用遗传算法GA改进CloudSim自带的资源调度策略

Posted 2020-08-25 morein2008

遗传算法GA的核心代码实现：

最核心：

private static ArrayList<int[]> GA(ArrayList<int[]> pop,int gmax,double crossoverProb,double mutationRate)
    {
        HashMap<Integer,double[]> segmentForEach=calcSelectionProbs(pop);
        ArrayList<int[]> children=new ArrayList<int[]>();
        ArrayList<int[]> tempParents=new ArrayList<int[]>();
        while(children.size()<pop.size())
        {    
            //selection phase:select two parents each time.
            for(int i=0;i<2;i++)
            {
                double prob = new Random().nextDouble();
                for (int j = 0; j < pop.size(); j++)
                {
                    if (isBetween(prob, segmentForEach.get(j)))
                    {
                        tempParents.add(pop.get(j));
                        break;
                    }
                }
            }
            //cross-over phase.
            int[] p1,p2,p1temp,p2temp;
            p1= tempParents.get(tempParents.size() - 2).clone();
            p1temp= tempParents.get(tempParents.size() - 2).clone();
            p2 = tempParents.get(tempParents.size() -1).clone();
            p2temp = tempParents.get(tempParents.size() -1).clone();
            if(new Random().nextDouble()<crossoverProb)
            {
                int crossPosition = new Random().nextInt(cloudletList.size() - 1);
                //cross-over operation
                for (int i = crossPosition + 1; i < cloudletList.size(); i++)
                {
                    int temp = p1temp[i];
                    p1temp[i] = p2temp[i];
                    p2temp[i] = temp;
                }
            }
            //choose the children if they are better,else keep parents in next iteration.
            children.add(getFitness(p1temp) < getFitness(p1) ? p1temp : p1);
            children.add(getFitness(p2temp) < getFitness(p2) ? p2temp : p2);    
            // mutation phase.
            if (new Random().nextDouble() < mutationRate)
            {
                // mutation operations bellow.
                int maxIndex = children.size() - 1;

                for (int i = maxIndex - 1; i <= maxIndex; i++)
                {
                    operateMutation(children.get(i), mutationRate);
                }
            }
        }
        
        gmax--;
        return gmax > 0 ? GA(children, gmax, crossoverProb, mutationRate): children;
    }

 

完整核心代码：

  1 private static int[] findBestSchedule(ArrayList<int[]> pop)
  2     {
  3         double bestFitness=1000000000;
  4         int bestIndex=0;
  5         for(int i=0;i<pop.size();i++)
  6         {
  7             int []schedule=pop.get(i);
  8             double fitness=getFitness(schedule);
  9             if(bestFitness>fitness)
 10             {
 11                 bestFitness=fitness;
 12                 bestIndex=i;
 13             }
 14         }
 15         return pop.get(bestIndex);
 16     }
 17     
 18     private static int[] getScheduleByGA(int popSize,int gmax,double crossoverProb,double mutationRate)
 19     {
 20         ArrayList<int[]> pop=initPopsRandomly(cloudletList.size(),vmList.size(),popSize);
 21         pop=GA(pop,gmax,crossoverProb,mutationRate);
 22         return findBestSchedule(pop);
 23     }
 24     
 25     private static ArrayList<int[]> initPopsRandomly(int taskNum,int vmNum,int popsize)
 26     {
 27         ArrayList<int[]> schedules=new ArrayList<int[]>();
 28         for(int i=0;i<popsize;i++)
 29         {
 30             //data structure for saving a schedule：array,index of array are cloudlet id,content of array are vm id.
 31             int[] schedule=new int[taskNum];
 32             for(int j=0;j<taskNum;j++)
 33             {
 34                 schedule[j]=new Random().nextInt(vmNum);
 35             }
 36             schedules.add(schedule);
 37         }
 38         return schedules;
 39     }
 40     
 41     private static double getFitness(int[] schedule)
 42     {
 43         double fitness=0;
 44 
 45         HashMap<Integer,ArrayList<Integer>> vmTasks=new HashMap<Integer,ArrayList<Integer>>();
 46         int size=cloudletList.size();
 47         
 48         for(int i=0;i<size;i++)
 49         {
 50             if(!vmTasks.keySet().contains(schedule[i]))
 51             {
 52                 ArrayList<Integer> taskList=new ArrayList<Integer>();
 53                 taskList.add(i);
 54                 vmTasks.put(schedule[i],taskList);
 55             }
 56             else
 57             {
 58                 vmTasks.get(schedule[i]).add(i);
 59             }
 60         }
 61 
 62         for(Entry<Integer, ArrayList<Integer>> vmtask:vmTasks.entrySet())
 63         {
 64             int length=0;
 65             for(Integer taskid:vmtask.getValue())
 66             {
 67                 length+=getCloudletById(taskid).getCloudletLength();
 68             }
 69             
 70             double runtime=length/getVmById(vmtask.getKey()).getMips();
 71             if (fitness<runtime)
 72             {
 73                 fitness=runtime;
 74             }
 75         }
 76         
 77         return fitness;
 78     }
 79 
 80     private static ArrayList<int[]> GA(ArrayList<int[]> pop,int gmax,double crossoverProb,double mutationRate)
 81     {
 82         HashMap<Integer,double[]> segmentForEach=calcSelectionProbs(pop);
 83         ArrayList<int[]> children=new ArrayList<int[]>();
 84         ArrayList<int[]> tempParents=new ArrayList<int[]>();
 85         while(children.size()<pop.size())
 86         {    
 87             //selection phase:select two parents each time.
 88             for(int i=0;i<2;i++)
 89             {
 90                 double prob = new Random().nextDouble();
 91                 for (int j = 0; j < pop.size(); j++)
 92                 {
 93                     if (isBetween(prob, segmentForEach.get(j)))
 94                     {
 95                         tempParents.add(pop.get(j));
 96                         break;
 97                     }
 98                 }
 99             }
100             //cross-over phase.
101             int[] p1,p2,p1temp,p2temp;
102             p1= tempParents.get(tempParents.size() - 2).clone();
103             p1temp= tempParents.get(tempParents.size() - 2).clone();
104             p2 = tempParents.get(tempParents.size() -1).clone();
105             p2temp = tempParents.get(tempParents.size() -1).clone();
106             if(new Random().nextDouble()<crossoverProb)
107             {
108                 int crossPosition = new Random().nextInt(cloudletList.size() - 1);
109                 //cross-over operation
110                 for (int i = crossPosition + 1; i < cloudletList.size(); i++)
111                 {
112                     int temp = p1temp[i];
113                     p1temp[i] = p2temp[i];
114                     p2temp[i] = temp;
115                 }
116             }
117             //choose the children if they are better,else keep parents in next iteration.
118             children.add(getFitness(p1temp) < getFitness(p1) ? p1temp : p1);
119             children.add(getFitness(p2temp) < getFitness(p2) ? p2temp : p2);    
120             // mutation phase.
121             if (new Random().nextDouble() < mutationRate)
122             {
123                 // mutation operations bellow.
124                 int maxIndex = children.size() - 1;
125 
126                 for (int i = maxIndex - 1; i <= maxIndex; i++)
127                 {
128                     operateMutation(children.get(i), mutationRate);
129                 }
130             }
131         }
132         
133         gmax--;
134         return gmax > 0 ? GA(children, gmax, crossoverProb, mutationRate): children;
135     }
136     
137     public static void operateMutation(int []child,double mutationRate)
138     {
139         if(new Random().nextDouble()<mutationRate)
140         {
141             int mutationIndex=new Random().nextInt(cloudletList.size());
142             int newVmId=new Random().nextInt(vmList.size());
143             while(child[mutationIndex]==newVmId)
144             {
145                 newVmId=new Random().nextInt(vmList.size());
146             }
147             
148             child[mutationIndex]=newVmId;
149         }
150     }
151     
152     private static boolean isBetween(double prob,double[]segment)
153     {
154         if(segment[0]<=prob&&prob<=segment[1])
155             return true;
156         return false;    
157     }
158     
159     private static HashMap<Integer,double[]> calcSelectionProbs(ArrayList<int[]> parents)
160     {
161         int size=parents.size();
162         double totalFitness=0;    
163         ArrayList<Double> fits=new ArrayList<Double>();
164         HashMap<Integer,Double> probs=new HashMap<Integer,Double>();
165         
166         for(int i=0;i<size;i++)
167         {
168             double fitness=getFitness(parents.get(i));
169             fits.add(fitness);
170             totalFitness+=fitness;
171         }
172         for(int i=0;i<size;i++)
173         {
174             probs.put(i,fits.get(i)/totalFitness );
175         }
176         
177         return getSegments(probs);
178     }
179     
180     private static HashMap<Integer,double[]> getSegments(HashMap<Integer,Double> probs)
181     {
182         HashMap<Integer,double[]> probSegments=new HashMap<Integer,double[]>();
183         //probSegments保存每个个体的选择概率的起点、终点，以便选择作为交配元素。
184         int size=probs.size();
185         double start=0;
186         double end=0;
187         for(int i=0;i<size;i++)
188         {
189             end=start+probs.get(i);
190             double[]segment=new double[2];
191             segment[0]=start;
192             segment[1]=end;
193             probSegments.put(i, segment);
194             start=end;
195         }
196         
197         return probSegments;
198     }
199     

完整的GA算法的工程实现，包括与轮询(RR)算法效果对比：

GA-cloudsim.zip