title: python multiprocessing pool Assertion Error in interpreter
body: <p>I am writing a sample program to test the usage of multiprocessing pool of workers in python 2.7.2+ </p>
  
  <p>This is the code i have written in the python ubuntu interpreter</p>
  
  <pre><code>&gt;&gt;&gt; from multiprocessing import Pool
  &gt;&gt;&gt; def name_append(first_name,last_name):
  ...     return first_name+" "+last_name
  ...
  
  &gt;&gt;&gt; from functools import partial
  &gt;&gt;&gt; partial_name_append=partial(name_append,'kiran')
  &gt;&gt;&gt; partial_name_append('acb')
  'kiran acb'
  &gt;&gt;&gt; abc='kiran'
  
  &gt;&gt;&gt; pool=Pool(processes=4)
  &gt;&gt;&gt; pool.map(partial_name_append,abc)
  ['kiran k', 'kiran i', 'kiran r', 'kiran a', 'kiran n']
  &gt;&gt;&gt; pool.close()
  &gt;&gt;&gt; pool.join()
  
  &gt;&gt;&gt; pool.map(partial_name_append,abc)
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/usr/lib/python2.7/multiprocessing/pool.py", line 226, in map
      assert self._state == RUN
  AssertionError
  </code></pre>
  
  <p>After i got pickle errors, over my pool of workers code for large data sets, i am trying to do small examples and try to figure out what is the error.</p>
  
  <p>I dont understand why the same statement 'pool.map' doesn't work, when it has worked above. I think i have executed the 'pool map' correctly but i dont understand the reason.</p>
  
  <p>Is this error related to "PicklingError: Can't pickle : attribute lookup <strong>builtin</strong>.function failed"</p>
  
  <p>Can someone help me out ?</p>
  
  <p>Thanks</p>