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From "Jean-Daniel Cryans (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-3484) Replace memstore's ConcurrentSkipListMap with our own implementation
Date Thu, 05 Apr 2012 21:50:25 GMT

     [ https://issues.apache.org/jira/browse/HBASE-3484?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jean-Daniel Cryans updated HBASE-3484:
--------------------------------------

    Attachment: memstore_drag.png

This is what the slow down currently looks like when using big MemStores. In this graph I
flush at around 6GB and there's only 1 region per RS. It seems that the top speed is 100k/s
which happens at the very beginning and it can go down to 40k/s.

For those wondering, the dips are caused because we max out our links when the flushes happen
all at the same time.
                
> Replace memstore's ConcurrentSkipListMap with our own implementation
> --------------------------------------------------------------------
>
>                 Key: HBASE-3484
>                 URL: https://issues.apache.org/jira/browse/HBASE-3484
>             Project: HBase
>          Issue Type: Improvement
>          Components: performance
>    Affects Versions: 0.92.0
>            Reporter: Todd Lipcon
>            Priority: Critical
>         Attachments: hierarchical-map.txt, memstore_drag.png
>
>
> By copy-pasting ConcurrentSkipListMap into HBase we can make two improvements to it for
our use case in MemStore:
> - add an iterator.replace() method which should allow us to do upsert much more cheaply
> - implement a Set directly without having to do Map<KeyValue,KeyValue> to save
one reference per entry
> It turns out CSLM is in public domain from its development as part of JSR 166, so we
should be OK with licenses.

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