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Posted to issues@hbase.apache.org by "Todd Lipcon (JIRA)" <ji...@apache.org> on 2012/05/10 00:15:48 UTC

[jira] [Created] (HBASE-5978) Scanner next() calls should return after a configurable time threshold regardless of number of accumulated rows

Todd Lipcon created HBASE-5978:
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             Summary: Scanner next() calls should return after a configurable time threshold regardless of number of accumulated rows
                 Key: HBASE-5978
                 URL: https://issues.apache.org/jira/browse/HBASE-5978
             Project: HBase
          Issue Type: Improvement
          Components: client, regionserver
    Affects Versions: 0.92.1, 0.90.7
            Reporter: Todd Lipcon


Currently if you pass a very restrictive filter to a scanner, along with a high caching value, you will end up causing RPC timeouts, lease exceptions, etc. Although this is a poor configuration and easy to work around by lowering caching, HBase should be resilient to a badly chosen caching value. As such, the scanner next() call should record the elapsed time, and after some number of seconds have passed, return any accumulated rows regardless of the caching value. This prevents the calls from starving out other threads or region operations.

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[jira] [Commented] (HBASE-5978) Scanner next() calls should return after a configurable time threshold regardless of number of accumulated rows

Posted by "Alex Newman (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13281228#comment-13281228 ] 

Alex Newman commented on HBASE-5978:
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I assume you want this to return before any exception is thrown?
                
> Scanner next() calls should return after a configurable time threshold regardless of number of accumulated rows
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-5978
>                 URL: https://issues.apache.org/jira/browse/HBASE-5978
>             Project: HBase
>          Issue Type: Improvement
>          Components: client, regionserver
>    Affects Versions: 0.90.7, 0.92.1
>            Reporter: Todd Lipcon
>
> Currently if you pass a very restrictive filter to a scanner, along with a high caching value, you will end up causing RPC timeouts, lease exceptions, etc. Although this is a poor configuration and easy to work around by lowering caching, HBase should be resilient to a badly chosen caching value. As such, the scanner next() call should record the elapsed time, and after some number of seconds have passed, return any accumulated rows regardless of the caching value. This prevents the calls from starving out other threads or region operations.

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[jira] [Commented] (HBASE-5978) Scanner next() calls should return after a configurable time threshold regardless of number of accumulated rows

Posted by "Alex Newman (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13281227#comment-13281227 ] 

Alex Newman commented on HBASE-5978:
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Do we already have some choosen favorite way to commit an action after a timer?
                
> Scanner next() calls should return after a configurable time threshold regardless of number of accumulated rows
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-5978
>                 URL: https://issues.apache.org/jira/browse/HBASE-5978
>             Project: HBase
>          Issue Type: Improvement
>          Components: client, regionserver
>    Affects Versions: 0.90.7, 0.92.1
>            Reporter: Todd Lipcon
>
> Currently if you pass a very restrictive filter to a scanner, along with a high caching value, you will end up causing RPC timeouts, lease exceptions, etc. Although this is a poor configuration and easy to work around by lowering caching, HBase should be resilient to a badly chosen caching value. As such, the scanner next() call should record the elapsed time, and after some number of seconds have passed, return any accumulated rows regardless of the caching value. This prevents the calls from starving out other threads or region operations.

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[jira] [Commented] (HBASE-5978) Scanner next() calls should return after a configurable time threshold regardless of number of accumulated rows

Posted by "Elliott Clark (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13281253#comment-13281253 ] 

Elliott Clark commented on HBASE-5978:
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This has come up twice today.  It should also include some way to include a empty set result if the filter has filtered everything.

Can this be rolled into the pb work ?
                
> Scanner next() calls should return after a configurable time threshold regardless of number of accumulated rows
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-5978
>                 URL: https://issues.apache.org/jira/browse/HBASE-5978
>             Project: HBase
>          Issue Type: Improvement
>          Components: client, regionserver
>    Affects Versions: 0.90.7, 0.92.1
>            Reporter: Todd Lipcon
>
> Currently if you pass a very restrictive filter to a scanner, along with a high caching value, you will end up causing RPC timeouts, lease exceptions, etc. Although this is a poor configuration and easy to work around by lowering caching, HBase should be resilient to a badly chosen caching value. As such, the scanner next() call should record the elapsed time, and after some number of seconds have passed, return any accumulated rows regardless of the caching value. This prevents the calls from starving out other threads or region operations.

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