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ActionScript 3
Performance
Tuning
Ted Patrick
Flex Evangelist
Adobe Systems
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Overview
Premature Optimization How Flash Player and ActionScript
work
Strong Typing - variables, events, return types
Measuring Performance
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Premature Optimization
More Computing sins are committed in the name of eciencythan any
other reason including blind stupidity W.A. Wulf
Premature Optimization is the root of all evil. - Hoare and
Knuth
Bottlenecks occur in surprising places, so dont try to
second
guess and put in a speed hack until you have proven thats
where the bottleneck is. - Rob Pike
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How Flash Player works
Graphics
Rendering
ActionScript
Execution
ActionScript
Frame & Network
Events
One Frame Cycle
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AVM2 Architecture
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How Flash Player works
Flash Player presents a single thread of execution Flash Player
is multi-threaded!!!
Rendering and ActionScript are executed sequentially.
The player will do everything you ask it to do.
Do to much in one frame cycle a script-timeout occurs.
Defer AS execution to next frame cycle with:
mx.core.UIComponent.callLater()
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Typing optimizes bytecode!
Typing optimizes bytecode!
Typing optimizes bytecode!Typing optimizes bytecode!
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Typing optimizes bytecode!
Typing aects member access. Two Performance Cases for member
access
Strong references are equivalent to C++ member access
Must use dot operator for member
Must use strong typing
Weak references are a hash lookup
No typing
Use of [member] access
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Member Access Examples
instance.x
instance[3]
This stuhappens a lot!!!
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Typing Examples
function a ( o ) // RETURN WEAK
{
return o; // WEAK
}
function b ( o ) // RETURN WEAK{
return o.x; // WEAK
}
function c ( o:Object ) // RETURN WEAK
{
return o.x; // WEAK
}
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Typing Examples
class Base extends Object { var x:int; // STRONG
var y:int; // STRONG
var z; // WEAK
}
function a ( o:Base ) // RETURN WEAK{
return o.z; // WEAK
}
function b ( o:Base ):int // RETURN STRONG
{ return o.x; // STRONG
}
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Typing Examples
dynamic class Base extends Object {
var x:int; // STRONG
var y:int; // STRONG
}
function a ( o:Base ) // RETURN WEAK
{
return o.z; // WEAK
}
function a ( o:Base ):int // RETURN STRONG
{
return o.x; // STRONG
}
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Typing Examples
dynamic class Base extends Object { var x:int; // STRONG
}
class Example extends Base {
var z:int //STRONG
}
function a ( o:Example ):int // RETURN STRONG
{
return o.y; // WEAK
}
function a ( o:Example ):int // RETURN STRONG{
return o.x; // STRONG
}
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Array Member Access
Arrays include fast path for dense portion
Member access is as fast as C++ in dense portion
var a:Array = [1,2,3,4,5];
a[1000] = 2010;
a[1001] = 2011;
a[2]; //FAST PATH
a[1000]; //SLOW PATH
Demo
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Typing with int, uint, Number
Avoid implicit type conversion Math operations can induce type
conversion
Sometimes just using Number is more ecient.
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Strong Typing improves productivity
Simpli
ed debugging Compiler will throw compile-time errors
Code hinting in Flex Builder is based on Strong Typing
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Contact Info
Ted PatrickFlex Evangelist
http://www.onex.org
[email protected]
