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https://issues.apache.org/jira/browse/HBASE-9676?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13783246#comment-13783246
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Nick Dimiduk commented on HBASE-9676:
-------------------------------------
{noformat}
+ /**
+ * The number of tasks we run in parallel on a single region.
+ * With 1 (the default) , we ensure that the ordering of the queries is
respected: we don't start
+ * a set of operations on a region before the previous one is done. As well,
this limits
+ * the pressure we put on the region server.
+ */
protected final int maxConcurrentTasksPerRegion;
{noformat}
This documentation is very good. Thinking about consistency models and the
linear ordering of writes, I'm concerned about proper documentation of this
setting. By setting {{hbase.client.max.perregion.tasks > 1}} the user has
accepted the possibility of the RS ACKing writes out of order. Technically this
is okay, I think, because at this level, the API only makes guarantees about a
single row; so long as edits to a single row are properly grouped, there are no
surprises. The user has also accepted the out-of-order nature of writes across
multiple regions; conceptually this is an extension.
I don't see the second bug fixed in this patch; I'll have to trust you.
+1
> AsyncProcess can create more tasks than hbase.client.max.total.tasks
> --------------------------------------------------------------------
>
> Key: HBASE-9676
> URL: https://issues.apache.org/jira/browse/HBASE-9676
> Project: HBase
> Issue Type: Bug
> Components: Client
> Affects Versions: 0.98.0, 0.96.0
> Reporter: Nicolas Liochon
> Assignee: Nicolas Liochon
> Priority: Critical
> Fix For: 0.98.0, 0.96.1
>
> Attachments: 9676.v2.patch, 9676.v3.patch, 9676.v4.patch
>
>
> hbase.client.max.total.tasks allows to control the number of tasks in
> progress. But when adding tasks, we take only into account the number of
> tasks currently running, not the one we're creating.
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