Patent ID: 7911639

Claim:
An image forming device having a processor, multiple image input units connected to the processor, and a storing unit connected to the processor and embodying a virtual address spaces and a real address space, wherein an operating system that executes multiple jobs by mapping a virtual address space of a process of each job onto a real address space being stored in the storing unit, the image forming device, comprising: a first shared area onto which a data area in each virtual address space of an executing process is mapped and to which a kernel of the operating system can make access; a second shared area where state information of each executing job and an area allocation status information of each executing job in the first shared area are stored, wherein the real address space includes the first shared area and the second shared area; and identical job page assurance programs, wherein processes in the virtual address spaces have the identical job page assurance programs; and the job page assurance programs, further comprising steps of: (a) determining a memory size of an area to which one page of non-compressed data for a job is allocated in the first shared area, which is to be requested to the kernel, based on the state information and the area allocation status information of the job; (b) requesting the kernel to allocate the area of the size and altering the area allocation status information; and (c) requesting the kernel to release the allocated area for the job in the first shared area and altering the area acquisition status information, in response to an output completion report of the job.