1. A distributed processing system supporting process migration, the system comprising: a distributed computer processing environment having a plurality of computer processors that are configured to collectively perform a distributed processing task under a current distribution policy, wherein the current distribution policy describes how the distributed processing task is to be divided into a plurality of sub-tasks that are then distributed to the plurality of computer processors: a utilization monitor configured to determine a utilization of each task running on each of said processors, wherein the utilization is expressed as an amount of computational resources currently used or available for use at a processor: a scenario forecaster configured to calculate one or more possible utilization scenarios for said processors; a distribution determiner configured to determine at least one candidate distribution policy for redistributing said distributed processing task among said processors; and a cost calculator configured to calculate an expected cost of allowing said distributed processing task to remain distributed among said processors according to the current distribution policy according to which said distributed processing task is currently distributed among said processors, calculate an expected cost of redistributing said distributed processing task among said processors according to any of said candidate distribution policies, wherein any of said calculations are based on any of said possible utilization scenarios and associated probabilities of said possible utilization scenarios occurring and on a net cost calculated from the maximum cost of all processors to complete their sub-tasks, and compare said expected costs of said current and candidate distributions to determine which of said distributions are optimal in accordance with predefined optimization criteria, wherein any of said utilization monitor, scenario forecaster, distribution determiner, and cost calculator are implemented in either of computer hardware and computer software and embodied in a computer-readable medium, wherein the expected cost of allowing is calculated using the formula ECA=Σ((Cost(CDP_Ui))*prob(Ui)) for i=1 to n, wherein (ECA) is the expected cost of allowing, Cost(CDP_Ui) is a cost of the current distribution policy using the possible utilization scenario, and Prob(Ui) is the probability of occurrence of the possible utilization scenario under the current distribution policy and wherein the expected cost of redistributing is calculated using the formula ECR=((Cost(CnDP_Ui))*prob(Uci)) for i=1 to n, wherein (ECA) is the expected cost of allowing, Cost(CnDP_Uci) is a cost of the candidate distribution policy using the possible utilization scenario, and Prob(Uci) is the probability of occurrence of the possible utilization scenario under the candidate distribution policy.