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https://issues.apache.org/jira/browse/HIVE-15077?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16364990#comment-16364990
 ] 

Hive QA commented on HIVE-15077:
--------------------------------

| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
|| || || || {color:brown} Prechecks {color} ||
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue}  0m  
0s{color} | {color:blue} Findbugs executables are not available. {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}  0m 
44s{color} | {color:blue} Maven dependency ordering for branch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  7m 
11s{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}  1m 
 3s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  1m 
43s{color} | {color:green} master passed {color} |
|| || || || {color:brown} Patch Compile Tests {color} ||
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue}  0m  
8s{color} | {color:blue} Maven dependency ordering for patch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  2m 
15s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  1m 
39s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green}  1m 
39s{color} | {color:green} the patch passed {color} |
| {color:red}-1{color} | {color:red} checkstyle {color} | {color:red}  0m 
44s{color} | {color:red} ql: The patch generated 7 new + 426 unchanged - 0 
fixed = 433 total (was 426) {color} |
| {color:red}-1{color} | {color:red} checkstyle {color} | {color:red}  0m 
20s{color} | {color:red} standalone-metastore: The patch generated 2 new + 510 
unchanged - 3 fixed = 512 total (was 513) {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} javadoc {color} | {color:green}  1m 
42s{color} | {color:green} the patch passed {color} |
|| || || || {color:brown} Other Tests {color} ||
| {color:red}-1{color} | {color:red} asflicense {color} | {color:red}  0m 
14s{color} | {color:red} The patch generated 49 ASF License warnings. {color} |
| {color:black}{color} | {color:black} {color} | {color:black} 20m  0s{color} | 
{color:black} {color} |
\\
\\
|| Subsystem || Report/Notes ||
| Optional Tests |  asflicense  javac  javadoc  findbugs  checkstyle  compile  |
| uname | Linux hiveptest-server-upstream 3.16.0-4-amd64 #1 SMP Debian 
3.16.36-1+deb8u1 (2016-09-03) x86_64 GNU/Linux |
| Build tool | maven |
| Personality | /data/hiveptest/working/yetus/dev-support/hive-personality.sh |
| git revision | master / a2d22b4 |
| Default Java | 1.8.0_111 |
| checkstyle | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-9219/yetus/diff-checkstyle-ql.txt
 |
| checkstyle | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-9219/yetus/diff-checkstyle-standalone-metastore.txt
 |
| asflicense | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-9219/yetus/patch-asflicense-problems.txt
 |
| modules | C: ql standalone-metastore U: . |
| Console output | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-9219/yetus.txt |
| Powered by | Apache Yetus    http://yetus.apache.org |


This message was automatically generated.



> Acid LockManager is unfair
> --------------------------
>
>                 Key: HIVE-15077
>                 URL: https://issues.apache.org/jira/browse/HIVE-15077
>             Project: Hive
>          Issue Type: Bug
>          Components: Transactions
>    Affects Versions: 2.3.0
>            Reporter: Eugene Koifman
>            Assignee: Eugene Koifman
>            Priority: Blocker
>         Attachments: HIVE-15077.02.patch
>
>
> HIVE-10242 made the acid LM unfair.
> In TxnHandler.checkLock(), suppose we are trying to acquire SR5  (the number 
> is extLockId).  
> Then 
> LockInfo[] locks = lockSet.toArray(new LockInfo[lockSet.size()]);
> may look like this (all explicitly listed locks are in Waiting state)
> {...., SR5 SW3 X4}
> So the algorithm will find SR5 in the list and start looking backwards (to 
> the left).
> According to IDs, SR5 should wait for X4 to be granted but X4 won't even be 
> examined and so SR5 may be granted.
> Theoretically, this could cause starvation.
> The query that generates the list already has
> query.append(" and hl_lock_ext_id <= ").append(extLockId);
> but it should use "<" rather than "<=" to exclude the locks being checked 
> from "locks" list which will make the algorithm look at all locks "in front" 
> of a given lock.
> Here is an example (add to TestDbTxnManager2)
> {noformat}
>   @Test
>   public void testFairness2() throws Exception {
>     dropTable(new String[]{"T7"});
>     CommandProcessorResponse cpr = driver.run("create table if not exists T7 
> (a int) partitioned by (p int) stored as orc TBLPROPERTIES 
> ('transactional'='true')");
>     checkCmdOnDriver(cpr);
>     checkCmdOnDriver(driver.run("insert into T7 partition(p) 
> values(1,1),(1,2)"));//create 2 partitions
>     cpr = driver.compileAndRespond("select a from T7 ");
>     checkCmdOnDriver(cpr);
>     txnMgr.acquireLocks(driver.getPlan(), ctx, "Fifer");//gets S lock on T7
>     HiveTxnManager txnMgr2 = 
> TxnManagerFactory.getTxnManagerFactory().getTxnManager(conf);
>     swapTxnManager(txnMgr2);
>     cpr = driver.compileAndRespond("alter table T7 drop partition (p=1)");
>     checkCmdOnDriver(cpr);
>     //tries to get X lock on T7.p=1 and gets Waiting state
>     LockState lockState = ((DbTxnManager) 
> txnMgr2).acquireLocks(driver.getPlan(), ctx, "Fiddler", false);
>     List<ShowLocksResponseElement> locks = getLocks();
>     Assert.assertEquals("Unexpected lock count", 4, locks.size());
>     checkLock(LockType.SHARED_READ, LockState.ACQUIRED, "default", "T7", 
> null, locks);
>     checkLock(LockType.SHARED_READ, LockState.ACQUIRED, "default", "T7", 
> "p=1", locks);
>     checkLock(LockType.SHARED_READ, LockState.ACQUIRED, "default", "T7", 
> "p=2", locks);
>     checkLock(LockType.EXCLUSIVE, LockState.WAITING, "default", "T7", "p=1", 
> locks);
>     HiveTxnManager txnMgr3 = 
> TxnManagerFactory.getTxnManagerFactory().getTxnManager(conf);
>     swapTxnManager(txnMgr3);
>     //this should block behind the X lock on  T7.p=1
>     cpr = driver.compileAndRespond("select a from T7");
>     checkCmdOnDriver(cpr);
>     txnMgr3.acquireLocks(driver.getPlan(), ctx, "Fifer");//gets S lock on T6
>     locks = getLocks();
>     Assert.assertEquals("Unexpected lock count", 7, locks.size());
>     checkLock(LockType.SHARED_READ, LockState.ACQUIRED, "default", "T7", 
> null, locks);
>     checkLock(LockType.SHARED_READ, LockState.ACQUIRED, "default", "T7", 
> "p=1", locks);
>     checkLock(LockType.SHARED_READ, LockState.ACQUIRED, "default", "T7", 
> "p=2", locks);
>     checkLock(LockType.SHARED_READ, LockState.ACQUIRED, "default", "T7", 
> null, locks);
>     checkLock(LockType.SHARED_READ, LockState.ACQUIRED, "default", "T7", 
> "p=1", locks);
>     checkLock(LockType.SHARED_READ, LockState.ACQUIRED, "default", "T7", 
> "p=2", locks);
>     checkLock(LockType.EXCLUSIVE, LockState.WAITING, "default", "T7", "p=1", 
> locks);
>   }
> {noformat}
> The 2nd {{locks = getLocks();}} output shows that all locks for the 2nd 
> {{select * from T7}} are all acquired while they should block behind the X 
> lock to be fair.



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