交叉锁引起程序死锁

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已于 2022-03-05 09:41:31 修改 · 639 阅读

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#Java

于 2022-03-05 09:41:21 首次发布

一点睛

交叉锁不仅自己写的代码会出现，如果使用某个框架或者开源库，由于对源码 API 的不熟悉，很有可能也会引起死锁，这种情况出现死锁后，排查的困难则要高于前者，所以在使用框架或者开源库的时候要做到了如指掌。

二代码

package concurrent;

public class DeadLock {
    private final Object mutexRead = new Object();
    private final Object mutexWrite = new Object();

    public void read() {
        synchronized (mutexRead) {
            System.out.println(Thread.currentThread().getName() + " get READ lock");
            synchronized (mutexWrite) {
                System.out.println(Thread.currentThread().getName() + " get write lock");
            }
            System.out.println(Thread.currentThread().getName() + " release write lock");
        }
        System.out.println(Thread.currentThread().getName() + " release READ lock");
    }

    public void write() {
        synchronized (mutexWrite) {
            System.out.println(Thread.currentThread().getName() + " get write lock");
            synchronized (mutexRead) {
                System.out.println(Thread.currentThread().getName() + " get READ lock");
            }
            System.out.println(Thread.currentThread().getName() + " release READ lock");
        }
        System.out.println(Thread.currentThread().getName() + " release write lock");
    }

    public static void main(String[] args) {
        final DeadLock deadLock = new DeadLock();
        new Thread(() -> {
            while (true) {
                deadLock.read();
            }
        }, "READ-THREAD").start();

        new Thread(() -> {
            while (true) {
                deadLock.write();
            }
        }, "WRITE-THREAD").start();
    }
}

三测试

READ-THREAD get READ lock
READ-THREAD get write lock
READ-THREAD release write lock
READ-THREAD release READ lock
READ-THREAD get READ lock
READ-THREAD get write lock
READ-THREAD release write lock
READ-THREAD release READ lock
READ-THREAD get READ lock
READ-THREAD get write lock
READ-THREAD