[PIG-5310] MergeJoin throwing NullPointer Exception

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.18.0
• Hadoop Flags: Reviewed
• Assignee: Satish Saley
• Reporter: Satish Saley
• Created: 25/Oct/17 23:15
• Updated: 29/Nov/17 19:39
• Resolved: 29/Nov/17 19:39

Description

Merge join throws NullPointerException if left input's first key doesn't exist in right input and if it is smaller than first key of right input.
For ex

left	right
1	3
1	5
1

Error we get -

ERROR 2998: Unhandled internal error. Vertex failed, vertexName=scope-16, vertexId=vertex_1509400259446_0001_1_02, diagnostics=[Task failed, taskId=task_1509400259446_0001_1_02_000000, diagnostics=[TaskAttempt 0 failed, info=[Error: Error while running task ( failure ) : attempt_1509400259446_0001_1_02_000000_0:java.lang.NullPointerException
	at java.lang.Integer.compareTo(Integer.java:1216)
	at java.lang.Integer.compareTo(Integer.java:52)
	at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POMergeJoin.getNextTuple(POMergeJoin.java:525)
	at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.processInput(PhysicalOperator.java:305)
	at org.apache.pig.backend.hadoop.executionengine.tez.plan.operator.POStoreTez.getNextTuple(POStoreTez.java:123)
	at org.apache.pig.backend.hadoop.executionengine.tez.runtime.PigProcessor.runPipeline(PigProcessor.java:416)
	at org.apache.pig.backend.hadoop.executionengine.tez.runtime.PigProcessor.run(PigProcessor.java:281)
	at org.apache.tez.runtime.LogicalIOProcessorRuntimeTask.run(LogicalIOProcessorRuntimeTask.java:370)
	at org.apache.tez.runtime.task.TaskRunner2Callable$1.run(TaskRunner2Callable.java:73)
	at org.apache.tez.runtime.task.TaskRunner2Callable$1.run(TaskRunner2Callable.java:61)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:422)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1945)
	at org.apache.tez.runtime.task.TaskRunner2Callable.callInternal(TaskRunner2Callable.java:61)
	at org.apache.tez.runtime.task.TaskRunner2Callable.callInternal(TaskRunner2Callable.java:37)
	at org.apache.tez.common.CallableWithNdc.call(CallableWithNdc.java:36)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

Here, the key used in join is an integer. Integer.compareTo(other) method throws null pointer exception if comparison is made against null.