1. A computer-implemented method for sharing reference data among a plurality of application programs executed by a plurality of virtual machines, the method comprising: allocating an empty page of a physical memory in response to a memory allocation request for a reference data file from one application program; determining whether the reference data file has been already loaded in the physical memory by another application program in response to an open request for the reference data file from the application program; and sharing, when the reference data file has already been loaded in the physical memory, the reference data file between the one application program and the another application program by mapping an address of the physical memory in which the reference data file has been loaded to a virtual machine memory address in which the empty page is mapped, in response to a read request of the reference data file from the application program.