java volatile

The volatile keyword-Modified shared variable has two main features: 1. Memory visibility for different thread access 2. Prevent reordering Before we talk about memory visibility and ordering, we need to look at the memory model of Java (note the distinction between the JVM memory model) Why do you have a Java memory model? First we know that memory access and

In the last two articles I have introduced some basic communication between the threads, then this article will talk about the volatile keyword related knowledge. This keyword is seldom used in our daily development, and the class under the lock and concurrent packages of the JDK uses this keyword extensively because it has the following two features:1. Ensure memory Visibility 2. Prohibit command reorderingThe next step is to analyze this two-point f

Java Theory and Practice: using Volatile variables correctlyOriginal: http://www.ibm.com/developerworks/cn/java/j-jtp06197.htmlSummarize:The lock provides two main features: Mutual exclusion (mutual exclusion) and visibility (visibility). Mutual exclusion allows only one thread to hold a particular lock at a time, so you can use this attribute to implement a coor

Reprint Please keep the following statementZhaozongSource: https://www.cnblogs.com/zhao-zongsheng/p/9092520.htmlRecently saw the definition of the volatile keyword in the C + + standard, found that the volatile keyword is completely different from Java, C + + volatile for concurrent programming basically does not help.

When studying concurrent programming, it involves the volatile,volatile and the JVM memory model, which is the knowledge of previous learning, and now some forget, as review and learn again. Because the research is shallow, fear of expression is not clear offended the principle, is not here to say volatile principle and JVM memory model, a better explanation

reorder occurs, another thread B that executes concurrently may have taken instance before the object operation has been initialized, but the object may not have been actually initialized by the thread, so this thread is unsafe. Java antecedent principle: 1. Rules of Procedure Order: in a thread, according to the Order of the program code (accurately said to be control flow order), first write first occurrence, after writing occurs. 2. Pipe lock rule

lock addl command is added. This lock is actually a command prefix. It ensures that the Cache Line of the current operation is in the Exclusive State and ensures the order of the commands. This command may be implemented by locking the bus, but if the bus has been locked, it will only consume the Time of the suffix command.In fact, the volatile in Java is implemented by adding a lock add command. Write ag

decorate B with the volatile keyword, the miracle will appear. Note: Here the B is volatile modified volatile Boolean b = false; This is how the process will beAfter adding the volatile keyword modifier to B, thread 1 modifies B, and then immediately updates the value in memory, thread 2 discovers that its copy h

Thread Basics Series (iv) Synchronization of threads 2: notify-wait communication mechanism for threads, and condition condition variablesThread Basics Series (iii) synchronization of Threads: synchronization control, locks and synchronizedThread Basics Series (ii) thread management: Thread state, control, hibernation, Interrupt,yield, etc.Thread Basics Series (a) thread creation and startup: Thread creation and startup, join (), daemon thread, callable task.The key words discussed in this artic

declared as volatile. I'm afraid it's easiest to explain the difference between volatile and synchronized.Volatile is a variable modifier, while synchronized acts on a piece of code or method; Look at the following three-sentence get code: int i1;int Geti1 () {return i1;} volatile int i2;int Geti2 () {return i2;} int i3; synchronized int Geti3 () {return i3;}

This may be the best contrast to the volatile and synchronized effects of the article. Volatile is a variable modifier, and synchronized is a modifier of a method or a block. So we use both of these keywords to specify three simple ways to access variables. int i1; int Geti1 () { return i1; } volatile int i2; int Ge

In Java thread concurrency processing, there is a very big confusion about the use of a keyword volatile, for the use of this keyword, in the multi-threaded concurrent processing can be all right.The Java language is multi-threaded, in order to solve the problem of thread concurrency, the synchronization block synchronized and the

When it comes to volatile, some of the students who have attended the interview are certainly not unfamiliar with it.It is a frequent visitor to the interviewer's mouth, but the usual coding is seldom met (at least, I am).In recent interviews, I have often asked about volatile related issues such as the difference between volatile and sychronized ,

performance is better than synchronized. Volatile can only modify variables, synchronized may modify methods, code blocks volatile not block threads, synchronized block threads volatile ensure data visibility, not guarantee atomicity, Synchronized can guarantee atomicity and can indirectly guarantee visibility, which synchronizes data from public and private mem