Possible to poll JobTracker for information from any language?
Hello, I'm interested in writing a library, to be used with Node.js, that can ask the JobTracker for information about jobs. I see that this is possible using the Java API, with the JobClient interface [1]. I also saw that on the wiki, it mentions that clients can poll the JobTracker for information, but does not go into detail [2]. Is it possible to get information about jobs from the JobTracker using C, or C++, or Thrift, or something else? Thanks, Ryan 1. http://hadoop.apache.org/common/docs/r1.0.1/mapred_tutorial.html#Job+Submission+and+Monitoring 2. http://wiki.apache.org/hadoop/JobTracker
Can't construct instance of class org.apache.hadoop.conf.Configuration
Hello, I'm trying to run an application, written in C++, that uses libhdfs. I have compiled the code and get an error when I attempt to run the application. The error that I am getting is as follows: "Can't construct instance of class org.apache.hadoop.conf.Configuration". Initially, I was receiving an error saying that CLASSPATH was not set. That was easy, so I set CLASSPATH to include the following three directories, in this order: 1. $HADOOP_HOME 2. $HADOOP_HOME/lib 3. $HADOOP_HOME/conf The CLASSPATH not set error went away, and now I receive the error about the Configuration class. I'm assuming that I do not have something on the path that I need to, but everything I have read says to simply include these three directories. Does anybody have any idea what I might be missing? Full exception pasted below. Thanks, Ryan Exception in thread "main" java.lang.NoClassDefFoundError: > org/apache/hadoop/conf/Configuration > Caused by: java.lang.ClassNotFoundException: > org.apache.hadoop.conf.Configuration > at java.net.URLClassLoader$1.run(URLClassLoader.java:366) > at java.net.URLClassLoader$1.run(URLClassLoader.java:355) > at java.security.AccessController.doPrivileged(Native Method) > at java.net.URLClassLoader.findClass(URLClassLoader.java:354) > at java.lang.ClassLoader.loadClass(ClassLoader.java:423) > at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) > at java.lang.ClassLoader.loadClass(ClassLoader.java:356) > Can't construct instance of class org.apache.hadoop.conf.Configuration > node: /home/ryan/.node-gyp/0.7.8/src/node_object_wrap.h:61: void > node::ObjectWrap::Wrap(v8::Handle): Assertion > `handle_.IsEmpty()' failed. > Aborted (core dumped)
Re: Can't construct instance of class org.apache.hadoop.conf.Configuration
Brock, Ah, thanks. I did not realize that you could do that. That sets the correct CLASSPATH! Thanks. Ryan On Mon, Apr 30, 2012 at 10:22 AM, Brock Noland wrote: > Hi, > > I would try this: > > export CLASSPATH=$(hadoop classpath) > > Brock > > On Mon, Apr 30, 2012 at 10:15 AM, Ryan Cole wrote: > > Hello, > > > > I'm trying to run an application, written in C++, that uses libhdfs. I > have > > compiled the code and get an error when I attempt to run the application. > > The error that I am getting is as follows: "Can't construct instance of > > class org.apache.hadoop.conf.Configuration". > > > > Initially, I was receiving an error saying that CLASSPATH was not set. > That > > was easy, so I set CLASSPATH to include the following three directories, > in > > this order: > > > > > > 1. $HADOOP_HOME > > 2. $HADOOP_HOME/lib > > 3. $HADOOP_HOME/conf > > > > The CLASSPATH not set error went away, and now I receive the error about > > the Configuration class. I'm assuming that I do not have something on the > > path that I need to, but everything I have read says to simply include > > these three directories. > > > > Does anybody have any idea what I might be missing? Full exception pasted > > below. > > > > Thanks, > > Ryan > > > > Exception in thread "main" java.lang.NoClassDefFoundError: > >> org/apache/hadoop/conf/Configuration > >> Caused by: java.lang.ClassNotFoundException: > >> org.apache.hadoop.conf.Configuration > >> at java.net.URLClassLoader$1.run(URLClassLoader.java:366) > >> at java.net.URLClassLoader$1.run(URLClassLoader.java:355) > >> at java.security.AccessController.doPrivileged(Native Method) > >> at java.net.URLClassLoader.findClass(URLClassLoader.java:354) > >> at java.lang.ClassLoader.loadClass(ClassLoader.java:423) > >> at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) > >> at java.lang.ClassLoader.loadClass(ClassLoader.java:356) > >> Can't construct instance of class org.apache.hadoop.conf.Configuration > >> node: /home/ryan/.node-gyp/0.7.8/src/node_object_wrap.h:61: void > >> node::ObjectWrap::Wrap(v8::Handle): Assertion > >> `handle_.IsEmpty()' failed. > >> Aborted (core dumped) > > > > -- > Apache MRUnit - Unit testing MapReduce - > http://incubator.apache.org/mrunit/ >
