Why does the resolved ts buffer get closed, and what triggers its closure?

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This topic has been translated from a Chinese forum by GPT and might contain errors.

Original topic: resolved ts buffer is closed为什么会关闭，是触发什么导致的关闭

| username: wluckdog

[TiDB Usage Environment] Production Environment / Testing / Poc
[TiDB Version] v6.1.0
[Reproduction Path]
tiup cdc cli changefeed create --pd=http://xx.xx.xx.xx:2379 --sink-uri=“kafka://xx.xx.xx.xx:65502,xx.xx.xx.xx:65502,xx.xx.xx.xx:65502/center_dispatch?kafka-version=3.1.0&max-message-bytes=60485760&replication-factor=2&partition-num=1&max-batch-size=128” --changefeed-id=“center-dispatch-1” --config /home/tidb/cdc-conf/center_dispatch.toml --sort-engine=“unified”
When creating a cdc task, the following warning appears:
[WARN] [mq.go:206] [“resolved ts buffer is closed”] [namespace=] [changefeed=] [role=cdc-client]
[Resource Configuration]
[Attachment: Screenshot/Log/Monitoring]

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| username: Lucien-卢西恩 | Original post link

This is a warning message, which might actually indicate a delay in sending requests to Kafka. You can check the monitoring of Slow poll duration percentile to see if there is any delay in the slow-table type.

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| username: wluckdog | Original post link

What is the monitoring path for Slow poll duration percentile? I couldn’t find it. TiDB cluster version v6.1.0.

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| username: asddongmen | Original post link

When creating a changefeed, CDC will establish a real connection to the downstream Kafka to verify whether the provided sink-uri can successfully connect to the downstream, and then close the connection. This log may appear when closing the connection used for verification.
If the changefeed is successfully created and synchronizing normally, this warning can be ignored.
If the changefeed is not synchronizing normally, please provide more logs or monitoring screenshots for further troubleshooting.

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| username: wluckdog | Original post link

Normal synchronization, but there is an alert.

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| username: asddongmen | Original post link

Reason: When creating a changefeed, CDC will establish a real connection to the downstream Kafka to verify whether the provided sink-uri can successfully connect to the downstream, and then close the connection. This log appears when closing the verification connection. Therefore, you don’t need to worry about it.