[jira] Commented: (HBASE-3438) Cluster Wide Pauses

["Jonathan Gray (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-3438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12980826#action_12980826 ] 

Jonathan Gray commented on HBASE-3438:
--------------------------------------

What do the operations coming in to the cluster look like?  Is each client issuing requests that are randomly distributed across all regions/nodes?  If so, then the unavailability of a single region could end up looking like a pause against all your clients (eventually each client piles up waiting on the offline region).  This could be worse if you have larger regions because unavailability could increase and likelihood that a client hits that region increases.

> 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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