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POBroken Pipe Error causes streaming Elastic MapReduce job on AWS to fail
 

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  1. POBroken Pipe Error causes streaming Elastic MapReduce job on AWS to fail
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    <p>Everything works fine locally when I do as follows:</p> <pre><code>cat input | python mapper.py | sort | python reducer.py </code></pre> <p>However, when I run the streaming MapReduce job on AWS Elastic Mapreduce, the job does not complete successfully. The <code>mapper.py</code> runs part way through (I know this because of writing to <code>stderr</code> along the way). The mapper is interrupted by a "Broken Pipe" error, which I'm able to retrieve from the syslog of the task attempt after it fails:</p> <pre><code>java.io.IOException: Broken pipe at java.io.FileOutputStream.writeBytes(Native Method) at java.io.FileOutputStream.write(FileOutputStream.java:282) at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105) at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65) at java.io.BufferedOutputStream.write(BufferedOutputStream.java:109) at java.io.DataOutputStream.write(DataOutputStream.java:90) at org.apache.hadoop.streaming.io.TextInputWriter.writeUTF8(TextInputWriter.java:72) at org.apache.hadoop.streaming.io.TextInputWriter.writeValue(TextInputWriter.java:51) at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:109) at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50) at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36) at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377) at org.apache.hadoop.mapred.Child$4.run(Child.java:255) 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:249) 2012-03-26 07:19:05,400 WARN org.apache.hadoop.streaming.PipeMapRed (main): java.io.IOException: Broken pipe at java.io.FileOutputStream.writeBytes(Native Method) at java.io.FileOutputStream.write(FileOutputStream.java:282) at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105) at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65) at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:123) at java.io.DataOutputStream.flush(DataOutputStream.java:106) at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:579) at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:124) at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50) at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36) at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377) at org.apache.hadoop.mapred.Child$4.run(Child.java:255) 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:249) 2012-03-26 07:19:05,400 INFO org.apache.hadoop.streaming.PipeMapRed (main): mapRedFinished 2012-03-26 07:19:05,400 WARN org.apache.hadoop.streaming.PipeMapRed (main): java.io.IOException: Bad file descriptor at java.io.FileOutputStream.writeBytes(Native Method) at java.io.FileOutputStream.write(FileOutputStream.java:282) at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105) at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65) at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:123) at java.io.DataOutputStream.flush(DataOutputStream.java:106) at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:579) at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:135) at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:57) at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36) at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377) at org.apache.hadoop.mapred.Child$4.run(Child.java:255) 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:249) 2012-03-26 07:19:05,400 INFO org.apache.hadoop.streaming.PipeMapRed (main): mapRedFinished 2012-03-26 07:19:05,405 INFO org.apache.hadoop.streaming.PipeMapRed (Thread-13): MRErrorThread done 2012-03-26 07:19:05,408 INFO org.apache.hadoop.mapred.TaskLogsTruncater (main): Initializing logs' truncater with mapRetainSize=-1 and reduceRetainSize=-1 2012-03-26 07:19:05,519 INFO org.apache.hadoop.io.nativeio.NativeIO (main): Initialized cache for UID to User mapping with a cache timeout of 14400 seconds. 2012-03-26 07:19:05,520 INFO org.apache.hadoop.io.nativeio.NativeIO (main): Got UserName hadoop for UID 106 from the native implementation 2012-03-26 07:19:05,522 WARN org.apache.hadoop.mapred.Child (main): Error running child java.io.IOException: log:null R/W/S=7018/3/0 in:NA [rec/s] out:NA [rec/s] minRecWrittenToEnableSkip_=9223372036854775807 LOGNAME=null HOST=null USER=hadoop HADOOP_USER=null last Hadoop input: |null| last tool output: |text/html 1| Date: Mon Mar 26 07:19:05 UTC 2012 java.io.IOException: Broken pipe at java.io.FileOutputStream.writeBytes(Native Method) at java.io.FileOutputStream.write(FileOutputStream.java:282) at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105) at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65) at java.io.BufferedOutputStream.write(BufferedOutputStream.java:109) at java.io.DataOutputStream.write(DataOutputStream.java:90) at org.apache.hadoop.streaming.io.TextInputWriter.writeUTF8(TextInputWriter.java:72) at org.apache.hadoop.streaming.io.TextInputWriter.writeValue(TextInputWriter.java:51) at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:109) at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50) at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36) at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377) at org.apache.hadoop.mapred.Child$4.run(Child.java:255) 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:249) at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:125) at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50) at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36) at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:441) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:377) at org.apache.hadoop.mapred.Child$4.run(Child.java:255) 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:249) 2012-03-26 07:19:05,525 INFO org.apache.hadoop.mapred.Task (main): Runnning cleanup for the task 2012-03-26 07:19:05,526 INFO org.apache.hadoop.mapred.DirectFileOutputCommitter (main): Nothing to clean up on abort since there are no temporary files written </code></pre> <p>Here is <code>mapper.py</code>. Note that I write to stderr to provide myself with debugging info:</p> <pre><code>#!/usr/bin/env python import sys from warc import ARCFile def main(): warc_file = ARCFile(fileobj=sys.stdin) for web_page in warc_file: print &gt;&gt; sys.stderr, '%s\t%s' % (web_page.header.content_type, 1) #For debugging print '%s\t%s' % (web_page.header.content_type, 1) print &gt;&gt; sys.stderr, 'done' #For debugging if __name__ == "__main__": main() </code></pre> <p>Here is what I get in the stderr for the task attempt when the mapper.py is run:</p> <pre><code>text/html 1 text/html 1 text/html 1 </code></pre> <p>Basically, the loop runs through 3 times and then stops abruptly without python throwing any error. (Note: it <em>should</em> be outputting thousands of lines). Even an uncaught exception should appear in stderr. </p> <p>Because the MapReduce runs completely fine on my local computer, my guess is that this is a problem with how Hadoop is dealing with the output I'm printing from mapper.py. But I'm clueless as to what the problem could be.</p>
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