Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/commit/ChildOrderConflictHandler.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/commit/ChildOrderConflictHandler.java	(date 1392290482000)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/commit/ChildOrderConflictHandler.java	(revision )
@@ -92,7 +92,20 @@
             }
         }
 
-        parent.setProperty(merged.getPropertyState());
+        PropertyState propertyState = merged.getPropertyState();
+        dump("o: ", ours);
+        dump("t: ", theirs);
+        dump("m: ", propertyState);
+        parent.setProperty(propertyState);
+    }
+
+    private static void dump(String m, PropertyState propertyState) {
+        Iterable<String> vs = propertyState.getValue(Type.STRINGS);
+        String s = "";
+        for (String v : vs) {
+            s += v + ", ";
+        }
+        System.out.println(m + s);
     }
 
     @Override
Index: oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/ConcurrentAddIT.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/ConcurrentAddIT.java	(date 1392290482000)
+++ oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/ConcurrentAddIT.java	(revision )
@@ -16,21 +16,27 @@
  */
 package org.apache.jackrabbit.oak.jcr;
 
+import static com.google.common.collect.Iterators.transform;
 import static org.apache.jackrabbit.commons.JcrUtils.in;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Random;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import javax.annotation.Nullable;
 import javax.jcr.Node;
 import javax.jcr.RepositoryException;
 import javax.jcr.Session;
 
+import com.google.common.base.Function;
 import com.google.common.collect.Iterators;
+import com.google.common.collect.Sets;
 import org.junit.Assume;
 import org.junit.Test;
 
@@ -40,9 +46,9 @@
  */
 public class ConcurrentAddIT extends AbstractRepositoryTest {
 
-    private static final int NUM_WORKERS = 10;
+    private static final int NUM_WORKERS = 100;
 
-    private static final int NODES_PER_WORKER = 100;
+    private static final int NODES_PER_WORKER = 2;
 
     public ConcurrentAddIT(NodeStoreFixture fixture) {
         super(fixture);
@@ -79,18 +85,16 @@
     public void addNodesSameParent() throws Exception {
         // takes too long with RDBDocumentStore
         Assume.assumeTrue(fixture != NodeStoreFixture.DOCUMENT_JDBC);
-        // FIXME enable again once OAK-1420 is fixed
-        Assume.assumeTrue(fixture != NodeStoreFixture.DOCUMENT_NS);
         List<Exception> exceptions = Collections.synchronizedList(
                 new ArrayList<Exception>());
         // use nt:unstructured to force conflicts on :childOrder property
         Node test = getAdminSession().getRootNode().addNode("test", "nt:unstructured");
+        getAdminSession().save();
         List<Thread> worker = new ArrayList<Thread>();
         for (int i = 0; i < NUM_WORKERS; i++) {
             worker.add(new Thread(new Worker(
                     createAdminSession(), test.getPath(), exceptions)));
         }
-        getAdminSession().save();
         for (Thread t : worker) {
             t.start();
         }
@@ -101,9 +105,34 @@
             fail(e.toString());
         }
         getAdminSession().refresh(false);
-        assertEquals(NODES_PER_WORKER * NUM_WORKERS, Iterators.size(test.getNodes()));
+        int size = Iterators.size(test.getNodes());
+        if (size != NODES_PER_WORKER * NUM_WORKERS) {
+            HashSet<String> nodes = Sets.newHashSet(transform(test.getNodes(),
+                    new Function<Node, String>() {
+                @Nullable
+                @Override
+                public String apply(Node node) {
+                    try {
+                        return node.getName();
+                    } catch (RepositoryException e) {
+                        return null;
-    }
+                    }
+                }
+            }));
 
+            for (int w = 1; w <= NUM_WORKERS; w++) {
+                for (int n = 0; n < NODES_PER_WORKER; n++) {
+                    String name = "worker-" + w + "-node-" + n;
+                    if (!nodes.contains(name)) {
+                        System.out.println(name);
+                    }
+                }
+            }
+
+            assertEquals(NODES_PER_WORKER * NUM_WORKERS, size);
+        }
+    }
+
     private static final class Worker implements Runnable {
 
         private static final AtomicInteger WORKER_ID = new AtomicInteger();
@@ -118,14 +147,18 @@
             this.exceptions = exceptions;
         }
 
+        Random r = new Random();
+
         @Override
         public void run() {
             try {
-                s.refresh(false);
                 Node n = s.getNode(path);
                 for (int i = 0; i < NODES_PER_WORKER; i++) {
                     n.addNode(id + "-node-" + i);
                     s.save();
+                    try {
+                        Thread.sleep(r.nextInt(20));
+                    } catch (InterruptedException e) { }
                 }
             } catch (RepositoryException e) {
                 exceptions.add(e);
Index: oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/AbstractRepositoryTest.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/AbstractRepositoryTest.java	(date 1392290482000)
+++ oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/AbstractRepositoryTest.java	(revision )
@@ -41,7 +41,7 @@
  * Users of this class must call clear to close the session associated with
  * this instance and clean up the repository when done.
  */
-@RunWith(Parallelized.class)
+@RunWith(Parameterized.class)
 @Ignore("This abstract base class does not have any tests")
 public abstract class AbstractRepositoryTest {
 
@@ -57,11 +57,11 @@
     @Parameterized.Parameters
     public static Collection<Object[]> fixtures() {
         Object[][] fixtures = new Object[][] {
-                {NodeStoreFixture.MK_IMPL},
-                {NodeStoreFixture.DOCUMENT_MK},
+//                {NodeStoreFixture.MK_IMPL},
+//                {NodeStoreFixture.DOCUMENT_MK},
                 {NodeStoreFixture.DOCUMENT_NS},
-                {NodeStoreFixture.SEGMENT_MK},
-                {NodeStoreFixture.DOCUMENT_JDBC},
+//                {NodeStoreFixture.SEGMENT_MK},
+//                {NodeStoreFixture.DOCUMENT_JDBC},
         };
         return Arrays.asList(fixtures);
     }