Question

I want to create method for getting file Stream by file name and expect that my method can work with multithreading but it fails… My code here:

public static class FileHelper
{
   private static object lockObject = new object();
   private static Stream fileStream;

    public static Stream GetFileStream(string filename)
    {
        if (fileStream != null)
            return fileStream;

        lock(lockObject)
        {
            if (fileStream != null)
            {
                return fileStream;
            }

            fileStream = File.OpenRead(filename);
            return fileStream;
        }
    }  
}

Answer 1

Possibly what you are looking for is a thread-safe singleton pattern implementation. Here is a good article of how to do it in java, but it’s pretty much the same in C#.

http://www.ibm.com/developerworks/java/library/j-dcl/index.html