Kafka - 经纪人：集团协调员不可用 [英] Kafka - Broker: Group coordinator not available

问题描述

我有以下结构：

zookeeper: 3.4.12
kafka: kafka_2.11-1.1.0
server1: zookeeper + kafka
server2: zookeeper + kafka
server3: zookeeper + kafka

使用kafka-topics shell脚本创建复制因子3和分区3的主题。

Created topic with replication factor 3 and partitions 3 by kafka-topics shell script.

./kafka-topics.sh --create --zookeeper localhost:2181 --topic test-flow --partitions 3 --replication-factor 3

并使用group localConsumers。领导者还可以。它可行。

And use group localConsumers. it works fine when leader is ok.

./kafka-topics.sh --describe --zookeeper localhost:2181 --topic test-flow
Topic:test-flow PartitionCount:3    ReplicationFactor:3 Configs:
    Topic: test-flow    Partition: 0    Leader: 3   Replicas: 3,2,1 Isr: 3,2,1
    Topic: test-flow    Partition: 1    Leader: 1   Replicas: 1,3,2 Isr: 1,3,2
    Topic: test-flow    Partition: 2    Leader: 2   Replicas: 2,1,3 Isr: 2,1,3

消费者日志

Received FindCoordinator response ClientResponse(receivedTimeMs=1529508772673, latencyMs=217, disconnected=false, requestHeader=RequestHeader(apiKey=FIND_COORDINATOR, apiVersion=1, clientId=consumer-1, correlationId=0), responseBody=FindCoordinatorResponse(throttleTimeMs=0, errorMessage='null', error=NONE, node=myserver3:9092 (id: 3 rack: null)))

但如果领导者失败 - 我在消费者中遇到错误（systemctl stop kafka）：

But if leader is down - I get the error in consumer (systemctl stop kafka):

节点3不可用。好的

./kafka-topics.sh --describe --zookeeper localhost:2181 --topic test-flow
Topic:test-flow PartitionCount:3    ReplicationFactor:3 Configs:
    Topic: test-flow    Partition: 0    Leader: 2   Replicas: 3,2,1 Isr: 2,1
    Topic: test-flow    Partition: 1    Leader: 1   Replicas: 1,3,2 Isr: 1,2
    Topic: test-flow    Partition: 2    Leader: 2   Replicas: 2,1,3 Isr: 2,1

消费者日志

Received FindCoordinator response 
ClientResponse(receivedTimeMs=1529507314193, latencyMs=36, 
disconnected=false, 
requestHeader=RequestHeader(apiKey=FIND_COORDINATOR, apiVersion=1, 
clientId=consumer-1, correlationId=149), 
responseBody=FindCoordinatorResponse(throttleTimeMs=0, 
errorMessage='null', error=COORDINATOR_NOT_AVAILABLE, node=:-1 (id: -1 
rack: null)))

- Group coordinator lookup failed: The coordinator is not available.
- Coordinator discovery failed, refreshing metadata

消费者无法连接，直到领导者关闭或重新连接与另一个消费者群体。

Consumer unable to connect until leader is down or reconnect with another consumer group.

无法理解为什么会这样？
消费者应该重新平衡到另一个经纪人，但事实并非如此。

Can't understand why it happens? Consumer should be rebalanced to another broker, but it doesn't.

推荐答案

尝试向服务器添加属性.conf并清理zookeeper缓存。
应该有帮助

Try to add properties into the server.conf and clean zookeeper cache. It should help

offsets.topic.replication.factor=3
default.replication.factor=3

此问题的根本原因是不可能在节点之间分配主题偏移。

Root cause of this issue is impossibility to distribute topic offsets between nodes.

自动生成的主题：
__consumer_offsets

Auto generated topic: __consumer_offsets

您可以查看：
./kafka-topics.sh --describe --zookeeper localhost：2181 --topic __consumer_offsets

You can check it by: ./kafka-topics.sh --describe --zookeeper localhost:2181 --topic __consumer_offsets

注意这篇文章：
https://kafka.apache.org/documentation/#prodconfig

默认情况下使用RF创建__consumer_offsets - 1

by default it creates __consumer_offsets with RF - 1

重要的是在kafka / cluster启动之前配置复制因子。
否则它可能会带来一些重新配置实例的问题，例如你的情况。

Important thing is to configure replication factor before the kafka/cluster start. Otherwise it can bring some issues with re configuring instances like in your case.

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