--- jsr166/src/jsr166e/Striped64.java	2013/01/14 01:59:15	1.8
+++ jsr166/src/jsr166e/Striped64.java	2014/05/04 22:38:19	1.9
@@ -111,32 +111,17 @@ abstract class Striped64 extends Number
     }
 
     /**
-     * Holder for the thread-local hash code. The code is initially
-     * random, but may be set to a different value upon collisions.
+     * ThreadLocal holding a single-slot int array holding hash code.
+     * Unlike the JDK8 version of this class, we use a suboptimal
+     * int[] representation to avoid introducing a new type that can
+     * impede class-unloading when ThreadLocals are not removed.
      */
-    static final class HashCode {
-        static final Random rng = new Random();
-        int code;
-        HashCode() {
-            int h = rng.nextInt(); // Avoid zero to allow xorShift rehash
-            code = (h == 0) ? 1 : h;
-        }
-    }
+    static final ThreadLocal<int[]> threadHashCode = new ThreadLocal<int[]>();
 
     /**
-     * The corresponding ThreadLocal class
+     * Generator of new random hash codes
      */
-    static final class ThreadHashCode extends ThreadLocal<HashCode> {
-        public HashCode initialValue() { return new HashCode(); }
-    }
-
-    /**
-     * Static per-thread hash codes. Shared across all instances to
-     * reduce ThreadLocal pollution and because adjustments due to
-     * collisions in one table are likely to be appropriate for
-     * others.
-     */
-    static final ThreadHashCode threadHashCode = new ThreadHashCode();
+    static final Random rng = new Random();
 
     /** Number of CPUS, to place bound on table size */
     static final int NCPU = Runtime.getRuntime().availableProcessors();
@@ -199,8 +184,15 @@ abstract class Striped64 extends Number
      * @param hc the hash code holder
      * @param wasUncontended false if CAS failed before call
      */
-    final void retryUpdate(long x, HashCode hc, boolean wasUncontended) {
-        int h = hc.code;
+    final void retryUpdate(long x, int[] hc, boolean wasUncontended) {
+        int h;
+        if (hc == null) {
+            threadHashCode.set(hc = new int[1]); // Initialize randomly
+            int r = rng.nextInt(); // Avoid zero to allow xorShift rehash
+            h = hc[0] = (r == 0) ? 1 : r;
+        }
+        else
+            h = hc[0];
         boolean collide = false;                // True if last slot nonempty
         for (;;) {
             Cell[] as; Cell a; int n; long v;
@@ -253,6 +245,7 @@ abstract class Striped64 extends Number
                 h ^= h << 13;                   // Rehash
                 h ^= h >>> 17;
                 h ^= h << 5;
+                hc[0] = h;                      // Record index for next time
             }
             else if (busy == 0 && cells == as && casBusy()) {
                 boolean init = false;
@@ -272,7 +265,6 @@ abstract class Striped64 extends Number
             else if (casBase(v = base, fn(v, x)))
                 break;                          // Fall back on using base
         }
-        hc.code = h;                            // Record index for next time
     }