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https://issues.apache.org/jira/browse/HIVE-24363?focusedWorklogId=510324&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-510324
]
ASF GitHub Bot logged work on HIVE-24363:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 11/Nov/20 16:45
Start Date: 11/Nov/20 16:45
Worklog Time Spent: 10m
Work Description: pkumarsinha commented on a change in pull request #1657:
URL: https://github.com/apache/hive/pull/1657#discussion_r521492511
##########
File path:
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java
##########
@@ -571,9 +571,12 @@ public void init() throws MetaException {
listeners =
MetaStoreServerUtils.getMetaStoreListeners(MetaStoreEventListener.class, conf,
MetastoreConf.getVar(conf, ConfVars.EVENT_LISTENERS));
listeners.add(new SessionPropertiesListener(conf));
- transactionalListeners =
MetaStoreServerUtils.getMetaStoreListeners(TransactionalMetaStoreEventListener.class,
- conf, MetastoreConf.getVar(conf,
ConfVars.TRANSACTIONAL_EVENT_LISTENERS));
- transactionalListeners.add(new AcidEventListener(conf));
+ transactionalListeners = new ArrayList() {{
Review comment:
@pgaref Thanks for the review.
Currently, there are just two impl for transnational event listener in Hive
. Out of that, AcidEventLisner is hard-coded to be included. The other one,
DbNotificationListener is the one which will ideally end up getting configured
if user choose to do so. So the idea was, unless a user writes a custom
transnational event listener, this config can have at most one value as of now.
Let me know your opinion with this context.
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Issue Time Tracking
-------------------
Worklog Id: (was: 510324)
Time Spent: 1h 40m (was: 1.5h)
> 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: 1h 40m
> 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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