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From: vanzin <git@git.apache.org>
To: reviews@spark.apache.org
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References: <git-pr-718-spark@git.apache.org>
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Subject: [GitHub] spark pull request: [SPARK-1768] History server
 enhancements.
Content-Type: text/plain
Message-Id: <20140611185345.A20A047041@tyr.zones.apache.org>
Date: Wed, 11 Jun 2014 18:53:45 +0000 (UTC)

Github user vanzin commented on a diff in the pull request:

    https://github.com/apache/spark/pull/718#discussion_r13667055
  
    --- Diff: core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala ---
    @@ -0,0 +1,210 @@
    +/*
    + * 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.spark.deploy.history
    +
    +import java.io.FileNotFoundException
    +
    +import scala.collection.mutable
    +
    +import org.apache.hadoop.fs.{FileStatus, Path}
    +
    +import org.apache.spark.{Logging, SecurityManager, SparkConf}
    +import org.apache.spark.scheduler._
    +import org.apache.spark.ui.SparkUI
    +import org.apache.spark.util.Utils
    +
    +private[history] class FsHistoryProvider(conf: SparkConf) extends ApplicationHistoryProvider
    +  with Logging {
    +
    +  // Interval between each check for event log updates
    +  private val UPDATE_INTERVAL_MS = conf.getInt("spark.history.fs.updateInterval",
    +    conf.getInt("spark.history.updateInterval", 10)) * 1000
    +
    +  private val logDir = conf.get("spark.history.fs.logDirectory")
    +  private val fs = Utils.getHadoopFileSystem(logDir)
    +
    +  // A timestamp of when the disk was last accessed to check for log updates
    +  private var lastLogCheckTimeMs = -1L
    +
    +  // List of applications, in order from newest to oldest.
    +  @volatile private var appList: Seq[ApplicationHistoryInfo] = Nil
    +
    +  /**
    +   * A background thread that periodically checks for event log updates on disk.
    +   *
    +   * If a log check is invoked manually in the middle of a period, this thread re-adjusts the
    +   * time at which it performs the next log check to maintain the same period as before.
    +   *
    +   * TODO: Add a mechanism to update manually.
    +   */
    +  private val logCheckingThread = new Thread("LogCheckingThread") {
    +    override def run() = Utils.logUncaughtExceptions {
    +      while (true) {
    +        val now = getMonotonicTimeMs()
    +        if (now - lastLogCheckTimeMs > UPDATE_INTERVAL_MS) {
    +          Thread.sleep(UPDATE_INTERVAL_MS)
    +        } else {
    +          // If the user has manually checked for logs recently, wait until
    +          // UPDATE_INTERVAL_MS after the last check time
    +          Thread.sleep(lastLogCheckTimeMs + UPDATE_INTERVAL_MS - now)
    +        }
    +        checkForLogs()
    +      }
    +    }
    +  }
    +
    +  initialize()
    +
    +  private def initialize() {
    +    // Validate the log directory.
    +    val path = new Path(logDir)
    +    if (!fs.exists(path)) {
    +      throw new IllegalArgumentException(
    +        "Logging directory specified does not exist: %s".format(logDir))
    +    }
    +    if (!fs.getFileStatus(path).isDir) {
    +      throw new IllegalArgumentException(
    +        "Logging directory specified is not a directory: %s".format(logDir))
    +    }
    +
    +    checkForLogs()
    +    logCheckingThread.setDaemon(true)
    +    logCheckingThread.start()
    +  }
    +
    +  override def getListing() = appList
    +
    +  override def getAppUI(appId: String): SparkUI = {
    +    try {
    +      val appLogDir = fs.getFileStatus(new Path(logDir, appId))
    +      loadAppInfo(appLogDir, true)._2
    +    } catch {
    +      case e: FileNotFoundException => null
    +    }
    +  }
    +
    +  override def getConfig(): Map[String, String] =
    +    Map(("Event Log Location" -> logDir))
    +
    +  /**
    +   * Builds the application list based on the current contents of the log directory.
    +   * Tries to reuse as much of the data already in memory as possible, by not reading
    +   * applications that haven't been updated since last time the logs were checked.
    +   */
    +  private def checkForLogs() = {
    +    lastLogCheckTimeMs = getMonotonicTimeMs()
    +    logDebug("Checking for logs. Time is now %d.".format(lastLogCheckTimeMs))
    +    try {
    +      val logStatus = fs.listStatus(new Path(logDir))
    +      val logDirs = if (logStatus != null) logStatus.filter(_.isDir).toSeq else Seq[FileStatus]()
    +      val logInfos = logDirs
    +        .filter {
    +            dir => fs.isFile(new Path(dir.getPath(), EventLoggingListener.APPLICATION_COMPLETE))
    +          }
    +
    +      val currentApps = Map[String, ApplicationHistoryInfo](
    +        appList.map(app => (app.id -> app)):_*)
    +
    +      // For any application that either (i) is not listed or (ii) has changed since the last time
    +      // the listing was created (defined by the log dir's modification time), load the app's info.
    +      // Otherwise just reuse what's already in memory.
    +      val newApps = new mutable.ArrayBuffer[ApplicationHistoryInfo](logInfos.size)
    +      for (dir <- logInfos) {
    +        val curr = currentApps.getOrElse(dir.getPath().getName(), null)
    +        if (curr == null || curr.lastUpdated < getModificationTime(dir)) {
    +          try {
    +            newApps += loadAppInfo(dir, false)._1
    +          } catch {
    +            case e: Exception => logError(s"Failed to load app info from directory $dir.")
    +          }
    +        } else {
    +          newApps += curr
    +        }
    +      }
    +
    +      appList = newApps.sortBy { info => -info.endTime }
    +    } catch {
    +      case t: Throwable => logError("Exception in checking for event log updates", t)
    +    }
    +  }
    +
    +  /**
    +   * Parse the application's logs to find out the information we need to build the
    +   * listing page.
    +   *
    +   * When creating the listing of available apps, there is no need to load the whole UI for the
    +   * application. The UI is requested by the HistoryServer (by calling getAppInfo()) when the user
    +   * clicks on a specific application.
    +   *
    +   * @param logDir Directory with application's log files.
    +   * @param renderUI Whether to create the SparkUI for the application.
    +   * @return A 2-tuple `(app info, ui)`. `ui` will be null if `renderUI` is false.
    --- End diff --
    
    Yes, you're right (a `registerListener` approach has the same problem as the constructor).


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