Is it possible for a Java memory leak to use more memory than the heap + permgen? [duplicate]

Answer 1

Yes - it's possible. Java memory area is divided into few regions - heap and permgen are not all of them. There are also areas for code cache and native memory, which is quite popular for all of-heap structures. Please take a look at slide 7 of this presentation

Answer 2

Of course, it is possible. Simple examples are ByteBuffer.allocateDirect() and FileChannel.map(). The contents of such buffers is out of Java Heap.