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Posted to notifications@dubbo.apache.org by "Zhengcy05 (via GitHub)" <gi...@apache.org> on 2026/06/10 08:32:56 UTC
[PR] Fix unconnected Curator client handling when registry check is false [dubbo]
Zhengcy05 opened a new pull request, #16329:
URL: https://github.com/apache/dubbo/pull/16329
Fixes #16186
## What is the purpose of the change?
This PR fixes an issue in the multi-ZooKeeper registry scenario when one registry is unavailable and configured with `check=false`.
Based on the issue report, in the `dubbo 3.3` branch, if multiple ZooKeeper registries are configured and one of them is not started with `check=false`, `Curator5ZookeeperClient` may keep an unconnected Curator client alive after `blockUntilConnected(...)` returns `false`. As a result, the following registry workflow still treats that client as usable and continues trying to create nodes on it. This can cause repeated failures in node creation, significantly slow down application startup, and eventually lead to startup failure.
From the call path, the problem has two parts:
1. `Curator5ZookeeperClient` does not fail fast enough on connection failure
If `blockUntilConnected(...)` returns `false`, the ZooKeeper client has not been successfully established. This should always be treated as a client creation failure, and the underlying Curator client should be closed immediately so it cannot be reused later.
The `check=false` semantic should only control whether the upper layer continues to throw when registry creation fails. It should not change whether the low-level ZooKeeper client itself is considered successfully created.
2. `ListenerRegistryWrapper` is not null-safe when the upper layer returns a `null` registry
In `AbstractRegistryFactory#getRegistry()`, when registry creation fails and `check=false`, Dubbo logs a warning and returns `null`.
However, `RegistryFactoryWrapper` still wraps that result, and methods such as `ListenerRegistryWrapper#getUrl()` previously dereferenced the delegate directly. This could later trigger a `NullPointerException` in paths like `RegistryDirectory#subscribe()`.
To address this, this PR includes two parts:
- Fix the connection failure handling in `Curator5ZookeeperClient`
- When `blockUntilConnected(...) == false`, always close the client first and then throw an exception.
- Remove the dependency on `check` in this low-level failure path.
- Keep the client creation semantic consistent: if the connection is not established, client creation fails.
- Add null-safe handling to `ListenerRegistryWrapper`
- Add a constructor that preserves the original `URL`.
- Return the original URL from `getUrl()` when `registry == null`.
- Return `false` from `isAvailable()` when `registry == null`.
- Make `destroy()` a safe no-op when `registry == null`.
- Add null protection to `unsubscribe()`, `isServiceDiscovery()`, and `lookup()`.
- Keep the existing listener callback behavior unchanged.
With these changes:
- an unconnected ZooKeeper client will not be reused by the following registry workflow;
- the existing `check=false` behavior at the registry factory layer remains unchanged;
- a `null` registry can still be safely wrapped without introducing extra NPEs.
## Tests
This PR adds focused regression coverage for both the low-level client behavior and the upper-layer `check=false` flow:
- `Curator5ZookeeperClientTest`
- verifies that when `blockUntilConnected(...)` fails, constructing `Curator5ZookeeperClient` throws `IllegalStateException` for both `check=true` and `check=false`;
- verifies that `client.close()` is invoked on connection failure.
- `AbstractRegistryFactoryTest`
- verifies that when `createRegistry(url)` fails and `check=false`, `getRegistry(url)` returns `null`, preserving the existing upper-layer behavior.
- `ListenerRegistryWrapperTest`
- verifies that `getUrl()`, `isAvailable()`, `destroy()`, `lookup()`, `subscribe()`, and `unsubscribe()` are safe when `registry == null`;
- verifies that listener callbacks are still triggered as expected in the `null registry` case.
- `RegistryFactoryWrapperTest`
- verifies that when the underlying `RegistryFactory#getRegistry(url)` returns `null`, the wrapper still returns the original URL safely and allows subscription-related calls without throwing exceptions.
Verification command used:
```bash
mvn -pl dubbo-remoting/dubbo-remoting-zookeeper-curator5,dubbo-registry/dubbo-registry-api \
-Dtest=Curator5ZookeeperClientTest,ListenerRegistryWrapperTest,RegistryFactoryWrapperTest,AbstractRegistryFactoryTest \
-Dsurefire.failIfNoSpecifiedTests=false test -q
```
## Checklist
- [x] Make sure there is a [GitHub_issue](https://github.com/apache/dubbo/issues) field for the change.
- [x] Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
- [x] Write necessary unit-test to verify your logic correction. If the new feature or significant change is committed, please remember to add sample in [dubbo samples](https://github.com/apache/dubbo-samples) project.
- [x] Make sure gitHub actions can pass. [Why the workflow is failing and how to fix it?](../CONTRIBUTING.md)
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Re: [PR] Fix unconnected Curator client handling when registry check is false [dubbo]
Posted by "codecov-commenter (via GitHub)" <gi...@apache.org>.
codecov-commenter commented on PR #16329:
URL: https://github.com/apache/dubbo/pull/16329#issuecomment-4677089101
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:x: Patch coverage is `26.66667%` with `11 lines` in your changes missing coverage. Please review.
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>|unit-tests-java11|1|0|
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<details><summary>Additional details and impacted files</summary>
```diff
@@ Coverage Diff @@
## 3.3 #16329 +/- ##
=============================================
- Coverage 60.79% 35.30% -25.49%
+ Complexity 11777 11206 -571
=============================================
Files 1953 1952 -1
Lines 89208 89190 -18
Branches 13458 13374 -84
=============================================
- Hits 54234 31492 -22742
- Misses 29403 53164 +23761
+ Partials 5571 4534 -1037
```
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