package com.msj.jvm;

/**

* 堆分配参数

*

* 在实际工作中，我们可以直接将初始的堆大小与最大堆大小设置相等，这样的好处是可以减少程序运行时的垃圾回收，从而提高性能。

*/

public class Test01 {

public static void main(String[] args) {

//-Xms5m -Xmx20m -XX:+PrintGCDetails -XX:+UseSerialGC -XX:+PrintCommandLineFlags

//查看GC信息

System.out.println("max memory:" + Runtime.getRuntime().maxMemory());

System.out.println("free memory:" + Runtime.getRuntime().freeMemory());

System.out.println("total memory:" + Runtime.getRuntime().totalMemory());

byte[] b1 = new byte[1*1024*1024];

System.out.println("分配了1M");

System.out.println("max memory:" + Runtime.getRuntime().maxMemory());

System.out.println("free memory:" + Runtime.getRuntime().freeMemory());

System.out.println("total memory:" + Runtime.getRuntime().totalMemory());

byte[] b2 = new byte[4*1024*1024];

System.out.println("分配了4M");

System.out.println("max memory:" + Runtime.getRuntime().maxMemory());

System.out.println("free memory:" + Runtime.getRuntime().freeMemory());

System.out.println("total memory:" + Runtime.getRuntime().totalMemory());

}

}