并行while循环使用OpenMP [英] Parallelize while loop with OpenMP

问题描述

我有一个非常大的数据文件，并且在该数据文件中的每个记录具有4行。我写了一个非常简单的C程序来分析这种类型的文件，并打印出一些有用的信息。该方案的基本思想是本

I have a very large data file, and each record in this data file has 4 lines. I have written a very simple C program to analyze files of this type and print out some useful information. The basic idea of the program is this.

int main()
{
  char buffer[BUFFER_SIZE];
  while(fgets(buffer, BUFFER_SIZE, stdin))
  {
    fgets(buffer, BUFFER_SIZE, stdin);
    do_some_simple_processing_on_the_second_line_of_the_record(buffer);
    fgets(buffer, BUFFER_SIZE, stdin);
    fgets(buffer, BUFFER_SIZE, stdin);
  }
  print_out_result();
}

这当然是留下了一些细节（理智/错误检查等），但是这是不相关的问题。

This of course leaves out some details (sanity/error checking, etc), but that is not relevant to the question.

该程序工作正常，但我的工作数据文件是巨大的。我想我会尝试通过并行使用OpenMP循环加快程序。有点搜索之后，虽然，它看起来OpenMP的只能处理为回路，其中的迭代次数是事先知道。由于我不知道这些文件的大小事前，甚至简单的命令，比如 WC -l <​​/ code>需要较长的时间来运行，我怎么能并行这个计划？

The program works fine, but the data files I'm working with are huge. I figured I would try to speed up the program by parallelizing the loop with OpenMP. After a bit of searching, though, it appears that OpenMP can only handle for loops where the number of iterations is know beforehand. Since I don't know the size of the files beforehand, and even simple commands like wc -l take a long time to run, how can I parallelize this program?

推荐答案

您确认您的过程实际上是CPU密集型的，而不是I / O密集​​型？您code看起来很像I / O密集​​型code，这将受益于并行一无所获。

Have you checked that your process is actually CPU-bound and not I/O-bound? Your code looks very much like I/O-bound code, which would gain nothing from parallelization.

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