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Posted to common-user@hadoop.apache.org by Stefan Groschupf <sg...@101tec.com> on 2008/03/16 04:37:08 UTC
[memory leak?] Re: MapReduce failure
Hi there,
we see the same situation and browsing the posts there are quite a lot
of people running into this OOM problem.
We run a own Mapper and our mapred.child.java.opts is -Xmx3048m, I
think that should be more then enough.
Also I changed io.sort.mb to 10, which had also no impact.
Any ideas what might cause the OutOfMemoryError ?
Thanks.
Stefan
On Mar 9, 2008, at 10:28 PM, Amar Kamat wrote:
> What is the heap size you are using for your tasks? Check
> 'mapred.child.java.opts' in your hadoop-default.xml. Try increasing
> it. This will happen if you try running the random-writer + sort
> examples with default parameters. The maps are not able to spill the
> data to the disk. Btw what version of HADOOP are you using?
> Amar
> On Mon, 10 Mar 2008, Ved Prakash wrote:
>
>> Hi friends,
>>
>> I have made a cluster of 3 machines, one of them is master, and
>> other 2
>> slaves. I executed a mapreduce job on master but after Map, the
>> execution
>> terminates and Reduce doesn't happen. I have checked dfs and no
>> output
>> folder gets created.
>>
>> this is the error I see
>>
>> 08/03/10 10:35:21 INFO mapred.JobClient: Task Id :
>> task_200803101001_0001_m_000064_0, Status : FAILED
>> java.lang.OutOfMemoryError: Java heap space
>> at
>> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
>> :95)
>> 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:347)
>> at org.apache.hadoop.examples.WordCount
>> $MapClass.map(WordCount.java
>> :72)
>> at org.apache.hadoop.examples.WordCount
>> $MapClass.map(WordCount.java
>> :59)
>> 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
>> $Child.main(TaskTracker.java
>> :1787)
>>
>> 08/03/10 10:35:22 INFO mapred.JobClient: map 55% reduce 17%
>> 08/03/10 10:35:31 INFO mapred.JobClient: map 56% reduce 17%
>> 08/03/10 10:35:51 INFO mapred.JobClient: map 57% reduce 17%
>> 08/03/10 10:36:04 INFO mapred.JobClient: map 58% reduce 17%
>> 08/03/10 10:36:07 INFO mapred.JobClient: map 57% reduce 17%
>> 08/03/10 10:36:07 INFO mapred.JobClient: Task Id :
>> task_200803101001_0001_m_000071_0, Status : FAILED
>> java.lang.OutOfMemoryError: Java heap space
>> at
>> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
>> :95)
>> at java.io.DataOutputStream.write(DataOutputStream.java:90)
>> at org.apache.hadoop.io.Text.write(Text.java:243)
>> at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(
>> MapTask.java:347)
>> at org.apache.hadoop.examples.WordCount
>> $MapClass.map(WordCount.java
>> :72)
>> at org.apache.hadoop.examples.WordCount
>> $MapClass.map(WordCount.java
>> :59)
>> 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
>> :1787)
>>
>> though it tries to overcome this problem but the mapreduce
>> application
>> doesn't create output, can anyone tell me why is this happening?
>>
>> Thanks
>>
>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
101tec Inc.
Menlo Park, California, USA
http://www.101tec.com
Re: [memory leak?] Re: MapReduce failure
Posted by Stefan Groschupf <sg...@101tec.com>.
ups sorry I forgot to mention I use 0.16.0. I will try to update to
16.1 tomorrow and see if this helps, but i couldn't find an closed
issue in jira that might be related.
On Mar 15, 2008, at 8:37 PM, Stefan Groschupf wrote:
> Hi there,
>
> we see the same situation and browsing the posts there are quite a
> lot of people running into this OOM problem.
> We run a own Mapper and our mapred.child.java.opts is -Xmx3048m, I
> think that should be more then enough.
> Also I changed io.sort.mb to 10, which had also no impact.
>
> Any ideas what might cause the OutOfMemoryError ?
> Thanks.
> Stefan
>
>
>
>
> On Mar 9, 2008, at 10:28 PM, Amar Kamat wrote:
>
>> What is the heap size you are using for your tasks? Check
>> 'mapred.child.java.opts' in your hadoop-default.xml. Try increasing
>> it. This will happen if you try running the random-writer + sort
>> examples with default parameters. The maps are not able to spill
>> the data to the disk. Btw what version of HADOOP are you using?
>> Amar
>> On Mon, 10 Mar 2008, Ved Prakash wrote:
>>
>>> Hi friends,
>>>
>>> I have made a cluster of 3 machines, one of them is master, and
>>> other 2
>>> slaves. I executed a mapreduce job on master but after Map, the
>>> execution
>>> terminates and Reduce doesn't happen. I have checked dfs and no
>>> output
>>> folder gets created.
>>>
>>> this is the error I see
>>>
>>> 08/03/10 10:35:21 INFO mapred.JobClient: Task Id :
>>> task_200803101001_0001_m_000064_0, Status : FAILED
>>> java.lang.OutOfMemoryError: Java heap space
>>> at
>>> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
>>> :95)
>>> 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:347)
>>> at org.apache.hadoop.examples.WordCount
>>> $MapClass.map(WordCount.java
>>> :72)
>>> at org.apache.hadoop.examples.WordCount
>>> $MapClass.map(WordCount.java
>>> :59)
>>> 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
>>> $Child.main(TaskTracker.java
>>> :1787)
>>>
>>> 08/03/10 10:35:22 INFO mapred.JobClient: map 55% reduce 17%
>>> 08/03/10 10:35:31 INFO mapred.JobClient: map 56% reduce 17%
>>> 08/03/10 10:35:51 INFO mapred.JobClient: map 57% reduce 17%
>>> 08/03/10 10:36:04 INFO mapred.JobClient: map 58% reduce 17%
>>> 08/03/10 10:36:07 INFO mapred.JobClient: map 57% reduce 17%
>>> 08/03/10 10:36:07 INFO mapred.JobClient: Task Id :
>>> task_200803101001_0001_m_000071_0, Status : FAILED
>>> java.lang.OutOfMemoryError: Java heap space
>>> at
>>> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
>>> :95)
>>> at java.io.DataOutputStream.write(DataOutputStream.java:90)
>>> at org.apache.hadoop.io.Text.write(Text.java:243)
>>> at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(
>>> MapTask.java:347)
>>> at org.apache.hadoop.examples.WordCount
>>> $MapClass.map(WordCount.java
>>> :72)
>>> at org.apache.hadoop.examples.WordCount
>>> $MapClass.map(WordCount.java
>>> :59)
>>> 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
>>> :1787)
>>>
>>> though it tries to overcome this problem but the mapreduce
>>> application
>>> doesn't create output, can anyone tell me why is this happening?
>>>
>>> Thanks
>>>
>>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 101tec Inc.
> Menlo Park, California, USA
> http://www.101tec.com
>
>
>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
101tec Inc.
Menlo Park, California, USA
http://www.101tec.com
RE: [memory leak?] Re: MapReduce failure
Posted by Devaraj Das <dd...@yahoo-inc.com>.
Wordcount doesn't work? Which platform are you on? I just ran the wordcount
on a RHEL linux machine with hadoop-0.16.0 and that worked, and my -Xmx is
512m.
Could you pls share your config file (hadoop-site.xml) as well?
> -----Original Message-----
> From: Stefan Groschupf [mailto:sg@101tec.com]
> Sent: Sunday, March 16, 2008 12:46 PM
> To: core-user@hadoop.apache.org
> Subject: Re: [memory leak?] Re: MapReduce failure
>
> I do not instantiate 3 GB of objects, that is for sure. The
> wordcount example does not run anymore so I dont think this
> is something releated to my code, beside the wordcount
> example many other users report the same problem:
> See:
> http://markmail.org/search/?q=org.apache.hadoop.mapred.MapTask
> %24MapOutputBuffer.collect+order%3Adate-backward
> Thanks for your help!
>
> Stefan
>
>
> On Mar 15, 2008, at 11:02 PM, Devaraj Das wrote:
>
> > It might have something to do with your application itself. By any
> > chance are you doing a lot of huge object allocation (directly or
> > indirectly) within the map method? Which version of hadoop
> are you on?
> >
> >> -----Original Message-----
> >> From: Stefan Groschupf [mailto:sg@101tec.com]
> >> Sent: Sunday, March 16, 2008 9:07 AM
> >> To: core-user@hadoop.apache.org
> >> Subject: [memory leak?] Re: MapReduce failure
> >>
> >> Hi there,
> >>
> >> we see the same situation and browsing the posts there are quite a
> >> lot of people running into this OOM problem.
> >> We run a own Mapper and our mapred.child.java.opts is -Xmx3048m, I
> >> think that should be more then enough.
> >> Also I changed io.sort.mb to 10, which had also no impact.
> >>
> >> Any ideas what might cause the OutOfMemoryError ?
> >> Thanks.
> >> Stefan
> >>
> >>
> >>
> >>
> >> On Mar 9, 2008, at 10:28 PM, Amar Kamat wrote:
> >>
> >>> What is the heap size you are using for your tasks? Check
> >>> 'mapred.child.java.opts' in your hadoop-default.xml. Try
> increasing
> >>> it. This will happen if you try running the random-writer + sort
> >>> examples with default parameters. The maps are not able to
> >> spill the
> >>> data to the disk. Btw what version of HADOOP are you using?
> >>> Amar
> >>> On Mon, 10 Mar 2008, Ved Prakash wrote:
> >>>
> >>>> Hi friends,
> >>>>
> >>>> I have made a cluster of 3 machines, one of them is
> >> master, and other
> >>>> 2 slaves. I executed a mapreduce job on master but after
> Map, the
> >>>> execution terminates and Reduce doesn't happen. I have
> checked dfs
> >>>> and no output folder gets created.
> >>>>
> >>>> this is the error I see
> >>>>
> >>>> 08/03/10 10:35:21 INFO mapred.JobClient: Task Id :
> >>>> task_200803101001_0001_m_000064_0, Status : FAILED
> >>>> java.lang.OutOfMemoryError: Java heap space
> >>>> at
> >>>> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
> >>>> :95)
> >>>> 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:347)
> >>>> at org.apache.hadoop.examples.WordCount
> >>>> $MapClass.map(WordCount.java
> >>>> :72)
> >>>> at org.apache.hadoop.examples.WordCount
> >>>> $MapClass.map(WordCount.java
> >>>> :59)
> >>>> 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
> >>>> $Child.main(TaskTracker.java
> >>>> :1787)
> >>>>
> >>>> 08/03/10 10:35:22 INFO mapred.JobClient: map 55% reduce
> >> 17% 08/03/10
> >>>> 10:35:31 INFO mapred.JobClient: map 56% reduce 17%
> >> 08/03/10 10:35:51
> >>>> INFO mapred.JobClient: map 57% reduce 17% 08/03/10 10:36:04 INFO
> >>>> mapred.JobClient: map 58% reduce 17% 08/03/10 10:36:07 INFO
> >>>> mapred.JobClient: map 57% reduce 17% 08/03/10 10:36:07 INFO
> >>>> mapred.JobClient: Task Id :
> >>>> task_200803101001_0001_m_000071_0, Status : FAILED
> >>>> java.lang.OutOfMemoryError: Java heap space
> >>>> at
> >>>> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
> >>>> :95)
> >>>> at java.io.DataOutputStream.write(DataOutputStream.java:90)
> >>>> at org.apache.hadoop.io.Text.write(Text.java:243)
> >>>> at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(
> >>>> MapTask.java:347)
> >>>> at org.apache.hadoop.examples.WordCount
> >>>> $MapClass.map(WordCount.java
> >>>> :72)
> >>>> at org.apache.hadoop.examples.WordCount
> >>>> $MapClass.map(WordCount.java
> >>>> :59)
> >>>> 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
> >>>> :1787)
> >>>>
> >>>> though it tries to overcome this problem but the mapreduce
> >>>> application doesn't create output, can anyone tell me
> why is this
> >>>> happening?
> >>>>
> >>>> Thanks
> >>>>
> >>>
> >>
> >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> 101tec Inc.
> >> Menlo Park, California, USA
> >> http://www.101tec.com
> >>
> >>
> >>
> >
> >
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 101tec Inc.
> Menlo Park, California, USA
> http://www.101tec.com
>
>
>
Re: [memory leak?] Re: MapReduce failure
Posted by Stefan Groschupf <sg...@101tec.com>.
I do not instantiate 3 GB of objects, that is for sure. The wordcount
example does not run anymore so I dont think this is something
releated to my code, beside the wordcount example many other users
report the same problem:
See:
http://markmail.org/search/?q=org.apache.hadoop.mapred.MapTask%24MapOutputBuffer.collect+order%3Adate-backward
Thanks for your help!
Stefan
On Mar 15, 2008, at 11:02 PM, Devaraj Das wrote:
> It might have something to do with your application itself. By any
> chance
> are you doing a lot of huge object allocation (directly or indirectly)
> within the map method? Which version of hadoop are you on?
>
>> -----Original Message-----
>> From: Stefan Groschupf [mailto:sg@101tec.com]
>> Sent: Sunday, March 16, 2008 9:07 AM
>> To: core-user@hadoop.apache.org
>> Subject: [memory leak?] Re: MapReduce failure
>>
>> Hi there,
>>
>> we see the same situation and browsing the posts there are
>> quite a lot of people running into this OOM problem.
>> We run a own Mapper and our mapred.child.java.opts is
>> -Xmx3048m, I think that should be more then enough.
>> Also I changed io.sort.mb to 10, which had also no impact.
>>
>> Any ideas what might cause the OutOfMemoryError ?
>> Thanks.
>> Stefan
>>
>>
>>
>>
>> On Mar 9, 2008, at 10:28 PM, Amar Kamat wrote:
>>
>>> What is the heap size you are using for your tasks? Check
>>> 'mapred.child.java.opts' in your hadoop-default.xml. Try increasing
>>> it. This will happen if you try running the random-writer + sort
>>> examples with default parameters. The maps are not able to
>> spill the
>>> data to the disk. Btw what version of HADOOP are you using?
>>> Amar
>>> On Mon, 10 Mar 2008, Ved Prakash wrote:
>>>
>>>> Hi friends,
>>>>
>>>> I have made a cluster of 3 machines, one of them is
>> master, and other
>>>> 2 slaves. I executed a mapreduce job on master but after Map, the
>>>> execution terminates and Reduce doesn't happen. I have checked dfs
>>>> and no output folder gets created.
>>>>
>>>> this is the error I see
>>>>
>>>> 08/03/10 10:35:21 INFO mapred.JobClient: Task Id :
>>>> task_200803101001_0001_m_000064_0, Status : FAILED
>>>> java.lang.OutOfMemoryError: Java heap space
>>>> at
>>>> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
>>>> :95)
>>>> 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:347)
>>>> at org.apache.hadoop.examples.WordCount
>>>> $MapClass.map(WordCount.java
>>>> :72)
>>>> at org.apache.hadoop.examples.WordCount
>>>> $MapClass.map(WordCount.java
>>>> :59)
>>>> 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
>>>> $Child.main(TaskTracker.java
>>>> :1787)
>>>>
>>>> 08/03/10 10:35:22 INFO mapred.JobClient: map 55% reduce
>> 17% 08/03/10
>>>> 10:35:31 INFO mapred.JobClient: map 56% reduce 17%
>> 08/03/10 10:35:51
>>>> INFO mapred.JobClient: map 57% reduce 17% 08/03/10 10:36:04 INFO
>>>> mapred.JobClient: map 58% reduce 17% 08/03/10 10:36:07 INFO
>>>> mapred.JobClient: map 57% reduce 17% 08/03/10 10:36:07 INFO
>>>> mapred.JobClient: Task Id :
>>>> task_200803101001_0001_m_000071_0, Status : FAILED
>>>> java.lang.OutOfMemoryError: Java heap space
>>>> at
>>>> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
>>>> :95)
>>>> at java.io.DataOutputStream.write(DataOutputStream.java:90)
>>>> at org.apache.hadoop.io.Text.write(Text.java:243)
>>>> at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(
>>>> MapTask.java:347)
>>>> at org.apache.hadoop.examples.WordCount
>>>> $MapClass.map(WordCount.java
>>>> :72)
>>>> at org.apache.hadoop.examples.WordCount
>>>> $MapClass.map(WordCount.java
>>>> :59)
>>>> 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
>>>> :1787)
>>>>
>>>> though it tries to overcome this problem but the mapreduce
>>>> application doesn't create output, can anyone tell me why is this
>>>> happening?
>>>>
>>>> Thanks
>>>>
>>>
>>
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> 101tec Inc.
>> Menlo Park, California, USA
>> http://www.101tec.com
>>
>>
>>
>
>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
101tec Inc.
Menlo Park, California, USA
http://www.101tec.com
RE: [memory leak?] Re: MapReduce failure
Posted by Devaraj Das <dd...@yahoo-inc.com>.
It might have something to do with your application itself. By any chance
are you doing a lot of huge object allocation (directly or indirectly)
within the map method? Which version of hadoop are you on?
> -----Original Message-----
> From: Stefan Groschupf [mailto:sg@101tec.com]
> Sent: Sunday, March 16, 2008 9:07 AM
> To: core-user@hadoop.apache.org
> Subject: [memory leak?] Re: MapReduce failure
>
> Hi there,
>
> we see the same situation and browsing the posts there are
> quite a lot of people running into this OOM problem.
> We run a own Mapper and our mapred.child.java.opts is
> -Xmx3048m, I think that should be more then enough.
> Also I changed io.sort.mb to 10, which had also no impact.
>
> Any ideas what might cause the OutOfMemoryError ?
> Thanks.
> Stefan
>
>
>
>
> On Mar 9, 2008, at 10:28 PM, Amar Kamat wrote:
>
> > What is the heap size you are using for your tasks? Check
> > 'mapred.child.java.opts' in your hadoop-default.xml. Try increasing
> > it. This will happen if you try running the random-writer + sort
> > examples with default parameters. The maps are not able to
> spill the
> > data to the disk. Btw what version of HADOOP are you using?
> > Amar
> > On Mon, 10 Mar 2008, Ved Prakash wrote:
> >
> >> Hi friends,
> >>
> >> I have made a cluster of 3 machines, one of them is
> master, and other
> >> 2 slaves. I executed a mapreduce job on master but after Map, the
> >> execution terminates and Reduce doesn't happen. I have checked dfs
> >> and no output folder gets created.
> >>
> >> this is the error I see
> >>
> >> 08/03/10 10:35:21 INFO mapred.JobClient: Task Id :
> >> task_200803101001_0001_m_000064_0, Status : FAILED
> >> java.lang.OutOfMemoryError: Java heap space
> >> at
> >> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
> >> :95)
> >> 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:347)
> >> at org.apache.hadoop.examples.WordCount
> >> $MapClass.map(WordCount.java
> >> :72)
> >> at org.apache.hadoop.examples.WordCount
> >> $MapClass.map(WordCount.java
> >> :59)
> >> 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
> >> $Child.main(TaskTracker.java
> >> :1787)
> >>
> >> 08/03/10 10:35:22 INFO mapred.JobClient: map 55% reduce
> 17% 08/03/10
> >> 10:35:31 INFO mapred.JobClient: map 56% reduce 17%
> 08/03/10 10:35:51
> >> INFO mapred.JobClient: map 57% reduce 17% 08/03/10 10:36:04 INFO
> >> mapred.JobClient: map 58% reduce 17% 08/03/10 10:36:07 INFO
> >> mapred.JobClient: map 57% reduce 17% 08/03/10 10:36:07 INFO
> >> mapred.JobClient: Task Id :
> >> task_200803101001_0001_m_000071_0, Status : FAILED
> >> java.lang.OutOfMemoryError: Java heap space
> >> at
> >> java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java
> >> :95)
> >> at java.io.DataOutputStream.write(DataOutputStream.java:90)
> >> at org.apache.hadoop.io.Text.write(Text.java:243)
> >> at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(
> >> MapTask.java:347)
> >> at org.apache.hadoop.examples.WordCount
> >> $MapClass.map(WordCount.java
> >> :72)
> >> at org.apache.hadoop.examples.WordCount
> >> $MapClass.map(WordCount.java
> >> :59)
> >> 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
> >> :1787)
> >>
> >> though it tries to overcome this problem but the mapreduce
> >> application doesn't create output, can anyone tell me why is this
> >> happening?
> >>
> >> Thanks
> >>
> >
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 101tec Inc.
> Menlo Park, California, USA
> http://www.101tec.com
>
>
>