Double-checked locking in .NET

.net multithreading paradigms double-checked-locking
erikkallen picture erikkallen · Dec 27, 2008 · Viewed 52.9k times · Source

I came across this article discussing why the double-check locking paradigm is broken in Java. Is the paradigm valid for .NET (in particular, C#), if variables are declared volatile?

Answer

Jon Skeet picture Jon Skeet · Dec 27, 2008

Double-checking locking now works in Java as well as C# (the Java memory model changed and this is one of the effects). However, you have to get it exactly right. If you mess things up even slightly, you may well end up losing the thread safety.

As other answers have stated, if you're implementing the singleton pattern there are much better ways to do it. Personally, if I'm in a situation where I have to choose between implementing double-checked locking myself and "lock every time" code I'd go for locking every time until I'd got real evidence that it was causing a bottleneck. When it comes to threading, a simple and obviously-correct pattern is worth a lot.

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