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https://issues.apache.org/jira/browse/CASSANDRA-3427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13149312#comment-13149312
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Mck SembWever edited comment on CASSANDRA-3427 at 11/14/11 9:44 AM:
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bq. Does heap usage stay high-post startup? Can you try forcing a full GC to
check that?
Yes. GC doesn't seem to help, i'll attach a munin graph that shows it over
time. It was running for a number of days just under 20G, but you can see from
that how "squeezed" it was.
(invoking full gc via jmx has no noticeable effect on heap used)
was (Author: michaelsembwever):
bq. Does heap usage stay high-post startup? Can you try forcing a full GC
to check that?
Yes. GC doesn't seem to help, i'll attach a munin graph that shows it over
time. It was running for a number of days just under 20G, but you can see from
that how "squeezed" it was.
> CompressionMetadata is not shared across threads, we create a new one for
> each read
> -----------------------------------------------------------------------------------
>
> Key: CASSANDRA-3427
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3427
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.0.0
> Reporter: Sylvain Lebresne
> Assignee: Sylvain Lebresne
> Labels: compression
> Fix For: 1.0.2
>
> Attachments: 3427.patch, 3427_v2.patch, CASSANDRA-3427.patch,
> jmx_jvm_memory-month.png, jmx_jvm_memory-week.png
>
>
> The CompressionMetada holds the compressed block offsets in memory. Without
> being absolutely huge, this is still of non-negligible size as soon as you
> have a bit of data in the DB. Reallocating this for each read is a very bad
> idea.
> Note that this only affect range queries, since "normal" queries uses
> CompressedSegmentedFile that does reuse a unique CompressionMetadata instance.
> ( Background: http://thread.gmane.org/gmane.comp.db.cassandra.user/21362 )
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