常见的非阻塞队列

来源：互联网发布：node 编辑：程序博客网时间：2024/04/30 11:43

常见的非阻塞队列

1) ConcurrentHashMap
2) ConcurrentSkipListMap
3) ConcurrentSkipListSet
4) ConcurrentLinkedQueue
5) ConcurrentLinkedDeque
6) CopyOnWriteArrayList
7) CopyOnWriteArraySet

HashTable、Vector调用iterator()方法返回Iterator对象后，再调用remove()时会出现ConcurrentModificationException异常，也就是并不支持Iterator并发的删除。

ConcurrentHashMap是弱一致性模型
ConcurrentSkipListMap 并发程序中可以保证顺序

public class MyService {    public ConcurrentSkipListMap map = new ConcurrentSkipListMap();    public MyService(){        UserInfo user1 = new UserInfo(1, "user1");        UserInfo user2 = new UserInfo(2, "user2");        UserInfo user3 = new UserInfo(3, "user3");        UserInfo user4 = new UserInfo(4, "user4");        UserInfo user5 = new UserInfo(5, "user5");        map.put(user1, "value1");        map.put(user4, "value4");        map.put(user2, "value2");        map.put(user5, "value5");        map.put(user3, "value3");    }}public class ThreadA extends Thread {    private MyService myservice;    public ThreadA(MyService myservice){        this.myservice = myservice;    }    @Override    public void run() {        while(!myservice.map.isEmpty()){            Map.Entry entry = myservice.map.pollFirstEntry();            UserInfo userInfo = (UserInfo) entry.getKey();            System.out.println("key = " + userInfo.getId() + entry.getValue());        }    }}

ConcurrentSkipListSet 支持排序且不允许重复的元素
ConcurrentLinkedQueue 提供了并发环境的队列操作
方法poll当没有获得数据时返回null，如果有数据则移除表头，并将表头进行返回
方法element当没有数据时，出现NoSuchElementExcepiton异常，如果有数据则返回表头项
方法peek当没有数据时返回null，有数据则不移除表头，返回表头项
ConcurrentLinkedDeque

public class AddTask implements Runnable {    private ConcurrentLinkedDeque<String> list;    public AddTask(ConcurrentLinkedDeque<String> list){        this.list = list;    }    @Override    public void run() {        String name = Thread.currentThread().getName();        for(int i=0;i<1000;i++){            list.add(name+"--" + (i+1));        }    }}public class RemoveTask implements Runnable{    private ConcurrentLinkedDeque list;    public RemoveTask(ConcurrentLinkedDeque list){        this.list = list;    }    @Override    public void run() {        String name = Thread.currentThread().getName();        for(int i=0;i<500;i++){            list.pollFirst();            list.pollLast();        }    }}public class Main {    public static void main(String[] args) throws InterruptedException {        ConcurrentLinkedDeque<String> list = new ConcurrentLinkedDeque<>();        Thread[] threads = new Thread[100];        for(int i=0;i<threads.length;i++){            AddTask task = new AddTask(list);            threads[i] = new Thread(task);            threads[i].start();        }        System.out.printf("Main %d AddTask have been launched\n", threads.length);        for(int i=0;i<threads.length;i++){            threads[i].join();        }        System.out.printf("Main size of threads %d\n", list.size());        for(int i=0;i<threads.length;i++){            RemoveTask removeTask = new RemoveTask(list);            threads[i] = new Thread(removeTask);            threads[i].start();        }        System.out.printf("Main %d RemoveTask have been launched\n", threads.length);        for(int i=0;i<threads.length;i++){            threads[i].join();        }        System.out.printf("Main size of threads %d\n", list.size());    }}

CopyOnWriteArrayList
CopyOnWriteArraySet

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