Redis的Redisson库的API方法.unlock()没有释放锁，在尝试使用相同实例解锁。

huangapple
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英文:

Redis's Redisson's API method .unlock() is not releasing the lock, trying from the same instance

问题

我在我的Java应用程序中创建了一个单例的Redisson实例，我使用它来与Redis服务器进行通信。
现在，使用这个Redisson实例，我正在获取一个锁，在完成一些任务后，我会释放它。但是在调用unlock方法之后，我仍然看到Redis仍然持有该锁，其他线程无法获取该锁。
以下是我正在使用的代码片段：

  1. class RedisInstance
  2. {
  3.    static RedisInstance ins;
  4.    private RedisInstance()
  5.      {
  6.        ins = new RedisInstance();
  7.      }
  8.    public static RedisInstance getInstance()
  9.      {
  10.        return ins;
  11.      }
  13.    //获取锁：
  14.    public boolean acquireLock(String lockKey)
  15. 	 {
  16. 		 RLock redisLock = getRedisClient().getLock(lockKey);
  17. 		 boolean isLockFree;
  18. 		 try 
  19. 		 {
  20. 			isLockFree = redisLock.tryLock(lockAcquistionTimeLimit, TimeUnit.SECONDS);
  21. 			if(isLockFree)
  22. 			{
  23. 				 redisLock.lock();
  24. 				 logger.info("锁已获取：{}", lockKey);
  25. 				 return true;
  26. 			}
  27. 		 } 
  28. 		 catch (InterruptedException e) 
  29. 		 {
  30. 			 logger.error("在获取Redis锁时发生异常：{}", e, lockKey);
  31. 		 }
  32. 		 
  33. 		 return false;
  34. 	 }
  36.    //释放锁：
  37.    public void unlock(String lockKey)
  38. 	 {
  39. 		 RLock redisLock = getRedisClient().getLock(lockKey);
  40. 		 redisLock.unlock();
  41. 		 logger.debug("Redis是否已锁定：" + redisLock.isLocked());
  42. 		 logger.info("锁已释放：{}", lockKey);
  43. 	 }
  44. }
  1. class A
  2. {
  3.    RedisIns ins = RedisInstance.getInstance();
  4.    public void run() 
  5.         {
  6. 		if(ins.acquireLock(lockKey))
  7. 				{
  8. 					try 
  9. 					{
  10. 						//进行一些处理，耗时不到一秒		
  11.                     }
  12. 					catch(Exception e)
  13. 					{
  14. 						
  15. 					}
  16. 					finally
  17. 					{
  18. 						ins.unlock(lockKey);
  19. 					}
  20. 				}
  21. 	     }
  23.    //在我的主方法中：
  24.    public static void main(String args[])
  25.    {
  26.      A a = new A();
  27.      A b = new A();
  28.      Thread t1 = new Thread(a);
  29.      Thread t2 = new Thread(b);
  30.      t1.start();
  31.      Thread.sleep(5000); //仅为模拟，假设t1在t2开始之前完成
  32.      t2.start();
  33.    }
  34. }

在t1调用ins.unlock(lockKey);之后，日志logger.debug("Redis是否已锁定：" + redisLock.isLocked());显示为：true，且t2无法获取锁。

但是，如果我将redisLock.unlock();替换为redisLock.forceUnlock();，一切都按预期工作。不知道为什么unlock()无法释放锁，而forceUnlock()可以。

英文:

I have created singleton redisson instance in my Java application, which I am using to communicate to redis servers.
Now using this redisson instance, I am acquiring a lock which after getting some task done, I am releasing. But after calling unlock method, I still see redis have the lock and other threads are unable to acquire the lock.
Below is the code snippet, I am using:

  1. class RedisInstance
  2. {
  3.    static RedisInstance ins;
  4.    private RedisInstance()
  5.      {
  6.        ins = new RedisInstance();
  7.      }
  8.    public static RedisInstance getInstance()
  9.      {
  10.        return ins;
  11.      }
  12.    //Acquire the lock:   
  13.    public boolean acquireLock(String lockKey)
  14. 	 {
  15. 		 RLock redisLock = getRedisClient().getLock(lockKey);
  16. 		 boolean isLockFree;
  17. 		 try 
  18. 		 {
  19. 			isLockFree = redisLock.tryLock(lockAcquistionTimeLimit, TimeUnit.SECONDS);
  20. 			if(isLockFree)
  21. 			{
  22. 				 redisLock.lock();
  23. 				 logger.info("lock acquired for: {}", lockKey);
  24. 				 return true;
  25. 			}
  26. 		 } 
  27. 		 catch (InterruptedException e) 
  28. 		 {
  29. 			 logger.error("Got exception {} in acquiring Redis Lock for: {}" , e, lockKey);
  30. 		 }
  31. 		 
  32. 		 return false;
  33. 	 }
  36.    //Release the lock:
  37.    public void unlock(String lockKey)
  38. 	 {
  39. 		 RLock redisLock = getRedisClient().getLock(lockKey);
  40. 		 redisLock.unlock();
  41. 		 logger.debug("IS redis locked "+redisLock.isLocked());
  42. 		 logger.info("lock released for: {}", lockKey);
  43. 	 }
  44. }
  1. class A
  2. {
  3.    RedisIns ins = RedisInstance.getInstance();
  4.    public void run() 
  5.         {
  6. 		if(ins.acquireLock(lockKey))
  7. 				{
  8. 					try 
  9. 					{
  10. 						//do some processing takes less than a second		
  11.                     }
  12. 					catch(Exception e)
  13. 					{
  14. 						
  15. 					}
  16. 					finally
  17. 					{
  18. 						ins.unlock(lockKey);
  19. 					}
  20. 				}
  21. 	     }
  22.    //In my main method:
  23.    public static void main(String args[])
  24.    {
  25.      A a = new A();
  26.      A b = new A();
  27.      Thread t1 = new Thread(a);
  28.      Thread t2 = new Thread(b);
  29.      t1.start();
  30.      Thread.sleep(5000); //just to mock, lets say t1 finishes before t2 starts
  31.      t2.start();
  32.    }
  33. }

After t1 calls ins.unlock(lockKey);, the log logger.debug("IS redis locked "+redisLock.isLocked()); says: true and t2 is unable to acquire the lock.

But if I replace redisLock.unlock(); with redisLock.forceUnlock(); everything is working as expected.
Dont know why unlock() is unable to release the lock forceUnlock() is able to do it.

答案1

得分: 1

tryLock如果成功获取了锁，则返回true。因此，在此之后调用lock是不必要的，我认为这可能是您问题的原因。实现可能期望锁定/解锁成对出现，而在您的情况下，lock的次数比unlock多一个。

英文:

tryLock returns true if it acquired the lock. So calling lock after is unnecessary, and I think it may be the cause of your problem. The implementation probably expects an even number of lock/unlock and in you case you have one more lock than unlock.

huangapple
  • 本文由 发表于 2020年9月11日 09:40:25
  • 转载请务必保留本文链接：https://go.coder-hub.com/63839691.html
  • java
  • redis
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