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
