A Discussion about Semaphore, and Cyclic Barrier

Break the loop using threads (Threads forum at JavaRanch)

This is an interesting discussion involved Semaphore and Cyclic Barrier in Java. I just keep in here for further references.

Rohan Dhapodkar

1. import java.util.concurrent.Semaphore;
4. public class PrintUsingSemaphore {
6. public static void main(String[] args) throws Exception{
7. final Semaphore semaphore = new Semaphore(1);
8. class MyPrinter implements Runnable {
9. public void run(){
10. for (int i = 0; i < 20; i++) {
11. try {
12. semaphore.acquire();
13. System.out.println(i+" "+Thread.currentThread().getName());
14. semaphore.release();
15. Thread.sleep(100);
16. } catch (InterruptedException e) {
17. e.printStackTrace();
18. }
19. }
20. }
21. };
23. for (int i = 0; i < 2; i++) {
24. Thread t = new Thread(new MyPrinter());
25. t.setPriority(Thread.MAX_PRIORITY-i*2);
26. t.start();
27. }
28. Thread.sleep(100000);
29. }
31. }

1. import java.util.concurrent.BrokenBarrierException;
2. import java.util.concurrent.CyclicBarrier;
5. public class PrintUsingCyclicBarrier {
7. public static void main(String[] args) throws Exception{
8. final CyclicBarrier semaphore = new CyclicBarrier(2,new Runnable() {
9. public void run() {
10. System.out.println();
11. }
12. });
13. class MyPrinter implements Runnable {
14. public void run(){
15. for (int i = 0; i < 20; i++) {
16. try {
17. semaphore.await();
18. System.out.print(i+" ");
19. Thread.sleep(100);
20. } catch (InterruptedException e) {
21. e.printStackTrace();
22. }catch (BrokenBarrierException e) {
23. e.printStackTrace();
24. }
25. }
26. }
27. };
29. for (int i = 0; i < 2; i++) {
30. Thread t = new Thread(new MyPrinter());
31. t.setPriority(Thread.MAX_PRIORITY-i*2);
32. t.start();
33. }
34. Thread.sleep(100000);
35. }
37. }

Harsha Smith

1. public static void main(String[] args) throws Exception{
3. class MyPrinter implements Runnable {
4. public void run(){
5. for (int i = 0; i < 20; i++) {
6. try {
7. System.out.println(i +" "+Thread.currentThread().getName());
9. TimeUnit.MILLISECONDS.sleep(1);
10. } catch (InterruptedException e) {
11. e.printStackTrace();
12. }
13. }
14. }
15. };
17. for (int i = 0; i < 2; i++) {
18. Thread t = new Thread(new MyPrinter());
19. t.start();
20. }
22. }