Github user tgravescs commented on a diff in the pull request:
https://github.com/apache/spark/pull/204#discussion_r11434671
--- Diff:
core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala ---
@@ -0,0 +1,322 @@
+/*
+ * 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 javax.servlet.http.HttpServletRequest
+
+import scala.collection.mutable
+
+import org.apache.hadoop.fs.{FileStatus, Path}
+import org.eclipse.jetty.servlet.ServletContextHandler
+
+import org.apache.spark.{Logging, SecurityManager, SparkConf}
+import org.apache.spark.deploy.SparkUIContainer
+import org.apache.spark.ui.SparkUI
+import org.apache.spark.ui.JettyUtils._
+import org.apache.spark.util.Utils
+import org.apache.spark.scheduler.{ApplicationEventListener,
ReplayListenerBus}
+
+/**
+ * A web server that renders SparkUIs of finished applications.
+ *
+ * For the standalone mode, MasterWebUI already achieves this
functionality. Thus, the
+ * main use case of the HistoryServer is in other deploy modes (e.g. Yarn
or Mesos).
+ *
+ * The logging directory structure is as follows: Within the given base
directory, each
+ * application's event logs are maintained in the application's own
sub-directory. This
+ * is the same structure as maintained in the event log write code path in
+ * EventLoggingListener.
+ *
+ * @param baseLogDir The base directory in which event logs are found
+ * @param requestedPort The requested port to which this server is to be
bound
+ */
+class HistoryServer(
+ val baseLogDir: String,
+ requestedPort: Int,
+ conf: SparkConf)
+ extends SparkUIContainer("History Server") with Logging {
+
+ import HistoryServer._
+
+ private val fileSystem = Utils.getHadoopFileSystem(baseLogDir)
+ private val localHost = Utils.localHostName()
+ private val publicHost =
Option(System.getenv("SPARK_PUBLIC_DNS")).getOrElse(localHost)
+ private val port = requestedPort
+ private val securityManager = new SecurityManager(conf)
+ private val indexPage = new IndexPage(this)
+
+ // A timestamp of when the disk was last accessed to check for log
updates
+ private var lastLogCheckTime = -1L
+
+ // If an application is last updated after this threshold, then its UI
is retained
+ private var updateTimeThreshold = -1L
+
+ // Number of applications hidden from the UI because the application
limit has been reached
+ private var numApplicationsHidden = 0
+
+ @volatile private var stopped = false
+
+ /**
+ * 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.
+ */
+ private val logCheckingThread = new Thread {
+ override def run() {
+ while (!stopped) {
+ val now = System.currentTimeMillis
+ if (now - lastLogCheckTime > UPDATE_INTERVAL_MS) {
+ checkForLogs()
+ 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(lastLogCheckTime + UPDATE_INTERVAL_MS - now)
+ }
+ }
+ }
+ }
+
+ private val handlers = Seq[ServletContextHandler](
+ createStaticHandler(STATIC_RESOURCE_DIR, "/static"),
+ createServletHandler("/",
+ (request: HttpServletRequest) => indexPage.render(request),
securityMgr = securityManager)
+ )
+
+ // A mapping of application ID to its history information, which
includes the rendered UI
+ val appIdToInfo = mutable.HashMap[String, ApplicationHistoryInfo]()
+
+ /**
+ * Start the history server.
+ *
+ * This starts a background thread that periodically synchronizes
information displayed on
+ * this UI with the event logs in the provided base directory.
+ */
+ def start() {
+ logCheckingThread.start()
+ }
+
+ /** Bind to the HTTP server behind this web interface. */
+ override def bind() {
+ try {
+ serverInfo = Some(startJettyServer("0.0.0.0", port, handlers, conf))
+ logInfo("Started HistoryServer at http://%s:%d".format(publicHost,
boundPort))
+ } catch {
+ case e: Exception =>
+ logError("Failed to bind HistoryServer", e)
+ System.exit(1)
+ }
+ checkForLogs()
+ }
+
+ /**
+ * Check for any updates to event logs in the base directory. This is
only effective once
+ * the server has been bound.
+ *
+ * If a new finished application is found, the server renders the
associated SparkUI
+ * from the application's event logs, attaches this UI to itself, and
stores metadata
+ * information for this application.
+ *
+ * If the logs for an existing finished application are no longer found,
the server
+ * removes all associated information and detaches the SparkUI.
+ */
+ def checkForLogs() = synchronized {
+ if (serverInfo.isDefined) {
+ lastLogCheckTime = System.currentTimeMillis
+ logDebug("Checking for logs. Time is now
%d.".format(lastLogCheckTime))
+ try {
+ val logStatus = fileSystem.listStatus(new Path(baseLogDir))
+ val logDirs = if (logStatus != null)
logStatus.filter(_.isDir).toSeq else Seq[FileStatus]()
+
+ // Forget about any SparkUIs that can no longer be found
+ val mostRecentAppIds = logDirs.map { dir =>
getAppId(dir.getPath.toString) }
+ appIdToInfo.foreach { case (appId, info) =>
+ if (!mostRecentAppIds.contains(appId)) {
+ detachUI(info.ui)
+ appIdToInfo.remove(appId)
+ updateTimeThreshold = -1L
+ }
+ }
+
+ // Keep track of the number of applications hidden from the UI
this round
+ var _numApplicationsHidden = 0
+
+ // Render SparkUI for any new completed applications
+ logDirs.foreach { dir =>
+ val path = dir.getPath.toString
+ val appId = getAppId(path)
+ val lastUpdated = getModificationTime(dir)
+ if (!appIdToInfo.contains(appId)) {
+ if (lastUpdated > updateTimeThreshold) {
+ maybeRenderUI(appId, path, lastUpdated)
+ } else {
+ // This application was previously blacklisted due to the
application limit
+ _numApplicationsHidden += 1
+ }
+ }
+ // If the cap is reached, remove the least recently updated
application
+ if (appIdToInfo.size > RETAINED_APPLICATIONS) {
+ removeOldestApp()
+ _numApplicationsHidden += 1
+ }
+ }
+
+ numApplicationsHidden = _numApplicationsHidden
+
+ } catch {
+ case t: Throwable => logError("Exception in checking for event log
updates", t)
+ }
+ } else {
+ logWarning("Attempted to check for event log updates before binding
the server.")
+ }
+ }
+
+ /**
+ * Render a new SparkUI from the event logs if the associated
application is finished.
+ *
+ * HistoryServer looks for a special file that indicates application
completion in the given
+ * directory. If this file exists, the associated application is
regarded to be complete, in
+ * which case the server proceeds to render the SparkUI. Otherwise, the
server does nothing.
+ */
+ private def maybeRenderUI(appId: String, logPath: String, lastUpdated:
Long) {
+ val replayBus = new ReplayListenerBus(logPath, fileSystem)
+ replayBus.start()
+
+ // If the application completion file is found
+ if (replayBus.isApplicationComplete) {
+ val ui = new SparkUI(replayBus, appId, "/history/%s".format(appId))
+ val appListener = new ApplicationEventListener
+ replayBus.addListener(appListener)
+
+ // Do not call ui.bind() to avoid creating a new server for each
application
+ ui.start()
+ val success = replayBus.replay()
+ if (success && appListener.applicationStarted) {
+ attachUI(ui)
+ val appName = appListener.appName
+ val sparkUser = appListener.sparkUser
+ val startTime = appListener.startTime
+ val endTime = appListener.endTime
+ ui.setAppName("%s (finished)".format(appName))
+ appIdToInfo(appId) =
+ ApplicationHistoryInfo(appName, startTime, endTime, lastUpdated,
sparkUser, logPath, ui)
+ } else {
+ logWarning("Reconstructing application UI was unsuccessful. Either
no event logs were" +
+ "found or the event signaling application start is missing:
%s".format(logPath))
+ }
+ } else {
+ logWarning("Skipping incomplete application: %s".format(logPath))
+ }
+ }
+
+ /**
+ * Remove the oldest application and detach its associated UI.
+ *
+ * As an optimization, record the last updated time of this application
as the minimum
+ * update time threshold. Only applications with a last updated time
that exceeds this
+ * threshold will be retained by the server. This avoids re-rendering an
old application
+ * that is recently removed.
+ */
+ private def removeOldestApp() {
+ val appToRemove = appIdToInfo.toSeq.minBy { case (_, info) =>
info.lastUpdated }
+ appToRemove match { case (id, info) =>
+ appIdToInfo.remove(id)
+ detachUI(info.ui)
+ updateTimeThreshold = info.lastUpdated
+ }
+ }
+
+ /** Stop the server and close the file system. */
+ override def stop() {
+ super.stop()
+ stopped = true
+ fileSystem.close()
+ }
+
+ /** Parse app ID from the given log path. */
+ def getAppId(logPath: String): String = logPath.split("/").last
+
+ /** Return the address of this server. */
+ def getAddress: String = "http://"; + publicHost + ":" + boundPort
+
+ /** Return the total number of application logs found, whether or not
the UI is retained. */
+ def getTotalApplications: Int = appIdToInfo.size + numApplicationsHidden
+
+ /** Return when this directory was last modified. */
+ private def getModificationTime(dir: FileStatus): Long = {
+ try {
+ val logFiles = fileSystem.listStatus(dir.getPath)
+ if (logFiles != null) {
+ logFiles.map(_.getModificationTime).max
+ } else {
+ dir.getModificationTime
+ }
+ } catch {
+ case t: Throwable =>
+ logError("Exception in accessing modification time of
%s".format(dir.getPath), t)
+ -1L
+ }
+ }
+}
+
+/**
+ * The recommended way of starting and stopping a HistoryServer is through
the scripts
+ * start-history-server.sh and stop-history-server.sh. The path to a base
log directory
+ * is must be specified, while the requested UI port is optional. For
example:
+ *
+ * ./sbin/spark-history-server.sh /tmp/spark-events 18080
+ * ./sbin/spark-history-server.sh hdfs://1.2.3.4:9000/spark-events
+ *
+ * This launches the HistoryServer as a Spark daemon.
+ */
+object HistoryServer {
+ private val conf = new SparkConf
+
+ // Interval between each check for event log updates
+ val UPDATE_INTERVAL_MS = conf.getInt("spark.history.updateInterval", 10)
* 1000
--- End diff --
we need to document the new configs.
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