David v.Knobelsdorff dehlen

libdispatch efficiency tips

The libdispatch is one of the most misused API due to the way it was presented to us when it was introduced and for many years after that, and due to the confusing documentation and API. This page is a compilation of important things to know if you're going to use this library. Many references are available at the end of this document pointing to comments from Apple's very own libdispatch maintainer (Pierre Habouzit).

My take-aways are:

You should create very few, long-lived, well-defined queues. These queues should be seen as execution contexts in your program (gui, background work, ...) that benefit from executing in parallel. An important thing to note is that if these queues are all active at once, you will get as many threads running. In most apps, you probably do not need to create more than 3 or 4 queues.
Go serial first, and as you find performance bottle necks, measure why, and if concurrency helps, apply with care, always validating under system pressure. Reuse

	//
	// ColorSchemeApp.swift
	// ColorScheme
	//
	// Created by Craig Hockenberry on 9/11/24.
	//

	import SwiftUI

	@main

	// Copyright 2021 Kyle Hughes
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	// SparkleCommands.swift
	// Past for iChat
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	// Created by Helge Heß on 08.04.21.
	//

	import SwiftUI

	#if SPARKLE && canImport(Sparkle)

	// Depends on https://github.com/sindresorhus/Defaults
	@available(macOS 10.15, *)
	private struct ShowForAppRuns: ViewModifier {
	private static var runCounts = [String: Int]()

	private let count: Int
	private let startShowingFromAppRun: Int
	private let runCount: Int

	init(count: Int, id: String, startShowingFromAppRun: Int = 1) {

	//
	// Library.swift
	// LabelLayout
	//
	// Created by Chris Eidhof on 09.09.18.
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	import UIKit

	//
	// UserDefaults.swift
	//
	// Created by Shaps Benkau on 24/05/2018.
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	import Foundation

	#if os(iOS)

	import UIKit
	import Cartography // https://github.com/robb/Cartography

	/**
	This is an example of self sizing `UICollectionView` cells using AutoLayout,
	where the width of cells is always the width of the parent, to mimic `UITableView`.
	*/

	fileprivate let items: [String] = (0..<100)
	.map { _ in Lorem.sentences(Int.random(min: 1, max: 8)) } // Using https://github.com/lukaskubanek/LoremSwiftum/blob/master/Sources/LoremSwiftum.swift

	// @flow
	import React from 'react';
	import styled from 'styled-components';

	type GlobalCssValues = 'initial' \| 'inherit' \| 'unset';

	type WrapValue = 'nowrap' \| 'wrap' \| 'wrap-reverse' \| GlobalCssValues;

	type JustifyValue =
	\| 'center'

	#!/usr/bin/env ruby

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