kafka changefeed don't work even cdc max-message-bytes less then broker topic's

[Tammyxia]

What did you do?

• tidb cluster + capture each has one node which all deployed in a physical server.
• Deploy a broker, then create a topic: bin/kafka-topics.sh --create --topic cdc-events --bootstrap-server 172.16.6.24:9092 --replication-factor 1 --partitions 6
• Check this topic parameters: message.max.bytes = 1000012, max.message.bytes -> 1000012, replica.fetch.max.bytes = 1048576, replica.fetch.max.bytes = 1048576, socket.request.max.bytes = 104857600
• Create a changefeed: tiup ctl:v5.2.1 cdc changefeed create --pd=http://172.16.4.158:2379 --sink-uri='kafka://172.16.6.24:9092/cdc-events?partition-num=6&max-message-bytes=900000' --changefeed-id="kafka-task-1"
• Create one more changefeed: tiup ctl:v5.2.1 cdc changefeed create --pd=http://172.16.4.158:2379 --sink-uri='kafka://172.16.6.24:9092/cdc-events?partition-num=6&max-message-bytes=10000' --changefeed-id="kafka-task-2"
• Run sysbench workload: sysbench oltp_insert run --db-driver=mysql --mysql-host=172.16.4.158 --mysql-port=4000 --mysql-user=root --mysql-password= --mysql-db=test --threads=20 --tables=10 --time=360000 --report-interval=10

What did you expect to see?

The two changefeeds work normally.

What did you see instead?

• Both changefeeds failed to sync any data.

• Using cdc to create a kafka topic test-events, also has error "Message too large": tiup ctl:v5.2.1 cdc changefeed create --pd=http://172.16.4.158:2379 --sink-uri='kafka://172.16.6.24:9092/test-events?' --changefeed-id="kafka-task-3"

Versions of the cluster

Upstream TiDB cluster version (execute SELECT tidb_version(); in a MySQL client):

v5.2.1

TiCDC version (execute cdc version):

Release Version: v5.2.1-20211014
Git Commit Hash: f1dd56ab5861fc52ab30d8af7a44037ba58277eb
Git Branch: heads/refs/tags/v5.2.1-20211014
UTC Build Time: 2021-10-14 13:51:49
Go Version: go version go1.16.4 linux/amd64
Failpoint Build: false```