We use the various ranges a user provides to create splits. Those get read when the job is submitted by the client. On the client side, those ranges are used to get all of the splits, and then the job is started. If the configuration is too large, the job will fail to submit (this size is configurable, but that's besides the point). We should look into clearing the ranges out of the jobconf if it's large to prevent this error, since at this point the ranges are no longer needed in the configuration.