-XX:SurvivorRatio

news2024/9/28 1:15:09

-XX:SurvivorRatio
`-XXSurvivorRatio = eden ：from = eden ：to`
默认`-XXSurvivorRatio=8`，即 Eden : s0 : s1 = 8 : 1 : 1，Eden占了年轻代的8/10，不建议修改

在这里插入图片描述

case1: `-XX:NewRatio=4 -XX:SurvivorRatio=8`

启动参数
-Xmx200m -Xms100m `-XX:NewRatio=4 -XX:SurvivorRatio=8` -XX:+PrintCommandLineFlags

启动日志
-XX:ConcGCThreads=3 -XX:G1ConcRefinementThreads=13 -XX:GCDrainStackTargetSize=64 `-XX:InitialHeapSize=104857600` -XX:MarkStackSize=4194304 `-XX:MaxHeapSize=209715200` -XX:MinHeapSize=104857600 `-XX:NewRatio=4` -XX:+PrintCommandLineFlags -XX:ReservedCodeCacheSize=251658240 -XX:+SegmentedCodeCache `-XX:SurvivorRatio=8` -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseG1GC -XX:-UseLargePagesIndividualAllocation

JPS+jhsdb jmap --heap --pid 进程ID
Heap Configuration: MinHeapFreeRatio = 40 MaxHeapFreeRatio = 70 MaxHeapSize = 209715200 (200.0MB) NewSize = 1363144 (1.2999954223632812MB) MaxNewSize = 41943040 (40.0MB) OldSize = 5452592 (5.1999969482421875MB) NewRatio = 4 SurvivorRatio = 8 MetaspaceSize = 22020096 (21.0MB) CompressedClassSpaceSize = 1073741824 (1024.0MB) MaxMetaspaceSize = 17592186044415 MB G1HeapRegionSize = 1048576 (1.0MB)

case 2 : `-Xmn80m -XX:SurvivorRatio=8`

启动参数
-Xmx200m -Xms100m `-Xmn80m -XX:SurvivorRatio=8` -XX:+PrintCommandLineFlags

启动日志
-XX:ConcGCThreads=3 -XX:G1ConcRefinementThreads=13 -XX:GCDrainStackTargetSize=64 `-XX:InitialHeapSize=104857600` -XX:MarkStackSize=4194304 `-XX:MaxHeapSize=209715200` `-XX:MaxNewSize=83886080` -XX:MinHeapSize=104857600 `-XX:NewSize=83886080` -XX:+PrintCommandLineFlags -XX:ReservedCodeCacheSize=251658240 -XX:+SegmentedCodeCache -XX:SurvivorRatio=8 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseG1GC -XX:-UseLargePagesIndividualAllocation

JPS+jhsdb jmap --heap --pid 进程ID
Heap Configuration: MinHeapFreeRatio = 40 MaxHeapFreeRatio = 70 MaxHeapSize = 209715200 (200.0MB) NewSize = 83886080 (80.0MB) MaxNewSize = 83886080 (80.0MB) OldSize = 5452592 (5.1999969482421875MB) NewRatio = 2 SurvivorRatio = 8 MetaspaceSize = 22020096 (21.0MB) CompressedClassSpaceSize = 1073741824 (1024.0MB) MaxMetaspaceSize = 17592186044415 MB G1HeapRegionSize = 1048576 (1.0MB)

在这里插入图片描述

（好早以前验证截图,删除可惜保留参考）

case1: `-XX:NewRatio=4 -XX:SurvivorRatio=8`

//JVM 启动参数
-Xmx40m -Xms20m -XX:NewRatio=4 -XX:SurvivorRatio=8  -XX:+PrintGCDetails -XX:+PrintCommandLineFlags

//运行结果：
-XX:InitialHeapSize=20971520 -XX:MaxHeapSize=41943040 -XX:NewRatio=4 -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -XX:SurvivorRatio=8 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:-UseLargePagesIndividualAllocation -XX:+UseParallelGC

在这里插入图片描述

case 2 : `-Xmn80m -XX:SurvivorRatio=8`

//JVM 启动参数
-Xmx400m -Xms200m -Xmn100m -XX:SurvivorRatio=8  -XX:+PrintGCDetails -XX:+PrintCommandLineFlags

//运行结果：
-XX:InitialHeapSize=20,971,520 -XX:MaxHeapSize=41,943,040 
-XX:MaxNewSize=104,857,600 -XX:NewSize=104,857,600 -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -XX:SurvivorRatio=8 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:-UseLargePagesIndividualAllocation -XX:+UseParallelGC

在这里插入图片描述

case 3 : -Xmn + -XX:SurvivorRatio & -Xmn > -Xmx

//JVM 启动参数
-Xmx40m -Xms20m -Xmn100m -XX:SurvivorRatio=8  -XX:+PrintGCDetails -XX:+PrintCommandLineFlags

//运行结果：
-XX:InitialHeapSize=20,971,520 -XX:MaxHeapSize=41,943,040 
-XX:MaxNewSize=104,857,600 -XX:NewSize=104,857,600 -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -XX:SurvivorRatio=8 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:-UseLargePagesIndividualAllocation -XX:+UseParallelGC