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From "Imran Rashid (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SPARK-25855) Don't use Erasure Coding for event log files
Date Fri, 26 Oct 2018 18:08:00 GMT
Imran Rashid created SPARK-25855:
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             Summary: Don't use Erasure Coding for event log files
                 Key: SPARK-25855
                 URL: https://issues.apache.org/jira/browse/SPARK-25855
             Project: Spark
          Issue Type: Improvement
          Components: Spark Core
    Affects Versions: 2.4.0
            Reporter: Imran Rashid


While testing spark with hdfs erasure coding (new in hadoop 3), we ran into a bug with the
event logs.  The main issue was a bug in hdfs (HDFS-14027), but it did make us wonder whether
Spark should be using EC for event log files in general.  Its a poor choice because EC currently
implements {{hflush()}} or {{hsync()}} as no-ops, which mean you won't see anything in your
event logs until the app is complete.  That isn't necessarily a bug, but isn't really great.
 So I think we should ensure EC is always off for event logs.

Also related are SPARK-24787 & SPARK-19531.

The space savings from EC would be nice as the event logs can get somewhat large, but I think
other factors outweigh this.



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