shibd opened a new pull request, #22860:
URL: https://github.com/apache/pulsar/pull/22860
### Motivation
We observe that a `normal topic` might reference a `closed ledger` and it
never auto recover. will cause the producer and customer stuck.
The root cause is related to `topic create timeout`. Assuming we have two
concurrent requests to create a topic: `firstCreate(Thread-1)`,
`secondCreate(Thread-2)`
| Thread-1 | Thread-2
|
|----------------|-------------------------------------------------|
| firstCreate topic timeout |
|
| | [remove this old
topic and recreate a new
topic](https://github.com/shibd/pulsar/blob/f07b3a030179c38f9786b3e26c82aa13e00b34a6/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/BrokerService.java#L1009-L1012)
|
| | Open ledger from
cache, and get an old ledger that create by firstCreate topic
|
| call [topic.close
](https://github.com/apache/pulsar/blob/31bfded7d717afd3e76de4d839bdb3daebf704a0/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/BrokerService.java#L1749-L1755)
|
|
| old ledger close and remove it from cache |
|
| | but this `old
ledger` being referenced to `new topic` and that stats is close |
- When the `firstCreate` topic timeout, will call `topic.close`. it will
close the ledger, and remove it from the ledger cache.
https://github.com/apache/pulsar/blob/f07b3a030179c38f9786b3e26c82aa13e00b34a6/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/BrokerService.java#L1745-L1752
- If the `secondCreate` request successfully creates a topic before the `old
ledger closes`, the reference will be made to the `old ledger`.
### Modifications
Refactor `BrokerService#getTopic()` method:
- If any exceptions occur during the creation topics process, they should
be proactively and asynchronously removed from the topics:
`pulsar.getExecutor().execute(() -> topics.remove(topicName.toString()));`
- The new get topic operation should not remove the `topicFuture` that
created by previous get topic operation. If the previous topicFuture is not
removed from the map yet, the broker should always use the existing topicFuture
(waiting for completion or return an error to the client side directly)
- Add documentation to clearly define the method boundaries
- During the process of creating a topic, all the remove methods should
`not include topicFuture` because the actual future object placed in the map
might not be the same as the `topicFuture`. You can check this
[code](https://github.com/apache/pulsar/blob/21596227415968dd9b9219779657ff74decfa45b/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/BrokerService.java#L1042-L1073)
to validation it.
### Verifying this change
- Add testCloseLedgerThatTopicAfterCreateTimeout to cover this case.
### Does this pull request potentially affect one of the following parts:
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- [ ] Dependencies (add or upgrade a dependency)
- [ ] The public API
- [ ] The schema
- [ ] The default values of configurations
- [ ] The threading model
- [ ] The binary protocol
- [ ] The REST endpoints
- [ ] The admin CLI options
- [ ] The metrics
- [ ] Anything that affects deployment
### Documentation
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- [ ] `doc` <!-- Your PR contains doc changes. -->
- [ ] `doc-required` <!-- Your PR changes impact docs and you will update
later -->
- [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: https://github.com/shibd/pulsar/pull/37
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