Bug or wrong code?

Question

Hi,

 

I've tried to use PLINQ to load and evaluate images from files. So I use Select at first to get Image from file and then Where with condition about Image. Well, maybe it's unusual, but I think it's semantically and surely syntactically correct (see bellow).

What's strange - Select was called twice for each file (found by including Console.WriteLine in Select method). Firstly I thought that something wrong with threads but even in case of degree of paralellism = 1 (as shown in code) the result was same. Without AsParallel this code works perfectly.

 

var largeImages = fileNames.AsParallel(1).Select(fName =>

{

var fileImg = new { fName, img = Image.FromFile(fName)};

Console.WriteLine("Loaded file: {0} on thread {1}", Path.GetFileName(fileImg.fName), Thread.CurrentThread.ManagedThreadId);

return fileImg;

}).Where(fileImg =>

{

return fileImg.img.Width > Width || fileImg.img.Height > Height;

});

foreach (var fileImg in largeImages)

{

// do something with images

}

 

 

So my question is - is it bug in AsParallel (or some lower level) implementation or is my code wrong? For the second case - could you tell me what I'm doing wrong?

 

TIA. Best regards,

Vlada B.