Java common memory overflow exceptions and code implementation

/**
 * @author xiongyongshun
 * VM Args: java -Xms10m -Xmx10m -XX:+HeapDumpOnOutOfMemoryError
 */
public class OutOfMemoryErrorTest {
    public static void main(String[] args) {
        List<Integer> list = new ArrayList<>();
        int i = 0;
        while (true) {
            list.add(i++);
        }
    }
}

>>> java -Xms10m -Xmx10m -XX:+HeapDumpOnOutOfMemoryError com.test.OutOfMemoryErrorTest                                                                                            16-10-02 23:35
java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid1810.hprof ...
Heap dump file created [14212861 bytes in 0.125 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 com.test.OutOfMemoryErrorTest.main(OutOfMemoryErrorTest.java:15)

/**
 * @author xiongyongshun
 * VM Args: java -Xss64k
 */
public class OutOfMemoryErrorTest {
    public static void main(String[] args) {
        stackOutOfMemoryError(1);
    }
    public static void stackOutOfMemoryError(int depth) {
        depth++;
        stackOutOfMemoryError(depth);
    }
}

Exception in thread "main" java.lang.StackOverflowError
    at com.test.OutOfMemoryErrorTest.stackOutOfMemoryError(OutOfMemoryErrorTest.java:27)

, 因为 JDK8 已经移除了永久代, 取而代之的是 metaspace, 因此在 JDK8 中, 下面两个例子都不会导致 java.lang.OutOfMemoryError: PermGen space 异常.

, 上面所说的 String.intern() 方法和常量池的内存分布仅仅针对于 JDK 1.6 及之前的版本, 在 JDK 1.7 或以上的版本中, 由于去除了永久代的概念, 因此内存布局稍有不同.

/**
 * @author xiongyongshun
 * VM Args:  -XX:PermSize=10M -XX:MaxPermSize=10M 
 */
public class RuntimeConstantPoolOOMTest {
    public static void main(String[] args) {
        List<String> list = new ArrayList<String>();
        int i = 0;
        while (true) {
            list.add(String.valueOf(i++).intern());
        }
    }
}

Exception in thread "main" java.lang.OutOfMemoryError: PermGen space
        at java.lang.String.intern(Native Method)
        at com.test.RuntimeConstantPoolOOMTest.main(RuntimeConstantPoolOOMTest.java:16)

, 如果通过 JDK1.8 来编译运行上面代码的话, 会有如下警告, 并且不会产生任何的异常:

>>> java -XX:PermSize=10M -XX:MaxPermSize=10M com.test.RuntimeConstantPoolOOMTest                                                                                                  16-10-03 0:23
Java HotSpot(TM) 64-Bit Server VM warning: ignoring option PermSize=10M; support was removed in 8.0
Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=10M; support was removed in 8.0

//VM Args:  -XX:PermSize=10M -XX:MaxPermSize=10M
public class MethodAreaOOMTest {
    public static void main(String[] args) {
        while (true) {
            Enhancer enhancer = new Enhancer();
            enhancer.setSuperclass(MethodAreaOOMTest.class);
            enhancer.setUseCache(false);
            enhancer.setCallback(new MethodInterceptor() {
                public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                    return methodProxy.invokeSuper(o, objects);
                }
            });
            enhancer.create();
        }
    }
}

Caused by: java.lang.OutOfMemoryError: PermGen space
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(ClassLoader.java:637)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
        ... 11 more

//VM Args: -XX:MaxMetaspaceSize=10M
public class MethodAreaOOMTest {
    public static void main(String[] args) {
        while (true) {
            Enhancer enhancer = new Enhancer();
            enhancer.setSuperclass(MethodAreaOOMTest.class);
            enhancer.setUseCache(false);
            enhancer.setCallback(new MethodInterceptor() {
                public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                    return methodProxy.invokeSuper(o, objects);
                }
            });
            enhancer.create();
        }
    }
}

>>> java -jar -XX:MaxMetaspaceSize=10M target/Test-1.0-SNAPSHOT.jar
Exception in thread "main" java.lang.OutOfMemoryError: Metaspace
    at net.sf.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:345)
    at net.sf.cglib.proxy.Enhancer.generate(Enhancer.java:492)
    at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:114)
    at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:291)
    at net.sf.cglib.proxy.Enhancer.createHelper(Enhancer.java:480)
    at net.sf.cglib.proxy.Enhancer.create(Enhancer.java:305)
    at com.test.MethodAreaOOMTest.main(MethodAreaOOMTest.java:22)