Tag Archive for: Relaxed Semantics

Posts

BlockingNonBlocking

Blocking and Non-Blocking Algorithms

June 2, 2017

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Blocking, non-blocking, lock-free, and wait-free. Each of these terms describes a key characteristic…

SingleThreadedAdditionEng

My Conclusion: Summation of a Vector in three Variants

September 11, 2016

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After I've calculated in three different ways the sum of a std::vector I want to draw my conclusions. The…

localVariable

Multithreaded: Summation with Minimal Synchronization

September 7, 2016

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Until now, I've used two strategies to summate a std::vector. First, I did the whole math in one thread…

sukzessiveOptimierungRelaxedSemantikEng

Ongoing Optimization: Relaxed Semantics with CppMem

August 20, 2016

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With the relaxed semantics, we have no synchronizations and ordering constraints on atomic operations. Relaxed…

relaxed

Relaxed Semantics

July 27, 2016

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The relaxed semantics is the end of the scale. The relaxed semantic is the weakest of all memory models…

FullFence

Fences are Memory Barriers

July 19, 2016

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The key idea of a std::atomic_thread_fence is to establish synchronization and ordering constraints between…

atomicOperationsReadWriteEng

Synchronization and Ordering Constraints

June 28, 2016

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In this post, our tour through the c++ memory model goes one step deeper. Until now, the posts were only…

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A Lock-Free Stack: Atomic Smart PointerFebruary 17, 2025 - 11:47 am
The easiest way to solve this memory leak issue from the last post is to use a std::shared_ptr. Atomic Smart Pointer There are two ways to apply atomic operations on a std::shared_ptr: In C++11, you can use the free atomic functions on std::shared_ptr. With C++20, you can use atomic smart pointers. C++11 Using atomic operations […]
A Lock-Free Stack: A Complete ImplementationFebruary 10, 2025 - 3:01 pm
My last lock-free stack implementation was incomplete. It only supported push operations. Let’s change this. The following paragraph about sequential consistency is optional. You can easily ignore it. Sequential Consistency In my examples, I use the default memory ordering: sequential consistency. The reason is simple. Sequential consistency provides the strongest guarantees of all memory ordering […]
My Next Mentoring Program: “Generic Programming (Templates) with C++” startsFebruary 4, 2025 - 4:51 pm
My next mentoring program, “Embedded Programming with Modern C++,” starts on January 31st. Registration is open. Here are more details. Embedded Programming with Modern C++ The mentoring program consists of 16 stations. You have to invest at least 3 hours per week for each one. This means the program takes four months, and you can […]
A Lock-Free Stack: A Simplified ImplementationFebruary 3, 2025 - 10:37 am
Today, I continue my mini story about lock-free data structures. General Considerations From the outside, the caller’s responsibility (application) is to protect the data. From inside, the data structure is responsible for protecting itself. A data structure that protects itself so a data race cannot appear is called thread-safe. First, what general considerations must you […]
Deferred Reclamation in C++26: Read-Copy Update and Hazard PointersJanuary 27, 2025 - 12:23 pm
Before I dive into lock-free programming, there’s a little bit of theory necessary. A common problem in concurrency is the so-called ABA problem. That means you read a variable twice, which returns the same value each time, A. Therefore, you conclude that nothing changed in between. But you forgot the B. Let me first use […]
std::format ExtensionJanuary 20, 2025 - 11:55 am
Displaying the address of an arbitrary pointer in C++ 20 fails but succeeds with C++26. C++20 Only void, const void, and std::nullptr_t pointer types are valid. If you want to display the address of an arbitrary pointer, you must cast it to (const) void*. // formatPointer20.cpp #include <format> #include <iostream> #include <string> int main() { […]