Scriptella: ResourceException with Jaybird - linux

I'm very newbie with Linux/Java/Scriptella and I'm trying a jdbc connection with scriptella on a Firebird local database, but I'm receiving the following errors:
2-dic-2013 1.03.34 <INFO> Execution Progress.Initializing properties: 1%
2-dic-2013 1.03.34 <GRAVE> Script /home/maurizio/Scrivania/JATROPHA/applicazioni/prova_per_scriptella.etl execution failed.
javax/resource/ResourceException
2-dic-2013 1.03.34 <GRAVE> Scriptella bug report. Submit to issue tracker.
Scriptella version: 1.1
Exception:
scriptella.execution.EtlExecutorException: javax/resource/ResourceException
at scriptella.execution.EtlExecutor.execute(EtlExecutor.java:190)
at scriptella.tools.launcher.EtlLauncher.execute(EtlLauncher.java:276)
at scriptella.tools.launcher.EtlLauncher.launch(EtlLauncher.java:193)
at scriptella.tools.launcher.EtlLauncher.main(EtlLauncher.java:321)
Caused by: java.lang.NoClassDefFoundError: javax/resource/ResourceException
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:270)
at scriptella.core.DriverFactory.getDriver(DriverFactory.java:53)
at scriptella.core.ConnectionManager.<init>(ConnectionManager.java:70)
at scriptella.core.Session.<init>(Session.java:51)
at scriptella.execution.EtlExecutor.prepare(EtlExecutor.java:248)
at scriptella.execution.EtlExecutor.execute(EtlExecutor.java:178)
... 3 more
Caused by: java.lang.ClassNotFoundException: javax.resource.ResourceException
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
... 10 more
I'm using Ubuntu 10.04 Lucid Lynx.
I start scriptella via console in directory /home/maurizio/Scrivania/JATROPHA/applicazioni/ with the command scriptella/scriptella-1.1/bin/scriptella.sh -debug "prova_per_scriptella.etl"
My ETL file prova_per_scriptella.etl contains the following rows:
<!DOCTYPE etl SYSTEM "http://scriptella.javaforge.com/dtd/etl.dtd">
<etl>
<description>Prova connessione Firebird</description>
<connection
id="fb_destination"
driver="org.firebirdsql.jdbc.FBDriver"
url="jdbc:firebirdsql:localhost/3050:/home/maurizio/Scrivania/JATROPHA/db/jatrofa.fdb"
user="user"
password="password"
classpath="/home/maurizio/Scrivania/JATROPHA/applicazioni/jaybird/Jaybird-2.2.3JDK_1.6/jaybird-2.2.3.jar"
/>
</etl>
The env var $_SCRIPTELLA_CP of batch command scriptella/scriptella-1.1/bin/scriptella.sh results in
:/home/maurizio/Scrivania/JATROPHA/applicazioni/scriptella/scriptella-1.1/lib/commons-jexl.jar:
/home/maurizio/Scrivania/JATROPHA/applicazioni/scriptella/scriptella-1.1/lib/commons-logging.jar:
/home/maurizio/Scrivania/JATROPHA/applicazioni/scriptella/scriptella-1.1/lib/jaybird-2.2.3.jar:
/home/maurizio/Scrivania/JATROPHA/applicazioni/scriptella/scriptella-1.1/lib/jsqlparser-0.8.0.jar:
/home/maurizio/Scrivania/JATROPHA/applicazioni/scriptella/scriptella-1.1/lib/scriptella-core.jar:
/home/maurizio/Scrivania/JATROPHA/applicazioni/scriptella/scriptella-1.1/lib/scriptella-drivers.jar:
/home/maurizio/Scrivania/JATROPHA/applicazioni/scriptella/scriptella-1.1/lib/scriptella-tools.jar:
/home/maurizio/Scrivania/JATROPHA/applicazioni/scriptella/scriptella-1.1/lib/sqlsheet-6.5.jar
Any help would be very appreciated.
Thanks in advance.

You are missing the required dependency connector-api-1.5.jar, or you need to use jaybird-full-2.2.3.jar (which includes both the normal Jaybird and connector-api). See the releasenotes of Jaybird 2.2.3

The error means that you probably miss additional J2EE classes on classpath. Try downloading mini-j2ee.jar from http://www.firebirdsql.org/en/jdbc-driver/ and adding it to classpath attribute in etl.xml:
classpath="/path/to/mini-j2ee.jar:/home/maurizio/Scrivania/JATROPHA/applicazioni/jaybird/Jaybird-2.2.3JDK_1.6/jaybird-2.2.3.jar"

Related

Spark 2.3 java.lang.NoSuchMethodError: io.netty.buffer.PooledByteBufAllocator.metric

SPARK 2.3 is throwing following exception. Can anyone please help!! I tried adding the JARs
308 [Driver] ERROR org.apache.spark.deploy.yarn.ApplicationMaster - User class threw exception: java.lang.NoSuchMethodError: io.netty.buffer.PooledByteBufAllocator.metric()Lio/netty/buffer/PooledByteBufAllocatorMetric;
java.lang.NoSuchMethodError: io.netty.buffer.PooledByteBufAllocator.metric()Lio/netty/buffer/PooledByteBufAllocatorMetric;
at org.apache.spark.network.util.NettyMemoryMetrics.registerMetrics(NettyMemoryMetrics.java:80)
at org.apache.spark.network.util.NettyMemoryMetrics.(NettyMemoryMetrics.java:76)
at org.apache.spark.network.client.TransportClientFactory.(TransportClientFactory.java:109)
at org.apache.spark.network.TransportContext.createClientFactory(TransportContext.java:99)
at org.apache.spark.rpc.netty.NettyRpcEnv.(NettyRpcEnv.scala:71)
at org.apache.spark.rpc.netty.NettyRpcEnvFactory.create(NettyRpcEnv.scala:461)
at org.apache.spark.rpc.RpcEnv$.create(RpcEnv.scala:57)
at org.apache.spark.SparkEnv$.create(SparkEnv.scala:249)
at org.apache.spark.SparkEnv$.createDriverEnv(SparkEnv.scala:175)
at org.apache.spark.SparkContext.createSparkEnv(SparkContext.scala:256)
at org.apache.spark.SparkContext.(SparkContext.scala:423)
at org.apache.spark.api.java.JavaSparkContext.(JavaSparkContext.scala:58)
at com.voicebase.etl.HBasePhoenixPerformance2.main(HBasePhoenixPerformance2.java:55)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.spark.deploy.yarn.ApplicationMaster$$anon$4.run(ApplicationMaster.scala:706)
315 [main] ERROR org.apache.spark.deploy.yarn.ApplicationMaster - Uncaught exception:
org.apache.spark.SparkException: Exception thrown in awaitResult:
at org.apache.spark.util.ThreadUtils$.awaitResult(ThreadUtils.scala:205)
at org.apache.spark.deploy.yarn.ApplicationMaster.runDriver(ApplicationMaster.scala:486)
at org.apache.spark.deploy.yarn.ApplicationMaster.org$apache$spark$deploy$yarn$ApplicationMaster$$runImpl(ApplicationMaster.scala:345)
at org.apache.spark.deploy.yarn.ApplicationMaster$$anonfun$run$2.apply$mcV$sp(ApplicationMaster.scala:260)
at org.apache.spark.deploy.yarn.ApplicationMaster$$anonfun$run$2.apply(ApplicationMaster.scala:260)
at org.apache.spark.deploy.yarn.ApplicationMaster$$anonfun$run$2.apply(ApplicationMaster.scala:260)
at org.apache.spark.deploy.yarn.ApplicationMaster$$anon$5.run(ApplicationMaster.scala:800)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1836)
at org.apache.spark.deploy.yarn.ApplicationMaster.doAsUser(ApplicationMaster.scala:799)
at org.apache.spark.deploy.yarn.ApplicationMaster.run(ApplicationMaster.scala:259)
at org.apache.spark.deploy.yarn.ApplicationMaster$.main(ApplicationMaster.scala:824)
at org.apache.spark.deploy.yarn.ApplicationMaster.main(ApplicationMaster.scala)
Caused by: java.util.concurrent.ExecutionException: Boxed Error
This is because Hadoop binaries compiled with an older version and need us to just replace them. I haven't faced any issues with Hadoop by replacing them.
You need to replace netty-3.6.2.Final.jar and netty-all-4.0.23.Final.jar from path $HADOOP_HOME\share\hadoop with netty-all-4.1.17.Final.jar and netty-3.9.9.Final.jar.
This issue plagues due to mismatch of the version that Hadoop and Spark are compiled on for Netty. So you can follow this.
Similar Issue , solved by manually compiling the Spark by using specific version of Netty
And the other one as recommended by Suhas , by copying the content of SPARK_HOME/jars folder to the various lib folder or only the one in yarn inside HADOOP_HOME/share/hadoop solves the problem also. But it's a dirty fix. So maybe use latest version of both or manually compile them.
An older version of Netty was required by the aws-java-sdk. Deleting all the netty jars and removing the aws-java-sdk from the project solved the problem.
Issue has been resolved by adding the below netty jars in the dependencies,
"io.netty" % "netty-all" % "4.1.68.Final"
"io.netty" % "netty-buffer" % "4.1.68.Final"
And excluding all existing netty jars by adding excludeAll code.
val excludeNettyBufferBinding = ExclusionRule(organization = "io.netty.buffer")
excludeAll(excludeNettyBufferBinding)

UIMA Ruta run errors using DKProCore Part-of-Speech Tagger (German Novels tutorial)

When following this tutorial on UIMA Ruta for German Novels step by step, I get the following error upon running Main.ruta:
*SEVERE: Exception occurred
org.apache.uima.analysis_engine.AnalysisEngineProcessException
(...)
Caused by: java.io.IOException: Unable to locate model [de] in the
following locations
[classpath:/de/tudarmstadt/ukp/dkpro/core/treetagger/lib/tagger-de-
little-endian.par]. Make sure the environment variable
'TREETAGGER_HOME' or 'TAGDIR' or the system property 'treetagger.home'
point to the TreeTagger installation directory.*
I have verified the location of my TREETAGGER_HOME, which is set in my environment variables and in Eclipse. I also considered using a more recent verison of the treetagger and found the following errors:
1.7.0
SEVERE: Exception occurred
org.apache.uima.analysis_engine.AnalysisEngineProcessException:
Annotator processing failed.
(...)
Caused by: java.lang.ClassNotFoundException:
de.tudarmstadt.ukp.dkpro.core.api.parameter.Messages
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 43 more
1.8.0
SEVERE: Exception occurred
org.apache.uima.analysis_engine.AnalysisEngineProcessException:
"Unsupported language [de]."
at de.tudarmstadt.uk
(...)
Caused by: java.io.IOException: Unable to load resource
[classpath:/de/tudarmstadt/ukp/dkpro/core/treetagger/lib/tagger-de-
le.properties]:
FileNotFoundException: No file found at
[classpath:/de/tudarmstadt/ukp/dkpro/core/treetagger/lib/tagger-de-
le.properties]
Upon seeing the error in the last attempt I checked once more the language parameters for German which are present under the necessary formats.
Any advice on how to solve this?
The problem is, that the license of TreeTagger prohibits distributing it through Maven Central.
The is a long answer to that which includes how to build and install the TreeTagger models locally. You could look e.g. at the instructions here provided by the Excitement project which also uses DKPro Core.
I would recommend you try using another tagger instead of TreeTagger, e.g. the OpenNlpPosTagger from DKPro Core. Instead of the de.tudarmstadt.ukp.dkpro.core.treetagger-asl use de.tudarmstadt.ukp.dkpro.core.opennlp-asl in the pom.xml file.
<dependency>
<groupId>de.tudarmstadt.ukp.dkpro.core</groupId>
<artifactId>de.tudarmstadt.ukp.dkpro.core.opennlp-asl</artifactId>
<version>1.5.0</version>
</dependency>
And in the POSTag.ruta script, try replacing the import/exec of TreeTaggerPosLemmaTT4J with these:
UIMAFIT de.tudarmstadt.ukp.dkpro.core.opennlp.OpenNlpPosTagger;
...snip...
Document{-> EXEC(OpenNlpPosTagger, {pos.POS, Lemma})}:
Warning: I haven't tried running this ;)
Disclaimer: I'm working on DKPro Core.

loging to hazelcast management center is throwing NullPointerException

When I log in to Hazelcast management center I get the following exception. Not sure what exactly is causing this issue.
The Management Center is deployed in Weblogic 12c
Hazelcast version: 3.1.3
java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor534.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.apache.commons.beanutils.MethodUtils.invokeMethod(MethodUtils.java:282)
at org.apache.commons.beanutils.MethodUtils.invokeMethod(MethodUtils.java:226)
at org.apache.commons.beanutils.MethodUtils.invokeMethod(MethodUtils.java:177)
at com.hazelcast.webmonitor.service.DataService.invokeMethod(DataService.java:108)
at com.hazelcast.webmonitor.service.DataService.getResponse(DataService.java:86)
at com.hazelcast.webmonitor.servlet.MainServlet.doGet(MainServlet.java:80)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:844)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:242)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:216)
at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:132)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:338)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:221)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3284)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.__run(WebAppServletContext.java:3254)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:120)
at weblogic.servlet.provider.WlsSubjectHandle.run(WlsSubjectHandle.java:57)
at weblogic.servlet.internal.WebAppServletContext.doSecuredExecute(WebAppServletContext.java:2163)
at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2089)
at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2074)
at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1513)
at weblogic.servlet.provider.ContainerSupportProviderImpl$WlsRequestExecutor.run(ContainerSupportProviderImpl.java:254)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:256)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:221)
Caused by: java.lang.NullPointerException
at java.util.LinkedList$ListItr.next(LinkedList.java:891)
at java.util.SubList$1.next(AbstractList.java:707)
at java.util.AbstractCollection.toArray(AbstractCollection.java:141)
at java.util.Collections.sort(Collections.java:216)
at com.hazelcast.webmonitor.service.WarningLogsManager.getSystemWarnings(WarningLogsManager.java:96)
at com.hazelcast.webmonitor.service.DataService.showSystemWarning(DataService.java:717)
... 29 more
So finally this issue got resolved . I added the following preferred packages list to my weblogic.xml file because it was suggested by CAT tool .
<wls:package-name>javax.activation.*</wls:package-name>
<wls:package-name>javax.mail.*</wls:package-name>
<wls:package-name>javax.mail.event.*</wls:package-name>
<wls:package-name>javax.mail.internet.*</wls:package-name>
<wls:package-name>javax.mail.search.*</wls:package-name>
<wls:package-name>javax.mail.util.*</wls:package-name>
<wls:package-name>org.apache.commons.*</wls:package-name>
Removing those fixed the issue.
I just checked the code. The exception doesn't make any sense. Which JVM are you using. And perhaps it is smarter to run on a more lightweight container like jetty,tomcat etc.

Cassandra Startup java.lang.reflect.InvocationTargetException

What could be the solution for this exception
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.xerial.snappy.SnappyLoader.loadNativeLibrary(SnappyLoader.java:322)
at org.xerial.snappy.SnappyLoader.load(SnappyLoader.java:229)
at org.xerial.snappy.Snappy.<clinit>(Snappy.java:48)
at org.xerial.snappy.SnappyOutputStream.<init>(SnappyOutputStream.java:79)
at org.xerial.snappy.SnappyOutputStream.<init>(SnappyOutputStream.java:66)
at org.apache.cassandra.net.OutboundTcpConnection.connect(OutboundTcpConnection.java:359)
at org.apache.cassandra.net.OutboundTcpConnection.run(OutboundTcpConnection.java:150)
Caused by: java.lang.UnsatisfiedLinkError: /tmp/snappy-1.0.5-libsnappyjava.so: /tmp/snappy-1.0.5-libsnappyjava.so: failed to map segment from shared object: Operation not permitted
at java.lang.ClassLoader$NativeLibrary.load(Native Method)
at java.lang.ClassLoader.loadLibrary1(ClassLoader.java:1957)
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1882)
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1843)
at java.lang.Runtime.load0(Runtime.java:795)
at java.lang.System.load(System.java:1061)
at org.xerial.snappy.SnappyNativeLoader.load(SnappyNativeLoader.java:39)
... 11 more
ERROR 11:46:22,430 Exception in thread Thread[WRITE-/172.20.6.138,5,main]
org.xerial.snappy.SnappyError: [FAILED_TO_LOAD_NATIVE_LIBRARY] null
at org.xerial.snappy.SnappyLoader.load(SnappyLoader.java:239)
at org.xerial.snappy.Snappy.<clinit>(Snappy.java:48)
at org.xerial.snappy.SnappyOutputStream.<init>(SnappyOutputStream.java:79)
at org.xerial.snappy.SnappyOutputStream.<init>(SnappyOutputStream.java:66)
at org.apache.cassandra.net.OutboundTcpConnection.connect(OutboundTcpConnection.java:359)
at org.apache.cassandra.net.OutboundTcpConnection.run(OutboundTcpConnection.java:150)
But the cassandra startup execution is continue. and at the end i am getting exception
java.lang.IllegalStateException: Unable to contact any seeds!
at org.apache.cassandra.service.StorageService.bootstrap(StorageService.java:947)
at org.apache.cassandra.service.StorageService.joinTokenRing(StorageService.java:716)
at org.apache.cassandra.service.StorageService.initServer(StorageService.java:554)
at org.apache.cassandra.service.StorageService.initServer(StorageService.java:451)
at org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:347)
at org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:446)
at org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:489)
Exception encountered during startup: Unable to contact any seeds!
ERROR 11:55:11,732 Exception in thread Thread[StorageServiceShutdownHook,5,main]
java.lang.NullPointerException
at org.apache.cassandra.service.StorageService.stopRPCServer(StorageService.java:321)
at org.apache.cassandra.service.StorageService.shutdownClientServers(StorageService.java:370)
at org.apache.cassandra.service.StorageService.access$000(StorageService.java:88)
at org.apache.cassandra.service.StorageService$1.runMayThrow(StorageService.java:519)
at org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:28)
at java.lang.Thread.run(Thread.java:724)
but the seeds nodes are running.
Machine firewall is disabled.
I also tried changing default tmp directory. I tried including JVM_OPTS=-Dorg.xerial.snappy.tempdir=/tmp to cassandra.in.sh file but the problem is remains.
Linux version 2.6.32-358.6.1.el6.x86_64 (mockbuild#c6b9.bsys.dev.centos.org) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC) ) #1 SMP Tue Apr 23 19:29:00 UTC 2013
please help me.. thanks in advance.
They mention this error here in the Cassandra JIRA:
https://issues.apache.org/jira/browse/CASSANDRA-4400
I had a similar error with Cassandra 1.2, and I fixed it by replacing the snappy 1.0.5 library with the snappy 1.0.4.1. If that link doesn't work, you should be able to grab that from an earlier version of Cassandra (like 1.1.x).
Basically, remove the snappy-java.1.0.5.jar from your $CASSANDRA_HOME/lib directory, and replace it with snappy-java-1.0.4.1.jar
I found an answer wrote by Erik in
http://mail-archives.apache.org/mod_mbox/cassandra-user/201312.mbox/%3C52C1DEC4.2080904#cj.com%3E
You can add something like this to cassandra-env.sh :
JVM_OPTS="$JVM_OPTS
-Dorg.xerial.snappy.tempdir=/path/that/allows/executables"
I created a tmp folder in /var/lib/cassandra/
so I added
JVM_OPTS="$JVM_OPTS -Dorg.xerial.snappy.tempdir=/var/lib/cassandra/tmp/"
Hope this help somebody

Hadoop HDFS test running issue - org.apache.hadoop.conf.Configuration NoClassDefFoundError

I'm working with Hadoop 0.21.0. and trying to run the hdfs_test application that comes alongside the C API library. After many problems I was able to compile hdfs_test. Now when I'm running it:
./hdfs_test
I'm getting the following error:
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory
at org.apache.hadoop.conf.Configuration.<clinit>(Configuration.java:153)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
... 1 more
Can't construct instance of class org.apache.hadoop.conf.Configuration
Oops! Failed to connect to hdfs!
Any help is appreciated.. thanks
Like any other Java program you need the dependencies in the classpath or inside the jar. Hadoop also has an HADOOP_CLASSPATH to tell the cluster where to find dependencies in map-reduce tasks. Also see How to run a Hadoop program?

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