netty bytebuff 释放原则和防止内存泄露

Action	Who should release?	Who released?
1. main() creates buf	buf→main()
2. main() calls a() with buf	buf→a()
3. a() returns buf merely.	buf→main()
4. main() calls b() with buf	buf→b()
5. b() returns the copy of buf	buf→b(), copy→main()	b() releases buf
6. main() calls c() with copy	copy→c()
7. c() swallows copy	copy→c()	c() releases copy

• If a [sending] component is supposed to pass a reference-counted object to another [receiving] component, the sending component usually does not need to destroy it but defers that decision to the receiving component.
• If a component consumes a reference-counted object and knows nothing else will access it anymore (i.e., does not pass along a reference to yet another component), the component should destroy it.

1.A（byteBuff)接受了byteBuff, 然后又传给了另外一个方法B(bytebuff)，A方法内不用释放；

2.如果B(bytebuff)接受了byteBuff，没有再传递给其他方法，B负责release；

http://netty.io/wiki/reference-counted-objects.html

http://stackoverflow.com/questions/15781276/buffer-ownership-in-netty-4-how-is-buffer-life-cycle-managed