Github user pwendell commented on a diff in the pull request:
https://github.com/apache/spark/pull/718#discussion_r13366096
--- Diff:
core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala ---
@@ -0,0 +1,203 @@
+/*
+ * 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 java.util.concurrent.atomic.AtomicReference
+
+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", 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.
+ private val appList = new
AtomicReference[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 = getMonotonicTime()
+ 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(offset: Int, count: Int) = {
+ val list = appList.get()
+ val theOffset = if (offset < list.size) offset else 0
+ (list.slice(theOffset, Math.min(theOffset + count, list.size)),
theOffset, list.size)
+ }
+
+ override def getAppInfo(appId: String): ApplicationHistoryInfo = {
+ try {
+ val appLogDir = fs.getFileStatus(new Path(logDir, appId))
+ loadAppInfo(appLogDir, true)
+ } catch {
+ case e: FileNotFoundException => null
+ }
+ }
+
+ /**
+ * 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, but
not reading
+ * applications that hasn't been updated since last time the logs were
checked.
+ */
+ def checkForLogs() = synchronized {
--- End diff --
Does this need to be synchronzied given the new re-factoring? What if you
just added a lock around the `appList` (as discussed earlier) would that be
sufficient?
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