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From acmur...@apache.org
Subject svn commit: r610135 [1/3] - in /lucene/hadoop/trunk: ./ docs/ src/docs/src/documentation/content/xdocs/ src/java/org/apache/hadoop/mapred/
Date Tue, 08 Jan 2008 20:32:31 GMT
Author: acmurthy
Date: Tue Jan  8 12:32:29 2008
New Revision: 610135

URL: http://svn.apache.org/viewvc?rev=610135&view=rev
HADOOP-1660. Add the cwd of the map/reduce task to the java.library.path of the child-jvm
to support loading of native libraries distributed via the DistributedCache.


Modified: lucene/hadoop/trunk/CHANGES.txt
URL: http://svn.apache.org/viewvc/lucene/hadoop/trunk/CHANGES.txt?rev=610135&r1=610134&r2=610135&view=diff
--- lucene/hadoop/trunk/CHANGES.txt (original)
+++ lucene/hadoop/trunk/CHANGES.txt Tue Jan  8 12:32:29 2008
@@ -163,6 +163,10 @@
     HADOOP-2390. Added documentation for user-controls for intermediate
     map-outputs & final job-outputs and native-hadoop libraries. (acmurthy) 
+    HADOOP-1660. Add the cwd of the map/reduce task to the java.library.path
+    of the child-jvm to support loading of native libraries distributed via
+    the DistributedCache. (acmurthy)
     HADOOP-1898.  Release the lock protecting the last time of the last stack

Modified: lucene/hadoop/trunk/docs/mapred_tutorial.html
URL: http://svn.apache.org/viewvc/lucene/hadoop/trunk/docs/mapred_tutorial.html?rev=610135&r1=610134&r2=610135&view=diff
--- lucene/hadoop/trunk/docs/mapred_tutorial.html (original)
+++ lucene/hadoop/trunk/docs/mapred_tutorial.html Tue Jan  8 12:32:29 2008
@@ -216,6 +216,9 @@
 <a href="#Job+Configuration">Job Configuration</a>
+<a href="#Task+Execution+%26+Environment">Task Execution &amp; Environment</a>
 <a href="#Job+Submission+and+Monitoring">Job Submission and Monitoring</a>
 <ul class="minitoc">
@@ -274,7 +277,7 @@
 <a href="#Example%3A+WordCount+v2.0">Example: WordCount v2.0</a>
 <ul class="minitoc">
-<a href="#Source+Code-N10B1F">Source Code</a>
+<a href="#Source+Code-N10B98">Source Code</a>
 <a href="#Sample+Runs">Sample Runs</a>
@@ -1460,7 +1463,67 @@
         <a href="api/org/apache/hadoop/conf/Configuration.html#set(java.lang.String, java.lang.String)">set(String,
String)</a>/<a href="api/org/apache/hadoop/conf/Configuration.html#get(java.lang.String,
java.lang.String)">get(String, String)</a>
         to set/get arbitrary parameters needed by applications. However, use the 
         <span class="codefrag">DistributedCache</span> for large amounts of (read-only)
-<a name="N1082C"></a><a name="Job+Submission+and+Monitoring"></a>
+<a name="N1082C"></a><a name="Task+Execution+%26+Environment"></a>
+<h3 class="h4">Task Execution &amp; Environment</h3>
+<p>The <span class="codefrag">TaskTracker</span> executes the <span
+        <span class="codefrag">Reducer</span>  <em>task</em> as a
child process in a separate jvm.
+        </p>
+<p>The child-task inherits the environment of the parent 
+        <span class="codefrag">TaskTracker</span>. The user can specify additional
options to the
+        child-jvm via the <span class="codefrag">mapred.child.java.opts</span>
+        parameter in the <span class="codefrag">JobConf</span> such as non-standard
paths for the 
+        run-time linker to search shared libraries via 
+        <span class="codefrag">-Djava.library.path=&lt;&gt;</span> etc.
If the 
+        <span class="codefrag">mapred.child.java.opts</span> contains the symbol
+        it is interpolated with value of <span class="codefrag">taskid</span>
of the map/reduce
+        task.</p>
+<p>Here is an example with multiple arguments and substitutions, 
+        showing jvm GC logging, and start of a passwordless JVM JMX agent so that
+        it can connect with jconsole and the likes to watch child memory, 
+        threads and get thread dumps. It also sets the maximum heap-size of the 
+        child jvm to 512MB and adds an additional path to the 
+        <span class="codefrag">java.library.path</span> of the child-jvm.</p>
+<span class="codefrag">&lt;property&gt;</span>
+          &nbsp;&nbsp;<span class="codefrag">&lt;name&gt;mapred.child.java.opts&lt;/name&gt;</span>
+          &nbsp;&nbsp;<span class="codefrag">&lt;value&gt;</span>
+          &nbsp;&nbsp;&nbsp;&nbsp;<span class="codefrag">
+                    -Xmx512M -Djava.library.path=/home/mycompany/lib
+                    -verbose:gc -Xloggc:/tmp/@taskid@.gc</span>
+          &nbsp;&nbsp;&nbsp;&nbsp;<span class="codefrag">
+                    -Dcom.sun.management.jmxremote.authenticate=false 
+                    -Dcom.sun.management.jmxremote.ssl=false</span>
+          &nbsp;&nbsp;<span class="codefrag">&lt;/value&gt;</span>
+<span class="codefrag">&lt;/property&gt;</span>
+<p>The <a href="#DistributedCache">DistributedCache</a> can also be used
+        as a rudimentary software distribution mechanism for use in the map 
+        and/or reduce tasks. It can be used to distribute both jars and 
+        native libraries. The 
+        <a href="api/org/apache/hadoop/filecache/DistributedCache.html#addArchiveToClassPath(org.apache.hadoop.fs.Path,%20org.apache.hadoop.conf.Configuration)">
+        DistributedCache.addArchiveToClassPath(Path, Configuration)</a> or 
+        <a href="api/org/apache/hadoop/filecache/DistributedCache.html#addFileToClassPath(org.apache.hadoop.fs.Path,%20org.apache.hadoop.conf.Configuration)">
+        DistributedCache.addFileToClassPath(Path, Configuration)</a> api can 
+        be used to cache files/jars and also add them to the <em>classpath</em>

+        of child-jvm. Similarly the facility provided by the 
+        <span class="codefrag">DistributedCache</span> where-in it symlinks the
cached files into
+        the working directory of the task can be used to distribute native 
+        libraries and load them. The underlying detail is that child-jvm always 
+        has its <em>current working directory</em> added to the
+        <span class="codefrag">java.library.path</span> and hence the cached
libraries can be 
+        loaded via <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/System.html#loadLibrary(java.lang.String)">
+        System.loadLibrary</a> or <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/System.html#load(java.lang.String)">
+        System.load</a>.</p>
+<a name="N108A1"></a><a name="Job+Submission+and+Monitoring"></a>
 <h3 class="h4">Job Submission and Monitoring</h3>
 <a href="api/org/apache/hadoop/mapred/JobClient.html">
@@ -1496,7 +1559,7 @@
 <p>Normally the user creates the application, describes various facets 
         of the job via <span class="codefrag">JobConf</span>, and then uses the

         <span class="codefrag">JobClient</span> to submit the job and monitor
its progress.</p>
-<a name="N1086A"></a><a name="Job+Control"></a>
+<a name="N108DF"></a><a name="Job+Control"></a>
 <h4>Job Control</h4>
 <p>Users may need to chain map-reduce jobs to accomplish complex
           tasks which cannot be done via a single map-reduce job. This is fairly
@@ -1532,7 +1595,7 @@
-<a name="N10894"></a><a name="Job+Input"></a>
+<a name="N10909"></a><a name="Job+Input"></a>
 <h3 class="h4">Job Input</h3>
 <a href="api/org/apache/hadoop/mapred/InputFormat.html">
@@ -1580,7 +1643,7 @@
         appropriate <span class="codefrag">CompressionCodec</span>. However,
it must be noted that
         compressed files with the above extensions cannot be <em>split</em> and

         each compressed file is processed in its entirety by a single mapper.</p>
-<a name="N108FE"></a><a name="InputSplit"></a>
+<a name="N10973"></a><a name="InputSplit"></a>
 <a href="api/org/apache/hadoop/mapred/InputSplit.html">
@@ -1594,7 +1657,7 @@
           FileSplit</a> is the default <span class="codefrag">InputSplit</span>.
It sets 
           <span class="codefrag">map.input.file</span> to the path of the input
file for the
           logical split.</p>
-<a name="N10923"></a><a name="RecordReader"></a>
+<a name="N10998"></a><a name="RecordReader"></a>
 <a href="api/org/apache/hadoop/mapred/RecordReader.html">
@@ -1606,7 +1669,7 @@
           for processing. <span class="codefrag">RecordReader</span> thus assumes
           responsibility of processing record boundaries and presents the tasks 
           with keys and values.</p>
-<a name="N10946"></a><a name="Job+Output"></a>
+<a name="N109BB"></a><a name="Job+Output"></a>
 <h3 class="h4">Job Output</h3>
 <a href="api/org/apache/hadoop/mapred/OutputFormat.html">
@@ -1631,7 +1694,7 @@
 <span class="codefrag">TextOutputFormat</span> is the default 
         <span class="codefrag">OutputFormat</span>.</p>
-<a name="N1096F"></a><a name="Task+Side-Effect+Files"></a>
+<a name="N109E4"></a><a name="Task+Side-Effect+Files"></a>
 <h4>Task Side-Effect Files</h4>
 <p>In some applications, component tasks need to create and/or write to
           side-files, which differ from the actual job-output files.</p>
@@ -1657,7 +1720,7 @@
           JobConf.getOutputPath()</a>, and the framework will promote them 
           similarly for succesful task-attempts, thus eliminating the need to 
           pick unique paths per task-attempt.</p>
-<a name="N109A4"></a><a name="RecordWriter"></a>
+<a name="N10A19"></a><a name="RecordWriter"></a>
 <a href="api/org/apache/hadoop/mapred/RecordWriter.html">
@@ -1665,9 +1728,9 @@
           pairs to an output file.</p>
 <p>RecordWriter implementations write the job outputs to the 
           <span class="codefrag">FileSystem</span>.</p>
-<a name="N109BB"></a><a name="Other+Useful+Features"></a>
+<a name="N10A30"></a><a name="Other+Useful+Features"></a>
 <h3 class="h4">Other Useful Features</h3>
-<a name="N109C1"></a><a name="Counters"></a>
+<a name="N10A36"></a><a name="Counters"></a>
 <span class="codefrag">Counters</span> represent global counters, defined either
@@ -1681,7 +1744,7 @@
           Reporter.incrCounter(Enum, long)</a> in the <span class="codefrag">map</span>
           <span class="codefrag">reduce</span> methods. These counters are then
           aggregated by the framework.</p>
-<a name="N109EC"></a><a name="DistributedCache"></a>
+<a name="N10A61"></a><a name="DistributedCache"></a>
 <a href="api/org/apache/hadoop/filecache/DistributedCache.html">
@@ -1701,19 +1764,20 @@
           per job and the ability to cache archives which are un-archived on 
           the slaves.</p>
-<span class="codefrag">DistributedCache</span> can be used to distribute simple,

-          read-only data/text files and more complex types such as archives and
-          jars. Archives (zip files) are <em>un-archived</em> at the slave nodes.
-          Jars maybe be optionally added to the classpath of the tasks, a
-          rudimentary <em>software distribution</em> mechanism.  Files have 
-          <em>execution permissions</em> set. Optionally users can also direct
-          <span class="codefrag">DistributedCache</span> to <em>symlink</em>
the cached file(s) 
-          into the working directory of the task.</p>
 <span class="codefrag">DistributedCache</span> tracks the modification timestamps
           the cached files. Clearly the cache files should not be modified by 
           the application or externally while the job is executing.</p>
-<a name="N10A26"></a><a name="Tool"></a>
+<span class="codefrag">DistributedCache</span> can be used to distribute simple,

+          read-only data/text files and more complex types such as archives and
+          jars. Archives (zip files) are <em>un-archived</em> at the slave nodes.
+          Optionally users can also direct the <span class="codefrag">DistributedCache</span>
+          <em>symlink</em> the cached file(s) into the <span class="codefrag">current
+          directory</span> of the task via the 
+          <a href="api/org/apache/hadoop/filecache/DistributedCache.html#createSymlink(org.apache.hadoop.conf.Configuration)">
+          DistributedCache.createSymlink(Path, Configuration)</a> api. Files 
+          have <em>execution permissions</em> set.</p>
+<a name="N10A9F"></a><a name="Tool"></a>
 <p>The <a href="api/org/apache/hadoop/util/Tool.html">Tool</a> 
           interface supports the handling of generic Hadoop command-line options.
@@ -1753,7 +1817,7 @@
-<a name="N10A58"></a><a name="IsolationRunner"></a>
+<a name="N10AD1"></a><a name="IsolationRunner"></a>
 <a href="api/org/apache/hadoop/mapred/IsolationRunner.html">
@@ -1777,13 +1841,13 @@
 <span class="codefrag">IsolationRunner</span> will run the failed task in a single

           jvm, which can be in the debugger, over precisely the same input.</p>
-<a name="N10A8B"></a><a name="JobControl"></a>
+<a name="N10B04"></a><a name="JobControl"></a>
 <a href="api/org/apache/hadoop/mapred/jobcontrol/package-summary.html">
           JobControl</a> is a utility which encapsulates a set of Map-Reduce jobs
           and their dependencies.</p>
-<a name="N10A98"></a><a name="Data+Compression"></a>
+<a name="N10B11"></a><a name="Data+Compression"></a>
 <h4>Data Compression</h4>
 <p>Hadoop Map-Reduce provides facilities for the application-writer to
           specify compression for both intermediate map-outputs and the
@@ -1797,7 +1861,7 @@
           codecs for reasons of both performance (zlib) and non-availability of
           Java libraries (lzo). More details on their usage and availability are
           available <a href="native_libraries.html">here</a>.</p>
-<a name="N10AB8"></a><a name="Intermediate+Outputs"></a>
+<a name="N10B31"></a><a name="Intermediate+Outputs"></a>
 <h5>Intermediate Outputs</h5>
 <p>Applications can control compression of intermediate map-outputs
             via the 
@@ -1818,7 +1882,7 @@
             <a href="api/org/apache/hadoop/mapred/JobConf.html#setMapOutputCompressionType(org.apache.hadoop.io.SequenceFile.CompressionType)">
-<a name="N10AE4"></a><a name="Job+Outputs"></a>
+<a name="N10B5D"></a><a name="Job+Outputs"></a>
 <h5>Job Outputs</h5>
 <p>Applications can control compression of job-outputs via the
             <a href="api/org/apache/hadoop/mapred/OutputFormatBase.html#setCompressOutput(org.apache.hadoop.mapred.JobConf,%20boolean)">
@@ -1838,12 +1902,12 @@
-<a name="N10B13"></a><a name="Example%3A+WordCount+v2.0"></a>
+<a name="N10B8C"></a><a name="Example%3A+WordCount+v2.0"></a>
 <h2 class="h3">Example: WordCount v2.0</h2>
 <div class="section">
 <p>Here is a more complete <span class="codefrag">WordCount</span> which
uses many of the
       features provided by the Map-Reduce framework we discussed so far:</p>
-<a name="N10B1F"></a><a name="Source+Code-N10B1F"></a>
+<a name="N10B98"></a><a name="Source+Code-N10B98"></a>
 <h3 class="h4">Source Code</h3>
 <table class="ForrestTable" cellspacing="1" cellpadding="4">
@@ -3021,7 +3085,7 @@
-<a name="N11251"></a><a name="Sample+Runs"></a>
+<a name="N112CA"></a><a name="Sample+Runs"></a>
 <h3 class="h4">Sample Runs</h3>
 <p>Sample text-files as input:</p>
@@ -3186,7 +3250,7 @@
-<a name="N11321"></a><a name="Salient+Points"></a>
+<a name="N1139A"></a><a name="Salient+Points"></a>
 <h3 class="h4">Salient Points</h3>
 <p>The second version of <span class="codefrag">WordCount</span> improves
upon the 
         previous one by using some features offered by the Map-Reduce framework:

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