diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index b9a13c48007..ae37ffdd1e5 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -191,6 +191,11 @@ Bug Fixes
   inside ConstantScoreQuery, which now rewrites to a query removing the
   obsolete QueryWrapperFilter.  (Adrien Grand, Uwe Schindler)
 
+* LUCENE-5330: IndexWriter didn't process all internal events on 
+  #getReader(), #close() and #rollback() which causes files to be
+  deleted at a later point in time. This could cause short-term disk
+  pollution or OOM if in-memory directories are used. (Simon Willnauer)
+
 API Changes:
 
 * LUCENE-5222: Add SortField.needsScores(). Previously it was not possible
diff --git a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
index a684c42b4eb..453134f7585 100644
--- a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
@@ -394,6 +394,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit{
           }
           // Done: finish the full flush!
           docWriter.finishFullFlush(success);
+          processEvents(false, true);
           doAfterFlush();
         }
       }
@@ -929,6 +930,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit{
           closeInternal(waitForMerges, true);
         }
       }
+      assert eventQueue.isEmpty();
     }
   }
 
@@ -1061,6 +1063,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit{
       }
       // finally, restore interrupt status:
       if (interrupted) Thread.currentThread().interrupt();
+      processEvents(false, true);
     }
   }
 
@@ -2020,6 +2023,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit{
         rollbackInternal();
       }
     }
+    assert eventQueue.isEmpty() : eventQueue;
   }
 
   private void rollbackInternal() throws IOException {
diff --git a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
index 4f0bc600797..0046ea651b9 100644
--- a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
+++ b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
@@ -1321,6 +1321,7 @@ public class TestIndexWriter extends LuceneTestCase {
     dir.close();
   }
 
+
   public void testDeleteUnusedFiles() throws Exception {
     for(int iter=0;iter<2;iter++) {
       Directory dir = newMockDirectory(); // relies on windows semantics
@@ -1350,7 +1351,19 @@ public class TestIndexWriter extends LuceneTestCase {
       }
 
       List<String> files = Arrays.asList(dir.listAll());
+
       assertTrue(files.contains("_0.cfs"));
+      assertTrue(files.contains("_0.cfe"));
+      assertTrue(files.contains("_0.si"));
+      if (iter == 1) {
+        // we run a full commit so there should be a segments file etc.
+        assertTrue(files.contains("segments_1"));
+        assertTrue(files.contains("segments.gen"));
+        assertEquals(files.toString(), files.size(), 5);
+      } else {
+        // this is an NRT reopen - no segments files yet
+        assertEquals(files.toString(), files.size(), 3);
+      }
       w.addDocument(doc);
       w.forceMerge(1);
       if (iter == 1) {