Add a callback when the MemoryManager adjusts row group size

[asfimport]

Parquet Hive would like to increment a counter when the row group size is altered by the memory manager so that Hive can detect when there are memory problems and inform the user. I think the right way to do this is to provide a callback that will be triggered when the memory manager hits its limit.

Reporter: Ryan Blue / @rdblue
Assignee: Dong Chen / @dongc

Related issues:

• Warn when parquet memory manager kicks in (is related to)

PRs and other links:

• PR #120

_{Note: This issue was originally created as PARQUET-199. Please see the migration documentation for further details.}

[asfimport]

Ryan Blue / @rdblue:
This builds on PARQUET-164; see discussion on Dong's pull request: https://github.com/apache/incubator-parquet-mr/pull/120

[asfimport]

Ryan Blue / @rdblue:
This was merged a few days ago, just forgot to close.