mattisonchao opened a new pull request, #19374:
URL: https://github.com/apache/pulsar/pull/19374
Fixes #19083
Fixes #11866
### Motivation
Currently, the delete namespace operation has the following steps:
1. Do pre-check
2. Get full of topics
3. Mark the namespace as `deleted` to avoid creating the topic again by
client lookup or reconnect.
4. Delete all of the user-created topics
5. Delete all system topics.
6. Delete namespace event topics.
7. clean up namespace metadata and resources
A race condition will make step 2 unable to get full of topics. e.g:
| - | Thread A
| Thread B
|
|--------|------------------------------------------------------------------------------------------|-------------------------------------------------------------|
| time 1 | Got full of topics
| Trying to create a new topic and passed the `deleted`
check |
| time 2 | Mark `deleted`
| Do other checks
|
| time 3 | Do the rest of steps 4,5,6
| Created managed ledger and has persistent info to
metadata |
| time 4 | Step 7, Got exception `Directory not empty for
/managed-ledgers/test-tenant/test-ns2/persistent` | Do the rest work
|
| time 5 | Return the exception
| Topic created
|
This problem also exists for user-created topics, but I don't think we need
to deal with them. The user can run the command multiple times and it will
clean up successfully. Otherwise, we need to use a heavily distributed lock to
ensure that.
However, we need to do something about the internal `change_event` topic. we
can always assume the existence of a `change_event` topic to avoid race
conditions where the topic passes the check but is not yet persisted in the
metadata.
I've tested in my local env 1k times. It works great for me.
<img width="657" alt="image"
src="https://user-images.githubusercontent.com/74767115/215781535-c993e7f3-aa8d-406e-b720-0aa97f72dfab.png";>
### Modifications
> Deleting topic xxxx because local cluster is not part of global namespace
repl list
- Remove `namespacePolicies.deleted` logic to ensure the new topic will not
be deleted by `PersistenTopic#checkReplication`.
- Always assume the existence of an event topic to avoid race conditions
where the topic passes the check but is not yet persisted in the metadata.
- Add a test case to test if the subject name object is left behind.
### Verifying this change
- [x] Make sure that the change passes the CI checks.
### Documentation
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- [x] `doc-not-needed` <!-- Your PR changes do not impact docs -->
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