There is my code public class Test { private static boolean running = true; public static void main(String[] args) { new Thread(() -> { System.out.println(Thread.currentThread().getName() +...

I wrote this code that looked very simple to me at a first glance. It modifies a variable that is referenced by a reference variable and then returns the value of the reference. A simplified versio...

public class Factory { private Singleton instance; public Singleton getInstance() { Singleton res = instance; if (res == null) { synchronized (this) { res = instance; if (res == null) { res...

The volatile keyword is used in C to prevent the compiler performing certain optimizations, amongst other subtle changes, on a variable. For example; volatile int my_int = 0; creates an integer...

I was looking at some of the implementation details of Task in System.Threading.Tasks (.NET standard 2.0) and I came across this interesting piece of code: internal volatile int m_stateFlags; ......

Assume I have a field that's accessed concurrently and it's read many times and seldom written to. public Object myRef = new Object(); Let's say a Thread T1 will be setting myRef to another valu...

I am trying to understand the intrinsics of java volatile and its semantics, and its transaltion to the underlying architecture and its instructions. If we consider the following blogs and resourse...

This is a borderline topic. Since I wanted to know about programming, CPU cache memory, reading CPU cache lines etc, I'm posting it here. I was implementing AES algorithm in C/C++. Since performin...

I've read some posts and articles saying that we shouldn't declare java objects as volatile, because as a result, only the reference becomes volatile. Here are some examples: link-1 link-2 link-3 ...

I read some articles about the volatile keyword but I could not figure out its correct usage. Could you please tell me what it should be used for in C# and in Java?

Consider the snippet from Java Concurrency in Practice- @ThreadSafe public class SynchronizedInteger{ @GuardedBy("this") private int value; public synchronized int getValue() { return value; ...

suppose we use double-check lock to implement singleton pattern: private static Singleton instance; private static Object lock = new Object(); public static Singleton getInstance() { if(inst...

Here I wrote a test about access speed of local, member, volatile member: public class VolatileTest { public int member = -100; public volatile int volatileMember = -100; public static void mai...

I've got an address which points to a control port like so (for context I'm working on a Sega/Megadrive game): volatile u32 * vdp_ctrl = (u32 *) 0x00C00004; And an array of initial values I want...

If I have this code: class A { ... }; class B { ... }; void dummy() { A a(...); B b(...); ... } I know that variables a and b will be destroyed in reverse allocation order (b will be destroy...

According to cppreference, most uses of the volatile keyword are to be deprecated in C++20. What is the disadvantage of volatile? And what is the alternative solution when not using volatile?

As known, std::atomic and volatile are different things. There are 2 main differences: Two optimizations can be for std::atomic<int> a;, but can't be for volatile int a;: fused operation...

I know volatile keyword prevents compiler from optimizing a variable and read it from memory whenever it is read. Apart from memory mapped registers, what are all the situations where we need to us...

volatile int vfoo = 0; void func() { int bar; do { bar = vfoo; // L.7 }while(bar!=1); return; } This code busy-waits for the variable to turn to 1. If on first pass vfoo is not set to 1, wi...

Consider this simple code: void g(); void foo() { volatile bool x = false; if (x) g(); } https://godbolt.org/z/I2kBY7 You can see that neither gcc nor clang optimize out the potential call ...

If there are two threads accessing a global variable then many tutorials say make the variable volatile to prevent the compiler caching the variable in a register and it thus not getting updated co...

Premise: I'm working with an ARM embedded (almost bare-metal) environment where I don't even have C++11 (with std::atomic<int>) available, so please avoid answers like "just use standard C++ ...

I know volatile allows for visibility, AtomicInteger allows for atomicity. So if I use a volatile AtomicInteger, does it mean I don't have to use any more synchronization mechanisms? Eg. c...

How do you declare a particular member of a struct as volatile?

I am reading an article about the Java Volatile keyword, got some questions. click here public class MyClass { private int years; private int months private volatile int days; public void up...