小编Qy *_*Zuo的帖子

下面的代码将分配大量的直接内存,但不会导致java.lang.OutOfMemoryError:直接缓冲内存:

//JVM args: -Xms10m -Xmx10m -XX:MaxDirectMemorySize=10m
    public class DirectMemoryOOM {
        public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException {
            Field f = Unsafe.class.getDeclaredFields()[0];
            f.setAccessible(true);
            Unsafe us = (Unsafe) f.get(null);
            long size = 1024 * 1024 * 1024;
            while (true) {
                long p = us.allocateMemory(size);
                for (int i = 0; i < size; i++) {
                    us.putByte(p + i, Byte.MAX_VALUE);
                }
            }
        }
    }

但代码下面的代码将获得java.lang.OutOfMemoryError:直接缓冲内存.我已经看到了Java不安全内存分配限制的答案,但ByteBuffer.allocateDirect是使用Unsafe.allocateMemory()实现的.

//JVM args: -Xms10m -Xmx10m -XX:MaxDirectMemorySize=10m
public class DirectMemoryOOM {
    public static …