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https://issues.apache.org/jira/browse/HADOOP-11098?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14138283#comment-14138283
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Travis Thompson commented on HADOOP-11098:
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bq. According to the link, MaxDirectMemorySize sets the NIO buffer size. I
wouldn't expect that to be the same thing as the non-heap max.
Yeah after reading more it looks like that's definitely the case, I don't
remember what I initially read that lead me to believe that, it's been a while
since I actually looked at this (this ticket is a copy of an internal ticket).
It looks like this is probably related to "PermGen" going away and now having
"Metaspace", which is part of the heap now where PermGen was not (more [here |
http://javaeesupportpatterns.blogspot.com/2013/02/java-8-from-permgen-to-metaspace.html]).
Anyways, I haven't actually found a way to cap non-heap yet and I'm not sure
it's actually even necessary anymore?
> [JDK8] MaxDirectMemorySize default changed between JDK7 and 8
> -------------------------------------------------------------
>
> Key: HADOOP-11098
> URL: https://issues.apache.org/jira/browse/HADOOP-11098
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 2.3.0
> Environment: JDK8
> Reporter: Travis Thompson
>
> I noticed this because the NameNode UI shows "Max Non Heap Memory" which
> after some digging I found correlates to MaxDirectMemorySize.
> JDK7
> {noformat}
> Heap Memory used 16.75 GB of 23 GB Heap Memory. Max Heap Memory is 23.7 GB.
> Non Heap Memory used 57.32 MB of 67.38 MB Commited Non Heap Memory. Max Non
> Heap Memory is 130 MB.
> {noformat}
> JDK8
> {noformat}
> Heap Memory used 3.02 GB of 7.65 GB Heap Memory. Max Heap Memory is 23.7 GB.
> Non Heap Memory used 103.12 MB of 104.41 MB Commited Non Heap Memory. Max Non
> Heap Memory is -1 B.
> {noformat}
> More information in first comment.
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