java-memory-model

Here is the originan question, but mine have some differences with it. C++ memory model - does this example contain a data race? My question: //CODE-1: initially, x == 0 and y == 0 if (x) y++; // pthread 1 if (y) x++; // pthread 2 Note: the code above is written in C, not C++ (without a memory model). So does it contain a data race? From my point of view: if we view the code in Sequential Consistency memory model, there is no data race because x and y will never be both non-zero at the same time. However, we can never assume a Sequential Consistency memory model, so the compilier reordering

I am watching video from java jpoint conference. I have question about following slide from Alexey Shipilev report: Excuse me for non-english on slide. Actually author says that it is impossible that variable set will be r1 = 1 (Y) r2 = 0 (x) r3 = 1 (x) r4 = 0 (Y) According the video he implies that it is obviously. Can someone clarify why this value set impossible according JMM? P.S. If I understand Alexey notation correct it respects the following code: public class SequentialConsistency { static volatile int x; static volatile int y; public static void main(String[] args) { new Thread(new

I read somewhere that starting a thread has some special effect on the happend before relationship. Now I'm not sure if my code gurantees the happend before relationship, so please enlighten me. I have a Dispatcher thread and a Worker class implementing the Runnable interface. The Dispatcher thread creates a new instance of the Worker and fills a LinkedList in the Worker instance through the add method with elements. Then the Dispatcher hands the Worker instance to a ExecutorService via the execute method. Then the run method in the Worker class starts accessing and removing stuff from the

When a synchronized method is completed, will it push only the data modified by it to main memory, or all the member variables, similarly when a synchronized method executes, will it read only the data it needs from main memory or will it clear all the member variables in the cache and read their values from main memory ? For example public class SharedData { int a; int b; int c; int d; public SharedData() { a = b = c = d = 10; } public synchronized void compute() { a = b * 20; b = a + 10; } public synchronized int getResult() { return b*c; } } In the above code assume compute is executed by