You might find this
It explains the problem
and solution in great detail.
On Thu, Jan 17, 2013 at 12:14 PM, Liu, Raymond <[EMAIL PROTECTED]>wrote:
> I have a table with about 24 region on the one regionserver, and
> each region have about 20 block files on hdfs.
> The xceiverCount is set to 1024, I have thought that this is quite
> enough since at most 480 blocks will be opened.
> While when I do a MR job to scan the table, with 24 map task each
> open and scan a different region at the same time, it turn out that the
> DataXceiver is run out...
> I am a little bit puzzled, those blocks will only be read by one
> task, then shouldn't region server scan blocks one by one? And since there
> are 480 blocks at most, how can it use up dataXceiver?
> Best Regards,
> Raymond Liu