Troy Rollins wrote:
On Jul 12, 2004, at 11:41 PM, Richard Gaskin wrote:
Yes, it takes almost six times longer to access a property than it does to access a local var. Run the benchmarking script below; on my modest single-processor G4 it gets:
Props: 62 ms Vars: 12 ms
Hmm. Very interesting, my "modest" 1gHz G4 shows the same results for vars exactly, but props ran 274ms... roughly 20 times as long.
Does 0.124ms per access have you tapping your foot with impatience? ;)
I wonder what accounts for the difference. My PB has an L3 cache, 768MB RAM, OS X 10.3.4. Any other differences we might look at?
So, it would be safe to say that vars are considerably faster, as Jacque said. But, at least until I learn some new techniques, are way more limited, to my thinking.
But then, here is something interesting, based on an adaptation of your benchmark script (note that the array even uses a slower repeat structure.) -
Props: 274 Vars: 12 Array: 129
on mouseUp put 10000 into N -- put the millisecs into s repeat n set the uTest of this stack to "hello world" get the uTest of this stack end repeat put the millisecs - s into s1
-- put the millisecs into s repeat n put "Hello World" into tMyVar get tMyVar end repeat put the millisecs - s into s2 -- put the milliSecs into s repeat with i = 1 to n put "Hello world" into tMyVar[i] get tMyVar[i] end repeat put the milliSecs - s into s3
put "Props: "&s1 &cr& "Vars: "& s2 &CR& "Array: " & s3 end mouseUp
Storing a single value to overwrite the entire contents of a single var will be hard to beat.
But to compare apples to apples more closely, we might modify tests 1 and 2 to store values indexed by i:
on mouseUp
put 10000 into N
--
put the millisecs into s
repeat with i = 1 to n
set the uTest[i] of this stack to "hello world"
get the uTest[i] of this stack
end repeat
put the millisecs - s into s1 --
put the millisecs into s
repeat with i = 1 to n
put "Hello World" into line i of tMyVar
get line i of tMyVar
end repeat
put the millisecs - s into s2
--
put the milliSecs into s
repeat with i = 1 to n
put "Hello world" into tMyVar[i]
get tMyVar[i]
end repeat
put the milliSecs - s into s3put "Props: "&s1 &cr& "Vars: "& s2 &CR& "Array: " & s3 end mouseUp
And here we see that delimited vars don't scale well in indexed accesses:
Props: 165 ms Vars: 17155 ms Array: 110 ms
It's interesting to see how close the times are for the object-based properties and the variable-based arrays. This would be jaw-dropping in any other xTalk, as most others page objects from disk and you know what that does to performance, but just another benefit of the always-in-RAM way that Rev deals with stack files.
And all the while, just one line away from being saved to disk if needed.
If the ~40% difference in execution speed is critical (here that amounts to 0.0055ms per access), remember you can always store an array into an object's custom props if needed:
put the customProperties of stack tMyStack into tMyArray set the customProperties of stack tMyStack to tMyArray
I recently got Vitual PC (so I can build Win installers for clients on the train to Monterey, believe it or not), and I find the ability to shut it down mid-session and return to the restored session very convenient. It's given me a new appreciation for saving state data, something I'll be adding more of to my apps going forward. After working with Virtual PC, my ideal is to get the user back to as close to the same state they were in during their last session as possible.
-- Richard Gaskin Fourth World Media Corporation ___________________________________________________ Rev tools and more: http://www.fourthworld.com/rev
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