PredictionIO start server throws Unsupported class version errors in centos 6

Question

I have installed predictionIO in RHEL 6.6. But when I start pio with pio-start-all I am getting error as follows

$ pio-start-all 
Starting Elasticsearch...
Starting HBase...
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/hadoop/hbase/util/HBaseConfTool : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:643)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
Could not find the main class: org.apache.hadoop.hbase.util.HBaseConfTool. Program will exit.
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/hadoop/hbase/zookeeper/ZKServerTool : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:643)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
Could not find the main class: org.apache.hadoop.hbase.zookeeper.ZKServerTool. Program will exit.
starting master, logging to /home/itdevel/PredictionIO/vendors/hbase-1.0.0/bin/../logs/hbase-itdevel-master-Puget-129416.out
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/hadoop/hbase/master/HMaster : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:643)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
starting regionserver, logging to /home/itdevel/PredictionIO/vendors/hbase-1.0.0/bin/../logs/hbase-itdevel-1-regionserver-Puget-129416.out
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/hadoop/hbase/regionserver/HRegionServer : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:643)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
Waiting 10 seconds for HBase to fully initialize...
Starting PredictionIO Event Server...

pio server is not started after all. I have created a new user and installed java for that user as the system wide java installation is 1.6. I have successfully installed java 1.8 for the new user

$java -version
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)

I have edited path in pio-start-all to point to my java installation since pio-start-all cannot find jdp. I have checked my java path.

 $echo $JAVA_HOME
/home/me/jdk1.8.0_45/bin

After changing path in pio-start-all from /home/me/jdk1.8.0_45/bin/bin to /home/me/jdk1.8.0_45/bin jdp error was fixed but I am struck at current error. I have installed pio in a couple of ubuntu machines and servers, customized pio to meet my custom engine template requirements and it is running without issues. Do predictionIO supports Redhat? Hope this is all the error trace you needed. thanks in advance :)

Answer 1

The java.lang.UnsupportedClassVersionError definitely thrown when pio-start-all or other scripts it runs still use earlier version of Java than required by predictionIO. You must thoroughly check what Java version is used.

One of the way is to try under root:

alternatives --config java

You will have something like this

There are 2 choices for the alternative java (providing /usr/bin/java).

Selection    Path                                            Priority   Status
------------------------------------------------------------
* 0            /usr/lib/jvm/java-7-oracle/jre/bin/java          1062      auto mode
  1            /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java   1061      manual mode
  2            /usr/lib/jvm/java-7-oracle/jre/bin/java          1062      manual mode

Press enter to keep the current choice[*], or type selection number:

Choose the latest Java version.

You can configure JAVA_HOME as well. Please, check the instructions for RedHat.

Answer 2

I have solved the issue. In my case hbase was pointing to the wrong java installation. After updating JAVA_HOME in /home/me/PredictionIO/vendors/hbase-1.0.0/bin/hbase hbase was up and running and my issue was fixed. Thanks for the support :)