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Posted to issues@spark.apache.org by "Yin Huai (JIRA)" <ji...@apache.org> on 2018/02/02 02:11:02 UTC

[jira] [Created] (SPARK-23310) Perf regression introduced by SPARK-21113

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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