since you're attempting to execute a print request (from our sample server which is not intended to be utilized by production applications :)), what is the benefit of passing the geometry and attributes of over 1000 features?
come to think of it, even in an interactive webpage its not possible for end users to work with that many features.
it would probably be a lot more appropriate to work with a dynamicMapServiceLayer to draw the same information. have you seen our sample which demonstrates how to draw the same data using this technique and use a featureLayer in selection only mode?
we also have an article in the conceptual help related to considerations when working with a large number of graphics.