scala - 使用响应式(Reactive) mongo 驱动程序时，控制台 Scala 应用程序不会停止

Question

我正在通过 Reactive Mongo 驱动程序使用 Mongo 数据库

import org.slf4j.LoggerFactory

import reactivemongo.api.MongoDriver
import reactivemongo.api.collections.default.BSONCollection
import reactivemongo.bson.BSONDocument

import scala.concurrent.Future
import scala.concurrent.duration._
import scala.concurrent.ExecutionContext.Implicits.global

object Main {

  val log = LoggerFactory.getLogger("Main")

  def main(args: Array[String]): Unit = {

    log.info("Start")

    val conn = new MongoDriver().connection(List("localhost"))
    val db = conn("test")

    log.info("Done")

  }
}

我的 build.sbt文件:

lazy val root = (project in file(".")).
  settings(
    name := "simpleapp",
    version := "1.0.0",
    scalaVersion := "2.11.4",
    libraryDependencies ++= Seq(
      "org.reactivemongo" %% "reactivemongo" % "0.10.5.0.akka23",
      "ch.qos.logback" % "logback-classic" % "1.1.2"
    )
  )

当我运行时:sbt compile run
我得到这个输出:

$ sbt compile run
[success] Total time: 0 s, completed Apr 25, 2015 5:36:51 PM
[info] Running Main 
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.
17:36:52.328 [run-main-0] INFO  Main - Start
17:36:52.333 [run-main-0] INFO  Main - Done

并且应用程序不会停止....:/

我必须按 Ctrl + C 才能杀死它

我读过 MongoDriver()创建 ActorSystem所以我尝试使用 conn.close() 手动关闭连接但我明白了:

[info] Running Main 
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.
17:42:23.252 [run-main-0] INFO  Main - Start
17:42:23.258 [run-main-0] INFO  Main - Done
17:42:23.403 [reactivemongo-akka.actor.default-dispatcher-2] ERROR reactivemongo.core.actors.MongoDBSystem - (State: Closing) UNHANDLED MESSAGE: ChannelConnected(-973180998)
[INFO] [04/25/2015 17:42:23.413] [reactivemongo-akka.actor.default-dispatcher-3] [akka://reactivemongo/deadLetters] Message [reactivemongo.core.actors.Closed$] from Actor[akka://reactivemongo/user/$b#-1700211063] to Actor[akka://reactivemongo/deadLetters] was not delivered. [1] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.
[INFO] [04/25/2015 17:42:23.414] [reactivemongo-akka.actor.default-dispatcher-3] [akka://reactivemongo/user/$a] Message [reactivemongo.core.actors.Close$] from Actor[akka://reactivemongo/user/$b#-1700211063] to Actor[akka://reactivemongo/user/$a#-1418324178] was not delivered. [2] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'. 

而且应用程序也不会退出

那么，我做错了什么？我找不到答案...

在我看来，官方文档根本没有解释我是否应该关心优雅关机。

我对控制台应用程序没有太多经验，我在我的项目中使用 play 框架，但我想创建与 mongodb 一起使用的子项目

我看到许多模板(在激活器中)，例如:Play + Reactive Mongo、Play + Akka + Mongo 但没有 Scala + Reactive Mongo 可以解释如何正常工作:/

Answer 1

我遇到了同样的问题。我找到的解决方案是在对象、驱动程序和连接上调用 close:

val driver = new MongoDriver
val connection = driver.connection(List("localhost"))
...
connection.close()
driver.close()

如果您只关闭连接，那么 akka 系统将保持事件状态。

使用 ReactiveMongo 0.12 测试