#### DirectMemory溢出 DirectMemory容量可通过-XX:MaxDirectMemorySize指定，如果不指定则默认与JAVA堆最大值\(-Xmx\)一样 ``` 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) ```