DirectMemory溢出

package com.quancheng.jvm.oom;

import java.lang.reflect.Field;

import sun.misc.Unsafe;

// -Xmx20M -XX:MaxDirectMemorySize=10M
public class DirectMemoryTest {

    public static void main(String[] args) throws IllegalArgumentException, IllegalAccessException {
        Field field = sun.misc.Unsafe.class.getDeclaredFields()[0];
        field.setAccessible(true);
        sun.misc.Unsafe unsafe = (Unsafe) field.get(null);
        while (true) {
            unsafe.allocateMemory(64 * 1024 * 1024);
        }
    }
}

output============================================
java(16010,0x700002d01000) malloc: *** mach_vm_map(size=67108864) failed (error code=3)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
Exception in thread "main" java.lang.OutOfMemoryError
    at sun.misc.Unsafe.allocateMemory(Native Method)
    at com.quancheng.jvm.oom.DirectMemoryTest.main(DirectMemoryTest.java:15)