Why is List not thread-safe?

Question

From the following site:

http://crfdesign.net/programming/top-10-differences-between-java-and-c

Unfortunately, List<> is no

Answer 1

The race-condition possibility JaredPar mentions is the scary consequence of relying on Vector's supposed thread-safety. It's the sort of thing that results in the "every ninth Tuesday the app does something weird"-sort of defect report that will drive you insane.

There are a number of truly thread-safe collections coming in .Net 4, with an interesting side-effect that they allow single-threaded modification of the collection while enumerating, but there's a performance hit that comes with thread-safety, sometimes a pretty big one.

So the logical thing for a framework developer to do is keep the class as performant as possible for the 95% of users who probably won't be doing threading and rely on those who do multi-thread to know what they have to do to keep it safe.