Index: src/test/org/apache/lucene/index/TestIndexWriterWithThreads.java
===================================================================
--- src/test/org/apache/lucene/index/TestIndexWriterWithThreads.java	(revision 1415996)
+++ src/test/org/apache/lucene/index/TestIndexWriterWithThreads.java	(working copy)
@@ -18,6 +18,9 @@
  */
 
 import java.io.IOException;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
@@ -28,6 +31,7 @@
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.Field;
 import org.apache.lucene.document.FieldType;
+import org.apache.lucene.document.StringField;
 import org.apache.lucene.document.TextField;
 import org.apache.lucene.search.DocIdSetIterator;
 import org.apache.lucene.store.AlreadyClosedException;
@@ -38,10 +42,10 @@
 import org.apache.lucene.util.Bits;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.LineFileDocs;
+import org.apache.lucene.util.LuceneTestCase.Slow;
 import org.apache.lucene.util.LuceneTestCase;
 import org.apache.lucene.util.ThreadInterruptedException;
 import org.apache.lucene.util._TestUtil;
-import org.apache.lucene.util.LuceneTestCase.Slow;
 
 /**
  * MultiThreaded IndexWriter tests
@@ -614,4 +618,21 @@
     writerRef.get().close();
     d.close();
   }
+
+  public void testCommitDataWithThreads() throws Exception {
+    Directory d = newMockDirectory();
+    final RandomIndexWriter w = new RandomIndexWriter(random(), d);
+    final Map<String,String> commitData = new HashMap<String,String>();
+    commitData.put("one", "two");
+    w.addDocument(new Document());
+    w.w.prepareCommit();
+    w.w.setCommitData(commitData);
+    w.commit();
+    w.close();
+
+    List<IndexCommit> commits = DirectoryReader.listCommits(d);
+    assertEquals(1, commits.size());
+    assertEquals("{one=two}", commits.get(0).getUserData().toString());
+    d.close();
+  }
 }