SennoYuki

> Thanks for the PR. Please add a test case reproducing your change. Can you also please explain the change a bit? Do I need create a issue for the...

> Just amend the test case to this PR. See tests/Issues dir for reference I have added the unit test file. Do I need do anything eles?

> Just amend the test case to this PR. See tests/Issues dir for reference Look at this please. Thanks

And I had already used config `delayedDeliveryTrackerFactoryClassName=org.apache.pulsar.broker.delayed.BucketDelayedDeliveryTrackerFactory`

> I need more context: > > 1. What's your subscription type? `Exclusive`,`Failover`,`Shared` or `Key_Shared`? > 2. Did you enable `delayedDeliveryEnabled` ? 1. Shared 2. enable

And I discover my subscription cursor may not be durable. But I confirm I used durable subscription from consumer config and pulsar-admin topic stats 

> I need more context: > > 1. What's your subscription type? `Exclusive`,`Failover`,`Shared` or `Key_Shared`? > 2. Did you enable `delayedDeliveryEnabled` ? If possible, maybe we can check this problem...

> I don't reproduce the issue, and I'll keep trying > > For determine if a subscription is durable, try run `./pulsar-admin topics stats persistent://public/default/my-topic1`, and see the `isDurable` field...

> If `isDurable` is true, it means your cursor is durable So I can't fix the situation. I can't restart the broker to tuning config because of duplicated consume happening...

@dao-jun @coderzc Any update? Today I reproduce the problem with topic unload operation. Can you check the unload code?