Native Libraries Guide

Native Hadoop Library

Hadoop has native implementations of certain components for performance reasons and for non-availability of Java implementations. These components are available in a single, dynamically-linked native library called the native hadoop library. On the *nix platforms the library is named libhadoop.so.

Usage

It is fairly easy to use the native hadoop library:

Review the components.

Review the supported platforms.

Either download a hadoop release, which will include a pre-built version of the native hadoop library, or build your own version of the native hadoop library. Whether you download or build, the name for the library is the same: libhadoop.so

Install the compression codec development packages (>zlib-1.2, >gzip-1.2):

If you download the library, install one or more development packages - whichever compression codecs you want to use with your deployment.

If you build the library, it is mandatory to install both development packages.

Check the runtime log files.

Components

The native hadoop library includes various components:

Compression Codecs (bzip2, lz4, snappy, zlib)

Native IO utilities for HDFS Short-Circuit Local Reads and Centralized Cache Management in HDFS

CRC32 checksum implementation

Supported Platforms

The native hadoop library is supported on *nix platforms only. The library does not to work with Cygwin or the Mac OS X platform.

The native hadoop library is mainly used on the GNU/Linus platform and has been tested on these distributions:

RHEL4/Fedora

Ubuntu

Gentoo

On all the above distributions a 32/64 bit native hadoop library will work with a respective 32/64 bit jvm.

Build

The native hadoop library is written in ANSI C and is built using the GNU autotools-chain (autoconf, autoheader, automake, autoscan, libtool). This means it should be straight-forward to build the library on any platform with a standards-compliant C compiler and the GNU autotools-chain (see the supported platforms).

The packages you need to install on the target platform are:

C compiler (e.g. GNU C Compiler)

GNU Autools Chain: autoconf, automake, libtool

zlib-development package (stable version >= 1.2.0)

openssl-development package(e.g. libssl-dev)

Once you installed the prerequisite packages use the standard hadoop pom.xml file and pass along the native flag to build the native hadoop library:

$ mvn package -Pdist,native -DskipTests -Dtar

You should see the newly-built library in:

$ hadoop-dist/target/hadoop-2.7.1/lib/native

Please note the following:

It is mandatory to install both the zlib and gzip development packages on the target platform in order to build the native hadoop library; however, for deployment it is sufficient to install just one package if you wish to use only one codec.

It is necessary to have the correct 32/64 libraries for zlib, depending on the 32/64 bit jvm for the target platform, in order to build and deploy the native hadoop library.

http://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-common/NativeLibraries.html