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https://issues.apache.org/jira/browse/HIVE-21917?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16975556#comment-16975556
 ] 

Hive QA commented on HIVE-21917:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
|| || || || {color:brown} Prechecks {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:brown} master Compile Tests {color} ||
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue}  1m 
32s{color} | {color:blue} Maven dependency ordering for branch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  7m 
23s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  1m 
36s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green}  1m 
 6s{color} | {color:green} master passed {color} |
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue}  1m 
16s{color} | {color:blue} standalone-metastore/metastore-server in master has 
178 extant Findbugs warnings. {color} |
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue}  4m  
7s{color} | {color:blue} ql in master has 1544 extant Findbugs warnings. 
{color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  1m 
25s{color} | {color:green} master passed {color} |
|| || || || {color:brown} Patch Compile Tests {color} ||
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue}  0m 
27s{color} | {color:blue} Maven dependency ordering for patch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  2m 
 4s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  1m 
35s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green}  1m 
35s{color} | {color:green} the patch passed {color} |
| {color:red}-1{color} | {color:red} checkstyle {color} | {color:red}  0m 
25s{color} | {color:red} standalone-metastore/metastore-server: The patch 
generated 18 new + 627 unchanged - 1 fixed = 645 total (was 628) {color} |
| {color:red}-1{color} | {color:red} checkstyle {color} | {color:red}  0m 
42s{color} | {color:red} ql: The patch generated 1 new + 33 unchanged - 0 fixed 
= 34 total (was 33) {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} findbugs {color} | {color:green}  5m 
36s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  1m 
22s{color} | {color:green} the patch passed {color} |
|| || || || {color:brown} Other Tests {color} ||
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green}  0m 
15s{color} | {color:green} The patch does not generate ASF License warnings. 
{color} |
| {color:black}{color} | {color:black} {color} | {color:black} 31m 37s{color} | 
{color:black} {color} |
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|| Subsystem || Report/Notes ||
| Optional Tests |  asflicense  javac  javadoc  findbugs  checkstyle  compile  |
| uname | Linux hiveptest-server-upstream 3.16.0-4-amd64 #1 SMP Debian 
3.16.43-2+deb8u5 (2017-09-19) x86_64 GNU/Linux |
| Build tool | maven |
| Personality | 
/data/hiveptest/working/yetus_PreCommit-HIVE-Build-19449/dev-support/hive-personality.sh
 |
| git revision | master / 078182a |
| Default Java | 1.8.0_111 |
| findbugs | v3.0.0 |
| checkstyle | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-19449/yetus/diff-checkstyle-standalone-metastore_metastore-server.txt
 |
| checkstyle | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-19449/yetus/diff-checkstyle-ql.txt
 |
| modules | C: standalone-metastore/metastore-server ql U: . |
| Console output | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-19449/yetus.txt |
| Powered by | Apache Yetus    http://yetus.apache.org |


This message was automatically generated.



> COMPLETED_TXN_COMPONENTS table is never cleaned up unless Compactor runs
> ------------------------------------------------------------------------
>
>                 Key: HIVE-21917
>                 URL: https://issues.apache.org/jira/browse/HIVE-21917
>             Project: Hive
>          Issue Type: Bug
>          Components: Transactions
>    Affects Versions: 3.1.0, 3.1.1
>            Reporter: Craig Condit
>            Assignee: Denys Kuzmenko
>            Priority: Major
>         Attachments: HIVE-21917.1.patch, HIVE-21917.2.patch
>
>
> The Initiator thread in the metastore repeatedly loops over entries in the 
> COMPLETED_TXN_COMPONENTS table to determine which partitions / tables might 
> need to be compacted. However, entries are never removed from this table 
> except by a completed Compactor run.
> In a cluster where most tables / partitions are write-once read-many, this 
> results in stale entries in this table never being cleaned up. In a small 
> test cluster, we have observed approximately 45k entries in this table 
> (virtually equal to the number of partitions in the cluster) while < 100 of 
> these tables have delta files at all. Since most of the tables will never get 
> enough writes to trigger a compaction (and in fact have only ever been 
> written to once), the initiator thread keeps trying to evaluate them on every 
> loop.
> On this test cluster, it takes approximately 10 minutes to loop through all 
> the entries and results in severe performance degradation on metastore 
> operations. With the default run timing of 5 minutes, the initiator basically 
> never stops running.
> On a production cluster with 2M partitions, this would be a non-starter.
> The initiator thread should proactively remove entries from 
> COMPLETED_TXN_COMPONENTS when it determines that a compaction is not needed, 
> so that they are not evaluated again on the next loop.
>  



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