为什么openMP取消构造不取消工作共享区域? [英] Why is openMP cancellation construct not cancelling the worksharing region?

问题描述

i期望变量"i"将达到最大值11，然后将取消"for"工作共享区域，代码为:

i was expecting that variable "i" will reach a maximum value of 11 and then the "for" worksharing region will be cancelled ,code is:

omp_set_num_threads(11);

#pragma omp parallel
{

    #pragma omp for
    for(i=0;i<9999;i++){
        printf("%d by %d \n",i,omp_get_thread_num());

        if(i>11)   //2
        {
            #pragma omp cancel for 
        }

    }//for

}//parallel omp pragma

但是变量i的最大值为9998，我想这意味着工作共享区域没有被取消.

but the variable i was holding max value of 9998 which i suppose means that worksharing region was not cancelled.

推荐答案

默认情况下，取消功能处于禁用状态，主要是出于性能方面的考虑.您必须通过将 cancel-var ICV设置为true来专门启用取消支持.唯一的方法是将环境变量OMP_CANCELLATION设置为true，例如:

Cancellation is disabled by default, mostly for performance reasons. You must specifically enable cancellation support by setting the cancel-var ICV to true. The only way to do so is to set the environment variable OMP_CANCELLATION to true, e.g.:

$ OMP_CANCELLATION=true ... ./omp_executable ...

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