parallel-python error: RuntimeError("Socket connection is broken")

I am using a simple program to send a function:

import pp
nodes=('mosura02','mosura03','mosura04','mosura05','mosura06',
       'mosura09','mosura10','mosura11','mosura12')
nodes=('miner:60001',)
def pptester():

   js=pp.Server(ppservers=nodes)
   js.set_ncpus(0)
   tmp=[]
   for i in range(200):
      tmp.append(js.submit(ppworktest,(),(),('os',)))
   return tmp

def ppworktest():
   import os
   return os.system("uname -a")

the result is:

wkerzend@mosura:/home/wkerzend/tmp/ppython_test>ssh miner "source ~/coala_pyth开发者_运维百科on_setup.sh;ppserver.py -d -p 60001"
2010-04-12 00:50:48,162 - pp - INFO - Creating server instance (pp-1.6.0)
2010-04-12 00:50:52,732 - pp - INFO - pp local server started with 32 workers
2010-04-12 00:50:52,732 - pp - DEBUG - Strarting network server interface=0.0.0.0 port=60001
Exception in thread client_socket:
Traceback (most recent call last):
  File "/usr/lib64/python2.6/threading.py", line 525, in __bootstrap_inner
    self.run()
  File "/usr/lib64/python2.6/threading.py", line 477, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/home/wkerzend/python_coala/bin/ppserver.py", line 161, in crun
    ctype = mysocket.receive()
  File "/home/wkerzend/python_coala/lib/python2.6/site-packages/pptransport.py", line 178, in receive
    raise RuntimeError("Socket connection is broken")
RuntimeError: Socket connection is broken