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https://issues.apache.org/jira/browse/HIVE-21469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16799134#comment-16799134
 ] 

Hive QA commented on HIVE-21469:
--------------------------------

| (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:green}+1{color} | {color:green} mvninstall {color} | {color:green}  8m 
56s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  1m 
13s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green}  0m 
46s{color} | {color:green} master passed {color} |
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue}  4m 
26s{color} | {color:blue} ql in master has 2255 extant Findbugs warnings. 
{color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  1m  
8s{color} | {color:green} master passed {color} |
|| || || || {color:brown} Patch Compile Tests {color} ||
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  1m 
43s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  1m 
22s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green}  1m 
22s{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 1 new + 49 unchanged - 34 
fixed = 50 total (was 83) {color} |
| {color:green}+1{color} | {color:green} whitespace {color} | {color:green}  0m 
 0s{color} | {color:green} The patch has no whitespace issues. {color} |
| {color:red}-1{color} | {color:red} findbugs {color} | {color:red}  4m 
43s{color} | {color:red} ql generated 1 new + 2252 unchanged - 3 fixed = 2253 
total (was 2255) {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  1m  
5s{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} 27m  2s{color} | 
{color:black} {color} |
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|| Reason || Tests ||
| FindBugs | module:ql |
|  |  Write to static field 
org.apache.hadoop.hive.ql.lockmgr.zookeeper.ZooKeeperHiveLockManager.metrics 
from instance method 
org.apache.hadoop.hive.ql.lockmgr.zookeeper.ZooKeeperHiveLockManager.setContext(HiveLockManagerCtx)
  At ZooKeeperHiveLockManager.java:from instance method 
org.apache.hadoop.hive.ql.lockmgr.zookeeper.ZooKeeperHiveLockManager.setContext(HiveLockManagerCtx)
  At ZooKeeperHiveLockManager.java:[line 124] |
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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 
3.16.36-1+deb8u1 (2016-09-03) x86_64 GNU/Linux |
| Build tool | maven |
| Personality | 
/data/hiveptest/working/yetus_PreCommit-HIVE-Build-16635/dev-support/hive-personality.sh
 |
| git revision | master / 2fa22bf |
| Default Java | 1.8.0_111 |
| findbugs | v3.0.0 |
| checkstyle | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-16635/yetus/diff-checkstyle-ql.txt
 |
| findbugs | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-16635/yetus/new-findbugs-ql.html
 |
| modules | C: ql U: ql |
| Console output | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-16635/yetus.txt |
| Powered by | Apache Yetus    http://yetus.apache.org |


This message was automatically generated.



> Review of ZooKeeperHiveLockManager
> ----------------------------------
>
>                 Key: HIVE-21469
>                 URL: https://issues.apache.org/jira/browse/HIVE-21469
>             Project: Hive
>          Issue Type: Improvement
>          Components: Locking
>    Affects Versions: 4.0.0, 3.2.0
>            Reporter: David Mollitor
>            Assignee: David Mollitor
>            Priority: Major
>         Attachments: HIVE-21469.1.patch, HIVE-21469.2.patch, 
> HIVE-21469.3.patch, HIVE-21469.4.patch, HIVE-21469.5.patch
>
>
> A lot of sins in this class to resolve:
> {code:java}
>   @Override
>   public void setContext(HiveLockManagerCtx ctx) throws LockException {
>  try {
>       curatorFramework = CuratorFrameworkSingleton.getInstance(conf);
>       parent = conf.getVar(HiveConf.ConfVars.HIVE_ZOOKEEPER_NAMESPACE);
>       try{
>         curatorFramework.create().withMode(CreateMode.PERSISTENT).forPath("/" 
> +  parent, new byte[0]);
>       } catch (Exception e) {
>         // ignore if the parent already exists
>         if (!(e instanceof KeeperException) || ((KeeperException)e).code() != 
> KeeperException.Code.NODEEXISTS) {
>           LOG.warn("Unexpected ZK exception when creating parent node /" + 
> parent, e);
>         }
>       }
> {code}
> Every time a new session is created and this {{setContext}} method is called, 
> it attempts to create the root node.  I have seen that, even though the root 
> node exists, an create node action is written to the ZK logs.  Check first if 
> the node exists before trying to create it.
> {code:java}
>       try {
>         curatorFramework.delete().forPath(zLock.getPath());
>       } catch (InterruptedException ie) {
>         curatorFramework.delete().forPath(zLock.getPath());
>       }
> {code}
> There has historically been a quite a few bugs regarding leaked locks.  The 
> Driver will signal the session {{Thread}} by performing an interrupt.  That 
> interrupt can happen any time and it can kill a create/delete action within 
> the ZK framework.  We can see one example of workaround for this.  If the ZK 
> action is interrupted, simply do it again.  Well, what if it's interrupted 
> yet again?  The lock will be leaked.  Also, when the {{InterruptedException}} 
> is caught in the try block, the thread's interrupted flag is cleared.  The 
> flag is not reset in this code and therefore we lose the fact that this 
> thread has been interrupted.  This flag should be preserved so that other 
> code paths will know that it's time to exit.
> {code:java}
>         if (tryNum > 1) {
>           Thread.sleep(sleepTime);
>         }
>         unlockPrimitive(hiveLock, parent, curatorFramework);
>         break;
>       } catch (Exception e) {
>         if (tryNum >= numRetriesForUnLock) {
>           String name = ((ZooKeeperHiveLock)hiveLock).getPath();
>           throw new LockException("Node " + name + " can not be deleted after 
> " + numRetriesForUnLock + " attempts.",
>               e);
>         }
>       }
> {code}
> ... related... the sleep here may be interrupted, but we still need to delete 
> the lock (again, for fear of leaking it).  This sleep should be 
> uninterruptible.  If we need to get the lock deleted, and there's a problem, 
> interrupting the sleep will cause the code to eventually exit and locks will 
> be leaked.
> It also requires a bunch more TLC.



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