Re: Dexterity performance issues.

Hmm, the benchmarking I did early in Dexterity's life suggested that it 
was roughly comparable in performance to Archetypes. It's possible that 
a regression has happened since then, or it's possible that that 
benchmark didn't adequately cover this use case.

Thanks for providing your benchmark code so others can investigate.

On 5/16/14, 8:37 AM, Matt Hamilton wrote:
> After digging around for most of a day, it seems like the main culprit is the __get__ call in p.dexterity.content.FTIAwareSpecification:
> https://github.com/plone/plone.dexterity/blob/master/plone/dexterity/content.py#L69
>
> In short, this is a method that on AT types is in C, and in Dexterity is in Python (I think). The DX call also has a mutex around a module level schema cache which may not be helping things (although in this case there is only one thread). In this *specific* case, setting a class-level attribute of __ac_local_roles_block__ = None does help as is means that accessing that attribute on a DX object stops there and don’t trigger then custom __getattr__ code. But it is a wider problem. Anytime you call e.g. IFoo.providedBy(my_dx_object) then it takes a long time… and we do that *a lot*.
>
I have a branch I never finished up where I added a list of attributes 
that are commonly missing or acquired to make sure that __getattr__ 
doesn't try to look them up as fields. Does this help at all?

+MISSING_OR_ACQUIRED_ATTRIBUTES = frozenset([
+    '__allow_groups__',
+    '__annotations__',
+    '__bobo_traverse__',
+    '__cmp__',
+    '__conform__',
+    '__provides__',
+    '_dav_writelocks',
+    '_EtagSupport__etag',
+    '_isPortalRoot',
+    '_is_wrapperish',
+    '_owner',
+    '_plone.uuid',
+    '_subobject_permissions',
+    '_v__providedBy__',
+    'aq_inner',
+    'dav__title',
+    'default_page',
+    'displayContentsTab',
+    'document_src',
+    'externalEditorEnabled',
+    'im_self',
+    'index_html',
+    'isTemporary',
+    'folder_listing',
+    'getCurrentSkinName',
+    'getCustomNavQuery',
+    'getFolderContents',
+    'getRawRelatedItems',
+    'getURL',
+    'global_cache_settings',
+    'global_statusmessage',
+    'layout',
+    'kss_generic_macros',
+    'main_template',
+    'plone_utils',
+    'portal_actions',
+    'portal_catalog',
+    'portal_css',
+    'portal_factory',
+    'portal_javascripts',
+    'portal_kss',
+    'portal_languages',
+    'portal_membership',
+    'portal_placeful_workflow',
+    'portal_properties',
+    'portal_types',
+    'portal_url',
+    'portal_workflow',
+    'role_map',
+    'sort-on',
+    'sort-limit',
+    'sort-order',
+    'translation_service',
+    'view',
+    ])
+
+
  class DexterityContent(DAVResourceMixin, PortalContent, 
DefaultDublinCoreImpl, Contained):
      """Base class for Dexterity content
      """
@@ -183,13 +244,15 @@ class DexterityContent(DAVResourceMixin, 
PortalContent, DefaultDublinCoreImpl, C
      description = u''

      def __getattr__(self, name):
-        # optimization: sometimes we're asked for special attributes
-        # such as __conform__ that we can disregard (because we
-        # wouldn't be in here if the class had such an attribute
-        # defined).
-        if name.startswith('__'):
+        """Return default values for fields that don't have a value 
stored."""
+        # optimization: avoid checking the schema for names that
+        # are expected to be missing or acquired
+        if name in MISSING_OR_ACQUIRED_ATTRIBUTES \
+                or name.endswith('_Permission'):
              raise AttributeError(name)

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