Static instance of DataContractJsonSerializer - good or bad design?

I have a class which I am using to serialize and deserialize business objects in an ASP.NET application.

The class contains this static variable:

private static DataContra开发者_如何学JAVActJsonSerializer m_serializer = new DataContractJsonSerializer(typeof(MyBusinessObject));

... and two static methods in the class:

public static string SerializeJson(MyBusinessObject bo);

public static MyBusinessObject DeserializeJson(string json);

In these methods, I use the static DataContractJsonSerializer object (m_serializer) to perform serialization and deserialization. This way, I do not need to instantiate a DataContractJsonSerializer instance for each call.

Is it correct design to use a static variable in this way?

Could I run into any problems if I get lots of hits on the serialize/deserialize code?

It will be called from website which gets 100s of concurrent hits every second.

As Alex mentioned, you can run into problems - the documentation of the class states that it's not thread safe (at least not the methods used to read / write objects). By doing a quick look on reflector it seems like the serialization can actually work (assuming you're not serializing the same object at the same time in different threads, that's a whole new can of worms), but since it's an internal implementation detail, it's possible that in a new version of the framework the class has some change (i.e., optimization) and that won't be true anymore.

An option which you can consider is to have a pool of serializers which can be reused. Your code would take one serializer from the pool, use it to serialize / deserialize, and then return it to the pool. This way you get the benefit of reusing the instances, but without the risk of using a thread-unsafe class in multiple threads.

Finally, have you verified that the creation of the serializers is indeed a problem (i.e., by profiling)? It's possible that the time it takes is negligible in your scenario, and using some sort of reuse would just add unnecessary complication to your code.