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Posted to issues@impala.apache.org by "Joe McDonnell (JIRA)" <ji...@apache.org> on 2018/04/04 22:18:00 UTC

[jira] [Created] (IMPALA-6807) Known Issues needs to be updated to reflect resolution of HDFS-12528

Joe McDonnell created IMPALA-6807:
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             Summary: Known Issues needs to be updated to reflect resolution of HDFS-12528
                 Key: IMPALA-6807
                 URL: https://issues.apache.org/jira/browse/IMPALA-6807
             Project: IMPALA
          Issue Type: Sub-task
          Components: Docs
    Affects Versions: Impala 2.12.0
            Reporter: Joe McDonnell
            Assignee: Alex Rodoni


In docs/topics/impala_known_issues.xml, we have a section "ki_file_handle_cache" that covers the interaction of the file handle cache with short circuit reads. This is related to the HDFS issue HDFS-12528.

HDFS-12528 is resolved. The way it was resolved is to introduce an HDFS parameter dfs.domain.socket.disable.interval.seconds that specifies the amount of time that short circuit reads are disabled. The default value for upstream Hadoop is 10 minutes (600 seconds). It can be customized, and the default value for CDH is 1 second. 

I think this section should recommend running with dfs.domain.socket.disable.interval.seconds set to a small value (CDH uses 1 second) when using file handle cache. However, 0 is not recommended. 



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