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From "Ayappan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-6459) native task crashes when merging spilled file on ppc64
Date Sun, 14 May 2017 12:27:04 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6459?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16009719#comment-16009719
] 

Ayappan commented on MAPREDUCE-6459:
------------------------------------

As mentioned in the previous comment, platforms like PowerPC has unsigned char as the default
one. NativeTask module does operations assuming char as signed one. So it makes sense to add
the gcc compiler flag "-fsigned-char" for the NativeTask Module.

[~Tao Jie] Can you attach a new patch ? (only diff being the addition of "-fsigned-char" option
in the NativeTask CMakeLists.txt file)

> native task crashes when merging spilled file on ppc64
> ------------------------------------------------------
>
>                 Key: MAPREDUCE-6459
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6459
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>    Affects Versions: 2.6.0
>         Environment: Linux version 2.6.32-431.el6.ppc64
>            Reporter: Tao Jie
>            Assignee: Tao Jie
>         Attachments: MAPREDUCE-6459.001.patch, ppc64_error.txt
>
>
> when running native task on ppc64´╝îmerging spilled files fails since we could not deserialize
local spill file correctly.
> Function readVLong in WritableUtils.h and Buffers.h, we try to compare a char with a
number and convert a char to int64_t. It does not work correctly on ppc64 since char definition
is different between ppc64 and x86 platform. On x86 platform char is defined as signed number
while on ppc64 char is unsigned. As a result, we write EOF marker [-1, -1] at the end of spill
partition, but deserialize chars as [255, 255].



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