apache/dubbo

[Bug] issues 15271 Refactoring the bug in the registry center

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#16186 opened on Mar 30, 2026

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help wanted

Description

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Apache Dubbo Component

Java SDK (apache/dubbo)

Dubbo Version

dubbo 3.3 branch. jdk 11

Steps to reproduce this issue

Configure multiple ZooKeeper registries, with one service not started and configured as check=false

What you expected to happen

There is an issue with this approach. When multiple ZooKeeper registries are configured and one of them has check=false, the logic in org.apache.dubbo.remoting.zookeeper.curator5.Curator5ZookeeperClient#Curator5ZookeeperClient was changed from the original behavior of closing the connection when !connected to closing it only when check && !connected. As a result, the subsequent workflow incorrectly assumes that the connection has been successfully established and continues writing node data to that connection.

A typical example is node creation in org.apache.dubbo.remoting.zookeeper.curator5.AbstractZookeeperClient#create. Each recursive attempt to create the node fails, which prolongs the application startup time. Eventually, an exception is thrown in org.apache.dubbo.remoting.zookeeper.curator5.Curator5ZookeeperClient#createPersistent(java.lang.String, boolean), causing the application startup to fail.

Anything else

I want to solve this issue, I'm willing to submit a PR. Could you provide me with some ideas on how to approach this problem? My approach is to add a registry != null check to all methods in org.apache.dubbo.registry.ListenerRegistryWrapper, while also passing in the original URL object. When org.apache.dubbo.registry.ListenerRegistryWrapper#getUrl is invoked, if registry == null, it should return the original URL directly. In this way, when the following code is executed in org.apache.dubbo.registry.integration.RegistryDirectory#subscribe: registry.getUrl() .getParameter( RegistryConstants.REGISTRY_CLUSTER_KEY, registry.getUrl().getParameter(PROTOCOL_KEY)); it will no longer trigger a NullPointerException.

Do you have a (mini) reproduction demo?

  • Yes, I have a minimal reproduction demo to help resolve this issue more effectively!

Are you willing to submit a pull request to fix on your own?

  • Yes I am willing to submit a pull request on my own!

Code of Conduct

Contributor guide

Tech stack
java
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaApache DubboZooKeeper
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
The bug occurs when multiple ZooKeeper registries are configured with check=false. The fix proposed by the reporter involves modifying methods in ListenerRegistryWrapper to handle null registry gracefully. Key files to examine: org.apache.dubbo.remoting.zookeeper.curator5.Curator5ZookeeperClient, org.apache.dubbo.registry.ListenerRegistryWrapper, and org.apache.dubbo.registry.integration.RegistryDirectory. Investigate the Curator5ZookeeperClient constructor logic and the create method's retry behavior. Consider adding null checks in ListenerRegistryWrapper as suggested. No PR is linked yet, so this issue is available for contribution.