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问题分析

• 自己在测试环境部署了RocketMQ，发现namesrv很容易挂掉，于是就想着监控，挂了就发邮件通知。
• 查看了rocketmq-dashboard项目，发现只能监控Broker，遂放弃这一路径。
• 于是就从报错的日志入手，发现最终可以根据RocketMQTemplate获得可活动的NameServer。

报错日志

• 报错日志如下：

12月 25 13:59:22 192.168.240.65 java[59571]: 2023-12-25 13:59:22.598  INFO 59571 --- [tWorkerThread_2] RocketmqRemoting                         : NETTY CLIENT PIPELINE: CLOSE 192.168.240.86:9876
12月 25 13:59:22 192.168.240.65 java[59571]: 2023-12-25 13:59:22.598  INFO 59571 --- [tWorkerThread_2] RocketmqRemoting                         : closeChannel: the channel[192.168.240.86:9876] was removed from channel table
12月 25 13:59:22 192.168.240.65 java[59571]: 2023-12-25 13:59:22.598  INFO 59571 --- [tWorkerThread_2] RocketmqRemoting                         : NETTY CLIENT PIPELINE: CLOSE 192.168.240.86:9876
12月 25 13:59:22 192.168.240.65 java[59571]: 2023-12-25 13:59:22.598  INFO 59571 --- [tWorkerThread_2] RocketmqRemoting                         : eventCloseChannel: the channel[null] has been removed from the channel table before
12月 25 13:59:22 192.168.240.65 java[59571]: 2023-12-25 13:59:22.598  INFO 59571 --- [lientSelector_1] RocketmqRemoting                         : closeChannel: close the connection to remote address[192.168.240.86:9876] result: true
12月 25 13:59:25 192.168.240.65 java[59571]: 2023-12-25 13:59:25.597  INFO 59571 --- [ntScan_thread_1] RocketmqRemoting                         : createChannel: begin to connect remote host[192.168.240.86:9876] asynchronously
12月 25 13:59:25 192.168.240.65 java[59571]: 2023-12-25 13:59:25.597  INFO 59571 --- [tWorkerThread_3] RocketmqRemoting                         : NETTY CLIENT PIPELINE: CONNECT  UNKNOWN => 192.168.240.86:9876
12月 25 13:59:25 192.168.240.65 java[59571]: 2023-12-25 13:59:25.598  WARN 59571 --- [ntScan_thread_1] RocketmqRemoting                         : createChannel: connect remote host[192.168.240.86:9876] failed, AbstractBootstrap$PendingRegistrationPromise@f2a3fc5(failure: io.netty.channel.AbstractChannel$AnnotatedConnectException: 拒绝连接: /192.168.240.86:9876)

• 根据日志可以发现是NettyRemotingClient类在做监控，持续调用，具体核心方法：

org.apache.rocketmq.remoting.netty.NettyRemotingClient#createChannel

• createChannel的源码：

private Channel createChannel(String addr) throws InterruptedException {NettyRemotingClient.ChannelWrapper cw = (NettyRemotingClient.ChannelWrapper)this.channelTables.get(addr);if (cw != null && cw.isOK()) {return cw.getChannel();} else {if (this.lockChannelTables.tryLock(3000L, TimeUnit.MILLISECONDS)) {try {cw = (NettyRemotingClient.ChannelWrapper)this.channelTables.get(addr);boolean createNewConnection;if (cw != null) {if (cw.isOK()) {Channel var4 = cw.getChannel();return var4;}if (!cw.getChannelFuture().isDone()) {createNewConnection = false;} else {this.channelTables.remove(addr);createNewConnection = true;}} else {createNewConnection = true;}if (createNewConnection) {ChannelFuture channelFuture = this.bootstrap.connect(RemotingHelper.string2SocketAddress(addr));LOGGER.info("createChannel: begin to connect remote host[{}] asynchronously", addr);cw = new NettyRemotingClient.ChannelWrapper(channelFuture);this.channelTables.put(addr, cw);}} catch (Exception var8) {LOGGER.error("createChannel: create channel exception", var8);} finally {this.lockChannelTables.unlock();}} else {LOGGER.warn("createChannel: try to lock channel table, but timeout, {}ms", 3000L);}if (cw != null) {ChannelFuture channelFuture = cw.getChannelFuture();if (channelFuture.awaitUninterruptibly((long)this.nettyClientConfig.getConnectTimeoutMillis())) {if (cw.isOK()) {LOGGER.info("createChannel: connect remote host[{}] success, {}", addr, channelFuture.toString());return cw.getChannel();}LOGGER.warn("createChannel: connect remote host[" + addr + "] failed, " + channelFuture.toString());} else {LOGGER.warn("createChannel: connect remote host[{}] timeout {}ms, {}", new Object[]{addr, this.nettyClientConfig.getConnectTimeoutMillis(), channelFuture.toString()});}}return null;}}

• 从源码中可以看到报错的日志数据

追溯

• 以NettyRemotingClient类为起点，使用Debug分析，最终可以看到完整的调用链路：
  

监控开发

• 那么监控开发就很容易了，注册RocketMQTemplate，使用定时任务监听即可，示例代码如下：

@Slf4j
@Component
public class MQMonitorTask {@Resourceprivate RocketMQTemplate rocketMQTemplate;@Scheduled(cron = "0/10 * * * * ?")public void scanNameServerBroker() {org.apache.rocketmq.remoting.RemotingClient remotingClient = rocketMQTemplate.getProducer().getDefaultMQProducerImpl().getMqClientFactory().getMQClientAPIImpl().getRemotingClient();// 注册的 NameServerList<String> nameServerAddressList = remotingClient.getNameServerAddressList();// 当前活跃的 NameServerList<String> availableNameSrvList = remotingClient.getAvailableNameSrvList();log.info("nameServerAddressList:{}", JSONUtil.toJsonStr(nameServerAddressList));log.info("availableNameSrvList:{}", JSONUtil.toJsonStr(availableNameSrvList));// 只要 nameServerAddressList 和 availableNameSrvList 大小不一致，即可做邮件通知，具体阈值自己设置！！！// TODO:邮件通知}}

• 另外要在SprongBoot启动类加上注解@EnableScheduling来开启定时任务。