[PATCH FOR REVIEW] 7036559: ConcurrentHashMap footprint and contention improvements

[Omair Majid]

On 05/31/2013 05:38 PM, Andrew Hughes wrote:
> This fix was determined to be a prerequisite backport for the 2013-04 security fixes.
> 
> http://cr.openjdk.java.net/~andrew/jdk6/7036559/

I did a diff between the result of this patch and the file in jdk7u
after revision 005c0c85b0de and it looks identical, except for minor
changes:

> --- jdk7u/jdk/src/share/classes/java/util/concurrent/ConcurrentHashMap.java	2013-05-31 18:32:28.179433269 -0400
> +++ temp/ConcurrentHashMap.java	2013-05-31 17:34:06.000000000 -0400
> @@ -30,7 +30,7 @@
>   *
>   * Written by Doug Lea with assistance from members of JCP JSR-166
>   * Expert Group and released to the public domain, as explained at
> - * http://creativecommons.org/publicdomain/zero/1.0/
> + * http://creativecommons.org/licenses/publicdomain
>   */
>  
>  package java.util.concurrent;
> @@ -1412,7 +1412,7 @@
>       * for each key-value mapping, followed by a null pair.
>       * The key-value mappings are emitted in no particular order.
>       */
> -    private void writeObject(java.io.ObjectOutputStream s) throws IOException {
> +    private void writeObject(java.io.ObjectOutputStream s) throws IOException  {
>          // force all segments for serialization compatibility
>          for (int k = 0; k < segments.length; ++k)
>              ensureSegment(k);
> @@ -1446,7 +1446,7 @@
>       */
>      @SuppressWarnings("unchecked")
>      private void readObject(java.io.ObjectInputStream s)
> -        throws IOException, ClassNotFoundException {
> +        throws IOException, ClassNotFoundException  {
>          s.defaultReadObject();
>  
>          // Re-initialize segments to be minimally sized, and let grow.

I don't see any API changes in the webrev; that's good.

Do you also intend to backport the following?

changeset:   4110:e9ec52c63a9f
user:        dl
date:        Thu Apr 21 17:00:23 2011 +0100
summary:     7038542: Small performace regression in ConcurrentHashMap
on c1 since CR 703655

Thanks,
Omair
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