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https://issues.apache.org/jira/browse/HADOOP-15171?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17191286#comment-17191286
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Michael South commented on HADOOP-15171:
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Issue should be closed, unfounded. The Hive Orc driver creates a decompression
object and repeatedly calling it to deflate Orc blocks. Its treating each block
as an entirely separate chunk (stream), completely decompressing each with one
call to ...{{_inflateBytesDirect()}}. However, it wasn't calling
{{inflateReset()}} or {{inflateEnd()}} / {{inflateInit()}} between the streams,
which naturally left things in a confused state. It appears to be fixed in
trunk Hive.
Also, returning 0 for {{Z_BUF_ERROR}} or {{Z_NEED_DICT}} is correct, and should
not throw an error. The Java decompression object is agnostic as to whether the
application is working in stream or all-at-once mode. The only determination of
which mode is active is whether the application (Hive Orc driver in this case)
is passing the entire input in one chunk and is allocating sufficient space for
all of the output. Therefore, the application must check for a zero return. If
no-progress (zero return) is an impossible situation then it can throw an
exception; otherwise it needs to look at one or more of ...{{_finished()}},
...{{_getRemaining()}}, and/or ...{{_needDict()}} to figure out what's needed
to make further progress. (It would be nice if JNI exposed the {{avail_out}}
field, but if it's not an input or dictionary issue it must be a full output
buffer.)
There *is* a very minor bug in ...{{inflateBytesDirect()}}. It's calling
{{inflate()}} with {{Z_PARTIAL_FLUSH}}, which only applies to {{deflate()}}. It
should be {{Z_NO_FLUSH}}. However, in the current zlib code (1.2.11) the
{{flush}} parameter only affects the return code, and it only checks whether or
not it is {{Z_FINISH}}.
> native ZLIB decompressor produces 0 bytes on the 2nd call; also incorrrectly
> handles some zlib errors
> -----------------------------------------------------------------------------------------------------
>
> Key: HADOOP-15171
> URL: https://issues.apache.org/jira/browse/HADOOP-15171
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 3.1.0
> Reporter: Sergey Shelukhin
> Assignee: Lokesh Jain
> Priority: Blocker
>
> While reading some ORC file via direct buffers, Hive gets a 0-sized buffer
> for a particular compressed segment of the file. We narrowed it down to
> Hadoop native ZLIB codec; when the data is copied to heap-based buffer and
> the JDK Inflater is used, it produces correct output. Input is only 127 bytes
> so I can paste it here.
> All the other (many) blocks of the file are decompressed without problems by
> the same code.
> {noformat}
> 2018-01-13T02:47:40,815 TRACE [IO-Elevator-Thread-0
> (1515637158315_0079_1_00_000000_0)] encoded.EncodedReaderImpl: Decompressing
> 127 bytes to dest buffer pos 524288, limit 786432
> 2018-01-13T02:47:40,816 WARN [IO-Elevator-Thread-0
> (1515637158315_0079_1_00_000000_0)] encoded.EncodedReaderImpl: The codec has
> produced 0 bytes for 127 bytes at pos 0, data hash 1719565039: [e3 92 e1 62
> 66 60 60 10 12 e5 98 e0 27 c4 c7 f1 e8 12 8f 40 c3 7b 5e 89 09 7f 6e 74 73 04
> 30 70 c9 72 b1 30 14 4d 60 82 49 37 bd e7 15 58 d0 cd 2f 31 a1 a1 e3 35 4c fa
> 15 a3 02 4c 7a 51 37 bf c0 81 e5 02 12 13 5a b6 9f e2 04 ea 96 e3 62 65 b8 c3
> b4 01 ae fd d0 72 01 81 07 87 05 25 26 74 3c 5b c9 05 35 fd 0a b3 03 50 7b 83
> 11 c8 f2 c3 82 02 0f 96 0b 49 34 7c fa ff 9f 2d 80 01 00
> 2018-01-13T02:47:40,816 WARN [IO-Elevator-Thread-0
> (1515637158315_0079_1_00_000000_0)] encoded.EncodedReaderImpl: Fell back to
> JDK decompressor with memcopy; got 155 bytes
> {noformat}
> Hadoop version is based on 3.1 snapshot.
> The size of libhadoop.so is 824403 bytes, and libgplcompression is 78273
> FWIW. Not sure how to extract versions from those.
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