What is iOS deadlock?
In short, a deadlock can occur when the system is waiting for a resource to free up while it’s logically impossible for that resource to become available. You can think of this resource as almost anything. It could be a database handle, a file on the filesystem, or even time to run code on the CPU.
Is iOS multi threaded?
Concurrency and multithreading are a core part of iOS development. Let’s dive into what makes them so powerful, and how we can leverage them in our own Cocoa Touch applications.
What is thread explosion?
When a queue blocks its thread, a new thread will be spawned to handle work. This means that the system can overcommit with more threads than there are CPU cores. This is also called Thread explosion and can lead to memory and performance issues. There’s a lot of scheduling overhead during threads.
What is main thread Swift?
The main thread is the one that starts our program, and it’s also the one where all our UI work must happen. However, there is also a main queue, and although sometimes we use the terms “main thread” and “main queue” interchangeably, they aren’t quite the same thing.
Is Swift dictionary thread safe?
Dictionaries in Swift are not thread safe , they lead to wierd crashes which are very hard to debug. This class solves this problem by using a dictionary whose accesses are made thread safe by using a concurrent queue with a barrier.
Is NSLock fair?
NSLock and the other Foundation’s locks are unfair, meaning that when a series of threads is waiting to acquire a lock, they will not acquire it in the same order in which they originally tried to lock it. A lower-level C pthread_mutex_t is also available in Swift.
Is iOS single threaded?
Each process (application) in OS X or iOS is made up of one or more threads, each of which represents a single path of execution through the application’s code. Every application starts with a single thread, which runs the application’s main function.
What is the difference between GCD and NSOperation?
GCD is a low-level C-based API that enables very simple use of a task-based concurrency model. NSOperation and NSOperationQueue are Objective-C classes that do a similar thing. NSOperation was introduced first, but as of 10.5 and iOS 2, NSOperationQueue and friends are internally implemented using GCD .
What is deadlock in Swift?
Deadlock. The word Deadlock refers to a situation in which a set of different threads sharing the same resource are waiting for each other release the resource to finish its tasks. When working with the GCD, if we do not fully understand the GCD’s concepts, we may create a deadlock in our code.
What are queues and threads?
A message queue is a data structure for holding messages from the time they’re sent until the time the receiver retrieves and acts on them. Generally queues are used as a way to ‘connect’ producers (of data) & consumers (of data). A thread pool is a pool of threads that do some sort of processing.
Is main thread C++?
2.1. Basic thread management. Every C++ program has at least one thread, which is started by the C++ runtime: the thread running main() . Your program can then launch additional threads that have another function as the entry point.
What does main thread mean?
The main thread is where a browser processes user events and paints. By default, the browser uses a single thread to run all the JavaScript in your page, as well as to perform layout, reflows, and garbage collection.