kafka高可用探究
眾所周知 kafka 的 topic 可以使用 –replication-factor 數和 partitions 數來保證服務的高可用性
問題發現
查了很多資料後發現是kafka本身的 topic __consumer_offsets 搞的鬼。
問題分析
在高版本的kakfa中，消費者的offset偏移量會保存在kafka自身一個叫做__consumer_offsets的topic中，由於這個topic是由kafka本身默認創建，所以副本數會配置文件中指定的默認副本數，一般為1。
查看副本分區情況一般為：
./kafka-topics.sh --zookeeper localhost:2181 --describe __consumer_offsets Topic:__consumer_offsets PartitionCount:50 ReplicationFactor:1 Configs:segment.bytes=104857600,cleanup.policy=compact,compression.type=producer Topic: __consumer_offsets Partition: 0 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 1 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 2 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 3 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 4 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 5 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 6 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 7 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 8 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 9 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 10 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 11 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 12 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 13 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 14 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 15 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 16 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 17 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 18 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 19 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 20 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 21 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 22 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 23 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 24 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 25 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 26 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 27 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 28 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 29 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 30 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 31 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 32 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 33 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 34 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 35 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 36 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 37 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 38 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 39 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 40 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 41 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 42 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 43 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 44 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 45 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 46 Leader: 1 Replicas: 1 Isr: 1 Topic: __consumer_offsets Partition: 47 Leader: 2 Replicas: 2 Isr: 2 Topic: __consumer_offsets Partition: 48 Leader: 3 Replicas: 3 Isr: 3 Topic: __consumer_offsets Partition: 49 Leader: 1 Replicas: 1 Isr: 1
50個分區，每個分區1個副本。
50個分區是遍布在3台broker的，這就導致如果有其中一台broker服務掛了，在其broker的所有Partition將不能正常使用，就導致此Partition的消費者不知道自己的offset偏移量，就導致無法正常消費。
問題解決
方法1
由於現在kafka已經開始正常提供服務，所以只能動態修改：
先準備分區副本規劃 json 文件
vim /data/vfan/consumer.json
{ "version": 1, "partitions": [ { "topic": "__consumer_offsets", "partition": 0, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 1, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 2, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 3, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 4, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 5, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 6, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 7, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 8, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 9, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 10, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 11, "replicas": [ 3, 1, 2 ] }, { "topic": "__consumer_offsets", "partition": 12, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 13, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 14, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 15, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 16, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 17, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 18, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 19, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 20, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 21, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 22, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 23, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 24, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 25, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 26, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 27, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 28, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 29, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 30, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 31, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 32, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 33, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 34, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 35, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 36, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 37, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 38, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 39, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 40, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 41, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 42, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 43, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 44, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 45, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 46, "replicas": [ 3, 2, 1 ] }, { "topic": "__consumer_offsets", "partition": 47, "replicas": [ 1, 2, 3 ] }, { "topic": "__consumer_offsets", "partition": 48, "replicas": [ 2, 1, 3 ] }, { "topic": "__consumer_offsets", "partition": 49, "replicas": [ 3, 2, 1 ] } ] }
各 replicas 所在的 broker id可以自定義修改，但不能有重複的broker
開始執行變更
./kafka-reassign-partitions.sh --zookeeper localhost:2181 --reassignment-json-file /data/vfan/consumer.json --execute
校驗變更是否完成
./kafka-reassign-partitions.sh --zookeeper localhost:2181 --reassignment-json-file /data/vfan/consumer.json --verify
檢查變更後效果
./kafka-topics.sh --zookeeper localhost:2181 --describe --topic __consumer_offsets Topic:__consumer_offsets PartitionCount:50 ReplicationFactor:3 Configs:segment.bytes=104857600,cleanup.policy=compact,compression.type=producer Topic: __consumer_offsets Partition: 0 Leader: 1 Replicas: 1,2,3 Isr: 3,2,1 Topic: __consumer_offsets Partition: 1 Leader: 2 Replicas: 2,1,3 Isr: 1,2,3 Topic: __consumer_offsets Partition: 2 Leader: 3 Replicas: 3,2,1 Isr: 2,3,1 Topic: __consumer_offsets Partition: 3 Leader: 1 Replicas: 1,2,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 4 Leader: 2 Replicas: 2,1,3 Isr: 1,2,3 Topic: __consumer_offsets Partition: 5 Leader: 3 Replicas: 3,2,1 Isr: 2,3,1 Topic: __consumer_offsets Partition: 6 Leader: 1 Replicas: 1,2,3 Isr: 3,2,1 Topic: __consumer_offsets Partition: 7 Leader: 2 Replicas: 2,1,3 Isr: 1,2,3 Topic: __consumer_offsets Partition: 8 Leader: 3 Replicas: 3,2,1 Isr: 2,1,3 Topic: __consumer_offsets Partition: 9 Leader: 1 Replicas: 1,2,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 10 Leader: 2 Replicas: 2,1,3 Isr: 1,2,3 Topic: __consumer_offsets Partition: 11 Leader: 3 Replicas: 3,1,2 Isr: 2,3,1 Topic: __consumer_offsets Partition: 12 Leader: 2 Replicas: 2,1,3 Isr: 3,2,1 Topic: __consumer_offsets Partition: 13 Leader: 1 Replicas: 1,2,3 Isr: 1,2,3 Topic: __consumer_offsets Partition: 14 Leader: 1 Replicas: 1,2,3 Isr: 2,3,1 Topic: __consumer_offsets Partition: 15 Leader: 2 Replicas: 2,1,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 16 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3 Topic: __consumer_offsets Partition: 17 Leader: 1 Replicas: 1,2,3 Isr: 2,3,1 Topic: __consumer_offsets Partition: 18 Leader: 2 Replicas: 2,1,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 19 Leader: 3 Replicas: 3,2,1 Isr: 1,3,2 Topic: __consumer_offsets Partition: 20 Leader: 1 Replicas: 1,2,3 Isr: 2,3,1 Topic: __consumer_offsets Partition: 21 Leader: 2 Replicas: 2,1,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 22 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3 Topic: __consumer_offsets Partition: 23 Leader: 1 Replicas: 1,2,3 Isr: 2,1,3 Topic: __consumer_offsets Partition: 24 Leader: 2 Replicas: 2,1,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 25 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3 Topic: __consumer_offsets Partition: 26 Leader: 1 Replicas: 1,2,3 Isr: 2,3,1 Topic: __consumer_offsets Partition: 27 Leader: 2 Replicas: 2,1,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 28 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3 Topic: __consumer_offsets Partition: 29 Leader: 1 Replicas: 1,2,3 Isr: 2,3,1 Topic: __consumer_offsets Partition: 30 Leader: 2 Replicas: 2,1,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 31 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3 Topic: __consumer_offsets Partition: 32 Leader: 1 Replicas: 1,2,3 Isr: 2,3,1 Topic: __consumer_offsets Partition: 33 Leader: 2 Replicas: 2,1,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 34 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3 Topic: __consumer_offsets Partition: 35 Leader: 1 Replicas: 1,2,3 Isr: 2,1,3 Topic: __consumer_offsets Partition: 36 Leader: 2 Replicas: 2,1,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 37 Leader: 3 Replicas: 3,2,1 Isr: 1,3,2 Topic: __consumer_offsets Partition: 38 Leader: 1 Replicas: 1,2,3 Isr: 2,3,1 Topic: __consumer_offsets Partition: 39 Leader: 2 Replicas: 2,1,3 Isr: 3,2,1 Topic: __consumer_offsets Partition: 40 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3 Topic: __consumer_offsets Partition: 41 Leader: 1 Replicas: 1,2,3 Isr: 2,1,3 Topic: __consumer_offsets Partition: 42 Leader: 2 Replicas: 2,1,3 Isr: 3,1,2 Topic: __consumer_offsets Partition: 43 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3 Topic: __consumer_offsets Partition: 44 Leader: 1 Replicas: 1,2,3 Isr: 2,3,1 Topic: __consumer_offsets Partition: 45 Leader: 2 Replicas: 2,1,3 Isr: 3,2,1 Topic: __consumer_offsets Partition: 46 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3 Topic: __consumer_offsets Partition: 47 Leader: 1 Replicas: 1,2,3 Isr: 2,1,3 Topic: __consumer_offsets Partition: 48 Leader: 2 Replicas: 2,1,3 Isr: 3,2,1 Topic: __consumer_offsets Partition: 49 Leader: 3 Replicas: 3,2,1 Isr: 1,2,3
副本數已經成為三個並分布在三個broker中，實現高可用。
方法2
直接在kafka服務啟動前，修改系統創建topic默認副本分區參數
num.partitions=3 ;當topic不存在系統自動創建時的分區數 default.replication.factor=3 ;當topic不存在系統自動創建時的副本數 offsets.topic.replication.factor=3 ；表示kafka的內部topic consumer_offsets副本數，默認為1
設置完畢後，啟動 zk kafka，隨後測試生產 消費
## 生產 ./kafka-console-producer.sh --broker-list localhost:9092 --topic test ## 消費，--from-beginning參數表示從頭開始 ./kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test --from-beginning
查看系統生成的topic 分區及副本數
## test ./kafka-topics.sh --zookeeper localhost:2181 --describe --topic test Topic:test PartitionCount:3 ReplicationFactor:3 Configs: ## __consumer_offsets ./kafka-topics.sh --zookeeper localhost:2181 --describe --topic __consumer_offsets Topic:__consumer_offsets PartitionCount:50 ReplicationFactor:3 Configs:segment.bytes=104857600,cleanup.policy=compact,compression.type=producer
系統自動生成的topic也都已實現高可用
