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https://issues.apache.org/jira/browse/MAPREDUCE-6481?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14791717#comment-14791717
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Hadoop QA commented on MAPREDUCE-6481:
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| (/) *{color:green}+1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | pre-patch | 18m 24s | Pre-patch trunk compilation is
healthy. |
| {color:green}+1{color} | @author | 0m 0s | The patch does not contain any
@author tags. |
| {color:green}+1{color} | tests included | 0m 0s | The patch appears to
include 2 new or modified test files. |
| {color:green}+1{color} | javac | 7m 47s | There were no new javac warning
messages. |
| {color:green}+1{color} | javadoc | 10m 3s | There were no new javadoc
warning messages. |
| {color:green}+1{color} | release audit | 0m 24s | The applied patch does
not increase the total number of release audit warnings. |
| {color:green}+1{color} | checkstyle | 1m 54s | There were no new checkstyle
issues. |
| {color:green}+1{color} | whitespace | 0m 2s | The patch has no lines that
end in whitespace. |
| {color:green}+1{color} | install | 1m 27s | mvn install still works. |
| {color:green}+1{color} | eclipse:eclipse | 0m 33s | The patch built with
eclipse:eclipse. |
| {color:green}+1{color} | findbugs | 3m 16s | The patch does not introduce
any new Findbugs (version 3.0.0) warnings. |
| {color:green}+1{color} | common tests | 22m 58s | Tests passed in
hadoop-common. |
| {color:green}+1{color} | mapreduce tests | 1m 45s | Tests passed in
hadoop-mapreduce-client-core. |
| | | 68m 37s | |
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|| Subsystem || Report/Notes ||
| Patch URL |
http://issues.apache.org/jira/secure/attachment/12756420/MAPREDUCE-6481.000.patch
|
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / 0832b38 |
| hadoop-common test log |
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/5998/artifact/patchprocess/testrun_hadoop-common.txt
|
| hadoop-mapreduce-client-core test log |
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/5998/artifact/patchprocess/testrun_hadoop-mapreduce-client-core.txt
|
| Test Results |
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/5998/testReport/ |
| Java | 1.7.0_55 |
| uname | Linux asf904.gq1.ygridcore.net 3.13.0-36-lowlatency #63-Ubuntu SMP
PREEMPT Wed Sep 3 21:56:12 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux |
| Console output |
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/5998/console |
This message was automatically generated.
> LineRecordReader may give incomplete record and wrong position/key
> information for uncompressed input sometimes.
> ----------------------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-6481
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6481
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv2
> Affects Versions: 2.7.0
> Reporter: zhihai xu
> Assignee: zhihai xu
> Priority: Critical
> Attachments: MAPREDUCE-6481.000.patch
>
>
> LineRecordReader may give incomplete record and wrong position/key
> information for uncompressed input sometimes.
> There are two issues:
> # LineRecordReader may give incomplete record: some characters cut off at the
> end of record.
> # LineRecordReader may give wrong position/key information.
> The first issue only happens for Custom Delimiter, which is caused by the
> following code at {{LineReader#readCustomLine}}:
> {code}
> if (appendLength > 0) {
> if (ambiguousByteCount > 0) {
> str.append(recordDelimiterBytes, 0, ambiguousByteCount);
> //appending the ambiguous characters (refer case 2.2)
> bytesConsumed += ambiguousByteCount;
> ambiguousByteCount=0;
> }
> str.append(buffer, startPosn, appendLength);
> txtLength += appendLength;
> }
> {code}
> If {{appendLength}} is 0 and {{ambiguousByteCount}} is not 0, this bug will
> be triggered. For example, input is "123456789aab", Custom Delimiter is "ab",
> bufferSize is 10 and splitLength is 12, the correct record should be
> "123456789a" with length 10, but we get incomplete record "123456789" with
> length 9 from current code.
> The second issue can happen for both Custom Delimiter and Default Delimiter,
> which is caused by the code in {{UncompressedSplitLineReader#readLine}}.
> {{UncompressedSplitLineReader#readLine}} may report wrong size information at
> some corner cases. The reason is {{unusedBytes}} in the following code:
> {code}
> bytesRead += unusedBytes;
> unusedBytes = bufferSize - getBufferPosn();
> bytesRead -= unusedBytes;
> {code}
> If the last bytes read (bufferLength) is less than bufferSize, the previous
> {{unusedBytes}} will be wrong, which should be {{bufferLength}} -
> {{bufferPosn}} instead of bufferSize - {{bufferPosn}}. It will return larger
> value.
> For example, input is "1234567890ab12ab345", Custom Delimiter is "ab",
> bufferSize is 10 and two splits:first splitLength is 15 and second
> splitLength 4:
> the current code will give the following result:
> First record: Key:0 Value:"1234567890"
> Second record: Key:12 Value:"12"
> Third Record: Key:21 Value:"345"
> You can see the Key for the third record is wrong, it should be 16 instead of
> 21. It is due to wrong {{unusedBytes}}. {{fillBuffer}} read 10 bytes for the
> first time, for the second times, it only read 5 bytes, which is 5 bytes less
> than the bufferSize. That is why the key we get is 5 bytes larger than the
> correct one.
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