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https://issues.apache.org/jira/browse/HBASE-15576?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16030846#comment-16030846
 ] 

Hadoop QA commented on HBASE-15576:
-----------------------------------

| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue} 0m 40s 
{color} | {color:blue} Docker mode activated. {color} |
| {color:green}+1{color} | {color:green} hbaseanti {color} | {color:green} 0m 
0s {color} | {color:green} Patch does not have any anti-patterns. {color} |
| {color:green}+1{color} | {color:green} @author {color} | {color:green} 0m 0s 
{color} | {color:green} The patch does not contain any @author tags. {color} |
| {color:green}+1{color} | {color:green} test4tests {color} | {color:green} 0m 
0s {color} | {color:green} The patch appears to include 1 new or modified test 
files. {color} |
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue} 0m 29s 
{color} | {color:blue} Maven dependency ordering for branch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 3m 
49s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m 54s 
{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 6m 
22s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} mvneclipse {color} | {color:green} 0m 
42s {color} | {color:green} master passed {color} |
| {color:red}-1{color} | {color:red} findbugs {color} | {color:red} 2m 20s 
{color} | {color:red} hbase-protocol-shaded in master has 24 extant Findbugs 
warnings. {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m 5s 
{color} | {color:green} master passed {color} |
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue} 0m 12s 
{color} | {color:blue} Maven dependency ordering for patch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 2m 
6s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m 53s 
{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} cc {color} | {color:green} 1m 53s 
{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 1m 53s 
{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 6m 
24s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} mvneclipse {color} | {color:green} 0m 
42s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} whitespace {color} | {color:green} 0m 
0s {color} | {color:green} The patch has no whitespace issues. {color} |
| {color:green}+1{color} | {color:green} hadoopcheck {color} | {color:green} 
32m 17s {color} | {color:green} Patch does not cause any errors with Hadoop 
2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 2.7.1 2.7.2 2.7.3 or 3.0.0-alpha2. {color} |
| {color:green}+1{color} | {color:green} hbaseprotoc {color} | {color:green} 1m 
34s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} findbugs {color} | {color:green} 7m 
37s {color} | {color:green} the patch passed {color} |
| {color:red}-1{color} | {color:red} javadoc {color} | {color:red} 0m 20s 
{color} | {color:red} hbase-client generated 37 new + 1 unchanged - 0 fixed = 
38 total (was 1) {color} |
| {color:green}+1{color} | {color:green} unit {color} | {color:green} 0m 20s 
{color} | {color:green} hbase-protocol in the patch passed. {color} |
| {color:green}+1{color} | {color:green} unit {color} | {color:green} 0m 32s 
{color} | {color:green} hbase-protocol-shaded in the patch passed. {color} |
| {color:green}+1{color} | {color:green} unit {color} | {color:green} 2m 32s 
{color} | {color:green} hbase-client in the patch passed. {color} |
| {color:red}-1{color} | {color:red} unit {color} | {color:red} 135m 9s {color} 
| {color:red} hbase-server in the patch failed. {color} |
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 1m 
16s {color} | {color:green} The patch does not generate ASF License warnings. 
{color} |
| {color:black}{color} | {color:black} {color} | {color:black} 216m 26s {color} 
| {color:black} {color} |
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|| Reason || Tests ||
| Failed junit tests | hadoop.hbase.regionserver.TestHRegionWithInMemoryFlush |
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|| Subsystem || Report/Notes ||
| Docker | Client=1.12.3 Server=1.12.3 Image:yetus/hbase:757bf37 |
| JIRA Patch URL | 
https://issues.apache.org/jira/secure/attachment/12870509/HBASE-15576.v04.patch 
|
| JIRA Issue | HBASE-15576 |
| Optional Tests |  asflicense  javac  javadoc  unit  findbugs  hadoopcheck  
hbaseanti  checkstyle  compile  cc  hbaseprotoc  |
| uname | Linux cf5533f90229 3.13.0-105-generic #152-Ubuntu SMP Fri Dec 2 
15:37:11 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux |
| Build tool | maven |
| Personality | 
/home/jenkins/jenkins-slave/workspace/PreCommit-HBASE-Build/component/dev-support/hbase-personality.sh
 |
| git revision | master / d547feac |
| Default Java | 1.8.0_131 |
| findbugs | v3.0.0 |
| findbugs | 
https://builds.apache.org/job/PreCommit-HBASE-Build/7014/artifact/patchprocess/branch-findbugs-hbase-protocol-shaded-warnings.html
 |
| javadoc | 
https://builds.apache.org/job/PreCommit-HBASE-Build/7014/artifact/patchprocess/diff-javadoc-javadoc-hbase-client.txt
 |
| unit | 
https://builds.apache.org/job/PreCommit-HBASE-Build/7014/artifact/patchprocess/patch-unit-hbase-server.txt
 |
| unit test logs |  
https://builds.apache.org/job/PreCommit-HBASE-Build/7014/artifact/patchprocess/patch-unit-hbase-server.txt
 |
|  Test Results | 
https://builds.apache.org/job/PreCommit-HBASE-Build/7014/testReport/ |
| modules | C: hbase-protocol hbase-protocol-shaded hbase-client hbase-server 
U: . |
| Console output | 
https://builds.apache.org/job/PreCommit-HBASE-Build/7014/console |
| Powered by | Apache Yetus 0.3.0   http://yetus.apache.org |


This message was automatically generated.



> Scanning cursor to prevent blocking long time on ResultScanner.next()
> ---------------------------------------------------------------------
>
>                 Key: HBASE-15576
>                 URL: https://issues.apache.org/jira/browse/HBASE-15576
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Phil Yang
>            Assignee: Phil Yang
>             Fix For: 2.0.0, 1.4.0
>
>         Attachments: HBASE-15576.v01.patch, HBASE-15576.v02.patch, 
> HBASE-15576.v03.patch, HBASE-15576.v03.patch, HBASE-15576.v04.patch, 
> HBASE-15576.v04.patch
>
>
> After 1.1.0 released, we have partial and heartbeat protocol in scanning to 
> prevent responding large data or timeout. Now for ResultScanner.next(), we 
> may block for longer time larger than timeout settings to get a Result if the 
> row is very large, or filter is sparse, or there are too many delete markers 
> in files.
> However, in some scenes, we don't want it to be blocked for too long. For 
> example, a web service which handles requests from mobile devices whose 
> network is not stable and we can not set timeout too long(eg. only 5 seconds) 
> between mobile and web service. This service will scan rows from HBase and 
> return it to mobile devices. In this scene, the simplest way is to make the 
> web service stateless. Apps in mobile devices will send several requests one 
> by one to get the data until enough just like paging a list. In each request 
> it will carry a start position which depends on the last result from web 
> service. Different requests can be sent to different web service server 
> because it is stateless.
> Therefore, the stateless web service need a cursor from HBase telling where 
> we have scanned in RegionScanner when HBase client receives an empty 
> heartbeat. And the service will return the cursor to mobile device although 
> the response has no data. In next request we can start at the position of 
> cursor, without the cursor we have to scan from last returned result and we 
> may timeout forever. And of course even if the heartbeat message is not empty 
> we can still use cursor to prevent re-scan the same rows/cells which has beed 
> skipped.
> Obviously, we will give up consistency for scanning because even HBase client 
> is also stateless, but it is acceptable in this scene. And maybe we can keep 
> mvcc in cursor so we can get a consistent view?
> HBASE-13099 had some discussion, but it has no further progress by now.
> API:
> In Scan we need a new method setNeedCursorResult(true) to get the cursor row 
> key when there is a RPC response but client can not return any Result. In 
> this mode we will not block ResultScanner.next() longer than this timeout 
> setting.
> {code}
> while (r = scanner.next() && r != null) {
>   if(r.isCursor()){
>   // scanning is not end, it is a cursor, save its row key and close scanner 
> if you want, or
>   // just continue the loop to call next().
>   } else {
>   // just like before
>   }
> }
> // scanning is end
> {code}



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