I am a hadoop beginner .
I have inastelled Hadoop 3.1.1 on a cluster. As my OS is CentOS 6.9 (64bit), I recompiled Hadoop Native library and replaced it in HADOOP_HOME/lib.
When I run wordcount example which is in "HADOOP_HOME/share/hadoop/mapreduce", I get: "Error: Could not find or load main class org.apache.hadoop.mapred.YarnChild".
I found no answer except changing the version of Hadoop on the internet.
Any idea about how to solve it?
Thanks in advance
Thanks, it is solved.
based on my exprience, any error about class not found is because of mapred-site.xml wrong configuration.
a good config is here:
hadoop pagerank error when running
Related
C:\hadoop-2.3.0\bin>hadoop
The system cannot find the path specified.
Error: JAVA_HOME is incorrectly set.
Please update C:\hadoop-2.3.0\conf\hadoop-env.c
Usage: hadoop [--config confdir] COMMAND
Facing above error in Hadoop configuration. Can anyone please help to resolve the issue.
If this is for learning purpose to setup hadoop on windows you will find enough blog link
If your primary objective is to learn Hadoop then i will suggest you to download VMware Player and setup hadoop on ubantu or you can download CDH version from cloudera website to start your learning.
I've been trying to install hadoop 2.7.0 on Ubuntu but when i enter the hadoop namenode -format command i get the following message:
Error: Could not find or load main class org.apache.hadoop.hdfs.server.namenode.NameNode
I've triple checked all the configuration files but i can't seem to find where the problem is.
I followed this tutorial : http://www.bogotobogo.com/Hadoop/BigData_hadoop_Install_on_ubuntu_single_node_cluster.php
Can anyone please tell me why is this not working??
You have to add hadoop-hdfs-2.7.0.jar to your hadoop classpath. Just add these lines in $HADOOP_HOME/etc/hadoop/hadoop-env.sh:
export HADOOP_HOME=/path/to/hadoop
export HADOOP_CLASSPATH=$HADOOP_CLASSPATH:$HADOOP_HOME/share/hadoop/hdfs/hadoop-hdfs-2.7.0.jar
Now, stop all hadoop processes. Try to format namenode now. Post the error if you get any.
I just installed Hadoop from the yahoo developers network running on a vm. I ran the following code after start-all.sh after cd-ing to the bin folder
hadoop jar hadoop-0.19.0.-examples.jar pi 10 1000000
I'm getting
java. io.IOException:Error opening jon jar:hadoop-0.18.0-examples.jar
at org.apache.hadoop.util.main(RunJar.java:90) at
org.apache.hadoop.mapred.JobShell.run(JobShell.java:54) at
org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65) at
org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79) at
org.apache.hadoop.mapred.JobShell.main(JobShell.java:68) caused
by:java.util.ZipExcaption:error in opening zip file
How do i sort this out?
Please make sure that have below things in place
Your examples.jar file is present in the path where you are running the above command. else you need to give complete path for the jar file.
hadoop jar /usr/lib/hadoop-mapreduce/*example.jar pi 10 100000
It has appropriate read permissions for the user that you are using to run the hadoop job.
If you still face issue, please update logs in your question.
You will face this issue if you are using older version of the java . Hadoop needs Java 7 or Java 8. Please check your JAVA version and update if needed.
I'm new to hadoop. I want to do stress/performance test on hadoop cluster. To do that, I followed the instructions given at Hadoop benchmarking. The difference is that in tutorial he is talking about hadoop 0.20.0 version and I'm trying to run similar thing in hadoop 2.4.0. I understand tutorial might not work fully, as there are many changes in version. For performing IO performance test on Hadoop, in tutorial he told me to use TestDFSIO. But I can't find the same in my hadoop installation.
To find TestDFSIO, I tried following command,
jar tf /home/hadoop/share/hadoop/hdfs/hadoop-hdfs-2.4.0-tests.jar|grep TestDFS
But couldn't find it. So, I assume I the filename is changed in newer version. Can somebody help in finding the new filename? or equivalent benchmarking techniques required for hadoop 2.4.0?
Found the jar which has TestDFSIO and other bench-marking classes/code. It is present in
/home/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-client-jobclient-2.4.0-tests.jar
Here /home/hadoop is my hadoop installed path. It may not be same for you.
I was unable to configure the HBase standalone instance. Following are the steps I followed:
Downloaded hbase-0.98.9-hadoop2 and extracted it.
Set my JAVA_HOMEin the environment variables.
Edited conf/hbase-site.xml and changed the configuration as mentioned in the Apache HBase quick start guide.
Ran the bin/start-hbase.sh and this error came up.
Can anyone tell me what I'm missing or doing wrong? Thanks
Here are the steps:
http://hbase.apache.org/cygwin.html
Hbase cannot be installed without cygwin tooling.