Prasanth Jayachandran created HIVE-21391:
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Summary: LLAP: Pool of column vector buffers can cause memory
pressure
Key: HIVE-21391
URL: https://issues.apache.org/jira/browse/HIVE-21391
Project: Hive
Issue Type: Bug
Components: llap
Affects Versions: 4.0.0, 3.2.0
Reporter: Prasanth Jayachandran
Where there are too many columns (in the order of 100s), with decimal, string
types the column vector pool of buffers created here
[https://github.com/apache/hive/blob/master/llap-server/src/java/org/apache/hadoop/hive/llap/io/decode/EncodedDataConsumer.java#L59]
can cause memory pressure.
Example:
128 (poolSize) * 300 (numCols) * 1024 (batchSize) * 80 (decimalSize) ~= 3GB
The pool size keeps increasing when there is slow consumer but fast llap io
(SSDs) leading to GC pressure when all LLAP io threads read splits from same
table.
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