Thread safety and class methods

Hey guys,

using passenger, is it possible that there could be thread safety issues
when executing a class method on a model?

I am seeing some weird data in some of my model instances and I think it
may be to do with concurrent processing of a class method in a model.

Is this possible, that variables get shared between all threads of
execution, when you are accessing a class method?

#example
def self.somemethod

end