kafka-producer-network-thread hangs while fetching metadata.

[nikhita kataria <ni...@gmail.com>]

Hi Team,

I am debugging why my application would not stop. I saw
kafka-producer-network-thread was hung forever trying to get
metadata update and the following trace was produced a couple of thousands
of times (literally every second). I am wondering if there is a
configuration I can use to set an upper limit?

I am already using max.block.ms = 60 s, request.timeout.ms  = 20s and
retries as 20.

```
java.io.IOException: Can't resolve address: mycoolhost:mycoolport
        at
org.apache.kafka.common.network.Selector.doConnect(Selector.java:235)
~[kafka-clients-2.0.0.24.jar:?]
        at
org.apache.kafka.common.network.Selector.connect(Selector.java:214)
~[kafka-clients-2.0.0.24.jar:?]
        at
org.apache.kafka.clients.NetworkClient.initiateConnect(NetworkClient.java:877)
[kafka-clients-2.0.0.24.jar:?]
        at
org.apache.kafka.clients.NetworkClient.access$800(NetworkClient.java:64)
[kafka-clients-2.0.0.24.jar:?]
        at
org.apache.kafka.clients.NetworkClient$DefaultMetadataUpdater.maybeUpdate(NetworkClient.java:1053)
[kafka-clients-2.0.0.24.jar:?]
        at
org.apache.kafka.clients.NetworkClient$DefaultMetadataUpdater.maybeUpdate(NetworkClient.java:938)
[kafka-clients-2.0.0.24.jar:?]
        at
org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:514)
[kafka-clients-2.0.0.24.jar:?]
        at
org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:313)
[kafka-clients-2.0.0.24.jar:?]
        at
org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:237)
[kafka-clients-2.0.0.24.jar:?]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_172]
Caused by: java.nio.channels.UnresolvedAddressException
        at sun.nio.ch.Net.checkAddress(Net.java:101) ~[?:1.8.0_172]
        at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:622)
~[?:1.8.0_172]
        at
org.apache.kafka.common.network.Selector.doConnect(Selector.java:233)
~[kafka-clients-2.0.0.24.jar:?]
        ... 9 more
```

Nikhita Kataria..

Re: kafka-producer-network-thread hangs while fetching metadata.

[lobo xu <we...@gmail.com>]

Hi nikhita
   It looks like there is a problem with the connection address "mycoolhost:mycoolport". The address resolves properly to IP and port。
> 在 2021年4月15日，08:51，nikhita kataria <ni...@gmail.com> 写道：
> 
> ava.io.IOException: Can't resolve address: mycoolhost:mycoolport
>        at