On May 10, 2010, at 3:45 PM, Ben wrote:

> - Is Activity Monitor likely just reporting this high tide value?

Yes.

> - Is the increase in memory usage (of about 50%) normal?

Yes. Remember, long integers and pointer variables are now twice as large in 
64-bit apps. And common Cocoa integer types like CFIndex and NSInteger are 
typedefs for long integers.

> - Either way, should I be concerned?

Two years ago I would have said yes, because when we published our first 64-bit 
program around that time, we had several users write in and tell us they 
thought the app was using too much memory. 64-bit apps were really rare back 
then, and people weren't used to seeing them, so we obliged and went back to 
32-bit. But now, 64-bit apps are far more common than they were back then, and 
a lot of the bugs in Leopard's 64-bit frameworks were fixed in Snow Leopard, so 
now I wouldn't hold back. There is more to the transition than having a higher 
VM ceiling, e.g. 64-bit apps will run faster than 32-bit apps on Intel CPUs due 
to improvements in the ABI.

> Lastly:
> - HeapDiff reports the worst offender for memory expansion between 32/64-bit 
> processes as NSCFDictionary. Instruments suggests it is CFBasicHash. Is 
> CFBasicHash part of the internals for NSCFDictionary? Google doesn't have 
> much info on this.

I think so. A lot of Foundation objects are actually class clusters, and 
NSDictionary is one of them.

Nick Zitzmann
<http://www.chronosnet.com/>

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