diff -r 700ec2a5d680 -r c90a67d75c9f jdk/src/share/classes/sun/nio/ch/Util.java
--- a/jdk/src/share/classes/sun/nio/ch/Util.java	Tue Aug 10 13:15:40 2010 -0700
+++ b/jdk/src/share/classes/sun/nio/ch/Util.java	Thu Aug 12 19:53:25 2010 +0100
@@ -41,67 +41,180 @@
 
 class Util {
 
-
     // -- Caches --
 
     // The number of temp buffers in our pool
-    private static final int TEMP_BUF_POOL_SIZE = 3;
+    private static final int TEMP_BUF_POOL_SIZE = 8;
 
-    // Per-thread soft cache of the last temporary direct buffer
-    private static ThreadLocal<SoftReference<ByteBuffer>>[] bufferPool;
+    // Per-thread cache of temporary direct buffers
+    private static ThreadLocal<BufferCache> bufferCache =
+        new ThreadLocal<BufferCache>()
+    {
+        @Override
+        protected BufferCache initialValue() {
+            return new BufferCache();
+        }
+    };
+
+    /**
+     * A simple cache of direct buffers.
+     */
+    private static class BufferCache {
+        // the array of buffers
+        private ByteBuffer[] buffers;
 
-    @SuppressWarnings("unchecked")
-    static ThreadLocal<SoftReference<ByteBuffer>>[] createThreadLocalBufferPool() {
-        return new ThreadLocal[TEMP_BUF_POOL_SIZE];
-    }
+        // the number of buffers in the cache
+        private int count;
+
+        // the index of the first valid buffer (undefined if count == 0)
+        private int start;
+
+        private int next(int i) {
+            return (i + 1) % TEMP_BUF_POOL_SIZE;
+        }
+
+        BufferCache() {
+            buffers = new ByteBuffer[TEMP_BUF_POOL_SIZE];
+        }
+
+        /**
+         * Removes and returns a buffer from the cache of at least the given
+         * size (or null if no suitable buffer is found).
+         */
+        ByteBuffer get(int size) {
+            if (count == 0)
+                return null;  // cache is empty
 
-    static {
-        bufferPool = createThreadLocalBufferPool();
-        for (int i=0; i<TEMP_BUF_POOL_SIZE; i++)
-            bufferPool[i] = new ThreadLocal<SoftReference<ByteBuffer>>();
-    }
+            ByteBuffer[] buffers = this.buffers;
 
-    static ByteBuffer getTemporaryDirectBuffer(int size) {
-        ByteBuffer buf = null;
-        // Grab a buffer if available
-        for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
-            SoftReference<ByteBuffer> ref = bufferPool[i].get();
-            if ((ref != null) && ((buf = ref.get()) != null) &&
-                (buf.capacity() >= size)) {
-                buf.rewind();
-                buf.limit(size);
-                bufferPool[i].set(null);
-                return buf;
+            // search for suitable buffer (often the first buffer will do)
+            ByteBuffer buf = buffers[start];
+            if (buf.capacity() < size) {
+                buf = null;
+                int i = start;
+                while ((i = next(i)) != start) {
+                    ByteBuffer bb = buffers[i];
+                    if (bb == null)
+                        break;
+                    if (bb.capacity() >= size) {
+                        buf = bb;
+                        break;
+                    }
+                }
+                if (buf == null)
+                    return null;
+                // move first element to here to avoid re-packing
+                buffers[i] = buffers[start];
+            }
+
+            // remove first element
+            buffers[start] = null;
+            start = next(start);
+            count--;
+
+            // prepare the buffer and return it
+            buf.rewind();
+            buf.limit(size);
+            return buf;
+        }
+
+        boolean offerFirst(ByteBuffer buf) {
+            if (count >= TEMP_BUF_POOL_SIZE) {
+                return false;
+            } else {
+                start = (start + TEMP_BUF_POOL_SIZE - 1) % TEMP_BUF_POOL_SIZE;
+                buffers[start] = buf;
+                count++;
+                return true;
             }
         }
 
-        // Make a new one
-        return ByteBuffer.allocateDirect(size);
-    }
-
-    static void releaseTemporaryDirectBuffer(ByteBuffer buf) {
-        if (buf == null)
-            return;
-        // Put it in an empty slot if such exists
-        for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
-            SoftReference<ByteBuffer> ref = bufferPool[i].get();
-            if ((ref == null) || (ref.get() == null)) {
-                bufferPool[i].set(new SoftReference<ByteBuffer>(buf));
-                return;
-            }
-        }
-        // Otherwise replace a smaller one in the cache if such exists
-        for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
-            SoftReference<ByteBuffer> ref = bufferPool[i].get();
-            ByteBuffer inCacheBuf = ref.get();
-            if ((inCacheBuf == null) || (buf.capacity() > inCacheBuf.capacity())) {
-                bufferPool[i].set(new SoftReference<ByteBuffer>(buf));
-                return;
+        boolean offerLast(ByteBuffer buf) {
+            if (count >= TEMP_BUF_POOL_SIZE) {
+                return false;
+            } else {
+                int next = (start + count) % TEMP_BUF_POOL_SIZE;
+                buffers[next] = buf;
+                count++;
+                return true;
             }
         }
 
-        // release memory
-       ((DirectBuffer)buf).cleaner().clean();
+        boolean isEmpty() {
+            return count == 0;
+        }
+
+        ByteBuffer removeFirst() {
+            assert count > 0;
+            ByteBuffer buf = buffers[start];
+            buffers[start] = null;
+            start = next(start);
+            count--;
+            return buf;
+        }
+    }
+
+    /**
+     * Returns a temporary buffer of at least the given size
+     */
+    static ByteBuffer getTemporaryDirectBuffer(int size) {
+        BufferCache cache = bufferCache.get();
+        ByteBuffer buf = cache.get(size);
+        if (buf != null) {
+            return buf;
+        } else {
+            // No suitable buffer in the cache so we need to allocate a new
+            // one. To avoid the cache growing then we remove the first
+            // buffer from the cache and free it.
+            if (!cache.isEmpty()) {
+                buf = cache.removeFirst();
+                free(buf);
+            }
+            return ByteBuffer.allocateDirect(size);
+        }
+    }
+
+    /**
+     * Releases a temporary buffer by returning to the cache or freeing it.
+     */
+    static void releaseTemporaryDirectBuffer(ByteBuffer buf) {
+        offerFirstTemporaryDirectBuffer(buf);
+    }
+
+    /**
+     * Releases a temporary buffer by returning to the cache or freeing it. If
+     * returning to the cache then insert it at the start so that it is
+     * likely to be returned by a subsequent call to getTemporaryDirectBuffer.
+     */
+    static void offerFirstTemporaryDirectBuffer(ByteBuffer buf) {
+        assert buf != null;
+        BufferCache cache = bufferCache.get();
+        if (!cache.offerFirst(buf)) {
+            // cache is full
+            free(buf);
+        }
+    }
+
+    /**
+     * Releases a temporary buffer by returning to the cache or freeing it. If
+     * returning to the cache then insert it at the end. This makes it
+     * suitable for scatter/gather operations where the buffers are returned to
+     * cache in same order that they were obtained.
+     */
+    static void offerLastTemporaryDirectBuffer(ByteBuffer buf) {
+        assert buf != null;
+        BufferCache cache = bufferCache.get();
+        if (!cache.offerLast(buf)) {
+            // cache is full
+            free(buf);
+        }
+    }
+
+    /**
+     * Frees the memory for the given direct buffer
+     */
+    private static void free(ByteBuffer buf) {
+        ((DirectBuffer)buf).cleaner().clean();
     }
 
     private static class SelectorWrapper {