cache.py: Add a random delay to memcached retries

This should reduce memcached spam during outages

r2/r2/lib/cache.py

@@ -27,12 +27,15 @@ import cPickle as pickle
 from copy import copy
 from curses.ascii import isgraph
 import logging
+from time import sleep
 
 from pylons import g
 
 import pylibmc
 from _pylibmc import MemcachedError
 
+import random
+
 from pycassa import ColumnFamily
 from pycassa.cassandra.ttypes import ConsistencyLevel
 
@@ -176,6 +179,7 @@ class CMemcache(CacheUtils):
                 raise
             except MemcachedError as e:
                 ex = e
+            sleep(random.uniform(0, 0.1))
 
         event_name = "cache.retry.%s" % fn.__name__
         g.stats.event_count(event_name, "fail")