[PIG-2429] Better error message in pig_*.log

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.9.0
• Fix Version/s: 0.9.0
• Assignee: xuting zhao
• Reporter: Anitha Raju
• Created: 14/Dec/11 11:40
• Updated: 20/Dec/11 20:00
• Resolved: 20/Dec/11 20:00

Description

Hi,

The below script sometimes fails giving null error message and some times with correct error message in the pig_*.log

Script

register 'a.py' using jython as test;
A = load 'test.txt' as (x:chararray);
B = foreach A generate
        test.a(x) as y;
C = group B by (y);
store C into 'C';

where a.py is

@outputSchema("n:chararray")
def a(n):
  n = n.lower();
  return n;

input- test.txt
=======
a

=======

I have not put null check in a.py so that the script would error out.

This script when run with 0.9 version, fails printing in the pig_*.log either null error message or the correct error message

Null Error message

Pig Stack Trace
---------------
ERROR 2244: Job failed, hadoop does not return any error message

org.apache.pig.backend.executionengine.ExecException: ERROR 2244: Job failed, hadoop does not return any error message
        at org.apache.pig.tools.grunt.GruntParser.executeBatch(GruntParser.java:139)
        at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:192)
        at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:164)
        at org.apache.pig.tools.grunt.Grunt.exec(Grunt.java:81)
        at org.apache.pig.Main.run(Main.java:561)
        at org.apache.pig.Main.main(Main.java:111)

Correct Error message

Backend error message
---------------------
org.apache.pig.backend.executionengine.ExecException: ERROR 0: Error executing function
        at org.apache.pig.scripting.jython.JythonFunction.exec(JythonFunction.java:106)
        at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POUserFunc.getNext(POUserFunc.java:216)
        at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POUserFunc.getNext(POUserFunc.java:305)
        at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.getNext(PhysicalOperator.java:322)
        at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.processPlan(POForEach.java:332)
        at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.getNext(POForEach.java:284)
        at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.processInput(PhysicalOperator.java:290)
        at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POLocalRearrange.getNext(POLocalRearrange.java:256)
        at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapBase.runPipeline(PigGenericMapBase.java:267)
        at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapBase.map(PigGenericMapBase.java:262)
        at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapBase.map(PigGenericMapBase.java:64)
        at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
        at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
        at org.apache.hadoop.mapred.Child$4.run(Child.java:261)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:396)
        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
        at org.apache.hadoop.mapred.Child.main(Child.java:255)
Caused by: Traceback (most recent call last):
  File "a.py", line 5, in n
AttributeError: 'NoneType' object has no attribute 'lower'

        at org.python.core.PyException.fillInStackTrace(PyException.java:70)
        at java.lang.Throwable.<init>(Throwable.java:181)
        at java.lang.Exception.<init>(Exception.java:29)
        at java.lang.RuntimeException.<init>(RuntimeException.java:32)
        at org.python.core.PyException.<init>(PyException.java:46)
        at org.python.core.PyException.<init>(PyException.java:43)
        at org.python.core.PyException.<init>(PyException.java:61)
        at org.python.core.Py.AttributeError(Py.java:145)
        at org.python.core.PyObject.noAttributeError(PyObject.java:936)
        at org.python.core.PyObject.__getattr__(PyObject.java:931)
        at org.python.pycode._pyx3.n$1(a.py:6)
        at org.python.pycode._pyx3.call_function(a.py)
        at org.python.core.PyTableCode.call(PyTableCode.java:165)
        at org.python.core.PyBaseCode.call(PyBaseCode.java:297)
        at org.python.core.PyFunction.__call__(PyFunction.java:370)
        at org.python.core.PyFunction.__call__(PyFunction.java:360)
        at org.python.core.PyFunction.__call__(PyFunction.java:355)
        at org.apache.pig.scripting.jython.JythonFunction.exec(JythonFunction.java:103)
        ... 18 more
		

Putting a couple of sysout in the code, i found it was happening when in Launcher.getStats

TaskReport[] mapRep = jobClient.getMapTaskReports(MRJobID);
getErrorMessages(mapRep, "map", errNotDbg, pigContext);
totalHadoopTimeSpent += computeTimeSpent(mapRep);

whenever mapRed becomes null, it gives null error message.

Can it be made better?

Regards,
Anitha

Issue Links

• relates to: PIG-1829 "0" value seen in PigStat's map/reduce runtime, even when the job is successful