A scenario that TiCDC could have more than one owner

[amyangfei]

What did you do?

1. Create two ticdc servers
2. Delete the owner key of the ticdc owner in etcd. /tidb/cdc/owner/<lease-id>
3. Observe another ticdc server will become owner, and the old owner is still running.

What did you expect to see?

The old owner could detect this behavior.

What did you see instead?

Two owner exist.

NOTE: this is an unexpected user operation, if we don't think it is a bug, we must forbid it.

Versions of the cluster

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

(paste TiDB cluster version here)

TiCDC version (execute cdc version):

master@aa6f3c6e5ccf1dd5578de35a4a946712e9ef4ef9

[lance6716]

why the old owner can't know the leadership has been changed through watch?

[asddongmen]

I will do a investigation on this issue.

[asddongmen]

This issue is fixed in >= v6.3.0, and we do not cherrypick it to the older version since we consider it's an malicious behavior and we should have no guarantee in such scenario.