Java元数据区域（MetaSpace）OOM

元数据区

元数据区取代了1.7版本及以前的永久代。元数据区和永久代本质上都是方法区的实现。方法区存放虚拟机加载的类信息，静态变量，常量等数据。

JVM配置

-XX:MetaspaceSize=10M 
-XX:MaxMetaspaceSize=10M 
-XX:+HeapDumpOnOutOfMemoryError

测试代码

public class MetaSpaceOOM {
    public static void main(String[] args) {
        while (true) {
            Enhancer enhancer=new Enhancer();
            enhancer.setSuperclass(OOMObject.class);
            enhancer.setUseCache(false);
            enhancer.setCallback(new MethodInterceptor() {
                @Override
                public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                    return methodProxy.invokeSuper(o,args);
                }
            });
            enhancer.create();
        }
    }

    static class OOMObject {

    }
}

运行结果

Dumping heap to java_pid2776.hprof ...
Heap dump file created [4179143 bytes in 0.023 secs]
Exception in thread "main" java.lang.OutOfMemoryError: Metaspace
    at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:538)
    at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:363)
    at org.springframework.cglib.proxy.Enhancer.generate(Enhancer.java:582)
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:131)
    at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:319)
    at org.springframework.cglib.proxy.Enhancer.createHelper(Enhancer.java:569)
    at org.springframework.cglib.proxy.Enhancer.create(Enhancer.java:384)
    at com.example.oom.MetaSpaceOOM.main(MetaSpaceOOM.java:21)

GC LOG

[GC (Allocation Failure) [PSYoungGen: 64512K->3311K(75264K)] 64512K->3327K(247296K), 0.0056889 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 
[GC (Allocation Failure) [PSYoungGen: 67823K->3272K(75264K)] 67839K->3296K(247296K), 0.0049203 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 
[GC (Metadata GC Threshold) [PSYoungGen: 39236K->3816K(75264K)] 39260K->3848K(247296K), 0.0040988 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 
[Full GC (Metadata GC Threshold) [PSYoungGen: 3816K->0K(75264K)] [ParOldGen: 32K->3694K(98816K)] 3848K->3694K(174080K), [Metaspace: 9913K->9913K(1058816K)], 0.0195453 secs] [Times: user=0.03 sys=0.00, real=0.02 secs] 
[GC (Last ditch collection) [PSYoungGen: 0K->0K(102400K)] 3694K->3694K(201216K), 0.0006640 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 
[Full GC (Last ditch collection) [PSYoungGen: 0K->0K(102400K)] [ParOldGen: 3694K->2157K(188928K)] 3694K->2157K(291328K), [Metaspace: 9913K->9913K(1058816K)], 0.0355431 secs] [Times: user=0.14 sys=0.02, real=0.05 secs] 
java.lang.OutOfMemoryError: Metaspace