Hi, bumping ktor client from 3.4.2 to 3.4.3 causes...

# ktor

[Oğuzhan Soykan]

Hi, bumping ktor client from 3.4.2 to 3.4.3 causes:

Error: java.io.IOException: unexpected end of stream on <http://localhost:36389/>...
      │    java.io.IOException: unexpected end of stream on <http://localhost:36389/>...
      │    at _COROUTINE._BOUNDARY._(CoroutineDebugging.kt:42)
      │    at io.ktor.client.engine.okhttp.OkHttpEngine.executeHttpRequest(OkHttpEngine.kt:107)

3.4.2 works fine.
The renovate pr and run: https://github.com/Trendyol/stove/actions/runs/25662659272/job/75327028874?pr=1167

Is there any breaking change that I might be missing?

[Aleksei Tirman [JB]]

As I can see, there were no changes to the OkHttp engine between those versions. Does the test fail on each run?

[Oğuzhan Soykan]

It fails yes, not a flaky one. Locally reproducible too

[Aleksei Tirman [JB]]

Does the test use a local Ktor server?

[Oğuzhan Soykan]

yes

fun run(
  args: Array<String>,
  shouldWait: Boolean = false,
  applicationOverrides: () -> Module = { module { } }
): Application {
  val config = loadConfiguration<AppConfiguration>(args)

  val applicationEngine = embeddedServer(Netty, port = config.port, host = "localhost") {
    mainModule(config, applicationOverrides)
  }

  applicationEngine.monitor.subscribe(ApplicationStarted) {
    it.get<ExampleAppConsumer<String, Any>>().start()
  }

  applicationEngine.monitor.subscribe(ApplicationStopping) {
    it.get<ExampleAppConsumer<String, Any>>().stop()
  }

  applicationEngine.start(wait = shouldWait)
  return applicationEngine.application
}

[Oğuzhan Soykan]

this project: https://github.com/Trendyol/stove/tree/main/examples/ktor-example

[Aleksei Tirman [JB]]

The exception might be caused by the fix for KTOR-9343. Can you please try using another server engine to pinpoint the problem?

[Oğuzhan Soykan]

for example CIO?

[Aleksei Tirman [JB]]

Yes

[Oğuzhan Soykan]

I tried with CIO, locally it passes! Now let’s see what CI thinks. Thanks for the advise

[Aleksei Tirman [JB]]

Can you please share the steps to reproduce the exception with your project?

[Bruce Hamilton]

I've figured out the issue that triggers the connection drops here - running the grpc server on the same JVM as Ktor 3.4.3 with Netty will cause the netty engine to drop all connections. This seems to be the same issue that's causing the problems with the upgrade from Netty 4.2.9 -> 4.2.12 in Ktor.

[Bruce Hamilton]

Looks like it's still an issue in 4.2.13 so we'll need to downgrade back to 4.2.9 in Ktor 3.5.0

[Oğuzhan Soykan]

What if someone forces transitive netty to 4.2.13, it might still appear in a hidden way

[Bruce Hamilton]

Yeah, there's a classpath conflict of some sort between Netty > 4.2.9 and Netty 4.1.+ that's referenced from grpc-netty

[Bruce Hamilton]

Looks like it's specifically netty-codec that causes the issue, because Ktor depends on netty-codec-base so it loads conflicting classes from either jar. A workaround would be:

testImplementation("io.grpc:grpc-netty:1.74.0") {
    exclude(group = "io.netty", module = "netty-codec")
  }

[Bruce Hamilton]

Anyway, we should be releasing 3.5.0 this week so I'd recommend just skipping 3.4.3.

[Oğuzhan Soykan]

I was able to bump it with CIO, but as soon as it is released I will bump it to 3.5.0 and release Stove with it, for now it is only in SNASPHOT

[Oğuzhan Soykan]

Thanks for the investigation!

[Bruce Hamilton]

Yeah CIO works, though swapping out the engine could have other hidden implications for consumers. Waiting for 3.5.0 is a good call 👍

[Bruce Hamilton]

I've got a fix with the latest version of Netty too just by depending directly on the codec lib

[Oğuzhan Soykan]

though swapping out the engine could have other hidden implications for consumers.

Exactly 👍

I’ve got a fix with the latest version of Netty too just by depending directly on the codec lib

Is it going to land with 3.5.0 or is it the exclusion above?

[Bruce Hamilton]

Yeah, I'll release the fix in 3.5.0

[Oğuzhan Soykan]

Perfect!