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https://issues.apache.org/jira/browse/HIVE-18885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16412263#comment-16412263
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Vihang Karajgaonkar commented on HIVE-18885:
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[~akolb] Can you take a look at the patch?
> DbNotificationListener has a deadlock between Java and DB locks
> ---------------------------------------------------------------
>
> Key: HIVE-18885
> URL: https://issues.apache.org/jira/browse/HIVE-18885
> Project: Hive
> Issue Type: Bug
> Components: Hive, Metastore
> Affects Versions: 2.3.2
> Reporter: Alexander Kolbasov
> Assignee: Vihang Karajgaonkar
> Priority: Major
> Attachments: HIVE-18885.01.branch-2.patch
>
>
> You can see the problem from looking at the code, but it actually created
> severe problems for real life Hive user.
> When {{alter table}} has {{cascade}} option it does the following:
> {code:java}
> msdb.openTransaction()
> ...
> List<Partition> parts = msdb.getPartitions(dbname, name, -1);
> for (Partition part : parts) {
> List<FieldSchema> oldCols = part.getSd().getCols();
> part.getSd().setCols(newt.getSd().getCols());
> String oldPartName =
> Warehouse.makePartName(oldt.getPartitionKeys(), part.getValues());
> updatePartColumnStatsForAlterColumns(msdb, part, oldPartName,
> part.getValues(), oldCols, part);
> msdb.alterPartition(dbname, name, part.getValues(), part);
> }
> {code}
> So it walks all partitions (and this may be huge list) and does some
> non-trivial operations in one single uber-transaction.
> When DbNotificationListener is enabled, it adds an event for each partition,
> all while
> holding a row lock on NOTIFICATION_SEQUENCE table. As a result, while this is
> happening no other write DDL can proceed. This can sometimes cause DB lock
> timeouts which cause HMS level operation retries which make things even worse.
> In one particular case this pretty much made HMS unusable.
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