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Posted to user@cassandra.apache.org by cs...@orange.com on 2013/05/03 17:24:33 UTC

Hadoop jobs and data locality

Hi,

I'm using Pig to calculate the sum of a columns from a columnfamily (scan of all rows) and I've read that input data locality is supported at http://wiki.apache.org/cassandra/HadoopSupport
However when I execute my Pig script Hadoop assigns only one mapper to the task and not one mapper on each node (replication factor = 1).  FYI, I've 8 mappers available (2 per node).
Is there anything that can disable the data locality feature ?

Thanks
--
Cyril SCETBON


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Re: Hadoop jobs and data locality

Posted by cs...@orange.com.

I tried to use your quick workaround but the task is lasting really longer than before even if it uses 2 mappers in //. The fact is that there are 1000 tasks. Are you using vnodes ? I didn't try to disable them.

Kind % Complete Num Tasks Pending Running Complete Killed Failed/Killed
Task Attempts<http://107.21.43.255:50030/jobfailures.jsp?jobid=job_201305070843_0001>
map<http://107.21.43.255:50030/jobtasks.jsp?jobid=job_201305070843_0001&type=map&pagenum=1> 7.64%

1025 945<http://107.21.43.255:50030/jobtasks.jsp?jobid=job_201305070843_0001&type=map&pagenum=1&state=pending> 2<http://107.21.43.255:50030/jobtasks.jsp?jobid=job_201305070843_0001&type=map&pagenum=1&state=running> 78<http://107.21.43.255:50030/jobtasks.jsp?jobid=job_201305070843_0001&type=map&pagenum=1&state=completed> 0 0 / 0
reduce<http://107.21.43.255:50030/jobtasks.jsp?jobid=job_201305070843_0001&type=reduce&pagenum=1> 2.53%

1 0 1<http://107.21.43.255:50030/jobtasks.jsp?jobid=job_201305070843_0001&type=reduce&pagenum=1&state=running> 0 0 0 / 0

--
Cyril SCETBON

On May 5, 2013, at 8:45 AM, Shamim <sr...@yandex.ru>> wrote:

Hello,
We have also came across this issue in our dev environment, when we upgrade Cassandra from 1.1.5 to 1.2.1 version. I have mentioned this issue in few times in this forum but haven't got any answer yet. For quick work around you can use pig.splitCombination false in your pig script to avoid this issue, but it will make one of your task with a very big amount of data. I can't figure out why this happening in newer version of Cassandra, strongly guess some thing goes wrong in Cassandra implementation of LoadFunc or in Murmur3Partition (it's my guess).
Here is my earliar post
http://www.mail-archive.com/user@cassandra.apache.org/msg28016.html
http://www.mail-archive.com/user@cassandra.apache.org/msg29425.html

Any comment from authors will be highly appreciated
P.S. please keep me in touch with any solution or hints.

--
Best regards
Shamim A.

03.05.2013, 19:25, "cscetbon.ext@orange.com" <cs...@orange.com>:
Hi,
I'm using Pig to calculate the sum of a columns from a columnfamily (scan of all rows) and I've read that input data locality is supported at http://wiki.apache.org/cassandra/HadoopSupport
However when I execute my Pig script Hadoop assigns only one mapper to the task and not one mapper on each node (replication factor = 1). FYI, I've 8 mappers available (2 per node).
Is there anything that can disable the data locality feature ?

Thanks
--
Cyril SCETBON

_________________________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, France Telecom - Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may contain confidential or privileged information that may be protected by law; they should not be distributed, used or copied without authorisation. If you have received this email in error, please notify the sender and delete this message and its attachments. As emails may be altered, France Telecom - Orange is not liable for messages that have been modified, changed or falsified. Thank you.

_________________________________________________________________________________________________________________________

Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
France Telecom - Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.

This message and its attachments may contain confidential or privileged information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete this message and its attachments.
As emails may be altered, France Telecom - Orange is not liable for messages that have been modified, changed or falsified.
Thank you.

Re: Hadoop jobs and data locality

Posted by cs...@orange.com.

Unfortunately I've just tried with a new cluster with RandomPartitioner and it doesn't work better :

it may come from hadoop/pig modifications :

18:02:53|elia:hadoop cyril$ git diff --stat cassandra-1.1.5..cassandra-1.2.1 .
.../apache/cassandra/hadoop/BulkOutputFormat.java | 27 +--
.../apache/cassandra/hadoop/BulkRecordWriter.java | 55 +++---
.../cassandra/hadoop/ColumnFamilyInputFormat.java | 102 ++++++----
.../cassandra/hadoop/ColumnFamilyOutputFormat.java | 31 ++--
.../cassandra/hadoop/ColumnFamilyRecordReader.java | 76 ++++----
.../cassandra/hadoop/ColumnFamilyRecordWriter.java | 24 +--
.../apache/cassandra/hadoop/ColumnFamilySplit.java | 32 ++--
.../org/apache/cassandra/hadoop/ConfigHelper.java | 73 ++++++--
.../cassandra/hadoop/pig/CassandraStorage.java | 214 +++++++++++++-------
9 files changed, 380 insertions(+), 254 deletions(-)

Can anyone help on getting more mapper running ? Maybe we should open a bug report ?
--
Cyril SCETBON

On May 5, 2013, at 8:45 AM, Shamim <sr...@yandex.ru>> wrote:

Any comment from authors will be highly appreciated
P.S. please keep me in touch with any solution or hints.

--
Best regards
Shamim A.

Thanks
--
Cyril SCETBON

_________________________________________________________________________________________________________________________

Re: Hadoop jobs and data locality

Posted by Shamim <sr...@yandex.ru>.

Hello,
  We have also came across this issue in our dev environment, when we upgrade Cassandra from 1.1.5 to 1.2.1 version. I have mentioned this issue in few times in this forum but haven't got any answer yet. For quick work around you can use pig.splitCombination false in your pig script to avoid this issue, but it will make one of your task with a very big amount of data. I can't figure out why this happening in newer version of Cassandra, strongly guess some thing goes wrong in Cassandra implementation of LoadFunc or in Murmur3Partition (it's my guess).
Here is my earliar post
http://www.mail-archive.com/user@cassandra.apache.org/msg28016.html
http://www.mail-archive.com/user@cassandra.apache.org/msg29425.html

Any comment from authors will be highly appreciated
P.S. please keep me in touch with any solution or hints.

-- 
Best regards
  Shamim A.



03.05.2013, 19:25, "cscetbon.ext@orange.com" <cs...@orange.com>:
> Hi,
> I'm using Pig to calculate the sum of a columns from a columnfamily (scan of all rows) and I've read that input data locality is supported at http://wiki.apache.org/cassandra/HadoopSupport
> However when I execute my Pig script Hadoop assigns only one mapper to the task and not one mapper on each node (replication factor = 1).  FYI, I've 8 mappers available (2 per node).
> Is there anything that can disable the data locality feature ?
>
> Thanks
> --
> Cyril SCETBON
>
> _________________________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, France Telecom - Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may contain confidential or privileged information that may be protected by law; they should not be distributed, used or copied without authorisation. If you have received this email in error, please notify the sender and delete this message and its attachments. As emails may be altered, France Telecom - Orange is not liable for messages that have been modified, changed or falsified. Thank you.