jvm启动参数NewRatio不生效

Posted on | Edited on | In ,

现象：jvm启动参数的配置，由于-Xmn的值优先级更高，所以NewRatio会被-Xmn覆盖。见下面的测试：

1
2
3
4
5
6
7
8
9
# 这里NewSize是20MB
java -Xmn20M -XX:NewRatio=2 -Xms50M -XX:+PrintFlagsFinal -version | grep -E '(Old|New)Size'
    uintx MaxNewSize                               := 20971520                            {product}
    uintx NewSize                                  := 20971520                            {product}
    uintx NewSizeThreadIncrease                     = 5320                                {pd product}
    uintx OldSize                                  := 31457280                            {product}
openjdk version "1.8.0_222"
OpenJDK Runtime Environment (build 1.8.0_222-b10)
OpenJDK 64-Bit Server VM (build 25.222-b10, mixed mode)                       {product}
1
2
3
4
5
6
7
8
9
#这里是50MB的1/3，可见NewRatio生效了
java -XX:NewRatio=2 -Xms50M -XX:+PrintFlagsFinal -version | grep -E '(Old|New)Size'
    uintx MaxNewSize                               := 1073741824                          {product}
    uintx NewSize                                  := 17301504                            {product}
    uintx NewSizeThreadIncrease                     = 5320                                {pd product}
    uintx OldSize                                  := 35127296                            {product}
openjdk version "1.8.0_222"
OpenJDK Runtime Environment (build 1.8.0_222-b10)
OpenJDK 64-Bit Server VM (build 25.222-b10, mixed mode)