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https://issues.apache.org/jira/browse/CASSANDRA-1968?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12984580#action_12984580
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Jonathan Ellis commented on CASSANDRA-1968:
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Yes, I meant young gen.
An insert-heavy workload will have more of the young gen survive since we have
to keep data around in memtables until flush. With a read-heavy load almost
all of it is discarded. Here are some ParNew collections with about a 1.5G
young gen, mTT=1, serving mostly reads:
{code}
49527.273: [GC 49527.274: [ParNew
Desired survivor size 107347968 bytes, new threshold 1 (max 1)
- age 1: 15782840 bytes, 15782840 total
: 1696530K->21789K(1887488K), 0.0737280 secs] 6279370K->4617936K(12373248K),
0.0745280 secs] [Times: user=0.41 sys=0.00, real=0.07 secs]
Total time for which application threads were stopped: 0.1053180 seconds
49534.739: [GC 49534.739: [ParNew
Desired survivor size 107347968 bytes, new threshold 1 (max 1)
- age 1: 14990096 bytes, 14990096 total
: 1699613K->18988K(1887488K), 0.0777830 secs] 6295760K->4629494K(12373248K),
0.0786270 secs]
{code}
> Increase JVM young generation size
> ----------------------------------
>
> Key: CASSANDRA-1968
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1968
> Project: Cassandra
> Issue Type: Improvement
> Affects Versions: 0.7.0
> Reporter: Brandon Williams
> Assignee: Brandon Williams
> Fix For: 0.7.1
>
> Attachments: 1968.txt, 1968_v2.txt
>
> Original Estimate: 4h
> Remaining Estimate: 4h
>
> Increasing the young generation size has a profound effect on performance and
> cpu utilization. We should set it explicitly.
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