Java8的OutOfMemoryError如何产生

测试类

public class PerGenTest {
	
	
	public static void main(String[] args) {
	    ArrayList<TestClass> list = new ArrayList<TestClass>();
		String i = "";
		while(true){
			i = i + "a";
			TestClass test = new TestClass();
			test.setName(i);
			list.add(test);
		}	
		
	}
	
}

引用类

public class TestClass {
	private static String staticName = "";
	private long a;
	
	public void setName(String name){
	    a = 100l;
		staticName = name;
	}
}

设置JVM启动参数（较小的Heap，较大的Meta（PerGen））：

-Xms1m -Xmx1m -XX:MaxMetaspaceSize=5M -XX:+HeapDumpOnOutOfMemoryError

结果：

引用

java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid9948.hprof ...
Heap dump file created [1834150 bytes in 0.023 secs]
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:3210)
at java.util.Arrays.copyOf(Arrays.java:3181)
at java.util.ArrayList.grow(ArrayList.java:261)
at java.util.ArrayList.ensureExplicitCapacity(ArrayList.java:235)
at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:227)
at java.util.ArrayList.add(ArrayList.java:458)
at OutMemoryTest.PerGenTest.main(PerGenTest.java:15)

设置JVM启动参数（较大的Heap，较小的Meta（PerGen））：

-Xms1m -Xmx1m -XX:MaxMetaspaceSize=5M -XX:+HeapDumpOnOutOfMemoryError

java.lang.OutOfMemoryError: Metaspace
Dumping heap to java_pid12916.hprof ...
Error occurred during initialization of VM
GC triggered before VM initialization completed. Try increasing NewSize, current value 2048K.