获取对象占用内存

1. 添加依赖

   
   	org.apache.lucene
   	lucene-core
   	4.0.0
   
   

2. 添加vm启动参数

   --add-opens java.base/java.lang=ALL-UNNAMED --add-opens java.base/java.util=ALL-UNNAMED --add-opens java.base/java.nio=ALL-UNNAMED --add-opens java.base/sun.nio.ch=ALL-UNNAMED
   

3. 编写测试代码

   public static void main(String[] args) throws Exception {
   	List list = new ArrayList<>() ;
   	for (int i = 0; i < 1000000; i++) {
   		list.add(new ChannelUserDTO()) ;
   	}
   	log.info("size 2: {}", RamUsageEstimator.humanSizeOf(list));
   }