poorbarcode opened a new pull request, #23163:
URL: https://github.com/apache/pulsar/pull/23163
### Motivation
After a consumer calls `seek`, the operation `reconnect` will get a fenced
error, which leads to more unnecessary reconnects. The steps to produce are as
follows:
- `client-side`: consumer connected
- `client-side`: calls `consumer.seek` or `seekAsync`
- `broker-side`: mark subscription as `fenced`
- remove all consumer
- do reset the cursor internally
-`client-side`: consumer tries to reconnect
- get an error Subscription was fenced due to the task `reset cursor` not
finished yet.
- `broker-side`: `reset cursor` is completed
- `client-side`: The consumer tries to reconnect, and it will finish at this
time.
### Modifications
- This PR fixes the issue that a consumer fenced itself.
- This PR can probably fix the issue that a `consumer.seek` fenced other
consumers under the same subscription.
- This PR does not fix all scenarios in which a `consumer.seek` fenced
other consumers under the same subscription. See the following example:
| time | `broker-side: consumer_1` | `broker-side: consumer_2` |
| --- | --- | --- |
| 1 | | check whether an in-progress reset cursor exists: `false` |
| 2 | | start to add `consumer_2` |
| 3 | `reset cursor` started |
| 4 | mark subscription as `fenced` |
| 5 | | get a fenced error |
I do not want to improve the behavior above because it needs a lock. Since
it does not cause critical errors, it just causes reconnection and the
possibility of it occurring is low, we can leave it there.
### Documentation
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- [ ] `doc-required` <!-- Your PR changes impact docs and you will update
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- [x] `doc-not-needed` <!-- Your PR changes do not impact docs -->
- [ ] `doc-complete` <!-- Docs have been already added -->
### Matching PR in forked repository
PR in forked repository: x
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