--- a/jdk/src/java.base/share/classes/java/io/OutputStreamWriter.java	Wed Dec 02 09:34:55 2015 -0800
+++ b/jdk/src/java.base/share/classes/java/io/OutputStreamWriter.java	Wed Dec 02 21:32:40 2015 +0100
@@ -25,6 +25,7 @@
 
 package java.io;
 
+import java.nio.CharBuffer;
 import java.nio.charset.Charset;
 import java.nio.charset.CharsetEncoder;
 import sun.nio.cs.StreamEncoder;
@@ -220,6 +221,28 @@
         se.write(str, off, len);
     }
 
+    @Override
+    public Writer append(CharSequence csq, int start, int end) throws IOException {
+        if (csq == null) {
+            write("null".subSequence(start, end).toString());
+            return this;
+        } else {
+            return append(csq.subSequence(start, end));
+        }
+    }
+
+    @Override
+    public Writer append(CharSequence csq) throws IOException {
+        if (csq == null) {
+            se.write("null");
+        } else if (csq instanceof CharBuffer) {
+            se.write((CharBuffer) csq);
+        } else {
+            se.write(csq.toString());
+        }
+        return this;
+    }
+
     /**
      * Flushes the stream.
      *

--- a/jdk/src/java.base/share/classes/sun/nio/cs/StreamEncoder.java	Wed Dec 02 09:34:55 2015 -0800
+++ b/jdk/src/java.base/share/classes/sun/nio/cs/StreamEncoder.java	Wed Dec 02 21:32:40 2015 +0100
@@ -135,6 +135,18 @@
         write(cbuf, 0, len);
     }
 
+    public void write(CharBuffer cb) throws IOException {
+        int position = cb.position();
+        try {
+            synchronized (lock) {
+                ensureOpen();
+                implWrite(cb);
+            }
+        } finally {
+            cb.position(position);
+        }
+    }
+
     public void flush() throws IOException {
         synchronized (lock) {
             ensureOpen();
@@ -266,9 +278,15 @@
         throws IOException
     {
         CharBuffer cb = CharBuffer.wrap(cbuf, off, len);
+        implWrite(cb);
+    }
 
-        if (haveLeftoverChar)
+    void implWrite(CharBuffer cb)
+        throws IOException
+    {
+        if (haveLeftoverChar) {
             flushLeftoverChar(cb, false);
+        }
 
         while (cb.hasRemaining()) {
             CoderResult cr = encoder.encode(cb, bb, false);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/io/Writer/Bug6856817.java	Wed Dec 02 21:32:40 2015 +0100
@@ -0,0 +1,156 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 6856817
+ * @summary optimize the Writer.append(CharSequence) method
+ */
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.FileReader;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+
+/**
+ *
+ * @author vyom.tewari@oacle.com
+ */
+public class Bug6856817 {
+
+    private static final String str = "This is just a test string that i am using it to test the CharBuffer.append(CharSequence csq)  for little bit performance improvement.";
+    private static final int BUF_SIZE = 1024;
+
+    /**
+     *
+     * @param args
+     */
+    public static void main(String args[]) {
+        CharBuffer charBuffer = CharBuffer.allocate(BUF_SIZE);
+        File file = new File("temp.txt");
+        file.deleteOnExit();
+
+        charBuffer.put(str);
+        charBuffer.flip();
+        checkFileContent(charBuffer, file, str);
+        charBuffer.position(10);
+        checkFileContent(charBuffer, file, str.substring(10));
+        charBuffer.position(charBuffer.limit());
+        checkFileContent(charBuffer, file, str.substring(charBuffer.limit()));
+
+        char arr[] = new char[BUF_SIZE];
+        charBuffer = CharBuffer.wrap(arr);
+        charBuffer.put(str);
+        charBuffer.flip();
+        checkFileContent(charBuffer, file, str);
+        charBuffer.position(10);
+        checkFileContent(charBuffer, file, str.substring(10));
+        charBuffer.position(charBuffer.limit());
+        checkFileContent(charBuffer, file, str.substring(charBuffer.limit()));
+
+        char secArr[] = new char[BUF_SIZE];
+        charBuffer = CharBuffer.wrap(secArr);
+        charBuffer.put(str);
+        charBuffer.position(5);
+        charBuffer.limit(str.length() - 7);
+        charBuffer = charBuffer.slice();
+        checkFileContent(charBuffer, file, str.substring(5, (str.length() - 7)));
+        charBuffer.position(10);
+        checkFileContent(charBuffer, file, str.substring(15, (str.length() - 7)));
+        charBuffer.position(charBuffer.limit());
+        checkFileContent(charBuffer, file, str.substring(charBuffer.limit()));
+
+        charBuffer = ByteBuffer.allocate(BUF_SIZE).asCharBuffer();
+        charBuffer.put(str);
+        charBuffer.flip();
+        checkFileContent(charBuffer, file, str);
+        charBuffer.position(10);
+        checkFileContent(charBuffer, file, str.substring(10));
+        charBuffer.position(charBuffer.limit());
+        checkFileContent(charBuffer, file, str.substring(charBuffer.limit()));
+
+        charBuffer = ByteBuffer.allocateDirect(1024).asCharBuffer();
+        charBuffer.put(str);
+        charBuffer.flip();
+        checkFileContent(charBuffer, file, str);
+        charBuffer.position(10);
+        checkFileContent(charBuffer, file, str.substring(10));
+        charBuffer.position(charBuffer.limit());
+        checkFileContent(charBuffer, file, str.substring(charBuffer.limit()));
+    }
+
+    private static void checkFileContent(CharBuffer charBuffer, File file, String expectedValue) {
+        OutputStreamWriter writer = null;
+        FileReader reader = null;
+        int position, limit;
+        position = charBuffer.position();
+        limit = charBuffer.limit();
+        try {
+            OutputStream outputStream = new FileOutputStream(file);
+            writer = new OutputStreamWriter(outputStream);
+            writer.append(charBuffer);
+            writer.close();
+            if (!isEqual(position, charBuffer.position())) {
+                System.out.println(": failed");
+                throw new RuntimeException("buffer position before write: " + position + " and position after write: " + charBuffer.position());
+            }
+            if (!isEqual(limit, charBuffer.limit())) {
+                System.out.println(": failed");
+                throw new RuntimeException("buffer limit before write: " + limit + " and limit after write: " + charBuffer.limit());
+            }
+            reader = new FileReader(file);
+            char arr[] = new char[BUF_SIZE];
+            int byteRead = reader.read(arr);
+            if (byteRead != -1) {
+                String stringRead = new String(arr, 0, byteRead);
+                if (expectedValue.equals(stringRead)) {
+                    System.out.println(": passed");
+                } else {
+                    System.out.println(": failed");
+                    throw new RuntimeException("expected :" + expectedValue + " and got:" + stringRead);
+                }
+            }
+        } catch (IOException ex) {
+            ex.printStackTrace();
+            throw new RuntimeException(ex);
+        } finally {
+            try {
+                if (writer != null) {
+                    writer.close();
+                }
+                if (reader != null) {
+                    reader.close();
+                }
+            } catch (IOException ex) {
+                throw new RuntimeException(ex);
+            }
+        }
+    }
+
+    private static boolean isEqual(final int first, final int second) {
+        return (first == second);
+    }
+}