java 多线程 锁 demo

Java

2018-04-27

107

0

技术:java8

运行环境:IDEA 15.2 + jdk8 + windows 7

demo功能:java多线程锁竞争资源demo

源代码

package com.demoworld;

import java.util.concurrent.*;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * Created by francis on 2018/4/27.
 */
public class Startup {
    private static int taskCounter = 5000;
    private static int threadCounter = 200;
    private static int count = 0;

    private static Lock lock = new ReentrantLock();

    public static void main(String[] args) throws InterruptedException {
        reentrantLockDemo();
    }

    //多线程 竞争同一个资源, 锁demo, 依次输出1,2,3.。。taskCounter
    private static void reentrantLockDemo() throws InterruptedException {
        ExecutorService executorService = Executors.newCachedThreadPool();
        for (int i = 0; i < taskCounter; i++) {
            executorService.execute(() -> {
                try {
                    lock.lock();
                    count++;
                    lock.unlock();
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            });
        }
        Thread.sleep(1000L);
        executorService.shutdown();
        System.out.println(count);
    }

    private static Object object = new Object();

    //多线程 计数器. 多个任务做完后, 继续做其他的事情
    private static void countDownLatchDemo() throws InterruptedException {
        ExecutorService executorService = Executors.newCachedThreadPool();
        final CountDownLatch cdl = new CountDownLatch(taskCounter);
        final Semaphore semaphore = new Semaphore(threadCounter);

        for (int i = 0; i < taskCounter; i++) {
            executorService.execute(() -> {
                try {
                    semaphore.acquire();
                    synchronized (object) {
                        count++;
                    }
                    semaphore.release();
                } catch (Exception ex) {
                    ex.printStackTrace();
                } finally {
                    cdl.countDown();
                }
            });
        }
        cdl.await();
        executorService.shutdown();
        System.out.println(count);
    }

    //多线程 竞争同一个资源, 同步锁demo 依次输出1,2,3.。。taskCounter
    private static void lockDemo() throws InterruptedException {
        ExecutorService executorService = Executors.newCachedThreadPool();
        for (int i = 0; i < taskCounter; i++) {
            executorService.execute(() -> {
                try {
                    synchronized (object) {
                        add();
                    }
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            });
        }
        Thread.currentThread().join();
        executorService.shutdown();
    }

    //多线程 竞争同一个资源, 互斥 信号量 做锁 demo 依次输出1,2,3.。。taskCounter
    private static void semaphoreDemo() throws InterruptedException {
        ExecutorService executorService = Executors.newCachedThreadPool();
        final Semaphore semaphore = new Semaphore(1);
        for (int i = 0; i < taskCounter; i++) {
            executorService.execute(() -> {
                try {
                    semaphore.acquire();
                    add();
                    semaphore.release();
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            });
        }
        Thread.currentThread().join();
        executorService.shutdown();
    }

    private static void add() {
        count++;
        System.out.println(count);
    }
}
 
 

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