RedisLockRegistry expireAfter doesn't work

[hero-zhanghao]

In what version(s) of Spring Integration are you seeing this issue?

For example:

5.3.1.RELEASE

Describe the bug

I create a RedisLockRegistry and set expireAfter to 1000L .

After obtain the Lock object, invoke tryLock (3000, TimeUnit.MILLISECONDS) method.

Print 'lock-test' to sleep 2000L milliseconds, then call unlock.

When two threads come in at the same time, the second thread should get the lock one second after the first thread,

However, what observe now is that the two threads are always two seconds apart, seemingly unaffected by the expireAfter field.

thanks

To Reproduce

2020-10-10 15:40:46,063 [boundedElastic-2] INFO c.e.s.raffle.utils.RedisLockUtils.lambda$null$1(RedisLockUtils.java:65) - try obtain lock

2020-10-10 15:40:46,066 [boundedElastic-2] INFO c.e.s.raffle.utils.RedisLockUtils.lambda$null$1(RedisLockUtils.java:68) - Got the distributed lock and executing , key = test , time = 2020-10-10T15:40:46.066

lock-test

2020-10-10 15:40:47,006 [boundedElastic-1] INFO c.e.s.raffle.utils.RedisLockUtils.lambda$null$1(RedisLockUtils.java:65) - try obtain lock

2020-10-10 15:40:48,069 [boundedElastic-1] INFO c.e.s.raffle.utils.RedisLockUtils.lambda$null$1(RedisLockUtils.java:68) - Got the distributed lock and executing , key = test , time = 2020-10-10T15:40:48.069

lock-test

[hero-zhanghao]

Also, I find that if the unlock method is not called, the lock cannot be obtained again.

This seems to have been affected by ReentrantLock

[artembilan]

Would be great to have some code to play with.

There is no expire option for the ReentrantLock and we definitely can't unlock it from non-owner. So, your concern is not clear: as long as you hold a lock in one thread, it cannot be obtained from another one even if its distributed instance has been expired in Redis.

Thanks for understanding.

[hero-zhanghao]

But most of the time, we need to be able to release locks automatically after the lock holder has held them for a certain amount of time, which is one of the reasons for using Redis.

Maybe we can choose whether or not we need ReentrantLock

[artembilan]

Well, that's not how locks are designed and you definitely can't release the lock if you are not a holder of it.
It even doesn't matter if we don't use ReentrantLock just because the holder may not know (or just doesn't care) if lock has been expired already or not. You even may release the lock somehow, but your main flow may not know about that at all and would continue to perform its logic. That's why it is recommended to design locks logic carefully, so you have some way to release lock safely even for failure reason. Since ReentrantLock is like that we can't release it from outside, so we have designed all the distributed locks the same way. The point of the expireAfter is more about a shared persistent store to not hold a record when the owner of the lock dies accidentally.

We have a feature request like this: https://jira.spring.io/browse/INT-4286, so probably we can have some compromise eventually. But still: I'm against unlocking outside from the lock owner...

See also this discussion: #2894

[hero-zhanghao]

Ok, thank you for your answer