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https://issues.apache.org/jira/browse/TRAFODION-2566?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15960912#comment-15960912
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ASF GitHub Bot commented on TRAFODION-2566:
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Github user asfgit closed the pull request at:
https://github.com/apache/incubator-trafodion/pull/1045
> Reduce the virtual memory allocated in Trafodion processes with JDK1.8
> ----------------------------------------------------------------------
>
> Key: TRAFODION-2566
> URL: https://issues.apache.org/jira/browse/TRAFODION-2566
> Project: Apache Trafodion
> Issue Type: Improvement
> Components: sql-exe
> Affects Versions: 2.1-incubating
> Reporter: Selvaganesan Govindarajan
> Assignee: Selvaganesan Govindarajan
>
> It is observed that JDK1.8 uses native memory to store class metadata in lieu
> of permanent generation of earlier releases. By default, JVM mmaps 1 GB of
> virtual address space to the process. Because Trafodion SQL processes are not
> generic JVM processes, it is viable to reduce the default JVM mmap for the
> class metadata
> In JVM1.8
> A simple hello world java program shows the following:
> Heap Configuration when java invoked as
> java -Xmx512m Sample
> MinHeapFreeRatio = 0
> MaxHeapFreeRatio = 100
> MaxHeapSize = 536870912 (512.0MB)
> NewSize = 178782208 (170.5MB)
> MaxNewSize = 178782208 (170.5MB)
> OldSize = 358088704 (341.5MB)
> NewRatio = 2
> SurvivorRatio = 8
> MetaspaceSize = 21807104 (20.796875MB)
> CompressedClassSpaceSize = 1073741824 (1024.0MB)
> MaxMetaspaceSize = 17592186044415 MB
> G1HeapRegionSize = 0 (0.0MB)
> Heap Configuration when Java is invoked as
> java -XX:MaxMetaspaceSize=256m -XX:CompressedClassSpaceSize=256m -Xmx=512m
> Sample
> MinHeapFreeRatio = 0
> MaxHeapFreeRatio = 100
> MaxHeapSize = 536870912 (512.0MB)
> NewSize = 178782208 (170.5MB)
> MaxNewSize = 178782208 (170.5MB)
> OldSize = 358088704 (341.5MB)
> NewRatio = 2
> SurvivorRatio = 8
> MetaspaceSize = 21807104 (20.796875MB)
> CompressedClassSpaceSize = 268435456 (256.0MB)
> MaxMetaspaceSize = 268435456 (256.0MB)
> G1HeapRegionSize = 0 (0.0MB)
> With JDK 1.7
> $JAVA_HOME/bin/java -Xmx512m Sample
> Heap Configuration:
> MinHeapFreeRatio = 0
> MaxHeapFreeRatio = 100
> MaxHeapSize = 536870912 (512.0MB)
> NewSize = 1310720 (1.25MB)
> MaxNewSize = 17592186044415 MB
> OldSize = 5439488 (5.1875MB)
> NewRatio = 2
> SurvivorRatio = 8
> PermSize = 21757952 (20.75MB)
> MaxPermSize = 85983232 (82.0MB)
> G1HeapRegionSize = 0 (0.0MB)
> Permanent Generation in 1.7 is equivalent to MaxMetaDataSpace. I am planning
> to reduce both MaxMetaspaceSize and CompressedClassSpace Size to 128MB.
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