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From "thushara wijeratna (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-6109) Handle large (several MB) text input lines in a reasonable amount of time
Date Thu, 25 Jun 2009 23:32:07 GMT
Handle large (several MB) text input lines in a reasonable amount of time
-------------------------------------------------------------------------

                 Key: HADOOP-6109
                 URL: https://issues.apache.org/jira/browse/HADOOP-6109
             Project: Hadoop Common
          Issue Type: Improvement
          Components: util
    Affects Versions: 0.19.0
         Environment: Linux 2.6 kernel, java 1.6 AMD Dual-Core Opteron 2.6GHz with 1M L1/L2
cache 1.8G RAM
            Reporter: thushara wijeratna


problem:
=======
hadoop was timing out on a simple pass-through job (with the default 10 min timeout)

cause:
=====
i hunted this down to how Text lines are being processed inside org.apache.hadoop.util.LineReader.
i have a fix, a task that took more than 20 minutes and still failed to complete, completes
with this fix in under 30 s.
i attach the patch (for trunk)

the problem traces:
================

hadoop version: 0.19.0
userlogs on slave node:

2009-05-29 13:57:33,551 WARN org.apache.hadoop.mapred.TaskRunner: Parent died.  Exiting attempt_200905281652_0013_m_000006_1
[root@domU-12-31-38-01-7C-92 attempt_200905281652_0013_m_000006_1]#

tellingly, the last input line processed right before this WARN is 19K. (i log the full input
line in the map function for debugging)

output on map-reduce task:

Task attempt_200905281652_0013_m_000006_2 failed to report status for 600 seconds. Killing!
09/05/29 14:08:01 INFO mapred.JobClient:  map 99% reduce 32%
09/05/29 14:18:05 INFO mapred.JobClient:  map 98% reduce 32%
java.io.IOException: Job failed!
    at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1217)
    at com.adxpose.data.mr.DailyHeatmapAggregator.run(DailyHeatmapAggregator.java:547)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
    at com.adxpose.data.mr.DailyHeatmapAggregator.main(DailyHeatmapAggregator.java:553)
    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:165)
    at org.apache.hadoop.mapred.JobShell.run(JobShell.java:54)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
    at org.apache.hadoop.mapred.JobShell.main(JobShell.java:68)

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