0715

http://docs.oracle.com/javase/tutorial/essential/concurrency/sync.html

thread interference  memory consistency errors

class Counter {
    private int c = 0;

记不起来，在类中似乎有变量不能赋值的。

memory consistency errors：happens-before relationship

http://docs.oracle.com/javase/tutorial/essential/concurrency/syncmeth.html

wo basic synchronization idioms: synchronized methods and synchronized statements.

When constructing an object that will be shared between threads, be very careful that a reference to the object does not "leak" prematurely. For example, suppose you want to maintain a List called instances containing every instance of class. You might be tempted to add the following line to your constructor:？？？

http://docs.oracle.com/javase/tutorial/essential/concurrency/locksync.html

Synchronization is built around an internal entity known as the intrinsic lock or monitor lock.