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https://issues.apache.org/jira/browse/HIVE-24363?focusedWorklogId=509512&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-509512
]
ASF GitHub Bot logged work on HIVE-24363:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 10/Nov/20 05:35
Start Date: 10/Nov/20 05:35
Worklog Time Spent: 10m
Work Description: aasha commented on a change in pull request #1657:
URL: https://github.com/apache/hive/pull/1657#discussion_r520298358
##########
File path:
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java
##########
@@ -573,7 +573,7 @@ public void init() throws MetaException {
listeners.add(new SessionPropertiesListener(conf));
transactionalListeners =
MetaStoreServerUtils.getMetaStoreListeners(TransactionalMetaStoreEventListener.class,
conf, MetastoreConf.getVar(conf,
ConfVars.TRANSACTIONAL_EVENT_LISTENERS));
- transactionalListeners.add(new AcidEventListener(conf));
+ transactionalListeners.add(0, new AcidEventListener(conf));
Review comment:
Since you already know this has to be at the 0th index, you can add this
add the beginning instead of shifting all other listeners and adding this to
0th index later.
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Issue Time Tracking
-------------------
Worklog Id: (was: 509512)
Time Spent: 20m (was: 10m)
> Current order of transactional event listeners is prone to deadlock in
> backend DB connections
> ---------------------------------------------------------------------------------------------
>
> Key: HIVE-24363
> URL: https://issues.apache.org/jira/browse/HIVE-24363
> Project: Hive
> Issue Type: Bug
> Reporter: Pravin Sinha
> Assignee: Pravin Sinha
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-24363.01.patch
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently the AcidEventListener is added to the end of list of transactional
> event listeners. When DbNotificationListener is configured as
> 'hive.metastore.transactional.event.listeners'. The final list will be formed
> as :
> {"DbNotificationListener" , "AcidEventListener"}
> This will result in backend DB lock acquisition in this order:
> {code:java}
> lock(a) {
> // perform some op on a
> lock(b) {
> // perform some op on b
> }
> }
> {code}
> On the other hand, there are some HMS API say for example commit_txn(), which
> calls the TxnHandler method directly, followed by DbNotificationListener
> processing. Which will result in the lock acquisition in reverse order:
> {code:java}
> lock(b) {
> // perform some op on b
> lock(a) {
> // perform some op on a
> }
> }
> {code}
> Note: 'a' and 'b' above are backend DB lock and not jvm locks.
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