A barrier is a rendezvous point for multiple threads: all threads must arrive at the barrier before any of them are permitted to proceed past the barrier. J2SE 5.0 supplies a barrier class, and a barrier class for previous versions of Java can be found in the Appendix A.
Condition variable
A condition variable is not actually a lock; it is a variable associated with a lock. Condition variables are often used in the context of data synchronization. Condition variables generally have an API that achieves the same functionality as Java's wait-and-notify mechanism; in that mechanism, the condition variable is actually the object lock it is protecting. J2SE 5.0 also supplies explicit condition variables, and a condition variable implementation for previous versions of Java can be found in the Appendix A. Both kinds of condition variables are discussed in Chapter 4.
Critical section
A critical section is a synchronized method or block. Critical sections do not nest like synchronized methods or blocks.
Event variable
Event variable is another term for a condition variable.
Lock
This term refers to the access granted to a particular thread that has entered a synchronized method or block. We say that a thread that has entered such a method or block has acquired the lock. As we discussed in Chapter 3, a lock is associated with either a particular instance of an object or a particular class.
Monitor
