Application memory use

[Michael Hall]

On Apr 23, 2012, at 4:28 AM, Henri Gomez wrote:

>> Both showed as 64 bit in Activity Monitor.
>> This may very well be the largest part of it but the JConsole heap graphs
>> looked considerably different between the two applications and the
>> information seemed to indicate different methods for gc. I guess I was
>> wondering if there is anything we should know about this as well?
> 
> 64bits Hotspot (6u23 and later) JVMs switch automatically to
> Compressed Pointers (-XX:+UseCompressedOops), saving memory.
> 
> http://docs.oracle.com/javase/7/docs/technotes/guides/vm/performance-enhancements-7.html

I will read that. Thanks. I'm wondering now if I can determine if this does more or less completely explain the difference.
Can I get the Java 6 to show about the same memory use as the Java 7?
If there is an option to turn the switch off that you mention I could try that.
Otherwise I was wondering if starting the Java 6 jvm -d64, iirc, or whatever it is to indicate it should use 64 bit would also accomplish eliminating the compression?
For a while watching JConsole it appeared Java 7 wasn't going to give any memory back at while while 6 showed to briefly climb and drop back down in a narrower range in the sawtooth pattern mentioned earlier. I would think this might mean some difference in the maximum memory footprint.