使静态类成员在OpenMP中成为线程私有 [英] Making static class members threadprivate in OpenMP

问题描述

我正在使用C ++中的OpenMP，并尝试使一个threadprivate类的静态成员变量. 一个非常简化的示例代码示例如下所示:

I'm working with OpenMP in C++ and try to make a static member variable of a class threadprivate. A very simplified example code example looks like this

#include <omp.h>
#include<iostream>

template<class numtype>
class A {
public:
    static numtype a;
    #pragma omp threadprivate(a)
};

template<class numtype>
numtype A<numtype>::a=1;

int main() {

 #pragma omp parallel
 {

  A<int>::a = omp_get_thread_num();

  #pragma omp critical
  {
    std::cout << A<int>::a << std::endl;
  }
 } /* end of parallel region */    
}

如果我尝试使用gcc编译器编译此代码，则会收到错误消息

If I try to compile this code with the gcc compiler I get the error message

threadprivatetest.cpp:8:27:错误:未声明'a'

threadprivatetest.cpp:8:27: error: ‘a’ has not been declared

#pragma omp threadprivate(a)

#pragma omp threadprivate(a)

如果使用Intel C ++编译器，则代码可以编译并运行. 当我搜索错误时，我已经发现了该问题的一些答案.

The code compiles and runs if I use the Intel C++ compiler. When I searched for the error I already found that some answers to this problem.

使用OpenMP threadprivate指令C ++ STL类型的静态实例上

但是，因为这是我要使用gcc编译器的大型项目，并且链接的文章已经有6年的历史了. 今天是否有可能用gcc编译器来编译此类代码? 有人可以详细解释旧帖子中提到的解决方法，因为我听不懂吗?

However since this is for a larger project to where I want to use the gcc compiler and since the linked post is already 6 years old. Is there a possibility do compile such code with the gcc compiler today? Could somebody explain the work around mentioned in the old post in detail, because i wasn't able to understand it?

感谢您的帮助！

推荐答案

以下代码可以工作，并且可以完成我最初打算做的事情.

The following code works and does what I originally intended to do.

#include <omp.h>
#include<iostream>

template<class numtype>
class A {
public:
  static numtype* a;
  #pragma omp threadprivate(a)
};

template<class numtype>
numtype* A<numtype>::a=nullptr;

template class A<int>;

int main() {
  #pragma omp parallel
  {

    A<int>::a = new int;
    *A<int>::a = omp_get_thread_num();

    #pragma omp critical
    {
      std::cout << *A<int>::a << std::endl;
    }
  } /* end of parallel region */
}

您可以看到不同之处在于，a现在是指向numtype的指针，而不是numtype.

As you can see the difference is that a is now a pointer to numtype instead of numtype.

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