OutOfMemoryError溢出

Java堆溢出： java.lang.OutOfMemoryError: Java heap space 

/**
* VM Args：-Xms20m -Xmx20m -XX:+HeapDumpOnOutOfMemoryError
* @author zzm
*/
ublic class HeapOOM {
static class OOMObject {
}
public static void main(String[] args) {
    List<OOMObject> list = new ArrayList<OOMObject>();
    while (true) {
        list.add(new OOMObject());
    }
}
}
java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid3404.hprof ...
Heap dump file created [22045981 bytes in 0.663 secs]

2017-05-14T20:02:37.074+0800: [GC [PSYoungGen: 717K->568K(5952K)] 717K->568K(19648K), 0.0060602 secs] [Times: user=0.00 sys=0.00, real=0.01 secs] 
2017-05-14T20:02:37.081+0800: [Full GC (System) [PSYoungGen: 568K->0K(5952K)] [ParOldGen: 0K->485K(13696K)] 568K->485K(19648K) [PSPermGen: 2527K->2525K(21248K)], 0.0097560 secs] [Times: user=0.01 sys=0.00, real=0.01 secs] 
Exception in thread "main" java.lang.OutOfMemoryError: Direct buffer memory
	at java.nio.Bits.reserveMemory(Bits.java:658)
	at java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:123)
	at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:306)
	at Test.createThread(Test.java:22)
	at Test.main(Test.java:7)

 

注意： 对于 DirectByteBuffer 因为不是在虚拟机分配的，full gc 日志 体现不了 日志回收的情况

这样分配的内存不再是在java heap上，而是在C heap上

http://book.51cto.com/art/201107/278895.htm