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https://issues.apache.org/jira/browse/HBASE-16698?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15518215#comment-15518215
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Hadoop QA commented on HBASE-16698:
-----------------------------------

| (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 18s 
{color} | {color:blue} Docker mode activated. {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:green}+1{color} | {color:green} mvninstall {color} | {color:green} 3m 
43s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 0m 43s 
{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m 
52s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} mvneclipse {color} | {color:green} 0m 
17s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} findbugs {color} | {color:green} 1m 
58s {color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m 31s 
{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 0m 
51s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 0m 40s 
{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 0m 40s 
{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m 
50s {color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} mvneclipse {color} | {color:green} 0m 
14s {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} 
29m 9s {color} | {color:green} Patch does not cause any errors with Hadoop 
2.4.0 2.4.1 2.5.0 2.5.1 2.5.2 2.6.1 2.6.2 2.6.3 2.7.1. {color} |
| {color:green}+1{color} | {color:green} hbaseprotoc {color} | {color:green} 0m 
14s {color} | {color:green} the patch passed {color} |
| {color:red}-1{color} | {color:red} findbugs {color} | {color:red} 1m 59s 
{color} | {color:red} hbase-server generated 1 new + 0 unchanged - 0 fixed = 1 
total (was 0) {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m 29s 
{color} | {color:green} the patch passed {color} |
| {color:red}-1{color} | {color:red} unit {color} | {color:red} 89m 31s {color} 
| {color:red} hbase-server in the patch failed. {color} |
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 0m 
19s {color} | {color:green} The patch does not generate ASF License warnings. 
{color} |
| {color:black}{color} | {color:black} {color} | {color:black} 133m 2s {color} 
| {color:black} {color} |
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|| Reason || Tests ||
| FindBugs | module:hbase-server |
|  |  
org.apache.hadoop.hbase.regionserver.HRegion.doMiniBatchMutate(HRegion$BatchOperation)
 does not release lock on all paths  At HRegion.java:on all paths  At 
HRegion.java:[line 3262] |
| Timed out junit tests | org.apache.hadoop.hbase.client.TestReplicasClient |
|   | org.apache.hadoop.hbase.client.TestFromClientSide |
|   | org.apache.hadoop.hbase.client.TestIncrementFromClientSideWithCoprocessor 
|
|   | org.apache.hadoop.hbase.client.TestMobCloneSnapshotFromClient |
|   | org.apache.hadoop.hbase.client.TestMobSnapshotCloneIndependence |
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|| Subsystem || Report/Notes ||
| Docker | Client=1.11.2 Server=1.11.2 Image:yetus/hbase:7bda515 |
| JIRA Patch URL | 
https://issues.apache.org/jira/secure/attachment/12830123/HBASE-16698.v2.patch |
| JIRA Issue | HBASE-16698 |
| Optional Tests |  asflicense  javac  javadoc  unit  findbugs  hadoopcheck  
hbaseanti  checkstyle  compile  |
| uname | Linux c6777619b1c9 3.13.0-92-generic #139-Ubuntu SMP Tue Jun 28 
20:42:26 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 / 7ed93f8 |
| Default Java | 1.8.0_101 |
| findbugs | v3.0.0 |
| findbugs | 
https://builds.apache.org/job/PreCommit-HBASE-Build/3700/artifact/patchprocess/new-findbugs-hbase-server.html
 |
| unit | 
https://builds.apache.org/job/PreCommit-HBASE-Build/3700/artifact/patchprocess/patch-unit-hbase-server.txt
 |
| unit test logs |  
https://builds.apache.org/job/PreCommit-HBASE-Build/3700/artifact/patchprocess/patch-unit-hbase-server.txt
 |
|  Test Results | 
https://builds.apache.org/job/PreCommit-HBASE-Build/3700/testReport/ |
| modules | C: hbase-server U: hbase-server |
| Console output | 
https://builds.apache.org/job/PreCommit-HBASE-Build/3700/console |
| Powered by | Apache Yetus 0.3.0   http://yetus.apache.org |


This message was automatically generated.



> Performance issue: handlers stuck waiting for CountDownLatch inside 
> WALKey#getWriteEntry under high writing workload
> --------------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-16698
>                 URL: https://issues.apache.org/jira/browse/HBASE-16698
>             Project: HBase
>          Issue Type: Improvement
>          Components: Performance
>    Affects Versions: 1.1.6, 1.2.3
>            Reporter: Yu Li
>            Assignee: Yu Li
>         Attachments: HBASE-16698.patch, HBASE-16698.v2.patch, 
> hadoop0495.et2.jstack
>
>
> As titled, on our production environment we observed 98 out of 128 handlers 
> get stuck waiting for the CountDownLatch {{seqNumAssignedLatch}} inside 
> {{WALKey#getWriteEntry}} under a high writing workload.
> After digging into the problem, we found that the problem is mainly caused by 
> advancing mvcc in the append logic. Below is some detailed analysis:
> Under current branch-1 code logic, all batch puts will call 
> {{WALKey#getWriteEntry}} after appending edit to WAL, and 
> {{seqNumAssignedLatch}} is only released when the relative append call is 
> handled by RingBufferEventHandler (see {{FSWALEntry#stampRegionSequenceId}}). 
> Because currently we're using a single event handler for the ringbuffer, the 
> append calls are handled one by one (actually lot's of our current logic 
> depending on this sequential dealing logic), and this becomes a bottleneck 
> under high writing workload.
> The worst part is that by default we only use one WAL per RS, so appends on 
> all regions are dealt with in sequential, which causes contention among 
> different regions...
> To fix this, we could also take use of the "sequential appends" mechanism, 
> that we could grab the WriteEntry before publishing append onto ringbuffer 
> and use it as sequence id, only that we need to add a lock to make "grab 
> WriteEntry" and "append edit" a transaction. This will still cause contention 
> inside a region but could avoid contention between different regions. This 
> solution is already verified in our online environment and proved to be 
> effective.
> Notice that for master (2.0) branch since we already change the write 
> pipeline to sync before writing memstore (HBASE-15158), this issue only 
> exists for the ASYNC_WAL writes scenario.



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