diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index cd1cb47..42bb29a 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -616,6 +616,10 @@
   directly into the FieldCache arrays during sorting, leading to concurrency
   issues.  (Uwe Schindler, Doron Cohen, Mike McCandless)
 
+* LUCENE-3439: Closing an NRT reader after the writer was closed was
+  incorrectly invoking the DeletionPolicy and (then possibly deleting
+  files) on the closed IndexWriter (Robert Muir, Mike McCandless)
+
 New Features
 
 Optimizations
diff --git a/lucene/src/java/org/apache/lucene/index/DirectoryReader.java b/lucene/src/java/org/apache/lucene/index/DirectoryReader.java
index 3618ac5..ad46bdb 100644
--- a/lucene/src/java/org/apache/lucene/index/DirectoryReader.java
+++ b/lucene/src/java/org/apache/lucene/index/DirectoryReader.java
@@ -364,6 +364,7 @@
 
   @Override
   public final synchronized IndexReader clone(boolean openReadOnly) throws CorruptIndexException, IOException {
+    // doReopen calls ensureOpen
     DirectoryReader newReader = doReopen((SegmentInfos) segmentInfos.clone(), true, openReadOnly);
 
     if (this != newReader) {
@@ -566,7 +567,7 @@
 
   @Override
   public boolean hasDeletions() {
-    // Don't call ensureOpen() here (it could affect performance)
+    ensureOpen();
     return hasDeletions;
   }
 
@@ -843,7 +844,7 @@
     if (writer != null) {
       // Since we just closed, writer may now be able to
       // delete unused files:
-      writer.deleteUnusedFiles();
+      writer.deletePendingFiles();
     }
 
     // throw the first exception
@@ -868,6 +869,7 @@
   
   @Override
   public ReaderContext getTopReaderContext() {
+    ensureOpen();
     return topLevelReaderContext;
   }
   
@@ -887,6 +889,7 @@
 
   @Override
   public int getTermInfosIndexDivisor() {
+    ensureOpen();
     return termInfosIndexDivisor;
   }
 
@@ -897,6 +900,7 @@
    */
   @Override
   public IndexCommit getIndexCommit() throws IOException {
+    ensureOpen();
     return new ReaderCommit(segmentInfos, directory);
   }
 
diff --git a/lucene/src/java/org/apache/lucene/index/FilterIndexReader.java b/lucene/src/java/org/apache/lucene/index/FilterIndexReader.java
index 7fecceb..22b6788 100644
--- a/lucene/src/java/org/apache/lucene/index/FilterIndexReader.java
+++ b/lucene/src/java/org/apache/lucene/index/FilterIndexReader.java
@@ -306,11 +306,13 @@
 
   @Override
   public Directory directory() {
+    ensureOpen();
     return in.directory();
   }
   
   @Override
   public Bits getLiveDocs() {
+    ensureOpen();
     return in.getLiveDocs();
   }
   
@@ -333,7 +335,6 @@
   public void getTermFreqVector(int docNumber, String field, TermVectorMapper mapper) throws IOException {
     ensureOpen();
     in.getTermFreqVector(docNumber, field, mapper);
-
   }
 
   @Override
@@ -362,7 +363,7 @@
 
   @Override
   public boolean hasDeletions() {
-    // Don't call ensureOpen() here (it could affect performance)
+    ensureOpen();
     return in.hasDeletions();
   }
 
@@ -402,14 +403,15 @@
   protected void doDelete(int n) throws  CorruptIndexException, IOException { in.deleteDocument(n); }
   
   @Override
-  protected void doCommit(Map<String,String> commitUserData) throws IOException { in.commit(commitUserData); }
+  protected void doCommit(Map<String,String> commitUserData) throws IOException {
+    in.commit(commitUserData);
+  }
   
   @Override
   protected void doClose() throws IOException {
     in.close();
   }
 
-
   @Override
   public Collection<String> getFieldNames(IndexReader.FieldOption fieldNames) {
     ensureOpen();
@@ -441,11 +443,13 @@
   
   @Override
   public ReaderContext getTopReaderContext() {
+    ensureOpen();
     return in.getTopReaderContext();
   }
 
   @Override
   public Fields fields() throws IOException {
+    ensureOpen();
     return in.fields();
   }
 
@@ -480,6 +484,7 @@
 
   @Override
   public PerDocValues perDocValues() throws IOException {
+    ensureOpen();
     return in.perDocValues();
   }
 }
diff --git a/lucene/src/java/org/apache/lucene/index/IndexReader.java b/lucene/src/java/org/apache/lucene/index/IndexReader.java
index e94b3af..8604c64 100644
--- a/lucene/src/java/org/apache/lucene/index/IndexReader.java
+++ b/lucene/src/java/org/apache/lucene/index/IndexReader.java
@@ -115,6 +115,7 @@
    *
    * @lucene.experimental */
   public void addReaderFinishedListener(ReaderFinishedListener listener) {
+    ensureOpen();
     readerFinishedListeners.add(listener);
   }
 
@@ -122,6 +123,7 @@
    *
    * @lucene.experimental */
   public void removeReaderFinishedListener(ReaderFinishedListener listener) {
+    ensureOpen();
     readerFinishedListeners.remove(listener);
   }
 
@@ -172,7 +174,7 @@
     DOC_VALUES
   }
 
-  private boolean closed;
+  private volatile boolean closed;
   protected boolean hasChanges;
   
   private final AtomicInteger refCount = new AtomicInteger();
@@ -236,7 +238,8 @@
    */
   public void decRef() throws IOException {
     ensureOpen();
-    if (refCount.getAndDecrement() == 1) {
+    final int rc = refCount.getAndDecrement();
+    if (rc == 1) {
       boolean success = false;
       try {
         commit();
@@ -249,6 +252,8 @@
         }
       }
       readerFinished();
+    } else if (rc <= 0) {
+      throw new IllegalStateException("too many decRef calls: refCount was " + rc + " before decrement");
     }
   }
   
@@ -1330,6 +1335,7 @@
    * @throws IOException if there is a low-level IO error
    */
   public final synchronized void commit(Map<String, String> commitUserData) throws IOException {
+    // Don't can ensureOpen since we commit() on close
     doCommit(commitUserData);
     hasChanges = false;
   }
@@ -1499,6 +1505,7 @@
    *  corruption for other readers (like DirectoryReader obtained
    *  through {@link #open}. Use the parent reader directly. */
   public IndexReader[] getSequentialSubReaders() {
+    ensureOpen();
     return null;
   }
   
@@ -1531,6 +1538,8 @@
 
   /** Expert */
   public Object getCoreCacheKey() {
+    // Don't can ensureOpen since FC calls this (to evict)
+    // on close
     return this;
   }
 
@@ -1569,6 +1578,7 @@
   }
   
   public final IndexDocValues docValues(String field) throws IOException {
+    ensureOpen();
     final PerDocValues perDoc = perDocValues();
     if (perDoc == null) {
       return null;
@@ -1580,11 +1590,13 @@
 
   /** @lucene.internal */
   void storeFields(Fields fields) {
+    ensureOpen();
     this.fields = fields;
   }
 
   /** @lucene.internal */
   Fields retrieveFields() {
+    ensureOpen();
     return fields;
   }
   
@@ -1592,11 +1604,13 @@
   
   /** @lucene.internal */
   void storePerDoc(PerDocValues perDocValues) {
+    ensureOpen();
     this.perDocValues = perDocValues;
   }
 
   /** @lucene.internal */
   PerDocValues retrievePerDoc() {
+    ensureOpen();
     return perDocValues;
   }  
   
diff --git a/lucene/src/java/org/apache/lucene/index/IndexWriter.java b/lucene/src/java/org/apache/lucene/index/IndexWriter.java
index 87be6b5..f3fa1dc 100644
--- a/lucene/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/lucene/src/java/org/apache/lucene/index/IndexWriter.java
@@ -233,8 +233,8 @@
 
   private Lock writeLock;
 
-  private boolean closed;
-  private boolean closing;
+  private volatile boolean closed;
+  private volatile boolean closing;
 
   // Holds all SegmentInfo instances currently involved in
   // merges
@@ -758,6 +758,7 @@
    * delCount is returned.
    */
   public int numDeletedDocs(SegmentInfo info) throws IOException {
+    ensureOpen(false);
     SegmentReader reader = readerPool.getIfExists(info);
     try {
       if (reader != null) {
@@ -960,6 +961,7 @@
    * IndexWriterConfig} for details.
    */
   public IndexWriterConfig getConfig() {
+    ensureOpen(false);
     return config;
   }
 
@@ -1204,6 +1206,7 @@
    *  not counting deletions.
    *  @see #numDocs */
   public synchronized int maxDoc() {
+    ensureOpen();
     int count;
     if (docWriter != null)
       count = docWriter.getNumDocs();
@@ -1221,6 +1224,7 @@
    *  counted you should call {@link #commit()} first.
    *  @see #numDocs */
   public synchronized int numDocs() throws IOException {
+    ensureOpen();
     int count;
     if (docWriter != null)
       count = docWriter.getNumDocs();
@@ -1960,6 +1964,7 @@
   }
 
   private final void maybeMerge(int maxNumSegmentsOptimize, boolean optimize) throws CorruptIndexException, IOException {
+    ensureOpen(false);
     updatePendingMerges(maxNumSegmentsOptimize, optimize);
     mergeScheduler.merge(this);
   }
@@ -2143,6 +2148,7 @@
    *    {@link MergePolicy.MergeAbortedException}s.
    */
   public synchronized void deleteAll() throws IOException {
+    ensureOpen();
     try {
 
       // Abort any running merges
@@ -2229,6 +2235,7 @@
    *    will have completed once this method completes.</p>
    */
   public synchronized void waitForMerges() {
+    ensureOpen(false);
     if (infoStream != null) {
       message("waitForMerges");
     }
@@ -2736,6 +2743,7 @@
    *  index to commit.
    */
   public final void prepareCommit(Map<String,String> commitUserData) throws CorruptIndexException, IOException {
+    ensureOpen(false);
 
     if (infoStream != null) {
       message("prepareCommit: flush");
@@ -4098,10 +4106,16 @@
    *  be deleted the next time commit() is called.
    */
   public synchronized void deleteUnusedFiles() throws IOException {
+    ensureOpen(false);
     deleter.deletePendingFiles();
     deleter.revisitPolicy();
   }
 
+  // Called by DirectoryReader.doClose
+  synchronized void deletePendingFiles() throws IOException {
+    deleter.deletePendingFiles();
+  }
+
   /**
    * Sets the {@link PayloadProcessorProvider} to use when merging payloads.
    * Note that the given <code>pcp</code> will be invoked for every segment that
@@ -4121,6 +4135,7 @@
    * {@link #optimize}, you can call {@link #waitForMerges()} before.
    */
   public void setPayloadProcessorProvider(PayloadProcessorProvider pcp) {
+    ensureOpen();
     payloadProcessorProvider = pcp;
   }
 
@@ -4129,6 +4144,7 @@
    * merges to process payloads.
    */
   public PayloadProcessorProvider getPayloadProcessorProvider() {
+    ensureOpen();
     return payloadProcessorProvider;
   }
 }
diff --git a/lucene/src/java/org/apache/lucene/index/MultiReader.java b/lucene/src/java/org/apache/lucene/index/MultiReader.java
index 72062cf..dfdc0db 100644
--- a/lucene/src/java/org/apache/lucene/index/MultiReader.java
+++ b/lucene/src/java/org/apache/lucene/index/MultiReader.java
@@ -233,6 +233,7 @@
 
   @Override
   public boolean isOptimized() {
+    ensureOpen();
     return false;
   }
   
@@ -265,7 +266,7 @@
 
   @Override
   public boolean hasDeletions() {
-    // Don't call ensureOpen() here (it could affect performance)
+    ensureOpen();
     return hasDeletions;
   }
 
@@ -358,6 +359,7 @@
    */
   @Override
   public boolean isCurrent() throws CorruptIndexException, IOException {
+    ensureOpen();
     for (int i = 0; i < subReaders.length; i++) {
       if (!subReaders[i].isCurrent()) {
         return false;
@@ -383,6 +385,7 @@
   
   @Override
   public ReaderContext getTopReaderContext() {
+    ensureOpen();
     return topLevelContext;
   }
 
diff --git a/lucene/src/java/org/apache/lucene/index/ParallelReader.java b/lucene/src/java/org/apache/lucene/index/ParallelReader.java
index 22c006c..df4b731 100644
--- a/lucene/src/java/org/apache/lucene/index/ParallelReader.java
+++ b/lucene/src/java/org/apache/lucene/index/ParallelReader.java
@@ -204,16 +204,19 @@
   
   @Override
   public Bits getLiveDocs() {
+    ensureOpen();
     return MultiFields.getLiveDocs(readers.get(0));
   }
 
   @Override
   public Fields fields() {
+    ensureOpen();
     return fields;
   }
   
   @Override
   public synchronized Object clone() {
+    // doReopen calls ensureOpen
     try {
       return doReopen(true);
     } catch (Exception ex) {
@@ -242,6 +245,7 @@
    */
   @Override
   public synchronized IndexReader reopen() throws CorruptIndexException, IOException {
+    // doReopen calls ensureOpen
     return doReopen(false);
   }
     
@@ -325,7 +329,7 @@
 
   @Override
   public boolean hasDeletions() {
-    // Don't call ensureOpen() here (it could affect performance)
+    ensureOpen();
     return hasDeletions;
   }
 
@@ -461,6 +465,7 @@
    */
   @Override
   public boolean isCurrent() throws CorruptIndexException, IOException {
+    ensureOpen();
     for (final IndexReader reader : readers) {
       if (!reader.isCurrent()) {
         return false;
@@ -476,6 +481,7 @@
    */
   @Override
   public boolean isOptimized() {
+    ensureOpen();
     for (final IndexReader reader : readers) {
       if (!reader.isOptimized()) {
         return false;
@@ -527,8 +533,10 @@
     }
     return fieldSet;
   }
+
   @Override
   public ReaderContext getTopReaderContext() {
+    ensureOpen();
     return topLevelReaderContext;
   }
 
@@ -550,6 +558,7 @@
 
   @Override
   public PerDocValues perDocValues() throws IOException {
+    ensureOpen();
     return perDocs;
   }
   
diff --git a/lucene/src/java/org/apache/lucene/index/SegmentReader.java b/lucene/src/java/org/apache/lucene/index/SegmentReader.java
index 622e45e..10f1cf9 100644
--- a/lucene/src/java/org/apache/lucene/index/SegmentReader.java
+++ b/lucene/src/java/org/apache/lucene/index/SegmentReader.java
@@ -135,6 +135,7 @@
 
   @Override
   public Bits getLiveDocs() {
+    ensureOpen();
     return liveDocs;
   }
 
@@ -184,6 +185,7 @@
    * @return New BitVector
    */
   protected BitVector cloneDeletedDocs(BitVector bv) {
+    ensureOpen();
     return (BitVector)bv.clone();
   }
 
@@ -214,6 +216,7 @@
   }
 
   synchronized SegmentReader reopenSegment(SegmentInfo si, boolean doClone, boolean openReadOnly) throws CorruptIndexException, IOException {
+    ensureOpen();
     boolean deletionsUpToDate = (this.si.hasDeletions() == si.hasDeletions()) 
                                   && (!si.hasDeletions() || this.si.getDelFileName().equals(si.getDelFileName()));
     boolean normsUpToDate = true;
@@ -463,13 +466,13 @@
 
   @Override
   public Fields fields() throws IOException {
+    ensureOpen();
     return core.fields;
   }
 
   @Override
   public int docFreq(String field, BytesRef term) throws IOException {
     ensureOpen();
-
     Terms terms = core.fields.terms(field);
     if (terms != null) {
       return terms.docFreq(term);
@@ -758,6 +761,7 @@
   
   @Override
   public ReaderContext getTopReaderContext() {
+    ensureOpen();
     return readerContext;
   }
 
@@ -835,6 +839,7 @@
   
   @Override
   public PerDocValues perDocValues() throws IOException {
+    ensureOpen();
     return core.perDocProducer;
   }
 }
diff --git a/lucene/src/java/org/apache/lucene/index/SlowMultiReaderWrapper.java b/lucene/src/java/org/apache/lucene/index/SlowMultiReaderWrapper.java
index e9432bd..39e15a6 100644
--- a/lucene/src/java/org/apache/lucene/index/SlowMultiReaderWrapper.java
+++ b/lucene/src/java/org/apache/lucene/index/SlowMultiReaderWrapper.java
@@ -67,16 +67,19 @@
 
   @Override
   public Fields fields() throws IOException {
+    ensureOpen();
     return MultiFields.getFields(in);
   }
 
   @Override
   public PerDocValues perDocValues() throws IOException {
+    ensureOpen();
     return MultiPerDocValues.getPerDocs(in);
   }
 
   @Override
   public Bits getLiveDocs() {
+    ensureOpen();
     return MultiFields.getLiveDocs(in);
   }
   
@@ -103,6 +106,7 @@
   
   @Override
   public ReaderContext getTopReaderContext() {
+    ensureOpen();
     return readerContext;
   }
   
diff --git a/lucene/src/test/org/apache/lucene/index/TestIndexReader.java b/lucene/src/test/org/apache/lucene/index/TestIndexReader.java
index 1e3269c..c71e6cb 100644
--- a/lucene/src/test/org/apache/lucene/index/TestIndexReader.java
+++ b/lucene/src/test/org/apache/lucene/index/TestIndexReader.java
@@ -73,18 +73,16 @@
       IndexReader r = IndexReader.open(d, false);
       r.deleteDocument(5);
       r.flush(commitUserData);
+      IndexCommit c = r.getIndexCommit();
       r.close();
       
       SegmentInfos sis = new SegmentInfos();
       sis.read(d);
       IndexReader r2 = IndexReader.open(d, false);
-      IndexCommit c = r.getIndexCommit();
       assertEquals(c.getUserData(), commitUserData);
 
       assertEquals(sis.getCurrentSegmentFileName(), c.getSegmentsFileName());
 
-      assertTrue(c.equals(r.getIndexCommit()));
-
       // Change the index
       writer = new IndexWriter(d, newIndexWriterConfig(TEST_VERSION_CURRENT,
           new MockAnalyzer(random)).setOpenMode(
diff --git a/lucene/src/test/org/apache/lucene/index/TestReaderClosed.java b/lucene/src/test/org/apache/lucene/index/TestReaderClosed.java
new file mode 100644
index 0000000..a870123
--- /dev/null
+++ b/lucene/src/test/org/apache/lucene/index/TestReaderClosed.java
@@ -0,0 +1,79 @@
+package org.apache.lucene.index;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.apache.lucene.analysis.MockAnalyzer;
+import org.apache.lucene.analysis.MockTokenizer;
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.StringField;
+import org.apache.lucene.index.codecs.CodecProvider;
+import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.TermRangeQuery;
+import org.apache.lucene.store.AlreadyClosedException;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.util.LuceneTestCase;
+import org.apache.lucene.util._TestUtil;
+
+public class TestReaderClosed extends LuceneTestCase {
+  private IndexSearcher searcher;
+  private IndexReader reader;
+  private Directory dir;
+
+  @Override
+  public void setUp() throws Exception {
+    super.setUp();
+    dir = newDirectory();
+    RandomIndexWriter writer = new RandomIndexWriter(random, dir, 
+        newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random, MockTokenizer.KEYWORD, false))
+        .setMaxBufferedDocs(_TestUtil.nextInt(random, 50, 1000)));
+    
+    Document doc = new Document();
+    Field field = newField("field", "", StringField.TYPE_UNSTORED);
+    doc.add(field);
+
+    // we generate aweful prefixes: good for testing.
+    // but for preflex codec, the test can be very slow, so use less iterations.
+    final String codec = CodecProvider.getDefault().getFieldCodec("field");
+    int num = codec.equals("PreFlex") ? 200 * RANDOM_MULTIPLIER : atLeast(1000);
+    for (int i = 0; i < num; i++) {
+      field.setValue(_TestUtil.randomUnicodeString(random, 10));
+      writer.addDocument(doc);
+    }
+    reader = writer.getReader();
+    searcher = newSearcher(reader);
+    writer.close();
+  }
+  
+  public void test() throws Exception {
+    TermRangeQuery query = TermRangeQuery.newStringRange("field", "a", "z", true, true);
+    searcher.search(query, 5);
+    searcher.close();
+    reader.close();
+    try {
+      searcher.search(query, 5);
+    } catch (AlreadyClosedException ace) {
+      // expected
+    }
+  }
+  
+  public void tearDown() throws Exception {
+    dir.close();
+    super.tearDown();
+  }
+}