Java 高并发下的实践

一、使用的技术

HashMap

ConcurrentHashMap

Lock

ReadWriteLock

synchronized

 

二、一百万并发下的组合

ConcurrentLockMap

/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */package cn.edu.scau.mk.map;import java.util.concurrent.ConcurrentHashMap;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;/** * * @author MK */public class ConcurrentLockMap implements In {    ConcurrentHashMap<Integer, Integer> map = new ConcurrentHashMap<>();    Lock lock = new ReentrantLock();    @Override    public void add(int a) {        lock.lock();        try {            if (map.containsKey(a)) {                map.put(a, 1 + map.get(a));            } else {                map.put(a, 1);            }        } finally {            lock.unlock();        }    }    @Override    public int get(int a) {        int as = map.get(a);        return as;    }}

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ConcurrentSynchronizedMap

package cn.edu.scau.mk.map;import java.util.concurrent.ConcurrentHashMap;/** * * @author MK */public class ConcurrentSynchronizedMap implements In {    ConcurrentHashMap<Integer, Integer> map = new ConcurrentHashMap<>();    @Override    public void add(int a) {        synchronized ((""+a).intern()) {            if (map.containsKey(a)) {                map.put(a, 1 + map.get(a));            } else {                map.put(a, 1);            }        }    }    @Override    public int get(int a) {        int as = map.get(a);        return as;    }}

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LockHashMap

package cn.edu.scau.mk.map;import java.util.HashMap;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;/** * * @author MK */public class LockHashMap implements In {    HashMap<Integer, Integer> map = new HashMap<>();    Lock lock = new ReentrantLock();    @Override    public void add(int a) {        lock.lock();        try {            if (map.containsKey(a)) {                map.put(a, 1 + map.get(a));            } else {                map.put(a, 1);            }        } finally {            lock.unlock();        }    }    @Override    public int get(int a) {         int as = 0;        lock.lock();        try {            map.get(a);        } finally {            lock.unlock();        }        return as;    }}

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ReadWriteHashMap

/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */package cn.edu.scau.mk.map;import java.util.HashMap;import java.util.concurrent.locks.ReentrantReadWriteLock;/** * * @author MK */public class ReadWriteHashMap implements In {    HashMap<Integer, Integer> map = new HashMap<>();    ReentrantReadWriteLock lock = new ReentrantReadWriteLock();    //390    @Override    public void add(int a) {        lock.writeLock().lock();        try {            if (map.containsKey(a)) {                map.put(a, 1 + map.get(a));            } else {                map.put(a, 1);            }        } finally {            lock.writeLock().unlock();        }    }    @Override    public int get(int a) {        int as = 0;        lock.readLock().lock();        try {            as = map.get(a);        } finally {            lock.readLock().unlock();        }        return as;    }}

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SynchronizedHashMap

/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */package cn.edu.scau.mk.map;import java.util.HashMap;/** * * @author MK */public class SynchronizedHashMap implements In {    HashMap<Integer, Integer> map = new HashMap<>();      @Override    public synchronized void add(int a) {                   if (map.containsKey(a)) {                map.put(a, 1 + map.get(a));            } else {                map.put(a, 1);            }            }    @Override    public synchronized int get(int a) {        int as = map.get(a);               return as;    }}

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In

package cn.edu.scau.mk.map;/** * * @author MK */public interface In {    void add(int a);    int get(int a);    }

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Adder

/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */package cn.edu.scau.mk.map;import java.util.Random;/** * * @author MK */public class Adder implements Runnable {    In in;    Random random = new Random();    public Adder(In in) {        this.in=in;    }    @Override    public void run() {        for (int i = 0; i < 1000; i++) {            //in.add(random.nextInt());            in.add(i);                    }    }}

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Getter

/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */package cn.edu.scau.mk.map;import java.util.Random;/** * * @author MK */public class Getter implements Runnable {    In in;    Random random = new Random();    public Getter(In in) {        this.in=in;    }    @Override    public void run() {        for (int i = 0; i < 1000; i++) {            //in.add(random.nextInt());            in.get(i);                    }    }}

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TestDemo

package cn.edu.scau.mk.map;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.ThreadPoolExecutor;import java.util.concurrent.TimeUnit;/** * * @author MK */public class TestDemo {    public static void main(String[] args) {        In in = null;        in = new ReadWriteHashMap();        operate(in);        in = new ConcurrentSynchronizedMap();        operate(in);        in = new ConcurrentLockMap();        operate(in);        in = new SynchronizedHashMap();        operate(in);        in = new LockHashMap();        operate(in);    }    public static void operate(In in) {        int poolSize = 1000000;        Adder add = new Adder(in);        ThreadPoolExecutor threadPool = (ThreadPoolExecutor) Executors.newCachedThreadPool();        long start = System.currentTimeMillis();        for (int i = 0; i < poolSize; i++) {            threadPool.execute(add);        }        System.out.println(threadPool.getActiveCount());        threadPool.shutdown();        try {//等待直到所有任务完成            threadPool.awaitTermination(Long.MAX_VALUE, TimeUnit.MINUTES);            long end = System.currentTimeMillis() - start;            System.out.print(in.getClass().getSimpleName()+" add:" + end);        } catch (InterruptedException e) {            e.printStackTrace();        }        Getter get = new Getter(in);        threadPool = (ThreadPoolExecutor) Executors.newCachedThreadPool();        start = System.currentTimeMillis();        for (int i = 0; i < poolSize; i++) {            threadPool.execute(add);        }        threadPool.shutdown();        try {//等待直到所有任务完成            threadPool.awaitTermination(Long.MAX_VALUE, TimeUnit.MINUTES);            long end = System.currentTimeMillis() - start;            System.out.println(" get:" + end);        } catch (InterruptedException e) {            e.printStackTrace();        }    }}

View Code

 

三、输出结果

（1）一万并发

6642
ReadWriteHashMap add:1263 get:983
7
ConcurrentSynchronizedMap add:577 get:546
7373
ConcurrentLockMap add:1515 get:1731
7783
SynchronizedHashMap add:1810 get:1607
6632
LockHashMap add:1092 get:1029

（2）十万并发

58095
ReadWriteHashMap add:149181 get:69606
1443
ConcurrentSynchronizedMap add:5678 get:6631
54623
ConcurrentLockMap add:84595 get:77182
48390
SynchronizedHashMap add:63958 get:64696
49078
LockHashMap add:64606 get:64364

（3）百万并发

681252
ReadWriteHashMap add:215943 get:85792
25145
ConcurrentSynchronizedMap add:80593 get:76485
546230
ConcurrentLockMap add:912461 get:821907
636318
SynchronizedHashMap add:845893 get:850142
500129
LockHashMap add:792271 get:808326