[jira] [Created] (HDDS-3173) Provide better default JVM options

["Marton Elek (Jira)" <ji...@apache.org>]

Marton Elek created HDDS-3173:
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             Summary: 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
            Reporter: Marton Elek


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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