Why double checked locking is broken?

In multi-threaded environments, initialization is usually not thread safe, so locking is required to protect the critical section. Since only the first access requires locking, double-checked locking is used to avoid locking overhead of subsequent accesses.

Why volatile in double checked locking?

volatile in turn establishes happens-before relation between reads and writes, and fixes the broken pattern. If you are looking for performance, use holder inner static class instead. But there’s no lock acquisition in the case the second thread only hits the outer if, so no ordering.

What is double lock in multithreading?

It is typically used to reduce locking overhead when implementing “lazy initialization” in a multi-threaded environment, especially as part of the Singleton pattern. Lazy initialization avoids initializing a value until the first time it is accessed.

What is the use of double checked locking in Singleton?

Double checked locking of Singleton is a way to make sure that only one instance of Singleton class is created through an application life cycle.

Do or make a double check?

to make certain that something is correct or safe, usually by examining it again: I always double-check to make sure I locked the door.

What is volatile C#?

The volatile keyword in C# is used to inform the JIT compiler that the value of the variable should never be cached because it might be changed by the operating system, the hardware, or a concurrently executing thread. You can declare a variable as volatile by preceding it with the volatile keyword.

Can the double checked locking fail on a single processor system?

Q1. Can the double checked locking fail on single processor system? Ans. So double check locking will not fail depending on number of processor.

Do or make a double-check?

What is it called for double check?

verify, cross-check, ascertain, examine, substantiate.

Is double-checked locking broken?

The “Double-Checked Locking is Broken” Declaration. Double-Checked Locking is widely cited and used as an efficient method for implementing lazy initialization in a multithreaded environment. Unfortunately, it will not work reliably in a platform independent way when implemented in Java, without additional synchronization.

Is double checked locking required in C++11?

Usage in C++11. For the singleton pattern, double-checked locking is not needed: If control enters the declaration concurrently while the variable is being initialized, the concurrent execution shall wait for completion of the initialization.

Can double-checked locking be implemented without synchronization?

Double-Checked Locking is widely cited and used as an efficient method for implementing lazy initialization in a multithreaded environment. Unfortunately, it will not work reliably in a platform independent way when implemented in Java, without additional synchronization.