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.
What is weakCompareAndSet?
The weakCompareAndSet javadoc explains it thus: Atomically sets the value to the given updated value if the current value == the expected value. May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to compareAndSet.
What is AtomicReference Java?
atomic. AtomicReference class provides operations on underlying object reference that can be read and written atomically, and also contains advanced atomic operations. AtomicReference supports atomic operations on underlying object reference variable.
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.
Is AtomicReference synchronized?
The synchronized approach is a more general purpose mechanism; with the synchronized block you can group together multiple assignments much more easily, where with atomic references it’s much more involved.
Is AtomicReference thread-safe?
Why do we use AtomicReference?
When do we use AtomicReference? AtomicReference is flexible way to update the variable value atomically without use of synchronization. AtomicReference support lock-free thread-safe programming on single variables.
What is an AtomicReference?
The AtomicReference class provides an object reference variable which can be read and written atomically. By atomic is meant that multiple threads attempting to change the same AtomicReference (e.g. with a compare-and-swap operation) will not make the AtomicReference end up in an inconsistent state.
What is compareAndSet?
compareAndSet() is an inbuilt method in java that sets the value to the passed value in the parameter if the current value is equal to the expected value which is also passed in the parameter. The function returns a boolean value which gives us an idea if the update was done or not.
Where do you use AtomicReference?
An atomic reference is ideal to use when you need to share and change the state of an immutable object between multiple threads. That is a super dense statement so I will break it down a bit. First, an immutable object is an object that is effectively not changed after construction.
What is AtomicBoolean?
atomic. AtomicBoolean class provides operations on underlying boolean value that can be read and written atomically, and also contains advanced atomic operations. AtomicBoolean supports atomic operations on underlying boolean variable. It have get and set methods that work like reads and writes on volatile variables.
How does swap and compare work in Java?
Compare and swap is a technique used when designing concurrent algorithms. The approach is to compare the actual value of the variable to the expected value of the variable and if the actual value matches the expected value, then swap the actual value of the variable for the new value passed in.
Is AtomicReference a volatile variable?
If you look at the code in AtomicReference, it uses a volatie variable for object storage. So, obviously if you are going to just use get () and set () on AtomicReference it is like using a volatile variable. But as other readers commented, AtomicReference provides additional CAS semantics.
What is the use of AtomicReference get ()?
This reference is a volatile member variable in the AtomicReference instance as below. get () simply returns the latest value of the variable (as volatiles do in a “happens before” manner).
What is the use of AtomicReference variable in thread based environment?
Returns the String representation of the current value. Atomically sets the value to the given updated value if the current value == the expected value. The following TestThread program shows usage of AtomicReference variable in thread based environment. This will produce the following result.
How does the unsafe method of AtomicReference work?
This method call of unsafe invokes the native call, which invokes a single instruction to the processor. “expect” and “update” each reference an object. If and only if the AtomicReference instance member variable “value” refers to the same object is referred to by “expect”, “update” is assigned to this instance variable now, and “true” is returned.