java volatile

Let's take a look at what this keyword means:volatile [? V?l?ta?l]Adj. variable, unstable;In translation, volatile means that the keyword is highly susceptible to change.Volatile is the most lightweight concurrency synchronization mechanism in the Java language. This keyword has the following two functions:1. Any modification to volatile variables, other threads

volatile definition The Java programming language allows threads to access shared variables, and in order to ensure that shared variables are updated accurately and consistently, threads should ensure that the variable is obtained separately through exclusive locks. The Java language provides volatile, which in some c

IntroductionWhen it comes to the volatile keyword, most developers have a certain understanding, which can be said to be a very familiar and very unfamiliar keyword for developers. The equivalent of lightweight synchronized, also known as lightweight locks, is less expensive than synchronized, with visibility, ordering, and partial atomicity, which is a very important keyword in Java concurrency. In this ar

Volatile allows variables to be taken from main memory each time they are used. Instead of "working memory" from each thread.Volatile has the "visibility" of the synchronized keyword, but there is no "concurrency correctness" of the synchronized keyword, which means that the ordering of thread execution is not guaranteed.In other words, the volatile variable is the most recent value of the current

Introduction: Synchronized and volatile play an important role in multithreaded concurrent programming, and volatile is a lightweight synchronizedthat guarantees the "visibility" of shared variables in multiprocessor development.Visibility means that when a thread modifies a shared variable, another thread can read the modified value.official definition of volatileThe definition of

Java concurrent programming: volatile keyword ParsingThe volatile keyword may have been heard or used by many friends. Before Java 5, it was a controversial keyword, because using it in a program often leads to unexpected results. After Java 5, the

We learned from the previous chapter that synchronized is a heavyweight lock, and although the JVM has done a lot of optimizations for it, the volatile described below is a lightweight synchronized. If a variable uses volatile, it is less expensive than using synchronized because it does not cause thread context switching and scheduling. The Java language Specifi

Used in multi-threading, synchronous variables. thread to improve efficiency, a member variable (such as a) copy a copy (such as b), the thread of access to a actually access is B. Synchronization of A and B occurs only in certain actions. Thus there is a and B inconsistency. Volatile is used to avoid this situation. Volatile tells the JVM that the variable it modifies does not keep the copy and accesses th

Used in multi-threading, synchronous variables. thread to improve efficiency, a member variable (such as a) copy a copy (such as b), the thread of access to a actually access is B. Synchronization of A and B occurs only in certain actions. Thus there is a and B inconsistency. Volatile is used to avoid this situation. Volatile tells the JVM that the variable it modifies does not keep the copy and accesses th

Used in multi-threading, synchronous variables. Thread to improve efficiency, a member variable (such as a) copy a copy (such as b), the thread of access to a actually access is B. Synchronization of A and B occurs only in certain actions. Thus there is a and B inconsistency. Volatile is used to avoid this Situation. Volatile tells the JVM that the variable it modifies does not keep the copy and accesses th

sending thread passing the message directly to the receiving thread.Because the execution order is done by the concurrency mechanism, there is no need for the programmer to add additional synchronization mechanisms, but to declare the code that the message sends and receives. Java Multithreaded memory model:All threads share a piece of memory that is used to store shared variables;In addition, each thread has its own storage space, storing

Let's talk about volatile and javavolatile in java. Memory visibility Pay attention to compound operations Solve the atomic problem of num ++ operations Disable Command Re-sorting SummaryMemory visibility Volatile is a lightweight synchronization mechanism provided by Java. It also plays an important role in concurrent

One, the visibility of the volatile keywordTo understand the volatile keyword, first understand the Java memory model, the Java memory model is abstracted as follows:Can be seen:① each thread has its own local memory space-the line stacks space??? When a thread executes, it reads the variable from main memory to the th

Used in multi-threading, synchronous variables. thread to improve efficiency, a member variable (such as a) copy a copy (such as b), the thread of access to a actually access is B. Synchronization of A and B occurs only in certain actions. Thus there is a and B inconsistency. Volatile is used to avoid this situation. Volatile tells the JVM that the variable it modifies does not keep the copy and accesses th

(); Attemptlocking.timed (); } }Lock mutex execution principle is implemented by Aqs Synchronizer. Please see AQS details lock visibility is also AQS, specifically the state variable Happen-before rules. How Aqs (or JDK locks) ensure visibility For more in-depth understanding please read: Java concurrent Programming--Nine AbstractqueuedsynchronizerAqs detailed Java Concurrent Programming--reentrantloc

The volatile variable in the Java language can be viewed as a "lighter synchronized", and the volatile variable requires less coding and less run-time overhead than the synchronized block, but the functionality it can achieve is only Part of the synchronized. This article describes several patterns that effectively use volati