Question

每当我运行使用Future（通过Await，map，onComplete等）的结果的scala流程时，它永远不会退出，强制执行我们手动杀死进程。无论我使用extends App还是仅使用标准def main(args: Array[String])方法，都会发生这种情况。

在我看来，它与ThreadPoolExecutor有关，scala会在函数结束时自动执行Future，但我似乎无法获得处理它以关闭它。

例如，以下代码将无法退出：

object ExecuteApi extends App with StrictLogging{

  lazy val config = StratumConfiguration.setupConfiguration()
  lazy val apiEndpoint = config.getProperty("APIEndpoint").split("/").head
  lazy val packetApiPath = "packets/getpackets"

  val resourceNames = sys.env.getOrElse("ResourceNames", "").stripMargin.split("[\n\\s]+").map(_.trim).filterNot(_.isEmpty)
  val searchBody =
  s"""{
    |  "resourceNames": [
    |    "${(resourceNames).mkString("\",\"")}"
    |  ]
    |}""".stripMargin
    logger.info(searchBody)
    val responseFuture = AmazonAsyncApiGatewayHelper.executeHttpRequest(apiEndpoint, searchBody, Some(packetApiPath), Some("api"))
    val response = Await.result(responseFuture, Duration(25, TimeUnit.SECONDS))
    val layerDefinitions = Json.parse(response)
    println(Json.prettyPrint(layerDefinitions))
}

虽然这段代码退出很好（唯一的变化是返回未来的Async版本，然后等待）：

object ExecuteAPI extends App with StrictLogging{

  lazy val config = Configuration.setupConfiguration()
  lazy val apiEndpoint = config.getProperty("APIEndpoint").split("/").head
  lazy val packetApiPath = "packets/getpackets"

  val resourceNames = sys.env.getOrElse("ResourceNames", "").stripMargin.split("\n").map(_.trim).filterNot(_.isEmpty)

  val searchBody =
  s"""{
    |  "resourceNames": [
    |    "${(resourceNames).mkString("\",\"")}"
    |  ]
    |}""".stripMargin
    logger.info(searchBody)
    val layersResponse = AmazonapiGatewayHelper.executeHttpRequest(apiEndpoint, searchBody, Some(packetApiPath), Some("api"))
    val layerDefinitions = Json.parse(layersResponse)
    println(Json.prettyPrint(layerDefinitions))
}

AmazonAsyncApiGatewayHelper中的代码最终通过执行Play库HTTP客户端创建Future。但是，我们在以其他方式执行期货时已经看到了这一点：

val request = wsClient.url(fullUrl)
    .withRequestTimeout(readTimeout)
val requestWithHeaders = headers.foldLeft(request) { (r, h) =>
  r.withHeaders(h)
}
val playResponseFuture = requestWithHeaders.post(requestBody)

Answer 1

我们最终找到了这个问题。 Play wsClient需要一个actor系统（从Play 2.5开始）。我们需要在退出主类之前手动终止此actor系统。退出的代码如下所示：

object ExecuteAPI extends App with StrictLogging{
 try {
  lazy val config = Configuration.setupConfiguration()
  lazy val apiEndpoint = config.getProperty("APIEndpoint").split("/").head
  lazy val packetApiPath = "packets/getpackets"

  val resourceNames = sys.env.getOrElse("ResourceNames", "").stripMargin.split("\n").map(_.trim).filterNot(_.isEmpty)

  val searchBody =
  s"""{
    |  "resourceNames": [
    |    "${(resourceNames).mkString("\",\"")}"
    |  ]
    |}""".stripMargin
    logger.info(searchBody)
    val responseFuture = AmazonAsyncApiGatewayHelper.executeHttpRequest(apiEndpoint, searchBody, Some(packetApiPath), Some("api"))
    val response = Await.result(responseFuture, Duration(25, TimeUnit.SECONDS))
    val layerDefinitions = Json.parse(response)
    println(Json.prettyPrint(layerDefinitions))
 } finally {
    AmazonAsyncApiGatewayHelper.client.actorSystem.terminate()
 }
}

Answer 2

您可以映射未来值并在最后添加Thread.sleep()。

val result = layersResponse  map { futureValue =>
 Json.parse(layerResponse)
}

Thread.sleep(10000)
println(Json.prettyPrint(result))

等待期货时，Scala控制台应用程序永远不会退出

2 个答案: