Grokbase Groups Pig user March 2013
FAQ
(to explain why it happens with the group by -- it's trying to estimate the
number of reducers you need by looking at the size of the input data. If
you remove the group by, there is no reduce step, so no estimation needed.
If you store, then load and group, presumably whatever null-returning bug
in S3 this thing tickles isn't being triggered).

On Tue, Mar 12, 2013 at 2:55 PM, Dmitriy Ryaboy wrote:

Sounds like a bug in the S3 implementation of FileSystem? Does this happen
with pig 0.10 or 0.11?


On Mon, Mar 11, 2013 at 12:11 AM, Yang wrote:

the following code gave null pointer exception


---------------------------------------------------------------------------------------

rbl_raw = load 's3://mybucket/rbl-logs/{2013/03/06,2013/03/05}' AS
(line:chararray);

rbl = FOREACH rbl_raw GENERATE FLATTEN(loadrbl(line)) AS (x:chararray,
y:chararray);

seo_rbl = FILTER rbl BY x IS NOT NULL AND y == 'seo_google';

rbl1 = GROUP seo_rbl BY x;

STORE rbl1 INTO '/user/hadoop/blah'


-------------------------------------------------------------------------------




Pig Stack Trace
---------------
ERROR 2017: Internal error creating job configuration.


org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobCreationException:
ERROR 2017: Internal error creating job configuration.
at

org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler.getJob(JobControlCompiler.java:750)
at

org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler.compile(JobControlCompiler.java:267)
at

org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher.launchPig(MapReduceLauncher.java:151)
at org.apache.pig.PigServer.launchPlan(PigServer.java:1313)
at
org.apache.pig.PigServer.executeCompiledLogicalPlan(PigServer.java:1298)
at org.apache.pig.PigServer.execute(PigServer.java:1288)
at org.apache.pig.PigServer.executeBatch(PigServer.java:360)
at
org.apache.pig.tools.grunt.GruntParser.executeBatch(GruntParser.java:132)
at

org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:193)
at

org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:165)
at org.apache.pig.tools.grunt.Grunt.exec(Grunt.java:84)
at org.apache.pig.Main.run(Main.java:568)
at org.apache.pig.Main.main(Main.java:114)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at

sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at

sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:187)
Caused by: java.lang.NullPointerException
at org.apache.hadoop.fs.FileSystem.globStatus(FileSystem.java:994)
at org.apache.hadoop.fs.FileSystem.globStatus(FileSystem.java:967)
at

org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler.getTotalInputFileSize(JobControlCompiler.java:798)
at

org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler.estimateNumberOfReducers(JobControlCompiler.java:773)
at

org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler.getJob(JobControlCompiler.java:611)
... 17 more

================================================================================



version of pig is 0.9.2:
hadoop@ip-10-147-131-60:/mnt/run$ pig -version


Apache Pig version 0.9.2-amzn (rexported)






the weird thing is that if I take out the GROUP BY, it works fine; if I
take out the glob in the initial LOAD statement, and just load one dir, it
works fine; also if I load both dirs with the glob, then store the loaded
result after the loadrbl() UDF, then store the result in a intermediate
dir; then load the intermediate result and continue all the original
computation all the way to GROUP BY, it works fine too.


so why does the GROUP BY have a problem with the glob above? while they
are far apart and the intermediate steps all worked fine?


thanks
Yang

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postedMar 11, '13 at 7:11a
activeMar 12, '13 at 9:57p
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