- Structural memory use has been improved via much more significant use

of ``__slots__`` for many internal objects.  This optimization is
particularly geared towards the base memory size of large applications
that have lots of tables and columns, and greatly reduces memory
size for a variety of high-volume objects including event listening
internals, comparator objects and parts of the ORM attribute and
loader strategy system.

diff --git a/doc/build/changelog/changelog_10.rst b/doc/build/changelog/changelog_10.rst
index bfe2ebbc6fac61f6bbd0554fdda086bfa8f15dec..7f9fbff91b2e5edf0e21fba1adf98e312b1b5969 100644 (file)
--- a/doc/build/changelog/changelog_10.rst
+++ b/doc/build/changelog/changelog_10.rst
@@ -22,6 +22,21 @@
     series as well.  For changes that are specific to 1.0 with an emphasis
     on compatibility concerns, see :doc:`/changelog/migration_10`.
 
+    .. change::
+        :tags: feature, general
+
+        Structural memory use has been improved via much more significant use
+        of ``__slots__`` for many internal objects.  This optimization is
+        particularly geared towards the base memory size of large applications
+        that have lots of tables and columns, and greatly reduces memory
+        size for a variety of high-volume objects including event listening
+        internals, comparator objects and parts of the ORM attribute and
+        loader strategy system.
+
+        .. seealso::
+
+            :ref:`feature_slots`
+
     .. change::
         :tags: bug, mysql
         :tickets: 3283

diff --git a/doc/build/changelog/migration_10.rst b/doc/build/changelog/migration_10.rst
index 79756ec17603864601edb8e303b58b0c636c95ce..e5382be542d64f26b2b6c739054188541a7680f3 100644 (file)
--- a/doc/build/changelog/migration_10.rst
+++ b/doc/build/changelog/migration_10.rst
@@ -8,7 +8,7 @@ What's New in SQLAlchemy 1.0?
     undergoing maintenance releases as of May, 2014,
     and SQLAlchemy version 1.0, as of yet unreleased.
 
-    Document last updated: December 14, 2014
+    Document last updated: January 4, 2015
 
 Introduction
 ============
@@ -286,6 +286,37 @@ object totally smokes both namedtuple and KeyedTuple::
 
 :ticket:`3176`
 
+.. _feature_slots:
+
+Significant Improvements in Structural Memory Use
+--------------------------------------------------
+
+Structural memory use has been improved via much more significant use
+of ``__slots__`` for many internal objects.  This optimization is
+particularly geared towards the base memory size of large applications
+that have lots of tables and columns, and reduces memory
+size for a variety of high-volume objects including event listening
+internals, comparator objects and parts of the ORM attribute and
+loader strategy system.
+
+A bench that makes use of heapy measure the startup size of Nova
+illustrates a difference of about 2 megs of memory, a total of 27%
+of memory taken up by SQLAlchemy's objects, associated dictionaries, as
+well as weakrefs, within a basic import of "nova.db.sqlalchemy.models"::
+
+    # reported by heapy, summation of SQLAlchemy objects +
+    # associated dicts + weakref-related objects with core of Nova imported:
+
+        Before: total count 26477 total bytes 7975712
+        After: total count 21413 total bytes 5752976
+
+    # reported for the Python module space overall with the
+    # core of Nova imported:
+
+        Before: Partition of a set of 355558 objects. Total size = 61661760 bytes.
+        After: Partition of a set of 350281 objects. Total size = 59415104 bytes.
+
+
 .. _feature_updatemany:
 
 UPDATE statements are now batched with executemany() in a flush