No I mean whether your mapreduce job's reduce task number is 1.

And could you share your pig script, then others can really understand
your problem.



On Fri, Oct 8, 2010 at 5:04 PM, Vincent <[email protected]> wrote:
>  You are right, I didn't change this parameter, therefore the default is
> used from src/mapred/mapred-default.xml
>
> <property>
> <name>mapred.reduce.tasks</name>
> <value>1</value>
> <description>The default number of reduce tasks per job. Typically set to
> 99%
>  of the cluster's reduce capacity, so that if a node fails the reduces can
>  still be executed in a single wave.
>  Ignored when mapred.job.tracker is "local".
> </description>
> </property>
>
> Not clear for me what is the reduce capacity of my cluster :)
>
> On 10/08/2010 01:00 PM, Jeff Zhang wrote:
>>
>> I guess maybe your reduce number is 1 which cause the reduce phase very
>> slowly.
>>
>>
>>
>> On Fri, Oct 8, 2010 at 4:44 PM, Vincent<[email protected]>
>>  wrote:
>>>
>>>  Well I can see from the job tracker that all the jobs are done quite
>>> quickly expect 2 for which reduce phase goes really really slowly.
>>>
>>> But how can I make the parallel between a job in the Hadoop jop tracker
>>> (example: job_201010072150_0045) and the Pig script execution?
>>>
>>> And what is the most efficient: several small Pig scripts? or one big Pig
>>> script? I did one big to avoid to load several time the same logs in
>>> different scripts. Maybe it is not so good design...
>>>
>>> Thanks for your help.
>>>
>>> - Vincent
>>>
>>>
>>> On 10/08/2010 11:31 AM, Vincent wrote:
>>>>
>>>>  I'm using pig-0.7.0 on hadoop-0.20.2.
>>>>
>>>> For the script, well it's more then 500 lines, I'm not sure if I post it
>>>> here that somebody will read it till the end :-)
>>>>
>>>>
>>>> On 10/08/2010 11:26 AM, Dmitriy Ryaboy wrote:
>>>>>
>>>>> What version of Pig, and what does your script look like?
>>>>>
>>>>> On Thu, Oct 7, 2010 at 11:48 PM, Vincent<[email protected]>
>>>>>  wrote:
>>>>>
>>>>>>  Hi All,
>>>>>>
>>>>>> I'm quite new to Pig/Hadoop. So maybe my cluster size will make you
>>>>>> laugh.
>>>>>>
>>>>>> I wrote a script on Pig handling 1.5GB of logs in less than one hour
>>>>>> in
>>>>>> pig
>>>>>> local mode on a Intel core 2 duo with 3GB of RAM.
>>>>>>
>>>>>> Then I tried this script on a simple 2 nodes cluster. These 2 nodes
>>>>>> are
>>>>>> not
>>>>>> servers but simple computers:
>>>>>> - Intel core 2 duo with 3GB of RAM.
>>>>>> - Intel Quad with 4GB of RAM.
>>>>>>
>>>>>> Well I was aware that hadoop has overhead and that it won't be done in
>>>>>> half
>>>>>> an hour (time in local divided by number of nodes). But I was
>>>>>> surprised
>>>>>> to
>>>>>> see this morning it took 7 hours to complete!!!
>>>>>>
>>>>>> My configuration was made according to this link:
>>>>>>
>>>>>>
>>>>>>
>>>>>> http://www.michael-noll.com/wiki/Running_Hadoop_On_Ubuntu_Linux_%28Multi-Node_Cluster%29
>>>>>>
>>>>>> My question is simple: Is it normal?
>>>>>>
>>>>>> Cheers
>>>>>>
>>>>>>
>>>>>> Vincent
>>>>>>
>>>>>>
>>>
>>
>>
>
>



-- 
Best Regards

Jeff Zhang

Reply via email to