diff -r 2349e7ad1056 lucene/CHANGES.txt
--- a/lucene/CHANGES.txt	Tue Sep 21 05:04:19 2010 +0000
+++ b/lucene/CHANGES.txt	Tue Sep 21 12:21:08 2010 -0400
@@ -529,6 +529,10 @@
 * LUCENE-2650: Added extra safety to MMapIndexInput clones to prevent accessing
   an unmapped buffer if the input is closed (Mike McCandless, Uwe Schindler, Robert Muir) 
 
+* LUCENE-2658: Exceptions while processing term vectors enabled for multiple
+  fields could lead to invalid ArrayIndexOutOfBoundsExceptions.
+  (Robert Muir, Mike McCandless)
+
 New features
 
 * LUCENE-2128: Parallelized fetching document frequencies during weight
diff -r 2349e7ad1056 lucene/src/java/org/apache/lucene/index/TermVectorsTermsWriterPerField.java
--- a/lucene/src/java/org/apache/lucene/index/TermVectorsTermsWriterPerField.java	Tue Sep 21 05:04:19 2010 +0000
+++ b/lucene/src/java/org/apache/lucene/index/TermVectorsTermsWriterPerField.java	Tue Sep 21 12:21:08 2010 -0400
@@ -76,14 +76,16 @@
         assert perThread.doc.numVectorFields == 0;
         assert 0 == perThread.doc.perDocTvf.length();
         assert 0 == perThread.doc.perDocTvf.getFilePointer();
-      } else {
-        assert perThread.doc.docID == docState.docID;
+      }
 
-        if (termsHashPerField.numPostings != 0)
-          // Only necessary if previous doc hit a
-          // non-aborting exception while writing vectors in
-          // this field:
-          termsHashPerField.reset();
+      assert perThread.doc.docID == docState.docID;
+
+      if (termsHashPerField.numPostings != 0) {
+        // Only necessary if previous doc hit a
+        // non-aborting exception while writing vectors in
+        // this field:
+        termsHashPerField.reset();
+        perThread.termsHashPerThread.reset(false);
       }
     }
 
@@ -98,7 +100,7 @@
   /** Called once per field per document if term vectors
    *  are enabled, to write the vectors to
    *  RAMOutputStream, which is then quickly flushed to
-   *  * the real term vectors files in the Directory. */
+   *  the real term vectors files in the Directory. */
   @Override
   void finish() throws IOException {
 
@@ -188,6 +190,12 @@
     }
 
     termsHashPerField.reset();
+
+    // NOTE: we clear, per-field, at the thread level,
+    // because term vectors fully write themselves on each
+    // field; this saves RAM (eg if large doc has two large
+    // fields w/ term vectors on) because we recycle/reuse
+    // all RAM after each field:
     perThread.termsHashPerThread.reset(false);
   }
 
diff -r 2349e7ad1056 lucene/src/test/org/apache/lucene/index/TestIndexWriterExceptions.java
--- a/lucene/src/test/org/apache/lucene/index/TestIndexWriterExceptions.java	Tue Sep 21 05:04:19 2010 +0000
+++ b/lucene/src/test/org/apache/lucene/index/TestIndexWriterExceptions.java	Tue Sep 21 12:21:08 2010 -0400
@@ -71,7 +71,7 @@
           writer.updateDocument(idTerm, doc);
         } catch (RuntimeException re) {
           if (VERBOSE) {
-            System.out.println("EXC: ");
+            System.out.println(Thread.currentThread().getName() + ": EXC: ");
             re.printStackTrace(System.out);
           }
           try {