[GitHub] [incubator-livy] jahstreet commented on a change in pull request #249: [LIVY-702]: Submit Spark apps to Kubernetes

[GitBox <gi...@apache.org>]

jahstreet commented on a change in pull request #249: [LIVY-702]: Submit Spark apps to Kubernetes
URL: https://github.com/apache/incubator-livy/pull/249#discussion_r353977634
 
 

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 File path: server/src/main/scala/org/apache/livy/utils/SparkKubernetesApp.scala
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.livy.utils
+
+import java.util.concurrent.TimeoutException
+
+import scala.annotation.tailrec
+import scala.collection.mutable.ArrayBuffer
+import scala.concurrent._
+import scala.concurrent.duration._
+import scala.language.postfixOps
+import scala.util.{Failure, Success, Try}
+import scala.util.control.NonFatal
+
+import io.fabric8.kubernetes.api.model._
+import io.fabric8.kubernetes.client._
+
+import org.apache.livy.{LivyConf, Logging, Utils}
+
+object SparkKubernetesApp extends Logging {
+
+  lazy val kubernetesClient: LivyKubernetesClient =
+    KubernetesClientFactory.createKubernetesClient(livyConf)
+
+  private val RETRY_BACKOFF_MILLIS = 1000
+  private val leakedAppTags = new java.util.concurrent.ConcurrentHashMap[String, Long]()
+
+  private val leakedAppsGCThread = new Thread() {
+    override def run(): Unit = {
+      while (true) {
+        if (!leakedAppTags.isEmpty) {
+          // kill the app if found it or remove it if exceeding a threshold
+          val leakedApps = leakedAppTags.entrySet().iterator()
+          val now = System.currentTimeMillis()
+          try {
+            val apps = withRetry(kubernetesClient.getApplications()).groupBy(_.getApplicationTag)
+            while (leakedApps.hasNext) {
+              val leakedApp = leakedApps.next()
+              apps.get(leakedApp.getKey) match {
+                case Some(seq) =>
+                  seq.foreach(app =>
+                    if (withRetry(kubernetesClient.killApplication(app))) {
+                      leakedApps.remove()
+                      info(s"Killed leaked app with tag ${leakedApp.getKey}")
+                    } else {
+                      warn(s"Leaked app with tag ${leakedApp.getKey} haven't been killed")
+                    }
+                  )
+                case None if (leakedApp.getValue - now) > sessionLeakageCheckTimeout =>
+                  leakedApps.remove()
+                  warn(s"Leaked app with tag ${leakedApp.getKey} doesn't exist")
+              }
+            }
+          } catch {
+            case e: KubernetesClientException =>
+              error("Kubernetes client failure", e)
+            case NonFatal(e) =>
+              error("Failed to remove leaked apps", e)
+          }
+        }
+        Thread.sleep(sessionLeakageCheckInterval)
+      }
+    }
+  }
+
+  private var livyConf: LivyConf = _
+  private var sessionLeakageCheckTimeout: Long = _
+  private var sessionLeakageCheckInterval: Long = _
+
+  def init(livyConf: LivyConf): Unit = {
+    this.livyConf = livyConf
+    sessionLeakageCheckInterval =
+      livyConf.getTimeAsMs(LivyConf.KUBERNETES_APP_LEAKAGE_CHECK_INTERVAL)
+    sessionLeakageCheckTimeout = livyConf.getTimeAsMs(LivyConf.KUBERNETES_APP_LEAKAGE_CHECK_TIMEOUT)
+    leakedAppsGCThread.setDaemon(true)
+    leakedAppsGCThread.setName("LeakedAppsGCThread")
+    leakedAppsGCThread.start()
+  }
+
+  // Returning T, throwing the exception on failure
+  @tailrec
+  private def withRetry[T](fn: => T, retries: Int = 3): T = {
+    Try { fn } match {
+      case Success(x) => x
+      case _ if retries > 1 =>
+        Thread.sleep(RETRY_BACKOFF_MILLIS)
+        withRetry(fn, retries - 1)
+      case Failure(e) => throw e
+    }
+  }
+
+  private[utils] def mapKubernetesState(
+      kubernetesAppState: String,
+      appTag: String): SparkApp.State.Value = {
+    import KubernetesApplicationState._
+    kubernetesAppState.toLowerCase match {
+      case PENDING =>
+        SparkApp.State.STARTING
+      case RUNNING =>
+        SparkApp.State.RUNNING
+      case SUCCEEDED =>
+        SparkApp.State.FINISHED
+      case FAILED =>
+        SparkApp.State.FAILED
+      case other => // any other combination is invalid, so FAIL the application.
+        error(s"Unknown Kubernetes state $other for app with tag $appTag")
+        SparkApp.State.FAILED
+    }
+  }
+
+  private[utils] object KubernetesApplicationState {
+    val PENDING = "pending"
+    val RUNNING = "running"
+    val SUCCEEDED = "succeeded"
+    val FAILED = "failed"
+  }
+}
+
+class SparkKubernetesApp private[utils](
+    appTag: String,
+    appIdOption: Option[String],
+    process: Option[LineBufferedProcess],
+    listener: Option[SparkAppListener],
+    livyConf: LivyConf,
+    // For unit tests
+    kubernetesClient: => LivyKubernetesClient = SparkKubernetesApp.kubernetesClient)
+  extends SparkApp with Logging {
+
+  import SparkKubernetesApp._
+
+  private val appLookupTimeout =
+    livyConf.getTimeAsMs(LivyConf.KUBERNETES_APP_LOOKUP_TIMEOUT).milliseconds
+  private val cacheLogSize = livyConf.getInt(LivyConf.SPARK_LOGS_SIZE)
+  private val pollInterval = livyConf.getTimeAsMs(LivyConf.KUBERNETES_POLL_INTERVAL).milliseconds
+
+  private var kubernetesAppLog: IndexedSeq[String] = IndexedSeq.empty[String]
+  private var kubernetesDiagnostics: IndexedSeq[String] = IndexedSeq.empty[String]
+
+  private var state: SparkApp.State = SparkApp.State.STARTING
+  private val appPromise: Promise[KubernetesApplication] = Promise()
+
+  private[utils] val kubernetesAppMonitorThread = Utils
+    .startDaemonThread(s"kubernetesAppMonitorThread-$this") {
+      try {
+        val app = try {
+          getAppFromTag(appTag, pollInterval, appLookupTimeout.fromNow)
+        } catch {
+          case e: Exception =>
+            appPromise.failure(e)
+            throw e
+        }
+        appPromise.success(app)
+        val appId = app.getApplicationId
+
+        Thread.currentThread().setName(s"kubernetesAppMonitorThread-$appTag")
+        listener.foreach(_.appIdKnown(appId))
+
+        while (isRunning) {
+          val appReport = withRetry(kubernetesClient.getApplicationReport(app, cacheLogSize))
+          kubernetesAppLog = appReport.getApplicationLog
+          kubernetesDiagnostics = appReport.getApplicationDiagnostics
+          changeState(mapKubernetesState(appReport.getApplicationState, appTag))
+
+          Clock.sleep(pollInterval.toMillis)
+        }
+        debug(s"Application $appId is in state $state\nDiagnostics:" +
+          s"\n${kubernetesDiagnostics.mkString("\n")}")
+      } catch {
+        case _: InterruptedException =>
+          kubernetesDiagnostics = ArrayBuffer("Application stopped by user.")
+          changeState(SparkApp.State.KILLED)
+        case NonFatal(e) =>
+          error("Couldn't refresh Kubernetes state", e)
+          kubernetesDiagnostics = ArrayBuffer(e.getMessage)
+          changeState(SparkApp.State.FAILED)
+      } finally {
+        info(s"Finished monitoring application $appTag with state $state")
+      }
+    }
+
+  override def log(): IndexedSeq[String] = {
+    ("stdout: " +: kubernetesAppLog) ++
+      ("\nstderr: " +: (process.map(_.inputLines).getOrElse(ArrayBuffer.empty[String]) ++
+        process.map(_.errorLines).getOrElse(ArrayBuffer.empty[String]))) ++
+      ("\nKubernetes Diagnostics: " +: kubernetesDiagnostics)
+  }
+
+  override def kill(): Unit = {
+    try {
+      withRetry {
+        kubernetesClient.killApplication(Await.result(appPromise.future, appLookupTimeout))
+      }
+    } catch {
+      // We cannot kill the Kubernetes app without the appTag.
+      // There's a chance the Kubernetes app hasn't been submitted during a livy-server failure.
+      // We don't want a stuck session that can't be deleted. Emit a warning and move on.
+      case _: TimeoutException | _: InterruptedException =>
+        warn("Attempted to delete a session while its Kubernetes application is not found.")
+        kubernetesAppMonitorThread.interrupt()
+    } finally {
+      process.foreach(_.destroy())
+    }
+  }
+
+  private def isRunning: Boolean = {
+    state != SparkApp.State.FAILED &&
+      state != SparkApp.State.FINISHED &&
+      state != SparkApp.State.KILLED
+  }
+
+  private def changeState(newState: SparkApp.State.Value): Unit = {
+    if (state != newState) {
+      listener.foreach(_.stateChanged(state, newState))
+      state = newState
+    }
+  }
+
+  /**
+   * Find the corresponding KubernetesApplication from an application tag.
+   *
+   * @param appTag The application tag tagged on the target application.
+   *               If the tag is not unique, it returns the first application it found.
+   * @return KubernetesApplication or the failure.
+   */
+  @tailrec
+  private def getAppFromTag(
+      appTag: String,
+      pollInterval: Duration,
+      deadline: Deadline): KubernetesApplication = {
+    withRetry(kubernetesClient.getApplications().find(_.getApplicationTag.contains(appTag)))
+    match {
+      case Some(app) => app
+      case None =>
+        if (deadline.isOverdue) {
+          process.foreach(_.destroy())
+          leakedAppTags.put(appTag, System.currentTimeMillis())
+          throw new IllegalStateException(s"No Kubernetes application is found with tag" +
+            s" $appTag in ${livyConf.getTimeAsMs(LivyConf.KUBERNETES_APP_LOOKUP_TIMEOUT) / 1000}" +
+            " seconds. This may be because 1) spark-submit fail to submit application to " +
+            "Kubernetes; or 2) Kubernetes cluster doesn't have enough resources to start the " +
+            "application in time. Please check Livy log and Kubernetes log to know the details.")
+        } else {
+          Clock.sleep(pollInterval.toMillis)
+          getAppFromTag(appTag, pollInterval, deadline)
+        }
+    }
+  }
+
 
 Review comment:
   Note to self: remove the empty line

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