Piyush Narang created PARQUET-580:
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Summary: Potentially unnecessary creation of large int[] in
IntList for columns that aren't used
Key: PARQUET-580
URL: https://issues.apache.org/jira/browse/PARQUET-580
Project: Parquet
Issue Type: Bug
Reporter: Piyush Narang
Priority: Minor
Noticed that for a dataset that we were trying to import that had a lot of
columns (few thousand) that weren't being used, we ended up allocating a lot of
unnecessary int arrays (each 64K in size) in the IntList class constructor.
Heap footprint for all those int[]s turned out to be around 2GB or so (and
results in some jobs OOMing). This seems unnecessary for columns that might not
be used.
Also wondering if 64K is the right size to start off with. Wondering if a
potential improvement is if we could allocate these int[]s in IntList in a way
that slowly ramps up their size. So rather than create arrays of size 64K at a
time (which is potentially wasteful if there are only a few hundred bytes), we
could create say a 4K int[], then when it fills up an 8K[] and so on till we
reach 64K (at which point the behavior is the same as the current
implementation).
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