Get off my thread: Techniques for moving work to background threads Anthony Williams Just Software Solutions Ltd https://www.justsoftwaresolutions.co.uk September 2020Get off my thread: Techniques for current thread? How do we move work off the current thread? Final Guidelines and QuestionsWhy do we need to move work off the current thread?Why do we need to move work off the current thread? Many environments environments have a dedicated thread for processing events: GUIs Client-Server applications Performing extensive processing on the event thread prevents other events from being handled.Why do we need

Back to Basics: Concurrency STD::THREAD int main() { std::thread my_thread{[](int z){ std::cout << "Hello from thread: " << z << "\n"; }, 42}; my_thread.join(); } Hello, world! https://godbolt Calls to acquire() and release() can happen on different threads https://en.cppreference.com/w/cpp/thread/counting_semaphoreCppCon 2023 9 David Olsen - Back to Basics: Concurrency CONCURRENCY “Multiple Make sure your code is thread safe with no data races SummaryCppCon 2023 42 David Olsen - Back to Basics: Concurrency STD::THREAD https://en.cppreference.com/w/cpp/thread/threadCppCon 2023 43 David

programmers? In this talk we provide a gentle introduction to concurrency with the modern C++ std::thread library. We will introduce topics with pragmatic code examples introducing the ideas of threads fundamental building blocks to write for instance a multi-threaded program ○ We are going to focus on std::thread for creating concurrent programs. ■ We will review briefly other methods of writing concurrent programs fundamental building blocks to write for instance a multi-threaded program ○ We are going to focus on std::thread for creating concurrent programs. ■ We will review briefly other methods of writing concurrent programs

Terrible task selection “fairness” Task Thread Thread Thread Task Task Task Task Task Task Task Back Front Task Queue Execute Task() Thread Thread PoolRethinking: Task Queues Problem #2 - starvation, load balancing, work stealing Task Thread Thread Thread Task Task Task Task Task Task Task Back Front Task Queue Execute Task() Thread Thread PoolRethinking: Task Queues Problem #3 - prioritization, etc, as enumerated previously Task Thread Thread Thread Task Task Task Task Task Task Task Back Front Task Queue Execute Task() Thread Thread PoolRethinking: Task Queues Summary: ● Queues

use std::io; use rand::Rng; fn main() { println!("Guess the number!"); let secret_number = rand::thread_rng().gen_range(1, 101); println!("The secret number is: {}", secret_number) ; println!("Please lines in the middle. The rand:: thread_rng function will give us the particular random number gen- erator that we’re going to use: one that is local to the current thread of execution and seeded by the std::cmp::Ordering; use rand::Rng; fn main() { println!("Guess the number!"); let secret_number = rand::thread_rng().gen_range(1, 101); println!("The secret number is: {}", secret_number) ; println!("Please

multithreaded programs? 4 Thread A int x = 0; start_thread_b(); x = 1; Thread B while (x != 1) {} Will this loop ever terminate? Will this write ever become “visible” to Thread B?The compiler can rewrite unambiguously “yes.” No other thread is allowed to look at the variable x while this thread is modifying it; and without some kind of synchronization, there’s no way to ensure that this thread isn’t modifying it new thread In C++03 pthreads, you’d create a new thread by calling a third-party library function. In C++11, the standard library “owns” the notion of creating new threads. To create a thread, you

let mut b = &a[0..4]; println!("{}", b); //This will panic //thread 'main' panicked at 'byte index 6 is not a char boundary; it is inside '你' (bytes 5..8) of `testa Arc Weak 首先引出 Arc 前先罗列一个例子。搭配 mutex 进行使用，对共享内存中的内容 进行修改。 use std::sync::{Mutex, Arc}; use std::thread; fn main() { let counter = Arc::new(Mutex::new(0)); let mut handles = vec![]; (i,j) in (0..20).enumerate() { let counter = Arc::clone(&counter); let handle = thread::spawn(move || { let mut num = counter.lock().unwrap(); println!("index

进程一般由程序段、数据段和进程控制块三部分构成进程 实体。 大纲 线程基础 线程控制 线程的同步 相关知识回顾 什么是线程 根据多任务原理，在一个程序内部也可以实现多个任务（顺序控 制流）的并发执行，其中每个任务被称为线程（Thread）。更专 业的表述为： 线程是程序内部的顺序控制流。 大纲 线程基础 线程控制 线程的同步 相关知识回顾 线程和进程的区别和联系 代码 数据 进程空间 打开文件 寄存器 栈 线程 1 。 大纲 线程基础 线程控制 线程的同步 相关知识回顾 多核与多线程 ▶ 多核处理器是指在一个处理器上集成多个运算核心以提高并 行计算能力，每一个处理核心对应一个内核线程（Kernel Thread，KLT）。 ▶ 内核线程是直接由操作系统内核支持的线程，由内核来完成 线程切换，内核通过操作调度器对线程进行调度，并负责将 线程的任务映射到各个处理器上。 大纲 线程基础 线程控制 线程的同步 线程的概念模型 Java 线程的概念模型 在 Java 语言中，多线程的机制通过虚拟 CPU 来实现。 1. 虚拟的 CPU，由 java.lang.Thread 类封装和虚拟； 2. CPU 所执行的代码和数据，传递给 Thread 类对象。 代码 数据 虚拟CPU 大纲 线程基础 线程控制 线程的同步 创建线程 ���� 线程基础 相关知识回顾 线程的概念模型 创建线程

� � � � � � � � � � concurrency � � � � � � ) � � � � � � � � preemptively � � � � � � � � � � � thread � � � mutex � � ( � async/await concurrency (multitasking � � � � � � � ( � � � � � � � � � � � futures are accessible from any thread, they must be Sync. Interior mutability is possible through a Mutex, atomic or similar . Thread-local data can be created with the macro std::thread_local . 10.6 � � � � std::time::Duration ; fn sleep_for(secs: f32 ( } if let Ok(dur) = Duration::try_from_secs_f32(secs ( } std::thread::sleep(dur ( ; println!("slept for {:?}", dur ( ; { { fn main ) ( } sleep_for(-10.0 ( ; sleep_for(0

channel.Reader(); thread xfutures/promises: “buffered channel” Channel channel; Channel::Reader reader = channel.Reader(); reader.Read(); // Blocks! thread xfutures/promises: Reader(); reader.Read(); // Blocks! Channel::Writer writer = channel.Writer(); thread x thread yfutures/promises: “buffered channel” Channel channel; Channel::Reader Channel::Writer writer = channel.Writer(); writer.Write("..."); // Non-blocking! thread x thread yfutures/promises: “buffered channel” Channel channel; Channel::Reader