Thanks Stephan for the support! Unfortunately we are not able to understand what lineage of operators cause this problem.. in our case we set the scan timeout to 15 minutes so I think we can exclude garbage collection thus, probably, this is caused by the first option (unfortunately HBase cannot block scans indefinitely..).
What can we do to debug this problem? can you give us more detail or links to the internals of such situations? it is not very clear to me the relation between buffers, actions and pauses between two consecutive nextRecord() on the same split of the inputFormat..
