Reduce the number of circular references

This should avoid high memory usage due to largish object not being
deleted immediately by the reference counter.

Signed-off-by: Pierre Fersing <pierre.fersing@bleemeo.com>

rest_framework/response.py

@@ -13,6 +13,29 @@ from django.utils.six.moves.http_client import responses
 from rest_framework.serializers import Serializer
 
 
+def cleanup(response):
+    """ Cleanup circular reference between view/request/response object
+
+        This reduce load on GC and help to keep low memory usage even
+        if some response are larger.
+    """
+    view = response.renderer_context.get('view')
+    request = response.renderer_context.get('request')
+
+    if view:
+        view.response = None
+        view.request = None
+
+    if request:
+        request.parser_context.clear()
+
+    response.renderer_context.clear()
+
+    # Re-add request in renderer_context. It does not seem to cause
+    # circular reference and is needed for tests.
+    response.renderer_context['request'] = request
+
+
 class Response(SimpleTemplateResponse):
     """
     An HttpResponse that allows its data to be rendered into
@@ -48,6 +71,8 @@ class Response(SimpleTemplateResponse):
             for name, value in six.iteritems(headers):
                 self[name] = value
 
+        self.add_post_render_callback(cleanup)
+
     @property
     def rendered_content(self):
         renderer = getattr(self, 'accepted_renderer', None)

rest_framework/viewsets.py

@@ -100,7 +100,16 @@ class ViewSetMixin(object):
             self.kwargs = kwargs
 
             # And continue as usual
-            return self.dispatch(request, *args, **kwargs)
+            result = self.dispatch(request, *args, **kwargs)
+
+            # break our circular reference before finishing
+            for method in actions:
+                delattr(self, method)
+
+            if hasattr(self, 'head'):
+                delattr(self, 'head')
+
+            return result
 
         # take name and docstring from class
         update_wrapper(view, cls, updated=())

tests/test_generics.py

@@ -167,7 +167,7 @@ class TestRootView(TestCase):
         request = factory.post('/', data, HTTP_ACCEPT='text/html')
         response = self.view(request).render()
         expected_error = '<span class="help-block">Ensure this field has no more than 100 characters.</span>'
-        assert expected_error in response.rendered_content.decode('utf-8')
+        assert expected_error in response.content.decode('utf-8')
 
 
 EXPECTED_QUERIES_FOR_PUT = 2
@@ -314,7 +314,7 @@ class TestInstanceView(TestCase):
         request = factory.put('/', data, HTTP_ACCEPT='text/html')
         response = self.view(request, pk=1).render()
         expected_error = '<span class="help-block">Ensure this field has no more than 100 characters.</span>'
-        assert expected_error in response.rendered_content.decode('utf-8')
+        assert expected_error in response.content.decode('utf-8')
 
 
 class TestFKInstanceView(TestCase):