On Oct 2, 2009, at 7:42 AM, Mike Abdullah wrote:
While using this code in an experimental project I found the app was
routinely using 500+ MB of RAM. When measured with Instruments I
realised that every time you use a character set for string
scanning, Foundation internally copies it, presumably to ensure it
has an immutable object to work with. As a result, potentially
thousands of copies are being created, resulting in either:
A) Outrunning the garbage collector
B) Spending far more time allocating and deallocating character sets
than doing the actual scanning
Easiest solution is just to make a single copy yourself early on.
Also the docs for NSMutableCharacterSet do point out that it's
inefficient but don't really offer any detail.
Very good to know, thanks, Mike. You might want to post a comment
on the macresearch.org page so Drew can adjust the example.
Do you happen to remember what percentage of difference you were
able to achieve? It's fine if not - it's not too difficult to set up a
test. :-)
--
I.S.
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