[Bug] consumer will continue to reconnect the Dubbo 3.2.0 offline provider

[chensanpi]

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Apache Dubbo Component

Java SDK (apache/dubbo)

Descriptions

Environment

• Dubbo version:3.2.0
• Operating System version: CentOS
• Java version: 17

项目使用的Dubbo3.2.0 ，nacos使用的2.0.4，目前应用已经接入无损下线模式，可以确定的是重连之前下线的provider已经从注册中心下掉了。但最近应用发版时经常会遇到[DUBBO] Fail to connect toHeaderExchangeClient错误，详细报错信息如下：
className:org.apache.dubbo.remoting.transport.netty4.NettyClient
content:[DUBBO] Failed to connect to provider server by other reason., dubbo version: 3.2.0, current host: 172.17.0.2, error code: 6-1. This may be caused by network disconnected, go to https://dubbo.apache.org/faq/6/1 to find instructions.
io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: /172.29.79.248:28004
Caused by: java.net.ConnectException: Connection refused
at sun.nio.ch.Net.pollConnect(Native Method) ~[?:?]
at sun.nio.ch.Net.pollConnectNow(Net.java:672) ~[?:?]
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:946) ~[?:?]
at io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:337) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:334) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:776) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:724) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:650) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.100.Final.jar!/:4.1.100.Final]

className:org.apache.dubbo.remoting.exchange.support.header.ReconnectTimerTask
content:[DUBBO] Fail to connect toHeaderExchangeClient [channel=org.apache.dubbo.remoting.transport.netty4.NettyClient [/172.17.0.2:60946 -> /172.29.79.248:28004]], dubbo version: 3.2.0, current host: 172.17.0.2, error code: 6-16. This may be caused by , go to https://dubbo.apache.org/faq/6/16 to find instructions.
org.apache.dubbo.remoting.RemotingException: client(url: dubbo://172.29.79.248:28004/com.xxx.SmartOrderFacade?anyhost=true&application=xxx&background=false&check=false&codec=dubbo&deprecated=false&dubbo=2.0.2&dubbo.endpoints=[{"port":28004,"protocol":"dubbo"}]&dubbo.metadata-service.url-params={"prefer.serialization":"fastjson2,hessian2","version":"1.0.0","dubbo":"2.0.2","release":"3.2.0","side":"provider","port":"28004","protocol":"dubbo"}&dubbo.metadata.revision=0cb72cfbead0343b0571e40f6eba849a&dubbo.metadata.storage-type=local&dynamic=true&executor-management-mode=isolation&file-cache=true&generic=false&heartbeat=60000&interface=com.xxx.SmartOrderFacade&methods=querySmartOrderListByDate&pid=31&prefer.serialization=fastjson2,hessian2&qos.enable=true&register-mode=instance&register.ip=172.16.85.16&release=3.2.0&revision=1.0.0&service-name-mapping=true&side=consumer&sticky=false&timeout=3000&timestamp=1764759449650&unloadClusterRelated=false&version=1.0.0) failed to connect to server /172.29.79.248:28004, error message is:Connection refused: /172.29.79.248:28004
at org.apache.dubbo.remoting.transport.netty4.NettyClient.doConnect(NettyClient.java:226) ~[dubbo-3.2.0.jar!/:3.2.0]
at org.apache.dubbo.remoting.transport.netty4.NettyClient.doConnect(NettyClient.java:173) ~[dubbo-3.2.0.jar!/:3.2.0]
at org.apache.dubbo.remoting.transport.AbstractClient.connect(AbstractClient.java:219) ~[dubbo-3.2.0.jar!/:3.2.0]
at org.apache.dubbo.remoting.transport.AbstractClient.reconnect(AbstractClient.java:273) ~[dubbo-3.2.0.jar!/:3.2.0]
at org.apache.dubbo.remoting.exchange.support.header.HeaderExchangeClient.reconnect(HeaderExchangeClient.java:183) ~[dubbo-3.2.0.jar!/:3.2.0]
at org.apache.dubbo.remoting.exchange.support.header.ReconnectTimerTask.doTask(ReconnectTimerTask.java:53) ~[dubbo-3.2.0.jar!/:3.2.0]
at org.apache.dubbo.remoting.exchange.support.header.AbstractTimerTask.run(AbstractTimerTask.java:94) ~[dubbo-3.2.0.jar!/:3.2.0]
at org.apache.dubbo.common.timer.HashedWheelTimer$HashedWheelTimeout.expire(HashedWheelTimer.java:653) ~[dubbo-3.2.0.jar!/:3.2.0]
at org.apache.dubbo.common.timer.HashedWheelTimer$HashedWheelBucket.expireTimeouts(HashedWheelTimer.java:732) ~[dubbo-3.2.0.jar!/:3.2.0]
at org.apache.dubbo.common.timer.HashedWheelTimer$Worker.run(HashedWheelTimer.java:454) ~[dubbo-3.2.0.jar!/:3.2.0]
at java.lang.Thread.run(Thread.java:842) ~[?:?]
Caused by: io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: /172.29.79.248:28004
Caused by: java.net.ConnectException: Connection refused
at sun.nio.ch.Net.pollConnect(Native Method) ~[?:?]
at sun.nio.ch.Net.pollConnectNow(Net.java:672) ~[?:?]
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:946) ~[?:?]
at io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:337) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:334) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:776) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:724) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:650) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[netty-transport-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.100.Final.jar!/:4.1.100.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.100.Final.jar!/:4.1.100.Final]
... 1 more
收起
env:prod
eventLevel:ERROR
eventTime:2025-12-22 16:44:53.800
threadName:dubbo-client-heartbeat-reconnect-thread-1
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.100.Final.jar!/:4.1.100.Final]
at java.lang.Thread.run(Thread.java:842) ~[?:?]

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[chensanpi]

2025-12-22 16:43:43服务下线，相关日志：

2025-12-22 16:44:53.800还在重连，相关日志：

2025-12-22 16:45:48.933重新注册完成，相关日志：

[zrlw]

both dubbo 3.2 * and nacos 2.0.* are outdated, try latest dubbo 3.3 and latest nacos 2.x

[Rafiaminhaj]

Hi, I am interested in working on this issue.
I am exploring the Dubbo codebase and would like to investigate this bug.
Please let me know if I can take this up.

[EarthChen]

It seems that this issue no longer exists in the latest version, so you can try using the latest version.

[Rafiaminhaj]

Hi maintainers, thanks for assigning this issue to me.
I am currently going through the issue details and the related code.
I will share my findings or questions shortly. Please let me know if there is any specific area I should focus on.