Elasticsearch `availableProcessors is already set` error when using Testcontainers netty transport

So far I’ve only seen this affect our internal tests. On one of my machines I consistently get this failure:

Gradle Test Executor 5 > org.testcontainers.elasticsearch.ElasticsearchContainerTest > transportClientClusterHealth FAILED
    java.lang.IllegalStateException: availableProcessors is already set to [4], rejecting [4]
        at io.netty.util.NettyRuntime$AvailableProcessorsHolder.setAvailableProcessors(NettyRuntime.java:51)
        at io.netty.util.NettyRuntime.setAvailableProcessors(NettyRuntime.java:87)
        at org.elasticsearch.transport.netty4.Netty4Utils.setAvailableProcessors(Netty4Utils.java:83)
        at org.elasticsearch.transport.netty4.Netty4Transport.<init>(Netty4Transport.java:112)
        at org.elasticsearch.transport.Netty4Plugin.lambda$getTransports$0(Netty4Plugin.java:86)
        at org.elasticsearch.client.transport.TransportClient.buildTemplate(TransportClient.java:189)
        at org.elasticsearch.client.transport.TransportClient.<init>(TransportClient.java:283)
        at org.elasticsearch.transport.client.PreBuiltTransportClient.<init>(PreBuiltTransportClient.java:128)
        at org.elasticsearch.transport.client.PreBuiltTransportClient.<init>(PreBuiltTransportClient.java:114)
        at org.elasticsearch.transport.client.PreBuiltTransportClient.<init>(PreBuiltTransportClient.java:104)
        at org.testcontainers.elasticsearch.ElasticsearchContainerTest.transportClientClusterHealth(ElasticsearchContainerTest.java:103)

I believe this is an instance of a known Elasticsearch client issue (https://github.com/elastic/elasticsearch/issues/25741). This will be arising because both Elasticsearch and docker-java can use netty.

It is heavily mitigated by okhttp being our default transport now, but this bug does mean that we can’t test the netty transport any more.

We should probably either:

• Wait for https://github.com/elastic/elasticsearch/issues/25741 to be resolved more elegantly (I agree with https://github.com/elastic/elasticsearch/issues/25741#issuecomment-430063966, but I’m not sure if it will be resolved that way)
• Modify our tests to set the workaround system property
• Modify the ElasticsearchContainer class to automatically set the workaround system property

@dadoonet you might have a better understanding of this - do you have any suggestions?

[rfelgent]

You have my respect that you have taken the effort to remove completely the dependency of Netty transport!

Thank you people!

[bsideup]

Since 1.11.0, we no longer include Netty transport and fully migrated to OkHttp. I’m closing this issue as not relevant anymore 😃