In ArrayBlockingQueue, why copy final member field into local final variable?

Question

In ArrayBlockingQueue, all the methods that require the lock copy it to a local final variable before calling lock().

Answer 1

This thread gives some answers. In substance:

• the compiler can't easily prove that a final field does not change within a method (due to reflection / serialization etc.)
• most current compilers actually don't try and would therefore have to reload the final field everytime it is used which could lead to a cache miss or a page fault
• storing it in a local variable forces the JVM to perform only one load