Status: New
Owner: ----
New issue 293 by sgbeal: Call of member func, even called as non-member,
3-4 times slower than global func
http://code.google.com/p/v8/issues/detail?id=293
Calling two code-identical functions, where one is global scope and one is
a member, requires radically different call times. The member func, even if
it is called without a 'this' object, requires 3-4 times as long to call.
Demonstration code follows. Jump to the bottom and follow the testDF()
call. The point of interest is marked with "HOLY COW".
try
{
undefined === FudgeSystem;
}
catch(e){
FudgeSystem = (function() {
var fudge = {};
fudge.rollDF = function (n) {
if( 0 == arguments.length ) n = 4;
var rc = 0;
var df = function() { return Math.floor( (Math.random() * 1000 %
(3))) - 1; };
for( var i = 0; i < n; ++i )
{
rc += df();
}
return rc;
};
return fudge;
})();
}
// Identical to FudgeSystem.rollDF, but is not a member func:
function rollDF(n) {
if( 0 == arguments.length ) n = 4;
var rc = 0;
var df = function() { return Math.floor( (Math.random() * 1000 % (3)))
- 1; };
for( var i = 0; i < n; ++i )
{
rc += df();
}
return rc;
}
function testDF()
{
var n = 10000;
var dN = 4;
print( new Date() );
print('Rolling',n,'sets of',dN+'dF...');
var func =
FudgeSystem.rollDF; // HOLY COW! This is about 3.5x slower!
//rollDF; // much faster!
for( var i = 0; i < n; ++i )
{
func(dN);
}
print( new Date() );
}
testDF();
Sample output from that program, using both approaches to
calling 'func(dN)':
Member func:
step...@jareth:~/cvs/v8-juice/js-snippets/gaming$ time v8-juice-shell
speed.js
Mon Mar 30 2009 22:48:25 GMT+0200 (CEST)
Rolling 10000 sets of 4dF...
Mon Mar 30 2009 22:48:25 GMT+0200 (CEST)
real 0m0.438s
user 0m0.432s
sys 0m0.008s
Non-member func:
step...@jareth:~/cvs/v8-juice/js-snippets/gaming$ time v8-juice-shell
speed.js
Mon Mar 30 2009 22:48:32 GMT+0200 (CEST)
Rolling 10000 sets of 4dF...
Mon Mar 30 2009 22:48:33 GMT+0200 (CEST)
real 0m1.626s
user 0m1.624s
sys 0m0.000s
i'm on Ubuntu Linux on an i86/32, but i assume that this is a
platform-independent behaviour.
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