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https://issues.apache.org/jira/browse/HBASE-3438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12980876#action_12980876
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Wayne commented on HBASE-3438:
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We have 10 nodes with 4 dedicated writers per node. These writers are basically
pushing randomly distributed writes via 40 "threads" constantly 7/24. If a
single region was locked I guess it could cause a pause for all of them, but it
would then would go into a wait state like domino's one after the other. It
appears to occur all at once and reads are blocked as well which is the biggest
concern. There are also 40 read workers. It seems a little crazy to me to think
80 threads are all waiting for a single region when there are thousands of
regions. A region split only pauses writes anyway correct? Are reads blocked as
well?
> Cluster Wide Pauses
> -------------------
>
> Key: HBASE-3438
> URL: https://issues.apache.org/jira/browse/HBASE-3438
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.89.20100924
> Environment: CentOS 5.5, 10 Nodes, 24GB RAM, 4 1TB Disks, 8GB Heap
> Reporter: Wayne
>
> Under heavy write load the entire cluster seems to pause with all nodes
> pausing writes/reads for several seconds at a time. This seems to be worse
> with larger region sizes. One possible explanation is that a single node gets
> caught/paused/stuck during a split and that all other nodes are waiting on
> that one node so it looks like a cluster wide pause.
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