OpenMP - Serialize for-loop在并行区域中包含并行for循环(OpenMP - Serialise for-loop in Parallel Region which Contains Parallel for-loop)

 我问这个问题一个非常相似的问题，但那里只有一个答案，但对我来说并没有用。 
 
 我在main()有一个并行区域，它带有一个调用函数new_value()的for循环： 
 
int main(int argc, char** argv)
{
    omp_set_num_threads(4);

#pragma omp parallel default(shared) private(...)
{
    for(int i = 0; i < MAX_VALUE; i++)
        new_value(...);
}

    return 0;
}
 
 new_value()看起来像： 
 
void new_value(...)
{
#pragma omp for schedule(static, chunk_width)
    for(int i = 0; i < N; i++)
        arr[i] = update();
}
 
 我遇到的问题是我不希望main()的for循环被并行化（即总共运行MAX_VALUE * 4次）。 
 
 我基本上希望这个循环能够连续运行，但new_value()的for循环要使用四个线程运行。 
 
 我在循环之前尝试了#pragma omp single ，但它导致程序死锁或挂起某些东西。 我也尝试了由已经链接的线程提示的嵌套并行方法，但是我得到了相同的结果。 
 
 任何解决方案将不胜感激。 

I'm asking a very similar question to this chap but there is only one answer there and it hasn't proved useful for me.
 
I have a parallel region in main() with a for-loop which calls the function new_value():
 
int main(int argc, char** argv)
{
    omp_set_num_threads(4);

#pragma omp parallel default(shared) private(...)
{
    for(int i = 0; i < MAX_VALUE; i++)
        new_value(...);
}

    return 0;
}
 
And new_value() looks like:
 
void new_value(...)
{
#pragma omp for schedule(static, chunk_width)
    for(int i = 0; i < N; i++)
        arr[i] = update();
}
 
The issue I am having is that I do not want the for-loop in main() to be parallelised (i.e. ran MAX_VALUE * 4 times in total).
 
I essentially want that one loop to be ran serially but the for-loop in new_value() to be ran with four threads.
 
I tried #pragma omp single before the loop but it caused the program to deadlock or hang on something. I also tried the nested parallelism approach as suggest by the already linked thread but I got the same result.
 
Any solutions would be appreciated.

原文：https://stackoverflow.com/questions/47475715