AtomicReference refers to an object reference. This reference is a volatile member variable in the AtomicReference instance as below. private volatile V value; get() simply returns the latest value of the variable (as volatiles do in a “happens before” manner).
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How does AtomicReference work in Java?
AtomicReference refers to an object reference. This reference is a volatile member variable in the AtomicReference instance as below. private volatile V value; get() simply returns the latest value of the variable (as volatiles do in a “happens before” manner).
Is AtomicReference thread-safe?
AtomicReference support lock-free thread-safe programming on single variables. There are multiple ways of achieving Thread safety with high level concurrent API. Atomic variables is one of the multiple options.
What is an atomic Integer Java?
An AtomicInteger is used in applications such as atomically incremented counters, and cannot be used as a replacement for an Integer . However, this class does extend Number to allow uniform access by tools and utilities that deal with numerically-based classes.
What is lazySet?
To summarize: lazySet is a weak volatile write in the sense that it acts as a store-store and not a store-load fence. This boils down to lazySet being JIT compiled to a MOV instruction that cannot be re-ordered by the compiler rather then the significantly more expensive instruction used for a volatile set.
Is AtomicReference volatile?
There are several differences and tradeoffs: Using an AtomicReference get/set has the same JMM semantics as a volatile field(as the javadoc states), but the AtomicReference is a wrapper around a reference, so any access to the field involves a further pointer chase.
Why do we use atomic Integer?
The primary use of AtomicInteger is when you are in a multithreaded context and you need to perform thread safe operations on an integer without using synchronized . The assignation and retrieval on the primitive type int are already atomic but AtomicInteger comes with many operations which are not atomic on int .
Why do we need atomic Integer?
Conclusion. As discussed above, the primary use of AtomicInteger is when we are in multi-threaded context and we need to perform atomic operations on an int value without using synchronized keyword. Using the AtomicInteger is equally faster and more readable than performing the same using synchronization.
What is difference between volatile and atomic?
Volatile and Atomic are two different concepts. Volatile ensures, that a certain, expected (memory) state is true across different threads, while Atomics ensure that operation on variables are performed atomically.
How does volatile work in Java?
Since volatile keyword in Java only synchronizes the value of one variable between Thread memory and “ main ” memory while synchronized synchronizes the value of all variable between thread memory and “ main ” memory and locks and releases a monitor to boot.
How is atomic Integer implemented?
AtomicInteger uses combination of volatile & CAS (compare and swap) to achieve thread-safety for Integer Counter. It is non-blocking in nature and thus highly usable in writing high throughput concurrent data structures that can be used under low to moderate thread contention.