RocketMQ-广播模式注意事项

消费进度存放

存放于conmser实例所在机器的${user.home}/.rocketmq_offsets/MQClientId/ConsumerGroup/offsets.json文件中

public class LocalFileOffsetStore {
    public final static String LOCAL_OFFSET_STORE_DIR = System.getProperty(
        "rocketmq.client.localOffsetStoreDir",
        System.getProperty("user.home") + File.separator + ".rocketmq_offsets");

    this.mQClientFactory = mQClientFactory;
        this.groupName = groupName;
        this.storePath = LOCAL_OFFSET_STORE_DIR + File.separator +
            // clientId默认为DEFAULT
            this.mQClientFactory.getClientId() + File.separator +
            this.groupName + File.separator +
            "offsets.json";
    }
}

public class ClientConfig {
    private String instanceName = System.getProperty("rocketmq.client.name", "DEFAULT");
}
public class DefaultMQPushConsumerImpl implements MQConsumerInner {
    public synchronized void start() throws MQClientException {
        //只有在集群模式下，才会将DEFAULT替换成pid
        if (this.defaultMQPushConsumer.getMessageModel() == MessageModel.CLUSTERING) {
            this.defaultMQPushConsumer.changeInstanceNameToPID();
        }
    }
}

所以如果你希望在同一台机器上部署同一个ConsumerGroup的多个consumer实例，那么一定一定要自定义实例consumer的instanceName参数，否则会导致不同的consumer实例修改同一份offsets.json文件，导致消费进度错乱。