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Posted to common-dev@hadoop.apache.org by "Hadoop QA (JIRA)" <ji...@apache.org> on 2009/03/11 12:57:50 UTC
[jira] Commented: (HADOOP-5459) CRC errors not detected reading
intermediate output into memory with problematic length
[ https://issues.apache.org/jira/browse/HADOOP-5459?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12680851#action_12680851 ]
Hadoop QA commented on HADOOP-5459:
-----------------------------------
+1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12401904/5459-1.patch
against trunk revision 752405.
+1 @author. The patch does not contain any @author tags.
+1 tests included. The patch appears to include 2 new or modified tests.
+1 javadoc. The javadoc tool did not generate any warning messages.
+1 javac. The applied patch does not increase the total number of javac compiler warnings.
+1 findbugs. The patch does not introduce any new Findbugs warnings.
+1 Eclipse classpath. The patch retains Eclipse classpath integrity.
+1 release audit. The applied patch does not increase the total number of release audit warnings.
+1 core tests. The patch passed core unit tests.
+1 contrib tests. The patch passed contrib unit tests.
Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-minerva.apache.org/49/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-minerva.apache.org/49/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-minerva.apache.org/49/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-minerva.apache.org/49/console
This message is automatically generated.
> CRC errors not detected reading intermediate output into memory with problematic length
> ---------------------------------------------------------------------------------------
>
> Key: HADOOP-5459
> URL: https://issues.apache.org/jira/browse/HADOOP-5459
> Project: Hadoop Core
> Issue Type: Bug
> Affects Versions: 0.20.0
> Reporter: Chris Douglas
> Assignee: Chris Douglas
> Priority: Blocker
> Attachments: 5459-0.patch, 5459-1.patch
>
>
> It's possible that the expected, uncompressed length of the segment is less than the available/decompressed data. This can happen in some worst-cases for compression, but it is exceedingly rare. It is also possible (though also fantastically unlikely) for the data to deflate to a size greater than that reported by the map. CRC errors will remain undetected because IFileInputStream does not validate the checksum until the end of the stream, and close() does not advance the stream to the end of the segment. The (abbreviated) read loop fetching data in shuffleInMemory:
> {code}
> int n = input.read(shuffleData, 0, shuffleData.length);
> while (n > 0) {
> bytesRead += n;
> n = input.read(shuffleData, bytesRead,
> (shuffleData.length-bytesRead));
> }
> {code}
> Will read only up to the expected length. Without reading the whole segment, the checksum is not validated. Even if IFileInputStream instances are closed, they should always validate checksums.
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