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Posted to commits@cassandra.apache.org by "Michael Semb Wever (Jira)" <ji...@apache.org> on 2022/11/12 08:25:00 UTC
[jira] [Comment Edited] (CASSANDRA-18027) Use G1GC as default
[ https://issues.apache.org/jira/browse/CASSANDRA-18027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17632625#comment-17632625 ]
Michael Semb Wever edited comment on CASSANDRA-18027 at 11/12/22 8:24 AM:
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bq. Why MaxTenuringThreshold=1 ?
Answering my own question here.
Benchmarks show that G1 and Cassandra work best when objects are promoted immediately. That is the survival spaces give no benefit. A value of one is chosen over zero as it provides no performance difference but is assumed to be safer keeping one survival space for edge-case behaviour rather than remove them altogether.
A value of one was also the CMS default.
was (Author: michaelsembwever):
bq. Why MaxTenuringThreshold=1 ?
Answering my own question here.
Benchmarks show that G1 and Cassandra work best when objects are promoted immediately. That is the survival spaces give no benefit. A value of one is chosen over zero as it provides no performance difference but is assumed to be safer keeping one survival space for edge-case behaviour rather than remove them altogether.
> Use G1GC as default
> -------------------
>
> Key: CASSANDRA-18027
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18027
> Project: Cassandra
> Issue Type: Task
> Components: Local/Config
> Reporter: Michael Semb Wever
> Assignee: Michael Semb Wever
> Priority: Normal
>
> G1GC is well battle tested now, and the recommended configuration for most users. CMS can work well on smaller heaps but requires more tuning, initially and over time. G1GC just works. CMS was deprecated in JDK 9.
> Patch at https://github.com/apache/cassandra/compare/trunk...thelastpickle:cassandra:mck/7486/trunk
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