AckCount is invalid when ackMode is Count and ackCount is less than maxPollRecords

[wapkch]

Expected Behavior

Assume we have following settings:

application.properties

spring.kafka.listener.ack-mode=count
spring.kafka.listener.ack-count=100
logging.level.org.springframework.kafka=debug

Expect to commit offset every 100 messages processed

SpringBoot Application:

@RestController
@SpringBootApplication
public class SpringKafkaDemo2Application {

    public static void main(String[] args) {
        SpringApplication.run(SpringKafkaDemo2Application.class, args);
    }

    @KafkaListener(id = "fooGroup", topics = "topic")
    public void listen(ConsumerRecord<String, String> record) throws Exception {
    }

    @Autowired
    private KafkaTemplate<Object, Object> template;

    @PostMapping(path = "/send/{what}")
    public void sendFoo(@PathVariable String what) {
        for (int i = 0; i < 500; i++) {
            this.template.send("topic", "message" + i);
        }
    }

}

Current Behavior

Committing the offset every time after 500 records processed:

2023-07-06T18:07:36.680+08:00 DEBUG 26195 --- [ fooGroup-0-C-1] o.s.k.l.KafkaMessageListenerContainer    : Committing in COUNT because count 500 exceeds configured limit of 100
2023-07-06T18:07:36.680+08:00 DEBUG 26195 --- [ fooGroup-0-C-1] o.s.k.l.KafkaMessageListenerContainer    : Commit list: {topic-0=OffsetAndMetadata{offset=560, leaderEpoch=null, metadata=''}}
2023-07-06T18:07:36.680+08:00 DEBUG 26195 --- [ fooGroup-0-C-1] o.s.k.l.KafkaMessageListenerContainer    : Committing: {topic-0=OffsetAndMetadata{offset=560, leaderEpoch=null, metadata=''}}

Context
Although the larger the ackCount, the better the performance, but it will increase the chance of retransmission, so sometimes it is useful for the ackCount to be smaller than maxPollRecords

[garyrussell]

We currently only consider count and time ack modes just before the next poll.

It's probably not a big change; I'll put it on the backlog.

Contributions are welcome.

[hscom96]

@garyrussell Can i solve this issue?

[garyrussell]

Yes, please go ahead. Please read the contribution guidelines.

[Wzy19930507]

@hscom96 @garyrussell can I pick this up ?

[garyrussell]

Yes, please do.