YARN-6680. Avoid locking overhead for NO_LABEL lookups. Contributed by Daryn Sharp

(cherry picked from commit ee89ac84e6)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/nodelabels/CommonNodeLabelsManager.java

@@ -99,6 +99,8 @@ public class CommonNodeLabelsManager extends AbstractService {
   protected ConcurrentMap<String, Host> nodeCollections =
       new ConcurrentHashMap<String, Host>();
 
+  protected RMNodeLabel noNodeLabel;
+
   protected final ReadLock readLock;
   protected final WriteLock writeLock;
 
@@ -225,7 +227,8 @@ public class CommonNodeLabelsManager extends AbstractService {
     isCentralizedNodeLabelConfiguration  =
         YarnConfiguration.isCentralizedNodeLabelConfiguration(conf);
 
-    labelCollections.put(NO_LABEL, new RMNodeLabel(NO_LABEL));
+    noNodeLabel = new RMNodeLabel(NO_LABEL);
+    labelCollections.put(NO_LABEL, noNodeLabel);
   }
 
   /**
@@ -925,6 +928,9 @@ public class CommonNodeLabelsManager extends AbstractService {
   }
 
   public boolean isExclusiveNodeLabel(String nodeLabel) throws IOException {
+    if (nodeLabel.equals(NO_LABEL)) {
+      return noNodeLabel.getIsExclusive();
+    }
     try {
       readLock.lock();
       RMNodeLabel label = labelCollections.get(nodeLabel);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/nodelabels/RMNodeLabelsManager.java

@@ -503,12 +503,16 @@ public class RMNodeLabelsManager extends CommonNodeLabelsManager {
   
   public Resource getResourceByLabel(String label, Resource clusterResource) {
     label = normalizeLabel(label);
+    if (label.equals(NO_LABEL)) {
+      return noNodeLabel.getResource();
+    }
     try {
       readLock.lock();
-      if (null == labelCollections.get(label)) {
+      RMNodeLabel nodeLabel = labelCollections.get(label);
+      if (nodeLabel == null) {
         return Resources.none();
       }
-      return labelCollections.get(label).getResource();
+      return nodeLabel.getResource();
     } finally {
       readLock.unlock();
     }

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

@@ -28,7 +28,6 @@ import java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock;
 
 import org.apache.hadoop.yarn.api.records.Resource;
 import org.apache.hadoop.yarn.nodelabels.CommonNodeLabelsManager;
-import org.apache.hadoop.yarn.server.resourcemanager.nodelabels.RMNodeLabelsManager;
 import org.apache.hadoop.yarn.util.resource.Resources;
 
 /**
@@ -46,6 +45,7 @@ public class ResourceUsage {
   private Map<String, UsageByLabel> usages;
   // short for no-label :)
   private static final String NL = CommonNodeLabelsManager.NO_LABEL;
+  private final UsageByLabel usageNoLabel;
 
   public ResourceUsage() {
     ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
@@ -53,7 +53,8 @@ public class ResourceUsage {
     writeLock = lock.writeLock();
 
     usages = new HashMap<String, UsageByLabel>();
-    usages.put(NL, new UsageByLabel(NL));
+    usageNoLabel = new UsageByLabel(NL);
+    usages.put(NL, usageNoLabel);
   }
 
   // Usage enum here to make implement cleaner
@@ -323,10 +324,9 @@ public class ResourceUsage {
   }
 
   private Resource _get(String label, ResourceType type) {
-    if (label == null) {
+    if (label == null || label.equals(NL)) {
-      label = RMNodeLabelsManager.NO_LABEL;
+      return normalize(usageNoLabel.resArr[type.idx]);
     }
-    
     try {
       readLock.lock();
       UsageByLabel usage = usages.get(label);
@@ -362,8 +362,8 @@ public class ResourceUsage {
   }
 
   private UsageByLabel getAndAddIfMissing(String label) {
-    if (label == null) {
+    if (label == null || label.equals(NL)) {
-      label = RMNodeLabelsManager.NO_LABEL;
+      return usageNoLabel;
     }
     if (!usages.containsKey(label)) {
       UsageByLabel u = new UsageByLabel(label);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/TestRMWebApp.java

@@ -52,6 +52,7 @@ import org.apache.hadoop.yarn.server.resourcemanager.RMContextImpl;
 import org.apache.hadoop.yarn.server.resourcemanager.ResourceManager;
 import org.apache.hadoop.yarn.server.resourcemanager.applicationsmanager.MockAsm;
 import org.apache.hadoop.yarn.server.resourcemanager.nodelabels.NullRMNodeLabelsManager;
+import org.apache.hadoop.yarn.server.resourcemanager.nodelabels.RMNodeLabelsManager;
 import org.apache.hadoop.yarn.server.resourcemanager.rmapp.RMApp;
 import org.apache.hadoop.yarn.server.resourcemanager.rmnode.RMNode;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.ResourceScheduler;
@@ -228,12 +229,15 @@ public class TestRMWebApp {
     setupQueueConfiguration(conf);
 
     CapacityScheduler cs = new CapacityScheduler();
-    cs.setConf(new YarnConfiguration());
+    YarnConfiguration yarnConf = new YarnConfiguration();
+    cs.setConf(yarnConf);
     RMContext rmContext = new RMContextImpl(null, null, null, null, null,
         null, new RMContainerTokenSecretManager(conf),
         new NMTokenSecretManagerInRM(conf),
         new ClientToAMTokenSecretManagerInRM(), null);
-    rmContext.setNodeLabelManager(new NullRMNodeLabelsManager());
+    RMNodeLabelsManager labelManager = new NullRMNodeLabelsManager();
+    labelManager.init(yarnConf);
+    rmContext.setNodeLabelManager(labelManager);
     cs.setRMContext(rmContext);
     cs.init(conf);
     return cs;