Hi, For option 1: I can not add jars in our cluster as no permission. And we also want to keep our cluster clean and stable.
For option 2: It does not work as the jars from "-libjar" are not loaded in the client process. However, an optional solution is adding my jar to HADOOP_CLASSPATH. But here I want to know is why does DBConfiguration not use "conf.getClassByName" to load the jdbc driver? 2013/4/19 vasanth kumar <[email protected]> > Hi, > > No need to pack mysql packages into your jar. > Option 1: Copy mysql jdbc jar into $HADOOP_HOME/lib. Restart hadoop > daemons. > > Option 2: while executing try : *$hadoop jar your.jar a.b.c.Main -libjar > /path/mysql.jar* > > > On Fri, Apr 19, 2013 at 12:32 PM, Shixiong Zhu <[email protected]> wrote: > >> Hi, >> >> I encountered a ClassNotFoundException when I used DBInputFormat. I >> packaged my codes with mysql-connector-java-5.1.24.jar to abc.jar. Then I >> run the following command to run: >> >> hadoop jar abc.jar a.b.c.Main >> >> But it is crashed by the following exception: >> >> Notes: java.lang.RuntimeException: java.lang.RuntimeException: >> java.lang.ClassNotFoundException: com.mysql.jdbc.Driver >> at >> org.apache.hadoop.mapreduce.lib.db.DBInputFormat.setConf(DBInputFormat.java:158) >> at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:70) >> at >> org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:130) >> at org.apache.hadoop.mapred.JobClient.writeNewSplits(JobClient.java:959) >> at org.apache.hadoop.mapred.JobClient.writeSplits(JobClient.java:979) >> at org.apache.hadoop.mapred.JobClient.access$500(JobClient.java:170) >> at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:891) >> at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:844) >> at java.security.AccessController.doPrivileged(Native Method) >> at javax.security.auth.Subject.doAs(Subject.java:416) >> at >> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1232) >> at >> org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:844) >> at org.apache.hadoop.mapreduce.Job.submit(Job.java:481) >> at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:511) >> ... >> at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) >> at >> com.microstrategy.etl.alert.feedback.FeedbackDumpTask.main(FeedbackDumpTask.java:17) >> 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:616) >> at org.apache.hadoop.util.RunJar.main(RunJar.java:208) >> Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: >> com.mysql.jdbc.Driver >> at >> org.apache.hadoop.mapreduce.lib.db.DBInputFormat.getConnection(DBInputFormat.java:184) >> at >> org.apache.hadoop.mapreduce.lib.db.DBInputFormat.setConf(DBInputFormat.java:152) >> ... 25 more >> Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver >> 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) >> at java.lang.Class.forName0(Native Method) >> at java.lang.Class.forName(Class.java:186) >> at >> org.apache.hadoop.mapreduce.lib.db.DBConfiguration.getConnection(DBConfiguration.java:143) >> at >> org.apache.hadoop.mapreduce.lib.db.DBInputFormat.getConnection(DBInputFormat.java:178) >> ... 26 more >> >> I read the DBConfiguration.java file, and found it uses "Class.forName" >> to load "com.mysql.jdbc.Driver": >> >> /** Returns a connection object to the DB. >> * @throws ClassNotFoundException >> * @throws SQLException */ >> public Connection getConnection() >> throws ClassNotFoundException, SQLException { >> Connection connection; >> >> Class.forName(conf.get(DBConfiguration.DRIVER_CLASS_PROPERTY)); >> >> I think that's why my application crashed. The classloader of >> DBConfiguration is sun.misc.Launcher$AppClassLoader, but >> "com.mysql.jdbc.Driver" exists in the URLClassLoader created by >> org.apache.hadoop.util.RunJar. >> So "Class.forName" invoked by DBConfiguration can not find >> "com.mysql.jdbc.Driver" in the sun.misc.Launcher$AppClassLoader. >> >> Why does DBConfiguration not use "conf.getClassByName" to load the jdbc >> driver? If DBConfiguration use the following code, it can work in such >> situation. >> >> conf.getClassByName(conf.get(DBConfiguration.DRIVER_CLASS_PROPERTY)); >> >> Is there any similar issue? Sorry that I can not find any JIRA about this >> problem. >> >> -- >> Thanks, >> Shixiong Zhu >> > > > > -- > Regards > Vasanth kumar RJ >
