[14/18] ambari git commit: AMBARI-21427. Assigning hosts concurrently to same config group may fail with 'org.apache.ambari.server.controller.spi.ResourceAlreadyExistsException: Config group already exist'. (stoader)

[rl...@apache.org]

AMBARI-21427. Assigning hosts concurrently to same config group may fail with 'org.apache.ambari.server.controller.spi.ResourceAlreadyExistsException: Config group already exist'. (stoader)


Project: http://git-wip-us.apache.org/repos/asf/ambari/repo
Commit: http://git-wip-us.apache.org/repos/asf/ambari/commit/3c9f125c
Tree: http://git-wip-us.apache.org/repos/asf/ambari/tree/3c9f125c
Diff: http://git-wip-us.apache.org/repos/asf/ambari/diff/3c9f125c

Branch: refs/heads/branch-feature-AMBARI-20859
Commit: 3c9f125cc08269558f35a971c321777d331de1ca
Parents: 7f3d3b2
Author: Toader, Sebastian <st...@hortonworks.com>
Authored: Mon Jul 10 13:02:20 2017 +0200
Committer: Toader, Sebastian <st...@hortonworks.com>
Committed: Mon Jul 10 13:02:45 2017 +0200

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 .../ambari/server/topology/AmbariContext.java   | 28 +++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)
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http://git-wip-us.apache.org/repos/asf/ambari/blob/3c9f125c/ambari-server/src/main/java/org/apache/ambari/server/topology/AmbariContext.java
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diff --git a/ambari-server/src/main/java/org/apache/ambari/server/topology/AmbariContext.java b/ambari-server/src/main/java/org/apache/ambari/server/topology/AmbariContext.java
index 9b64edc..dee0e6c 100644
--- a/ambari-server/src/main/java/org/apache/ambari/server/topology/AmbariContext.java
+++ b/ambari-server/src/main/java/org/apache/ambari/server/topology/AmbariContext.java
@@ -30,6 +30,7 @@ import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.concurrent.Callable;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.locks.Lock;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
@@ -81,6 +82,7 @@ import org.slf4j.LoggerFactory;
 
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Sets;
+import com.google.common.util.concurrent.Striped;
 import com.google.inject.Provider;
 
 
@@ -121,6 +123,16 @@ public class AmbariContext {
 
   private final static Logger LOG = LoggerFactory.getLogger(AmbariContext.class);
 
+
+  /**
+   * When config groups are created using Blueprints these are created when
+   * hosts join a hostgroup and are added to the corresponding config group.
+   * Since hosts join in parallel there might be a race condition in creating
+   * the config group a host is to be added to. Thus we need to synchronize
+   * the creation of config groups with the same name.
+   */
+  private Striped<Lock> configGroupCreateLock = Striped.lazyWeakLock(1);
+
   public boolean isClusterKerberosEnabled(long clusterId) {
     Cluster cluster;
     try {
@@ -341,11 +353,17 @@ public class AmbariContext {
   }
 
   public void registerHostWithConfigGroup(final String hostName, final ClusterTopology topology, final String groupName) {
+    String qualifiedGroupName = getConfigurationGroupName(topology.getBlueprint().getName(), groupName);
+
+    Lock configGroupLock = configGroupCreateLock.get(qualifiedGroupName);
+
     try {
+      configGroupLock.lock();
+
       boolean hostAdded = RetryHelper.executeWithRetry(new Callable<Boolean>() {
         @Override
         public Boolean call() throws Exception {
-          return addHostToExistingConfigGroups(hostName, topology, groupName);
+          return addHostToExistingConfigGroups(hostName, topology, qualifiedGroupName);
         }
       });
       if (!hostAdded) {
@@ -355,6 +373,9 @@ public class AmbariContext {
       LOG.error("Unable to register config group for host: ", e);
       throw new RuntimeException("Unable to register config group for host: " + hostName);
     }
+    finally {
+      configGroupLock.unlock();
+    }
   }
 
   public RequestStatusResponse installHost(String hostName, String clusterName, Collection<String> skipInstallForComponents, Collection<String> dontSkipInstallForComponents, boolean skipFailure) {
@@ -562,7 +583,7 @@ public class AmbariContext {
   /**
    * Add the new host to an existing config group.
    */
-  private boolean addHostToExistingConfigGroups(String hostName, ClusterTopology topology, String groupName) {
+  private boolean addHostToExistingConfigGroups(String hostName, ClusterTopology topology, String configGroupName) {
     boolean addedHost = false;
     Clusters clusters;
     Cluster cluster;
@@ -576,9 +597,8 @@ public class AmbariContext {
     // I don't know of a method to get config group by name
     //todo: add a method to get config group by name
     Map<Long, ConfigGroup> configGroups = cluster.getConfigGroups();
-    String qualifiedGroupName = getConfigurationGroupName(topology.getBlueprint().getName(), groupName);
     for (ConfigGroup group : configGroups.values()) {
-      if (group.getName().equals(qualifiedGroupName)) {
+      if (group.getName().equals(configGroupName)) {
         try {
           Host host = clusters.getHost(hostName);
           addedHost = true;