IOException: The process cannot access the file 'file path' because it is being used by another process in Console Application in C#

Question

I am running Console_Application-A in which I am calling another Console_Application-B (in which I am creating log file for Error/Exception).

But when I am running Console_Application-B individually its working properly but when I am running Console_Application-A at that time I am getting an Exception when Application need to write an Error in log file.(Error.txt).

IOException: The process cannot access the file 'Error.txt' because it is being used by another process

please guide me in this issue.

Code for Writing Error log

public static bool IsFileLocked(FileInfo file)
{
 FileStream stream = null;
 try
 {
 stream = file.Open(FileMode.Open, FileAccess.Read, FileShare.None);
 }
 catch (IOException)
 {
  return true;
 }
 finally
 {
  if (stream != null)
  stream.Close();
  }
  return false;
 }

---

catch (Exception e)
{
    string filePath =Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location) + "\\Error.txt";

FileInfo FInfo = new FileInfo(filePath);
var FileState = IsFileLocked(FInfo);

while (FileState){
FileState = IsFileLocked(FInfo);
}
if (!FileState){
using (StreamWriter writer = new StreamWriter(filePath, true))
{
 writer.WriteLine("Message :" + e.Message + "<br/>" + Environment.NewLine + "StackTrace :" + e.StackTrace +"" + Environment.NewLine + "Date :" + DateTime.Now.ToString());
 writer.WriteLine(Environment.NewLine + "-----------------------------------------------------------------------------" + Environment.NewLine);
writer.Dispose();
}
}
}

Answer 1

There is no need first to check if the file is locked and then access it, as between the check and the access some other process may still get a lock on the file.

using System;
using System.IO;

class DirAppend
{
    public static void Main()
    {
        using (StreamWriter w = File.AppendText("log.txt"))
        {
            Log("Test1", w);
            Log("Test2", w);
        }

        using (StreamReader r = File.OpenText("log.txt"))
        {
            DumpLog(r);
        }
    }

    public static void Log(string logMessage, TextWriter w)
    {
        w.Write("\r\nLog Entry : ");
        w.WriteLine("{0} {1}", DateTime.Now.ToLongTimeString(),
            DateTime.Now.ToLongDateString());
        w.WriteLine("  :");
        w.WriteLine("  :{0}", logMessage);
        w.WriteLine ("-------------------------------");
    }

    public static void DumpLog(StreamReader r)
    {
        string line;
        while ((line = r.ReadLine()) != null)
        {
            Console.WriteLine(line);
        }
    }
}

Source - https://msdn.microsoft.com/en-us/library/3zc0w663(v=vs.110).aspx