zookeeper Curator 场景应用

最新推荐文章于 2024-07-23 10:29:11 发布

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最新推荐文章于 2024-07-23 10:29:11 发布

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本文链接：https://blog.youkuaiyun.com/lm324114/article/details/71056013

本文介绍如何使用Apache Curator实现分布式锁、计数器、Barrier等功能，确保在分布式系统中的一致性和协调性。

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分布式锁功能：

在分布式场景中，我们为了保证数据的一致性，经常在程序运行的某一个点需要进行同步操作（java可提供synchronzied或者reentrantlock），分布式不同步的问题：

因为我们之前所说的是在高并发下访问程序，现在我们则是在高并发下访问多个服务器节点

我们使用 curator基于zookeeper的特性提供分布式锁来处理分布式场景的数据一致性，zookeeper本身的分布式是有写问题的

我们用代码来模拟实现一下：

package bjsxt.curator.lock;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.locks.ReentrantLock;

import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.locks.InterProcessMutex;
import org.apache.curator.retry.ExponentialBackoffRetry;


public class Lock2 {

	/** zookeeper地址 */
	static final String CONNECT_ADDR = "192.168.1.171:2181,192.168.1.172:2181,192.168.1.173:2181";
	/** session超时时间 */
	static final int SESSION_OUTTIME = 5000;//ms 
	
	static int count = 10;
	public static void genarNo(){
		try {
			count--;
			System.out.println(count);
		} finally {
		
		}
	}
	
	public static void main(String[] args) throws Exception {
		
		//1 重试策略：初试时间为1s 重试10次
		RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
		//2 通过工厂创建连接
		CuratorFramework cf = CuratorFrameworkFactory.builder()
					.connectString(CONNECT_ADDR)
					.sessionTimeoutMs(SESSION_OUTTIME)
					.retryPolicy(retryPolicy)
//					.namespace("super")
					.build();
		//3 开启连接
		cf.start();
		
		//4 分布式锁
		final InterProcessMutex lock = new InterProcessMutex(cf, "/super");
		//final ReentrantLock reentrantLock = new ReentrantLock();
		final CountDownLatch countdown = new CountDownLatch(1);
		
		for(int i = 0; i < 10; i++){
			new Thread(new Runnable() {
				@Override
				public void run() {
					try {
						countdown.await();
						//加锁
						lock.acquire();
						//reentrantLock.lock();
						//-------------业务处理开始
						//genarNo();
						SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss|SSS");
						System.out.println(sdf.format(new Date()));
						//System.out.println(System.currentTimeMillis());
						//-------------业务处理结束
					} catch (Exception e) {
						e.printStackTrace();
					} finally {
						try {
							//释放
							lock.release();
							//reentrantLock.unlock();
						} catch (Exception e) {
							e.printStackTrace();
						}
					}
				}
			},"t" + i).start();
		}
		Thread.sleep(100);
		countdown.countDown();
		
		
		
		
		
		
		
		
		
		
		
		
		
		 
	}
}

分布式计数器功能：

一说到分布式计数器，你可能脑海里想到了AtomicInteger这中经典的方式，如果针对一个jvm 的场景当然没问题，但是我们现在是分布式场景下，就需要利用Curator框架的DistrbutedAtomicInteger了。

package bjsxt.curator.atomicinteger;

import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.atomic.AtomicValue;
import org.apache.curator.framework.recipes.atomic.DistributedAtomicInteger;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.retry.RetryNTimes;

public class CuratorAtomicInteger {

	/** zookeeper地址 */
	static final String CONNECT_ADDR = "192.168.1.128:2181,192.168.1.131:2181,192.168.1.130:2181";
	/** session超时时间 */
	static final int SESSION_OUTTIME = 5000;//ms 
	
	public static void main(String[] args) throws Exception {
		
		//1 重试策略：初试时间为1s 重试10次
		RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
		//2 通过工厂创建连接
		CuratorFramework cf = CuratorFrameworkFactory.builder()
					.connectString(CONNECT_ADDR)
					.sessionTimeoutMs(SESSION_OUTTIME)
					.retryPolicy(retryPolicy)
					.build();
		//3 开启连接
		cf.start();
		//cf.delete().forPath("/super");
		

		//4 使用DistributedAtomicInteger
		DistributedAtomicInteger atomicIntger = 
				new DistributedAtomicInteger(cf, "/super", new RetryNTimes(3, 1000));
		
		AtomicValue<Integer> value = atomicIntger.add(1);
		System.out.println(value.succeeded());
		System.out.println(value.postValue());	//最新值
		System.out.println(value.preValue());	//原始值
		
	}
}

输出结果：

log4j:WARN No appenders could be found for logger (org.apache.curator.CuratorZookeeperClient).
log4j:WARN Please initialize the log4j system properly.
true
1
0

DistributedBarrier 、DistributedDoubleBarrier

package bjsxt.curator.barrier;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.atomic.AtomicValue;
import org.apache.curator.framework.recipes.atomic.DistributedAtomicInteger;
import org.apache.curator.framework.recipes.barriers.DistributedBarrier;
import org.apache.curator.framework.recipes.queue.DistributedQueue;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.retry.RetryNTimes;

public class CuratorBarrier2 {

	/** zookeeper地址 */
	static final String CONNECT_ADDR = "192.168.1.131:2181,192.168.1.128:2181,192.168.1.130:2181";
	/** session超时时间 */
	static final int SESSION_OUTTIME = 5000;//ms 
	
	static DistributedBarrier barrier = null;
	
	public static void main(String[] args) throws Exception {
		
		
		
		for(int i = 0; i < 5; i++){
			new Thread(new Runnable() {
				@Override
				public void run() {
					try {
						RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
						CuratorFramework cf = CuratorFrameworkFactory.builder()
									.connectString(CONNECT_ADDR)
									.sessionTimeoutMs(SESSION_OUTTIME)
									.retryPolicy(retryPolicy)
									.build();
						cf.start();
						barrier = new DistributedBarrier(cf, "/super");
						System.out.println(Thread.currentThread().getName() + "设置barrier!");
						barrier.setBarrier();	//设置
						barrier.waitOnBarrier();	//等待
						System.out.println("---------开始执行程序----------");
					} catch (Exception e) {
						e.printStackTrace();
					}
				}
			},"t" + i).start();
		}

		Thread.sleep(5000);
		barrier.removeBarrier();	//释放
		
		
	}
}

package bjsxt.curator.barrier;

import java.util.Random;

import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.barriers.DistributedDoubleBarrier;
import org.apache.curator.retry.ExponentialBackoffRetry;

public class CuratorBarrier1 {

	/** zookeeper地址 */
	static final String CONNECT_ADDR = "192.168.1.128:2181,192.168.1.130:2181,192.168.1.131:2181";
	/** session超时时间 */
	static final int SESSION_OUTTIME = 5000;//ms 
	
	public static void main(String[] args) throws Exception {
		
		
		
		for(int i = 0; i < 5; i++){
			new Thread(new Runnable() {
				@Override
				public void run() {
					try {
						RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
						CuratorFramework cf = CuratorFrameworkFactory.builder()
									.connectString(CONNECT_ADDR)
									.retryPolicy(retryPolicy)
									.build();
						cf.start();
						
						DistributedDoubleBarrier barrier = new DistributedDoubleBarrier(cf, "/super", 5);
						Thread.sleep(1000 * (new Random()).nextInt(3)); 
						System.out.println(Thread.currentThread().getName() + "已经准备");
						barrier.enter();
						System.out.println("同时开始运行...");
						Thread.sleep(1000 * (new Random()).nextInt(3));
						System.out.println(Thread.currentThread().getName() + "运行完毕");
						barrier.leave();
						System.out.println("同时退出运行...");
						

					} catch (Exception e) {
						e.printStackTrace();
					}
				}
			},"t" + i).start();
		}

		
		
	}
}