This commit modifies the elasticsearch/connection_pool.py file to solve the list index out of range error. (elastic#539)

Fixes elastic#371

Author: HusainZafar

elasticsearch/connection_pool.py

@@ -1,6 +1,7 @@
 import time
 import random
 import logging
+import threading
 
 try:
  from Queue import PriorityQueue, Empty
@@ -58,12 +59,12 @@ class RoundRobinSelector(ConnectionSelector):
  """
  def __init__(self, opts):
  super(RoundRobinSelector, self).__init__(opts)
- self.rr = -1
+ self.data = threading.local()
 
  def select(self, connections):
- self.rr += 1
- self.rr %= len(connections)
- return connections[self.rr]
+ self.data.rr = getattr(self.data, 'rr', -1) + 1
+ self.data.rr %= len(connections)
+ return connections[self.data.rr]
 
 class ConnectionPool(object):
  """