zookeeper编程入门系列之zookeeper实现分布式进程监控和分布式共享锁(图文详解)...
本博文的主要内容有
一、zookeeper编程入门系列之利用zookeeper的临时节点的特性来监控程序是否还在运行
二、zookeeper编程入门系列之zookeeper实现分布式进程监控
三、zookeeper编程入门系列之zookeeper实现分布式共享锁
这里,推荐用下面的eclipse版本(当然你若也有myeclipse,请忽视我这句话)
Group Id:zhouls.bigdata
Artifact Id:zkDemo
Package:zhouls.bigdata.zkDemo
将默认的jdk,修改为jdk1.7
修改默认的pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>zhouls.bigdata</groupId><artifactId>zkDemo</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>zkDemo</name><url>http://maven.apache.org</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>3.8.1</version><scope>test</scope></dependency></dependencies> </project>
修改后的pom.xml为
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>zhouls.bigdata</groupId><artifactId>zkDemo</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>zkDemo</name><url>http://maven.apache.org</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope></dependency><!-- 此版本的curator操作的zk是3.4.6版本 --><dependency><groupId>org.apache.curator</groupId><artifactId>curator-framework</artifactId><version>2.10.0</version></dependency></dependencies> </project>
junit是单元测试。
也许,大家的jdk1.7会报错误,那就改为jdk1.8。
一、zookeeper编程入门系列之利用zookeeper的临时节点的特性来监控程序是否还在运行
写一个TestCurator.java
怎么通过Curator连接到zookeeper官网,其实是有固定的。
这打开需要好几分钟的时间,里面会有示范代码,教我们怎么连接zookeeper。
我这里的zookeeper集群是master(192.168.80.145)、slave1(192.168.80.146)和slave2(192.168.80.147)。
WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] ls / [hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 1]
WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] ls / [hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 1]
WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] ls / [hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 1]
现在,我想通过Curator来连接到zookeeper集群,并在里面创建临时节点。
这里,永久节点为monitor、临时节点为test123。(当然,大家可以自行去命名)(同时,大家也可以通过命令行方式来创建,我这里就是以代码api形式来创建了)
比如,这样,monitor是父节点(作为永久节点),test123是临时节点。
而现在,是monitor都没有,它不会给我们一次性创建完。
除非,大家在命令行里先创建好monitor节点,之后,然后上述代码可以操作成功。否则,就需如下修改代码。
package zhouls.bigdata.zkDemo;import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.ZooDefs.Ids; import org.junit.Test;/*** * @author zhouls**/ public class TestCurator {@Testpublic void testName() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL)//指定节点类型,临时节点.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/monitor/test123");//指定节点名称 }}
可以看到成功monitor生成,其实啊,/monitor/test123节点也是有的。(只是中间又消失了)
为什么会中间消失了呢?是因为,test123是临时节点。创建完之后,它就会消失了。
WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] ls / [hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 1] ls / [monitor, hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 2] ls /monitor []
那么,我想看,怎么用代码来实现呢?
增加以下代码
此时的代码是TestCurator.java
package zhouls.bigdata.zkDemo;import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.ZooDefs.Ids; import org.junit.Test;/*** * @author zhouls**/ public class TestCurator {@Testpublic void testName() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL)//指定节点类型,临时节点.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/monitor/test123");//指定节点名称 while (true) {;}}}
WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] ls / [hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 1] ls / [monitor, hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 2] ls /monitor [test123] [zk: localhost:2181(CONNECTED) 3]
然后,我这边,把代码,来停掉,则它就会消失了。
WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] ls / [hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 1] ls / [monitor, hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 2] ls /monitor [] [zk: localhost:2181(CONNECTED) 3] ls /monitor [test123] [zk: localhost:2181(CONNECTED) 4] ls /monitor [] [zk: localhost:2181(CONNECTED) 5]
好的,那么,现在,又有一个疑问出来了,在往monitor节点里,注册节点如test123,那么,我怎么知道是哪一台的呢?则此时,需要做如下修改
此刻的代码如下TestCurator.java
package zhouls.bigdata.zkDemo;import java.net.InetAddress;import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.ZooDefs.Ids; import org.junit.Test;/*** * @author zhouls**/ public class TestCurator {@Testpublic void testName() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 InetAddress localhost = InetAddress.getLocalHost();String ip = localhost.getHostAddress();client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL)//指定节点类型,临时节点.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/monitor/" + ip);//指定节点名称while (true) {;}}}
WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] ls / [hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 1] ls / [monitor, hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 2] ls /monitor [] [zk: localhost:2181(CONNECTED) 3] ls /monitor [test123] [zk: localhost:2181(CONNECTED) 4] ls /monitor [] [zk: localhost:2181(CONNECTED) 5] ls /monitor [169.254.28.160] [zk: localhost:2181(CONNECTED) 6]
WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] ls / [hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 1] ls / [monitor, hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 2] ls /monitor [test123] [zk: localhost:2181(CONNECTED) 3] ls /monitor [169.254.28.160] [zk: localhost:2181(CONNECTED) 4]
WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] ls / [hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 1] ls / [monitor, hbase, zookeeper, admin, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 2] ls /monitor [test123] [zk: localhost:2181(CONNECTED) 3] ls /monitor [169.254.28.160] [zk: localhost:2181(CONNECTED) 4]
这个ip怎么不是我集群里的ip呢?是哪里的???
原来是这里的
因为,我是在test测试,所以,拿到的是windows本地的ip地址。
如果,放在mian去测试,则就是拿到集群里的ip地址了。
至此,我们是用临时节点的这个特性,来监控程序有没有运行的。并不是说临时节点就是来只做这个事!!!
package zhouls.bigdata.zkDemo;import java.net.InetAddress;import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.ZooDefs.Ids; import org.junit.Test;/*** * @author zhouls**/ public class TestCurator {@Testpublic void testName() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 InetAddress localhost = InetAddress.getLocalHost();String ip = localhost.getHostAddress();client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL)//指定节点类型,临时节点.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/monitor/" + ip);//指定节点名称while (true) {;}//或者// client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建 // .withMode(CreateMode.EPHEMERAL_SEQUENTIAL)// 指定节点类型,注意:临时节点必须在某一个永久节点下面 // .withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息 // .forPath("/monitor/ + ip");// 指定节点名称 // while (true) { // ; // } }}
可以将这个,写入到入口类或构造函数里。每次开始前都调用执行。以此来监控程序是否还在运行,非常重要!
二、zookeeper编程入门系列之zookeeper实现分布式进程监控
思路: 即在/下,先注册一个监视器,即monitor节点(为永久节点)
然后,监视monitor节点下面的所有子节点(为临时节点)
概念见
Zookeeper概念学习系列之zookeeper实现分布式进程监控
先执行
然后执行
ZkNodeWacter.java
package zhouls.bigdata.zkDemo;import java.util.ArrayList; import java.util.List;import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; /*** 这个监视器需要一直在后台运行,所以相当于是一个死循环的进程* @author zhouls**/ public class ZkNodeWacter implements Watcher {CuratorFramework client;List<String> childrenList = new ArrayList<String>();public ZkNodeWacter() {//在启动监视器的时候,链接到zkRetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;int connectionTimeoutMs = 3000;client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端//监视monitor节点下面的所有子节点(为临时节点)try {//在monitor目录上注册一个监视器,这个监视器只能使用一次childrenList = client.getChildren().usingWatcher(this).forPath("/monitor");} catch (Exception e) {e.printStackTrace();}}/*** 当monitor节点下面的子节点发生变化的时候,这个方法会被调用到*/public void process(WatchedEvent event) {System.out.println("我被调用了:"+event);try {//重复注册监视器List<String> newChildrenList = client.getChildren().usingWatcher(this).forPath("/monitor");//先遍历原始的子节点listfor (String ip : childrenList) {if(!newChildrenList.contains(ip)){System.out.println("节点消失:"+ip);}}for (String ip : newChildrenList) {if(!childrenList.contains(ip)){System.out.println("新增节点:"+ip);}}childrenList = newChildrenList;} catch (Exception e) {e.printStackTrace();}}public static void main(String[] args) {ZkNodeWacter spiderWacter = new ZkNodeWacter();spiderWacter.start();//表示需要开启一个监视器 }private void start() {while(true){;}}}
TestCurator.java
package zhouls.bigdata.zkDemo;import java.net.InetAddress;import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.ZooDefs.Ids; import org.junit.Test;/*** * @author zhouls**/ public class TestCurator {@Testpublic void testName() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 InetAddress localhost = InetAddress.getLocalHost();String ip = localhost.getHostAddress();client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL)//指定节点类型,临时节点.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/monitor/" + ip);//指定节点名称while (true) {;}// client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建 // .withMode(CreateMode.EPHEMERAL_SEQUENTIAL)// 指定节点类型,注意:临时节点必须在某一个永久节点下面 // .withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息 // .forPath("/monitor/ + ip");// 指定节点名称 // while (true) { // ; // } }}
三、zookeeper编程入门系列之zookeeper实现分布式共享锁
这里,一般,都是创建临时有序子节点,怎么来创建,不难
说到协调,我首先想到的是北京很多十字路口的交通协管,他们手握着小红旗,指挥车辆和行人是不是可以通行。如果我们把车辆和行人比喻成运行在计算机中的单元(线程),那么这个协管是干什么的?很多人都会想到,这不就是锁么?对,在一个并发的环境里,我们为了避免多个运行单元对共享数据同时进行修改,造成数据损坏的情况出现,我们就必须依赖像锁这样的协调机制,让有的线程可以先操作这些资源,然后其他线程等待。对于进程内的锁来讲,我们使用的各种语言平台都已经给我们准备很多种选择。
TestCurator.java
package zhouls.bigdata.zkDemo;import java.net.InetAddress;import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.ZooDefs.Ids; import org.junit.Test;/*** * @author zhouls**/ public class TestCurator {@Testpublic void test1() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 InetAddress localhost = InetAddress.getLocalHost();String ip = localhost.getHostAddress();client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL)//指定节点类型,临时节点.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/monitor/" + ip);//指定节点名称while (true) {;}}@Testpublic void test2() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 InetAddress localhost = InetAddress.getLocalHost();String ip = localhost.getHostAddress();client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL_SEQUENTIAL)// 指定节点类型,注意:临时节点必须在某一个永久节点下面.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/monitor/");// 指定节点名称while (true) {;}}}
DistributedLock.java
package zhouls.bigdata.zkDemo;import java.io.IOException; import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.concurrent.CountDownLatch; import java.util.concurrent.TimeUnit; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock;import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooDefs; import org.apache.zookeeper.ZooKeeper; import org.apache.zookeeper.data.Stat;/**DistributedLock lock = null;try {lock = new DistributedLock("127.0.0.1:2181","test");lock.lock();//do something...} catch (Exception e) {e.printStackTrace();} finally {if(lock != null)lock.unlock();}//lock.closeZk();//在cleanup方法中添加**/ public class DistributedLock implements Lock, Watcher{private ZooKeeper zk;private String root = "/locks";//根private String lockName;//竞争资源的标志private String waitNode;//等待前一个锁private String myZnode;//当前锁private CountDownLatch latch;//计数器private int sessionTimeout = 30000;//30秒private int waitTimeout = 30000;//等待节点失效最大时间 30秒private List<Exception> exception = new ArrayList<Exception>();/*** 创建分布式锁,使用前请确认zkConnString配置的zookeeper服务可用* @param zkConnString 127.0.0.1:2181* @param lockName 竞争资源标志,lockName中不能包含单词lock*/public DistributedLock(String zkConnString, String lockName){this.lockName = lockName;// 创建一个与服务器的连接try {zk = new ZooKeeper(zkConnString, sessionTimeout, this);Stat stat = zk.exists(root, false);if(stat == null){// 创建根节点zk.create(root, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT); }} catch (IOException e) {exception.add(e);} catch (KeeperException e) {exception.add(e);} catch (InterruptedException e) {exception.add(e);}}/*** zookeeper节点的监视器*/public void process(WatchedEvent event) {if(this.latch != null) { this.latch.countDown(); }}/*** 获取锁*/public void lock() {if(exception.size() > 0){throw new LockException(exception.get(0));}try {if(this.tryLock()){System.out.println("Thread " + Thread.currentThread().getId() + " " +myZnode + " get lock true");return;}else{waitForLock(waitNode, waitTimeout);//等待获取锁 }} catch (KeeperException e) {throw new LockException(e);} catch (InterruptedException e) {throw new LockException(e);} }/*** 尝试获取锁*/public boolean tryLock() {try {String splitStr = "_lock_";if(lockName.contains(splitStr))throw new LockException("lockName can not contains \\u000B");//创建临时有序子节点myZnode = zk.create(root + "/" + lockName + splitStr, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.EPHEMERAL_SEQUENTIAL);System.err.println(myZnode + " is created ");//取出所有子节点List<String> subNodes = zk.getChildren(root, false);//取出所有lockName的锁List<String> lockObjNodes = new ArrayList<String>();for (String node : subNodes) {String _node = node.split(splitStr)[0];if(_node.equals(lockName)){lockObjNodes.add(node);}}//对所有节点进行默认排序,从小到大 Collections.sort(lockObjNodes);System.out.println(myZnode + "==" + lockObjNodes.get(0));if(myZnode.equals(root+"/"+lockObjNodes.get(0))){//如果是最小的节点,则表示取得锁return true;}//如果不是最小的节点,找到比自己小1的节点String subMyZnode = myZnode.substring(myZnode.lastIndexOf("/") + 1);//获取比当前节点小一级的节点(Collections.binarySearch(lockObjNodes, subMyZnode):获取当前节点的角标)waitNode = lockObjNodes.get(Collections.binarySearch(lockObjNodes, subMyZnode) - 1);} catch (KeeperException e) {throw new LockException(e);} catch (InterruptedException e) {throw new LockException(e);}return false;}public boolean tryLock(long time, TimeUnit unit) {try {if(this.tryLock()){return true;}return waitForLock(waitNode,time);} catch (Exception e) {e.printStackTrace();}return false;}/*** 等待获取锁* @param lower :等待的锁* @param waitTime 最大等待时间* @return* @throws InterruptedException* @throws KeeperException*/private boolean waitForLock(String lower, long waitTime) throws InterruptedException, KeeperException {Stat stat = zk.exists(root + "/" + lower,true);//判断比自己小一个数的节点是否存在,如果不存在则无需等待锁,同时注册监听if(stat != null){System.out.println("Thread " + Thread.currentThread().getId() + " waiting for " + root + "/" + lower);this.latch = new CountDownLatch(1);this.latch.await(waitTime, TimeUnit.MILLISECONDS);this.latch = null;}return true;}/*** 取消锁监控*/public void unlock() {try {System.out.println(Thread.currentThread().getId()+",unlock " + myZnode);zk.delete(myZnode,-1);myZnode = null;//zk.close();} catch (InterruptedException e) {e.printStackTrace();} catch (KeeperException e) {e.printStackTrace();}}/*** 关闭zk链接*/public void closeZk(){try {zk.close();} catch (InterruptedException e) {e.printStackTrace();}}public void lockInterruptibly() throws InterruptedException {this.lock();}public Condition newCondition() {return null;}/*** 自定义异常信息* @author lenovo**/public class LockException extends RuntimeException {private static final long serialVersionUID = 1L;public LockException(String e){super(e);}public LockException(Exception e){super(e);}} }
如有两个线程, 两个线程要同时到mysql中更新一条数据, 对数据库中的数据进行累加更新。由于在分布式环境下, 这两个线程可能存在于不同的机器上的不同jvm进程中, 所以这两个线程的关系就是垮主机跨进程, 使用java中的synchronized锁是搞不定的。
概念,见
Zookeeper概念学习系列之zookeeper实现分布式共享锁
这里的节点也可以为lock。
先执行以下的test3,再执行test4
[zk: localhost:2181(CONNECTED) 9] ls / [monitor, hbase, zookeeper, admin, lock, consumers, config, storm, brokers, controller_epoch] [zk: localhost:2181(CONNECTED) 10] ls /lock [169.254.28.160] [zk: localhost:2181(CONNECTED) 11]
然后,再执行test4
然后,再执行下test4,试试,看看有什么变化
可以看到,在增加。
总的代码是TestCurator.java
package zhouls.bigdata.zkDemo;import java.net.InetAddress;import org.apache.curator.RetryPolicy; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.retry.ExponentialBackoffRetry; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.ZooDefs.Ids; import org.junit.Test;/*** * @author zhouls**/ public class TestCurator {@Testpublic void test1() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 InetAddress localhost = InetAddress.getLocalHost();String ip = localhost.getHostAddress();client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL)//指定节点类型,临时节点.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/monitor/" + ip);//指定节点名称while (true) {;}}@Testpublic void test2() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 InetAddress localhost = InetAddress.getLocalHost();String ip = localhost.getHostAddress();client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL_SEQUENTIAL)// 指定节点类型,注意:临时节点必须在某一个永久节点下面.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/monitor/");// 指定节点名称while (true) {;}}@Testpublic void test3() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 InetAddress localhost = InetAddress.getLocalHost();String ip = localhost.getHostAddress();client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL)//指定节点类型,临时节点.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/lock/" + ip);//指定节点名称while (true) {;}}@Testpublic void test4() throws Exception {// 1000:表示curator链接zk的时候超时时间是多少 3:表示链接zk的最大重试次数RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);String connectString = "master:2181,slave1:2181,slave2:2181";int sessionTimeoutMs = 5000;// 这个值只能在4000-40000ms之间 表示链接断掉之后多长时间临时节点会消失int connectionTimeoutMs = 3000;// 获取链接的超时时间CuratorFramework client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs,retryPolicy);client.start();// 开启客户端 InetAddress localhost = InetAddress.getLocalHost();String ip = localhost.getHostAddress();client.create().creatingParentsIfNeeded()// 如果父节点不存在则创建.withMode(CreateMode.EPHEMERAL_SEQUENTIAL)// 指定节点类型,注意:临时节点必须在某一个永久节点下面.withACL(Ids.OPEN_ACL_UNSAFE)// 设置节点权限信息.forPath("/lock/");// 指定节点名称while (true) {;}}}
DistributedLock.java
package zhouls.bigdata.zkDemo;import java.io.IOException; import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.concurrent.CountDownLatch; import java.util.concurrent.TimeUnit; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock;import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooDefs; import org.apache.zookeeper.ZooKeeper; import org.apache.zookeeper.data.Stat;/**DistributedLock lock = null;try {lock = new DistributedLock("127.0.0.1:2181","test");lock.lock();//do something...} catch (Exception e) {e.printStackTrace();} finally {if(lock != null)lock.unlock();}//lock.closeZk();//在cleanup方法中添加**/ public class DistributedLock implements Lock, Watcher{private ZooKeeper zk;private String root = "/locks";//根private String lockName;//竞争资源的标志private String waitNode;//等待前一个锁private String myZnode;//当前锁private CountDownLatch latch;//计数器private int sessionTimeout = 30000;//30秒private int waitTimeout = 30000;//等待节点失效最大时间 30秒private List<Exception> exception = new ArrayList<Exception>();/*** 创建分布式锁,使用前请确认zkConnString配置的zookeeper服务可用* @param zkConnString 127.0.0.1:2181* @param lockName 竞争资源标志,lockName中不能包含单词lock*/public DistributedLock(String zkConnString, String lockName){this.lockName = lockName;// 创建一个与服务器的连接try {zk = new ZooKeeper(zkConnString, sessionTimeout, this);Stat stat = zk.exists(root, false);if(stat == null){// 创建根节点zk.create(root, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT); }} catch (IOException e) {exception.add(e);} catch (KeeperException e) {exception.add(e);} catch (InterruptedException e) {exception.add(e);}}/*** zookeeper节点的监视器*/public void process(WatchedEvent event) {if(this.latch != null) { this.latch.countDown(); }}/*** 获取锁*/public void lock() {if(exception.size() > 0){throw new LockException(exception.get(0));}try {if(this.tryLock()){System.out.println("Thread " + Thread.currentThread().getId() + " " +myZnode + " get lock true");return;}else{waitForLock(waitNode, waitTimeout);//等待获取锁 }} catch (KeeperException e) {throw new LockException(e);} catch (InterruptedException e) {throw new LockException(e);} }/*** 尝试获取锁*/public boolean tryLock() {try {String splitStr = "_lock_";if(lockName.contains(splitStr))throw new LockException("lockName can not contains \\u000B");//创建临时有序子节点myZnode = zk.create(root + "/" + lockName + splitStr, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE,CreateMode.EPHEMERAL_SEQUENTIAL);System.err.println(myZnode + " is created ");//取出所有子节点List<String> subNodes = zk.getChildren(root, false);//取出所有lockName的锁List<String> lockObjNodes = new ArrayList<String>();for (String node : subNodes) {String _node = node.split(splitStr)[0];if(_node.equals(lockName)){lockObjNodes.add(node);}}//对所有节点进行默认排序,从小到大 Collections.sort(lockObjNodes);System.out.println(myZnode + "==" + lockObjNodes.get(0));if(myZnode.equals(root+"/"+lockObjNodes.get(0))){//如果是最小的节点,则表示取得锁return true;}//如果不是最小的节点,找到比自己小1的节点String subMyZnode = myZnode.substring(myZnode.lastIndexOf("/") + 1);//获取比当前节点小一级的节点(Collections.binarySearch(lockObjNodes, subMyZnode):获取当前节点的角标)waitNode = lockObjNodes.get(Collections.binarySearch(lockObjNodes, subMyZnode) - 1);} catch (KeeperException e) {throw new LockException(e);} catch (InterruptedException e) {throw new LockException(e);}return false;}public boolean tryLock(long time, TimeUnit unit) {try {if(this.tryLock()){return true;}return waitForLock(waitNode,time);} catch (Exception e) {e.printStackTrace();}return false;}/*** 等待获取锁* @param lower :等待的锁* @param waitTime 最大等待时间* @return* @throws InterruptedException* @throws KeeperException*/private boolean waitForLock(String lower, long waitTime) throws InterruptedException, KeeperException {Stat stat = zk.exists(root + "/" + lower,true);//判断比自己小一个数的节点是否存在,如果不存在则无需等待锁,同时注册监听if(stat != null){System.out.println("Thread " + Thread.currentThread().getId() + " waiting for " + root + "/" + lower);this.latch = new CountDownLatch(1);this.latch.await(waitTime, TimeUnit.MILLISECONDS);this.latch = null;}return true;}/*** 取消锁监控*/public void unlock() {try {System.out.println(Thread.currentThread().getId()+",unlock " + myZnode);zk.delete(myZnode,-1);myZnode = null;//zk.close();} catch (InterruptedException e) {e.printStackTrace();} catch (KeeperException e) {e.printStackTrace();}}/*** 关闭zk链接*/public void closeZk(){try {zk.close();} catch (InterruptedException e) {e.printStackTrace();}}public void lockInterruptibly() throws InterruptedException {this.lock();}public Condition newCondition() {return null;}/*** 自定义异常信息* @author lenovo**/public class LockException extends RuntimeException {private static final long serialVersionUID = 1L;public LockException(String e){super(e);}public LockException(Exception e){super(e);}} }
这个代码里,大家可以改为自己的集群,如我的是master:2181,slave1:2181,slave2:2181
本文转自大数据躺过的坑博客园博客,原文链接:http://www.cnblogs.com/zlslch/p/7242381.html,如需转载请自行联系原作者
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