Index: lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java	(revision 1364784)
+++ lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java	(working copy)
@@ -243,27 +243,34 @@
     sync();
   }
 
-  /** Wait for any running merge threads to finish */
+  /** Wait for any running merge threads to finish. This call is not interruptible as used by {@link #close()}. */
   public void sync() {
-    while (true) {
-      MergeThread toSync = null;
-      synchronized (this) {
-        for (MergeThread t : mergeThreads) {
-          if (t.isAlive()) {
-            toSync = t;
-            break;
+    boolean interrupted = Thread.interrupted();
+    try {
+      while (true) {
+        MergeThread toSync = null;
+        synchronized (this) {
+          for (MergeThread t : mergeThreads) {
+            if (t.isAlive()) {
+              toSync = t;
+              break;
+            }
           }
         }
-      }
-      if (toSync != null) {
-        try {
-          toSync.join();
-        } catch (InterruptedException ie) {
-          throw new ThreadInterruptedException(ie);
+        if (toSync != null) {
+          try {
+            toSync.join();
+          } catch (InterruptedException ie) {
+            // ignore this Exception, we will retry until all threads are dead
+            interrupted = true;
+          }
+        } else {
+          break;
         }
-      } else {
-        break;
       }
+    } finally {
+      // finally, restore original interrupt status:
+      if (interrupted) Thread.currentThread().interrupt();
     }
   }
 
Index: lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/index/IndexWriter.java	(revision 1364784)
+++ lucene/core/src/java/org/apache/lucene/index/IndexWriter.java	(working copy)
@@ -842,7 +842,7 @@
         if (hitOOM) {
           rollbackInternal();
         } else {
-          closeInternal(waitForMerges, !hitOOM);
+          closeInternal(waitForMerges, true);
         }
       }
     }
@@ -870,7 +870,7 @@
   }
 
   private void closeInternal(boolean waitForMerges, boolean doFlush) throws IOException {
-
+    boolean interrupted = Thread.interrupted();
     try {
 
       if (pendingCommit != null) {
@@ -891,17 +891,35 @@
         docWriter.abort(); // already closed
       }
 
-      if (waitForMerges)
-        // Give merge scheduler last chance to run, in case
-        // any pending merges are waiting:
-        mergeScheduler.merge(this);
-
+      if (waitForMerges) {
+        try {
+          // Give merge scheduler last chance to run, in case
+          // any pending merges are waiting:
+          mergeScheduler.merge(this);
+        } catch (ThreadInterruptedException tie) {
+          // ignore any interruption, does not matter
+          interrupted = true;
+        }
+      }
+      
       mergePolicy.close();
 
       synchronized(this) {
-        finishMerges(waitForMerges);
+        for (;;) {
+          try {
+            finishMerges(waitForMerges && !interrupted);
+            break;
+          } catch (ThreadInterruptedException tie) {
+            // by setting the interrupted status, the
+            // next call to finishMerges will pass false,
+            // so it will not wait
+            interrupted = true;
+          }
+        }
         stopMerges = true;
       }
+      
+      // shutdown scheduler and all threads (this call is not interruptible):
       mergeScheduler.close();
 
       if (infoStream.isEnabled("IW")) {
@@ -943,6 +961,8 @@
           }
         }
       }
+      // finally, restore original interrupt status:
+      if (interrupted) Thread.currentThread().interrupt();
     }
   }
 
Index: lucene/core/src/java/org/apache/lucene/index/MergeScheduler.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/index/MergeScheduler.java	(revision 1364784)
+++ lucene/core/src/java/org/apache/lucene/index/MergeScheduler.java	(working copy)
@@ -17,6 +17,7 @@
  * limitations under the License.
  */
 
+import java.io.Closeable;
 import java.io.IOException;
 
 /** <p>Expert: {@link IndexWriter} uses an instance
@@ -26,7 +27,7 @@
  *
  * @lucene.experimental
 */
-public abstract class MergeScheduler {
+public abstract class MergeScheduler implements Closeable {
 
   /** Run the merges provided by {@link IndexWriter#getNextMerge()}. */
   public abstract void merge(IndexWriter writer) throws IOException;