淺談Java實作線程同步&互斥

先說簡單的，Java實作線程互斥：

無線程互斥的情況：

/**
 * @desc: 沒有進行互斥的情況
 * @author: YanMingXin
 * @create: 2021/12/19-18:02
 **/
public class Method0 {

    private int value = 10;

    private void reduce() {
        try {
            while (value == 0) {
                System.out.println("stop...");
                return;
            }
            System.out.println(Thread.currentThread().getName() + "：" + value);
            value--;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void make() {
        ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(3, 5, 3, TimeUnit.SECONDS, new LinkedBlockingDeque<>());
        for (int i = 0; i < 20; i++) {
            poolExecutor.execute(() -> {
                reduce();
            });
        }
    }

    public static void main(String[] args) {
        Method0 methodA = new Method0();
        methodA.make();
    }

}
           

方式一：互斥鎖synchronized

/**
 * @desc: 互斥方式一
 * @author: YanMingXin
 * @create: 2021/12/19-17:48
 **/
public class MethodA {

    private int value = 10;

    private synchronized void reduce() {
        try {
            while (value == 0) {
                System.out.println("stop...");
                return;
            }
            System.out.println(Thread.currentThread().getName() + "：" + value);
            value--;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void make() {
        ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(3, 5, 3, TimeUnit.SECONDS, new LinkedBlockingDeque<>());
        for (int i = 0; i < 20; i++) {
            poolExecutor.execute(() -> {
                reduce();
            });
        }
    }

    public static void main(String[] args) {
        MethodA methodA = new MethodA();
        methodA.make();
    }

}
           

方式二：可重入互斥鎖ReentrantLock

/**
 * @desc: 互斥方式二
 * @author: YanMingXin
 * @create: 2021/12/19-17:50
 **/
public class MethodB {

    private int value = 10;

    private ReentrantLock lock=new ReentrantLock();


    private void reduce(){
        lock.lock();
        try {
            while (value == 0) {
                System.out.println("stop...");
                return;
            }
            System.out.println(Thread.currentThread().getName() + "：" + value);
            value--;
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }

    private void make() {
        ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(3, 5, 3, TimeUnit.SECONDS, new LinkedBlockingDeque<>());
        for (int i = 0; i < 20; i++) {
            poolExecutor.execute(() -> {
                reduce();
            });
        }
    }

    public static void main(String[] args) {
        MethodB methodA = new MethodB();
        methodA.make();
    }

}
           

然後，Java實作線程同步：

無線程同步的情況：

/**
 * @desc: 無線程同步狀态
 * @author: YanMingXin
 * @create: 2021/12/19-17:47
 **/
public class Method0 {

    private int value = 0;

    private static List list = new ArrayList<String>();

    static {
        list = Arrays.asList("1-Insert", "2-Delete", "3-Update", "4-Select");
    }

    private void reduce() {
        try {
            System.out.println(list.get(value));
            value++;
            while (value > 3) {
                System.out.println("stop...");
                return;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void make() {
        ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(
                4,
                4,
                3,
                TimeUnit.SECONDS,
                new LinkedBlockingDeque<>());
        for (int i = 0; i < 4; i++) {
            poolExecutor.execute(() -> {
                reduce();
            });
        }
        poolExecutor.shutdown();
    }

    public static void main(String[] args) {
        Method0 methodA = new Method0();
        methodA.make();
    }

}
           

/**
 * @desc: 線程同步方式一
 * @author: YanMingXin
 * @create: 2021/12/19-17:47
 **/
public class MethodA {

    private int value = 0;

    private static List list = new ArrayList<String>();

    static {
        list = Arrays.asList("1-Insert", "2-Delete", "3-Update", "4-Select");
    }

    private synchronized void reduce() {
        try {
            System.out.println(list.get(value));
            value++;
            while (value > 3) {
                System.out.println("stop...");
                return;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void make() {
        ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(
                4,
                4,
                3,
                TimeUnit.SECONDS,
                new LinkedBlockingDeque<>());
        for (int i = 0; i < 4; i++) {
            poolExecutor.execute(() -> {
                reduce();
            });
        }
        poolExecutor.shutdown();
    }

    public static void main(String[] args) {
        MethodA methodA = new MethodA();
        methodA.make();
    }

}
           

/**
 * @desc: 線程同步方式二
 * @author: YanMingXin
 * @create: 2021/12/19-17:47
 **/
public class MethodA {

    private int value = 0;

    private ReentrantLock lock = new ReentrantLock();

    private static List list = new ArrayList<String>();

    static {
        list = Arrays.asList("1-Insert", "2-Delete", "3-Update", "4-Select");
    }

    private void reduce() {
        lock.lock();
        try {
            System.out.println(list.get(value));
            value++;
            while (value > 3) {
                System.out.println("stop...");
                return;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    private void make() {
        ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(
                4,
                4,
                3,
                TimeUnit.SECONDS,
                new LinkedBlockingDeque<>());
        for (int i = 0; i < 4; i++) {
            poolExecutor.execute(() -> {
                reduce();
            });
        }
        poolExecutor.shutdown();
    }

    public static void main(String[] args) {
        MethodA methodA = new MethodA();
        methodA.make();
    }

}
           

/**
 * @desc: 線程同步方式三
 * @author: YanMingXin
 * @create: 2021/12/19-17:47
 **/
public class MethodA {

    private int value = 0;

    private static List list = new ArrayList<String>();

    static {
        list = Arrays.asList("1-Insert", "2-Delete", "3-Update", "4-Select");
    }

    private void reduce() {
        synchronized (this) {
            try {
                System.out.println(list.get(value));
                value++;
                while (value > 3) {
                    System.out.println("stop...");
                    return;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    private void make() {
        ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(
                4,
                4,
                3,
                TimeUnit.SECONDS,
                new LinkedBlockingDeque<>());
        for (int i = 0; i < 4; i++) {
            poolExecutor.execute(() -> {
                reduce();
            });
        }
        poolExecutor.shutdown();
    }

    public static void main(String[] args) {
        MethodA methodA = new MethodA();
        methodA.make();
    }

}