YARN-2313. Livelock can occur in FairScheduler when there are lots of running apps (Tsuyoshi Ozawa via Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1612769 13f79535-47bb-0310-9956-ffa450edef68

hadoop-yarn-project/CHANGES.txt

@@ -91,6 +91,9 @@ Release 2.6.0 - UNRELEASED
     YARN-2273. NPE in ContinuousScheduling thread when we lose a node. 
     (Wei Yan via kasha)
 
+    YARN-2313. Livelock can occur in FairScheduler when there are lots of
+    running apps (Tsuyoshi Ozawa via Sandy Ryza)
+
 Release 2.5.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-yarn-project/hadoop-yarn/dev-support/findbugs-exclude.xml

@@ -194,6 +194,12 @@
     <Field name="scheduleAsynchronously" />
     <Bug pattern="IS2_INCONSISTENT_SYNC" />
   </Match>
+  <!-- Inconsistent sync warning - updateInterval is only initialized once and never changed -->
+  <Match>
+    <Class name="org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler" />
+    <Field name="updateInterval" />
+    <Bug pattern="IS2_INCONSISTENT_SYNC" />
+  </Match>
   <!-- Inconsistent sync warning - numRetries is only initialized once and never changed -->
   <Match>
     <Class name="org.apache.hadoop.yarn.server.resourcemanager.recovery.ZKRMStateStore" />

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java

@@ -135,7 +135,7 @@ public class FairScheduler extends
   public static final Resource CONTAINER_RESERVED = Resources.createResource(-1);
 
   // How often fair shares are re-calculated (ms)
-  protected long UPDATE_INTERVAL = 500;
+  protected long updateInterval;
   private final int UPDATE_DEBUG_FREQUENCY = 5;
   private int updatesToSkipForDebug = UPDATE_DEBUG_FREQUENCY;
 
@@ -244,13 +244,13 @@ public class FairScheduler extends
 
   /**
    * A runnable which calls {@link FairScheduler#update()} every
-   * <code>UPDATE_INTERVAL</code> milliseconds.
+   * <code>updateInterval</code> milliseconds.
    */
   private class UpdateThread implements Runnable {
     public void run() {
       while (true) {
         try {
-          Thread.sleep(UPDATE_INTERVAL);
+          Thread.sleep(updateInterval);
           update();
           preemptTasksIfNecessary();
         } catch (Exception e) {
@@ -1206,6 +1206,15 @@ public class FairScheduler extends
     waitTimeBeforeKill = this.conf.getWaitTimeBeforeKill();
     usePortForNodeName = this.conf.getUsePortForNodeName();
 
+    updateInterval = this.conf.getUpdateInterval();
+    if (updateInterval < 0) {
+      updateInterval = FairSchedulerConfiguration.DEFAULT_UPDATE_INTERVAL_MS;
+      LOG.warn(FairSchedulerConfiguration.UPDATE_INTERVAL_MS
+              + " is invalid, so using default value " +
+              + FairSchedulerConfiguration.DEFAULT_UPDATE_INTERVAL_MS
+              + " ms instead");
+    }
+
     rootMetrics = FSQueueMetrics.forQueue("root", null, true, conf);
     // This stores per-application scheduling information
     this.applications =

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairSchedulerConfiguration.java

@@ -123,6 +123,11 @@ public class FairSchedulerConfiguration extends Configuration {
   protected static final String MAX_ASSIGN = CONF_PREFIX + "max.assign";
   protected static final int DEFAULT_MAX_ASSIGN = -1;
 
+  /** The update interval for calculating resources in FairScheduler .*/
+  public static final String UPDATE_INTERVAL_MS =
+      CONF_PREFIX + "update-interval-ms";
+  public static final int DEFAULT_UPDATE_INTERVAL_MS = 500;
+
   public FairSchedulerConfiguration() {
     super();
   }
@@ -246,6 +251,10 @@ public class FairSchedulerConfiguration extends Configuration {
           "Error reading resource config", ex);
     }
   }
+
+  public long getUpdateInterval() {
+    return getLong(UPDATE_INTERVAL_MS, DEFAULT_UPDATE_INTERVAL_MS);
+  }
   
   private static int findResource(String val, String units)
     throws AllocationConfigurationException {

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/TestFairSchedulerPreemption.java

@@ -94,7 +94,7 @@ public class TestFairSchedulerPreemption extends FairSchedulerTestBase {
     scheduler = (FairScheduler)resourceManager.getResourceScheduler();
 
     scheduler.setClock(clock);
-    scheduler.UPDATE_INTERVAL = 60 * 1000;
+    scheduler.updateInterval = 60 * 1000;
   }
 
   private void registerNodeAndSubmitApp(

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/FairScheduler.apt.vm

@@ -205,6 +205,12 @@ Properties that can be placed in yarn-site.xml
       instead. Defaults to true. If a queue placement policy is given in the
       allocations file, this property is ignored.
 
+ * <<<yarn.scheduler.fair.update-interval-ms>>>
+ 
+    * The interval at which to lock the scheduler and recalculate fair shares,
+      recalculate demand, and check whether anything is due for preemption.
+      Defaults to 500 ms. 
+
 Allocation file format
 
   The allocation file must be in XML format. The format contains five types of