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Fixes issue #6766: Updated multiprocessing Proxy Objects to support nesting

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This commit is contained in:
Davin Potts 2016-09-07 18:48:01 -05:00
parent 1aa642f6bd
commit 86a7668426
3 changed files with 192 additions and 56 deletions
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95
Lib/multiprocessing/managers.py
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@ -142,7 +142,8 @@ class Server(object):
self.id_to_obj = {'0': (None, ())}
self.id_to_refcount = {}
self.mutex = threading.RLock()
self.id_to_local_proxy_obj = {}
self.mutex = threading.Lock()
def serve_forever(self):
'''
@ -227,7 +228,14 @@ class Server(object):
methodname = obj = None
request = recv()
ident, methodname, args, kwds = request
obj, exposed, gettypeid = id_to_obj[ident]
try:
obj, exposed, gettypeid = id_to_obj[ident]
except KeyError as ke:
try:
obj, exposed, gettypeid = \
self.id_to_local_proxy_obj[ident]
except KeyError as second_ke:
raise ke
if methodname not in exposed:
raise AttributeError(
@ -308,7 +316,7 @@ class Server(object):
'''
with self.mutex:
result = []
keys = list(self.id_to_obj.keys())
keys = list(self.id_to_refcount.keys())
keys.sort()
for ident in keys:
if ident != '0':
@ -321,7 +329,8 @@ class Server(object):
'''
Number of shared objects
'''
return len(self.id_to_obj) - 1 # don't count ident='0'
# Doesn't use (len(self.id_to_obj) - 1) as we shouldn't count ident='0'
return len(self.id_to_refcount)
def shutdown(self, c):
'''
@ -363,13 +372,9 @@ class Server(object):
self.id_to_obj[ident] = (obj, set(exposed), method_to_typeid)
if ident not in self.id_to_refcount:
self.id_to_refcount[ident] = 0
# increment the reference count immediately, to avoid
# this object being garbage collected before a Proxy
# object for it can be created. The caller of create()
# is responsible for doing a decref once the Proxy object
# has been created.
self.incref(c, ident)
return ident, tuple(exposed)
self.incref(c, ident)
return ident, tuple(exposed)
def get_methods(self, c, token):
'''
@ -387,15 +392,45 @@ class Server(object):
def incref(self, c, ident):
with self.mutex:
self.id_to_refcount[ident] += 1
try:
self.id_to_refcount[ident] += 1
except KeyError as ke:
# If no external references exist but an internal (to the
# manager) still does and a new external reference is created
# from it, restore the manager's tracking of it from the
# previously stashed internal ref.
if ident in self.id_to_local_proxy_obj:
self.id_to_refcount[ident] = 1
self.id_to_obj[ident] = \
self.id_to_local_proxy_obj[ident]
obj, exposed, gettypeid = self.id_to_obj[ident]
util.debug('Server re-enabled tracking & INCREF %r', ident)
else:
raise ke
def decref(self, c, ident):
if ident not in self.id_to_refcount and \
ident in self.id_to_local_proxy_obj:
util.debug('Server DECREF skipping %r', ident)
return
with self.mutex:
assert self.id_to_refcount[ident] >= 1
self.id_to_refcount[ident] -= 1
if self.id_to_refcount[ident] == 0:
del self.id_to_obj[ident], self.id_to_refcount[ident]
util.debug('disposing of obj with id %r', ident)
del self.id_to_refcount[ident]
if ident not in self.id_to_refcount:
# Two-step process in case the object turns out to contain other
# proxy objects (e.g. a managed list of managed lists).
# Otherwise, deleting self.id_to_obj[ident] would trigger the
# deleting of the stored value (another managed object) which would
# in turn attempt to acquire the mutex that is already held here.
self.id_to_obj[ident] = (None, (), None) # thread-safe
util.debug('disposing of obj with id %r', ident)
with self.mutex:
del self.id_to_obj[ident]
#
# Class to represent state of a manager
@ -658,7 +693,7 @@ class BaseProxy(object):
_mutex = util.ForkAwareThreadLock()
def __init__(self, token, serializer, manager=None,
authkey=None, exposed=None, incref=True):
authkey=None, exposed=None, incref=True, manager_owned=False):
with BaseProxy._mutex:
tls_idset = BaseProxy._address_to_local.get(token.address, None)
if tls_idset is None:
@ -680,6 +715,12 @@ class BaseProxy(object):
self._serializer = serializer
self._Client = listener_client[serializer][1]
# Should be set to True only when a proxy object is being created
# on the manager server; primary use case: nested proxy objects.
# RebuildProxy detects when a proxy is being created on the manager
# and sets this value appropriately.
self._owned_by_manager = manager_owned
if authkey is not None:
self._authkey = process.AuthenticationString(authkey)
elif self._manager is not None:
@ -738,6 +779,10 @@ class BaseProxy(object):
return self._callmethod('#GETVALUE')
def _incref(self):
if self._owned_by_manager:
util.debug('owned_by_manager skipped INCREF of %r', self._token.id)
return
conn = self._Client(self._token.address, authkey=self._authkey)
dispatch(conn, None, 'incref', (self._id,))
util.debug('INCREF %r', self._token.id)
@ -822,19 +867,19 @@ class BaseProxy(object):
def RebuildProxy(func, token, serializer, kwds):
'''
Function used for unpickling proxy objects.
If possible the shared object is returned, or otherwise a proxy for it.
'''
server = getattr(process.current_process(), '_manager_server', None)
if server and server.address == token.address:
return server.id_to_obj[token.id][0]
else:
incref = (
kwds.pop('incref', True) and
not getattr(process.current_process(), '_inheriting', False)
)
return func(token, serializer, incref=incref, **kwds)
util.debug('Rebuild a proxy owned by manager, token=%r', token)
kwds['manager_owned'] = True
if token.id not in server.id_to_local_proxy_obj:
server.id_to_local_proxy_obj[token.id] = \
server.id_to_obj[token.id]
incref = (
kwds.pop('incref', True) and
not getattr(process.current_process(), '_inheriting', False)
)
return func(token, serializer, incref=incref, **kwds)
#
# Functions to create proxies and proxy types