I want to start another series of articles about lock-free algorithms and how we can implement them using swift atomics framework. It’s a very complicated topic with a lot of hidden stones there. I want to mention that it’s very difficult to debug and find mistakes. Sometimes algorithms can behave…

In this article, we will implement some of the GCD classes using low-level primitives to understand how GCD is actually functioning. Semaphore We’re going to begin with DispatchSemaphore, although what we’ll be implementing is a simplified version. The real DispatchSemaphore has a much more specific set of functionalities. …

In this article, we will discuss some niche concepts such as DispatchSource and target queue hierarchy. DispatchSource DispatchSource is the fundamental type that handles system events. It can be an event listener for different types like file system events, signals, memory warnings and etc. I don’t think we often use this…

The topic of today’s article is synchronization. It’s one of the most important concepts in multithreading. And we will see how we can provide thread safety using GCD primitives. Semaphore And the first primitive we will consider is DispatchSemaphore. I guess you’ve heard about mutex before. Briefly, it’s a construction that…

Today we will consider one of the most useful GCD components DispatchGroup and also we will take a look at the concurrentPerform method and dispatch precondition. DispatchGroup In some cases, we need to follow a certain order of our tasks. To solve these issues we can use DispatchGroup. As you remember…

This is the second part of the GCD series and here we will discuss QoS and DispatchWorkItem. DispatchWorkItem There is a way to add a task to the queue through a special class called DispatchWorkItem instead of direct passing the closure to async or sync methods. This class provides additional methods…

I would like to start a series of articles about Grand Central Dispatch (GCD). GCD or libdispatch is one the most popular instruments for multithreading programming in iOS and macOS. It’s a library written in C to ease thread management. …