Selvaganesan Govindarajan created TRAFODION-2566:
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Summary: 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 lie of
permanent generation in 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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