Issue 18771: Make it possible to set the number linear probes at compile-time.
diff --git a/Doc/whatsnew/3.4.rst b/Doc/whatsnew/3.4.rst
index 0749f03..e91ce2a 100644
--- a/Doc/whatsnew/3.4.rst
+++ b/Doc/whatsnew/3.4.rst
@@ -444,8 +444,15 @@
* 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.
+ probe now checks a series of consecutive, adjacent key/hash pairs before
+ continuing to make random probes through the hash table. This exploits
+ cache locality to make collision resolution less expensive.
+
+ The collision resolution scheme can be described as a hybrid of linear
+ probing and open addressing. The number of additional linear probes
+ defaults to nine. This can be changed at compile-time by defining
+ LINEAR_PROBES to be any value. Set LINEAR_PROBES=0 to turn-off
+ linear probing entirely.
(Contributed by Raymond Hettinger in :issue"`18771`.)