ZIO learning - dealing with blocking operations => Nothing more to do from ZIO2 ? / published by https://github.com/dacr/code-examples-manager #66e3d0f1-9667-457e-bc95-1bcbaa1b1e61/d4d16e33444accafe36d8d60c088c82aa4689e75

zio-learning-27-blocking.sc

// summary : ZIO learning - dealing with blocking operations => Nothing more to do from ZIO2 ?
// keywords : scala, zio, learning, blocking, synchronous, pure-functional, @testable
// publish : gist
// authors : zio
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : 66e3d0f1-9667-457e-bc95-1bcbaa1b1e61
// created-on : 2021-05-14T17:17:37+02:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.4.2"
//> using dep "dev.zio::zio:2.0.13"
// ---------------------

import zio.*

import java.io.IOException
import java.time.Instant

// Since ZIO2 and thanks to the new scheduler ?
// blocking operations should be automatically managed transparently by the ZIO Library !

object BlockingOperations extends ZIOAppDefault {
  // ---------------------------------------------------------------------
  def blockingOperation(message: String): Unit =
    println(message+" "+Instant.now)
    Thread.sleep(5000 + scala.util.Random.nextInt(5000))

  // ---------------------------------------------------------------------
  val badProgram = { // with stuck threads
    def blockingTask(n: Int) = ZIO.attempt {
      blockingOperation(s"BAD - running blocking task number $n")
    }
    ZIO.foreachPar(1 to 200)(blockingTask)
  }

  // ---------------------------------------------------------------------
  val goodProgram = { // This time no issue, the primary pool thread is not overused !
    def blockingTask(n: Int) = ZIO.attemptBlocking {
      blockingOperation(s"GOOD - running blocking task number $n")
    }
    ZIO.foreachPar(1 to 200)(blockingTask)
  }

  // ---------------------------------------------------------------------
  override def run = for {
    _ <- badProgram.timeout(10.seconds)  // Limited number of threads => slow
    _ <- goodProgram.timeout(10.seconds) // spawn as many threads as requires
  } yield ()
}

BlockingOperations.main(Array.empty)