[Python-checkins] cpython: Issue 18774: Update news and whatsnew for the set optimizations

[raymond.hettinger]

http://hg.python.org/cpython/rev/a02339bda413
changeset:   85266:a02339bda413
parent:      85264:28e68f4807a2
user:        Raymond Hettinger <python at rcn.com>
date:        Mon Aug 19 09:12:20 2013 -0700
summary:
  Issue 18774:  Update news and whatsnew for the set optimizations

files:
  Doc/whatsnew/3.4.rst |  6 ++++++
  Misc/NEWS            |  4 ++++
  2 files changed, 10 insertions(+), 0 deletions(-)


diff --git a/Doc/whatsnew/3.4.rst b/Doc/whatsnew/3.4.rst
--- a/Doc/whatsnew/3.4.rst
+++ b/Doc/whatsnew/3.4.rst
@@ -389,6 +389,12 @@
 
 * The UTF-32 decoder is now 3x to 4x faster.
 
+* The cost of hash collisions for sets is now reduced.  Each hash table
+  probe now checks a second key/hash pair for each cache line retrieved.
+  This exploits cache locality to make collision resolution less expensive.
+
+  (Contributed by Raymond Hetting in :issue"`18771`.)
+
 
 Build and C API Changes
 =======================
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,10 @@
 
 - Issue #18774: Remove last bits of GNU PTH thread code and thread_pth.h.
 
+- Issue #18771: Add optimization to set object lookups to reduce the cost
+  of hash collisions.  The core idea is to inspect a second key/hash pair
+  for each cache line retrieved.
+
 - Issue #16105: When a signal handler fails to write to the file descriptor
   registered with ``signal.set_wakeup_fd()``, report an exception instead
   of ignoring the error.

-- 
Repository URL: http://hg.python.org/cpython