bug in CommitRecords?

[vtolstov]

https://pkg.go.dev/github.com/twmb/franz-go/pkg/kgo#Client.CommitRecords

GROUP           TOPIC           PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             CONSUMER-ID                               HOST            CLIENT-ID
test            test            14         113803          113804          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            6          70845           70846           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            17         83443           83444           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            20         92923           92924           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            29         115043          115044          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            23         91864           91865           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            24         163181          163182          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            11         126313          126314          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            10         26007           26008           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            28         49406           49407           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            19         189287          189288          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            0          143943          143944          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            7          47460           47461           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            18         293857          293858          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            22         78649           78650           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            25         130283          130284          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            5          139839          139840          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            8          229405          229406          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            1          177599          177600          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            26         143427          143428          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            27         227426          227427          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            13         48765           48766           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            4          205139          205140          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            30         217249          217250          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            16         118387          118388          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            9          183699          183700          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            3          227301          227302          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            21         91192           91193           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            12         180762          180763          1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            32         88184           88185           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            15         38668           38669           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            2          77828           77829           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test
test            test            31         26093           26094           1               test-f556d15a-12a5-433d-af67-fe107b303a6b /172.18.0.1     test

[vtolstov]

as you see lag always 1 and after i'm restart test last record always processed.

[vtolstov]

i have such issue in other kafka driver (segmentio/kafka-go) when commit current record offset and not next offset.
https://kafka.apache.org/22/javadoc/index.html?org/apache/kafka/clients/consumer/KafkaConsumer.html#:~:text=Note%3A%20The%20committed%20offset%20should,of%20the%20last%20message%20processed

can you check this? or i have may be error in my code (but i dont think so)
https://github.com/unistack-org/micro-broker-kgo/blob/master/kgo.go#L486 (this is my code, i'm simply run CommitRecords)

[vtolstov]

@twmb i think you need to https://github.com/twmb/franz-go/blob/v0.10.1/pkg/kgo/consumer_group.go#L1687 add +1 to offset from record. in this case you don't have lag with 1 message and not double process last message each time

[vtolstov]

i'm check my proposed solution and after r.Offset + 1 in 1687 lag goes to 0 and messages after restart not double processed

[vtolstov]

fix #65

[twmb]

Thank you, very obvious bug, great catch!