synchronization

Possible Duplicate: Java Synchronized Block for .class I was reading through an article on synchronization. I am confused on below points and need more clarification 1) For synchronization block. How synchronize(this){ // code } differs from synchronize(MyClass.class){ //code } 2) Synchronizing instance method means threads will have to get exclusive lock on the instance, while synchronizing static method means thread will have to acquire a lock on whole class(correct me if I am wrong). So if a class has three methods and one of them is static synchronized then if a thread acquires lock on

First a little context : I'm in the process of learning about threading in C++11 and for this purpose, I'm trying to build a small actor class, essentially (I left the exception handling and propagation stuff out) like so: class actor { private: std::atomic<bool> stop; private: std::condition_variable interrupt; private: std::thread actor_thread; private: message_queue incoming_msgs; public: actor() : stop(false), actor_thread([&]{ run_actor(); }) {} public: virtual ~actor() { // if the actor is destroyed, we must ensure the thread dies too stop = true; // to this end, we have to interrupt the

With the new async/await keywords in C#, there are now impacts to the way (and when) you use ThreadStatic data, because the callback delegate is executed on a different thread to one the async operation started on. For instance, the following simple Console app: [ThreadStatic] private static string Secret; static void Main(string[] args) { Start().Wait(); Console.ReadKey(); } private static async Task Start() { Secret = "moo moo"; Console.WriteLine("Started on thread [{0}]", Thread.CurrentThread.ManagedThreadId); Console.WriteLine("Secret is [{0}]", Secret); await Sleepy(); Console.WriteLine(

Here is the scenario. 2 web servers in two separate locations having two mysql databases with identical tables. The data within the tables is also expected to be identical in real time. Here is the problem. if a user in either location simultaneously enters a new record into identical tables, as illustrated in the two first tables below, where the third record in each table has been entered simultaneously by the different people. The data in the tables is no longer identical. Which is the best way to maintain that the data remains identical in real time as illustrated in the third table below

Can some one explain initialization safety as required by Java memory model ? How does the final fields help in achieving initialization safety ? What role does the constructor play in ensuring initialization safety ? Initialization safety provides for an object to be seen by an external thread in its fully constructed ( initialized ) state. The prerequisite is that the object should not be published prematurely ie. in its constructor. Once this is ensured , JMM requires certain behaviour for the fields that are declared as final . First , all final object fields are guarenteed to be seen by

Ok, so I am reading about synchronization, and I read through various algorithms such as spinlocks, semaphores, and mutex to avoid race condition. However, these algorithms can't prevent race condition in SMP when multiple proceses access the data exactly at the same time. For example, suppose thread 1 in processor A runs lock(mutex1); withdraw(1000); unlock(mutex1); and thread 2 in processor B runs lock(mutex1); deposit(1000); deposit(1000); unlock(mutex1); When both threads run EXACTLY AT THE SAME TIME, both threads will be in critical section simultaneously. The only solution (should be in

I am developing a web application using php and mysql. This application runs on three different locations. On internet Head office Branch office Application runs on local server on head office and branch office. Internet connection is not available on every time. Customers placing orders through these three locations. My problem is, I want to synchronize the data among these three databases and keep these three databases up to date. Is there any way to do this? I'm using SymmetricDS to synchronize databases. It is capable of synchronizing or replicating data between nodes (servers/databases),

In what cases is it necessary to synchronize access to instance members? I understand that access to static members of a class always needs to be synchronized- because they are shared across all object instances of the class. My question is when would I be incorrect if I do not synchronize instance members? for example if my class is public class MyClass { private int instanceVar = 0; public setInstanceVar() { instanceVar++; } public getInstanceVar() { return instanceVar; } } in what cases (of usage of the class MyClass ) would I need to have methods: public synchronized setInstanceVar() and