A three parameter types
1, the standard parameters: relatively stable, future versions will be retained
-help
-version
2, -X parameter (non-standard parameters)
-Xint
-Xcomp
3, -XX parameters (non-standard parameter, a higher utilization rate)
-XX:newSize
-XX:+UseSerialGC
Second, the standard parameters
Generally very stable and will not change in the future jvm version, you can use java -help retrieve all the standard parameters.
Three, -X parameters
Non-standard options are subject to change without notice.
Use Java -X -X is retrieved parameters.
-Xint，-Xcomp，-Xmixed
-Xint forces perform all JVM byte code, can slow, commonly 10 times or more.
-Xcomp and -Xint contrast, will all the byte code compiled to native code.
-Xmixed mixed mode is the default mode JVM is recommended.
Four, -XX parameters
JVM is mainly used for tuning and debug operations. There are two, boolean and non-boolean type type.
boolean type
Format: -XX [+ -] <name> represents enable or disable <name> attribute.
Such as: -XX + DisableExplicitGC express prohibition of calling gc operating manual, which is System.gc () is invalid.
Non-boolean type
Format: -XX: <name> = <value> represents <name> attribute value <value>.
Such as: -XX: NewRatio = 1 represents the ratio of old and new generation's.
-Xms and -Xmx parameters
-Xms512m: equivalent to -XX: InitialHeapSize = 512m, provided the initial heap memory of 512M.
-Xmx2048m: equivalent to -XX: MaxHeapSize = 2048m, set the maximum heap memory to 2048M.