如何在 Boost/C++ 实现中控制线程池

我正在开发一个非常基本的应用程序来自学线程池，并能够使用 boost 在 c++ 中控制它们。

我正在尝试做的是能够发出一个命令，该命令可以暂停/重新启动正在使用的线程池之一。

void printStuff(int x){
while(true){    
std::cout <<" Hi from thread 1 in group " << x << std::endl;        
boost::this_thread::sleep( boost::posix_time::milliseconds(1000) );
}
}
void pstwo(int x){
while(true){    
std::cout <<" Hi from thread 2 in group " << x << std::endl;    
boost::this_thread::sleep( boost::posix_time::milliseconds(1500) );
}
}
int main()
{
boost::asio::io_service io_service;
boost::asio::io_service::work work(io_service);
boost::asio::io_service io_service2;
boost::asio::io_service::work work2(io_service2);
boost::thread_group threads;
boost::thread_group threadsTwo;
for (std::size_t i = 0; i < 2; ++i)
threads.create_thread(boost::bind(&boost::asio::io_service::run, &io_service));
for (std::size_t i = 0; i < 2; ++i)
threadsTwo.create_thread(boost::bind(&boost::asio::io_service::run, &io_service2));
io_service.post(boost::bind(printStuff,1));
io_service.post(boost::bind(pstwo,1));
io_service2.post(boost::bind(printStuff,2));
io_service2.post(boost::bind(pstwo,2));
boost::this_thread::sleep( boost::posix_time::milliseconds(10000));
io_service.stop();
std::cout<<"------------------"<<std::endl;
boost::this_thread::sleep( boost::posix_time::milliseconds(10000));
io_service.run();    
io_service2.stop();
std::cout<<"-----------------"<<std::endl;
boost::this_thread::sleep( boost::posix_time::milliseconds(10000));
io_service.stop();
threads.join_all();
threadsTwo.join_all();
return 0;
}

对 io_service.stop 的调用实际上不会停止线程池中的任何线程。