diff --git a/lucene/src/java/org/apache/lucene/index/DocumentsWriter.java b/lucene/src/java/org/apache/lucene/index/DocumentsWriter.java
index 78caa57a205..9a28d4374cb 100644
--- a/lucene/src/java/org/apache/lucene/index/DocumentsWriter.java
+++ b/lucene/src/java/org/apache/lucene/index/DocumentsWriter.java
@@ -338,6 +338,11 @@ final class DocumentsWriter {
     
     if (flushingDWPT != null) {
       maybeMerge |= doFlush(flushingDWPT);
+    } else {
+      final DocumentsWriterPerThread nextPendingFlush = flushControl.nextPendingFlush();
+      if (nextPendingFlush != null) {
+        maybeMerge |= doFlush(nextPendingFlush);
+      }
     }
     return maybeMerge;
   }
diff --git a/lucene/src/java/org/apache/lucene/index/DocumentsWriterDeleteQueue.java b/lucene/src/java/org/apache/lucene/index/DocumentsWriterDeleteQueue.java
index 9cf88061272..33484deec62 100644
--- a/lucene/src/java/org/apache/lucene/index/DocumentsWriterDeleteQueue.java
+++ b/lucene/src/java/org/apache/lucene/index/DocumentsWriterDeleteQueue.java
@@ -64,7 +64,7 @@ import org.apache.lucene.search.Query;
 final class DocumentsWriterDeleteQueue {
 
   private volatile Node tail;
-
+  
   private static final AtomicReferenceFieldUpdater<DocumentsWriterDeleteQueue, Node> tailUpdater = AtomicReferenceFieldUpdater
       .newUpdater(DocumentsWriterDeleteQueue.class, Node.class, "tail");
 
diff --git a/lucene/src/java/org/apache/lucene/index/DocumentsWriterFlushControl.java b/lucene/src/java/org/apache/lucene/index/DocumentsWriterFlushControl.java
index 4b88bb8aba5..7b968a8b4b4 100644
--- a/lucene/src/java/org/apache/lucene/index/DocumentsWriterFlushControl.java
+++ b/lucene/src/java/org/apache/lucene/index/DocumentsWriterFlushControl.java
@@ -128,7 +128,7 @@ public final class DocumentsWriterFlushControl {
         }
       }
     }
-    final DocumentsWriterPerThread flushingDWPT = getFlushIfPending(perThread);
+    final DocumentsWriterPerThread flushingDWPT = tryCheckoutForFlush(perThread, false);
     healthiness.updateStalled(this);
     return flushingDWPT;
   }
@@ -226,18 +226,6 @@ public final class DocumentsWriterFlushControl {
     return null;
   }
 
-  private DocumentsWriterPerThread getFlushIfPending(ThreadState perThread) {
-    if (numPending > 0) {
-      final DocumentsWriterPerThread dwpt = perThread == null ? null
-          : tryCheckoutForFlush(perThread, false);
-      if (dwpt == null) {
-        return nextPendingFlush();
-      }
-      return dwpt;
-    }
-    return null;
-  }
-
   @Override
   public String toString() {
     return "DocumentsWriterFlushControl [activeBytes=" + activeBytes
@@ -257,7 +245,7 @@ public final class DocumentsWriterFlushControl {
       while (allActiveThreads.hasNext() && numPending > 0) {
         ThreadState next = allActiveThreads.next();
         if (next.flushPending) {
-          DocumentsWriterPerThread dwpt = tryCheckoutForFlush(next, false);
+          final DocumentsWriterPerThread dwpt = tryCheckoutForFlush(next, false);
           if (dwpt != null) {
             return dwpt;
           }
@@ -327,6 +315,7 @@ public final class DocumentsWriterFlushControl {
         if (!next.isActive()) {
           continue; 
         }
+        assert next.perThread.deleteQueue == flushingQueue || next.perThread.deleteQueue == documentsWriter.deleteQueue;
         if (next.perThread.deleteQueue != flushingQueue) {
           // this one is already a new DWPT
           continue;
@@ -346,6 +335,7 @@ public final class DocumentsWriterFlushControl {
       }
     }
     synchronized (this) {
+      assert assertBlockedFlushes(flushingQueue);
       flushQueue.addAll(blockedFlushes);
       blockedFlushes.clear();
       flushQueue.addAll(toFlush);
@@ -357,6 +347,7 @@ public final class DocumentsWriterFlushControl {
     assert flushQueue.isEmpty();
     try {
       if (!blockedFlushes.isEmpty()) {
+        assert assertBlockedFlushes(documentsWriter.deleteQueue);
         flushQueue.addAll(blockedFlushes);
         blockedFlushes.clear();
       }
@@ -364,6 +355,14 @@ public final class DocumentsWriterFlushControl {
       fullFlush = false;
     }
   }
+  
+  boolean assertBlockedFlushes(DocumentsWriterDeleteQueue flushingQueue) {
+    Queue<DocumentsWriterPerThread> flushes = this.blockedFlushes;
+    for (DocumentsWriterPerThread documentsWriterPerThread : flushes) {
+      assert documentsWriterPerThread.deleteQueue == flushingQueue;
+    }
+    return true;
+  }
 
   synchronized void abortFullFlushes() {
     try {
diff --git a/lucene/src/java/org/apache/lucene/index/DocumentsWriterPerThread.java b/lucene/src/java/org/apache/lucene/index/DocumentsWriterPerThread.java
index b94fb24f101..65cdc2dc97d 100644
--- a/lucene/src/java/org/apache/lucene/index/DocumentsWriterPerThread.java
+++ b/lucene/src/java/org/apache/lucene/index/DocumentsWriterPerThread.java
@@ -322,6 +322,11 @@ public class DocumentsWriterPerThread {
     numDocsInRAM = 0;
   }
   
+  /**
+   * Prepares this DWPT for flushing. This method will freeze and return the
+   * {@link DocumentsWriterDeleteQueue}s global buffer and apply all pending
+   * deletes to this DWPT.
+   */
   FrozenBufferedDeletes prepareFlush() {
     assert numDocsInRAM > 0;
     final FrozenBufferedDeletes globalDeletes = deleteQueue.freezeGlobalBuffer(deleteSlice);
@@ -330,6 +335,7 @@ public class DocumentsWriterPerThread {
     if (deleteSlice != null) {
       // apply all deletes before we flush and release the delete slice
       deleteSlice.apply(pendingDeletes, numDocsInRAM);
+      assert deleteSlice.isEmpty();
       deleteSlice = null;
     }
     return globalDeletes;
@@ -338,6 +344,7 @@ public class DocumentsWriterPerThread {
   /** Flush all pending docs to a new segment */
   FlushedSegment flush() throws IOException {
     assert numDocsInRAM > 0;
+    assert deleteSlice == null : "all deletes must be applied in prepareFlush";
     flushState = new SegmentWriteState(infoStream, directory, segment, fieldInfos,
         numDocsInRAM, writer.getConfig().getTermIndexInterval(),
         fieldInfos.buildSegmentCodecs(true), pendingDeletes);
diff --git a/lucene/src/test/org/apache/lucene/index/TestFlushByRamOrCountsPolicy.java b/lucene/src/test/org/apache/lucene/index/TestFlushByRamOrCountsPolicy.java
index 2d6861bf771..7560b00b17f 100644
--- a/lucene/src/test/org/apache/lucene/index/TestFlushByRamOrCountsPolicy.java
+++ b/lucene/src/test/org/apache/lucene/index/TestFlushByRamOrCountsPolicy.java
@@ -199,7 +199,6 @@ public class TestFlushByRamOrCountsPolicy extends LuceneTestCase {
     for (int x = 0; x < threads.length; x++) {
       threads[x].join();
     }
-
     assertEquals(" all flushes must be due", 0, flushControl.flushBytes());
     assertEquals(numDocumentsToIndex, writer.numDocs());
     assertEquals(numDocumentsToIndex, writer.maxDoc());
@@ -334,6 +333,7 @@ public class TestFlushByRamOrCountsPolicy extends LuceneTestCase {
             }
           }
         }
+        writer.commit();
       } catch (Throwable ex) {
         throw new RuntimeException(ex);
       }