可以将std :: atomic与OpenMP安全使用 [英] Can std::atomic be safely used with OpenMP

问题描述

我目前正在尝试学习使用OpenMP的知识，我有一个问题. 这样做是否安全:

I'm currently trying to learn ow to use OpenMP and I have a question. Is it safe to do something like that :

  std::atomic<double> result;
  #pragma omp parallel for
  for(...)
  {
  result+= //some stuff;
  }

或者我应该使用:

  double result;
  #pragma omp parallel for
  for(...)
  {
    double tmp=0;
    //some stuff;
    #pragma omp atomic
    result+=tmp;
  }

谢谢！

我知道使用数组处理最简单的方法，但是我问是因为我很好奇

Edit : I know the most simple way to handle that is using an array, but Im asking because I'm curious

推荐答案

正式地，没有.在实践中，可能.

Officially, no. In practice, probably.

OpenMP 5.0规范说:

虽然预期OpenMP规范的未来版本将解决以下功能，但当前使用它们可能会导致未指定的行为.

While future versions of the OpenMP specification are expected to address the following features, currently their use may result in unspecified behavior.

• 并发性

• Concurrency

对标准库的添加

C ++ 11库

但是，取决于您使用的OpenMP运行时的实现，可能可以.实际上，LLVM OpenMP运行时甚至使用 std::atomic 来实现一些OpenMP规范.

However, depending on the implementation of the OpenMP runtime you use, it might be alright. In fact, the LLVM OpenMP runtime even uses std::atomic to implement some of the OpenMP specification.

最安全的选择是仅使用OpenMP提供的内容.使用std::atomic可以执行的任何操作，也应该仅使用OpenMP即可实现.

The safest option though is to stick with using only what OpenMP provides. Anything you can do using std::atomic you should also be able to achieve using only OpenMP.

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