Files
changeTest/MonitorCase2/src/PC.java
Karsten Jeppesen 3196804d11 2. Monitors
Concurrency
2020-08-26 14:25:02 +02:00

42 lines
1.5 KiB
Java

/*
* In MonitorCase1, the producer thread quickly fills the buffer
* with characters and then waits for the consumer to consume
* some characters from the buffer. The problem is that the
* producer waits inside the monitor associated with the buffer,
* preventing the consumer to execute the synchronized Get
* method on the buffer.
*
* We really want the Producer to release the monitor if the
* buffer becomes full and allow the Consumer to proceed.
* Similarly, the Consumer must release the monitor if the
* buffer becomes empty and allow the Producer to proceed.
* To coordinate the two threads, we must use the Object's
* wait() and notify or notifyAll() methods.
*
* The wait() method suspends the calling thread and temporarily
* releases ownership of the monitor (so it allows other threads
* to acquire the monitor). The suspended thread that called
* wait() wakes up only when another thread calls notify() or
* notifyAll() on that object.
*
* The notifyAll() method wakes up all threads waiting on the
* object in question. The awakened threads compete for the
* monitor. One thread gets it, and the others go back to
* waiting.
*
* Code courtesy of www.csc.villanova.edu/~mdamian/threads/javamonitors.html
*/
public class PC {
public static void main(String[] args) {
Buffer b = new Buffer(4);
Producer p = new Producer(b);
Consumer c = new Consumer(b);
p.start();
c.start();
}
}