Changeset: 43bd5ee0205e Author: mduigou Date: 2012-05-30 22:18 -0700 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/43bd5ee0205e
7126277: Alternative String hashing implementation Summary: All of the hashing based Map implementations: HashMap, Hashtable, LinkedHashMap, WeakHashMap and ConcurrentHashMap are modified to use an enhanced hashing algorithm for string keys when the capacity of the hash table has ever grown beyond 512 entries. The enhanced hashing implementation uses the murmur3 hashing algorithm along with random hash seeds and index masks. These enhancements mitigate cases where colliding String hash values could result in a performance bottleneck. Reviewed-by: alanb, forax, dl ! make/java/java/FILES_java.gmk ! src/share/classes/java/lang/String.java ! src/share/classes/java/util/HashMap.java ! src/share/classes/java/util/Hashtable.java ! src/share/classes/java/util/LinkedHashMap.java ! src/share/classes/java/util/WeakHashMap.java ! src/share/classes/java/util/concurrent/ConcurrentHashMap.java + src/share/classes/sun/misc/Hashing.java ! test/java/util/Collection/BiggernYours.java ! test/java/util/Hashtable/HashCode.java ! test/java/util/Hashtable/SimpleSerialization.java + test/java/util/Map/Collisions.java ! test/java/util/Map/Get.java + test/sun/misc/Hashing.java
