Get value from dictionary one by one in sequence

I need to process N files at a time, So I've stored all files information in Dictionary with Filename, Size, and SequenceNo, Now I've to select 5 files from that Dictionary and process that file, meanwhile if the process for any file completed then it will select another 1 file from that dictionary.

 

For Example :

 

If I've 10 Files in the dictionary and I select the first 5 files File 1, File 2, File 3, File 4, File 5 from the dictionary and process it. If process File 3 is completed then the process for File 6 should be started.

 

we are working in a team and we have also posted the same question in StackOverflow community but didn't get the expected solution.

 

So Help me.

Thank You.