If a user submits a job, the job is added to the job list of the user profile and the job exists in the list till the execution is completed. The result list of the user profile stores the results of all finished jobs during the life period of the user profile. Another list holds the slave nodes, whose resources cannot be accessed by the user. With such mechanisms, the job scheduler in the Master Node Module does not try to set up the connection to the slave nodes that are in this list, so that the resources in G-Hadoop are protected from misusing.