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RE: How to configure mapreduce archive size?
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From: Yang, Xia
Sent: Thursday, April 11, 2013 11:11 AM
Subject: RE: How to configure mapreduce archive size?

Hi Hemanth,

Attached is some sample folders within my /tmp/hadoop-root/mapred/local/archive. There are some jar and class files inside.

My application uses MapReduce job to do purge Hbase old data. I am using basic HBase MapReduce API to delete rows from Hbase table. I do not specify to use Distributed cache. Maybe HBase use it?

Some code here:

       Scan scan = new Scan();
       scan.setCaching(500);        // 1 is the default in Scan, which will be bad for MapReduce jobs
       scan.setCacheBlocks(false);  // don't set to true for MR jobs
       scan.setTimeRange(Long.MIN_VALUE, timestamp);
       // set other scan attrs
       // the purge start time
       Date date=new Date();
             tableName,        // input table
             scan,               // Scan instance to control CF and attribute selection
             MapperDelete.class,     // mapper class
             null,         // mapper output key
             null,  // mapper output value

       job.getConfiguration().set(TableOutputFormat.OUTPUT_TABLE, tableName);

       boolean b = job.waitForCompletion(true);

From: Hemanth Yamijala [mailto:[EMAIL PROTECTED]]
Sent: Thursday, April 11, 2013 12:29 AM
Subject: Re: How to configure mapreduce archive size?

Could you paste the contents of the directory ? Not sure whether that will help, but just giving it a shot.

What application are you using ? Is it custom MapReduce jobs in which you use Distributed cache (I guess not) ?


On Thu, Apr 11, 2013 at 3:34 AM, <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
Hi Arun,

I stopped my application, then restarted my hbase (which include hadoop). After that I start my application. After one evening, my /tmp/hadoop-root/mapred/local/archive goes to more than 1G. It does not work.

Is this the right place to change the value?

"local.cache.size" in file core-default.xml, which is in hadoop-core-1.0.3.jar



From: Arun C Murthy [mailto:[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>]
Sent: Wednesday, April 10, 2013 2:45 PM

Subject: Re: How to configure mapreduce archive size?

Ensure no jobs are running (cache limit is only for non-active cache files), check after a little while (takes sometime for the cleaner thread to kick in).


On Apr 11, 2013, at 2:29 AM, <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:

Hi Hemanth,

For the hadoop 1.0.3, I can only find "local.cache.size" in file core-default.xml, which is in hadoop-core-1.0.3.jar. It is not in mapred-default.xml.

I updated the value in file default.xml and changed the value to 500000. This is just for my testing purpose. However, the folder /tmp/hadoop-root/mapred/local/archive already goes more than 1G now. Looks like it does not do the work. Could you advise if what I did is correct?




From: Hemanth Yamijala [mailto:[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>]
Sent: Monday, April 08, 2013 9:09 PM
Subject: Re: How to configure mapreduce archive size?


This directory is used as part of the 'DistributedCache' feature. (http://hadoop.apache.org/docs/r1.0.4/mapred_tutorial.html#DistributedCache). There is a configuration key "local.cache.size" which controls the amount of data stored under DistributedCache. The default limit is 10GB. However, the files under this cannot be deleted if they are being used. Also, some frameworks on Hadoop could be using DistributedCache transparently to you.

So you could check what is being stored here and based on that lower the limit of the cache size if you feel that will help. The property needs to be set in mapred-default.xml.


On Mon, Apr 8, 2013 at 11:09 PM, <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:

I am using hadoop which is packaged within hbase -0.94.1. It is hadoop 1.0.3. There is some mapreduce job running on my server. After some time, I found that my folder /tmp/hadoop-root/mapred/local/archive has 14G size.

How to configure this and limit the size? I do not want  to waste my space for archive.



Arun C. Murthy
Hortonworks Inc.