Build Bug: org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool is not on the classpath

[He-Pin]

Even the PekkoJdk9ForkJoinPool is on the final result jar, but it does not on the classpath.

How to reproduce:

1. using Java 21
2. sbt console

Welcome to Scala 2.13.16 (Java HotSpot(TM) 64-Bit Server VM, Java 21.0.5).

scala> classOf[org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool]
                                         ^
       error: type PekkoJdk9ForkJoinPool is not a member of package org.apache.pekko.dispatch

scala> 

I think that's maybe caused by of the Jdk9.scala

[pjfanning]

Existing workaround:

pekko/actor/src/main/scala/org/apache/pekko/dispatch/ForkJoinExecutorConfigurator.scala

Lines 99 to 114 in d30e29d

	private def pekkoJdk9ForkJoinPoolClassOpt: Option[Class[_]] =
	Try(Class.forName("org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool")).toOption
	private lazy val pekkoJdk9ForkJoinPoolHandleOpt: Option[MethodHandle] = {
	if (JavaVersion.majorVersion == 8) {
	None
	} else {
	pekkoJdk9ForkJoinPoolClassOpt.map { clz =>
	val methodHandleLookup = MethodHandles.lookup()
	val mt = MethodType.methodType(classOf[Unit], classOf[Int],
	classOf[ForkJoinPool.ForkJoinWorkerThreadFactory],
	classOf[Int], classOf[Thread.UncaughtExceptionHandler], classOf[Boolean])
	methodHandleLookup.findConstructor(clz, mt)
	}
	}
	}

[raboof]

The classpath of which module are you referring to?

If this is about actor-tests, perhaps you could use a similar technique as at https://github.com/apache/pekko/blob/main/build.sbt#L419 at https://github.com/apache/pekko/blob/main/build.sbt#L128

[He-Pin]

1. Start SBT shell with Java 21/23
2. type console
3. classOf[org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool, class not found.

OR:
When Run a TestJdk9 / testOnly $someJDK21Test on Java 21, and in $someJDK21Test use Class.forName("org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool") , then a ClassNotFoundException throws.

[He-Pin]

I see no integration test for org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool， which must been tested manually.
as the full classpath has no org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool classes, just the product jar, where is the integration test for it @pjfanning ? shouldn't we expect a test for that lives in the scala-jdk9-only folder?

[He-Pin]

@pjfanning It's not I don't know how to write the code, but with the current setup, it can't be integrated tested, if you add an integration test for org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool and show it works, I'm very happy to follow.

[raboof]

1. Start SBT shell with Java 21/23

   2. type console

   3. classOf[org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool, class not found.

classOf is a little weird, but testing with Class.forName("org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool"):

indeed the root project does not depend on the individual modules, so that doesn't have PekkoJdk9ForkJoinPool or any other classes on the path.

actor / CompileJdk9 / console does find it, but indeed actor-tests / Test / console does not.

But with the following change to build.sbt:

 lazy val actorTests = pekkoModule("actor-tests")
   .configs(Jdk9.TestJdk9)
-  .dependsOn(testkit % "compile->compile;test->test", actor)
+  .dependsOn(
+    actor % "compile->CompileJdk9;test->test",
+    testkit % "compile->compile;test->test"
+  )

... it should work like I think you expect.

[He-Pin]

Doesn't work too :(

[raboof]

Interesting! In what way does it not work? How are you testing?

[He-Pin]

with sbt console and java 21

I think it's because the result class is not been added to the class path.

[raboof]

with sbt console and java 21

Hmm, that seems to work for me though.

What if you check out https://github.com/raboof/pekko/pull/new/actor-tests-depend-on-jdk9-classes

and then start sbt like this:

$ sbt
[info] welcome to sbt 1.10.7 (N/A Java 21.0.5)
[info] loading global plugins from /home/aengelen/.sbt/1.0/plugins
[info] loading settings for project cell-build from plugins.sbt...
[info] loading project definition from /cell/project
[info] loading settings for project pekko from build.sbt...
[info] resolving key references (70718 settings) ...
[info] Scala 2 optimizer/inliner enabled, to disable set the pekko.no.inline system property
(...)
pekko > actor-tests / Test / console
(...)
scala> Class.forName("org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool")
val res0: Class[_] = class org.apache.pekko.dispatch.PekkoJdk9ForkJoinPool

do you get a different result?

[pjfanning]

The problem seems to happen when using submodules in this repo. If you use a project with a dependency on a pekko-actor snapshot jar or released jar, the class is there and is used if use Java version 11 up. The code is integration tested by our other modules like pekko-http. It would be nice if it was easier to test.