce_partial)
+
 #
 # Unix
 #
@@ -105,16 +149,18 @@ else:
     import _thread
     import msvcrt
     import _subprocess
-    import copyreg
     import time
 
     from ._multiprocessing import win32, Connection, PipeConnection
     from .util import Finalize
 
-    try:
-        from cPickle import dump, load, HIGHEST_PROTOCOL
-    except ImportError:
-        from pickle import dump, load, HIGHEST_PROTOCOL
+    #try:
+    #    from cPickle import dump, load, HIGHEST_PROTOCOL
+    #except ImportError:
+    from pickle import load, HIGHEST_PROTOCOL
+
+    def dump(obj, file, protocol=None):
+        ForkingPickler(file, protocol).dump(obj)
 
     #
     #
@@ -346,9 +392,8 @@ else:
         return type(conn), (Popen.duplicate_for_child(conn.fileno()),
                             conn.readable, conn.writable)
 
-    copyreg.pickle(Connection, reduce_connection)
-    copyreg.pickle(PipeConnection, reduce_connection)
-
+    ForkingPickler.register(Connection, reduce_connection)
+    ForkingPickler.register(PipeConnection, reduce_connection)
 
 #
 # Prepare current process

Lib/multiprocessing/managers.py

@@ -18,13 +18,12 @@ import sys
 import weakref
 import threading
 import array
-import copyreg
 import queue
 
 from traceback import format_exc
 from multiprocessing import Process, current_process, active_children, Pool, util, connection
 from multiprocessing.process import AuthenticationString
-from multiprocessing.forking import exit, Popen, assert_spawning
+from multiprocessing.forking import exit, Popen, assert_spawning, ForkingPickler
 from multiprocessing.util import Finalize, info
 
 try:
@@ -38,14 +37,14 @@ except ImportError:
 
 def reduce_array(a):
     return array.array, (a.typecode, a.tostring())
-copyreg.pickle(array.array, reduce_array)
+ForkingPickler.register(array.array, reduce_array)
 
 view_types = [type(getattr({}, name)()) for name in ('items','keys','values')]
 if view_types[0] is not list:       # only needed in Py3.0
     def rebuild_as_list(obj):
         return list, (list(obj),)
     for view_type in view_types:
-        copyreg.pickle(view_type, rebuild_as_list)
+        ForkingPickler.register(view_type, rebuild_as_list)
 
 #
 # Type for identifying shared objects

Lib/multiprocessing/reduction.py

@@ -13,11 +13,10 @@ import os
 import sys
 import socket
 import threading
-import copyreg
 
 import _multiprocessing
 from multiprocessing import current_process
-from multiprocessing.forking import Popen, duplicate, close
+from multiprocessing.forking import Popen, duplicate, close, ForkingPickler
 from multiprocessing.util import register_after_fork, debug, sub_debug
 from multiprocessing.connection import Client, Listener
 
@@ -134,7 +133,7 @@ def rebuild_handle(pickled_data):
     return new_handle
 
 #
-# Register `_multiprocessing.Connection` with `copy_reg`
+# Register `_multiprocessing.Connection` with `ForkingPickler`
 #
 
 def reduce_connection(conn):
@@ -147,10 +146,10 @@ def rebuild_connection(reduced_handle, readable, writable):
         handle, readable=readable, writable=writable
         )
 
-copyreg.pickle(_multiprocessing.Connection, reduce_connection)
+ForkingPickler.register(_multiprocessing.Connection, reduce_connection)
 
 #
-# Register `socket.socket` with `copy_reg`
+# Register `socket.socket` with `ForkingPickler`
 #
 
 def fromfd(fd, family, type_, proto=0):
@@ -169,10 +168,10 @@ def rebuild_socket(reduced_handle, family, type_, proto):
     close(fd)
     return _sock
 
-copyreg.pickle(socket.socket, reduce_socket)
+ForkingPickler.register(socket.socket, reduce_socket)
 
 #
-# Register `_multiprocessing.PipeConnection` with `copy_reg`
+# Register `_multiprocessing.PipeConnection` with `ForkingPickler`
 #
 
 if sys.platform == 'win32':
@@ -187,4 +186,4 @@ if sys.platform == 'win32':
             handle, readable=readable, writable=writable
             )
 
-    copyreg.pickle(_multiprocessing.PipeConnection, reduce_pipe_connection)
+    ForkingPickler.register(_multiprocessing.PipeConnection, reduce_pipe_connection)

Lib/multiprocessing/sharedctypes.py

@@ -9,10 +9,9 @@
 import sys
 import ctypes
 import weakref
-import copyreg
 
 from multiprocessing import heap, RLock
-from multiprocessing.forking import assert_spawning
+from multiprocessing.forking import assert_spawning, ForkingPickler
 
 __all__ = ['RawValue', 'RawArray', 'Value', 'Array', 'copy', 'synchronized']
 
@@ -124,8 +123,7 @@ def reduce_ctype(obj):
 def rebuild_ctype(type_, wrapper, length):
     if length is not None:
         type_ = type_ * length
-    if sys.platform == 'win32' and type_ not in copyreg.dispatch_table:
-        copyreg.pickle(type_, reduce_ctype)
+    ForkingPickler.register(type_, reduce_ctype)
     obj = type_.from_address(wrapper.get_address())
     obj._wrapper = wrapper
     return obj

Lib/multiprocessing/util.py

@@ -8,7 +8,6 @@
 
 import itertools
 import weakref
-import copyreg
 import atexit
 import threading        # we want threading to install it's
                         # cleanup function before multiprocessing does
@@ -302,35 +301,3 @@ class ForkAwareLocal(threading.local):
         register_after_fork(self, lambda obj : obj.__dict__.clear())
     def __reduce__(self):
         return type(self), ()
-
-#
-# Try making some callable types picklable
-#
-
-def _reduce_method(m):
-    if m.__self__ is None:
-        return getattr, (m.__self__.__class__, m.__func__.__name__)
-    else:
-        return getattr, (m.__self__, m.__func__.__name__)
-copyreg.pickle(type(Finalize.__init__), _reduce_method)
-
-def _reduce_method_descriptor(m):
-    return getattr, (m.__objclass__, m.__name__)
-copyreg.pickle(type(list.append), _reduce_method_descriptor)
-copyreg.pickle(type(int.__add__), _reduce_method_descriptor)
-
-def _reduce_builtin_function_or_method(m):
-    return getattr, (m.__self__, m.__name__)
-copyreg.pickle(type(list().append), _reduce_builtin_function_or_method)
-copyreg.pickle(type(int().__add__), _reduce_builtin_function_or_method)
-
-try:
-    from functools import partial
-except ImportError:
-    pass
-else:
-    def _reduce_partial(p):
-        return _rebuild_partial, (p.func, p.args, p.keywords or {})
-    def _rebuild_partial(func, args, keywords):
-        return partial(func, *args, **keywords)
-    copyreg.pickle(partial, _reduce_partial)