Error writing to file

Question

The error occurs randomly, my guess is when there is heavy traffic, but i'm having a hard time replicating it. This functionality runs everytime a business transaction is initiated.

Error: System.IO.IOException: The process cannot access the file '' because it is being used by another process. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)

private void writeToTrafficLogFile(string data, string filePath)
    {
        try
        {
            StreamWriter logWriter;

            if (!File.Exists(filePath))
            {
                logWriter = new StreamWriter(filePath);
            }
            else
            {
                logWriter = File.AppendText(filePath);
            }

            logWriter.WriteLine(DateTime.Now);
            logWriter.WriteLine(data);
            logWriter.WriteLine();

            logWriter.Close();

        }
        catch (Exception error) {
            sendLoggingErrorEmail(error, "Error Writing writeToTrafficLogFile", "Error Writing writeToTrafficLogFile.\r\n");
        }
    }

    #endregion
}

Answer 1

It might be easier and more bulletproof to switch to an existing, well tested logging solution. Several exist, have a look at dotnetlogging.com where dozens are listed. I can't recommend any, right now I am stuck with log4net but I can't recommend it.

Answer 2

You're probably calling that from multiple threads at the same time...

There are two possible solutions:

A: Create a single thread that writes to the log file from a string that other threads can write to. -- Clarification edit: Have a class with code like

public static List<string> logme = new List<string>();
// Launch LogLoop as a thread!
public static void logloop()
{
     while (true)
     {
          while (logme.Count > 0)
          {
              File.AppendAllText("log.txt", logme[0] + "\r\n");
              logme.RemoveAt(0);
          }
          Thread.Sleep(500);
     }
}
// Oh, and whenever you want to log something, just do:
logme.add("Log this text!");

B: Use a Lock on the log writer.