Aspects of the disclosure provide an apparatus for executing a program that involves a plurality of operators. For example, the apparatus can include an executor and an analyzer. The executor can be configured to execute the program with at least a first one of the operators loaded on a second memory from a first memory that stores the operators and to generate a signal based on a progress of the execution of the program with the first operator. The analyzer can be coupled to the executor, the first memory and the second memory, and configured to load at least a second one of the operators of the program next to the first operator stored in the first memory to the second memory before the executor finishes execution of the program with the first operator based on the signal from the executor and an executing scheme stored in the second memory.