From 29a1ba1e8fb11432404cea49e46eef47c36bb70a Mon Sep 17 00:00:00 2001
From: Suresh Srinivas <suresh@apache.org>
Date: Thu, 24 Dec 2009 00:47:20 +0000
Subject: [PATCH] HADOOP-6460. Reinitializes buffers used for serializing
 responses in ipc server on exceeding maximum response size to free up Java
 heap. Contributed by Suresh Srinivas.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@893666 13f79535-47bb-0310-9956-ffa450edef68
---
 CHANGES.txt                                     |  4 ++++
 src/java/org/apache/hadoop/ipc/Server.java      | 17 +++++++++++++++--
 .../hadoop/ipc/TestIPCServerResponder.java      |  6 ++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 36e2ab2f32..c5cca75cfc 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1267,6 +1267,10 @@ Release 0.20.2 - Unreleased
     HADOOP-6269. Fix threading issue with defaultResource in Configuration.
     (Sreekanth Ramakrishnan via cdouglas)
 
+    HADOOP-6460. Reinitializes buffers used for serializing responses in ipc
+    server on exceeding maximum response size to free up Java heap. (suresh)
+    
+
 Release 0.20.1 - 2009-09-01
 
   INCOMPATIBLE CHANGES
diff --git a/src/java/org/apache/hadoop/ipc/Server.java b/src/java/org/apache/hadoop/ipc/Server.java
index 5bd0e8363d..02e78b55ce 100644
--- a/src/java/org/apache/hadoop/ipc/Server.java
+++ b/src/java/org/apache/hadoop/ipc/Server.java
@@ -91,6 +91,12 @@ public abstract class Server {
    */
   private static final int MAX_QUEUE_SIZE_PER_HANDLER = 100;
   
+  /**
+   * Initial and max size of response buffer
+   */
+  static int INITIAL_RESP_BUF_SIZE = 10240;
+  static int MAX_RESP_BUF_SIZE = 1024*1024;
+    
   public static final Log LOG = LogFactory.getLog(Server.class);
 
   private static final ThreadLocal<Server> SERVER = new ThreadLocal<Server>();
@@ -944,7 +950,8 @@ public Handler(int instanceNumber) {
     public void run() {
       LOG.info(getName() + ": starting");
       SERVER.set(Server.this);
-      ByteArrayOutputStream buf = new ByteArrayOutputStream(10240);
+      ByteArrayOutputStream buf = 
+        new ByteArrayOutputStream(INITIAL_RESP_BUF_SIZE);
       while (running) {
         try {
           final Call call = callQueue.take(); // pop the queue; maybe blocked here
@@ -985,10 +992,16 @@ public Writable run() throws Exception {
             error = StringUtils.stringifyException(e);
           }
           CurCall.set(null);
-
           setupResponse(buf, call, 
                         (error == null) ? Status.SUCCESS : Status.ERROR, 
                         value, errorClass, error);
+          // Discard the large buf and reset it back to 
+          // smaller size to freeup heap
+          if (buf.size() > MAX_RESP_BUF_SIZE) {
+            LOG.warn("Large response size " + buf.size() + " for call " + 
+                call.toString());
+            buf = new ByteArrayOutputStream(INITIAL_RESP_BUF_SIZE);
+          }
           responder.doRespond(call);
         } catch (InterruptedException e) {
           if (running) {                          // unexpected -- log it
diff --git a/src/test/core/org/apache/hadoop/ipc/TestIPCServerResponder.java b/src/test/core/org/apache/hadoop/ipc/TestIPCServerResponder.java
index 2591da0143..e1370fe866 100644
--- a/src/test/core/org/apache/hadoop/ipc/TestIPCServerResponder.java
+++ b/src/test/core/org/apache/hadoop/ipc/TestIPCServerResponder.java
@@ -114,6 +114,12 @@ public void run() {
     }
   }
 
+  public void testResponseBuffer() throws Exception {
+    Server.INITIAL_RESP_BUF_SIZE = 1;
+    Server.MAX_RESP_BUF_SIZE = 1;
+    testServerResponder(1, true, 1, 1, 5);
+  }
+
   public void testServerResponder() throws Exception {
     testServerResponder(10, true, 1, 10, 200);
   }