Ticket #15324: memcached_connection_reuse.patch

django/core/cache/backends/memcached.py

@@ -28 +28 @@
         """
         Implements transparent thread-safe access to a memcached client.
         """
-        return self._lib.Client(self._servers)
+        client = getattr(self, 'client', None)
+        if client:
+            return client
 
+        client = self._lib.Client(self._servers)
+
+        self.client = client
+
+        return client
+
     def _get_memcache_timeout(self, timeout):
         """
         Memcached deals with long (> 30 days) timeouts in a special

tests/regressiontests/cache/tests.py

@@ -801 +801 @@
         # memcached limits key length to 250
         self.assertRaises(Exception, self.cache.set, 'a' * 251, 'value')
 
+    def test_connection_reuse(self):
+        """
+        Ensure that we don't create a new memcached connection for every
+        cache operation.
+        """
+
+        # deliberately bypass the _cache, to ensure that fetching of stats doesn't muddy the results
+        cache = self.cache._lib.Client(self.cache._servers)
+        def count_connections():
+            # get_stats() returns a list of (server, stats_dictionary) tuples
+            return sum(int(stats[1]['curr_connections']) for stats in cache.get_stats())
+
+        # perform a cache operation...
+        self.cache.set('foo', 'bar')
+        connections = count_connections()
+
+        # ... a second cache operation on the same key should not increase the number of connections!
+        self.cache.get('foo')
+        self.assertEqual(connections, count_connections())
+
 MemcachedCacheTests = unittest.skipUnless(settings.CACHES[DEFAULT_CACHE_ALIAS]['BACKEND'].startswith('django.core.cache.backends.memcached.'), "memcached not available")(MemcachedCacheTests)
 
 class FileBasedCacheTests(unittest.TestCase, BaseCacheTests):