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https://issues.apache.org/jira/browse/HIVE-18885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16413356#comment-16413356
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Alexander Kolbasov edited comment on HIVE-18885 at 3/26/18 4:11 AM:
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Looks like you are fixing two problems at once. One is described here and is
only applicable to branch-3. The second poblem (cleaner thread throwing
exception) is applicable to branch-3 as well, so I suggest using a separate
JIRA for it.
As for the fix for the second problem, I think you need to catch {{Throwable}},
not just {{Exception}} to guarantee that the cleaner thread will survive.
A few more thoughts:
# The comment for the {{DbNotificationListener}} class is stale and should be
updated.
# CleanerThread is static, which is Ok, but better to guarantee that the whole
thing is a singleton.
# It would be nice to have a custom name for a cleaner thread.
I don't mean that all of these should be done in this patch - probably it is
best to just remove the lock here and do cleaner-thread improvements as a
separate JIRA (or two) since they are valid for both branch-2 and branch-3.
was (Author: akolb):
Looks like you are fixing two problems at once. One is described here and is
only applicable to branch-3. The second poblem (cleaner thread throwing
exception) is applicable to branch-3 as well, so I suggest using a separate
JIRA for it.
As for the fix for the second problem, I think you need to catch Throwable, not
just Exception to guarantee that the cleaner thread will survive.
A few more thoughts:
# The comment for the {{DbNotificationListener}} class is stale and should be
updated.
# CleanerThread is static, which is Ok, but better to guarantee that the whole
thing is a singleton.
# It would be nice to have a custom name for a cleaner thread.
I don't mean that all of these should be done in this patch - probably it is
best to just remove the lock here and do cleaner-thread improvements as a
separate JIRA (or two) since they are valid for both branch-2 and branch-3.
> DbNotificationListener has a deadlock between Java and DB locks (2.x line)
> --------------------------------------------------------------------------
>
> 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,
> HIVE-18885.02.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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