1.现在错误的用法:
RLock lock = redisson.getLock(String.format(LOCK_KEY, 2));
try {
if (lock.tryLock()) {
//处理
logger.info("aaaaaaaaaaaaaaaaaa");
} catch(Exception e) {
//处理异常
} finally {
if (lock.isLocked()) {
lock.unlock();
}
}
测试实例:
TwoThread.java
public class TwoThread implements Runnable {
private RedissonClient redisson;
public TwoThread(RedissonClient redisson) {
this.redisson = redisson;
}
private Logger logger = LogManager.getLogger(getClass());
private String REWARD_CARD_LOCK_KEY = "444:lock:%d";
public void run() {
RLock lock = redisson.getLock(String.format(REWARD_CARD_LOCK_KEY, 2));
logger.info("thread---{}, lock:{}",Thread.currentThread().getId(), lock);
try {
if (lock.tryLock()) {
logger.info("tryLock thread---{}, lock:{}",Thread.currentThread().getId(),lock);
logger.info("aaaaaaaaaaaaaaaaaa");
}
} finally {
boolean locked = lock.isLocked();
logger.info("thread---{},lock:{},locked:{}",Thread.currentThread().getId(),lock,locked);
if (locked) {
logger.info("thread unlock---{}, lock:{}",Thread.currentThread().getId(),lock);
lock.unlock();
}
}
}
测试类:
Thread one = new Thread(new TwoThread(redisson));
Thread two = new Thread(new TwoThread(redisson));
Thread three = new Thread(new TwoThread(redisson));
Thread four = new Thread(new TwoThread(redisson));
one.start();
two.start();
three.start();
four.start();
打印结果:
thread---111, lock:org.redisson.RedissonLock@1cb2393f
thread---112, lock:org.redisson.RedissonLock@70feb82b
thread---114, lock:org.redisson.RedissonLock@50384a5d
thread---113, lock:org.redisson.RedissonLock@42232129
thread---111,lock:org.redisson.RedissonLock@1cb2393f,locked:true
aaaaaaaaaaaaaaaaaa
thread---113,lock:org.redisson.RedissonLock@42232129,locked:true
thread---112,lock:org.redisson.RedissonLock@70feb82b,locked:true
thread unlock---111, lock:org.redisson.RedissonLock@1cb2393f
thread---114,lock:org.redisson.RedissonLock@50384a5d,locked:true
thread unlock---114, lock:org.redisson.RedissonLock@50384a5d
thread unlock---113, lock:org.redisson.RedissonLock@42232129
thread unlock---112, lock:org.redisson.RedissonLock@70feb82b
Exception in thread "Thread-20" Exception in thread "Thread-19" java.lang.IllegalMonitorStateException: attempt to unlock lock, not locked by current thread by node id: 54882863-3389-40e7-ba4d-58ecae0a7155 thread-id: 114
at org.redisson.RedissonLock.unlock(RedissonLock.java:367)
at xx.TwoThread.run(TwoThread.java:36)
at java.lang.Thread.run(Thread.java:745)
java.lang.IllegalMonitorStateException: attempt to unlock lock, not locked by current thread by node id: 54882863-3389-40e7-ba4d-58ecae0a7155 thread-id: 113
at org.redisson.RedissonLock.unlock(RedissonLock.java:367)
at xx.TwoThread.run(TwoThread.java:36)
at java.lang.Thread.run(Thread.java:745)
尝试去解锁,但是没有被当前线程锁住。
boolean locked = lock.isLocked()为什么一直返回true，查看源码,只要这个锁被任意一个线程锁,就会返回true
/**
* Checks if this lock locked by any thread
*
* @return <code>true</code> if locked otherwise <code>false</code>
*/
boolean isLocked();
所以,在finally里面 没有被锁就解锁,肯定会报错的。
2.tryLock正确用法:
RLock lock = redisson.getLock(String.format(REWARD_CARD_LOCK_KEY, 2));
try {
//尝试加锁，最多等待10秒，上锁以后10秒自动解锁
if (lock.tryLock(10,10, TimeUnit.SECONDS)) {
try {
//处理
logger.info("tryLock thread---{}, lock:{}", Thread.currentThread().getId(), lock);
} catch (Exception e) {
} finally {
//解锁
lock.unlock();
}
}
} catch (InterruptedException e) {
//处理
//保留中断发生的证据，以便调用栈中更高层的代码能知道中断，并对中断作出响应
Thread.currentThread().interrupt();
}
关于处理InterruptedException,文档参考:
https://www.ibm.com/developerworks/cn/java/j-jtp05236.html
需要恢复中断状态场景的一个例子,方便理解:
https://www.cnblogs.com/softidea/p/4413374.html
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原文链接：https://blog.csdn.net/qq_24664619/article/details/103879692