Hazelcast Trylock 和多次通话

Question

I ran into the following issue:

We have a multipart Process P with two steps ( s1 and s2 ). The process is implemented, that in s1 a lock is acquired - but not released. In s2 the lock is required again (?) and after s2 is done, the lock is released again.

From the documentation :

Locks are re-entrant: the same thread can lock multiple times on the same lock. Note that for other threads to be able to require this lock, the owner of the lock must call unlock as many times as the owner called lock.

If I understand this correctly, this means, if I call s1 for the first time, the lock is acquired by a Thread from the threadpool, say Tx . Since the lock is not released after the request, the thread goes back to the pool. If a second request comes in, the lock is in use (by Tx ). But if I start enough requests, at some point in time, I will get Tx from the pool again, and I am able to successfully tryLock the same lock as before again?

Is this right? This means, the lock is not exclusive for it's lifetime, or only insofar exclusive, that it is exclusively bound to one thread.

Answer 1

A lock has the concept of lock ownership; which means that there is a particular thread is owning a lock. It also means that only this thread needs to release this lock.

So your usecase where thread1 acquires and thread2 releases, will not work with a lock (no matter if it a hz lock or a regular juclReentrantLock).

You might want to have a look at the ISemaphore and initialise it with 1, so you can create a binary semaphore. This will allow you to acquire a 'lock' in 1 thread and release the 'lock' in another.

However, it will not deal with reentrant behavior. But will deadlock instead.