C++11 并发指南一(C++11 多线程初探)

时间:2023-11-29 16:02:50

引言

C++11 自2011年发布以来已经快两年了,之前一直没怎么关注,直到最近几个月才看了一些 C++11 的新特性,今后几篇博客我都会写一些关于 C++11 的特性,算是记录一下自己学到的东西吧,和大家共勉。

相信 Linux 程序员都用过 Pthread, 但有了 C++11 的 std::thread 以后,你可以在语言层面编写多线程程序了,直接的好处就是多线程程序的可移植性得到了很大的提高,所以作为一名 C++ 程序员,熟悉 C++11 的多线程编程方式还是很有益处的。

如果你对 C++11 不太熟悉,建议先看看维基百科上关于 C++11 新特性的介绍,中文C++11介绍英文C++11介绍 ,另外C++之父 Bjarne Stroustrup 的关于 C++11 的 FAQ 也是必看的,我也收集了一些关于C++11的资料,供大家查阅:

资料汇

http://www.open-std.org/jtc1/sc22/wg21/

C++0x/C++11 Support in GCC:http://gcc.gnu.org/projects/cxx0x.html

What is C++0x:https://www2.research.att.com/~bs/what-is-2009.pdf

Overview of the New C++:http://www.artima.com/shop/overview_of_the_new_cpp

Overview of the New C++ (C++0x).pdf:http://ishare.iask.sina.com.cn/f/20120005.html?from=like

A Brief Look at C++0x:http://www.artima.com/cppsource/cpp0x.html

Summary of C++11 Feature Availability in gcc and MSVC:http://www.aristeia.com/C++11/C++11FeatureAvailability.htm

C++ 11: Come Closer:http://www.codeproject.com/Articles/344282/Cplusplus-11-Come-Closer

C++11 threads, locks and condition variables: http://www.codeproject.com/Articles/598695/Cplusplus11-threads-locks-and-condition-variables

Move Semantics and Perfect Forwarding in C++11:http://www.codeproject.com/Articles/397492/Move-Semantics-and-Perfect-Forwarding-in-Cplusplus

http://solarianprogrammer.com/categories/C++11/

C++11 Concurrency:http://www.baptiste-wicht.com/2012/03/cpp11-concurrency-part1-start-threads/

http://www.hpl.hp.com/personal/Hans_Boehm/misc_slides/sfacm-cleaned.pdf

http://en.cppreference.com/w/cpp/thread

http://isocpp.org/blog/2012/12/c11-a-cheat-sheet-alex-sinyakov

The Biggest Changes in C++11:http://blog.smartbear.com/c-plus-plus/the-biggest-changes-in-c11-and-why-you-should-care/

Ten C++11 Features Every C++ Developer Should Use:http://www.codeproject.com/Articles/570638/Ten-Cplusplus11-Features-Every-Cplusplus-Developer

C++11 – A Glance [part 1 of n]:http://www.codeproject.com/Articles/312029/Cplusplus11-A-Glance-part-1-of-n

C++11 – A Glance [part 2 of n]:http://www.codeproject.com/Articles/314415/Cplusplus11-A-Glance-part-2-of-n

C++11(及现代C++风格)和快速迭代式开发:http://mindhacks.cn/2012/08/27/modern-cpp-practices/

Lambda Functions in C++11 - the Definitive Guide:http://www.cprogramming.com/c++11/c++11-lambda-closures.html

Better types in C++11 - nullptr, enum classes (strongly typed enumerations) and cstdint:http://www.cprogramming.com/c++11/c++11-nullptr-strongly-typed-enum-class.html

Rvalue-references-and-move-semantics-in-c++11:http://www.cprogramming.com/c++11/rvalue-references-and-move-semantics-in-c++11.html

http://www.gotw.ca/publications/index.htm

http://www.devx.com/SpecialReports/Door/38865

Multi-threading in C++0x:http://accu.org/index.php/journals/1584

C++ 0X feature summary cheat sheat:http://www.iesensor.com/blog/2011/05/31/c-0x-feature-summary-cheat-sheat/

Multithreading in C++0x part 1: Starting Threads:http://www.justsoftwaresolutions.co.uk/threading/multithreading-in-c++0x-part-1-starting-threads.html

http://en.cppreference.com/w/cpp/thread

http://www.cplusplus.com/reference/multithreading/

好了,下面来说正题吧 ;-)

与 C++11 多线程相关的头文件

C++11 新标准中引入了四个头文件来支持多线程编程,他们分别是<atomic> ,<thread>,<mutex>,<condition_variable>和<future>。

  • <atomic>:该头文主要声明了两个类, std::atomic 和 std::atomic_flag,另外还声明了一套 C 风格的原子类型和与 C 兼容的原子操作的函数。
  • <thread>:该头文件主要声明了 std::thread 类,另外 std::this_thread 命名空间也在该头文件中。
  • <mutex>:该头文件主要声明了与互斥量(mutex)相关的类,包括 std::mutex 系列类,std::lock_guard, std::unique_lock, 以及其他的类型和函数。
  • <condition_variable>:该头文件主要声明了与条件变量相关的类,包括 std::condition_variable 和 std::condition_variable_any。
  • <future>:该头文件主要声明了 std::promise, std::package_task 两个 Provider 类,以及 std::future 和 std::shared_future 两个 Future 类,另外还有一些与之相关的类型和函数,std::async() 函数就声明在此头文件中。

std::thread "Hello world"

下面是一个最简单的使用 std::thread 类的例子:

#include <stdio.h>
#include <stdlib.h> #include <iostream> // std::cout
#include <thread> // std::thread void thread_task() {
std::cout << "hello thread" << std::endl;
} /*
* === FUNCTION =========================================================
* Name: main
* Description: program entry routine.
* ========================================================================
*/
int main(int argc, const char *argv[])
{
std::thread t(thread_task);
t.join(); return EXIT_SUCCESS;
} /* ---------- end of function main ---------- */

Makefile 如下:

all:Thread

CC=g++
CPPFLAGS=-Wall -std=c++ -ggdb
LDFLAGS=-pthread Thread:Thread.o
$(CC) $(LDFLAGS) -o $@ $^ Thread.o:Thread.cc
$(CC) $(CPPFLAGS) -o $@ -c $^ .PHONY:
clean clean:
rm Thread.o Thread

注意在 Linux GCC4.6 环境下,编译时需要加 -pthread,否则执行时会出现:

$ ./Thread
terminate called after throwing an instance of 'std::system_error'
what(): Operation not permitted
Aborted (core dumped)

原因是 GCC 默认没有加载 pthread 库,据说在后续的版本中可以不用在编译时添加 -pthread 选项。

更多的有关 C++11 Concurrency 的介绍将在后续的一系列博客中写出,希望自己勤快一点吧 ;-)