poorbarcode opened a new pull request, #23802:
URL: https://github.com/apache/pulsar/pull/23802
### Motivation
**Background**
- After all, consumers are off-line, the cursor will be triggered a `rewind`
- If there is a pending read is in-progress, the action `rewind` will be
delayed after the pending read is complete.
- The variable `dispatcher.recentlyJoinedConsumers` of `key_shared` mode
guarantees delivery in order, it records the `cursor.readPosition` when
consumers join.
**Issue**: a case that makes items in `dispatcher.recentlyJoinedConsumers`
out-of-order, the steps to reproduce the issue are as follows:
- there are `3` consumers: `c1`, `c2`, `c3`
- `c1` and `c2` consumed all messages that they received.
- `c3` is stuck
- `LAC`: `3:299`, `cursor.readPosition`: `3:300`, `mard-deleted-position`:
`3:100`
- The dispatcher will replay the messages that were sent to `c3` after `c3`
is removed.
- At the moment, `c1` and `c2` are also off-line, which will trigger a
`rewind`
- Since there is a pending read, the `rewind` will be delayed.
- `consumer-4` joined, its `recentlyJoinedPosition` was set to `3:300`
- The delayed `rewind` was triggered.
- `LAC`: `3:299`, `cursor.readPosition`: `3:101`,
`mard-deleted-position`: `3:100`
- `consumer-5` joined, its `recentlyJoinedPosition` was set to `3:101`
- The issue occured.
### Modifications
- After the delayed `rewind` was executed, clear the collection
`dispatcher.recentlyJoinedConsumers`
### Documentation
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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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