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

[Jon VanAlten]

----- Original Message -----
> From: "Omair Majid" <omajid at redhat.com>
> To: "Andrew Hughes" <gnu.andrew at redhat.com>
> Cc: "jdk6-dev" <jdk6-dev at openjdk.java.net>
> Sent: Friday, May 31, 2013 4:54:35 PM
> Subject: Re: [PATCH FOR REVIEW] 7036559: ConcurrentHashMap footprint and	contention improvements
> 
> 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.
> 

It looks to me like those differences from cleanup changes pushed to
jdk7u and not backported.  They certainly aren't introduced in this
webrev.  Being as it's just minor whitespace and comment changes, I
don't think it's worth hunting down the specific cleanup changes to
backport from 7u, and also it doesn't seem like any reason to avoid
backporting these ConcurrentHashMap changes.

cheers,
jon