Always get Unknown channel option 'io.netty.channel.epoll.EpollChannelOption#TCP_USER_TIMEOUT' for channel the client try to access etcd server

[kxs-nzeng]

Versions

• etcd: 3.5.14-debian-12-r4
• jetcd: 0.8.3
• java: jvm 21_

Describe the bug
When the client try to access etcd server in a docker compose with endpoint "http://etcd:2379" , always get error like
Unknown channel option 'io.netty.channel.epoll.EpollChannelOption#TCP_USER_TIMEOUT' for channel '[id: 0x8d9e6cd5]'

grpc-netty version 1.62.2
grpc-netty-shaded version 1.62.2

Based on the full log,
2024-12-13T22:37:37.874Z WARN 1773773 --- [ntloop-thread-0] io.netty.bootstrap.Bootstrap : Unknown channel option 'io.netty.channel.epoll.EpollChannelOption#TCP_USER_TIMEOUT' for channel

Now I suspect when jetcd try to access etcd server, the channel builder try to mix NioEventLoopGroup with EpollSocketChannel. I am on Linux system. Not sure how could it happen and how to resolve it

What I could do to resolve this?

My project is hung now. Very appreciate for any help here.

[ghimi-g]

at code

// io/etcd/jetcd/impl/ClientConnectionManager.java:219
    Vertx vertx() {
        if (this.vertx == null) {
            synchronized (this.lock) {
                if (this.vertx == null) {
                    this.vertx = Vertx.vertx(new VertxOptions().setUseDaemonThread(true));
                }
            }
        }

        return this.vertx;
    }

Change into this can solve problem

this.vertx = Vertx.vertx(new VertxOptions().setUseDaemonThread(true).setPreferNativeTransport(Utils.isEpollAvailable()))

Utils comes from io.grpc.netty.Utils ,at package io.grpc:grpc-netty,used for determine whether epoll(netty-transport-native-epoll) is available。 Vertex use preferNativeTransport property to decide whether use EpollEventLoopGroup. The default option is false, which cause use NioEventLoopGroup but config EpollChannelOption cause this warning.

If you don't want to see this warning, you can temporarily remove netty-transport-native-epoll package in your project.

Reference

• netty native-transports
• ClientConnectionManager

[cnz101]

@ghimi-g hello, Have you ever been in this situation？jetcd get、put、delete operaton blocked and no response. when i use jetcd below 0.7.x, it's ok. but when i upgrade to 0.7.x, this problem happened.
jetcd 0.7.7
etcd v3.5.4
jdk 1.8

[lburgazzoli]

you probably need to check your dependency tree, unfortunately a few things break if the groc and netty deps are not correct

[kxs-nzeng]

Thank you for all of your reply. Finally the issue seems to be related with the endpoint I provided. My etcd server spin up in a docker compose, therefore the endpoint should use host name return from getServiceHost from docker compose container. Not etcd. The error message is misleading. When I give the correct endpoint, everything is fine now.
Thanks again for everybody's help.

[kxs-nzeng]

For Question from CNZ101,
I use version 0.8.3.
I could really get response when using code as

public byte[] getValue(String key) throws InterruptedException, ExecutionException {
ByteSequence keyByte = ByteSequence.from(key.getBytes());
GetResponse response = kvClient.get(keyByte).get();