????5??-Xnoclassgc disable class garbage collection
????????????????????
????6??-Xincgc enable incremental garbage collection
??????????????????????
????7??-Xloggc:<file> log GC status to a file with time stamps
??????????????????????????
????8??-Xbatch disable background compilation
?????????????
????9??-Xms<size> set initial Java heap size
????????JVM???????????С
????10??-Xmx<size> set maximum Java heap size
????????JVM????????С
????11??-Xss<size> set java thread stack size
????????JVM?????С
????12??-Xprof output cpu profiling data
????????CPU?????????
????13??-Xfuture enable strictest checks?? anticipating future default
???????????????飬?????????????
????14??-Xrs reduce use of OS signals by Java/VM (see documentation)
???????JVM????????????
????15??-Xcheck:jni perform. additional checks for JNI functions
??????JNI??????м??
????16??-Xshare:off do not attempt to use shared class data
??????????????ù??????????
????17??-Xshare:auto use shared class data if possible (default)
?????????????ù??????????
????18??-Xshare:on require using shared class data?? otherwise fail.
?????????????ù??????????????????????
?????????????Щ?????????????е??????ж??????????????????????????HelloWorl?????????????????????÷???????????
????????????:
????// HelloWorld.java
????public class HelloWorld {
????public static void main(String[] args){
????System.out.println("Hello World!");
????}
????}
???????????У?
????D:j2sdk15in>javac HelloWorld.java
????D:j2sdk15in>java -Xms256M -Xmx512M HelloWorld
????Hello World!