ZPool hangs during parallel item acquisition after invalidation

[daemas]

The following program hangs. Which, I guess, is not supposed to happen.

package test

import zio.{Scope, ZIO, ZIOAppArgs, ZIOAppDefault, ZPool}

import java.time.Duration

object TestPool extends ZIOAppDefault {

  private val program: ZIO[Any, Throwable, Unit] = ZIO.scoped {
    for {
      pool <- ZPool.make(
        ZIO.succeed("item").tap(r => ZIO.logInfo(s"Made $r")),
        0 to 1,
        Duration.ofSeconds(10)
      )
      getZIO = ZIO.scoped {
        for {
          _ <- ZIO.logInfo(s"Acquiring...")
          v <- pool.get
          _ <- ZIO.logInfo(s"Got: $v")
          _ <- pool.invalidate(v)
          _ <- ZIO.logInfo(s"Invalidated")
        } yield v
      }

      res <- ZIO.foreachPar(Seq.fill(2)(0)) { _ => getZIO.tap(r => ZIO.logInfo(s"Received: $r")) }
    } yield ()
  }

  override def run: ZIO[ZIOAppArgs & Scope, Any, Any] = program
}

The log is the following:

thread=#zio-fiber-8 message="Acquiring..." location=test.TestPool.program.getZIO file=TestPool.scala line=18
thread=#zio-fiber-7 message="Acquiring..." location=test.TestPool.program.getZIO file=TestPool.scala line=18
thread=#zio-fiber-9 message="Made item" location=test.TestPool.program file=TestPool.scala line=12
thread=#zio-fiber-7 message="Got: item" location=test.TestPool.program.getZIO file=TestPool.scala line=20
thread=#zio-fiber-7 message="Invalidated" location=test.TestPool.program.getZIO file=TestPool.scala line=22
thread=#zio-fiber-7 message="Received: item" location=test.TestPool.program file=TestPool.scala line=26

(program hangs here)

If I change ZIO.foreachPar to just ZIO.foreach, everything works as expected:

thread=#zio-fiber-4 message="Acquiring..." location=test.TestPool.program.getZIO file=TestPool.scala line=18
thread=#zio-fiber-7 message="Made item" location=test.TestPool.program file=TestPool.scala line=12
thread=#zio-fiber-4 message="Got: item" location=test.TestPool.program.getZIO file=TestPool.scala line=20
thread=#zio-fiber-4 message="Invalidated" location=test.TestPool.program.getZIO file=TestPool.scala line=22
thread=#zio-fiber-4 message="Received: item" location=test.TestPool.program file=TestPool.scala line=26
thread=#zio-fiber-4 message="Acquiring..." location=test.TestPool.program.getZIO file=TestPool.scala line=18
thread=#zio-fiber-8 message="Made item" location=test.TestPool.program file=TestPool.scala line=12
thread=#zio-fiber-4 message="Got: item" location=test.TestPool.program.getZIO file=TestPool.scala line=20
thread=#zio-fiber-4 message="Invalidated" location=test.TestPool.program.getZIO file=TestPool.scala line=22
thread=#zio-fiber-4 message="Received: item" location=test.TestPool.program file=TestPool.scala line=26

Process finished with exit code 0

I use scala 3.4.1 and sbt 1.9.7.
I tried ZIO 2.0.22 and ZIO 2.1.0-RC5, with the same outcome.

[jdegoes]

/bounty $100

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Attempt	Started (GMT+0)	Solution
🟢 @daemas	May 9, 2024, 4:29:22 PM	#8833

[daemas]

/attempt #8820

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