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Message-ID: <73e5a5310801220930q6d2bbe99l6a72451ca4bbea9c@mail.gmail.com>
Date: Tue, 22 Jan 2008 17:30:22 +0000
From: "Miles Osborne" <miles@inf.ed.ac.uk>
Sender: milesosb@gmail.com
To: core-user@hadoop.apache.org
Subject: Re: Hadoop-2438
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The max heap size for each child was the default,  200M.

Thanks for this tip:  right now i'm playing around with machines which we
mothballed years ago (they have 512M a pop!).  once i put more memory into
them i'll see if this works.

(Hadoop is a great way to breath life into otherwise unloved boxes)

Miles

On 22/01/2008, Arun C Murthy <acm@yahoo-inc.com> wrote:
>
>
> On Jan 22, 2008, at 6:26 AM, Miles Osborne wrote:
>
> > Has there been any progress / a work-around for this?
> >
> > Currently I'm experimenting with Streaming and I've encountered
> > what looks
> > like the same problem as described here:
> >
> > https://issues.apache.org/jira/browse/HADOOP-2438
> >
>
> Uh, I'm not sure how we missed H-2438, but what is ur max heap size
> for the child?
> http://lucene.apache.org/hadoop/docs/r0.15.2/hadoop-
> default.html#mapred.child.java.opts
> Check if it works with -Xmx512m.
>
> I think i need to open a bug to bump the default up to 512M, sigh!
>
> thanks,
> Arun
>
> > So, I get much the same errors (see below).
> >
> > For this particular task, when I replace the mappers and reducers
> > with the
> > identity operation (ie just pass through the data) all is well.  When
> > instead I try to do something more taxing
> > (in this case, gathering together all ngrams with the same prefix),
> > I get
> > these errors.
> >
> > My guess is that this is something to do with caching / buffering,
> > since I
> > presume that when the Stream mapper has real work to do, the
> > associated Java
> > streamer buffers input until the Mapper signals that it can process
> > more
> > data.  If the Mapper is busy, then a lot of data would get cached,
> > causing
> > some internal buffer to overflow.
> >
> > Miles
> >
> >>
> >
> > Date: Tue Jan 22 14:12:28 GMT 2008
> > java.io.IOException: Broken pipe
> >       at java.io.FileOutputStream.writeBytes(Native Method)
> >       at java.io.FileOutputStream.write(FileOutputStream.java:260)
> >       at java.io.BufferedOutputStream.flushBuffer
> > (BufferedOutputStream.java:65)
> >       at java.io.BufferedOutputStream.flush(BufferedOutputStream.java
> :123)
> >       at java.io.BufferedOutputStream.flush(BufferedOutputStream.java
> :124)
> >       at java.io.DataOutputStream.flush(DataOutputStream.java:106)
> >       at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:96)
> >       at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
> >       at org.apache.hadoop.mapred.MapTask.run(MapTask.java:192)
> >       at org.apache.hadoop.mapred.TaskTracker$Child.main
> > (TaskTracker.java:1760)
> >
> >
> >       at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:107)
> >       at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
> >       at org.apache.hadoop.mapred.MapTask.run(MapTask.java:192)
> >       at org.apache.hadoop.mapred.TaskTracker$Child.main
> > (TaskTracker.java:1760)
> >
> > java.io.IOException: MROutput/MRErrThread
> > failed:java.lang.OutOfMemoryError: Java heap space
> >       at java.util.Arrays.copyOf(Arrays.java:2786)
> >       at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
> :94)
> >       at java.io.DataOutputStream.write(DataOutputStream.java:90)
> >       at org.apache.hadoop.io.Text.write(Text.java:243)
> >       at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect
> > (MapTask.java:349)
> >       at org.apache.hadoop.streaming.PipeMapRed$MROutputThread.run
> > (PipeMapRed.java:344)
> >
> >       at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:76)
> >       at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
> >       at org.apache.hadoop.mapred.MapTask.run(MapTask.java:192)
> >       at org.apache.hadoop.mapred.TaskTracker$Child.main
> > (TaskTracker.java:1760)
> >
> > java.io.IOException: MROutput/MRErrThread
> > failed:java.lang.OutOfMemoryError: Java heap space
> >       at java.util.Arrays.copyOf(Arrays.java:2786)
> >       at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
> :94)
> >       at java.io.DataOutputStream.write(DataOutputStream.java:90)
> >       at org.apache.hadoop.io.Text.write(Text.java:243)
> >       at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect
> > (MapTask.java:349)
> >       at org.apache.hadoop.streaming.PipeMapRed$MROutputThread.run
> > (PipeMapRed.java:344)
> >
> >       at org.apache.hadoop.streaming.PipeMapper.map(PipeMapper.java:76)
> >       at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
> >       at org.apache.hadoop.mapred.MapTask.run(MapTask.java:192)
> >       at org.apache.hadoop.mapred.TaskTracker$Child.main
> > (TaskTracker.java:1760)
>
>

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