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NOTE

6.19 ReentrantReadWriteLock

1. What ReentrantReadWriteLock is. 2. ReentrantReadWriteLock categories. 3. References.

JavaCreated Updated 1 min readhistorical

This is a historical learning note and may contain outdated or incomplete understanding.

1. What Is ReentrantReadWriteLock?

ReentrantLock ensures that only one thread at a time can read or write data in the critical section. This means that even if two reader threads are reading data at the same time, ReentrantLock allows only one of them through. What we want, however, is for reads to execute concurrently, while any write causes the other threads to wait. The behavior is shown below:

Can proceed at the same time Read Write
Read √ ×
Write × ×

That is why ReentrantReadWriteLock exists.

2. ReentrantReadWriteLock Categories

3. References

  1. Concurrency Programming (8): Read-Write Locks — From Language Rules to the CPU

    Uses the same counter and counter + ready examples to trace read-write locks from Java language-level rules through the JDK, HotSpot, and x86-64, explaining Atomicity, Visibility, Ordering, and the boundary with Mutex.

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