--- jython/src/org/python/core/packagecache/CachedJarsPackageManager.java	2009-09-26 11:43:16.000000000 -0600
+++ ../jython/src/org/python/core/packagecache/CachedJarsPackageManager.java	2010-04-13 11:57:37.976997583 -0600
@@ -392,7 +392,10 @@
             for (Entry<String,String> kv : zipPackages.entrySet()) {
                 String classes = kv.getValue();
                 ostream.writeUTF(kv.getKey());
-                ostream.writeUTF(classes);
+                // Make sure each package is not larger than 64k
+                for (String part : splitString(classes, 65535)) {
+                    ostream.writeUTF(part);
+                }
             }
             ostream.close();
         } catch (IOException ioe) {
@@ -401,6 +404,45 @@
     }
 
     /**
+     * Split up a string into several chunks based on a certain size
+     * 
+     *  The writeCacheFile method will use the writeUTF method on a
+     *  DataOutputStream which only allows writing 64k chunks, so use 
+     *  this utility method to split it up
+     * 
+     * @param str - The string to split up into chunks
+     * @param maxLength - The max size a string should be
+     * @return - An array of strings, each of which will not be larger than maxLength
+     */
+    protected static String[] splitString(String str, int maxLength) {
+        if (str==null) {
+        	return null;
+        }
+        // Determine number of chunks
+        int len = str.length();
+        int fullChunks = len / maxLength;
+        boolean lastChunkEmpty = fullChunks*maxLength == len;
+        
+        // Setup size of array based on number of chunks
+        int size = fullChunks;
+        if (!lastChunkEmpty) {
+        	size++;
+        }
+        
+        int i = 0;
+        String[] chunks = new String[size];
+        for (i=0; i<fullChunks; i++) {
+            chunks[i] = str.substring(i*maxLength, i*maxLength+maxLength);
+        }
+        
+        if (!lastChunkEmpty) {
+        	chunks[i] = str.substring(i*maxLength, len);
+        }
+        
+        return chunks;
+    }
+
+    /**
      * Initializes cache. Eventually reads back cache index. Index persistent
      * storage is accessed through inOpenIndex().
      */