Remove duplicate lines in a file that is being used by another thread

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Remove duplicate lines in a file that is being used by another thread



I have a file called example.txt and I want to remove the duplicate lines in this file using my C# application.


example.txt



My application is multi-threaded, and more than one thread are already accessing the file example.txt


example.txt



I've tried a lot of methods but all of them returns the error:



The file 0 is already being used by another process.





If the file is in use by another thread, there isn't much you can do. Attempting to read/write by multiple threads at the same time would cause data corruption. I'd implement a lock () mechanism.
– FrankerZ
Aug 8 at 7:30


lock ()





@FrankerZ - I've tried lock(locker) File.WriteAllLines(filepath, File.ReadLines(filepath) .Where(line => previousLines.Add(line))); but it is giving the same problem.
– MatrixCow08
Aug 8 at 7:52


lock(locker) File.WriteAllLines(filepath, File.ReadLines(filepath) .Where(line => previousLines.Add(line)));





Add a .ToArray() after the .Where().
– FrankerZ
Aug 8 at 8:03


.ToArray()


.Where()





@FrankerZ - File.ReadLines(filepath).Where().ToArray that can't work
– MatrixCow08
Aug 8 at 8:11


File.ReadLines(filepath).Where().ToArray





Ok, I got it to work but still the same results :/
– MatrixCow08
Aug 8 at 8:13




1 Answer
1



You should be able to do this by specifying file share in your file stream


FileStream s2 = new FileStream(name, FileMode.Open, FileAccess.Read, FileShare.Read);



https://msdn.microsoft.com/en-us/library/system.io.fileshare(v=vs.110).aspx





How can this be threads-safe?
– MatrixCow08
Aug 8 at 7:57





It allows you to open file by another process, you still need to implement locking mechanism
– sziszu
Aug 8 at 8:00





But why did you make it FileStream s2, why not New FileStream so it can be called immediately on a method?
– MatrixCow08
Aug 8 at 8:01


FileStream s2


New FileStream






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