Java - Use Phaser in multiple phases by synchronizing multiple parties in each phase.

  1. HOME
  2. Java
  3. Thread
  4. Phasers

Introduction

Each tasks add integer in each phase and add them to a List.

After the Phaser is terminated, compute the sum of all the generated integers.

Demo

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import java.util.concurrent.Phaser;

class AdderTask extends Thread {
  private Phaser phaser;
  private String taskName;
  private List<Integer> list;
  public AdderTask(String taskName, Phaser phaser, List<Integer> list) {
    this.taskName = taskName;
    this.phaser = phaser;
    this.list = list;
  }/*from w  ww  .ja va  2  s .c  o  m*/

  @Override
  public void run() {
    do {
      System.out.println(taskName + " added " + 2);
      // Add the integer to the list
      list.add(2);

      // Wait for all parties to arrive at the phaser
      phaser.arriveAndAwaitAdvance();
    } while (!phaser.isTerminated());
  }
}

public class Main {
  public static void main(String[] args) {
    final int PHASE_COUNT = 2;
    Phaser phaser = new Phaser() {
      public boolean onAdvance(int phase, int parties) {
        System.out.println("Phase:" + phase + ", Parties:" + parties
            + ", Arrived:" + this.getArrivedParties());
        boolean terminatePhaser = false;
        if (phase >= PHASE_COUNT - 1 || parties == 0) {
          terminatePhaser = true;
        }
        return terminatePhaser;
      }
    };
    List<Integer> list = Collections.synchronizedList(new ArrayList<Integer>());
    int ADDER_COUNT = 3;
    phaser.bulkRegister(ADDER_COUNT + 1);
    for (int i = 1; i <= ADDER_COUNT; i++) {
      String taskName = "Task #" + i;
      AdderTask task = new AdderTask(taskName, phaser, list);
      task.start();
    }
    while (!phaser.isTerminated()) {
      phaser.arriveAndAwaitAdvance();
    }
    // Phaser is terminated now. Compute the sum
    int sum = 0;
    for (Integer num : list) {
      sum = sum + num;
    }
    System.out.println("Sum = " + sum);
  }
}

Result

Related Topic