Deadlock with ZIO runtime / init in object

TestRuntime.scala

object TestRuntime {
  object internal {
    val platform : _root_.zio.internal.Platform = _root_.zio.internal.Platform.makeDefault()
    // a local runtime just to build first zlayer
    private val r = Runtime((), platform)


    // non memomized env
    val env = ZEnv.live
    val runtime = Runtime.unsafeFromLayer(env, platform)
    // here, everything is fine
    runtime.unsafeRun(UIO.effectTotal(println("case 2.1: non blocking")))
    runtime.unsafeRun(ZIO.accessM[_root_.zio.blocking.Blocking](_.get.blocking(UIO.effectTotal(println("case 2.2: blocking")))) )
  }

  def main(args: Array[String]): Unit = {
    // in main, this works
    {
      val platform : _root_.zio.internal.Platform = _root_.zio.internal.Platform.makeDefault()
      // a local runtime just to build first zlayer
      val r = Runtime((), platform)
      val env = ZEnv.live
      val runtime = Runtime.unsafeFromLayer(env, platform)
      // here, everything is fine
      runtime.unsafeRun(UIO.effectTotal(println("case 1.1: non blocking")))
      runtime.unsafeRun(ZIO.accessM[_root_.zio.blocking.Blocking](_.get.blocking(UIO.effectTotal(println("case 1.2: blocking")))) )
    }

    println("done in function, start in object")
    // in internal, it blocks
    internal
    println("done")
/* console output:
case 1.1: non blocking
case 1.2: blocking
done in function, start in object
case 2.1: non blocking
// block forever, thread waiting
"zio-default-blocking-1-555173385@1943" daemon prio=5 tid=0x20 nid=NA runnable
  java.lang.Thread.State: RUNNABLE
	  at com.normation.TestRuntime$internal$$$Lambda$388.1905485420.apply$mcV$sp(Unknown Source:-1) // seems to be "1.2 blocking" effect
	  at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
	  at zio.internal.FiberContext.evaluateNow(FiberContext.scala:383)  //  curZio = nextInstr(effect())
	  at zio.internal.FiberContext.$anonfun$evaluateLater$1(FiberContext.scala:679)
	  at zio.internal.FiberContext$$Lambda$224.1368440436.run(Unknown Source:-1)
	  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	  at java.lang.Thread.run(Thread.java:834)
*/
  }
}

Definitly a problem with object, if I replace internal by:

  trait Internal {
    def platform: _root_.zio.internal.Platform
    def runtime : Runtime.Managed[ZEnv]
  }

And then:

  val internal = new Internal () {
    val platform : _root_.zio.internal.Platform = _root_.zio.internal.Platform.makeDefault()
    // a local runtime just to build first zlayer
    private val r = Runtime((), platform)


    // non memomized env
    val env = ZEnv.live
    val runtime = Runtime.unsafeFromLayer(env, platform)
    // here, everything is fine
    runtime.unsafeRun(UIO.effectTotal(println("case 2.1: non blocking")))
    runtime.unsafeRun(ZIO.accessM[_root_.zio.blocking.Blocking](_.get.blocking(UIO.effectTotal(println("case 2.2: blocking")))) )
  }

It does not block

Also works in that case with

    internal.runtime.unsafeRun(UIO.effectTotal(println("case 2.1: non blocking")))
    internal.runtime.unsafeRun(ZIO.accessM[_root_.zio.blocking.Blocking](_.get.blocking(UIO.effectTotal(println("case 2.2: blocking")))) )

Well, it seems to be more complex than that. It works in unit test, but not in real app, so something may be related to other init order.

It may be variant of: zio/zio#1841
But just adding lazy is not sufficient:

object zioRuntime {
  object internal {
    lazy val platform : _root_.zio.internal.Platform = _root_.zio.internal.Platform.makeDefault()
    lazy val environment = {
      // that platform is just for init zlayer
      val r = Runtime((), platform)
      r.unsafeRun(ZEnv.live.build.memoize.map(ZLayer(_)).use(ZIO.succeed(_)))
    }
    lazy val runtime = Runtime.unsafeFromLayer(environment, platform)
    runtime.unsafeRun(UIO.effectTotal(println("**** case 1: non blocking")))
    runtime.unsafeRun(ZIO.accessM[_root_.zio.blocking.Blocking](_.get.blocking(UIO.effectTotal(println("**** case 2: blocking")))).provideLayer(environment) )
    runtime.unsafeRun(_root_.zio.blocking.blocking(UIO.effectTotal(println("**** case 3: blocking variant"))).provideLayer(environment))
  }
}

object TestRuntime {
  def main(args: Array[String]): Unit = {
    zioRuntime.internal.runtime.unsafeRun(UIO.effectTotal(println("**** case 10: non blocking")))
    zioRuntime.internal.runtime.unsafeRun(ZIO.accessM[_root_.zio.blocking.Blocking](_.get.blocking(UIO.effectTotal(println("**** case 20: blocking")))).provideLayer(zioRuntime.internal.environment) )
    zioRuntime.internal.runtime.unsafeRun(_root_.zio.blocking.blocking(UIO.effectTotal(println("**** case 30: blocking variant"))).provideLayer(zioRuntime.internal.environment))
    println("done")
}
``` => blocks in the println #2 in object `internal`

But that works:

class internalRuntime {
    lazy val platform : _root_.zio.internal.Platform = _root_.zio.internal.Platform.makeDefault()
    lazy val environment = {
      // that platform is just for init zlayer
      val r = Runtime((), platform)
      r.unsafeRun(ZEnv.live.build.memoize.map(ZLayer(_)).use(ZIO.succeed(_)))
    }
    lazy val runtime = Runtime.unsafeFromLayer(environment, platform)
    runtime.unsafeRun(UIO.effectTotal(println("**** case 1: non blocking")))
    runtime.unsafeRun(ZIO.accessM[_root_.zio.blocking.Blocking](_.get.blocking(UIO.effectTotal(println("**** case 2: blocking")))).provideLayer(environment) )
    runtime.unsafeRun(_root_.zio.blocking.blocking(UIO.effectTotal(println("**** case 3: blocking variant"))).provideLayer(environment))
  }

object zioRuntime {
  lazy val internal = new internalRuntime()
}
//same TestRuntime