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https://issues.apache.org/jira/browse/CASSANDRA-5661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13701495#comment-13701495
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Ben Manes edited comment on CASSANDRA-5661 at 7/7/13 3:35 AM:
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"rarely explicitly invalidated" is in regards to a cache, as Jonathan
originally described the problem as a multimap cache instead of as an object
pool. He also expressed concern with evicting a block of buffers at once when
he conceived of the same model that you implemented.
I am intimately familiar with Guava's cache as I designed the algorithms,
ported and wrote code for it, and advised on the api. Unfortunately I am not
familiar with Cassandra's needs and its code, so the pool was implemented based
on a brief description of the problem and ideal behavior.
It was a fun exercise for a long weekend. I'd recommend writing tests and
benchmarks, which unfortunately appears to be missing with the patch in its
current form. Of couse use whatever makes the most sense.
was (Author: ben.manes):
"rarely explicitly invalidated" is regards to a cache, as Jonathan
originally described the problem as a multimap cache instead of as an object
pool. He also expressed concern with evicting a block of buffers at once when
he conceived of the same model that you implemented.
I am intimately familiar with Guava's cache as I designed the algorithms,
ported and wrote code for it, and advised on the api. Unfortunately I am not
familiar with Cassandra's needs and its code, so the pool was implemented based
on a brief description of the problem and ideal behavior.
It was a fun exercise for a long weekend. I'd recommend writing tests and
benchmarks, which unfortunately appears to be missing with the patch in its
current form. Of couse use whatever makes the most sense.
> Discard pooled readers for cold data
> ------------------------------------
>
> Key: CASSANDRA-5661
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5661
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.2.1
> Reporter: Jonathan Ellis
> Assignee: Pavel Yaskevich
> Fix For: 1.2.7
>
> Attachments: CASSANDRA-5661.patch, DominatorTree.png, Histogram.png
>
>
> Reader pooling was introduced in CASSANDRA-4942 but pooled
> RandomAccessReaders are never cleaned up until the SSTableReader is closed.
> So memory use is "the worst case simultaneous RAR we had open for this file,
> forever."
> We should introduce a global limit on how much memory to use for RAR, and
> evict old ones.
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