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https://issues.apache.org/jira/browse/HBASE-10676?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13925239#comment-13925239
]
Hadoop QA commented on HBASE-10676:
-----------------------------------
{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12633590/HBASE-10676-0.98-branchV2.patch
against trunk revision .
ATTACHMENT ID: 12633590
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:red}-1 tests included{color}. The patch doesn't appear to include
any new or modified tests.
Please justify why no new tests are needed for this
patch.
Also please list what manual steps were performed to
verify this patch.
{color:green}+1 hadoop1.0{color}. The patch compiles against the hadoop
1.0 profile.
{color:green}+1 hadoop1.1{color}. The patch compiles against the hadoop
1.1 profile.
{color:green}+1 javadoc{color}. The javadoc tool did not generate any
warning messages.
{color:green}+1 javac{color}. The applied patch does not increase the
total number of javac compiler warnings.
{color:green}+1 findbugs{color}. The patch does not introduce any 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:green}+1 lineLengths{color}. The patch does not introduce lines
longer than 100
{color:green}+1 site{color}. The mvn site goal succeeds with this patch.
{color:green}+1 core tests{color}. The patch passed unit tests in .
Test results:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//testReport/
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-hadoop2-compat.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-prefix-tree.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-client.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-common.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-protocol.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-server.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-examples.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-thrift.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-hadoop-compat.html
Console output:
https://builds.apache.org/job/PreCommit-HBASE-Build/8934//console
This message is automatically generated.
> Removing ThreadLocal of PrefetchedHeader in HFileBlock.FSReaderV2 make higher
> perforamce of scan
> ------------------------------------------------------------------------------------------------
>
> Key: HBASE-10676
> URL: https://issues.apache.org/jira/browse/HBASE-10676
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 0.98.0
> Reporter: zhaojianbo
> Attachments: HBASE-10676-0.98-branch-AtomicReference.patch,
> HBASE-10676-0.98-branch-AtomicReferenceV2.patch,
> HBASE-10676-0.98-branch.patch, HBASE-10676-0.98-branchV2.patch
>
>
> PrefetchedHeader variable in HFileBlock.FSReaderV2 is used for avoiding
> backward seek operation as the comment said:
> {quote}
> we will not incur a backward seek operation if we have already read this
> block's header as part of the previous read's look-ahead. And we also want to
> skip reading the header again if it has already been read.
> {quote}
> But that is not the case. In the code of 0.98, prefetchedHeader is
> threadlocal for one storefile reader, and in the RegionScanner
> lifecycle，different rpc handlers will serve scan requests of the same
> scanner. Even though one handler of previous scan call prefetched the next
> block header, the other handlers of current scan call will still trigger a
> backward seek operation. The process is like this:
> # rs handler1 serves the scan call, reads block1 and prefetches the header of
> block2
> # rs handler2 serves the same scanner's next scan call, because rs handler2
> doesn't know the header of block2 already prefetched by rs handler1, triggers
> a backward seek and reads block2, and prefetches the header of block3.
> It is not the sequential read. So I think that the threadlocal is useless,
> and should be abandoned. I did the work, and evaluated the performance of one
> client, two client and four client scanning the same region with one
> storefile. The test environment is
> # A hdfs cluster with a namenode, a secondary namenode , a datanode in a
> machine
> # A hbase cluster with a zk, a master, a regionserver in the same machine
> # clients are also in the same machine.
> So all the data is local. The storefile is about 22.7GB from our online data,
> 18995949 kvs. Caching is set 1000. And setCacheBlocks(false)
> With the improvement, the client total scan time decreases 21% for the one
> client case, 11% for the two clients case. But the four clients case is
> almost the same. The details tests' data is the following:
> ||case||client||time(ms)||
> | original | 1 | 306222 |
> | new | 1 | 241313 |
> | original | 2 | 416390 |
> | new | 2 | 369064 |
> | original | 4 | 555986 |
> | new | 4 | 562152 |
> With some modification(see the comments below), the newest result is
> ||case||client||time(ms)||case||client||time(ms)||case||client||time(ms)||
> |original|1|306222|new with synchronized|1|239510|new with
> AtomicReference|1|241243|
> |original|2|416390|new with synchronized|2|365367|new with
> AtomicReference|2|368952|
> |original|4|555986|new with synchronized|4|540642|new with
> AtomicReference|4|545715|
> |original|8|854029|new with synchronized|8|852137|new with
> AtomicReference|8|850401|
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