title: Trying to use multiprocessing to fill an array in python
body: <p>I have a code like this</p>
  
  <pre><code>x = 3;
  y = 3;
  z = 10;
  ar = np.zeros((x,y,z))
  
  from multiprocessing import Process, Pool
  
  para = []
  process = []
  def local_func(section):
      print "section %s" % str(section)
      ar[2,2,section] = 255
      print "value set %d", ar[2,2,section]
  
  pool = Pool(1)
  
  run_list = range(0,10)
  list_of_results = pool.map(local_func, run_list)
  
  print ar
  </code></pre>
  
  <p>The value in ar was not changed with multithreading, what might be wrong?</p>
  
  <p>thanks</p>