一個LinkedBlockingQueue線程安全的例子

一個LinkedBlockingQueue線程安全的例子

package llj.mf.ace;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.LinkedBlockingQueue;

public class Ace {

	public static void main(String[] args) throws Exception {

		final Queue<Integer> q1 = new LinkedBlockingQueue<>();
		final Queue<Integer> q2 = new LinkedBlockingQueue<>();
		final int n = 1000000;
		final int m = 100;

		for (int i = 0; i < n; i++) {
			q1.add(i);
		}

		List<Thread> ts = new ArrayList<>();
		for (int i = 0; i < m; i++) {
			ts.add(new Thread(new Runnable() {
				public void run() {
					int i = 0;
					while (q2.size() < n && i++ < n / m) { // q2.size() 非線程安全，所以設置每個線程添加平均個數，防止poll出null報錯
						q2.add(q1.poll());
					}
				}
			}));
		}

		for (Thread t : ts) {
			t.start();
		}

		System.out.println("啟動了 " + m + " 個線程，每個線程處理 " + n / m + " 個操作");

		for (Thread t : ts) {
			while (t.isAlive()) {
				Thread.sleep(1);
			}
		}

		System.out.println("q1.size()：" + q1.size());
		System.out.println("q2.size()：" + q2.size());

		Set<Integer> set = new HashSet<>();
		Integer i;
		while ((i = q2.poll()) != null) {
			set.add(i);
		}
		System.out.println("q2.size()：" + q2.size());
		System.out.println("set.size()：" + set.size());
	}

}