测试代码

class User{	}public class Program {		public static void main(String[] args) {		List
    
     list=new ArrayList<>();		while(true){			User user=new User();			list.add(user);		}	}}
    

配置JVM参数

-XX:+HeapDumpOnOutOfMemoryError -Xms20m -Xmx20m

运行报错

java.lang.OutOfMemoryError: Java heap spaceDumping heap to java_pid11944.hprof ...Heap dump file created [27895404 bytes in 0.123 secs]Exception in thread "main" java.lang.OutOfMemoryError: Java heap space	at java.util.Arrays.copyOf(Arrays.java:2245)	at java.util.Arrays.copyOf(Arrays.java:2219)	at java.util.ArrayList.grow(ArrayList.java:242)	at java.util.ArrayList.ensureExplicitCapacity(ArrayList.java:216)	at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:208)	at java.util.ArrayList.add(ArrayList.java:440)	at com.jvm.Program.main(Program.java:11)

在项目根目录下，有个快照文件，使用Eclipse Memory Analyzer打开

发现大部分内存被main线程占用了

而这些内存都用来保存User对象了