Kafka Rest Proxy Api 消息分布不均匀

Question

I have 2 partitions and messages in avro-format. I send the messages via kafka rest proxy api. I use the key for the messages. The key is a string. For example, there are my keys:

41:46-300, 41:45-300, 41:44-300, 41:43-300, 41:42-300.

But the messages are uneven distributed. In the partition 0 there are messages with keys 41:46-300, 41:45-300, 41:44-300, 41:43-300 and in the partition 1 there are only messages with the key 41:42-300.

Kafka version: 2.4

Could you explain me Why there is happened?

Answer 1

Kafka uses Murmur2 hashing to distribute keys, not an evenly distributed round-robin mechanism.

So, this means all events in the same partition ended up with hashes that modulo'd into that partition.