java - Hadoop "Unable to load native-hadoop library for your platform" warning

Question

I'm currently configuring hadoop on a server running CentOs. When I run start-dfs.sh or stop-dfs.sh, I get the following error:

WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable

I'm running Hadoop 2.2.0.

Doing a search online brought up this link: http://balanceandbreath.blogspot.ca/2013/01/utilnativecodeloader-unable-to-load.html

However, the contents of /native/ directory on hadoop 2.x appear to be different so I am not sure what to do.

I've also added these two environment variables in hadoop-env.sh:

export HADOOP_OPTS="$HADOOP_OPTS -Djava.library.path=/usr/local/hadoop/lib/"

export HADOOP_COMMON_LIB_NATIVE_DIR="/usr/local/hadoop/lib/native/"

Any ideas?

Answer 1

I assume you're running Hadoop on 64bit CentOS. The reason you saw that warning is the native Hadoop library $HADOOP_HOME/lib/native/libhadoop.so.1.0.0 was actually compiled on 32 bit.

Anyway, it's just a warning, and won't impact Hadoop's functionalities.

Here is the way if you do want to eliminate this warning, download the source code of Hadoop and recompile libhadoop.so.1.0.0 on 64bit system, then replace the 32bit one.

Steps on how to recompile source code are included here for Ubuntu:

• http://www.ercoppa.org/Linux-Compile-Hadoop-220-fix-Unable-to-load-native-hadoop-library.htm

Good luck.