Index: src/java/org/apache/lucene/index/IndexWriter.java
===================================================================
--- src/java/org/apache/lucene/index/IndexWriter.java	(revision 768415)
+++ src/java/org/apache/lucene/index/IndexWriter.java	(working copy)
@@ -2043,7 +2043,8 @@
 
       // Only allow a new merge to be triggered if we are
       // going to wait for merges:
-      flush(waitForMerges, true, true);
+      if (!hitOOM)
+        flush(waitForMerges, true, true);
 
       if (waitForMerges)
         // Give merge scheduler last chance to run, in case
@@ -2708,6 +2709,10 @@
     if (doWait) {
       synchronized(this) {
         while(true) {
+
+          if (hitOOM)
+            throw new IllegalStateException("this writer hit an OutOfMemoryError; cannot complete optimize");
+
           if (mergeExceptions.size() > 0) {
             // Forward any exceptions in background merge
             // threads to the current thread:
@@ -2795,6 +2800,10 @@
         boolean running = true;
         while(running) {
 
+          if (hitOOM) {
+            throw new IllegalStateException("this writer hit an OutOfMemoryError; cannot complete expungeDeletes");
+          }
+
           // Check each merge that MergePolicy asked us to
           // do, to see if any of them are still running and
           // if any of them have hit an exception.
@@ -2883,6 +2892,10 @@
     if (stopMerges)
       return;
 
+    // Do not start new merges if we've hit OOME
+    if (hitOOM)
+      return;
+
     final MergePolicy.MergeSpecification spec;
     if (optimize) {
       spec = mergePolicy.findMergesForOptimize(segmentInfos, this, maxNumSegmentsOptimize, segmentsToOptimize);
@@ -3981,6 +3994,9 @@
   // even while a flush is happening
   private synchronized final boolean doFlush(boolean flushDocStores, boolean flushDeletes) throws CorruptIndexException, IOException {
 
+    if (hitOOM)
+      throw new IllegalStateException("this writer hit an OutOfMemoryError; cannot flush");
+
     ensureOpen(false);
 
     assert testPoint("startDoFlush");
@@ -4261,7 +4277,7 @@
     assert testPoint("startCommitMerge");
 
     if (hitOOM)
-      return false;
+      throw new IllegalStateException("this writer hit an OutOfMemoryError; cannot complete merge");
 
     if (infoStream != null)
       message("commitMerge: " + merge.segString(directory) + " index=" + segString());
@@ -4477,6 +4493,9 @@
     assert merge.registerDone;
     assert !merge.optimize || merge.maxNumSegmentsOptimize > 0;
 
+    if (hitOOM)
+      throw new IllegalStateException("this writer hit an OutOfMemoryError; cannot merge");
+
     if (merge.info != null)
       // mergeInit already done
       return;