DefaultThreadPoolTestApp.scala

import java.lang.management.ManagementFactory
import java.util.concurrent.ThreadPoolExecutor

import scalaz.zio.RTS
//import scalaz.zio.IO

object TheadPoolTestApp {
  def main(args: Array[String]): Unit = {
    val rts = new RTS {}
    val pool = rts.threadPool.asInstanceOf[ThreadPoolExecutor]

    // This is run in a separate thread to output diagnostic information,
    // such as thread pool size and work queue size
    val diagnosticPrinter: Runnable = () => {
      var cycle = 0
      val threadBean = ManagementFactory.getThreadMXBean()

      while (true) {
        cycle += 1
        print(s"Cycle $cycle")
        print(s" thread count = ${threadBean.getThreadCount()}")
        print(s", queue size: ${ pool.getQueue.size()}")
        println(s", task count: ${pool.getCompletedTaskCount} out of ${pool.getTaskCount} completed")
        Thread.sleep(1000L)
      }
    }

    println(s"Available CPUs: ${Runtime.getRuntime.availableProcessors()}")
    println(s"Thread pool size: ${rts.threadPool.asInstanceOf[ThreadPoolExecutor].getCorePoolSize}")

    val threadCounter = new Thread(diagnosticPrinter)
    threadCounter.start()
    Thread.sleep(1)

    println("Start queueing load (> poolSize)")
    val loadVolume = 100
    1.to(loadVolume).foreach { _ =>
      rts.submit {
        Thread.sleep(2000L)
      }

      Thread.sleep(50L) // allow for some overlap between long running tasks
    }

    // Wait for all tasks to finish
    while (pool.getCompletedTaskCount < loadVolume) {
      Thread.sleep(1000L)
    }

    println("Start light load (< poolSize)")
    1.to(5).foreach { _ =>
      rts.submit(Thread.sleep(2000L))
      Thread.sleep(2000L)
    }
  }
}