Review CR #6611830: UUID thread-safety and performance improvements

Mike Duigou mike.duigou at
Wed Feb 23 00:29:18 UTC 2011

Daniel Aioanei reported via Josh Bloch a data race issue with the UUID accessor and hashCode() methods. I've prepared a webrev with the suggested changes:

I've tested the change against the standard UUID tests and did a microbenchmark test of one method, variant(), to see what impact not caching had on performance. Since there was only negligible change in performance vs. the existing UUID implementation I am comfortable with eliminating the cache values. It would appear that a field access plus a shift is not a significant cost over a field access.


More information about the core-libs-dev mailing list