[HADOOP-3706] CompositeInputFormat: Unable to wrap custom InputFormats

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.17.0
• Fix Version/s: 0.18.0
• Hadoop Flags: Reviewed
• Assignee: Jingkei Ly
• Reporter: Jingkei Ly
• Created: 07/Jul/08 17:03
• Updated: 08/Jul/09 16:52
• Resolved: 09/Jul/08 01:35

Description

I am unable to use a custom InputFormat with the CompositeInputFormat as the classloader that is used by Parser is unable to find my class.

To reproduce (although I've got an example program, if that's preferred?):
1) Create a custom InputFormat (I made a copy of SequenceFileInputFormat and named it MyInputFormat)
2) Create a program using CompositeInputFormat [Set "mapred.join.expr" to CompositeInputFormat.compose("outer", MyInputFormat.class, plist)]
3) Create jar file
4) Run job (must be via the jar - the problem cannot be reproduced in Local mode)

Doing so causes the following exception:

Caused by: java.io.IOException
	at org.apache.hadoop.mapred.join.Parser$WNode.parse(Parser.java:274)
	at org.apache.hadoop.mapred.join.Parser.reduce(Parser.java:463)
	at org.apache.hadoop.mapred.join.Parser.parse(Parser.java:481)
	at org.apache.hadoop.mapred.join.CompositeInputFormat.setFormat(CompositeInputFormat.java:77)
	at org.apache.hadoop.mapred.join.CompositeInputFormat.validateInput(CompositeInputFormat.java:118)

Caused by: java.lang.ClassNotFoundException: my.custom.input.format.MyInputFormat
	at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:164)
	at org.apache.hadoop.mapred.join.Parser$WNode.parse(Parser.java:270)

Should the line on Parser.java:271 be something like:

jobConf.getClassByName(sb.toString());

instead of:

Class.forName(sb.toString()).asSubclass(InputFormat.class)

to ensure the correct classloader is used?