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https://issues.apache.org/jira/browse/HIVE-21841?focusedWorklogId=262098&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-262098
 ]

ASF GitHub Bot logged work on HIVE-21841:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 18/Jun/19 07:07
            Start Date: 18/Jun/19 07:07
    Worklog Time Spent: 10m 
      Work Description: maheshk114 commented on pull request #668: HIVE-21841 : 
Add configuration to specify the hostname of HMS leader …to run housekeeping 
tasks in.
URL: https://github.com/apache/hive/pull/668#discussion_r294619030
 
 

 ##########
 File path: 
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java
 ##########
 @@ -609,22 +609,10 @@ public void init() throws MetaException {
         partitionValidationPattern = null;
       }
 
-      // We only initialize once the tasks that need to be run periodically
-      if (alwaysThreadsInitialized.compareAndSet(false, true)) {
-        ThreadPool.initialize(conf);
-        Collection<String> taskNames =
-            MetastoreConf.getStringCollection(conf, 
ConfVars.TASK_THREADS_ALWAYS);
-        for (String taskName : taskNames) {
-          MetastoreTaskThread task =
-              JavaUtils.newInstance(JavaUtils.getClass(taskName, 
MetastoreTaskThread.class));
-          task.setConf(conf);
-          long freq = task.runFrequency(TimeUnit.MILLISECONDS);
-          // For backwards compatibility, since some threads used to be hard 
coded but only run if
-          // frequency was > 0
-          if (freq > 0) {
-            ThreadPool.getPool().scheduleAtFixedRate(task, freq, freq, 
TimeUnit.MILLISECONDS);
-          }
-        }
+      // We only initialize once the tasks that need to be run periodically. 
For remote metastore
+      // these threads are started along with the other housekeeping threads 
only in the leader HMS.
+      if (!isMetaStoreRemote()) {
 
 Review comment:
   so in stand alone meta stores with hms leader config not set.. 
startAlwaysTaskThreads will not be started ?
 
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Issue Time Tracking
-------------------

    Worklog Id:     (was: 262098)
    Time Spent: 3h 20m  (was: 3h 10m)

> Leader election in HMS to run housekeeping tasks.
> -------------------------------------------------
>
>                 Key: HIVE-21841
>                 URL: https://issues.apache.org/jira/browse/HIVE-21841
>             Project: Hive
>          Issue Type: New Feature
>    Affects Versions: 4.0.0
>            Reporter: Ashutosh Bapat
>            Assignee: Ashutosh Bapat
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 4.0.0
>
>         Attachments: HIVE-21841.01.patch, HIVE-21841.02.patch, 
> HIVE-21841.04.patch
>
>          Time Spent: 3h 20m
>  Remaining Estimate: 0h
>
> HMS performs housekeeping tasks. When there are multiple HMSes we need to 
> have a leader HMS elected which will carry out those housekeeping tasks. 
> These tasks include execution of compaction tasks, auto-discovering 
> partitions for external tables, generation of compaction tasks, repl thread 
> etc.
> Note that, though the code for compaction tasks, auto-discovery of partitions 
> etc. is in Hive, the actual tasks are initiated by an HMS configured to do 
> so. So, leader election is required only for HMS and not for HS2.



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