Re: [flexcoders] speed of the for each looping
Sorry, couldn't resist commenting on the term cognitive cruft! I love it! :)) On Wed, Dec 10, 2008 at 12:37, Maciek Sakrejda [EMAIL PROTECTED] wrote: Interesting. I decided to actually try my test above, and on 100 items, the for-each version takes ~50 milliseconds, versus ~25 milliseconds for the explicitly indexed loop. When doing some actual work in the loop (a trace), the numbers are 41.9 seconds for the for-each and 41.1 seconds for the indexed for. On a loop with a trace with 100 items, both forms take ~5 milliseconds. This is rather unscientific, but I don't have the profiler available (will it ever make it to Linux, Adobe?). So yes, it looks like for-each is a lot slower in some cases, but I'll maintain it still probably won't make a difference unless you've got a massive loop that does very little, or a deeply nested set of loops. Consider also the readability and maintainability benefits of a for-each: unless you need the index, it's just one more place to introduce bugs when refactoring, and it's cognitive cruft when trying to follow what's going on. -- Maciek Sakrejda Truviso, Inc. http://www.truviso.com
[flexcoders] speed of the for each looping
Hi, all you experts :)
I'm tying to speed up my application and I use a lot of
exsample
for (var i:int = 0; i 5; i++)
{
trace(i);
}
so is the for each looping faster ?
Re: [flexcoders] speed of the for each looping
If you're trying to speed up your application, you should use the
profiler. Something like the difference between a manually indexed for
loop and a for-each loop is almost certain to be trivial.
If you don't have the profiler, run an ad-hoc perf test by doing
something like
// we need to construct something to iterate over:
var iterations:int = 100;
var arr:Array = [];
for (var i:int = 0; i iterations; i++) arr.push(i);
var dummy:int = 0;
var forBeginning:Number = new Date().getTime();
for (var j:int = 0; j iterations; j++)
{
// we need to do something in the loop so the whole thing
// is not just optimized out (not sure if FP does this, but
// it can), but we don't want to use trace() since I/O is
// relatively expensive compared to the cost of the loop itself
dummy = arr[j];
}
trace(for loop took + (new Date().getTime() - forBeginning) +
milliseconds);
var forEachBeginning:Number = new Date().getTime();
for each (var k:int in arr)
{
dummy = k;
}
trace(for-each loop took + (new Date().getTime() - forEachBeginning)
+ milliseconds);
That should give you an idea of the difference (but run this many times
and average it, and vary the order of the loops). Also, keep in mind
that most of the time, you won't be iterating over a million items.
Bottlenecks can occur in surprising places (though they're often found
in common places too, like Container layout code). Don't try to optimize
things that *seem like* they would be slow without actually confirming
not only that they *are* slow, but that they are affecting the overall
speed or responsiveness of your application. It makes no sense to make a
10x performance improvement in one part of your code that accounts
for .01% of your application's CPU usage.
--
Maciek Sakrejda
Truviso, Inc.
http://www.truviso.com
-Original Message-
From: Cato Paus [EMAIL PROTECTED]
Reply-To: flexcoders@yahoogroups.com
To: flexcoders@yahoogroups.com
Subject: [flexcoders] speed of the for each looping
Date: Tue, 09 Dec 2008 13:28:23 -
Hi, all you experts :)
I'm tying to speed up my application and I use a lot of
exsample
for (var i:int = 0; i 5; i++)
{
trace(i);
}
so is the for each looping faster ?
RE: [flexcoders] speed of the for each looping
For each should be much slower than a basic iterator as it has to walk the
object's properties.
For each (var p:* in someObject)
And
For (var p:String in SomeObject)
Probably run at the same rate.
From: flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Cato
Paus
Sent: Tuesday, December 09, 2008 5:28 AM
To: flexcoders@yahoogroups.com
Subject: [flexcoders] speed of the for each looping
Hi, all you experts :)
I'm tying to speed up my application and I use a lot of
exsample
for (var i:int = 0; i 5; i++)
{
trace(i);
}
so is the for each looping faster ?
RE: [flexcoders] speed of the for each looping
Interesting. I decided to actually try my test above, and on 100
items, the for-each version takes ~50 milliseconds, versus ~25
milliseconds for the explicitly indexed loop. When doing some actual
work in the loop (a trace), the numbers are 41.9 seconds for the
for-each and 41.1 seconds for the indexed for. On a loop with a trace
with 100 items, both forms take ~5 milliseconds. This is rather
unscientific, but I don't have the profiler available (will it ever make
it to Linux, Adobe?).
So yes, it looks like for-each is a lot slower in some cases, but I'll
maintain it still probably won't make a difference unless you've got a
massive loop that does very little, or a deeply nested set of loops.
Consider also the readability and maintainability benefits of a
for-each: unless you need the index, it's just one more place to
introduce bugs when refactoring, and it's cognitive cruft when trying to
follow what's going on.
--
Maciek Sakrejda
Truviso, Inc.
http://www.truviso.com
-Original Message-
From: Alex Harui [EMAIL PROTECTED]
Reply-To: flexcoders@yahoogroups.com
To: flexcoders@yahoogroups.com flexcoders@yahoogroups.com
Subject: RE: [flexcoders] speed of the for each looping
Date: Tue, 9 Dec 2008 12:30:19 -0800
For each should be much slower than a basic iterator as it has to walk
the object’s properties.
For each (var p:* in someObject)
And
For (var p:String in SomeObject)
Probably run at the same rate.
From:flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] On
Behalf Of Cato Paus
Sent: Tuesday, December 09, 2008 5:28 AM
To: flexcoders@yahoogroups.com
Subject: [flexcoders] speed of the for each looping
Hi, all you experts :)
I'm tying to speed up my application and I use a lot of
exsample
for (var i:int = 0; i 5; i++)
{
trace(i);
}
so is the for each looping faster ?
Re: [flexcoders] speed of the for each looping
*nods*
I find that it's often much easier to read when you use for..in and for
each..in rather than regular for. And since you need to have a var current
= list[i] or similar as the first line, If you only need an index to
display, or it's 1-based as opposed to 0-based, using a for [each]..in and
having the first inner line be ++idx will be easier to read than a bunch
of statements within your loop that look like:
var current = foo[i+1]
or
msg = you're at item # + (i + 1)
If you want to know more about for each and how it works (outside of Arrays
at least), look into flash.Proxy. The documentation is a little unclear at
times on Proxy, so I wrote a couple of posts on using it here:
http://flex.joshmcdonald.info/2008/09/using-proxy-class-part-1_04.html
http://flex.joshmcdonald.info/2008/09/using-proxy-class-part-2.html
* IMHO, YMMV, (code) beauty is in the eye of the beholder, etc... =]
-Josh
On Wed, Dec 10, 2008 at 9:37 AM, Maciek Sakrejda [EMAIL PROTECTED]wrote:
Interesting. I decided to actually try my test above, and on 100
items, the for-each version takes ~50 milliseconds, versus ~25
milliseconds for the explicitly indexed loop. When doing some actual
work in the loop (a trace), the numbers are 41.9 seconds for the
for-each and 41.1 seconds for the indexed for. On a loop with a trace
with 100 items, both forms take ~5 milliseconds. This is rather
unscientific, but I don't have the profiler available (will it ever make
it to Linux, Adobe?).
So yes, it looks like for-each is a lot slower in some cases, but I'll
maintain it still probably won't make a difference unless you've got a
massive loop that does very little, or a deeply nested set of loops.
Consider also the readability and maintainability benefits of a
for-each: unless you need the index, it's just one more place to
introduce bugs when refactoring, and it's cognitive cruft when trying to
follow what's going on.
--
Maciek Sakrejda
Truviso, Inc.
http://www.truviso.com
-Original Message-
From: Alex Harui [EMAIL PROTECTED]
Reply-To: flexcoders@yahoogroups.com
To: flexcoders@yahoogroups.com flexcoders@yahoogroups.com
Subject: RE: [flexcoders] speed of the for each looping
Date: Tue, 9 Dec 2008 12:30:19 -0800
For each should be much slower than a basic iterator as it has to walk
the object's properties.
For each (var p:* in someObject)
And
For (var p:String in SomeObject)
Probably run at the same rate.
From:flexcoders@yahoogroups.com [EMAIL PROTECTED][mailto:
[EMAIL PROTECTED] On
Behalf Of Cato Paus
Sent: Tuesday, December 09, 2008 5:28 AM
To: flexcoders@yahoogroups.com
Subject: [flexcoders] speed of the for each looping
Hi, all you experts :)
I'm tying to speed up my application and I use a lot of
exsample
for (var i:int = 0; i 5; i++)
{
trace(i);
}
so is the for each looping faster ?
--
Flexcoders Mailing List
FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
Alternative FAQ location:
https://share.acrobat.com/adc/document.do?docid=942dbdc8-e469-446f-b4cf-1e62079f6847
Search Archives:
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Links
--
Therefore, send not to know For whom the bell tolls. It tolls for thee.
Like the cut of my jib? Check out my Flex blog!
:: Josh 'G-Funk' McDonald
:: 0437 221 380 :: [EMAIL PROTECTED]
:: http://flex.joshmcdonald.info/
:: http://twitter.com/sophistifunk
RE: [flexcoders] speed of the for each looping
They are different animals. Scenarios where you could choose between
index-based or property-based iteration don't come to mind.
Also note property-based iteration can perform much more slowly iterating
proxy-based objects, and do not work on sealed non-dynamic classes.
-Alex
From: flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Josh
McDonald
Sent: Tuesday, December 09, 2008 3:51 PM
To: flexcoders@yahoogroups.com
Subject: Re: [flexcoders] speed of the for each looping
*nods*
I find that it's often much easier to read when you use for..in and for
each..in rather than regular for. And since you need to have a var current =
list[i] or similar as the first line, If you only need an index to display, or
it's 1-based as opposed to 0-based, using a for [each]..in and having the
first inner line be ++idx will be easier to read than a bunch of statements
within your loop that look like:
var current = foo[i+1]
or
msg = you're at item # + (i + 1)
If you want to know more about for each and how it works (outside of Arrays at
least), look into flash.Proxy. The documentation is a little unclear at times
on Proxy, so I wrote a couple of posts on using it here:
http://flex.joshmcdonald.info/2008/09/using-proxy-class-part-1_04.html
http://flex.joshmcdonald.info/2008/09/using-proxy-class-part-2.html
* IMHO, YMMV, (code) beauty is in the eye of the beholder, etc... =]
-Josh
On Wed, Dec 10, 2008 at 9:37 AM, Maciek Sakrejda [EMAIL
PROTECTED]mailto:[EMAIL PROTECTED] wrote:
Interesting. I decided to actually try my test above, and on 100
items, the for-each version takes ~50 milliseconds, versus ~25
milliseconds for the explicitly indexed loop. When doing some actual
work in the loop (a trace), the numbers are 41.9 seconds for the
for-each and 41.1 seconds for the indexed for. On a loop with a trace
with 100 items, both forms take ~5 milliseconds. This is rather
unscientific, but I don't have the profiler available (will it ever make
it to Linux, Adobe?).
So yes, it looks like for-each is a lot slower in some cases, but I'll
maintain it still probably won't make a difference unless you've got a
massive loop that does very little, or a deeply nested set of loops.
Consider also the readability and maintainability benefits of a
for-each: unless you need the index, it's just one more place to
introduce bugs when refactoring, and it's cognitive cruft when trying to
follow what's going on.
--
Maciek Sakrejda
Truviso, Inc.
http://www.truviso.com
-Original Message-
From: Alex Harui [EMAIL PROTECTED]mailto:[EMAIL PROTECTED]
Reply-To: flexcoders@yahoogroups.commailto:flexcoders@yahoogroups.com
To: flexcoders@yahoogroups.commailto:flexcoders@yahoogroups.com
flexcoders@yahoogroups.commailto:flexcoders@yahoogroups.com
Subject: RE: [flexcoders] speed of the for each looping
Date: Tue, 9 Dec 2008 12:30:19 -0800
For each should be much slower than a basic iterator as it has to walk
the object's properties.
For each (var p:* in someObject)
And
For (var p:String in SomeObject)
Probably run at the same rate.
From:flexcoders@yahoogroups.commailto:[EMAIL PROTECTED]
[mailto:flexcoders@yahoogroups.commailto:flexcoders@yahoogroups.com] On
Behalf Of Cato Paus
Sent: Tuesday, December 09, 2008 5:28 AM
To: flexcoders@yahoogroups.commailto:flexcoders@yahoogroups.com
Subject: [flexcoders] speed of the for each looping
Hi, all you experts :)
I'm tying to speed up my application and I use a lot of
exsample
for (var i:int = 0; i 5; i++)
{
trace(i);
}
so is the for each looping faster ?
--
Flexcoders Mailing List
FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
Alternative FAQ location:
https://share.acrobat.com/adc/document.do?docid=942dbdc8-e469-446f-b4cf-1e62079f6847
Search Archives: http://www.mail-archive.com/flexcoders%40yahoogroups.comYahoo!
Groups Links
Individual Email | Traditional
--
Therefore, send not to know For whom the bell tolls. It tolls for thee.
Like the cut of my jib? Check out my Flex blog!
:: Josh 'G-Funk' McDonald
:: 0437 221 380 :: [EMAIL PROTECTED]mailto:[EMAIL PROTECTED]
:: http://flex.joshmcdonald.info/
:: http://twitter.com/sophistifunk
