java线程池之newFixedThreadPool

Posted 2021-06-26 胡乐天

newFixedThreadPool 测试类

package com.thread.pool;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TestFixedThreadPool {

    public static void main(String[] args) {
        /**
         *  调用方法 new ThreadPoolExecutor(nThreads, nThreads,
         *                                       0L, TimeUnit.MILLISECONDS,
         *                                       new LinkedBlockingQueue<Runnable>());
         * newFixedThreadPool:用来创建一个固定大小的线程池
         * 只有一个参数，nThreads,即核心线程数和最大线程数
         * 采用无界的阻塞队列，可以存储最大整数个任务，所以实际的线程数量永远不会变化
         * 对当前线程数量进行限制，保证线程数可控，不会造成线程更多，导致系统负载更为严重。
         * 适用于负载较重的场景
         */
        ExecutorService executorService = Executors.newFixedThreadPool(2);

        for (int i=0;i<500;i++){
            ThreadPool threadPool = new ThreadPool(""+i);
            executorService.execute(threadPool);

        }
        executorService.shutdown();
    }
}

线程任务类

package com.thread.pool;

import java.util.Date;

public class ThreadPool implements Runnable {

    private static ThreadPool threadPool = null;
    String name;

    public ThreadPool(String name){
        this.name = name;
    }
    @Override
    public void run() {
        doSomeThing();
    }

    public static synchronized Runnable getInstance(){
        if(threadPool == null){
            threadPool = new ThreadPool("getInstance");
        }
        return getInstance();
    }

    private void doSomeThing() {

        for (int i=0;i<10;i++){
            System.out.println((new Date()).toLocaleString() + "   " + Thread.currentThread().getName() + "执行" +i + ",name=" + name);
        }

       /* try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }*/
    }
}