Github user pwendell commented on a diff in the pull request:
https://github.com/apache/spark/pull/204#discussion_r11469876
--- Diff:
core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala ---
@@ -0,0 +1,287 @@
+/*
+ * 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.scheduler._
+import org.apache.spark.ui.SparkUI
+import org.apache.spark.ui.JettyUtils._
+import org.apache.spark.util.Utils
+
+/**
+ * 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
+ */
+class HistoryServer(
+ val baseLogDir: String,
+ 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 = WEB_UI_PORT
+ 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
+
+ // Number of complete applications found in this directory
+ private var numApplicationsTotal = 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.
+ *
+ * TODO: Add a mechanism to update manually.
+ */
+ 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)
+ }
+ }
+
+ /**
+ * 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]()
+ val logInfos = logDirs
+ .sortBy { dir => getModificationTime(dir) }
+ .map { dir => (dir,
EventLoggingListener.parseLoggingInfo(dir.getPath, fileSystem)) }
+ .filter { case (dir, info) => info.applicationComplete }
+
+ // Logging information for applications that should be retained
+ val retainedLogInfos = logInfos.takeRight(RETAINED_APPLICATIONS)
+ val retainedAppIds = retainedLogInfos.map { case (dir, _) =>
dir.getPath.getName }
+
+ // Remove any applications that should no longer be retained
+ appIdToInfo.foreach { case (appId, info) =>
+ if (!retainedAppIds.contains(appId)) {
+ detachUI(info.ui)
+ appIdToInfo.remove(appId)
+ }
+ }
+
+ // Render the application's UI if it is not already there
+ retainedLogInfos.foreach { case (dir, info) =>
+ val appId = dir.getPath.getName
+ if (!appIdToInfo.contains(appId)) {
+ renderSparkUI(dir, info)
+ }
+ }
+
+ // Track the total number of complete applications observed this
round
+ numApplicationsTotal = logInfos.size
+
+ } 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 renderSparkUI(logDir: FileStatus, logInfo: EventLoggingInfo)
{
+ val path = logDir.getPath
+ val appId = path.getName
+ val replayBus = new ReplayListenerBus(logInfo.logPaths, fileSystem,
logInfo.compressionCodec)
+ val ui = new SparkUI(replayBus, appId, "/history/" + appId)
+ val appListener = new ApplicationEventListener
--- End diff --
Is there any reason the `SparkUI` couldn't be modify to just collect and
expose the fields that the `ApplicaitonEventListener` currently deals with?
Then you wouldn't have to create this extra listener class. Doesn't the SparkUI
class need to know all of this stuff anyways?
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