如何在CentOS上使用Zookeeper进行分布式锁管理

在CentOS上使用Zookeeper进行分布式锁管理，可以按照以下步骤进行：

1. 安装Zookeeper

首先，需要在CentOS上安装Zookeeper。可以通过以下命令来安装：

sudo yum install zookeeper zookeeper-server

2. 配置Zookeeper

编辑Zookeeper的配置文件/etc/zookeeper/conf/zoo.cfg，确保配置正确。以下是一个基本的配置示例：

tickTime=2000
dataDir=/var/lib/zookeeper
clientPort=2181
initLimit=5
syncLimit=2
server.1=zoo1:2888:3888
server.2=zoo2:2888:3888
server.3=zoo3:2888:3888

确保dataDir目录存在并且Zookeeper有权限访问。

3. 启动Zookeeper

启动Zookeeper服务：

sudo systemctl start zookeeper

检查Zookeeper的状态：

sudo systemctl status zookeeper

4. 使用Zookeeper进行分布式锁

可以使用Java客户端库来与Zookeeper进行交互。以下是一个简单的示例代码，展示如何使用Zookeeper实现分布式锁：

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;

import java.io.IOException;
import java.util.Collections;
import java.util.List;

public class DistributedLock {
    private static final String ZK_ADDRESS = "localhost:2181";
    private static final int SESSION_TIMEOUT = 3000;
    private static final String LOCK_ROOT = "/locks";
    private static final String LOCK_NODE = LOCK_ROOT + "/lock_";

    private ZooKeeper zk;
    private String lockPath;

    public DistributedLock() throws IOException, InterruptedException, KeeperException {
        zk = new ZooKeeper(ZK_ADDRESS, SESSION_TIMEOUT, new Watcher() {
            @Override
            public void process(WatchedEvent event) {
                // Do nothing for now
            }
        });

        // Ensure the root lock node exists
        Stat stat = zk.exists(LOCK_ROOT, false);
        if (stat == null) {
            zk.create(LOCK_ROOT, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        }
    }

    public void lock() throws KeeperException, InterruptedException {
        lockPath = zk.create(LOCK_NODE, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);

        while (true) {
            List<String> children = zk.getChildren(LOCK_ROOT, false);
            Collections.sort(children);
            String smallestChild = children.get(0);

            if (lockPath.endsWith(smallestChild)) {
                // We have the lock
                return;
            } else {
                // Wait for the node to be deleted
                int index = Collections.binarySearch(children, lockPath.substring(LOCK_ROOT.length() + 1));
                String watchNode = LOCK_ROOT + "/" + children.get(index - 1);

                Stat stat = zk.exists(watchNode, new Watcher() {
                    @Override
                    public void process(WatchedEvent event) {
                        if (event.getType() == Event.EventType.NodeDeleted) {
                            synchronized (this) {
                                notifyAll();
                            }
                        }
                    }
                });

                if (stat != null) {
                    synchronized (this) {
                        wait();
                    }
                }
            }
        }
    }

    public void unlock() throws KeeperException, InterruptedException {
        if (lockPath != null) {
            zk.delete(lockPath, -1);
            lockPath = null;
        }
    }

    public static void main(String[] args) {
        try {
            DistributedLock lock = new DistributedLock();
            lock.lock();
            System.out.println("Lock acquired");

            // Perform some critical section operations

            lock.unlock();
            System.out.println("Lock released");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

5. 编译和运行

确保你已经添加了Zookeeper客户端库到你的项目中。如果你使用Maven，可以在pom.xml中添加以下依赖：

<dependency>
    <groupId>org.apache.zookeeper</groupId>
    <artifactId>zookeeper</artifactId>
    <version>3.7.0</version>
</dependency>

编译并运行你的Java程序：

mvn compile exec:java -Dexec.mainClass="DistributedLock"

通过以上步骤，你可以在CentOS上使用Zookeeper实现分布式锁管理。