Hi, May I have review for "JDK-8229871: Imporve performance of Method.copy() and leafCopy()"?
Method.copy() and leafCopy() creates a copy of a Method object with sharing MethodAccessor object. Since the methodAccessor field is a volatile variable, copying this field needs memory fence to ensure the field is visible to all threads on the weak memory platforms such as POWER and ARM. When the methodAccessor of the root object is null (i.e., not initialized yet), we do not need to copy the null value because this field of the copied object has been initialized to null in the constructor. We can reduce overhead of the memory fence only when the root's methodAccessor is non-null. This change improved performance by 5.8% using a micro benchmark that repeatedly invokes Class.getMethods(). Bug: https://bugs.openjdk.java.net/browse/JDK-8229871 Webrev: http://cr.openjdk.java.net/~ogatak/8229871/webrev.00/ By the way, why Method.methodAccessor is volatile, while Field.fieldAccessor and Field.overrideFieldAccessor are not volatile? I know the use of volatile reduces probability of creating duplicated method accessor, but the chance still exists. I couldn't find the difference between Method and Field classes to make Method.methodAccessor volatile. If we can make it non-volatile, it is more preferable than a quick hack above. Regards, Ogata
