Pre-approved pending positive review. If you don't make the snapshot for
B17 we can arrange that you either push the fix or that we do a final
syncup of 7u-dev before next weeks build.
Cheers,
Edvard
On 06/27/2012 11:34 PM, Mike Duigou wrote:
Hello all;
Following testing and feedback the alternative hashing string keys in hash maps
which was introduced in CR#7126277 is going to be disabled by default in 7u6.
Developers can still enable the alternative hashing but by default it will be
disabled. More time is required for developers to test their applications and
correct improper usages before this feature can be enabled as the default
behaviour. The alternative hashing of String keys feature remains the default
for Java 8 and may become the default for Java 7 in a future release.
Developers are strongly encouraged test their applications by enabling the alternative string
hashing feature before it does become the default behaviour. The alternative Sring hashing feature
is enabled by setting the system property, jdk.map.althashing.threshold to a value smaller than the
capacity of the maps to be tested. The future default is likely to be "512" which will
have the effect of enabling alternative hashing of string keys for all maps who's capacity is
larger than 511 entries. Small maps only encounter limited impact from collisions and the higher
threshold also masks incidental dependence upon iteration order that may be present in those maps.
For the most rigorous testing, set the jdk.map.althashing.threshold property to "1" which
will force all maps to use alternative string hashing.
The current patch for review:
http://cr.openjdk.java.net/~mduigou/7180240/0/webrev/
This change is not a back port because jdk8 uses a different implementation and
is unaffected.
When approved and reviewed I intend to push it to
ssh://hg.openjdk.java.net/jdk7u/jdk7u-dev-gate/jdk
Regards,
Mike
