From 07ecdb877dee0aa76a3269e37ac4783a55ab6bf6 Mon Sep 17 00:00:00 2001
From: Uma Mahesh <umamahesh@apache.org>
Date: Wed, 28 Oct 2015 23:33:11 -0700
Subject: [PATCH] HDFS-9261. Erasure Coding: Skip encoding the data cells if
 all the parity data streamers are failed for the current block group. (Rakesh
 R via umamahesh)

---
 .../hadoop/hdfs/DFSStripedOutputStream.java    | 18 ++++++++++++++++++
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt    |  3 +++
 2 files changed, 21 insertions(+)

diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedOutputStream.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedOutputStream.java
index 884fa42484..c595026174 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedOutputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedOutputStream.java
@@ -844,6 +844,11 @@ private boolean generateParityCellsForLastStripe() {
 
   void writeParityCells() throws IOException {
     final ByteBuffer[] buffers = cellBuffers.getBuffers();
+    // Skips encoding and writing parity cells if there are no healthy parity
+    // data streamers
+    if (!checkAnyParityStreamerIsHealthy()) {
+      return;
+    }
     //encode the data cells
     encode(encoder, numDataBlocks, buffers);
     for (int i = numDataBlocks; i < numAllBlocks; i++) {
@@ -852,6 +857,19 @@ void writeParityCells() throws IOException {
     cellBuffers.clear();
   }
 
+  private boolean checkAnyParityStreamerIsHealthy() {
+    for (int i = numDataBlocks; i < numAllBlocks; i++) {
+      if (streamers.get(i).isHealthy()) {
+        return true;
+      }
+    }
+    if (LOG.isDebugEnabled()) {
+      LOG.debug("Skips encoding and writing parity cells as there are "
+          + "no healthy parity data streamers: " + streamers);
+    }
+    return false;
+  }
+
   void writeParity(int index, ByteBuffer buffer, byte[] checksumBuf)
       throws IOException {
     final StripedDataStreamer current = setCurrentStreamer(index);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index aa26088d86..a87fe76b34 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -184,6 +184,9 @@ Trunk (Unreleased)
     HDFS-9070. Allow fsck display pending replica location information for
     being-written blocks. (GAO Rui via jing9)
 
+    HDFS-9261. Erasure Coding: Skip encoding the data cells if all the parity data 
+    streamers are failed for the current block group. (Rakesh R via umamahesh)
+
   OPTIMIZATIONS
 
   BUG FIXES