From e532293310472bc474771d3f5f8c53113eaf4bcb Mon Sep 17 00:00:00 2001
From: Michael Stack <stack@apache.org>
Date: Fri, 17 Sep 2010 04:21:28 +0000
Subject: [PATCH] HBASE-3006 Reading compressed HFile blocks causes way too
 many DFS RPC calls severly impacting performance--Now add fix I intended, a
 spelling mistake in HFile

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@997975 13f79535-47bb-0310-9956-ffa450edef68
---
 CHANGES.txt                                          |  3 +++
 .../java/org/apache/hadoop/hbase/io/hfile/HFile.java | 12 +++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index f49a4f5fe46..6d7d97f1caa 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -523,6 +523,9 @@ Release 0.21.0 - Unreleased
    HBASE-2986  multi writable can npe causing client hang
    HBASE-2979  Fix failing TestMultParrallel in hudson build
    HBASE-2899  hfile.min.blocksize.size ignored/documentation wrong
+   HBASE-3006  Reading compressed HFile blocks causes way too many DFS RPC
+               calls severly impacting performance
+               (Kannan Muthukkaruppan via Stack)
 
   IMPROVEMENTS
    HBASE-1760  Cleanup TODOs in HTable
diff --git a/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java b/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
index f9c8dd6d520..8f3e08ca8c0 100644
--- a/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
+++ b/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
@@ -19,6 +19,7 @@
  */
 package org.apache.hadoop.hbase.io.hfile;
 
+import java.io.BufferedInputStream;
 import java.io.Closeable;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
@@ -1051,10 +1052,15 @@ public class HFile {
         // decompressor reading into next block -- IIRC, it just grabs a
         // bunch of data w/o regard to whether decompressor is coming to end of a
         // decompression.
+
+        // We use a buffer of DEFAULT_BLOCKSIZE size.  This might be extreme.
+        // Could maybe do with less. Study and figure it: TODO
         InputStream is = this.compressAlgo.createDecompressionStream(
-          new BoundedRangeFileInputStream(this.istream, offset, compressedSize,
-            pread),
-          decompressor, 0);
+            new BufferedInputStream(
+                new BoundedRangeFileInputStream(this.istream, offset, compressedSize,
+                                                pread),
+                Math.min(DEFAULT_BLOCKSIZE, compressedSize)),
+            decompressor, 0);
         buf = ByteBuffer.allocate(decompressedSize);
         IOUtils.readFully(is, buf.array(), 0, buf.capacity());
         is.close();