Index: src/test/org/apache/lucene/index/TestAddIndexesNoOptimize.java
===================================================================
--- src/test/org/apache/lucene/index/TestAddIndexesNoOptimize.java	(revision 650838)
+++ src/test/org/apache/lucene/index/TestAddIndexesNoOptimize.java	(working copy)
@@ -26,6 +26,7 @@
 import org.apache.lucene.document.Field;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.RAMDirectory;
+import org.apache.lucene.store.MockRAMDirectory;
 
 import org.apache.lucene.search.PhraseQuery;
 
@@ -432,9 +433,8 @@
   private void addDocs(IndexWriter writer, int numDocs) throws IOException {
     for (int i = 0; i < numDocs; i++) {
       Document doc = new Document();
-      doc
-          .add(new Field("content", "aaa", Field.Store.NO,
-              Field.Index.TOKENIZED));
+      doc.add(new Field("content", "aaa", Field.Store.NO,
+                        Field.Index.TOKENIZED));
       writer.addDocument(doc);
     }
   }
@@ -442,9 +442,8 @@
   private void addDocs2(IndexWriter writer, int numDocs) throws IOException {
     for (int i = 0; i < numDocs; i++) {
       Document doc = new Document();
-      doc
-          .add(new Field("content", "bbb", Field.Store.NO,
-              Field.Index.TOKENIZED));
+      doc.add(new Field("content", "bbb", Field.Store.NO,
+                        Field.Index.TOKENIZED));
       writer.addDocument(doc);
     }
   }
@@ -495,4 +494,47 @@
     assertEquals(3, writer.getSegmentCount());
     writer.close();
   }
+
+  // LUCENE-1270
+  public void testHangOnClose() throws IOException {
+
+    Directory dir = new MockRAMDirectory();
+    IndexWriter writer = new IndexWriter(dir, false, new WhitespaceAnalyzer(), true, IndexWriter.MaxFieldLength.LIMITED);
+    writer.setMergePolicy(new LogByteSizeMergePolicy());
+    writer.setMaxBufferedDocs(5);
+    writer.setUseCompoundFile(false);
+    writer.setMergeFactor(100);
+
+    Document doc = new Document();
+    doc.add(new Field("content", "aaa bbb ccc ddd eee fff ggg hhh iii", Field.Store.YES,
+                      Field.Index.TOKENIZED, Field.TermVector.WITH_POSITIONS_OFFSETS));
+    for(int i=0;i<60;i++)
+      writer.addDocument(doc);
+    writer.setMaxBufferedDocs(200);
+    Document doc2 = new Document();
+    doc2.add(new Field("content", "aaa bbb ccc ddd eee fff ggg hhh iii", Field.Store.YES,
+                      Field.Index.NO));
+    doc2.add(new Field("content", "aaa bbb ccc ddd eee fff ggg hhh iii", Field.Store.YES,
+                      Field.Index.NO));
+    doc2.add(new Field("content", "aaa bbb ccc ddd eee fff ggg hhh iii", Field.Store.YES,
+                      Field.Index.NO));
+    doc2.add(new Field("content", "aaa bbb ccc ddd eee fff ggg hhh iii", Field.Store.YES,
+                      Field.Index.NO));
+    for(int i=0;i<10;i++)
+      writer.addDocument(doc2);
+    writer.close();
+
+    Directory dir2 = new MockRAMDirectory();
+    writer = new IndexWriter(dir2, false, new WhitespaceAnalyzer(), true, IndexWriter.MaxFieldLength.LIMITED);
+    LogByteSizeMergePolicy lmp = new LogByteSizeMergePolicy();
+    lmp.setMinMergeMB(0.0001);
+    writer.setMergePolicy(lmp);
+    writer.setMergeFactor(4);
+    writer.setUseCompoundFile(false);
+    writer.setMergeScheduler(new SerialMergeScheduler());
+    writer.addIndexesNoOptimize(new Directory[] {dir});
+    writer.close();
+    dir.close();
+    dir2.close();
+  }
 }
Index: src/java/org/apache/lucene/index/IndexWriter.java
===================================================================
--- src/java/org/apache/lucene/index/IndexWriter.java	(revision 650838)
+++ src/java/org/apache/lucene/index/IndexWriter.java	(working copy)
@@ -1658,6 +1658,11 @@
       // going to wait for merges:
       flush(waitForMerges, true, true);
 
+      if (waitForMerges)
+        // Give merge scheduler last chance to run, in case
+        // any pending merges are waiting:
+        mergeScheduler.merge(this);
+
       mergePolicy.close();
 
       finishMerges(waitForMerges);
@@ -2889,6 +2894,9 @@
    * then copy them over.  Currently this is only used by
    * addIndexesNoOptimize(). */
   private void copyExternalSegments() throws CorruptIndexException, IOException {
+
+    boolean any = false;
+
     while(true) {
       SegmentInfo info = null;
       MergePolicy.OneMerge merge = null;
@@ -2907,6 +2915,7 @@
         if (registerMerge(merge)) {
           pendingMerges.remove(merge);
           runningMerges.add(merge);
+          any = true;
           merge(merge);
         } else
           // This means there is a bug in the
@@ -2923,6 +2932,11 @@
         // No more external segments
         break;
     }
+
+    if (any)
+      // Sometimes, on copying an external segment over,
+      // more merges may become necessary:
+      mergeScheduler.merge(this);
   }
 
   /** Merges the provided indexes into this index.