Tested on MacOSX 10.5.4, running test_multiprocessing in a tight loop :

[~/Sources/py3k]> while true;do ./python ./Lib/test/regrtest.py 
test_multiprocessing;done
test_multiprocessing
1 test OK.
test_multiprocessing
1 test OK.
test_multiprocessing
1 test OK.
test_multiprocessing
Process Process-48:
Traceback (most recent call last):
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/managers.py", 
line 720, 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 "/Users/cartman/Sources/py3k/Lib/multiprocessing/process.py", 
line 232, in _bootstrap
    self.run()
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/process.py", 
line 88, in run
    self._target(*self._args, **self._kwargs)
  File "/Users/cartman/Sources/py3k/Lib/test/test_multiprocessing.py", 
line 601, in f
    cond.acquire()
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/managers.py", 
line 949, in acquire
    return self._callmethod('acquire', (blocking,))
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/managers.py", 
line 724, in _callmethod
    self._connect()
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/managers.py", 
line 711, in _connect
    conn = self._Client(self._token.address, authkey=self._authkey)
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/connection.py", 
line 133, in Client
    c = SocketClient(address)
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/connection.py", 
line 254, in SocketClient
    s.connect(address)
socket.error: [Errno 61] Connection refused
Exception in thread Thread-58:
Traceback (most recent call last):
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/managers.py", 
line 720, 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 "/Users/cartman/Sources/py3k/Lib/threading.py", line 492, in 
_bootstrap_inner
    self.run()
  File "/Users/cartman/Sources/py3k/Lib/threading.py", line 447, in run
    self._target(*self._args, **self._kwargs)
  File "/Users/cartman/Sources/py3k/Lib/test/test_multiprocessing.py", 
line 601, in f
    cond.acquire()
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/managers.py", 
line 949, in acquire
    return self._callmethod('acquire', (blocking,))
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/managers.py", 
line 724, in _callmethod
    self._connect()
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/managers.py", 
line 711, in _connect
    conn = self._Client(self._token.address, authkey=self._authkey)
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/connection.py", 
line 133, in Client
    c = SocketClient(address)
  File "/Users/cartman/Sources/py3k/Lib/multiprocessing/connection.py", 
line 254, in SocketClient
    s.connect(address)
socket.error: [Errno 61] Connection refused