std::thread::detach

void detach();

Detaches the thread represented by the object from the calling thread, allowing them to execute independently from each other.

将本线程从调用线程中分离出来，允许本线程独立执行。(但是当主进程结束的时候，即便是detach（）出去的子线程不管有没有完成都会被强制杀死)

例子：

#include <iostream>
#include <thread>
#include <vector>
#include <ctime>
#include <fstream>
using namespace std;
//delay(n) 延时n秒  
void delay(double sec)  
{  
    time_t start_time, cur_time; // 变量声明  
    time(&start_time);  
    do {  
        time(&cur_time);  
        }while((cur_time - start_time) < sec );  
};  
void show(int n){
	ofstream fout("detach.txt");
	if(!fout.is_open())
		cout<<"open failed!"<<endl;
	while(n>0){
		fout<<"1currentThread is "<<pthread_self()<<",Now n is "<<n<<endl;
		delay(0.2);
		n--;
	}
	fout<<"ok"<<endl;
	fout.close();
}
int main()
{
	cout<<"main starts"<<endl;
	thread t(show,100);
	t.detach();
	delay(1);
	cout<<"main complete!"<<endl;
}

运行截图:

可以看出，当进程结束的时候，即便detach没有完成任务也会被强制杀死。

Both threads continue without blocking nor synchronizing in any way. Note that when either one ends execution, its resources are released.

两个线程不会堵塞也不会同步，注意他们任一一个结束的时候，所持有的资源将会被释放。

After a call to this function, the thread object becomes non-joinable and
can be destroyed safely.

调用该方法后，该线程对象变得不可连接以及可以安全地销毁。

例子:

Parameters

none

Return value

none

Example

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#include <iostream>       // std::cout
#include <thread>         // std::thread, std::this_thread::sleep_for
#include <chrono>         // std::chrono::seconds
 
void pause_thread(int n) 
{
  std::this_thread::sleep_for (std::chrono::seconds(n));
  std::cout << "pause of " << n << " seconds ended\n";
}
 
int main() 
{
  std::cout << "Spawning and detaching 3 threads...\n";
  std::thread (pause_thread,1).detach();
  std::thread (pause_thread,2).detach();
  std::thread (pause_thread,3).detach();
  std::cout << "Done spawning threads.\n";

  std::cout << "(the main thread will now pause for 5 seconds)\n";
  // give the detached threads time to finish (but not guaranteed!):
  pause_thread(5);
  return 0;
}

Output (after 5 seconds):

Spawning and detaching 3 threads...
Done spawning threads.
(the main thread will now pause for 5 seconds)
pause of 1 seconds ended
pause of 2 seconds ended
pause of 3 seconds ended
pause of 5 seconds ended

Data races

The object is modified.

Exception safety

Basic guarantee: if an exception is thrown by this member function, the thread object is
left in a valid state.

If the call fails, a system_error exception is thrown:

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//写的错误或者不好的地方请多多指导，可以在下面留言或者点击左上方邮件地址给我发邮件，指出我的错误以及不足，以便我修改，更好的分享给大家，谢谢。

转载请注明出处：http://blog.csdn.net/qq844352155

author:天下无双

Email:coderguang@gmail.com

2014-9-3

于GDUT

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