Global.asax singleton

Question

Please help me decide whether this should be good or bad idea to declare a Singleton variable in Global.asax file. (It is not actually singleton pattern, I just want to make sure that only one instance is created for this class.)

public class Global : System.Web.HttpApplication
{
 private HTML5Video dailyHtml5Video;
 public HTML5Video DailyHtml5Video
 {
 get
 {
 if (dailyHtml5Video==null)
 {
 dailyHtml5Video = new HTML5Video();
 }
 return dailyHtml5Video;
 }
 }
}

Will this cause any thread-related issues or other possible issues?

Answer 1

It is not thread safe. You can use Lazy type to create a variable of HTML5Video in a thread safe manner.

Lazy<HTML5Video> dailyHtml5Video = new Lazy<HTML5Video>(() => new HTML5Video());
public HTML5Video DailyHtml5Video
{
 get {return dailyHtml5Video.Value;}
}

You can read about different versions of Singleton pattern here http://csharpindepth.com/articles/general/singleton.aspx