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Posted to issues@spark.apache.org by "DB Tsai (Jira)" <ji...@apache.org> on 2019/10/03 21:07:00 UTC

[jira] [Created] (SPARK-29351) Avoid full synchronization in ShuffleMapStage

DB Tsai created SPARK-29351:
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             Summary: Avoid full synchronization in ShuffleMapStage
                 Key: SPARK-29351
                 URL: https://issues.apache.org/jira/browse/SPARK-29351
             Project: Spark
          Issue Type: New Feature
          Components: Spark Core
    Affects Versions: 2.4.4
         Environment: # 
            Reporter: DB Tsai
             Fix For: 3.0.0


In one of our production streaming jobs that has more than 1k executors, and each has 20 cores, Spark spends significant portion of time (30s) in sending out the `ShuffeStatus`. We find there are two issues.

# In driver's message loop, it's calling `serializedMapStatus` which is in sync block. When the job scales really big, it can cause the contention.
# When the job is big, the `MapStatus` is huge as well, the serialization time and compression time is slow.

This work aims to address the first problem.
 
 

 



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