Chris, Looks good to me. David Holmes Christopher Hegarty - Sun Microsystems Ireland said the following on 02/21/09 07:46:

6806649: synchronization bottleneck when constructing Thread subclasses

Webrev: http://cr.openjdk.java.net/~chegar/6806649/webrev.00/webrev/

The global synchronization on Thread.subclassAudits at Thread construction time has been discussed as a bottleneck:

http://cs.oswego.edu/pipermail/concurrency-interest/2009-February/005839.htm...

The implementation approach for this cache of subclass audits matches the once-similar implementations in ObjectInputStream and ObjectOutputStream, but since the 5056445 fix in JDKs 5.0u7 and 6, those classes were changed to use a ConcurrentHashMap (with weakly referenced Class keys) instead-- Thread should probably be changed similarly.

Thanks, -Chris.