1. A method for preparing a PTX instruction code to enable an intermediate code-based application program to access a target graphics processing unit (GPU) in a parallel processing environment, comprising: scanning for an attribute annotation associated with a section of a source code for the intermediate code-based application program; translating the section of the source code to the PTX instruction code for the target GPU according to the attribute annotation; and causing a virtual clustering service associated with a host computer to query availability of the target GPU through communicating with a virtual clustering service associated with a graphics system that comprises the target GPU.