System and methods for receiving requests for executing specific tasks, analyzing current computational resources available for executing the tasks, and selecting code segments for executing the tasks, in which the selection of the code segments is done in a way that optimizes allocation of the various computational resources among the tasks, and such that said optimization is directed and facilitated by taking into consideration constraints and guidelines associated with the requests. Each of the tasks is associated with at least two code segments operative to execute the task, in which per a given task, different code segments operative to execute the task are associated with different computational resources needed for such execution. The selection of specific code segments in turn affects utilization of the computational resources. Guidelines such as latency requirements, cost constraints, and specific sources of code may be considered when selecting code segments in conjunction with resource availability.