问题
max.poll.records has been recently changed to 500 in kafka consumer config, but I am wondering how does this affect the consumer poll. Is it just an upper bound of the maximum number of records that could be fetched or the consumer waits till it gets 500 records.
回答1:
max.poll.records : Yes from new consumer this property is changed to 500 by default which means consumer can poll minimum 1 to max 500 records for each poll, and which means consumer will not wait when partition did not have sufficient data
fetch.min.bytes : By default it is 1 byte, consumer will wait if you increase this configuration.
The minimum amount of data the server should return for a fetch request. If insufficient data is available the request will wait for that much data to accumulate before answering the request. The default setting of 1 byte means that fetch requests are answered as soon as a single byte of data is available or the fetch request times out waiting for data to arrive. Setting this to something greater than 1 will cause the server to wait for larger amounts of data to accumulate which can improve server throughput a bit at the cost of some additional latency.
来源：https://stackoverflow.com/questions/53308986/how-does-max-poll-records-affect-the-consumer-poll