fix memcache memory leak (#278)

Apparently the closure used in parsing the memcache config is
leaving behind some uncollectable objects on each run. Replaced
it with a while loop.

checks/db/mcache.py

@@ -55,6 +55,8 @@
 # https://github.com/membase/ep-engine/blob/master/docs/stats.org
 
 class Memcache(Check):
+    DEFAULT_PORT = 11211
+
     def __init__(self, logger):
         Check.__init__(self, logger)
         self.gauge("memcache.total_items")
@@ -102,23 +104,21 @@ def _load_conf(self, agentConfig):
         #memcache_instance_1: first_host:first_port:first_tag
         #memcache_instance_2: second_host:second_port:second_tag
         #memcache_instance_3: third_host:third_port:third_tag
-        def load_conf(index=1):
+        index = 1
+        instance = agentConfig.get("memcache_instance_%s" % index, None)
+        while instance:
+            instance = instance.split(":")
+            memcache_urls.append(instance[0])
+            if len(instance)>1:
+                memcache_ports.append(instance[1])
+            else:
+                memcache_ports.append(self.DEFAULT_PORT)
+            if len(instance)==3:
+                tags.append(instance[2])
+            else:
+                tags.append(None)
+            index = index + 1
             instance = agentConfig.get("memcache_instance_%s" % index, None)
-            if instance is not None:
-                instance = instance.split(":")
-                memcache_urls.append(instance[0])
-                if len(instance)>1:
-                    memcache_ports.append(instance[1])
-                else:
-                    memcache_ports.append(11211)
-                if len(instance)==3:
-                    tags.append(instance[2])
-                else:
-                    tags.append(None)
-
-                load_conf(index+1)
-
-        load_conf()
 
         return (memcache_urls, memcache_ports, tags)
 

tests/test_mcache.py

@@ -8,6 +8,12 @@
 class TestMemCache(unittest.TestCase):
     def setUp(self):
         self.c = Memcache(logging.getLogger(__file__))
+        self.agent_config = {
+            "memcache_server": "localhost",
+            "memcache_instance_1": "localhost:11211:mytag",
+            "memcache_instance_2": "dummy:11211:myothertag",
+            "memcache_instance_3": "localhost:11211:mythirdtag",
+        }
 
     def _countConnections(self, port):
         pid = os.getpid()
@@ -28,15 +34,25 @@ def testConnectionLeaks(self):
 
     def testMetrics(self):
         raise SkipTest("Test is not working anymore on travis boxes. Needs further investigation")
-        agent_config = {"memcache_server": "localhost",
-                           "memcache_instance_1": "localhost:11211:mytag",
-                           "memcache_instance_2": "dummy:11211:myothertag",
-                           "memcache_instance_3": "localhost:11211:mythirdtag"}
-        self.c.check(agent_config)
-        r = self.c.check(agent_config)
+        self.c.check(self.agent_config)
+        r = self.c.check(self.agent_config)
 
         self.assertEquals(len([t for t in r if t[0] == "memcache.total_items"]), 3, r)
         self.assertEquals(len([t for t in r if t[3].get('tags') == ["instance:mythirdtag"]]), 20, r)
 
+    def testMemoryLeak(self):
+        import gc
+        gc.set_debug(gc.DEBUG_LEAK)
+        try:
+            start = len(gc.garbage)
+            for i in range(10):
+                self.c.check(self.agent_config)
+            end = len(gc.garbage)
+            self.assertEquals(end - start, 0, gc.garbage)
+        finally:
+            gc.set_debug(0)
+
+
+
 if __name__ == '__main__':
     unittest.main()