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https://issues.apache.org/jira/browse/HDFS-4953?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13707639#comment-13707639
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Hadoop QA commented on HDFS-4953:
---------------------------------
{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12592112/HDFS-4953.002.patch
against trunk revision .
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:green}+1 tests included{color}. The patch appears to include 2 new
or modified test files.
{color:red}-1 javac{color}. The applied patch generated 1155 javac
compiler warnings (more than the trunk's current 1152 warnings).
{color:red}-1 javadoc{color}. The javadoc tool appears to have generated 1
warning messages.
{color:green}+1 eclipse:eclipse{color}. The patch built with
eclipse:eclipse.
{color:red}-1 findbugs{color}. The patch appears to introduce 7 new
Findbugs (version 1.3.9) warnings.
{color:green}+1 release audit{color}. The applied patch does not increase
the total number of release audit warnings.
{color:red}-1 core tests{color}. The patch failed these unit tests in
hadoop-common-project/hadoop-common hadoop-hdfs-project/hadoop-hdfs:
org.apache.hadoop.io.TestIOUtils
org.apache.hadoop.hdfs.server.namenode.ha.TestBootstrapStandby
{color:green}+1 contrib tests{color}. The patch passed contrib unit tests.
Test results:
https://builds.apache.org/job/PreCommit-HDFS-Build/4650//testReport/
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HDFS-Build/4650//artifact/trunk/patchprocess/newPatchFindbugsWarningshadoop-hdfs.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HDFS-Build/4650//artifact/trunk/patchprocess/newPatchFindbugsWarningshadoop-common.html
Javac warnings:
https://builds.apache.org/job/PreCommit-HDFS-Build/4650//artifact/trunk/patchprocess/diffJavacWarnings.txt
Console output: https://builds.apache.org/job/PreCommit-HDFS-Build/4650//console
This message is automatically generated.
> enable HDFS local reads via mmap
> --------------------------------
>
> Key: HDFS-4953
> URL: https://issues.apache.org/jira/browse/HDFS-4953
> Project: Hadoop HDFS
> Issue Type: New Feature
> Affects Versions: 2.2.0
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Attachments: benchmark.png, HDFS-4953.001.patch, HDFS-4953.002.patch
>
>
> Currently, the short-circuit local read pathway allows HDFS clients to access
> files directly without going through the DataNode. However, all of these
> reads involve a copy at the operating system level, since they rely on the
> read() / pread() / etc family of kernel interfaces.
> We would like to enable HDFS to read local files via mmap. This would enable
> truly zero-copy reads.
> In the initial implementation, zero-copy reads will only be performed when
> checksums were disabled. Later, we can use the DataNode's cache awareness to
> only perform zero-copy reads when we know that checksum has already been
> verified.
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