How to use lock-free technology in Java
This article introduces the knowledge of "how to use lock-free technology in Java". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!
1. Atomic tool class
In JDK 1.8, the classes under the java.util.concurrent.atomic package are all atomic classes, and atomic classes are all implemented based on sun.misc.Unsafe.
In order to solve the concurrency problem, CPU provides CAS instruction, full name Compare And Swap, that is, compare and interact.
The CAS instruction requires three parameters, variables, comparison values, and new values. Update the variable to the new value only when the current value of the variable is equal to the comparison value
CAS is a CPU instruction that is guaranteed atomicity at the CPU hardware level
The atoms in the java.util.concurrent.atomic package are divided into: atomic basic data type, atomic object reference type, atomic array, atomic object attribute updater and atomic accumulator.
Atomic basic data types: AtomicBoolean, AtomicInteger, AtomicLong
Atomic object reference types: AtomicReference, AtomicStampedReference, AtomicMarkableReference
Atomic arrays: AtomicIntegerArray, AtomicLongArray, AtomicReferenceArray
Atomic object property updates: AtomicIntegerFieldUpdater, AtomicLongFieldUpdater, AtomicReferenceFieldUpdater
Atomic accumulator: DoubleAccumulator, DoubleAdder, LongAccumulator, LongAdder
Modify the class that we tested for atomicity problems earlier, using a simple example of AtomicInteger
Package constxiong.concurrency.a026; import java.util.concurrent.atomic.AtomicInteger; / * Test atomic class AtomicInteger * * @ author ConstXiong * / public class TestAtomicInteger {/ / count variable static volatile AtomicInteger count = new AtomicInteger (0); public static void main (String [] args) throws InterruptedException {/ / Thread 1 adds 10000 Thread T1 = new Thread (())-> {for (int j = 0; j {for (int j = 0; j)
