Hi,

First off, I'd like to say thanks to the developers for HBase, it's been fun to 
work with.

I've been using TableInputFormat to run a Map-Reduce job and ran into an issue.

Exception in thread "main" org.apache.hadoop.ipc.RemoteException: 
java.io.IOException: java.io.IOException: The number of tasks for this job 
149624 exceeds the configured limit 100000

The table i'm accessing has 149624 regions, however my Hadoop instance won't 
allow me to start a job with that many map tasks.  After briefly looking at the 
TableInputFormatBase code, it appears that since TableSplit only knows about a 
single region, my job will be forced into having mappers == # of regions.  
Since the Hadoop instance I'm using is shared, I'm concerned that even if 
configured limit was raised, having Jobs with so many mappers would eventually 
cause havoc to the job tracker.

Given that I have no control over the number of regions in the table 
(maintained by someone else), is the only solution to implement another input 
format (i.e. MultiRegionTableFormat) that allows InputSplits to have more than 
one region?  I don't mind doing it, but didn't want to write it if another 
solution already exists.

Apologies if this issue has been raised before, but a quick search didn't turn 
anything up for me.

Thanks,

Avery

Reply via email to