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From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-14083) libhdfs logs errors when opened FS doesn't support ByteBufferReadable
Date Thu, 15 Nov 2018 09:51:01 GMT

     [ https://issues.apache.org/jira/browse/HDFS-14083?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Steve Loughran updated HDFS-14083:
----------------------------------
    Description: 
Problem:
------------
There is excessive error logging when a file is opened by libhdfs (DFSClient/HDFS) in S3 environment,
this issue is caused because buffered read is not supported in S3 environment, HADOOP-14603
"S3A input stream to support ByteBufferReadable"  

The following message is printed repeatedly in the error log/ to STDERR:
{code}
--------------------------------------------------------------------------------------------------
UnsupportedOperationException: Byte-buffer read unsupported by input streamjava.lang.UnsupportedOperationException:
Byte-buffer read unsupported by input stream
        at org.apache.hadoop.fs.FSDataInputStream.read(FSDataInputStream.java:150)
{code}

h3. Root cause


After investigating the issue, it appears that the above exception is printed because
when a file is opened via {{hdfsOpenFileImpl()}} calls {{readDirect()}} which is hitting this
exception.

h3. Fix:

Since the hdfs client is not initiating the byte buffered read but is happening in a implicit
manner, we should not be generating the error log during open of a file.




  was:
Problem:
------------
There is excessive error logging when a file is opened by libhdfs (DFSClient/HDFS) in S3 environment,
this issue is caused because buffered read is not supported in S3 environment, HADOOP-14603
"S3A input stream to support ByteBufferReadable"  

The following message is printed repeatedly in the error log/ to STDERR:
--------------------------------------------------------------------------------------------------
UnsupportedOperationException: Byte-buffer read unsupported by input streamjava.lang.UnsupportedOperationException:
Byte-buffer read unsupported by input stream
        at org.apache.hadoop.fs.FSDataInputStream.read(FSDataInputStream.java:150)

Root cause
----------------
After investigating the issue, it appears that the above exception is printed because
when a file is opened via hdfsOpenFileImpl() calls readDirect() which is hitting this
exception.

Fix:
----
Since the hdfs client is not initiating the byte buffered read but is happening in a implicit
manner, we should not be generating the error log during open of a file.





> libhdfs logs errors when opened FS doesn't support ByteBufferReadable
> ---------------------------------------------------------------------
>
>                 Key: HDFS-14083
>                 URL: https://issues.apache.org/jira/browse/HDFS-14083
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: native
>    Affects Versions: 3.0.3
>            Reporter: Pranay Singh
>            Assignee: Pranay Singh
>            Priority: Minor
>         Attachments: HADOOP-15928.001.patch, HADOOP-15928.002.patch
>
>
> Problem:
> ------------
> There is excessive error logging when a file is opened by libhdfs (DFSClient/HDFS) in
S3 environment, this issue is caused because buffered read is not supported in S3 environment,
HADOOP-14603 "S3A input stream to support ByteBufferReadable"  
> The following message is printed repeatedly in the error log/ to STDERR:
> {code}
> --------------------------------------------------------------------------------------------------
> UnsupportedOperationException: Byte-buffer read unsupported by input streamjava.lang.UnsupportedOperationException:
Byte-buffer read unsupported by input stream
>         at org.apache.hadoop.fs.FSDataInputStream.read(FSDataInputStream.java:150)
> {code}
> h3. Root cause
> After investigating the issue, it appears that the above exception is printed because
> when a file is opened via {{hdfsOpenFileImpl()}} calls {{readDirect()}} which is hitting
this
> exception.
> h3. Fix:
> Since the hdfs client is not initiating the byte buffered read but is happening in a
implicit manner, we should not be generating the error log during open of a file.



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