Is parquet-mr thread-safe?

[Gabor Szadovszky <ga...@apache.org>]

Hi All,

After finally pushing column-indexes we've got the issue PARQUET-1456.
ColumnIndexBuilder uses not thread-safe cache to build ColumnIndex objects
while reading.
I was not aware that parquet-mr might be used in a concurrent way. Never
seen any unit tests that  suggests we are prepared for this usage.
So the question is does parquet-mr supports concurrency? Is this JIRA valid?

Thanks a lot,
Gabor