How to implement asynchronous file creation?

Question

C++ / C#

The task is very simple, the graphic files in the folder are sorted and for each file its thumbnails are created for several sizes. The task runs for a long time. How can it be rewritten with an asynchronous approach, and does it make sense?

public void MakeCopys(string path)
{
  var di = new DirectoryInfo(path);
  foreach (var file in di.GetFiles("*.jpg"))
  {
    MakeThumbnails(file);
  }
}

public void MakeThumbnails(FileInfo file)
{
  MakeThumbnail(file, 75, file.FullName + ".lg.jpg");
  MakeThumbnail(file, 50, file.FullName + ".md.jpg");
  MakeThumbnail(file, 25, file.FullName + ".sm.jpg");
}

public void MakeThumbnail(FileInfo file, int size, string name)
{
  // код генерации уменьшенной копии
}

Answer 1

Use Parallel.For

Answer 2

can it be like this

public void MakeCopys(string path)
{
var di = new DirectoryInfo(path);
Parallel.ForEach(di.GetFiles("*.jpg"),  new ParallelOptions {MaxDegreeOfParallelism = 10}, (file) =>
{
MakeThumbnails(file);
});
}