Comments on: Using the Singleton Pattern http://www.jaltiere.com/index.php/2008/03/26/using-the-singleton-pattern/ .NET Software Development Mon, 14 Nov 2011 14:58:38 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Jack Altiere http://www.jaltiere.com/index.php/2008/03/26/using-the-singleton-pattern/comment-page-1/#comment-24260 Jack Altiere Mon, 31 Mar 2008 13:26:19 +0000 http://www.jaltiere.com/?p=42#comment-24260 @Arnon, You are right that the lazy initialization isn't necessary, and you're solution will work. Lazy initialization is nice if your constructor does anything time consuming. As for the point on efficiency....I'll grant you the point that locking is not efficient, but some performance tests were done in the link that Peter pointed out. The author of that article has a locking solution very similiar to the one I came up with, and in his benchmark he was able to acquire the singleton a billion times in under 40 seconds. To me, that performance is more than good enough. I do like your idea with generics, I might have to explore that a little and come back with a follow up post. @Arnon,

You are right that the lazy initialization isn’t necessary, and you’re solution will work. Lazy initialization is nice if your constructor does anything time consuming.

As for the point on efficiency….I’ll grant you the point that locking is not efficient, but some performance tests were done in the link that Peter pointed out. The author of that article has a locking solution very similiar to the one I came up with, and in his benchmark he was able to acquire the singleton a billion times in under 40 seconds. To me, that performance is more than good enough.

I do like your idea with generics, I might have to explore that a little and come back with a follow up post.

]]> By: Arnon http://www.jaltiere.com/index.php/2008/03/26/using-the-singleton-pattern/comment-page-1/#comment-24246 Arnon Mon, 31 Mar 2008 07:22:00 +0000 http://www.jaltiere.com/?p=42#comment-24246 You implementation with the mutex while thread safe is not very efficient. Singletons are instantiated once but used many times so it is better to only lock if the instance is null (and then check again since potentially multiple threads can get there. plus you'd also have to mark the instance volatile in that case) In any event, if you don't need the lazy initialization you can just do public static readonly MySingleton instance = new MySingleton() and the CLR will take care of everything for you. Lastly, if you are going to implement a singleton it is better to implement a "template" one using Generics and then just initialize it with the type you want. This is a better approach from the SRP perspective Arnon You implementation with the mutex while thread safe is not very efficient.
Singletons are instantiated once but used many times so it is better to only lock if the instance is null (and then check again since potentially multiple threads can get there. plus you’d also have to mark the instance volatile in that case)
In any event, if you don’t need the lazy initialization you can just do
public static readonly MySingleton instance = new MySingleton()
and the CLR will take care of everything for you.

Lastly, if you are going to implement a singleton it is better to implement a “template” one using Generics and then just initialize it with the type you want. This is a better approach from the SRP perspective

Arnon

]]> By: Jack Altiere http://www.jaltiere.com/index.php/2008/03/26/using-the-singleton-pattern/comment-page-1/#comment-24084 Jack Altiere Thu, 27 Mar 2008 12:35:57 +0000 http://www.jaltiere.com/?p=42#comment-24084 @Hyle, That is another example of how to do it. In that article, they use a method rather than a property to get an instance to the singleton. It works either way. @Hyle,

That is another example of how to do it. In that article, they use a method rather than a property to get an instance to the singleton. It works either way.

]]> By: Hyle http://www.jaltiere.com/index.php/2008/03/26/using-the-singleton-pattern/comment-page-1/#comment-24046 Hyle Thu, 27 Mar 2008 06:11:47 +0000 http://www.jaltiere.com/?p=42#comment-24046 Here is another perspective: http://en.csharp-online.net/Singleton_design_pattern Here is another perspective:

http://en.csharp-online.net/Singleton_design_pattern

]]> By: Jack Altiere http://www.jaltiere.com/index.php/2008/03/26/using-the-singleton-pattern/comment-page-1/#comment-23985 Jack Altiere Wed, 26 Mar 2008 19:02:19 +0000 http://www.jaltiere.com/?p=42#comment-23985 @Peter: That is a good article, he goes into much more detail than I did with different ways to do it. I will have to disagree about it being a "simpler" implementation, especially since my thread-safe version is basically the same thing as his second example. (in fact, they are almost identical) @Peter:

That is a good article, he goes into much more detail than I did with different ways to do it. I will have to disagree about it being a “simpler” implementation, especially since my thread-safe version is basically the same thing as his second example. (in fact, they are almost identical)

]]> By: Peter Ritchie http://www.jaltiere.com/index.php/2008/03/26/using-the-singleton-pattern/comment-page-1/#comment-23983 Peter Ritchie Wed, 26 Mar 2008 18:51:54 +0000 http://www.jaltiere.com/?p=42#comment-23983 See http://www.yoda.arachsys.com/csharp/singleton.html for much simpler implementations of a thread-safe singleton in C#. See http://www.yoda.arachsys.com/csharp/singleton.html for much simpler implementations of a thread-safe singleton in C#.

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