Duplicated item inserted into OrderedSet

[Quafadas]

I'm getting this quite repeatably in CI.

Caused by: java.lang.Exception: Duplicated item inserted into OrderedSet: mill.define.Task$TraverseCtx@f8a6243

I've found the two issues below, which suggest it may have been fixed?

#913
#2289

I seem to be able to produce locally, but only after a clean.

Then I run this command.

PS C:\temp\Scala-ILS-Lib>  mill -j 1 --no-server smithyapi.jvm.prepareOffline
Could not start a Mill server process.
This could be caused by too many already running Mill instances or by an unsupported platform.

Trying to run Mill in-process ...
Launching Mill as sub-process ...
WARNING: Using incubator modules: jdk.incubator.vector
[22/22] smithyapi.jvm.prepareOffline 
An unexpected error occurred
Exception in thread "main" java.lang.Exception: Duplicated item inserted into OrderedSet: mill.define.Task$TraverseCtx@201aa8c1

The bottom of the stack seems to point here

mill/main/api/src/mill/api/AggWrapper.scala

Line 99 in e57652b

throw new Exception("Duplicated item inserted into OrderedSet: " + v)

But I guess the "real" problem is subtle and elsewhere. I'm wondering if there Is there a "known" solution? Mill 0.11.6

edit - as requested, full stack.

An unexpected error occurred
Exception in thread "main" java.lang.Exception: Duplicated item inserted into OrderedSet: mill.define.Task$TraverseCtx@2b46a8c1
        at mill.api.AggWrapper$Agg$Mutable.append(AggWrapper.scala:99)
        at mill.api.AggWrapper$Agg$Mutable$.$anonfun$from$1(AggWrapper.scala:60)
        at scala.collection.IterableOnceOps.foreach(IterableOnce.scala:576)
        at scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:574)
        at scala.collection.AbstractIterator.foreach(Iterator.scala:1300)
        at mill.api.AggWrapper$Agg$Mutable$.from(AggWrapper.scala:60)
        at mill.api.AggWrapper$Agg$.from(AggWrapper.scala:56)
        at mill.eval.EvaluatorCore.evaluate0(EvaluatorCore.scala:172)
        at mill.eval.EvaluatorCore.$anonfun$evaluate$1(EvaluatorCore.scala:43)
        at scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)
        at mill.eval.EvaluatorCore.evaluate(EvaluatorCore.scala:34)
        at mill.eval.EvaluatorCore.evaluate$(EvaluatorCore.scala:26)
        at mill.eval.EvaluatorImpl.evaluate(EvaluatorImpl.scala:15)
        at mill.main.RunScript$.evaluateNamed(RunScript.scala:38)
        at mill.main.RunScript$.$anonfun$evaluateTasksNamed$2(RunScript.scala:26)
        at scala.util.Either.map(Either.scala:382)
        at mill.main.RunScript$.evaluateTasksNamed(RunScript.scala:26)
        at mill.runner.MillBuildBootstrap$.evaluateWithWatches(MillBuildBootstrap.scala:399)
        at mill.runner.MillBuildBootstrap.$anonfun$processFinalTargets$3(MillBuildBootstrap.scala:308)
        at scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)
        at mill.runner.MillBuildBootstrap.processFinalTargets(MillBuildBootstrap.scala:308)
        at mill.runner.MillBuildBootstrap.evaluateRec(MillBuildBootstrap.scala:196)
        at mill.runner.MillBuildBootstrap.evaluate(MillBuildBootstrap.scala:48)
        at mill.runner.MillMain$.$anonfun$main0$6(MillMain.scala:234)
        at mill.runner.Watching$.watchLoop(Watching.scala:27)
        at mill.runner.MillMain$.$anonfun$main0$1(MillMain.scala:219)
        at scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)
        at scala.Console$.withErr(Console.scala:193)
        at mill.api.SystemStreams$.$anonfun$withStreams$2(SystemStreams.scala:62)
        at scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)
        at scala.Console$.withOut(Console.scala:164)
        at mill.api.SystemStreams$.$anonfun$withStreams$1(SystemStreams.scala:61)
        at scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)
        at scala.Console$.withIn(Console.scala:227)
        at mill.api.SystemStreams$.withStreams(SystemStreams.scala:60)
        at mill.runner.MillMain$.main0(MillMain.scala:101)
        at mill.runner.MillMain$.liftedTree1$1(MillMain.scala:78)
        at mill.runner.MillMain$.main(MillMain.scala:69)
        at mill.runner.MillMain.main(MillMain.scala)

[lefou]

Can you post the full stacktrace? We closed the other issues, because we thought the issue might be closed, but we never confirmed because we had no deterministic reproducer. If you have one, please share it with us.

[Quafadas]

I think I'm close to having that, although I suspect, that at least in my case it isn't easily reproducible without corporate infrastructure. Bear with me a sec.

[Quafadas]

Weirdly, I can reproduce this, on this library;
https://github.com/Quafadas/vecxt

but only, if I change the build config, to be compatible with my corporate infrastructure. i.e. add this

val repos = T.task {
  Seq(
    MavenRepository("https://packages.corp.com/artifactory/maven/"),
    coursier.LocalRepositories.ivy2Local
  )
}

// Allows mill to resolve the "meta-build"
object CustomZincWorkerModule extends ZincWorkerModule with CoursierModule {
  def repositoriesTask = repos
}

trait Common extends ScalaModule  with PublishModule {
  def scalaVersion = "3.3.1"

  def publishVersion = VcsVersion.vcsState().format()

  def repositoriesTask = repos
  def zincWorker       = ModuleRef(CustomZincWorkerModule)

}

example

At $work, on windows

PS C:\temp\vecxt> mill -j 0 vecxt.__.prepareOffline
[137/166] vecxt.js.test.resolvedRunIvyDeps | Downloading [48/48] artifacts (~0/0 bytes)
An unexpected error occurred
Exception in thread "MillServerActionRunner" java.lang.Exception: Duplicated item inserted into OrderedSet: mill.define.Task$TraverseCtx@1821e7da

Is reliably reproducible. I need to test, whether that remains the case at home (MacOS, no crazy firewalls).

An unexpected error occurred
Exception in thread "MillServerActionRunner" java.lang.Exception: Duplicated item inserted into OrderedSet: mill.define.Task$TraverseCtx@1821e7da
        at mill.api.AggWrapper$Agg$Mutable.append(AggWrapper.scala:99)
        at mill.api.AggWrapper$Agg$Mutable$.$anonfun$from$1(AggWrapper.scala:60)
        at scala.collection.IterableOnceOps.foreach(IterableOnce.scala:576)
        at scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:574)
        at scala.collection.AbstractIterator.foreach(Iterator.scala:1300)
        at mill.api.AggWrapper$Agg$Mutable$.from(AggWrapper.scala:60)
        at mill.api.AggWrapper$Agg$.from(AggWrapper.scala:56)
        at mill.eval.EvaluatorCore.evaluate0(EvaluatorCore.scala:170)
        at mill.eval.EvaluatorCore.$anonfun$evaluate$1(EvaluatorCore.scala:43)
        at scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)
        at mill.eval.EvaluatorCore.evaluate(EvaluatorCore.scala:34)
        at mill.eval.EvaluatorCore.evaluate$(EvaluatorCore.scala:26)
        at mill.eval.EvaluatorImpl.evaluate(EvaluatorImpl.scala:15)
        at mill.main.RunScript$.evaluateNamed(RunScript.scala:38)
        at mill.main.RunScript$.$anonfun$evaluateTasksNamed$2(RunScript.scala:26)
        at scala.util.Either.map(Either.scala:382)
        at mill.main.RunScript$.evaluateTasksNamed(RunScript.scala:26)
        at mill.runner.MillBuildBootstrap$.evaluateWithWatches(MillBuildBootstrap.scala:399)
        at mill.runner.MillBuildBootstrap.$anonfun$processFinalTargets$3(MillBuildBootstrap.scala:308)
        at scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)
        at mill.runner.MillBuildBootstrap.processFinalTargets(MillBuildBootstrap.scala:308)
        at mill.runner.MillBuildBootstrap.evaluateRec(MillBuildBootstrap.scala:196)
        at mill.runner.MillBuildBootstrap.evaluate(MillBuildBootstrap.scala:48)
        at mill.runner.MillMain$.$anonfun$main0$6(MillMain.scala:234)
        at mill.runner.Watching$.watchLoop(Watching.scala:27)
        at mill.runner.MillMain$.$anonfun$main0$1(MillMain.scala:219)
        at scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)
        at scala.Console$.withErr(Console.scala:193)
        at mill.api.SystemStreams$.$anonfun$withStreams$2(SystemStreams.scala:62)
        at scala.util.DynamicVariable.withValue(DynamicVariable.scala:59)

[Quafadas]

Bit of a stream of conciousness, but plot deepens running these two back to back.

PS C:\temp\vecxt> mill -j 0 vecxt.jvm.prepareOffline
[#4] [20/23] vecxt.jvm.resolvedIvyDeps | Downloading [36/36] artifacts (~0/0 bytes)
An unexpected error occurred
Exception in thread "MillServerActionRunner" java.lang.Exception: Duplicated item inserted into OrderedSet: mill.define.Task$TraverseCtx@1821e7da

But this;

PS C:\temp\vecxt> mill -j 1 vecxt.jvm.prepareOffline
[14/23] vecxt.jvm.resolvedIvyDeps | Downloading [36/36] artifacts (~0/0 bytes)
1 targets failed
vecxt.jvm.resolvedIvyDeps
Resolution failed for 3 modules:
--------------------------------------------
  org.scala-lang:scala3-library_3:3.3.1
        download error: Caught javax.net.ssl.SSLHandshakeException (PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target)

Generates a different error.

My current theory, is that in this particular incarnation, this error message, is essentially "swallowing" some other error message during artifact resolution, and the -j 0 is confusing mills error reporting.

Theory - at home, this is going to work fine.

Proposal; write a little plugin / publish a local version of mill which throws an error randomly during artifact resolution...

[Quafadas]

Hmmm, that doesn't fly, as I can also make it happen, when the second run, is successful.

[lefou]

Just from looking at the stacktrace and the location where this issue happens, it could be that we're using an Agg for results but it might not be an appropriate data structure, as there is no guarantee that two distinct tasks evaluate to distinct results.

[Quafadas]

Hmm... I'm trying to figure out how to be helpful. If I can figure out a public repo, I'll tag you on it.

[lefou]

Fixed in #2959