MULTITHREADING AND PARALLEL PROGRAMMING - Introduction to Java Programming: Comprehensive Version - page 1120

int int

Task for adding an Task for deleting an

while (count == CAPACITY)
notFull.await();

while (count == 0 )

notEmpty.await();

int

int

Delete an from the buffer

Add an to the buffer

notEmpty.signal(); notFull.signal();

F IGURE 30.18

The conditions notFull and notEmpty are used to coordinate task

interactions.

The buffer is actually a first-in, first-out queue (lines 52-53). The conditions notEmpty
and notFull on the lock are created in lines 59-60. The conditions are bound to a lock. A
lock must be acquired before a condition can be applied. If you use the wait() and notify()
methods to rewrite this example, you have to designate two objects as monitors.

L ISTING 30.7

ConsumerProducer.java
1 import java.util.concurrent.*;
2 import java.util.concurrent.locks.*;
3
4 public class ConsumerProducer {
5 private static Buffer buffer = new Buffer(); create a buffer

6
7 public static void main(String[] args) {
8 // Create a thread pool with two threads
9 ExecutorService executor = Executors.newFixedThreadPool( 2 );
10 executor.execute( new ProducerTask());
11 executor.execute( new ConsumerTask());
12 executor.shutdown();
13 }
14
15 // A task for adding an int to the buffer
16 private static class ProducerTask implements Runnable {
17 public void run() {
18 try {
19 int i = 1 ;
20 while ( true ) {
21 System.out.println( "Producer writes " + i);
22 buffer.write(i++); // Add a value to the buffer
23 // Put the thread into sleep
24 Thread.sleep(( int )(Math.random() * 10000 ));
25 }
26 }
27 catch (InterruptedException ex) {
28 ex.printStackTrace();
29 }
30 }
31 }
32
33

create two threads

producer task

// A task for reading and deleting an int from the buffer

34 private static class ConsumerTask implements Runnable {

consumer task

35 public void run() {