负载均衡算法小结

来源：互联网发布：域名dns查询 java 编辑：程序博客网时间：2024/06/06 08:37

1、轮询法
将请求按顺序轮流地分配到服务器上，他均衡的对待后端每一台服务器，而不关心服务器实际的连接数和当前的系统负载

public class TeskToundRobin {    private static Map<String, Integer> serverWeightMap = null;    private static Integer pos = 0;    public void initServerWeightMap(){        serverWeightMap = new HashMap<String,Integer>();        serverWeightMap.put("192.168.1.100", 1);        serverWeightMap.put("192.168.1.101", 1);        serverWeightMap.put("192.168.1.102", 4);        serverWeightMap.put("192.168.1.103", 1);        serverWeightMap.put("192.168.1.104", 1);        serverWeightMap.put("192.168.1.105", 3);        serverWeightMap.put("192.168.1.106", 1);        serverWeightMap.put("192.168.1.107", 2);        serverWeightMap.put("192.168.1.108", 1);        serverWeightMap.put("192.168.1.109", 1);        serverWeightMap.put("192.168.1.110", 1);    }    public static String testRoundRobin(){        Map<String,Integer> serverMap = new HashMap<String,Integer>();        serverMap.putAll(serverWeightMap);        Set<String> keySet = serverMap.keySet();        ArrayList<String> keyList = new ArrayList<String>();        keyList.addAll(keySet);        String server = null;        synchronized(pos){            System.out.println("pos = "+pos);            if(pos >= keySet.size()){                pos = 0;            }            server = keyList.get(pos);            System.out.println("server = "+server);            pos++;        }        return server;    }    public static void main(String[] args) {        for(int i= 0;i<15; i++){            TeskToundRobin test = new TeskToundRobin();            test.initServerWeightMap();            test.testRoundRobin();        }    }}

2、随机算法

public static String randomAlgorithm(){        Map<String,Integer> serverMap = new HashMap<String,Integer>();        serverMap.putAll(serverWeightMap);        Set<String> keySet = serverMap.keySet();        ArrayList<String> keyList = new ArrayList<String>();        keyList.addAll(keySet);        Random random = new Random();        int randomPos = random.nextInt(keyList.size());        String server = keyList.get(randomPos);        System.out.println(server);        return server;    }

3、哈希算法

public static String testConsumerHash(String remoteip){        Map<String,Integer> serverMap = new HashMap<String,Integer>();        serverMap.putAll(serverWeightMap);        Set<String> keySet = serverMap.keySet();        ArrayList<String> keyList = new ArrayList<String>();        keyList.addAll(keySet);        int hashCode = remoteip.hashCode();        int serverListSize = keyList.size();        int serverPos = hashCode % serverListSize;        String server = keyList.get(serverPos);        System.out.println(serverPos+"==="+server);        return server;    }

4、加权轮询法

public static String testWeightRoundRobin(){        Map<String,Integer> serverMap = new HashMap<String,Integer>();        serverMap.putAll(serverWeightMap);        Set<String> keySet = serverMap.keySet();        Iterator<String> it = keySet.iterator();        List<String> serverList = new ArrayList<String>();        while(it.hasNext()){            String server = it.next();            Integer weight = serverMap.get(server);            for(int i=0; i<weight; i++){                serverList.add(server);            }        }        String server = null;        synchronized(pos){            if(pos >= serverList.size()){                pos = 0;            }            server = serverList.get(pos);            pos ++;        }        return server;    }

5、加权随机法

public static String testWeightRandom(){        Map<String,Integer> serverMap = new HashMap<String,Integer>();        serverMap.putAll(serverWeightMap);        Set<String> keySet = serverMap.keySet();        Iterator<String> it = keySet.iterator();        List<String> serverList = new ArrayList<String>();        while(it.hasNext()){            String server = it.next();            Integer weight = serverMap.get(server);            for(int i=0; i<weight; i++){                serverList.add(server);            }        }        Random random = new Random();        int randomPos = random.nextInt(serverList.size());        String server = serverList.get(randomPos);        return server;    }

6、最小连接数法
根据后端服务器当前连接数情况，取连接数最小的服务器地址，尽可能得提高后端服务器的利用效率，奖负载合理地分流到每一台机器。由于最小连接数涉及服务器连接数的汇总和感知。所以设计和实现比较繁琐。

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