From ffa160ddb824cbcb8ab6b10ee1414507686e3c63 Mon Sep 17 00:00:00 2001
From: Arpit Agarwal <arp@apache.org>
Date: Fri, 17 Mar 2017 19:02:24 -0700
Subject: [PATCH] HDFS-11547. Add logs for slow BlockReceiver while writing
 data to disk. Contributed by Xiaobing Zhou.

---
 .../org/apache/hadoop/hdfs/server/datanode/BlockReceiver.java | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockReceiver.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockReceiver.java
index 5852403ac2..bb6bd5570e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockReceiver.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockReceiver.java
@@ -711,6 +711,10 @@ private int receivePacket() throws IOException {
           streams.writeDataToDisk(dataBuf.array(),
               startByteToDisk, numBytesToDisk);
           long duration = Time.monotonicNow() - begin;
+          if (duration > datanodeSlowLogThresholdMs) {
+            LOG.warn("Slow BlockReceiver write data to disk cost:" + duration
+                + "ms (threshold=" + datanodeSlowLogThresholdMs + "ms)");
+          }
 
           if (duration > maxWriteToDiskMs) {
             maxWriteToDiskMs = duration;