知识点１
转载自 https://www.ev0l.art/index.php/archives/9/
- Linux 下编译 带<thread> 的CPP需要加上 -pthread 编译选项。例如：
g++ -std=c++11 -pthread a.cpp
- QT Creator 编译带<thread>的CPP有ＢＵＧ，暂时不知道怎么去除！
代码1
#include <stdlib.h>v
#include <thread>
using namespace std;
void run(char* p) { int i=0; i=system(p); } int main() { char p[5][20]={ "ls", "echo nihao", "gnome-terminal", "terminator", "ps -aux" }; while("nimei") { static int i(0); if(i<5){ thread *pt=new thread(run,p[i]); i+=1; cout<<"I now is :\t"<<i<<endl; } else{ break; } cout<<"Breaking...."<<endl; } cin.get(); return 0; }
知识点２
<li> 关于thread类的内部成
| 关键字 | 详细解释 |
|---|---|
| id | Thread的iｄ |
| native_handle_type | native_handle_type |
| operator= | Move massive Thread |
| get_id | get Thread ID |
| joinable | get if joinable |
| join | join thread |
| detach | detach thread |
| swap | swap thread |
| native_handle | get native handle |
| hardware_concurrency[static] | Detect hardware concurrency (public static function) |
<li> 线程 detach 脱离主线程的绑定，主线程挂了，子线程不报错，子线程执行完自动退出。
<li> 线程 detach以后，子线程会成为孤儿线程，线程之间将无法通信。
知识点３
<li>线程中变量的竞争控制是通过 mutex automic 来实现的
<li>mutex : 互斥量。需要包含头文件 <mutex> 来使用 -->速度慢
<li>atomic 原子变量。需要包含头文件<atomic>来实现 -->速度快，线程安全。
代码３
#include <iostream>
#include <stdlib.h>
#include <thread>
#include <atomic>
using namespace std; int count(0); void run() { for(int i(0);i<1000000;i++) { count++; cout<<"\t"<<i<<"\t"<<count<<"\t"; } } int main() { auto n=thread::hardware_concurrency(); thread* pt[n]; for(int z=0;z<n;z++) { pt[z]=new thread(run); pt[z]->detach(); } cout<<"Finally count is \t"<<count<<endl; cout<<"Used "<<n <<"threads"<<endl; cin.get(); return 0; }
运行结果不是1000000×２．
1 #include <stdlib.h>
2 #include <thread>
3 #include <atomic>
4
5 using namespace std; 6 int count(0); 7 8 void run() 9 { 10 for(int i(0);i<1000000;i++) 11 { 12 count++; 13 cout<<"\t"<<i<<"\t"<<count<<"\t"; 14 } 15 } 16 17 int main() 18 { 19 auto n=thread::hardware_concurrency(); 20 21 thread* pt[n]; 22 for(int z=0;z<n;z++) 23 { 24 pt[z]=new thread(run); 25 pt[z]->detach(); 26 27 } 28 29 cout<<"Finally count is \t"<<count<<endl; 30 cout<<"Used "<<n <<"threads"<<endl; 31 32 33 34 35 cin.get(); 36 return 0; 37 }
运行结果是1000000×２．正确
<li>atomic 声明方式为 atomic<int> a(100); 等号初始化会报错
<li>vim 按ＣＴＲＬ+S 后假死按 ＣＴＲＬ＋q 退出