title: Multiprocessing shared variable not updating
body: <p>I'm trying to update a shared variable (numpy array in a namespace) when using the multiprocessing module. However, the variable is not updated and I dont understand why.</p>
  
  <p>Here is a sample code to illustrate this:</p>
  
  <pre><code>from multiprocessing import Process, Manager
  import numpy as np
  
  chunk_size = 15
  arr_length = 1000
  jobs = []
  namespace = Manager().Namespace()
  namespace.arr = np.zeros(arr_length)
  nb_chunk = arr_length/chunk_size + 1
  
  
  def foo(i, ns):
      from_idx = chunk_size*i
      to_idx = min(arr_length, chunk_size*(i+1))
      ns.arr[from_idx:to_idx] = np.random.randint(0, 100, to_idx-from_idx)
  
  for i in np.arange(nb_chunk):
      p = Process(target=foo, args=(i, namespace))
      p.start()
      jobs.append(p)
  for i in np.arange(nb_chunk):
      jobs[i].join()
  
  print namespace.arr[:10]
  </code></pre>