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From "Olga Natkovich (JIRA)" <j...@apache.org>
Subject [jira] Created: (PIG-250) Pig is broken with speculative execution
Date Wed, 28 May 2008 00:45:47 GMT
Pig is broken with speculative execution

                 Key: PIG-250
                 URL: https://issues.apache.org/jira/browse/PIG-250
             Project: Pig
          Issue Type: Bug
            Reporter: Olga Natkovich

If I have speculative execution turned on, the following script fails:

a = load 'studenttab20m' as (name, age, gpa);
b = load 'votertab10k' as (name, age, registration, contributions);
c = filter a by age < '50';
d = filter b by age < '50';
e = cogroup c by (name, age), d by (name, age) parallel 10;
f = foreach e generate flatten(c), flatten(d) parallel 10;
g = group f by registration parallel 10;
h = foreach g generate group, SUM(f.d::contributions) parallel 10;
i = order h by ($1, $0);
store i into 'out';

I traced this to the fact that the first MR job produces one or more empty outputs from the
reducer. This happened on the reducers that happened to have second task running.

I am not sure what the issue is and I am working with hadoop guys to investigate. Until this
issue is resolved, I would like to trun speculative execution off.

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