Please review the enhancement at http://cr.openjdk.java.net/~weijun/7004967/webrev.00/
Basically, we want SecureRandom to be more efficient by removing all synchronized keywords from its public methods and let an implementation to take care of thread-safety (We already did some in JDK-8098581). On the other hand, we need to make sure that existing implementations that have not synchronized correctly to behave just as good as before.
Therefore a new Service Attribute "ThreadSafe" is introduced. If you think your implementation is already thread-safe, set it to "true" and SecureRandom will be happy. Otherwise, don't set it and SecureRandom will continuously call your SecureRandomSpi engine methods in synchronized blocks.
Thanks Max
