apache/dubbo

使用多注册中心集群会进入ZoneAwareClusterInvoker.doInvoke方法中对所有注册中心进行负载均衡，会将所有Invoke强转为MockClusterInvoker<T>类型

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#7,313 opened on Mar 3, 2021

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Description

Environment

  • Dubbo version: 2.7.6
  • Operating System version: window10
  • Java version: 1.8

Steps to reproduce this issue

使用多注册中心集群会进入ZoneAwareClusterInvoker.doInvoke方法中对所有注册中心进行负载均衡，会将所有Invoke强转为MockClusterInvoker类型，dubbo的具体解释（FIXME, the invoker is a cluster invoker representing one Registry, so it will automatically wrapped by MockClusterInvoker.） 由于自己对Cluster进行了扩展，我提供的ClusterInvoker和dubbo自身的MockClusterInvoker同为Invoker的子类，所以会有类型转换异常。 image 不使用扩展的cluster时的invoker都是MockClusterInvoker类型： image 使用扩展的cluster时的invoker都是ClusterInvoker类型： image 强转时发生解析异常： java.lang.ClassCastException: com.common.util.rpc.dubbo.invoker.ClusterInvoker cannot be cast to org.apache.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker

首先，为什么在ZoneAwareClusterInvoker类中会耦合MockClusterInvoker，其次这边把所有Invoke强转为MockClusterInvoker类型，是不是会对Cluster的扩展产生影响？ image image

Contributor guide

Research direction
Examine ZoneAwareClusterInvoker.doInvoke method to understand why it casts all invokers to MockClusterInvoker. Investigate the impact on custom ClusterInvoker extensions and identify a fix that avoids the tight coupling with MockClusterInvoker.
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.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
JavaDubbo
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55