File sharing for a separate writer and reader application in C#

Question

I have 2 applications, one is writing to a file, and the other one reads the file. It's a log file, so the writer will be logging until the program stops, while the reader could be invoked any time to get the content of the file.

I thought that when the writer opens the file with FileShare.Read, the reader would be able to access the file, but it produces an error saying that the file is being used by another process.

Writer Application:

FileStream fs = new FileStream("file.log", FileMode.Open, FileAccess.Write, FileShare.Read); BinaryWriter writer = new BinaryWriter(fs);

Reader Application:

BinaryReader reader = new BinaryReader(File.OpenRead("file.log"));

How do I prevent this error?

any final solution with full source code sample working about it ? — Kiquenet, Aug 21 '13 at 10:03

score 0 · Answer 1 · answered Jul 30 '13 at 02:30

0

Can you try specifying FileShare.Read while reading the file also? Instead of directly using File.OpenRead use FileStream with this permission.

Also, for logging, you can use log4Net or any other free logging framework which manages logging so efficiently and we do not have to manage writing to files.

answered Jul 30 '13 at 02:30

appcoder

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1
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Thanks. I used the FileStream and it worked. I cannot use log4Net because I need to write binary files and need to be in a ring buffer. – gemini Aug 01 '13 at 20:55
Glad it worked. Please accept this as answer if you feel its right – appcoder Aug 02 '13 at 01:16

score 0 · Answer 2 · answered Jul 30 '13 at 02:53

o read a locked file you are going to need to provide more flags for the FileStream.

Code such as below.

using (var reader = new FileStream("d:\\test.txt", FileMode.Open, FileAccess.Read,FileShare.ReadWrite))
{
            using (var binary = new BinaryReader(reader))
            {
                //todo: add your code
                binary.Close();
            }
            reader.Close();
}

This would open the file for reading only with the share mode of read write. This can be tested with a small app. (Using streamreader\write instead of binary)

    static Thread writer,
                  reader;

    static bool abort = false;

    static void Main(string[] args)
    {

        var fs = File.Create("D:\\test.txt");
        fs.Dispose();

        writer = new Thread(new ThreadStart(testWriteLoop));
        reader = new Thread(new ThreadStart(testReadLoop));
        writer.Start();
        reader.Start();

        Console.ReadKey();
        abort = true;
    }

    static void testWriteLoop()
    {
        using (FileStream fs = new FileStream("d:\\test.txt", FileMode.Open, FileAccess.Write, FileShare.Read))
        {
            using (var writer = new StreamWriter(fs))
            {
                while (!abort)
                {
                    writer.WriteLine(DateTime.Now.ToString());
                    writer.Flush();
                    Thread.Sleep(1000);
                }
            }
        }
    }

    static void testReadLoop()
    {
        while (!abort)
        {
            Thread.Sleep(1000);
            using (var reader = new FileStream("d:\\test.txt", FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
            {
                using (var stream = new StreamReader(reader))
                {
                    Console.WriteLine(stream.ReadToEnd());
                    stream.Close();

                }
                reader.Close();
            }
        }
    }

I realize the example above is pretty simple but the fact still remains that the "testWriteLoop" never releases the lock.

Hope this helps

Thank you. Yes, that was simple but it was just what I needed. :) Problem is solved. :) — gemini, Aug 01 '13 at 20:56

File sharing for a separate writer and reader application in C#

2 Answers2