Research Article

Multiobjective Level-Wise Scientific Workflow Optimization in IaaS Public Cloud Environment

Algorithm 2

Workflow optimization using SPEA2.
Input: Task Objects, Search Space (SP), total number of levels (), : Population size, : number of generations,
: number of objectives, MP: mutation probability, CP: crossover probability.
Output: Pareto optimal solutions, .
Processing
Step 1. Generate random initial population, and empty archive .
(1.1) Randomly generate integer chromosome for .
(truncate if necessary)
(1.2) Calculate the fitness of each random chromosome
(1.3) Copy all non-dominated individuals in and to
Step 2. Evolve population .
(2.1) Select parents using tournament selection,
(2.2) Perform two-point dynamic crossover operation on parents with probability CP to produce offspring
population.
(2.3) Perform mutation operation with probability MP on random points applied to offspring
(2.4) Calculate fitness of new offspring population and update population
(2.5) Use non-dominated sorting to divide into several non-domination levels ,.
(2.6) Update
Step 3. Repeat Step 2 until termination condition is met.
Step 4. Output the list of optimal solutions at Pareto front, .