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https://issues.apache.org/jira/browse/HDDS-3173?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17058754#comment-17058754
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Arpit Agarwal edited comment on HDDS-3173 at 3/13/20, 2:10 PM:
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The other option is we spend time testing with G1GC to arrive at a set of
parameters that work well and use those for all the JDK versions.
IMO the decision to remove CMS GC in JDK14 is asinine, since [JEP
363|http://openjdk.java.net/jeps/363] acknowledges that there is still an
overhead to the CMS alternatives. The Java committee has become obsessed with
bi-annual breaking upgrades destroying the very stability that made Java
appealing for enterprise applications like Hadoop. /rant.
We don't have to participate in the insanity by targeting the bleeding edge JDK
version. :)
was (Author: arpitagarwal):
The other option is we spend time testing with G1GC to arrive at a set of
parameters that work well and use those for all the JDK versions.
IMO the decision to remove CMS GC in JDK14 is asinine, since [JEP
363|http://openjdk.java.net/jeps/363] acknowledges that there is still an
overhead to the CMS alternatives. The Java committee has become obsessed with
bi-annual breaking upgrades destroying the very stability that made Java
appealing for enterprise applications like Hadoop. /rant.
> Provide better default JVM options
> ----------------------------------
>
> Key: HDDS-3173
> URL: https://issues.apache.org/jira/browse/HDDS-3173
> Project: Hadoop Distributed Data Store
> Issue Type: Improvement
> Affects Versions: 0.5.0
> Reporter: Marton Elek
> Priority: Blocker
>
> The GC pressure on Datanode is high because of the retry cache. I found
> crashes due to the long GC pauses. I started to use the following JVM
> parameters:
> {code}
> -server -XX:ParallelGCThreads=8 -XX:+UseConcMarkSweepGC
> -XX:CMSInitiatingOccupancyFraction=70 -XX:+UseCMSInitiatingOccupancyOnly
> {code}
> Which provide stable output.
> It would be great to detect the current version and add these parameters, if
> required.
> But there are two problems:
> * Different java versions support different flags
> * There could be conflicting flags (eg. if the user defines to use G1 we
> shouldn't add any other default parameters).
> I am not sure (yet) what is the best approach, I opened this issue to start a
> discussion.
> /cc [~arp]
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