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权重轮询调度算法(WeightedRound-RobinScheduling)-Java实现2

2024-07-13 14:41:51   217人阅读

 

权重轮询调度算法(WeightedRound-RobinScheduling)-Java实现
                                      ----参考Nginx中负载均衡算法实现


与上一遍博客 http://www.cnblogs.com/huligong1234/p/3819979.html 中实现方式不同，
这里主要参考这篇文章的实现： Nginx 负载均衡-加权轮询策略剖析 http://www.cnblogs.com/dyllove98/archive/2013/07/13/3188450.html，
与上一遍中实现比起来，效果比较好，权重比较低的服务器，也比较容易背获取到，但请求数量比较大的时候，两个实现方式中，每个服务器分担的请求数基本无差别，区别主要是顺序上。
本篇文章也加上了动态添加服务器，和动态down掉服务器的演示实例。 由于研究本算法的目的是在其他方面的应用，故涉及服务器请求超时时间等因素，并未考虑。

 

  1 import java.util.ArrayList;  2 import java.util.Date;  3 import java.util.HashMap;  4 import java.util.List;  5 import java.util.Map;  6 import java.util.Map.Entry;  7   8 /**  9  * 权重轮询调度算法(WeightedRound-RobinScheduling)-Java实现 10  * @author huligong 11  * */ 12 public class WeightedRoundRobinScheduling { 13  14     private List<Server> serverList; //服务器集合 15  16     public Server GetBestServer() { 17         Server server = null; 18         Server best = null; 19         int total = 0; 20         for(int i=0,len=serverList.size();i<len;i++){ 21             //当前服务器对象 22             server = serverList.get(i); 23  24             //当前服务器已宕机，排除 25             if(server.down){ 26                 continue; 27             } 28  29             server.currentWeight += server.effectiveWeight; 30             total += server.effectiveWeight; 31              32             if(server.effectiveWeight < server.weight){ 33                 server.effectiveWeight++; 34             } 35              36             if(best == null || server.currentWeight>best.currentWeight){ 37                 best = server; 38             } 39              40         } 41  42         if (best == null) { 43             return null; 44         } 45  46         best.currentWeight -= total; 47         best.checkedDate = new Date(); 48         return best; 49     } 50      51      52  53     class Server { 54         public String ip; 55         public int weight; 56         public int effectiveWeight; 57         public int currentWeight; 58         public boolean down = false; 59         public Date checkedDate; 60         public Server(String ip, int weight) { 61             super(); 62             this.ip = ip; 63             this.weight = weight; 64             this.effectiveWeight = this.weight; 65             this.currentWeight = 0; 66             if(this.weight < 0){ 67                 this.down = true; 68             }else{ 69                 this.down = false; 70             } 71         } 72         public String getIp() { 73             return ip; 74         } 75         public void setIp(String ip) { 76             this.ip = ip; 77         } 78         public int getWeight() { 79             return weight; 80         } 81         public void setWeight(int weight) { 82             this.weight = weight; 83         } 84         public int getEffectiveWeight() { 85             return effectiveWeight; 86         } 87         public void setEffectiveWeight(int effectiveWeight) { 88             this.effectiveWeight = effectiveWeight; 89         } 90         public int getCurrentWeight() { 91             return currentWeight; 92         } 93         public void setCurrentWeight(int currentWeight) { 94             this.currentWeight = currentWeight; 95         } 96         public boolean isDown() { 97             return down; 98         } 99         public void setDown(boolean down) {100             this.down = down;101         }102         public Date getCheckedDate() {103             return checkedDate;104         }105         public void setCheckedDate(Date checkedDate) {106             this.checkedDate = checkedDate;107         }108         109     }110     111 112     public void init() {113         Server s1 = new Server("192.168.0.100", 3);//3114         Server s2 = new Server("192.168.0.101", 2);//2115         Server s3 = new Server("192.168.0.102", 6);//6116         Server s4 = new Server("192.168.0.103", 4);//4117         Server s5 = new Server("192.168.0.104", 1);//1118         Server s6 = new Server("192.168.0.105", 0);//0119         Server s7 = new Server("192.168.0.106", 0);//0120         Server s8 = new Server("192.168.0.107", 0);//0121         Server s9 = new Server("192.168.0.108", 0);//0122         serverList = new ArrayList<Server>();123         serverList.add(s1);124         serverList.add(s2);125         serverList.add(s3);126         serverList.add(s4);127         serverList.add(s5);128         serverList.add(s6);129         serverList.add(s7);130         serverList.add(s8);131         serverList.add(s9);132     }133     134     public void add(int i) {135         Server s = new Server("192.168.0.1"+i, i-15);136         serverList.add(s);137     }138     139     public Server getServer(int i) {140         if(i<serverList.size()){141             return serverList.get(i);142         }143        return null;144     }145     146     147     public static void main(String[] args) {148         WeightedRoundRobinScheduling obj = new WeightedRoundRobinScheduling();149         obj.init();150         151         Map<String,Integer> countResult = new HashMap<String,Integer>();152         153         for (int i = 0; i < 100; i++) {154             Server s = obj.GetBestServer();155             String log = "ip:"+s.ip+";weight:"+s.weight;156             if(countResult.containsKey(log)){157                 countResult.put(log,countResult.get(log)+1);158             }else{159                 countResult.put(log,1);160             }161             System.out.println(log);162         163             //动态添加服务器164             if(i==20 || i==22){165                   obj.add(i);166             }167             168             //动态停止服务器169             if(i==30){170                 obj.getServer(2).setDown(true);171                 obj.getServer(3).setDown(true);172           }173         }174         175         for(Entry<String, Integer> map : countResult.entrySet()){176             System.out.println("服务器 "+map.getKey()+" 请求次数： "+map.getValue());177         }178     }179 180 }


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