apache / apache/rocketmq

RocketMQ Netty NioSocketChannel stuck on read fd 0

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Description

### Before Creating the Bug Report

- [x] I found a bug, not just asking a question, which should be created in [GitHub Discussions](https://github.com/apache/rocketmq/discussions).

- [x] I have searched the [GitHub Issues](https://github.com/apache/rocketmq/issues) and [GitHub Discussions](https://github.com/apache/rocketmq/discussions) of this repository and believe that this is not a duplicate.

- [x] I have confirmed that this bug belongs to the current repository, not other repositories of RocketMQ.

### Runtime platform environment

Both CentOS and OpenEuler met

### RocketMQ version

RocketMQ 4.9.x

### JDK Version

OpenJDK 17.0.2, we use ZGC.

### Describe the Bug

We met a extremely strange problem in rocketmq, a netty workerGroup thread hung on sun.nio.ch.SocketDispatcher.read0(workerGroup thread we set 3), then this server's 1/3 another tcp events can't be processed. See details in https://github.com/netty/netty/issues/15746, I wonder if anyone met this.

Image

Then we rollback our production cluster to rocketmq 4.8 & jdk 8, problem is not reproduced.

Environment: rocketmq 4.9.4 on jdk 17.0.2

### Steps to Reproduce

we dont't know how to reproduce

### What Did You Expect to See?

-

### What Did You See Instead?

-

### Additional Context

_No response_

Contributor guide

Open the contributing guide

Research direction

Start with the reported RocketMQ 4.9.4, OpenJDK 17.0.2, ZGC environment and compare it with RocketMQ 4.8 on JDK 8. Read the linked Netty issue and investigate the workerGroup hang at sun.nio.ch.SocketDispatcher.read0; the issue currently provides no reproduction steps, so done means isolating a reproducible cause and validating a fix.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
backend, networking
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Active
Clarity
Needs clarification
Newbie friendliness
35/100

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