java synchronized method

(){ //............ Synchronized(B ){ //......... } //........ } } In this case, the block lock is implemented. The locked object is variable A or variable B. (Note that both A and B are non-static.) If there is a class instance object: demo = new demo2 (). There are two other threads: thread1 and thread2, both of which call the demo object. At the same time, if thread1 calls the demo. m1 (), then thread2 can

Look at the API documentation to introduce several methods:A multi-threaded upgrade solution is available in JDK1.5:Features: 1. Replace the sync synchronized display with lock2. Interface Condition:condition replaces the object monitor method (Wait, notify, Notifyall), respectively, with await (), signal () (wakes up a waiting thread), Signalal L () wakes up multiple threads. A lock can bind multiple condi

Synchronized in multi-threading should be the most we use, and many people will call it a heavyweight lock. Each object in Java can be used as a lock. It is shown in the following three forms.For the normal synchronization method, the lock is the current instance object.Book class Books {private int id;//book idprivate String name;//book name private int number;/

Http://www.infoq.com/cn/articles/java-memory-model-5 deep understanding of the Java Memory Model (v)--lock Http://www.ibm.com/developerworks/cn/java/j-jtp10264/Java Theory and Practice: a more flexible and scalable locking mechanism in JDK 5.0 http://blog.csdn.net/ghsau/article/details/7481142 1,

Record the pitfalls caused by the synchronized lock string and then talk about the Java string, synchronizedjava Problem description The business has a requirement. I will describe the problem as follows: Access a foreign website through the proxy IP address N, each IP address corresponds to a fixed website n cookie, COOKIE has a failure time.In concurrency, there is a certain policy to get the IP address.

Synchronized usage based on java, using ynchronized First, reference: http://www.cnblogs.com/devinzhang/archive/2011/12/14/2287675.html PS: The reference article is very long, but the content is very rich. If you are a beginner, you must read it with patience. Second, my personal summary: The role of the synchronized keyword: 1. In all the

to focus on the zookeeper is not changed to monitor mode)Synchronized keywords in JavaSo let's go back to Java the synchronized key words, if you don't understand the above behavior and synchronized the relationship you can continue to look backwards.synchronizedWhat exactly is locked, locked is a piece of memory, we

ToString () method does not have some understanding of concurrency: how to ensure that multithreading is a code block in the serial code block synchronized the issue of the problem, is simply impossible to solve, even can say how to do the analysis do not know.Therefore, and do not feel that the JVM, JDK source code underlying implementation of the principle of what is useless, on the contrary, these are t

same time by one thread. Use of the 2.synchronized keyword To lock a given object by locking it into a synchronized code block to obtain a lock on a given object Direct action on an instance method: the equivalent of locking the current instance into a synchronized code block to obtain the current instance's lock (

Http://www.infoq.com/cn/articles/java-memory-model-5 in-depth understanding of Java memory Model (v)--lockHttp://www.ibm.com/developerworks/cn/java/j-jtp10264/Java Theory and Practice: a more flexible and scalable locking mechanism in JDK 5.0http://blog.csdn.net/ghsau/article/details/74811421, synchronizedDeclaring a b

Try to implement the Java synchronized keyword in C ++. A powerful keyword in Java is calledSynchronizedTo facilitate thread synchronization. Today's whimsical attempt is to simulate a similar one in C ++. When I recently learned C ++ STL and saw the smart pointer chapter, I was not surprised to use the rich features of language to implement various clever ideas.

1,volatile The variable it modifies does not retain a copy and accesses directly in the main memory. In the Java memory model, there is main memory, and each thread has its own memory (for example, registers). For performance, a thread keeps a copy of the variable to be accessed in its own memory.This will show the same variable at some point, the value in the memory of one thread may be inconsistent with the value in the memory of another thread, or

entry to 0.If synchronized is added to a common method, then the valid range is the way that multiple threads execute the same object. The above explanation should be easier to understand, because different objects get different monitor monitors, and naturally there is no occupancy-wait process. If you are loading the static method then you need to get the objec

On behalf of this method lock, the equivalent of any thread a every time it runs to this method, it is necessary to check if there is any other thread B (or C d, etc.) that is using this method, or wait for thread B (or C D) that is using this method to run this method befor

, then the method or the thread within the method block may have multiple at the same time, assuming that wait () is available, it will add all of these threads to the waiting set to be awakened so that there is never any extra thread to wake them up. Each object manages a thread that calls its wait (), notify (), so that other objects cannot help even if they want to help. The result is that multithreading

As early as the summary, I will try to put the focus of the synchronized is simple: it is matching and object of the implicit lock use, attention must be the object of the implicit lock! So how does the following example explain this? Java code /*** User:yanxuxin* Date:dec 17, 2009* Time:9:38:27 PM*/public class Implicitlocksample { public static void Main (string[] args) {Final Implicitlock sample = new

Performance Comparison In JDK1.5, synchronized is inefficient. Because this is a heavyweight operation, its greatest performance impact is the implementation, suspend the thread and recover the thread of the operation need to go into the kernel state of completion, these operations to the system's concurrency has brought great pressure. By contrast, using the lock object provided by Java, the performance

is satisfied;2. Synchronized general end of multi-threaded environment, for the use of shared resources to deal with the problem;3. Notify is used to wake the wait () thread;The difference between wait and sleepWait is for the machine lock of the block where the current synchronized is located:1>. Synchronized if an ordinary class is identified, the lock is the

java allows multi-threaded concurrency control, when multiple threads concurrently manipulate a shareable resource variable (such as data additions and deletions), will result in inaccurate data and conflict with each other, so join the sync lock to avoid before the thread does not complete the operation , called by other threads, to ensure the uniqueness and accuracy of the variable. 1. Synchronization methods The

testOkokokokokokthisis testOkthisok is TokokokoestIt can be seen that at the beginning of the output is not a problem, and then the output is chaotic.The workaround is to add the synchronization method to the Outputstr method to add the Sync keyword synchronized can Public synchronized void outputstr (String str)