Time duration is the difference between two time points. It will be measured in time ticks.

The starting point (epoch) and the additional time duration define the time point. It consists of two components, clock and time duration.

A blog dealing with multithreading in modern C++ but not writing about the new time library is incomplete. Primarily because I often used the time library in my posts to measure the performance of shortcode snippets. Therefore, I give in this post an overview of the components of the time library: time point, time duration, and clock. I will write additional posts about each of these three components.

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

Until now, I've used two strategies to summate a std::vector. First, I did the whole math in one thread (Single Threaded: Summation of a vector); second multiple threads shared the same variable for the result (Multithreaded: Summation of a vector). In particular, the second strategy was extremely naive. In this post, I will apply my knowledge of both posts. My goal is that the thread will perform their summation as independently from each other as possible and therefore reduce the synchronization overhead. 

My goal is to sum up all elements of a vector. I used in the last post a single thread. In this post, I use multiple threads and, therefore, the full power of my PC. The addition will be done on a shared variable. What, at first glance, seems like a good idea is a very naive strategy. The synchronization overhead of the summation variable is higher than the performance benefit of my four or two cores.

What is the fastest way to add the elements of a std::vector? This a question that I will pursue in the following posts. I use the single-threaded addition as the reference number. In further posts, I discuss atomics, locks, and thread-local data.

There are a lot of issues with the singleton pattern. I'm aware of that. But the singleton pattern is an ideal use case for a variable, which can only be initialized in a thread-safe way. From that point on, you can use it without synchronization. So in this post, I discuss different ways to initialize a singleton in a multithreading environment. You get the performance numbers and can reason about your use cases for the thread-safe initialization of a variable.

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

But we can improve and further improve the acquire-release semantics of the last post. Why should x be atomic? There is no reason. That was my first but incorrect assumption. See why?