[jira] [Created] (PARQUET-787) Add a size limit for heap allocations when reading

["Ryan Blue (JIRA)" <ji...@apache.org>]

Ryan Blue created PARQUET-787:
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             Summary: Add a size limit for heap allocations when reading
                 Key: PARQUET-787
                 URL: https://issues.apache.org/jira/browse/PARQUET-787
             Project: Parquet
          Issue Type: Bug
          Components: parquet-mr
    Affects Versions: 1.9.0
            Reporter: Ryan Blue
            Assignee: Ryan Blue


[G1GC allocates humongous objects directly in the old generation|https://www.infoq.com/articles/tuning-tips-G1-GC] to avoid unnecessary copies, which means that these allocations aren't garbage collected until a full GC runs. Humongous objects are objects that are 50% of the region size or more. Region size is at most 32MB (see the table for [region size from heap size|http://product.hubspot.com/blog/g1gc-fundamentals-lessons-from-taming-garbage-collection#Regions]).

Parquet currently allocates a huge buffer for each contiguous group of column chunks, which in many cases is not garbage collected until a full GC. Adding a size limit for the allocation size should allow users to break row groups across multiple buffers so that buffers get collected when they have been read.



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