I have your same problem and i think the performance is a little degraded.
Are you using always -XX:+UseMembar ? or did you find another solution?
After posting this, the original issue that all threads were waiting for ReentrantReadWriteLock happened again.
So -XX:+UseMembar is not helpful.
The issue is pending on a bug now.
With this option (-XX:+UseMembar) I work,
only once in the tomcat it got stuck!!!
Then on only one server i did change the garbage collector alghoritm to
and on this server it do never stuck!!!