Fixed several reference cycles to prevent memory leaks. Added simple …

…test for detect memory leaks after application closing.

Backport #2967 to the 1.7-branch

CONTRIBUTORS.txt

@@ -278,3 +278,13 @@ Contributors
 - Jon Davidson, 2016/07/18
 
 - Keith Yang, 2016/07/22
+
+- Hannah Krager, 2016/10/22
+
+- Moriyoshi Koizumi, 2016/11/20
+
+- Mikko Ohtamaa, 2016/12/6
+
+- Martin Frlin, 2016/12/7
+
+- Kirill Kuzminykh, 2017/03/01

pyramid/registry.py

@@ -257,7 +257,9 @@ def __init__(self, func):
 
     @reify
     def value(self):
-        return self.func()
+        result = self.func()
+        del self.func
+        return result
 
     def resolve(self):
         return self.value

pyramid/tests/test_integration.py

@@ -1,13 +1,15 @@
 # -*- coding: utf-8 -*-
 
 import datetime
+import gc
 import locale
 import os
 import unittest
 
 from pyramid.wsgi import wsgiapp
 from pyramid.view import view_config
 from pyramid.static import static_view
+from pyramid.testing import skip_on
 from pyramid.compat import (
     text_,
     url_quote,
@@ -741,3 +743,29 @@ def _assertBody(body, filename):
     data = data.replace(b'\r', b'')
     data = data.replace(b'\n', b'')
     assert(body == data)
+
+
+class MemoryLeaksTest(unittest.TestCase):
+
+    def tearDown(self):
+        import pyramid.config
+        pyramid.config.global_registries.empty()
+
+    def get_gc_count(self):
+        last_collected = 0
+        while True:
+            collected = gc.collect()
+            if collected == last_collected:
+                break
+            last_collected = collected
+        return len(gc.get_objects())
+
+    @skip_on('pypy')
+    def test_memory_leaks(self):
+        from pyramid.config import Configurator
+        Configurator().make_wsgi_app()  # Initialize all global objects
+
+        initial_count = self.get_gc_count()
+        Configurator().make_wsgi_app()
+        current_count = self.get_gc_count()
+        self.assertEqual(current_count, initial_count)

pyramid/util.py

@@ -220,17 +220,20 @@ def add(self, item):
             self._order.remove(oid)
             self._order.append(oid)
             return
-        ref = weakref.ref(item, lambda x: self.remove(item))
+        ref = weakref.ref(item, lambda x: self._remove_by_id(oid))
         self._items[oid] = ref
         self._order.append(oid)
 
-    def remove(self, item):
+    def _remove_by_id(self, oid):
         """ Remove an item from the set."""
-        oid = id(item)
         if oid in self._items:
             del self._items[oid]
             self._order.remove(oid)
 
+    def remove(self, item):
+        """ Remove an item from the set."""
+        self._remove_by_id(id(item))
+
     def empty(self):
         """ Clear all objects from the set."""
         self._items = {}