Yin Huai created SPARK-23310:
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Summary: Perf regression introduced by SPARK-21113
Key: SPARK-23310
URL: https://issues.apache.org/jira/browse/SPARK-23310
Project: Spark
Issue Type: Bug
Components: Spark Core
Affects Versions: 2.3.0
Reporter: Yin Huai
While running all TPC-DS queries with SF set to 1000, we noticed that Q95 has
noticeable regression (11%). After looking into it, we found that the
regression was introduced by SPARK-21113. Specially, ReadAheadInputStream gets
lock congestion. After setting spark.unsafe.sorter.spill.read.ahead.enabled set
to false, the regression disappear and the overall performance of all TPC-DS
queries has improved.
I am proposing that we set spark.unsafe.sorter.spill.read.ahead.enabled to
false by default for Spark 2.3 and re-enable it after addressing the lock
congestion issue.
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