Question

我正在尝试建模一个系统，它是网站的负载生成器。该网站的网页目前是字符串。

type Page = String

val pages: Vector[Page] = Stream.eval(Task.delay {
  new Random().alphanumeric.take(10).mkString
}).repeat.take(100).runLog.unsafeRun

该网站的用户被建模为随机开始浏览网站：

case class User(userName: String)

def newUser: Task[User] = Task.delay {
  val random = new Random
  val userName = random.alphanumeric.take(5).mkString
  val sleepTime = random.nextInt(10000)
  println(s"${new Date}: ${Thread.currentThread.getName} Generating user ${userName} after ${sleepTime}ms")
  Thread.sleep(sleepTime)
  User(userName)
}

每个用户从一个页面转换到另一个页面，并建模为：

case class Transition(from: Page, to: Page, thinkTime: Int)

def newTransitions(user: User): Stream[Task, Transition] = {
  val init = Transition(pages(0), pages(1), 100)
  Stream.iterateEval(init) { t => nextTransition(user)(t) }
}

def nextTransition(user: User)(curr: Transition): Task[Transition] = Task.delay {
  val random = new Random
  val from: Page = curr.to
  val to: Page = pages(random.nextInt(pages.size))
  val thinkTime: Int = random.nextInt(10000)
  Thread.sleep(thinkTime)
  println(s"${new Date}: ${Thread.currentThread.getName} ${user} transitioning from ${from} to ${to} after thinking for ${thinkTime}ms")
  Transition(from, to, thinkTime)
}

我正在尝试运行此模拟，让4个用户在随机间隔后开始浏览此网站，并且每个用户随机访问三个页面：

implicit val S = fs2.Strategy.fromFixedDaemonPool(8, threadName = "worker")
val users: Stream[Task, User] = Stream.eval(newUser).repeat
val transitions: Stream[Task, Stream[Task, Transition]] = users.map(newTransitions(_).take(3))

transitions.take(4).runLog.async.unsafeRun.map { _.runLog.async.unsafeRun }

输出如下：

Sun Oct 16 12:58:04 PDT 2016: worker-1 Generating user 97qkE after 3700ms
Sun Oct 16 12:58:08 PDT 2016: worker-1 Generating user sMIJs after 2074ms
Sun Oct 16 12:58:10 PDT 2016: worker-1 Generating user CpWWf after 1334ms
Sun Oct 16 12:58:11 PDT 2016: worker-1 Generating user xlQmj after 8825ms
Sun Oct 16 12:58:28 PDT 2016: worker-7 User(97qkE) transitioning from sLBbTbXKhO to 7ROMneDkzl after thinking for 8040ms
Sun Oct 16 12:58:34 PDT 2016: worker-7 User(97qkE) transitioning from 7ROMneDkzl to AK66SuDENi after thinking for 6227ms
Sun Oct 16 12:58:41 PDT 2016: worker-6 User(sMIJs) transitioning from sLBbTbXKhO to U2Qu8Th1oH after thinking for 6599ms
Sun Oct 16 12:58:46 PDT 2016: worker-6 User(sMIJs) transitioning from U2Qu8Th1oH to 3bRBWYUeS0 after thinking for 4920ms
Sun Oct 16 12:58:52 PDT 2016: worker-4 User(CpWWf) transitioning from sLBbTbXKhO to ZVwRydhPe9 after thinking for 6395ms
Sun Oct 16 12:58:54 PDT 2016: worker-4 User(CpWWf) transitioning from ZVwRydhPe9 to yHtly5IrMC after thinking for 1963ms
Sun Oct 16 12:58:57 PDT 2016: worker-2 User(xlQmj) transitioning from sLBbTbXKhO to 6jn7TmxW0O after thinking for 2565ms
Sun Oct 16 12:59:05 PDT 2016: worker-2 User(xlQmj) transitioning from 6jn7TmxW0O to FFROVBvpHJ after thinking for 8535ms

即。没有货币，所有随机睡眠按严格顺序发生。

如何更改此程序，使这些不同的流（开始浏览网站的新用户以及每个用户进行的转换）同时发生？

这是我的完整计划：

import fs2._
import scala.util.Random
import java.util.Date

object Question {
  type Page = String

  val pages: Vector[Page] = Stream.eval(Task.delay {
    new Random().alphanumeric.take(10).mkString
  }).repeat.take(100).runLog.unsafeRun

  case class User(userName: String)

  case class Transition(from: Page, to: Page, thinkTime: Int)

  def newUser: Task[User] = Task.delay {
    val random = new Random
    val userName = random.alphanumeric.take(5).mkString
    val sleepTime = random.nextInt(10000)
    println(s"${new Date}: ${Thread.currentThread.getName} Generating user ${userName} after ${sleepTime}ms")
    Thread.sleep(sleepTime)
    User(userName)
  }

  def nextTransition(user: User)(curr: Transition): Task[Transition] = Task.delay {
    val random = new Random
    val from: Page = curr.to
    val to: Page = pages(random.nextInt(pages.size))
    val thinkTime: Int = random.nextInt(10000)
    Thread.sleep(thinkTime)
    println(s"${new Date}: ${Thread.currentThread.getName} ${user} transitioning from ${from} to ${to} after thinking for ${thinkTime}ms")
    Transition(from, to, thinkTime)
  }

  def newTransitions(user: User): Stream[Task, Transition] = {
    val init = Transition(pages(0), pages(1), 100)
    Stream.iterateEval(init) { t => nextTransition(user)(t) }
  }

  def main(args: Array[String]) {
    implicit val S = fs2.Strategy.fromFixedDaemonPool(8, threadName = "worker")
    val users: Stream[Task, User] = Stream.eval(newUser).repeat
    val transitions: Stream[Task, Stream[Task, Transition]] = users.map(newTransitions(_).take(3))

    transitions.take(4).runLog.async.unsafeRun.map { _.runLog.async.unsafeRun }
  }
}

Answer 1

首先，在你的object Question上，看起来有一个错字。记得切换：

Thread.sleep(sleepTime)
println(s"${new Date}: ${Thread.currentThread.getName} Generating user ${userName} after ${sleepTime}ms")

接下来，您需要使用Task { ... }而不是Task.delay，因为您想在工作线程上运行它。

最后，主函数的最后一行应该是：

fs2.concurrent.join(maxOpen = 3)(transitions).run.unsafeRun

另外，我猜测Thread.sleep只是占位符 - 您不希望在实际代码中使用它们。并且println可以用于调试，但最好在完成后将日志记录作为单独的流构造移动。

同时运行Scala FS2 Streams

1 个答案: