Question

我正在学习boost.thread的基础知识。到目前为止，我可以手动逐个创建每个线程，让它们同时运行。但是，在通过循环创建时，它会依次运行而不是并发运行。

#include <iostream>
#include <boost/thread.hpp>
void workerFunc()
{
  boost::posix_time::seconds workTime(3);
  std::cout << "Worker: Running" << '\n';
  boost::this_thread::sleep(workTime);
  std::cout<< "Worker: Finished" << '\n';
}

int main()
{
  std::cout << "main: startup" << '\n';
  boost::thread workerThread(workerFunc);
  std::cout << "main: waiting for thread" << '\n';
  //these are ok
  boost::thread t(workerFunc), t2(workerFunc), t3(workerFunc), t4(workerFunc);     
  t.join();
  t2.join();
  t3.join();
  t4.join();
  //these are not
  for (int i = 0; i < 2; ++i)
    {
      boost::thread z(workerFunc);
      z.join();
    }
  std::cout << "main:done" << '\n';
  return 0;
}

Answer 1

  for (int i = 0; i < 2; ++i)
    {
      boost::thread z(workerFunc);
      z.join();
    }

您正在开始线程，然后立即等待它完成！

修改

除线程组之外的几种替代黑客之一。

std::vector<boost::thread *> z; for (int i = 0; i < 2; ++i) z.push_back(new boost::thread(workerFunc)); for (int i = 0; i < 2; ++i) { z[i]->join(); delete z[i]; }

Answer 2

好的，我通过别人的问题找到答案，并了解他们的问题：

How to make boost::thread_group execute a fixed number of parallel threads

Answer 3

使用shared_ptr

#include <iostream>
#include <boost/thread.hpp>

void workerFunc()
{
    boost::posix_time::seconds workTime(3);
    std::cout << "Worker: Running" << '\n';
    boost::this_thread::sleep(workTime);
    std::cout << "Worker: Finished" << '\n';
}

int main()
{
    std::cout << "main: startup" << '\n';
    std::vector<std::shared_ptr<boost::thread>> z;

    for (int i = 0; i < 2; ++i) {
        z.push_back(std::make_shared<boost::thread>(workerFunc));
    }

    for (auto t : z) {
        t->join();
    }

    std::cout << "main:done" << '\n';
    return 0;
}

执行

# g++ e.cpp -lboost_thread && ./a.out
main: startup
Worker: Running
Worker: Running
Worker: Finished
Worker: Finished
main:done

如何使用boost.thread同时运行循环创建的多个线程？

3 个答案: