Index: lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
===================================================================
--- lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java	(revision 1421596)
+++ lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java	(working copy)
@@ -26,6 +26,7 @@
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Random;
 
 import org.apache.lucene.analysis.*;
 import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
@@ -57,6 +58,7 @@
 import org.apache.lucene.store.SimpleFSLockFactory;
 import org.apache.lucene.store.SingleInstanceLockFactory;
 import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.IOUtils;
 import org.apache.lucene.util.LuceneTestCase;
 import org.apache.lucene.util.ThreadInterruptedException;
 import org.apache.lucene.util._TestUtil;
@@ -1995,4 +1997,73 @@
     dir.close();
   }
   
+  public void testIterableThrowsException() throws IOException {
+    Directory dir = newDirectory();
+    IndexWriter w = new IndexWriter(dir, newIndexWriterConfig(
+        TEST_VERSION_CURRENT, new MockAnalyzer(random())));
+    int iters = atLeast(100);
+    int docCount = 0;
+    for (int i = 0; i < iters; i++) {
+      List<IndexDocument> docs = new ArrayList<IndexDocument>();
+      FieldType ft = new FieldType(TextField.TYPE_NOT_STORED);
+      
+      int numDocs = atLeast(4);
+      for (int j = 0; j < numDocs; j++) {
+        Document doc = new Document();
+        doc.add(newField("foo", _TestUtil.randomSimpleString(random()), ft));
+        docs.add(doc);
+      }
+      boolean success = false;
+      try {
+        w.addDocuments(new RandomFailingFieldIterable(docs, random()));
+        success = true;
+      } catch (RuntimeException e) {
+        assertEquals("boom", e.getMessage());
+      } finally {
+        if (success) {
+          docCount += docs.size();
+        }
+      }
+    }
+    DirectoryReader reader = w.getReader();
+    assertEquals(docCount, reader.numDocs());
+    IOUtils.close(reader, w, dir);
+  }
+
+  private static class RandomFailingFieldIterable implements Iterable<IndexDocument> {
+    private final List<IndexDocument> docList;
+    private final Random random;
+
+    public RandomFailingFieldIterable(List<IndexDocument> docList, Random random) {
+      this.docList = docList;
+      this.random = random;
+    }
+    
+    @Override
+    public Iterator<IndexDocument> iterator() {
+      final Iterator<IndexDocument> docIter = docList.iterator();
+      return new Iterator<IndexDocument>() {
+
+        @Override
+        public boolean hasNext() {
+          return docIter.hasNext();
+        }
+
+        @Override
+        public IndexDocument next() {
+          if (random.nextInt(5) == 0) {
+            throw new RuntimeException("boom");
+          }
+          return docIter.next();
+        }
+
+        @Override
+        public void remove() {throw new UnsupportedOperationException();}
+        
+        
+      };
+    }
+    
+  }
+  
 }
Index: lucene/core/src/java/org/apache/lucene/index/DocumentsWriterPerThread.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/index/DocumentsWriterPerThread.java	(revision 1421596)
+++ lucene/core/src/java/org/apache/lucene/index/DocumentsWriterPerThread.java	(working copy)
@@ -296,7 +296,9 @@
       infoStream.message("DWPT", Thread.currentThread().getName() + " update delTerm=" + delTerm + " docID=" + docState.docID + " seg=" + segmentInfo.name);
     }
     int docCount = 0;
+    boolean allDocsIndexed = false;
     try {
+      
       for(IndexDocument doc : docs) {
         docState.doc = doc;
         docState.docID = numDocsInRAM;
@@ -343,6 +345,7 @@
 
         finishDocument(null);
       }
+      allDocsIndexed = true;
 
       // Apply delTerm only after all indexing has
       // succeeded, but apply it only to docs prior to when
@@ -354,6 +357,16 @@
       }
 
     } finally {
+      if (!allDocsIndexed && !aborting) {
+        // the iterator threw an exception that is not aborting 
+        // go and mark all docs from this block as deleted
+        int docID = numDocsInRAM-1;
+        final int endDocID = docID - docCount;
+        while (docID > endDocID) {
+          deleteDocID(docID);
+          docID--;
+        }
+      }
       docState.clear();
     }