OpenMP从磁盘顺序读取和并行处理

Question

There is my question:

I have many files (more than 1000) of the same size (several Mb). I have to read them and extract some information. This step of the information extraction requires some time, so I can use (at least I hope so) this time to read another file. What I try to do is:

#pragma omp parallel for
for (int i=0; i<FilesCount; i++)
{
    myData Data;

    #pragma omp critical
    {
        Data.ReadDataFromFile (FileNames[i]);
    }

    //Operate with the Data and extract some information
}

It doesn't work as I expect. I also tried to use:

#pragma omp ordered

and the result is the same - only one thread is used. Other OpenMP stuff works fine. Maybe the problem is that I use fstream for the reading?

What is the problem with it and how to do that correctly?

Answer 1

Everything in a block marked with

#pragma omp critical

will be executed by one thread at a time only. All other threads have to wait until the current thread leaves that block.

Section about 'critical' in an OpenMP tutorial