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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-12976) Default hbase.client.scanner.max.result.size
Date Thu, 05 Feb 2015 05:59:35 GMT

     [ https://issues.apache.org/jira/browse/HBASE-12976?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Lars Hofhansl updated HBASE-12976:
    Attachment: 12976.txt

Trivial but important change.

Client can set caching as desired, the size of chunks between client and server is limited
to 2MB (unless a single row is larger than 2MB).

In my tests that made a *huge* difference in region server health and GC behavior (avoided
full GCs due to many handlers allocating too many big chunks for responses, while not impacting

> Default hbase.client.scanner.max.result.size
> --------------------------------------------
>                 Key: HBASE-12976
>                 URL: https://issues.apache.org/jira/browse/HBASE-12976
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Lars Hofhansl
>             Fix For: 2.0.0, 1.0.1, 0.94.27, 0.98.11
>         Attachments: 12976.txt
> Setting scanner caching is somewhat of a black art. It's hard to estimate ahead of time
how large the result set will be.
> I propose we hbase.client.scanner.max.result.size to 2mb. That is good compromise between
performance and buffer usage on typical networks (avoiding OOMs when the caching was chosen
too high).
> To an HTable client this is completely transparent.

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