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c#multithreadingfilestream

Does FileShare.ReadWrite imply thread-safe writing to a file in C#

using (FileStream fs =  File.Open(@"C:\logs\log1.txt",FileMode.Append,
              FileAccess.Write, FileShare.ReadWrite))
{

    using (StreamWriter w = new StreamWriter(fs))
    {
        w.WriteLine(logMessage);
        w.Flush();
        isSuccessful = true;
    }
}

In code above, I am instantiating a FileStream object so the file is opened in FileShare.ReadWrite mode.

My Question: Does this mean that the code that writes a line to the opened file is going to be thread-safe, Or FileShare.ReadWrite implies something other than thread-safe?

Solution

  • No, it just allows multiple processes to write to the file. You will still need to implement some locking mechanism on the File.Write operation if you want it to be thread safe.

    Check out the answer to this question for more info: What is the fastest and safest way to append records to disk file in highly loaded .ashx http handler?