HADOOP-6292. Update native libraries guide. Contributed by Corinne Chandel
git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@827855 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Christopher Douglas
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@ -1122,6 +1122,8 @@ Release 0.21.0 - Unreleased
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HADOOP-6286. Fix bugs in related to URI handling in glob methods in
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FileContext. (Boris Shkolnik via suresh)
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HADOOP-6292. Update native libraries guide. (Corinne Chandel via cdouglas)
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Release 0.20.2 - Unreleased
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HADOOP-6231. Allow caching of filesystem instances to be disabled on a
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@ -27,89 +27,81 @@
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<body>
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<section>
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<title>Purpose</title>
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<title>Overview</title>
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<p>This guide describes the native hadoop library and includes a small discussion about native shared libraries.</p>
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<p><strong>Note:</strong> Depending on your environment, the term "native libraries" <em>could</em>
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refer to all *.so's you need to compile; and, the term "native compression" <em>could</em> refer to all *.so's
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you need to compile that are specifically related to compression.
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Currently, however, this document only addresses the native hadoop library (<em>libhadoop.so</em>).</p>
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<p>Hadoop has native implementations of certain components for reasons of
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both performance and non-availability of Java implementations. These
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components are available in a single, dynamically-linked, native library.
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On the *nix platform it is <em>libhadoop.so</em>. This document describes
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the usage and details on how to build the native libraries.</p>
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</section>
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<section>
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<title>Components</title>
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<title>Native Hadoop Library </title>
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<p>Hadoop currently has the following
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<a href="ext:api/org/apache/hadoop/io/compress/compressioncodec">
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compression codecs</a> as the native components:</p>
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<ul>
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<li><a href="ext:zlib">zlib</a></li>
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<li><a href="ext:gzip">gzip</a></li>
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<li><a href="ext:bzip">bzip2</a></li>
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</ul>
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<p>Of the above, the availability of native hadoop libraries is imperative
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for the gzip and bzip2 compression codecs to work.</p>
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</section>
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<p>Hadoop has native implementations of certain components for
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performance reasons and for non-availability of Java implementations. These
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components are available in a single, dynamically-linked native library called
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the native hadoop library. On the *nix platforms the library is named <em>libhadoop.so</em>. </p>
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<section>
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<title>Usage</title>
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<p>It is fairly simple to use the native hadoop libraries:</p>
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<p>It is fairly easy to use the native hadoop library:</p>
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<ol>
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<li>
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Review the <a href="#Components">components</a>.
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</li>
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<li>
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Review the <a href="#Supported+Platforms">supported platforms</a>.
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</li>
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<li>
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Either <a href="#Download">download</a> a hadoop release, which will
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include a pre-built version of the native hadoop library, or
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<a href="#Build">build</a> your own version of the
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native hadoop library. Whether you download or build, the name for the library is
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the same: <em>libhadoop.so</em>
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</li>
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<li>
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Install the compression codec development packages
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(<strong>>zlib-1.2</strong>, <strong>>gzip-1.2</strong>):
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<ul>
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<li>
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Take a look at the
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<a href="#Supported+Platforms">supported platforms</a>.
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</li>
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<li>
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Either <a href="ext:releases/download">download</a> the pre-built
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32-bit i386-Linux native hadoop libraries (available as part of hadoop
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distribution in <code>lib/native</code> directory) or
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<a href="#Building+Native+Hadoop+Libraries">build</a> them yourself.
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</li>
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<li>
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Make sure you have any of or all of <strong>>zlib-1.2</strong>,
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<strong>>gzip-1.2</strong>, and <strong>>bzip2-1.0</strong>
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packages for your platform installed;
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depending on your needs.
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</li>
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<li>If you download the library, install one or more development packages -
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whichever compression codecs you want to use with your deployment.</li>
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<li>If you build the library, it is <strong>mandatory</strong>
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to install both development packages.</li>
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</ul>
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<p>The <code>bin/hadoop</code> script ensures that the native hadoop
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library is on the library path via the system property
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<em>-Djava.library.path=<path></em>.</p>
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<p>To check everything went alright check the hadoop log files for:</p>
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<p>
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<code>
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DEBUG util.NativeCodeLoader - Trying to load the custom-built
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native-hadoop library...
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</code><br/>
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<code>
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INFO util.NativeCodeLoader - Loaded the native-hadoop library
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</code>
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</p>
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<p>If something goes wrong, then:</p>
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<p>
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<code>
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INFO util.NativeCodeLoader - Unable to load native-hadoop library for
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your platform... using builtin-java classes where applicable
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</code>
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</li>
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<li>
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Check the <a href="#Runtime">runtime</a> log files.
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</li>
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</ol>
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</section>
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<section>
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<title>Components</title>
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<p>The native hadoop library includes two components, the zlib and gzip
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<a href="http://hadoop.apache.org/common/docs/current/api/org/apache/hadoop/io/compress/CompressionCodec.html">
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compression codecs</a>:
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</p>
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<ul>
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<li><a href="ext:zlib">zlib</a></li>
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<li><a href="ext:gzip">gzip</a></li>
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</ul>
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<p>The native hadoop library is imperative for gzip to work.</p>
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</section>
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<section>
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<title>Supported Platforms</title>
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<p>Hadoop native library is supported only on *nix platforms only.
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Unfortunately it is known not to work on <a href="ext:cygwin">Cygwin</a>
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and <a href="ext:osx">Mac OS X</a> and has mainly been used on the
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GNU/Linux platform.</p>
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<p>The native hadoop library is supported on *nix platforms only.
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The library does not to work with <a href="ext:cygwin">Cygwin</a>
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or the <a href="ext:osx">Mac OS X</a> platform.</p>
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<p>It has been tested on the following GNU/Linux distributions:</p>
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<p>The native hadoop library is mainly used on the GNU/Linus platform and
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has been tested on these distributions:</p>
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<ul>
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<li>
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<a href="http://www.redhat.com/rhel/">RHEL4</a>/<a href="http://fedora.redhat.com/">Fedora</a>
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@ -118,22 +110,30 @@
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<li><a href="http://www.gentoo.org/">Gentoo</a></li>
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</ul>
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<p>On all the above platforms a 32/64 bit Hadoop native library will work
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<p>On all the above distributions a 32/64 bit native hadoop library will work
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with a respective 32/64 bit jvm.</p>
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</section>
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<section>
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<title>Building Native Hadoop Libraries</title>
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<title>Download</title>
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<p>Hadoop native library is written in
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<a href="http://en.wikipedia.org/wiki/ANSI_C">ANSI C</a> and built using
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the GNU autotools-chain (autoconf, autoheader, automake, autoscan, libtool).
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This means it should be straight-forward to build them on any platform with
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a standards compliant C compiler and the GNU autotools-chain.
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See <a href="#Supported+Platforms">supported platforms</a>.</p>
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<p>The pre-built 32-bit i386-Linux native hadoop library is available as part of the
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hadoop distribution and is located in the <code>lib/native</code> directory. You can download the
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hadoop distribution from <a href="ext:releases/download">Hadoop Common Releases</a>.</p>
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<p>In particular the various packages you would need on the target
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platform are:</p>
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<p>Be sure to install the zlib and/or gzip development packages - whichever compression
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codecs you want to use with your deployment.</p>
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</section>
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<section>
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<title>Build</title>
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<p>The native hadoop library is written in <a href="http://en.wikipedia.org/wiki/ANSI_C">ANSI C</a>
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and is built using the GNU autotools-chain (autoconf, autoheader, automake, autoscan, libtool).
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This means it should be straight-forward to build the library on any platform with a standards-compliant
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C compiler and the GNU autotools-chain (see the <a href="#Supported+Platforms">supported platforms</a>).</p>
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<p>The packages you need to install on the target platform are:</p>
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<ul>
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<li>
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C compiler (e.g. <a href="http://gcc.gnu.org/">GNU C Compiler</a>)
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@ -149,52 +149,69 @@
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</li>
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</ul>
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<p>Once you have the prerequisites use the standard <code>build.xml</code>
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and pass along the <code>compile.native</code> flag (set to
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<code>true</code>) to build the native hadoop library:</p>
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<p>Once you installed the prerequisite packages use the standard hadoop <code>build.xml</code>
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file and pass along the <code>compile.native</code> flag (set to <code>true</code>) to build the native hadoop library:</p>
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<p><code>$ ant -Dcompile.native=true <target></code></p>
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<p>The native hadoop library is not built by default since not everyone is
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interested in building them.</p>
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<p>You should see the newly-built native hadoop library in:</p>
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<p>You should see the newly-built library in:</p>
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<p><code>$ build/native/<platform>/lib</code></p>
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<p>where <platform> is combination of the system-properties:
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<code>${os.name}-${os.arch}-${sun.arch.data.model}</code>; for e.g.
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Linux-i386-32.</p>
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<section>
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<title>Notes</title>
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<p>where <<code>platform</code>> is a combination of the system-properties:
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<code>${os.name}-${os.arch}-${sun.arch.data.model}</code> (for example, Linux-i386-32).</p>
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<p>Please note the following:</p>
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<ul>
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<li>
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It is <strong>mandatory</strong> to have the
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zlib, gzip, and bzip2
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development packages on the target platform for building the
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native hadoop library; however for deployment it is sufficient to
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install one of them if you wish to use only one of them.
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It is <strong>mandatory</strong> to install both the zlib and gzip
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development packages on the target platform in order to build the
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native hadoop library; however, for deployment it is sufficient to
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install just one package if you wish to use only one codec.
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</li>
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<li>
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It is necessary to have the correct 32/64 libraries of both zlib
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depending on the 32/64 bit jvm for the target platform for
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building/deployment of the native hadoop library.
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It is necessary to have the correct 32/64 libraries for zlib,
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depending on the 32/64 bit jvm for the target platform, in order to
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build and deploy the native hadoop library.
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</li>
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</ul>
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</section>
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<section>
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<title>Runtime</title>
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<p>The <code>bin/hadoop</code> script ensures that the native hadoop
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library is on the library path via the system property: <br/>
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<em>-Djava.library.path=<path></em></p>
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<p>During runtime, check the hadoop log files for your MapReduce tasks.</p>
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<ul>
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<li>If everything is all right, then:<br/><br/>
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<code> DEBUG util.NativeCodeLoader - Trying to load the custom-built native-hadoop library... </code><br/>
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<code> INFO util.NativeCodeLoader - Loaded the native-hadoop library </code><br/>
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</li>
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<li>If something goes wrong, then:<br/><br/>
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<code>
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INFO util.NativeCodeLoader - Unable to load native-hadoop library for
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your platform... using builtin-java classes where applicable
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</code>
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</li>
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</ul>
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</section>
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</section>
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<section>
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<title> Loading Native Libraries Through DistributedCache </title>
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<p>User can load native shared libraries through
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<title>Native Shared Libraries</title>
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<p>You can load <strong>any</strong> native shared library using
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<a href="http://hadoop.apache.org/mapreduce/docs/current/mapred_tutorial.html#DistributedCache">DistributedCache</a>
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for <em>distributing</em> and <em>symlinking</em> the library files.</p>
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<p>Here is an example, describing how to distribute the library and
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load it from a MapReduce task. </p>
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<p>This example shows you how to distribute a shared library, <code>mylib.so</code>,
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and load it from a MapReduce task.</p>
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<ol>
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<li> First copy the library to the HDFS. <br/>
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<li> First copy the library to the HDFS: <br/>
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<code>bin/hadoop fs -copyFromLocal mylib.so.1 /libraries/mylib.so.1</code>
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</li>
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<li> The job launching program should contain the following: <br/>
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@ -206,6 +223,9 @@
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<code> System.loadLibrary("mylib.so"); </code>
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</li>
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</ol>
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<p><br/><strong>Note:</strong> If you downloaded or built the native hadoop library, you don’t need to use DistibutedCache to
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make the library available to your MapReduce tasks.</p>
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</section>
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</body>
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