Lance's Whiteboard

Recursive method calls are the most common causes for stack overflow errors.  Also, if your parameter list contains any object references (any mutable type), then the GC cannot dispose of anything until the entire stack unwinds via completing all recursions or due to an exception.  All that stack walking and unraveling causes excessive overhead on the GC and the CLR.

Instead of forcing the CLR to maintain that stack, you can simply do the stack management yourself within a loop.

I'm not sure if I am explaining this very well, so here is a quick and dirty example:

public string[] GetAllFiles(string path, string fileMask, int max)

{

   Stack<string> folderList = new Stack<string>();

   List<string> fileList = new List<string>();

   string[] currentFolders = null;

   string[] currentFiles = null;

   string thisFolder = null;

   folderList.Push(path);

   while(folderList.Count > 0)

   {

       thisFolder = folderList.Pop();

       currentFiles = Directory.GetFiles(thisFolder, fileMask);

       foreach(string file in currentFiles)

       {

           if(fileList.Count < max)

           {

               fileList.Add(file);

           }

           else

           {

               folderList.Clear();

               break;

           }

       }

       currentFolders = Directory.GetDirectories(thisFolder);

       if(currentFolders != null && currentFolders.Length > 0)

       {

           foreach(string folder in currentFolders)

               folderList.Push(folder);

       }

   }

   return fileList.ToArray();

}