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https://issues.apache.org/jira/browse/CASSANDRA-1255?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12982492#action_12982492
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Jonathan Ellis edited comment on CASSANDRA-1255 at 1/17/11 1:20 AM:
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I expect this to show negligible performance impact on a fresh JVM, but since
column names on "static" CFs can be GCd almost 100% in young generation this
should result in a lower rate of promotion to old gen, which in turn means
lower rate of heap fragmentation and less frequent STW collections of old gen
to compact/defragment.
was (Author: jbellis):
I expect this to show negligible performance impact on a fresh JVM, but
once the heap starts getting fragmented this should result in a reduction in
promotion to old gen, since column names on "static" CFs can be GCd almost 100%
in young generation.
> Explore interning keys and column names
> ---------------------------------------
>
> Key: CASSANDRA-1255
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1255
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Stu Hood
> Assignee: Jonathan Ellis
> Priority: Minor
> Fix For: 0.7.1
>
> Attachments: 1255.txt
>
> Original Estimate: 8h
> Remaining Estimate: 8h
>
> With multiple Memtables, key caches and row caches holding DecoratedKey
> references, it could potentially be a huge memory savings (and relief to GC)
> to intern DecoratedKeys. Taking the idea farther, for the skinny row pattern,
> and for certain types of wide row patterns, interning of column names could
> be very beneficial as well (although we would need to wrap the byte[]s in
> something for hashCode/equals).
> This ticket should explore the benefits and overhead of interning.
> Google collections/guava MapMaker is a very convenient way to create this
> type of cache: example call:
> http://stackoverflow.com/questions/2865026/use-permgen-space-or-roll-my-own-intern-method/2865083#2865083
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