我试图顺序启动三个作业,但是当我尝试此代码时:
val jobs = Seq("stream.Job1","stream.Job2","stream.Job3")
Future.sequence {
jobs.map { jobClass =>
Future {
println(s"Starting the spark job from class $jobClass...")
% gcloud("sparkC", "jobs", "submit", "spark", s"--cluster=$clusterName", s"--class=$jobClass", "--region=global", s"--jars=$JarFile")
println(s"Starting the spark job from class $jobClass...DONE")
}
}
}
我并联三个作业,然后是顺序。我认为解决方案是使用flatMap
,但我无法实施。
请任何帮助。
尝试此
val jobs = Seq("stream.Job1","stream.Job2","stream.Job3")
jobs.foldLeft(Future.successful[Unit]()) {
case (result, jobClass) =>
result.flatMap[Unit] {_ =>
Future {
println(s"Starting the spark job from class $jobClass...")
% gcloud("sparkC", "jobs", "submit", "spark", s"--cluster=$clusterName", s"--class=$jobClass", "--region=global", s"--jars=$JarFile")
println(s"Starting the spark job from class $jobClass...DONE")
}
}.
recoverWith {
case NonFatal(e) => result
}
}
这将迭代您的工作,并在上一个完成后立即运行。我添加了recoverWith
块以独立处理所有Futures
,如果其中任何一个失败
如果作业不依赖彼此,并且如果您想拥有结果列表最后,您可以使用以下方式:
import scala.concurrent._
def runIndependentSequentially[X]
(futs: List[() => Future[X]])
(implicit ec: ExecutionContext): Future[List[X]] = futs match {
case Nil => Future { Nil }
case h :: t => for {
x <- h()
xs <- runIndependentSequentially(t)
} yield x :: xs
}
现在,您可以在工作期货清单上使用它,如下所示:
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.duration._
import scala.language.postfixOps
val jobs = List("stream.Job1","stream.Job2","stream.Job3")
val futFactories = jobs.map { jobClass =>
() => Future {
println(s"Starting the spark job from class $jobClass...")
Thread.sleep(5000)
"result[" + jobClass + "," + (System.currentTimeMillis / 1000) % 3600 + "]"
}
}
println(Await.result(runIndependentSequentially(futFactories), 30 seconds))
这会产生以下输出:
Starting the spark job from class stream.Job1...
Starting the spark job from class stream.Job2...
Starting the spark job from class stream.Job3...
List(result[stream.Job1,3011], result[stream.Job2,3016], result[stream.Job3,3021])
update :由List[() => Future[X]]
替换了期货列表,以便即使在论证传递给该论点之前,对期货的评估也不会开始 runIndependentSequentially
方法。非常感谢@Evgeny指出它!