[FIXED] Different netty versions from the same gatling depency

Issue

I've been running the gatling performance tests and have noticed that one of our APIs is throwing the following error at the HttpProtocolBuilder stage:

Exception in thread "main" java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.CommandLineWrapper.main(CommandLineWrapper.java:64)
Caused by: java.lang.NoSuchFieldError: DNT
    at io.gatling.http.HeaderNames$.<clinit>(Headers.scala:44)
    at io.gatling.http.HttpDsl.$init$(HttpDsl.scala:52)
    at io.gatling.http.Predef$.<clinit>(Predef.scala:19)

I suspect this is due to a mismatch in dependency versions and sure enough I noticed that the working APIs are using this netty version

[INFO] |  |  +- io.gatling:gatling-http:jar:3.7.6:test
[INFO] |  |  |  \- io.gatling:gatling-http-client:jar:3.7.6:test
[INFO] |  |  |     +- io.netty:netty-handler-proxy:jar:4.1.65.Final:test
[INFO] |  |  |     |  \- io.netty:netty-codec-socks:jar:4.1.65.Final:test
[INFO] |  |  |     +- io.netty:netty-resolver-dns:jar:4.1.65.Final:test
[INFO] |  |  |     |  \- io.netty:netty-codec-dns:jar:4.1.65.Final:test
[INFO] |  |  |     +- io.netty:netty-codec-http2:jar:4.1.65.Final:test
[INFO] |  |  |     +- io.netty:netty-tcnative-boringssl-static:jar:2.0.39.Final:test

Whereas the failing one is using

[INFO] |  |  +- io.gatling:gatling-http:jar:3.7.6:test
[INFO] |  |  |  \- io.gatling:gatling-http-client:jar:3.7.6:test
[INFO] |  |  |     +- io.netty:netty-handler-proxy:jar:4.1.31.Final:test
[INFO] |  |  |     |  \- io.netty:netty-codec-socks:jar:4.1.31.Final:test
[INFO] |  |  |     +- io.netty:netty-resolver-dns:jar:4.1.31.Final:test
[INFO] |  |  |     |  \- io.netty:netty-codec-dns:jar:4.1.31.Final:test
[INFO] |  |  |     +- io.netty:netty-codec-http2:jar:4.1.31.Final:test
[INFO] |  |  |     +- io.netty:netty-tcnative-boringssl-static:jar:2.0.20.Final:test

Does anyone know why the APIs might be using different netty versions when they come from the exact same gatling library? And how to potentially fix it?

Can't share much more information due to it being a work project.

Cheers, Kris

Solution

Does anyone know why the APIs might be using different netty versions when they come from the exact same gatling library?

No idea what you mean here.

My2cents: Gatling is not the only library in your project pulling netty. Some other library, or some dependencyManagement block, force a downgrade to a very old version (4.1.31 was released 4 years ago).

Don't downgrade, upgrade instead. If you have a library that pulls a dependency from 4 years ago, there's a very good chance it's super old too.

Answered By - Stéphane LANDELLE
Answer Checked By - Willingham (JavaFixing Volunteer)