java concurrency in practice

The Java.util.concurrent package (J.U.C) after Java5 is the work of the world-class concurrent Master Doug Lea, which mainly implements The corresponding atomic class of Integer/long in atomic package is mainly based on CAS; Some of the same steps, including Lock,countdownlatch,semaphore,futuretask, are based on the Abstractqueuedsynchronizer class; About the executors class of thread execution, etc.; Some concurrent collection classes, such as Concurrenthashmap,concurrentl

In general development, I often see many students in the Java Concurrent development model will only use some basic methods. Like volatile,synchronized. High-level contracts such as lock and atomic are not often used by many people. I think most of the reasons are due to the nature of the principle. In the busy development work, who will be able to accurately grasp and use the correct concurrency model?So r

Previous blog "Dead java Concurrency"-in-depth analysis of the volatile implementation principle has described the characteristics of volatile: volatile visibility; For a volatile read, you can always see the final write of this variable; volatile atomicity; volatile is atomic for a single read/write (32-bit long, Double), except for composite operations, such as i++; A "memory barrier" is

) {e.printstacktrace (); } System.out.println ("Test ends ..."); } } } classMyThreadextendsThread { Public voidrun () {Sync sync=NewSync (); Sync.test (); } } Public classMain { Public Static voidMain (string[] args) { for(inti = 0; I ) {thread thread=NewMyThread (); Thread.Start (); } } } Operation Result:Test start:Test end:Test start:Test end:Test start:Test end:The above code uses synchronized (Sync.class) to achieve the effect of global locking.Finally, th

[Practical Java high concurrency Program Design 7] Let threads help each other-Implementation of SynchronousQueue and synchronousqueue [Practice: Java high concurrency Program Design 1] pointer in Java: Unsafe class [

ThreadPoolExecutor thread execution service for Java concurrency and java multi-thread concurrent execution 1 package com. thread. test. thread; 2 3 import java. util. concurrent. executorService; 4 import java. util. concurrent. define blockingqueue; 5 import

Mainly talk about the performance of the lock and some other theoretical knowledge, the main source of the content is "Java Concurrency in Practice", combined with their own understanding and practical application of the lock mechanism to a small summary.One of the first things to emphasize is that all locks (including built-in locks and advanced locks) are perfo

Mainly talk about the performance of the lock and some other theoretical knowledge, the main source of the content is "Java Concurrency in Practice", combined with their own understanding and practical application of the lock mechanism to a small summary.One of the first things to emphasize is that all locks (including built-in locks and advanced locks) are perfo

is the "Practical Java High concurrency program design," The 4th chapter of several points.If you have a unhesitatingly pursuit of technology, you should also be particularly concerned about the implementation of Compareandset () in the Incrementandget () method. Now, let's take a closer look at it! Public Final Boolean compareandset (intint update) { Returnunsafe.compareandswapint (This, Valueoffset, e

Multithreading and concurrency issues are among the questions that interviewers prefer to ask in a Java technology interview. Here, the most important questions are listed from the interview point of view, but you should still have a solid grasp of the basics of Java multithreading to match the problems you encounter later. ( proof Note: Very much agree with this

lock: When multiple threads are waiting for the same lock, they must be queued in the order in which they are requested, while non-fair locks do not guarantee this, and any thread that waits for a lock has a chance to acquire a lock when the lock is released. Synchronized locks are not fair when locked, Reentrantlock is also an unfair lock by default, but you can require a fair lock by constructing method Reentrantlock (ture).3. Locks can bind multiple conditions: The Reentrantlock object can b

downgrade, follow the acquisition of write lock, read lock and then release the order of the write lock, write lock can be downgraded to read lock. Locksupport provides a park unpark static method of blocking, waking. Condition Interface : Any Java object, has a set of monitor methods, including, wait() and notify() so on, these methods and synchronized keyword Mates can implement the wait/notification mode, the Condition interface also provides

, but for 64-bit data types long and double, A loose rule is defined in the model that allows the virtual machine to divide the read and write operations of 64-bit data that are not volatile-modified into two 32-bit operations. Thus, if there are multiple threads sharing a long or double type of variable that is not declared volatile, and both are read and modified, some threads may read a value that is neither the original nor the other thread to modify the value that is worth representing the

Java Concurrency structureOriginal link: http://gee.cs.oswego.edu/dl/cpj/mechanics.htmlContent Thread Synchronous Monitor ThreadA thread is a sequence of calls that are executed independently, and the threads of the same process share some system resources (such as file handles) at the same time to access the object resources (memory resources) created by the same process. The Java.lan

. There is more discussion of this content in hunger and equity.Call Unlock () in the Finally statementIt is important to call unlock () in the finally statement if lock is used to protect the critical section and the critical section is likely to throw an exception. This ensures that the lock object can be unlocked so that other threads can continue to lock it. The following is an example:Lock.lock (); Try { //docritical sections code, //which may throw exception finally { lock.unlock

In the daily Java code development process, it is inevitable to have multi-threaded requirements, mastering the Java multithreading and concurrency mechanism is the Java programmer to write more robust and efficient code base. I find the domestic published on the Java Multi-

Java concurrency: thread pool, saturation policy, customization, expansion, java thread I. Preface When we need to use a thread, we can create a new thread and explicitly call the start () method of the thread. This is very easy to implement, but there are defects in some scenarios: if you need to execute multiple tasks at the same time (that is, the number of co

The following information is transferred from http://tutorials.jenkov.com/java-concurrency/volatile.html (using Google Translate):The Java volatile keyword is used to mark Java variables as "stored in primary storage". More precisely, this means that each read volatile variable is read from the main memory of the compu

Java Concurrency: Lock framework Detailed Summary: We already know that synchronized is the Java keyword, is the built-in features of Java, in the JVM level to achieve the synchronization of the critical resources of mutually exclusive access, but the synchronized granularity is somewhat large, in dealing with the act

A lot of information on the web when describing the Java memory model, will introduce a main memory, and then each worker thread has its own working memory. The data is in main memory and there is a copy in the working RAM. There is a variety of atomic operations between working memory and main storage to synchronize. The following figure comes from this blog But because of the evolving Java version, th