Spring kafka消息延迟

Question

使用spring kafka客户端收消息时，日志总是有类似下面的信息，而且会间隔15s以上，有时候30s左右，同时，会出现partitions assigned:[]这样的情况，或者partitions assigned:[test-1]，不在assigned里的partitions就会等到下次reblance成功后才能接受数据。
kafka server只有一台，为什么会发生reblance？有谁了解？

2016-10-13 14:23:43,564 [webOutChannel-0-kafka-consumer-1] [INFO] o.s.k.l.KafkaMessageListenerContainer - partitions revoked:[test2-0]
2016-10-13 14:23:44,186 [serverInChannel-0-kafka-consumer-1] [INFO] o.s.k.l.KafkaMessageListenerContainer - partitions revoked:[test-0, test-1]
2016-10-13 14:23:44,233 [webOutChannel-0-kafka-consumer-1] [INFO] o.s.k.l.KafkaMessageListenerContainer - partitions assigned:[]
2016-10-13 14:23:44,273 [serverInChannel-0-kafka-consumer-1] [INFO] o.s.k.l.KafkaMessageListenerContainer - partitions assigned:[test-1]
2016-10-13 14:24:14,267 [webOutChannel-0-kafka-consumer-1] [INFO] o.s.k.l.KafkaMessageListenerContainer - partitions revoked:[]
2016-10-13 14:24:15,302 [serverInChannel-0-kafka-consumer-1] [INFO] o.s.k.l.KafkaMessageListenerContainer - partitions revoked:[test-1]
2016-10-13 14:24:15,465 [serverInChannel-0-kafka-consumer-1] [INFO] o.s.k.l.KafkaMessageListenerContainer - partitions assigned:[test-0, test-1]
2016-10-13 14:24:15,465 [webOutChannel-0-kafka-consumer-1] [INFO] o.s.k.l.KafkaMessageListenerContainer - partitions assigned:[test2-0]

Answer 1

rebalance的发生不是你的kafka变化，而是你的consumer变化，consumer个数变化