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?